冲击载荷作用下锚固围岩损伤破坏机制

为研究冲击地压巷道锚固围岩损伤破坏特征,以实际发生冲击失稳的巷道为例,分析了冲击载荷作用下锚固围岩动载响应特征,现场测试了冲击载荷作用后围岩损伤、锚固界面损伤及锚固性能,对比分析了冲击载荷前后锚杆力学性能。研究结果表明:冲击载荷作用下,巷道锚固围岩和锚杆与锚索受反复压拉压作用,导致锚固系统锚固性能降低与失效;冲击载荷作用后,巷道围岩节理、裂隙发育,完整性差且强度大幅降低,锚固性能劣化或失效;锚杆支护材料性能降低,杆体延伸率降低13. 8%,抗拉强度降低6. 6%,冲击吸收功降低24. 3%,锚杆产生塑性变形,晶粒扭曲、畸变,微观金相组织紊乱。采用锚固注浆、高预应力全长锚固以及高强度、高伸长率、高冲击韧性锚杆与锚索联合支护,可以有效提高冲击载荷作用下巷道围岩的稳定性。

Damage and failure mechanism of anchored surrounding rock with impact loading

In order to study the damage and failure characteristics of anchored surrounding rock in rock burst roadway,the dynamic response characteristic of anchored surrounding rock under impact loading was analyzed.The damage of surrounding rock and anchorage interface were tested and the mechanical properties of the bolt before and after the impact load were compared through the site tests.The results show that the anchorage performance reduction and failure were induced by repeated tension and extrusion under impact stress wave.After impact loading,the strength and integrity of roadway surrounding rock decreased sharply with a mount of internal fractures’development,then,the anchored performance of bolt system became invalid eventually.The performance of bolt supporting material was reduced,and the reduction of rod elongation reached 13.8%,tensile strength decreased 6.6%,impact absorbing energy decreased 24.3%,plastic deformation and grain distortion occurred,and micro metallographic organization disordered.The comprehensive supporting method,including anchor grouting,full size grouted,bolt and anchor combined support with high strength,high elongation,and high impact toughness,can ensure the surrounding rock stability under impact loading.