An adaptive mesh refinement algorithm based on element subdivision with application to geomaterials

The implementation of Adaptive Mesh Refinement (AMR) within the geotechnical software package PLAXIS 2D is described in this paper. A recovery-based algorithm is used which aims to reduce the discretisation error by refining the mesh during the solution process. The error is estimated with a Zienkiewicz-Zhu-type error estimator but based on the incremental deviatoric strain instead of stress. The deviatoric strain field is compared with an improved field calculated by superconvergent patch recovery. Once elements with large errors have been detected, mesh refinement takes place. A combination of regular subdivision and longest-edge bisection is employed. Mapping history variables from the old mesh to the new mesh is accomplished by using the recovered solutions and the shape functions. The AMR algorithm is demonstrated for a biaxial compression test