深部碎裂围岩锚固协同承载力学性能及作用机制研究

The fragmented surrounding-rockmass and bolt can enable the excavated deep tunnel to be stable again. Nevertheless, the fundamental understanding of the composite bearing performance and cooperated mechanism remains elusive between the two, which results in anchoring support design being crude and empirical. To solve this key problem, the effect laws of structural characteristics of fragmented rock-mass and anchoring parameters on bearing performances of anchored surrounding rock will be investigated through orthogonal physical simulation tests firstly. By so doing, the sensitivities of various influencing factors will be recognized quantitatively. The computational formula of composite bearing capacity incorporating the influence of fragmentation degree of surrounding rock will be proposed. Further, the characteristics of bolt shear and tension failure, and the dynamic inhibiting effect of anchored fragmented surrounding-rockmass in post-peak period will be considered. The corresponding constitutive models will be presented after amendment and embedded in existing discrete element software based on the experimental results. Then the overall forming-bearing-failure process of the load-bearing body of anchored fragmented surrounding-rockmass can be reappeared. Furthermore, by means of the numerical tests and physical simulation tests, the stress response characteristics, broken expand evolution laws, structural restraint effects, and discontinuous deformation fracture modes of the anchored fragmented surrounding-rockmass in twice stable process will be investigated systematically. Accordingly, the action mechanism of the anchored fragmented surrounding-rockmass in the overall load-bearing process will be discerned. The quantitative evaluation index of surrounding-rockmass control effect and the matched suggested anchoring parameters will be put forward. This research serves to provide theoretical basis for the design of anchoring support and the stable control of surrounding rock in deep tunnels.

碎裂围岩与锚固支护协同作用可实现深部隧洞二次稳定，但其复合承载力学性能及作用机制尚不明确，致使锚固支护设计多依靠经验类比。针对该关键问题，本项目首先开展正交物理模拟试验，研究不同碎裂围岩结构特征及锚固参数对围岩锚固协同承载体力学性能影响规律，定量识别各因素影响敏感程度，统计提出可考虑围岩碎裂程度影响的复合承载力计算公式；基于试验数据修正提出可考虑锚杆剪切、拉伸承载-失效特性与碎裂围岩峰后锚固动态抑制效应的本构模型，并嵌入现有离散元软件中，再现碎裂围岩锚固协同承载体形成-稳定承载-失效的全过程；基于数值试验与模拟试验，研究锚固碎裂围岩二次稳定过程中的应力响应特征、碎胀演化规律、结构控制效应及非连续破裂模式，揭示碎裂围岩锚固协同承载的全过程演化作用机制，建立碎裂围岩锚固控制效果定量评价指标，提出相匹配锚固参数建议值。研究成果可为深部隧洞锚固支护设计及围岩稳定控制提供理论依据。

深部隧洞开挖后碎裂围岩与锚固支护协同作用可实现二次稳定，但其复合承载力学性能及作用机制尚不明确，致使目前隧洞锚固支护设计多依靠经验类比。本项目聚焦该科学问题，通过室内试验、理论分析与数值模拟相结合的研究方法，进行了深部碎裂围岩锚固协同承载力学性能及作用机制研究。首先，考虑单裂隙张开及滑移工况，开展了锚杆拉伸与剪切力学试验，得到了锚杆杆体在拉伸与剪切工况下的承载-失效特征与本构关系，提出了单裂隙岩体锚固承载强度计算方法；其次，提出了碎裂岩体实验室模拟方法，考虑岩块大小、岩性、锚杆布设参数等因素，开展了碎裂岩体锚固承载力学性能试验，揭示了锚固复合体在试验加载过程中的协同承载性能与作用机制；第三，根据锚杆对围岩的轴向与横向支护作用，建立了围岩强化指标计算公式，提出了碎裂岩体锚固复合承载性能的定量评价方法；第四，将提出的锚杆拉伸、剪切承载-失效本构关系，通过程序二次开发，将其嵌入到常用商业数值模拟软件中，修正实现了锚杆承载及失效特性的有效模拟。最后，考虑不同支护参数影响，开展了典型深部隧洞、硐室开挖-支护全过程数值模拟，揭示了围岩-锚固支护的全过程相互作用特征与灾变演化机制，提出了锚杆-围岩相互作用分析方法。研究成果可为我国深部隧洞工程锚固支护设计及围岩稳定控制提供理论依据。