1. bookVolume 41 (2019): Issue 3 (September 2019)
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Effective Friction Angle Of Deltaic Soils In The Vistula Marshlands

Published Online: 30 Sep 2019
Page range: 143 - 150
Received: 28 Jan 2019
Accepted: 29 May 2019
Journal Details
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09 Nov 2012
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This article presents the results of laboratory tests on soft, normally consolidated soils from the Vistula Marshlands. Samples of high-plasticity organic soils (muds) taken from 3.2–4.0 m and 9.5–10.0 m depth, as well as peat deposit at 14.0 m, are analysed. Presented case study confirms the applicability of the Norwegian Institute of Technology (NTH) method based on Cone Penetration Tests (CPTU) and allows for a conservative estimation of effective friction angle for muds. The plastification angle equal to 14.5° for organic silt, applied in the modified NTH method, fits well the triaxial test (TX) results. Moreover, the dilative-contractive behaviour according to the CPTU soil classification based on the Robertson’s proposal from 2016 corresponds well with volumetric changes observed in the consolidated drained triaxial compression tests. The internal friction angles of the Vistula Marshlands’ muds and peats are lower in comparison with the database of similar soft soils.

Keywords

Introduction
Aim of research

This research is focused on effective angle of internal friction and compares the results for the Vistula Marshlands muds and peats with similar soft soils. Effective shear strength parameters of the deltaic soils near Gdańsk are measured in drained and undrained triaxial compression tests and estimated with the Norwegian Institute of Technology (NTH) method using the Cone Penetration Tests (CPTU) sounding. The observed dilative-contractive soil behaviour is discussed taking into account the CPTU classification chart proposed by Robertson (2016). The aim of the research presented herein is to verify the applicability of the NTH method for the estimation of effective friction angle of soft soils in the Vistula Marshlands.

Testing site description

The testing field is located near the Jazowa village, in the Vistula Marshlands, Northern Poland. Intensive geotechnical investigations related with the construction of S-7 expressway were carried out in the studied area. Fifteen CPTU soundings, performed at every 2 m spacing, proved the regularity of the subsoil. Soil layers, distinguished according to the Unified Soil Classification System (USCS), are presented in Figure 1 along with the results of the CPTU soundings. The soil profile at the site contains the following layers:

Figure 1

Soil profile and CPTU sounding results.

0.00–0.70 m– silty sand (working platform)

0.70–1.80 m – low-plasticity silt

1.80–2.70 m – organic silty clay (mud) of high-plasticity

2.70–4.05 m – mixture of organic silty clay (mud) and peat

4.00–7.05 m – silty sand (loose to medium dense)

7.05–12.15 m - organic silt (mud) of high plasticity intersected with thin sand layer

12.15–14.45 m – peat with organic silt inclusions

below 14.45 m – well-graded sand

In this paper, the study is focused on the samples taken from 1.8–4.0 m (organic silty clay), 7.80–12.15 m (organic silt), and 12.15–14.45 m (peat). Selected index properties of these soils are presented in Table 1.

Selected index properties of the Vistula Marshlands soft soils.

Soil layerSampling depthwcγGsPLLLIPLOI
[m][%][kN/m3][g/cm3][%][%][%][%]
Organic silty clay (OH)3.2÷4.0554.4 ÷75.914.22 ÷14.522.54 ÷2.6140.7 ÷55.390.4 ÷119.049.7 ÷63.711.4 ÷16.2
Organic silt (OH)9.5÷10.545.4 ÷57.315.6÷16.62.54 ÷2.67228.3 ÷38.053.7÷57.115.7 ÷27.554.2÷7.1
Peat (Pt)13.0÷14..0179.210.51.57N/AN/AN/A87.2
Testing Methodology
Triaxial tests

The consolidated undrained (CU) triaxial compression test (ASTM D4767, 2011) was conducted on muds (organic silty clay and organic silt) taken from 3.2–4.0 m and 9.5–10.0 m and on peat from approximately 14 m. The specimens were sheared at the rate of 0.011 mm/min. The three CU tests on mud samples were made at different level of cell pressure. However, only two samples of peat have been sheared due to limited amount of material. The consolidated drained (CD) triaxial compression test (ASTM D7181, 2011) was conducted only on organic silt samples, sheared at the rate of 0.002 mm/min. Standard triaxial device was used. The angle of internal friction has been determined using the stress ratio M in the p’-q (p’ = effective mean stress; q = deviatoric stress) plane defined as:

M=6sinϕ3sinϕ$$M=\frac{6\cdot \sin {\phi }'}{3-\sin {\phi }'}$$

where: ϕ’ = effective angle of internal friction.

CPTU soundings

The CPTU estimation of internal friction angle using the NHT method was calculated with the following equations (Mayne, 2007):

ϕ=29.5Bq0.1210.256+0.336Bq+logQt$${\phi }'=29.5\cdot {{B}_{q}}^{0.121}\left( 0.256+0.336\cdot {{B}_{q}}+\log {{Q}_{t}} \right)$$

where:

Qt=qtσv0σv0$${{Q}_{t}}=\frac{{{q}_{t}}-{{\sigma }_{v0}}}{{{{{\sigma }'}}_{v0}}}$$Bq=u2u0qtσv0$${{B}_{q}}=\frac{{{u}_{2}}-{{u}_{0}}}{{{q}_{t}}-{{\sigma }_{v0}}}$$

qt = corrected cone resistance, σv0 = in-situ vertical total stress, σ’v0 = in-situ vertical effective stress, Qt = normalized cone resistance, Bq = normalized pore-water pressure, u0 = hydrostatic pressure based on the water table level.

The values of effective angle of internal friction based on CPTU results were adjusted with those determined from the triaxial tests using the modified NTH method (Ouyang & Mayne, 2017) with the angle of plastification β being fitting parameter:

ϕ=29.5100.0035βBq0.1210.256+0.336Bq+logQt$${\phi }'=29.5\cdot {{10}^{0.0035\cdot \beta }}\left[ {{B}_{q}}^{0.121}\cdot \left( 0.256+0.336\cdot {{B}_{q}}+\log \,{{Q}_{t}} \right) \right]$$

The modified NTH method can be applied for soils ranging from sands to clays, where the angle of plastification β = (-20°; 20°). The modified NTH method should not be adopted to peats.

The dilative-contractive soil behaviour type parameters required in the Robertson (2016) classification are:

– normalized sleeve friction:

F=fsσv0$$F=\frac{{{f}_{s}}}{{{{{\sigma }'}}_{v0}}}$$

- normalized cone resistance:

Qtn=qtσv0papaσv0n$${{Q}_{tn}}=\left[ \frac{{{q}_{t}}-{{\sigma }_{v0}}}{{{p}_{a}}} \right]\cdot {{\left( \frac{{{p}_{a}}}{{{{{\sigma }'}}_{v0}}} \right)}^{n}}$$

and:

n=0.38Ic+0.05σv0pa0.15$$n=0.38\cdot {{I}_{c}}+0.05\cdot \left( \frac{{{{{\sigma }'}}_{v0}}}{{{p}_{a}}} \right)-0.15$$Ic=3.47logQt2+logFr+1.2220.5$${{I}_{c}}={{\left[ {{\left( 3.47-\log {{Q}_{t}} \right)}^{2}}+{{\left( \log {{F}_{r}}+1.22 \right)}^{2}} \right]}^{0.5}}$$Fr=fs/qtσv0100%$${{F}_{r}}=\left[ \left( {{f}_{s}}/{{q}_{t}}-{{\sigma }_{v0}} \right) \right]\cdot \text{100%}$$

where: fs = sleeve friction, pa = atmospheric reference pressure equal to 100 kPa, n = variable stress exponent; n ≤ 1.0, Ic = soil behaviour type index, Fr = friction ratio.

Results And Interpretation

Frictional strength of soil in terms of effective angle of internal friction ϕ’ depends on soil particles interference and interlocking (Terzaghi et al., 1996). For normally consolidated soils, the critical value of effective angle of internal friction (ϕ’c) is equal to the maximum value (ϕ’max). The determination of ϕ’max in TX tests is related to the choice of failure criterion. There are three standard criterions: (i) maximum deviatoric stress qmax = max(σ13), (ii) maximum obliquity: max(σ13), (iii) max(σ13) or max(σ13) at predefined value of axial strain (usually 15%). The choice of failure criterion for organic soils is not obvious as soft soils, and peats in particular, could exhibit plastic flow phenomenon, see Figure 3. For some soils (mostly peats), the qmax can even increase up to Rankine’s surface. To interpret such behaviour, the procedure adopted after Hendry et al. (2012), and schematically presented in Figure 2, was applied. The plastic flow is usually characterized by almost linear increase of qmax with axial strain (εa). The qmax is assumed as a point of intersection between non-linear and linear part of q-εa plot (see Figure 2). The Authors believe that this interpretation can be satisfactorily applied for non-standard q-εa curves when considerable plastic flow occurs.

Figure 2

Determination of qmax for non-standard q-εa curves. Procedure adopted after Hendry et al. (2012).

Figure 3

The CU tests results for (a) organic silty clay, (b) organic silt and (c) peat.

The results of CU triaxial compression tests are presented in Figure 3 in terms of the plots in q-εa and p’-q planes. Strength mobilization in the organic silty clay progresses slowly (Figure 3a) and the failure is achieved at the axial strain between 6% and 8%. The achieved M = 0.904 corresponds to the effective angle of internal friction of 23.1°.

For organic silt (Figure 3b), the maximum deviatoric stress is reached at the axial strains of 3-4%. The samples exhibit plastic flow phenomenon and the failure point has been adopted after the procedure described above. The assumed stress ratio M = 1.255, which results in the angle of internal friction equal to 31.3°. The results of CU tests on organic silt have been verified by CD triaxial compression tests, see Figure 4. Almost the same failure envelope has been achieved in CD and CU tests. However, large axial strains are required at the failure in CD tests and the response of specimens during shearing is clearly contractive (Figure 4). This observation confirms the CPTU soil classification based on soil behaviour type (SBT) proposed by Robertson (2016) (Figure 5). The organic silt and peat layers are classified as clay-like contractive, while the silty clay layer is mostly dilative.

Figure 4

The results of CD tests on organic silt.

Figure 5

SBTn chart based on Qtn-F (Robertson, 2016).

The angle of internal friction equal to 55.7° was obtained in CU tests for peat taken from 14 m. High value of ϕ’ is typical for fibrous peat (Mesri and Ajlouni, 2007) due to its microstructure (Cheng et al., 2007). The assumed qmax for peats is achieved at approximately 10% of axial strain.

Using CPTU results, the ϕ’ was determined with Equations 2 and 5. Only the results for organic silt and peat layers from 7.80–14.45 m depth could be taken into consideration. In the shallow layers (up to 4.05 m), negative u2 readings were obtained, which results in Bq < 0. The ϕ’ according to the Equation 2 almost perfectly fits the TX value for organic silts. However, the CPTU based ϕ’ underestimates the TX value of ϕ’ for peats.

In organic silt, the angle of plastification equal to 14.5° provides a fitting match between the modified NHT and the TX tests. The effective internal friction angles obtained in the laboratory tests and mean value derived from the fifteen CPTU tests are summarized in Table 2.

Values of effective friction angle of soft soils in Jazowa.

Soil typeType of the test
CUCDCPTU
NHT method (Mayne, 2007)NTH modified method (Ouyang & Mayne, 2017)
Organic silty clay (3.2–4.0 m depth)23.1°23.4° *N/AN/A
Organic silt (9.5–10.0 m depth)31.3°31.0°27.9°±1.231.3°±1.4
Peat (~14.0 m depth)55.7°N/A29.0°±2.4N/A

*Value obtained from lab tests, conducted by an external company, and summarized in geotechnical documentation for the S-7 expressway.

The effective friction angels for soft soil deposits in the Jazowa site are compared with the other soft soils in Table 3. As one can see, the organic soft soil in the Jazowa are characterized by similar frictional parameters as observed for other sites. However, the angles of the internal friction of organic silty clay and organic silt form the lower bound of the reported database.

Effective friction angle of soft soils deposits.

Soilϕ’Reference
CLAYSBothkennar clay34°(Hight et al., 1992)
Osaka bay clay25–40°(Tanaka and Locat, 1999)
Omono clay50–60°(Yasuhara and Takenaka, 1977)
Muck clay52–60°(Tsushima et al., 1977)
Juturnaiba organic clay23–57°(Coutinho and Lacerda, 1989)
Soft organic clay32.0°(Danziger, 2007)
Organic clay30.0°(Larsson et al., 2007)
Organic clay38–46°(Cheng et al., 2007)
Organic clay from Cubzac-les-Ponts28–34°(Shahanguian, 1981)
Various organic clays44–74°(Krieg, 2000)
Alluvial clay31.5°(Sandroni et al., 2015)
Soft alluvial clay36°(Takemura et al., 2006)
Soft alluvial Atchafalaya clay20.2°(Donaghe and Townsend, 1978)
Soft deltaic clay36.0°(Sultan et al., 2004; Dan et al., 2007)
SILTSAlluvial clayey silt28°(Lambson et al., 1993; Powell and Lunne, 2005)
Organic silt38–56°(Cheng et al., 2007)
PEATSwedish clayey gyttja60–90°(Larsson, 1990)
Eemian gyttja29–44°(Pietrzykowski, 2004)
peat63–65°(Cheng et al., 2007)
Middleton peat60°(Ajlouni, 2000)
Ohmiya peat51–55°(Yamaguchi et al., 1985)
Edson peat28.8–50.1°(Hendry et al., 2012)
THISJazowa silty clay23°
STUDYJazowa organic silt31°
Jazowa peat56°
Conclusions

The high values of effective angle of internal friction are obtained for organic silts, organic silty clays and peats. However, the full shear strength is achieved at relatively large strains (εa = 10% in most cases). The angles of internal friction are lower in comparison with database. The ϕ’ according to NTH (Mayne, 2007) almost fits the value of effective friction angle for silty layers, but significantly underestimates the ϕ’ for peats. However, the good estimation of ϕ’ requires reliable measurement of u2 reading, which was not be fulfilled for shallow layers of soft soils in the reported testing site. The presented research shows that the NTH method can be treated as a conservative estimation of effective friction angle for soft soils. In case of organic silt, perfect agreement between the CPTU and the modified NTH method is achieved for the angle of plastification β = 14.5°. The CD triaxial tests on organic silt confirmed the updated Robertson’s (2016) classification as a practical tool for qualitative description of soil behaviour type (SBT).

Figure 1

Soil profile and CPTU sounding results.
Soil profile and CPTU sounding results.

Figure 2

Determination of qmax for non-standard q-εa curves. Procedure adopted after Hendry et al. (2012).
Determination of qmax for non-standard q-εa curves. Procedure adopted after Hendry et al. (2012).

Figure 3

The CU tests results for (a) organic silty clay, (b) organic silt and (c) peat.
The CU tests results for (a) organic silty clay, (b) organic silt and (c) peat.

Figure 4

The results of CD tests on organic silt.
The results of CD tests on organic silt.

Figure 5

SBTn chart based on Qtn-F (Robertson, 2016).
SBTn chart based on Qtn-F (Robertson, 2016).

Effective friction angle of soft soils deposits.

Soilϕ’Reference
CLAYSBothkennar clay34°(Hight et al., 1992)
Osaka bay clay25–40°(Tanaka and Locat, 1999)
Omono clay50–60°(Yasuhara and Takenaka, 1977)
Muck clay52–60°(Tsushima et al., 1977)
Juturnaiba organic clay23–57°(Coutinho and Lacerda, 1989)
Soft organic clay32.0°(Danziger, 2007)
Organic clay30.0°(Larsson et al., 2007)
Organic clay38–46°(Cheng et al., 2007)
Organic clay from Cubzac-les-Ponts28–34°(Shahanguian, 1981)
Various organic clays44–74°(Krieg, 2000)
Alluvial clay31.5°(Sandroni et al., 2015)
Soft alluvial clay36°(Takemura et al., 2006)
Soft alluvial Atchafalaya clay20.2°(Donaghe and Townsend, 1978)
Soft deltaic clay36.0°(Sultan et al., 2004; Dan et al., 2007)
SILTSAlluvial clayey silt28°(Lambson et al., 1993; Powell and Lunne, 2005)
Organic silt38–56°(Cheng et al., 2007)
PEATSwedish clayey gyttja60–90°(Larsson, 1990)
Eemian gyttja29–44°(Pietrzykowski, 2004)
peat63–65°(Cheng et al., 2007)
Middleton peat60°(Ajlouni, 2000)
Ohmiya peat51–55°(Yamaguchi et al., 1985)
Edson peat28.8–50.1°(Hendry et al., 2012)
THISJazowa silty clay23°
STUDYJazowa organic silt31°
Jazowa peat56°

Selected index properties of the Vistula Marshlands soft soils.

Soil layerSampling depthwcγGsPLLLIPLOI
[m][%][kN/m3][g/cm3][%][%][%][%]
Organic silty clay (OH)3.2÷4.0554.4 ÷75.914.22 ÷14.522.54 ÷2.6140.7 ÷55.390.4 ÷119.049.7 ÷63.711.4 ÷16.2
Organic silt (OH)9.5÷10.545.4 ÷57.315.6÷16.62.54 ÷2.67228.3 ÷38.053.7÷57.115.7 ÷27.554.2÷7.1
Peat (Pt)13.0÷14..0179.210.51.57N/AN/AN/A87.2

Values of effective friction angle of soft soils in Jazowa.

Soil typeType of the test
CUCDCPTU
NHT method (Mayne, 2007)NTH modified method (Ouyang & Mayne, 2017)
Organic silty clay (3.2–4.0 m depth)23.1°23.4° *N/AN/A
Organic silt (9.5–10.0 m depth)31.3°31.0°27.9°±1.231.3°±1.4
Peat (~14.0 m depth)55.7°N/A29.0°±2.4N/A

Ajlouni, M.A. 2000. Geotechnical properties of peat and related engineering problems. Ph.D. thesis, Univ. of Illinois at Urbana-Champaign, Urbana, Ill.AjlouniM.A.2000Geotechnical properties of peat and related engineering problemsPh.D. thesisUniv. of Illinois at Urbana-ChampaignUrbana, IllSearch in Google Scholar

ASTM D4767, 2011. Standard Test Method for Consolidated Undrained Triaxial Compression Test for Cohesive Soils. ASTM International, West Conshohocken, PA.ASTM D47672011Standard Test Method for Consolidated Undrained Triaxial Compression Test for Cohesive SoilsASTM InternationalWest Conshohocken, PASearch in Google Scholar

ASTM D7181, 2011. Method for Consolidated Drained Triaxial Compression Test for Soils. ASTM International, West Conshohocken, PA.ASTM D71812011Method for Consolidated Drained Triaxial Compression Test for SoilsASTM InternationalWest Conshohocken, PASearch in Google Scholar

Cheng, X.H., Ngan-Tillard, D.J.M., Den Haan, E.J., 2007. The causes of the high friction angle of Dutch organic soils. Engineering Geology 93, 31–44. https://doi.org/10.1016/j.enggeo.2007.03.009ChengX.H.Ngan-TillardD.J.M.Den HaanE.J.2007The causes of the high friction angle of Dutch organic soilsEngineering Geology933144https://doi.org/10.1016/j.enggeo.2007.03.009Search in Google Scholar

Coutinho, R.Q., Lacerda, W.A., 1989. Strength characteristics of Juturnaiba organic clays. Presented at the 12th International conference on Soil Mechanics and Foundation Engineering, Balkema, Rio de Janeiro, pp. 1731–1734.CoutinhoR.Q.LacerdaW.A.1989Strength characteristics of Juturnaiba organic claysPresented at the 12th International conference on Soil Mechanics and Foundation EngineeringBalkemaRiode Janeiro17311734Search in Google Scholar

Dan, G., Sultan, N., Savoye, B. 2007. The 1979 Nice harbor catastrophe revisited: trigger mechanism inferred from Geotechnical measurements and numerical modelling. Marine Geology, 245(1–4): 40–64. doi:10.1016/j.margeo. 2007.06.011.DanG.SultanN.SavoyeB.2007The 1979 Nice harbor catastrophe revisited: trigger mechanism inferred from Geotechnical measurements and numerical modellingMarine Geology2451–4406410.1016/j.margeo.2007.06.011Open DOISearch in Google Scholar

Danziger, F.A.B. 2007. In-situ testing of soft Brazilian soils. Studia Geotechnica et Mechanica, 29(1–2): 5–22.DanzigerF.A.B.2007In-situ testing of soft Brazilian soilsStudia Geotechnica et Mechanica291–2522Search in Google Scholar

Donaghe, R.T., and Townsend, F.C. 1978. Effects of anisotropic versus isotropic consolidation in consolidated undrained triaxial compression tests of cohesive soils. Geotechnical Testing Journal, 1(4): 173–189. doi:10.1520/GTJ10868J.DonagheR.T.TownsendF.C.1978Effects of anisotropic versus isotropic consolidation in consolidated undrained triaxial compression tests of cohesive soilsGeotechnical Testing Journal1417318910.1520/GTJ10868JOpen DOISearch in Google Scholar

Hendry, M.T., Sharma, J.S., Martin, C.D., Barbour, S.L., 2012. Effect of fibre content and structure on anisotropic elastic stiffness and shear strength of peat. Canadian Geotechnical Journal 49, 403–415. https://doi.org/10.1139/t2012-003HendryM.T.SharmaJ.S.MartinC.D.BarbourS.L.2012Effect of fibre content and structure on anisotropic elastic stiffness and shear strength of peatCanadian Geotechnical Journal49403415https://doi.org/10.1139/t2012-003Search in Google Scholar

Hight, D.W., Bond, A.J., Legge, J.D., 1992. Characterization of the Bothkennar clay: an overview. Geotechnique 42, 303–347.HightD.W.BondA.J.LeggeJ.D.1992Characterization of the Bothkennar clay: an overviewGeotechnique42303347Search in Google Scholar

Krieg, S. 2000. Viskoses Bodenverhalten von Mudden, Seeton und Klei. Veroff. Inst. Boden-u. Felsm., 150.KriegS.2000Viskoses Bodenverhalten von Mudden, Seeton und KleiVeroff. Inst. Boden-u. Felsm150Search in Google Scholar

Lambson, M.D., Clare, D.G., Senner, D.W.F., and Semple, R.M. 1993. Investigation and interpretation of Pentre and Tilbrook Grange soil conditions. In Large scale pile tests in clay. Thomas Telford Publishing, London, pp. 134–196.LambsonM.D.ClareD.G.SennerD.W.F.SempleR.M.1993Investigation and interpretation of Pentre and Tilbrook Grange soil conditionsLarge scale pile tests in clayThomas Telford PublishingLondon134196Search in Google Scholar

Larsson, R., Westerberg, B., Albing, D., Knutsson, S., and Carlsson, E. 2007. Sulfidjord–geoteknisk klassificering och odranerad skjuvhallfasthet. [Sulphide soil—geotechnical classification and undrained shear strength.] Report No. 69, Swedish Geotechnical Institute, SGI, Linkoping. 135 pp.LarssonR.WesterbergB.AlbingD.KnutssonS.CarlssonE.2007Sulfidjord–geoteknisk klassificering och odranerad skjuvhallfasthet[Sulphide soil—geotechnical classification and undrained shear strength.] Report No. 69Swedish Geotechnical InstituteSGI, Linkoping135Search in Google Scholar

Larsson, R., 1990. Behaviour of Organic Clay and Gyttja (No. Report vol.38). Swedish Geotechnical Institute.LarssonR.1990Behaviour of Organic Clay and Gyttja (No. Report vol.38)Swedish Geotechnical InstituteSearch in Google Scholar

Mayne, P.W. 2007. In-situ test calibrations for evaluating soil parameters. In Characterization & Engineering Properties of Natural Soils, Vol. 3, Proc. Singapore 2006, Taylor & Francis Group, London, pp. 1602–1652.MayneP.W.2007In-situ test calibrations for evaluating soil parametersCharacterization & Engineering Properties of Natural SoilsVol. 3, Proc. Singapore 2006Taylor & Francis GroupLondon16021652Search in Google Scholar

Mesri, G., Ajlouni, M., 2007. Engineering properties of fibrous peats. Journal of Geotechnical and Geoenvironmental Engineering 133, 850–866.MesriG.AjlouniM.2007Engineering properties of fibrous peatsJournal of Geotechnical and Geoenvironmental Engineering133850866Search in Google Scholar

Ouyang, Z., & Mayne, P.W. 2017. Effective Friction Angle of Clays and Silts from Piezocone Penetration Tests. Canadian Geotechnical Journal, (ja).OuyangZ.MayneP.W.2017Effective Friction Angle of Clays and Silts from Piezocone Penetration TestsCanadian Geotechnical Journal, (ja)Search in Google Scholar

Pietrzykowski, P., 2004. Charakterystyka geologiczno-inżynierska eemskich gytii i kredy jeziornej z terenu Warszawy, PhD Thesis. ed. University of Warsaw, Warsaw. (in Polish)PietrzykowskiP.2004Charakterystyka geologiczno-inżynierska eemskich gytii i kredy jeziornej z terenu Warszawy, PhD Thesised. University of WarsawWarsaw. (in Polish)Search in Google Scholar

Powell, J.J.M., and Lunne, T. 2005. Use of CPTU data in clays/ fine grained soils. Studia Geotechnica et Mechanica, 27(3–4): 29–66.PowellJ.J.M.LunneT.2005Use of CPTU data in clays/ fine grained soilsStudia Geotechnica et Mechanica273–42966Search in Google Scholar

Robertson, P.K., 2016. Cone penetration test (CPT)-based soil behaviour type (SBT) classification system — an update. Canadian Geotechnical Journal 53, 1910–1927.RobertsonP.K.2016Cone penetration test (CPT)-based soil behaviour type (SBT) classification system — an updateCanadian Geotechnical Journal5319101927Search in Google Scholar

Sandroni, S., Barreto, E., and Leroueil, S. 2015. The Santana Port accident: Could it be a sensitive clay flowslide under the Equator? In Proceedings, GeoQuebec 2015, (68th Canadian Geotechnical Conference), Canadian Geotechnical Society, Ottawa.SandroniS.BarretoE.LeroueilS.2015The Santana Port accident: Could it be a sensitive clay flowslide under the Equator?Proceedings, GeoQuebec 2015, (68th Canadian Geotechnical Conference)Canadian Geotechnical SocietyOttawaSearch in Google Scholar

Shahanguian, S., 1981. Détermination expérimentale des courbes d’état limite de l’argile organique de Cubzac-les-Ponts. Rapport de recherche LCPC, vol. 106.ShahanguianS.1981Détermination expérimentale des courbes d’état limite de l’argile organique de Cubzac-les-PontsRapport de recherche LCPCvol. 106Search in Google Scholar

Sultan, N., Voisset, M., Marsset, B., Marsset, T., Cauquil, E., and Colliat, J.L. 2007. Potential role of compressional structures in generating submarine slope failures in the Niger Delta. Marine Geology, 237(3): 169–190. doi:10.1016/j.margeo.2006.11.002.SultanN.VoissetM.MarssetB.MarssetT.CauquilE.ColliatJ.L.2007Potential role of compressional structures in generating submarine slope failures in the Niger DeltaMarine Geology237316919010.1016/j.margeo.2006.11.002Open DOISearch in Google Scholar

Takemura, J., Watabe, Y., and Tanaka, M. 2006. Characterization of alluvial deposits in Mekong Delta. In Characterisation and Engineering Properties of Natural Soils II, Singapore. Vol. 3, Taylor & Francis Group, London, pp. 1805–1829.TakemuraJ.WatabeY.TanakaM.2006Characterization of alluvial deposits in Mekong DeltaCharacterisation and Engineering Properties of Natural Soils IISingapore. Vol. 3Taylor & Francis GroupLondon18051829Search in Google Scholar

Tanaka, H., Locat, J., 1999. A microstructural investigation of Osaka Bay clay: the impact of microfossils on its mechanical behaviour. Canadian Geotechnical Journal 36, 493–508. https://doi.org/10.1139/t99-009TanakaH.LocatJ.1999A microstructural investigation of Osaka Bay clay: the impact of microfossils on its mechanical behaviourCanadian Geotechnical Journal36493508https://doi.org/10.1139/t99-009Search in Google Scholar

Terzaghi, K., Peck, R.B., Mesri, G., 1996. Soil mechanics in engineering practice, Third Edition. ed. John Wiley & Sons, Inc., New York. https://doi.org/10.1139/cgj-2016-0044TerzaghiK.PeckR.B.MesriG.1996Soil mechanics in engineering practice, Third EditionJohn Wiley & Sons, IncNew Yorkhttps://doi.org/10.1139/cgj-2016-0044Search in Google Scholar

Tsushima, M., Miyakawa, I., and Iwasaki, T., 1977. Some investigations on shear strength of organic soil. Tsuchi-to-Kiso, J. Soil Mech. Found. Eng., 235, 13–18 (in Japanese).TsushimaM.MiyakawaI.IwasakiT.1977Some investigations on shear strength of organic soil. Tsuchi-to-KisoJ. Soil Mech. Found. Eng23513–18(in Japanese)Search in Google Scholar

Yamaguchi, H., Ohira, Y., Kogure, K., Mori, S., 1985. Undrained shear characteristics of normally consolidated peat under triaxial compression and extension conditions. Soils and Foundations 25, 1–18.YamaguchiH.OhiraY.KogureK.MoriS.1985Undrained shear characteristics of normally consolidated peat under triaxial compression and extension conditionsSoils and Foundations25118Search in Google Scholar

Yasuhara, K., & Takenaka, H., 1977. Physical and mechanical properties 2. Engineering Problems of Organic Soils in Japan, Japanese Society of Soil Mechanics and Foundation Engineering, 35–48.YasuharaK.TakenakaH.1977Physical and mechanical properties 2Engineering Problems of Organic Soils in Japan, Japanese Society of Soil Mechanics and Foundation Engineering35–48Search in Google Scholar

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