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.
In the process of coal resources development, a large number of strip coal pillars have been left behind in the coal mines in central–eastern China. With the increase in coal mining depth year by year, the rock burst threat of strip coal pillars is becoming more and more prominent due to the influence of buried depth, geological structure, gob and other factors. Backfilling mining is the main means to recover the residual strip coal pillar. In order to investigate the effect of backfilling mining on the prevention and control of rock burst, taking the paste backfilling workface 1# of Gucheng coal mine as the engineering background, a comprehensive research method of theoretical analysis, numerical simulation and field monitoring was used to study the evolution of stress and of the overburden spatial structure of the backfilling workface under the control of the backfilled ratio. The results showed that the backfilling mining controls the movement and deformation of overburden by reducing the activity range of roof strata. The overburden fracture development height decreases with the increase in backfilled ratio, but there is a boundary effect influenced by the roof deflection before backfilling and the defective distance of roof contact. With the increase in backfilled ratio, the concentration coefficient of front abutment pressure, the vertical displacement of the roof and the development height of the plastic zone of overlying strata decreased obviously, which indicates that filling mining can effectively control the stress of surrounding rock and the movement of overlying strata. The field monitoring data showed that the influence range of the front abutment pressure of the paste backfilling workface was about 90 m and the maximum stress of the surrounding rock of the two entries did not exceed 7 MPa. The average daily frequency of microseism was 1.34, and the average daily total energy of microseism was 1.80 + 103 J, which decreased by 69% and 90%, respectively, compared with the caving method working face with similar geological conditions. The data above showed that the backfilling mining can effectively reduce the working face stress level and dynamic load strength to achieve the effect of prevention and control of rock burst.