## 3 Verification of CRTS III Slab Track Deformation Simulation Model  
At present, there are few field tests on the deformation of CRTS III slab track. To verify the accuracy of the simulation model established in this paper, the slab track of a high-speed railway under operation was selected for a field test. The test section was a straight section, the slab was on the elevated and simply supported box girder section, and the three slab tracks were located in the middle of the bridge. The test area was surrounded by farmland and there were no buildings. The displacement sensors and temperature sensors selected for the experiment were demarcated and durability-tested to ensure the credibility of the collected data. The installation of the sensors is shown in Figure 10; two contact displacement sensors (LVDT) were installed at each displacement measuring point, with a total of 20 sensors. The temperature sensors were installed in the middle of the slab,  
\begin{table}
\begin{tabular}{c c c c} \hline \hline  & \multicolumn{2}{c}{**Displacement Variation in**} & \multicolumn{2}{c}{**Displacement Variation of**} \\  & & **the Middle/mm** & **the Edge/mm** \\ \hline Positive & \(10\)\({}^{\circ}\)C/m & \(0.428\) & \(-0.781\) \\ temperature & \(30\)\({}^{\circ}\)C/m & \(0.453\) & \(-0.873\) \\ gradient & \(50\)\({}^{\circ}\)C/m & \(0.477\) & \(-0.981\) \\ \hline Negative & \(-10\)\({}^{\circ}\)C/m & \(-0.035\) & \(0.0464\) \\ temperature & \(-30\)\({}^{\circ}\)C/m & \(-0.061\) & \(0.155\) \\ gradient & \(-50\)\({}^{\circ}\)C/m & \(-0.085\) & \(0.252\) \\ \hline \hline \end{tabular}
\end{table}
Table 5: Displacement changes in the middle and edge of the slab track under positive and negative temperature gradients.  
Figure 9: Simulation results of vertical displacement of slab track under positive and negative temperature gradients.  
At the same time, to verify the accuracy of the ballastless track displacement simulation results, the simulation results were compared with the measured slab displacement results. The comparison between the measured and simulated results is shown in Figure 14. The simulation results are slightly less than the measured displacement of the slab track. This error may be mainly caused by the following factors: When the temperature load in the slab track was applied, the calculated entire temperature field was not imported into the ballastless track stress-strain model. The stress-strain model of the ballastless track does not consider the setting of the internal steel reinforcement, and there is no prestressing force in the ballastless track. The displacement difference between the simulation results and the measured results in the middle of the slab is 0.015 mm, and the trend of the simulation results and the measured results is the same. In high-temperature weather, the middle of the slab track was deformed upward, and the edge of the slab was deformed downward. Therefore, the stress-strain model of the ballastless track can be used to study the deformation trend and deformation process of the slab track under temperature loads.  
In summary, the stress-strain model of CRTS III slab ballastless track developed in this study can reflect the temperature field inside the slab track and the vertical displacement of the slab track at the macro-level under the condition of meeting the accuracy requirements. According to the simulation results, combined with meteorological conditions, it can provide technical data for the maintenance and repair of CRTS III slab track, focusing on targeted maintenance and repair.  
Figure 14: Comparison of measured displacement and simulation results of slab track.  
Figure 13: Comparison between the simulation and measurement results of the slab track temperature.