含弱胶裂隙锚固承载结构累积损伤过程及增稳止损效应

Based on the fact which soft-rock roadway surrounding rock has been damaged before carrying out bolt support, it will be studied that the accumulated damage process, stability increasing and loss stop mechanism of anchorage bearing structure with weak cementation fissure. The integrated research method such as Lab experiment, theoretical analysis, numerical simulation and field monitoring will be used. Firstly, the strength accumulated weakening law and destruction again of anchorage bearing structure with weak cementation fissure will be revealed by Based on the fact which soft-rock roadway surrounding rock has been damaged before carrying out bolt support, it will be studied that the accumulated damage process, stability increasing and loss stop mechanism of anchorage bearing structure with weak cementation fissure. The integrated research method such as Lab experiment, theoretical analysis, numerical simulation and field monitoring will be used. Firstly, the strength accumulated weakening law and destruction again of anchorage bearing structure with weak cementation fissure will be revealed by lab experiment. Secondly, it will be studied that the effect law which fissures with different distribution forms and anchorage parameters on the strength and deformation of bearing structure. Thirdly, the accumulated damage index which covers fissures distribution characteristics and anchorage parameters will be established for quantificationally analyzing accumulated damage process and instability characteristics. At last, the accumulated weakening key point and weak stability position will be analyzed and confirmed. The structure compensation theory will be proposed and it contains the compensation measures, time and position. Meanwhile, field monitoring method will be used for reveal the load relation between the basic support with compensation support body, and expound the stability increasing and loss stop mechanism for compensation body on bearing structure.

基于锚杆支护实施前巷道围岩已破坏的事实，以及锚固范围内裂隙为泥质弱胶结或无胶结的状态，针对此状态下的锚固承载结构，采用实验室试验、理论分析、数值模拟和现场监测的综合研究方法，研究承载结构的累积损伤过程，以及增稳止损对策和作用机制。首先，揭示含弱胶裂隙锚固承载结构强度累积弱化规律和再破坏特征；其次，研究不同分布形态的单一弱胶结构面，以及锚杆直径、布锚密度、锚固长度和锚固层厚度等锚固参数，对承载结构强度和变形累积损伤特征的影响；再次，建立涵盖弱胶结裂隙面分布特征和锚固参数的累积损伤指标，定量分析承载结构的累积损伤过程和失稳特征；最后，确定含弱胶裂隙锚固承载结构强度累积弱化关键点和弱稳定性部位，提出承载结构补偿原理，以及涵盖补偿措施、补偿时机和补偿位置的补偿原则，并结合支护体实际荷载监测结果，揭示补偿体与基本支护之间的荷载关系，阐述补偿体对承载结构的增稳止损作用机理。

在锚杆支护实施前，高应力软岩巷道浅表围岩在开挖扰动作用下已逐渐破坏，且裂隙多为泥质弱胶结或无胶结条件，直接决定岩体稳定特征和锚杆索受力状态。因此，本项目以含弱胶结构面岩体与锚杆形成的锚固体为研究对象，采用实验室实验、理论分析、数值模拟和现场监测的等研究方法，揭示了含弱胶裂隙锚固体在三轴加载条件下的强度累积弱化规律和再破坏特征，获得了锚固参数对其强度和破坏特征的影响规律。将含弱胶裂隙锚固体视为一种等效复合材料，以满足特定莫尔-库伦强度准则为基本假设条件，选取含弱胶裂隙锚固体等效内聚力为强度参数、塑性剪应变为塑性参数，建立了涵盖锚固参数的含弱胶裂隙锚固体强度累积弱化模型，定量分析了锚固体强度弱化过程。并结合现场实测数据，揭示了含弱胶裂隙锚固体锚杆轴向荷载和弯矩变化规律，以及两者与结构内部累积变形之间的关系，提出了含弱胶裂隙锚固承载结构补偿原理，以及涵盖时空关系的补偿原则，揭示了结构补偿措施对承载结构的增稳止损作用。研究结果表明：含弱胶裂隙锚固体等效内聚力呈现上升、稳定和下降的三阶段变化规律，并在稳定期内出现多峰值波动特征；随着锚杆间排距增大，上升阶段等效内聚力与塑性剪应变的关系逐渐由线性转变为非线性关系，稳定阶段的多个峰值均出现不同程度减小，且峰值波动幅度逐渐增大，下降阶段均为近似的抛物线函数关系；随着锚杆预紧力增大，等效内聚力在其上升阶段与锚杆预紧力成正比例关系，在稳定阶段，当锚杆预紧力小于某一值时，等效内聚力变化趋势与塑性剪应变成正相关关系，预紧力继续增加，则转变成了负相关关系；在锚固承载结构弱化失稳过程中，确定其强度衰减关键点，并针对由自身强度和结构形式决定的弱稳定性部位，采用补偿体为承载结构提供一定补偿力，提高承载结构极限强度和对深部岩体的承载能力，限制承载结构内破裂岩体剪切滑移变形，以及承载结构的整体内移变形，减小承载结构不均匀变形程度，提高承载结构的整体稳定性。