In order to probe into the effects of the changes of fracture aperture casued by combined action of normal stress and shear stress on coupled temperature field

seepage field and stress field

introducing the “cubic law” describing the relationship between hydraulic conductivity and fracture aperture

the evolution expressions for hydraulic conductivity of fracture are established

using the 2D FEM code for analysis of thermo-hydro-mechanical coupling in dual-porosity medium for ubiquitous-joint rock mass developed by the author and taking a hypothetical nuclear waste repository located in an unsaturated stratum as a calculation example

the numerical simulations are carried out for six cases in which three kinds of updated pattern of fracture aperture are applied under the conditions in which two sets of joint cross obliquely and perpendicularily respectively

and the distributions and changes of temperatures

pore and fracture pressures

fracture apertures

hydraulic conductivities

flow velocities of groundwater

and stresses in the surrounding rock mass are investigated. The results show that if the fracture aperture depends on only normal stress the closure of fracture aperture is the largest acted by a compressive stress; while the fracture pressure is the highest; if the fracture aperture is a function of normal stress and shearing displacement

the closure of fracture aperture is smaller than the former due to shear dilation effect

so the fracture pressure is a moderate value; but if the fracture aperture is a constant

the fracture pressure is the lowest.