InfluenceofLooselyBoundWateronCompressibilityof …downloads.hindawi.com/journals/ace/2020/1496241.pdf · 2020-02-22 · thatC c wasrelatedtothespeciﬁcsurfaceareaofsoilpar- ticles

Research ArticleInfluence of Loosely Bound Water on Compressibility ofCompacted Fine-Grained Soils

Rui Zhang 12 Mengli Wu2 Prince Kumar3 and Qian-Feng Gao 12

1National Engineering Laboratory of Highway Maintenance Technology Changsha University of Science amp TechnologyChangsha 410114 China2School of Traffic amp Transportation Engineering Changsha University of Science amp Technology Changsha 410114 China3Graduate Research Assistant Zachry Department of Civil amp Environment Engineering Texas AampMUniversity College StationTexas 77843 USA

Correspondence should be addressed to Rui Zhang zrcsusteducn

Received 24 August 2019 Revised 31 December 2019 Accepted 3 February 2020 Published 22 February 2020

Academic Editor Claudia Vitone

Copyright copy 2020 Rui Zhang et al (is 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

(is study aimed to investigate the influence of loosely bound water (LBW) on the compressibility of compacted fine-grained soilsand accurately determine the soilrsquos compression index Four fine-grained soils (ie heavy clay heavy silt lean clay and lean silt)and a coarse-grained soil were examined (e volumetric flask method was used to measure the LBW contents of the five soilsX-ray diffraction (XRD) analysis was then performed to test the mineral compositions and help explain the reason why the LBWcontent varied between different soils A concept of modified void ratio was proposed by assuming that LBW is a part of the solidphase in soil Subsequently consolidation tests and permeability tests were conducted on saturated compacted specimens (eresults show that the compression indexes or permeability coefficients tend to be the same for the soils with identical initialmodified void ratios Consolidation tests were also carried out on the unsaturated compacted heavy silt of four different drydensities prepared at a water content higher than the optimum(ey show that the compression of unsaturated soil occurs if poreair is discharged when the water content is less than the LBW content (is confirms the previous assumption that LBW can beregarded as a part of the soil solid phase Amodified compression index was deduced and implemented to predict the settlement ofa road embankment (e result suggests that the modified compression index is capable of calculating the compression of fine-grained soils whose water contents are higher than their LBW contents

1 Introduction

Fine-grained soils are commonly encountered in the practiceof geotechnical engineering making it crucial to understandand predict their engineering behaviors which are stronglydependent on water contents Previous studies have shownthat the water-holding capacity of soil affects its compressioncharacteristics [1 2] and the loosely bound water (LBW)the main form of water in fine-grained soil [3 4] affects themicrostructure during the compression process Soil com-pression characteristics have consistently been the focus ofattention in engineering design and construction as thepostconstruction soil settlement significantly affects thesafety and stability of superstructures (erefore it is

theoretically and practically important to study the effect ofLBW on soil compression characteristics

(e compression of soil is a process that involves thedissipation of pore water and air particle movements andincreased densities under the actions of loads [5] (e soilcompressibility can be characterized by the compressionindex (Cc) An accurate determination of Cc is required for abetter understanding of the mechanical properties of soil(e void ratio that greatly affects the compression process ofsoil is a key parameter in the determination of Cc [6 7]Petersen et al [8] found that the Cc value of clay was smallerthan that of silt at the same initial void ratio Chu et al [9]pointed out that the mineral composition of soil affected thesoil compressibility Sridharan and Jayadeva [10] presented

HindawiAdvances in Civil EngineeringVolume 2020 Article ID 1496241 14 pageshttpsdoiorg10115520201496241

that Cc was related to the specific surface area of soil par-ticles In the literature many experimental and micro-structural observations revealed that the consolidation andcompression processes of soil were also affected by LBW[11 12] According to the diffuse-electric double layer(DDL) theory [13] the water in soil can be classified intothree types ie tightly bound water (TBW) LBW and freewater TBW is tightly adsorbed on the surfaces of soilparticles and it gradually turns into LBW with weakeningaction of the electric double layer TBW has a strong vis-cosity and cannot be removed entirely from the surfaces ofsoil particles until the soil temperature is raised up to 200degCBecause of its unique properties TBW is generally incor-porated as a part of soil particles in calculations [14]

Many studies including nanoscale observations haverevealed that the density of LBWwas higher than that of freewater [15ndash17] It was found that the LBW content of fine-grained soils was generally between 03 and 50 and theLBW density ranged from 115 gcm3 to 1872 gcm3

[14 18 19] and gradually became lower as the distance fromthe particle surface increased [20] (e montmorillonitecontent of soil also greatly affected the content and density ofLBW [21ndash24] Various studies reported different values forthe LBW density but failed to suggest a fixed value LBWcould be converted into free water at temperatures above50degC [17] By oedometer tests Shang et al [25] observed thatthe soil water content approximated the LBW content at aconsolidation pressure of 2MPa Furthermore many re-searchers found that the DDL efficiently explained theconsolidation behavior of soil [26ndash29] (e isomorphoussubstitution of clay minerals occurs easily in fine-grainedsoils and low valence ions replace high valence ionsresulting in a loss of positive and negative charges on thesurfaces of clay minerals Cations and dipole water mole-cules are adsorbed on the surfaces of soil particles due tostatic electricity which cannot easily discharge under ex-ternal forces [18] In the process of consolidation the ex-istence of the LBW film greatly reduces the soil permeability

To the best of our knowledge few studies have addressedthe effect of LBW on the compressibility of soil (ereforeone objective of this study was to determine the LBWcontents of different fine-grained soils using the volumetricflask method and then to analyze the effects of LBW on theconsolidation characteristics of soil specimens (e secondobjective was to propose a modified mathematical equationfor the void ratio considering the LBW effects Subsequentlythe modified compression index (Cc

prime) was calculated by theproposed equation and compared with the conventional Ccvalue and the theoretical value determined based on thework of Sridharan and Jayadeva [10] Finally the settlementof a road embankment was predicted using Cc

prime and verifiedwith field data

2 Modification of Void Ratio

Since LBW is usually hard to remove from soil [25 30] it canbe regarded as a part of the solid phase in soil when the watercontent is greater than the LBW content In this study theassumption is also made to deduce the modified void ratio

(us the three-phase structure of soil can be illustrated inFigure 1 (e LBW content is defined as

wg mg

ms

(1)

where wg is the LBW content mg is the LBWmass andms isthe solid mass of soil

(en the volume of LBW can be calculated by

Vg mg

ρg

ρs

ρg

Vs middot wg (2)

where Vg is the LBW volume ρg is the LBW density ρs is thedensity of the soil solid and Vs is the solid volume of the soil

(us the volume of the soil solid phase including LBW(Vsprime) can be calculated by

Vsprime Vs + Vg Vs 1 +

ρs

ρg

wg1113888 1113889 (3)

According to the definition of void ratio the modifiedvoid ratio that takes LBW into account can be calculated by

eprime V

Vsprime minus 1

Vs(e + 1)

Vsprime minus 1 (4)

where eprime is the modified void ratio and V is the total volumeof the soil

Substituting Vsprime from equation (3) into (4) yields the

expression of the modified void ratio

eprime e + 1

1 + ρsρg1113872 1113873wg

minus 1 (5)

3 Experimental Program

31 Soil Samples Four fine-grained soil samples were col-lected from different cities in China Xiangtan DanzhouZhuzhou and Enshi A coarse-grained soil sample was se-lected from Changsha for comparison purposes Particle sizeanalyses Atterberg limit tests and specific gravity tests wereperformed on all of the soil samples (e methylene blueadsorption method was employed to determine the specificsurface area of soil particles [31] (e basic physical prop-erties of the soils are shown in Table 1 (e soil samples wereclassified as per ASTM D2487 Xiangtan soil was heavy clay(CH) Danzhou soil was heavy silt (MH) Zhuzhou soil waslean clay (CL) Enshi soil was lean silt (ML) and Changshasoil was clayey sand (SC)

32 X-Ray Diffraction Tests XRD was used to identify theclay minerals in different soils [32 33] (e collected soilsamples were dried and pulverized to obtain homogeneouspowders (less than 40 μm) and the angle was set from 3deg to80deg (e test results were characterized by the X-ray dif-fraction pattern from which different minerals (eg illitekaolinite montmorillonite and quartz) were identified bymatching the peaks to the known database of minerals (ematching process and the mineral quantification were re-alized using the Match 3 XRD software

2 Advances in Civil Engineering

33 LBW Content Tests (e surfaces of soil particles containhydroxyl and oxide layers Water molecules pass through thehydrogen bonding van der Waals forces ion exchange etcand form a water film when they meet the bound waterResearchers have determined the LBW density at different soilwater contents It was reported that the LBW densities of soilwere 146 gcm3 127 gcm3 and 116 gcm3 at water contentsof 15 28 and 46 respectively [19] Generally in roadembankments the water content is between 15 and 28 forfine-grained soils (us an LBW density of 13 gcm3 whichwas the same as that suggested by Kurichetsky and Li [34] wastentatively assumed in this study Wu [13] proposed thevolumetric flask method to determine the LBW content Inthis method the density of free water in clay is assumed to be10 gcm3 After the free water is transformed into LBW thevolume of water in the volumetric flask shrinks due to theincrease in water density (e LBW content of the sample wascalculated based on the total volume change in the volumetricflask containing the soil and water

(e test mechanism of the volumetric flask method isshown in Figure 2 Two graduated volumetric flasks of255mL capacity were used their accuracy was within005mL To eliminate the influence of water evaporationone flask was used to measure the evaporation loss while theother was used to measure the change in the total volume ofsoil and water (e flasks were cleaned with deaired waterusing an ultrasonic cleaner and then they were oven-dried at

105degC for 12 hours At 25degC temperature the density ofdistilled water was 0997 gcm3 To accurately measure254mL distilled water 25324 g distilled water was put intoone of the volumetric flasks and the water level wasrecorded (is flask was used to measure the evaporationloss (e soil sample was dried at 105degC for 8 hours [14] 20 gdried soil sample was put into a dry flask and a particularvolume of distilled water was slowly poured into it (e flaskwas shaken to remove trapped air bubbles To maintain aconstant temperature both volumetric flasks were placed ina 25degC temperature water bath (e room temperature wasmaintained at about 25degC to avoid any environmental in-fluence For both flasks the liquid level was recorded every24 hours When the change in the liquid level of both flaskswas the same the test was terminated (e above procedurewas followed for all of the soil samples Before testing theLBW content the LBW content of commercial standardsand was tested by this method Test results showed that themeasured LBW content of standard sand was almost zerowhich is consistent with the finding (less than 037) re-ported by Wang et al [14] (is implies that the LBWcontent can be measured by the volumetric flask method

34 Consolidation Tests on Saturated Soils (is section aimsto understand the effect of LBWon the consolidation behaviorof saturated soils One-dimensional consolidation tests were

Tightly bound water and soil particle

Air

Free water

VS

VL

VF

VA

mS

mL

mF

Solid phase

Air phase

Liquid phase VF

VA

mprimeS

mF

Loosely bound water

VV

V

VprimeS

VprimeV

V

Figure 1 (ree-phase schematic diagram of soil considering LBW

Table 1 Physical properties of different soil samples

Collectionsite

Particlecomposition () Specific

surface area(m2middotgminus 1)

Natural watercontent ()

Atterberg limitSpecificgravity

United soilclassification

Clay Silt SandLiquidlimit wl

()

Plasticlimit wp

()

Plasticityindex PI ()

Xiangtan 5080 4098 822 5034 264 699 334 365 271 CHDanzhou 4800 3250 1950 4078 361 572 313 259 273 MHZhuzhou 4041 2452 3507 2691 187 467 236 231 266 CLEnshi 2577 4001 3422 2447 2475 3101 192 1232 275 MLChangsha 776 2012 7212 2039 212 298 156 142 269 SC

Advances in Civil Engineering 3

conducted based on Terzaghirsquos consolidation theory Becausethe maximum dry density and the optimum water content ofthe MH soil were about 161 gcm3 and 230 respectively aninitial void ratio of 081 that corresponded to the void ratio at93 compactness was considered for this type of soil duringspecimen preparation To eliminate the influence of void ratiothe initial void ratio of 081 was also taken for the other foursoils Consolidation tests were conducted with a consolidationring of 20mm in height and 618mm in diameter as per ASTMD2435-11 According to the overburden pressure in the actualembankment a maximum pressure of 400 kPa was consid-ered Loading was applied in a consecutive order of 50 kPa100 kPa 200 kPa 300 kPa and 400 kPa After completion ofthe tests the soil specimens were put in an oven to determinethe water contents

Consolidation tests were also conducted on saturatedsoil samples prepared at an identical modified void ratio (eprime)Note that the tests could not be conducted at 93 com-pactness of the MH soil because the difference in the LBWcontents of different soils would make the dry densities ofother soils especially the SC soil with the lowest LBWcontent too high to be compacted easily resulting in a wasteof materials and increased labor for compaction(erefore amodified void ratio of 033 was used to ensure that the drydensity of the tested soil sample was within the compactnesscommonly used in engineering practice

35 Permeability Tests on Saturated Soils Permeability testswere carried out to evaluate the effect of LBW on the per-meability coefficient in accordance with ASTMD5084(e soilspecimens of CH MH CL ML and SC were prepared con-sidering the same initial void ratio of 081(e specimens of fourfine-grained soils (ie CHMH CL andML) were tested with afalling-head permeability test device the coarse-grained soil(ie SC) was tested with a constant-head permeability testapparatus After considering the LBW content the initial voidratio was modified to 033 for all soil specimens (e samepermeability tests were performed on the new soil specimensthat were 40mm in height and 618mm in diameter After staticcompaction the samples were saturated in vacuum for 24hours and then they were used for permeability tests

36 Consolidation Tests on Unsaturated Soils To investigatethe effect of LBW on the compressibility of unsaturated soilsamples consolidation tests were conducted on the MH soil

Different dry densities (ie 146 gcm3 140 gcm3138 gcm3 and 133 gcm3) and water contents (27 29432 and 34) were considered during specimen prepa-rations and all water contents were on the wet side of theoptimum water content After the soil specimens wereprepared they were sealed and stored in a desiccator for24 hours (e test apparatus and the loading process werethe same as those for the saturated consolidation test andthe tests were conducted as per ASTM D2435-11 To reducethe loss of water due to evaporation the consolidometer wascovered with a wet cloth during each test

4 Results and Discussion

41 Verification of the LBW Density (e LBW density waspreviously assumed to be 13 gcm3 based on the findingsreported in the literature To verify the rationality of theassumption consolidation tests were conducted on satu-rated MH and SC soil specimens with the same initialmodified void ratio (ie 033) (ree LBW densities of12 gcm3 13 gcm3 and 14 gcm3 were considered whencalculating the modified void ratio (e compression of thespecimens with time is illustrated in Figure 3 It is observedthat when the LBW density was assumed to be 12 gcm3 or14 gcm3 the compression curves obviously vary betweendifferent soils By contrast when an LBW density of13 gcm3 was considered the compression curves of dif-ferent soils approximate (is indicates that it is reasonableto assume the LBW density to be 13 gcm3

(erefore equation (5) can be rewritten as

eprime e + 1

1 + ρs13( 1113857wg

minus 1 (6)

42Mineral Compositions ofDifferent Soils (e XRD resultsin Figures 4 and 5 show that the five soil samples all con-tained a large amount of quartz and minor montmorillonitehowever their illite and kaolinite contents were quite dif-ferent And the mineral compositions of all soil samples aresummarized in Table 2

Montmorillonite illite and kaolinite are clay minerals thathave a high affinity for water due to their small particle size andhigh surface activity(is affinity for water can be attributed tohydrogen bonding (oxygen or hydroxyl molecules attract thehydrogen of water) van der Waals attractions and charged

Free water

VF Oven-dried soil VF+LBW+S

VS = (MSρw25degCGS)

Evaporation loss

LBWSoil particle

Free water

∆V

Figure 2 Procedure for measuring the LBW content Note ΔV is the reduction in volume of free water converted to loosely bound waterLBW is the loosely bound water


surface-dipole attractions [35] Among these different types ofbonding hydrogen bonding is the strongest and is consideredto be the primary reason for the swelling of expansive soilsafter water absorption [36] In the clay-water system somewater molecular layers designated as LBW surround clayparticles and are tightly held by clay particle surfaces [37] Inthis study the clay mineral content of CH was higher thanthose of the other soils hence the CH soil had the highestwater-holding capacity

43 LBW Contents of Different Soils (e LBW content wascalculated by the following equation

wg ρgρwt

ρg minus ρwt

middotΔVms

(7)

where ρwt is the bulk density of free water at 25degC and ΔV isthe change in total volume when the water is converted fromfree water to LBW and can be calculated by

ΔV ms

ρs

minus Vt (8)

where Vt is the change in water volume in the volumetricflask

Table 3 shows that the LBW contents of the five soilsamples were different It is observed that the LBW contentincreased with the increasing clay content (is is becauseclay particles have large surface energy and strong bondingcapacity to form bound water Moreover the LBW content(wg) was slightly smaller than the plastic limit (wp) Aprevious study [38] also stated that there was a linearcorrelation between the LBW content and the plastic limit ofsoil (us the following equation was derived by fitting theexperimental data reported in the literature as well as thoseobtained in this study (see Figure 6)

wg 08493wp (9)

(e coefficient of determination of equation (9) isR2 09897 (e determination of the LBW content is time-consuming by laboratory tests thus equation (9) can beused for this purpose

44 Compressibility of Saturated Soils (e relationship be-tween the void ratio e and the overburden pressure p caneffectively predict the settlement of the soil [26] (e e-log pcurves are presented in Figures 7 and 8 It is observed thatthe void ratio of all five soils decreased with increasing

00

05

10

15

20

25

30

ρg = 12gcm335

40

0 20 40 60 80 100 120

Com

pres

sion

heig

ht (m

m)

Time (h)

MHSC

(a)

00

05

10

15

20

25

0 20 40 60 80 100 120

Com

pres

sion

heig

ht (m

m)

Time (h)

MHSC

ρg = 13gcm3

(b)

00

05

10

15

20

0 20 40 60 80 100 120

Com

pres

sion

heig

ht (m

m)

Time (h)

MHSC

ρg = 14gcm3

(c)

Figure 3 Compression curves of MH and SC considering different LBW densities (a) ρg 12gcm3 (b) ρg 13gcm3(c) ρg 14gcm3


consolidation pressure which can be explained by Terzaghirsquosconsolidation theory As the consolidation pressure variedfrom 50 kPa to 400 kPa the SC soil had the largest change inthe void ratio and the CH soil showed the lowest change

although they were prepared at the same initial conventionalvoid ratio Table 3 shows that the LBW content was thehighest for the CH soil whereas it was the lowest for the SCsoil (erefore the change in the void ratio can be explained

10 20 30 402θ (degrees)

50 60 8070

Inte

nsity

(au

)

Quartz (395)Montmorillonite(04)

Illite (331)Kaolinite (270)

(a)

10 20 30 402θ (degrees)

50 60 8070

Inte

nsity

(au

)



(b)

Inte

nsity

(au

)

10 20 30 402θ (degrees)

50 60 8070



(c)

Inte

nsity

(au

)

10 20 30 402θ (degrees)

50 60 8070



(d)

Inte

nsity

(au

)

10 20 30 402θ (degrees)

50 60 8070



(e)

Figure 4 X-ray diffraction patterns for different soil specimens (a) CH soil (b) MH soil (c) CL soil (d) ML soil (e) SC soil


in terms of LBW contents In the present range of con-solidation pressure free water was removed easily but LBWcould not be removed due to the bonding force between thewater and soil particles which is consistent with the findingsreported by Shang et al [25] and Li et al [39] At a givenwater content the higher the LBW content the lower thefree water content and the smaller the change of the voidratio during consolidation Hence it can be concluded that areduction in the void ratio is related to the LBW contentMoreover the LBW content increased while the change inthe void ratio decreased with the increase in the clay content(e initial water content was higher than the correspondingLBW content for all of the soil specimens At a given water

content when the LBW content is higher the content of freewater is smaller so there is less expulsion of water inconsolidation (erefore the change in the void ratio is lessfor soils (eg CH) with a high LBW content(e Cc values ofthe soil specimens are shown in Table 4 It is noted that forsoils with a greater LBW content the Cc value is smallerrevealing that the compressibility of soil is affected by theLBW content When LBW was considered a part of the solidphase the trend for all of the soil specimens was almost thesame as can be seen in Figure 8(e change in the void ratiowith consolidation pressure was nearly the same regardlessof soil types Hence it is reasonable to assume LBW to be apart of the solid phase

0

20

40

60

80

100

CH MH CL ML SCPe

rcen

tage

cont

ent

Soil sample

Clay mineralsQuartz

Figure 5 Contents of quartz and clay minerals in different soils

Table 2 Mineral compositions of different soil samples

SampleMineral composition ()

Quartz Montmorillonite Illite KaoliniteCH 395 04 331 270MH 691 12 115 182CL 743 10 151 96ML 858 06 65 71SC 906 03 51 40

Table 3 Parallel LBW content tests on different soil samples

Sample

Drysoilmass(g)

Specificgravity

Dry soilvolume(cm3)

Distilledwatervolume(mL)

Finalreading(mL)

Solutionvolume

increment(mL)

Evaporation(mL)

Solutionshrinking

volume (mL)

LBWcontent()

Averagevalue ()

CH-1 2710 271 1000 24300 25092 792 020 209 3006 3014CH-2 2710 1000 24300 25091 791 020 209 3022MH-1 2730 273 1000 24300 25095 795 020 205 2936 2944MH-2 2730 1000 24300 25094 794 020 204 2952CL-1 2660 266 1000 24300 25156 856 020 144 2004 2012CL-2 2660 1000 24300 25157 857 020 143 2020ML-1 2750 275 1000 24300 25177 877 020 123 1623 1631ML-2 2750 1000 24300 25176 876 020 124 1639SC-1 2690 269 1000 24300 25197 897 020 103 1337 1321SC-2 2690 1000 24300 25199 899 020 101 1305


45 Permeability Coefficients of Saturated Soils (e per-meability coefficients (k) of saturated soil specimens arepresented in Table 5 It is noted that the k values of these soilspecimens were different At the same initial conventionalvoid ratio the soil (ie CH) with the largest LBW contenthad the least k value in comparison with other soils Becausefree water cannot pass through LBW the effective void forflowing water is reduced as the LBW content increasesActually the space occupied by LBW can be regarded as anineffective void as explained by Zhang et al [40] As a resultthe presence of LBW in soil reduces its k value However thek values of soil specimens prepared at the identical initialmodified void ratio were approximately the same In otherwords the k values were almost equal for all soil specimenswhen LBW was considered a part of the solid phase

46 Compressibility of Unsaturated Soils Table 6 presents thedegrees of saturation of the unsaturated MH soil before andafter consolidation tests It shows that the degree of saturationcalculated from the conventional void ratio reached above100(is was inconsistent with the actual situation caused bythe density problem of the water in soil as mentioned by Villar[41](erefore the degree of saturation was recalculated basedon the modified void ratio taking the density of LBW intoaccount (e results indicate that the recalculated degree ofsaturation was in accordance with common sense (Table 6)Figure 9 illustrates the compressive behavior of the MH soilwith different initial dry densities and initial water contents Itshows that the void ratio of soil specimens with the same drydensity varied with the change in the water content At thesame water content the larger the dry density of soil thesmaller the change of the void ratio (is is because a higherdry density leads to a higher content of soil particles pervolume and consequently the soil has a stronger adsorptioncapacity to bound water (e discharge of pore gas constitutesthe main part of the compression process

(e change in the conventional compression index of theunsaturated MH soil is shown in Figure 10 Since the initialwater content of the soil specimens was smaller than the liquidlimit the conventional compression index decreased with theincrease in the initial water content When the water contentwas lower than the LBW content the water-adsorption film ofthe soil particles thickened as the water content increased(erefore the solid volume of the soil increased and thevolume ratio of air became smaller Because of the relativelystrong viscosity of LBW it was difficult to discharge LBW at aconsolidation pressure of 16MPa [39] this led to a decrease inthe compression index (e water content was less than theliquid limit although it had a value higher than the LBWcontent With the increase of the water content the effect ofthe DDL made LBW bind to the surfaces of soil particles atcertain viscosity and fluidity Hence the volume ratio of airbecame smaller At a consolidation pressure of 200 kPa LBW

y = 08493xR2 = 09897

0

10

20

30

40

50

60

0 20 40 60 80

LBW

cont

ent (

)

Plastic limit ()

Experimental dataExperimental data from J B Yuan (2012)

Figure 6 Fitting curve of the relationship between the LBWcontent and the plastic limit

100010010101

09

08

07

06

05

Con

vent

iona

l voi

d ra

tio e

Consolidation pressure logp (kPa)

CHMHCL

MLSC

Figure 7 Compressive behavior of saturated soils with the sameinitial conventional void ratio

Mod

ified

voi

d ra

tio eprime

035033031029027025023021019017015

100010010101Consolidation pressure logp (kPa)

CHMHCL

MLSC

Figure 8 Compressive behavior of saturated soils with the sameinitial modified void ratio

Table 4 Compression indexes of different soil samples

Sample CH MH CL ML SCCc 0067 0083 0118 0142 0161


can migrate to adjacent soil particles however it remainsdifficult to discharge (e water contents of soil specimensexhibited different decreases compared to the initial values Atan initial dry density of 146 gcm3 and an initial water contentof 340 the water content of theMH soil decreased the mostto reach a value of 3274 (is was larger than the LBWcontent of the MH soil (erefore for unsaturated soilspecimens when the initial water content was lower than theLBW content the soil compression was mainly due to thedischarge of pore air and the water content was almost un-changed after the experiment When the initial water contentis higher than the LBW content the soil compression processinvolved the discharge of pore air free water and the out-ermost water film on particle surfaces After the test the watercontent was not lower than the LBW content and LBW couldbe considered a part of the solid phase

(rough the consolidation and permeability tests of fivesoil samples the LBW content was found to have a sig-nificant influence on the consolidation and compression ofthe soil In previous specifications when calculating thecompression index of soil all water in the soil was regardedas free water However according to the results of LBWcontent tests and consolidation tests normative calculationsdo not precisely match the engineering reality In engi-neering practice the temperature of embankment fillers israrely higher than 25degC even in hot and humid areas thetemperature does not exceed 30degC (us the change in LBWcontent is not more than 1 [42] In addition an on-site

investigation showed that the water content of a fine-grainedsoil embankment increased yearly from an initial value to anequilibrium one approaching the plastic limit in southernChina [43] When the water content of soil reaches theplastic limit a full layer of LBW is formed [34] In theoperation period the LBW content of the fine-grained soil isrelatively stable in the service life of the embankment afterthe water content reaches its equilibrium LBW can thus beregarded as a part of the solid phase of fine-grained soil

5 Modified Compression Index andIts Application

(e existence of LBW affects the pore characteristics andconsolidation behavior of fine-grained soils as deducedfrom the above-described consolidation and permeabilitytests To accurately predict the consolidation settlement ofsoil consolidation characteristics need to be predictedcorrectly In the present study the compression index wasmodified on the basis of the modified void ratio and it wasused to predict the settlement of a road embankment

51 Compression Index considering LBW (e modified voidratio can be obtained by substituting equation (9) into (6)

eprime e + 1

1 + ρs13( 1113857 times 08493wp

minus 1 (10)

Table 5 Permeability coefficients of soil samples with the same e0 or e0prime

Sample e0 k (cms) e0prime k (cms)

CH

081

153times10minus 6

033

757times10minus 5

MH 447times10minus 6 650times10minus 5

CL 661times 10minus 5 801times 10minus 5

ML 695times10minus 5 471times 10minus 5

SC 115times10minus 4 821times 10minus 5

Note e0 is the initial conventional void ratio e0prime is the initial modified void ratio k is the permeability coefficient

Table 6 Degree of saturation of the MH soil before and after the consolidation test

Water content () Dry density (gmiddotcmminus 3)Degree of saturation calculated by the

conventional void ratio (e)Degree of saturation calculated by the

modified void ratio (eprime)Initial value () Final value () Initial value () Final value ()

340

146 10708 11572 8575 9364141 9953 11248 7967 9004138 9526 10904 7625 8728133 8872 10205 7170 8297

320

146 10090 11113 7951 8757141 9368 10484 7381 8262138 8965 9958 6612 7398133 8391 9388 1718 1180

294

146 9259 10331 7123 7881141 8606 9633 6620 7410138 8237 9328 6336 7176133 7746 8916 5958 6890

270

146 8513 9642 6549 7417141 7904 8920 6080 6861138 7546 8660 5819 6662133 7080 8156 5446 6274


(e compression index is an important characteristic ofsoil compression and it can be calculated by the followingequation according to Terzaghirsquos consolidation theory

Cc ΔeΔ lgp

(11)

where p is the consolidation pressureBased on the modified void ratio a modified com-

pression index is obtained

Ccprime ΔeprimeΔ lgp

(12)

Con

vent

iona

l voi

d ra

tio e

11

10

09

08

07

0601 1 10 100 1000

Consolidation pressure p (kPa)

146gcm3

141gcm3138gcm3

133gcm3

(a)

Con

vent

iona

l voi

d ra

tio e

11

10

09

08

07

0601 1 10 100 1000


146gcm3

141gcm3138gcm3

133gcm3

(b)

Con

vent

iona

l voi

d ra

tio e

11

10

09

08

07

0601 1 10 100 1000


146gcm3

141gcm3138gcm3

133gcm3

(c)

Con

vent

iona

l voi

d ra

tio e

11

10

09

08

07

0601 1 10 100 1000


146gcm3

141gcm3138gcm3

133gcm3

(d)

Figure 9 Compressive behavior of the unsaturated MH soil with different water contents and dry densities (a) Water content 340(b) Water content 320 (c) Water content 294 (d) Water content 270


where Ccprime is the modified compression index

Combining equations (10)ndash(12) one can deduce thefollowing equation


Cc

1 + Gs( 13) times 08493wp

(13)

Sridharan and Jayadeva [10] proposed a theoreticalequation for the compression index from the microscopicpoint of view and the equation is expressed as

Cct GscwS times 10minus 6

04367(nεT)]

1113968 (14)

where Cct is the theoretical compression index cw is the unitweight of water S is the specific surface area of soil particlesn is the concentration of the pore liquid ions ε is the di-electric constant (7854 Fm) v is the valency of the cationand T is Kelvinrsquos constant (298K)

Since equation (14) has a theoretical basis and con-siders various factors that affect the compression index theresults can be regarded as a benchmark for the com-pression index (e conventional compression indexesmodified compression indexes and theoretical compres-sion indexes of the five saturated soils with an initial voidratio of 081 were calculated and the results are shown inFigure 11 It is observed that conventional compressionindexes were obviously higher than theoretical values Bycontrast modified compression indexes were quite close totheoretical compression indexes calculated by the equationproposed by Sridharan and Jayadeva [10] (is indicatesthat the modified compression index is better than theconventional compression index in characterizing thecompressive behavior of fine-grained soils Compared withthe theoretical compression index the determination ofthe modified compression index needs only macroscopicparameters and thus does not need to conduct a series ofmicroscopic tests In other words the modified com-pression index is more convenient for practical applica-tions than the theoretical one and also more precise thanthe conventional one

52 Application of the Modified Compression Index (emodified compression index was used to predict the set-tlement of an embankment section of the WanningndashYangpuhighway in Hainan Province China (e humid climate inHainan Province makes it vital to pay special attention to theembankment settlement after constructions (e embank-ment was 80m high and 1225m wide It was filled with alocally available fine-grained soil (ie MH clay) whosephysical properties are shown in Table 1 To observe thesettlement after construction two monitoring tubes were setup with one (S1) located on the bottom of the embankmentand the other (S2) located on the top of the embankment(e installation of the upper settlement tube is shown inFigure 12(a) (us the difference between the readings of S2and S1 could be regarded as the settlement of the em-bankment Also the embankment settlement was calculatedfrom the conventional compression index and modifiedcompression index based on the layerwise summationmethod as recommended by the Chinese standard (JTGD30-2015)

St 1113944n

i1

Hi

1 + e0i

Ccilgp0i + Δpi

p0i

1113890 1113891 (15)

where St is the total settlement Hi is the thickness of thelayer i e0i is the initial void ratio of the layer i Cci is thecompression index of the layer i p0i is the self-weight stressof the layer i and Δpi is the additional stress of the layer i

(e settlement of the embankment was monitored for360 days and the results are shown in Figure 12(b) It isobserved that the readings of the monitoring tubes (ie S1and S2) stabilized gradually and the final settlement of theembankment was approximately 733mm (e total settle-ments of the embankment calculated using Cc and Cc

prime were1135mm and 707mm respectively Obviously the set-tlement calculated by Cc

prime was closer to the measured onewhile Cc overestimated the settlement(is indicates that themodified compression index can effectively predict the

006

011

016

250 270 290 310 330 350

Con

vent

iona

l com

pres

sion

inde

x C

c

Water content ()

wg = 294

146gcm3

141gcm3138gcm3

133gcm3

Figure 10 Conventional compression indexes of the unsaturatedMH soil with different dry densities

0

01

02

CH MH CL ML SC

Com

pres

sion

inde

x

Soil sample

CcCctCprimec

Figure 11 Comparison of conventional theoretical and modifiedcompression indexes of different soils Note Cc is the conventionalcompression index Cct is the theoretical compression index Cc

prime isthe modified compression index


settlement of fine-grained soil embankments (erefore it isreasonable to consider the effect of LBW in evaluating thecompressibility of fine-grained soils It should be mentionedthat the prediction of embankment settlements can begreatly improved using themodified compression index andthe prediction results still deviate a lot from the measureddata due to the variability of soil properties in the field[44ndash46] (us the future work could be done by taking thevariability and uncertainty of soil parameters intoconsideration

6 Conclusions

(is study investigated the effects of LBW on the com-pressibility of compacted fine-grained soils (e LBWdensity of 13 gcm3 was assumed for the measurement (emodified void ratio was introduced and LBW was con-sidered a part of the solid phase of soil (e settlement of anembankment was calculated based on the modified com-pression index and compared with the field data From thepresent experimental studies the following conclusions canbe drawn

(1) It is confirmed that montmorillonite and illite greatlyaffect the LBW content and the LBW content varieslinearly with the plastic limit Hence for engineeringconvenience LBW can be estimated from the plasticlimit

(2) For saturated fine-grained soil samples with the sameinitial void ratio the compression indexes andpermeability coefficients decrease with the increasein the LBW content When LBW is regarded as a partof the solid phase in soil at the same modified voidratio the compression indexes and the permeabilitycoefficients of different soils tend to be the same

(3) For unsaturated soils the compression of soil duringconsolidation is due to air discharge when the watercontent is less than the LBW content whereas thecompression of soil is due to the discharge of both air

and water when the water content is higher than theLBW content (is confirms the assumption thatLBW is a part of the solid phase

(4) (e modified compression index determined basedon the modified void ratio is recommended forcalculating the compression of fine-grained soilswhen the water content is higher than the LBWcontent

Data Availability

(e data used to support the findings of this study are in-cluded within this article

Conflicts of Interest

(e authors declare that there are no conflicts of interestregarding the publication of this paper

Acknowledgments

(is work was supported by the National Natural ScienceFoundation of China (51978085 and 51108049) and theHighway Industry Standard Compilation Project of Ministryof Transportation (JTG-201507)

References

[1] U Dagdeviren A S Demir and T F Kurnaz ldquoEvaluation ofthe compressibility parameters of soils using soft computingmethodsrdquo Soil Mechanics and Foundation Engineeringvol 55 no 3 pp 173ndash180 2018

[2] S Shimobe and G Spagnoli ldquoSome generic trends on the basicengineering properties of fine-grained soilsrdquo EnvironmentalEarth Sciences vol 78 no 9 2019

[3] R T Martin ldquoAdsorbed water on clay a reviewrdquo Clays andClay Minerals vol 9 no 1 pp 28ndash70 1962

[4] J Mitchell and K Soga Fundamentals of Soil Behavior JohnWiley amp Sons Inc Press Hoboken NJ USA 2005

[5] B P Radhika A Krishnamoorthy and A U Rao ldquoA reviewon consolidation theories and its applicationrdquo International

(a)

0

20

40

60

80

100

0 100 200 300 400

Settl

emen

t (m

m)

Time (d)

S1S2

733Subgrade

8m 115

26m

Embankment

Upper settlement tube

Lower settlement tubeS1

S2

(b)

Figure 12 Field monitoring on the settlement of theWanningndashYangpu highway embankment (a) Installation of the upper settlement tube(b) Monitored settlement


Journal of Geotechnical Engineering vol 14 no 1 pp 9ndash152020

[6] L Q Sun J X Lu W Guo et al ldquoModels to predict com-pressibility and permeability of reconstituted claysrdquo Geo-technical Testing Journal vol 39 no 2 pp 324ndash330 2016

[7] L L Zeng Y Q Cai Y J Cui et al ldquoHydraulic conductivity ofreconstituted clays based on intrinsic compressionrdquo Geo-technique vol 70 no 3 pp 268ndash275 2019

[8] D R Petersen R E Link R G Robinson and M M AllamldquoCompression index of clays and siltsrdquo Journal of Testing andEvaluation vol 31 no 1 pp 22ndash27 2003

[9] C Chu Z Wu Y Deng Y Chen and Q Wang ldquoIntrinsiccompression behavior of remolded sand-clay mixturerdquo Ca-nadian Geotechnical Journal vol 54 no 7 pp 926ndash932 2017

[10] A Sridharan and M S Jayadeva ldquoDouble layer theory andcompressibility of claysrdquo Geotechnique vol 32 no 2pp 133ndash144 1982

[11] J Chen A Anandarajah and H Inyang ldquoPore fluid prop-erties and compressibility of kaoliniterdquo Journal of Geotech-nical and Geoenvironmental Engineering vol 126 no 9pp 798ndash807 2000

[12] XW Zhang C MWang and J X Li ldquoExperimental study ofcoupling behaviors of consolidation-creep of soft clay and itsmechanismrdquo Rock and Soil Mechanics vol 32 no 12pp 3584ndash3590 2011 in Chinese

[13] F C Wu ldquoCharacteristics of adsorption and binding water ofcohesive soil and some characteristics of seepagerdquo ChineseJournal of Geotechnical Engineering vol 6 no 6 pp 86ndash951984 in Chinese

[14] YWang S Lu T Ren and B Li ldquoBound water content of air-dry soils measured by thermal analysisrdquo Soil Science Society ofAmerica Journal vol 75 no 2 pp 481ndash487 2011

[15] L Cheng P Fenter K L Nagy et al ldquoMolecular-scale densityoscillations in water adjacent to a mica surfacerdquo PhysicalReview Letters vol 87 no 15 p 156103 2001

[16] P L Arens ldquoMoisture content and density of some clayminerals and some remarks on the hydration pattern of clayrdquoTransactions of the International Congress of Soil Science inTransactions of the International Congress of Soil Sciencevol 2 pp 59ndash62 1950

[17] D M Zymnis A J Whittle and J T Germaine ldquoMea-surement of temperature-dependent bound water in claysrdquoGeotechnical Testing Journal vol 42 no 1 pp 232ndash244 2018

[18] F Min C Peng and S Song ldquoHydration layers on claymineral surfaces in aqueous solutions a Reviewrdquo Archives ofMining Sciences vol 59 no 2 pp 489ndash500 2014

[19] C Zhang and N Lu ldquoWhat is the range of soil water densityCritical reviews with a unified modelrdquo Reviews of Geophysicsvol 56 no 3 pp 532ndash562 2018

[20] P A Mante C C Chen Y C Wen et al ldquoProbing hy-drophilic interface of solidliquid-water by nanoultrasonicsrdquoScientific Reports vol 4 no 1 pp 1ndash6 2014

[21] A C Jacinto M V Villar and A Ledesma ldquoInfluence ofwater density on the water-retention curve of expansiveclaysrdquo Geotechnique vol 62 no 8 pp 657ndash667 2012

[22] Y Bahramian A Bahramian and A Javadi ldquoConfined fluidsin clay interlayers a simple method for density and abnormalpore pressure interpretationrdquo Colloids and Surfaces APhysicochemical and Engineering Aspects vol 521 pp 260ndash271 2017

[23] R C Mackenzie ldquoDensity of water sorbed on montmoril-loniterdquo Nature vol 181 no 4605 p 334 1958

[24] A M Fernandez and P Rivas ldquoAnalysis and distribution ofwaters in the compacted FEBEX bentonite pore water

chemistry and adsorbed water propertiesrdquo Advances in Un-derstanding Engineered Clay Barriers pp 257ndash275 2005

[25] X-Y Shang G-Q Zhou L-F Kuang and W Cai ldquoCom-pressibility of deep clay in East China subjected to a widerange of consolidation stressesrdquo Canadian GeotechnicalJournal vol 52 no 2 pp 244ndash250 2015

[26] T V Bharat and A Sridharan ldquoPrediction of compressibilitydata for highly plastic clays using diffuse double-layer theoryrdquoClays and Clay Minerals vol 63 no 1 pp 30ndash42 2015

[27] A Sridharan ldquoSoil clay mineralogy and physico-chemicalmechanisms governing the fine-grained soil behaviourrdquo In-dian Geotechnical Journal vol 44 pp 371ndash399 2014

[28] T V Bharat P V Sivapullaiah and M M Allam ldquoNovelprocedure for the estimation of swelling pressures of com-pacted bentonites based on diffuse double layer theoryrdquoEnvironmental Earth Sciences vol 70 no 1 pp 303ndash3142013

[29] S Tripathy A Sridharan and T Schanz ldquoSwelling pressuresof compacted bentonites from diffuse double layer theoryrdquoCanadian Geotechnical Journal vol 41 no 3 pp 437ndash4502004

[30] M P Segall D E Buckley and C F M Lewis ldquoClay mineralindicators of geological and geochemical subaerial modifi-cation of near-surface Tertiary sediments on the northeasternGrand Banks of Newfoundlandrdquo Canadian Journal of EarthSciences vol 24 no 11 pp 2172ndash2187 1987

[31] Y Yukselen and A Kaya ldquoComparison of methods for de-termining specific surface area of soilsrdquo Journal of Geotech-nical and Geoenvironmental Engineering vol 132 no 7pp 931ndash936 2006

[32] B Chittoori and A J Puppala ldquoQuantitative estimation ofclay mineralogy in fine-grained soilsrdquo Journal of Geotechnicaland Geoenvironmental Engineering vol 137 no 11pp 997ndash1008 2011

[33] S He X Yu A Banerjee and A J Puppala ldquoExpansive soiltreatment with liquid ionic soil stabilizerrdquo TransportationResearch Record Journal of the Transportation ResearchBoard vol 2672 no 52 pp 185ndash194 2018

[34] A H Kurichetsky and S L LiDe Combination of Soil WaterTranslation Geological Publishing House Press BeijingChina 1982 in Chinese

[35] N Ural Current Topics in the Utilization of Clay in Industrialand Medical Applications IntechOpen London UK 2018

[36] R D Holtz and W D Kovacs An Introduction to Geotech-nical Engineering Prentice-Hall Englewood Cliffs NJ USA1981

[37] F H Chen Foundations on Expansive Soils ElsevierAmsterdam Netherlands 2012

[38] J B Yuan ldquo(e study for properties of bound water on clayeysoils and their quantitative methodsrdquo M S thesis SouthChina University of Technology Guangzhou China 2012 inChinese

[39] S Li C MWang and QWu ldquoVariations of bound water andmicrostructure in consolidation-creep process of Shanghaimucky clayrdquo Rock and Soil Mechanics vol 38 no 10pp 2809ndash2816 2017 in Chinese

[40] Y Zhang T L Chen Y J Zhang et al ldquoCalculation methodsof seepage coefficient for clay based on the permeationmechanismrdquo Advances in Civil Engineering vol 2019 ArticleID 6034526 9 pages 2019

[41] M V Villar ldquo(ermo-hydro-mechanical characterisation of abentonite from Cabo de Gata a study applied to the use ofbentonite as sealing material in high level radioactive waste


repositoriesrdquo Publicacion tecnica (Empresa Nacional deResiduos Radiactivos) vol 4 pp 15ndash258 2002

[42] Y X Shao B Shi C Liu et al ldquoTemperature effect on hydro-physical properties of clayey soilsrdquo Chinese Journal of Geo-technical Engineering vol 33 no 10 pp 1576ndash1582 2011 inChinese

[43] J L Zheng and R Zhang ldquoPrediction and control method fordeformation of highway expansive soil subgraderdquo ChinaJournal of Highway and Transport vol 28 no 3 pp 1ndash102015 in Chinese

[44] J Ji W J Zhang F Zhang et al ldquoReliability analysis onpermanent displacement of earth slopes using the simplifiedbishop methodrdquo Computers and Geotechnics vol 117 2020

[45] J Ji C Zhang Y Gao and J Kodikara ldquoReliability-baseddesign for geotechnical engineering an inverse FORM ap-proach for practicerdquo Computers and Geotechnics vol 111pp 22ndash29 2019

[46] Y X Wu Y F Gao L M Zhang and J Yang ldquoHow thedistribution characteristics of soil property affect probabilisticfoundation settlement from the view of the first four sta-tistical momentsrdquo Canadian Geotechnical Journal 2019


that Cc was related to the specific surface area of soil par-ticles In the literature many experimental and micro-structural observations revealed that the consolidation andcompression processes of soil were also affected by LBW[11 12] According to the diffuse-electric double layer(DDL) theory [13] the water in soil can be classified intothree types ie tightly bound water (TBW) LBW and freewater TBW is tightly adsorbed on the surfaces of soilparticles and it gradually turns into LBW with weakeningaction of the electric double layer TBW has a strong vis-cosity and cannot be removed entirely from the surfaces ofsoil particles until the soil temperature is raised up to 200degCBecause of its unique properties TBW is generally incor-porated as a part of soil particles in calculations [14]

Many studies including nanoscale observations haverevealed that the density of LBWwas higher than that of freewater [15ndash17] It was found that the LBW content of fine-grained soils was generally between 03 and 50 and theLBW density ranged from 115 gcm3 to 1872 gcm3

[14 18 19] and gradually became lower as the distance fromthe particle surface increased [20] (e montmorillonitecontent of soil also greatly affected the content and density ofLBW [21ndash24] Various studies reported different values forthe LBW density but failed to suggest a fixed value LBWcould be converted into free water at temperatures above50degC [17] By oedometer tests Shang et al [25] observed thatthe soil water content approximated the LBW content at aconsolidation pressure of 2MPa Furthermore many re-searchers found that the DDL efficiently explained theconsolidation behavior of soil [26ndash29] (e isomorphoussubstitution of clay minerals occurs easily in fine-grainedsoils and low valence ions replace high valence ionsresulting in a loss of positive and negative charges on thesurfaces of clay minerals Cations and dipole water mole-cules are adsorbed on the surfaces of soil particles due tostatic electricity which cannot easily discharge under ex-ternal forces [18] In the process of consolidation the ex-istence of the LBW film greatly reduces the soil permeability

To the best of our knowledge few studies have addressedthe effect of LBW on the compressibility of soil (ereforeone objective of this study was to determine the LBWcontents of different fine-grained soils using the volumetricflask method and then to analyze the effects of LBW on theconsolidation characteristics of soil specimens (e secondobjective was to propose a modified mathematical equationfor the void ratio considering the LBW effects Subsequentlythe modified compression index (Cc

prime) was calculated by theproposed equation and compared with the conventional Ccvalue and the theoretical value determined based on thework of Sridharan and Jayadeva [10] Finally the settlementof a road embankment was predicted using Cc

prime and verifiedwith field data

2 Modification of Void Ratio

Since LBW is usually hard to remove from soil [25 30] it canbe regarded as a part of the solid phase in soil when the watercontent is greater than the LBW content In this study theassumption is also made to deduce the modified void ratio

(us the three-phase structure of soil can be illustrated inFigure 1 (e LBW content is defined as

wg mg

ms

(1)

where wg is the LBW content mg is the LBWmass andms isthe solid mass of soil

(en the volume of LBW can be calculated by

Vg mg

ρg

ρs

ρg

Vs middot wg (2)

where Vg is the LBW volume ρg is the LBW density ρs is thedensity of the soil solid and Vs is the solid volume of the soil

(us the volume of the soil solid phase including LBW(Vsprime) can be calculated by

Vsprime Vs + Vg Vs 1 +

ρs

ρg

wg1113888 1113889 (3)

According to the definition of void ratio the modifiedvoid ratio that takes LBW into account can be calculated by

eprime V

Vsprime minus 1

Vs(e + 1)

Vsprime minus 1 (4)

where eprime is the modified void ratio and V is the total volumeof the soil

Substituting Vsprime from equation (3) into (4) yields the

expression of the modified void ratio

eprime e + 1

1 + ρsρg1113872 1113873wg

minus 1 (5)

3 Experimental Program

31 Soil Samples Four fine-grained soil samples were col-lected from different cities in China Xiangtan DanzhouZhuzhou and Enshi A coarse-grained soil sample was se-lected from Changsha for comparison purposes Particle sizeanalyses Atterberg limit tests and specific gravity tests wereperformed on all of the soil samples (e methylene blueadsorption method was employed to determine the specificsurface area of soil particles [31] (e basic physical prop-erties of the soils are shown in Table 1 (e soil samples wereclassified as per ASTM D2487 Xiangtan soil was heavy clay(CH) Danzhou soil was heavy silt (MH) Zhuzhou soil waslean clay (CL) Enshi soil was lean silt (ML) and Changshasoil was clayey sand (SC)

32 X-Ray Diffraction Tests XRD was used to identify theclay minerals in different soils [32 33] (e collected soilsamples were dried and pulverized to obtain homogeneouspowders (less than 40 μm) and the angle was set from 3deg to80deg (e test results were characterized by the X-ray dif-fraction pattern from which different minerals (eg illitekaolinite montmorillonite and quartz) were identified bymatching the peaks to the known database of minerals (ematching process and the mineral quantification were re-alized using the Match 3 XRD software







Air

Free water

VS

VL

VF

VA

mS

mL

mF

Solid phase

Air phase

Liquid phase VF

VA

mprimeS

mF

Loosely bound water

VV

V

VprimeS

VprimeV

V



Collectionsite







()

Plasticlimit wp

()












eprime e + 1

1 + ρs13( 1113857wg

minus 1 (6)



Free water



Evaporation loss

LBWSoil particle

Free water

∆V





wg ρgρwt

ρg minus ρwt

middotΔVms

(7)


ΔV ms

ρs

minus Vt (8)



wg 08493wp (9)



00

05

10

15

20

25

30

ρg = 12gcm335

40

0 20 40 60 80 100 120

Com

pres

sion

heig

ht (m

m)

Time (h)

MHSC

(a)

00

05

10

15

20

25

0 20 40 60 80 100 120

Com

pres

sion

heig

ht (m

m)

Time (h)

MHSC

ρg = 13gcm3

(b)

00

05

10

15

20

0 20 40 60 80 100 120

Com

pres

sion

heig

ht (m

m)

Time (h)

MHSC

ρg = 14gcm3

(c)





10 20 30 402θ (degrees)

50 60 8070

Inte

nsity

(au

)



(a)

10 20 30 402θ (degrees)

50 60 8070

Inte

nsity

(au

)



(b)

Inte

nsity

(au

)

10 20 30 402θ (degrees)

50 60 8070



(c)

Inte

nsity

(au

)

10 20 30 402θ (degrees)

50 60 8070



(d)

Inte

nsity

(au

)

10 20 30 402θ (degrees)

50 60 8070



(e)





0

20

40

60

80

100

CH MH CL ML SCPe

rcen

tage

cont

ent

Soil sample

Clay mineralsQuartz






Sample

Drysoilmass(g)

Specificgravity

Dry soilvolume(cm3)


Finalreading(mL)

Solutionvolume

increment(mL)

Evaporation(mL)

Solutionshrinking

volume (mL)

LBWcontent()

Averagevalue ()






y = 08493xR2 = 09897

0

10

20

30

40

50

60

0 20 40 60 80

LBW

cont

ent (

)

Plastic limit ()



100010010101

09

08

07

06

05

Con

vent

iona

l voi

d ra

tio e


CHMHCL

MLSC


Mod

ified

voi

d ra

tio eprime

035033031029027025023021019017015


CHMHCL

MLSC











eprime e + 1

1 + ρs13( 1113857 times 08493wp

minus 1 (10)



CH

081

153times10minus 6

033

757times10minus 5










340

146 10708 11572 8575 9364141 9953 11248 7967 9004138 9526 10904 7625 8728133 8872 10205 7170 8297

320

146 10090 11113 7951 8757141 9368 10484 7381 8262138 8965 9958 6612 7398133 8391 9388 1718 1180

294

146 9259 10331 7123 7881141 8606 9633 6620 7410138 8237 9328 6336 7176133 7746 8916 5958 6890

270

146 8513 9642 6549 7417141 7904 8920 6080 6861138 7546 8660 5819 6662133 7080 8156 5446 6274



Cc ΔeΔ lgp

(11)




(12)

Con

vent

iona

l voi

d ra

tio e

11

10

09

08

07

0601 1 10 100 1000


146gcm3

141gcm3138gcm3

133gcm3

(a)

Con

vent

iona

l voi

d ra

tio e

11

10

09

08

07

0601 1 10 100 1000


146gcm3

141gcm3138gcm3

133gcm3

(b)

Con

vent

iona

l voi

d ra

tio e

11

10

09

08

07

0601 1 10 100 1000


146gcm3

141gcm3138gcm3

133gcm3

(c)

Con

vent

iona

l voi

d ra

tio e

11

10

09

08

07

0601 1 10 100 1000


146gcm3

141gcm3138gcm3

133gcm3

(d)






Cc

1 + Gs( 13) times 08493wp

(13)



04367(nεT)]

1113968 (14)




St 1113944n

i1

Hi

1 + e0i

Ccilgp0i + Δpi

p0i

1113890 1113891 (15)





006

011

016

250 270 290 310 330 350

Con

vent

iona

l com

pres

sion

inde

x C

c

Water content ()

wg = 294

146gcm3

141gcm3138gcm3

133gcm3


0

01

02

CH MH CL ML SC

Com

pres

sion

inde

x

Soil sample

CcCctCprimec





6 Conclusions







Data Availability




Acknowledgments


References






(a)

0

20

40

60

80

100

0 100 200 300 400

Settl

emen

t (m

m)

Time (d)

S1S2

733Subgrade

8m 115

26m

Embankment



S2

(b)






















































Air

Free water

VS

VL

VF

VA

mS

mL

mF

Solid phase

Air phase

Liquid phase VF

VA

mprimeS

mF

Loosely bound water

VV

V

VprimeS

VprimeV

V



Collectionsite







()

Plasticlimit wp

()












eprime e + 1

1 + ρs13( 1113857wg

minus 1 (6)



Free water



Evaporation loss

LBWSoil particle

Free water

∆V





wg ρgρwt

ρg minus ρwt

middotΔVms

(7)


ΔV ms

ρs

minus Vt (8)



wg 08493wp (9)



00

05

10

15

20

25

30

ρg = 12gcm335

40

0 20 40 60 80 100 120

Com

pres

sion

heig

ht (m

m)

Time (h)

MHSC

(a)

00

05

10

15

20

25

0 20 40 60 80 100 120

Com

pres

sion

heig

ht (m

m)

Time (h)

MHSC

ρg = 13gcm3

(b)

00

05

10

15

20

0 20 40 60 80 100 120

Com

pres

sion

heig

ht (m

m)

Time (h)

MHSC

ρg = 14gcm3

(c)





10 20 30 402θ (degrees)

50 60 8070

Inte

nsity

(au

)



(a)

10 20 30 402θ (degrees)

50 60 8070

Inte

nsity

(au

)



(b)

Inte

nsity

(au

)

10 20 30 402θ (degrees)

50 60 8070



(c)

Inte

nsity

(au

)

10 20 30 402θ (degrees)

50 60 8070



(d)

Inte

nsity

(au

)

10 20 30 402θ (degrees)

50 60 8070



(e)





0

20

40

60

80

100

CH MH CL ML SCPe

rcen

tage

cont

ent

Soil sample

Clay mineralsQuartz






Sample

Drysoilmass(g)

Specificgravity

Dry soilvolume(cm3)


Finalreading(mL)

Solutionvolume

increment(mL)

Evaporation(mL)

Solutionshrinking

volume (mL)

LBWcontent()

Averagevalue ()






y = 08493xR2 = 09897

0

10

20

30

40

50

60

0 20 40 60 80

LBW

cont

ent (

)

Plastic limit ()



100010010101

09

08

07

06

05

Con

vent

iona

l voi

d ra

tio e


CHMHCL

MLSC


Mod

ified

voi

d ra

tio eprime

035033031029027025023021019017015


CHMHCL

MLSC











eprime e + 1

1 + ρs13( 1113857 times 08493wp

minus 1 (10)



CH

081

153times10minus 6

033

757times10minus 5










340

146 10708 11572 8575 9364141 9953 11248 7967 9004138 9526 10904 7625 8728133 8872 10205 7170 8297

320

146 10090 11113 7951 8757141 9368 10484 7381 8262138 8965 9958 6612 7398133 8391 9388 1718 1180

294

146 9259 10331 7123 7881141 8606 9633 6620 7410138 8237 9328 6336 7176133 7746 8916 5958 6890

270

146 8513 9642 6549 7417141 7904 8920 6080 6861138 7546 8660 5819 6662133 7080 8156 5446 6274



Cc ΔeΔ lgp

(11)




(12)

Con

vent

iona

l voi

d ra

tio e

11

10

09

08

07

0601 1 10 100 1000


146gcm3

141gcm3138gcm3

133gcm3

(a)

Con

vent

iona

l voi

d ra

tio e

11

10

09

08

07

0601 1 10 100 1000


146gcm3

141gcm3138gcm3

133gcm3

(b)

Con

vent

iona

l voi

d ra

tio e

11

10

09

08

07

0601 1 10 100 1000


146gcm3

141gcm3138gcm3

133gcm3

(c)

Con

vent

iona

l voi

d ra

tio e

11

10

09

08

07

0601 1 10 100 1000


146gcm3

141gcm3138gcm3

133gcm3

(d)






Cc

1 + Gs( 13) times 08493wp

(13)



04367(nεT)]

1113968 (14)




St 1113944n

i1

Hi

1 + e0i

Ccilgp0i + Δpi

p0i

1113890 1113891 (15)





006

011

016

250 270 290 310 330 350

Con

vent

iona

l com

pres

sion

inde

x C

c

Water content ()

wg = 294

146gcm3

141gcm3138gcm3

133gcm3


0

01

02

CH MH CL ML SC

Com

pres

sion

inde

x

Soil sample

CcCctCprimec





6 Conclusions







Data Availability




Acknowledgments


References






(a)

0

20

40

60

80

100

0 100 200 300 400

Settl

emen

t (m

m)

Time (d)

S1S2

733Subgrade

8m 115

26m

Embankment



S2

(b)

























































eprime e + 1

1 + ρs13( 1113857wg

minus 1 (6)



Free water



Evaporation loss

LBWSoil particle

Free water

∆V





wg ρgρwt

ρg minus ρwt

middotΔVms

(7)


ΔV ms

ρs

minus Vt (8)



wg 08493wp (9)



00

05

10

15

20

25

30

ρg = 12gcm335

40

0 20 40 60 80 100 120

Com

pres

sion

heig

ht (m

m)

Time (h)

MHSC

(a)

00

05

10

15

20

25

0 20 40 60 80 100 120

Com

pres

sion

heig

ht (m

m)

Time (h)

MHSC

ρg = 13gcm3

(b)

00

05

10

15

20

0 20 40 60 80 100 120

Com

pres

sion

heig

ht (m

m)

Time (h)

MHSC

ρg = 14gcm3

(c)





10 20 30 402θ (degrees)

50 60 8070

Inte

nsity

(au

)



(a)

10 20 30 402θ (degrees)

50 60 8070

Inte

nsity

(au

)



(b)

Inte

nsity

(au

)

10 20 30 402θ (degrees)

50 60 8070



(c)

Inte

nsity

(au

)

10 20 30 402θ (degrees)

50 60 8070



(d)

Inte

nsity

(au

)

10 20 30 402θ (degrees)

50 60 8070



(e)





0

20

40

60

80

100

CH MH CL ML SCPe

rcen

tage

cont

ent

Soil sample

Clay mineralsQuartz






Sample

Drysoilmass(g)

Specificgravity

Dry soilvolume(cm3)


Finalreading(mL)

Solutionvolume

increment(mL)

Evaporation(mL)

Solutionshrinking

volume (mL)

LBWcontent()

Averagevalue ()






y = 08493xR2 = 09897

0

10

20

30

40

50

60

0 20 40 60 80

LBW

cont

ent (

)

Plastic limit ()



100010010101

09

08

07

06

05

Con

vent

iona

l voi

d ra

tio e


CHMHCL

MLSC


Mod

ified

voi

d ra

tio eprime

035033031029027025023021019017015


CHMHCL

MLSC











eprime e + 1

1 + ρs13( 1113857 times 08493wp

minus 1 (10)



CH

081

153times10minus 6

033

757times10minus 5










340

146 10708 11572 8575 9364141 9953 11248 7967 9004138 9526 10904 7625 8728133 8872 10205 7170 8297

320

146 10090 11113 7951 8757141 9368 10484 7381 8262138 8965 9958 6612 7398133 8391 9388 1718 1180

294

146 9259 10331 7123 7881141 8606 9633 6620 7410138 8237 9328 6336 7176133 7746 8916 5958 6890

270

146 8513 9642 6549 7417141 7904 8920 6080 6861138 7546 8660 5819 6662133 7080 8156 5446 6274



Cc ΔeΔ lgp

(11)




(12)

Con

vent

iona

l voi

d ra

tio e

11

10

09

08

07

0601 1 10 100 1000


146gcm3

141gcm3138gcm3

133gcm3

(a)

Con

vent

iona

l voi

d ra

tio e

11

10

09

08

07

0601 1 10 100 1000


146gcm3

141gcm3138gcm3

133gcm3

(b)

Con

vent

iona

l voi

d ra

tio e

11

10

09

08

07

0601 1 10 100 1000


146gcm3

141gcm3138gcm3

133gcm3

(c)

Con

vent

iona

l voi

d ra

tio e

11

10

09

08

07

0601 1 10 100 1000


146gcm3

141gcm3138gcm3

133gcm3

(d)






Cc

1 + Gs( 13) times 08493wp

(13)



04367(nεT)]

1113968 (14)




St 1113944n

i1

Hi

1 + e0i

Ccilgp0i + Δpi

p0i

1113890 1113891 (15)





006

011

016

250 270 290 310 330 350

Con

vent

iona

l com

pres

sion

inde

x C

c

Water content ()

wg = 294

146gcm3

141gcm3138gcm3

133gcm3


0

01

02

CH MH CL ML SC

Com

pres

sion

inde

x

Soil sample

CcCctCprimec





6 Conclusions







Data Availability




Acknowledgments


References






(a)

0

20

40

60

80

100

0 100 200 300 400

Settl

emen

t (m

m)

Time (d)

S1S2

733Subgrade

8m 115

26m

Embankment



S2

(b)



















































wg ρgρwt

ρg minus ρwt

middotΔVms

(7)


ΔV ms

ρs

minus Vt (8)



wg 08493wp (9)



00

05

10

15

20

25

30

ρg = 12gcm335

40

0 20 40 60 80 100 120

Com

pres

sion

heig

ht (m

m)

Time (h)

MHSC

(a)

00

05

10

15

20

25

0 20 40 60 80 100 120

Com

pres

sion

heig

ht (m

m)

Time (h)

MHSC

ρg = 13gcm3

(b)

00

05

10

15

20

0 20 40 60 80 100 120

Com

pres

sion

heig

ht (m

m)

Time (h)

MHSC

ρg = 14gcm3

(c)





10 20 30 402θ (degrees)

50 60 8070

Inte

nsity

(au

)



(a)

10 20 30 402θ (degrees)

50 60 8070

Inte

nsity

(au

)



(b)

Inte

nsity

(au

)

10 20 30 402θ (degrees)

50 60 8070



(c)

Inte

nsity

(au

)

10 20 30 402θ (degrees)

50 60 8070



(d)

Inte

nsity

(au

)

10 20 30 402θ (degrees)

50 60 8070



(e)





0

20

40

60

80

100

CH MH CL ML SCPe

rcen

tage

cont

ent

Soil sample

Clay mineralsQuartz






Sample

Drysoilmass(g)

Specificgravity

Dry soilvolume(cm3)


Finalreading(mL)

Solutionvolume

increment(mL)

Evaporation(mL)

Solutionshrinking

volume (mL)

LBWcontent()

Averagevalue ()






y = 08493xR2 = 09897

0

10

20

30

40

50

60

0 20 40 60 80

LBW

cont

ent (

)

Plastic limit ()



100010010101

09

08

07

06

05

Con

vent

iona

l voi

d ra

tio e


CHMHCL

MLSC


Mod

ified

voi

d ra

tio eprime

035033031029027025023021019017015


CHMHCL

MLSC











eprime e + 1

1 + ρs13( 1113857 times 08493wp

minus 1 (10)



CH

081

153times10minus 6

033

757times10minus 5










340

146 10708 11572 8575 9364141 9953 11248 7967 9004138 9526 10904 7625 8728133 8872 10205 7170 8297

320

146 10090 11113 7951 8757141 9368 10484 7381 8262138 8965 9958 6612 7398133 8391 9388 1718 1180

294

146 9259 10331 7123 7881141 8606 9633 6620 7410138 8237 9328 6336 7176133 7746 8916 5958 6890

270

146 8513 9642 6549 7417141 7904 8920 6080 6861138 7546 8660 5819 6662133 7080 8156 5446 6274



Cc ΔeΔ lgp

(11)




(12)

Con

vent

iona

l voi

d ra

tio e

11

10

09

08

07

0601 1 10 100 1000


146gcm3

141gcm3138gcm3

133gcm3

(a)

Con

vent

iona

l voi

d ra

tio e

11

10

09

08

07

0601 1 10 100 1000


146gcm3

141gcm3138gcm3

133gcm3

(b)

Con

vent

iona

l voi

d ra

tio e

11

10

09

08

07

0601 1 10 100 1000


146gcm3

141gcm3138gcm3

133gcm3

(c)

Con

vent

iona

l voi

d ra

tio e

11

10

09

08

07

0601 1 10 100 1000


146gcm3

141gcm3138gcm3

133gcm3

(d)






Cc

1 + Gs( 13) times 08493wp

(13)



04367(nεT)]

1113968 (14)




St 1113944n

i1

Hi

1 + e0i

Ccilgp0i + Δpi

p0i

1113890 1113891 (15)





006

011

016

250 270 290 310 330 350

Con

vent

iona

l com

pres

sion

inde

x C

c

Water content ()

wg = 294

146gcm3

141gcm3138gcm3

133gcm3


0

01

02

CH MH CL ML SC

Com

pres

sion

inde

x

Soil sample

CcCctCprimec





6 Conclusions







Data Availability




Acknowledgments


References






(a)

0

20

40

60

80

100

0 100 200 300 400

Settl

emen

t (m

m)

Time (d)

S1S2

733Subgrade

8m 115

26m

Embankment



S2

(b)



















































10 20 30 402θ (degrees)

50 60 8070

Inte

nsity

(au

)



(a)

10 20 30 402θ (degrees)

50 60 8070

Inte

nsity

(au

)



(b)

Inte

nsity

(au

)

10 20 30 402θ (degrees)

50 60 8070



(c)

Inte

nsity

(au

)

10 20 30 402θ (degrees)

50 60 8070



(d)

Inte

nsity

(au

)

10 20 30 402θ (degrees)

50 60 8070



(e)





0

20

40

60

80

100

CH MH CL ML SCPe

rcen

tage

cont

ent

Soil sample

Clay mineralsQuartz






Sample

Drysoilmass(g)

Specificgravity

Dry soilvolume(cm3)


Finalreading(mL)

Solutionvolume

increment(mL)

Evaporation(mL)

Solutionshrinking

volume (mL)

LBWcontent()

Averagevalue ()






y = 08493xR2 = 09897

0

10

20

30

40

50

60

0 20 40 60 80

LBW

cont

ent (

)

Plastic limit ()



100010010101

09

08

07

06

05

Con

vent

iona

l voi

d ra

tio e


CHMHCL

MLSC


Mod

ified

voi

d ra

tio eprime

035033031029027025023021019017015


CHMHCL

MLSC











eprime e + 1

1 + ρs13( 1113857 times 08493wp

minus 1 (10)



CH

081

153times10minus 6

033

757times10minus 5










340

146 10708 11572 8575 9364141 9953 11248 7967 9004138 9526 10904 7625 8728133 8872 10205 7170 8297

320

146 10090 11113 7951 8757141 9368 10484 7381 8262138 8965 9958 6612 7398133 8391 9388 1718 1180

294

146 9259 10331 7123 7881141 8606 9633 6620 7410138 8237 9328 6336 7176133 7746 8916 5958 6890

270

146 8513 9642 6549 7417141 7904 8920 6080 6861138 7546 8660 5819 6662133 7080 8156 5446 6274



Cc ΔeΔ lgp

(11)




(12)

Con

vent

iona

l voi

d ra

tio e

11

10

09

08

07

0601 1 10 100 1000


146gcm3

141gcm3138gcm3

133gcm3

(a)

Con

vent

iona

l voi

d ra

tio e

11

10

09

08

07

0601 1 10 100 1000


146gcm3

141gcm3138gcm3

133gcm3

(b)

Con

vent

iona

l voi

d ra

tio e

11

10

09

08

07

0601 1 10 100 1000


146gcm3

141gcm3138gcm3

133gcm3

(c)

Con

vent

iona

l voi

d ra

tio e

11

10

09

08

07

0601 1 10 100 1000


146gcm3

141gcm3138gcm3

133gcm3

(d)






Cc

1 + Gs( 13) times 08493wp

(13)



04367(nεT)]

1113968 (14)




St 1113944n

i1

Hi

1 + e0i

Ccilgp0i + Δpi

p0i

1113890 1113891 (15)





006

011

016

250 270 290 310 330 350

Con

vent

iona

l com

pres

sion

inde

x C

c

Water content ()

wg = 294

146gcm3

141gcm3138gcm3

133gcm3


0

01

02

CH MH CL ML SC

Com

pres

sion

inde

x

Soil sample

CcCctCprimec





6 Conclusions







Data Availability




Acknowledgments


References






(a)

0

20

40

60

80

100

0 100 200 300 400

Settl

emen

t (m

m)

Time (d)

S1S2

733Subgrade

8m 115

26m

Embankment



S2

(b)



















































0

20

40

60

80

100

CH MH CL ML SCPe

rcen

tage

cont

ent

Soil sample

Clay mineralsQuartz






Sample

Drysoilmass(g)

Specificgravity

Dry soilvolume(cm3)


Finalreading(mL)

Solutionvolume

increment(mL)

Evaporation(mL)

Solutionshrinking

volume (mL)

LBWcontent()

Averagevalue ()






y = 08493xR2 = 09897

0

10

20

30

40

50

60

0 20 40 60 80

LBW

cont

ent (

)

Plastic limit ()



100010010101

09

08

07

06

05

Con

vent

iona

l voi

d ra

tio e


CHMHCL

MLSC


Mod

ified

voi

d ra

tio eprime

035033031029027025023021019017015


CHMHCL

MLSC











eprime e + 1

1 + ρs13( 1113857 times 08493wp

minus 1 (10)



CH

081

153times10minus 6

033

757times10minus 5










340

146 10708 11572 8575 9364141 9953 11248 7967 9004138 9526 10904 7625 8728133 8872 10205 7170 8297

320

146 10090 11113 7951 8757141 9368 10484 7381 8262138 8965 9958 6612 7398133 8391 9388 1718 1180

294

146 9259 10331 7123 7881141 8606 9633 6620 7410138 8237 9328 6336 7176133 7746 8916 5958 6890

270

146 8513 9642 6549 7417141 7904 8920 6080 6861138 7546 8660 5819 6662133 7080 8156 5446 6274



Cc ΔeΔ lgp

(11)




(12)

Con

vent

iona

l voi

d ra

tio e

11

10

09

08

07

0601 1 10 100 1000


146gcm3

141gcm3138gcm3

133gcm3

(a)

Con

vent

iona

l voi

d ra

tio e

11

10

09

08

07

0601 1 10 100 1000


146gcm3

141gcm3138gcm3

133gcm3

(b)

Con

vent

iona

l voi

d ra

tio e

11

10

09

08

07

0601 1 10 100 1000


146gcm3

141gcm3138gcm3

133gcm3

(c)

Con

vent

iona

l voi

d ra

tio e

11

10

09

08

07

0601 1 10 100 1000


146gcm3

141gcm3138gcm3

133gcm3

(d)






Cc

1 + Gs( 13) times 08493wp

(13)



04367(nεT)]

1113968 (14)




St 1113944n

i1

Hi

1 + e0i

Ccilgp0i + Δpi

p0i

1113890 1113891 (15)





006

011

016

250 270 290 310 330 350

Con

vent

iona

l com

pres

sion

inde

x C

c

Water content ()

wg = 294

146gcm3

141gcm3138gcm3

133gcm3


0

01

02

CH MH CL ML SC

Com

pres

sion

inde

x

Soil sample

CcCctCprimec





6 Conclusions







Data Availability




Acknowledgments


References






(a)

0

20

40

60

80

100

0 100 200 300 400

Settl

emen

t (m

m)

Time (d)

S1S2

733Subgrade

8m 115

26m

Embankment



S2

(b)




















































y = 08493xR2 = 09897

0

10

20

30

40

50

60

0 20 40 60 80

LBW

cont

ent (

)

Plastic limit ()



100010010101

09

08

07

06

05

Con

vent

iona

l voi

d ra

tio e


CHMHCL

MLSC


Mod

ified

voi

d ra

tio eprime

035033031029027025023021019017015


CHMHCL

MLSC











eprime e + 1

1 + ρs13( 1113857 times 08493wp

minus 1 (10)



CH

081

153times10minus 6

033

757times10minus 5










340

146 10708 11572 8575 9364141 9953 11248 7967 9004138 9526 10904 7625 8728133 8872 10205 7170 8297

320

146 10090 11113 7951 8757141 9368 10484 7381 8262138 8965 9958 6612 7398133 8391 9388 1718 1180

294

146 9259 10331 7123 7881141 8606 9633 6620 7410138 8237 9328 6336 7176133 7746 8916 5958 6890

270

146 8513 9642 6549 7417141 7904 8920 6080 6861138 7546 8660 5819 6662133 7080 8156 5446 6274



Cc ΔeΔ lgp

(11)




(12)

Con

vent

iona

l voi

d ra

tio e

11

10

09

08

07

0601 1 10 100 1000


146gcm3

141gcm3138gcm3

133gcm3

(a)

Con

vent

iona

l voi

d ra

tio e

11

10

09

08

07

0601 1 10 100 1000


146gcm3

141gcm3138gcm3

133gcm3

(b)

Con

vent

iona

l voi

d ra

tio e

11

10

09

08

07

0601 1 10 100 1000


146gcm3

141gcm3138gcm3

133gcm3

(c)

Con

vent

iona

l voi

d ra

tio e

11

10

09

08

07

0601 1 10 100 1000


146gcm3

141gcm3138gcm3

133gcm3

(d)






Cc

1 + Gs( 13) times 08493wp

(13)



04367(nεT)]

1113968 (14)




St 1113944n

i1

Hi

1 + e0i

Ccilgp0i + Δpi

p0i

1113890 1113891 (15)





006

011

016

250 270 290 310 330 350

Con

vent

iona

l com

pres

sion

inde

x C

c

Water content ()

wg = 294

146gcm3

141gcm3138gcm3

133gcm3


0

01

02

CH MH CL ML SC

Com

pres

sion

inde

x

Soil sample

CcCctCprimec





6 Conclusions







Data Availability




Acknowledgments


References






(a)

0

20

40

60

80

100

0 100 200 300 400

Settl

emen

t (m

m)

Time (d)

S1S2

733Subgrade

8m 115

26m

Embankment



S2

(b)























































eprime e + 1

1 + ρs13( 1113857 times 08493wp

minus 1 (10)



CH

081

153times10minus 6

033

757times10minus 5










340

146 10708 11572 8575 9364141 9953 11248 7967 9004138 9526 10904 7625 8728133 8872 10205 7170 8297

320

146 10090 11113 7951 8757141 9368 10484 7381 8262138 8965 9958 6612 7398133 8391 9388 1718 1180

294

146 9259 10331 7123 7881141 8606 9633 6620 7410138 8237 9328 6336 7176133 7746 8916 5958 6890

270

146 8513 9642 6549 7417141 7904 8920 6080 6861138 7546 8660 5819 6662133 7080 8156 5446 6274



Cc ΔeΔ lgp

(11)




(12)

Con

vent

iona

l voi

d ra

tio e

11

10

09

08

07

0601 1 10 100 1000


146gcm3

141gcm3138gcm3

133gcm3

(a)

Con

vent

iona

l voi

d ra

tio e

11

10

09

08

07

0601 1 10 100 1000


146gcm3

141gcm3138gcm3

133gcm3

(b)

Con

vent

iona

l voi

d ra

tio e

11

10

09

08

07

0601 1 10 100 1000


146gcm3

141gcm3138gcm3

133gcm3

(c)

Con

vent

iona

l voi

d ra

tio e

11

10

09

08

07

0601 1 10 100 1000


146gcm3

141gcm3138gcm3

133gcm3

(d)






Cc

1 + Gs( 13) times 08493wp

(13)



04367(nεT)]

1113968 (14)




St 1113944n

i1

Hi

1 + e0i

Ccilgp0i + Δpi

p0i

1113890 1113891 (15)





006

011

016

250 270 290 310 330 350

Con

vent

iona

l com

pres

sion

inde

x C

c

Water content ()

wg = 294

146gcm3

141gcm3138gcm3

133gcm3


0

01

02

CH MH CL ML SC

Com

pres

sion

inde

x

Soil sample

CcCctCprimec





6 Conclusions







Data Availability




Acknowledgments


References






(a)

0

20

40

60

80

100

0 100 200 300 400

Settl

emen

t (m

m)

Time (d)

S1S2

733Subgrade

8m 115

26m

Embankment



S2

(b)


















































Cc ΔeΔ lgp

(11)




(12)

Con

vent

iona

l voi

d ra

tio e

11

10

09

08

07

0601 1 10 100 1000


146gcm3

141gcm3138gcm3

133gcm3

(a)

Con

vent

iona

l voi

d ra

tio e

11

10

09

08

07

0601 1 10 100 1000


146gcm3

141gcm3138gcm3

133gcm3

(b)

Con

vent

iona

l voi

d ra

tio e

11

10

09

08

07

0601 1 10 100 1000


146gcm3

141gcm3138gcm3

133gcm3

(c)

Con

vent

iona

l voi

d ra

tio e

11

10

09

08

07

0601 1 10 100 1000


146gcm3

141gcm3138gcm3

133gcm3

(d)






Cc

1 + Gs( 13) times 08493wp

(13)



04367(nεT)]

1113968 (14)




St 1113944n

i1

Hi

1 + e0i

Ccilgp0i + Δpi

p0i

1113890 1113891 (15)





006

011

016

250 270 290 310 330 350

Con

vent

iona

l com

pres

sion

inde

x C

c

Water content ()

wg = 294

146gcm3

141gcm3138gcm3

133gcm3


0

01

02

CH MH CL ML SC

Com

pres

sion

inde

x

Soil sample

CcCctCprimec





6 Conclusions







Data Availability




Acknowledgments


References






(a)

0

20

40

60

80

100

0 100 200 300 400

Settl

emen

t (m

m)

Time (d)

S1S2

733Subgrade

8m 115

26m

Embankment



S2

(b)




















































Cc

1 + Gs( 13) times 08493wp

(13)



04367(nεT)]

1113968 (14)




St 1113944n

i1

Hi

1 + e0i

Ccilgp0i + Δpi

p0i

1113890 1113891 (15)





006

011

016

250 270 290 310 330 350

Con

vent

iona

l com

pres

sion

inde

x C

c

Water content ()

wg = 294

146gcm3

141gcm3138gcm3

133gcm3


0

01

02

CH MH CL ML SC

Com

pres

sion

inde

x

Soil sample

CcCctCprimec





6 Conclusions







Data Availability




Acknowledgments


References






(a)

0

20

40

60

80

100

0 100 200 300 400

Settl

emen

t (m

m)

Time (d)

S1S2

733Subgrade

8m 115

26m

Embankment



S2

(b)


















































6 Conclusions







Data Availability




Acknowledgments


References






(a)

0

20

40

60

80

100

0 100 200 300 400

Settl

emen

t (m

m)

Time (d)

S1S2

733Subgrade

8m 115

26m

Embankment



S2

(b)






































































































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