A modified creep index and its application to viscoplastic modelling of soft clays

Zhu, Qi-Yin; Wu, Zhiqing; Li, Yanling; Xu, Changjie; Wang, Jianhua; Xia, Xiaohe

doi:10.1631/jzus.a1300331

Cited by 12 publications

(5 citation statements)

References 22 publications

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“…Figure 12 shows a tendency for an increasing C ae with the increasing LL, PI and SOM. These results were consistent with those of Bjerrum et al [8], Nakase et al [53], Yin [70], Jesmani et al [32] and Zhu et al [82]. Present study and the results of the above-mentioned researchers showed that plasticity and organic matter to a great extent influence the timedependent behaviour of fine-grained soils.…”

Section: Coefficient Of Secondary Compression Change Index Msupporting

confidence: 93%

“…To overcome the limitation of the logarithmic function, some nonlinear creep formulations have been proposed. Yin et al [73] formulated a nonlinear expression of C ae with volumetric strain and time that considers the influence of the bulk density q and e. Wu et al [68] also considered consecutively decreasing C ae related to the q. Zhu et al [82] and Yin et al [74] demonstrated a decreasing C ae as q increased. They introduced a modified C ae * , defined in a double-logarithmic plane.…”

Section: Introductionmentioning

confidence: 99%

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An experimental investigation of the influence of plasticity on creep degradation rate

Olek

2021

Acta Geotech.

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Intrinsic soil properties, such as the Atterberg limits, are essential factors influencing the mechanical behaviour of the fine-grained soils. In this study, a series of long-term multiple-stage loading oedometer tests were performed on alluvial organic soils to investigate the creep behaviour. The plasticity ratios ranged from 0.4 to 0.63. The smaller value of the plasticity ratio Rp indicated higher soil plasticity. The results showed that the coefficient of secondary compression Cαe of alluvial organic soils was stress- and strain-rate-dependent. The coefficient of secondary compression change index m was derived using a double-logarithmic approach for a creep degradation and was related to the plasticity and clay percentage to fines. Based on the results, it was found that high plasticity soils exhibit slow creep degradation rate during one-dimensional straining under normally consolidated state. The results show that the higher soil plasticity expressed by the plasticity index, plasticity ratio and clay percentage to fines, smaller the coefficient of secondary compression change index. Moreover, the correlations among a soil plasticity properties and creep parameters for the alluvial soils have also been proposed.

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Section: Coefficient Of Secondary Compression Change Index Msupporting

confidence: 93%

Section: Introductionmentioning

confidence: 99%

An experimental investigation of the influence of plasticity on creep degradation rate

Olek

2021

Acta Geotech.

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“…At the same time, the reduction of the σ′ p0 and σ′ pi0 are the pre-consolidated pressures for the natural sample and reconstituted sample, respectively; K nc is the coefficient of lateral pressure for normally consolidated clay apparent secondary compression coefficient through inter-particle debonding can be reproduced. The model's predictive ability has been validated for various soft sensitive clays (Yin et al, 2010a;2011a;Karstunen and Yin, 2010;Zhu et al, 2014). Therefore, this model was adopted in this study.…”

Section: Adopted and Enhanced Constitutive Modelmentioning

confidence: 99%

An efficient parameter identification procedure for soft sensitive clays

Liang

Jin

Shen

et al. 2016

JZUS-A

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Abstract:The creep and destructuration characteristics of soft clay are always coupled under loading, making it difficult for engineers to determine these related parameters. This paper proposes a simple and efficient optimization procedure to identify both creep and destructuration parameters based on low cost experiments. For this purpose, a simplex algorithm (SA) with random samplings is adopted in the optimization. Conventional undrained triaxial tests are performed on Wenzhou clay. The newly developed creep model accounting for the destructuration is enhanced by anisotropy of elasticity and adopted to simulate tests. The optimal parameters are validated first by experimental measurements, and then by simulating other tests on the same clay. Finally, the proposed procedure is successfully applied to soft Shanghai clay. The results demonstrate that the proposed optimization procedure is efficient and reliable in identifying creep and destructuration related parameters.

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“…Clayey soils usually display significant creep deformation in the form of prolonged settlements of foundations, tilts of geotechnical structures, or slippage of slopes and embankments, for instance (i.e. Mesri & Choi, 1985;Tavenas & Leroueil, 1981;O'Reilly et al, 1991;Rowe & Hinchberger, 1998;Mitchell & Soga, 2005;Karstunen & Yin, 2010;Yin et al, 2015Yin et al, , 2017Zhu et al 2014). Generally, the mechanical behavior of clay is determined by the microstructural state of the material and its evolution.…”

Section: Introductionmentioning

confidence: 99%

Effect of Stress Level on the Microstructural Evolution of Clay under Creep

et al. 2022

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Creep in clay can significantly affect long-term deformation evolution and therefore impact the safety of geotechnical structures. To improve our understanding of the mechanism of creep, we have examined the microstructural evolution of a kaolin clay sample submitted to creep under three-dimensional or axisymmetric loading conditions, focusing on the effect of the stress level. This experimental study identifies the local mechanisms in normally and over consolidated remolded clay samples during creep under triaxial conditions at different stress levels. The results show that the macro and micro behaviors of the kaolin clay are predominantly governed by the contractancy/dilatancy mechanism activated along stress paths at constant p'. Within the contractancy domain, the SEM observations showed that the microstructural anisotropy increased with the augmentation of the stress level. The microstructural evolution during creep can be attributed to changing patterns in particle reorientation and pore geometry, resulting in plastic strain hardening/softening as well as in viscous fluid flow. The evolution of the clay microstructure therefore depends on both the stress level and the OCR. The differences in the orientation pattern under creep appeared to be enhanced according to the contractancy/dilatancy mechanism. The dilative specimens exhibited particle orientations which were relatively random. The flattening/expansion of the micropores under creep corresponded to the contraction/dilation mechanism at the specimen scale. An attempt based on the analysis of the SEM photographs was made to evaluate the evolution of anisotropy during the different loading phases.

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A modified creep index and its application to viscoplastic modelling of soft clays

Cited by 12 publications

References 22 publications

An experimental investigation of the influence of plasticity on creep degradation rate

An experimental investigation of the influence of plasticity on creep degradation rate

An efficient parameter identification procedure for soft sensitive clays

Effect of Stress Level on the Microstructural Evolution of Clay under Creep

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