高地应力软岩下山非对称变形机理与控制研究

软岩巷道稳定性控制是当今深部煤炭资源开采面临的难点,以刘桥一矿Ⅱ66辅助下山为支护工程实践。现场实测发现巷道底板软弱破碎,围岩非对称变形严重;室内测试显示,围岩强度较低,且富含伊利石、长石和绿泥石等亲水性矿物;地应力测量表明,辅助下山处于高原岩应力区,最大主应力为水平应力且与巷道轴线方向夹角较大,不利于围岩稳定;理论分析显示,由于原支护方案没有采取控底措施,U型钢承载结构稳定性较差,底板破坏易带动帮墙失稳;采用FLAC3D数值模拟软件分析了邻近采掘工程对辅助下山的影响,获得非对称变形诱因和失稳的始发部位。基于上述分析,提出了"注浆锚杆+注浆锚索多层次"组合控制措施,现场工业性试验效果较好,满足安全生产需求。

Study on surrounding rock deformation mechanism and control of soft rock descending roadway in coal mine

With the depletion of shallow resources and the development of coal mining, the disaster of soft rock engineering is prominent. Based on the engineering background of II66 auxiliary descending of Liuqiao No.1 mine, according to its deformation and instability characteristics, the mechanism of auxiliary descending asymmetric deformation and failure is analyzed by means of field measurement, laboratory experiment, theoretical analysis, numerical simulation and industrial test, and the optimal control measures are proposed. The research shows that :(1) the auxiliary downhill floor is weak and broken, and the roadway has significant asymmetric deformation. The surrounding rocks are of low strength, and the fine sandstones are rich in hydrophilic minerals such as illite, feldspar and chlorite. (2) according to the in-situ stress measurement, it is found that the auxiliary down-hill is in the stress zone of the plateau rock. The maximum main stress is horizontal stress and has obvious direction, and the included Angle with the roadway axis is large, which is not conducive to the stability of the surrounding rock. (3) the original support scheme did not adopt bottom control measures, ignoring the stability of u-shaped steel bearing structure, and the failure of bottom plate drives the instability of wall; (4) the numerical analysis results are close to the field observation, and the auxiliary down-slope is greatly affected by the adjacent excavation engineering disturbance, which is the main reason for its asymmetric failure. (5) based on field observation and analysis of deformation and instability mechanism, multi-level combined control measures of grouting bolt and grouting anchor cable are adopted, and structural reinforcement of u-type support is carried out at the same time, which results in good industrial test results and meets the field requirements.