Change Rule of Crack Widths of CRTSⅡTrack Slab

To study the influence of longitudinal connection forming process of track structure on track slab cracks, a 1/4 unit track slab separate model was established, and the crack problems were analysed. By studying the track structure longitudinal connection forming process, Ⅱslab was found to have unique longitudinal connection and structure characteristics. Based on these, the influencing factors and the change rule of crack widths both in the middle and at the end of track slab were analysed, respectively, when its temperature decreased 30 ℃ and 40 ℃. The results show that with the bonding state weakening between the track slab and mortar layer, the crack width at the end of track slab ${\omega _{\rm{k}}}$ increases slightly, while the crack width in the middle of track slab ${\omega _{\rm{z}}}$ decreases slightly; ${\omega _{\rm{k}}}$ can be increased by 0.032 1 mm at most if track slab has no cracks. Moreover, ${\omega _{\rm{k}}}$ can be increased by 0.026 9 mm at most and ${\omega _{\rm{z}}}$ can be decreased by 0.026 9 mm at most if the track slab has a crack in the middle. The most influential factors on ${\omega _{\rm{k}}}$ are the initial stress at the end of tensioned rebars, and the initial compressive stresses of narrow joints when wide joints harden; there is also the question of whether track slab has a crack in the middle or not. The initial stress at the end of tensioned rebars, when wide joints harden, is the most influential factor on ${\omega _{\rm{z}}}$, and the more it decreases, the smaller ${\omega _{\rm{z}}}$ is. Both ${\omega _{\rm{k}}}$ and ${\omega _{\rm{z}}}$ are distributed unevenly as a result of the longitudinal connection characteristic of track slab, and the numerical value of ${\omega _{\rm{k}}}$ is large because of the weak connection between track slabs. When track slab temperature decreases 30 ℃ and 40 ℃, respectively, numeric ranges of ${\omega _{\rm{k}}}$ are 0.182–1.906 mm and 0.389–2.546 mm respectively, and ${\omega _{\rm{k}}}$ is larger than ${\omega _{\rm{z}}}$usually, which are consistent with the crack characteristics of Ⅱ slab track at present.