微型抗滑桩加固边坡力学机制与稳定性研究

Surface deformation, landslides and other geological disasters occur frequently not only disturbed the route operation of the mine, but also threated the lives and safety of workers. Relatively simple, fast, environmental-friendly and economic micropiles for slope stabilizing will be investigated in this research project. Model tests, numerical analyses and field tests are used to clarify the anti-sliding mechanism of micropiles, so as to establish a method to caculate the performance of the micropiles and evaluate the stability of micropiles-reinforced slopes considering the static and dynamic response. Three-dimensional group effect and knot effect will be analyzed on the basis of comprehensive measurements of displacement and stress of the reinforced slopes. The anti-sliding mechanism of micropiles will be revealed systematically in this research project, considering different factors such as pile diameter, pile length, micropile spacings in a line, micropile spacings in a row, micropiles inclination with regard to the vertical axis, pressure of grouting, types of the cap beam, soil type and loading mode. A model for analyzing the bear capacity and inner force of micropiles in slope stabilising will be estabilished based on the simplification criterion. Several destructive tests also will be performed to make clear the failure mode of reinforced slope and its governing laws. The special attention is paid to set up the evaluation standard of micropiles-reinfoced slope failure, then a mutiple evaluation method will be proposed considering the qualitative investigation and quantitative analysis simultaneously. Finally, large scale field tests will be carried out to validate the proposed method. It is expected that, the results of this project will provide an useful basis for the design and stability analysis of slopes reinforced by micropiles. Therefore, it is decisive significance for the slopes of the open pit mining and external waste dump in emergent circumstances.

本项目针对露天矿采场与排土场中滑坡及地表变形等灾害，以施工快捷、操作灵活、低成本的微型抗滑桩为对象，采用理论分析、模型试验、数值分析以及现场试验相结合的研究方法，探讨微型抗滑桩加固边坡的力学机制与失稳判据等重要科学问题。通过研究静动力条件下微型抗滑桩加固边坡的力学特征，辨识“群桩效应”和“网状效应”等三维效应的形成条件及演化规律，分析多种因素影响的内在机理，建立微型抗滑桩加固边坡体系的承载力和力学分析模型，提出相应的计算方法，并开发相应的计算程序；基于不同条件的破坏性试验结果，研究微型抗滑桩加固边坡的失稳判据，提出微型抗滑桩加固边坡稳定性的多元评价模型和方法，并进行现场试验验证。本项目是在露天矿边坡工程实践中凝练出的课题，创新点明确，研究成果对揭示微型抗滑桩加固边坡的破坏规律、工程结构设计以及安全评价具有指导作用，对于露天矿采场及排土场等边坡变形的快速加固具有重要的理论意义和应用价值。

项目以微型抗滑桩加固边坡力学机制与稳定性研究为对象开展工作。主要成果包括: (1)自主研发了大型多功能露天矿边坡模型试验系统，本系统包括框架式试验台架、地下水模拟装置、双向加载装置、组合式边坡模型开挖装置、凹凸边坡模型制作装置、低温模拟装置等；(2)开展了单根微型桩在横向滑体变形作用下承载力现场试验和微型桩加固边坡底摩擦试验，结合数值模拟结果，以桩身弯矩、剪力和结构位移等为控制条件，提出了确定微型桩加固土质边坡极限抗力的分析方法；(3)基于非接触摄影测量技术和Monte-Carlo原理提出了一种岩质边坡结构面三维随机网络模拟方法，为边坡岩体三维强度确定、尺寸效应分析以及节理岩体边坡的物理模拟试验提供理论依据；(4)运用自主研发的边坡模型试验系统完成了不同间距微型桩加固土质边坡模型试验，结合数值分析成果，探讨了微型桩-土极限水平接触反力及体系形成三维复合体的临界桩间距；(5) 基于破坏性试验结果和数值模拟结果，提出了微型桩群加固边坡稳定性的耦合评价方法，并研究了削剪效应对微型桩加固边坡稳定性的影响。