Deformation mapping and damage mechanism of ballastless track under lateral dislocation in tunnel-active fault zones
摘要
Tunnel offset and deformation in active fault zones under complex geological conditions present significant challenges to the operation of slab track structures. This study develops models for various forms of double-block slab track structures in active fault zones, incorporating concrete plastic damage theory and a cohesive zone model to analyze layered deformation, interlayer bond failure, and damage evolution under lateral deformation. The analysis reveals that when lateral deformation loads are applied to the midsection of the track structure, in addition to deformation in the bottom layer, pronounced abrupt rail displacements occur due to the vertical discontinuity of the multilayer structure. The magnitude of structural deformation is directly proportional to the lateral deformation amplitude, while the displacement gradient is inversely proportional to the length of lateral deformation. Under lateral deformation, significant bond failure occurs at the edges of the track slab, with the degree of debonding closely correlated with the length of the track slab elements, where double-block slab track elements exhibit the lowest bonding strength. As the deformation amplitude increases, structural damage progressively intensifies, beginning with the formation of diagonal cracks and primarily concentrated in the middle of the track slab.