Mechanical response and deterioration mechanism of sandstone with intermittent joints under cyclic drying–saturation

Abstract

A drying–saturation cyclic water–rock interaction test simulating the periodic fluctuation of reservoir water level was designed. The results are as follows. (1) With increasing number of cycles, the compressive strength of a sandstone joint gradually decreases. The compressive strength decreases rapidly for the first four cycles and a deterioration effect is obvious. As the joint dip angle increases, the compressive strength of the sandstone joint shows a U-shaped distribution. (2) With increasing number of cycles, the elastic modulus of the sandstone joint gradually decreases. With increasing joint inclination angle, the elastic modulus shows a V-shaped trend of change. (3) With increasing number of cycles, the brittleness of the sample obviously decreases and the sample shows the characteristics of looseness and weakness. With the increase of joint inclination, the failure mode of the sample gradually changes from tensile failure to tensile-shear failure to tensile failure. (4) The mechanical properties of an intermittent sandstone joint under circulating water–rock interaction show obvious deterioration effects, which are the result of physical, chemical and mechanical actions occurring inside the sandstone joint.