浅埋暗挖大跨黄土隧道下穿地下行包通道沉降分析及对策

机场地下行包通道沉降控制要求高，且不能中断运行，新建浅埋暗挖大跨黄土隧道下穿施工风险高，施工不当会引起地下行包通道沉降、变形，甚至引起混凝土结构开裂。为找出下穿隧道施工过程中引起通道底沉降的关键步序，更好地控制沉降，采用三维数值模拟方法对新建隧道下穿机场地下行包通道进行了沉降分析，并通过在隧道开挖过程中洞内采用分步开挖、大直径管棚超前预支护、初期支护和二次衬砌背后回填压浆等沉降控制措施，将通道底板沉降控制在3 mm左右，并在施工过程中加强监测，能够保证既有地下行包通道的结构安全。

Settlement Analysis on and Countermeasures for Shallow-covered Large-span Loess Tunnel Constructed by Mining Method Crossing Underneath Baggage-dedicated Gallery of Airport

The settlement, deformation and concrete structure crack, may occur to the gallery due to the high construction risk and irrational construction of the shallow covered large span loess tunnel. In this paper, in order to satisfy the requirements of the baggage dedicated gallery and to control the settlement, 3D numerical simulation method is used to analyze the settlement caused by new tunnel crossing underneath baggage dedicated gallery of the airport. In addition, some effective measures, such as strengthening the monitoring and using effective technologies (including excavation step by step, advance support by means of large diameter pipe roof and grout backfilling behind primary support and secondary lining) have been adopted to minimize the settlement of the baggage dedicated gallery. The settlement of the gallery floor is limited to about 3 mm, which guarantees the safety of the baggage dedicated gallery.