FEM analyses for influences of stress-chemical solution on THM coupling in dual-porosity rock mass  

作　　者：张玉军 杨朝帅 

机构地区：[1]State Key Laboratory of Geomechanics and Geotechnical Engineering,Institute of Rock and Soil Mechanics,The Chinese Academy of Sciences [2]Technical Centre,China Railway Tunnel Group Co.Ltd

出　　处：《Journal of Central South University》2012年第4期1138-1147,共10页中南大学学报（英文版）

基　　金：Project(2010CB732101) supported by the National Basic Research Program of China;Project(51079145) supported by the National Natural Science Foundation of China;Project(2009BAK53B03) supported by the National Key Technology R&D Program of China

摘　　要：The models of stress corrosion, pressure solution and flee-face dissolution/precipitation were introduced. Taking a hypothetical nuclear waste repository in an unsaturated dual-porosity rock mass as the calculation objective, four cases were designed 1） the fracture aperture is a function of stress corrosion, pressure solution and free-face dissolution/precipitation; 2） the fracture aperture changes with stress corrosion and pressure solution; 3） the fracture aperture changes with pressure solution and free-face dissolution/precipitation; 4） the fracture aperture is only a function of pressure solution, and the matrix porosity is also a function of stress in these four cases. Then, the corresponding two-dimensional FEM analyses for the coupled thermo-hydro-mechanical processes were carried out. The results show that the effects of stress corrosion are more prominent than those of pressure solution and free-face dissolution/precipitation, and the fracture aperture and relevant permeability caused by the stress corrosion arc only about 1/5 and 1/1000 of the corresponding values created by the pressure solution and free-face dissolution/precipitation, respectively Under the action of temperature field from released heat, the negative pore and fracture pressures in the computation domain rise continuously, and are inversely proportional to the sealing of fracture aperture. The vector fields of flow velocity of fracture water in the cases with and without considering stress corrosion are obviously different. The differences between the magnitudes and distributions of stresses within the rock mass are very small in all cases.The models of stress corrosion,pressure solution and free-face dissolution/precipitation were introduced.Taking a hypothetical nuclear waste repository in an unsaturated dual-porosity rock mass as the calculation objective,four cases were designed:1) the fracture aperture is a function of stress corrosion,pressure solution and free-face dissolution/precipitation;2) the fracture aperture changes with stress corrosion and pressure solution;3) the fracture aperture changes with pressure solution and free-face dissolution/precipitation;4) the fracture aperture is only a function of pressure solution,and the matrix porosity is also a function of stress in these four cases.Then,the corresponding two-dimensional FEM analyses for the coupled thermo-hydro-mechanical processes were carried out.The results show that the effects of stress corrosion are more prominent than those of pressure solution and free-face dissolution/precipitation,and the fracture aperture and relevant permeability caused by the stress corrosion are only about 1/5 and 1/1000 of the corresponding values created by the pressure solution and free-face dissolution/precipitation,respectively.Under the action of temperature field from released heat,the negative pore and fracture pressures in the computation domain rise continuously,and are inversely proportional to the sealing of fracture aperture.The vector fields of flow velocity of fracture water in the cases with and without considering stress corrosion are obviously different.The differences between the magnitudes and distributions of stresses within the rock mass are very small in all cases.

关 键 词：stress corrosion pressure solution flee-face dissolution/precipitation dual-porosity medium thermo-hydro-mechanicalcoupling FEM analysis 

分 类 号：TU452[建筑科学—岩土工程]