武汉鹦鹉洲长江大桥南锚碇基础设计

Design of South Anchorage Foundation of Yingwuzhou Changjiang River Bridge in Wuhan

武汉鹦鹉洲长江大桥主桥为三塔四跨结合梁悬索桥，加劲梁跨径布置为（200＋2×850＋200）m。该桥南锚碇基础经多方案比选采用圆形嵌岩地下连续墙基础。地下连续墙外径68m、壁厚1．5m，底板厚6m，顶板厚14．5m。导墙由2个L形钢筋混凝土墙组成，墙间距1．6m；帽梁总宽4．0m、高2．5m；内衬厚1．5～2．5m；在地下连续墙外围设置环形防渗帷幕。采用“理正深基坑软件”分析地下连续墙施工全过程的受力，进行结构配筋。采用软件FLAC3D建立基坑及周围土体三维模型，分析基坑开挖对长江大堤变形的影响，分析结果表明，正常施工时，周边建筑及长江大堤的安全可以得到保证。

The main bridge of Yingwuzhou Changjiang River Bridge in Wuhan is a three-tower and four-span composite girder suspension bridge with span arrangement for its stiffening girder being （200＋2 × 850＋200） m. After comparison of different design proposals, it was determined that the rock socketed circular diaphragm wall would be used for the south anchorage foundation of the bridge. The outer diameter of the diaphragm wall is 68 m, the thickness of the wall is 1.5 m, the base plate is 6 m and the top plate is 14.5 m. The part of the pilot wall is formed by two L-shape reinforce concrete walls having a spacing distance of 1.6 m. The total width of the capping beam is 4.0 m and the depth is 2.5 m and the thickness of the inner lagging is 1.5-2.5 m. At the outside of the diaphragm wall, the circular cut-off curtain was arranged. The Lizheng Software for Deep Foundation Pits was used to analyze the force conditions of the whole construction process of the diaphragm wall and to determine the reinforcement arrangement of the structure. The software FLAC3D was used to set up the three-dimensional models for both the foundation pit and the earth around the pit and to analyze the influence of excavation of the pit on the deformation of the river dyke. The results of the analysis indicate that in the case of normal construction, the safety of the ambient buildings and the river dyke can be guaranteed.