中文摘要：

针对华北型煤田采动变形破坏底板突水通道的形成机制问题，划分了4种底板隔水层岩体结构类型；分析了采动效应特征，研究了压剪破坏和拉张破坏两种岩体结构破坏形式；探讨了底板突水通道形成的断裂力学机制。结果表明：对于裂隙型底板岩体结构而言，底板突水说明隔水层中潜在突水通道转化为突水通道，即裂隙已经扩展贯通到采空区临空面；岩体结构变化是引起渗透率变化的根本原因。也是岩体丧失隔水性能的根本原因；应力集中区裂纹扩展属于压剪状态下的Ⅰ型裂纹扩展，而卸荷区裂纹扩展属于拉剪状态下Ⅰ-Ⅱ型复合裂纹扩展。

英文摘要：

Aiming at the water inrush channel formation mechanism in coal seam floor with mining-induced deformation and failure in North China, the floor water-resisting layer was divided into four types. The characteristics and effects of mining were analyzed, and two kinds of failure forms including shear failure and tensile failure were studied. Crack propagation angle and fracture criterion were obtained by the maximum circumferential tensile stress theory. The mechanism of fracture mechanics for channel formation of floor water bursting was discussed. The results show that： for fractured network type of floor water-resisting layer, floor water bursting indicates that the potential channel had changed to water inrush channel, which the crack has extended into the mined-out area. The changes of water-resisting layer permeability are caused by the changes of rock mass structure, which is also the primary cause of water-resisting property loss. The crack propagation belongs to I type fracture under compression-shear state in stress concentration zone, while that belongs to Ⅰ-Ⅱ type fracture under tension-shear state in unloading zone.