含铜矽卡岩在高应力卸荷过程中受冲击扰动时的损伤破坏机理研究

It is because that the consumption of resources caused shallow copper resources tends to be exhausted in our country, so more and more copper mines will go deeper than one kilometer. In order to safely and efficiently exploit deep copper resources, it is urgent to master the dynamic mechanical characteristics and failure law of deep copper-bearing rock mass under impact disturbance in high static load and unloading process. In this project, the impact dynamics tests will be carried out around the damage characteristics of deep reserved ore pillars, which have different copper content and were affected by frequent blasting excavation disturbance under high stress conditions. In the experiment, the different density of rock samples can indicate the different copper content, “the preload high axial compression, high axial compression dropped loading on a certain rate and the repeated impact” can be used to simulate “the high ground stress, excavation unloading, frequent blasting disturbance”, respectively. Through this test, the influence of "copper content, high stress, unloading process, impact disturbance" on the damage and failure characteristics of deep rock mass can be found. Then, the critical condition of macroscopic failure of deep copper-bearing rock mass can be determined by analyzing the quantitative relationship between the above factors and rock dynamic characteristic parameters, damage and failure process. Finally, the dynamic constitutive model of deep copper-bearing rock mass under impact disturbance in high static load and unloading process will be established, which can reveal the damage and failure mechanism of deep copper-bearing rock mass during excavation. The research results can provide the theoretical basis for deep copper mining, goaf stability control, dynamic disaster prevention and so on.

我国浅部铜矿资源消耗趋于殆尽，超过千米的深部铜矿井越来越多。为安全、高效开采深部铜矿资源，急需掌握深部含铜岩体在高应力卸荷过程中受冲击扰动时的动力学特性及破坏规律。本项目围绕深部不同含铜量的预留矿柱在高应力条件下受频繁爆破开挖扰动时的损伤特性，用岩样密度差异表征不同含铜量、“预加载高轴压”模拟深部岩体承受的“高应力”、“一定卸荷速率卸载高轴压”模拟“开挖卸荷”、“多次冲击荷载”模拟“频繁爆破扰动”的方法开展冲击动力学试验，探索“含铜量、高应力、卸荷过程、冲击扰动”各因素对深部岩体损伤破坏特征的影响；接着，通过分析上述因素与岩石动力学特征参数、损伤破坏过程之间的定量关系，判定深部含铜岩体发生宏观破坏的临界条件；最后，建立多因素条件下深部含铜岩体的动态本构模型，揭示开挖过程中深部含铜岩体的损伤破坏机理。研究成果可为深部铜矿资源开采、采空区稳定性控制、动力灾害事故预防等提供理论依据。

项目以深部矿产资源开采为工程背景，以提高开采效率和安全性为目的，将含铜矽卡岩作为主要的研究对象，采用动力学实验、理论分析、工程验证相结合的方法，研究了高应力卸荷过程中受冲击扰动时深部岩石的动力学特性，揭示了“含铜量、高应力、卸荷过程、冲击扰动”四因素对深部岩体损伤破坏机理的影响，建立了相应条件下岩石的动态损伤本构模型。首先，以含铜矽卡岩静力学特征为基础开展高静载卸荷过程中受冲击扰动时含铜矽卡岩的动力学实验，建立了岩石动力学特征参数与四因素之间的定量关系；随后，研究岩样的动态损伤历程、破碎岩块形态及内部结构特征，分析出岩样受四因素影响的破坏模式，揭示了高应力卸荷过程中岩石受冲击扰动时的破坏机理；最后，在一定假设条件下，采用组合模型法建立了四因素制约下深部岩石的动态损伤本构模型。历经三年的研究，项目负责人以第一作者发表论文10篇，其中SCI收录7篇、EI收录3篇，授权发明专利2项，实用新型专利3项，取得的主要成果如下：1）岩石的动态应力—应变曲线未出现回弹现象，初始阶段为短暂直线段，随后进入非线性发展阶段，整体变化趋势不受卸载速率、含铜量的影响；2）随扰动冲击次数的增加，岩石的动态峰值应力和动态变形模量减小，动态峰值应变增大，并拟合得出其与四因素之间的定量关系式；3）裂纹萌发于岩样入射端，且沿应力波传播方向扩展，导致岩样最终以拉伸破坏为主，且破坏模式受四因素影响较小；4）定义并推演了高静载卸荷频繁冲击条件下岩石的损伤变量，获取了损伤变量方程中各参数的确定方法和岩石的损伤演化规律，也从定量分析角度揭示了岩样的损伤破坏机理；5）建立了高静载卸荷频繁冲击条件下和加卸荷后分级动载扰动时含铜矽卡岩的本构模型，实现了四因素影响下岩石变形规律的定量预测。项目研究成果不仅为深部采矿破岩、围岩稳定性控制、工程灾害预警提供了基础理论支撑，也对提高深部岩体工程作业效率、安全性具有重要的科学意义。