Research on stability control technology of surrounding rock along goaf roadway with water intrusion in isolated island working face
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摘要: 目前对孤岛工作面采空区积水弱化围岩条件下的合理煤柱留设研究较少,仅从积水侵蚀煤柱承载强度弱化影响因子、煤柱常规应力简化模型、实验室测定积水弱化煤柱强度等某一方面进行简化分析或理论研究,沿空巷道围岩控制效果不佳。针对该问题,以国能蒙西煤化工股份有限公司棋盘井煤矿I020908回风巷为工程背景,针对孤岛工作面采空区积水弱化条件下沿空巷道围岩变形严重这一特征,采用实验室测定和数值计算分析法,通过室内物理力学实验测定了干燥和吸水饱和2种条件下的煤岩体物理力学参数;基于测定的参数利用FLAC3D数值软件建立了围岩弱化数值计算模型,分析了采空区积水条件下巷道围岩侧向支承应力演化规律、塑性区分布特征;建立了考虑积水弱化的煤柱力学模型,确定了水侵条件下合理煤柱宽度为6~12 m;针对回风巷煤柱帮受积水侵蚀影响,容易产生冒顶和片帮的问题,提出了孤岛工作面水侵条件下沿空巷道围岩稳控技术方案,当煤柱宽度为6 m时,对巷道进行锚索加强支护能够有效控制巷道围岩的大变形。采用加强支护后巷道围岩变形在52 d内趋于稳定,顶底板最大移近量约为200 mm,两帮最大移近量约为130 mm,比原支护条件下围岩移近量降低85.6%,巷道围岩控制效果较好。Abstract: At present, there are few researches on the reasonable coal pillar design under the condition of accumulated water weakened surrounding rock in the goaf of isolated island working face. Only simplified analysis or theoretical researches are conducted from one aspect such as the influencing factor of weakened bearing strength of coal pillar by accumulated water, simplified model of conventional stress of coal pillar, laboratory determination of accumulated water weakened coal pillar strength, etc. The effect of surrounding rock control along goaf roadway is poor. In order to solve this problem, the I020908 return airway of Qipanjing Coal Mine of China Energy Mengxi Coal Chemical Co., Ltd. is studied as the engineering background. In order to solve the problem of serious deformation of the surrounding rock along the goaf roadway under the condition of accumulated water weakening in the goaf of the isolated working face, the physical and mechanical parameters of the coal rock mass under the two conditions of dryness and water absorption saturation are determined by indoor physical and mechanical experiments using laboratory measurements and numerical calculations and analysis methods. Based on the measured parameters, FLAC3D numerical software is used to establish a numerical calculation model for the weakening of surrounding rock, which analyzes the evolution law of lateral support stress and the distribution characteristics of plastic zone in the surrounding rock in the roadway under the condition of accumulated water in the goaf. The mechanical model of accumulated water weakened coal pillar is established and a reasonable coal pillar width of 6-12 m under the accumulated water condition is determined. In order to solve the problem of roof falling and rib spalling caused by the water intrusion of the coal pillar of the return airway, a technical scheme for the stability control of surrounding rock along goaf roadway with water intrusion in isolated island working face is proposed. When the width of coal pillar is 6 m, the anchor cable reinforced support of the roadway can effectively control the large deformation of the surrounding rock of the roadway. The deformation of the surrounding rock of the roadway tends to be stable within 52 d after using the reinforced support. The maximum displacement of the roof and floor is about 200 mm, and the maximum displacement of the two sides is about 130 mm, which is 85.6% lower than the displacement of the surrounding rock under the original support condition. The control effect of the surrounding rock of the roadway is better.
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