深部开采底板隐伏断层活化效应及承压水导升致灾机理研究

This project aims at the safety problem of water inrush of bottom plate caused by mining on high pressure aquifer under the condition of deep complex stress. The main line of this project is the coupling of mining stress and water pressure. The key scientific problems about the activation effect of hidden fault and the mechanism of water conductivity rise caused by pressure are studied. Firstly, the mechanical properties of rock samples with different combination of fractures are studied. On the basis of permeability test and physical simulation test of macroscopic failure of floor plate containing hidden fault, the mechanism of multi-scale deterioration of deep floor water barrier layer is revealed, and the coupling numerical model of stope propulsion with hidden fault on bottom plate is established. The influence of fault strength and dip angle, relative position of fault and working face, lithologic combination structure, mining intensity and aquifer water pressure on the water inrush of deep mining floor is analyzed, and the promotion mechanism of hidden fault to the formation of water inrush passage is discussed. This paper reveals the activation effect of hidden faults, based on the measured distribution of mining stress in deep mining stope of typical mine, constructs the mechanical model of underground fault activation under the condition of mining under the action of osmotic water pressure, and studies the mechanical mechanism of hydraulic conductivity and uplift of confined water. The formula for calculation of water conductivity and uplift of confined water is derived, and the mechanism of water inrush induced by confined water is revealed, which can guide the safe and efficient mining of coal resources in deep high pressure water body.

本项目针对深部复杂应力条件下高承压含水层上开采引发的底板突水安全问题，以开采应力、水压力多因素耦合作用为主线，围绕底板隐伏断层活化效应和承压水导升致灾关键科学问题开展研究。在含裂隙不同岩性组合岩样力学特性、渗透性细观试验及含隐伏断层底板宏观破坏物理模拟试验的基础上，揭示深部底板隔水层多尺度劣化机制；以此为基础建立底板含隐伏断层的耦合数值模型，分析断层强度及倾角、断层与工作面的相对空间位置、岩性组合结构、开采强度、含水层水压等因素对深部开采底板突水的控制效应，探讨隐伏断层对突水通道形成的促进机制，揭示隐伏断层活化效应及承压水渗流、运移、导升机制；在实测典型矿井深部采动应力分布规律的基础上，构建高渗透水压作用时采动条件下底板隐伏断层活化的力学模型，研究承压水导升力学机制，推导承压水导升计算公式，揭示承压水导升突水致灾机理，指导深部高承压水体上煤炭资源的安全高效开采。

随着采深增加将面临愈加复杂的工程地质与水文地质条件，底板隐伏断层突水现象更加突出。底板隐伏断层不仅弱化底板岩层的完整性，而且对采动应力在底板动态分布规律扰动作用亦十分显著，极易造成隐伏断层围岩活化导水。本项目通过现场实测、理论分析、数值模拟等手段，开展高水压与采动应力耦合作用下含隐伏断层底板承压水导升致灾机理研究。基于底板突水类型和典型突水案例分析，提出上位隐伏性断层突水、下位隐伏性断层突水、沟通隐伏性断层突水三类底板隐伏断层突水模式；开展了不同岩性岩石试样循环加卸载-渗流和声发射试验，从实验室角度揭示了含隐伏断层底板隔水层劣化机制；基于半无限体理论模型，建立了下位隐伏断层采动力学模型，研究得出底板导水隐伏断层采动导升高度计算公式；针对不同隐伏断层赋存特征，开展了底板高承压水采动运移规律研究，模拟结果表明：受采动影响，隐伏断层围岩会出现应力集中现象，高承压水更易趋向具有良好导水性的隐伏断层运动，隐伏断层厚度越大、倾角越大、越接近含水层则对承压水导升影响越显著；分别从采动裂隙可视化和导水性、采动地层应力—应变特征、采动地层物性变化特征等多参量方面，以“点—线—面”、动静结合全空间的方式，监测获取矿区采动底板破坏规律，在此基础上提出底板采动破坏分带模型，将底板采动影响范围自上而下分为导水裂隙带、微小裂隙带、物性差异带。研究了采动与水压力协同作用下底板隐伏断层突水机制，研究表明：隐伏正断层对于底板应力场扰动作用要强于隐伏逆断层，前者突水通道发育规模显著大于后者，隐伏正断层更容易诱发突水灾害。并基于底板采动破坏分带模型提出了隐伏断层底板采动应力与水压力联合作用突水机制，并提出了一种“精查构造疏水降压、系统治理分段强注”的底板突水防控技术。本项目的研究成果不仅丰富了承压水上开采的理论体系，而且对深部带压开采、尤其是底板含隐伏断层突水灾害预防具有重要的理论指导意义。