# Influence of Uneven Subgrade Frost Heave on Deformation and Damage of CRTSIII Slab Track
## 5 Conclusions  
Aiming at the problem of uneven high-speed railway subgrade frost heave, based on the concrete damage plasticity theory, an analytical model of CRTSIII slab track-subgrade coupling calculation model was established to study the influence of uneven subgrade frost heave on the deformation and damage of slab track. Conclusions from this analysis are summarized below:  
1. Based on the concrete damage plasticity theory, the damage plasticity parameters of concrete in a track structure are deduced and the correctness of the parameters is verified. The damage plastic model can reflect the softening behavior and stress attenuation phenomenon of the concrete in the track structure after reaching tensile strength. The analytical results are consistent with the on-site condition, which fully demonstrates the necessity and superiority of considering plastic damage on concrete materials. 2. The peak value of the seam between the self-compacting concrete and the base normally occurs at the self-compacting concrete edge. When the frost heaving wave peak appears at the position that is one-sixth of the base length from the edge of the concrete base (e), due to the lack of longitudinal constraints at the base edge and the formation of a lever system in the middle of the self-compacting concrete, the seam between layers reaches its maximum value at 7.94 mm. The maximum and minimum interlayer seams between the base and the subgrade surface occur when the frost heaving positions are at one-sixth of the base length from the edge of the concrete base (e) and the expansion joint of base (g), respectively. 3. When the frost heaving wave peak is on grooves in the middle of the base (b), initially, damage and macroscopic cracks of concrete base appear. When the frost heaving wavelength is 10 m, the frost heaving values corresponding to initial damage and macroscopic cracks are 2.43 and 3.83 mm, respectively. When the frost heaving position is near the slab center, the damage to the slab is significant. It occurs near the center of the slab. 4. The deformation of the track structure increases with an increase in frost heaving wavelength and frost heaving wave amplitude. It is mainly dominated by the frost heaving wave amplitude. The seam between layers decreases with an increase in frost heaving wavelength and increases with an increase in frost heaving wave amplitude. The frost heaving wavelength has a greater influence on the interlayer seam, and the interlayer seam is more sensitive to the frost heaving in the 10 m range wavelength. 5. When the frost heaving wave amplitude is 15 mm or less, the normal relationship between the maximum tensile stress of the base and the frost heaving amplitude is linear. At this moment, the base has not been damaged or the damage is limited. When the frost heaving wave amplitude reaches 15 mm, 25 mm, and 30 mm, the peak tensile stress of the base reaches the maximum tensile strength, and the stress attenuation phenomenon occurs. The corresponding minimum allowable frost heaving wavelengths are 10 m, 20 m, and 30 m, respectively. 6. The average damage factor for the base decreases with an increase in frost heaving wavelength and increases with an increase in frost heaving wave amplitude. With a decrease in the wave/amplitude ratio of frost heaving, an increase in damage to the base is observed. Here, it undergoes changes in three stages, namely: (i) no damage, (ii) bending damage on the upper surface, and (iii) reverse bending damage. Conceptualization, H.W. and H.X. ; Data curation, H.W. ; Formal analysis, H.W. and H.X. ; Funding acquisition, H.X. ; Investigation, Q.G. ; Methodology, H.W. and H.X. ; Project administration, S.Y. and Q.G. ; Resources, S.Y. and Q.G. ; Software, H.W. and X.C. ; Supervision, H.X. ; Visualization, M.M.N. ; Writing--original draft, H.W. ; Writing--review and editing, H.X. and X.C. All authors have read and agreed to the published version of the manuscript.