盾构竖井垂直顶升施工阶段隧道变形分析

Tunnel Deformation in Vertical Jacking Construction Stage of Shield Shaft

针对盾构内垂直顶升诱发的隧道结构变形问题,借助精细的数值计算,探讨盾构竖井垂直顶升阶段衬砌结构和接头变形响应特征,并通过理论计算验证数值模型具备一定的合理性.研究表明,垂直顶升施工影响主要集中在开口环及相邻三环标准环,对隧道底部的影响大于隧道顶部,竖向变形大于横向变形;垂直顶升前期隧道整体下沉,开口环和相邻环收敛变形,顶升后期隧道整体有一定的抬升,开口环和相邻环扩张;环缝接头发生以错台为主的变形,开口环与相邻环之间的错台量最大,且在底部竖向错台最明显;垂直顶升施工引起的隧道最大竖向位移、水平位移、错台量均随顶升反力的增大而同向线性增大.

Aiming at the tunnel structural deformation induced by vertical jacking of shield shaft,numerical simulation was applied to study the characteristics of tunnel lining and joint deformation in vertical jacking stage and verified by theoretical calculation. The results show that the influencing scope of the deformation is manifested on the opening rings and the adjacent three segment rings on both sides. The influence on the bottom of the tunnel is greater than that on the top of the tunnel,and the vertical deformation of tunnel is greater than the transverse deformation. In the early stage of vertical jacking,the tunnel sinks,the opening ring and the adjacent ring converge,while in the later stage of jacking,the tunnel rises to a certain extent,and the opening ring and the adjacent ring expand. The deformation of the circumferential joint is mainly caused by the dislocation,and the dislocation between the open ring and the adjacent ring is the largest,and the vertical dislocation at the bottom is most significant. The maximum vertical displacement,horizontal displacement and dislocation of the tunnel caused by vertical jacking increase linearly with the increase of jacking reaction force.