压裂-采动效应对坚硬顶板损伤及瓦斯运移的影响机理

The hard roof – gas coupling disaster constitutes a serious threat to the coal mine safety production. Hydraulic fracturing is an effective means for controlling hard roof and gas disaster. The influence mechanism of the fracturing–mining superimposed effects on hard roof damage and gas transport is the key scientific problem to study the hard roof–gas coupling disaster. Take the hard roof as the research object, based on the fracture mechanics and fluid mechanics, the propagation mechanism of hydraulic fracture in compound hard roof is analyzed, the propagation rules and fracture shape are revealed. According to the stress analysis and superposition principle of elastic-plastic mechanics, the stress field distribution equation of hard roof with fracturing – mining effects is established and the evolution law of stress and crack fields in time and space under the influence of fracturing–mining effects. Based on the distribution characteristics and evolution laws of stress fields, the load-unload stress path could be determined and the deformation–failure and gas seepage experiments could be carried out. Based on gas-solid coupling theory and porous media dynamics, the coupling model of crack field evolution and gas transport of hard roof under fracturing–mining effects and the gas transport and concentration regularity could be studied. The research results could provide scientific basis for the control of hard roof – gas coupling disaster.

坚硬顶板-瓦斯耦合灾害严重威胁矿井的安全生产，水力压裂是治理坚硬顶板、瓦斯灾害的有效手段，压裂-采动作用的叠加效应对坚硬顶板的损伤及瓦斯运移的影响机理，是研究解决坚硬顶板-瓦斯耦合灾害的关键科学问题。以坚硬顶板为研究对象，首先基于断裂力学和流体力学，对水压裂缝在复合坚硬顶板的扩展机理进行分析，揭示水压裂缝的扩展规律及裂缝形态；基于弹塑性力学应力分析和叠加原理，建立压裂-采动效应下坚硬顶板的应力场分布方程，揭示压裂-采动效应下坚硬顶板的应力场、裂隙场时空演化规律；根据应力场展布特征及演化规律，确定加卸载应力路径，开展坚硬顶板岩石变形破坏及瓦斯渗流实验；然后基于气固耦合理论、多孔介质力学等相关理论，建立压裂-采动效应下坚硬顶板的裂隙场演化与瓦斯运移的耦合模型，对压裂-采动效应下瓦斯的运移富集规律进行研究。项目的研究成果可为坚硬顶板-瓦斯耦合灾害的防治提供科学依据。

坚硬顶板-瓦斯耦合灾害严重威胁矿井的安全生产，水力压裂是治理坚硬顶板、瓦斯灾害的有效手段，对压裂-采动作用的叠加效应及其对坚硬顶板作用特征进行研究，对于坚硬顶板-瓦斯耦合灾害的防治具有重要意义。.项目采用理论研究、数值模拟、实验室与现场实验等相结合的方法展开研究：① 开展了水压裂缝在复合层状坚硬顶板的扩展机理研究，建立了水压裂缝在复合坚硬顶板扩展的理论分析模型，得出了不同扩展模式的理论判别式，揭示了不同因素对水压裂缝扩展的影响机制；② 开展了水力压裂复合坚硬顶板的相似模型试验和现场试验，得到了水力压裂复合坚硬顶板的裂缝扩展规律、裂缝形态及分布范围；③ 建立了复合坚硬顶板的应力场分析模型和坚硬顶板压裂改造应力场与采动应力场的应力叠加分析模型，得出了压裂-采动效应下坚硬顶板的应力场分布方程，揭示了压裂-采动效应对坚硬顶板失稳破断的影响机制；④ 对压裂-采动效应下坚硬顶板的变形破坏特征及渗流规律进行了研究，揭示了压裂-采动效应下坚硬顶板岩石应力场、裂隙场演化规律及瓦斯运移规律。.相关研究成果可为水力压裂治理坚硬顶板-瓦斯耦合灾害提供理论基础，有效提升坚硬顶板-瓦斯耦合灾害的治理效果，具有应用价值。