Influence of Surface Roughness of the Fracture on Hydraulic Characteristics of Rock Mass

To obtain the influence of surface roughness of the fracture on hydraulic characteristics of rock mass. Firstly, the roughness of three kinds of fracture surfaces were determined using TR600 roughness profiler. The vertical stress and horizontal stress and water head pressure of samples are simulated by normal load, shear load, and seepage water pressure respectively. The coupled shear-seepage tests were carried out using a JAW-600 shear-seepage coupled test system. The changes in hydraulic opening and permeability with shear displacement were obtained under different initial normal stress and normal stiffness conditions. This study shows that the hydraulic opening and permeability of fracture rock mass can be divided into three stages of reduction, accelerated rise and stability with the increase of the shear displacement. Larger initial normal stress correspond to greater the hydraulic opening and transmission rate of the rock mass. Greater roughness of the fracture surfaces correspond to greater hydraulic opening and transmission rate, and worse stability. The water infiltration is proportional to three times the degree of hydraulic opening. A small change in the degree of hydraulic opening can cause great changes in the transmission rate. Under the same stress condition, the degree of the fracture surface roughness will produce important influence on the volume of gushing water.