Laboratory determination of direct shear strength of granitoid rocks; examples from the host rock of the nuclear waste storage facility of Bátaapáti (Hungary)

Abstract This paper provides test results and interpretation of the shear strength of granitic rocks. The samples were obtained from Bataapati (South Hungary), where the low and medium-activity nuclear waste storage facility of Hungary is under construction. The experiments were carried out under laboratory conditions by using direct shear strength tests of samples drilled and cut from larger granitic blocks. The friction angles of both the maximal and residual shear stress, as well as the cohesion, were detected for various joint systems and also for the cut surface of the granitic rock. The interpretation of test results includes the evaluation of normal stress versus shear strength for cut, moderately rough, rough and calcite-filled joints. The tests have demonstrated that the average internal angle of friction for granitic rocks exceeds 20°, with a maximum of 39° for rough surfaces. Calcite-filled joints have lower friction angles, in the range of 16–23°. The peak shear strength of granitic test speci...