Extension of a basic hypoplastic model for overconsolidated clays

Abstract

This paper presents a hypoplastic constitutive model for overconsolidated clays. The model is developed based on a basic model proposed recently for sand. New density and stiffness factors are introduced to account for history dependence. The model is capable of predicting a desirable asymptotic state boundary surface for overconsolidated clays. Validation with experimental results shows this model can properly describe the main features of overconsolidated clays.

A simple hypoplastic model for overconsolidated clays

“…Unlike some existing hypoplastic models for clays [16,21,24,42], the unloading index, i.e., j à , is not used in the proposed model. In fact, the unloading index facilitates the predictions of unloading behavior of one loading cycle, while it has little contribution in capturing the cyclic behavior with a large number of loading cycles [24].…”

Validation of a simple hypoplastic constitutive model for overconsolidated clays

“…in which G i ¼ 1:5pf s denotes the initial shear stiffness at an isotropic stress state. As assumed in previous works [10,11,16,39], the ratio v i ¼ K i =G i can be considered as a material constant, which has a similar physical meaning to Poisson's ratio. As a consequence, a simple formulation for the multiplier f v is obtained as follows:…”

“…These models open a new avenue for modeling of OC clays. Based on these models, some extensions for OC clays were made by Shi et al [33] and Wang et al [39]. Whereas the aforementioned models provide a fairly decent prediction for OC clays, their formulations are rather intricate and further extensions based on these models will inevitably increase the complexity of the model and the number of the parameters.…”

On mechanical behaviour of clastic soils: numerical simulations and constitutive modelling

“…(Tang et al , 2015;Wang et al , 2018) Therefore, a more advanced model incorporating both the critical state and overconsolidation is required to serve this purpose. As an alternative to the prevailing plasticity theory, hypoplastic models have gained much attention in recent years (Fuentes et al , 2019;Mašín , 2012Mašín , , 2014Wang et al , 2018c,b;Wang & Wu , 2020a;Wang et al , 2020c). Unlike elastoplastic models, hypoplastic models are able to describe the critical state and overconsolidation behaviour without using the yield surface, plastic potential, decomposition into elastic and plastic parts, and a loading criterion (Wu et al, 2017).…”