A study of the principles and methods of quick validation of the outburst-prevention effect in the process of coal uncovering

Given the increasing exploitation depth, outburst under the condition of uncovering coal in crosscut is increasingly dangerous. To prevent the occurrence of outburst, a novel forecast indicator, which is the initial volume of gas emission from the borehole (IVGEB) was proposed to validate the outburst prevention effect. A self-developed experimental device for measuring the initial rate of gas emission from the borehole (IRGEB) was developed correspondingly. The IVGEB value is the sum of the unit length of IRGEB. Experiments have been conducted under different gas injection rates and gas pressures. CO2 and N-2 gases have been used as injection media. After 50 test runs, 48 sets of valid data have been collected. The results suggested that the IVGEB value is approximately proportional to the gas pressure: the higher the gas pressure, the larger the IVGEB value. Furthermore, based on the relationship of the initial expansion energy of released gas (IEERG), which is another forecast indicator and gas pressure, the weak outburst pressure P-1 and intense outburst pressure P-2 of each coal sample could be calculated because the critical values of IEERG were 42.98 and 103.8 mJ/g, respectively. Thus, the IVGEB critical value of weak outburst and intense outburst could be obtained by applying a relation formula between IVGEB and gas pressure. The obtained IVGEB critical value of weak outburst and intense outburst were 39.69 L and 93.32 L, respectively. This approach might provide a possible method to validate the outburst-prevention effect quickly in the process of. uncovering coal in crosscuts within deep mines. (C) 2016 Elsevier B.V. All rights reserved.