Shear strength of non-persistent rock joints

摘要

The present experimental study was conducted to investigate the strength-anisotropy, failure mechanism, progressive failure and scale effect of closed persistent and non-persistent multiple, single plane and offset rock joints under uniaxial compressive load. The parameters investigated are: orientation with respect to the applied axial load, degree of persistence, relative joint density and joint friction angle. Four modes of failure were observed; failure along the plane of the joints (mode 1), which occurred in samples with joints oriented at 22.5° to the applied axial load and have degree of persistence, k, of 0.667 and in samples with joints oriented at 45° to the applied axial load and have k of 0.8, stepping failure (mode 2) which occurred in samples with joints oriented at 45° to the applied axial load and have k of 0.667, multiple-plane stepping failure (mode 3) which observed in sample with joint oriented at 67.5° to the applied axial load and has k of 0.667 with joint spacing, d, of 2 in., and the last mode observed was failure along the intact material for samples with joints oriented at 80° to the applied axial load and joint spacing, d, of 102 mm and 50.8 mm.