软弱再生顶板巷道围岩失稳机理及其控制原理与技术

针对软弱再生顶板巷道围岩大变形问题,结合现场调研、室内试验、理论分析等手段研究了软弱再生顶板围岩失稳机理,并提出了针对该类围岩的控制原理、支护原则和支护技术。研究表明:软弱再生顶板具有自稳平衡拱结构,但极其不稳定。在扰动作用下快速松散、破碎,表现出局部到整体的连锁失稳特征。基于再生顶板围岩条件提出再生顶板"抛物线-半双曲线"扩展力学模型,即再生顶板平衡拱边界在纵向上以"抛物线"形式向上扩展,横向上以"半双曲线"形式延伸。巷道底臌使得两帮整体下沉或两帮肩角处破坏造成再生顶板自稳平衡拱结构不断地向围岩深部转移。根据该模型计算发现,此时棚架上的载荷增加更快。再生顶板松散范围的非线性增加使得棚架上的荷载急剧增加,围岩变形量增大,最终导致巷道整体失稳。因此,提出了"护底→固帮→控顶"的软弱再生顶板围岩控制基本原理。结合州景煤矿再生顶板巷道实际情况,通过疏干排水防止底臌、改善棚架结构加强帮、顶支撑,形成了"强化整体约束、优化棚架结构和架间协同控制"的支护原则,具体形成了"双层金属网+预支撑囧型棚架+可缩性纵向连接器"的组合支护技术,经工程试验表明该支护技术可有效控制软弱再生顶板巷道围岩初期的稳定,后期回采时建议采用"三支一体"支护体系进行加强支护,控制再生顶板围岩回采期间的稳定。

Control principle and technology and instability mechanism of sur rounding rock in weak regenerated roof

In terms of the large deformation problem of surrounding rock in soft weak regenerated roof roadway,the instability mechanism of surrounding rock of soft weak regenerated roof is studied by means of on site investigation,laboratory test and theoretical analysis,and the control principle,support principle and technology for this kind of surrounding rock are put forward.The research shows that the soft weak regenerated roof has self stabilizing balance arch structure,but it is extremely unstable.Under the action of disturbance,it is loosened and fragmented rapidly,showing the characteristics of local to global instability.Based on the surrounding rock condition of the regenerated roof,an extended mechanics model of “parabola semi hyperbola” for the regenerated roof is proposed,that is,the balance arch boundary of the regenerated roof expands upward in the form of “parabola” in the longitudinal direction and extends in the form of “semi hyperbola” in the transverse direction.According to the calculation of the model,it is found that the load on the scaffolds increases faster when the self stabilizing balance arch structure of the regenerated roof continuously transfers to the deep surrounding rock due to the floor heave of the roadway,which makes the two sides sink as a whole or the corner of the shoulder of the two ribs be destroyed.The non linear increase of the loose range of the regenerated roof makes the load on the scaffolds increase sharply and the deformation of surrounding rock increase,which ultimately leads to the overall instability of the roadway.Therefore,the basic principle of surrounding rock control of soft weak regenerated roof of the “protective bottom→solid ribs→control top” is proposed.Combined with the actual situation of regenerated roof roadway in Zhoujing Coal Mine,the floor heave is prevented by drainage,and the scaffold structure is improved to strengthen the support of ribs and roof.The supporting principles of “strengthening the overall restraint,optimizing the scaffold structure and coordinated control between scaffolds” was formed.Then,the combined support technology of “double layer metal mesh+pre supported truss scaffold+shrinkable longitudinal connector” has been formed.The engineering test shows that the support technology can effectively control the initial stability of surrounding rock in soft weak regenerated roof roadway.In the later mining operation,it is recommended to use the “three in one” support system to strengthen the support and control the stability of surrounding rock.