ANISOTROPY OF STRENGTH OF ROCK MASS UNDER COMPLICATED STRESS STATE

Discontinuities are ubiquitous in rock masses.The discontinuities significantly affect the strength of rock masses,which cause the failure of the rock mass along the discontinuities.Based on the analysis of the effect of the intermediate principal stress on the strength of rock mass,a twin shear unified strength theory is illustrated.The unified cohesion and friction angle,which are dependent upon the Lode parameter and the intermediate principal stress parameter b,are established.The stress distribution on the discontinuities in rock mass is investigated.The anisotropic strength criterion of rock mass is proposed.For the specific case,the proposed strength criterion is simplified.The application condition of the criterion is also analyzed.The polyaxial test results of jointed rock mass are used to verify the proposed criterion.The results indicate that the proposed criterion can well predict the strength of the jointed rock mass.The effects of the intermediate principal stress,inclination and azimuth of the discontinuities on the strength of rock mass are also investigated.