武汉鹦鹉洲长江大桥北锚碇施工变位分析

武汉鹦鹉洲长江大桥主桥为3塔4跨悬索桥，其北锚碇采用圆形沉井形式，施工前在周围预先制作圆形地下连续墙。考虑到沉井下沉对邻近建筑物和构筑物的影响，根据沉井施工工况，结合现场实测监控数据，采用MIDAS-GTS建立三维计算模型进行有限元分析，主要讨论三维计算模型所得关键测点的位移值与实际测量值的吻合情况，在指导现阶段施工的同时，预测后续工况对周围建筑及长江大堤的影响，同时先后分析沉井下沉过程对圆形地下连续墙变形的影响。计算结果表明，关键测点的变形计算值与实测值结果比较吻合，计算误差基本在5%~30%，施工可有效地避免对周围建筑物和长江大堤不利影响；地下连续墙变形会随沉井下沉而增大，但收敛趋势明显。该计算模型对沉井下沉的姿态控制具有参考价值。

Research on construction displacement of north anchorage caisson of parrot cay Yangtze River bridges in Wuhan

The main bridge of Yingwuzhou Yangtze River bridge is a three-towers and four-spans suspension bridge, for which north anchorage adopted circular caisson. A diaphragm wall was built surround the caisson before the caisson construction. According to the construction condition and the effect of caisson sinking to adjacent buildings, three dimensional calculation modes were established by MIDAS-GTS combined filed monitor data. It was mainly discussed the displacements agreement between calculation values and filed monitor data through some key points, and analyzed the effect of caisson sinking to diaphragm wall. It provided guidance to practice construction in order to predict the effect of follow conditions to adjacent buildings and the Yangtze River levee. The results show that: simulation results agree well with in-situ measurement; the errors are mostly among 5%-30%; and the adverse effects of construction can be effectively avoided to the adjacent buildings and levee; the deformation of diaphragm wall increases with the increase of sinking length; but the effect is more and more small. The calculation model will provide references in control of caisson sinking.