Superposed disturbance mechanism of sequential overlying strata collapse for gob-side entry retaining and corresponding control strategies

覆岩分次垮落对沿空留巷的叠加扰动机理及其控制对策（英文）

Gob-area roof rupture movement is a key disturbance factor for gob-side entry retaining.The characteristics of gob-area sequential roof collapse of overlying strata and superposed disturbance mechanism for gob-side entry retaining are obtained via physical simulation and theoretical analysis,in which the scope of disturbed strata is enlarged from main roof to fracture zone.The experiment reveals that as a working face advances,roof strata sequentially collapse from bottom to top and produce multiple disturbances to gob-side entry retaining.Key strata among the overlying strata control each collapse.Main roof subsidence is divided into three stages:flexure subsidence prior to rupture,rotational subsidence during rupture and compressive subsidence after rupture.The amounts of deformation evident in each of the three stages are 15%,55%and 30%,respectively.After the master stratum collapses,main roof subsidence approaches its maximum value.The final span of the key stratum determines the moment and cycling of gob-side entry retaining disturbances.Main roof subsidence influences the load on the filling wall.The sequential roof collapse of overlying strata results in fluctuations in the gob-side entry retaining deformation.Calculation formulae for the final span of the key stratum and the filling wall load are obtained via theoretical analysis.A control method for the stability of the gob-side entry retaining’s surrounding rock is proposed,which includes 3 measures:a“dual-layer”proactive anchorage support,roadside filling with dynamic strength matching and auxiliary support during disturbance.Finally,the gob-side entry retaining of the Xiaoqing mine E1403 working face is presented as an engineering case capable of verifying the validity of the research conclusions.

采空区顶板断裂运动是沿空留巷的关键扰动因素。本文阐述了采空区覆岩的分次垮落特征及其对沿空留巷的叠加扰动机理,将扰动岩层由过去的老顶扩大到了裂隙带。物理模拟实验揭示,顶板各岩层随着工作面的推进而由下向上依次垮落,并对沿空留巷造成多次扰动。覆岩中的各个关键层控制着每一次垮落,其中老顶下沉分为断裂前的挠曲下沉、断裂时的旋转下沉以及断裂后的压缩下沉三个阶段,实验中三部分变形量分别占15%,55%和30%,主控关键层垮落后老顶接近最大下沉值。关键层的极限跨距决定着沿空留巷的扰动时机和扰动周期,老顶下沉量影响着充填墙体的载荷大小,覆岩的分次垮落则使沿空留巷呈现出波动性变形。采用理论分析,得到了关键层极限跨距和充填墙体载荷的计算方法。提出了沿空留巷围岩稳定性控制技术,包括"双层"主动锚固支护、强度动态匹配的巷旁充填以及扰动期间的辅助支护3项。最后结合小青矿E1403工作面沿空留巷的工程案例,验证了研究结论的合理性。