Mechanical Properties of Ballastless Track Considering Freeze–Thaw Deterioration Damage

Abstract

In order to investigate the stress characteristics of ballastless track under high latitude, and multi-source and multi-field extreme temperature conditions. Based on the finite element theory and the elastic foundation beam–plate principle, a finite element model of the ballastless track considering the limit convex abutment, gel resin, and interlayer bonding is established. The mechanical characteristics of the ballastless track under the slab–CAM layer bonding state, mortar separation, freeze–thaw degradation and forced deformation of the foundation are studied. Considering the deterioration of materials, the bending moment and reinforcement of track structures in cold regions are checked and calculated. The studies show that under the action of negative temperature gradient load, the edge of the track slab is subjected to tension, and structural separation occurs at the edge of the slab. When the interface between the track slab–CAM layer is poorly bonded, the bearing capacity can be improved, and the amount of separation can be reduced by increasing the structural stiffness of the CAM layer. Under the action of freeze–thaw cycles, the material performance deteriorates seriously, the separation between the track structures intensifies, the baseplate is seriously powdered and cracked, and the maximum tensile stress exceeds 6 MPa. The CAM layer and the baseplate are weak structures, and the foundation frost heave occurs at the expansion joint of the baseplate, which is the frost heave condition. Under freeze–thaw deterioration, the original reinforcement design of the substructure structure does not meet the requirements of structural cracks and reinforcement yield stress. In severely cold areas, the structural reinforcement scheme should be reasonably determined.

A Study on the Influence of Steel Structures in Concrete Subgrades on the Detection of Subgrade Distresses by Ground-Penetrating Radar

“…The dense steel reinforcements can introduce signal interference during non-destructive testing methods such as radar and ultrasonic testing, which makes it difficult to accurately identify and analyze subgrade distresses. Therefore, precise differentiation between actual subgrade signals and steel-reinforcement interference signals is a pressing technical challenge [15][16][17][18]. Due to their high electrical conductivity, these reinforcements can cause signal reflections, scattering, and multiple propagation, resulting in an overlap between the subgrade and reinforcement signals that complicates signal differentiation.…”