渝黔铁路夜郎河大桥主桥设计关键技术

Key Techniques of Design of Main Bridge of Yelang River Bridge on Chongqing-Guiyang Railway

渝黔铁路夜郎河大桥主桥采用一跨370m的上承式钢筋混凝土拱桥。拱脚采用等截面实心超大桩径倾斜桩基础(截面长22.502 m、宽16.388 m),工程量及边坡开挖量小且施工安全、环保。主拱圈采用2个单箱单室拱肋相交组成的X形拱圈,极大地提高了桥梁的横向刚度,主拱圈外包混凝土分层(可减少对劲性骨架的强度要求)分段(可增加工作面)浇筑。钢管混凝土劲性骨架采用由通长钢管组成的桁架拱,钢管内灌注泵送混凝土,采用扣挂法节段拼装施工;通过扣索调整上、下弦钢管中的应力,管内混凝土替代了部分钢材。桥面系采用每孔跨径38m的钢-混连续结合梁,采用大节段吊装拼装钢梁、现场分段浇筑桥面混凝土的施工方案。

The main bridge of the Yelang River Bridge on Chongqing-Guiyang Railway is a reinforced concrete deck arch bridge with a single span of 370 m.The foundations for the arch springs of the bridge are the constant section and solid foundations composed of the very large diameter batter piles（the section of a foundation being 22.502 mlong and 16.388 m wide）.The engineering quantities and the side slope excavation amounts of the foundations of such kind are the fewest and the construction is safe and environmentally friendly.The main arch ring of the bridge is the X-shape arch ring intersected by the 2 single-cell and single-box arch ribs and with the Xshape arch ring,the lateral stiffness of the bridge is greatly improved.As is designed,the encased concrete for the arch ring is cast in layers（the strength requirements for the concrete-filled steel tube stiff skeleton can be decreased）and in segments（the working spots can be increased）.The stiff skeleton is a sort of the truss arch structure formed by the through length steel tubes filled with the pumped concrete and the stiff skeleton is assembled in segments,using the fastening stay method.The stresses in the upper and lower chord steel tubes are adjusted by adjusting the fastening stays and the concrete in the tubes replaces part of the steel material.The floor system of each span is the 38 msteel and concrete continuous composite beam and the construction scheme for the composite beam is to lift and install the steel beams in large segments and to cast the concrete deck slabs in segments in the field.