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Digest 2004, December 2004 947-961

The Effects Of Over Consolidation Ratio And EffectiveStresses To The Earth Pressure At Rest At Clay Soils1

S. Nilay KESKN*

M. Arslan TEKNSOY**Soner UZUNDURUKAN***

ABSTRACT

The coefficient of earth pressure at rest (K0) changes depending on the relative density,stress history, over-consolidation ratio, plasticity index and similar soil properties. In thisstudy, effect of vertical effective stress and over-consolidation ratio to the coefficient earthpressure at rest were investigated. For this purpose, consolidation tests with thin-walledoedometer technique were used on four different clay samples. Variations in the horizontalstress and coefficient of earth pressure at rest were recorded during loading stage.Empirical equations which were given in the literature for estimation of K0 of normallyconsolidated and over-consolidated soils were compared with values obtained from thetests. These results showed that, over-consolidation ratio is an important factor on K0 forunloading stage. When over-consolidation ratio increased, the coefficient of earth pressureat rest is also increased. K0 is almost stable for vertical effective pressures which is higherthan pre-consolidation pressure.

1. INTRODUCTIONThe determination of lateral earth pressures is necessary at design and application stage ofthe most engineering structure. Especially, the knowledge of lateral earth pressure isrequired to design the retaining structures and deep foundations.Coefficient of earth pressure at rest (K0 ) is defined as the ratio of horizontal stresses toapplied vertical stresses at zero lateral strain [1].

vh K *0= (1)

where, h is the horizontal stress, v is the vertical stress, K0 is the coefficient of earth

pressure.

If the soil is assumed as an elastic material, following equation can be derived for K0 at thestate of zero lateral principle strain state (2=3=0) [2].*

* Sleyman Demirel University, Isparta, Turkey [email protected]** ukurova University, Adana, Turkey*** Sleyman Demirel University, Isparta, Turkey [email protected] Published in Teknik Dergi Vol. 15, No. 3 July 2004, pp: 3295-3310


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The Effects Of Over Consolidation Ratio And Effective

948

=

10K (2)

where, is the poisson ratio.K0 is determined by field or laboratory tests. In laboratory methods, tri-axial test withBishop ring and odometer test equipment that is equipped with special hardware such asstrain gauge has been used. With the tri-axial test mechanism, proving K0 condition isdifficult because the lateral deformations cant be controlled exactly. But with the odometerequipment, field K0 conditions can be presented fairly well.In this study, horizontal stresses that are occurred in clay soil samples exposed to verticalpressures, was directly measured by using thin-walled odometer technique. The coefficient

of earth pressure at rest of used soils was determined and the effects of vertical stresses andover consolidation ratio on the K0 were investigated. For this purpose, in the laboratory,thin-walled odometer test that can be simulated the field K0 conditions fairly well, werecarried out on the four undisturbed clay samples that were extracted from Afyon andorum regions.

2. LITERATURE REVIEWMany methods has been developed depend on the result of various laboratory and field teststo determine the coefficient at earth pressure at rest of different soil types. Thedetermination of earth pressure coefficient at rest by using laboratory methods has beenpreferred because the laboratory tests could be easy rather than the field tests.Bishop and Henkel stated in their study that coefficient of earth pressure at rest is

dependent on soil type, stress history and pore water pressure.Hendron [4] used an oedometer that can measure lateral pressures by strain gauge that wasmounted on a metal ring that is sensitive to the lateral stresses. Then, Brooker and Ireland[5] used to data obtained from Hendrons study and they investigated the variation of earthpressure coefficient at rest dependent on the over consolidation ratio and plasticity index.Campanella and Vaid [6] developed a tri-axial test equipment to determine K0 and theycarried out K0 tests for saturated clay samples.Saglamer investigated the effect of relative density (Dr), stress history, particle size andshape of soil to K0 in coarse-grained soils. In an odometer that was developed for this aim,loading test were carried out on four different air-dried sand. At the result of tests, it wasstated that K0 was mainly dependent on relative density of soil at loading condition. It wasalso emphasise that K0 values in loose sand were higher than in dense sands. Coefficient ofearth pressure at rest was decreased in reloading stage, especially in loose sands, but in very

dense sands K0 values was remain almost constant in loading and reloading stages. Inaddition, initial void ratio (eo) was also an important factor that controlled to Ko in normalloading condition [7].In other study concentrated on clay soils, test equipment that can be directly measure thehorizontal stresses was used. The variations of the horizontal stress and K0 values accordingto applied vertical stresses were investigated. It was concluded that the K0 values wasremain constant for the vertical stresses higher than the pre consolidation pressure, but itincreased in unloading state [8].


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In another study, the time dependent behaviour of horizontal stresses was investigated byusing K0 test tube. Pore water pressures were measured by aid of pressure transducer. Atthe results of test on the turba soils with high water contents, it was observed that therelationship between horizontal and vertical effective pressures was almost linear in loadingstage. This situation is result from the K0 values obtained in all loading stage is constant[9].K0 values are 0.60 and 0.35 in loose sands and dense sands, respectively. In normallyconsolidated soils it varies from 0.50 to 0.60 and in over consolidated soils it can be greaterthan 1 [10].Bedikan used the thin-walled oedometer and investigated the relationship between K0 andOCR for loading, unloading and reloading stages. It was observed that as the OCRincreases K0 values also increases and K0 values in the loading stage is higher than in the

unloading stage. In addition, time dependent behaviour of the horizontal stresses and K0was investigated, and it is implied that K0 values decrease under the constant vertical stress[11].Kayadelen also used the thin-walled odometer technique on different clay samples. In thatstudy, it was determined that the measured horizontal stresses in the loading stage has anlinear relationship for the vertical stresses higher than pre-consolidation pressure and theseK0 values is remain constant [12].K0 and lateral earth pressures are also determined by field tests. For this aim, total stresscell (gltzl) method, pressuremeter method and hydraulic fracturing methods has been used[13].Tavenas et al. used these three method mentioned above for measuring horizontal pressureand they investigated the validity of these methods for clays. At the results of this study,they implied that the total stress cell method is the most useful field method due to

deformations that occurs in the soil during test is small and the result of tests can be easilyinterpreted. They expressed that incorrect result can be obtained with the hydraulicfracturing method due to disturbance of the soil during test. They also expressed that thepressuremeter test results can be doubtful due to stress release during the boring of hole inwhich the test is carried out [14].In another study, K0 measurements was made by using the total stress cell and the hydraulicfracturing methods in five different site, and it is expressed in the study that more reliableresults can be obtained with the total stress method [15].Coefficient of lateral earth pressure at rest can be predicted by using one of the severalempirical equations that is in the literature. Below equation is commonly used fordetermination ofK0 in the normally consolidated soils [16].

K sin10

= (3)

where is effective internal friction angle.

Another equation used by determination ofK0 is given in Eq.4 [5].K sin95.00 = (4)

This equation can be expressed as in Eq. 5 for sloping ground surface.


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K

sin1

sin10

+

= (5)

where, is the angle of the sloping ground surface.

In clays coefficient of earth pressure at rest can be given as the following equations in termsof plasticity index

)(007.04.00 PIK += 400


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)sin94.01(*97.00K = (13)

Mayne and Kulhawy [20] investigated the K0 in the unloading stage (K0(unloading)) and theygave following relationship between over consolidation ratio and K0(unloading).

OCRKK NCunloading)(*)(0)(0 = (14)

where is slope of the relationship between log K0(unloading) and log (OCR).

)log(

)log()log()(0)(0

OCR

KKNCunloading

= (15)

is also determined by following equation [20].

)(0*852.0929.0 NC K= (16)

Mayne and Kulhawy [21] proposed following general equation that can be used for bothclays and sands.

+=

max)sin1(max

0 1

4

3)sin1(

OCR

OCR

OCR

OCRK

(17)

where, OCR is the actual over consolidation ratio, OCRmax is the maximum over

consolidation ratio and is effective angle of internal friction.

Cherubine et al. [22] was carried out an laboratory study by using special oedometerequipment on the undisturbed over consolidated clays whose natural water contents varyfrom 25 to29 and plasticity indexes vary from 30 to 40. They implied that their results arealmost same with the values obtained from Eq. 16.Tekinsoy [22, 23]developed a theoretical and iterative model for determining K0 in bothnormally and over consolidated soils. In this method, determination of horizontal stressvariation was aimed. For this aim, variations of the shear stresses and deformations in the

soil under the K0 condition were investigated. A general calculation procedure that cancalculate the horizontal earth pressure was presented. An equation for initial K0 value isgiven in Eq. 18.

21

0)2(

1

=K (18)


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where 1 is deformation of soil in the oedometer cell, is a constant dependent on loadingcondition and liquidity index (Cr). is in relation with vertical effective stress (v) and isobtained from Figure 1.

3. SOIL PROPERTIESIndex properties of soils investigated in this study are given in Table 1.

4. TESTING SYSTEMMain part of thin-walled oedometer testing system consists of a specially manufacturedoedometer ring that has a standard diameter. In this method, horizontal stresses occurred inthe soil specimen is determined from deformation values by means of strain gauges thatwas attached on the ring body.Thin-walled oedometer ring was manufactured from high alloy steel material whosethickness is 0.35 mm. It has cylindrical shape, its inner diameter is 63.5 mm and its heightis 63 mm. The top edge of ring has diameter of 140 mm and it has six holes. Three of them

3

2

1

0

-

-

-

-

-

-

100 200 300 400 500 600 700 800 900

v

12

3

a

b

1 - CH (Undisturbed O.C. Pc=400kPa Cr=16.4%)

2 - CH (Undisturbed O.C. Pc=230kPa Cr=44.7%)3 - CH (Remolded N.C. Cr=47.2%)a - Dense Sand (Dr= 0.89)b - Loose Sand (Dr= 0.33)


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has diameter of 6mm and they allow entrance of cables that strain gauges are attached. Theother three are in 7 mm diameter and they belong to screws which are located inside ofoedometer cell.

Table 1.Index properties and effective shear parameters of samples

Index Properties Sample I Sample II Sample III Sample IV

Depth (H) (m) 16.00 7.00 13.00 7..50

Natural water content (w) ( %) 30 35 21 56

Specific gravity of solid soil particles(Gs) 2.54 2.62 2.68 2.65

Liquid limit (wL) (%) 51 78 60 98

Plastic limit (wp) (%) 24 21 28 29

Plasticity index (Ip) (%) 27 57 32 69

Gravel (%) - - - -

Sand (%) 31 16 25 9

Silt + Clay (%) 69 84 75 91

Soil Class CH CH CH CH

Effective angle of internal friction ( ) 280 190 200 140

Effective cohesion ( c ) (kPa) 7 30 18 12

Four strain gauges with resistance of 120 ohm in 90 degrees angles reciprocal positions toobtain a Wheaston bridge are mounted in the outer centre surface of the ring. Two of thestrain gauges which are bonded in the centre surface of thin walled ring are positioned inparallel to horizontal plane and the other two has a right angle with these strain gauges. Thestrain gauges which are positioned in parallel to horizontal plane work actively after soilsample is loaded. The other two strain gauges balance the deformations as a result of heatchanges during the experimentation. The resistance changes in strain gauges are read fromdeformation meter. The ring is calibrated by adding water with increasing pressure into thering in three-dimensional pressure equipment before experiments start. The calibrationfactor (k) of 1.99 is obtained by measuring the amount deformations for each pressurevalues [13].In experiments, soil samples which are undisturbed and taken out from tubes are placed inload mechanism by located in thin walled oedometer ring. Samples are loaded in 50, 100,200, 400, and 800 kPa vertical strain stages and emptying stage is carried out later. It iswaited in each load stage until fixations are completed. Afterward, horizontal strain valuesare determined by using deformation meters and following load stage is carried out.

5. FINDINGSIn this study, coefficient of earth pressure at rest (K0) was determined from directlymeasured horizontal stresses (h) by means of strain gauges that were placed on thin wall of


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ring. The variation of measured horizontal stresses (h) and coefficient of earth pressure atrest (K0) according to applied vertical stress (v) was investigated for all samples. Inaddition, the relationship between coefficient of earth pressure at rest (K0) and overconsolidation ratio (OCR) was investigated for loading-unloading conditions. At the resultof tests, the variation of coefficient of earth pressure at rest (K0) with over consolidationratio was given in Table 2. The variation of measured horizontal stresses according todifferent vertical stresses was given in Figure 2, and the variation of coefficient of earthpressure at rest according to different vertical stresses was given in Figure 3 for Sample I. Itis seen from the Figure 2 and 3 that the variation is linear for vertical stresses greater thanpre-consolidation pressure.Similar relationships were obtained for the other samples, but only the results that wereobtained for Sample I were graphically presented in this article. K0 values that were

obtained from empirical equations and values obtained from laboratory tests werecompared. Results of this comparison were given in Table 4 and 5 for normallyconsolidated and over consolidated condition, respectively. Eq. 8 and Eq. 17 gave sameresults for over consolidated soils. So, only the results obtained from Eq. 8 were given inTable 4 and 5.

6. CONCLUSIONSThe effects of vertical stress and over consolidation ratio on the coefficient of earthpressure at rest were investigated experimentally in fine-grained soils. K0 values weredetermined from directly measured horizontal stresses by means of thin-walled oedometertechnique and these values were compared with K0 values that were calculated fromempirical equations. Findings were evaluated and following conclusions were derived.

1. The variation of horizontal stresses is linear for vertical stresses greater than pre-consolidation pressure in loading stage. Therefore, K0 values remain as a constantvalue for vertical stresses greater than pre-consolidation pressure.

2. It was observed that experimental K0 values is greater than K0 values calculated fromempirical equations for normally consolidated state. However, experimental K0 valuesis lower than calculated K0 values for over consolidated state. K0 values that werecalculated for low over consolidation ratio values are approximate to test results.

3. In the unloading stage, horizontal stresses decreased slower than vertical stresses, so K0values were increased. Therefore, K0 values are affected considerably from overconsolidation ratio in unloading stage. As over consolidation ratio increases,coefficient of earth pressure at rest also increases.


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Table 2. The variation of K0 values according to OCR

Sample I Sample II

Before Test After Test Before Test After Test

W (%) e H (mm) w (%) e H (mm) w (%) e H (mm) w (%) e H (mm)

30 0.74 63.00 21 0.53 55.50 35 0.99 63.00 33 0.87 59.2

OCR v (kPa) h (kPa) Ko OCR v (kPa) h (kPa) Ko

2.4 50 66 1.320 4.60 50 94.62 1.892

1.2 100 51 0.510 2.30 100 104.88 1.049

NC 200 88 0.440 1.15 200 133.48 0.667

NC 400 168 0.420 NC 400 214.23 0.536

NC 800 341 0.426 NC 800 423.23 0.529

2 400 256 0.640 2 400 308.28 0.771

4 200 196 0.980 4 200 230.85 1.154

8 100 140 1.400 8 100 160.55 1.606

16 50 101 2.020 16 50 116.38 2.328

Sample III Sample IV

Before Test After Test Before Test After Test

W (%) e H (mm) w (%) e H (mm) w (%) e H (mm) w (%) e H (mm)

21 0.62 63.00 20 0.54 60.00 56 1.33 63.00 32 0.85 49.95

OCR v (kPa) h (kPa) Ko OCR v (kPa) h (kPa) Ko

2.80 50 64.20 1.284 2.8 50 58.43 1.169

1.40 100 70.40 0.704 1.4 100 81.70 0.817

NC 200 102.40 0.512 NC 200 144.88 0.724

NC 400 201.00 0.503 NC 400 294.50 0.736

NC 800 394.00 0.493 NC 800 570.48 0.713

2 400 303.80 0.760 2 400 418.48 1.046

4 200 216.20 1.081 4 200 304.95 1.525

8100 163.40 1.634 8 100 203.30 2.033

- - - - 16 50 127.30 2.546

w Water Content (%)e Void raioH Sample Height (mm)v Applied vertical stress (kPa)h Measured horizontal stress (kPa)K0 Coefficient of earth pressure at restOCR Over consolidation ratioNC Normally consolidated


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Figure 4. The variation of coefficient of earth pressure at rest(K0) according to overconsolidation ratio for Sample I

Table 3. The comparison between experimental K0 values and K0 values obtained fromempirical equations

Sample I Sample II Sample III Sample IV

Effective angle of internal friction,

(degree) 28 19 20 14

Plasticity Index, IP(%) 27 57 32 69

K sin10 = [16] 0.531 0.674 0.658 0.758

K sin95.00 = [5] 0.481 0.624 0.608 0.708

)(*007.04.00 PIK += [5]

)(*001.064.00 PIK += [5]0.589 0.697 0.624 0.709

)(*2333.019.00 PILogK += [19] 0.524 0.600 0.541 0.619

Iterative K0 Approach [23, 24] 0.426 0.548 0.518 0.715

Experimental K0 values 0.429 0.533 0.502 0.724

10 100Log (OCR)

2.50

1

0

0.50

1.00

1.50

2.00

Unloading

LoadingK0


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Table 4. Comparison between K0 values obtained from empirical equations and valuesobtained from laboratory tests for over consolidated state (Sample I and Sample II)

Coefficient of earth pressure at rest, K0(NC) 0429

Plasticity index, IP(%) 27

OCR 2.4 1.2 2 4 8 16

Loading 0.665 0.470 - - - -2/1)(0)(0 *OCRKK NCOCR =

[5] Unloading - - 0.607 0.858 1.213 1.716

Loading 0.8 0.58 - - - -( )( ) OCRK sin0 sin1= [18] Unloading - - 0.735 1.018 1.408 1.95

Loading 0.627 0.464 - - - -nNCOCR OCRKK *)(0)(0 =

28110*54.0 PIn = [19] Unloading - - 0.579 0.782 1.055 1.424

Loading 1.317 0.511 - - - -Iterative K0 Approach

[23, 24]Unloading - - - - - -

Loading 1.320 0.510 - - - -

SampleI

Exparimental K0 Values

Unloading - - 0.640 0.980 1.400 2.020

Coefficient of earth pressure at rest, K0(NC) 0.533


OCR 4.6 2.3 1.15 2 4 8 16

Loading 1.143 0.808 0.572 - - - -2/1)(0)(0 *OCRKK NCOCR =

[5] Unloading - - - 0.754 1.066 1.508 2.132

Loading 1.108 0.885 0.706 - - - -( )( ) OCRK sin0 sin1= [18] Unloading - - - 0.845 1.059 1.327 1.663

Loading 0.893 0.707 0.559 - - - -nNCOCR OCRKK *)(0)(0 =

281

10*54.0PI

n

= [19] Unloading - - - 0.674 0.852 1.077 1.362

Loading 1.862 1.085 0.646 - - - -Iterative K0 Approach[23, 24]

Unloading - - - - - - -

Loading 1.892 1.049 0.667 - - - -

SampleII


Unloading - - - 0.771 1.154 1.606 2.328


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Table 5. Comparison between K0 values obtained from empirical equations and valuesobtained from laboratory tests for over consolidated state (Sample III and Sample IV)

Coefficient of earth pressure at rest, K0(NC) 0.502


OCR 2.8 1.4 2 4 8

Loading 0.840 0.594 - - -2/1)(0)(0 *OCRKK NCOCR =

[5] Unloading - - 0.710 1.004 1.420

Loading 0.936 0.715 - - -

( )( )

OCRK sin

0sin1=

[18] Unloading - - 0.809 1.057 1.339

Loading 0.767 0.577 - - -nNCOCR OCRKK *)(0)(0 =

28110*54.0 PIn = [19] Unloading - - 0.668 0.889 1.183

Loading 1.336 0.707 - - -Iterative K0 Approach

[23, 24]Unloading - - - - -

Loading 1.284 0.704 - - -

SampleIII


Unloading - - 0.760 1.081 1.634

Coefficient of earth pressure at rest, K0(NC) 0.720Plasticity index, IP(%) 69

OCR 2.8 1.4 2 4 8 16

Loading 1.205 0.582 - - - -2/1

)(0)(0 *OCRKK NCOCR =

[5]Unloading - - 1.018 1.440 2.036 2.880

Loading 0.973 0.882 - - - -( )( ) OCRK sin0 sin1= [18] Unloading - - 0.896 1.06 1.254 1.483

Loading 0.987 0.798 - - - -nNCOCR OCRKK *)(0)(0 =

281

10*54.0PI

n

= [19] Unloading - - 0.891 1.102 1.363 1.686

Loading 1.192 0.816 - - - -Iterative K0 Approach

[23, 24]Unloading - - - - - -

Loading 1.169 0.817 - -

SampleIV

Exparimental K0 ValuesUnloading - - 1.050 1.520 2.030 2.550


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Nomenclature

OCR Over consolidation ratioCr Liquidity indexDr Relative densitye Void ratioH Height of specimenIp Plasticity indexKo Coefficient of earth pressure at restKo(OCR) Coefficient of earth pressure at rest in over consolidated soilsKo(NC) Coefficient of earth pressure at rest in normally consolidated soils

Kor Coefficient of earth pressure at rest in reloaded soilsK0(unloading) Coefficient of earth pressure at rest at unloading stageNC Normally consolidatedPc Pre-consolidation pressurew Natural water contentwL Liquid limitwp Plastic limitn Constant dependent on plasticity index Constant dependent on liquidity index and loading condition Slope of ground surfacev Vertical stressh Horizontal stressh Measured horizontal stress

Effective angle of internal friction1 Volumetric deformation of soil in the oedometer ringAcknowledgementsThe authors are grateful to technical staff at ukurova University Engineering Faculty SoilMechanics Laboratory for their assistance.

References

[1] Donath, A.D., Untersuchungen Veber den Erddruck auf Stuetzwaende. ZeitschriftFuer Bauwesen., 1891.

[2] Lambe, W., Whitman, R.V., Soil Mechanics, John Wiley&Sons, New York, 1969.[3] Bishop, A.W., Henkel, D.J., The Measurement of Soil Properties in the Triaxial

Test., Arnold Publishing Company, London, 1962.[4] Hendron, A.J., The Behaviour of Sand in One Dimensional Compression,

Ph.D.Thesis, University of Illinois, 1963.[5] Brooker, E.W., Ireland, H.O., Earth Pressures at Rest Related to the Stress History.

Canadian Geotechnical Journal, Vol.2, 1-15, 1965.[6] Campanella, R., Vaid, Y., A Simple Ko Triaxial Cell. Canadian Geotechnical

Journal, Vol.9, No.3, 249-260, 1972.


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[7] Salamer, A., Kohezyonsuz Zeminlerde Skunetteki Toprak Basnc KatsaysnnZemin Parametreleri Cinsinden fadesi, T, Doktora Tezi, stanbul, 1972.

[8] Abdelhamid, M.S., Krizek, R.J., At Rest Lateral Earth Pressure of a ConsolidationClay, Journal of Geotechinal Engineering, Vol.102, No.GT7, 721-738, 1976.

[9] Edil T.B., Dhowian, A.W., At-Rest Lateral Pressure of Peat Soils. Journal ofGeotechnical Engineering Divison, ASCE, Vol.107, 201-220, 1981.

[10] Craig, R.F., Soil Mechanics, Chapman & Hall, London 1994.[11] Bedikan, E., Effects of Overconsolidation Ratio on Coefficient of Lateral Earth

Pressure At-Rest., METU, M.S.in Civil Engineering, 1993.[12] Kayadelen, C., Ko Koullarnda Yanal Zemin Basnlarn rdelenmesi, Yksek

Lisans Tezi, ukurova niversitesi, Adana, 2001.[13] Basmac, E., Skunetteki Toprak Basnc Katsaysnn belirlenmesi ve Baz Zemin

zellikleri ile likisi, Yksek Lisans Tezi, Sleyman Demirel niversitesi, 2002.[14] Tavenas, F.A., Blanchette G., Leroueil, S. Roy, M., Larochell P., In-situ

Determination of Ko in Soft Sensitive Clays, Proceedings In-situ Measurement ofSoil Properties. Vol.1, 450-476, 1975.

[15] Massarsch, K.R., Holtz, R.D., Holm, B., Measurement of Horizantal In-SituStresses, Proceedings Insitu Measurement of Soil Properties, Vol.1, 266 - 286, 1975

[16] Jacky, J., The Coefficient of Earth Pressure at Rest, Journal for Society ofHungarian Architects and Engineers, Budapest, 355-358, 1944.

[17] Kezdi, A., Stability of Rigid Structures, Proc.5 ECSMFE, Vol.2, 105-130, 1972.[18] Mitchel, J.K., Fundamentals of Soil Behavior. 2nd Ed, John Wiley&Sons, 1993.[19] Alpan, I., The Empirical Evaluation of the Coefficient Ko and Kor., Soils and

Foundations, Vol.7, No.1, 31-40, 1967.[20] Mayne, P.W., Kulhawy F.H., Ko-OCR Relationship in Soil, Journal of Geotechnical

Engineering Division,Vol.108, 851-872, 1982.[21] Das, B.M., Principles of Foundation Engineering. 4th Ed, Brooks Cole, 1998.[22] Cherubine, C., Giasi, C.I., and Guadagno, F.M., The Coefficient of Earth Pressure at

rest. Can. Geotech, Vol.31, 790-791, 1994[23] Tekinsoy, M.A., An Approximation to Lateral Earth Pressures for K0 Condition,

Journal of Engineering Sciences, Vol.5, No.1, 933-942, Pamukkale UniversityEngineering Faculty, Denizli, 1999.

[24] Tekinsoy, M.A., Laman, M., Elastik Zemin Problemleri, SDU Yaynlar No 6,Isparta, 2000.

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