Effect of Subgrade Differential Settlement on Dynamic Response of Vehicle and Slab Track Vertical Coupled System

Abstract:

Based on the theory of vehicle track coupling dynamics, the vibration differential equations of rail, track plate and concrete footing in the slab track system were deduced considering the gravity of track structure. Combined with the vehicle dynamics model of multi rigid bodies, a vehicle and slab track vertical coupled dynamics model was established considering the gravity of track structure. The method of controlling subgrade reaction force was proposed to analyze the dynamic response of vehicle slab track system induced by a wide range of subgrade differential settlement, and the coupled model and control method were verified to be accurate and reliable. The factors of subgrade differential settlement affecting the dynamic response of the system, including driving speed, magnitude of the settlement and wavelength of the settlement, were analyzed. The result shows that the dynamics response increases with the driving speed and the magnitude of the settlement. The comfort index should be treated as the primary index which is more important than the safety index when facing differential settlement. Along with the wavelength of settlement increasing, the relative response first increases and then decreases. There exists a sensitive wavelength of the differential settlement which is related with the length of concrete base.

Key words:slab track; subgrade settlement; self weight; dynamic response