Experimental study on the mechanical properties of intermittent jointed sandstone considering water-rock interaction and confining pressure effect

In geotechnical engineering, jointed rock mass is often affected by water-rock interaction and confining pressure effect. Axial compression tests were carried out on intermittent jointed sandstones with different inclinations under different immersion times and different confining pressures. The results show that (1) with the increase of immersion time, the compressive strength and elastic modulus gradually decreases. With the increase of the confining pressure, the compressive strength and the amplitude also increases. With the increase of the joint inclination, the compressive strength and elastic modulus changes in a “V-shaped” shape, and the compressive strength and elastic modulus are the smallest when the joint inclination is 60°. (2) With the increase of immersion time, the number of secondary cracks increases, and the angle between the crack and the radial direction of the sample is about 0~45°, which belongs to plastic failure. (3) With the increase of the confining pressure, the cracks become shorter and the number increases, the angle between the crack and the radial direction of the sample becomes smaller. The plastic failure gradually occurs in the sample. (4) The deterioration of the mechanical properties of the intermittent jointed sandstone is essentially the external manifestation of the physical and chemical action of the sample under the water-rock action and the effect of confining pressure, and it is a process of continuous accumulation of damage.