钻孔回填试样力学特性及能量耗散特征研究

Mechanical properties and energy dissipation of samples with holes and backfilling

  • 摘要: 为解决大直径钻孔卸压与巷道围岩弱化相冲突的问题,以具有强冲击倾向性的煤岩相似材料为对象,研究单轴压缩条件下大直径钻孔对冲击倾向性试样强度的影响,采用PFC2D软件分析大直径钻孔和充填耦合作用对细观裂隙扩展和能量耗散的影响。结果表明:(1)随钻孔直径的增大,试样峰值强度的弱化效果越来越明显,而充填作用下试样峰值强度明显提升; (2)钻孔直径的增大有利于抑制裂隙的无序扩展,充填体强度的增大有利于裂隙向充填体与试样之间的边界扩展; (3)充填钻孔试样的释能效果与充填体强度呈正相关,大直径高强度充填可在满足卸压的前提下提高围岩的承载能力。

     

    Abstract: This study addresses the conflict between pressure relief of large diameter borehole and weakening of roadway surrounding rock. Taking similar materials with strong impulse tendency as the research object, this study investigated the effect of large-diameter drilling on the strength of sample with impulse tendency under uniaxial compression. We analyzed the effects of large-diameter drilling and packing coupling on fracture propagation and energy dissipation by using PFC2D software. Results show that: (1) the peak strength of the sample exhibited more explicit weakening effect with the increase of the diameter of the drilling hole, and the peak strength of the sample was significantly higher under the action of filling; (2) The increase of borehole diameter was conducive to inhibiting the disorderly expansion of cracks. With the increase of backfill strength, the interaction between backfill and sample matrix was conducive to controlling the expansion of cracks towards the boundary between backfill andsample; (3) The energy release effect of the filling borehole sample was positively correlated with the strength of the filling body. Large-diameter and high-strength filling could improve the bearing capacity of surrounding rock under the premise of satisfying the pressure relief.

     

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