高应力煤巷围岩控制关键技术研究

Research on key control technology of surrounding rock in high stress roadway

针对深井高应力煤巷帮部煤壁整体偏移、锚杆剪切破断、巷道围岩变形剧烈等支护难题,以城郊矿二水平西翼回风大巷为工程背景,采用YTJ-20型岩层探测记录仪实测、微梯形与矩形断面巷道力学结构分析、FLAC3D数值模拟及现场试验监测分析相结合的方法,观测了巷道围岩裂隙演化规律,探究了不同地应力、侧压系数对巷道稳定性的影响特征,并提出了微梯形断面巷道支护设计方案。研究结果表明:煤巷呈大松动圈发育特征,围岩碎胀变形范围大、变形持续时间长、支护难度大,高地应力是其主要影响因素;力学结构对比分析表明微梯形断面受力小于矩形断面巷道,有利于增加巷道的抗冲击性;数值模拟显示微梯形巷道应力集中、塑性区发育范围及围岩变形量相较于矩形煤巷均有所减小,尤其帮部位移减小量明显,微梯形巷道断面有利于巷道围岩稳定性控制。断面形状优化设计及合理支护技术是实现高应力煤巷围岩变形有效控制的关键。结合现场深井高应力煤巷围岩条件,基于悬吊理论与数值模拟优化确定了微梯形巷道合理支护设计参数,跟踪监测结果显示巷道顶板下沉量达到20mm时趋于稳定,两帮移近量为82mm,底鼓量为126mm,表明深井高应力煤巷顶板采用锚网带+锚索梁、帮部采用锚网带的联合支护方案的围岩控制效果良好,可满足深井高应力煤巷长期稳定要求。

Coal roadway in deep buried depth with high stress conditions has many difficult support problems,such as overall rib deformation,anchor bolt shear fracture,which seriously restricts the continuation of mining and tunneling,and affects the safe and efficient mining.Taking the Level-II west wing return-airroadway of Chengjiao Mine as the engineering background,the evolution law of surrounding rock fissures of the roadway is observed by YTJ-20 type on-site rock formation detector,the design of slight-trapezoidal shape roadway is proposed by mechanics model analyses theoretical of slight-trapezoidal shapeand rectangular shape,FLAC 3D software is used to simulate the plastic zone evolution and deformation characteristics in surrounding rock under different ground stress conditions.The results show that:the surrounding rock has alarge-loose circle of rock,including large deformation range,fast initial deformation,long deformation duration and difficultyin supporting,high geo-stress is the main reason for the deformation and failure of the surrounding rock.The stress structure analysis shows that the force of the micro-trapezoidal shape has a relatively lower stress,which is beneficial to increase the impact resistance for the roadway,and also has a better surrounding rock control effect.The slight-trapezoidal shape has a relatively lower stress,which is beneficial to increase the anti-shock resistance for the roadway,and also has a better surrounding rock control effect.The roadway in slight-trapezoidal shape has a lower stress concentration,plastic zone and deformation than rectangle shape,especially the displacement of the side was significantly reduced,which is helpful for the stability control of the deep buried roadway with high geo-stress.The optimized shape design and reasonable support technology are the key to realize the effective control of surrounding rock deformation in high geo-stress coal roadway.Combined with the surrounding rock conditions of high stress coal roadway,the reasonable support parameters were determined based on suspension theory and numerical simulation.The tracking monitoring results show that the roof sinking reaches 20 mm and tends to be stable,two rib deformation reaches 82 mm,and floor heave is 126 mm,indicating that the deep well high stress coal roadway is designed as a micro-trapezoidal section,the roof plate adopts the anchor net belt+anchor cable beam joint support scheme,and the rib is supported by anchor net belt support.The rock control effect is good and can meet the long-term stability requirements of coal roadway.