武汉青山长江公路大桥主桥边跨结合梁施工技术

武汉青山长江公路大桥主桥为主跨938m的双塔双索面全飘浮体系斜拉桥,单侧边跨结合梁长368m,由钢槽梁与预制混凝土桥面板通过湿接缝及剪力钉结合而成。其中,钢槽梁宽48m,桥中线处梁高4.06m;预制混凝土桥面板最大单块尺寸10.135m×3.2m×0.37m,重34.2t。边跨结合梁施工采用先顶推架设钢槽梁,再安装预制混凝土桥面板,最后浇筑湿接缝的整体施工方案。钢槽梁节段由浮吊吊装至主墩墩旁托架平台,依次拼装焊接3个节段后由主墩托架平台往边跨方向顶推架设;混凝土桥面板采用工厂化预制,采用50t全回转架板吊机由主墩往边墩方向逐块吊装;桥面板架设后,浇筑湿接缝混凝土,完成结合梁结合施工。施工过程中采取了临时支点同步下落、墩顶钢梁横向压载、辅助墩支点顶落梁等质量控制措施。

Construction Techniques for Side Span Composite Girder of Main Bridge of Qingshan Changjiang River Bridge in Wuhan

The main bridge of Qingshan Changjiang River Bridge in Wuhan is a full floating system cable-stayed bridge with a main span of 938 m,consisting of double pylons and double cable planes.The length of unilateral side span composite girder is 368 m,and the girder is comprised of steel groove girders and precast concrete bridge deck slabs by shear studs and wet-joints.The width of the steel groove girder is 48 m and the height of the steel groove girder at bridge centerline is 4.06 m.The maximum size of precast concrete bridge deck slabs are 10.135 m×3.2 m×0.37 m and the weight is 34.2 t.The construction scheme of the side span composite girder is as follows:the steel groove girders are erected using incremental launching method firstly,then the precast concrete bridge deck slabs are installed,finally the wet-joints will be poured.The steel groove girder segments are lifted to the pier-side brackets of main pier by floating crane,thereafter,the 3 segments being successively assembled and welded are erected by pushing from the pier-side brackets of main pier to side span.The concrete bridge deck slabs were prefabricated in factory,and erected from the main pier to side pier gradually by a 50 t full slewing crane.After the concrete bridge deck slabs are installed,fresh concrete is poured in wet-joint to complete the construction of composite girder.Construction quality control measures,including sinking the temporary fulcrum synchronously,lateral loading on the steel girder at the piers,jacking-up and falling-off the girders at the auxiliary piers,are taken in the construction procedure.