Numerical Study of Desiccation Cracking In Clayey Soil: A New FEM-MPM Coupling Method.

Abstract

Desiccation cracking is a critical phenomenon soliciting the soil hydro-mechanical behavior, and significantly affects the performance of soil in geotechnical engineering. For this reason, an increasing interest toward studying and simulating the soil crack propagation, after a severe exposure to dry conditions (induced by desiccation), has been noticed during the recent years. However, major gaps remain in the previously developed models to properly provide a realistic prediction of the cracks pattern scheme especially when using the classical Finite Element Method (FEM), widely used in the geotechnical application. In this study, owing to the limitation of this method in re-meshing and dealing with large deformation, the authors were prompted to couple FEM with a mesh-free method: The Material Point Method (MPM) to overcome the individual drawbacks of each method. The dominant influencing factors on soil desiccation cracking have been assessed through a desiccation test performed in climatic chamber and using a digital image processing technique (image analysis) for a quantitative description of the studied sample. A model that relates porosity with suction and tensile strength was used to study the effect of the shrinkage phenomena in desiccation term, and to simulate the crack propagation in a thin clayey soil layer using the Code_Bright software. Consequently, a clear and connected crack pattern was observed, the problem of mesh dependency was clearly overcome proving the validity of the approach and providing a further insight into the behavior of clayey soil exposed to desiccation factors.