In situ leaching was a very important technical approach in ion-adsorption rare earth mining, because it can effectively avoid the geological hazards, protect the environment, and reduce the mining costs. The critical issue of this mining technique was to increase the permeability of ion-adsorption rare earth deposits. Due to the close relationship between the permeability and the porosity, in this paper, several experiments were conducted to find the dynamic characteristics of the granite deposit and the relationship between the dynamic characteristics and the porosity. Moreover, the SHPB test system was equipped to conduct the dynamic test, and the ultrasonic wave detector with high precision was employed to obtain the damage factor of granites. The test results showed that the failure mode under dynamic load and static load was close, and they both had splitting failure. Besides, when cyclic dynamic loading velocity was between 5.8 m/s and 8.4 m/s, the specimen was not a failure, but it caused the damage and changed the porosity. And the dynamic thresholds of failure stress and damage stress were found. Finally, a linear relationship between the porosity and the damage factor was found, which would help to analyze and predict the change of porosity under different dynamic loading velocities.

中文翻译：

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基于SHPB试验的浸出开采花岗岩动态损伤致孔隙度变化分析

原位浸出是离子吸附稀土开采中非常重要的技术手段，可以有效避免地质灾害，保护环境，降低开采成本。这种采矿技术的关键问题是提高离子吸附稀土矿床的渗透率。由于渗透率与孔隙度之间的关系密切，本文通过多次实验研究花岗岩矿床的动态特征以及动态特征与孔隙度的关系。并配备SHPB试验系统进行动态试验，采用高精度超声波检测仪获取花岗岩的损伤系数。试验结果表明，动载荷和静载荷下的失效模式接近，他们都分裂失败了。此外，当循环动态加载速度在 5.8 m/s 到 8.4 m/s 之间时，试件不是破坏，而是造成损坏并改变孔隙率。并求出破坏应力和损伤应力的动态阈值。最后，发现孔隙率与损伤因子之间存在线性关系，有助于分析和预测不同动加载速度下孔隙率的变化。