Empirical shear strength criteria for filled jointed of metasedimentary sandstone

Abstract

Rock joint shear failure criteria constitute numerical simulation that significantly governs the calculation for rock mass stability analysis. The presence of joint infilling potentially reduces the estimation accuracy for the deformation of rock joint. This study discovers the role of infilling thickness in governing the empirical calculation of linear Mohr-Coulomb failure criterion and non-linear Barton-Bandis failure criterion. A series of direct shear tests with constant surface roughness and controlled infilling material composition facilitates the joint shear strength with various infilling thicknesses. The results indicate that the joint shear strength decreases primarily with infilling material within the joint aperture. Although all the friction angles are closely similar, different cohesion values show the influence of infilling material thickness on shear strength characteristics. The joint shear strength values indicate significant differences where the filled joint shear strength reduction depends on associated infilling thicknesses and the adopted failure criterion. Multiplication to the Filled Joint Factor (FJF ) normalized from the tfilled joint/tcleaned joint ratio will precisely evaluate the filled joint shear strength. Hence, the shear strength estimation from Mohr-Coulomb and Barton-Bandis failure criteria to the various thicknesses of joint infilling will provide sufficient filled joint deformability characteristics.