Vertical Stress Attenuation Characteristics of Slab Ballastless Track Under High-frequency Train Load
In order to optimize the design of ballastless track structure and provide reference for determining the values of dynamic coefficients,CRTSⅠ slab ballastless track was taken as the research object.LS-DYNA software was used to establish a vehicle-track coupling dynamic model,analyze the time-frequency characteristics of wheel-rail vertical force under wheel tread and weld seam excitation at different speed levels,and clarify the variation law of wheel-rail vertical force with vehicle speed.Furthermore,the variation law of vertical stress along the depth of the track structure was analyzed,and the dynamic coefficient of the track structure was calculated,revealing the variation laws of the dynamic coefficient along the depth of the track structure.The results show that within a speed of 400 km/h,the main frequency of the vertical force between the wheel and rail under the action of uneven wheel tread is greater than 500 Hz.While under the action of uneven weld seams,there are two main frequencies of the vertical force between the wheel and rail,where the higher main frequency is greater than 500 Hz,and the lower main frequency is within(49.9±10)Hz.The vertical stress of the track under high-frequency train load decays significantly along the depth of the track structure.The vertical stress at the bottom of the track slab is about 15%of that at the top of the track slab,and the vertical stress at the bottom of the base slab is about 4%of that at the top of the track slab.The dynamic coefficient of the track structure significantly decreases along the depth of the track structure,with a decay of about 40%between the steel rail and the track slab and a decrease of about 50%in the dynamic coefficient at the bottom of the base slab compared to the steel rail.It is suggested to appropriately reduce the design and calculation dynamic coefficients of ballastless tracks under high-frequency train loads.
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