高寒冻融区露天矿岩质边坡裂隙网络扩展行为多尺度时变演化机制

There are abundant mineral resources in the alpine region of western China. With the increasing of the exploitation of mineral resources in the western alpine region, the geotechnical engineering problems in many alpine regions are becoming increasingly prominent, and the current research on these problems is relatively weak. At present, the stability of open-pits rock slopes in alpine cold freezing–thawing regions is the typical problem. Therefore, this program focuses on the multi-scale study on time-varying evolution mechanism for fracture network propagation behavior of open-pits rock slope in alpine cold freezing–thawing regions. By the method of laboratory experiments, field microseismic monitoring, and combining macro and microstruct, and through the technology of multi-interdisciplinary, theoretical analyses and multi-scale calculation, the meso-damage evolution law of rock mass under the interaction of multi-field and multi-factor coupling will be analyzed. With the time-varying mechanics theory, the time-varying mechanism of crack propagation in multi-scale fractured rock mass under the condition of freezing-thawing cycle will be obtained. On the basis of field microseismic monitoring, the correlation mechanism between crack propagation and microseismic events of slope rock mass under the condition of freezing- thawing cycle will be revealed. Based on the research above, a new method of slope stability analysis, evaluation, early warning and disaster control will be proposed.

我国西部高寒地区蕴藏着丰富的矿产资源，随着西部高寒地区资源开发强度的逐渐加大，众多寒区岩土工程问题也日益突出，目前对这方面的研究比较薄弱，其中，高寒冻融区露天矿岩质边坡工程稳定性就是目前面临的典型难题。基于此，本研究开展高寒冻融区露天矿边坡岩体裂隙网络扩展行为的多尺度时变演化规律研究，拟采用室内试验、宏观与微观结合和现场微震监测等综合研究方法，通过多学科交叉、理论分析和多尺度数值计算等手段，研究冻融循环多场多因素耦合作用下岩体的细观损伤演化规律；采用时变力学理论，研究分析冻融循环作用下多尺度裂隙岩体裂纹扩展的时变机制；在现场微震监测的基础上，揭示冻融循环作用下边坡岩体裂隙网络扩展行为与微震事件间的关联机制；提出冻融循环作用下露天矿岩质体边坡稳定性分析、评价、预警与控制新方法。

寒区露天矿岩质边坡工程稳定性对矿山安全生产起着至关重要的作用。而寒区昼夜和季节温差引起的冻融循环过程是寒区岩体工程破坏与失稳的最重要原因之一。冻融循环过程中岩石物理力学特性的变化亦是研究寒区边坡工程稳定性的关键。本研究采用理论分析、室内试验、数值模拟方法开展了高寒冻融区露天矿边坡岩体裂隙网络扩展行为的多尺度时变演化规律研究。主要研究内容有：通过对冻融循环前后的青砂岩开展低场核磁共振测试和纵波波速测试，得出了冻融循环作用下青砂岩的细观损伤演化特征。采用NMR、MRI技术开展了红砂岩冻融损伤特征研究，揭示了红砂岩在特定冻融循环次数下的孔隙度减小机理。对冻融循环处理后的岩石力学特性和红外辐射特性进行了试验研究，提出了红外辐射速率指标。该指标可用于测量UCS试验过程中红外辐射温度随应力增加的上升速率，并对边坡失稳预警具有重要意义。考虑微观、宏观损伤，开展了缺陷岩体冻融损伤演化规律研究。考虑不同加载速率及循环初始峰值，开展了岩石在不同加卸载路径下的声发射演化特征。利用数值模拟及人工智能算法开展了寒区边坡稳定性研究与评价，并提供了边坡加固及灾害防治措施。