支承压力区煤体裂隙演化区域性研究

Study of crack propagation by partition of the abutment pressure area in underground mine

为了研究支承压力区内煤岩体裂隙的演化规律,建立了原生裂隙扩展的力学模型,得出了裂隙的扩展过程及其力学条件.结果表明:煤体原生裂隙经历了剪切滑移—Ⅱ型扩展—弯折扩展—剪切扩展—剪切破坏—反向滑移的过程;同时,在现场对工作面前方不同距离处煤层取样,并对取样切片进行显微照相,切片的裂隙特征反映了支承压力区内的裂隙特征,现场观测和理论研究结果基本一致.基于以上分析,按照煤体裂隙发育特征,将支承压力区分为初始裂隙区、剪切滑移与Ⅱ型裂隙扩展区、裂隙弯折扩展区、裂隙剪切扩展区、剪切破坏区和裂隙反向滑移区,并结合支承压力表达式和裂隙扩展的力学条件,量化得出了各区域范围的表达式.

To make clear the law that governs crack propagation in the abutment pressure area in front of the working face,mechanical model of crack propagation was established and the process of crack propagation and its mechanical condition were proposed.The results show that the original crack experiences the process of shear slip—modeⅡpropagation—bending propagation—shear propagation—shear failure—reverse slip.Plus,coal samples from different distances in front of the working face were taken from a underground mine.These samples were sliced for microphtography which could reflect the crack property in the abutment pressure area.The observation in the field are consistent with the theoretical analysis.Based on the results above,the abutment pressure area can be divided into 6zones:original crack area,shear slip and modeⅡpropagation area,bending propagation area,shear propagation area,shear failure area and reverse slip area.Cracks propagate in different modes in these areas.Also,the range of these areas are determined by combining the formula of abutment pressure with the mechanical condition of crack propagation.