冲击载荷下凝灰岩破坏特征及能耗规律分析

Failure and energy dissipation patterns of tuff under impact loads

  • 摘要: 针对大红山铜矿不同赋存条件凝灰岩在冲击载荷下的破坏特征与能量耗散规律,采用分离式霍普金森压杆(SHPB)冲击试验,结合数字图像相关(DIC)技术、分形维数、扫描电子显微镜及能谱仪(SEM-EDS)进行研究。研究结果表明:①相同应变率条件下,300水平岩样动态抗压强度仅为420水平岩样动态抗压强度的71 % ~77 %;②冲击载荷下,2组岩样均经历“均匀应变-局部集中-裂纹破碎”过程,冲击载荷相同时,300水平岩样裂纹更密集、扩展更迅速、应变峰值及破碎程度更高;③ 2组岩样破碎耗能密度均随冲击载荷增大呈线性增长,300水平岩样平均能量吸收效率为35.86 %,420水平岩样平均能量吸收效率19.29 %。研究结果揭示了矿岩微观结构与组成成分差异对其冲击载荷下动态力学特性的影响规律,可为动态载荷作用下矿岩稳定性分析与矿山安全开采提供理论支持。

     

    Abstract: This study investigates the failure and energy dissipation patterns of tuff under impact loads with varying occurrence conditions in Dahongshan Copper Mine through Split Hopkinson pressure bar (SHPB) tests, digital image correlation (DIC), fractal dimension analysis, scanning electron microscopy and energy dispersive spectroscopy (SEM-EDS). Results show that: ① At identical strain rate, the dynamic compressive strength of the 300-level tuff was only 71 % ~77 % of that from the 420-level tuff. ② Both types of specimens underwent a transition from uniform strain, local concentration to crack fragmentation. The 300-level tuff exhibited denser cracks, faster propagation, higher peak strain and higher degree of fragmentation under equivalent impact load. ③ While the crushing energy dissipation density of both types of specimens increased linearly with impact load, the 300-level tuff exhibited significantly higher average energy absorption efficiency (35.86 %) than the 420-level tuff (19.29 %). This study reveals how varying rock microstructures and composition affect the dynamic mechanical properties of ore and rock under impact load, providing theoretical implications for their stability analysis under dynamic load and safe mining.

     

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