Influence of Destructuration of Soft Clay on Time-Dependent Settlements: Comparison of Some Elastic Viscoplastic Models

Nash, Dft; Brown, Matthew

doi:10.1061/(asce)gm.1943-5622.0000281

Cited by 19 publications

(11 citation statements)

References 25 publications

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“…Mesri and Godlewski , Choi , Feng , Mesri and Vardhanabhuti , and Mesri , supporting Hypothesis A, believed that soil is compressed for two interrelated reasons: ( i ) the change of effective stress, ( ii ) the change of time. Meanwhile, Bjerrum , Stolle et al , Vermeer and Neher , Nash and Ryde , Yin et al , Leroueil , Leoni et al , Karim et al , Nash and Brown used Hypothesis B to consider that the creep occurs during the consolidation stage. Navarro and Alonso regarded the ‘secondary compression’ of clays as the rate of local water transfer process.…”

Section: Introductionmentioning

confidence: 99%

A new simplified Hypothesis B method for calculating consolidation settlements of double soil layers exhibiting creep

Feng

Yin

2016

Num Anal Meth Geomechanics

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Summary This paper presents a new simplified method, based on Hypothesis B, for calculating the consolidation settlements of double soil layers exhibiting creep. In the new simplified Hypothesis B method, different stress–strain states including over‐consolidation and normal consolidation states can be considered with the help of the ‘equivalent time’ concept. Zhu and Yin method and US Navy method are adopted to calculate the average degree of consolidation for a double soil layer profile. This new simplified Hypothesis B method is then used to calculate the consolidation settlements of double soil layers, which have two different total thicknesses of soil layer (4 m and 8 m) and three different OCR values (Over‐Consolidation Ratio, OCR = 1, 1.5 and 2). The accuracy and verification of this new simplified method are examined by comparing the calculated results with simulation results from a fully coupled finite element (FE) program using a soft soil creep model. Four cases of double layer soil profiles are analyzed. Hypothesis A method with US Navy method for the average degree of consolidation has also been used to for calculating consolidation settlements of the same cases. For Case I(4m) and Case III(8m), it is found that curves of the new simplified Hypothesis B method using both Zhu and Yin method and US Navy method are very close to the results from FE simulations with the relative errors within 8.5%. For Case II(4m) and Case IV(8m), it is found that curves of the new simplified Hypothesis B method using Zhu and Yin method agree better with results from FE simulations with the relative errors within 11.7% than curves of the new simplified Hypothesis B method adopting US Navy method with the relative error up to 36.1%. Curves of Hypothesis A method adopting US Navy method have the relative error up to 55.0% among all four cases. In overall, the new simplified Hypothesis B method is suitable for calculation of consolidation settlements of double soil layers exhibiting creep, in which, Zhu and Yin method is recommended to obtain the average degree of consolidation. Copyright © 2016 John Wiley & Sons, Ltd.

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Section: Introductionmentioning

confidence: 99%

A new simplified Hypothesis B method for calculating consolidation settlements of double soil layers exhibiting creep

Feng

Yin

2016

Num Anal Meth Geomechanics

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“…However, as shown by Nash and Brown (2015) and by Grimstad et al (2015), there are some underlying problems in using the time(log) presentation, as time is not an objective measure. In reality, the linear line in a time resistance R versus time plot does not necessarily intercept with origin.…”

Section: Stress-strain Behaviour Observed In the Oedometer Testsmentioning

confidence: 99%

Determination of Creep Properties of Clays from VRS Oedometer Tests

Länsivaara

2019

Geotech Geol Eng

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The determination of creep properties still relies almost entirely on the incrementally loaded oedometer test introduced about 100 years ago. Although the simplicity of the test assures a robust evaluation of soil parameters, it also introduces some shortcomings like discontinuity of the evaluated parameters and the long duration of the test. In this study, the performance of the variable rate of strain (VRS) oedometer test for determination of creep properties of a sensitive soft clay is studied. The results from a comprehensive test series of VRS oedometer tests on a soft sensitive clay is presented. Three different setups for the strain rate variation were used, and each test was repeated thrice. The tests showed good consistency and yielded equal creep parameters compared to values from traditional incrementally loaded (IL) oedometer tests. The tests further verified that it is possible to describe the complex stress dependency of creep parameters with just one additional parameter to the primary deformation parameters. Compared to the IL tests, the VRS tests offers a faster determination and continuous creep properties for a wide range of stress.

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“…The finite element (FE) program (Plaxis 2015 version) using SSC model is used to analyze the same soil layers because the SSC model is widely supported by researchers studying creep . In addition, it is found that simulation results using this FE program with 1‐D EVP model are the same as the results from Plaxis software with SSC model . The FE simulations are regarded as the exact coupled results.…”

Section: Cases Of Hong Kong Marine Deposits and Its Finite Element Simentioning

confidence: 99%

A new simplified Hypothesis B method for calculating the consolidation settlement of ground improved by vertical drains

Feng

Yin

2017

Num Anal Meth Geomechanics

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Vertical drains are widely used in soft ground improvements to accelerate the consolidation process. This paper develops a new simplified Hypothesis B method for calculating the consolidation settlement of a soil layer improved by vertical drains under the instant and ramp loadings. As a comparison, the traditional Hypothesis A method is also used to calculate the settlement.Then, a fully coupled finite element consolidation analysis is utilized to examine and verify this simplified method and Hypothesis A method. For the instant loading, Carrillo-Barron method and Zhu-Yin method are used to obtain the average degree of consolidation for vertical drain system. Typical parameters, such as over-consolidation ratio (OCR), smear zone, and space ratio of vertical drains, are considered. It is found that the calculation results from the new simplified method in this study agree well with finite element simulations, and relative errors are in the range of 0.1% to 12.3%. Comparatively, there are obvious differences between the calculated results from Hypothesis A method and finite element results. Carrillo-Olson method and Zhu-Yin method are utilized to obtain the average degree of consolidation for the vertical drain system to consider the ramp loading. Equivalent time is determined from half of the construction period to calculate the creep compression under the ramp loading. The accuracy of this simplified Hypothesis B method using both Carrillo-Olson method and Zhu-Yin method is acceptable with the relative errors less than 9.4%.

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Influence of Destructuration of Soft Clay on Time-Dependent Settlements: Comparison of Some Elastic Viscoplastic Models

Cited by 19 publications

References 25 publications

A new simplified Hypothesis B method for calculating consolidation settlements of double soil layers exhibiting creep

A new simplified Hypothesis B method for calculating consolidation settlements of double soil layers exhibiting creep

Determination of Creep Properties of Clays from VRS Oedometer Tests

A new simplified Hypothesis B method for calculating the consolidation settlement of ground improved by vertical drains

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