Abstract: Permeability evolution of the joint is a key scientific problem for the hydraulic characteristic of rock mass. To further understand the permeability variation of coupling granite joint during shearing under high normal stress, the permeability of coupling granite joint was measured during shearing. To solve the sealing problem of high-pressure pore fluid during shear and the measurement of joint permeability, we designed a shear flow testing system for high-pressure porous fluid. Shear flow tests were conducted to obtain the variation of permeability with shear displacement, and the relationship between shear stress/normal deformation and shear displacement. Experimental results show that the joint permeability tends to decrease after shear stress peak under high-stress conditions, though dilatancy occurs during shearing. During the shearing process, the damage mechanism of dilation, compression and asperities contribute to the change of permeability. Under high-stress conditions, the dilatancy characteristics of joints are limited, but the shearing mechanism of asperities is enhanced. The joint permeability under joint shear is thus reduced.

Key words: fracture, shear slipping, higher stress, permeability, transient pulse technique