煤层群开采的多次采动应力与瓦斯压力演化的响应机制研究

High in-situ stress and gas pressure is redistributed and released within rock mass and coal seams, which is resulted from multiple mining activities of multiple coal seam.,Rock mass and coal seam failure may be triggered by the combination interaction effect of mining induced stress and gas pressure and this failure type has been became one of key factors constraining the normal mining safety. The response mechanism between the stress redistribution in surrounding rock and the gas pressure evolution due to mining processing in coal seam is still unclear. To understand the interaction mechanism of mining induced stress and gas pressure evolution, a synthetically methods are taken in this study, which including the,in-situ field tests, laboratory tests, numerical simulation, and theoretical analysis. The influence of stress alternation on the gas pressure is investigated firstly for the coal specimens with gas. In the mean time, the stress-strain relations of coal specimens with gas are conducted under different gap pressure. Based on the lab results, the interaction effect between the coal seam stress and gas pressure evolution is further studied for multiple coal seams. In addition, the mechanism and interaction effect of mining-induced stress on gas pressure are explored. In this fashion, a constitutive relationship, a instability failure criterion, and a coupling mathematical model is proposed and developed for coal body containing gas. The results would provide a theoretical support for the co-mining of gas and coal and for the gas burst prone mines within high-gas coal seam

煤层群开采的多次采动作用将导致煤岩所受的高地应力、高瓦斯压力不同程度的多次被卸除，这将更容易诱发煤岩体失稳破坏从而造成的矿井灾害，而开采扰动造成的应力重新分布与煤层瓦斯压力演化的相互响应机制构成了煤与瓦斯突出主要致灾背景，亟待深入研究。本研究以多煤层条件下的采动应力和瓦斯压力响应机制为出发点，采用现场实测、实验室实验、数值模拟以及理论分析综合研究方法，开展含瓦斯煤样应力变化对瓦斯压力的影响规律、不同瓦斯压力条件下含瓦斯煤样应力应变关系的实验研究；在此基础上，研究煤层群条件下采场煤层应力和瓦斯压力演化的采动影响规律，并揭示采动应力对瓦斯压力动态演化的影响机理、及相互作用关系，构建采动应力与瓦斯压力相互作用的数力学模型，为优化煤与瓦斯共采技术和高瓦斯突出矿井的瓦斯灾害预测与防治提供理论支持。

本项目建立了煤层瓦斯压力场二元高阶多项式反演数学模型，形成了一种基于阻尼最小二乘法的二元高阶多项式瓦斯压力场反演方法，揭示了煤层最大瓦斯压力梯度方向与最大水平主应力方向近似垂直的规律。实验阐明了重复加卸载路径下煤岩峰后力学行为特征及其围压效应，揭示了卸压开采下煤岩峰后变形机制；获得了不同循环加卸载路径下含瓦斯煤的渗流特性，揭示了不同循环加卸载路径下含瓦斯煤损伤演化特征。基于煤层瓦斯赋存条件和工作面的开采顺序，建立了煤层瓦斯压力赋存条件的简化的数值计算模型，再现了工作面依次开采过程中煤层瓦斯压力的分布特征及瓦斯压力场的宏观演化规律。研发了一套在线/离线煤层瓦斯压力动态监测分析系统，系统实现了瓦斯压力数据在线/离线式的连续自动观测和记录，并且可以自动绘制煤层瓦斯压力变化曲线。提出了双巷掘进或底抽巷/高抽巷掩护煤巷掘进条件下突出危险性动态监测预警技术，形成了在线或离线煤层瓦斯压力动态监测分析系统，并对掘进面前方煤体内煤层瓦斯压力的动态分布规律进行了监测，进而定量化分析了掘进工作面的突出危险性。研究成果为优化煤与瓦斯共采技术和高瓦斯、突出矿井的瓦斯灾害预测与防治提供了理论与技术支持。