Mechanical behaviour of fracture-filled rock-like specimens under compression-shear loads: An experimental and numerical study

Abstract

In rock engineering, the failure mechanism of a fractured rock mass under compression-shear stress has been focused on, but the effect of filler in fracture-filled rock masses has not received widespread attention. In this research, compression-shear tests are performed on rock-like specimens with three fissures under four filling conditions, unfilled, gypsum filled, cement filled and resin filled, to obtain the effect of three fillers on the mechanical characteristics and failure mode of fractured specimens. The discrete element method (DEM) is used to analyse the crack propagation and coalescence of the specimens. The results show that the peak load and displacement of specimens primarily depend on the strength of the fillers and inclination angle of the central fissure. For gypsum and cement filled specimens, when the fissure inclination angle is small, the influence of fillers on the peak load and displacement is obvious, but the effect can be neglected when the fissure inclination angle is large. The resin has a remarkable influence on the peak load and displacement of all specimens. Three failure modes were found in this study. Failure mode I primarily occurs when the fissure inclination angle is 0°. Failure mode II appears in specimens with a fissure inclination angle equal to 30° or 45°. The failure mode of specimens with a fissure inclination angle equal to 60°, 75° or 90° is defined as mode III. For the failure mode, the action mechanism of filler is to weaken stress borne by rock-like material. The larger the weakening degree of the shear stress is, the easier tensile failure occurs in filled specimens. However, when the stress is substantially weakened, the failure mode of filled specimens is similar to that of specimens containing no fissures.