Impermeability quality evaluation of rock mass

The impermeability of rock mass is one of important indexes to evaluate the rock foundation of hydraulic structure and underground-water caverns, which have direct relation to rock quality and necessity to take impermeable measure. The paper build the indexes system of evaluating rock impermeability that taking the dam rock mass of Gauanyinyan Hydropower Station as an example, extension assessment method is used to appraised rock impermeability. The results coincided with the evaluation results according conditions, which indicated that this system is feasible to evaluate the impermeability quality of rock.