An alternative BE–FE formulation for a raft resting on a finite soil layer

This work presents a numerical tool for simulating the interaction of a raft with the soil, which can be a half space or a finite layer supported by a rigid base. The soil is modelled using the boundary element method (BEM) with Kelvin fundamental solutions. Infinite boundary elements (IBEs) are employed for the far field simulation, allowing computational cost reduction without compromising the accuracy. The IBE formulation is based on a triangular boundary element with linear shape functions instead of the commonly used quadrilateral IBEs. Displacements are restrained at the rigid base, when it exists. The raft is modeled with the finite element method (FEM) using a triangular element, which is obtained by combining bending effects and membrane effects. For the FEM–BEM coupling, the BEM tractions are considered as nodal reactions in the FEM formulation. The coupling is established using equilibrium and compatibility conditions, obtaining a system of equations that represents the complete problem.