深埋大断面开切眼大厚度泥岩顶板冒顶机理及其梯次支护技术研究

Research on Roof Fall Mechanism and Cascade Support Technology of Deeply Buried Large Section Open-off Cut and Large Thick Mudstone Roof

针对深埋大断面开切眼大厚度泥岩顶板易发生冒顶的问题,以张家洼煤矿9 m宽的大断面开切眼为研究对象,采用室内试验、现场实测、理论分析及数值模拟等研究了该类巷道的围岩变形破坏特征与应力场分布特征,揭示了冒顶机理,并提出了锚网梁+长短锚索的梯次主动支护与单体柱+木垛的联合被动支护相组合的协同控制技术。结果表明:发生冒顶的内在原因是直接顶的大厚度泥岩强度低,外在原因是水对泥岩的崩解破坏、单体柱反复加卸载的疲劳损伤以及深部高应力,主要原因是支护参数不合理。通过梯次支护中9.3 m的短锚索与锚网梁将顶板中下部的软岩有效组合在一起,形成一个具有承载作用的锚固体,且受力均匀;通过梯次支护中12.3 m的长锚索将该锚固体悬吊于深部稳定岩层。再配合该联合被动支护的有效支撑与信号作用,协同实现该条件下巷道围岩的有效控制。采用梯次支护技术后,1305开切眼围岩稳定性显著提高。

Aiming at the problem that the deep-buried and large-section open-cut and large-thickness mudstone roof is prone to roof fall,the 9-meter-wide large-section open-cut in Zhangjiawa coal mine is used as the research object,and indoor experiments,field measurements,theoretical analysis and numerical simulation are used.The surrounding rock deformation and failure characteristics and stress field distribution characteristics of this type of roadway are revealed,the roof fall mechanism is revealed,and the combination of cascaded active support of bolt mesh beam+long and short anchor cables and combined passive support of single column+wood pile is proposed.Collaborative control technology.The results show that the internal reason for roof fall is the low strength of the thick mudstone directly on the roof,and the external reason is the collapse and failure of the mudstone by water,the fatigue damage caused by repeated loading and unloading of the single column,and the high stress in the deep part.The main reason is the support parameters unreasonable.The 9.3 m short anchor cable and the anchor mesh beam in the ladder support effectively combine the soft rock in the middle and lower parts of the roof to form an anchor solid with load-bearing effect and uniform force;through the ladder the 12.3 m long anchor cable suspends the anchor solid to the deep stable rock formation.Coupled with the effective support and signal function of the combined passive support,the effective control of the surrounding rock of the roadway under this condition is realized in coordination.After adopting the cascade support technology,the stability of the surrounding rock of the 1305 open cut is significantly improved.