Research ArticleStructural Behavior of Thin-Walled Concrete-FilledSteel Tube Used in Cable Tunnel An Experimental andNumerical Investigation

Hetao Hou1 Su Ma1 Bing Qu12 Yanhong Liang1 Yanjun Jin3

Wencan Zhu1 and Lei Chen1

1School of Civil Engineering Shandong University Jinan 250061 China2Department of Civil and Environmental Engineering California Polytechnic State University San Luis Obispo CA 93407 USA3Department of Building Engineering Mianyang Vocational and Technical College Mianyang 621000 China

Correspondence should be addressed to Bing Qu bqucalpolyedu

Received 26 April 2015 Revised 9 June 2015 Accepted 10 June 2015

Academic Editor Robert Cerny

Copyright copy 2015 Hetao Hou et al This is an open access article distributed under the Creative Commons Attribution Licensewhich permits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

One steel grid and five thin-walled concrete-filled steel tubes (CTST) used as the supports of tunnel were tested in site forinvestigating the mechanical behavior The mechanical influences of thickness node form and concrete on CTST were gainedand compared with the impacts on steel grid It is indicated that high antideformation capacity of CTST improved the stability ofsurrounding rock in short time The cementitious grouted sleeve connection exhibited superior flexibility when CTST was erectedand built Although the deformation of rock and soil in the tunnel was increasing good compression resistance was observedby CTST with the new connection type It was also seen that vault tube foot and connections were with larger absolute strainvalues The finite element analysis (FEA) was carried out using ABAQUS program The results were validated by comparison withexperimental results The FE model could be referred by similar projects

1 Introduction

Although steel grid and steel arch are common used struc-tures for tunnel support they are not good enough forlarge deformation control of soft rock As a new structureconcrete-filled steel tubes (CFST) with high bearing capacityand good plasticity have a broad application prospect [1ndash3] Under compressive loading the local buckling resistanceof the steel tube could be effectively enhanced by the filledconcrete At the same time the strength plasticity andtoughness of the concrete can also be boosted [4] Li etal [5] pointed out that deformation of surrounding rockcould be effectively reduced byCFST for roadway supportingHowever the cost of CFST has to be reduced

Compared with ordinary CFST less steel and weldingwork are needed for CTST because of the thin wall Previousresearch mainly focused on the experimental behaviour ofCTST in the laboratory [6ndash8] Despite low cost few studies

are conducted in site to test the influences of wall thicknessand mechanical properties

In this study tests have been done in a cable tunnel inJinan while an FE analysis by ABAQUS program is con-ducted to do further research on the application of CTST intunnel

2 Test program

21 Project Background of Cable Tunnel The cable tunnel islocated in Shunhua Road in Jinan As the tunnel in strongweathered rock it is 145m long The thickness of overlayingsoil of the tunnel is about 67sim8mThemaximum excavationheight is 46m while the largest excavation span is 675mFor presupport advanced small pipes with 15m longitudinaldistance are supplementedThenC25 early-strength concreteis sprayed for primary support Subsequently steel grid orCTST is used to support the tunnel At last C30 waterproof

Hindawi Publishing CorporationAdvances in Materials Science and EngineeringVolume 2015 Article ID 781823 12 pageshttpdxdoiorg1011552015781823

2 Advances in Materials Science and Engineering

Table 1 Parameters of CTST specimens

Specimens ST-1 ST-2 ST-3 ST-4 ST-5119863 (mm) 159 159 159 159 159119905 (mm) 55 45 35 55 55Concrete Filled in Filled in Filled in Not filled in Filled in

Connection Cementitiousgrouted sleeve

Cementitiousgrouted sleeve

Cementitiousgrouted sleeve

Cementitiousgrouted sleeve Ordinary sleeve

Note119863 is the external diameter and 119905 is the thickness

2139

2245

3900

484

1627

1627

6750

Connection 2

Connection 1

484

1942

1942

1089 10892409

L3

R1421

R8293

L3

L2 L2

L1

120601159 times 35(45ndash55)

Figure 1 Size and segmentation of CTST support

concrete with seepage resistance 119875 gt 8 is adopted to improvethe secondary lining

22 Test Specimen In the study the steel tube is segmentedfor installation and transport One end of segment is sealedwhile the other is opened The segment is sealed by precasthead pale once the concrete vibrating finished Finally thesegments are spliced in site According to the results ofgeological exploration the counter-arch for the support isnot set owing to the small effect of soil arch The size andsegmentation of CTST support are shown in Figure 1

5 CTST specimens and 1 steel grid specimen are testedThe details of the test specimens are shown in Figure 2 andTable 1

For the butt joint in the tunnel a new cementitiousgrouted sleeve connection is designed and shown in Figure 3Microexpansive cement mortar is grouted after the con-nection inserting Comparing with the traditional connec-tion the new type with better yielding could satisfy therequirements of surrounding rock pressure Besides the newconnection could reduce the welding works and avoid thetunnel excavation generated by butt joints

According to ldquometallic materials at ambient temperaturetensile test methodrdquo (GBT228-2002) steel tube Q235B isused in the test The yield strength of the steel tube is2553MPa while the tensile strength is 3307MPaThe elasticmodulus is 206 times 105MPa and Poissonrsquos ratio is 030 As whatis shown in Figure 4 the steel tube is bent into the designed

270

270

112060125

112060125

212060125

12060114300

12060114300

12060114300

Figure 2 Steel grid section

Head pale 1

230

20

70

5050 26

0

70

704

CTST

Micro-expansivecement mortar

70

120601159 times 80mm

Rubber mat

120601140 times 20mmHead pale 2120601108 times 80mm

t = 8mm

12060116 hale

12060116 hale

M14

M14

Figure 3 Details of cementitious grouted sleeve connection

shape in the factory and then is stereotyped under cryogeniccooling

The mix proportion of cement sand and gravel usedin the concrete is 1 151 245 The water cement ratio ofthe cement is 041 The expansion agent ratio is 11 Thewater reducing agent ratio is 05 According to the relevant

Advances in Materials Science and Engineering 3

Figure 4 Manufacturing procedure of steel tube in factory

Figure 5 Material test of concrete

Table 2 Compressive strength of concrete at different ages

Age 3 d 7 d 28 dCompressive strength (MPa) 163 248 455

Chinese standards compression tests are carried out asshown in Figure 5 and Table 2 The elastic modulus (Ec) is316 times 104MPa

3 Test Monitoring and Analysis

31 Test Monitoring Program

311 Displacement Monitoring Vault and convergency dis-placement are monitored in the test The settlement value istested with a level and the convergency values are tested witha convergence device

312 Strain Monitoring It is shown in Figure 6 that theresistance strain gauge and fiber are set only on one side of thespecimen for symmetryMeasuring point arrangement can bedivided into the vault area (C1 A1 and S1) the largest cornerarea (C2 S2) the top of the straight wall area (S3 B1) thestraight wall area (A2) and the connection area (from D1 toD4) in which S1simS3 are fiber grating measuring points

313 Pressure Monitoring As what is shown in Figures 7and 8 three pressure gauges (Y1simY3) are set between CTST

1000

A2

D3

D1

D2

D4

B1S3

S2C2

C1A1S1

Figure 6 The location of resistance strain gauge and fiber

1500

Y3

Y2

Y1

3072

Figure 7 The location of pressure gauge

support (or the steel grid support) and surrounding rockThe pressure gauges are tied to the designed position on theoutside surface of the support in site

32 Test Results Analysis

321 Displacement Monitoring Results Analysis The settle-ment-time curves in the vaults and convergency value-timecurves in both sides are shown in Figures 9 and 10 It isobserved that the biggest settlement in the vaults of CTSTwith concrete is less than 5mm while for the one withoutconcrete it is less than 75mm The steel gridrsquos biggestsettlement in the vaults is less than 7mmAll the convergencyvalues in both sides of the supports are less than 18mmThevertical and horizontal deformations of the tunnel are stableafter 10 days so the unobvious deformations in the latter arenot shown in Figure 9

Figures 11 and 12 present load-settlement curves in thevaults and load-convergency value curves in both sides

It is shown in Figure 11 that the curves of ST-1simST-3appeared under the concave due to connection scalability and

4 Advances in Materials Science and Engineering

(a) The colligation of the pressure monitor (b) Read the pressure monitor in situ

Figure 8 Pressure measurement in situ

0 2Time (d)

4 6 8 10 12

1

2

3

4

5

6

7

8

ST-1ST-2ST-3

ST-4ST-5GS

Settl

emen

t (m

m)

Figure 9 Settlement-time curves in the vaults

0 2 4 6 8 10 12

02

04

06

08

10

12

14

16

18

Time (d)

Con

verg

ency

val

ue (m

m)

ST-1ST-2ST-3

ST-4ST-5GS

Figure 10 Convergency value-time curves in both sides

Advances in Materials Science and Engineering 5

0 1 2 3 4 5 6 7 8

10

20

30

40

50

60

70

80

90

100

Settlement (mm)

Load

(kN

)

ST-1ST-2ST-3

ST-4ST-5GS

Figure 11 Load-settlement curves in the vaults

02 04 06 08 10 12 14 160

10

20

30

40

50

60

70

80

90

100

Convergency value (mm)

Load

(kN

)

ST-1ST-2ST-3

ST-4ST-5GS

Figure 12 Load-convergency value curves in both sides

smaller gap between surrounding rock and support when theload is less than 10 kN In the later elastic stage the largestvertical deformation is 25sim45mm The curve of ST-4 withnew connection has no obvious concave It may be becauseof the faster deformation and the shorter time of connectioncompression and gap pressure for CTST without concreteThe curves of ST-5 with common connection and steel griddid not appear under the concave It can be seen that themaincause of the concave is connection scalability The straightline slope of ST-1 is bigger than that of ST-5 which presents

that the new connection has better resistance to deformationFrom the gradually decreasing straight line slopes of ST-1simST-3 it could be concluded that the vertical deformationdecreased as the steel thickness enlarged

It is indicated in Figure 12 that the horizontal deformationof steel grid is less than what happened in CTST under thesame load It might be that the bottom of steel grid is linkedto counter-arch making horizontal stiffness of the supportincrease Meanwhile the higher steel ratio and concreteinside the support would lead to larger stiffness

6 Advances in Materials Science and Engineering

0 40 80 120 160 2000

5

10

15

20

25

30

35

40

45

50Lo

ad (k

Nm

)

(120583120576)

ST-1ST-2ST-3

ST-4ST-5

(a) C1

4000

5

10

15

20

25

30

35

40

45

50

Load

(kN

m)

(120583120576)

ST-1ST-2ST-3

ST-4ST-5

minus40minus80minus120

(b) C2

00

5

10

15

20

25

30

35

40

45

50

Load

(kN

m)

(120583120576)

ST-1ST-2ST-3

ST-4ST-5

minus40minus80minus120minus160minus200

(c) S3

Figure 13 Load-strain curves in the outer edge of the CTST supports

322 Strain Monitoring Results Analysis In this study tan-gential strains of 5 CTST supports are mainly monitored

(1) Strain Curves of the Outer Edge It is indicated in Figure 13that each curve in addition toC2 in the ST-2 support is almosta straight line which suggests that the specimen performedlinear elastic as awholeThe slope of ST-2 in the largest cornerchanges from positive to negative It may be caused by steeltube defect or the local stress concentration by concrete insidefilling the gap The support vault of the outer edge (C1) is inthe tensile force While both the largest corner (C2) and thetop of the straight wall (S3) are in the compressive force theabsolute values of maximum tensile and compressive strains

are less than 200 120583120576 Each strain of ST-4 is bigger than ST-3which means that the steel tube with concrete filling couldeffectively improve the ability of resisting deformation

(2) Strain Curves of the Center Axis It is described in Figure 14that both the vault (A1) and the straight wall (A2) are in thecompressive force with the absolute strain values less than200120583120576 Each load-strain curve is almost a straight line

(3) Strain Curves of the Inner Edge It could be seen inFigure 15 that each load-strain curve of the inner edge ofCTST supports is also almost a straight lineThe vault (S1) thelargest corner (S2) and the top of the straight wall (B1) are in

Advances in Materials Science and Engineering 7

0

5

10

15

20

25

30

35

40

45

50

Load

(kN

m)

0(120583120576)

minus40minus60minus80minus100 minus20

ST-1ST-2ST-3

ST-4ST-5

(a) A1

0

5

10

15

20

25

30

35

40

45

50

Load

(kN

m)

0(120583120576)

minus40 minus20minus60minus100 minus80minus120minus140minus160minus180minus200

ST-1ST-2ST-3

ST-4ST-5

(b) A2

Figure 14 Load-strain curves on the center axis of the CTST supports

the compressive force with the absolute strain values less than275120583120576 The specimens performed elastic The steel thicknessand the style of connection cannot influence the load-straincurve in the inner edge obviously

(4) StrainCurves of the Connections As displayed in Figure 16load-strain curves in the inner edge of the CTST supportshave obvious properties The curves of supports with cemen-titious grouted sleeve (ST-1simST-4) can be roughly dividedinto flat part and growing part Early strain grows faster thanthe load which means that the cementitious grouted sleeveconnection exhibits superior flexibility The curve of supportwith common sleeve (ST-5) has no obvious flat part reflectingits connection with bigger stiffness All the absolute values ofmaximum tensile and compressive strains at the connectionsare less than 250120583120576

(5) Strain Distribution Curves of the Inner and Outer EdgesOwing to symmetry of CTST supports the strain distributioncurves are tested only on the left side of the support Themaximum strain distributions of the inner and outer edge ofthe supports are shown in Figures 17 and 18

It is obvious that the tensile strain was gradually trans-formed into compressive strain along the direction of vault tothe straight wall in the outer edge All the straight walls arein compression The maximum tensile strain of outer edge islocated in the vaults while the maximum compressive strainis generated near the lower connection The inner edges ofthe CTST supports are all in compression with the maximumstrain in the vaults But the maximum compressive strain ofST-5 is located near the lower connection The compressivestrain values of vault foot and area near the lower connectionare relatively larger

4 Numerical Analysis

41 The Finite Element Modeling The finite element analysis(FEA) of ST-1simST-3 by ABAQUS program is conductedFour-noded shell element with reduced integration (S4R) isused for steel tube Von-Mises kinematic hardening rule isadopted for steel material The elasticity modulus of steeltakes 206GPa Poissonrsquos ratio takes 030

The three-dimensional 8-noded solid element withreduced integration (C3D8R) is used to mesh the concreteThe elasticity modulus takes 4730radic1198911015840

119888 1198911015840119888mean compression

cylindrical strength of concrete Poissonrsquos ratio takes 020The interface behavior in the tangential direction employs theCoulomb friction model

Considering the influences of surrounding rocks at thescope of 5 times the width the spacing of support (05m) wastaken as the width of surrounding rock Considering that themid-separate wall was established between CTST supportsin the experiment which could affect the force situationa vertical constraint was added at both sides in the outeredges of the concrete lining Only 12 model is needed whencalculation according to the structure symmetry as shown inFigure 19

In this test the displacement values were taken as the loadto apply to the supports and the FEA results were comparedwith the testing results

42 FEA Results and Contrastive Analysis Based on the FEMresults the maximum strain distribution curves of the innerand outer edge of ST-1simST-3 are shown in Figures 20 and21 Table 3 describes the comparison of the maximal strainbetween FEA and test results

8 Advances in Materials Science and Engineering

0

5

10

15

20

25

30

35

40

45

50

Load

(kN

m)

0(120583120576)

minus25minus50minus75minus100minus125minus150minus175minus200minus225minus250minus275

ST-1ST-2ST-3

ST-4ST-5

(a) S1

0

5

10

15

20

25

30

35

40

45

50

Load

(kN

m)

0(120583120576)

minus25minus50minus75minus100minus125minus150minus175minus200minus225minus250

ST-1ST-2ST-3

ST-4ST-5

(b) S2

0

5

10

15

20

25

30

35

40

45

50

Load

(kN

m)

0(120583120576)

minus25minus50minus75minus100minus125minus150minus175minus200minus225minus250

ST-1ST-2ST-3

ST-4ST-5

(c) B1

Figure 15 Load-strain curves in the inner edge of the CTST supports

From Table 3 it is observed that the maximum straindistribution curves of the FEA results are in good agreementwith the experimental results The average error rate of eachmeasuring point (vault largest corner top of the straight walland foot) in the outer edge is 64 71 55 and 72respectively The average error rate of each measuring point(vault largest corner top of the straight wall and foot) inthe inner edge is 60 30 62 and 61 respectivelyThe maximum error of all measuring points is 102 Itmay be caused by less number of horizontal and verticalmeasuring points as a result of some differences betweenthe displacement load applied on the model and the realdisplacement Comparing with the experimental data it isobserved that the FEM adopted in this section is reasonable

which can be well simulated with the working condition ofCTST supports in tunnel and can be used for the structuralanalysis of the similar projects

5 Conclusions

In line with the results of the experimental study and FEAanalysis the results could be summarized as follows

(1) With better compression resistance CTST benefitsto resist against the deformation of the tunnel Thedeformation of tunnels with CTST can reach thesteady state in a short time

Advances in Materials Science and Engineering 9

0 50 100 150 2000

5

10

15

20

25

30

35

40

45

50

Load

(kN

m)

(120583120576)

ST-1ST-2ST-3

ST-4ST-5

(a) D1

0

5

10

15

20

25

30

35

40

45

50

Load

(kN

m)

(120583120576)

ST-1ST-2ST-3

ST-4ST-5

0minus50minus100minus150minus200minus250

(b) D2

(120583120576)

ST-1ST-2ST-3

ST-4ST-5

0minus50minus100minus150minus250 minus2000

5

10

15

20

25

30

35

40

45

50

Load

(kN

m)

(c) D3

0

5

10

15

20

25

30

35

40

45

50

Load

(kN

m)

(120583120576)

ST-1ST-2ST-3

ST-4ST-5

0minus50minus100minus150minus250 minus200

(d) D4

Figure 16 Load-strain curves at the connections of the CTST supports

ST-1 ST-2 ST-3 ST-4 ST-5

1172 1242 1284 1313 2003 18521795 17621758 1797

minus1229 minus929 minus1253 minus1412minus1463

minus1974minus1885

minus963

minus1905minus1873

minus1062

minus1995minus1942

minus1037

minus1495minus145

minus663

minus1795minus175

minus97

Figure 17 Strain distribution curves in the outer edge of the CTST supports

10 Advances in Materials Science and Engineering

ST-1 ST-2 ST-3 ST-4 ST-5

minus2134 minus1645 minus2175 minus2237 minus2361

minus2302minus2285

minus2315

minus2465 minus238

minus1796minus1555

minus1935

minus2059 minus2503

minus1964

minus1499

minus1758

minus1883minus2243

minus1396

minus1094

minus1285

minus1785minus192

minus2095

minus1562

minus1881

minus1956 minus2408

Figure 18 Strain distribution curves in the inner edge of the CTST supports

(a) The whole mesh of tunnel

X

Y

Z

(b) Lining and supportmesh

Figure 19 Mesh of steel tube model

ST-1 ST-2 ST-3

1853 1348 1434

minus1337

minus1858

minus108

minus989

minus133

minus722

minus1354

minus1912

minus1034

Figure 20 Strain distribution curves in the outer edge of the CTST supports

ST-1 ST-2 ST-3

minus2303

minus1003

minus1479

minus1913 minus2473

minus1854

minus1447

minus2337minus1714

minus1474

minus2153

minus2527

Figure 21 Strain distribution curves in the inner edge of the CTST supports

Advances in Materials Science and Engineering 11

Table3Com

paris

onof

them

axim

alstr

ainbetweenFE

Aandtestresults

Locatio

nSpecim

enST

-1ST

-2ST

-3120576

119879120576

FEM(|120576

FEMminus120576

119879|120576

FEM)times100120576

119879120576

FEM(|120576

FEMminus120576

119879|120576

FEM)times100120576

119879120576

FEM(|120576

FEMminus120576

119879|120576

FEM)times100

Theo

uter

edge

Vault

1797

1853

30

1242

1348

79

1313

1434

84

Largestcorner

minus97minus108

102

minus663minus722

82

minus1037minus1034

30

Topof

thes

traightw

allminus175minus1858

58

minus145minus133

90

minus1942minus1912

16

Foot

minus1229minus1337

81

minus929minus989

61

minus1253minus1354

75

Theinn

eredge

Vault

minus2408minus2527

47

minus192minus1913

40

minus2243minus2473

93

Largestcornerminus1881minus2153

26

minus1285minus1479

13

minus1758minus1854

52

Topof

thes

traightw

allminus1562minus1474

60

minus1094minus1003

91

minus1499minus1447

36

Foot

minus2134minus2303

73

minus1645minus1714

40

minus2175minus2337

69

Note120576119879means

them

axim

umstr

ainvalueo

fexp

erim

entand120576FE

Mmeans

them

axim

umstr

ainvalueo

fFEM

Tensiles

trainispo

sitivecompressiv

estrainisnegativ

e

12 Advances in Materials Science and Engineering

(2) All of the CTST supports perform elastic duringthe experiment The higher steel ratio and concreteinside the larger stiffness of CTST obtained

(3) The cementitious grouted sleeve connection withsuperior flexibility exhibits better resistance to defor-mation

(4) The tensile strain is gradually transformed into com-pressive strain along the direction of vault to thefoot in the outer edge The inner edges of the CTSTsupports are all in compression The absolute strainvalues of vault connections and tube foot are larger

(5) The mechanical behaviors of CTST supports in thetunnel are analyzed with ABAQUS software packageThe analysis results agree well with the test resultsThe maximum error is 102 The model and theparameters chosen are relatively reasonable and couldbe used for the structural analysis of the similarsupporting projects

Conflict of Interests

The authors declare that they have no conflict of interests

References

[1] M Elchalakani and X-L Zhao ldquoConcrete-filled cold-formedcircular steel tubes subjected to variable amplitude cyclic purebendingrdquo Engineering Structures vol 30 no 2 pp 287ndash2992008

[2] M V Chitawadagi and M C Narasimhan ldquoStrength deforma-tion behaviour of circular concrete filled steel tubes subjected topure bendingrdquo Journal of Constructional Steel Research vol 65no 8-9 pp 1836ndash1845 2009

[3] Y-F An C Roeder and L-H Han ldquoFlexural performanceof concrete-encased concrete-filled steel tubesrdquo Magazine ofConcrete Research vol 66 no 5-6 pp 249ndash267 2014

[4] L-H Han S-H He and F-Y Liao ldquoPerformance and calcula-tions of concrete filled steel tubes (CFST) under axial tensionrdquoJournal of Constructional Steel Research vol 67 no 11 pp 1699ndash1709 2011

[5] W Li Q Wang D Wang et al ldquoExperimental study on shortcolumns under axial load of U-type confined concrete archcentering and its application in minerdquo Journal of Mining ampSafety Engineering vol 31 no 1 pp 1ndash9 2014 (Chinese)

[6] A-Y Jiang J Chen and W-L Jin ldquoExperimental investigationand design of thin-walled concrete-filled steel tubes subject tobendingrdquoThin-Walled Structures vol 63 pp 44ndash50 2013

[7] B Uy ldquoStrength of concrete filled steel box columns incorporat-ing local bucklingrdquo Journal of Structural Engineering vol 126no 3 pp 341ndash352 2000

[8] M Mursi and B Uy ldquoStrength of concrete filled steel boxcolumns incorporating interaction bucklingrdquo Journal of Struc-tural Engineering vol 129 no 5 pp 626ndash639 2003

Submit your manuscripts athttpwwwhindawicom

ScientificaHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

CorrosionInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Polymer ScienceInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

CeramicsJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

CompositesJournal of

NanoparticlesJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

International Journal of

Biomaterials

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

NanoscienceJournal of

TextilesHindawi Publishing Corporation httpwwwhindawicom Volume 2014

Journal of

NanotechnologyHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal of

CrystallographyJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

CoatingsJournal of

Advances in

Materials Science and EngineeringHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Smart Materials Research

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

MetallurgyJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

BioMed Research International

MaterialsJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Nano

materials

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal ofNanomaterials

2 Advances in Materials Science and Engineering

Table 1 Parameters of CTST specimens

Specimens ST-1 ST-2 ST-3 ST-4 ST-5119863 (mm) 159 159 159 159 159119905 (mm) 55 45 35 55 55Concrete Filled in Filled in Filled in Not filled in Filled in

Connection Cementitiousgrouted sleeve

Cementitiousgrouted sleeve

Cementitiousgrouted sleeve

Cementitiousgrouted sleeve Ordinary sleeve

Note119863 is the external diameter and 119905 is the thickness

2139

2245

3900

484

1627

1627

6750

Connection 2

Connection 1

484

1942

1942

1089 10892409

L3

R1421

R8293

L3

L2 L2

L1

120601159 times 35(45ndash55)

Figure 1 Size and segmentation of CTST support

concrete with seepage resistance 119875 gt 8 is adopted to improvethe secondary lining

22 Test Specimen In the study the steel tube is segmentedfor installation and transport One end of segment is sealedwhile the other is opened The segment is sealed by precasthead pale once the concrete vibrating finished Finally thesegments are spliced in site According to the results ofgeological exploration the counter-arch for the support isnot set owing to the small effect of soil arch The size andsegmentation of CTST support are shown in Figure 1

5 CTST specimens and 1 steel grid specimen are testedThe details of the test specimens are shown in Figure 2 andTable 1

For the butt joint in the tunnel a new cementitiousgrouted sleeve connection is designed and shown in Figure 3Microexpansive cement mortar is grouted after the con-nection inserting Comparing with the traditional connec-tion the new type with better yielding could satisfy therequirements of surrounding rock pressure Besides the newconnection could reduce the welding works and avoid thetunnel excavation generated by butt joints

According to ldquometallic materials at ambient temperaturetensile test methodrdquo (GBT228-2002) steel tube Q235B isused in the test The yield strength of the steel tube is2553MPa while the tensile strength is 3307MPaThe elasticmodulus is 206 times 105MPa and Poissonrsquos ratio is 030 As whatis shown in Figure 4 the steel tube is bent into the designed

270

270

112060125

112060125

212060125

12060114300

12060114300

12060114300

Figure 2 Steel grid section

Head pale 1

230

20

70

5050 26

0

70

704

CTST

Micro-expansivecement mortar

70

120601159 times 80mm

Rubber mat

120601140 times 20mmHead pale 2120601108 times 80mm

t = 8mm

12060116 hale

12060116 hale

M14

M14

Figure 3 Details of cementitious grouted sleeve connection

shape in the factory and then is stereotyped under cryogeniccooling

The mix proportion of cement sand and gravel usedin the concrete is 1 151 245 The water cement ratio ofthe cement is 041 The expansion agent ratio is 11 Thewater reducing agent ratio is 05 According to the relevant

Advances in Materials Science and Engineering 3

Figure 4 Manufacturing procedure of steel tube in factory

Figure 5 Material test of concrete

Table 2 Compressive strength of concrete at different ages

Age 3 d 7 d 28 dCompressive strength (MPa) 163 248 455

Chinese standards compression tests are carried out asshown in Figure 5 and Table 2 The elastic modulus (Ec) is316 times 104MPa

3 Test Monitoring and Analysis

31 Test Monitoring Program

311 Displacement Monitoring Vault and convergency dis-placement are monitored in the test The settlement value istested with a level and the convergency values are tested witha convergence device

312 Strain Monitoring It is shown in Figure 6 that theresistance strain gauge and fiber are set only on one side of thespecimen for symmetryMeasuring point arrangement can bedivided into the vault area (C1 A1 and S1) the largest cornerarea (C2 S2) the top of the straight wall area (S3 B1) thestraight wall area (A2) and the connection area (from D1 toD4) in which S1simS3 are fiber grating measuring points

313 Pressure Monitoring As what is shown in Figures 7and 8 three pressure gauges (Y1simY3) are set between CTST

1000

A2

D3

D1

D2

D4

B1S3

S2C2

C1A1S1

Figure 6 The location of resistance strain gauge and fiber

1500

Y3

Y2

Y1

3072

Figure 7 The location of pressure gauge

support (or the steel grid support) and surrounding rockThe pressure gauges are tied to the designed position on theoutside surface of the support in site

32 Test Results Analysis

321 Displacement Monitoring Results Analysis The settle-ment-time curves in the vaults and convergency value-timecurves in both sides are shown in Figures 9 and 10 It isobserved that the biggest settlement in the vaults of CTSTwith concrete is less than 5mm while for the one withoutconcrete it is less than 75mm The steel gridrsquos biggestsettlement in the vaults is less than 7mmAll the convergencyvalues in both sides of the supports are less than 18mmThevertical and horizontal deformations of the tunnel are stableafter 10 days so the unobvious deformations in the latter arenot shown in Figure 9

Figures 11 and 12 present load-settlement curves in thevaults and load-convergency value curves in both sides

It is shown in Figure 11 that the curves of ST-1simST-3appeared under the concave due to connection scalability and

4 Advances in Materials Science and Engineering

(a) The colligation of the pressure monitor (b) Read the pressure monitor in situ

Figure 8 Pressure measurement in situ

0 2Time (d)

4 6 8 10 12

1

2

3

4

5

6

7

8

ST-1ST-2ST-3

ST-4ST-5GS

Settl

emen

t (m

m)

Figure 9 Settlement-time curves in the vaults

0 2 4 6 8 10 12

02

04

06

08

10

12

14

16

18

Time (d)

Con

verg

ency

val

ue (m

m)

ST-1ST-2ST-3

ST-4ST-5GS

Figure 10 Convergency value-time curves in both sides

Advances in Materials Science and Engineering 5

0 1 2 3 4 5 6 7 8

10

20

30

40

50

60

70

80

90

100

Settlement (mm)

Load

(kN

)

ST-1ST-2ST-3

ST-4ST-5GS

Figure 11 Load-settlement curves in the vaults

02 04 06 08 10 12 14 160

10

20

30

40

50

60

70

80

90

100

Convergency value (mm)

Load

(kN

)

ST-1ST-2ST-3

ST-4ST-5GS

Figure 12 Load-convergency value curves in both sides

smaller gap between surrounding rock and support when theload is less than 10 kN In the later elastic stage the largestvertical deformation is 25sim45mm The curve of ST-4 withnew connection has no obvious concave It may be becauseof the faster deformation and the shorter time of connectioncompression and gap pressure for CTST without concreteThe curves of ST-5 with common connection and steel griddid not appear under the concave It can be seen that themaincause of the concave is connection scalability The straightline slope of ST-1 is bigger than that of ST-5 which presents

that the new connection has better resistance to deformationFrom the gradually decreasing straight line slopes of ST-1simST-3 it could be concluded that the vertical deformationdecreased as the steel thickness enlarged

It is indicated in Figure 12 that the horizontal deformationof steel grid is less than what happened in CTST under thesame load It might be that the bottom of steel grid is linkedto counter-arch making horizontal stiffness of the supportincrease Meanwhile the higher steel ratio and concreteinside the support would lead to larger stiffness

6 Advances in Materials Science and Engineering

0 40 80 120 160 2000

5

10

15

20

25

30

35

40

45

50Lo

ad (k

Nm

)

(120583120576)

ST-1ST-2ST-3

ST-4ST-5

(a) C1

4000

5

10

15

20

25

30

35

40

45

50

Load

(kN

m)

(120583120576)

ST-1ST-2ST-3

ST-4ST-5

minus40minus80minus120

(b) C2

00

5

10

15

20

25

30

35

40

45

50

Load

(kN

m)

(120583120576)

ST-1ST-2ST-3

ST-4ST-5

minus40minus80minus120minus160minus200

(c) S3

Figure 13 Load-strain curves in the outer edge of the CTST supports

322 Strain Monitoring Results Analysis In this study tan-gential strains of 5 CTST supports are mainly monitored

(1) Strain Curves of the Outer Edge It is indicated in Figure 13that each curve in addition toC2 in the ST-2 support is almosta straight line which suggests that the specimen performedlinear elastic as awholeThe slope of ST-2 in the largest cornerchanges from positive to negative It may be caused by steeltube defect or the local stress concentration by concrete insidefilling the gap The support vault of the outer edge (C1) is inthe tensile force While both the largest corner (C2) and thetop of the straight wall (S3) are in the compressive force theabsolute values of maximum tensile and compressive strains

are less than 200 120583120576 Each strain of ST-4 is bigger than ST-3which means that the steel tube with concrete filling couldeffectively improve the ability of resisting deformation

(2) Strain Curves of the Center Axis It is described in Figure 14that both the vault (A1) and the straight wall (A2) are in thecompressive force with the absolute strain values less than200120583120576 Each load-strain curve is almost a straight line

(3) Strain Curves of the Inner Edge It could be seen inFigure 15 that each load-strain curve of the inner edge ofCTST supports is also almost a straight lineThe vault (S1) thelargest corner (S2) and the top of the straight wall (B1) are in

Advances in Materials Science and Engineering 7

0

5

10

15

20

25

30

35

40

45

50

Load

(kN

m)

0(120583120576)

minus40minus60minus80minus100 minus20

ST-1ST-2ST-3

ST-4ST-5

(a) A1

0

5

10

15

20

25

30

35

40

45

50

Load

(kN

m)

0(120583120576)

minus40 minus20minus60minus100 minus80minus120minus140minus160minus180minus200

ST-1ST-2ST-3

ST-4ST-5

(b) A2

Figure 14 Load-strain curves on the center axis of the CTST supports

the compressive force with the absolute strain values less than275120583120576 The specimens performed elastic The steel thicknessand the style of connection cannot influence the load-straincurve in the inner edge obviously

(4) StrainCurves of the Connections As displayed in Figure 16load-strain curves in the inner edge of the CTST supportshave obvious properties The curves of supports with cemen-titious grouted sleeve (ST-1simST-4) can be roughly dividedinto flat part and growing part Early strain grows faster thanthe load which means that the cementitious grouted sleeveconnection exhibits superior flexibility The curve of supportwith common sleeve (ST-5) has no obvious flat part reflectingits connection with bigger stiffness All the absolute values ofmaximum tensile and compressive strains at the connectionsare less than 250120583120576

(5) Strain Distribution Curves of the Inner and Outer EdgesOwing to symmetry of CTST supports the strain distributioncurves are tested only on the left side of the support Themaximum strain distributions of the inner and outer edge ofthe supports are shown in Figures 17 and 18

It is obvious that the tensile strain was gradually trans-formed into compressive strain along the direction of vault tothe straight wall in the outer edge All the straight walls arein compression The maximum tensile strain of outer edge islocated in the vaults while the maximum compressive strainis generated near the lower connection The inner edges ofthe CTST supports are all in compression with the maximumstrain in the vaults But the maximum compressive strain ofST-5 is located near the lower connection The compressivestrain values of vault foot and area near the lower connectionare relatively larger

4 Numerical Analysis

41 The Finite Element Modeling The finite element analysis(FEA) of ST-1simST-3 by ABAQUS program is conductedFour-noded shell element with reduced integration (S4R) isused for steel tube Von-Mises kinematic hardening rule isadopted for steel material The elasticity modulus of steeltakes 206GPa Poissonrsquos ratio takes 030

The three-dimensional 8-noded solid element withreduced integration (C3D8R) is used to mesh the concreteThe elasticity modulus takes 4730radic1198911015840

119888 1198911015840119888mean compression

cylindrical strength of concrete Poissonrsquos ratio takes 020The interface behavior in the tangential direction employs theCoulomb friction model

Considering the influences of surrounding rocks at thescope of 5 times the width the spacing of support (05m) wastaken as the width of surrounding rock Considering that themid-separate wall was established between CTST supportsin the experiment which could affect the force situationa vertical constraint was added at both sides in the outeredges of the concrete lining Only 12 model is needed whencalculation according to the structure symmetry as shown inFigure 19

In this test the displacement values were taken as the loadto apply to the supports and the FEA results were comparedwith the testing results

42 FEA Results and Contrastive Analysis Based on the FEMresults the maximum strain distribution curves of the innerand outer edge of ST-1simST-3 are shown in Figures 20 and21 Table 3 describes the comparison of the maximal strainbetween FEA and test results

8 Advances in Materials Science and Engineering

0

5

10

15

20

25

30

35

40

45

50

Load

(kN

m)

0(120583120576)

minus25minus50minus75minus100minus125minus150minus175minus200minus225minus250minus275

ST-1ST-2ST-3

ST-4ST-5

(a) S1

0

5

10

15

20

25

30

35

40

45

50

Load

(kN

m)

0(120583120576)

minus25minus50minus75minus100minus125minus150minus175minus200minus225minus250

ST-1ST-2ST-3

ST-4ST-5

(b) S2

0

5

10

15

20

25

30

35

40

45

50

Load

(kN

m)

0(120583120576)

minus25minus50minus75minus100minus125minus150minus175minus200minus225minus250

ST-1ST-2ST-3

ST-4ST-5

(c) B1

Figure 15 Load-strain curves in the inner edge of the CTST supports

From Table 3 it is observed that the maximum straindistribution curves of the FEA results are in good agreementwith the experimental results The average error rate of eachmeasuring point (vault largest corner top of the straight walland foot) in the outer edge is 64 71 55 and 72respectively The average error rate of each measuring point(vault largest corner top of the straight wall and foot) inthe inner edge is 60 30 62 and 61 respectivelyThe maximum error of all measuring points is 102 Itmay be caused by less number of horizontal and verticalmeasuring points as a result of some differences betweenthe displacement load applied on the model and the realdisplacement Comparing with the experimental data it isobserved that the FEM adopted in this section is reasonable

which can be well simulated with the working condition ofCTST supports in tunnel and can be used for the structuralanalysis of the similar projects

5 Conclusions

In line with the results of the experimental study and FEAanalysis the results could be summarized as follows

(1) With better compression resistance CTST benefitsto resist against the deformation of the tunnel Thedeformation of tunnels with CTST can reach thesteady state in a short time

Advances in Materials Science and Engineering 9

0 50 100 150 2000

5

10

15

20

25

30

35

40

45

50

Load

(kN

m)

(120583120576)

ST-1ST-2ST-3

ST-4ST-5

(a) D1

0

5

10

15

20

25

30

35

40

45

50

Load

(kN

m)

(120583120576)

ST-1ST-2ST-3

ST-4ST-5

0minus50minus100minus150minus200minus250

(b) D2

(120583120576)

ST-1ST-2ST-3

ST-4ST-5

0minus50minus100minus150minus250 minus2000

5

10

15

20

25

30

35

40

45

50

Load

(kN

m)

(c) D3

0

5

10

15

20

25

30

35

40

45

50

Load

(kN

m)

(120583120576)

ST-1ST-2ST-3

ST-4ST-5

0minus50minus100minus150minus250 minus200

(d) D4

Figure 16 Load-strain curves at the connections of the CTST supports

ST-1 ST-2 ST-3 ST-4 ST-5

1172 1242 1284 1313 2003 18521795 17621758 1797

minus1229 minus929 minus1253 minus1412minus1463

minus1974minus1885

minus963

minus1905minus1873

minus1062

minus1995minus1942

minus1037

minus1495minus145

minus663

minus1795minus175

minus97

Figure 17 Strain distribution curves in the outer edge of the CTST supports

10 Advances in Materials Science and Engineering

ST-1 ST-2 ST-3 ST-4 ST-5

minus2134 minus1645 minus2175 minus2237 minus2361

minus2302minus2285

minus2315

minus2465 minus238

minus1796minus1555

minus1935

minus2059 minus2503

minus1964

minus1499

minus1758

minus1883minus2243

minus1396

minus1094

minus1285

minus1785minus192

minus2095

minus1562

minus1881

minus1956 minus2408

Figure 18 Strain distribution curves in the inner edge of the CTST supports

(a) The whole mesh of tunnel

X

Y

Z

(b) Lining and supportmesh

Figure 19 Mesh of steel tube model

ST-1 ST-2 ST-3

1853 1348 1434

minus1337

minus1858

minus108

minus989

minus133

minus722

minus1354

minus1912

minus1034

Figure 20 Strain distribution curves in the outer edge of the CTST supports

ST-1 ST-2 ST-3

minus2303

minus1003

minus1479

minus1913 minus2473

minus1854

minus1447

minus2337minus1714

minus1474

minus2153

minus2527

Figure 21 Strain distribution curves in the inner edge of the CTST supports

Advances in Materials Science and Engineering 11

Table3Com

paris

onof

them

axim

alstr

ainbetweenFE

Aandtestresults

Locatio

nSpecim

enST

-1ST

-2ST

-3120576

119879120576

FEM(|120576

FEMminus120576

119879|120576

FEM)times100120576

119879120576

FEM(|120576

FEMminus120576

119879|120576

FEM)times100120576

119879120576

FEM(|120576

FEMminus120576

119879|120576

FEM)times100

Theo

uter

edge

Vault

1797

1853

30

1242

1348

79

1313

1434

84

Largestcorner

minus97minus108

102

minus663minus722

82

minus1037minus1034

30

Topof

thes

traightw

allminus175minus1858

58

minus145minus133

90

minus1942minus1912

16

Foot

minus1229minus1337

81

minus929minus989

61

minus1253minus1354

75

Theinn

eredge

Vault

minus2408minus2527

47

minus192minus1913

40

minus2243minus2473

93

Largestcornerminus1881minus2153

26

minus1285minus1479

13

minus1758minus1854

52

Topof

thes

traightw

allminus1562minus1474

60

minus1094minus1003

91

minus1499minus1447

36

Foot

minus2134minus2303

73

minus1645minus1714

40

minus2175minus2337

69

Note120576119879means

them

axim

umstr

ainvalueo

fexp

erim

entand120576FE

Mmeans

them

axim

umstr

ainvalueo

fFEM

Tensiles

trainispo

sitivecompressiv

estrainisnegativ

e

12 Advances in Materials Science and Engineering

(2) All of the CTST supports perform elastic duringthe experiment The higher steel ratio and concreteinside the larger stiffness of CTST obtained

(3) The cementitious grouted sleeve connection withsuperior flexibility exhibits better resistance to defor-mation

(4) The tensile strain is gradually transformed into com-pressive strain along the direction of vault to thefoot in the outer edge The inner edges of the CTSTsupports are all in compression The absolute strainvalues of vault connections and tube foot are larger

(5) The mechanical behaviors of CTST supports in thetunnel are analyzed with ABAQUS software packageThe analysis results agree well with the test resultsThe maximum error is 102 The model and theparameters chosen are relatively reasonable and couldbe used for the structural analysis of the similarsupporting projects

Conflict of Interests

The authors declare that they have no conflict of interests

References

[1] M Elchalakani and X-L Zhao ldquoConcrete-filled cold-formedcircular steel tubes subjected to variable amplitude cyclic purebendingrdquo Engineering Structures vol 30 no 2 pp 287ndash2992008

[2] M V Chitawadagi and M C Narasimhan ldquoStrength deforma-tion behaviour of circular concrete filled steel tubes subjected topure bendingrdquo Journal of Constructional Steel Research vol 65no 8-9 pp 1836ndash1845 2009

[3] Y-F An C Roeder and L-H Han ldquoFlexural performanceof concrete-encased concrete-filled steel tubesrdquo Magazine ofConcrete Research vol 66 no 5-6 pp 249ndash267 2014

[4] L-H Han S-H He and F-Y Liao ldquoPerformance and calcula-tions of concrete filled steel tubes (CFST) under axial tensionrdquoJournal of Constructional Steel Research vol 67 no 11 pp 1699ndash1709 2011

[5] W Li Q Wang D Wang et al ldquoExperimental study on shortcolumns under axial load of U-type confined concrete archcentering and its application in minerdquo Journal of Mining ampSafety Engineering vol 31 no 1 pp 1ndash9 2014 (Chinese)

[6] A-Y Jiang J Chen and W-L Jin ldquoExperimental investigationand design of thin-walled concrete-filled steel tubes subject tobendingrdquoThin-Walled Structures vol 63 pp 44ndash50 2013

[7] B Uy ldquoStrength of concrete filled steel box columns incorporat-ing local bucklingrdquo Journal of Structural Engineering vol 126no 3 pp 341ndash352 2000

[8] M Mursi and B Uy ldquoStrength of concrete filled steel boxcolumns incorporating interaction bucklingrdquo Journal of Struc-tural Engineering vol 129 no 5 pp 626ndash639 2003

Submit your manuscripts athttpwwwhindawicom

ScientificaHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

CorrosionInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Polymer ScienceInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

CeramicsJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

CompositesJournal of

NanoparticlesJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

International Journal of

Biomaterials

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

NanoscienceJournal of

TextilesHindawi Publishing Corporation httpwwwhindawicom Volume 2014

Journal of

NanotechnologyHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal of

CrystallographyJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

CoatingsJournal of

Advances in

Materials Science and EngineeringHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Smart Materials Research

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

MetallurgyJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

BioMed Research International

MaterialsJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Nano

materials

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal ofNanomaterials

Advances in Materials Science and Engineering 3

Figure 4 Manufacturing procedure of steel tube in factory

Figure 5 Material test of concrete

Table 2 Compressive strength of concrete at different ages

Age 3 d 7 d 28 dCompressive strength (MPa) 163 248 455

Chinese standards compression tests are carried out asshown in Figure 5 and Table 2 The elastic modulus (Ec) is316 times 104MPa

3 Test Monitoring and Analysis

31 Test Monitoring Program

311 Displacement Monitoring Vault and convergency dis-placement are monitored in the test The settlement value istested with a level and the convergency values are tested witha convergence device

312 Strain Monitoring It is shown in Figure 6 that theresistance strain gauge and fiber are set only on one side of thespecimen for symmetryMeasuring point arrangement can bedivided into the vault area (C1 A1 and S1) the largest cornerarea (C2 S2) the top of the straight wall area (S3 B1) thestraight wall area (A2) and the connection area (from D1 toD4) in which S1simS3 are fiber grating measuring points

313 Pressure Monitoring As what is shown in Figures 7and 8 three pressure gauges (Y1simY3) are set between CTST

1000

A2

D3

D1

D2

D4

B1S3

S2C2

C1A1S1

Figure 6 The location of resistance strain gauge and fiber

1500

Y3

Y2

Y1

3072

Figure 7 The location of pressure gauge

support (or the steel grid support) and surrounding rockThe pressure gauges are tied to the designed position on theoutside surface of the support in site

32 Test Results Analysis

321 Displacement Monitoring Results Analysis The settle-ment-time curves in the vaults and convergency value-timecurves in both sides are shown in Figures 9 and 10 It isobserved that the biggest settlement in the vaults of CTSTwith concrete is less than 5mm while for the one withoutconcrete it is less than 75mm The steel gridrsquos biggestsettlement in the vaults is less than 7mmAll the convergencyvalues in both sides of the supports are less than 18mmThevertical and horizontal deformations of the tunnel are stableafter 10 days so the unobvious deformations in the latter arenot shown in Figure 9

Figures 11 and 12 present load-settlement curves in thevaults and load-convergency value curves in both sides

It is shown in Figure 11 that the curves of ST-1simST-3appeared under the concave due to connection scalability and

4 Advances in Materials Science and Engineering

(a) The colligation of the pressure monitor (b) Read the pressure monitor in situ

Figure 8 Pressure measurement in situ

0 2Time (d)

4 6 8 10 12

1

2

3

4

5

6

7

8

ST-1ST-2ST-3

ST-4ST-5GS

Settl

emen

t (m

m)

Figure 9 Settlement-time curves in the vaults

0 2 4 6 8 10 12

02

04

06

08

10

12

14

16

18

Time (d)

Con

verg

ency

val

ue (m

m)

ST-1ST-2ST-3

ST-4ST-5GS

Figure 10 Convergency value-time curves in both sides

Advances in Materials Science and Engineering 5

0 1 2 3 4 5 6 7 8

10

20

30

40

50

60

70

80

90

100

Settlement (mm)

Load

(kN

)

ST-1ST-2ST-3

ST-4ST-5GS

Figure 11 Load-settlement curves in the vaults

02 04 06 08 10 12 14 160

10

20

30

40

50

60

70

80

90

100

Convergency value (mm)

Load

(kN

)

ST-1ST-2ST-3

ST-4ST-5GS

Figure 12 Load-convergency value curves in both sides

smaller gap between surrounding rock and support when theload is less than 10 kN In the later elastic stage the largestvertical deformation is 25sim45mm The curve of ST-4 withnew connection has no obvious concave It may be becauseof the faster deformation and the shorter time of connectioncompression and gap pressure for CTST without concreteThe curves of ST-5 with common connection and steel griddid not appear under the concave It can be seen that themaincause of the concave is connection scalability The straightline slope of ST-1 is bigger than that of ST-5 which presents

that the new connection has better resistance to deformationFrom the gradually decreasing straight line slopes of ST-1simST-3 it could be concluded that the vertical deformationdecreased as the steel thickness enlarged

It is indicated in Figure 12 that the horizontal deformationof steel grid is less than what happened in CTST under thesame load It might be that the bottom of steel grid is linkedto counter-arch making horizontal stiffness of the supportincrease Meanwhile the higher steel ratio and concreteinside the support would lead to larger stiffness

6 Advances in Materials Science and Engineering

0 40 80 120 160 2000

5

10

15

20

25

30

35

40

45

50Lo

ad (k

Nm

)

(120583120576)

ST-1ST-2ST-3

ST-4ST-5

(a) C1

4000

5

10

15

20

25

30

35

40

45

50

Load

(kN

m)

(120583120576)

ST-1ST-2ST-3

ST-4ST-5

minus40minus80minus120

(b) C2

00

5

10

15

20

25

30

35

40

45

50

Load

(kN

m)

(120583120576)

ST-1ST-2ST-3

ST-4ST-5

minus40minus80minus120minus160minus200

(c) S3

Figure 13 Load-strain curves in the outer edge of the CTST supports

322 Strain Monitoring Results Analysis In this study tan-gential strains of 5 CTST supports are mainly monitored

(1) Strain Curves of the Outer Edge It is indicated in Figure 13that each curve in addition toC2 in the ST-2 support is almosta straight line which suggests that the specimen performedlinear elastic as awholeThe slope of ST-2 in the largest cornerchanges from positive to negative It may be caused by steeltube defect or the local stress concentration by concrete insidefilling the gap The support vault of the outer edge (C1) is inthe tensile force While both the largest corner (C2) and thetop of the straight wall (S3) are in the compressive force theabsolute values of maximum tensile and compressive strains

are less than 200 120583120576 Each strain of ST-4 is bigger than ST-3which means that the steel tube with concrete filling couldeffectively improve the ability of resisting deformation

(2) Strain Curves of the Center Axis It is described in Figure 14that both the vault (A1) and the straight wall (A2) are in thecompressive force with the absolute strain values less than200120583120576 Each load-strain curve is almost a straight line

(3) Strain Curves of the Inner Edge It could be seen inFigure 15 that each load-strain curve of the inner edge ofCTST supports is also almost a straight lineThe vault (S1) thelargest corner (S2) and the top of the straight wall (B1) are in

Advances in Materials Science and Engineering 7

0

5

10

15

20

25

30

35

40

45

50

Load

(kN

m)

0(120583120576)

minus40minus60minus80minus100 minus20

ST-1ST-2ST-3

ST-4ST-5

(a) A1

0

5

10

15

20

25

30

35

40

45

50

Load

(kN

m)

0(120583120576)

minus40 minus20minus60minus100 minus80minus120minus140minus160minus180minus200

ST-1ST-2ST-3

ST-4ST-5

(b) A2

Figure 14 Load-strain curves on the center axis of the CTST supports

the compressive force with the absolute strain values less than275120583120576 The specimens performed elastic The steel thicknessand the style of connection cannot influence the load-straincurve in the inner edge obviously

(4) StrainCurves of the Connections As displayed in Figure 16load-strain curves in the inner edge of the CTST supportshave obvious properties The curves of supports with cemen-titious grouted sleeve (ST-1simST-4) can be roughly dividedinto flat part and growing part Early strain grows faster thanthe load which means that the cementitious grouted sleeveconnection exhibits superior flexibility The curve of supportwith common sleeve (ST-5) has no obvious flat part reflectingits connection with bigger stiffness All the absolute values ofmaximum tensile and compressive strains at the connectionsare less than 250120583120576

(5) Strain Distribution Curves of the Inner and Outer EdgesOwing to symmetry of CTST supports the strain distributioncurves are tested only on the left side of the support Themaximum strain distributions of the inner and outer edge ofthe supports are shown in Figures 17 and 18

It is obvious that the tensile strain was gradually trans-formed into compressive strain along the direction of vault tothe straight wall in the outer edge All the straight walls arein compression The maximum tensile strain of outer edge islocated in the vaults while the maximum compressive strainis generated near the lower connection The inner edges ofthe CTST supports are all in compression with the maximumstrain in the vaults But the maximum compressive strain ofST-5 is located near the lower connection The compressivestrain values of vault foot and area near the lower connectionare relatively larger

4 Numerical Analysis

41 The Finite Element Modeling The finite element analysis(FEA) of ST-1simST-3 by ABAQUS program is conductedFour-noded shell element with reduced integration (S4R) isused for steel tube Von-Mises kinematic hardening rule isadopted for steel material The elasticity modulus of steeltakes 206GPa Poissonrsquos ratio takes 030

The three-dimensional 8-noded solid element withreduced integration (C3D8R) is used to mesh the concreteThe elasticity modulus takes 4730radic1198911015840

119888 1198911015840119888mean compression

cylindrical strength of concrete Poissonrsquos ratio takes 020The interface behavior in the tangential direction employs theCoulomb friction model

Considering the influences of surrounding rocks at thescope of 5 times the width the spacing of support (05m) wastaken as the width of surrounding rock Considering that themid-separate wall was established between CTST supportsin the experiment which could affect the force situationa vertical constraint was added at both sides in the outeredges of the concrete lining Only 12 model is needed whencalculation according to the structure symmetry as shown inFigure 19

In this test the displacement values were taken as the loadto apply to the supports and the FEA results were comparedwith the testing results

42 FEA Results and Contrastive Analysis Based on the FEMresults the maximum strain distribution curves of the innerand outer edge of ST-1simST-3 are shown in Figures 20 and21 Table 3 describes the comparison of the maximal strainbetween FEA and test results

8 Advances in Materials Science and Engineering

0

5

10

15

20

25

30

35

40

45

50

Load

(kN

m)

0(120583120576)

minus25minus50minus75minus100minus125minus150minus175minus200minus225minus250minus275

ST-1ST-2ST-3

ST-4ST-5

(a) S1

0

5

10

15

20

25

30

35

40

45

50

Load

(kN

m)

0(120583120576)

minus25minus50minus75minus100minus125minus150minus175minus200minus225minus250

ST-1ST-2ST-3

ST-4ST-5

(b) S2

0

5

10

15

20

25

30

35

40

45

50

Load

(kN

m)

0(120583120576)

minus25minus50minus75minus100minus125minus150minus175minus200minus225minus250

ST-1ST-2ST-3

ST-4ST-5

(c) B1

Figure 15 Load-strain curves in the inner edge of the CTST supports

From Table 3 it is observed that the maximum straindistribution curves of the FEA results are in good agreementwith the experimental results The average error rate of eachmeasuring point (vault largest corner top of the straight walland foot) in the outer edge is 64 71 55 and 72respectively The average error rate of each measuring point(vault largest corner top of the straight wall and foot) inthe inner edge is 60 30 62 and 61 respectivelyThe maximum error of all measuring points is 102 Itmay be caused by less number of horizontal and verticalmeasuring points as a result of some differences betweenthe displacement load applied on the model and the realdisplacement Comparing with the experimental data it isobserved that the FEM adopted in this section is reasonable

which can be well simulated with the working condition ofCTST supports in tunnel and can be used for the structuralanalysis of the similar projects

5 Conclusions

In line with the results of the experimental study and FEAanalysis the results could be summarized as follows

(1) With better compression resistance CTST benefitsto resist against the deformation of the tunnel Thedeformation of tunnels with CTST can reach thesteady state in a short time

Advances in Materials Science and Engineering 9

0 50 100 150 2000

5

10

15

20

25

30

35

40

45

50

Load

(kN

m)

(120583120576)

ST-1ST-2ST-3

ST-4ST-5

(a) D1

0

5

10

15

20

25

30

35

40

45

50

Load

(kN

m)

(120583120576)

ST-1ST-2ST-3

ST-4ST-5

0minus50minus100minus150minus200minus250

(b) D2

(120583120576)

ST-1ST-2ST-3

ST-4ST-5

0minus50minus100minus150minus250 minus2000

5

10

15

20

25

30

35

40

45

50

Load

(kN

m)

(c) D3

0

5

10

15

20

25

30

35

40

45

50

Load

(kN

m)

(120583120576)

ST-1ST-2ST-3

ST-4ST-5

0minus50minus100minus150minus250 minus200

(d) D4

Figure 16 Load-strain curves at the connections of the CTST supports

ST-1 ST-2 ST-3 ST-4 ST-5

1172 1242 1284 1313 2003 18521795 17621758 1797

minus1229 minus929 minus1253 minus1412minus1463

minus1974minus1885

minus963

minus1905minus1873

minus1062

minus1995minus1942

minus1037

minus1495minus145

minus663

minus1795minus175

minus97

Figure 17 Strain distribution curves in the outer edge of the CTST supports

10 Advances in Materials Science and Engineering

ST-1 ST-2 ST-3 ST-4 ST-5

minus2134 minus1645 minus2175 minus2237 minus2361

minus2302minus2285

minus2315

minus2465 minus238

minus1796minus1555

minus1935

minus2059 minus2503

minus1964

minus1499

minus1758

minus1883minus2243

minus1396

minus1094

minus1285

minus1785minus192

minus2095

minus1562

minus1881

minus1956 minus2408

Figure 18 Strain distribution curves in the inner edge of the CTST supports

(a) The whole mesh of tunnel

X

Y

Z

(b) Lining and supportmesh

Figure 19 Mesh of steel tube model

ST-1 ST-2 ST-3

1853 1348 1434

minus1337

minus1858

minus108

minus989

minus133

minus722

minus1354

minus1912

minus1034

Figure 20 Strain distribution curves in the outer edge of the CTST supports

ST-1 ST-2 ST-3

minus2303

minus1003

minus1479

minus1913 minus2473

minus1854

minus1447

minus2337minus1714

minus1474

minus2153

minus2527

Figure 21 Strain distribution curves in the inner edge of the CTST supports

Advances in Materials Science and Engineering 11

Table3Com

paris

onof

them

axim

alstr

ainbetweenFE

Aandtestresults

Locatio

nSpecim

enST

-1ST

-2ST

-3120576

119879120576

FEM(|120576

FEMminus120576

119879|120576

FEM)times100120576

119879120576

FEM(|120576

FEMminus120576

119879|120576

FEM)times100120576

119879120576

FEM(|120576

FEMminus120576

119879|120576

FEM)times100

Theo

uter

edge

Vault

1797

1853

30

1242

1348

79

1313

1434

84

Largestcorner

minus97minus108

102

minus663minus722

82

minus1037minus1034

30

Topof

thes

traightw

allminus175minus1858

58

minus145minus133

90

minus1942minus1912

16

Foot

minus1229minus1337

81

minus929minus989

61

minus1253minus1354

75

Theinn

eredge

Vault

minus2408minus2527

47

minus192minus1913

40

minus2243minus2473

93

Largestcornerminus1881minus2153

26

minus1285minus1479

13

minus1758minus1854

52

Topof

thes

traightw

allminus1562minus1474

60

minus1094minus1003

91

minus1499minus1447

36

Foot

minus2134minus2303

73

minus1645minus1714

40

minus2175minus2337

69

Note120576119879means

them

axim

umstr

ainvalueo

fexp

erim

entand120576FE

Mmeans

them

axim

umstr

ainvalueo

fFEM

Tensiles

trainispo

sitivecompressiv

estrainisnegativ

e

12 Advances in Materials Science and Engineering

(2) All of the CTST supports perform elastic duringthe experiment The higher steel ratio and concreteinside the larger stiffness of CTST obtained

(3) The cementitious grouted sleeve connection withsuperior flexibility exhibits better resistance to defor-mation

(4) The tensile strain is gradually transformed into com-pressive strain along the direction of vault to thefoot in the outer edge The inner edges of the CTSTsupports are all in compression The absolute strainvalues of vault connections and tube foot are larger

(5) The mechanical behaviors of CTST supports in thetunnel are analyzed with ABAQUS software packageThe analysis results agree well with the test resultsThe maximum error is 102 The model and theparameters chosen are relatively reasonable and couldbe used for the structural analysis of the similarsupporting projects

Conflict of Interests

The authors declare that they have no conflict of interests

References

[1] M Elchalakani and X-L Zhao ldquoConcrete-filled cold-formedcircular steel tubes subjected to variable amplitude cyclic purebendingrdquo Engineering Structures vol 30 no 2 pp 287ndash2992008

[2] M V Chitawadagi and M C Narasimhan ldquoStrength deforma-tion behaviour of circular concrete filled steel tubes subjected topure bendingrdquo Journal of Constructional Steel Research vol 65no 8-9 pp 1836ndash1845 2009

[3] Y-F An C Roeder and L-H Han ldquoFlexural performanceof concrete-encased concrete-filled steel tubesrdquo Magazine ofConcrete Research vol 66 no 5-6 pp 249ndash267 2014

[4] L-H Han S-H He and F-Y Liao ldquoPerformance and calcula-tions of concrete filled steel tubes (CFST) under axial tensionrdquoJournal of Constructional Steel Research vol 67 no 11 pp 1699ndash1709 2011

[5] W Li Q Wang D Wang et al ldquoExperimental study on shortcolumns under axial load of U-type confined concrete archcentering and its application in minerdquo Journal of Mining ampSafety Engineering vol 31 no 1 pp 1ndash9 2014 (Chinese)

[6] A-Y Jiang J Chen and W-L Jin ldquoExperimental investigationand design of thin-walled concrete-filled steel tubes subject tobendingrdquoThin-Walled Structures vol 63 pp 44ndash50 2013

[7] B Uy ldquoStrength of concrete filled steel box columns incorporat-ing local bucklingrdquo Journal of Structural Engineering vol 126no 3 pp 341ndash352 2000

[8] M Mursi and B Uy ldquoStrength of concrete filled steel boxcolumns incorporating interaction bucklingrdquo Journal of Struc-tural Engineering vol 129 no 5 pp 626ndash639 2003

Submit your manuscripts athttpwwwhindawicom

ScientificaHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

CorrosionInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Polymer ScienceInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

CeramicsJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

CompositesJournal of

NanoparticlesJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

International Journal of

Biomaterials

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

NanoscienceJournal of

TextilesHindawi Publishing Corporation httpwwwhindawicom Volume 2014

Journal of

NanotechnologyHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal of

CrystallographyJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

CoatingsJournal of

Advances in

Materials Science and EngineeringHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Smart Materials Research

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

MetallurgyJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

BioMed Research International

MaterialsJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Nano

materials

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal ofNanomaterials

4 Advances in Materials Science and Engineering

(a) The colligation of the pressure monitor (b) Read the pressure monitor in situ

Figure 8 Pressure measurement in situ

0 2Time (d)

4 6 8 10 12

1

2

3

4

5

6

7

8

ST-1ST-2ST-3

ST-4ST-5GS

Settl

emen

t (m

m)

Figure 9 Settlement-time curves in the vaults

0 2 4 6 8 10 12

02

04

06

08

10

12

14

16

18

Time (d)

Con

verg

ency

val

ue (m

m)

ST-1ST-2ST-3

ST-4ST-5GS

Figure 10 Convergency value-time curves in both sides

Advances in Materials Science and Engineering 5

0 1 2 3 4 5 6 7 8

10

20

30

40

50

60

70

80

90

100

Settlement (mm)

Load

(kN

)

ST-1ST-2ST-3

ST-4ST-5GS

Figure 11 Load-settlement curves in the vaults

02 04 06 08 10 12 14 160

10

20

30

40

50

60

70

80

90

100

Convergency value (mm)

Load

(kN

)

ST-1ST-2ST-3

ST-4ST-5GS

Figure 12 Load-convergency value curves in both sides

smaller gap between surrounding rock and support when theload is less than 10 kN In the later elastic stage the largestvertical deformation is 25sim45mm The curve of ST-4 withnew connection has no obvious concave It may be becauseof the faster deformation and the shorter time of connectioncompression and gap pressure for CTST without concreteThe curves of ST-5 with common connection and steel griddid not appear under the concave It can be seen that themaincause of the concave is connection scalability The straightline slope of ST-1 is bigger than that of ST-5 which presents

that the new connection has better resistance to deformationFrom the gradually decreasing straight line slopes of ST-1simST-3 it could be concluded that the vertical deformationdecreased as the steel thickness enlarged

It is indicated in Figure 12 that the horizontal deformationof steel grid is less than what happened in CTST under thesame load It might be that the bottom of steel grid is linkedto counter-arch making horizontal stiffness of the supportincrease Meanwhile the higher steel ratio and concreteinside the support would lead to larger stiffness

6 Advances in Materials Science and Engineering

0 40 80 120 160 2000

5

10

15

20

25

30

35

40

45

50Lo

ad (k

Nm

)

(120583120576)

ST-1ST-2ST-3

ST-4ST-5

(a) C1

4000

5

10

15

20

25

30

35

40

45

50

Load

(kN

m)

(120583120576)

ST-1ST-2ST-3

ST-4ST-5

minus40minus80minus120

(b) C2

00

5

10

15

20

25

30

35

40

45

50

Load

(kN

m)

(120583120576)

ST-1ST-2ST-3

ST-4ST-5

minus40minus80minus120minus160minus200

(c) S3

Figure 13 Load-strain curves in the outer edge of the CTST supports

322 Strain Monitoring Results Analysis In this study tan-gential strains of 5 CTST supports are mainly monitored

(1) Strain Curves of the Outer Edge It is indicated in Figure 13that each curve in addition toC2 in the ST-2 support is almosta straight line which suggests that the specimen performedlinear elastic as awholeThe slope of ST-2 in the largest cornerchanges from positive to negative It may be caused by steeltube defect or the local stress concentration by concrete insidefilling the gap The support vault of the outer edge (C1) is inthe tensile force While both the largest corner (C2) and thetop of the straight wall (S3) are in the compressive force theabsolute values of maximum tensile and compressive strains

are less than 200 120583120576 Each strain of ST-4 is bigger than ST-3which means that the steel tube with concrete filling couldeffectively improve the ability of resisting deformation

(2) Strain Curves of the Center Axis It is described in Figure 14that both the vault (A1) and the straight wall (A2) are in thecompressive force with the absolute strain values less than200120583120576 Each load-strain curve is almost a straight line

(3) Strain Curves of the Inner Edge It could be seen inFigure 15 that each load-strain curve of the inner edge ofCTST supports is also almost a straight lineThe vault (S1) thelargest corner (S2) and the top of the straight wall (B1) are in

Advances in Materials Science and Engineering 7

0

5

10

15

20

25

30

35

40

45

50

Load

(kN

m)

0(120583120576)

minus40minus60minus80minus100 minus20

ST-1ST-2ST-3

ST-4ST-5

(a) A1

0

5

10

15

20

25

30

35

40

45

50

Load

(kN

m)

0(120583120576)

minus40 minus20minus60minus100 minus80minus120minus140minus160minus180minus200

ST-1ST-2ST-3

ST-4ST-5

(b) A2

Figure 14 Load-strain curves on the center axis of the CTST supports

the compressive force with the absolute strain values less than275120583120576 The specimens performed elastic The steel thicknessand the style of connection cannot influence the load-straincurve in the inner edge obviously

(4) StrainCurves of the Connections As displayed in Figure 16load-strain curves in the inner edge of the CTST supportshave obvious properties The curves of supports with cemen-titious grouted sleeve (ST-1simST-4) can be roughly dividedinto flat part and growing part Early strain grows faster thanthe load which means that the cementitious grouted sleeveconnection exhibits superior flexibility The curve of supportwith common sleeve (ST-5) has no obvious flat part reflectingits connection with bigger stiffness All the absolute values ofmaximum tensile and compressive strains at the connectionsare less than 250120583120576

(5) Strain Distribution Curves of the Inner and Outer EdgesOwing to symmetry of CTST supports the strain distributioncurves are tested only on the left side of the support Themaximum strain distributions of the inner and outer edge ofthe supports are shown in Figures 17 and 18

It is obvious that the tensile strain was gradually trans-formed into compressive strain along the direction of vault tothe straight wall in the outer edge All the straight walls arein compression The maximum tensile strain of outer edge islocated in the vaults while the maximum compressive strainis generated near the lower connection The inner edges ofthe CTST supports are all in compression with the maximumstrain in the vaults But the maximum compressive strain ofST-5 is located near the lower connection The compressivestrain values of vault foot and area near the lower connectionare relatively larger

4 Numerical Analysis

41 The Finite Element Modeling The finite element analysis(FEA) of ST-1simST-3 by ABAQUS program is conductedFour-noded shell element with reduced integration (S4R) isused for steel tube Von-Mises kinematic hardening rule isadopted for steel material The elasticity modulus of steeltakes 206GPa Poissonrsquos ratio takes 030

The three-dimensional 8-noded solid element withreduced integration (C3D8R) is used to mesh the concreteThe elasticity modulus takes 4730radic1198911015840

119888 1198911015840119888mean compression

cylindrical strength of concrete Poissonrsquos ratio takes 020The interface behavior in the tangential direction employs theCoulomb friction model

Considering the influences of surrounding rocks at thescope of 5 times the width the spacing of support (05m) wastaken as the width of surrounding rock Considering that themid-separate wall was established between CTST supportsin the experiment which could affect the force situationa vertical constraint was added at both sides in the outeredges of the concrete lining Only 12 model is needed whencalculation according to the structure symmetry as shown inFigure 19

In this test the displacement values were taken as the loadto apply to the supports and the FEA results were comparedwith the testing results

42 FEA Results and Contrastive Analysis Based on the FEMresults the maximum strain distribution curves of the innerand outer edge of ST-1simST-3 are shown in Figures 20 and21 Table 3 describes the comparison of the maximal strainbetween FEA and test results

8 Advances in Materials Science and Engineering

0

5

10

15

20

25

30

35

40

45

50

Load

(kN

m)

0(120583120576)

minus25minus50minus75minus100minus125minus150minus175minus200minus225minus250minus275

ST-1ST-2ST-3

ST-4ST-5

(a) S1

0

5

10

15

20

25

30

35

40

45

50

Load

(kN

m)

0(120583120576)

minus25minus50minus75minus100minus125minus150minus175minus200minus225minus250

ST-1ST-2ST-3

ST-4ST-5

(b) S2

0

5

10

15

20

25

30

35

40

45

50

Load

(kN

m)

0(120583120576)

minus25minus50minus75minus100minus125minus150minus175minus200minus225minus250

ST-1ST-2ST-3

ST-4ST-5

(c) B1

Figure 15 Load-strain curves in the inner edge of the CTST supports

From Table 3 it is observed that the maximum straindistribution curves of the FEA results are in good agreementwith the experimental results The average error rate of eachmeasuring point (vault largest corner top of the straight walland foot) in the outer edge is 64 71 55 and 72respectively The average error rate of each measuring point(vault largest corner top of the straight wall and foot) inthe inner edge is 60 30 62 and 61 respectivelyThe maximum error of all measuring points is 102 Itmay be caused by less number of horizontal and verticalmeasuring points as a result of some differences betweenthe displacement load applied on the model and the realdisplacement Comparing with the experimental data it isobserved that the FEM adopted in this section is reasonable

which can be well simulated with the working condition ofCTST supports in tunnel and can be used for the structuralanalysis of the similar projects

5 Conclusions

In line with the results of the experimental study and FEAanalysis the results could be summarized as follows

(1) With better compression resistance CTST benefitsto resist against the deformation of the tunnel Thedeformation of tunnels with CTST can reach thesteady state in a short time

Advances in Materials Science and Engineering 9

0 50 100 150 2000

5

10

15

20

25

30

35

40

45

50

Load

(kN

m)

(120583120576)

ST-1ST-2ST-3

ST-4ST-5

(a) D1

0

5

10

15

20

25

30

35

40

45

50

Load

(kN

m)

(120583120576)

ST-1ST-2ST-3

ST-4ST-5

0minus50minus100minus150minus200minus250

(b) D2

(120583120576)

ST-1ST-2ST-3

ST-4ST-5

0minus50minus100minus150minus250 minus2000

5

10

15

20

25

30

35

40

45

50

Load

(kN

m)

(c) D3

0

5

10

15

20

25

30

35

40

45

50

Load

(kN

m)

(120583120576)

ST-1ST-2ST-3

ST-4ST-5

0minus50minus100minus150minus250 minus200

(d) D4

Figure 16 Load-strain curves at the connections of the CTST supports

ST-1 ST-2 ST-3 ST-4 ST-5

1172 1242 1284 1313 2003 18521795 17621758 1797

minus1229 minus929 minus1253 minus1412minus1463

minus1974minus1885

minus963

minus1905minus1873

minus1062

minus1995minus1942

minus1037

minus1495minus145

minus663

minus1795minus175

minus97

Figure 17 Strain distribution curves in the outer edge of the CTST supports

10 Advances in Materials Science and Engineering

ST-1 ST-2 ST-3 ST-4 ST-5

minus2134 minus1645 minus2175 minus2237 minus2361

minus2302minus2285

minus2315

minus2465 minus238

minus1796minus1555

minus1935

minus2059 minus2503

minus1964

minus1499

minus1758

minus1883minus2243

minus1396

minus1094

minus1285

minus1785minus192

minus2095

minus1562

minus1881

minus1956 minus2408

Figure 18 Strain distribution curves in the inner edge of the CTST supports

(a) The whole mesh of tunnel

X

Y

Z

(b) Lining and supportmesh

Figure 19 Mesh of steel tube model

ST-1 ST-2 ST-3

1853 1348 1434

minus1337

minus1858

minus108

minus989

minus133

minus722

minus1354

minus1912

minus1034

Figure 20 Strain distribution curves in the outer edge of the CTST supports

ST-1 ST-2 ST-3

minus2303

minus1003

minus1479

minus1913 minus2473

minus1854

minus1447

minus2337minus1714

minus1474

minus2153

minus2527

Figure 21 Strain distribution curves in the inner edge of the CTST supports

Advances in Materials Science and Engineering 11

Table3Com

paris

onof

them

axim

alstr

ainbetweenFE

Aandtestresults

Locatio

nSpecim

enST

-1ST

-2ST

-3120576

119879120576

FEM(|120576

FEMminus120576

119879|120576

FEM)times100120576

119879120576

FEM(|120576

FEMminus120576

119879|120576

FEM)times100120576

119879120576

FEM(|120576

FEMminus120576

119879|120576

FEM)times100

Theo

uter

edge

Vault

1797

1853

30

1242

1348

79

1313

1434

84

Largestcorner

minus97minus108

102

minus663minus722

82

minus1037minus1034

30

Topof

thes

traightw

allminus175minus1858

58

minus145minus133

90

minus1942minus1912

16

Foot

minus1229minus1337

81

minus929minus989

61

minus1253minus1354

75

Theinn

eredge

Vault

minus2408minus2527

47

minus192minus1913

40

minus2243minus2473

93

Largestcornerminus1881minus2153

26

minus1285minus1479

13

minus1758minus1854

52

Topof

thes

traightw

allminus1562minus1474

60

minus1094minus1003

91

minus1499minus1447

36

Foot

minus2134minus2303

73

minus1645minus1714

40

minus2175minus2337

69

Note120576119879means

them

axim

umstr

ainvalueo

fexp

erim

entand120576FE

Mmeans

them

axim

umstr

ainvalueo

fFEM

Tensiles

trainispo

sitivecompressiv

estrainisnegativ

e

12 Advances in Materials Science and Engineering

(2) All of the CTST supports perform elastic duringthe experiment The higher steel ratio and concreteinside the larger stiffness of CTST obtained

(3) The cementitious grouted sleeve connection withsuperior flexibility exhibits better resistance to defor-mation

(4) The tensile strain is gradually transformed into com-pressive strain along the direction of vault to thefoot in the outer edge The inner edges of the CTSTsupports are all in compression The absolute strainvalues of vault connections and tube foot are larger

(5) The mechanical behaviors of CTST supports in thetunnel are analyzed with ABAQUS software packageThe analysis results agree well with the test resultsThe maximum error is 102 The model and theparameters chosen are relatively reasonable and couldbe used for the structural analysis of the similarsupporting projects

Conflict of Interests

The authors declare that they have no conflict of interests

References

[1] M Elchalakani and X-L Zhao ldquoConcrete-filled cold-formedcircular steel tubes subjected to variable amplitude cyclic purebendingrdquo Engineering Structures vol 30 no 2 pp 287ndash2992008

[2] M V Chitawadagi and M C Narasimhan ldquoStrength deforma-tion behaviour of circular concrete filled steel tubes subjected topure bendingrdquo Journal of Constructional Steel Research vol 65no 8-9 pp 1836ndash1845 2009

[3] Y-F An C Roeder and L-H Han ldquoFlexural performanceof concrete-encased concrete-filled steel tubesrdquo Magazine ofConcrete Research vol 66 no 5-6 pp 249ndash267 2014

[4] L-H Han S-H He and F-Y Liao ldquoPerformance and calcula-tions of concrete filled steel tubes (CFST) under axial tensionrdquoJournal of Constructional Steel Research vol 67 no 11 pp 1699ndash1709 2011

[5] W Li Q Wang D Wang et al ldquoExperimental study on shortcolumns under axial load of U-type confined concrete archcentering and its application in minerdquo Journal of Mining ampSafety Engineering vol 31 no 1 pp 1ndash9 2014 (Chinese)

[6] A-Y Jiang J Chen and W-L Jin ldquoExperimental investigationand design of thin-walled concrete-filled steel tubes subject tobendingrdquoThin-Walled Structures vol 63 pp 44ndash50 2013

[7] B Uy ldquoStrength of concrete filled steel box columns incorporat-ing local bucklingrdquo Journal of Structural Engineering vol 126no 3 pp 341ndash352 2000

[8] M Mursi and B Uy ldquoStrength of concrete filled steel boxcolumns incorporating interaction bucklingrdquo Journal of Struc-tural Engineering vol 129 no 5 pp 626ndash639 2003

Submit your manuscripts athttpwwwhindawicom

ScientificaHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

CorrosionInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Polymer ScienceInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

CeramicsJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

CompositesJournal of

NanoparticlesJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

International Journal of

Biomaterials

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

NanoscienceJournal of

TextilesHindawi Publishing Corporation httpwwwhindawicom Volume 2014

Journal of

NanotechnologyHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal of

CrystallographyJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

CoatingsJournal of

Advances in

Materials Science and EngineeringHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Smart Materials Research

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

MetallurgyJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

BioMed Research International

MaterialsJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Nano

materials

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal ofNanomaterials

Advances in Materials Science and Engineering 5

0 1 2 3 4 5 6 7 8

10

20

30

40

50

60

70

80

90

100

Settlement (mm)

Load

(kN

)

ST-1ST-2ST-3

ST-4ST-5GS

Figure 11 Load-settlement curves in the vaults

02 04 06 08 10 12 14 160

10

20

30

40

50

60

70

80

90

100

Convergency value (mm)

Load

(kN

)

ST-1ST-2ST-3

ST-4ST-5GS

Figure 12 Load-convergency value curves in both sides

smaller gap between surrounding rock and support when theload is less than 10 kN In the later elastic stage the largestvertical deformation is 25sim45mm The curve of ST-4 withnew connection has no obvious concave It may be becauseof the faster deformation and the shorter time of connectioncompression and gap pressure for CTST without concreteThe curves of ST-5 with common connection and steel griddid not appear under the concave It can be seen that themaincause of the concave is connection scalability The straightline slope of ST-1 is bigger than that of ST-5 which presents

that the new connection has better resistance to deformationFrom the gradually decreasing straight line slopes of ST-1simST-3 it could be concluded that the vertical deformationdecreased as the steel thickness enlarged

It is indicated in Figure 12 that the horizontal deformationof steel grid is less than what happened in CTST under thesame load It might be that the bottom of steel grid is linkedto counter-arch making horizontal stiffness of the supportincrease Meanwhile the higher steel ratio and concreteinside the support would lead to larger stiffness

6 Advances in Materials Science and Engineering

0 40 80 120 160 2000

5

10

15

20

25

30

35

40

45

50Lo

ad (k

Nm

)

(120583120576)

ST-1ST-2ST-3

ST-4ST-5

(a) C1

4000

5

10

15

20

25

30

35

40

45

50

Load

(kN

m)

(120583120576)

ST-1ST-2ST-3

ST-4ST-5

minus40minus80minus120

(b) C2

00

5

10

15

20

25

30

35

40

45

50

Load

(kN

m)

(120583120576)

ST-1ST-2ST-3

ST-4ST-5

minus40minus80minus120minus160minus200

(c) S3

Figure 13 Load-strain curves in the outer edge of the CTST supports

322 Strain Monitoring Results Analysis In this study tan-gential strains of 5 CTST supports are mainly monitored

(1) Strain Curves of the Outer Edge It is indicated in Figure 13that each curve in addition toC2 in the ST-2 support is almosta straight line which suggests that the specimen performedlinear elastic as awholeThe slope of ST-2 in the largest cornerchanges from positive to negative It may be caused by steeltube defect or the local stress concentration by concrete insidefilling the gap The support vault of the outer edge (C1) is inthe tensile force While both the largest corner (C2) and thetop of the straight wall (S3) are in the compressive force theabsolute values of maximum tensile and compressive strains

are less than 200 120583120576 Each strain of ST-4 is bigger than ST-3which means that the steel tube with concrete filling couldeffectively improve the ability of resisting deformation

(2) Strain Curves of the Center Axis It is described in Figure 14that both the vault (A1) and the straight wall (A2) are in thecompressive force with the absolute strain values less than200120583120576 Each load-strain curve is almost a straight line

(3) Strain Curves of the Inner Edge It could be seen inFigure 15 that each load-strain curve of the inner edge ofCTST supports is also almost a straight lineThe vault (S1) thelargest corner (S2) and the top of the straight wall (B1) are in

Advances in Materials Science and Engineering 7

0

5

10

15

20

25

30

35

40

45

50

Load

(kN

m)

0(120583120576)

minus40minus60minus80minus100 minus20

ST-1ST-2ST-3

ST-4ST-5

(a) A1

0

5

10

15

20

25

30

35

40

45

50

Load

(kN

m)

0(120583120576)

minus40 minus20minus60minus100 minus80minus120minus140minus160minus180minus200

ST-1ST-2ST-3

ST-4ST-5

(b) A2

Figure 14 Load-strain curves on the center axis of the CTST supports

the compressive force with the absolute strain values less than275120583120576 The specimens performed elastic The steel thicknessand the style of connection cannot influence the load-straincurve in the inner edge obviously

(4) StrainCurves of the Connections As displayed in Figure 16load-strain curves in the inner edge of the CTST supportshave obvious properties The curves of supports with cemen-titious grouted sleeve (ST-1simST-4) can be roughly dividedinto flat part and growing part Early strain grows faster thanthe load which means that the cementitious grouted sleeveconnection exhibits superior flexibility The curve of supportwith common sleeve (ST-5) has no obvious flat part reflectingits connection with bigger stiffness All the absolute values ofmaximum tensile and compressive strains at the connectionsare less than 250120583120576

(5) Strain Distribution Curves of the Inner and Outer EdgesOwing to symmetry of CTST supports the strain distributioncurves are tested only on the left side of the support Themaximum strain distributions of the inner and outer edge ofthe supports are shown in Figures 17 and 18

It is obvious that the tensile strain was gradually trans-formed into compressive strain along the direction of vault tothe straight wall in the outer edge All the straight walls arein compression The maximum tensile strain of outer edge islocated in the vaults while the maximum compressive strainis generated near the lower connection The inner edges ofthe CTST supports are all in compression with the maximumstrain in the vaults But the maximum compressive strain ofST-5 is located near the lower connection The compressivestrain values of vault foot and area near the lower connectionare relatively larger

4 Numerical Analysis

41 The Finite Element Modeling The finite element analysis(FEA) of ST-1simST-3 by ABAQUS program is conductedFour-noded shell element with reduced integration (S4R) isused for steel tube Von-Mises kinematic hardening rule isadopted for steel material The elasticity modulus of steeltakes 206GPa Poissonrsquos ratio takes 030

The three-dimensional 8-noded solid element withreduced integration (C3D8R) is used to mesh the concreteThe elasticity modulus takes 4730radic1198911015840

119888 1198911015840119888mean compression

cylindrical strength of concrete Poissonrsquos ratio takes 020The interface behavior in the tangential direction employs theCoulomb friction model

Considering the influences of surrounding rocks at thescope of 5 times the width the spacing of support (05m) wastaken as the width of surrounding rock Considering that themid-separate wall was established between CTST supportsin the experiment which could affect the force situationa vertical constraint was added at both sides in the outeredges of the concrete lining Only 12 model is needed whencalculation according to the structure symmetry as shown inFigure 19

In this test the displacement values were taken as the loadto apply to the supports and the FEA results were comparedwith the testing results

42 FEA Results and Contrastive Analysis Based on the FEMresults the maximum strain distribution curves of the innerand outer edge of ST-1simST-3 are shown in Figures 20 and21 Table 3 describes the comparison of the maximal strainbetween FEA and test results

8 Advances in Materials Science and Engineering

0

5

10

15

20

25

30

35

40

45

50

Load

(kN

m)

0(120583120576)

minus25minus50minus75minus100minus125minus150minus175minus200minus225minus250minus275

ST-1ST-2ST-3

ST-4ST-5

(a) S1

0

5

10

15

20

25

30

35

40

45

50

Load

(kN

m)

0(120583120576)

minus25minus50minus75minus100minus125minus150minus175minus200minus225minus250

ST-1ST-2ST-3

ST-4ST-5

(b) S2

0

5

10

15

20

25

30

35

40

45

50

Load

(kN

m)

0(120583120576)

minus25minus50minus75minus100minus125minus150minus175minus200minus225minus250

ST-1ST-2ST-3

ST-4ST-5

(c) B1

Figure 15 Load-strain curves in the inner edge of the CTST supports

From Table 3 it is observed that the maximum straindistribution curves of the FEA results are in good agreementwith the experimental results The average error rate of eachmeasuring point (vault largest corner top of the straight walland foot) in the outer edge is 64 71 55 and 72respectively The average error rate of each measuring point(vault largest corner top of the straight wall and foot) inthe inner edge is 60 30 62 and 61 respectivelyThe maximum error of all measuring points is 102 Itmay be caused by less number of horizontal and verticalmeasuring points as a result of some differences betweenthe displacement load applied on the model and the realdisplacement Comparing with the experimental data it isobserved that the FEM adopted in this section is reasonable

which can be well simulated with the working condition ofCTST supports in tunnel and can be used for the structuralanalysis of the similar projects

5 Conclusions

In line with the results of the experimental study and FEAanalysis the results could be summarized as follows

(1) With better compression resistance CTST benefitsto resist against the deformation of the tunnel Thedeformation of tunnels with CTST can reach thesteady state in a short time

Advances in Materials Science and Engineering 9

0 50 100 150 2000

5

10

15

20

25

30

35

40

45

50

Load

(kN

m)

(120583120576)

ST-1ST-2ST-3

ST-4ST-5

(a) D1

0

5

10

15

20

25

30

35

40

45

50

Load

(kN

m)

(120583120576)

ST-1ST-2ST-3

ST-4ST-5

0minus50minus100minus150minus200minus250

(b) D2

(120583120576)

ST-1ST-2ST-3

ST-4ST-5

0minus50minus100minus150minus250 minus2000

5

10

15

20

25

30

35

40

45

50

Load

(kN

m)

(c) D3

0

5

10

15

20

25

30

35

40

45

50

Load

(kN

m)

(120583120576)

ST-1ST-2ST-3

ST-4ST-5

0minus50minus100minus150minus250 minus200

(d) D4

Figure 16 Load-strain curves at the connections of the CTST supports

ST-1 ST-2 ST-3 ST-4 ST-5

1172 1242 1284 1313 2003 18521795 17621758 1797

minus1229 minus929 minus1253 minus1412minus1463

minus1974minus1885

minus963

minus1905minus1873

minus1062

minus1995minus1942

minus1037

minus1495minus145

minus663

minus1795minus175

minus97

Figure 17 Strain distribution curves in the outer edge of the CTST supports

10 Advances in Materials Science and Engineering

ST-1 ST-2 ST-3 ST-4 ST-5

minus2134 minus1645 minus2175 minus2237 minus2361

minus2302minus2285

minus2315

minus2465 minus238

minus1796minus1555

minus1935

minus2059 minus2503

minus1964

minus1499

minus1758

minus1883minus2243

minus1396

minus1094

minus1285

minus1785minus192

minus2095

minus1562

minus1881

minus1956 minus2408

Figure 18 Strain distribution curves in the inner edge of the CTST supports

(a) The whole mesh of tunnel

X

Y

Z

(b) Lining and supportmesh

Figure 19 Mesh of steel tube model

ST-1 ST-2 ST-3

1853 1348 1434

minus1337

minus1858

minus108

minus989

minus133

minus722

minus1354

minus1912

minus1034

Figure 20 Strain distribution curves in the outer edge of the CTST supports

ST-1 ST-2 ST-3

minus2303

minus1003

minus1479

minus1913 minus2473

minus1854

minus1447

minus2337minus1714

minus1474

minus2153

minus2527

Figure 21 Strain distribution curves in the inner edge of the CTST supports

Advances in Materials Science and Engineering 11

Table3Com

paris

onof

them

axim

alstr

ainbetweenFE

Aandtestresults

Locatio

nSpecim

enST

-1ST

-2ST

-3120576

119879120576

FEM(|120576

FEMminus120576

119879|120576

FEM)times100120576

119879120576

FEM(|120576

FEMminus120576

119879|120576

FEM)times100120576

119879120576

FEM(|120576

FEMminus120576

119879|120576

FEM)times100

Theo

uter

edge

Vault

1797

1853

30

1242

1348

79

1313

1434

84

Largestcorner

minus97minus108

102

minus663minus722

82

minus1037minus1034

30

Topof

thes

traightw

allminus175minus1858

58

minus145minus133

90

minus1942minus1912

16

Foot

minus1229minus1337

81

minus929minus989

61

minus1253minus1354

75

Theinn

eredge

Vault

minus2408minus2527

47

minus192minus1913

40

minus2243minus2473

93

Largestcornerminus1881minus2153

26

minus1285minus1479

13

minus1758minus1854

52

Topof

thes

traightw

allminus1562minus1474

60

minus1094minus1003

91

minus1499minus1447

36

Foot

minus2134minus2303

73

minus1645minus1714

40

minus2175minus2337

69

Note120576119879means

them

axim

umstr

ainvalueo

fexp

erim

entand120576FE

Mmeans

them

axim

umstr

ainvalueo

fFEM

Tensiles

trainispo

sitivecompressiv

estrainisnegativ

e

12 Advances in Materials Science and Engineering

(2) All of the CTST supports perform elastic duringthe experiment The higher steel ratio and concreteinside the larger stiffness of CTST obtained

(3) The cementitious grouted sleeve connection withsuperior flexibility exhibits better resistance to defor-mation

(4) The tensile strain is gradually transformed into com-pressive strain along the direction of vault to thefoot in the outer edge The inner edges of the CTSTsupports are all in compression The absolute strainvalues of vault connections and tube foot are larger

(5) The mechanical behaviors of CTST supports in thetunnel are analyzed with ABAQUS software packageThe analysis results agree well with the test resultsThe maximum error is 102 The model and theparameters chosen are relatively reasonable and couldbe used for the structural analysis of the similarsupporting projects

Conflict of Interests

The authors declare that they have no conflict of interests

References

[1] M Elchalakani and X-L Zhao ldquoConcrete-filled cold-formedcircular steel tubes subjected to variable amplitude cyclic purebendingrdquo Engineering Structures vol 30 no 2 pp 287ndash2992008

[2] M V Chitawadagi and M C Narasimhan ldquoStrength deforma-tion behaviour of circular concrete filled steel tubes subjected topure bendingrdquo Journal of Constructional Steel Research vol 65no 8-9 pp 1836ndash1845 2009

[3] Y-F An C Roeder and L-H Han ldquoFlexural performanceof concrete-encased concrete-filled steel tubesrdquo Magazine ofConcrete Research vol 66 no 5-6 pp 249ndash267 2014

[4] L-H Han S-H He and F-Y Liao ldquoPerformance and calcula-tions of concrete filled steel tubes (CFST) under axial tensionrdquoJournal of Constructional Steel Research vol 67 no 11 pp 1699ndash1709 2011

[5] W Li Q Wang D Wang et al ldquoExperimental study on shortcolumns under axial load of U-type confined concrete archcentering and its application in minerdquo Journal of Mining ampSafety Engineering vol 31 no 1 pp 1ndash9 2014 (Chinese)

[6] A-Y Jiang J Chen and W-L Jin ldquoExperimental investigationand design of thin-walled concrete-filled steel tubes subject tobendingrdquoThin-Walled Structures vol 63 pp 44ndash50 2013

[7] B Uy ldquoStrength of concrete filled steel box columns incorporat-ing local bucklingrdquo Journal of Structural Engineering vol 126no 3 pp 341ndash352 2000

[8] M Mursi and B Uy ldquoStrength of concrete filled steel boxcolumns incorporating interaction bucklingrdquo Journal of Struc-tural Engineering vol 129 no 5 pp 626ndash639 2003

Submit your manuscripts athttpwwwhindawicom

ScientificaHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

CorrosionInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Polymer ScienceInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

CeramicsJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

CompositesJournal of

NanoparticlesJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

International Journal of

Biomaterials

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

NanoscienceJournal of

TextilesHindawi Publishing Corporation httpwwwhindawicom Volume 2014

Journal of

NanotechnologyHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal of

CrystallographyJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

CoatingsJournal of

Advances in

Materials Science and EngineeringHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Smart Materials Research

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

MetallurgyJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

BioMed Research International

MaterialsJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Nano

materials

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal ofNanomaterials

6 Advances in Materials Science and Engineering

0 40 80 120 160 2000

5

10

15

20

25

30

35

40

45

50Lo

ad (k

Nm

)

(120583120576)

ST-1ST-2ST-3

ST-4ST-5

(a) C1

4000

5

10

15

20

25

30

35

40

45

50

Load

(kN

m)

(120583120576)

ST-1ST-2ST-3

ST-4ST-5

minus40minus80minus120

(b) C2

00

5

10

15

20

25

30

35

40

45

50

Load

(kN

m)

(120583120576)

ST-1ST-2ST-3

ST-4ST-5

minus40minus80minus120minus160minus200

(c) S3

Figure 13 Load-strain curves in the outer edge of the CTST supports

322 Strain Monitoring Results Analysis In this study tan-gential strains of 5 CTST supports are mainly monitored

(1) Strain Curves of the Outer Edge It is indicated in Figure 13that each curve in addition toC2 in the ST-2 support is almosta straight line which suggests that the specimen performedlinear elastic as awholeThe slope of ST-2 in the largest cornerchanges from positive to negative It may be caused by steeltube defect or the local stress concentration by concrete insidefilling the gap The support vault of the outer edge (C1) is inthe tensile force While both the largest corner (C2) and thetop of the straight wall (S3) are in the compressive force theabsolute values of maximum tensile and compressive strains

are less than 200 120583120576 Each strain of ST-4 is bigger than ST-3which means that the steel tube with concrete filling couldeffectively improve the ability of resisting deformation

(2) Strain Curves of the Center Axis It is described in Figure 14that both the vault (A1) and the straight wall (A2) are in thecompressive force with the absolute strain values less than200120583120576 Each load-strain curve is almost a straight line

(3) Strain Curves of the Inner Edge It could be seen inFigure 15 that each load-strain curve of the inner edge ofCTST supports is also almost a straight lineThe vault (S1) thelargest corner (S2) and the top of the straight wall (B1) are in

Advances in Materials Science and Engineering 7

0

5

10

15

20

25

30

35

40

45

50

Load

(kN

m)

0(120583120576)

minus40minus60minus80minus100 minus20

ST-1ST-2ST-3

ST-4ST-5

(a) A1

0

5

10

15

20

25

30

35

40

45

50

Load

(kN

m)

0(120583120576)

minus40 minus20minus60minus100 minus80minus120minus140minus160minus180minus200

ST-1ST-2ST-3

ST-4ST-5

(b) A2

Figure 14 Load-strain curves on the center axis of the CTST supports

the compressive force with the absolute strain values less than275120583120576 The specimens performed elastic The steel thicknessand the style of connection cannot influence the load-straincurve in the inner edge obviously

(4) StrainCurves of the Connections As displayed in Figure 16load-strain curves in the inner edge of the CTST supportshave obvious properties The curves of supports with cemen-titious grouted sleeve (ST-1simST-4) can be roughly dividedinto flat part and growing part Early strain grows faster thanthe load which means that the cementitious grouted sleeveconnection exhibits superior flexibility The curve of supportwith common sleeve (ST-5) has no obvious flat part reflectingits connection with bigger stiffness All the absolute values ofmaximum tensile and compressive strains at the connectionsare less than 250120583120576

(5) Strain Distribution Curves of the Inner and Outer EdgesOwing to symmetry of CTST supports the strain distributioncurves are tested only on the left side of the support Themaximum strain distributions of the inner and outer edge ofthe supports are shown in Figures 17 and 18

It is obvious that the tensile strain was gradually trans-formed into compressive strain along the direction of vault tothe straight wall in the outer edge All the straight walls arein compression The maximum tensile strain of outer edge islocated in the vaults while the maximum compressive strainis generated near the lower connection The inner edges ofthe CTST supports are all in compression with the maximumstrain in the vaults But the maximum compressive strain ofST-5 is located near the lower connection The compressivestrain values of vault foot and area near the lower connectionare relatively larger

4 Numerical Analysis

41 The Finite Element Modeling The finite element analysis(FEA) of ST-1simST-3 by ABAQUS program is conductedFour-noded shell element with reduced integration (S4R) isused for steel tube Von-Mises kinematic hardening rule isadopted for steel material The elasticity modulus of steeltakes 206GPa Poissonrsquos ratio takes 030

The three-dimensional 8-noded solid element withreduced integration (C3D8R) is used to mesh the concreteThe elasticity modulus takes 4730radic1198911015840

119888 1198911015840119888mean compression

cylindrical strength of concrete Poissonrsquos ratio takes 020The interface behavior in the tangential direction employs theCoulomb friction model

Considering the influences of surrounding rocks at thescope of 5 times the width the spacing of support (05m) wastaken as the width of surrounding rock Considering that themid-separate wall was established between CTST supportsin the experiment which could affect the force situationa vertical constraint was added at both sides in the outeredges of the concrete lining Only 12 model is needed whencalculation according to the structure symmetry as shown inFigure 19

In this test the displacement values were taken as the loadto apply to the supports and the FEA results were comparedwith the testing results

42 FEA Results and Contrastive Analysis Based on the FEMresults the maximum strain distribution curves of the innerand outer edge of ST-1simST-3 are shown in Figures 20 and21 Table 3 describes the comparison of the maximal strainbetween FEA and test results

8 Advances in Materials Science and Engineering

0

5

10

15

20

25

30

35

40

45

50

Load

(kN

m)

0(120583120576)

minus25minus50minus75minus100minus125minus150minus175minus200minus225minus250minus275

ST-1ST-2ST-3

ST-4ST-5

(a) S1

0

5

10

15

20

25

30

35

40

45

50

Load

(kN

m)

0(120583120576)

minus25minus50minus75minus100minus125minus150minus175minus200minus225minus250

ST-1ST-2ST-3

ST-4ST-5

(b) S2

0

5

10

15

20

25

30

35

40

45

50

Load

(kN

m)

0(120583120576)

minus25minus50minus75minus100minus125minus150minus175minus200minus225minus250

ST-1ST-2ST-3

ST-4ST-5

(c) B1

Figure 15 Load-strain curves in the inner edge of the CTST supports

From Table 3 it is observed that the maximum straindistribution curves of the FEA results are in good agreementwith the experimental results The average error rate of eachmeasuring point (vault largest corner top of the straight walland foot) in the outer edge is 64 71 55 and 72respectively The average error rate of each measuring point(vault largest corner top of the straight wall and foot) inthe inner edge is 60 30 62 and 61 respectivelyThe maximum error of all measuring points is 102 Itmay be caused by less number of horizontal and verticalmeasuring points as a result of some differences betweenthe displacement load applied on the model and the realdisplacement Comparing with the experimental data it isobserved that the FEM adopted in this section is reasonable

which can be well simulated with the working condition ofCTST supports in tunnel and can be used for the structuralanalysis of the similar projects

5 Conclusions

In line with the results of the experimental study and FEAanalysis the results could be summarized as follows

(1) With better compression resistance CTST benefitsto resist against the deformation of the tunnel Thedeformation of tunnels with CTST can reach thesteady state in a short time

Advances in Materials Science and Engineering 9

0 50 100 150 2000

5

10

15

20

25

30

35

40

45

50

Load

(kN

m)

(120583120576)

ST-1ST-2ST-3

ST-4ST-5

(a) D1

0

5

10

15

20

25

30

35

40

45

50

Load

(kN

m)

(120583120576)

ST-1ST-2ST-3

ST-4ST-5

0minus50minus100minus150minus200minus250

(b) D2

(120583120576)

ST-1ST-2ST-3

ST-4ST-5

0minus50minus100minus150minus250 minus2000

5

10

15

20

25

30

35

40

45

50

Load

(kN

m)

(c) D3

0

5

10

15

20

25

30

35

40

45

50

Load

(kN

m)

(120583120576)

ST-1ST-2ST-3

ST-4ST-5

0minus50minus100minus150minus250 minus200

(d) D4

Figure 16 Load-strain curves at the connections of the CTST supports

ST-1 ST-2 ST-3 ST-4 ST-5

1172 1242 1284 1313 2003 18521795 17621758 1797

minus1229 minus929 minus1253 minus1412minus1463

minus1974minus1885

minus963

minus1905minus1873

minus1062

minus1995minus1942

minus1037

minus1495minus145

minus663

minus1795minus175

minus97

Figure 17 Strain distribution curves in the outer edge of the CTST supports

10 Advances in Materials Science and Engineering

ST-1 ST-2 ST-3 ST-4 ST-5

minus2134 minus1645 minus2175 minus2237 minus2361

minus2302minus2285

minus2315

minus2465 minus238

minus1796minus1555

minus1935

minus2059 minus2503

minus1964

minus1499

minus1758

minus1883minus2243

minus1396

minus1094

minus1285

minus1785minus192

minus2095

minus1562

minus1881

minus1956 minus2408

Figure 18 Strain distribution curves in the inner edge of the CTST supports

(a) The whole mesh of tunnel

X

Y

Z

(b) Lining and supportmesh

Figure 19 Mesh of steel tube model

ST-1 ST-2 ST-3

1853 1348 1434

minus1337

minus1858

minus108

minus989

minus133

minus722

minus1354

minus1912

minus1034

Figure 20 Strain distribution curves in the outer edge of the CTST supports

ST-1 ST-2 ST-3

minus2303

minus1003

minus1479

minus1913 minus2473

minus1854

minus1447

minus2337minus1714

minus1474

minus2153

minus2527

Figure 21 Strain distribution curves in the inner edge of the CTST supports

Advances in Materials Science and Engineering 11

Table3Com

paris

onof

them

axim

alstr

ainbetweenFE

Aandtestresults

Locatio

nSpecim

enST

-1ST

-2ST

-3120576

119879120576

FEM(|120576

FEMminus120576

119879|120576

FEM)times100120576

119879120576

FEM(|120576

FEMminus120576

119879|120576

FEM)times100120576

119879120576

FEM(|120576

FEMminus120576

119879|120576

FEM)times100

Theo

uter

edge

Vault

1797

1853

30

1242

1348

79

1313

1434

84

Largestcorner

minus97minus108

102

minus663minus722

82

minus1037minus1034

30

Topof

thes

traightw

allminus175minus1858

58

minus145minus133

90

minus1942minus1912

16

Foot

minus1229minus1337

81

minus929minus989

61

minus1253minus1354

75

Theinn

eredge

Vault

minus2408minus2527

47

minus192minus1913

40

minus2243minus2473

93

Largestcornerminus1881minus2153

26

minus1285minus1479

13

minus1758minus1854

52

Topof

thes

traightw

allminus1562minus1474

60

minus1094minus1003

91

minus1499minus1447

36

Foot

minus2134minus2303

73

minus1645minus1714

40

minus2175minus2337

69

Note120576119879means

them

axim

umstr

ainvalueo

fexp

erim

entand120576FE

Mmeans

them

axim

umstr

ainvalueo

fFEM

Tensiles

trainispo

sitivecompressiv

estrainisnegativ

e

12 Advances in Materials Science and Engineering

(2) All of the CTST supports perform elastic duringthe experiment The higher steel ratio and concreteinside the larger stiffness of CTST obtained

(3) The cementitious grouted sleeve connection withsuperior flexibility exhibits better resistance to defor-mation

(4) The tensile strain is gradually transformed into com-pressive strain along the direction of vault to thefoot in the outer edge The inner edges of the CTSTsupports are all in compression The absolute strainvalues of vault connections and tube foot are larger

(5) The mechanical behaviors of CTST supports in thetunnel are analyzed with ABAQUS software packageThe analysis results agree well with the test resultsThe maximum error is 102 The model and theparameters chosen are relatively reasonable and couldbe used for the structural analysis of the similarsupporting projects

Conflict of Interests

The authors declare that they have no conflict of interests

References

[1] M Elchalakani and X-L Zhao ldquoConcrete-filled cold-formedcircular steel tubes subjected to variable amplitude cyclic purebendingrdquo Engineering Structures vol 30 no 2 pp 287ndash2992008

[2] M V Chitawadagi and M C Narasimhan ldquoStrength deforma-tion behaviour of circular concrete filled steel tubes subjected topure bendingrdquo Journal of Constructional Steel Research vol 65no 8-9 pp 1836ndash1845 2009

[3] Y-F An C Roeder and L-H Han ldquoFlexural performanceof concrete-encased concrete-filled steel tubesrdquo Magazine ofConcrete Research vol 66 no 5-6 pp 249ndash267 2014

[4] L-H Han S-H He and F-Y Liao ldquoPerformance and calcula-tions of concrete filled steel tubes (CFST) under axial tensionrdquoJournal of Constructional Steel Research vol 67 no 11 pp 1699ndash1709 2011

[5] W Li Q Wang D Wang et al ldquoExperimental study on shortcolumns under axial load of U-type confined concrete archcentering and its application in minerdquo Journal of Mining ampSafety Engineering vol 31 no 1 pp 1ndash9 2014 (Chinese)

[6] A-Y Jiang J Chen and W-L Jin ldquoExperimental investigationand design of thin-walled concrete-filled steel tubes subject tobendingrdquoThin-Walled Structures vol 63 pp 44ndash50 2013

[7] B Uy ldquoStrength of concrete filled steel box columns incorporat-ing local bucklingrdquo Journal of Structural Engineering vol 126no 3 pp 341ndash352 2000

[8] M Mursi and B Uy ldquoStrength of concrete filled steel boxcolumns incorporating interaction bucklingrdquo Journal of Struc-tural Engineering vol 129 no 5 pp 626ndash639 2003

Submit your manuscripts athttpwwwhindawicom

ScientificaHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

CorrosionInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Polymer ScienceInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

CeramicsJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

CompositesJournal of

NanoparticlesJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

International Journal of

Biomaterials

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

NanoscienceJournal of

TextilesHindawi Publishing Corporation httpwwwhindawicom Volume 2014

Journal of

NanotechnologyHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal of

CrystallographyJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

CoatingsJournal of

Advances in

Materials Science and EngineeringHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Smart Materials Research

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

MetallurgyJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

BioMed Research International

MaterialsJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Nano

materials

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal ofNanomaterials

Advances in Materials Science and Engineering 7

0

5

10

15

20

25

30

35

40

45

50

Load

(kN

m)

0(120583120576)

minus40minus60minus80minus100 minus20

ST-1ST-2ST-3

ST-4ST-5

(a) A1

0

5

10

15

20

25

30

35

40

45

50

Load

(kN

m)

0(120583120576)

minus40 minus20minus60minus100 minus80minus120minus140minus160minus180minus200

ST-1ST-2ST-3

ST-4ST-5

(b) A2

Figure 14 Load-strain curves on the center axis of the CTST supports

the compressive force with the absolute strain values less than275120583120576 The specimens performed elastic The steel thicknessand the style of connection cannot influence the load-straincurve in the inner edge obviously

(4) StrainCurves of the Connections As displayed in Figure 16load-strain curves in the inner edge of the CTST supportshave obvious properties The curves of supports with cemen-titious grouted sleeve (ST-1simST-4) can be roughly dividedinto flat part and growing part Early strain grows faster thanthe load which means that the cementitious grouted sleeveconnection exhibits superior flexibility The curve of supportwith common sleeve (ST-5) has no obvious flat part reflectingits connection with bigger stiffness All the absolute values ofmaximum tensile and compressive strains at the connectionsare less than 250120583120576

(5) Strain Distribution Curves of the Inner and Outer EdgesOwing to symmetry of CTST supports the strain distributioncurves are tested only on the left side of the support Themaximum strain distributions of the inner and outer edge ofthe supports are shown in Figures 17 and 18

It is obvious that the tensile strain was gradually trans-formed into compressive strain along the direction of vault tothe straight wall in the outer edge All the straight walls arein compression The maximum tensile strain of outer edge islocated in the vaults while the maximum compressive strainis generated near the lower connection The inner edges ofthe CTST supports are all in compression with the maximumstrain in the vaults But the maximum compressive strain ofST-5 is located near the lower connection The compressivestrain values of vault foot and area near the lower connectionare relatively larger

4 Numerical Analysis

41 The Finite Element Modeling The finite element analysis(FEA) of ST-1simST-3 by ABAQUS program is conductedFour-noded shell element with reduced integration (S4R) isused for steel tube Von-Mises kinematic hardening rule isadopted for steel material The elasticity modulus of steeltakes 206GPa Poissonrsquos ratio takes 030

The three-dimensional 8-noded solid element withreduced integration (C3D8R) is used to mesh the concreteThe elasticity modulus takes 4730radic1198911015840

119888 1198911015840119888mean compression

cylindrical strength of concrete Poissonrsquos ratio takes 020The interface behavior in the tangential direction employs theCoulomb friction model

Considering the influences of surrounding rocks at thescope of 5 times the width the spacing of support (05m) wastaken as the width of surrounding rock Considering that themid-separate wall was established between CTST supportsin the experiment which could affect the force situationa vertical constraint was added at both sides in the outeredges of the concrete lining Only 12 model is needed whencalculation according to the structure symmetry as shown inFigure 19

In this test the displacement values were taken as the loadto apply to the supports and the FEA results were comparedwith the testing results

42 FEA Results and Contrastive Analysis Based on the FEMresults the maximum strain distribution curves of the innerand outer edge of ST-1simST-3 are shown in Figures 20 and21 Table 3 describes the comparison of the maximal strainbetween FEA and test results

8 Advances in Materials Science and Engineering

0

5

10

15

20

25

30

35

40

45

50

Load

(kN

m)

0(120583120576)

minus25minus50minus75minus100minus125minus150minus175minus200minus225minus250minus275

ST-1ST-2ST-3

ST-4ST-5

(a) S1

0

5

10

15

20

25

30

35

40

45

50

Load

(kN

m)

0(120583120576)

minus25minus50minus75minus100minus125minus150minus175minus200minus225minus250

ST-1ST-2ST-3

ST-4ST-5

(b) S2

0

5

10

15

20

25

30

35

40

45

50

Load

(kN

m)

0(120583120576)

minus25minus50minus75minus100minus125minus150minus175minus200minus225minus250

ST-1ST-2ST-3

ST-4ST-5

(c) B1

Figure 15 Load-strain curves in the inner edge of the CTST supports

From Table 3 it is observed that the maximum straindistribution curves of the FEA results are in good agreementwith the experimental results The average error rate of eachmeasuring point (vault largest corner top of the straight walland foot) in the outer edge is 64 71 55 and 72respectively The average error rate of each measuring point(vault largest corner top of the straight wall and foot) inthe inner edge is 60 30 62 and 61 respectivelyThe maximum error of all measuring points is 102 Itmay be caused by less number of horizontal and verticalmeasuring points as a result of some differences betweenthe displacement load applied on the model and the realdisplacement Comparing with the experimental data it isobserved that the FEM adopted in this section is reasonable

which can be well simulated with the working condition ofCTST supports in tunnel and can be used for the structuralanalysis of the similar projects

5 Conclusions

In line with the results of the experimental study and FEAanalysis the results could be summarized as follows

(1) With better compression resistance CTST benefitsto resist against the deformation of the tunnel Thedeformation of tunnels with CTST can reach thesteady state in a short time

Advances in Materials Science and Engineering 9

0 50 100 150 2000

5

10

15

20

25

30

35

40

45

50

Load

(kN

m)

(120583120576)

ST-1ST-2ST-3

ST-4ST-5

(a) D1

0

5

10

15

20

25

30

35

40

45

50

Load

(kN

m)

(120583120576)

ST-1ST-2ST-3

ST-4ST-5

0minus50minus100minus150minus200minus250

(b) D2

(120583120576)

ST-1ST-2ST-3

ST-4ST-5

0minus50minus100minus150minus250 minus2000

5

10

15

20

25

30

35

40

45

50

Load

(kN

m)

(c) D3

0

5

10

15

20

25

30

35

40

45

50

Load

(kN

m)

(120583120576)

ST-1ST-2ST-3

ST-4ST-5

0minus50minus100minus150minus250 minus200

(d) D4

Figure 16 Load-strain curves at the connections of the CTST supports

ST-1 ST-2 ST-3 ST-4 ST-5

1172 1242 1284 1313 2003 18521795 17621758 1797

minus1229 minus929 minus1253 minus1412minus1463

minus1974minus1885

minus963

minus1905minus1873

minus1062

minus1995minus1942

minus1037

minus1495minus145

minus663

minus1795minus175

minus97

Figure 17 Strain distribution curves in the outer edge of the CTST supports

10 Advances in Materials Science and Engineering

ST-1 ST-2 ST-3 ST-4 ST-5

minus2134 minus1645 minus2175 minus2237 minus2361

minus2302minus2285

minus2315

minus2465 minus238

minus1796minus1555

minus1935

minus2059 minus2503

minus1964

minus1499

minus1758

minus1883minus2243

minus1396

minus1094

minus1285

minus1785minus192

minus2095

minus1562

minus1881

minus1956 minus2408

Figure 18 Strain distribution curves in the inner edge of the CTST supports

(a) The whole mesh of tunnel

X

Y

Z

(b) Lining and supportmesh

Figure 19 Mesh of steel tube model

ST-1 ST-2 ST-3

1853 1348 1434

minus1337

minus1858

minus108

minus989

minus133

minus722

minus1354

minus1912

minus1034

Figure 20 Strain distribution curves in the outer edge of the CTST supports

ST-1 ST-2 ST-3

minus2303

minus1003

minus1479

minus1913 minus2473

minus1854

minus1447

minus2337minus1714

minus1474

minus2153

minus2527

Figure 21 Strain distribution curves in the inner edge of the CTST supports

Advances in Materials Science and Engineering 11

Table3Com

paris

onof

them

axim

alstr

ainbetweenFE

Aandtestresults

Locatio

nSpecim

enST

-1ST

-2ST

-3120576

119879120576

FEM(|120576

FEMminus120576

119879|120576

FEM)times100120576

119879120576

FEM(|120576

FEMminus120576

119879|120576

FEM)times100120576

119879120576

FEM(|120576

FEMminus120576

119879|120576

FEM)times100

Theo

uter

edge

Vault

1797

1853

30

1242

1348

79

1313

1434

84

Largestcorner

minus97minus108

102

minus663minus722

82

minus1037minus1034

30

Topof

thes

traightw

allminus175minus1858

58

minus145minus133

90

minus1942minus1912

16

Foot

minus1229minus1337

81

minus929minus989

61

minus1253minus1354

75

Theinn

eredge

Vault

minus2408minus2527

47

minus192minus1913

40

minus2243minus2473

93

Largestcornerminus1881minus2153

26

minus1285minus1479

13

minus1758minus1854

52

Topof

thes

traightw

allminus1562minus1474

60

minus1094minus1003

91

minus1499minus1447

36

Foot

minus2134minus2303

73

minus1645minus1714

40

minus2175minus2337

69

Note120576119879means

them

axim

umstr

ainvalueo

fexp

erim

entand120576FE

Mmeans

them

axim

umstr

ainvalueo

fFEM

Tensiles

trainispo

sitivecompressiv

estrainisnegativ

e

12 Advances in Materials Science and Engineering

(2) All of the CTST supports perform elastic duringthe experiment The higher steel ratio and concreteinside the larger stiffness of CTST obtained

(3) The cementitious grouted sleeve connection withsuperior flexibility exhibits better resistance to defor-mation

(4) The tensile strain is gradually transformed into com-pressive strain along the direction of vault to thefoot in the outer edge The inner edges of the CTSTsupports are all in compression The absolute strainvalues of vault connections and tube foot are larger

(5) The mechanical behaviors of CTST supports in thetunnel are analyzed with ABAQUS software packageThe analysis results agree well with the test resultsThe maximum error is 102 The model and theparameters chosen are relatively reasonable and couldbe used for the structural analysis of the similarsupporting projects

Conflict of Interests

The authors declare that they have no conflict of interests

References

[1] M Elchalakani and X-L Zhao ldquoConcrete-filled cold-formedcircular steel tubes subjected to variable amplitude cyclic purebendingrdquo Engineering Structures vol 30 no 2 pp 287ndash2992008

[2] M V Chitawadagi and M C Narasimhan ldquoStrength deforma-tion behaviour of circular concrete filled steel tubes subjected topure bendingrdquo Journal of Constructional Steel Research vol 65no 8-9 pp 1836ndash1845 2009

[3] Y-F An C Roeder and L-H Han ldquoFlexural performanceof concrete-encased concrete-filled steel tubesrdquo Magazine ofConcrete Research vol 66 no 5-6 pp 249ndash267 2014

[4] L-H Han S-H He and F-Y Liao ldquoPerformance and calcula-tions of concrete filled steel tubes (CFST) under axial tensionrdquoJournal of Constructional Steel Research vol 67 no 11 pp 1699ndash1709 2011

[5] W Li Q Wang D Wang et al ldquoExperimental study on shortcolumns under axial load of U-type confined concrete archcentering and its application in minerdquo Journal of Mining ampSafety Engineering vol 31 no 1 pp 1ndash9 2014 (Chinese)

[6] A-Y Jiang J Chen and W-L Jin ldquoExperimental investigationand design of thin-walled concrete-filled steel tubes subject tobendingrdquoThin-Walled Structures vol 63 pp 44ndash50 2013

[7] B Uy ldquoStrength of concrete filled steel box columns incorporat-ing local bucklingrdquo Journal of Structural Engineering vol 126no 3 pp 341ndash352 2000

[8] M Mursi and B Uy ldquoStrength of concrete filled steel boxcolumns incorporating interaction bucklingrdquo Journal of Struc-tural Engineering vol 129 no 5 pp 626ndash639 2003

Submit your manuscripts athttpwwwhindawicom

ScientificaHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

CorrosionInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Polymer ScienceInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

CeramicsJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

CompositesJournal of

NanoparticlesJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

International Journal of

Biomaterials

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

NanoscienceJournal of

TextilesHindawi Publishing Corporation httpwwwhindawicom Volume 2014

Journal of

NanotechnologyHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal of

CrystallographyJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

CoatingsJournal of

Advances in

Materials Science and EngineeringHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Smart Materials Research

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

MetallurgyJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

BioMed Research International

MaterialsJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Nano

materials

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal ofNanomaterials

8 Advances in Materials Science and Engineering

0

5

10

15

20

25

30

35

40

45

50

Load

(kN

m)

0(120583120576)

minus25minus50minus75minus100minus125minus150minus175minus200minus225minus250minus275

ST-1ST-2ST-3

ST-4ST-5

(a) S1

0

5

10

15

20

25

30

35

40

45

50

Load

(kN

m)

0(120583120576)

minus25minus50minus75minus100minus125minus150minus175minus200minus225minus250

ST-1ST-2ST-3

ST-4ST-5

(b) S2

0

5

10

15

20

25

30

35

40

45

50

Load

(kN

m)

0(120583120576)

minus25minus50minus75minus100minus125minus150minus175minus200minus225minus250

ST-1ST-2ST-3

ST-4ST-5

(c) B1

Figure 15 Load-strain curves in the inner edge of the CTST supports

From Table 3 it is observed that the maximum straindistribution curves of the FEA results are in good agreementwith the experimental results The average error rate of eachmeasuring point (vault largest corner top of the straight walland foot) in the outer edge is 64 71 55 and 72respectively The average error rate of each measuring point(vault largest corner top of the straight wall and foot) inthe inner edge is 60 30 62 and 61 respectivelyThe maximum error of all measuring points is 102 Itmay be caused by less number of horizontal and verticalmeasuring points as a result of some differences betweenthe displacement load applied on the model and the realdisplacement Comparing with the experimental data it isobserved that the FEM adopted in this section is reasonable

which can be well simulated with the working condition ofCTST supports in tunnel and can be used for the structuralanalysis of the similar projects

5 Conclusions

In line with the results of the experimental study and FEAanalysis the results could be summarized as follows

(1) With better compression resistance CTST benefitsto resist against the deformation of the tunnel Thedeformation of tunnels with CTST can reach thesteady state in a short time

Advances in Materials Science and Engineering 9

0 50 100 150 2000

5

10

15

20

25

30

35

40

45

50

Load

(kN

m)

(120583120576)

ST-1ST-2ST-3

ST-4ST-5

(a) D1

0

5

10

15

20

25

30

35

40

45

50

Load

(kN

m)

(120583120576)

ST-1ST-2ST-3

ST-4ST-5

0minus50minus100minus150minus200minus250

(b) D2

(120583120576)

ST-1ST-2ST-3

ST-4ST-5

0minus50minus100minus150minus250 minus2000

5

10

15

20

25

30

35

40

45

50

Load

(kN

m)

(c) D3

0

5

10

15

20

25

30

35

40

45

50

Load

(kN

m)

(120583120576)

ST-1ST-2ST-3

ST-4ST-5

0minus50minus100minus150minus250 minus200

(d) D4

Figure 16 Load-strain curves at the connections of the CTST supports

ST-1 ST-2 ST-3 ST-4 ST-5

1172 1242 1284 1313 2003 18521795 17621758 1797

minus1229 minus929 minus1253 minus1412minus1463

minus1974minus1885

minus963

minus1905minus1873

minus1062

minus1995minus1942

minus1037

minus1495minus145

minus663

minus1795minus175

minus97

Figure 17 Strain distribution curves in the outer edge of the CTST supports

10 Advances in Materials Science and Engineering

ST-1 ST-2 ST-3 ST-4 ST-5

minus2134 minus1645 minus2175 minus2237 minus2361

minus2302minus2285

minus2315

minus2465 minus238

minus1796minus1555

minus1935

minus2059 minus2503

minus1964

minus1499

minus1758

minus1883minus2243

minus1396

minus1094

minus1285

minus1785minus192

minus2095

minus1562

minus1881

minus1956 minus2408

Figure 18 Strain distribution curves in the inner edge of the CTST supports

(a) The whole mesh of tunnel

X

Y

Z

(b) Lining and supportmesh

Figure 19 Mesh of steel tube model

ST-1 ST-2 ST-3

1853 1348 1434

minus1337

minus1858

minus108

minus989

minus133

minus722

minus1354

minus1912

minus1034

Figure 20 Strain distribution curves in the outer edge of the CTST supports

ST-1 ST-2 ST-3

minus2303

minus1003

minus1479

minus1913 minus2473

minus1854

minus1447

minus2337minus1714

minus1474

minus2153

minus2527

Figure 21 Strain distribution curves in the inner edge of the CTST supports

Advances in Materials Science and Engineering 11

Table3Com

paris

onof

them

axim

alstr

ainbetweenFE

Aandtestresults

Locatio

nSpecim

enST

-1ST

-2ST

-3120576

119879120576

FEM(|120576

FEMminus120576

119879|120576

FEM)times100120576

119879120576

FEM(|120576

FEMminus120576

119879|120576

FEM)times100120576

119879120576

FEM(|120576

FEMminus120576

119879|120576

FEM)times100

Theo

uter

edge

Vault

1797

1853

30

1242

1348

79

1313

1434

84

Largestcorner

minus97minus108

102

minus663minus722

82

minus1037minus1034

30

Topof

thes

traightw

allminus175minus1858

58

minus145minus133

90

minus1942minus1912

16

Foot

minus1229minus1337

81

minus929minus989

61

minus1253minus1354

75

Theinn

eredge

Vault

minus2408minus2527

47

minus192minus1913

40

minus2243minus2473

93

Largestcornerminus1881minus2153

26

minus1285minus1479

13

minus1758minus1854

52

Topof

thes

traightw

allminus1562minus1474

60

minus1094minus1003

91

minus1499minus1447

36

Foot

minus2134minus2303

73

minus1645minus1714

40

minus2175minus2337

69

Note120576119879means

them

axim

umstr

ainvalueo

fexp

erim

entand120576FE

Mmeans

them

axim

umstr

ainvalueo

fFEM

Tensiles

trainispo

sitivecompressiv

estrainisnegativ

e

12 Advances in Materials Science and Engineering

(2) All of the CTST supports perform elastic duringthe experiment The higher steel ratio and concreteinside the larger stiffness of CTST obtained

(3) The cementitious grouted sleeve connection withsuperior flexibility exhibits better resistance to defor-mation

(4) The tensile strain is gradually transformed into com-pressive strain along the direction of vault to thefoot in the outer edge The inner edges of the CTSTsupports are all in compression The absolute strainvalues of vault connections and tube foot are larger

(5) The mechanical behaviors of CTST supports in thetunnel are analyzed with ABAQUS software packageThe analysis results agree well with the test resultsThe maximum error is 102 The model and theparameters chosen are relatively reasonable and couldbe used for the structural analysis of the similarsupporting projects

Conflict of Interests

The authors declare that they have no conflict of interests

References

[1] M Elchalakani and X-L Zhao ldquoConcrete-filled cold-formedcircular steel tubes subjected to variable amplitude cyclic purebendingrdquo Engineering Structures vol 30 no 2 pp 287ndash2992008

[2] M V Chitawadagi and M C Narasimhan ldquoStrength deforma-tion behaviour of circular concrete filled steel tubes subjected topure bendingrdquo Journal of Constructional Steel Research vol 65no 8-9 pp 1836ndash1845 2009

[3] Y-F An C Roeder and L-H Han ldquoFlexural performanceof concrete-encased concrete-filled steel tubesrdquo Magazine ofConcrete Research vol 66 no 5-6 pp 249ndash267 2014

[4] L-H Han S-H He and F-Y Liao ldquoPerformance and calcula-tions of concrete filled steel tubes (CFST) under axial tensionrdquoJournal of Constructional Steel Research vol 67 no 11 pp 1699ndash1709 2011

[5] W Li Q Wang D Wang et al ldquoExperimental study on shortcolumns under axial load of U-type confined concrete archcentering and its application in minerdquo Journal of Mining ampSafety Engineering vol 31 no 1 pp 1ndash9 2014 (Chinese)

[6] A-Y Jiang J Chen and W-L Jin ldquoExperimental investigationand design of thin-walled concrete-filled steel tubes subject tobendingrdquoThin-Walled Structures vol 63 pp 44ndash50 2013

[7] B Uy ldquoStrength of concrete filled steel box columns incorporat-ing local bucklingrdquo Journal of Structural Engineering vol 126no 3 pp 341ndash352 2000

[8] M Mursi and B Uy ldquoStrength of concrete filled steel boxcolumns incorporating interaction bucklingrdquo Journal of Struc-tural Engineering vol 129 no 5 pp 626ndash639 2003

Submit your manuscripts athttpwwwhindawicom

ScientificaHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

CorrosionInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Polymer ScienceInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

CeramicsJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

CompositesJournal of

NanoparticlesJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

International Journal of

Biomaterials

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

NanoscienceJournal of

TextilesHindawi Publishing Corporation httpwwwhindawicom Volume 2014

Journal of

NanotechnologyHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal of

CrystallographyJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

CoatingsJournal of

Advances in

Materials Science and EngineeringHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Smart Materials Research

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

MetallurgyJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

BioMed Research International

MaterialsJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Nano

materials

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal ofNanomaterials

Advances in Materials Science and Engineering 9

0 50 100 150 2000

5

10

15

20

25

30

35

40

45

50

Load

(kN

m)

(120583120576)

ST-1ST-2ST-3

ST-4ST-5

(a) D1

0

5

10

15

20

25

30

35

40

45

50

Load

(kN

m)

(120583120576)

ST-1ST-2ST-3

ST-4ST-5

0minus50minus100minus150minus200minus250

(b) D2

(120583120576)

ST-1ST-2ST-3

ST-4ST-5

0minus50minus100minus150minus250 minus2000

5

10

15

20

25

30

35

40

45

50

Load

(kN

m)

(c) D3

0

5

10

15

20

25

30

35

40

45

50

Load

(kN

m)

(120583120576)

ST-1ST-2ST-3

ST-4ST-5

0minus50minus100minus150minus250 minus200

(d) D4

Figure 16 Load-strain curves at the connections of the CTST supports

ST-1 ST-2 ST-3 ST-4 ST-5

1172 1242 1284 1313 2003 18521795 17621758 1797

minus1229 minus929 minus1253 minus1412minus1463

minus1974minus1885

minus963

minus1905minus1873

minus1062

minus1995minus1942

minus1037

minus1495minus145

minus663

minus1795minus175

minus97

Figure 17 Strain distribution curves in the outer edge of the CTST supports

10 Advances in Materials Science and Engineering

ST-1 ST-2 ST-3 ST-4 ST-5

minus2134 minus1645 minus2175 minus2237 minus2361

minus2302minus2285

minus2315

minus2465 minus238

minus1796minus1555

minus1935

minus2059 minus2503

minus1964

minus1499

minus1758

minus1883minus2243

minus1396

minus1094

minus1285

minus1785minus192

minus2095

minus1562

minus1881

minus1956 minus2408

Figure 18 Strain distribution curves in the inner edge of the CTST supports

(a) The whole mesh of tunnel

X

Y

Z

(b) Lining and supportmesh

Figure 19 Mesh of steel tube model

ST-1 ST-2 ST-3

1853 1348 1434

minus1337

minus1858

minus108

minus989

minus133

minus722

minus1354

minus1912

minus1034

Figure 20 Strain distribution curves in the outer edge of the CTST supports

ST-1 ST-2 ST-3

minus2303

minus1003

minus1479

minus1913 minus2473

minus1854

minus1447

minus2337minus1714

minus1474

minus2153

minus2527

Figure 21 Strain distribution curves in the inner edge of the CTST supports

Advances in Materials Science and Engineering 11

Table3Com

paris

onof

them

axim

alstr

ainbetweenFE

Aandtestresults

Locatio

nSpecim

enST

-1ST

-2ST

-3120576

119879120576

FEM(|120576

FEMminus120576

119879|120576

FEM)times100120576

119879120576

FEM(|120576

FEMminus120576

119879|120576

FEM)times100120576

119879120576

FEM(|120576

FEMminus120576

119879|120576

FEM)times100

Theo

uter

edge

Vault

1797

1853

30

1242

1348

79

1313

1434

84

Largestcorner

minus97minus108

102

minus663minus722

82

minus1037minus1034

30

Topof

thes

traightw

allminus175minus1858

58

minus145minus133

90

minus1942minus1912

16

Foot

minus1229minus1337

81

minus929minus989

61

minus1253minus1354

75

Theinn

eredge

Vault

minus2408minus2527

47

minus192minus1913

40

minus2243minus2473

93

Largestcornerminus1881minus2153

26

minus1285minus1479

13

minus1758minus1854

52

Topof

thes

traightw

allminus1562minus1474

60

minus1094minus1003

91

minus1499minus1447

36

Foot

minus2134minus2303

73

minus1645minus1714

40

minus2175minus2337

69

Note120576119879means

them

axim

umstr

ainvalueo

fexp

erim

entand120576FE

Mmeans

them

axim

umstr

ainvalueo

fFEM

Tensiles

trainispo

sitivecompressiv

estrainisnegativ

e

12 Advances in Materials Science and Engineering

(2) All of the CTST supports perform elastic duringthe experiment The higher steel ratio and concreteinside the larger stiffness of CTST obtained

(3) The cementitious grouted sleeve connection withsuperior flexibility exhibits better resistance to defor-mation

(4) The tensile strain is gradually transformed into com-pressive strain along the direction of vault to thefoot in the outer edge The inner edges of the CTSTsupports are all in compression The absolute strainvalues of vault connections and tube foot are larger

(5) The mechanical behaviors of CTST supports in thetunnel are analyzed with ABAQUS software packageThe analysis results agree well with the test resultsThe maximum error is 102 The model and theparameters chosen are relatively reasonable and couldbe used for the structural analysis of the similarsupporting projects

Conflict of Interests

The authors declare that they have no conflict of interests

References

[1] M Elchalakani and X-L Zhao ldquoConcrete-filled cold-formedcircular steel tubes subjected to variable amplitude cyclic purebendingrdquo Engineering Structures vol 30 no 2 pp 287ndash2992008

[2] M V Chitawadagi and M C Narasimhan ldquoStrength deforma-tion behaviour of circular concrete filled steel tubes subjected topure bendingrdquo Journal of Constructional Steel Research vol 65no 8-9 pp 1836ndash1845 2009

[3] Y-F An C Roeder and L-H Han ldquoFlexural performanceof concrete-encased concrete-filled steel tubesrdquo Magazine ofConcrete Research vol 66 no 5-6 pp 249ndash267 2014

[4] L-H Han S-H He and F-Y Liao ldquoPerformance and calcula-tions of concrete filled steel tubes (CFST) under axial tensionrdquoJournal of Constructional Steel Research vol 67 no 11 pp 1699ndash1709 2011

[5] W Li Q Wang D Wang et al ldquoExperimental study on shortcolumns under axial load of U-type confined concrete archcentering and its application in minerdquo Journal of Mining ampSafety Engineering vol 31 no 1 pp 1ndash9 2014 (Chinese)

[6] A-Y Jiang J Chen and W-L Jin ldquoExperimental investigationand design of thin-walled concrete-filled steel tubes subject tobendingrdquoThin-Walled Structures vol 63 pp 44ndash50 2013

[7] B Uy ldquoStrength of concrete filled steel box columns incorporat-ing local bucklingrdquo Journal of Structural Engineering vol 126no 3 pp 341ndash352 2000

[8] M Mursi and B Uy ldquoStrength of concrete filled steel boxcolumns incorporating interaction bucklingrdquo Journal of Struc-tural Engineering vol 129 no 5 pp 626ndash639 2003

Submit your manuscripts athttpwwwhindawicom

ScientificaHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

CorrosionInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Polymer ScienceInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

CeramicsJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

CompositesJournal of

NanoparticlesJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

International Journal of

Biomaterials

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

NanoscienceJournal of

TextilesHindawi Publishing Corporation httpwwwhindawicom Volume 2014

Journal of

NanotechnologyHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal of

CrystallographyJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

CoatingsJournal of

Advances in

Materials Science and EngineeringHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Smart Materials Research

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

MetallurgyJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

BioMed Research International

MaterialsJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Nano

materials

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal ofNanomaterials

10 Advances in Materials Science and Engineering

ST-1 ST-2 ST-3 ST-4 ST-5

minus2134 minus1645 minus2175 minus2237 minus2361

minus2302minus2285

minus2315

minus2465 minus238

minus1796minus1555

minus1935

minus2059 minus2503

minus1964

minus1499

minus1758

minus1883minus2243

minus1396

minus1094

minus1285

minus1785minus192

minus2095

minus1562

minus1881

minus1956 minus2408

Figure 18 Strain distribution curves in the inner edge of the CTST supports

(a) The whole mesh of tunnel

X

Y

Z

(b) Lining and supportmesh

Figure 19 Mesh of steel tube model

ST-1 ST-2 ST-3

1853 1348 1434

minus1337

minus1858

minus108

minus989

minus133

minus722

minus1354

minus1912

minus1034

Figure 20 Strain distribution curves in the outer edge of the CTST supports

ST-1 ST-2 ST-3

minus2303

minus1003

minus1479

minus1913 minus2473

minus1854

minus1447

minus2337minus1714

minus1474

minus2153

minus2527

Figure 21 Strain distribution curves in the inner edge of the CTST supports

Advances in Materials Science and Engineering 11

Table3Com

paris

onof

them

axim

alstr

ainbetweenFE

Aandtestresults

Locatio

nSpecim

enST

-1ST

-2ST

-3120576

119879120576

FEM(|120576

FEMminus120576

119879|120576

FEM)times100120576

119879120576

FEM(|120576

FEMminus120576

119879|120576

FEM)times100120576

119879120576

FEM(|120576

FEMminus120576

119879|120576

FEM)times100

Theo

uter

edge

Vault

1797

1853

30

1242

1348

79

1313

1434

84

Largestcorner

minus97minus108

102

minus663minus722

82

minus1037minus1034

30

Topof

thes

traightw

allminus175minus1858

58

minus145minus133

90

minus1942minus1912

16

Foot

minus1229minus1337

81

minus929minus989

61

minus1253minus1354

75

Theinn

eredge

Vault

minus2408minus2527

47

minus192minus1913

40

minus2243minus2473

93

Largestcornerminus1881minus2153

26

minus1285minus1479

13

minus1758minus1854

52

Topof

thes

traightw

allminus1562minus1474

60

minus1094minus1003

91

minus1499minus1447

36

Foot

minus2134minus2303

73

minus1645minus1714

40

minus2175minus2337

69

Note120576119879means

them

axim

umstr

ainvalueo

fexp

erim

entand120576FE

Mmeans

them

axim

umstr

ainvalueo

fFEM

Tensiles

trainispo

sitivecompressiv

estrainisnegativ

e

12 Advances in Materials Science and Engineering

(2) All of the CTST supports perform elastic duringthe experiment The higher steel ratio and concreteinside the larger stiffness of CTST obtained

(3) The cementitious grouted sleeve connection withsuperior flexibility exhibits better resistance to defor-mation

(4) The tensile strain is gradually transformed into com-pressive strain along the direction of vault to thefoot in the outer edge The inner edges of the CTSTsupports are all in compression The absolute strainvalues of vault connections and tube foot are larger

(5) The mechanical behaviors of CTST supports in thetunnel are analyzed with ABAQUS software packageThe analysis results agree well with the test resultsThe maximum error is 102 The model and theparameters chosen are relatively reasonable and couldbe used for the structural analysis of the similarsupporting projects

Conflict of Interests

The authors declare that they have no conflict of interests

References

[1] M Elchalakani and X-L Zhao ldquoConcrete-filled cold-formedcircular steel tubes subjected to variable amplitude cyclic purebendingrdquo Engineering Structures vol 30 no 2 pp 287ndash2992008

[2] M V Chitawadagi and M C Narasimhan ldquoStrength deforma-tion behaviour of circular concrete filled steel tubes subjected topure bendingrdquo Journal of Constructional Steel Research vol 65no 8-9 pp 1836ndash1845 2009

[3] Y-F An C Roeder and L-H Han ldquoFlexural performanceof concrete-encased concrete-filled steel tubesrdquo Magazine ofConcrete Research vol 66 no 5-6 pp 249ndash267 2014

[4] L-H Han S-H He and F-Y Liao ldquoPerformance and calcula-tions of concrete filled steel tubes (CFST) under axial tensionrdquoJournal of Constructional Steel Research vol 67 no 11 pp 1699ndash1709 2011

[5] W Li Q Wang D Wang et al ldquoExperimental study on shortcolumns under axial load of U-type confined concrete archcentering and its application in minerdquo Journal of Mining ampSafety Engineering vol 31 no 1 pp 1ndash9 2014 (Chinese)

[6] A-Y Jiang J Chen and W-L Jin ldquoExperimental investigationand design of thin-walled concrete-filled steel tubes subject tobendingrdquoThin-Walled Structures vol 63 pp 44ndash50 2013

[7] B Uy ldquoStrength of concrete filled steel box columns incorporat-ing local bucklingrdquo Journal of Structural Engineering vol 126no 3 pp 341ndash352 2000

[8] M Mursi and B Uy ldquoStrength of concrete filled steel boxcolumns incorporating interaction bucklingrdquo Journal of Struc-tural Engineering vol 129 no 5 pp 626ndash639 2003

Submit your manuscripts athttpwwwhindawicom

ScientificaHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

CorrosionInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Polymer ScienceInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

CeramicsJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

CompositesJournal of

NanoparticlesJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

International Journal of

Biomaterials

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

NanoscienceJournal of

TextilesHindawi Publishing Corporation httpwwwhindawicom Volume 2014

Journal of

NanotechnologyHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal of

CrystallographyJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

CoatingsJournal of

Advances in

Materials Science and EngineeringHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Smart Materials Research

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

MetallurgyJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

BioMed Research International

MaterialsJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Nano

materials

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal ofNanomaterials

Advances in Materials Science and Engineering 11

Table3Com

paris

onof

them

axim

alstr

ainbetweenFE

Aandtestresults

Locatio

nSpecim

enST

-1ST

-2ST

-3120576

119879120576

FEM(|120576

FEMminus120576

119879|120576

FEM)times100120576

119879120576

FEM(|120576

FEMminus120576

119879|120576

FEM)times100120576

119879120576

FEM(|120576

FEMminus120576

119879|120576

FEM)times100

Theo

uter

edge

Vault

1797

1853

30

1242

1348

79

1313

1434

84

Largestcorner

minus97minus108

102

minus663minus722

82

minus1037minus1034

30

Topof

thes

traightw

allminus175minus1858

58

minus145minus133

90

minus1942minus1912

16

Foot

minus1229minus1337

81

minus929minus989

61

minus1253minus1354

75

Theinn

eredge

Vault

minus2408minus2527

47

minus192minus1913

40

minus2243minus2473

93

Largestcornerminus1881minus2153

26

minus1285minus1479

13

minus1758minus1854

52

Topof

thes

traightw

allminus1562minus1474

60

minus1094minus1003

91

minus1499minus1447

36

Foot

minus2134minus2303

73

minus1645minus1714

40

minus2175minus2337

69

Note120576119879means

them

axim

umstr

ainvalueo

fexp

erim

entand120576FE

Mmeans

them

axim

umstr

ainvalueo

fFEM

Tensiles

trainispo

sitivecompressiv

estrainisnegativ

e

12 Advances in Materials Science and Engineering

(2) All of the CTST supports perform elastic duringthe experiment The higher steel ratio and concreteinside the larger stiffness of CTST obtained

(3) The cementitious grouted sleeve connection withsuperior flexibility exhibits better resistance to defor-mation

(4) The tensile strain is gradually transformed into com-pressive strain along the direction of vault to thefoot in the outer edge The inner edges of the CTSTsupports are all in compression The absolute strainvalues of vault connections and tube foot are larger

(5) The mechanical behaviors of CTST supports in thetunnel are analyzed with ABAQUS software packageThe analysis results agree well with the test resultsThe maximum error is 102 The model and theparameters chosen are relatively reasonable and couldbe used for the structural analysis of the similarsupporting projects

Conflict of Interests

The authors declare that they have no conflict of interests

References

[1] M Elchalakani and X-L Zhao ldquoConcrete-filled cold-formedcircular steel tubes subjected to variable amplitude cyclic purebendingrdquo Engineering Structures vol 30 no 2 pp 287ndash2992008

[2] M V Chitawadagi and M C Narasimhan ldquoStrength deforma-tion behaviour of circular concrete filled steel tubes subjected topure bendingrdquo Journal of Constructional Steel Research vol 65no 8-9 pp 1836ndash1845 2009

[3] Y-F An C Roeder and L-H Han ldquoFlexural performanceof concrete-encased concrete-filled steel tubesrdquo Magazine ofConcrete Research vol 66 no 5-6 pp 249ndash267 2014

[4] L-H Han S-H He and F-Y Liao ldquoPerformance and calcula-tions of concrete filled steel tubes (CFST) under axial tensionrdquoJournal of Constructional Steel Research vol 67 no 11 pp 1699ndash1709 2011

[5] W Li Q Wang D Wang et al ldquoExperimental study on shortcolumns under axial load of U-type confined concrete archcentering and its application in minerdquo Journal of Mining ampSafety Engineering vol 31 no 1 pp 1ndash9 2014 (Chinese)

[6] A-Y Jiang J Chen and W-L Jin ldquoExperimental investigationand design of thin-walled concrete-filled steel tubes subject tobendingrdquoThin-Walled Structures vol 63 pp 44ndash50 2013

[7] B Uy ldquoStrength of concrete filled steel box columns incorporat-ing local bucklingrdquo Journal of Structural Engineering vol 126no 3 pp 341ndash352 2000

[8] M Mursi and B Uy ldquoStrength of concrete filled steel boxcolumns incorporating interaction bucklingrdquo Journal of Struc-tural Engineering vol 129 no 5 pp 626ndash639 2003

Submit your manuscripts athttpwwwhindawicom

ScientificaHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

CorrosionInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Polymer ScienceInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

CeramicsJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

CompositesJournal of

NanoparticlesJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

International Journal of

Biomaterials

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

NanoscienceJournal of

TextilesHindawi Publishing Corporation httpwwwhindawicom Volume 2014

Journal of

NanotechnologyHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal of

CrystallographyJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

CoatingsJournal of

Advances in

Materials Science and EngineeringHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Smart Materials Research

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

MetallurgyJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

BioMed Research International

MaterialsJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Nano

materials

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal ofNanomaterials

12 Advances in Materials Science and Engineering

(2) All of the CTST supports perform elastic duringthe experiment The higher steel ratio and concreteinside the larger stiffness of CTST obtained

(3) The cementitious grouted sleeve connection withsuperior flexibility exhibits better resistance to defor-mation

(4) The tensile strain is gradually transformed into com-pressive strain along the direction of vault to thefoot in the outer edge The inner edges of the CTSTsupports are all in compression The absolute strainvalues of vault connections and tube foot are larger

(5) The mechanical behaviors of CTST supports in thetunnel are analyzed with ABAQUS software packageThe analysis results agree well with the test resultsThe maximum error is 102 The model and theparameters chosen are relatively reasonable and couldbe used for the structural analysis of the similarsupporting projects

Conflict of Interests

The authors declare that they have no conflict of interests

References

[1] M Elchalakani and X-L Zhao ldquoConcrete-filled cold-formedcircular steel tubes subjected to variable amplitude cyclic purebendingrdquo Engineering Structures vol 30 no 2 pp 287ndash2992008

[2] M V Chitawadagi and M C Narasimhan ldquoStrength deforma-tion behaviour of circular concrete filled steel tubes subjected topure bendingrdquo Journal of Constructional Steel Research vol 65no 8-9 pp 1836ndash1845 2009

[3] Y-F An C Roeder and L-H Han ldquoFlexural performanceof concrete-encased concrete-filled steel tubesrdquo Magazine ofConcrete Research vol 66 no 5-6 pp 249ndash267 2014

[4] L-H Han S-H He and F-Y Liao ldquoPerformance and calcula-tions of concrete filled steel tubes (CFST) under axial tensionrdquoJournal of Constructional Steel Research vol 67 no 11 pp 1699ndash1709 2011

[5] W Li Q Wang D Wang et al ldquoExperimental study on shortcolumns under axial load of U-type confined concrete archcentering and its application in minerdquo Journal of Mining ampSafety Engineering vol 31 no 1 pp 1ndash9 2014 (Chinese)

[6] A-Y Jiang J Chen and W-L Jin ldquoExperimental investigationand design of thin-walled concrete-filled steel tubes subject tobendingrdquoThin-Walled Structures vol 63 pp 44ndash50 2013

[7] B Uy ldquoStrength of concrete filled steel box columns incorporat-ing local bucklingrdquo Journal of Structural Engineering vol 126no 3 pp 341ndash352 2000

[8] M Mursi and B Uy ldquoStrength of concrete filled steel boxcolumns incorporating interaction bucklingrdquo Journal of Struc-tural Engineering vol 129 no 5 pp 626ndash639 2003

Submit your manuscripts athttpwwwhindawicom

ScientificaHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

CorrosionInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Polymer ScienceInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

CeramicsJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

CompositesJournal of

NanoparticlesJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

International Journal of

Biomaterials

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

NanoscienceJournal of

TextilesHindawi Publishing Corporation httpwwwhindawicom Volume 2014

Journal of

NanotechnologyHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal of

CrystallographyJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

CoatingsJournal of

Advances in

Materials Science and EngineeringHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Smart Materials Research

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

MetallurgyJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

BioMed Research International

MaterialsJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Nano

materials

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal ofNanomaterials

Submit your manuscripts athttpwwwhindawicom

ScientificaHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

CorrosionInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Polymer ScienceInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

CeramicsJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

CompositesJournal of

NanoparticlesJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

International Journal of

Biomaterials

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

NanoscienceJournal of

TextilesHindawi Publishing Corporation httpwwwhindawicom Volume 2014

Journal of

NanotechnologyHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal of

CrystallographyJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

CoatingsJournal of

Advances in

Materials Science and EngineeringHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Smart Materials Research

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

MetallurgyJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

BioMed Research International

MaterialsJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Nano

materials

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal ofNanomaterials