G3铜陵长江公铁大桥4号主墩基础施工关键技术  

Key Construction Techniques for Foundation of Main Pier No.4 of Tongling Changjiang River Rail-cum-Road Bridge Carrying a Section of G3 Expressway

作　　者：郭尚谦 何明辉[2] GUO Shangqian;HE Minghui(The Fourth Engineering Co.,Ltd.,China Railway Major Bridge Engineering Group,Nanjing 211800,China;China Railway Major Bridge Engineering Group Co.,Ltd.,Wuhan 430050,China)

机构地区：[1]中铁大桥局集团第四工程有限公司,江苏南京211800 [2]中铁大桥局集团有限公司,湖北武汉430050

出　　处：《桥梁建设》2025年第1期1-6,共6页Bridge Construction

基　　金：中铁大桥局集团有限公司科学技术研究与开发项目(2022-03-重大)。

摘　　要：G3铜陵长江公铁大桥主桥为(127.5+131+988+131+127.5)m斜拉-悬索协作体系桥,4号主墩承台为矩形-哑铃形,平面尺寸88.6 m×42.5 m,厚7.0 m,下设64根直径3.0 m钻孔灌注桩基础,桩长79 m。4号主墩基础采用U形无内支撑预应力锚索围堰方案施工,围堰设计为U形开口结构,不设内支撑,在围堰内部设置2批锚索,U形开口结构上游侧长81.1 m、江心侧长129.0 m、下游侧长52 m,围堰高度上分3节,平面分为11个节段(A、K节段为混凝土结构,B~J节段为钢结构)。施工U形无内支撑预应力锚索围堰时,充分利用山体与围堰共同形成挡水结构,减少了对临江山体的开挖;在围堰施工区域局部筑岛,确保了围堰双壁底节在无水条件下安装并浇筑扩大基础混凝土,提高了围堰与河床抗滑移性能。钻孔桩采用旋挖钻机两级钻进、干湿混合成孔的施工技术,缩短了钻孔桩施工工期,有效解决了4号主墩基础在半岸、半水状态且深埋岩层下施工难度大的问题。The main bridge of Tongling Changjiang River Rail-cum-Road Bridge carrying a section of G3 Expressway is a hybrid cable-stayed suspension bridge with a main span of 988 m,two side spans of 131 m and two side spans of 127.5 m.The main pier No.4 rests on a dumbbell-shaped pile cap(with identical rectangular"masses"),which measures 88.6 m by 42.5 m,7.0 m deep and is supported by 64,∅3.0 m bored piles of 79 m in length.The construction of the main pier No.4 was assisted by an open U-shaped cofferdam that contains no inner supports,but fitted with two batches of prestressing anchor cables.The open U-shaped cofferdam measures 81.1 m long on the upstream side,129.0 m long at the river center and 52 m long on the downstream side.To facilitate construction,the cofferdam was divided vertically into three lifts and 11 sections in plan,among which the sections A and K are concrete sections and the sections B to J are steel sections.During the construction,the hills around were fully relied to achieve sound water-retaining effect,together with the cofferdam,while minimizing the excavation in the hills.An artificial island was reclaimed to create a dry environment for the construction of the bottom cofferdam lift and the pouring of the concrete of the spread foundation as well,consequently improving the anti-slip performance of the cofferdam against the river bed.To shorten the construction schedule of the bored piles,the bore holes took shape by a two-phase drilling approach,in both dry environment and in water.The construction of the foundation of main pier No.4 was successfully completed,though it is located half on the bank and half in the river and is required to be deeply embedded into the river bedrock.

关 键 词：公路铁路两用桥 斜拉-悬索协作体系桥 钻孔灌注桩基础 U形无内支撑预应力锚索围堰 预应力锚索 施工技术 

分 类 号：U448.121[建筑科学—桥梁与隧道工程] U443.154[交通运输工程—道路与铁道工程] U445.4