Numerical Modeling of the Oedometrical Behavior of Collapsible Loess

Loess covers more than 10% of continental lands all around the world. The macrostructure of these soils collapses when water content increases, greatly decreasing soil volume. Two mechanisms are responsible for the collapse: the expansion of clay bridges and/or the dissolution of precipitated salts that join coarse particles forming an open microstructure. Double oedometer tests are widely used in geotechnical practice to estimate relative collapse or collapse potential. The main goal of this work is to evaluate the stress–strain behavior under zero-lateral displacement conditions of undisturbed loess samples tested at natural moisture content and inundated with water. Numerical models are developed by using the Comsol Multiphysics Software. Two elastoplastic models were implemented: the modified Cam Clay model (MCC) and the extended Barcelona Basic model (EBB). Numerical models were calibrated with experimental data by using a least square technique. The results show the capacity and limitations of the MCC and EBB models to represent the mechanical behavior of collapsible loess before and after water flooding. This work demonstrates the potential of the EBB model to predict the mechanical behavior of loess, using a limited amount of data obtained from uncontrolled- suction oedometer tests.