微型桩组合抗滑结构及其设计理论

 微型桩具有诸多施工优势，近年来正不断推广应用于滑坡治理工程，并取得了较好的工程效果。但由于理论研究严重滞后，急需开展相应研究，为工程提供理论支持和技术服务。边坡岩体的工程地质条件是很复杂的，应针对坡体地质特征选择不同的微型桩组合结构。按照微型桩在坡体的设置位置总结出3种类型的微型桩组合抗滑结构，即坡面加固型、平台加固型和坡脚加固型，对每种类型又给出几种组合结构形式，讨论这些结构在设计计算时应考虑的一些关键问题以及适用条件。在这些结构中，具有顶梁固定微型桩的组合结构在工程中应用较多，按照桩–土相互作用原则讨论这种组合结构的抗滑机制。结果表明，微型桩组合结构除了可增强滑面的抗剪强度外，桩与土形成的抗滑体的抗滑机制不同于一般的抗滑桩，其抗滑效果不是由桩的整体抗弯能力来实现的，而是通过发挥微型桩的抗拉强度和桩土地基承载力的优势来抵抗滑坡推力的。为了求出桩的轴力，按照横向约束的弹性地基梁法提出了设计计算理论，并结合具体工程给出设计计算方法，得出了较为合理的计算结果。

MICRO-PILE COMPOSITE STRUCTURE AND ITS DESIGN THEORY

Micro-pile composite structure has been widely applied to landslide treatment engineering due to its many advantages；and the engineering effect is very evident. But at present，few researches on the anti-sliding mechanism of the structure have been done. In order to provide theoretical support and technique service for the design and construction，the corresponding studies must be urgently conducted. Three types of the micro-pile composite anti-sliding structures have been summarized according to their setting places on the slope，namely，type of slope surface reinforcement，type of slope step reinforcement，type of slope foot reinforcement. Some key problems and applicable conditions are discussed for the design of these structures. Among these structures，the composite structure of micro-pile fixed by the tip beam is usually more adopted in projects. According to the relationship of pile-soil interaction，the anti-sliding mechanism of the composite structure is discussed. The composite structure improves the shear strength of the sliding surface；and the pile-soil system behaves better in anti-sliding effect. The anti-sliding mechanism of the system is not same as the one of the common retaining pile. The anti-sliding effect of the system is achieved by the tensile strength of the micro-pile and the bearing capacity of foundation of soil and pile，but not by the whole bend ability as the common retaining pile. In order to obtain the axial force of the micro-pile，the design theory is put forward according to the method of elastic foundation beam with restriction of transverse deformation. Application of the design theory to a slope project shows that the theory is reasonable and easy.