The Influence of Fractures in the Wall-Block Model Domain in the EDZ using an EPCA Code

摘要

Detailed analyses were conducted to study the coupled thermal, hydrological, mechanical and chemical (THMC) processes in a wall-block model over a 100,000 year time period after emplacement of heat releasing waste by using an EPCA (Elasto-Plastic Cellular Automaton) code, which has been successfully used to simulate the failure process of heterogeneous rocks by the authors. This study is a part (Task B) of the international DECOVALEX-THMC project. The Wall-Block model domain represents the situation close to the surface of the excavation disturbed zone (EDZ) around nuclear waste emplacement drifts in fractured crystalline rocks. Though it does not permit analysis of the extent of the EDZ, it is used for detailed analysis of the THMC processes within the EDZ. Four different wall-block models with various degree of macro fracturing in a porous rock matrix were included, and the study focused on elastic and elasto-plastic analyses to investigate the evolution of stress and deformations, as well as failure and permeability evolution in the EDZ. Results showed that existing fractures lead to further local stress concentrations which significantly impact the failure processes and permeability evolution.