Correlation of Joint Roughness Coefficient (JRC) and Peak Friction Angles of Discontinuities of Malaysian Schists

The surface roughness of geological discontinuities plays an important role in influencing the stability of rock masses. Several approaches can be adopted for its determination. This paper presents a simple approach whereby two polynomial approximations have been derived to correlate the peak friction angle, fpeak of discontinuity planes of fresh as well as slightly weathered schist bedrock with the Joint Roughness Coefficient, JRC. These polynomial approximations are fpeak= -0.022JRC2 + 3.21JRC + 28.1 for fresh discontinuities and fpeak= -0.025JRC2 + 3.24JRC + 26.6 for slightly weathered discontinuities, both with coefficient of determination (R2) of 0.98. These results offer an alternative method for estimation of the peak friction angle, fpeak by measuring the JRC values in a field survey and employing these equations for the estimation of the peak friction angles of the discontinuity planes of cut rock slopes.