采用部分拼接法拓宽长联混凝土桥梁应用基础研究

Due to its investment scale is not large and implementation cycle is not longer, widened road becomes the main form of highway widening alteration. To shorten the splicing time of long-connected concrete bridges, partially spliced method of new and old bridges was proposed, according to the characteristic transversal displacement of extended long-connected bridge which shows large at both ends and small at middle, in detail, new and old girders were symmetrically spliced from mid-span by cast-in-place wet joint, while were not spliced at both end parts. Through the analysis of the influence of different factors on long-connected concrete bridges, the stress mechanism of long-connected bridge will be analyzed, and the effective countermeasure to shorten the splicing time of long-connected bridge will be put forward. To the non-splicing part, three splicing structures were presented: "Z" shaped steel plate splicing structure with friction high strength bolts, splicing structure with corrugated steel plate and steel plate with long round holes, splicing structure with rectangular plate. Through model test and numerical analysis, stress mechanism, path of force transfer and failure mode of three splicing structures will be obtained, and then the reasonable geometrical size and optimal value of the splicing structure will be determined. On the basis of the above research, the design method and simplified calculation method of long-connected bridge with partial splicing method will be established. This project provides an effective and feasible method for long-connected bridge. It can be used to ensure the bridge widened during the construction period, avoid the improvement of construction cost caused by the secondary splicing construction, and promote the continuous improvement of traffic construction in China.

投资规模不大、实施周期较短的公路改扩建形式将成为公路拓宽改造的主要形式。为缩短拓宽长联混凝土桥梁拼接时间，根据拼宽长联桥梁横桥向变形一联两端大、中间较小的受力特点，提出拓宽长联桥梁的部分拼接法，即新、旧桥主梁沿纵桥向由桥梁中跨向两边通过现浇湿接缝对称拼接，在一联两端不拼接。通过不同因素对拼宽长联混凝土桥梁的影响分析，明确拼宽长联桥梁受力机理，得到缩短长联桥梁拼接时间的有效对策。对于不拼接段，提出带摩擦型高强螺栓的“Z”形钢板、带长圆孔的钢板+波形钢板和带矩形钢板三种拼接结构。通过模型试验和数值分析得到三种拼接结构的受力机理、传力路径和破坏模式，从而确定拼接结构的合理几何尺寸和最优值。在以上研究基础上建立采用部分拼接法拓宽长联桥梁的设计方法和简化计算方法。本项目为长联桥梁拓宽提供一种有效可行的方法，可保证在桥梁施工期内完成桥梁拓宽，避免二次拼接施工造成建设成本增加，促进我国交通建设不断发展。

以新旧桥上部结构拼接成整体、下部结构不拼接为原则进行拓宽的长联混凝土桥梁为研究对象，建立三维杆系有限元模型，分析了混凝土收缩、徐变和温度变化等长期荷载对新旧主梁纵、横桥向的影响，并提出带摩擦型高强螺栓的“Z”形钢板、带长圆孔的钢板+波形钢板和带矩形钢板三种拼接结构。并对拼接结构开展了足尺模型试验，建立采用所提出的拼接方法拓宽的长联桥梁的设计与验算方法。分析结果表明：《公路钢筋混凝土及预应力混凝土桥涵设计规范》的计算方法能较准确地计算混凝土收缩、徐变引起结构的变形；长期荷载使沿纵桥向全部拼接后的主梁产生较大的横桥向位移，引起的结构变形最大值均出现在桥台或一联的过渡墩位置；由混凝土收缩引起的横桥向位移占选取的长期荷载产生的横桥向位移的68.58%，混凝土收缩是影响拓宽后长联桥梁横桥放置时间主要因素，应保证拼接10年后新、旧桥支座最大横桥向位移小于容许值；新、旧桥主梁由桥梁中跨向两边通过现浇湿接缝对称拼接、但在一联两端不拼接的部分拼接方法，可明显减小新、旧桥支座横桥向变形，从而缩短长联桥梁拼接时间；新型拼接结构能够避免不拼接段桥面铺装出现裂缝，且保证新、旧桥主梁横桥向位移一致；当试验荷载加载至相当于2倍公路-I级设计荷载过程中，拼接钢板与翼缘连接处以及桥面铺装均未出现开裂或压碎现象，桥面铺装与主梁翼缘的结合面未张开，表明不拼接段新、旧桥主梁翼缘间沿纵桥向等间距设置钢板连接构造进行拼接的方法可避免不拼接段桥面铺装出现裂缝，且保证新、旧桥主梁横桥向位移一致；新、旧桥主梁应进行抗弯、抗剪和抗扭承载力验算，连续拼接段湿接缝与全桥桥面铺装应进行竖向、纵桥向抗弯和抗剪承载能力验算，拼接钢板应进行主平面抗弯和竖向、纵桥向抗剪承载力验算。