Research On Mechanical Feedback And Construction Paving Characteristics Of Steel Bridge Deck Pavement Under Train Disturbance

Highway-railway combined bridges are in desperate need of maintenance due to the thin thickness,special support system and complex using environment.However,the railway traffic can not be stopped.The construction of steel deck pavement was practiced under complicated working conditions due to the random vibrations caused by the current of constantly running trains.This thesis will propose a series of research methods on mechanical feedback and paving effect of steel bridge deck pavement composite system under train disturbance;to clarify the mechanical feedback and vibration conditions of highway bridge deck under train vibration,and propose suggestions for the construction of steel bridge deck pavement composite system under train disturbance.Firstly,this thesis proposes a train vibration excitation simulation method for the study of the highway-railway bridges paving constructions.Based on the train vibration mechanism and vibration excitation propagation law,integrating structural dynamics,orbital dynamics,vibration and other disciplines,to propose necessary train vibration assumptions,simplification and abstraction,comprehensive analysis of field test analysis methods.Also,this thesis chooses artificial excitation function simulation method as primary approach after comparing the correspondingly pro/con and the applicability of the finite element method of wheel-rail system and three commonly used train vibration load simulation methods which are calculated by the meta-calculation method.And the attenuation of the vibration excitation by the rail and sub-rail structure is considered.The function,combined with the actual traffic conditions of the Nanjing Yangtze River Bridge train and the locomotive and orbit parameters,completes the train vibration excitation simulation based on the artificial excitation function simulation method.Secondly,this thesis establishes a set of research methods for vibration effect transmission of highway-railway bridges based on finite element simulation.Taking the Nanjing Yangtze River Bridge Reconstruction Project as an example,considering the vibration excitation failure under the action of the rail,the Abaqus finite element software is used to establish the numerical simulation model of the train disturbance analysis of the railway and the sub-rail sub-model.The common paving scheme of the pavement composite system is combined with the common construction machinery to establish the construction simulation load.The finite element model calculation results of the following vehicle disturbances are compared with different loads.The mechanical response law and vibration of the highway deck system during the construction period are determined.The research indicates that under the train vibration excitation,the overall stress mode of the steel bridge deck pavement composite system remains unchanged during the construction period,and the stress distribution law of the pavement layer and the steel plate position is consistent with the construction load.The lateral and longitudinal maximum tensile stresses of the pavement layer under the influence of train disturbance are 0.57MPa and 0.79MPa,respectively increased by 54%and 49%,and the maximum vertical displacement is9.6mm,which is 37%higher than the construction load alone.Thirdly,this thesis proposes a research method for paving effect of steel bridge deck pavement composite system under vibration excitation.Developed an indoor vibration platform for highway-railway bridges,simulated the vibration conditions of bridge decks for indoor simulation test,studied the influence of vibration excitation on the performance of common asphalt mixture for steel bridge deck pavement,and established the degree of segregation and asphalt mixture.The structural equal model?SEM?of the degree of strength forming and the evaluation of the pavement of the train disturbance is the implicit parameter.The influence of parameters such as amplitude,frequency,total vibration duration and initial vibration time on the asphalt mixture is quantified.It is found that the evaluation amount E_t of the steel bridge deck pavement composite system under vibration excitation is affected by the degree of segregation of asphalt mixture and the strength of asphalt mixture.The degree of segregation of asphalt mixture is mainly affected by the vibration frequency and total vibration duration.The degree of strength formation of the asphalt mixture is mainly affected by the initial vibration time t₁.According to the conclusion of train vibration indoor simulation test and the characteristics of steel bridge deck pavement construction,the corresponding guidance and suggestions for steel bridge deck pavement system construction under train disturbance environment are proposed.This thesis can provide theoretical basis for train vibration load simulation,numerical simulation calculation of bridge deck mechanical response under train vibration,and construction of steel bridge deck pavement composite system under train disturbance.