Optimized mesh generation for two-dimensional finite element analysis of underground excavations in rocks masses traversed by joints

Deformation and distribution of stresses around underground excavations in jointed rock masses are influenced by yield and slip along joints. Since stresses are often computed using non-linear finite element analysis, and considering the excavation sequence, a number of what-if scenarios are performed, requiring considerable time. Often an accurate solution is only required in a limited part of a larger model. While mesh optimization can reduce the number of elements and analysis effort, the previously published optimization method by the author only considered the effect of excavations at a region of interest. The method was based on a cost function to prioritize the automatic removal of geometric detail from the boundary representation of the domain and the ensuing mesh. The inclusion of the effects of joints and excavation interaction in a stress analysis model, as part of the mesh optimization process, is developed in this paper with an application to a representative stress analysis case. The resulting optimized meshes can represent the displacement and stresses at the region of interest with considerable accuracy while capturing the yield along joints in the rock mass.