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弱面对水压裂隙的扩展有着重要影响,为达到有效控制坚硬难跨顶板,需要研究人为弱面对水力压裂的影响。根据水压裂隙产生及扩展机理,运用数值模拟试验方法,通过声发射及剪应力分布研究了3种人为弱面影响下的水力压裂过程中裂隙扩展特征,对比分析了7种压裂方式下的水力压裂数据。结果表明:预制裂隙开挖形成的层理弱面和监测孔开挖形成的应力卸压圈均能影响水压裂隙的扩展,在扩展方向上水压裂隙往往偏向于高孔隙水压力的区域扩展,且其在扩展一段之后受顶板自由面影响,主裂隙向工作面两端延伸4.5~8.5倍孔径的区域时会发生近90°的空间转向。水力压裂数据研究表明,预制裂隙和监测孔协同作用强化了控制坚硬难垮顶板的效果。
Weak face has an important influence on the expansion of hydraulic fractures. In order to effectively control hard and hard roof, it is necessary to study the effect of artificial weak face on hydraulic fracturing. According to the mechanism of hydraulic fissure generation and propagation, numerical simulation tests were used to study the characteristics of fissure propagation during hydraulic fracturing under the influence of three man-made weak planes through acoustic emission and shear stress distribution. Hydraulic fracturing data. The results show that both the stratified weak face formed by prefabricated excavation and the stress relief ring formed by excavation of monitoring hole can affect the expansion of hydraulic fractures. In the expansion direction, the hydraulic fractures tend to extend to areas with high pore water pressure , And it is affected by the free surface of the roof after a period of expansion. Nearly 90 ° of space deflection occurs when the main cracks extend 4.5 to 8.5 times the diameter of the working surface at both ends. Hydraulic fracture data studies show that the combined effect of prefabricated fractures and monitoring holes enhances the effectiveness of controlling hard and inhospitable roofing.