穿越既有管线的地下连续墙施工技术研究

Construction Technique for Diaphragm Wall Crossing Existing Pipelines

目的:针对常规的成槽机液压抓斗不能掏挖既有管线下方土体的问题,提出了一种穿越既有管线的地下连续墙施工技术。方法:以天津地铁7号线一期工程兴华道站主体围护结构施工为背景,介绍了改进后的成槽机液压抓斗结构;介绍了改进后的地下连续墙施工工序--槽壁三轴搅拌桩加固、深导墙施工、装配抓斗成槽、钢筋笼分片制作和吊装、混凝土浇筑等的内涵、具体施工过程和施工要点;对比分析了改进后的地连墙施工工序的工程应用效果。结果及结论:该施工技术解决了围护结构施工过程中因遇到切改难度大的既有管线而导致地下连续墙无法施作的难题。工程实践表明,相较于常用的气举反循环绞吸式施工方法,该施工技术能够有效降低施工成本和缩短施工工期。

Objective:In response to the unable excavating the soil beneath existing pipelines problem of conventional trenching machines with hydraulic clamshells,a construction technique for diaphragm wall crossing existing pipelines is explored.Method:Taking the construction of the mainbody retaining structure at Xinghuadao Station of Tianjin Metro Line 7 phase I project as research background,the improved structure of conventional trenching machine with hydraulic clamshells is introduced.The construction process after improvement is introduced:trench wall tri-axial mixing pile reinforcement,deep guide wall fabrication,assembly of clamshell trenching,segmented production and hoisting of reinforcement cages,as well as the connotation of concrete pouring,specific construction process and key points are explained.Engineering application effects of the improved diaphragm wall construction procedures are compared and analyzed.Result&Conclusion:The proposed construction technique addresses the challenge of unable constructing diaphragm walls when it is very hard to cut and modify the existing pipelines during the retaining structure construction process.Engineering practice shows that compared to the commonly used air-lifted reverse circulation suction construction method,this technique effectively reduces construction costs and shortens the construction period.