超低净空桩基托换和拔桩清障施工技术研究

Research on Construction Technology of Ultra-low Clearance Pile Foundation Underpinning and Obstacle Removal by Pulling Piles

为实现既有桥梁超低净空桩基托换和拔桩清障,以浦东机场南回转匝道为研究背景,提出了一种超低净空桩基托换和拔桩清障施工技术。应用有限元软件模拟复杂托换结构体系,验证了超低净空桩基托换和拔桩清障施工方案的可行性;针对超低净空边界,采用PLC同步顶升技术,将无法通过常规吊装就位的钢托架安装到最终设计高度;为确保桥梁受力体系不受影响,原位顶升托换连续箱梁,采用钢抱箍体系,解决新建桥墩接高技术难题;采用自行研发的履带式升降拔桩机,配合模块式钢护筒,解决超低净空拔桩清障和施工工效问题;施工全过程采用实时监测技术,保证基本不断交条件下的结构稳定及安全。实践总结的经验,可为类似工程提供借鉴。

To achieve ultra-low clearance pile foundation underpinning and removing obstacle removal by pulling piles for existing bridges,a construction technology is proposed,using the south turning ramp of Pudong Airport as the research background.Finite element software is used to simulate the complex underpinning structure system to verify the feasibility of the ultra-low clearance pile foundation underpinning and the construction scheme of removing obstacles by pulling piles.In order to ensure that the stress system of the bridge is not affected,the steel hoop system is used to solve the technical problem of new pier connection by in-situ jacking and underpinning of continuous box girder,and the self-developed crawler-type lifting pile extractor is used to solve the problems of ultra-low clearance pile removal and construction efficiency by cooperating with modular steel casing.The real-time monitoring technology is used in the whole construction process to ensure the stability and safety of the structure under the condition of continuous construction.The experience summarized from practice can provide reference for similar projects.