INFLUENCE OF ANISOTROPIC PERMEABILITY OF ROCKMASS ON STABILITY OF UNDERGROUND OIL STORAGE CAVERNS

Underground oil storage caverns are the main mode to strategic crude oil storage in the world,which is the underground rock caverns below ground water level and prevented leakage by water sealed. And the permeability of surrounding rock mass would affect the stability of caverns,especially the anisotropic. Taking an oil storage caverns as a case, which is the first large oil storage project in China. Based on calculation of permeability tensor of Granitic Gneiss,the groundwater pressure distribution,flow velocity,displacement and stress in the surrounded rock was gained with different anisotropic permeabilities by finite element method(FEM).And the factor of safety of rock caverns was obtained by strength reduction on the Generalized Hoek-Brown criterion. It shows that anisotropic permeability of Granitic Gneisses has a significant effect on the groundwaterpressure and flow velocity in surrounding rock,which the pressure increase linearly and flow velocity decrease logarithmic with increase of permeability anisotropy ratio. It has no effect on displacement and negligible on stress of surrounding rock. But it has a greater impact on factor of safety of rock caverns,which is general decreased with anisotropy ratio increased. It has some theoretical and engineering values to stability evaluation of underground water sealed oil storage caverns.