基于变形控制的预应力锚杆复合土钉支护协同作用机理研究及其参数反演

Anchor composite soil nailing support is the most commonly used form, but at present， the research about the synergy of deformation control mechanism is not sufficient, and which impacts on the reliability of the design theory. This topic proposed to reveal the displacement field coupling load transfer law of anchor composite soil nailing support, under the excavation unloading conditions from macro and microscopic Angle, by particle image experiment, excavation unloading platform experiment and mesoscopic numerical simulation study, and to reveal the corresponding relation between the displacement vector mesoscopic transmission of soil, mechanical mechanism and the slope deformation, to explore the load transfer synergies from the rod body stress to the soil displacement field. The synergy model will be established Within the framework of the deformation control and bearing capacity limit. And through the field monitoring, the parameters threshold, such as the anchor prestress and soil nail parameters, will be back- analyzed to be accordant with the monitoring data to further improve the practicability of the model. The research results have important theoretical significance and practical value to clarify the corresponding laws of the anchor and soil nail's load and displacement, and to deepen the mechanism cognition of the anchor composite soil nailing support, and to establish the more actual design model.

锚杆复合土钉支护是国内最常用的基坑支护形式之一，但目前对该种支护中锚杆与土钉的协同机理及变形控制的研究还很欠缺，直接影响了其设计理论的可靠性。本课题拟通过粒子影像实验、基坑卸荷平台实验及细观数值仿真研究，从宏细观角度，揭示开挖卸荷条件下锚杆复合土钉支护位移场和荷载耦合传递规律，以及土体细观的位移矢量传递方式、力学机制与基坑坡体变形的对应关系，探索荷载从杆体应力向土体内传递及与位移场相互协同转化的机制。在满足变形控制与承载力限值框架内，构建基于变形控制的锚杆复合土钉协同作用模型。并通过现场监测，对模型中的锚杆预应力、土钉内力等参数进行反分析研究，反演出符合现场位移监测信息的参数阈值，进一步完善该模型的实用性。该研究成果对于阐明锚杆和土钉的荷载传递与位移的对应规律，深化锚杆复合土钉支护的机理认识、建立更符合实际要求的设计模型具有重要的理论意义和实用价值。

锚杆复合土钉支护是国内最常用的基坑支护形式之一，但目前对该种支护中锚杆与土钉的协同机理及变形控制的研究还很欠缺，直接影响了其设计理论的可靠性。本课题通过粒子影像实验、基坑卸荷平台实验及细观仿真，系统地揭示了开挖卸荷条件下锚杆复合土钉支护协同作用机制。本课题研究成果主要有：（1）通过三维卸荷模型试验，模拟现场开挖工况，建立构件内力与土体位移的对应关系，并提出了以位移为控制指标的锚杆预应力的阈值。（2）通过土体位移粒子影像室内试验结合细观仿真，建立了界面应力扩散的细观模型，通过拉拔锚杆过程中位移场分布和应力场规律，提出了锚杆与土钉存在协同作用时的间距参数。（3）通过理论分析建立了基于位移控制的锚杆复合土钉协同作用模型，根据研究结果及理论分析，系统的提出了锚杆复合土钉的布置方式及预应力取值及自由段长度等参数。研究成果对指导锚杆复合土钉支护的设计具有理论意义和实用价值。