Investigating the mechanism and prevention of coal mine dynamic disasters by using dynamic cyclic loading tests

As one of coal mine dynamic disasters, rockbursts generally result in abrupt displacements and unpredictable coal rock failures with disastrous consequences and pose serious threats to mine health and safety all over the world. To improve mine safety, this work investigated the disaster-inducing mechanism and safety-control measures of rockburst. Laboratory dynamic cyclic loading tests were used along with a high-speed camera to capture the bursting failure of coal which was used to characterize this disaster evolution. Acoustic emission data were acquired. By adopting the velocity tomography technique, these data were used to inverse the spatial stress distribution inside the coal at different loading stages. It was found that there are many localised areas with different degrees of stress concentration inside the coal. The failure process of coal consists of several stages of bursting damage with violent ejection of broken coal material. The bursting damage is likely to occur in areas characterized by high stress concentration and dense micro-cracks, and is attributed to the inhomogeneous accumulation and unstable release of elastic energy. Rockbursts can be weakened or avoided by reducing stress concentration and controlling energy release intensity. Application of safety-control measures including destress boreholes and destress blasting have achieved good prevention effects.