A fully coupled simple model for unsaturated soils

Abstract

Summary Different phenomena influence the strength and volumetric behavior of unsaturated soils. Among the most important are suction hardening, hydraulic hysteresis, and the influence of volumetric strain on the soil‐water retention curves. Fully coupled hydro‐mechanical models require including all three phenomena in their constitutive relationships. Among these phenomena, suction hardening is the most influencing as it determines the apparent preconsolidation stress, the position of the loading‐collapse yield surface, and the shift of both the isotropic consolidation and the critical state lines. In this paper, a fully coupled hydro mechanical model is presented. It is based on the modified Cam‐Clay model but includes a yield surface with anisotropic hardening that takes account of the shift of the critical state line with suction. For highly overconsolidated materials, the sub‐loading surface concept has been included in order to increase the precision of the model for these materials. The shift of the retention curves produced by volumetric strains is simulated using a hydraulic model based on the grain and current pore size distribution of the soil.

Preconditioners for multiphase poromechanics with strong capillarity

“…It plays a critical role in unsaturated soil mechanics, 19–26 and significantly influences oil recovery predictions 27,28 . The solid deformation is intricately coupled with fluid pressures via nonlinear constitutive laws 29–33 relating the capillary pressure to degree of saturation. In some cases, the constitutive law may even display hysteresis with respect to wetting and drying 34 .…”

Evolution of anisotropy with saturation and its implications for the elastoplastic responses of clay rocks

“…Many hydromechanical models in the unsaturated range have been developed to model porous media subjected to drying and wetting process 46–56 . Some of these models 57–59 extend the modified Cam‐Clay (MCC) model 60,61 or the Barcelona Basic Model (BBM) 62 to account for the mechanical behavior of partially saturated materials.…”

“…Many hydromechanical models in the unsaturated range have been developed to model porous media subjected to drying and wetting process. [46][47][48][49][50][51][52][53][54][55][56] Some of these models [57][58][59] extend the modified Cam-Clay (MCC) model 60,61 or the Barcelona Basic Model (BBM) 62 to account for the mechanical behavior of partially saturated materials. Various authors have further extended these plasticity models to account for the effects of evolving anisotropy.…”