Interfacial failure behavior of longitudinally coupled slab tracks restored by interface adhesives

Longitudinally coupled slab tracks (LCSTs), one of the most popular slab track types, have experienced severe damage like interfacial debonding and gapping over the past few years. Although adhesives have been used to restore the separated interfaces of LCSTs, the high-temperature environment still poses a great challenge to the repaired tracks. Therefore, this paper presents a numerical investigation on the interfacial failure behavior of LCSTs restored by interface adhesives under high-temperature load. Firstly, the constitutive relationships and the damage behavior of the original and the restored interfaces between the track slabs and mortar layers was modelled based on the cohesive zone theory. Secondly, a finite element model of the LCST was established in which the nonlinear mechanical properties of the interfaces and the materials, as well as the nonlinear distribution of track temperature were considered. Last but not least, damage evolution law of interfaces restored by adhesives, the effects of adhesive-use area, and the performance of adhesives on interfacial debonding and gapping under high-temperature loads were studied. The following conclusions are drawn: (1) After adopting the adhesive, the maximum vertical displacement of track slabs can be reduced by 35.2%. (2) An adhesive-use depth above 500 mm on both sides of the lateral path is recommended to lower the height of interfacial gaps to below 1 mm. (3) In addition to using adhesives, keeping the T-shaped joints in a good condition also plays a crucial role in mitigating interfacial gapping. (4) The distribution of the interfacial damage index D on the lateral path of the track shows a significant asymmetry when adhesives are only used on one side of the lateral path.