采动影响下底板暗斜井的破坏机理及其控制

针对采动影响下底板巷道围岩出现的大变形失稳及屡修屡坏的控制难题,综合现场调研、理论分析、数值计算及井下试验与实测等方法,对采动条件下底板应力的分布和传播规律及其与巷道围岩应力的关系、底板暗斜井受回采过程扰动的动态变形破坏特征、底板巷道的失稳机制及控制方法进行了系统研究。结果表明,围岩应力分布受超前支承压力在底板中传递的显著影响是底板巷道变形破坏的根本原因。在采动加卸载作用下,底板水平应力增量与垂直应力增量的异步变化引起围岩帮部的环向应力激增并破坏造成顶底板临空宽度的加大,进而导致顶板破断和严重底臌。采用高阻可让压锚索减小顶底板的临空宽度、抑制底臌大变形,提出了锚网索+注浆+底板锚索的控制方法。对江西高坑矿底板暗斜井进行了现场支护试验,围岩控制效果良好。

Failure mechanism of the subinclined shaft in floor under mining influence and its control

In light of control problem for large deformation instability and repeated repair of roadway in floor，the combination of site investigation，theoretical analysis，numerical calculation and measurement methods were used.The distribution and propagation law of the floor stress under mining conditions and its relationship to surrounding rock stress，dynamic deformation and failure characteristics of subinclined shaft in floor disturbed by mining process，instability mechanism and control method of roadway in floor were systematically studied.The results show that the primary cause of roadway in floor’s damage is that the distribution of rock stress is significantly affected by abutment pressure passing in floor.Under the loading and unloading of mining，hoop stress of sidewalls that are damaged increase sharply due to asynchronous changes between horizontal stress increment and vertical stress increment in floor，which lead to increase width of opening for roof and floor and resulted in roof fracture and serious floor heave.However，cable with high resistance and releasable pressure is used to effectively reduce the width of opening for roof and floor and restrain large deformation of floor.On this basis，the authors proposed a control method of bolt-mesh-cable-grouting with cable in floor.Finally，a supporting test was conducted in subinclined shaft，and the surrounding rock control effect was good.