Fully coupled hydromechanical model for compacted soils

Abstract

To accomplish a proper conception and further modeling of the mechanical behavior of soils, observations at the micro and macro scales need to be merged. The authors believe that the link between scales can be achieved using the effective stress concept. In this paper, we present a model that quantifies the air and water volumes contained within the pores of a solid when their pore pressure is varied. The macroscopic consequences of this are expressed in terms of a single stress that is used to formulate a simple elastoplastic constitutive model to predict volume strains and shear strength of soils.

Elastoplastic Coupled Model of Saturated Soil Consolidation under Effective Stress

“…indicating that the associated variations in (34) apply the "Principle of Virtual Work" in Equation ( 30):…”

“…On the other hand, the consolidation of saturated soils is governed by the effective stress, as it relates to the soil's stiffness property [33] The effective stress combines the applied stress and water pore pressure, enabling the conversion of a multiphase porous medium to an equivalent single-phase continuous one [34,35]. Likewise, [36] established that effective stress can also describe the consolidation and SWRC behavior of unsaturated soils.…”

“…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. Due to this, there are no analytical solutions for hydromechanical coupling in unsaturated soils; therefore, it is necessary to employ numerical techniques such as the finite element (FE) method [6,7,13,38] in order to simplify the nonlinear behavior of the unsaturated consolidation theory, assuming that water permeability and air transmittance are constant [12].…”