深部大变形巷道层状顶板锚索破断机理研究

The cable bolt is the main supporting material for rock reinforcement in engineering. As the mining depth and intensity of coal mining continue to increase, the large deformation problem of deep roadway has been severer, which results in a significantly increasing use of the cable bolt. Furthermore, the failure rate of the cable bolt in layered roof is quite high, which causes a reduction of supporting strength and make the roof fall more easily. The comprehensive research methods, including in-situ detection, theoretical analysis, laboratory experiment and numerical simulation, will be used in this project to systematically study the failure mechanism of layered roof cable bolts in deep large deformation roadway. Firstly, refined in-situ exploration on flexural separation and shear slip evolution rules of layered roof in large deformed deep roadways will be performed, to study the deformation and fracture mechanism of cable bolt caused by the subsidence of layered roof. Meanwhile, the real stress state of cable bolt in layered roof will be explored, to obtain the key factors affecting the critical force of cable bolt, and furtherly to put forward the criteria that can accurately identify the critical rock layer leading to the failure of cable bolt. Secondly, the mechanical properties of prestressed cable bolt will be studied by the self-designed double shear test system, to reveal the reinforcement mechanism of jointed rock mass by cable bolt. On this basis, the mechanical model of interaction between prestressed cable bolt and jointed rock mass will be established to reveal the fracture mechanism and criterion of cable bolt in layered roof. It can furtherly provide a more scientific theoretical basis for the design and early warning of cable bolt support in large deformed layered roof.

锚索是工程岩体加固的主要支护材料。随着煤矿开采深度与强度不断增加，深部大变形巷道逐渐增多，锚索的使用量大幅增加，而大变形巷道层状顶板锚索破断率高，极易引发巷道冒顶。本项目拟采用现场探测、理论分析、实验室实验和数值模拟等综合研究方法，系统研究深部大变形巷道层状顶板锚索破断机理。首先，现场精细探测深部大变形巷道层状顶板挠曲离层与剪切滑移演化规律，探究层状顶板下沉致使锚索变形乃至断裂的力学过程；同时，研究层状顶板不同区域锚索真实受力状态，获取影响索体危险受力的关键因素，并提出能够准确辨识索体危险受力层位的判据。其次，采用研发的锚索双剪实验系统，研究预应力锚索剪切力学特性，揭示锚索对含结构面岩体的加固机制。在此基础上，构建预应力锚索与岩体结构面相互作用的力学模型，揭示巷道层状顶板锚索破断机理，并形成顶板锚索断裂准则，为大变形巷道层状顶板锚索支护设计与破断预警提供更加科学的理论依据。

锚索是煤矿巷道围岩控制的重要支护材料。随着煤矿开采深度增加，大变形巷道增多，锚索的使用量大幅增加，但顶板锚索破断问题较为突出，严重影响生产安全。本项目综合采用现场探测、理论分析、室内试验和数值模拟等方法，针对煤矿深部大变形巷道层状顶板锚索破断问题进行深入系统研究，获得了深部大变形巷道层状顶板锚索破断特征，研究了不同因素影响下深部大变形巷道层状顶板挠曲离层演化规律，深刻认识了层状顶板挠曲离层致使锚索变形与断裂的力学过程；研究了不同因素影响下顶板锚索的真实受力特征，阐明了深部大变形巷道不同区域顶板与锚索的相互作用机制，提出了能够辨识索体危险受力层位的判据；重点研究了预应力锚索的剪切力学行为，获得了锚索对含结构面岩体剪切性能的作用机制和模式，揭示了预应力锚索在轴向拉伸与横向剪切耦合作用下对节理岩体的加固机理；构建了预应力锚索与岩体结构面相互作用的力学模型，揭示了深部大变形巷道层状顶板锚索分区域破断机理，阐明了锚索破断失效与层状顶板变形失稳之间的内在联系，并提出了防止深部大变形巷道层状顶板锚索破断的控制对策。研究成果可为深部大变形巷道顶板锚索支护设计和破断预警提供科学的理论依据，对保证巷道围岩的稳定与畅通，具有重要的理论和实际意义。