新建盾构隧道施工次序对近接上跨既有隧道变形影响研究

Study on the Influence of Newly-built Shield Tunneling Sequence on the Deformation of Adjacent and Upper Span Existing Tunnels

针对某城市拟建地铁6号线近接上跨既有4号线形成的特殊叠置工况,建立描述近接上跨特殊叠置工况的三维数值模型,分析拟建隧道左右线施工次序对既有隧道衬砌结构的变形影响。结果表明:1)先左后右施工方案中,既有线隧道距交叠处20 m范围内为近接施工强影响区,先右后左施工方案中,既有线隧道距交叠处25 m范围内为近接施工强影响区;2)不同施工方案下施工影响及变形的时空分布规律较为相似,既有隧道整体向新建隧道侧变形;3)从既有线位移影响大小及范围来看,上跨近接距既有线远侧的线路先施工,近侧的线路后施工对既有线的位移影响更小。

In view of the special superposition condition formed by the proximity of the proposed Metro Line 6 to the existing Line 4,a three-dimensional numerical model is established to describe the special superposition condition of the proximity of the proposed Metro Line 6 to the existing Line 4.The influence of the construction sequence of the left and the right lines of the proposed tunnel on the deformation of the existing tunnel lining structure is analyzed.The results show that:1)In the left to the right construction scheme,the area within 20 m of the existing line tunnel from the intersection is the area with strong impact of adjacent construction;in the right to left construction scheme,the area within 25 m of the existing line tunnel from the intersection is the area with strong impact of adjacent construction;2)The space-time distribution rules of construction impact and deformation under different construction schemes are relatively similar,the existing tunnel is deformed towards the side of the new tunnel as a whole;3)From the perspective of the magnitude and scope of the displacement impact of the existing line,the upper span near the line far from the existing line shall be constructed first,and the construction of the line near the line will have less impact on the displacement of the existing line.