Dynamic Response Analysis of 400 km/h High-speed Railway Ballasted Track Under Rail Welding Zone Excitation
The increased speed of high-speed trains will result in stronger impact when vehicles pass over welded joints,which can negatively influence the stability of train operations.Therefore,it is crucial to analyze the dynamic response characteristics of high-speed trains passing over the welded joint for the design and operation of high-speed railways.This paper establishes a 3D vehicle-track-foundation coupled dynamic model that incorporates flexible wheelsets.Disadvantage conditions are selected to simulate the irregularities of welded joints.Then the dynamic response of a 400 km/h high-speed railway's ballast track structure is studied.Furthermore,the dynamic results are compared with the specified limits,and the effects of varying fastener stiffness,track bed support stiffness,and foundation types on wheel-rail dynamics are analyzed.The results demonstrate that when trains pass over welded joints at the speed of 400 km/h,all evaluated performance indicators meet the requirements outlined in current specifications with the derailment coefficient and the rail lateral displacement significantly lower than the permissible limits;The stiffness of the fastener support has considerable influence on rail displacement and track bed acceleration,reducing rail displacement by 0.8 mm and increasing track bed acceleration by 0.8 times;The stiffness of the track bed support primarily affects rail displacement and track bed acceleration,leading to an 8.9%increase in track bed acceleration;The foundation type hasminimal impact on vehicle-track dynamics,but increases the track bed vibration acceleration to 2.57 times.Compared to passing over welded joints at 350 km/h,the interaction between vehicle and track dynamics significantly intensifies at 400 km/h,resulting in a 46 kN increase in wheel-rail force.Under high-speed train operating conditions,wheel load reduction rate and wheel-rail vertical force won't exceed limit value but approach it.Therefore,significant scrutiny should be placed on the wheel load reduction rate and vertical wheel-rail force in project operations and management.Strict monitoring and focused management strategies are necessary to address the irregularities present in welded joint areas.
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