Coupled hydro-mechanical analysis of expansive soils: Parametric identification and calibration

A methodology for identifying and calibrating the material parameters for a coupled hydro-mechanical problem is presented in this paper. For validation purpose, a laboratory-based water infiltration test was numerically simulated using finite element method (FEM). The test was conducted using a self-designed column-type experimental device, which mimicked the wetting process of a candidate backfill material in a nuclear waste repository. The real-time measurements of key state variables (e.g. water content, relative humidity, temperature, and total stresses) were performed with the monitoring sensors along the height of cylindrical soil sample. For numerical simulation, the modified Barcelona Basic Model (BBM) along with soil-water retention model for compacted bentonite was used. It shows that the identified model parameters successfully captured the moisture migration process under an applied hydraulic gradient in a bentonite-based compacted soil sample. A comparison between the measured and predicted values of total stresses both in axial and lateral directions along with other state variables revealed that heterogeneous moisture content was distributed along the hydration-path, resulting in non-uniform stress-deformation characteristics of soil.