## 4 Analysis of Calculation Results
### Track Structure Deformation Analysis  
The influence of the excavation of the new tunnel on the magnetic levitation viaduct is finally reflected in the track structure. Therefore, the deformation values of the left and right magnetic levitation rails in each process are extracted and the dotted line diagram is drawn, as shown in Figures 12 and 13.  
Figure 11: Vertical deformation time history diagram of the existing pier.  
Figure 12: Settlement curve of the existing left rail.  
The upper rails corresponding to peers 71#, 72#, 73#, and 74# and the middle rails of the bridge are named according to the monitoring points. Five rail-row measuring points are arranged along the bridge, one for each of the corresponding four pier positions and one for crossing the mid-span. The layout of monitoring points is shown in Figure 14.  
From the diagram, it can be seen that the settlement trend of the rail row is 'U'-shaped, and the deformation law of the rail row on the left and right lines is almost the same as the deformation trend of the corresponding pier. The deformation values of the left and right line rails at the end of process 11 were analyzed and the deformation diagram was drawn, as shown in Figure 15. It can be seen that the maximum settlement value of each point of the left rail is slightly larger than that of the right rail, so the settlement value of the left rail is taken as an example for analysis. The maximum settlement of each point occurs in process 11. SJC-01-04 is the maximum deformation point and the maximum cumulative deformation point, and the maximum settlement value is 1.56 mm. The maximum settlement value of SJC-01-05 is 1.52 mm. Existing rail deformation values meet the control index requirements.  
Figure 14: Layout of monitoring points.  
Figure 13: Settlement curve of the existing right rail.  
In order to more intuitively show the deformation trend of the rail row in the whole construction process, the vertical deformation values of the typical points SJC-01-02, SJC-01-04, SJC-01-05, SJC-01-06, and SJC-01-08 on the rail row in each process were extracted, and the deformation time history curve was drawn, as shown in Figure 16.  
From the diagram, it can be seen that the vertical deformation of each typical point is the settlement trend. In the initial stage of construction, the excavation section of the new tunnel is far away from the existing structure, so the deformation value is small. As the excavation advances, the deformation value and deformation rate also increase. The deformation rate reaches the maximum when the excavation section reaches the undercrossing point, and then the deformation rate decreases continuously until the deformation reaches the extreme value when the excavation of the process 11 tunnel is completed. Because the right line tunnel adjacent to pier 72# is excavated first and the left line tunnel adjacent to pier 73# is excavated later, the settlement time of pier 73# is later than that of pier 72#. There is a maximum differential settlement of 0.5 mm between piers 72# and 73# in the construction process, but the final differential settlement tends to 0. The final cumulative calculated settlement of the pier is 1.73 mm and the maximum cumulative calculated settlement of the Maglev rail is 1.56 mm. From the relationship between the settlement of the pier and the rail row, it can also be seen that the settlement deformation of the pier will be attenuated after the pier, bearing, bridge, and track beam are finally transmitted to the rail row. Because the crossing section is a continuous beam, the deformation curve of the rail is relatively flat, and there is no obvious differential settlement between the rails.  
Figure 16: Time history curve of existing left rail deformation.  
Figure 15: Comparison of maximum deformation of existing left and right rails.