Hypoplastic model with fabric change effect and semifluidized state for post‐liquefaction cyclic behavior of sand

Abstract

This paper presented the formulation of a novel hypoplastic model for sand considering both the cyclic mobility and large accumulative shear deformation in the post‐liquefaction stage. Based on experimental observations and existing modeling response, two constitutive ingredients were incorporated into the hypoplastic model to improve its prediction accuracy. First, the fabric change effect was considered, enabling a satisfactory simulation of effective stress reduction under undrained cyclic loading. The second component was the introduction of the semifluidized state concept to reflect the modulus degradation and deviatoric strain development of sand at low‐stress state. The capability of the proposed model is demonstrated by the comparisons between the model responses and experimental results of the cyclic behavior of sand under different test conditions. Remarkably, the liquefaction phenomenon and increasing deviatoric strain amplitude during the post‐liquefaction stage were reproduced well by the model.

A hypoplastic model for hydrate‐bearing sand considering hydrate saturation and grain breakage

“…The hypoplastic model based on nonlinear tensor functions without the concept of yield surface/plastic potential has been widely adopted for studying the mechanical responses of geomaterials. Numerous researches demonstrate hypoplastic capabilities of describing mechanical responses of geomaterials, such as granular sand, [50][51][52][53][54][55][56] clay, [57][58][59][60] hydrate-bearing sand. 16,17,61 Especially, the concept of critical states in soil mechanics was incorporated into the hypoplastic framework, 62,63 leading to the capabilities of predicting strain hardening and softening behavior.…”