Modelling 3D desiccation cracking in clayey soils using a size-dependent SPH computational approach

Modelling desiccation cracking in soils is a challenging process that requires a robust computational approach capable of describing soils undergoing thermo-hydro-mechanical coupling processes induced complex cracking patterns. To facilitate this process, this paper presents a computational approach that combines the mesh-free smoothed particle hydrodynamics (SPH) method and a size-dependent constitutive model with an embedded cohesive fracture process zone to simulate shrinkage induced soil cracking. The proposed method describes the fracture geometry through a set of SPH particles that carries their own cohesive fracture process zone and freely moves without being confined to a grid system. As it is a particle-based approach, there are no preferred orientations for cracks to develop, and hence the direction of crack propagation is controlled by local stress conditions and material properties only. This unique feature of SPH in conjunction with the size-dependent constitutive model enables the proposed method to naturally capture the crack propagation in soils while eliminating issues associated with spatial-dependent solutions. The proposed computational framework is verified against analytical solutions followed by the validation against experiment data of direct shear tests, flexural tests and shrinkage-induced soil cracking tests. Very satisfactory agreements with experimental data demonstrate that the proposed computational method is a promising approach for further incorporating multi-physical processes that can provide insights into the crack development processes in clayey soils.