基于微震分布特征的覆岩结构演化规律研究

    Study on evolution law of overburden structure based on microseismic distribution characteristics

    • 摘要: 红庆河煤矿邻空宽煤柱402工作面上方存在多层层厚较大的关键层,关键层的存在会使支承压力的峰值以及影响范围显著增加,基于微震监测数据分析了邻空宽煤柱工作面回采的微震分布特征。发现:邻空宽煤柱工作面回采期间微震分布情况主要受超前支承压力、采空区侧向支承压力以及回采各阶段地质因素引起的构造应力、开采技术因素引起的应力集中共同影响;工作面侧向支承压力的影响范围为180 m左右,同时采空区以里120 m区域顶板结构的稳定性较差,容易诱发大能量微震事件;工作面超前支承压力的影响范围大致为240 m,工作面前方煤岩体受采空区侧向支承压力与超前支承压力叠加影响更容易达到极限状态,煤岩体的破裂、失稳容易诱发大量的微震事件;临空宽煤柱工作面回采受顶板岩层结构影响较大,工作面间覆岩产生协同运动后,采空区上覆岩层再次发生运动与失稳,增加了覆岩破坏高度;并且区段煤柱具有发生压缩变形的趋势,整体表现出煤柱破坏诱发失稳的特征。

       

      Abstract: There are several key layers with large thickness above the 402 working face of wide coal pillar in Hongqinghe Coal Mine. The existence of key layers will significantly increase the peak value of abutment pressure and its influence range. Based on the microseismic distribution characteristics of 402 working face are analyzed based on microseismic monitoring data. It is found that the microseismic distribution of working face during mining is mainly affected by advanced abutment pressure, lateral abutment pressure of goaf, tectonic stress and stress concentration caused by mining technology factors. The influence range of lateral abutment pressure of working face is about 180 m, and the stability of roof structure in 120 m area of goaf is poor, which is easy to induce large energy mine earthquake. The influence range of the advance abutment pressure of the working face is about 240 m. The coal and rock masses in front of the working face are easier to reach the limit state under the superposition of the lateral abutment pressure and the advance abutment pressure of the goaf, and the fracture and instability of coal and rock masses are easy to induce a large number of microseismic events. The mining of wide coal pillar face in goaf is greatly affected by roof strata structure, and the overburden strata in goaf move and lose stability again after collaborative movement of overburden strata between working faces, which increases the failure height of overburden strata. In addition, the coal pillar has the tendency of compression deformation, and the whole coal pillar shows the characteristics of instability induced by failure.

       

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