坚硬顶板特厚煤层初采初放卸压控制及回采率分析研究

Study on Pressure Releasing Control and Recovery Rate Analysis of Initial Mining and Initial Release in Extra-Thick Coal Seam with Hard Roof

针对工作面初采期间强矿压显现现象以及采出率低的问题,以唐家会煤矿坚硬顶板特厚煤层为背景,采用数值模拟、理论分析、现场实测等方法综合研究开切眼切顶卸压技术条件下工作面上覆岩层垮落规律、围岩应力与位移演化特征、顶煤受采动影响破坏规律。FLAC^(3D)数值模拟发现,采用切顶卸压技术可以切断工作面基本顶和切眼煤壁的应力传递,降低工作面超前支承压力峰值,加快上覆岩层回转下沉失稳,使顶板垮落更充分,同时使工作面前方顶煤水平位移增加,顶煤得到更高程度的破坏。理论分析发现,初采切顶卸压技术使基本顶由固支梁转化为悬臂梁,工作面切顶后可以避免采空区顶板大面积悬空,使顶板迅速垮落,优化工作面应力环境。现场实测表明,该技术的应用有效解决了坚硬顶板特厚煤层工作面强矿压显现问题,保障了工作面安全开采,使综放开采可以快速放煤,大幅提高了煤炭回采效率和经济效益。

In view of the phenomenon of strong mine pressure and low recovery rate during the initial mining of the working face, the extra thick coal seam with hard roof in Tangjiahui Coal Mine was taken as the background. Numerical simulation, theoretical analysis and field measurement were used to comprehensively study the caving law of working face, the evolution characteristics of surrounding rock stress and displacement, and the failure law of top coal affected by mining in the condition of roof cutting and pressure releasing technology. FLAC^(3D)numerical simulation indicates that the stress transfer of the basic roof and the coal wall of the cut can be cut off by using the roof cutting and pressure relief technology, which can reduce the peak value of the advance abutment pressure of the working face, accelerate the rotation and subsidence of the overlying strata, and make the roof collapse more fully. At the same time, the horizontal displacement of the top coal in front of the working face increases, and the top coal is destroyed to a higher degree. Through theoretical analysis, it is found that the roof cutting and pressure releasing technology in initial mining makes the basic roof from the fixed beam into a cantilever beam. After cutting the roof of the working face, it can avoid large area hanging of the goaf roof, make the roof collapse rapidly, and optimize the stress environment of the working face. The field measurement shows that the application of this technology effectively solves the problem of strong ground pressure in the working face of extra-thick coal seam with hard roof, ensures the safe mining of the working face, realizes quick discharge of coal in the fully mechanized caving mining, and greatly improves the coal recovery rate and the economic benefit.