Evaluation of bump-proneness of underground coal mines using burst energy coefficient

Underground exploitation of the deep-seated coal deposits faces a number of problems like coal bumps, pillar squeezes, sudden collapse and floor heaving. Among them, coal bump is one of the most difficult, hazardous and long-standing engineering problems. The bump-proneness of a mine can be used as a safety index and if anyone could identify the bump-proneness of the mine before the commencement of the mining operation, then a suitable safety or risk assessment of the mine can be done. Suitable remedial measures or method of mining can also be implemented to avoid major safety issues like strata control problems. Physical experiments in laboratory and field tests to determine the bump-proneness of a mine is a tedious, expensive and time-consuming process. In this paper, a methodology to evaluate bump-proneness of a mine has been described using Burst Energy Coefficient through numerical modelling along with three case studies, namely Digwadih Colliery of Tata Steel Limited, VK-7 Incline mine of SCCL and Chinakuri mine of ECL. It is found that the Digwadih colliery is not burst-prone up to the depth of 600 m, but it may be moderately burst-prone if the depth of cover of the working is increased to 750 m. Similarly, it is found from the study that the VK-7 Incline mine is not burst-prone up to the depth of cover of 450 m but estimated to be burst-prone at a depth of cover of 600 m. Chinakuri mine is found to be burst-prone for the considered depth of cover of 700 m. It is found that the observed or reported burst-proneness conditions of the mines are well-matching with the burst-proneness index estimated through the numerical modelling. Hence, it can be suggested that the coal bump hazards of mine can be effectively predicted by the burst energy coefficient.