深部综采工作面开采过程上覆煤岩体裂隙演化特性

Evolution Characteristics of Overlying Coal-Rock Fractures in Mining Process of Deep Fully Mechanized Mining Face

摘要: 为了掌握深部综采工作面开采过程上覆煤岩体裂隙演化特性，优化突出煤层瓦斯治理方案，本次以9#-101综采工作面为工程背景，建立了相似模拟试验平台，通过测定上覆煤岩体应力变化和位移变化，研究了深部综采工作面开采过程中上覆煤岩体的运动特征、位移变化规律、裂隙演化特性。研究结果表明：采空区顶板岩层移动是一个垮落下陷过程，在靠近煤壁处，由于顶板没有完全冒落，存在较多的空洞，顶板内的裂隙在相当长的时期内存在。煤层上方的冒落带高度大致为0~9 m的高度，顶板垮落步距约为20 m，裂隙带的高度在10~28 m的范围。煤壁上方的应力集中区是不断向前迁移的动态变化的区域(远离工作面向煤体深部迁移)。应力集中峰值出现工作面前方4.0~6.1 m范围内，支撑应力影响范围约为工作面前方15~20 m。工作面后方13~27 m范围内应力积聚下降。随着工作面的推进、采空区冒落范围的不断扩大，上覆煤岩体裂隙经过了卸压、失稳、起裂、张裂、裂隙萎缩、变小、吻合、封闭的演化过程。这种演化过程直接影响了采空区内瓦斯的解吸、流动及储集。当采空区长度达到143 m左右时，位于采空区中部的上覆煤岩体裂隙基本被压实，而采空区两端的上覆煤岩体裂隙发育。最后将研究结果应用于该煤矿高瓦斯突出煤层开采时的瓦斯治理设计，取得了较好的瓦斯治理效果。

Abstract: To obtain the fracture evolution characteristics of overlying coal-rock strata, and optimize the gas control scheme for outburst coal seams during the mining process of deep fully mechanized mining face, the study took the No.9#-101 fully mechanized mining face as the engineering background and established a similar simulation test platform. By measuring the stress and displacement variations of the overlying coal-rock strata, the movement characteristics, displacement variation laws and fracture evolution characteristics of the overlying coal-rock strata during deep fully mechanized mining were investigated. The research results show that the movement of roof strata in the goaf is a dynamic and continuous process. Because the roof is not completely caved and there are many cavities, fractures in the roof persist for a quite long period. The height of the caving zone above the coal seam is approximately 0~9 m, the roof caving step distance is about 20 m, and the height of the fracture zone ranges from 10 to 28 m. The stress concentration zone above the coal wall is a dynamically changing area that migrates forward continuously (toward the deep coal body away from the mining face). The peak stress concentration occurs in the range of 4.0~6.1 m in front of the mining face, and the influence range of abutment stress is about 15~20 m in front of the mining face. The stress accumulation decreases in the range of 13~27 m behind the mining face. With the advance of the mining face and the continuous expansion of the goaf caving range, the fractures of the overlying coal-rock strata undergo an evolution process of pressure relief, instability, initiation, tensile fracturing, fracture atrophy, reduction, anastomosis and closure. This evolution process directly affects the desorption, flow and accumulation of gas in the goaf. When the length of the goaf reaches about 143 m, the fractures of the overlying coal-rock strata in the middle of the goaf are basically compacted, while the fractures of the overlying coal-rock strata at both ends of the goaf are well developed. Finally, the research results were applied to the gas control design for the mining of high-gas and outburst coal seams in this coal mine, achieving favorable gas control effects.