某地铁车站基坑回筑阶段不同换撑设置情况的对比分析

Retractable Strut Installations During the Backfill of Subway Station Excavations

对苏州轨道交通5号线星塘街车站基坑支撑的竖向设置进行分析,通过计算比较了几种不同支撑+换撑组合方案,结果表明:不同的支撑+换撑方案,支护结构最大变形和最大弯矩出现的工况不同,对特定的地铁车站,只要支护结构最大变形在规定值以内,应尽量减少甚至避免回筑阶段的临时换撑,虽然临时换撑的减少或取消会使支护墙体弯矩增加而导致含钢量增加,但整体造价更省,且在施工便利性和工期方面更具优势,研究可为类似工程提供参考。

During the backfilling of the underground structures for a subway station,if a cross strut needs to be removed,an extractable strut is usually installed below this cross strut.Conventionally,the extractable strut is not optimized for the deformation control.This paper presents a case history of the application of the extractable strut in the supporting of Xingtang Street Station structures for Suzhou Transit Line No.5.The locations of the vertical struts were evaluated.Several different struts plus extractable struts were compared.It is concluded that different strut arrangement resulted in different maximum bending moment and at different locations.For the backfilling of the subway station,the number of extractable struts should be minimized and even avoid as long as the maximum bending moment is within the tolerable limits.Although the reduction of the extractable will result in the increase of the bending moments in the supporting structures and increase the content of steel,the over construction cost is still cost effective.