高应力红页岩巷道失稳机理与控制技术研究

Research on instability mechanism and control technology of high-stress red shale roadway

为解决高应力红页岩巷道维护的难题,本文以平安磷矿二矿为工程背景,采用理论分析、数值模拟、室内测试及工业性试验等方法,研究了红页岩的微观结构特征及巷道失稳机理。研究结果表明:红页岩内部孔隙孔径主要集中在0~50 nm和10~200μm之间;自然状态下孔径在10~200μm之间的微孔隙占总孔隙体积的37.45%,吸水后占比增加至45.82%,吸水后引发的岩石强度弱化是造成红页岩巷道失稳破坏的重要原因。本文提出了高强锚注+格栅拱架+小孔径锚索的高应力红页岩巷道支护对策,该支护结构能够适应红页岩巷道初期的变形要求,有效限制巷道出现过大的变形,并充分调动深部围岩的承载能力。现场监测结果表明,红页岩巷道两帮最大变形量在100 mm以内,顶板下沉量控制在40 mm以内,锚索受力在100~120 kN之间趋于稳定,说明新方案控制效果良好。

In order to solve the maintenance problem of high-stress red shale roadway,the No.2 mine of Ping’an phosphate mine is taken as the engineering background.Theoretical analysis,numerical simulation,experimental test and engineering practice are used to study the microstructure characteristics of red shale and the mechanism of roadway instability.The results show that the pore diameter of red shale is mainly distributed in 0-50 nm and 10-200μm.In the natural state,the micropore in 10-200μm accounts for 37.45%of the total pore volume,and it will increase to 45.82%after water absorption.The weakening of rock strength caused by water absorption is an important reason for the instability and failure of red shale roadway.The roadway supporting measures including high-strength bolt-grouting,grid arch and small diameter anchor cable are proposed.The supporting structure can adapt to the initial deformation requirements of the red shale roadway,effectively limit the excessive deformation of the roadway,and fully mobilize the bearing capacity of deep surrounding rocks.Field monitoring show that the maximum deformation of the two ribs of the red shale roadway is within 100 mm,the roof subsidence is controlled within 40 mm,and the force of the anchor cable is 100-120 kN and tends to be stable,indicating that the new scheme has good control effect.