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Abstract The models of pressure solution and free-face dissolution/precipitation are introduced in the study. Aiming at a hypothetical nuclear waste repository in a saturated dual-porosity fractured rock mass，three computation cases are designed：(1) fracture aperture is a function of pressure solution and free-face dissolution/precipitation；(2) fracture aperture changes only with pressure solution(the matrix porosity of bedrock is also a function of stresses in these computation two cases)；(3) fracture aperture and matrix porosity are constants. Then the corresponding two-dimensional finite element analysis of the coupled thermo-hydro- mechanical processes are carried out；and the states of temperatures，fracture apertures and permeabilities，pore water pressures，flow velocities and stresses in the rock mass are investigated. The results are as follows：the absolute values of increments of fracture aperture and relevant permeability caused by free-face dissolution/ precipitation are obviously larger than those of fracture aperture and relevant permeability caused by pressure solution；and the effects of pressure solution on fracture aperture and relevant permeability are less. The fracture apertures and relevant permabilities modified by combined action of pressure solution and free-face dissolution/ precipitation are about 1.5 and 7.0 times of those modified only by pressure solution，respectively. Under the action of temperature field from released heat，the fracture water pressures in the computation domain rise first，then drop again，but the change extents are not large. The differences between the magnitudes and distributions of stresses within rock mass in the three calculation cases are very small.
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Received: 10 June 2011
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2011, Vol. 30 
