大直径盾构隧道下穿河道护岸结构影响数值分析

Numerical Analysis of the Impact of Large-diameter ShieldTunneling Crossing under Riverbank Retaining Structures

如何保证大直径盾构隧道安全地穿越河岸护岸桩,是沿海及水系发达城市修建隧道面临的一项关键问题。针对深圳市望海路隧道下穿中心河护岸结构,通过数值模拟分析大直径盾构隧道施工对河道护岸桩的影响,结果表明:(1)盾构隧道开挖到距离护岸桩前10 m位置时,护岸桩开始出现水平方向位移,位于隧道边缘上方的护岸桩水平位移大于隧道中线上方的桩,最大位移3.75 mm。(2)隧道中线位置开挖土体较多,其上方的护岸桩竖向位移较大,为7 mm,靠近隧道边缘,开挖的土体较少,上方的桩竖向位移相对较小,为3 mm。(3)盾构隧道掘进到护岸桩下方,桩的位移迅速变大,隧道完全掘进通过护岸桩下方,桩的位移趋于稳定,盾构穿越护岸桩的过程在施工中需要重点监测。

How to ensure the safe crossing of large diameter shield tunnel through riverbank pile retaining structures is a key issue faced by coastal and waterway-rich cities when constructing tunnels.Taking the Shenzhen Wanghai Road Tunnel as an example,this paper analyzes the influence of large diameter shield tunnel construction on riverbank pile retaining structures through numerical simulation.The results show that:(1)The pile retaining structure begins to show horizontal displacement when the shield tunnel is excavated to a distance of 10 m from the pile.The horizontal displacement of the pile located above the tunnel edge is greater than that above the tunnel centerline,with a maximum displacement of 3.75 mm.(2)The vertical displacement of the pile retaining structure above the tunnel centerline is larger due to the excavation of more soil above the tunnel centerline.The maximum vertical displacement of the pile above the tunnel centerline is 7 mm,while the vertical displacement of the pile above the tunnel edge is relatively smaller,at 3 mm.(3)As the shield tunnel is excavated below the pile retaining structure,the displacement of the pile rapidly increases.As the shield tunnel is completely excavated below the pile retaining structure,the displacement of the pile stabilizes.The process of shield crossing the pile retaining structure needs to be closely monitored during construction.