考虑残余顶推力作用时盾构下穿引起既有顶管管廊变形

针对隧道开挖引起上覆既有顶管管廊变形的工况，提出了一种可考虑顶管管廊残余顶推力的管廊竖向变形理论计算方法。第一阶段采用修正Loganathan公式解得隧道开挖引起周围土体的自由位移，把土体自由位移附加在既有管廊轴线上，第二阶段将既有管廊简化成无限长Euler-Bernoulli梁搁置在Pasternak地基模型上，同时考虑管廊轴力对其变形响应的影响，随后根据管廊两端自由的约束条件提出了隧道开挖引起既有管廊受力变形半解析解。研究结果表明：与某工程实测数据验证对比，本文方法计算结果与实测较为符合；与本文方法退化解析比较，本文方法预测结果更具有优越性。进一步参数得到如下结论：地层损失率的增大会使得既有管廊位移及其内力呈现线性增大的趋势；随着管廊直径的增大，既有管廊位移和弯矩会迅速增大，其增速也在不断增大；随着隧道开挖轴线埋深的增加，既有管廊位移和内力均会大幅度减小。

Study of Deformation of Existing Jacking Pipeline Induced by Tunneling Underlying Considering Residual Jacking force

Aiming at the deformation of the existing pipe gallery caused by tunnel excavation, a theoretical calculation method of vertical deformation of pipe gallery considering residual thrust of pipe gallery is proposed. The first stage, the soil-free settlement caused by tunneling underlying can be calculated by Loganathan function, the additional soil-free settlement upon existing tunnel, the two-stage simplify the existing pipeline as Euler-Bernoulli beam lying on Pasternak foundation model and take the pipeline axis force effect into consideration, then a deformation analytical solution of the existing pipeline can be proposed by the condition with the freedom of two pipeline ends. Studies show: comparing with the measurements, the proposed method solutions have more in accord with the measurements. By comparing with degraded solution based on the proposed method, the prediction of the proposed method has more superiority. Further study shows that both the deformation and bending moment of the pipeline linear increase with the volume loss. With the increase of the diameter of the pipe gallery, the displacement and bending moment of the existing pipe gallery will increase rapidly, and its growth is also growing. As the depth of the existing tunnel centerline increases, existing pipeline deformation and inner force will be decreased greatly.