乐西高速苏坝特大桥主桥设计关键技术

Key Design Technology for Main Bridge of Suba Bridge in Leshan-Xichang Expressway

摘要:

乐西高速苏坝特大桥主桥为净跨350 m上承式钢筋混凝土劲性骨架拱桥。主拱采用拱座+桩基的组合式基础。主拱为等截面悬链线无铰拱，拱圈采用单箱双室截面的双拱肋形式。主拱采用强劲骨架法施工，劲性骨架为型钢与钢管混凝土组成的桁架结构，骨架钢管内灌C120超高强补偿收缩自密实混凝土。劲性骨架采用斜拉扣挂体系拼装合龙后连续泵送灌注管内混凝土，拱圈外包C55混凝土结合结构受力采用两环、分段浇筑，有效节约了施工工期。吊装系统及扣挂体系采用引桥桩基础+岩锚组合式锚碇。桥区地处高烈度地震区，桥梁除考虑结构轻型化外创新设计了由可联动多向防落梁装置、设置纵向变刚度支座及黏滞阻尼器多种抗震措施组成的拱桥结构抗震体系。

Abstract:

The main bridge of Suba Bridge in Leshan-Xichang Expressway is a net span-350 m deck-type reinforced concrete stiff-skeleton arch bridge. The combined foundation of arch support and pile foundation is used for the main arch. The main arch is an equal-section catenary hingeless arch. And the form of a double-arch rib with a single-box double-chamber section is used for the arch ring. The main arch is constructed by a strong stiff skeleton method. The stiff skeleton is a truss structure composed of section steel and concrete filled steel tube. The skeleton steel tube is filled with C120 ultra-high strength compensated shrinkage self-compacting concrete. The stiff skeleton is continuously pumped with the concrete inside pipe after assembled and closed by cable-stayed buckle system. The arch ring outer C55 concrete combined structure is loaded with two rings and segmented pouring, which effectively saves the construction period. The approach pile foundation + rock anchor combined anchorage is used for the hoisting system and the buckle hanging system. The bridge area is located in a high-intensity seismic zone. Therefore, in addition to considering the lightweight structure of the bridge, an anti-seismic system of arch bridge structure is innovatively designed, which is composed of multi-directional anti-falling beam device, longitudinal variable stiffness support and viscous damper.