含隐伏断层煤层底板承压水采动导升机制研究

Study on the mechanism of confined water mining lifting in coal seam floor with a hidden fault

根据裂隙岩体水力学分析了承压水导升运动过程中的水压变化与导升位置的变化规律,推导了二者之间的数学关系;通过分析底板采动应力场空间分布规律,构建含隐伏断层底板承压水导升力学模型,基于半无限体理论推导了采动影响在底板空间的应力传递规律表达式;结合断裂力学理论推导了矿山压力-水压力联合作用下的裂隙扩展的临界水压及承压水导升高度计算公式;采用单因素分析法对其影响因素进行了分析,并通过FLAC3D重点模拟分析了隐伏断层倾角对承压水采动导升规律的影响。研究结果表明:承压水导升高度受初始水压力、隐伏断层倾角增大而增大,而随着动水流速、岩体断裂韧度增加而减小;采动承压水导升高度还与其导升过程中的能量损失系数结构岩体的力学性质、原始地应力等相关联;模拟结果也表明受隐伏断层倾角影响,采动渗流场表现出随着隐伏断层倾角增大而导升强度越剧烈和强渗流区范围更大的现象。

According to the hydraulic mechanics of fractured rock mass,the variation law of water pressure and lifting position in the process of confined water lifting was analyzed,and the mathematical relationship between them was deduced.By analyzing the spatial distribution law of floor mining-induced stress field,the mechanical model of floor confined water with hidden fault was constructed,and the expression of stress transfer law of mining influence in floor space was deduced based on semi-infinite body theory.What’s more,the formulas for calculating the critical water pressure and the lifting height of confined water for fracture propagation under the combined action of mine pressure and water pressure were deduced based on the theory of fracture mechanics.The influencing factors were analyzed by single factor analysis method,and the influence of hidden fault dip on the mining lifting rule of confined water was simulated by FLAC3D.The results have shown that the lifting height of confined water increased with the increase of initial water pressure and hidden fault dip,while decreased with the increase of dynamic water velocity and fracture toughness of rock mass.The lifting height of mining-induced confined water was also related to its energy loss coefficients,mechanical properties of structural rock mass and original in-situ stress during the lifting process.It was also influenced by hidden fault dip that the guiding strength become more severe and the range of strong seepage zone became larger in mining seepage field with the increase of the hidden fault dip.