A new seismic-based strain energy methodology for coal burst forecasting in underground coal mines

Abstract

Coal burst has become a common safety issue in underground coal mines and its triggering mechanism is believed to be highly associated with coal state parameters including stress, strain and energy. As a powerful tool for coal burst forecasting, microseismic (MS) monitoring has the capability of directly monitoring energy release and indirectly capturing stress and strain changes. In this paper, the strain energy transfer in the process of coal burst during underground coal mining was investigated, which revealed that coal burst is caused by strain energy released from the surrounding rock, plus the additional energy input provided by the superposition of static and dynamic stresses. The seismic energy, derived from the strain energy transfer process, was defined and simulated in numerical models. Based on the modelling results, a damage mechanics model was developed to correlate stress, strain, damage and seismic energy release. In this context, a new index named as ‘bursting strain energy (BSE)’ was proposed to quantitatively assess coal burst propensity. This BSE index was first calibrated via numerical modelling and then successfully applied to a Chinese coal mine for coal burst forecasting. Results showed that the BSE index can effectively assess the likelihood of coal burst occurrence in the temporal domain and assess high risk regions in the spatial domain. Such practices can be conducted on a daily basis, which will contribute to the improvement of mine safety and productivity.