An Associative and Non-Associative Anisotropic Bounding Surface Model for Clay

Abstract

An anisotropic elastoplastic bounding surface model with non-associative flow rule is developed for simulating the mechanical behavior of different types of clays. The non-associative flow rule allows for the simulation of not only strain-hardening but also strain-softening response. The theoretical framework of the model is given, followed by the verification of the model as applied to the experimental results of a strain-hardening Kaolin tested under different undrained stress paths. The undrained behavior of Boston Blue clay, which exhibits a strain-softening behavior, is also simulated. It is shown that the non-associative nature of the model gives more accurate results than those of the same model employing an associative flow rule, especially for normally consolidated Kaolin specimens. The results show that the model is also capable of simulating the strain-softening behavior of Boston blue clay with reasonable accuracy.

Finite Element Simulation of Deep Excavation Failures

“…These soils were characterized by an enhanced anisotropic bounding surface model with associative [17] and non-associative [11,12] flow rules. This model was implemented into the PLAXIS computer program [26] for the analyses.…”

“…Thus, three versions of bounding surface model were used. The formulation and predictive capabilities of the enhanced anisotropic bounding surface model with associative and non-associative flow rules have been previously documented [10,12,17].…”

“…The sites are modeled and simulated using the small strain finite element method. The soft cohesive soils found at these sites are characterized by an enhanced anisotropic bounding surface model with associative [17] and nonassociative [11,12] flow rules that is implemented into the PLAXIS computer program [26] as part of this study. The results of the simulations are critically assessed with relation to field observations.…”

Finite Element Simulation of Deep Excavation in Soft Cohesive Soils Using an Enhanced Anisotropic Bounding Surface Model

“…Many simulations, however, were based on relatively simple constitutive models that might not have the capability to realistically describe ground movements due to complex characteristics of soils. For this reason, advanced bounding surface models (Ling et al, 2002;Jiang and Ling, 2010;Jiang et al, 2012) have recently been used in finite element excavation analyses. This paper describes the use of enhanced anisotropic bounding surface models with associative (Ling et al, 2002) and non-associative flow rules (Jiang and Ling, 2010;Jiang et al, 2012), in conjunction with the PLAXIS computer program for simulating ground movements associated with deep excavations.…”

“…For this reason, advanced bounding surface models (Ling et al, 2002;Jiang and Ling, 2010;Jiang et al, 2012) have recently been used in finite element excavation analyses. This paper describes the use of enhanced anisotropic bounding surface models with associative (Ling et al, 2002) and non-associative flow rules (Jiang and Ling, 2010;Jiang et al, 2012), in conjunction with the PLAXIS computer program for simulating ground movements associated with deep excavations. The proper implementation of the models into PLAXIS was first validated against undrained isotropic and anisotropic triaxial test results under compression and extension shearing modes for various cohesive soils.…”