基于断裂力学倾斜煤层底板采动破坏深度研究

Study on coal-mining failure depth of the inclined coal seam floor based on fracture mechanics

为掌握倾斜煤层开采后采空区底板破坏情况,基于断裂力学理论,构建倾斜煤层采后空间底板应力求解力学模型,结合应力场与双剪强度理论,推导底板采动破坏深度求解公式,并应用实例进行验证.依据求解公式分析了底板破坏形态及影响因素,结果表明:倾斜煤层底板采动破坏区域分布具有非对称性特征;破坏范围及深度主要受工作面赋存状态和底板岩性影响,其中破坏深度与工作面斜长、采深和底板内摩擦角正相关,与底板黏聚力呈反比;随着倾角的增大破坏深度呈现先升后降趋势,而随着测压系数的增大破坏深度呈现先降后升趋势.该文研究成果可为倾斜煤层承压水防治、邻近煤层开采提供一定的理论指导.

In order to grasp the goaf floor failure condition after the inclined coal seam mining,the stress solving mechanics mode of the inclined coal goaf floor was set up based on the fracture mechanics theories.Combined the stress field and twin shear strength theory,the floor failure depth solving equation was derived and the equation rationality was verified through examples.According to the solving equation,the failure modes and influencing factors of the goaf floor were analyzed.The findings include:the distribution of the coal-mining failure zone of the inclined coal seam had asymmetry characteristic.The failure range and depth of the floor were mainly affected by the occurrence state of the working face and the lithology of the floor.The failure depth was positively correlated with the working face inclined length、mining depth and internal friction angle of the floor,and inversely proportional to the cohesion of the floor.With the increase of inclination Angle,the failure depth tended to rise first and then fall,but with the increase of lateral pressure,the failure depth tended to fall first and then rise.These findings can provide some theoretical directions for controlling confined water and properly designing floor roadway position.