Development of shear-flow test apparatus and determination of coupled properties of rock joint

In order to investigate the hydromechanical coupling properties of rock joints, a new test apparatus including different flow systems consist of constant head, constant pressure, constant flow rates and also back pressure system is developed to perform test under wide range of hydraulic head and hydraulic gradient. Experimental test under normal and shear mode are performed and results show that, increasing normal stress cause a decrease in hydraulic conductivity. Furthermore, the results indicate that the inlet water pressure directly affects hydraulic conductivity. During shear process; increasing shear displacement causes a decrease in hydraulic conductivity about one order, and sudden increase of about three orders of magnitude. Changes of inlet water pressure during shear do not show significant changes in hydraulic conductivity. It is clarified that there is complexity of flow in a rock joint, and the parallel plate model is difficult to apply specifically to the evaluation of the hydraulic conductivity of a rock joint. The main reason is the variable flow path in rock joint according to the flow conditions.