Sensitivity analysis of influencing factors and control technology for coalface failure

In view of the fact that rib spalling of coalfaces seriously affects normal production in a large-cutting-height panel, the mechanical model of the “coalface–support-roof” is established to analyze the main factors affecting coalface stability, and a real panel, no. 8101, is used as an example. Using the main influence factors with different levels, orthogonal experimental design is used to determine the numerical simulation scenarios. The coalface failure conditions for different simulated scenarios are studied using DEM method. The orthogonal experiment method was used to analyze the simulation results in this study. The coalface is strengthened using the “manila+ grouting” reinforcement technique. The results show that the factors affecting coalface stability are the cutting height, support capacity, coal cohesion, coal friction, and upward-inclined angle. The larger the cutting height is, the larger the roof pressure is on the coalface. The larger the support capacity is, the smaller the roof pressure is on the coalface. The larger the coal cohesion and friction values are, the larger the roof pressure is that the coalface can bear. The sensitivities of cutting height, support capacity, coal cohesion, coal friction, and an upward-inclined angle with respect to coalface stability are 14.60, 2.29, 38.63, 1.19, and 1.95, respectively. In descending order of influence, the factors are coal cohesion ˃ cutting height ˃ support capacity ˃ upward-inclined angle ˃ coal friction. The “manila+ grouting” reinforcement technology effectively controls coalface failure, yields a 30~40% saving in costs, and reduces incidents of coalface failure by 70~80%. The research results provide new insights for the evaluation and control of coalface stability.