Experimental Study on Failure Behaviour of Ligaments Between Strike-Inconsistent Fissure Pairs Under Uniaxial Compression

Aiming at the fact that discontinuities in rock mass exhibit different orientations, uniaxial compression tests of resin specimens containing a strike-inconsistent fissure pair were carried out to investigate the failure behaviour of the ligaments. Combined with computerized tomography scanning technology, cracking behaviour and ligament failure pattern were revealed. The failure characteristics and mechanical properties of specimens were studied. The results indicate that the primary cracks generally initiate at a local point of the pre-existing fissure tip, then integrate into a wavy-shaped crack, and develop into a large wrapping crack over time. With the variation of fissure deflection angle, the ligament exhibits three failure patterns: spalling failure, coalescence of cracks at the proximal end and incoherence at the distal end, and torsional failure. The crack initiation stress generally exhibits an increasing trend as fissure deflection angle increases. Peak stress and strain difference are closely related to fissure deflection angle and failure pattern. The mechanical properties of specimens with parallel fissure deflection are the most affected by the fissure deflection angle, followed by those with steep fissure deflection, and those with gentle fissure deflection are minimally affected.