综放采场周期来压阶段顶板结构稳定性与顶煤放出率的关系

STUDY ON RELATIONSHIP BETWEEN ROOF STABILITY AND TOP COAL'S RECOVERY RATIO DURING CYCLIC WEIGHTING IN FULLY-MECHANIZED SUBLEVEL CAVING FACE

综放采场周期来压阶段,顶煤从垮落到放完是一个动态过程,采空区的充填程度影响着大厚度坚硬顶板的稳定性,因此,建立与顶煤放出率相关的顶板结构的稳定性判断准则是一个重要的理论课题。根据结构稳定理论和强度理论,分析了保持顶板结构整体变形稳定和岩块局部铰接稳定的顶板容许下沉量,通过与顶板回转下沉运动几何状态所决定的顶板下沉量的对比,得到了顶板结构整体变形稳定和岩块局部铰接稳定相统一的力学条件,从而建立与顶煤放出率相关的综放采场顶板动态稳定性判断准则;结合采场实例,给出了与顶煤放出率相关的综放采场顶板稳定性判断曲线和方法,为现场针对不同顶板设计合理的顶煤放出率、实现顶板的安全控制提供理论依据。

During cyclic weighting in fully-mechanized sublevel caving face, the stowing degree of the goaf influences the stability of hard and massive overlying roof. The course of top coal falling from begin to end is dynamic. To set up the judgment rules of roof stability with the top coal＇s recovery ratio is an important theoretical problem. The mechanical model of the stability of the whole roof deformation and the part contact of the main roof is established. Based on the structure stability theory and the strength theory, two kinds of limited subsidence maintaining the stability of the whole deformation of roof structure and the stability of part contact of the main roof are gained. According to the comparison of the limited subsidence and the subsidence of roof brought about by the movement situation of roof in the course of rotation： the unified mechanical conditions between the stability of the whole transmutation of roof structure and the stability of part contact of the main roof are analyzed; and the judgment rules of roof stability with the top coal＇s recovery ratio are established. Based on an example of fully-mechanized sublevel caving face, the judgment figure and method with the top coal＇s recovery ratio are put forward; the theoretical bases of designing the safe top coal＇s recovery ratio are provided according to different roofs, and the safe roof controlling is achieved at coal mine.