Experimental Investigation of Burst Failure Mechanism Under Polyaxial Loading Conditions

Abstract Effective monitoring and early warning methods are crucial for enhancing safety and sustainability in deep resource extraction, which are particularly important for mitigating rock/coal burst failures. This study introduces a newly modified thick-walled hollow cylinder (TWHC) testing system for rock and coal burst at the laboratory scale. Fracture initiation and propagation, leading to bursting on the wall of a cylindrical opening in granite, bluestone and coal are characterised by real-time acoustic emission (AE) responses. In this study, a borescope was used synchronously to observe the dynamic failure processes of rock/coal bursts and to verify AE results. The internal fracture morphologies of granite, bluestone and coal specimens were acquired using X-ray micro-Computed Tomography (μCT). We analysed the intrinsic mechanism of strain energy evolution of bursting and found that the average energy consumed by the induced cracking and released kinetic energy during bursting is approximately ~ 8, 25 and 18% of the total absorbed strain energy of granite, bluestone and coal, respectively. We found the average mass of the ejected rock/coal fragments to be ~ 0.3–0.5 g, whilst the rock/coal ejection velocity ranged from 10.5 to 19.8 m/s for the hollow coal, bluestone and granite. The results also indicate that granite and bluestone have the highest potential for violent bursting failure.