营盘路湘江隧道分岔大跨段地表沉降分析

Ground surface settlement analysis on the large-span section of Xiangjiang River Crossing Tunnel on Yingpan Road

以长沙市营盘路湘江隧道西岸北线分岔大跨段工况为实例,运用有限元软件MIDAS-GTS对大跨段进行全施工阶段三维数值模拟分析,得出结论:采用双侧壁导坑法能够有效的控制地表沉降;在两侧导坑开挖完成后,先施作导坑部分二衬再进行中部土体的开挖支护及二衬施工产生的最终地表沉降比隧道开挖完成后再施作整体二衬产生的地表沉降小的多,说明前者能够更有效的控制最终地表沉降;临时支护的拆除对地表沉降影响较大,实际施工过程中,建议紧密结合现场监控量测数据来确定拆除临时支撑的时机。

Taking the large - span section on the west shore of the north tube of Xiang jiang River Crossing Tunnel on Yingpan Road in Changsha City for exam- pie, a three - dimensional numerical model of the construction stage （ including the secondary lining construction） was established by using finite element soft- ware MIDAS- GTS, and the results show that：The ground surface settlement has been controled Effectively by using the Double wall pilot tunnel meth- od. Constuct the secondary lining of the pilot after excavating the double wall pilot, comparing with constuct the secondary lining of whole tunnel, the first situa- tion making less ground surface settlement. The removal of temporary support make larger influence on ground surface settlement. This papper suggest that de- termining the timing of the removal of temporary support closely combining with the field data in the actual construction.