Study On Propagation Laws Of The Vibration In Soil And Prediction Method For Buildings Induced By Traffic Loads

In order to alleviate the traffic pressure brought by the increase of urban population,so the urban traffic network becomes more and more intensive.Therefore,more and more attention was drawn by the problem of traffic environment vibration.How to predict the vibration response of the target building caused by running vehicles accurately,and how to avoid the potential harm to the structure itself,human body,precision instruments induced by the vibration in advance is particularly important.At present,the vibration response buildings close to the road under the influence of traffic load is predicted by establishing a comprehensive model which includes vibration source-soil-target building usually,but the predict accuracy cannot be verified.Based on the analysis of the characteristics of vibration source,the law of vibration transmission of vibration wave in free field and the vibration response of buildings respectively by the method of the theory analysis and field experiment,and the vibration prediction model of structures under traffic load is established by integrating all the parts.The purpose of establishing prediction model is to avoid establishing complex model contains vehicle-bridge-soil-target building,to avoid establishing complex model contains vehicles-traffic structure-foundation of the road/bridge/tunnel,to avoid establishing soil model with complex parameters,to avoid establishing complex finite element model of target structure,to avoid complex calculation with large-scale finite element model,and to realize the vibration response of adjacent buildings under traffic loads can be predicted rapidly.The main work and innovation are as follows:(1)Theoretical study on 2D/3D soil vibration under different types of loadsThrough theoretical derivation,2D/3D soil vibration response under different types of load was solved respectively,and the corresponding soil finite element models were established for mutual verification.The vibration propagation characteristics of 2D/3D soil under simple harmonic load are analyzed,including the following three aspects:1.spatial distribution of steady-state amplitude response of 2D/3D soil under simple harmonic load;2.spatial distribution of the amplitude ratio of steady-state response of 2D/3D soil under simple harmonic load;3.the law that the amplitude ratio of 2D/3D soil vibration response changes with the amplitude of load under simple harmonic load which can be used to serve for the next field test and prediction method.(2)Field test and prediction of soil vibration induced by running trainIn order to study the propagation law of vibration signals in free field induced by the running trains through field experiment,and the field test was done on the site of the bridge of a high-speed line,and the propagation and attenuation characteristics of vibration signals induced by the running vehicle at multiple speeds,and the principle of vibration amplification area was also studied.The acquired accelerations were divided in the frequency domain,and the vibration propagation law of each single frequency was studied,and transfer ratio between two transfer points was also studied.A prediction method of the vibration of the soils near the railway line caused by running train was proposed,and the validity and accuracy of the method was verified by a field test.(3)Study on the vibration of building under the influence of the traffic loadA prediction method of vibration of buildings near railway line caused by running trains is proposed and verified based on the field measurement.The prediction model of the structural vibration can be mainly divided into the following parts:1.Firstly,modal parameters of the structure are identified by analyzing field test data;2.Secondly,the modified FE model of the structure is established based on the identified modal parameters of the structure;3.Lastly,the vibration response of the entire structure is calculated based on the measured vibration response of the building'^foundation and the established FE model.Then,an effective method to remove the interference of background vibration induced by the walking people/electrical signals to the vibration induced by the focused vibration source in the energy domain is proposed.The reliability of this method is verified through the comparison of the processing results of simulated vibration signals and experimental verification.The interference of background vibration on the measured vibration data can be eliminated effectively by the method based on the energy conservation.(4)Study on the prediction method of the vibration response of ancient wooden structure under the influence of traffic loadsFirstly,the propagation law of a single-frequency simple harmonic wave is studied based on the theoretical solutions of a MDOFS linear system under the influence of a simple harmonic load.Secondly,a set of prediction system of the ancient wooden structures'vibrations response under the influence of the traffic load is proposed based on the transfer function of the single frequency vibration signal in the frequency domain and the structural characteristics of the ancient wooden.Finally,the proposed prediction models were applied to the actual two ancient wooden structures,and the validity and accuracy of the methods were verified by the comparison between the predicted value and the actual measured one by field test.