A new elastic T-shape joint of longitudinally connected slab ballastless track structure for releasing thermal stress caused by non-uniform temperature loads

Abstract

In a longitudinally connected slab ballastless track structure (LCSBTS), the T-shape joint is the critical section where severe damage is often found due to the extremely high-temperature effect, mainly concerned with routine high-speed railway maintenance. This paper proposes a new elastic T-shape joint that replaces a section of the original C55 concrete joint with elastic material. A numerical model of LCSBTS with a new elastic T-shape joint is established to simulate the development of the interfacial bond failure and joint compressive damage under temporally and spatially non-uniform temperature loads. The influence of the size, material properties and replacement position of the elastic material with the new elastic T-shape joint on the damage, deformation, and stress of LCSBTS subjected to the temperature loads is investigated. Results show that, by adopting the new elastic T-shape joint, the joint compressive damage and the longitudinal thermal stress of LCSBTS are reduced significantly. The lower the elastic modulus of the elastic material, the greater the longitudinal thermal stress release of the track structure. As the elastic modulus of the elastic material decreases, the vertical displacement of the track slab, interfacial damage of LCSBTS and joint compressive damage increase while the vertical displacement of the joint improves. The best new elastic T-shape joint is to replace the middle of the wide joint made of C55 concrete with 50 mm-width elastic material, where the elastic modulus is 17324 MPa. Compared to the original designation of C55 concrete joint, LCSBTS with a new elastic T-shape joint achieves 11.2% maximum thermal stress reduction ratio and reduces the joint compressive damage by 23.5% and interfacial damage by 4.2%.