拱北隧道超大管幕顶进横向地面沉降及管间作用分析

Analysis of Transverse Ground Settlement and Pipe Interaction of Super-large Pipe Roofing in Gongbei Tunnel

为研究小间距圆周群管顶进时的地面沉降规律及顶管间的相互作用,结合港珠澳大桥珠海连接线拱北隧道管幕工程,对群管顶进引起的地面沉降进行分析,确定小间距圆周群管顶进时地层损失率的取值,提出沉降槽宽度系数的经验公式,并通过数值模拟分析先顶管群对后顶管引起地层损失及最大沉降的影响。研究结果表明:拱北隧道管幕工程群管顶进引起的地表沉降满足控制标准要求。随着顶管埋深的增加,单根顶管引起的沉降槽宽度系数随之增大,地表最大沉降量随之减小,顶管顶进时的初始地层损失率为1. 5%。由于顶管顶进技术熟练程度的提高以及先顶管群对土体的加固作用,地表沉降得到有效控制,管幕所有37根顶管顶进结束后的平均地层损失率减小至0. 8%。

In order to study the ground settlement law and the interaction between jacking pipes during small-spacing circumferential group pipe jacking,the ground settlement caused by pipe-jacking is analyzed,and the value of ground loss ratio and the empirical formula of settlement trough width coefficient during small-spacing circumferential group pipe jacking are put forward by taking the pipe-roofing project of Gongbei Tunnel of Zhuhai Connection Line of Hong Kong-Zhuhai-Macao Bridge for example.And then the influence of fore pipe-jacking group on strata loss and maximum ground settlement induced by followed pipe-jacking group is analyzed by numerical simulation.The analytical results show that:(1)The ground settlement caused by the pipe jacking of Gongbei Tunnel is within the control requirements.(2)With the increase of buried depth of the pipe,the settlement trough width coefficient caused by the single pipe increases,while the maximum ground settlement decreases;the initial ground loss ratio during pipe jacking is 1.5%.(3)Due to the promotion of technical proficiency and the reinforcement effect of fore pipe-jacking group,the average ground loss ratio after jacking of all 37 pipes is ultimately controlled to 0.8%,and the ground settlement has been effectively controlled.