fall-cone penetration and water content relationship of clays.pdf

Fall-cone penetration and water content relationship of clays

TAO-WEI FENG

Results of previous studies on using the fall-cone test todetermine the plastic limit of soils show that further re-search is warranted. The present investigation devotes itselfto modication of the specimen preparation technique, ex-amination of the relationship between depth of cone penetra-tion and water content, and estimation of the plastic limitusing the penetration depth against water content relation-ship. Specimen rings are made and used to replace thespecimen cup so as to facilitate the preparation of speci-mens. Data of 26 soils, covering a wide range of liquid limitsfrom 30% to 526%, show that the logarithm of depth ofcone penetration against logarithm of water content relation-ship is linear. Therefore, a linear equation with two soil-dependent parameters is developed for estimation of theplastic limit. For a soil, the value of the soil-dependentparameters can be determined from as little as four fall-cone tests and substituted into the equation to estimate theplastic limit. The computed plastic limits of the soils ana-lysed are within 0812, with an average value of 1, timesthe measured plastic limits. The effects of strain rate andundrained strength ratio on the estimation of the plasticlimit are evaluated and found to be limited.

KEYWORDS: clays; laboratory tests; plasticity; shear strength.

Les resultats des etudes precedentes sur l'utilisation du testdu cote de chute pour determiner la limite plastique des solsindiquent de des travaux de recherche additionnels sontnecessaires. Les recherches actuelles sont consacrees a lamodication de la technique de preparation des specimens, al'examen des rapports entre profondeur de penetration ducone et teneur en eau, et l'estimation de la limite plastiqueen utilisant le rapport profondeur de penetration du cone/teneur en eau. On a produit des bagues specimen que l'on autilisees pour remplacer le gobelet specimen, an de faciliterla preparation des specimens. Des donnees sur vingt-six sols,portant sur une large plage de limites liquides de 30% a526%, indiquent que le rapport entre l'algorithme de laprofondeur de penetration du cone et celui de la teneur eneau est lineaire. En consequence, on produit une equationlineaire avex deux parametres fonction du sol pour l'estima-tion de la limite plastique. Pour un certain sol, on est enmesure de determiner la valeur de parametres tributaires dusol avec un nombre d'essais au cone pouvant etre inferieur aquatre, que l'on peut substituer ensuite dans l'equation pourevaluer la limite plastique. Les limites plastiques calculeespour les sols analyses sont comprises entre 08 at 12, avecune valeur moyenne de 1, multipliees par les limites plas-tiques mesurees. On a evalue les effets de la vitesse dedeformation et du rapport de resistance non draine surl'evaluation de la limite plastique et ils se sont avereslimites.

INTRODUCTION

The use of laboratory cone penetrometers to determine theliquid limit of soils has been studied in detail (e.g. Terzaghi,1927; Sowers et al., 1959; Karlsson, 1961; Sherwood & Riley,1970; Littleton & Farmilo, 1977; Garneau & Le Bihan, 1977;Wroth & Wood, 1978; Houlsby, 1982; Wood, 1982; Whyte,1983; Wood, 1985; Wasti & Bezirci, 1986; Leroueil & LeBihan, 1996; Farrell et al., 1997). The British Standard (BS1377:pt2: 1990), the Swedish Standard (SS 027120:1990) andthe Canadian Standard (CAN/BNQ 2501-092-M-86) have in-cluded the determination of the liquid limit by using fall-cones.On the other hand, only a few studies (e.g. Wood & Wroth,1978; Belviso et al., 1985; Harison, 1988) have focused on thedetermination of the plastic limit by the fall-cone test.

It was generally recognized that fall-cone tests were difcultto perform at water contents near the plastic limit, since soilsamples were stiff and difcult to mix (Wood & Wroth, 1978;Whyte, 1983; Wasti & Bezirci, 1986; Harison, 1988; Stone &Phan, 1996). Furthermore, in BS 1377 (1990), Test 2(A)(British Standards Institution, 1990), the test procedure fordetermination of liquid limit includes the following: `The re-mixed soil shall be pushed into the cup with a palette knife,taking care not to trap air.' The process of placing the soil intothe specimen cup is inuenced by individual judgement and isprobably the most difcult step in the fall-cone test. In fact,pushing soil into the cup may not be good practice, since thesoil is repeatedly loaded, although this effect is difcult toevaluate. This problem becomes more serious as the watercontent of the soil sample decreases.

Since it is difcult to carry out the fall-cone test at water

contents near the plastic limit, the relationship between logarith-mic depth of fall-cone penetration and water content has beenused to estimate the value of the plastic limit. Based on thecritical state theory, Wood & Wroth (1978) and Belviso et al.(1985) suggest that the logarithmic depth of penetration againstwater content relationship is linear between the liquid limit andthe plastic limit, and the slope of this relationship is equal toone half of the plasticity index. Then, the plastic limit can becomputed by subtracting the plasticity index from the liquidlimit. However, the relationship has been found to be highlynon-linear for a number of soils (e.g. Karlsson, 1961; Wood,1985; Wasti & Bezirci, 1986; Harison, 1988).

The penetration depth corresponding to the liquid limit is20 mm for the 308 British cone. Hansbo (1957) proposes thefollowing equation:

su k Wd2

(1)

where su is undrained shear strength, k is a constant, W is theweight of cone, and d is depth of penetration. It can be seenfrom equation (1) that undrained shear strength is inverselyproportional to the square of the depth of penetration. The dataof Skempton & Northey (1953) show that the undrained shearstrength at the plastic limit is about 100 times the undrainedshear strength at the liquid limit. Thus, it can be computed fromequation (1) that the depth of cone penetration at the plasticlimit is about 2 mm for the 308 cone. Harison (1988) suggests abilinear model indicating that the relationship is linear fordepths of penetration either greater or smaller than 14 mm.Therefore, the plastic limit can be estimated by extrapolating alinear relationship obtained from two to three fall-cone testswith depth of penetration smaller than 14 mm. However, withthe general lack of sufcient published information on thelogarithmic depth of cone penetration against water contentrelationship in between depths of penetration of 14 cm and

181

Feng, T. W. (2000). Geotechnique 50, No. 2, 181187

Manuscript received 7 July 1999; revised manuscript accepted 4October 1999.Discussion on this paper closes 4 August 2000; for further details see p. ii. Chung Yuan Christian University.

2 mm, a question as to whether the bilinear model is appro-priate still remains.

In summary, it appears that further studies are warranted inthe following areas:

(a) modication on the specimen preparation technique(b) examination of the shape of the relationship between

logarithm depth of cone penetration and water content,especially for depths of penetration less than 14 mm

(c) estimation of the plastic limit by using the depth ofpenetration and water content relationship.

This paper presents the results of a study focused on the above-mentioned areas.

TEST PROGRAMME

A set of fall-cone apparatus (made by Wykeham Farrance,Inc.), with a 308 cone (weight 80 g) was used during thisinvestigation. As difculties in specimen preparation are primar-ily associated with placing soil samples into the specimen cup,the cup was modied during this investigation by removing thebottom of the cup, keeping the diameter and the height of thecup unchanged. As a result, the specimen cup became a speci-men ring. Furthermore, one end of the ring was sharpened, asshown in Fig. 1(a), to facilitate penetration into soil samples. Infact, a stainless steel ring 55 mm in diameter, 40 mm in heightand 2 mm in thickness was used for depths of cone penetrationin between 25 mm and 10 mm. For depths of cone penetrationless than 10 mm, a shallower stainless steel ring (20 mm inheight) was used so that smaller amounts of soil were neededfor the tests.

The specimen preparation procedure started with mixing thesoil sample thoroughly on a large square glass plate (30 330 cm) at water contents slightly higher than the liquid limit. Asingle batch of the mixed soil sample was then transferred to asmall square glass plate (10 3 10 cm) to make a soil mound, asshown in Fig. 1(b), with lateral and vertical dimensions greaterthan the dimensions of the specimen ring used. Two spatulaswere used to mix the soil samples and to make the soil mound,to reduce the possibility of trapping air within the specimen.Furthermore, only small pressures are exerted on the soil, sothat their effect on the test result may be ignored. The specimenring was then placed on top of the soil mound with the

sharpened end facing downwards, as shown in Fig. 1(c). Initiallevelling of the ring can be done with a hand level and a smallglass plate placed at the top of the ring. After the initiallevelling, the ring was pushed downwards by hand until itreached the glass plate, as shown in Fig. 1(d). A wire-saw and astraight edge were then used to remove excess soil from the topof the ring, so as to obtain a at surface, as shown in Fig. 1(e).Lastly, the soil specimen together with the small glass plate wastransferred to the base stand below the fall-cone for the penetra-tion test.

Samples of kaolin, bentonite and three natural soils wereprepared at water contents slightly higher than the liquid limitsand then stored overnight before testing. For each soil, the fall-cone tests were carried out starting from water contents slightlyhigher than the liquid limit to water contents as near the plasticlimit as possible. After each fall-cone test, the water content ofthe soil specimen was measured. The remaining soil samplewas spread over the large glass plate for air-drying for the nextfall-cone test. The time required for proper air-drying of thesoil sample depends on a number of factors, such as the contactareas between the soil and the air, the plasticity of the soil, etc.In order to dene better the penetration depth against watercontent relationship, the fall-cone tests were carried out at asmany water contents as possible.

RELATIONSHIP BETWEEN DEPTH OF CONE PENETRATION AND

WATER CONTENT

Relationships between logarithmic depth of cone penetrationand water content for the soils tested during the present in-vestigation are shown in Figs 26. It can be seen from thesegures that these relationships are all non-linear in nature andthe minimum depths of penetration are as low as 31 mm.Incidentially, these data can be used to check Harison's (1988)bilinear model. In order to quantify the non-linearity of thecurves, secant slopes of the curves between 14 mm penetrationand 5 mm penetration for Sinjun clay, Taipei clay, Panama clay,kaolin and bentonite are rst determined as 19%, 22%, 73%,23% and 360%, respectively. In contrast, the tangent slopes ofthe curves at 5 mm penetration for Sinjun clay, Taipei clay,Panama clay, kaolin and bentonite are 12%, 9%, 55%, 13% and225%, respectively. It is thus apparent from these data that theuse of the bilinear model to estimate the value of the plasticlimit will result in an underestimation.

ESTIMATION OF THE PLASTIC LIMIT

In order to estimate the plastic limits, the non-linear regres-sion curves shown in Figs 26 may be manually extended with

Specimen ring

H D

(a)

(b) (c)

(d) (e)

10 cm Glass plate

Soil Soil

Soil Soil

Fig. 1. Side views of (a) the specimen ring, (b) the soil mound andthe glass plate, (c) the specimen ring placed on top of the soilmound, (d) the specimen ring fully penetrating the soil mound, and(e) excess soil removed from the top of the specimen ring

60

50

40

30

20

10

Wate

r con

tent

: %

30 20 10 7 5 3 2 1Penetration depth: mm

Sinjun clayPL(conventional) = 19%

Fig. 2. Logarithm of penetration depth against water content rela-tionship for Sinjun clay

182 FENG

the help of a French curve to the depth of cone penetration of2 mm. Results of the estimations show that the plastic limits ofSinjun clay, Taipei clay, Panama clay, kaolin and bentonite are20%, 25%, 61%, 26% and 38%, respectively, which agree wellwith the plastic limit values obtained from conventional tests,given in Figs 26. It may be noted from Figs 26 that 814data points are shown for each soil. The large number of datapoints ensures that the curves are well dened. It is impracticalin engineering practice to carry out such a large amount of testsfor estimation of the plastic limit.

On the other hand, the data shown in Figs 26 can be re-plotted on loglog scales, as shown in Fig. 7. Similar plots canbe made using the data of Skempton & Northey (1953),Karlsson (1961), Wood, (1985), Wasti & Bezirci (1986) andHarison (1988), as shown in Figs 812, respectively. Based onthe data shown in Figs 712, a linear model is proposed for theloglog relationship and is expressed by the following equation:

log w log c m log d (2)where w is water content, c is water content at d 1 mm, m isthe slope of the linear relationship, and d is the depth of conepenetration. Values of c and m obtained from linear regressionanalyses of the data presented in Figs 712 are listed in Table 1.

60

50

40

30

20

10

Wa

ter c

onte

nt: %


Taipei clayPL(conventional) = 24%

Fig. 3. Logarithm of penetration depth plotted against water contentrela-tionship for Taipei clay

150

120

90

60

30

Wate

r con

tent

: %


Panama clayPL(conventional) = 59%

Fig. 4. Logarithm of penetration depth plotted against water contentrela-tionship for Panama clay

60

50

40

30

20

10

Wate

r con

tent

: %


KaolinPL(conventional) = 25%

Fig. 5. Logarithm of penetration depth plotted against water contentrela-tionship for kaolin

500

400

300

100

200

0

Wa

ter c

onte

nt: %


BentonitePL(conventional) = 37%

Fig. 6. Logarithm of penetration depth plotted against water contentrela-tionship for bentonite

10

100

1000

Wate

r con

tent

: %


Sinjun clay

Bentonite

Panama clay

Kaolin

Taipei clay

Fig. 7. Loglog plot of penetration depth plotted against watercontent rela-tionships for the ve soils tested

FALL-CONE PENETRATION AND WATER CONTENT RELATIONSHIP OF CLAYS 183

It may be noted from Table 1 that the bentonite samples haveliquid limits of about 423% and 526%, the kaolin samples haveliquid limits of 50% and 59%, and the other 22 natural soilsshow a wide range of liquid limits ranging from 30% to 125%.Both of the bentonite specimens gave the same m value of 1,which is much larger than the m values from 0216 to 0569 forthe natural soils. A large value of m indicates a higher rate ofdecrease in water content with decreasing depth of penetration.A large value of c implies a large value of the plastic limit. ThePanama clay specimen tested has an organic content of 12%,which is probably responsible for its large c value of 47%. The cvalues of the Bandung clays are rather high, that is 3039%;probably these soils are organic to some degree, but informationon the composition of these soils is absent.

The existence of the linear relationship as expressed byequation (2) is useful for estimation of the plastic limit. For asoil, c and m can be determined from results of as few as fourfall-cone tests with depths of penetration evenly distributedbetween 25 mm and 3 mm. Equation (3) can then be used tocompute the plastic limit:

PL c(2)m (3)For example, the c and m values as listed in Table 1 and

equation (3) are used to compute the plastic limit values of the26 soils. The computed plastic limits are compared with theplastic limits determined by the conventional method, as shownin Fig. 13. The dashed lines in Fig. 13 show that the computedplastic limits are within 0812 times the measured plasticlimits, with an average value of 10. The discrepancies betweenthe measured and the computed plastic limits may result fromseveral reasons, such as the undrained strength ratio of 100adopted and problems associated with the conventional plasticlimit test.

The empirical ratio of undrained strength at the plastic limitto undrained strength at the liquid limit is estimated from thedata of Skempton & Northey (1953) as 100. However, Whyte(1982, 1983) suggests that the strength ratio derived from thedata of Skempton & Northey (1953) should be about 70.Furthermore, the data of Karlsson (1961) indicate a range of thestrength ratio from 50 to 100 for some Swedish clay and astrength ratio of about 200 for both a quick clay and a varvedclay. Now as equation (2) is developed, it is possible to examinethe effect of the strength ratio on the estimated plastic limit.According to equation (1), strength ratios of 50, 100 and 200correspond to depths of penetration of 28, 2 and 14 mm,respectively. For the soils listed in Table 1, the correspondingwater contents are computed using both equation (2) and valuesof c and m, and the results are also shown in Table 1. It maybe concluded from Table 1 that, except for the bentonite, theestimated plastic limits are affected by the strength ratioassumption around 1020%, which is consistent with the datashown in Fig. 13. The bentonite probably has a strength ratioslightly lower than 100, as the computed water content of 34%,corresponding to depth of penetration of 2 mm, is slightlysmaller than the measured plastic limit of 37%.

The measured plastic limits shown in Fig. 13 were deter-mined by the conventional plastic limit test, in which a soilthread was rolled to 3 mm diameter before it crumbled onrolling. The water content of the crumbled soil thread has beendened as the plastic limit. However, the stress system appliedto the soil thread during rolling is highly complicated and is notcontrolled. Whyte (1982) reported that the plastic limit of a claydetermined in different laboratories ranged from 19% to 39%,with an average plastic limit of 23%. He further concluded thatthe rolling thread test does not provide reliable and consistentresults for the plastic limit. Since the data shown in Fig. 13come from at least four different groups of people and fourdifferent laboratories, it is expected that some uncontrolledfactors during the conventional plastic limit test have played arole in the discrepancies between the measured and the com-puted plastic limits.

The fall-cone test is much more reliable than the conven-tional plastic limit test. As can be seen in both Fig. 14 and

Fig. 8. Loglog plot of penetration depth plotted against watercontent rela-tionships according to the data of Skempton & Northey(1953)

Fig. 9. Loglog plot of penetration depth plotted against watercontent rela-tionships according to the data of Karlsson (1961)

Fig. 10. Loglog plot of penetration depth plotted against watercontent relationships according to the data of Wood (1985)

184 FENG

Table 2, both the logarithm of penetration depth against loga-rithm of water content relationships and the (c, m) data ofkaolin obtained by ve persons demonstrate excellent repeat-ability of the fall-cone test. It is worthy of note that four of theve persons had no previous experience with the fall-cone testand were taught only once how to run the test. It is clear fromthe present investigation that mixing the soil specimen thor-oughly during preparation is one of the most important steps inthe fall-cone test.

STRAIN RATE EFFECT

It is generally known that the undrained shear strength ofsaturated clays is a function of strain rate. Since the fall-conetest is in fact a strength test, the effect of strain rate, if any, onthe test results must be evaluated.

In the absence of data on the time rate of cone penetration,an average strain rate for 20 mm and 4 mm of penetration may

be evaluated as follows. The volume of the portion of the 308cone penetrating into the specimen can be computed usingequation (4):

V 0:075h3 (4)

where h is depth of penetration. A zone of inuence of thecone penetration must be dened so that induced volumetricstrain can be determined. The inuence zone may be assumedto have a conical shape having a height equal to the depth ofpenetration and a diameter of three times the cone diameter(Houlsby, 1982). Then the volumetric strain induced by conepenetration is 11% and is independent of the depth of penetra-tion. On the other hand, experience obtained during the presentinvestigation showed that a penetration of 20 mm takes aboutve times as long as a penetration of 4 mm. Therefore, a ratioof average strain rates between 20 mm and 4 mm of penetra-tions can be computed using equation (5):

Table 1. Values of c and m parameters of clays and water contents computed from strength ratios of 50, 100 and 200

Soil LLCasagrande: % c: % m w1:4: % w2: % w2:8: % w1:4=w2: w2:8=w2 Reference

Sinjun clay 36 14 0322 16 18 20 089 111 Present investigationTaipei clay 43 17 0322 19 21 24 090 114 Present investigationPanama clay 125 47 0321 52 59 66 088 112 Present investigationKaolin 50 20 0301 22 25 27 088 108 Present investigationBentonite 423 17 1 24 34 48 071 141 Present investigationShellhaven clay 97 26 0436 30 35 41 086 117 Skempton & Northey (1953)London clay 73 21 0410 24 28 32 086 114 Skempton & Northey (1953)Horten clay 30 13 0266 14 16 17 088 106 Skempton & Northey (1953)Gosport clay 80 28 0352 32 36 40 089 111 Skempton & Northey (1953)Swedish clay 83 26 0425 30 35 40 086 114 Karlsson (1961)Swedish clay 70 25 0360 28 32 36 088 113 Karlsson (1961)Swedish clay 63 22 0360 25 28 32 089 114 Karlsson (1961)Swedish clay 54 21 0308 23 26 29 088 112 Karlsson (1961)Drammen clay 35 12 0350 14 15 17 093 113 Wood (1985)Kaolin 59 21 0343 24 27 30 089 111 Wood (1985)Gault clay 65 23 0345 26 29 33 090 114 Wood (1985)Bentonite 526 16 1 22 32 45 069 141 Wasti & Bezirci (1986)Turkey soil 110 20 0569 24 30 36 080 120 Wasti & Bezirci (1986)Turkey soil 52 21 0335 24 26 30 092 115 Wasti & Bezirci (1986)Bandung clay 100 39 0312 43 48 54 090 113 Harison (1988)Bandung clay 86 31 0341 35 39 44 090 113 Harison (1988)Bandung clay 78 30 0318 33 37 42 089 114 Harison (1988)Bandung clay 72 30 0292 33 37 41 089 111 Harison (1988)Bandung clay 65 32 0237 35 38 41 092 108 Harison (1988)Bandung clay 63 30 0239 33 35 38 094 109 Harison (1988)Bandung clay 59 31 0216 33 36 39 092 108 Harison (1988)

Fig. 11. Loglog plot of penetration depth plotted against watercontent relationships according to the data of Wasti & Bezirci(1986)

Fig. 12. Loglog plot of penetration depth plotted against watercontent relationships according to the data of Harison (1988)


_4_20 t20

t4 5 (5)

The effect of strain rate on undrained shear strength can thenbe computed by using equation (6):

su(4) su(20)su(20)

_4_20

C=Cc(6)

where su is undrained shear strength, _ is strain rate, c is thesecondary compression index, and cc is the compression index(Terzaghi et al., 1996). For example, the value of C=Cc can betaken as 004 for inorganic clays, and the effect of strain rate

on undrained shear strength is computed using equation (6) tobe 7% between 20 mm and 4 mm penetrations.

CONCLUSIONS

The following conclusions are based on data and analysespresented in the previous paragraphs:

(a) The specimen preparation technique has been improved byusing specimen rings to hold the specimens. The process ofspecimen preparation with the specimen ring is faster andeasier than that with a specimen cup, and it reduces thechances of trapping air in the specimen. Furthermore, thespecimen ring is pushed into the soil, instead of pushingsoil into the specimen cup. For liquid limit determinations,the specimen ring retained the dimensions of the specimencup. For depths of penetration less than 10 mm, a specimenring of 20 mm in height can be used so that less soil isneeded for the fall-cone test.

(b) The relationship between logarithmic depth of penetrationand water content in the range from the liquid limit to theplastic limit is generally non-linear. The minimum depth ofpenetration attainable with the specimen ring is about3 mm. For the ve soils tested during the present investi-gation, an attempt to extend the non-linear regressioncurves from around 3 mm to 2 mm penetration gives a closeestimate of the plastic limits, though these non-linear curvesare dened by 814 data points. On the other hand, therelationship between logarithmic depth of penetration andlogarithmic water content is linear. This relationship can bedened by as few as four data points with depths ofpenetration evenly distributed between 25 mm and 3 mm.This makes the fall-cone test easier to perform to determinethe plastic limit.

(c) Based on the linear model of the relationship betweenlogarithmic depth of penetration and logarithmic watercontent and an undrained strength ratio of 100, an equationis derived for estimation of the plastic limit. This equationincludes two soil-dependent parameters which can bedetermined from at least four fall-cone tests and substitutedinto the equation to estimate the plastic limit. For the 26soils analysed, the computed plastic limits are within 0812, with an average value of 10, times the measured plasticlimits. Factors such as the assumption of strength ratio of100 and problems associated with the conventional plasticlimit test could have contributed to the discrepanciesbetween the computed and the measured plastic limits.The plastic limits computed using the undrained strengthratios of 50 and 200 are affected by 1020% of the plasticlimits estimated using the undrained strength ratio of 100for most of the soils analysed. The strain rate effect in thefall-cone test is small. For a variation in depth ofpenetration from 20 mm to 4 mm, the strain rate effect onundrained strength is estimated as 7% for inorganic clays.

REFERENCESBelviso, R., Ciampoli, S., Cotecchia, V. & Federico, A. (1985). Use of

the cone penetrometer to determine consistency limits. GroundEngng 18, No. 5, 2122.

British Standards Institution (1990). Methods of test for soils for civilengineering purposes. British Standards Institution BS 1377. London.

Canadian Standards Association and Bureau de normalisation du Quebec(1986). Soils-Determination of liquid limit by the Swedish fall conepenetrometer method and determination of plastic limit. CAN=BNQ2501-092-M-86.

Farrell, E., Schuppener, B. & Wassing, B. (1997). ETC 5 fall-conestudy. Ground Engng 30, No. 1, 3336.

Garneau, R. & Le Bihan, J. P. (1977). Estimation of some properties ofChamplain clays with the Swedish fall-cone. Can. Geotech. J. 14,No. 3, 571581.

Hansbo, S. (1957). A new approach to the determination of the shearstrength of clay by the fall-cone test. R. Swedish Geotech. Inst.Proc. No. 14, 747.

Fig. 13. Computed plastic limits plotted against measured plasticlimits

10

100

Wate

r con

tent

: %


Kaolin

Fig. 14. Loglog plot of penetration depth versus water contentrelationships determined by ve persons for the repeatability study.One person determines one relationship as represented by aregression line passing through points of the same symbol.

Table 2. Values of c and m for kaolin determined for therepeatability study

Testno.

PL (measured):%

c: % m PL (computed): %

1 25 20 0301 252 25 19 0295 233 25 19 0316 244 25 20 0281 245 25 21 0281 26

186 FENG

Harison, J. A. (1988). Using the BS cone penetrometer for the deter-mination of the plastic limits of soils. Geotechnique 38, No. 3,433438.

Houlsby, G. T. (1982). Theoretical analysis of the fall-cone test. Geo-technique 32, No. 2, 111118.

Karlsson, R. (1961). Suggested improvements in the liquid limit test,with reference to ow properties of remoulded clays. Proc. 5thICSMFE 1, 171184.

Leroueil, S. & Le Bihan, J. P. (1996). Liquid limits and fall cones. Can.Geotech. J. 33, No. 5, 793798.

Littleton, I. & Farmilo, M. (1977). Some observations on liquid limitvalues. Ground Engng 10, No. 4, 3940.

Sherwood, P. T. & Riley, M. D. (1970). An investigation of a cone-penetrometer method for the determination of the liquid limit.Geotechnique 20, No. 2, 203208.

Skempton, A. W. & Northey, R. D. (1953). The sensitivity of clays.Geotechnique 3, No. 1, 3053.

Sowers, G. F., Vesic, A. & Grandol, M. (1959). Penetration tests forliquid limit. Philadelphia ASTM, STP No. 254, 216224.

Stone, K. J. L. & Phan, K. D. (1996). Cone penetration tests near theplastic limit. Geotechnique 45, No. 1, 155158.

Swedish Standards Commission (1990). Geotechnical tests cone liquidlimit. Swedish Standards Commission, Stockholm, SS 027120.

Terzaghi, K. (1927). Determination of consistency of soils by means ofpenetration tests. Public Roads 7, No. 12, 240247.

Terzaghi, K., Peck, R. B. & Mesri, G. (1996). Soil mechanics inengineering practice, 3rd edn. New York: Wiley.

Wasti, Y. & Bezirci, M. H. (1986). Determination of the consistency limitsof soils by the fall-cone test. Can. Geotech. J. 23, No. 2, 241246.

Whyte, I. L. (1982). Soil plasticity and strengtha new approach usingextrusion. Ground Engng 15, No. 1, 1624.

Whyte, I. L. (1983). Cone penetrometer and liquid limit. Geotechnique33, No. 1, 7677.

Wood, D. M. (1982). Cone penetrometer and liquid limit. Geotechnique32, No. 2, 152157.

Wood, D. M. (1985). Some fall-cone tests. Geotechnique 35, No. 1,6468.

Wood, D. M. & Wroth, C. P. (1978). The use of the cone penetrometerto determine the plastic limit of soils. Ground Engng 11, No. 3, 37.

Wroth, C. P. & Wood, D. M. (1978). The correlation of index propertieswith some basic engineering properties of soils. Can. Geotech. J. 15,No. 2, 137145.


INTRODUCTIONTEST PROGRAMMERELATIONSHIP BETWEEN DEPTH OF CONE PENETRATION AND WATER CONTENTESTIMATION OF THE PLASTIC LIMITSTRAIN RATE EFFECTCONCLUSIONSREFERENCES

fall-cone penetration and water content relationship of clays.pdf

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