干燥粉细砂地层大断面隧道施工力学行为分析

Research on the Mechanical Behavior of Large Cross-sectional Tunnel in Dry Silty-fine Sand

大西客运专线上白隧道全长1 717 m,全隧洞身范围均穿越不同厚度的干燥粉细砂层,最大开挖断面187.08 m^2。施工中,针对隧道全断面为干燥粉细砂地层提出了超前水平旋喷咬合桩预加固技术和多台阶预留核心土顺次开挖法,采用三维数值方法从隧道变形、支护结构受力及塑性区分布等方面揭示了全断面为粉细砂层隧道的施工过程力学行为,取得了大量有价值的数据和信息,对指导该隧道的施工具有重要作用。

Shangbei tunnel on Datong-Xi＇ an Passenger Dedicated Line is 717m in length, whose tunneling range through different thickness of the dry powder fine sand layer, with the largest excavation section of 187.08m^2. Pre-reinforeement technology of the horizontal jet grouting secant pile and multi step core soil reservation sequential excavation method of large section was proposed as dry silty-fine sand of full section of tunnel in construction. Analysis and Research on the mechani- cal behavior of dry silty-fine sand of full section of tunnel was revealed by three-dimensional numerical methodfrom the per＊ spectives of tunnel deformation, force on the supporting structure and the plastic zone distribution etc. in which great amount of valuable data and information were acquired. It is of great significance to the construction of the tunnel.