Finite-discrete element modelling of rock slope stability in jointed rock masses using discrete fracture networks and ubiquitous joint model

ABSTRACT: Modelling the strength of jointed rocks requires consideration of the joint weakness relative to the rock matrix strength. In the finite-discrete element method (FDEM), strength is typically modelled through cohesive elements embedded between finite elements, which can be specifically oriented and calibrated to behave as weak joints. However, large-scale models with complex geometries, such as slope stability models, may require a large number of finite elements to capture the joints as cohesive elements. Therefore, a ubiquitous joint Mohr-Coulomb elasto-plastic constitutive model was implemented within the finite elements to simulate the response of a heavily jointed slope with cross-jointing. Compressive strength test models were used to validate this new implementation. For comparison, an alternative FDEM approach using isotropic Mohr-Coulomb elasto-plasticity for the matrix strength and anisotropic cohesive elements for the joint strength was tested. This approach was more sensitive to the mesh geometry and would require additional refinement to achieve a comparable response. The ubiquitous joint constitutive model implemented into FDEM also showed similar performance compared to a finite element model with similar geometry. The ubiquitous joint model implemented for FDEM provides an alternative weak joint representation that does not need explicit meshing that the cohesive element approach would otherwise require.