轨道-箱梁耦合振动模型试验设计与验证

Model Test Design and Verification of Track-box Girder Coupling Vibration

为研究基于模型试验的轨道-箱梁耦合振动反演方法,从理论上探讨多层结构层间耦合相似关系,根据弹性力相似律和相似π定律,设计、制作几何相似比为101的轨道-箱梁耦合相似模型,分析轨道板密度和弹性模量、扣件刚度、CA砂浆层刚度等参数对系统相似性的影响。通过模态试验、有限元法验证模型设计的正确性及原型与模型间的相似关系。结果表明,通过模型试验方法,依据模型与原型间的相似关系反演现场不同工况条件下的振动水平;当某一结构层在荷载方向上的几何尺寸远大于其他结构层时,依据弹性力相似律,原型与模型间的耦合相似关系可由箱梁材料参数导出;轨道板密度及弹模变化,对结构前五阶模态影响误差最大为0.033%;在200~500 Hz范围内,扣件刚度、CA砂浆层刚度变化对箱梁振动加速度的最大影响分别为2.542%、4.326%。

In order to study the track-box girder coupling vibration inversion method based on model test,the coupling similarity relationship between the layers of the multilayer structure was discussed theoretically at first.According to the similarity law of elastic forces andπtheorem,a track-box girder coupling vibration model with a geometric similarity ratio of 101 was designed and produced to analyze the influence of the parameters on the system similarity such as the density and elastic modulus of track slab,the stiffness of fastener and CA mortar layer.The validity of model design and the similarity relationship between prototype and model were verified based on the modal test and finite element method.The results indicate that the vibration level under different working conditions on site can be inverted according to the similarity relationship between the model and the prototype using the model test method.In the model design,when the geometry size of a certain structural layer in the direction of load is much larger than that of the other structural layers,the similarity relationship can be directly derived from the material parameters of the box girder if the similarity model of the track-box girder coupling system is designed pursuant to the elasticity similarity law.The influence error of the change of track slab density and elastic modulus on the first five modes of the structure is 0.033%at most.Within the range of 200~500 Hz,the maximum influence of the change of fastener stiffness and CA mortar layer stiffness on the vibration acceleration of the box girder is 2.542%and 4.326%respectively.