Analysis On Mechanical Properties Of Ballast Bed During Operation Of Track Dynamic Stabilized Device

With the increase demand of Chinese railway transportation,increasing traffic density and shortening train interval have become an effective way for domestic railway transportation organizations to increase traffic volume.However,this will inevitably lead to an increase in the burden of ballasted track maintenance and a shortening of the maintenance period.Therefore,it is urgent to improve the maintenance efficiency.The maintenance method of using small maintenance machinery between train interval can no longer meet the current requirements,so it is necessary to use large-sized railway line maintenance machinery with high operation efficiency.Dynamic stabilized vehicle(DSV)is a large-scale maintenance equipment commonly used in ballasted track maintenance operations.Since it was introduced from abroad to be independently developed in 1984,China has made great progress in using DSV to repair and maintain ballast tracks.However,for different ballasted track line conditions,the selection of dynamic stability operation parameters is still mainly based on past experience,and theoretical guidance is still lacking.In this thesis,using the discrete element method and multi-body dynamics theory,a simulation analysis of the dynamic response and the evolution of its mechanical properties of the track bed during track dynamic stabilization is carried out,and the principles and methods for selecting the operating parameters of track dynamic stabilization are preliminarily discussed.And it is expected to provide theoretical guidance for the development of intelligent orbital dynamic stabilized devices.Firstly,the PFC software is used to establish a three-dimensional discrete element model of the ballasted track,and the support stiffness and lateral resistance of the ballast bed with different compactness are calculated,The supporting stiffness and lateral resistance of ballast beds with different compactness are calculated.It also analyzes the spatial distribution and sharing of the lateral resistance of the ballast bed,which provides a reference for the monitoring and evaluation of the state of the ballast bed.Secondly,the operation device and stabilization principle of the WD-320 DSV are analyzed,and the dynamic stabilized devicesrail row multi-body dynamics model is established by using the multi-body dynamics software UM.Using this model,the effect of the rotation frequency of the eccentric wheel and down force on the dynamic response of the device frame and sleeper was studied,and the resonance frequency of the dynamic stabilized devices-rail row system was analyzed.Finally,the discrete element simulation analysis of the macro and meso-mechanical behavior of the ballasted track and the lateral resistance of the ballast bed during the dynamic stabilization operation is carried out.The changes of the lateral resistance of the ballast bed before and after the stabilization operation are compared and analyzed,which provides a reference for the selection of dynamic stabilization parameters and effect evaluation.The research results show that the change of density has a significant impact on the mechanical properties of the ballast bed.The density of the loose ballast bed and the steady ballast bed is only 0.9% different,but the average value of the support stiffness and lateral resistance of the latter is more than 1.5 times that of the former;The density of the compacted ballast bed is 7.8% larger than that of the steady ballast bed,but the average value of the support stiffness and lateral resistance of the former is more than twice that of the latter.The lateral resistance distribution of three kinds of ballast beds with different densities is different.The lateral resistance of the loose ballast bed is borne by the ballast on both sides of the sleeper more,and the sleeper bottom bears the least;the lateral resistance of the steady and compacted ballast bed is mainly borne by the sleeper bottom.The downforce has little effect on the resonance frequency of the dynamic stabilized device-rail row system;when the rotation frequency of the eccentric wheel of the stabilized device is 33 Hz,the vibration response amplitude of the system is the largest.The influence of dynamic stabilization is reduced to 15%at a distance of 5.4 m from the stabilized device,and the influence of stabilization decreases rapidly with the increase of ballast depth.