Projection Methods for Soil Structure Interaction Numerical Simulations with Non-Matching Meshes

Abstract

Nowadays, it is of great interest to perform numerical simulations of soil structure interaction (SSI) since they are applied to a wide range of engineering problems. These include the construction of reliable earthquake resistant structures in seismic active areas, or to increase the comfort of buildings by decoupling them from surrounding emissions like vibrations induced by traffic. To analyse SSI problems taking unbounded soil domains into account a numerical implementation of a coupled finite element method (FEM) and scaled boundary finite element method (SBFEM) approach is used. This approach fulfills the Sommerfeld's radiation condition. The FEM is used to discretise the so called near-field, i.e. the structure and its surrounding soil, while the infinite half-space or so called far-field is realised by the SBFEM. Both methods are coupled at a common interface, where specific information like nodal velocities and forces required to be exchanged. Since computation of far-field solution demands more effort than for the near-field, the size of the elements in the far-field discretization is bigger than in the near-field. Therefore, a projection algorithm is needed to exchange information (i.e. nodal forces and velocities) between the non-matching meshes. Two projection methods borrowed from the fluid structure interaction framework are used in this work, namely a Nearest Neighbour projected method and a conservative one based on weigthed residual formulation plus Gauss numerical quadrature. They are wrapped in a library which is called during the coupled FEM-SBFEM solution process. Two SSI test problems are considered to validate the implementation, as well as to evaluate the savings in memory and computation time. Matching mesh results are taken as reference.