Nonlinear responses of longitudinally coupled slab tracks exposed to extreme heat waves

Abstract

Structural responses of longitudinally coupled slab tracks (LCSTs) under extreme heat waves (EHWs) and the adaptability of track reinforcement measures to cope with EHWs-related issues have been unprecedentedly investigated in this study. A novel finite element model (FEM) to assess nonlinear mechanical behaviours of LCSTs exposed to temperature rise has been established. The nonlinearities of material constitutional properties, interfacial behaviours and temperature distribution are taken into account, and the FEM has been fully validated by experimental data. This paper is the world's first to highlight nonlinear structural responses of LCSTs such as slab arching and interface failure under EHWs and under normal temperature rises (NTRs). More importantly, effectiveness of track reinforcement measures (such as post-installed anchors and interface adhesives) in mitigating track damage under EHWs are demonstrated to determine whether those measures are capable of making LCSTs adapt to EHWs. The new findings reveal that: (1) vertical buckling of LCST can be caused by atmospheric temperature rises; (2) the interface area between the mortar layer and the track slab adjacent to the joint with initial defect can fail under NTRs, while the interface delamination incurs under EHWs; (3) vertical displacements of track slabs under EHWs can be reduced by 97.3 % when post-installed anchors are introduced; and (4) the bond strength of interface adhesives should be larger than 0.02 MPa and 0.048 MPa to retain the vertical displacements within the threshold of level III interfacial gaps under NTRs and under EHWs, respectively.