properties and behaviour of hong kong marine deposits with different clay contents

Properties and behaviour of Hong Kong marinedeposits with different clay contents

Jian-Hua Yin

Abstract: Large-scale marine reclamation has taken place on soft Hong Kong marine deposits (HKMD). More andmore reclamation is to be undertaken due to the rapid development of infrastructures and housing projects. Propertiesand behavioural parameters (e.g., consolidation parameters) of HKMD are required for the design of reclamation orfoundations on HKMD. The behaviour of HKMD is affected by clay content and other factors. This paper presentsresults dealing with the (i) composition (content of clay, silt, and sand), (ii ) index properties, (iii ) behaviour duringoedometer consolidation, and (iv) strength and deformation behaviour in triaxial compression for HKMD deposits withdifferent clay contents. Correlations of the behavioural parameters with clay content and index properties are obtained,presented, and discussed. The correlations and parameter values obtained in the present study follow the same trend asthose published in the literature. Limitations on the application of these correlations are pointed out.

Key words: clay content, plasticity index, index property, compression index, coefficient of consolidation, friction angle.

Résumé: Du remblayage à grande échelle empiétant dans la mer a été réalisé sur les dépôts marins de Hong Kong(DMHK). De plus en plus de remblayage d’empiétement se produira par suite du développement rapide des projetsd’infrastructures et d’habitations. Les propriétés et les paramètres de comportement (e.g. paramètres de consolidation)de DMHK sont requis pour la conception du remblai et des fondations sur ces dépôts. Le comportement des dépôtsmarins est affecté entre autres facteurs par la teneur en argile. Cet article présente les résultats concernant (i) lacomposition (teneur en argile, silt et sable), (ii ) les indices des propriétés, (iii ) le comportement durant la consolidationdans l’oedomètre et (iv) la résistance et le comportement en déformation au cours de la compression triaxiale desDMHK avec différentes teneurs en argile. Des corrélations entre ces paramètres de comportement et la teneur en argileet les indices de propriétés ont été obtenues, et sont présentées et discutées. L’on trouve que les corrélations et lesvaleurs des paramètres obtenues dans la présente étude suivent les mêmes tendances que celles publiées dans lalittérature. L’on signale les limitations dans les applications de ces corrélations.

Mots clés: teneur en argile, indice de plasticité, indice de propriété, indice de compression, coefficient deconsolidation, angle de frottement

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Introduction

The development of infrastructures and civil projects de-mands more and more marine reclamation in Hong Kong’scoastal waters. Most marine deposits encountered in HongKong coastal waters are silt and sand with different claycontents and have low undrained shear strength. The thick-ness of Hong Kong marine deposits (HKMD) may vary froma few metres to more than 20 m. The low strength and highcompressibility of soft HKMD may cause excessive settle-ment–deformation and bearing-capacity failure of reclama-tion and (or) civil structures placed directly or indirectly onHKMD. The design of infrastructures on or installed directlyin HKMD requires estimating parameters such as compress-ibility, creep coefficient, friction angle, and Young’s modu-lus of these soils. These parameters may be evaluated usingtest data on high-quality soil samples. However, obtaininghigh-quality soil samples is often time-consuming and ex-

pensive. Moreover, the soil samples are always disturbed toa certain extent.

The clay content of HKMD may vary from 5 to 70%. Toobtain undisturbed (or less disturbed) HKMD samples repre-sentative of all different clay contents at all locations maynot be feasible in terms of time, cost, and techniques (it isvery difficult to obtain undisturbed or less disturbed samplesof HKMD with high sand content.) One alternative approachis to establish correlations of conventional soil parameterswith the value of clay contents or index properties usingremoulded samples in the laboratory. Both clay contents andindex properties can be easily obtained from particle-sizedistribution tests and index tests carried out on disturbed soilsamples in the laboratory. These correlations may be usedfor preliminary estimation of the soil parameters. In general,the surficial marine deposits in Hong Kong are mostly nor-mally consolidated or have a low overconsolidation ratio(OCR, 1.2–1.3). These deposits have a low sensitivity. Me-chanical properties of remoulded HKMD measured in thelaboratory are considered to be close to the properties of thesoil in the field because of the low sensitivity and OCR.

This paper presents the results of a series of index tests,oedometer tests, and triaxial tests on Hong Kong marine

Can. Geotech. J.36: 1085–1095 (1999) © 1999 NRC Canada

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Received April 28, 1998. Accepted May 19, 1999.

J.-H. Yin. The Department of Civil and StructuralEngineering, The Hong Kong Polytechnic University,Hong Kong, China.

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deposits (denoted HKMD-1) with different clay contents (6,10, 20, and 27.5%). Results from natural Hong Kong marinedeposits at Tseung Kwan O (denoted HKMD-2) and ChekLap Kok (from Koutsoftas et al. 1987) and other clayey soilspublished in the literature are presented and compared withthe results for HKMD-1. Results on HKMD-1 with differentclay contents can be used not only to derive correlations, butalso to provide a systematic data base for in-depth study ofthe effects of composition on the consolidation and triaxialbehaviour of Hong Kong marine deposits.

Test program and basic soil properties

Sample preparationThe marine deposits (HKMD-1) used in the present test

program were taken from a depth of 1–2 m at the locationnear Tai Kwok Tsui ferry pier in Hong Kong’s coastal wa-ters. The marine deposits were a dark grey mixture of clay,silt, and fine sand with occasional shells and coarse parti-cles. To obtain uniform and consistent soil samples, the ma-rine sediments were wet sieved through a 150µm sieve. Themud obtained after wet sieving had a composition of silt andclay with some fine sand. The mud was stored and left tosettle in a plastic container. After at least 1 day of settling,the soil was taken out and poured into a stainless steel cylin-drical mould for preloading and consolidation. This cylindri-cal mould was 300 mm in diameter and 450 mm high. Ametal plate of diameter 290 mm with small holes and anoverlayer of geotextile was placed at the bottom of themould. The same type of plate with an underlayer ofgeotextile was placed on the top of the soil sample. A deadweight of 50 kN was placed on this top plate to consolidatethe soil to a water content of approximately 80–90%. After3–4 days of consolidation, free water on the top plate wasremoved, and water contents at three locations of the soilmass were measured. The average water content,w, wasused to calculate the dry mass of the HKMD in the mould.The wet mass,M, of the HKMD was measured by weighingthe metal mould with and without the soil. The volume ofthe soil could also be measured. The dry massMs was calcu-lated asMs = M/(1 + w).

Dry silicon sand with two different size ranges (150–300and 300–600µm) and 50% dry mass for each size range waspoured into the mould and mixed thoroughly with theHKMD at four different dry mass mixing ratios: C1 (25%HKMD with 75% silicon sand), C2 (50% HKMD with 50%silicon sand), C3 (75% HKMD with 25% silicon sand), andC4 (100% HKMD with 0% silicon sand).

After mixing, dead weights were placed gradually on thetop plate until a maximum pressure of 30–40 kPa wasreached. The consolidation was checked by monitoring theexcess pore-water pressure at the bottom of the soil sampleusing a pressure transducer attached to the bottom of themould. After consolidation was completed, thin-wall PVCtubes of internal diameter of 75 mm (for oedometer testing)or 50 mm (for triaxial testing) were pushed vertically intothe consolidated HKMD sample (called HKMD-1, eventhough mixed with additional sand). Tube samples that werenot used immediately were sealed with wax on the top andbottom ends. For oedometer testing, the tube sample waspushed out and trimmed into a specimen 75 mm in diameter

and 19 mm high. A triaxial specimen was prepared using a50 mm diameter tube sample.

Composition and basic soil propertiesTests for measuring specific gravity, Atterberg limits, and

initial water content (before testing) of HKMD-1 were car-ried out according to British Standard 1377 (British Stan-dards Institution 1990). The results for the four differentratios (C1–C4) are summarized in Table 1.

Wet sieving and hydrometer tests were carried out on thedifferent mixes. The particle-size distribution curves areshown in Fig. 1 and the percentages of clay, silt, and sandare given in Table 2.

Using the data in Table 2, compositional relationships be-tween clay content (C) and silt content (Silt), clay and siltcontent (CSilt), and as-moulded initial water content (w) areshown in Fig. 2. A straight line is used to fit measured dataand plotted in Fig. 2. The best-fit lines are as follows:

[1] Silt = 1.89C + 6.37

[2] CSilt = 2.89C + 6.37

[3] w = 1.53C + 13.26

The R2 in Fig. 2 is the coefficient of determination andwill be in the range from 0 to 1. The closer to 1 theR2 value,the better the regression fitting. The values ofR2 are 0.96,0.98, and 0.96, respectively, for eqs. [1], [2], and [3].

The test results for liquid limitwL andC, plasticity indexIP andC, and plastic limitwP andC are shown in Fig. 3. Astraight line is used to best fit the test results ofwL and C(R2 = 0.995) andIP and C (R2 = 0.90) as follows:

[4] wL = 1.70C + 13.5

[5] IP = 1.26C

The best-fit line forwP and C can be calculated usingeqs. [4] and [5], sincewP = wL – IP

[6] wP = 0.44C + 13.50

The relationship of plastic limitwP and clay contentC ineq. [6] is shown in Fig. 3 and is in good agreement withmeasured data points.

The ratio of IP to clay contentC is defined as activity.From eq. [5], the activity of HKMD-1 is 1.26. Figure 4ashows a comparison of the activity of HKMD-1 with activityvalues for other clayey soils (data from Skempton 1953;Lupini et al. 1981; and Muir Wood 1990). Figure 4b com-pares the relationships betweenIP and C for HKMD-1 andnatural Hong Kong marine deposits (HKMD-2) taken from a

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C1 C2 C3 C4

Specific gravityGs 2.65 2.66 2.66 2.66

Initial water contentw (%) 22 31 40 57

Liquid limit wL (%) 23 32 47 60

Plastic limit wP (%) 14 15 20 29

Plasticity indexIP (%) 8 17 27 32

Table 1. Specific gravity, Atterberg limits, and water content fordry mass mixing ratios C1–C4.



site at Tseung Kwan O (a new development area) in HongKong. The data for HKMD-2 were from commercial soillaboratories in Hong Kong. The best-fit line to the datapoints in Fig. 4 has a slope (activity) of 0.885, which issmaller than the activity of 1.26 for HKMD-1 shown inFigs. 4a and 4b. The composition of HKMD-2 may not bethe same as that of HKMD-1. Figure 4b shows large scatterof the data. The slope of the line for HKMD-1 is within therange of these data points.

Oedometer test results, correlations, anddiscussion

Oedometer tests were carried out using Casagrande-typeoedometers. The loading was applied in increasing steps andwas reduced in stages at certain stress levels and then in-creased again. The duration for each stage of loading wasprescribed before starting the test. Most tests had a durationof 24 h and some lasted long enough to measure the creep

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Mixing ratioClay

(<0.002 mm; %)Silt

(0.002 < size < 0.063 mm; %)Sand

(0.063 < size < 1.18 mm; %)

C1: 25% HKMD and 75% silica sand 6.0 14.0 80.0C2: 50% HKMD and 50% silica sand 10.0 30.5 59.5C3: 75% HKMD and 25% silica sand 20.0 42.8 37.2C4: 100% HKMD and 0% silica sand 27.5 58.4 14.1

Table 2. Clay, silt, and sand content of dry mass mixing ratios C1–C4.

Fig. 1. Grain-size distribution curves for the four different mixing ratios C1–C4.

Fig. 2. Measured data and best-fit lines for clay content versus silt content (Silt), clay + silt content (CSilt), and water content (w).



behaviour. The duration of some stages of loading was up to33 days to measure the coefficient of secondary consolidationmore accurately. Results from the oedometer tests are pre-sented and discussed here.

The main oedometer test results of vertical strain versusthe logarithm of time for ratios C1, C2, C3, and C4 are pre-

sented in Figs. 5, 6, 7, and 8, respectively. Measured dataand best-fit lines of vertical strain versus the logarithm ofstress for C4 are presented in Fig. 9. The compression indexCc, unloading–reloading (or swelling) indexCr, coefficientof secondary consolidationCα, and coefficient of consolida-tion cv have been determined using the test data in Figs. 5–8.

© 1999 NRC Canada


Fig. 3. Measured data and best-fit lines for clay content versus liquid limitwL, plasticity indexIP, and plastic limitwP.

Fig. 4. IP versus clay content: (a) comparison with various clays, and (b) comparison with HKMD-2 (natural Hong Kong marinedeposits). The slope of the regression line or the activity value is given in parentheses.



The correlations of these parameters with the plasticity in-dex IP (%) (wL(%) for cv) are shown in Figs. 10a and 11.The values ofCr andCα in Fig. 10a are multiplied by 10 toplot them in the same figure clearly.

The correlations in Fig. 10a are as follows:

[7] Cc = 0.0138IP + 0.00732

[8] Cr = 0.00219IP – 0.0104

[9] Cα = 0.000369IP – 0.00055

where the plasticity indexIP is in percent (%). Values ofR2

are indicated in Fig. 10a. The correlations in eqs. [7], [8],and [9] are very close to those reported by Nakase et al.(1988), that is,Cc = 0.0104IP + 0.046, Cr = 0.00194IP –0.00892, andCα = 0.00033IP + 0.00168, for both Kawasakiclay (mixture series) and reconstituted natural marine clay.The relationship in Fig. 10a betweenCr and IP for HKMD-1shows slight curvature. The straight line fitting has beenused by others, for example, Nakase et al. (1988), and ineq. [7] is considered to be an approximate curve fitting forHKMD-1.

Figure 10b shows the test data and best-fit line for the re-lationship betweenCc and IP for HKMD-2. The test data arevery scattered andR2 has a value of only 0.25. TheCc value

for HKMD-2 (natural soil) is generally larger than that forHKMD-1 (remoulded soil) for the same value ofIP. This isconsistent with the findings for other soils (Mitchell 1993).

Some researchers have correlated the compression indexCc with liquid limit wL (e.g., Djoenaidi 1985). The correla-tion betweenCc and wL can be derived using eqs. [4], [5],and [7], without the need for further regression. Fromeq. [4], the clay contentC = (wL – 13.5)/1.7, and fromeq. [5] IP = 1.26C = 0.741(wL – 13.5). Substituting intoeq. [7], the correlation betweenCc and wL is

[10] Cc = 0.0102wL – 0.131

Figure 10c shows a comparison of measured data and val-ues calculated using eq. [10]. The calculated values are ingood agreement with the measured data. Using the same

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Fig. 5. Vertical strain versus the logarithm of time for ratio C1(25% HKMD and 75% sand): (a) loading, (b) unloading, and(c) reloading.




method and eqs. [1]–[6], the parametersCc, Cr, Cα, andCvcan be related towP or C (clay content).

Koutsoftas et al. (1987) reported oedometer test results forundisturbed upper marine clay (mud), upper alluvial crust(clay), and lower marine clay at the Chek Lap Kok site ofthe new international airport in Hong Kong. The upper ma-rine clay (mud) was a typical natural Hong Kong marine de-posit and was similar to HKMD-1. Koutsoftas et al. reportedthe following values for the upper marine clay (mud):(1) compression index CR =Cc/(1 + eo) = 0.10–0.25 (whereeo is the initial void ratio), (2) unloading–reloading compres-sion index RR =Cr/(1 + eo) = 0.015–0.04, (3) coefficient ofsecondary consolidationCα = 1.8 ± 0.5% (1.3–2.3), and(4) coefficient of consolidationcv = 1.3 ± 0.5 m2/year(0.8–1.8).

The liquid limit wL of the upper marine clay (mud) was inthe range 52–108%, much higher than thewL values forHKMD-1. The wL values for HKMD-1 were 47.2 and 60%(the largest) for mixing ratios C3 and C4, respectively. Theoedometer values for HKMD-1 with mixing ratios C3 andC4 are as follows: (1) compression index CR =Cc /(1 + eo) =0.17 and 0.18, (2) unloading–reloading compression indexRR = Cr /(1 + eo) = 0.020 and 0.027, (3) coefficient of sec-ondary consolidationCα = 0.94 and 1.22%, and (4) coeffi-cient of consolidationcv = 0.81 and 0.73 m2/year.

The wL values, 47.2 and 60%, for HKMD-1 were in thelower bound range of those for the upper marine clay (i.e.,52–108%). Since CR, RR, andCα increase with an increasein wL, we compare the values of CR, RR, andCα for

© 1999 NRC Canada






HKMD-1 with those forwL near the lower bound of the up-per marine clay. With this explanation, it is found that, bycomparison, the values of CR, RR, andCα for HKMD-1 areclose to the corresponding values of the upper marine clay.Thecv values for HKMD-1 are slightly smaller than those ofthe upper marine clay.

The relationship between the coefficient of consolidationcv andwL for all four mixing ratios (C1, C2, C3, and C4) isshown in Fig. 11. The relationship does not fall on a straightline. Koutsoftas et al. (1987) reported the correlation be-tweencv andwL for the upper marine clay (mud), upper al-luvial crust (clay), and lower marine clay at the Chek LapKok site. Figure 11 shows the upper bound and lower bound(broken lines) for the upper marine clay extended based onthe data in Koutsoftas et al. Thecv versuswL curve forHKMD-1 is below the lower bound of the natural HKMDreported by Koutsoftas et al., which is consistent with thefinding that thecv of remoulded soil is, in general, smallerthan that of undisturbed soils (NAVFAC 1982; Koutsoftas etal. 1987; Mitchell 1993). Another reason for the lowercvvalues is that shells and larger particles in HKMD-1 were re-moved, therefore the composition of HKMD-1 was not thesame as that of the upper marine clay, which included shellsand coarse particles. Shells and coarse particles might havemade the upper marine clay more permeable than HKMD-1.

The ratios of Cr to Cc and Cα to Cc on average forHKMD-1 are 0.114 and 0.026, respectively. The ratios onaverage for the upper marine clay areCr /Cc = 0.157 andCα/Cc = 0.022 (Koutsoftas et al. 1987). Mesri andGodlewski (1977) summarized the range ofCα/Cc values fora number of clays published in the literature and found thatthey range from 0.025 to 0.075 for inorganic clays and siltsand 0.03 to 0.085 for organic clays, silts, and peat. Nakase etal. (1988) reportedCα /Cc = 0.032 almost constant forIP =10–60% andC r /Cc = 0.144 on average for both Kawasakiclay (mixture series) and reconstituted natural marine clay.By comparison, the values ofCr /Cc = 0.114 andCα/Cc =0.026 for HKMD-1 are close to those reported by Koutsoftaset al. (1987) and Nakase et al. The average value ofCα/Cc =0.026 for HKMD-1 is near the lower bound of the range ofvalues 0.025–0.075 reported by Mesri and Godlewski (1977)for inorganic clays. TheCα/Cc value for HKMD-1 is nearthe lower bound because HKMD-1 is not all clay but has asand content of from 14.1% (C4) to 80% (C1). TheCα/Ccvalue normally decreases with an increase in sand content.

Triaxial test results, correlations, anddiscussion

Four multistaged consolidated undrained traixial (CU)tests were carried out on HKMD-1 with mixing ratios C1,C2, C3, and C4. A specimen with mixing ratio C1 was satu-rated with a back pressure of 100 kPa and consolidated at aneffective confining stressσ3 = 100 kPa. After consolidationwas completed, the specimen was compressed in the axialdirection (with axial stressσ1) to an axial strain of 5–6% (inthis range of strain, a limit deviator stress,ql = σ1 – σ3, couldbe identified). The specimen was then reconsolidated at aneffective confining stressσ3 = 200 kPa. After completing theconsolidation, the specimen was sheared to an additional ax-ial strain of 5–6%. The specimen was then reconsolidated

again to an effective confining stress ofσ3 = 400 kPa. Thespecimen was then sheared to about 7.5–12% of additionalaxial strain. Figure 12 shows CU test results for deviatorstress versus axial strain and pore-water pressure versus ax-ial strain at three different confining pressures of 100, 200,and 400 kPa for mixing ratio C4.

Both strength parameters and Young’s modulus were de-rived from the results of multistaged CU triaxial tests. Theeffective friction angleφ′ was calculated using the deviatorstressq at large axial strain (7.5–12%). All specimens wereinitially normally consolidated with effective cohesionc′ ofzero. Figure 13a showsφ′ versus percent clay content forHKMD-1 and φ′ at large strain (approximately at criticalstate) of a sand–bentonite mixture versus percent clay con-tent as reported by Lupini et al. (1981). It is seen fromFig. 13a that φ′ decreases with an increase in clay content.The trend of decrease for HKMD-1 is similar to that of thesand–bentonite mixture reported by Lupini et al.

Figure 13b shows the relationship betweenE50 and bothclay content and effective confining pressure (σ3 = 100, 200,and 400 kPa), whereE50 is defined as a secant Young’smodulus at 50% of the limit of deviator stressql. E50 is cal-culated as the slope of the line drawn from the origin of thecurve ofq versusε1 (axial strain) to the point withq equal to50% of limit deviator stressql. Figure 13b shows thatE50decreases with an increase in clay content but increases withan increase in confining pressure. Both friction angleφ′ andYoung’s modulusE50 can be related to the plasticity indexIP, plastic limit wP, or liquid limit wL using the samemethod as used in eq. [10].

Remarks

The correlations in eqs. [7]–[10] reflect the effects of thecompositional factors of soils. Both compositional factorsand environmental factors affect the engineering propertiesand behaviour of soils (Mitchell 1993). Compositional fac-tors include type of minerals, amount of each mineral, parti-cle shapes and size distribution, type of adsorbed cation, and

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Fig. 9. Vertical strain versus the logarithm of stress with loading,unloading, and reloading for mixing ratio C4.



pore-water composition (Mitchell 1993). Environmentalfactors include water content, density, confining pressure(pre-consolidation pressure), temperature, soil fabric andavailability of water (Mitchell 1993), and cementation. Lessdisturbed soils retain most of the environmental factors(soils are always disturbed to a certain extent). Remoulded(reconstituted) soils lose some of the environmental factorssuch as fabric and density. The HKMD-1 was a reconsti-

tuted soil. Therefore, some environmental factors were notconsidered such as fabric, cementation, preconsolidationpressure in in situ conditions. The composition of HKMD-1may not be the same as that of in situ HKMD. Therefore, theproperties and behaviour of HKMD-1 may not be the sameas those of in situ HKMD.

The study using HKMD-1 with a consistent compositioncan help us to understand the effects of compositional

© 1999 NRC Canada


Fig. 10. (a) Measured data and fitted lines ofIP versusCc, Cr, andCα for HKMD-1. (b) Measured data and fitted line ofIP versusCc

for HKMD-2. (c) Comparison of measured data and the calculated line ofwL versusCc for HKMD-1.



factors on the fundamental properties and behaviour of HKMD.As discussed in previous sections, the oedometer test valuesfor HKMD-1 are close to those for natural HKMD.

There have been different ways to correlate soil parameterswith basic properties and composition (e.g., clay content) ofsoils. Most researchers related behavioural parameters to

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Fig. 11. Liquid limit wL versus the logarithm ofcv for test data on HKMD-1 and lower and upper bounds for upper marine clay (afterKoutsoftas et al. 1987).

Fig. 12. Consolidated undrained triaxial test results of deviator stress and pore-water pressure versus axial strain for mixing ratio C4and confining stressσ3 of 100, 200, and 400 kPa.



index properties such asIP andwL (e.g., Lupini et al. 1981;Nakase et al. 1988; and others). Koutsoftas et al. (1987),however, related the compression ratio CR and the coeffi-cient of secondary consolidationCα to the natural water con-tent w of soil. This kind of correlation is questionable. Thewater content is related to the void ratioe by the relationshipe = wGs, whereGs is the specific gravity, for fully saturatedsoils, ande is related to vertical effective pressureσz′. It iscommonly known that CR (or Cc) andCα are approximatelyconstant for different values ofσz′ (thereforee or w) in nor-mally consolidated conditions. Thus, CR (or Cc) andCα willbe independent of water contentw, at least approximately,for soils in a normally consolidated state.

Correlations may be useful for preliminary estimation ofsoil parameters. Limitations of correlations must be pointedout. The correlations obtained for HKMD-1 are best suitedfor the range of composition (orIP ranges) tested. Any ex-tension beyond the range must be verified. For example, ineq. [8] whenIP is less than 4.75%, the swelling indexCr isnegative and this is apparently incorrect. If the compositionof HKMD differs from that of HKMD-1, then the correla-tions for HKMD-1 must be used carefully. Some environ-mental factors such as fabric and cementation are notconsidered in those correlations of HKMD-1. For a more ac-curate estimation of soil parameters, less disturbed (or undis-turbed) soil samples must be taken from the site and used intests to derive the required parameters. In situ tests may beused to determine some of the soil parameters.

Summary and conclusions

In this paper, the main results on composition, index prop-erties, and behaviour of oedometer consolidation and triaxialcompression of Hong Kong marine deposits with differentclay contents are presented, analyzed, and discussed. Corre-lations on composition, index properties, and behaviouralparameters are obtained and presented. It is suggested thatbasic correlations should be used to find the correlation withany other parameter which is of interest to users. Limitationsof those correlations have been pointed out.

Based on the work presented in this paper, the followingconclusions are drawn:

(1) The composition and index properties of HKMD-1 aretypical but may differ slightly from those of natural HKMD.

(2) The consolidation parameters are typical forremoulded HKMD and are close to those of natural HKMD(undisturbed or slightly disturbed).

(3) The correlations of consolidation parametersCc, Cr,and Cα with IP (or cv with wL) for HKMD-1 are similar tothose for other soils published in the literature.

(4) The friction angleφ′ of HKMD-1 decreases with an in-crease inIP in a trend similar to that for the soil reported byLupini et al. (1981). Young’s modulusE50 increases with anincrease in effective confining pressureσ3 but decreases withan increase in clay content (orIP).

(5) The correlations are best suited to the range of compo-sition or index values tested. Any extension beyond thisrange must be checked and verified.

(6) The approximate correlation of consolidation parame-ters with other index properties or composition can be ob-tained mathematically using the basic relationships ineqs. [1]–[6]. It has been pointed out that the physical mean-ing of the correlation must be carefully examined.

(7) Not all compositional factors and environmental fac-tors are considered in the correlations for HKMD-1. For amore accurate estimation of the behavioural parameters, asoil sample from the site should be used that has undergonelittle or no disturbance.

Acknowledgements

Financial support from a RGC grant (PolyU 5065/97E) ofthe University Grants Committee of the Hong Kong Govern-ment and from the Hong Kong Polytechnic University is ac-knowledged.

References

British Standards Institution. 1990. Methods of test for soils forcivil engineering purposes. British Standard 1377. British Stan-dards Institution, London.

Djoenaidi, W.J. 1985. A compendium of soil properties and corre-lations. M.Eng. thesis, University of Sydney, Sydney, Australia.

Koutsoftas, D.C., Foott, R., and Handfelt, L.D. 1987. Geotechnicalinvestigations offshore Hong Kong. Journal of Geotechnical En-gineering, ASCE,113(2): 87–105.

Lupini, J.F., Skinner, A.E., and Vaughan, P.R. 1981. The drainedresidual strength of cohesive soils. Géotechnique,31(2): 181–213.

Mesri, G., and Godlewski, P.M. 1977. Time- and stress-compress-ibility interrelationship. Journal of the Geotechnical EngineeringDivision, ASCE,103(GT5): 417–430.

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Fig. 13. (a) Effective friction angleφ′ versus clay content forHKMD-1 and a sand–bentonite mixture (data from Lupini et al.1981). (b) Young’s modulusE50 versus clay content for HKMD-1.



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Mitchell, J.K. 1993. Fundamentals of soil behaviour. 2nd ed. JohnWiley & Sons, Inc., New York.

Muir Wood, D. 1990. Soil behaviour and critical state soil mechan-ics. Cambridge University Press, Cambridge, U.K.

Nakase, A., Kamei, T., and Kusakabe, O. 1988. Constitutive pa-rameters estimated by plasticity index. Journal of GeotechnicalEngineering, ASCE,114(GT7): 844–858.

NAVFAC. 1982. Soil mechanics, DM 7.1. Naval Facilities Engi-neering Command, Alexandria, Va.

Skempton, A.W. 1953. The colloidal activity of clay.In Proceed-ings of the 3rd International Conference on Soil Mechanics andFoundation Engineering, Zurich, Vol. 1, pp. 57–61.



properties and behaviour of hong kong marine deposits with different clay contents

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