西部浅埋煤层开采隐伏断层活化诱发顶板切落机理及前兆特征研究

Large-area roof cutting disaster accidents occur frequently due to the large-scale, high intensity shallow coal seam mining in western China. When the roof has hidden faults, it will cause the complexity and sudden of the roof breaking process. This project will study the complexity of mining pressure in shallow seam with hidden faults, the mechanical mechanism and the control factors of roof cutting disaster, the precursor information of and interaction between surrounding rock and support, and the precursory characteristics of disasters, etc.. Through the combining the methods of theoretical analysis, numerical simulation, similar simulation test, field test, the mechanical model of roof failure under the influence of hidden faults is established. This study will analyze the key disaster factors of the instability of mining disturbance, reveal the mechanical mechanism of the catastrophes process of the cutting roof of the hidden fault and refining the key factors causing disaster, analyze the characteristics of the stress field, fracture field, displacement field and the change of the support pressure and the working resistance of the roof during the roof damage, deformation and fracture, the process and regularity of the mining failure of the roof under different occurrence conditions of the hidden fault, perfect the calculation method of the working resistance of support under the combined action of static and dynamic loads. By the studies of this project, we can refine the precursor characteristics of roof cutting disaster, build the multi parameter processing method of roof cutting more disasters precursor information, perfect the system of roof cutting disaster prevention and control technology, promote sustainable exploitation of mining safety and efficiency.

我国西部浅埋煤层在大规模、高强度开采中大范围顶板切落灾害事故频发，当顶板有隐伏断层存在时会造成顶板破断过程的复杂性、突发性。本项目针对西部浅埋煤层开采诱使隐伏断层活化矿压显现规律、顶板切落灾害发生的力学机理和主控因素、围岩支架关系及灾害前兆特征等内容进行深入研究，通过理论分析、相似材料模拟、数值模拟及现场监测相结合的手段，建立隐伏断层影响下顶板破断失稳的力学模型，揭示隐伏断层采动活化顶板切落压架突变过程的力学机制并提炼关键致灾因素，分析工作面过隐伏断层时的顶板损伤、变形直至断裂过程中的应力场-裂隙场-位移场特征及支承压力、支架工作阻力的变化规律，再现隐伏断层不同赋存条件下顶板的采动破断来压过程和规律，完善动静荷载联合作用下支架工作阻力的计算方法，提炼顶板切落灾害的前兆特征，建立顶板切落灾害前兆特征的多参量处理方法，完善切顶灾害的防治技术体系，促进西部煤炭资源安全高效可持续开采。

我国西部浅埋煤层在高强度开采过程中顶板灾害事故频发，尤其在初次来压及周期来压过程中顶板事故尤其严重，且具有明显的复杂性、突发性特征，严重危害了人民的生命安全和矿山企业的正常生产。因此，针对浅埋煤层开采过程中的矿压规律进行深入研究，揭示我国西部煤炭高强度开采下矿压显现特征和支架-围岩关系，探讨支架工作阻力的适应性，具有重要的理论和实际意义。我们主要做了如下几个方面的研究工作：(1)通过构建数值模型研究了3m~7m采高条件下的顶板破断过程及来压规律，研究了来压步距、支承压力的变化特征，分析了大采高顶板损伤裂隙扩展规律及破断的结构特征，探讨了大范围冲击地压显现机理。(2)结合断裂力学中裂纹受力扩展分析方法，建立了含边裂纹基本顶初次破断来压的断裂力学分析模型。分别计算了拉应力、剪应力和弯矩三种应力作用下的应力强度因子。讨论了顶板损伤裂纹活化准则及裂纹扩展工作面来压的充要条件，得到了保障工作面稳定的支架工作阻力计算公式。(3)建立了由基本顶-直接顶-支架组成的系统力学模型，基于直接顶岩体在支承压力作用下破坏失稳的非线性变化特征，利用突变理论及能量守恒原理研究了大采高工作面初次来压顶板沿煤壁滑落失稳机理。获得了系统失稳的充要条件条件，建立了岩体破坏分析方法和失稳判据，分析了突变发生的主要影响因素，给出了基本顶滑落失稳控制的支架支护阻力计算公式。(4)构建断裂力学模型研究了隐伏断层倾角对来压步距和支架工作阻力的影响作用，通过物理模型对比分析了不同倾角隐伏断层在工作面推进过程中的活化、扩展、垮落压架过程，分析了支承压力、断层应力场、支架工作阻力等的变化特征。断层倾角的变化对切顶线的形成和上覆岩层切落形特征有重要影响，且造成了工作面的剧烈来压。通过本项目，完善了切顶灾害的防治技术体系，为西部煤炭资源安全高效可持续开采提供了有力支持。