深部采空区破碎岩体二次成岩机制及其稳定性研究

Due to the secondary reorganization of the structure and composition of the regenerated rock mass in the deep goaf, the mechanical properties of this kind of rock mass have undergone an essential change. The control of the surrounding rock of the regenerated rock mass is a difficult problem to limit the deep mining of coal resources. At present, the second diagenesis mechanism and the stability of fracture rock mass in deep goaf are not clear, and the control of surrounding rock of the regenerated rock mass roadway in deep goaf lacks a reliable theoretical support, making the support has a certain degree of blindness. Therefore, the structural characteristics and mechanical behavior of fractured rock mass in deep goaf are analyzed by means of theoretical analysis, field detection and laboratory test. The compaction-consolidation diagenesis process of crushed rock mass is simulated by experiment, the mechanism of stress-time coupling of secondary diagenesis of crushed rock mass is explored, and the constitutive equation of deep regenerated rock mass is established. The deep mine roadway model test is adopted to study the deformation and failure mechanism of the surrounding rock of the reclaimed rock mass and the nonlinear decay law of the surrounding rock self-bearing capacity. Combined with the engineering characteristics of anchor bolt, the mechanism of co-bearing action between bolt supporting structure and surrounding rock of deep regenerated rock mass is studied. The combined bearing mechanics model of surrounding rock mass in deep gob area is proposed. The criterion of secondary instability of surrounding rock mass and its controlling principle in deep goaf are proposed, and it provides a theoretical basis for the surrounding rock control of deep regenerated rock mass roadway.

深部采空区再生岩体由于结构和成分进行了二次重组，岩体的力学性质发生了本质变化。再生岩体巷道围岩控制问题成为限制煤炭资源深部开采的难点问题。目前，深部采空区破碎岩体二次成岩机制及其稳定性尚不明晰，采空区再生岩体巷道围岩控制缺乏可靠的理论支撑，使得支护具有一定的盲目性。因此，本项目结合理论分析、现场探测和实验室试验等手段，分析深部采空区破碎岩体的结构特征及力学性状。通过试验模拟深部采空区破碎岩体压实-固结成岩过程，探究破碎岩体二次成岩的应力-时间耦合作用机制，建立深部再生岩体本构方程。采用深部矿井巷道模型试验，研究再生岩体巷道围岩变形破坏机理与巷道围岩自承载能力的非线性衰变规律。结合锚杆工程特性，研究锚杆支护结构与深部再生岩体巷道围岩的协同承载作用机理，构建深部采空区巷道围组合承载力学模型，提出深部采空区再生岩体巷道围岩二次失稳判据及其控制原理，为深部再生岩体巷道围岩控制提供理论依据。

采用理论分析、数值模拟、实验室实验和现场实测等手段主要展开深部采空区破碎岩体结构特征及其力学特性研究、深部采空区破碎岩体二次成岩机制研究以及深部采空区再生岩体稳定性控制原理分析。研究结果表明：破碎岩体二次成岩不仅与应力、时间有关，而且于围岩成分（是否含胶结材料）、含水率、岩性（主要指岩块强度）、粒径（包括粒径级配）等因素有关。在分次压实破碎岩样过程包括破碎压实、压实应力记忆和压密固结三个阶段，对应的压实特性曲线分别表现为线性、“S”型多项式以及指数形式变化，压缩次数越多，累积压缩应变越大。二次成岩试件的三轴强度与含水率呈三次多项式增长关系，与压实应力呈线性增长关系，与粒径之间呈三次多项式减小关系，二次成岩试件单轴抗压强度随粒径增大而线性减小。在工程尺度上，再生顶板围岩破碎冒落边界在纵向上以“抛物线”形式扩展，在横向上以“类双曲线”形式延伸，致使棚架变形失稳。通过现场调研采样和实验室进行破碎岩样分次压实试验，建立了实验室压实粒度分布与工程岩体实际压实应力及压实程度之间的相关关系。通过不同条件下的破碎岩样压实-固结二次成岩试验，提出以受侧限压缩时的破断指数和固结成岩时的固结指数。通过深部采空区再生顶板巷道稳定性控制原理与技术研究，提出采用“双层金属网+预支撑囧型棚架+可缩性纵向连接器”的组合支护技术。通过本项目的研究可为类似条件下的巷道围岩控制提供理论支撑与技术参考。