盾构隧道上跨施工对既有隧道变形的影响研究

Research on the influence of overcrossing shield tunnel construction on the deformation of existing tunnels

文章针对昆明新建地铁4号线双线盾构隧道上跨既有6号线双线隧道,形成两层四线叠交的特殊工况,采用三维有限元数值模拟和现场监测相结合的方法,研究盾构上跨施工引起既有隧道纵向位移的变化规律,并分析土仓压力、注浆压力及径向环形注浆加固对既有隧道变形的影响。研究结果表明:盾构二次穿越对既有隧道的影响小于盾构单次穿越;新建隧道与既有隧道的夹角越小,既有隧道受新建隧道施工的影响越大;既有隧道的竖向位移不随土仓压力的改变而变化,但随注浆压力的增大而减小;采取对既有线周围土体进行径向环形注浆加固的方式可显著减小既有线隧道管片的变形。研究成果可为同类型地质条件下多线叠交盾构施工设计以及隧道加固技术提供一定的理论依据。

Aiming at the special working conditions of the newly built Line 4 double-line shield tunnel overcrossing the existing Line 6 double-line tunnel in Kunming Metro,forming a two-layer four-line overlap,a method of combining three-dimensional finite element numerical simulation and on-site monitoring was used to study the change rule of the longitudinal displacement of the existing line caused by the overcrossing shield construction,and the effects of the chamber earth pressure,grouting pressure and radial annular grouting reinforcement on the deformation of the existing tunnel.The results show that the effect of the second crossing of the shield on the existing tunnel is less than that of the single crossing of the shield;the smaller the intersection angle between the new tunnel and the existing tunnel,the greater the impact of the construction of the new tunnel on the existing tunnel;the vertical displacement of the existing tunnel does not change with the change of the chamber earth pressure,but decreases with the increase of the grouting pressure;adopting the method of radial annular grouting reinforcement to the surrounding soil body can significantly reduce the deformation of the existing tunnel segment.The research results can provide a certain theoretical basis for the design of multi-line overlapped shield tunnel construction and the tunnel reinforcement technology under the same geological conditions.