An effective stress approach for hydro-mechanical coupling of unsaturated soils

Abstract

The simulation of the mechanical and hydraulic behaviour of soils is one of the most important tasks in soil mechanics. It is inaccurate to consider that the behaviour of saturated and unsaturated soils as if their governing laws were utterly different, this last condition is not sufficient to do so. However, unlike the laws governing the behaviour of saturated soils, those used to describe the behaviour of unsaturated soils lack the simplicity and predictability associated to the complexity of the phenomena that occur within these porous media. This is why it is important to establish a unified soil mechanics theory to reconcile saturated and unsaturated soil mechanics. In the present work, we describe a simple analytical equation to obtain effective stresses for any type of soil. The equation is coupled to an elastoplastic constitutive model which is capable to reproduce the stress-strain relationship of soil taking into account the hydro-dynamic coupling.

Elastoplastic Coupled Model of Saturated Soil Consolidation under Effective Stress

“…These forces are determined by the vector field on the trajectory T; ( , ) gives the force per unit volume exerted by the surroundings on . Thus, (55) gives that part of the force caused by the environment on .…”

“…During the last three decades, constitutive models have been developed based on elastoplastic theory, as it allows the modeling of the nonlinear and hysteretic behavior of soil [55,56]. These aimed to carry out hydromechanical coupling, such as in the Basic Barcelona Model (BBM) and the Drucker-Prager Model (DPM), which were defined with respect to mean and deviatoric stress [57]; while Arroyo and Rojas [34] developed a fully coupled hydromechanical model under effective stresses that accurately predicted the transition between saturated and unsaturated states as well as between elastic and elastoplastic states, but with limitations in the prediction of volumetric strains.…”