Rockbursts

Rockbursts are sudden, violent failures of rock around underground excavations caused by high in-situ stresses and the rapid release of elastic energy. They are most commonly observed in deep hard-rock mines where excavation alters the stress field and transient energy builds up in intact rock masses.

Mechanisms involve the accumulation of tensile and shear stress around openings and the rapid propagation of fractures when a critical strength is exceeded. The released energy can propel rock blocks into the excavation, causing block ejection, rib spalling, pillar and roof failure, and explosive ground movement. Energy release may be accompanied by audible seismic events and dust clouds.

Geologic and mining factors influence rockbursts. Deep settings, strong brittle rocks, and extensive faulting or anisotropy increase risk. Excavation geometry, sequencing, and the rate of advance affect stress redistribution. Rockbursts can occur without warning but are often correlated with microseismic activity and ground vibration.

Prevention and mitigation rely on rock mechanics and ground control. Assessments of in-situ stress and rock mass properties guide mine design. Monitoring such as microseismic networks detects precursors. Support systems, including rock bolts, lattice girders, shotcrete, and grout, along with controlled blasting and sequencing, are used to relieve stresses and strengthen pillars and tunnels. Evacuation and stoppage protocols are also integral when signs of instability appear.

Rockbursts present safety hazards and operational challenges in deep mining and underground construction, and understanding their mechanisms remains a focus of rock mechanics research.