Damage and deformation of concrete base under the sunny-shady slopes effect in seasonal freeze regions

Addressing the phenomenon of uneven frost heave in railway subgrades in seasonally frozen regions, the CRTS III slab track's weak component, the concrete base, was taken as the research object. A constitutive model of the concrete base considering double scalar damage was established, and a damage model for slab tracks considering the effect of uneven frost heave of the subgrade was constructed. The damage and deformation patterns of the slab track concrete base was analyzed under the influence of factors such as frost heave position, frost heave wavelength, and sunny-shady slope effect ratio. The main conclusions are as follows: under uneven frost heave of the subgrade, cracks in the concrete base mainly appear at the frost heave slope peak and slope toe. When frost heave acts at positions 1 to 5, the limiting grooves of the concrete base are most prone to damage due to their sharp shape, with the concrete base in position 2 being in the most adverse damage state. As the frost heave position moves towards the slab end, the voiding amount under the concrete base first increases and then decreases, with the maximum voiding amount occurring when frost heave acts at position 5. When the wavelength of the subgrade frost heave curve is less than 25 m and the sunny-shady slope effect ratio exceeds 1/3, both the damage state of the concrete base components and the voiding condition under the concrete base are more unfavorable, which will to some extent affect the service performance of the track structure.