Influence of two unparallel fissures on the mechanical behaviours of rock-like specimens subjected to uniaxial compression

Abstract

Preexisting unparallel fissures in rock mass significantly affect the overall mechanical behaviours of rock engineering structures. Understanding the mechanical properties of rocks containing unparallel fissures is beneficial for evaluating the overall stability of rock structures. This study comprehensively investigates the geometrical influence of two unparallel fissures on the mechanical behaviours of rock-like specimens, including the fissure inclination angle (α₂), the rock bridge lengths (d) and the bridging angles (β). Experimental results indicate that the strength, deformation characteristics and the crack coalescence modes of fissured specimens are highly dependent on the geometrical configurations of fissures. The elastic modulus of the tested specimen increases with the increase of fissure inclination angle (α₂), rock bridge length and bridging angle. Fissured specimens with lower rock bridge length and higher bridging angle are characterised by higher strengths. Energy analysis reveals that, the specimens with lower fissure inclination angle, higher rock bridge length and lower bridging angle dissipate more energy under uniaxial compression. The specimens with lower fissure inclination angle (α₂), lower rock bridge length and higher bridging angle release more elastic energy. Moreover, the crack evolution of the fissured specimens is numerically revealed by analysing the spatial development of cracks and the stress field in the fissured models.

Keywords:

• Rock-like specimen
• unparallel fissures
• mechanical properties
• crack coalescence
• discrete element method