基于杆系单元法的基坑三排桩支护结构简化计算方法

Simplified calculation method of three-row pile retaining structure of foundation pit based on the bar system element method

三排桩作为一种新型支护结构,相较一般的支护形式具有较大的侧向刚度以及抗倾覆能力,因此在一些安全要求较高的基坑工程中已有应用,但因其缺乏系统的计算方法和理论研究,给工程设计和建设带来了一定的困扰。以双排桩中常用的桩土相互作用模型和土压力分配模型为切入点,结合现行技术规程,通过对三排桩的结构受力机理进行探讨分析,分别建立了三种针对三排桩的平面杆系有限元模型,结合具体的算例,对这三种模型的合理性加以验证,研究了不同模型下三排桩支护结构的内力与变形规律,并对这三种模型的适用范围进行了探讨,同时在规程模型和桁架模型两种桩土相互作用模型的基础上,研究了桩间土压缩性能对支护结构内力及其变形的影响,旨在为基坑三排桩的工程应用提供一定的参考。

As a new type of support structure,three-row piles have greater lateral stiffness and anti-overturning ability than ordinary support forms,so they have been used in some foundation pit projects with higher safety requirements.However,due to the lack of systematic analytical methods and theoretical research for the analysis of three-row piles,this has brought some problems to the engineering design and construction.based on the pile-soil interaction model and the soil pressure distribution model commonly used in double-row piles,combined with current technical specification,through the discussion and analysis of the mechanism of the structure of three-row piles,three kinds of plane bar system finite element models for three-row piles are established respectively.Combined with specific examples,the rationality of these three models is verified,the internal force and deformation laws of the three-row pile retaining structure under different models are studied,and the application scope of these three models is discussed.At the same time,based on the code model and truss model,the influence of soil compression performance between piles on the internal force and deformation of supporting structure is studied,in order to provide some reference for the engineering application of three rows of piles in foundation pit.