Fracture features of brittle coal under uniaxial and cyclic compression loads

Abstract Under the effects of complex geological and stress environments, burst hazards continue to be a major challenge for underground space utilization deep resources exploration as its occurrence can lead personnel causalities, equipment damage structural collapse. Considering path experienced by in-situ coal body, cyclic loading appears in quite various forms instance shearer cutting, overlying strata breakage, hydro-fracturing blasting, during tunnel, mining utilizing process. The stability body subject periodic loading/unloading is extremely important maintain function designed engineering structure waste storage, safe mining, roadway development, gas recovery, carbon sequestration so on. mechanical properties hard rock fatigue loads has been intensively investigated many researchers induced supercritical long safety risk problems civil tunneling under overburden. More recently, samples from aspect hysteresis, energy dissipation irreversible brittle rising countries. However, crack propagation fracture pattern need more research understand micro mechanism incubation store elastic strain rapidly release when ultimate strength once reached. This studied internal status corresponding different stage samples. AE monitoring was applied uniaxial process record intensity at stages. evolution curve then determined. determined micro-CT scan observed discussed. It found this paper that compression tests demonstrated sudden failure caused splitting while progressive with mixture network.