Micromechanical modelling for effect of inherent anisotropy on cyclic behaviour of sand

Sci. China Technol. Sci.

Dano

et al. 2011

Self Cite

112

International audienceA particle breakage has a significant impact on the mechanical behavior of granular materials. In this paper, we present an elasto-plastic model with two yield surfaces to which the influence of particle breakage has been introduced. The main feature of this model is to incorporate the change in the critical state line (CSL) consequent to the grain breakage induced by isotropic and deviatoric stresses during loading. For this purpose we propose a breakage function which connects the evolution of the CSL to the energy consumed. Results from earlier studies on drained and undrained compression and extension triaxial tests were used to calibrate and validate the model. Comparison between earlier results and our simulations indicates that the model can reproduce with good accuracy the mechanical behavior of crushable granular materials and predict the evolution of the grain size distribution during loading

“…, where η = q/ p′ ; H is the hardening variable defined by a hyperbolic function in the H-ε d p plane, similar to the one proposed by Yin et al [24] ,…”

Section: Shear Sliding Criterionmentioning

confidence: 97%

A constitutive model for granular materials considering grain breakage

Sci. China Technol. Sci.

Dano

et al. 2011

Self Cite

112

“…Because of the discrepancy in fitting experimental tests, a material constant D is often introduced in dilatancy equations for sand, such as that proposed by Jefferies (1993), Gajo and Muir Wood (1999), Yin et al (2010a), and Yin and Chang (2012) …”

Section: Modification Of the Stress Dilatancy Equationmentioning

confidence: 99%

Stress Dilatancy of Natural Soft Clay under an Undrained Creep Condition

Wang

2015

Int. J. Geomech.

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The stress-dilatancy relationship is a key point to capture the evolution of both strains and excess pore pressure during an undrained creep of natural soft clay. This paper focuses on investigating the stress dilatancy of natural soft clay during an undrained creep. Undrained triaxial creep tests are performed on K 0 -consolidated and isotropically consolidated samples of a typical Chinese soft marine clay with different stress levels. A unique stress-dilatancy curve is obtained from all test results. Several typical stress-dilatancy relations for soils are discussed, comparing them with experimental results. A common modification method for the stress dilatancy of sand is adopted and discussed for clay. All comparisons demonstrate that modified dilatancy equations can describe the stress-dilatancy relationship during an undrained creep. The modified dilatancy equation with the inclination of a potential surface seems to better describe the whole trend, and is suitable for natural soft clay.

“…The micromechanical‐based models attract more attention and perform well in simulations (Yin et al . ). Each of them has its advantages and disadvantages in applications.…”

Section: Introductionmentioning

confidence: 97%

Selection of sand models and identification of parameters using an enhanced genetic algorithm

Jin

Num Anal Meth Geomechanics

Shen

et al. 2015

Self Cite

127

Summary Numerous constitutive models of granular soils have been developed during the last few decades. As a consequence, how to select an appropriate model with the necessary features based on conventional tests and with an easy way of identifying parameters for geotechnical applications has become a major issue. This paper aims to discuss the selection of sand models and parameters identification by using genetic algorithm. A real‐coded genetic algorithm is enhanced for the optimization with high efficiency. Models with gradually varying features (elastic‐perfectly plastic modelling, nonlinear stress–strain hardening, critical state concept and two‐surface concept) are selected from numerous sand models as examples for optimization. Conventional triaxial tests on Hostun sand are selected as the objectives in the optimization. Four key points are then discussed in turn: (i) which features are necessary to be accounted for in constitutive modelling of sand; (ii) which type of tests (drained and/or undrained) should be selected for an optimal identification of parameters; (iii) what is the minimum number of tests that should be selected for parameter identification; and (iv) what is the suitable and least strain level of objective tests to obtain reliable and reasonable parameters. Finally, a useful guide, based on all comparisons, is provided at the end of the discussion. Copyright © 2015 John Wiley & Sons, Ltd.