Determination of the Shear Strength Parameters of Rock Mass Based on Nonlinear Failure Criterion

The prediction of the shear strength is an important part in the analysis for rock mass stability.The shear strength parameters of the rock mass are described by the Hoek-Brown nonlinear failure criterion in this paper.And a transformation procedure from the Hoek-Brown parameters to the Mohr-Coulomb parameters is proposed.In the transformation procedure,the theoretical analysis and data fitting method are used.The influences of each parameter in the nonlinear failure criterion on the shear strength parameters are analyzed.It is shown that the relationship between the shear strength parameters and Hoek-Brown criterion parameters can be determined by fitting a large amount of data.With the increase of geological strength index GSI,the shear strength parameters c and Φ increase gradually.The effect of cohesion on the rock geological strength index is more sensitive to the friction angle.But their variations with the mi are not that large,which indicates that the GSI has a larger effect on the rock strength than on mi.The results can give some guidance for the real practice.