上海某地铁上盖项目大桁架下桩基础设计的探讨  

Research on Design of Pile Foundation under the Large-Span Truss of a Subway Superstructure Project in Shanghai

作　　者：孙抒宇 王经雨[1] SUN Shuyu;WANG Jingyu(East China Architectural Design and Research Institute Co.,Ltd.,Shanghai 200002,China)

机构地区：[1]上海华东建筑设计研究院有限公司,上海200002

出　　处：《结构工程师》2022年第6期126-133,共8页Structural Engineers

摘　　要：地铁上盖项目一般具有场地受限、基础沉降控制严格的特点,上海某地铁上盖项目因采用大桁架的方式横跨地铁,上部荷载的集中使得大桁架下桩基础设计更为困难。为解决因场地受限桩间距不满足规范要求的问题,本项目采用一种折算方法考虑这一不利因素,计算表明,桩基侧阻承载力经折减后,仍可满足桩基承载力设计要求。分析本项目沉降产生的主要原因,并依据类似工程的资料和试桩数据,对沉降数据进行了分析和预估。研究表明,本工程钻孔灌注桩沉降的主要原因是桩身压缩引起的沉降;大桁架下柱下桩基的沉降较小,能满足地铁对沉降控制的要求;因场地狭小,大桁架下基础桩数受限致使桩基水平抗力不足时,可在承台设置水平传力板的方式解决过大的水平力。Subway superstructure projects generally have the characteristics of limited site and strict foundation settlement control, which brings great challengers to structural design. What is more, in this project, large-span trusses are used to span the subway station, so the design of the pile foundation under the truss system is much more difficult because of the concentration of the load under the truss. To solve the problem that the pile spacing does not meet the code requirements due to the restricted site, this project adopts a new method to consider this adverse condition. The new method calculation results show that the shaft resistance bearing capacity of the pile foundation can still meet the design requirements after being reduced. The main reasons for the settlement of this project are analyzed. Based on the data such as the test pile results of similar projects, the settlement data is researched and estimated. Research shows that the main reason for the settlement of the cast-in-situ pile comes from the compression deformation of the pile body, the settlement of the pile foundation under the large-span truss is very small, which can meet the requirements of the subway settlement limitation. The number of piles under the truss is limited because of the restricted site, the horizontal bearing capacity of the pile foundation is insufficient, therefore, a horizontal force transfer plate is installed on the cap to solve the problem of the excessive horizontal force.

关 键 词：地铁上盖 大桁架 桩间距 折减系数 沉降控制 水平力 

分 类 号：U231[交通运输工程—道路与铁道工程] TU473.1[建筑科学—结构工程]