Mechanical response and deterioration mechanism of sandstone with intermittent joints under drying-saturation circulation

A drying-saturation cyclic water-rock interaction test simulating the periodic fluctuation process of reservoir water level was designed. The results show that: (1) With the increase of the number of cycles, the compressive strength of sandstone joint gradually decreases. The compressive strength of the first four cycles decreases rapidly and the deterioration effect is obvious. As the joint dip angle increases, the compressive strength of the sandstone joint showing a U-shaped distribution. (2) With the increase of the number of cycles, the elastic modulus of the sandstone joint gradually decreases. With the increase of the joint inclination angle, the elastic modulus showing a "V-shaped" change trend. (3) With the increase of the number of cycles, the brittleness of the sample is obviously weakened, showing 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 intermittent sandstone joint under the action of circulating water-rock have obvious deterioration effects, which are the result of physical, chemical, and mechanical actions occurring inside the sandstone joint.