Volumetric behavior of unsaturated soils

Abstract

An elastoplastic framework to account for the volumetric behavior of unsaturated soils is proposed herein. The proposed equation is based on the effective stress principle and results in a unifying framework for the volumetric behavior for both saturated and unsaturated soils. The results of the proposed equation are compared with experimental results published by different researchers. These comparisons show that the equation is adequate to account for wetting–drying and net stress loading–unloading paths. In addition, the collapse upon wetting phenomenon can be simulated and the critical state for unsaturated soils coincides with the proposed volumetric framework. This analysis confirms that the effective stress principle can be applied to the volumetric behavior of unsaturated soils.

Hydro-mechanical response of collapsible soils under different infiltration events

“…Adopting the same framework as that of Barcelona Basic Model, several authors provide a characterization of the stress state in terms of net stress and suction; see, for example, , , and references therein. Alternatively, models have been developed on the basis on the concept of Bishop's effective stress and suction; see, for a review, and , or some recent contribution as , and . In particular, the modified Cam‐Clay model adopted in this work has been extended to unsaturated conditions following this last approach; see and .…”

Modeling the soil–water retention curves while the soil is deforming

“…The elastoplastic framework used to model the volumetric behavior of unsaturated soils is based on the effective stress concept [17]. This framework uses the effective mean stress (p ) defined by Bishop's equation p = p + χs,…”

On Unsaturated Soil Mechanics – Personal Views on Current Research

“…This behaviour cannot be properly explained by constitutive models such as BBM [33], therefore new extended models were proposed [47]- [49]. However, it was shown by the authors of this paper in 1995 [48], that the phenomenon of collapse could be explained if an appropriate 'deviatoric' or 'combined volumetric-deviatoric' hardening model is adopted within the framework proposed in Section 5 (ii). It should be pointed out again that the hydro-mechanical properties of unsaturated soils are strongly dependent on the microstructure of saturation and its evolution.…”

“…Assume that T = 65 × 10 -6 kN/m, ξ = 1, ρ v = 3.8 × 10 -4 mm. Since the air phase is considered here to be interconnected, the initial air pressure is zero, p a = 0, which leads to where K and G are bulk and shear moduli respectively, η f and η c are slopes of failure and zero dilatancy lines in q-p′ space and α is material parameter appearing in hardening function [48]. Figure 6 shows q versus ε q = 2(ε 1 -ε 3 )/3 plot for initial value of S r = 0.4.…”