高应力下考虑结构面三维形貌特征的断裂滑移型岩爆机理与预测探究

Fault-slip rockbursts frequently occur during the excavation of deep rock mass, which can cause casualties and serious damage to the equipments. In this project, the mechanism and prediction of fault-slip rockburst under high geostress condition will be exhaustively studied. Firstly shear tests and acoustic emission (AE) monitoring will be carried out, and relationships between the peak shear strength, post-peak stress drop, the peak energy rate and normal stress, shear rate and three-dimensional morphology of joint surface will be obtained, and the shear failure characteristics and mechanism of joints with various three-dimensional topographic properties will be revealed. The damage evolution law of asperities will be inquired based on the located AE event, and mechanism and influencing factors of fault-slip rockburst induced by dynamic instability will be illustrated. A new peak shear strength model which can consider the brittle failure characteristics under high geostress and the three-dimensional morphology of joint will be proposed, and the numerical modeling method to predict fault-slip rockburst will be established, in which the new peak shear strength model acts as the criterion of fault reactivation. Correlations between the source parameters resulting from fault slip and burial depth, fault morphology and excavation rate will be evaluated using the prediction method. The research results of this project will have both theoretical and engineering significance in improving the prediction accuracy and prevention efficiency, as well as reducing losses caused by fault-slip bursts.

深部岩体开挖过程中断裂滑移型岩爆频发，极易造成设备损毁和人员伤亡。项目针对岩体开挖过程中亟待解决的断裂滑移型岩爆机理和预测问题，通过对硬岩结构面开展高法向应力的剪切试验和声发射测试，分别获得其峰值抗剪强度、应力跌落值和峰值能量释放率与法向压力、剪切速率和结构面三维形貌的内在联系，揭示高应力下具有不同三维形貌的结构面剪切破坏特征和机制；根据定位的声发射事件探究结构面起伏体的损伤演化规律，阐释结构面动力失稳诱发断裂滑移型岩爆的机理和影响因素。在试验的基础上，根据统计参数法给出节理峰值剪胀角表达式，建立综合考虑硬岩结构面高应力下脆性破坏特征和三维形貌参数的峰值剪切强度模型；以该模型作为结构面启滑判据，嵌入FLAC3D程序，构建断裂滑移型岩爆预测的数值分析方法，探索结构面断裂滑移的震源参数与埋深、结构面形貌等的相关性。研究成果对于揭示断裂滑移型岩爆机理、减少断裂滑移型岩爆造成的损失具有重意义。

深部矿山、深埋隧洞岩体中广泛存在结构面、断层等不连续地质构造，开挖作用后极易诱发断层活化导致断裂滑移型岩爆灾害，造成重大经济损失和人员伤亡。本项目通过制作粗糙的硬岩结构面，并且定量获得结构面的粗糙度参数，通过开展一系列的高应力下结构面的剪切试验，综合研究了法向压力、节理面形貌、岩石细观结构、充填物、剪切速率等对结构面滑移破坏的影响规律，并将研究成果用于阐释断裂滑移型岩爆的发生机制；系统分析了结构面峰值强度、残余强度、峰后应力降等随法向压力和剪切速率的变化特点；采用声发射技术，获得了结构面剪切过程中的声发射信号演化规律，定性和定量相结合分析了软、硬结构面起伏体的损伤演化特点、时空分布规律和对宏观力学特性的影响，建立了起伏体的损伤演化的概化模型和定量分析模型；并探讨了声发射b值预警断层错动失稳的有效性；研究了充填物种类对节理剪切力学特性和声发射信号的影响，并讨论了产生不同影响的内在机制；结合已有的试验数据和文章中的资料，综合分析了断层活化诱发地震、滑移型岩爆等过程中的幂函数规律。