Abstract：This random-fuzzy monovariant linear regression method for determining the shear strength parameters is modified in consideration of the randomness and fuzziness of rock. The formulae for calculating the uncertainty and variation coefficient of regression coefficients，and correlation coefficient of the regression equation，are derived. Based on the experimental data of triaxial compression test，methods for determining the values of the shear strength parameters of rock are discussed. The regression equation of the random-fuzzy monovariant linear regression method is more consistent with the experimental data than the least squares method. The results show that the proposed method is preferable to the conventional one.
