Potential for fracture shear slip due to thermo-mechanical loading of a deep geological repository for nuclear waste
Opening of fractures induced by shear dilation can be a significant source of fracture permeability change. In this study, the zones of fracture shear slip were examined through threedimensional thermo-mechanical analysis of a nuclear waste repository model using the finite element method. Stress evolutions in selected locations revealed the main mechanisms of the generation of thermal stress important for fracture shear slip. The implications are that fractures of different orientations are vulnerable to shear slip at various locations throughout the lifespan of a geological repository. Stress paths obtained from the thermo-mechanial analysis were used as stress boundary conditions in order to investigate the effect of stress change on permeability. DFN-DEM (Discrete Fracture Network - Discrete Element Method) analysis showed that normal deformation dominated fracture closure/opening in four models and shear dilation dominated in the remaining two models. In the latter two models, modest permeability increases up to a factor of four were observed during thermal loading history. Permeability changes caused by shear dilation were not recovered after cooling of the repository, which was in contrast with the recovery of permeability changes for models in which normal fracture closure dominates.
K.-B.Min O.Stephansson
Department of Energy Resources Engineering, Seoul National University, South Korea GeoForschungsZentrum, Potsdam, Germany
国际会议
香港
英文
1-6
2009-05-19（万方平台首次上网日期，不代表论文的发表时间）