## 4 Analysis of the Test Results
### Relative Displacement between the Track System Layers
#### 4.2.1 Vertical Relative Displacement between Layers
In the process of a temperature cycle for a single day, the vertical relative displacement curve between the track slab and base slab at each time is shown in Figure 9. Taking the curve analysis at 19:00 and 7:00, the following conclusions can be drawn: At 19:00 on the test day, the vertical relative displacement values of the track slab and base slab at 0 L and 1/2 L indicate that the two structural layers are away from each other, and the vertical relative displacement values of the track slab and base slab at 1/4 L indicate that the two structural layers are close to each other; at 7:00 on the next day, the vertical relative displacement values of the track slab and base slab at 0 L and 1/2 L indicate that the two structural layers are close to each other, and at 1/4 L, the layers are far away from each other. During the whole process of the test, the two structural layers at the section of 3/4 L and L are always away from each other, and the vertical relative displacement value increases first and then decreases with the change in temperature. It can be seen from the curve in Figure 10 that under the action of daily temperature loads, the vertical relative displacement difference between the track slab and the base slab at sections 0 L, 1/4 L, 1/2 L, 3/4 L and L of the test beam decreases successively at approximately 0.040 mm, 0.030 mm, 0.025 mm, 0.020 mm, and 0.003 mm, respectively. In the process of a temperature cycle for a single day, the upper surface of the track slab is in contact with the atmospheric environment, the lower surface is bonded to the CA mortar layer, and the base plate is located between the CA mortar layer and the beam body. According to the analysis of the spatial position and relative displacement results of the two structural layers, it is inferred that (due to the joint action of the shear slot and the mortar layer) the vertical relative displacement between the track slab and the base plate is constrained, which makes the relative displacement between the track slab and the base plate near the beam end of the shear slot side relatively large, and the relative displacement on the other side is essentially zero. The vertical relative displacement curve between the track slab and the CA mortar layer at different times is shown in Figure 10. Combined with the analysis of the ambient temperature, the following conclusions can be drawn: With the periodic change in the ambient temperature, the vertical relative  
Figure 9: The displacement between the track slab and base slab. displacement between the track slab and the CA mortar layer at each position increases gradually at first, then decreases to zero and increases reversely; at 19:00 on the day of the test and 7:00 on the next day, the vertical relative displacement between the track slab and the CA mortar layer reaches the two poles of the whole test process, and the sign of the two values is opposite. At 19:00, the ambient temperature is high, and the vertical relative displacement values for the track slab and CA mortar layer at sections 0 L, \(\frac{1}{4}\) L and \(\frac{3}{4}\) L indicate that the two structural layers are far from each other, and \(\frac{1}{2}\) L and L are close to each other; on the contrary, the ambient temperature is low at 7:00 the next day, and the vertical relative displacement values for the track slab and CA mortar layer at sections 0 L and \(\frac{1}{4}\) L indicate that the two structural layers are close to each other, and \(\frac{1}{2}\) L and L are away from each other.