Evaluation of the shear strength parameters plays a very important role in the stability of the hydraulic tunnels and hydro power plant in schistose and sandstone. The effect of shear strength parameters of anisotropic rock with various weakness plane oriented angles and confining σ3 and σ1 were pressure, were investigated. The experimental studies used rock mass from the Nam Soi hydropower in Vietnam. We presented determination methodology to investigate the shear strength parameters of anisotropic rock. The calculations in this study were performed with rockmass from Nam Soi hydropower in Son La province, Vietnam. The triaxial and UCS tests were performed in State Key Laboratory of Geomechanics and Geo-engineering (SKLGGE),Institute Soil and Rock Mechanics, Wuhan, China.
In nature, some rock types show anisotropic behaviors which include weakness planes, bedding, schistosity and joints. The mechanical properties of schistosity have parameters of shear strength that are smaller than the shear strength of intact rock, created weakness planes within the rockmass. Determination of the shear strength of intact rock determines the shear strength of the weakness plane. Determination of shear strength of some rock type scan be modeled by transversal anisotropic body.