Study on the effect of CRTS III ballastless track caused by angular settlement in transition section between bridge and subgrade

Since the supporting stiffness magnitudes of the bridge and subgrade are different and the subgrade behind the abutment is difficult to fill and compact, the high-speed railway bridge-subgrade transition section is prone to angular differential settlement. It leads to problems such as interlayer separation, structural cracks, and subgrade cavities in the ballastless track, affecting the operation comfort and safety of high-speed train. This paper took CRTS III ballastless slab track in the high-speed railway bridge-subgrade transition section as the research object, established the ballastless track spatial coupling model in the transition section by using ABAQUS finite element software, and studied the influence laws of the angle of settlement in the transition section and the thickness of base on the interlayer separation of ballastless track. In addition, the plastic damage characteristics of concrete were considered, and then the influences of different load combinations and base thicknesses on the stress and deformation of track were analyzed. The results show that the angle of settlement has a great influence on the stress and deformation of track. When the angle increases from 0.5° to 1°, the length of separation between the self-compacting concrete layer and the base increases from 0 to 1.46 m, and the amplitude of separation increases from 0.99 mm to 3.13 mm. The length of the loss of subgrade support increases from 0 to 0.92 m, and the amplitude of the loss of subgrade support increases from 0.51 mm to 2.53 mm. At the lower end of angular settlement, compared with the loss of subgrade support, the distribution range of separation joints between self-compacting concrete layers is larger, but the amplitude is smaller. At the upper end of corner settlement, the distribution range and amplitude of interlayer separation joints are larger than those of the loss of subgrade support. The increase in base thickness can reduce the separation between the track layers and the structural cracks caused by the angular settlement, and the range of damage and the maximum value of damage factor are reduced. It is suggested to increase the thickness of the base to 50 cm, which can effectively improve the adverse influence of the allowable angular settlement with 1° in the transition section specified in the code on the service state of the CRTS III ballastless track. © 2023, Central South University Press. All rights reserved.