怀来城市道路跨官厅水库720m悬索桥主桥设计与创新

Design and Innovation of 720m Suspension Bridge over Guanting Reservoir on Huailai Urban Road

怀来城市道路工程(沙城-东花园),连接沙城、燕山文化新城与东花园生态新城三个中心城区,是怀来县道路网规划的城市主干路,路线跨越北京市备用水源地官厅水库库区,为一级水源保护地核心区域。桥梁全长1 988 m,按双向6车道设计,主桥采用跨度720 m单跨双铰悬索桥一跨跨越官厅水库水面,引桥采用先简支后连续小箱梁。悬索桥锚碇采用沉井基础,主塔采用桩基础,主缆采用PPWS法施工,吊杆为平行钢丝束式。大桥是目前我国华北地区跨度最大的悬索桥,针对桥址多风沙特点和水源保护要求,设计新型抗风主梁,优化雨水收集系统的设计寿命。设计还着重考虑特殊的环境因素和县一级管养部门养护能力不足的矛盾,最终加劲梁采用免涂装耐候钢-混组合结构,有效减少钢结构防腐涂装对水体的污染,同时加强桥面刚度提升道路铺装与结构的耐久性,对环境十分友好且易于养护。

The urban road construction project of Huailai County(Shacheng-Donghuayuan) connects three central regions: Shacheng, Yanshan Cultural New Town and Donghuayuan Ecological New Town. It is a primary road in the road network planning in Huailai County. The road goes over Guanting Reservoir, an alternative water source of Beijing. The reservoir is also in the core region of first-class water source protection. The bridge has an overall length of 1 988 m with a two-way six-lane design. The main bridge is a 720 m-long, single-span and double-hinged suspension bridge that crosses over the water surface of Guanting Reservoir. The approach bridge consists of box girders that are first simply supported then continuously supported. The anchorage of the suspension bridge is built upon open caisson foundation, main columns are built upon pile foundations, main cables are installed with prefabricated parallel wires and strands(PPWS), suspenders are parallel bundled steel wires. The bridge is the suspension bridge with the largest span in North China. According to the characteristics of frequent wind sand and the requirements of water source protection, a new type of wind resistant girder is designed and the life of the rainwater collection system is optimized. During the design process, unique environmental factors and inadequate maintenance capability of county-level government sectors are stressed. Eventually, stiffening girders are designed in steel-concrete composite structure with uncoated weathering resisting steels to reduce water pollution due to the anti-corrosion coating of steel structures. Meanwhile, the rigidity of bridge floors and durability of road structures are improved. This design is proved environmentally friendly and easy for maintenance.