顶管工程中 PC 工法组合钢管桩关键技术研究

Study on Key Technology of PC Composite Steel Pipe Pile in Pipe Jacking Project

摘要:

顶管井施工工艺的选择是顶管设计中的关键，顶管井根据基坑安全等级及环境保护等级，多采用沉井、SMW工法、灌注桩、地连墙等围护形式。PC工法组合钢管桩是一种新型可循环周转的围护形式，具有节约施工工期、不产生泥浆、没有污染、低噪声等优点。对PC组合钢管桩作为围护时的基坑开挖工况中的围护结构变形、顶管顶进工况中的钢支撑受力采用理论计算及现场实测值分析。将PC工法组合钢管桩等刚度拟合为地连墙可基本反映出基坑开挖工况的实际变形，可用于实际工程设计阶段验算基坑变形。在开挖至坑底及施工壁板阶段，围护结构变形最大值的理论值与实测值基本一致，坑底以下围护结构实测值大于理论值。在均匀顶力及偏心顶力两种顶进工况下，顶管洞口上方最近的一道钢支撑体系在顶进工况下安全。

Abstract:

The selection of construction technology of pipe jacking well is the key in pipe jacking design. According to the safety level of foundation pit and environmental protection level, the enclosure forms of open caisson, SMW method, cast-in-place pile and underground diaphragm wall are adopted for the pipe jacking well. The PC composite steel pipe pile is a new type of enclosure form which can be recycled, and has the advantages of saving the construction period, no mud, no pollution and low noise. The deformation of the enclosure structure in the excavation condition of foundation pit and the force of steel support in the pipe jacking condition are analyzed by theoretical calculation and on-site measured value when PC composite steel pipe pile is used as the enclosure. Fitting the stiffness of PC composite steel pipe pile as a diaphragm wall can basically reflect the actual deformation of the foundation pit excavation condition, which can be used for checking the deformation of the foundation pit at the design stage of the actual project. In the stage of excavation to pit bottom and constructing wall plate, the theoretical value of maximum deformation of enclosure structure is basically the same as the measured value, and the measured value of enclosure structure below pit bottom is larger than the theoretical value. Under two jacking conditions of uniform jacking force and eccentric jacking force, a steel support system nearest to the top of pipe jacking opening is safe under the jacking condition.