【摘要】 针对巨厚覆岩层导致采场矿山压力大，矿压显现明显的问题，采用数值模拟和相似实验方法，分析了不同回采阶段巨厚覆岩层内各关键岩层采动应力场分布特征，对比研究了正常回采和预制裂隙回采条件下采场巨厚覆岩层破断运移特征，提出了基于定向钻孔的采动应力场下巨厚覆岩层分区水压致裂关键技术。研究表明：回采期间，受采动支承压力影响，巨厚覆岩层内垂直应力逐渐超过水平应力；在巨厚覆岩层应力集中区和原岩应力区进行水压致裂能够分别制造竖直和水平水力裂隙；预制裂隙能够改变巨厚覆岩层破断形式，增加上覆岩层垮落高度。工程实践表明，采动应力场下巨厚覆岩层分区水压致裂能够有效减小工作面来压步距，降低工作面支架阻力，为工作面安全生产提供保障。更多还原

【Abstract】 To address the problem of high mining pressure and pronounced rock pressure manifestations caused by the extra-thick overburden, this study adopted numerical simulations and similar experiments to investigate the distribution characteristics of the mining stress field within the extra-thick overburden at different mining stages and comparatively analyze the fracture and migration characteristics of the extra-thick overburden under normal mining conditions and prefabricated fracture conditions. At last, a key technology for zonal hydraulic fracturing in the extra-thick overburden affected by the mining stress field based on directional drilling was proposed. The following research findings were obtained: During mining, the vertical stress within the extra-thick overburden gradually exceeds the horizontal stress due to the influence of mining abutment pressure. Vertical and horizontal hydraulic fractures can be created by conducting hydraulic fracturing in the stress concentration zone and the original rock stress zone of the extra-thick overburden, respectively. Prefabricated fractures can change the breakage mode of the extra-thick overburden and increase its caving height. Field applications demonstrate that the key technology of zonal hydraulic fracturing in the extra-thick overburden affected by the mining stress field is capable of effectively shortening the weighting step distance of the working face and reducing the support resistance there, thus providing safe production conditions.更多还原