Analysis Of Vibration Response Induced By Trains And Long-term Settlement On High Embankment Of Bazhun Heavy-haul Railway

Now, the heavy haul for freight in railway has become a main trend of thedevelopment of railway in the world. Because of advantages of preferable benefit,large freight volume, high efficiency and low energy consumption, heavy haulrailway has developed rapidly in our country. At present, the research for basic rules ofvibration response caused by trains and the prediction method of the long term settlement ofsubgrade of common railway has done more work, but lack of further study for heavyhaul railway. Therefore, this paper chooses typical section of high embankment ofBazhun heavy haul railway as the research object, selects C75heavy haul freight car, usesthe combined method of finite element method and empirical anticipating model, researchesbasic rules of dynamic response and the prediction method of the long term settlement of highembankment of Bazhun railway under load of heavy haul train. Main researchcontents are as follows:First of all, according the actual situation of DK97+454section of Bazhun heavyhaul railway to establish the finite element model of dynamic response of highembankment under load of heavy haul train. In the model, considered the sleeperstructure to be linear beam element; optioned plane-strain element to simulate thestructure under sleepers; using infinite element model to simulate horizontal and verticalboundaries so that the effect of wave reflection at the artificial boundary could beeliminated; using elastic-plastic constitutive model to simulated the subgrade andfoundation, using linear elastic constitutive model to simulated sleeper and ballast bed; usingRayleigh damping modal in car-track-subgrade dynamic coupling system to consider theenergy dissipation; based on the unified theory, by using self-made numerical model ofcar-track-subgrade dynamic coupling system, calculate time-history curve of sleeper forceof heavy haul train as input load, using explicit integration algorithm to solvenonlinear dynamic equations of system, compared the calculated results withmeasured data to verify the correctness of the established numerical model.Then, based on the established finite element model, inputting dynamic timehistory of heavy haul train under different moving velocities as excitations, analysisdynamic stress and vertical acceleration.Discuss the influence of train speed, the thickness of ballast bed, stiffness of ballast, the thickness of surface layer ofsubgrade and stiffness of surface layer of subgrade to dynamic response of subgrade.Analysis showed that moving velocity will produce a great impact on the dynamic response ofvertical acceleration, the increase of thickness of ballast and surface layer of subgradecan effectively protect the stability of understructure, and the stiffness of ballast andsurface layer of subgrade should not be too great.Finally, applying the results of nonlinear dynamic finite element method toprediction formula of long-term settlement, divided the subgrade into ballast andembankment two parts to make long-term settlement of subgrade prediction, andthrough the conversion of vibration number and time to make evaluation of annualsettlement of subgrade. The increase of moving velocity of heavy-haul train and thethickness of ballast increased annual settlement of subgrade; the increase of stiffnessof ballast, stiffness of surface layer of subgrade and the thickness of surface layer ofsubgrade reduce annual settlement of subgrade，the influence of design parametersof ballast is greater than design parameters of surface layer of subgrade.