Retracement Techniques for Working Faces with High Instability Tendency at Large Inclination in Deep Tectonic Zone

Retracement of large inclination in deep tectonic anomalies has a high risk of instability. Taking 6199 working face in Panxi Mine as the background, theoretical analysis, numerical simulation, combined with engineering data, were used to analyze the tendency of instability and mechanism of the working face during the retracement period. The study shows that: the working face is in a complex high-stress environment, and has a high tendency to destabilize dominated by the roof under high overburden pressure and continuous weakening of the roof support of the working face during the retracement period. The mechanical model of roof-hydraulic supports action is established, the analysis showed that avoiding basic roof broken is the key to maintain the structural balance of the roof, and the calculation method of the number of hydraulic supports left to meet the roof control is proposed, and the number of hydraulic supports left should be calculated to be not less than 48. Propose the method and scheme of controlling the roof by uniformly retaining part of the support and Active support of the working face, and analyze the effect by numerical simulation, which shows that the basic roof displacement of uniformly retaining part of the support retracted is relatively small. The analysis results of mine pressure data during the retracement of the working face show that no obvious movement of the roof rock layer occurred, and the roof control effect is good.