平潭海峡公铁两用大桥非通航孔引桥围堰设计与施工  

Design and Construction of Cofferdam for Non-Navigable Span Approach Bridge of Pingtan Straits Rail-cum-Road Bridge

作　　者：王东辉[1] 

机构地区：[1]中铁大桥局集团有限公司,湖北武汉430050

出　　处：《桥梁建设》2016年第3期1-5,共5页Bridge Construction

摘　　要：平潭海峡公铁两用大桥浅水区非通航孔(水深15m以内)引桥为跨径48m的预应力混凝土梁桥,采用钻孔桩基础,基础采用围堰施工。围堰采用钢吊箱结构,平面尺寸为14.8m×23m,高12.3m,围堰内设2层内支撑,经围堰封底后抽水抗浮和浇注承台后抗沉工况计算,确定封底混凝土厚2m。结合平潭海域海况特点,充分考虑波浪力的作用以及潮差大的影响,钻孔桩施工后,整体拼装吊箱围堰,利用千斤顶整体下放围堰至设计标高;在围堰内设置了3层导向限位装置,以保证入水后的围堰安全;在围堰封底抽水后,对围堰吊挂系统进行二次安装,再次安装吊杆和吊挂牛腿,以满足承台施工需要;围堰侧板和底板间通过销轴连接,并焊接斜撑杆,将底板和侧板固定,以抵抗波浪振动。The non-navigable span approach bridge of the Pingtan Straits Rail-cum-Road Bridge over the shallow water area（the water depth being less than 15m）is a 48-m span prestressed concrete girder bridge.The foundations for the bridge are the bored piles that were constructed,using the cofferdams.A cofferdam for the construction of the piles is the steel boxed cofferdam structure that has the plan dimensions of 14.8×23mand the height of 12.3mand in the cofferdam,two tiers of the internal supports were arranged.Through the calculation of the load cases of anti-buoying of the cofferdam by pumping out the water and anti-sinking of the cofferdam after casting the concrete for the pile cap under the condition of base sealing of the cofferdam,it was determined that the depth of the base sealing concrete for the cofferdam should be 2m.With reference to the sea condition characteristic of the Pingtan Straits and in thorough consideration of the wave force action and the great tidal difference influence,the cofferdam was integrally assembled and was integrally lowered to its designed elevation,using the jacks after the bored piles were constructed.In the cofferdam,3tiers of the guiding and limiting devices were also arranged in order to ensure the safety of the cofferdam at the time the cofferdam was being lowered into the water.After the base for the cofferdam was sealed and the water in the cofferdam was pumped out,the slinging system of the cofferdam was installed for the second time,the hangers and slinging corbels were installed again in order to accommodate the construction of the pile cap.The side plates and bottom plate of the cofferdam were connected by pins and the diagonal struts were welded to fix the side plates and bottom plate in order to resist the vibration caused by the wave forces.

关 键 词：跨海大桥 公路铁路两用桥 钻孔桩基础 钢吊箱围堰 设计 桥梁施工 

分 类 号：U448.121[建筑科学—桥梁与隧道工程] U443.162[交通运输工程—道路与铁道工程]