Abstract:The results of benchmark test(BMT) from the study on coupled thermo-hydro-mechanical(THM) processes in the excavation damage zone(EDZ) around nuclear waste repository in fractured rocks are presented. This is an important part of international cooperation project DECOVALEX-THMC TASK B. The results focus on the influence of fractures on the evolution of EDZ over 1×106 years after disposal of high-level radioactive waste. The numerical study is conducted for two model domains,homogeneous and heterogeneous near-field models,surrounding a repository. The heterogeneous near-field model domain includes a realistic fracture network derived by detailed fracture mappings at the Äspö hard rock laboratory,Sweden. In this study,fractures are represented discretely,but softening and weakening effects of fractures intersecting a continuum element are simulated using continuum elements by a reduction in modulus. Using this approach for fracture representation,numerical analyses are conducted using elastoplastic cellular automata(EPCA) code. Elastic and elastoplastic analyses are performed to study the evolution of stress and deformations in EDZ adopting time-dependent thermal,mechanical and fluid pressure boundary conditions. The analysis shows a strong impact of fractures on the distribution of rock stress and deformation as well as the failure process. The numerical results are consistent with those obtained by other international research teams,indicating the validity of EPCA code. The results also indicate that the EPCA code can be used to perform next step analysis of DECOVALEX-THMC project.