夹矸对组合煤岩结构失稳破坏的控制机理及前兆信息研究

The special discontinuous structure formed by partings contained in coal seam significantly controls the deformation, damage and mechanical properties of coal and rock materials, and the interaction between the structure and the dynamic and static load has an essential effect on the pressure of working face, roadway damage and the evolutionary process of rockburst. Therefore, based on the combined coal-rock structure contained parting, we propose to investigate the failure mechanism of the structure subjected to dynamic and static load. Using the time dependent damage model and catastrophe theory, we will establish the geomechanical model of combined coal-rock structure composed of “roof-coal-parting-coal-floor (RCPCF)” deformation and failure subjected to dynamic and static load, and analyze the main influencing factors of parting on the combined coal-rock structure deformation and failure. In addition, by experiments and numerical simulation, we will conduct the investigation on failure process, the evolutions of deformation and energy fields, and energy dissipation rule of combined coal-rock structure contained parting subjected to dynamic and static load, reveal the key influencing factors of failure (especially the instability and failure of structure induced by parting slip), and put forward the corresponding controlling mechanism of parting and mechanical criterion of instability. Ultimately, we will experimentally measure the mechanical parameters and acoustic emission (AE) information in the whole process of deformation and failure of coal and parting in coal-rock structure, analyze the AE effects generated by coal fracture and parting slip, reveal the precursory characteristics of mechanical parameters and AE, and propose the early-warning method of combined coal-rock structure prior to failure. The expected outcomes of our proposal may provide some useful references for the surrounding rock control of working face and roadway, and rockburst prevention in the contained-parting mining regions.

煤层赋存的夹矸所形成的独特不连续结构控制着煤岩的变形、破坏及力学性质，该结构与动静载之间的相互作用是影响工作面矿压、巷道失稳及冲击地压演化过程的关键。本课题以含夹矸组合煤岩结构为研究对象，采用时效损伤本构模型与突变理论，建立动静加载下“顶板-煤层-夹矸-煤层-底板”组合煤岩结构失稳破坏的地质与力学模型，分析夹矸对组合煤岩结构变形破坏的主要影响因素；实验和数值模拟研究含夹矸组合煤岩结构的破坏、变形场和能量场的演化以及能量耗散规律，揭示其失稳破坏（尤其夹矸“层滑”导致煤岩结构失稳破坏）的关键因素，提出夹矸对组合煤岩结构变形破坏的控制机理及失稳判据；测定组合煤岩结构中煤体和夹矸变形破坏过程中的力学和声发射信息，研究煤体破坏以及夹矸滑移失稳的声发射效应，揭示其前兆信息特征，提出相应的预警方法。本课题的预期成果能够为含夹矸区域的工作面及巷道围岩控制以及冲击地压防治等提供有益参考。

煤层赋存的夹矸所形成的独特不连续结构控制着煤岩的变形、破坏及力学性质，该结构与动静载之间的相互作用是影响工作面矿压、巷道失稳及冲击地压演化过程的关键。我国多数矿井特别是鲁西南矿区主采3煤层普遍存在煤层分叉和夹矸，在采动影响下，夹矸滑移可能导致异常矿压显现、矿震、冲击地压等煤岩动力灾害（例如赵楼煤矿2015年“7.29”冲击地压事故）。本项目以“煤-夹矸-煤”组合煤岩结构为研究对象，系统开展了室内岩石力学实验、PFC数值计算、理论建模以及现场观测等，分析了含夹矸组合煤岩体的变形、破坏方式以及力学性质；建立了动静加载下组合煤岩结构失稳破坏的力学模型，揭示了组合煤岩结构变形破坏的机理，建立了组合煤岩结构失稳破坏的判据；研究了组合煤岩结构失稳破坏的前兆信息，揭示了声发射前兆效应，提出了组合结构失稳破坏的关键和前兆预警的方法；根据现场煤岩层以及夹矸参数、静载和冲击动载的监测结果进行了计算和验证，完善了理论。取得了如下重要结果：（1）建立了动静载作用下组合煤岩结构的力学模型，发现动载扰动可以通过改变主应力大小及方向以及接触面摩擦性质，促进夹矸-煤组合结构的破坏失稳，同时可以改变组合结构的失稳形式（滑移/破碎失稳）；（2）提出了动静载作用下夹矸对组合煤岩结构失稳破坏的控制机理及判据，发现了组合煤岩结构的三种破坏失稳方式，包括煤岩体破碎、单一接触面滑移破碎以及双接触面滑移破碎；（3）得到了动静载作用下含夹矸组合煤岩结构失稳破坏前兆的预警方法。失稳前兆信号特征满足：应力波动、裂隙发育及能量释放减缓；声发射事件b值由高值迅速降低；断层总面积出现相对低值。项目研究成果有助于进一步揭示煤层分叉以及夹矸滑移导致巷道变形破坏、异常矿压显现甚至诱发冲击地压的机理。