Influence of weathering on shear strength of joints in a porphyritic granite rock mass in Jechon area, South Korea

Abstract

The evolution of the shear strength of rock joints due to weathering processes is evaluated in terms of the joint wall compressive strength (JCS) and residual friction angle. Laboratory direct shear tests were performed on 32 porphyritic granite joints sampled from granitic rock slopes along a highway in the area of Jechon in South Korea. These samples were classified according to their initial weathering state and morphological conditions of the joint surface before direct shear tests. This study shows that JCS can be reduced by 20–25% of the initial JCS value for a fresh joint wall by weathering processes and that the residual friction angle depends mainly on the weathering state of the joint surface.