By using a self-developed shear-seepage coupling experimental device for coal rock

experiments were carried out on sandstone samples to obtain shear-seepage coupled properties under the action of seepage water. The results show that with constant seepage water pressure

the larger normal stress was

the higher shear strength was

but the smaller normal deformation was. Moreover

the shear deformation process of sandstone can be divided into three stages: the linear growth stage

the unstable fracture stage and the friction sliding stage

respectively. In the case of the constant seepage water pressure

as the normal stress decreased

the peak values of normal and shear deformation of specimen increased

and meanwhile the fluctuation of shear section grew. Besides

the surface crack growth became more obvious and widely distributed

and the damage of sandstone was more serious. In the total shear process

there were several apparent value reductions of shear stress. Usually

the first stress reduction occurred at the end of the stage of elastic deformation

and water flowed out at the same time

which means the first stress reduction caused by the first macrocrack is spatial connected. Furthermore

the larger normal stress is

the narrower fracture is and the worse water transmitting ability is. During the whole experimental process

the lower mean flow rate is

the smaller total flow is.