矩形断面巷道冲击地压机理研究

基于顶板剪切梁模型研究矩形巷道冲击地压发生问题,得到矩形断面巷道发生冲击地压的临界塑性软化区深度和临界载荷,分析巷道宽度、巷道高度或煤层厚度、顶板厚度等几何因素,以及煤层与顶板刚度比、煤的模量比、煤的强度参数、侧压力系数和水平应力分布指数等煤岩力学性质因素对临界条件的影响规律。结果表明:巷道顶板岩层以剪切变形破坏为主,当临界塑性区深度与临界载荷较小时,易于发生冲击地压,其发生频度较高,强度较小,破坏性较小;反之,冲击地压不易发生,其发生频度较低,一旦发生其强度会较大,破坏性较大。临界塑性区深度与巷道宽高比、初始黏聚力的大小无关,随顶板厚度、刚度比、模量比、水平应力分布指数的增加而增大,随煤层塑性软化刚度、内摩擦角、侧压力系数的增加而减小。临界载荷随巷道宽高比、煤层塑性软化刚度、水平应力分布指数的增加而降低,随顶板厚度、刚度比、模量比、初始黏聚力、内摩擦角、侧压力系数的增加而增大。

Mechanism of rock burst in rectangular section roadway

The critical plastic softening zone depth and the critical load of rock bursts in a rectangular section tunnel are obtained based on the roof shear beam model for rock burst problem of roadway, and the effects of correlation factors on the critical conditions are investigated. The results show that the damage of roof rock strata is dominated by the shear deformation, and the critical depth and the critical load of the plastic zone are important parameters for identifying risk impact. Rock burst will easily happen if the critical depth and the critical load of the plastic zone are small. Its occurrence frequency is higher, but its intensity is smaller, and the destruction is also small. When they are large enough, the opposite situations occur. The influence factors of rectangular section in roadways include roadway width, height or thickness of coal seam, thickness of roof, stiffness ratio of coal seam and roof, modulus, intensity parameter, lateral pressure coefficient and horizontal stress distribution index. The critical depth of the plastic zone increases a little with the height-width ratio of roadway, and it increases with the increase of the thickness of the roof, stiffness ratio and horizontal stress distribution index. It decreases with the increasing plastic stiffness softening, internal friction angle and lateral pressure coefficient, and it has nothing to do with the initial magnitude of the cohesive force. The critical load decreases with the height-width ratio of roadway and it increases with the increase of the thickness of the roof, stiffness ratio, modulus ratio, cohesive force, internal friction angle and lateral pressure coefficient. It decreasess with the increasing plastic stiffness softening and horizontal stress distribution index.