Analysis of mechanical mechanism and influencing factors of directional fracturing of multi-hole sleeve
HU Shanchao;HAN Jinming;CHENG Yafei;QI Jiali;HUANG Junhong;GAO Zhihao;GUO Shihao;YANG Lei
坚硬顶板破断释放巨大冲击动能是诱发煤矿动力灾害的重要因素之一,在特定位置断顶实现岩层的定向断裂、减小坚硬顶板悬顶长度是防治煤岩动力灾害的关键。多孔套筒压裂技术具有操作简单、适用条件广泛等优点,在坚硬顶板弱化领域有着广泛的研究前景。为深入了解多孔套筒压裂机理,采用理论分析与数值模拟方法开展了多孔套筒压裂力学机制研究,揭示了不同影响因素下孔间应力变化规律,获得了压裂过程裂缝扩展规律及力链分布特征。通过钻孔切槽可提升套筒压裂预裂效果,为确定合理的布孔参数,基于线弹性断裂力学建立了含预制缝多孔套筒压裂力学模型,给出了缝端应力强度因子、临界膨胀力及裂缝临界起裂角计算方程,获得了不同影响因素下缝端应力强度因子、临界膨胀力及临界起裂角的变化规律。研究结果表明:① 侧压系数
The huge impact of kinetic energy released by the breaking of hard roof is one of the important factors that induces dynamic disasters in coal mines. The key to preventing and controlling coal and rock dynamic disasters is the directional fracture of strata at a specific position and reducing the length of hard roof suspension. The multi-hole sleeve fracturing technology has the advantages of simple operation and wide application conditions and has a wide research prospect in the field of hard roof weakening. In order to understand the mechanism of multi-hole sleeve fracturing, the mechanical mechanism of multi-hole sleeve fracturing was studied using theoretical analysis and numerical simulation. The variation law of inter-hole stress under different influencing factors was revealed, and the crack propagation law and force chain distribution characteristics in the fracturing process were obtained. The pre-cracking effect of sleeve fracturing can be improved by changing the drilling structure through grooving. In order to determine the reasonable hole arrangement parameters, a mechanical model of the multi-hole sleeve fracturing with prefabricated cracks was established based on linear elastic fracture mechanics. The calculation equations of stress intensity factor, critical expansion pressure, and critical crack initiation angle of cracks were given, and the variation rules of stress intensity factor, critical expansion pressure, and critical crack initiation angle of cracks under different influencing factors were obtained. The results show that: ① The lateral pressure coefficient
sleeve directional fracturing;stress distribution between holes;stress intensity factor;critical expansion pressure;initiation angle
主办单位:煤炭科学研究总院有限公司 中国煤炭学会学术期刊工作委员会