Research on Engineering Practice and Effect Evaluation Method of Pressure Relief in Deep Rock Burst Danger Area of Coal Mine

Abstract

With a gradual increase in coal mining depth, the underground geological situation is more complex and the threat of rock bursts is more prominent due to the cross influence of multiple factors, such as faults, thick hard roofs, coal pillars, and high in situ stress areas. Additionally, it is difficult to test the effectiveness of multiple pressure relief measures after implementation in mining areas with rock burst dangers. By evaluating the geology and mining conditions of panel 5308 of the Tangkou coal mine, pressure relief prevention and control technology, combining pre-pressure relief and a danger relief measure, was proposed. An evaluation method for pressure relief implementation in deep mine rock burst danger areas was proposed, with changing rates of event frequency in microseismic high-energy intervals, changing rates of the mean values of hydraulic-powered support stress, and changing rates of bursting strain energy as evaluation indicators. The weight of each indicator was determined based on an analytic hierarchy process. The degree of pressure relief was measured by the pressure relief interval index. The comprehensive pressure relief effect index was calculated by an interval index and by a weight vector. Additionally, the classification standard of the pressure relief effect was proposed. The results show that the frequency of microseismic high-energy interval events decreased by 34.9%, the mean value of hydraulic-powered support stress decreased by 12.7%, and the bursting strain energy decreased by 14.7% after pressure relief was applied at panel 5308. Additionally, the interval indexes corresponding to each indicator were 3, 2, and 2 and the pressure relief effect index was 2.55, so the destress effect was good. The drilling method monitoring data show that the average value of the drilling powder decreased by 18% after pressure relief compared with before and the overall effect was good, which is consistent with the evaluation results of the multi-dimensional pressure relief implementation effect evaluation system, indicating that the evaluation system can accurately test the effectiveness of the multi-dimensional pressure relief implementation effect in deep mine rock burst danger areas. The results of the study provide methodological support and reference for the monitoring and prevention of rock bursts in mines with similar geological conditions.