In this research, rock mass deformation modulus (Emass), classification of rock mass, cohesion (c) and internal friction angle (Φ), and intact rock properties of the Khersan 2 dam site were investigated. Factors affecting mechanical properties were investigated and compared with the results of previous studies. To assess the shear strength and the Hoek and Brown failure criteria parameters, the triaxial test was performed on samples under saturated conditions. The Q-system and rock mass rating (RMR) were calculated for five-metre sections of boreholes. Results of the Mohr–Coulomb failure criterion showed that the limestones have a mean Φ of 40 degrees and a mean cohesion of 1 MPa, marl limestones have an average of 30 degrees and cohesion of 0.50 MPa, and anhydrite and gypsum showed an average of 26 degrees and 0.10 MPa. The results showed that c and Φ increase with the increase in the shear box size. Based on the RMR and Q-system the site was classified in good class. The mean of Emass showed that the dilatometry test gives the lowest value. Linear and logarithmic relationships were established between RMR89 with compressional wave velocity (Vp) (R2 = 0.95 and RMSE = 1.63) and Q-system (R2 = 0.95 and RMSE = 2.05), respectively.
