无锡市312高架桥倾覆事故分析

FORENSIC ANALYSIS OF THE WUXI 312 VIADUCT OVERTURNING COLLAPSE

2019年10月10日,无锡市锡山区312国道某3跨混凝土连续箱梁在2辆车辆作用下发生倾覆。首先开展了事故现场调查工作,基于事故现场残骸照片及施工图纸,建立考虑几何非线性的有限元模型,进行倾覆破坏机理研究,提出了基于强度和倾覆稳定效应的超载判定方法。研究结果如下:基于标准车道荷载的倾覆验算结果表明,无锡桥不满足现行2018版《公路钢筋混凝土及预应力混凝土桥涵设计规范》规定的抗倾覆验算要求;上部结构在超载车辆作用下发生先转动、再滑动,最后产生了大幅转动与滑动相结合的倾覆破坏模式;从支座脱空到上部结构发生倾覆,结构仍有一定安全储备;基于强度和倾覆稳定效应的计算结果表明,现场超载车辆产生的倾覆效应大于结构抗倾覆承载力,说明超载是结构发生倾覆的主要原因,但通过进一步计算发现结构抗弯承载力充足,表明结构倾覆破坏早于强度破坏,结构抗倾覆能力与抗弯能力不匹配。

On October 10,2019,a three-span concrete continuous box girder on National Highway 312 in Xishan District,Wuxi City,overturned under the action of two vehicles.Investigated the accident site first,then established a geometrically nonlinear finite element model based on wreckage photos and construction drawings,and studied the overturning mechanism.An overload determination method based on the strength and overturning stability effects is proposed.The results include:the overturning test results based on the standard lane load demonstrate that the bridge does not meet the overturning test requirements specified in the Specification for Design of Highway Reinforced Concrete and Prestressed Concrete Bridge and Culvert(2018 edition);the superstructure under the action of the overloaded vehicle first rotated,then slid,and finally exhibited a combination of substantial rotation and sliding overturning mode;the superstructure has a certain safety margin between bearing separation and overturning;the calculation based on the strength and overturning stability effect proves that the overturning effect generated by the overloaded vehicle is greater than the overturning capacity of the structure,indicating that the overturning is mainly attributed to the overload.However,the structural bending capacity turns out to be sufficient through further calculation,indicating that the overturning damage occurred earlier than the occurrence of strength damage,and that the overturning resistance and bending resistance do not match.