In-situ Test Study on Osmotic Behavior of Fracture Rock Mass under High Head Condition

Combined with high head permeability test and routine water pressure test and indoor permeability experiment for fractured rock mass in high pressure water tunnel in Heimifeng water-pumped storage power project, the variation law of rock mass permeability under high water pressure condition is analyzed to describe the relation between discharge and water pressure. Through the calculation of permeability coefficient of fractured rock mass, relation between water pressure and permeability coefficient is also discussed. By comparison the results of high pressure permeability test, conventional pressure permeability test and indoor permeability experiment, the environmental stress and water pressure state of rock mass are considered as the main factors influencing the permeability coefficient. The experimented and analyzed results indicate that values of permeability in high water pressure are obviously greater than values in low water pressure state. It is also pointed out that values of permeability in indoor experiment are greater than values obtained in situ test.