In order to understand the influence of seepage under high pressure condition on stress and deformation of fractured rock mass

fully coupling model based on porous media mechanics is employed to study the variations of pore pressure and displacement of measuring point in rock mass during the experiment period

combined with measured data of pore pressure and displacement obtained in high pressure permeability test at Heimifeng pumped storage power station. The hydro-mechanical coupling model is validated by the comparison of calculated results of pore pressure and displacements with measured data. It also indicates that rock mass stress increases sharply under the effect of water pressure in water injected borehole and pore pressure in rock mass. During the experiment

it occurs larger displacement in rock mass due to the seepage. After stopping injection of water

the deformation remains due to the existence of pore water pressure and hydraulic gradient in rock mass. The part of deformation is not the plastic residual deformation of rock mass after the unloading of water injected borehole. Hydro-mechanical coupling effect of rock mass under high water pressure condition is obvious. The evaluated results of rock mass stability with the consideration of hydro-mechanical coupling effect have more significance for engineering design.