The original Maksimovic peak shear strength criterion

has a concise form and clear physical meaning of the used parameters; but it cannot be used as a predictive tool to assess the peak shear strength of rock joints

because the roughness angle

which reflected the roughness of joint surface

is determined by back analysis according to the experimental results. The modified one inherits all the merits of the original criterion and the roughness angle is determined by a quantified roughness metric. In the current study

the modified Maksimovic criterion is validated using experimental data of rock joints. The good agreement between the calculated values and the measured ones indicates that the modified one has the ability to evaluate the peak shear strength for rock joints.