渗流-应力耦合作用下深部巷道围岩流变特性与时效破裂演化机理研究

The deep coal mining under complicated hydro-mechanical conditions frequently brings about the serious problems of time-dependent deformation and failure of surrounding rock of deep roadways. Based on the multidisciplinary theories of mining rock mechanics, hydrogeology, percolation mechanics, rock rheology and nonlinear dynamics, a set of physical experiments including loading-unloading rheological test of rocks under different stress paths coupled by pore pressure, permeability tests, acoustic emission monitoring tests, SEM scanning and CT scanning tests are proposed to investigate the characteristics of time-dependent deformation, damage and permeability of rocks and the mechanisms of fracturing at microscale in rocks. Then, following the experimental observations, a coupled time-dependent microcrack-based damage and flow model is suggested and a nonlinear multi-scale numerical method is put forward to model the time-dependent fracturing process of rocks under hydro-mechanical loading. Finally, using the combined approaches of theoretical analysis, numerical simulations and field tests, this project plans to explore the evolution of time-dependent deformation, damage development, fracture patterns and groundwater flow and to reveal the mechanisms of non-linearly time-dependent deformation and failure of surrounding rocks of deep roadways under varying geological environmental conditions, and a new approach is developed to evaluate and control the long-term stability of deep roadways. The anticipated outcome of this project would provide theoretical reference for solving the issue of strata control and disaster assessment of deep roadways under complicated hydro-mechanical conditions and for safely and effectively mining of deep coal resource.

针对当前煤矿深部开采中复杂水-力耦合环境下巷道围岩剧烈流变大变形与破裂失稳问题，以矿山岩体力学、水文地质学、渗流力学、岩石流变学等多学科理论为指导，通过开展一系列不同应力路径与孔隙水压联合作用下岩石三轴加卸载流变试验、渗透性试验、声发射监测及细观电镜扫描和CT扫描试验等，揭示渗流-应力耦合长期作用下岩石时效变形、损伤与渗透性演化特征及细观破坏机制，建立基于微裂纹演化的岩石渗流-应力耦合细观流变损伤本构模型，研发渗流-应力耦合作用下岩石流变破裂全过程分析的多尺度非线性数值模拟方法及软件，系统研究不同工程地质环境因素影响下深部富水巷道围岩流变变形、损伤发展、破坏形态和渗流运移的时空演化规律，揭示围岩非线性流变特征与时效破裂失稳机理，提出深部富水巷道长期稳定性预测评价方法及控制原理和对策，为解决我国深部富水巷道围岩控制及灾害防治难题，实现深部煤炭资源安全高效开采提供理论基础。

目前，我国东部地区及部分中西部矿区(如河南、贵州等)的深部开采已成为常态，平均采深已达800~1000m。深部矿井受高渗透水压和高应力耦合环境的影响，巷道围岩剧烈流变大变形破坏及由此带来的巷道长期稳定性问题越发严峻，严重制约了深部煤炭资源的安全高效开采。因此，开展多物理场(渗流-应力-损伤-时间)耦合作用下深部岩体时效破裂特征、围岩流变大变形破坏和控制机理等相关研究，对保障深部煤炭资源安全高效开采、降低巷道维护成本具有重要的意义。.本课题以深部富水巷道围岩流变破裂及控制为研究目标，综合运用室内试验、理论分析、数值模拟和现场监测相结合的方法，首先，对岩石细观结构参数和宏观基本力学参数进行了分析，开展了不同渗透水压和围压条件下的岩样三轴加卸载流变试验，并对破裂后的岩样进行了电镜扫描分析，揭示了渗流-应力耦合长期作用下的岩石时效变形、损伤演化及细观破裂机制。其次，在上述试验结果的基础上，建立了基于微裂纹亚临界扩展的岩石细观流变损伤本构方程、基于微裂纹扩展引起的渗透性演化方程以及基于微裂纹演化的岩石渗流-应力耦合流变损伤本构模型，发展了一种渗流-应力耦合作用下岩石流变破裂全过程的宏细观双尺度数值方法，并进行了数值验证。最后，以典型深部富水巷道为背景，进行了巷道围岩变形和破裂的长期动态观测，基于双尺度数值模型分析了不同支护系统、让压条件、注浆时机等对控制深部富水巷道围岩流变变形与破坏发展的作用规律，优化了深部富水巷道长期稳定关键控制参数，并提出了“让压-锚注”耦合支护控制技术体系，现场应用效果良好。.项目研究成果对于解决我国深部富水巷道围岩控制与灾害防治难题，完善深部巷道围岩控制理论，推动我国矿山岩体力学理论向纵深层次发展都具有重要的理论意义与工程价值。