Pilot Implementation Using Geofoam for Repair of Bridge Approach Slabs

Anand J. Puppala, Ph.D., P.E., DGE, F.ASCE Distinguished Professor, Dept. of Civil Engineering

Director, Sustainable and Resilient Civil Infrastructure (SARCI) Center The University of Texas at Arlington (UTA)

www.uta.edu/sarci

SARCI

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Courtesy: URETEK

Bump at the End of Bridge 40% TxDOT Bridges Have Bump Issues Annual Maintenance Costs - $7 Millions – Seo (2003)

Bump at the end of the bridge

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Foundation Soils Embankment backfill materials

1. Excavation and replacement 1. Geosynthetic reinforcement

2. Preloading surcharge loads 2. Use of MSE wall

3. Vertical drains 3. Grouting

4. Stone columns 4. Use of lightweight fill materials.

5. Deep soil mixing others

others

Lightweight Materials

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Use of lightweight fill materials for mitigating bridge approach settlement:

Lightweight Materials

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Densities and approximate costs of various lightweight fill materials (FHWA NHI-05-037)

Materials Density Approximate cost

kg/m3 lb/ft3 $/m3 $/ft3

EPS geofoam 12 to 46 0.75 to 2.85 40 to 85 1.2 to 2.4

Cellular (foamed) concrete 320 to 970 20.0 to 60.5 40 to 55 1.2 to 1.6

Shredded tires 600 to 900 37.5 to 56.2 20 to 30 0.6 to 0.8

Expanded shale and clay 600 to 1040 37.5 to 65.0 40 to 55 1.2 to 1.6

EPS Geofoam

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Expanded Polystyrene (EPS) Geofoam:

ASTM D-4439: a block or planar rigid cellular foamed polymeric material used in geotechnical engineering applications.

It has been widely used around the world as a fill material for more than 30 years.

EPS Geofoam

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Advantages of EPS Geofoam:

About 100 times lighter than soils.

At least 20 to 30 times lighter than other lightweight fill alternatives.

Easy to handle

Expedites construction process

Limited labor

EPS Geofoam

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Advantages of EPS Geofoam:

About 100 times lighter than soils.

At least 20 to 30 times lighter than other lightweight fill alternatives.

Easy to handle

Expedites construction process

Limited labor

Implementation of EPS Geofoam

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Location: US 67 bridge over SH 174, Johnson County, Cleburne, Texas

Implementation of EPS Geofoam Bump at the end of the bridge:

• Test Section - US 67 over SH 174 in Johnson County, Texas

• Abutments supported by drilled shaft foundation

• More than 17 in. of settlement observed since

construction in 1995

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Geofoam Construction

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EPS 22 geofoam blocks: top 6 ft depth

Geofoam installation period: 3-4 days

Test section construction period: January – February 2012

Geofoam Installation

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Process of EPS geofoam installation

Geofoam – Lightweight Fill Material Instrumentation- Horizontal Inclinometers, Pressure Cells

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PC #1 PC #2

PC #3 PC #4

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Site Visit and Data Collection

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The site visits have been conducted at least once a month from January 2012.

During the visit, the data from horizontal inclinometers and pressure cells are measured and recorded.

Site Visit and Data Collection

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0 2 4 6 8 10 12 14 16 18 20 22

Length of

inclinometer casing

in

feet

-0.50

-0.25

0.00

0.25

0.50

0.75

1.00

1.25

1.50

1.75

Cum

u la t

ive D

ispl

acem

ent (in

) from

1 /30

/201

2 01/30/1202/07/1202/14/1203/06/1204/18/1205/23/1206/20/1207/20/1208/29/1211/30/1212/21/1201/13/1302/17/1303/11/1304/13/1305/20/1306/18/1307/19/1308/21/1309/19/1310/18/1312/05/1301/16/1402/14/1403/21/1404/18/1405/23/1406/17/1407/18/1408/15/14

US 67_1

0 2 4 6 8 10 12 14 16 18 20 22

Len th of

inclinometer casin

in

feet

-0.50

-0.25

0.00

0.25

0.50

0.75

1.00

1.25

1.50

1.75

Cum

u la t

ive D

ispl

acem

ent (in

) from

1 /30

/201

2 01/30/1202/07/1202/14/1203/06/1204/18/1205/23/1206/20/1207/20/1208/29/1211/30/1201/13/1302/17/1303/11/1304/13/1305/20/1306/18/1307/19/1308/21/1309/19/1310/18/1306/17/1407/18/1408/15/14

US 67_2

0 2 4 6 8 10 12 14 16 18 20 22

Len th of

inclinometer casin

in

feet

-0.50

-0.25

0.00

0.25

0.50

0.75

1.00

1.25

1.50

1.75

Cum

u la t

ive D

ispl

acem

ent (in

) from

1 /30

/201

2 01/30/1202/07/1202/14/1203/06/1204/18/1205/23/1206/20/1207/20/1208/29/1211/30/1202/17/1303/11/1304/13/1305/20/1306/18/1307/19/1308/21/1309/19/1310/18/1312/05/1301/16/1402/14/1403/21/1404/18/1405/23/1406/17/1407/18/1408/15/14

US 67_3

0 2 4 6 8 10 12 14 16 18 20 22

Length of

inclinometer casing

in

feet

-0.50

-0.25

0.00

0.25

0.50

0.75

1.00

1.25

1.50

1.75C

umu l

a tiv

e Dis

pla c

emen

t (in) fr

om 1 /

3 0/2

012 01/30/12

02/07/1202/14/1203/06/1204/18/1205/23/1206/20/1207/20/1208/29/1211/30/1201/13/1302/17/1303/11/1304/13/1305/20/1306/18/1307/19/1308/21/1309/19/1310/18/1312/05/1301/16/1402/14/1403/21/1404/18/1405/23/1406/17/1407/18/1408/15/14

US 67_4

Site Visit and Data Collection

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• PC #1 and PC #2 were installed horizontally at 2 ft. (0.6 m) and 8 ft. (2.4 m) under the pavement surface.

• The data presented in the plots was collected from March 2015 Time (Month-Year)

0

2

4

6

8

Pres

sure

(psi

)

PC #1PC #2

Mar-15 Apr-15 May-15 Jun-15 Jul-15 Aug-15

Prediction of a Long Term Settlement of the Test Embankment: Predicted from the collected field data. Using Hyperbolic method (Lin and Wong, 1999). The hyperbolic relationship between the settlement and time:

𝒕 = time from the start of embankment fill (days); 𝑺 = measured settlement as any specific time (mm);

𝜷 = gradient of the straight line between 𝒕 and 𝒕𝑺 ; and

𝜶 = intersection of the straight line on the 𝒕𝑺 axis.

𝒕𝑺 = 𝜶 + 𝜷(𝒕) or 𝑺 = 𝒕

(𝜶+ 𝜷𝒕)

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Analysis of Field Data

Prediction of a Long Term Settlement of the Test Embankment: By plotting the data with the function of time-settlement ratio,

the values of 𝜷 and 𝜶 can be determined.

0 100 200 300 400 500 600 700 800 900 1000

Time da s

0.0

5.0

10.0

15.0

20.0

25.0

30.0

35.0

Tim

e /Se

ttlem

ent (d

a ys /

mm

)

Substituting 𝜷 and 𝜶 back

into the Equation 𝑺 = 𝒕(𝜶+ 𝜷𝒕)

,

the settlement at several times can be calculate and the plot between the settlement and time can be provided.

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Analysis of Field Data

Prediction of Long Term Settlement

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SARCI The total settlements of 1.42 in. and 1.50 in. are

predicted to occur at 10 year and 20-years intervals.

1.6

1.4

1.2

1.0

0.8

0.6

0.4

0.2

0.0

Settl

emen

t (in. )

0 100 200 300 400 500 600 700 800 900 1000Time

(days)

40

35

30

25

20

15

10

5

0

mm

Numerical Modeling of Geofoam Embankment

Geometry of the Test Embankment Section:

Material Properties: • Properties of the embankment fill and foundation soil were derived

from the laboratory test results.

• Properties of EPS 22 geofoam provided in ASTM D 6817-07 were used.

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• The vertical displacement – time plots at points A, B, C, D, and E.

Results of the Numerical Modeling:

• Contours of the total vertical displacement on the EPS geofoam embankment model after full dissipation of pore pressure.

Numerical Modeling of Geofoam Embankment System

1.6

1.4

1.2

1.0

0.8

0.6

0.4

0.2

0.0

Ver t

ica l

Dis

plac

emen

t (inc h

)

0 200 400 600 800 1000 1200Time

(days)

40

35

30

25

20

15

10

5

0

Ver t

ica l

Dis

lace

men

t mm

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Design charts to evaluate minimum thickness of EPS geofoam layer

250 500 750 1,000 1,250 1,500 1,750 2,000 2,250 2,500 2,750

Undrained Shear Stren th, Su

psf

0.0

5.0

10.0

15.0

20.0

25.0

30.0

35.0

40.0

45.0

50.0

Min

imum

Thic

knes

s o f EP

S Geo

foam

Laye

r (ft) 10 20 30 40 50 60 70 80 90 100 110 120 130

Undrained Shear Strength, Su

(kPa)

0.0

1.0

2.03.0

4.0

5.06.0

7.08.09.0

10.0

11.0

12.0

13.0

14.0

15.0

Min

imum

Thic

kne s

s o f E P

S Geo

foam

Laer

m

FS =

1.5FS

= 2.0

FS =

2.5FS

= 3.0

Embakment Height

= 50

ft

Top Width

of Embankment

= 76

ft

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Development of Design Charts

𝑺𝒖 =𝑭𝑺𝟓.𝟏𝟏

[∆𝝈𝒑𝒑𝒑𝒑𝒑𝒑𝒑𝒕 + ∆𝝈𝒕𝒕𝒑𝒕𝒕𝒕𝒕 + ∆𝝈𝒕𝒕𝒇𝒇 𝒑𝒑𝒎𝒎]

∆𝝈𝒑𝒑𝒑𝒑𝒑𝒑𝒑𝒕 = 𝝈𝒐, 𝒑𝒑𝒑𝒑𝒑𝒑𝒑𝒕 𝑾𝑾+ 𝑯𝑬𝒑𝑬.

∆𝝈𝒕𝒕𝒑𝒕𝒕𝒕𝒕 = 𝝈𝒐, 𝒕𝒕𝒑𝒕𝒕𝒕𝒕 𝑾𝑾+ 𝑯𝑬𝒑𝑬.

∆𝝈𝒕𝒕𝒇𝒇 𝒑𝒑𝒎𝒎 = 𝜸𝑬𝑬𝑺 𝑨𝑬𝑬𝑺 + 𝜸𝒕𝒕𝒇𝒇 𝒎𝒐𝒕𝒇 𝑨𝒕𝒕𝒇𝒇 𝒎𝒐𝒕𝒇

𝑾+𝟐 𝑺𝒇𝒐𝒑𝒑 𝑯𝑬𝒑𝑬.

𝑨𝑬𝑬𝑺 = 𝑾 + 𝑺𝒇𝒐𝒑𝒑 𝑯𝑬𝑬𝑺 𝑯𝑬𝑬𝑺

𝑨𝒘𝒘𝒐𝒇𝒑 𝒑𝒑𝑬. = 𝑾 + 𝟐 𝑺𝒇𝒐𝒑𝒑 𝑯𝒑𝒑𝒑𝒑. + 𝑺𝒇𝒐𝒑𝒑 𝑯𝑬𝒑𝑬. 𝑯𝑬𝒑𝑬.

𝑨𝒕𝒕𝒇𝒇 𝒎𝒐𝒕𝒇 = 𝑨𝒘𝒘𝒐𝒇𝒑 𝒑𝒑𝑬. − 𝑨𝑬𝑬𝑺

Design charts to evaluate minimum thickness of EPS geofoam layer (Bearing capacity controls the height of Geofoam)

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Development of Design Charts

Comparisons of the thickness of EPS geofoam layer

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Long Term Assessments

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Long Term Assessments

Acknowledgements • TxDOT: Richard

Williammee, Jimmy Si, Wade Blackmon

• RTI Office – Joe Adams, Sonya Badgely and Wade Odell

• UTA Geotech Research Group

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