海文跨海大桥设计关键技术

Key Design Technique for Haiwen Sea-Crossing Bridge

海文跨海大桥是中国首座跨越地震活动断层的跨海桥梁,主桥为独塔半飘浮体系斜拉桥,跨径布置为(230+230)m,跨断裂带引桥为57~60 m不等跨径的简支钢箱梁。针对项目强震、强风、强腐蚀等复杂建设条件,该桥主梁采用自重轻、抗风性能优、疲劳耐久的STC轻型组合扁平钢箱梁结构;桥塔采用承台无系梁的横向“人”字形塔、环向预应力锚固系统;通过与沉井方案比选,提出桥塔基础采用超大直径4.3 m的钢管复合桩,以解决强震作用下基础的受力与微风化花岗岩地质施工的难题;采用提出的钢-STC钢箱梁简支桥面连续构造、三维可调节的钢垫石支撑技术方案,以解决跨断裂带钢箱梁日常行车舒适性与强震下桥梁易修复的难题。开展钢箱梁简支桥面连续构造理论及荷载足尺模型试验、1∶20主桥振动台模型试验、抗风模型风洞试验等相关研究,验证了结构的可靠性及适应性。

The Haiwen Sea-Crossing Bridge is the first bridge crossing an active fault in China.The main bridge is a monopylon cable-stayed bridge of half-floating system,with two equal spans of 230 m.The approach bridge crossing the fault zone is a simply-supported steel box girder structure comprising spans of 57 to 60 m in length.The complicated conditions at the bridge site,like high magnitude earthquakes,harsh winds and strong corrosive environment,pose great challenges to the construction.To address these problems,the main girder adopts the composite girder by the combined use of flat steel box girder and light-weight STC(super toughness concrete)deck slabs.The pylon looks like the Chinese character"人",which has no cross beam.The stay cables are anchored to the pylon with a loop prestressing anchor system.By comparing with the caisson scheme,the 4.3 m diameter concrete-filled steel tubular piles were used for the pylon foundation,to make the load bearing capacity of the foundation competent under the action of strong earthquakes and to facilitate the construction in the region with light decomposed granites.The scheme of using steel box-STC composite girder with continuous deck and adjustable 3D steel-strengthened pad stones supporting technique was selected to ensure riding comfort on the deck over the fault and facilitate the retrofit of the bridge after strong earthquakes.A series of tests were conducted to verify the reliability of the structure and the riding comfort of drivers on the deck,including the theoretical study of the simply-supported steel box girder and continuous deck structure,full-scale model test,shake table test with a 1∶20 main bridge model and wind tunnel test.