A Time-varying Coupling Model for Dynamic Analysis of High Speed Railway Subgrade

Track transportation can be divided into the track system above and the track system below.While the train is moving,the parts above and below are interacted and mutually influenced.Therefore,the problem of track transportation is actually the matching between the vehicle and the railway line system.In this paper,keeping to the conditions of train running and taking the track-subgrade as a part of the vibration structure of the vehicle mode1,a vehicle-subgrade model of the secondary suspension vertically coupled system including the vehicle,rail,sleeper,ballast and subgrade is established.Dynamic computer simulation of the vehicle-subgrade system is performed in combination with speed raising reconstruction project of the Jingqin Railway Line as the verification of the model.Regarding the train travelling at different speeds and through subgrade sections ahead of and subsequent to strengthening,dynamic responses such as the acceleration of the vehicle,dynamic wheel load and rate of wheel load reduction and the main dynamic characters of ballast and subgrade are calculated and compared with the experimental results.The effectiveness of the theoretical model and simulation analysis are verified by the test results.Reference is made to analysis of the dynamic characters and design of the subgrade of high-speed railways.