The effect of confinement on rock failure behaviour under high-velocity impact

The result of redistributed quasi-static stress and/or dynamic sources can be serious underground disasters such as rock bursts. Rock failure characteristics are heavily affected by loading rates and confinement. A deep understanding of their roles has practical significance in evaluating the stability and the design of underground engineering. In this study, specimens were first confined under quasi- static uniaxial, biaxial and triaxial pre-stress conditions and then these were impacted by the launch of a high-velocity striker using a triaxial Hopkinson bar system. A high-speed imaging technique was used to record real-time deformation and fracturing processes. The rock dynamic behaviours such as stress- strain behaviours and energy evolutions were quantitatively investigated. The relationship between mechanical properties and fragmentation features was also presented.