Study on the Influence of Subgrade Arching of Long-unit Double-block Ballastless Track in Bridge-roadbed Transition Zone

The subgrade arching of the roadbed-bridge transition zone will cause the uplifting of the fasteners on the adjacent bridge,leading to track slab hanging and static and dynamic irregularity.The existence of static and dynamic irregularities will affect the running safety and comfort of the vehicle travelling at high speed.In this paper,a static and a dynamic analysis model coupling vehicle,track,bridge and roadbed was built,to estimate the static irregularity caused by the subgrade arching and its dynamic influence.The results show that when the subgrade arching is larger than 2 mm,the gap under the track slab begins to develop,which increases linearly with the increase of the subgrade arching.The fasteners on the adjacent bridge are uplifted obviously.At 5 mm of the subgrade arching,the vertical acceleration of the car body reaches the standard limit when the vehicle speed reaches 350 km/h.At this point,the wheel load reduction rate reaches 0.53.At 10 mm of the subgrade arching,the vertical acceleration of the car body reaches the standard limit when the vehicle speed reaches 150 km/h.The wheel load reduction rate reaches the standard limit when the vehicle speed reaches 250 km/h.When the subgrade arching is 10 mm,the fasteners on the adjacent bridge bear significant dynamic uplifting force,with the maximum dynamic uplifting force of 42.2 kN. © 2018, Department of Journal of the China Railway Society. All right reserved.