Mechanical behaviors of ballastless track under temperature and vehicle loads in high geo-temperature tunnel

To explore the temperature field, temperature effect and mechanical behaviors of the track structure under combined load in high geo-temperature tunnel, the temperature field test platform is built to simulate the conditions under which the track bottom is heated in high geo-temperature tunnel, and the temperature distribution of the track bed slab in the transverse, longitudinal, and vertical directions is investigated. Then, the numerical model is built to examine the displacement and stress of the track structure under temperature load and combined load consisting of temperature and static vehicle load. The results show that when the temperature load on the track bottom is 30 ℃, the vertical temperature gradient inside the slab is negative, with a maximum of 20 ℃/m, and the maximum temperature differences in the vertical, transverse, and longitudinal directions are 5 ℃, 3.25 ℃ and 2 ℃, respectively. The temperature deformation of the track bed slab is manifested as sinking in the middle and warping at the edge, with the maximum tensile stress occurring in the upper-middle region and the maximum compressive stress in the lower-middle region. Under the combined load, the most unfavorable position of the vehicle load is where the front wheel is in the center of the slab, and for every 5 tons increase in axle load, the maximum tensile stress of the slab increases by about 4%, and the maximum compressive stress increases by about 2%. The findings provide reference for the optimization design of track in high geo-temperature tunnel.