Models to Predict Compressibility and Permeability of Reconstituted Clays

Sun, Liqiang; Jin, Lu; Guo, Wei; Yan, Shuwang; Jia, Tianqiang

doi:10.1520/gtj20150145

Cited by 12 publications

(6 citation statements)

References 27 publications

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“…However, the variable ∆e 1 /C k = C c log((p' 0 + ∆p')/p' 0 )/C k , in which the compression index (C c ) should be replaced by the swelling index (C r ) for overconsolidated (OC) soil, is unchanged only when the soil has a constant compressibility and a constant slope of the e-log(k) curve, i.e., constant values of C c (or C r ) and C k . For soils with incomplete self-weight consolidation, e.g., dredged clayey slurry with extremely high moisture, the application of the proposed method should be reconsidered, as this type of soil normally has a nonlinear compressibility and permeability relationship (Morris 2003;Sun et al 2016). Therefore, the proposed method may not be directly used if the soil transforms from the OC state to the normal consolidation (NC) state within the applied incremental loading.…”

Section: Discussionmentioning

confidence: 99%

A novel semianalytical method for evaluating the average consolidation degree of a two-soil-layer deposit

Zhou

2021

Bull Eng Geol Environ

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Two-soil-layer deposits are sometimes encountered in engineering practice. To accurately assess the consolidation condition of a two-soil-layer deposit, it is necessary to fairly estimate both the settlement-and excess pore water pressure-defined average degrees of consolidation of the system. In this study, the consolidation behavior of a two-soil-layer deposit is first experimentally and numerically investigated, and the results show that the average degree of consolidation defined by the excess pore water pressure (ADCu) is generally less than that defined by the settlement (ADCs), and the difference can be distinct when a softer and less permeable layer is located adjacent to the drainage boundary. A new index (β) denoting the permeability reduction in the soil layer adjacent to the drainage boundary is introduced to indirectly quantify the difference between the ADCu and ADCs. The β value is quantitatively correlated to the permeability, compressibility, soil layer thickness, and loading condition of a two-soil-layer deposit, and a simple method with general application procedures is finally proposed to evaluate the ADCu of a two-soil-layer deposit by modifying a theory that was originally developed to predict the ADCs. Application of the proposed method to another two consolidation tests of two-soil-layer deposits demonstrates that the method has satisfactory validity. KeywordsConsolidation • Two-soil-layer deposit • Permeability • Laboratory test • Finite element analysis Notations C c Compression index C k Rate of permeability change with void ratio c' Effective cohesion c v Coefficient of vertical consolidation c v1 Coefficient of vertical consolidation of soil layer 1 c v2 Coefficient of vertical consolidation of soil layer 2 e Void ratio e 0 Initial void ratio * Fang Xu

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Section: Discussionmentioning

confidence: 99%

A novel semianalytical method for evaluating the average consolidation degree of a two-soil-layer deposit

Zhou

2021

Bull Eng Geol Environ

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“…The average undrained shear strength of the soils in subzones B1 and B3 were only 2.3 and 2.5 kPa, respectively. The 1-D consolidation and permeability tests are conducted by Sun et al 36 and obtained nonlinear and time-independent compressibility and permeability as,…”

Section: Application To the Case Studymentioning

confidence: 99%

“…The average undrained shear strength of the soils in subzones B1 and B3 were only 2.3 and 2.5 kPa, respectively. The 1‐D consolidation and permeability tests are conducted by Sun et al 36 . and obtained nonlinear and time‐independent compressibility and permeability as,

\begin{equation} \frac{e}{{{e}_{\mathrm{L}}}} = 1.9 - 1.4 {\left( {{1} - \sigma {^{\prime}}^{ - 0.434}} \right)}^2\end{equation}

\begin{equation}{\mathrm{log}}\ k = 4.7{\left( {{1} - {\mathrm{exp}}\left( { - 1.3\frac{e}{{{e}_{\mathrm{L}}}}} \right)} \right)}^2 - 9.65\end{equation}

where e is the void ratio, k is the coefficient of the permeability, σ ′ is the effective stress of soil mass, e L is the void ratio at the liquid limit state, and e L = G s w L , where G s is the specific gravity, and w L is liquid limit.…”

Section: Verification Of the Proposed Theorymentioning

confidence: 99%

Large‐strain consolidation of vacuum preloading combined with partially penetrating prefabricated vertical drains

Guo,

Zhou,

Sun

et al. 2024

Num Anal Meth Geomechanics

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A system of vacuum preloading combined with partially penetrating prefabricated vertical drains (PP‐PVDs) is an effective solution for promoting the consolidation of the dredged marine clay. However, a significant and traditionally challenging‐to‐predict amount of deformation or settlement occurs. Therefore, it is necessary to introduce a three‐dimensional large‐strain consolidation model to consider the length of the vertical drain to determine the consolidation time and degree of consolidation (DoC), and associated settlement. The predictions using the proposed analytical model provide fair agreements with the field data and those in the literature. Parametric studies reveal that to achieve a 90% DoC within 100 days in soft soil, the optimal penetration depth for PP‐PVDs would be 0.7 times the depth of the soil layer. With the increase of DoC, the ratio of excess pore water pressure to applied vacuum pressure (u/P) in the whole soil layer moves toward 1.0. With the increase of PVD penetration ratio (H1/H), more DoC is required to dissipate the excess pore water pressure in the top improved soil layer.

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“…e modified void ratio can be obtained by substituting equation (9) into (6): Note: e 0 is the initial conventional void ratio; e 0 ′ is the initial modified void ratio; k is the permeability coefficient. Advances in Civil Engineering e compression index is an important characteristic of soil compression, and it can be calculated by the following equation according to Terzaghi's consolidation theory:…”

Section: Compression Index Considering Lbwmentioning

confidence: 99%

“…e void ratio that greatly affects the compression process of soil is a key parameter in the determination of C c [6,7]. Petersen et al [8] found that the C c value of clay was smaller than that of silt at the same initial void ratio.…”

Section: Introductionmentioning

confidence: 99%

Influence of Loosely Bound Water on Compressibility of Compacted Fine‐Grained Soils

Zhang

Kumar

et al. 2020

Advances in Civil Engineering

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

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Models to Predict Compressibility and Permeability of Reconstituted Clays

Cited by 12 publications

References 27 publications

A novel semianalytical method for evaluating the average consolidation degree of a two-soil-layer deposit

A novel semianalytical method for evaluating the average consolidation degree of a two-soil-layer deposit

Large‐strain consolidation of vacuum preloading combined with partially penetrating prefabricated vertical drains

Influence of Loosely Bound Water on Compressibility of Compacted Fine‐Grained Soils

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