盾构区间隧道下穿暗渠施工稳定性分析

Stability Analysis of the Shield Tunnel Passes Through the Culvert

当盾构区间隧道近距离下穿暗渠时,施工会引起较大的土体变形和位移,加大了施工过程中的风险,也对项目自身以及沿线暗渠安全产生一定的影响。以青岛某地铁盾构区间隧道下穿暗渠为背景,通过建立三维有限元模型,评估了下穿河流过程中施工的稳定性,同时结合盾构下穿暗渠的施工工艺,对土体位移、管片变形、暗渠变形的规律进行了研究。研究结果表明:在双线隧道开挖过程中,地表竖向位移和水平位移均较小,最大地表沉降发生在双线隧道的上部区域,最大地表水平位移发生在隧道左侧;左、右线管片整体上浮,其中右线管片上部变形大于左侧管片的上部变形,但变形趋势大致相同,均呈对称分布,最大竖向位移出现在2个管片的正上部位置,位移值均较小;暗渠最大的竖向位移和水平位移发生在暗渠的中部、盾构隧道的上部,但管片竖向位移与水平位移均较小。该工程的地表沉降、管片变形和暗渠变形均满足施工规范要求,因此下穿暗渠的施工是可行的。该研究结果可为类似盾构区间隧道下穿暗渠的施工提供参考和借鉴。

When the tunnel in the shield section passes through the adjacent culvert,the construction will cause large soil deformation and displacement,which increases the risk in the construction process,and also have a certain impact on the safety of the project itself and the culverts along the line.Based on the background of the underpass culvert of a shield tunnel in Qingdao,the stability of the construction in the process of crossing the river was evaluated by establishing a 3D finite element model.Combined with the construction technology of the shield underpass culvert,the soil displacement,segment deformation and the culvert deformation were studied.The results show that the vertical displacement and horizontal displacement of the surface are smaller,and the maximum surface settlement occurs in the upper area of the double-track tunnel,and the maximum horizontal displacement occurs on the left side of the tunnel during the excavation of the double-track tunnel;The left and right segments totally float upwards,and the deformation of the upper part of the right segment is greater than that of the left segment.But the deformation trend is about the same with symmetrically distributed.The maximum vertical displacement appears in the upper part of the two segments,and the displacement values are also smaller;The maximum vertical and horizontal displacement of the culvert occur in the middle of the culvert and the upper part of the shield tunnel,but the vertical and horizontal displacement are smaller.All the surface settlement,segment deformation and culvert deformation of the project meet the requirements of the construction specification.The underpass construction is feasible.The results can provide a reference for the construction of tunnels under similar shield tunnels.