不规则工作面开采矿震活动规律及其致冲风险控制研究

    Research on law of shock bump activity in irregular face and control of inducing rock burst risk

    • 摘要: 针对不规则工作面开采期间矿震频繁问题,以陕西某矿21306工作面为工程背景,采用理论分析、数值模拟和现场实践等方法,分析了21306工作面上覆岩层破断特征及开采期间围岩应力分布特征,研究了不规则工作面开采矿震活动规律,优化了降载释能的矿震致冲风险控制方案。结果表明:35 m的区段煤柱可一定程度上制约两工作面覆岩协同运动,21306工作面开采期间覆岩结构呈“O-X”型破断结构,与相邻采空区形成对称长臂T型结构;工作面推进过程超前区域及运输大巷侧应力影响范围不断扩大,以区段煤柱区域应力集中程度最大,回采至480 m时垂直应力最大,已达到54.67 MPa,约是回采前垂直应力的1.41倍;随着工作面推进形成“刀把型”不规则结构,工作面缩面拐角区域应力集中程度明显较高,工作面缩面后降低了对运输大巷的影响;工作面开采期间震源事件主要分布于回采工作面前方,强矿震主要集中在工作面开采缩面区域、见方区域,且强矿震主要发生在工作面前方50 m及底板上方22~74 m范围内;强矿震诱发力源主要由关键层破断引起;实施了降载释能的矿震致冲风险控制优化方案,有效降低了强矿震的发生频次,保障了工作面后期的安全回采。

       

      Abstract: Aiming at the problem of frequent shock bump during the mining of irregular faces, this paper takes 21306 working face of a mine in Shaanxi as the engineering background and adopts methods such as theoretical analysis, numerical simulation and field practice. The fracture characteristics of the overlying strata on the 21306 working face and the stress distribution characteristics of the surrounding rock during mining are analyzed, the law of mining shock bump activity at irregular faces is studied, and the risk control plan for shock bump induced by reducing load and releasing energy is optimized. Research indicates: the 35 m section coal pillar can restrict the coordinated movement of the overlying strata of the two working faces. During the mining of the 21306 working face, the overlying strata structure is an “O-X” fractured structure, forming a symmetrical long-armT-shaped structure with the adjacent goaf; during the mining period of the working face, the leading area of the working face advancement process and the influence range of the stress on the side of the transportation roadway continue to expand, and the stress concentration in the section coal pillar area is the largest. The vertical stress reaches the maximum at 480 m, which has reached 54.67 MPa, which is about 1.41 times the vertical stress before the mining; as the working face advances to form a “knife-shaped” irregular structure, the stress concentration in the corner area of the working face is significantly higher, and the impact of the working face on the transportation roadway is reduced after the working face is reduced; during the mining of the working face, the shock bump source events are mainly distributed in front of the mining work, and the strong shock bump are mainly concentrated in the mining shrinkage area and square area of the working face, strong shock bump mainly occur within the range of 50 m in front of the work face and 22-74 m above the floor. The source of strong shock bump induced force is mainly caused by the breakage of key layers in some areas; the optimization scheme of mine shock risk control with load reduction and energy release is implemented, which effectively reduces the occurrence frequency of strong shock bump and guarantees the safety of late mining of the working face.

       

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