采场底板高承压水突水“三场”演化研究

"Three fields" evolution of water inrush process under high confined water in stope floor

采场底板承压水严重威胁着工作面的安全生产。通过理论分析建立了裂缝尖端力学模型,推导了裂缝力学平衡方程,分析了高承压水上工作面回采引发底板突水的裂缝扩展条件;利用RFPA软件模拟分析了承压水上工作面回采期间围岩应力场、损伤场与渗流场的演化过程,揭示了煤层底板承压水突水机制。研究结果表明:导水裂缝的扩展条件是孔隙水压力与地应力的合力大于煤岩体内部黏聚力;采矿活动改变了围岩应力场分布,造成局部应力集中,并引发煤岩体内部损伤破坏,大规模突水后主应力比裂纹开始扩展时显著增大;内部损伤增强了煤岩体的渗透性,增大了渗流场影响区域。

Mine confined water is a serious threat for the safety production of underground coal face. Through theoretical analysis, a mechanics model of crack tip was established, the equilibrium equation of fracture mechanics was deduced, and the crack propagation condition of floor water inrush caused by mining on high confined water were analyzed. In addition, evolution process of rock stress field, damage field and seepage field under mining were simulated by RFPA, and the mechanism of confined water inrush was further revealed. The results show that the propagation condition of water flowing crack is that the resultant force of pore water pressure and t in-situ stress should be greater than the internal cohesion of coal-rock mass. Surrounding rock stress distribution has been changed by mining activities, which also causes local stress concentration and damage within coal-rock mass. After a large-scale water inrush appears, the principal stress is significantly larger than that in crack initiation. Duo to internal damage, the permeability of coal-rock mass increases, and the affected area of seepage field also increases.