煤层底板破坏机理分析及最大破坏深度计算

摘要

To further understand the failure mechanism of coal seam floor, the stress and location of the critical failure of the coal seam floor were determined by using the semi-infinite body theory. Based on this, the formula of maximum breakage depth of coal seam floor was derived by using the slip line field theory of the plastic mechanics, the relationship between the maximum breakage depth of the coal seam floor and its affecting factors was analyzed, and the rationality of the calculation formula was illustrated by the examples. The results showed that the maximum breakage depth of the coal seam floor increased with the increase of the internal friction angle of the floor rock and decreased with the increase of the cohesion of the floor rock in a fixed scope of the plastic zone of coal wall. The maximum breakage depth of coal seam floor was not only related to the scope of the plastic zone of the coal body at the end of the stope, but also increased with the increase of the peak value of the leading support pressure.%为进一步认识底板破坏机理，运用半无限体理论计算了致使底板临界破坏的应力及位置，结合塑性力学的滑移线场理论推导出底板最大破坏深度计算公式，分析了底板最大破坏深度及其相关影响因素的关系，并通过算例分析说明了计算公式的合理性。结果表明：在煤壁塑性区范围一定的情况下，底板最大破坏深度随着底板岩石内摩擦角的增大而增大，随着底板岩石黏聚力的增大而减小。底板最大破坏深度不仅与采场端部煤体塑性区范围有关，而且随着工作面超前支承压力峰值的增大而增大。