武汉二七长江大桥5号主塔墩基础施工

Construction of Foundation of Pylon Pier No.5 of Erqi Changjiang River Bridge in Wuhan

武汉二七长江大桥为主跨616m三塔结合梁斜拉桥。5号墩为边主塔墩，共28根直径为2．8m的钻孔灌注桩，其地处岸边块石抛填防护带，深埋承台8～12m，在确保岸滩稳定的前提下，针对钢护筒插打、建立钻孔平台；利用枯水期先安装钢板桩围堰内支撑到位，以便钢板桩插打和钻孔桩施工同步进行；承台施工等过程，以及施工工期紧，上游侧有码头、北侧有加油船未搬迁，作业面狭小等难点，重点介绍在有限施工条件下，利用雪浪号400t全回转吊船，大吨位起吊安装围堰内支撑和钻孔桩施工平台的方案，以及5号墩基础施工过程中的重点、难点，探讨此类工程有效的施工方式、方法。

Erqi Changjiang River Bridge in Wuhan is a three-pylon composite girder cablestayed bridge with two main spans each 616 m. The Pier No. 5 of the Bridge is the side pylon pier that is arranged with totally 28 nos. of 42.8 m bored piles. The pier is located in the riprapped protection area nearby the river bank and has a pier base to be deeply embedded 8-12 m in the ground. On the prerequisite that the stability of the bank shoal can be ensured and in the light of the construction process of inserting and driving in the steel casings for the bored piles, setting up the working platform for the boring construction, installing the internal bracing system of the steel sheet pile cofferdam in place first by taking the advantage of the dry water period so that the construction of the sheet piles and bored piles can be carried out in parallel, carrying out the construction of the pier base and the challenge of the tight construction schedule and restricted working area since there are a wharf upstream and the fuelilling ships downstream not yet moved away, the corresponding construction schemes are carefully prepared. The schemes for lifting and installing the internal bracing system and the working platform in large tonnage, using the 400 t Snow Wave fully rotary lifting vessel, the key and difficult points in the construction of the foundation of the pylon pier are mainly presented herewith and the effective ways and methods for construction of such type of the foundations are also discussed.