层裂结构围岩储能释放机制及防冲动态调控研究

The rock mass around the roadway generally has an initial damage after the unloading excavation，and the complex stress environment can easily lead to high energy accumulation, which may cause rockburst. Thus, the energy evolution process of surrounding rock and its dynamic control are essential for the rockburst research. This project uses both macro and micro scale experiment methods to study the energy accumulation and release of the surrounding rock with layer-crack structure based on the coal(rock) damage as the main line. Firstly, the mechanical response of coal(rock) structure of different scales are researched through multi-physical field unloading experiments of layer-crack structure body, and then the characteristics of progressive failure and residual stress are analysed. Secondly, the energy field evolution under the mining condition is researched, the energy accumulation and storage based on gradient effect are analysed, and the damage constitutive model of energy release of layer-crack structure body is established. Thirdly, co-evolutionary behavior of energy accumulation and degradation damage of the surrounding rock with layer-crack structure are researched to reveal the mechanism of energy birth for the rockburst formation, and to propose two criterion: energy storage limit of start-up rockburst and energy release of gradient drive. Finally, the warning indexes and precursor information modes of rockburst are explored, energy control methods for rockburst prevention are proposed, and the dynamic prevention technology system depending on the risk classification of roadway’s surrounding rock is constructed. This research will provide a new theoretical foundation for predicting, evaluating and preventing rockburst of mining roadways.

开挖卸荷后的巷道围岩普遍具有初始损伤性，回采期间复杂应力环境易于形成冲击地压发生的能量条件，采动围岩能量演化过程及动态调控在冲击地压研究方面非常重要。本项目以煤岩损伤演化为主线，采用宏细观尺度试验方法研究层裂结构围岩能量存储与释放问题。首先，进行层裂结构体加卸载的多物理场试验，研究采动条件下不同尺度煤岩结构的力学响应，分析残余应力分布及渐进失稳破裂特征；其次，研究采动条件下围岩能量场演化规律，分析能量积聚存储形式与梯度效应，建立层裂结构体能量释放损伤本构模型；然后，研究层裂结构围岩能量累积与劣化损伤协同演化行为，揭示回采巷道冲击地压形成的能量孕育机制，提出冲击启动储能极限判据与能量释放梯度驱动判据；最后，探寻冲击地压预警当量指标与前兆信息模式，研发回采巷道防冲能量调控方法，构建巷道围岩危险性分级动态解危技术体系。本研究将为煤矿回采巷道冲击地压预测评价及灾害防治提供新的理论依据。

本项目针对煤矿巷道围岩层裂结构冲击地压致灾机理及调控解危方法，开展了系统的理论与试验研究。结合深部矿井脆性煤体钻孔窥视分析了围岩层裂结构破坏特征，构建滑移裂纹力学模型揭示了层裂结构形成机制；探讨了不同裂隙形态对层裂体失稳特征及损伤规律的影响特性，揭示了层裂体受压破坏和受拉破坏的失稳机制；研究巷道围岩破坏规律并建立了层裂结构动力失稳模型，获取了层裂体能量演化规律及动力失稳机制；结合煤矿巷道围岩层裂结构动力失稳的能量驱动理论，构建了巷道围岩层裂结构失稳的防控理念。研究结果表明：（1）相对高应力和硬脆性煤体易促进巷道围岩层裂结构形成和冲击地压发生，巷帮浅部煤体产生交替破裂现象且呈现层裂结构特征，煤壁松动、片帮和煤壁位移的破坏深度普遍小于冲击发生前浅部层裂煤体宽度；（2）层裂结构受压破坏失稳过程可分为均衡承载、非均衡承载和峰后破坏失稳三个阶段，裂隙宽度、长度及数目增加会减小均衡承载阶段应变、增大非均衡承载阶段应变，并降低其承载能力；（3）层裂结构动力失稳存在“煤体”自身释放型和“煤体+顶板”共同释放型两类机制，随围压增加层裂结构能量比例先提高后降低，随裂隙数目增加层裂结构能量比例降低；（4）巷道围岩层裂结构动力失稳防控主要包括增加浅部层裂煤体破坏时所需能量和减小深部完整煤体及顶板可释放能量两方面，现场实践表明防控方法避免了巷道围岩层裂结构动力失稳事件。.通过本项目共发表SCI论文10篇、中文核心论文2篇；授权国家发明专利4项、实用新型专利5项；获得中国煤炭工业科学技术一等奖1项、中国职业安全健康协会科学技术一等奖1项；参加国内外学术会议11次；培养毕业博士2名、硕士6名。本项目的研究成果为围岩层裂结构诱发冲击地压提供了新的实验解答，对煤矿回采巷道冲击地压预测评价及灾害防治提供了新的理论依据。