## 6 Analysis of Field Monitoring Results  
The on-site monitoring work began after filling the water bags and lasted for 48 days. The first deep-hole monitoring was conducted to obtain baseline data, and the arrangement of monitoring points is shown in Figure 15. On the 14 th day, the water bag filling reached a height of 0.8 m, and the second deep-hole monitoring was carried out. On the 30 th day, the water bag filling reached a height of 1.2 m, and at the same time, 14 additional surface-monitoring points were set up. The sixth round of monitoring was conducted, as shown in Figure 16a. The left diagram displays the initial positions of various monitoring points in the vertical direction, while the right diagram shows the cumulative settlement displacement values of each point after reaching a filling height of 1.2 m, with a significant cumulative settlement displacement in the 20 m depth range. As illustrated in Figure 16b, the left diagram represents the initial positions of various monitoring points in the horizontal direction, while the right diagram presents the cumulative horizontal deformation values of each point after reaching a filling height of 1.2 m. On the 35 th day, the seventh round of monitoring was conducted, as shown in Figure 17. On the 44 th day, the eleventh round of monitoring was conducted, as shown in Figure 18. Finally, on the 48 th day, the last round of monitoring was performed, as depicted in Figure 19.  
Figure 15: Layout of monitoring points.  
By comparison with Figures 17 and 18, it can be seen that the maximum variation of deep settlement in hole 1 is about 40 mm, the maximum deep settlement point is about 25 m, and other monitoring points are generally less than 25 mm. Most of the locations with large settlement deformation are located in the upper part of the roadbed with a hole depth above 15 m. The maximum depth settlement change in hole 2 is about 23 mm, the maximum deep settlement point is located at 4 m-7 m, and most of the locations with large settlement deformation are located in the upper subgrade with a hole depth of more than 15 m. The maximum change in deep horizontal displacement in hole 1 is about 3.5 mm, and the maximum deep horizontal displacement point is located at a hole depth of 22 m-25 m. The maximum depth horizontal displacement of hole 2 is about 3.5 mm, and the maximum depth horizontal displacement is located at about 26 m of the hole depth. Most other monitoring points with large horizontal displacement changes are located at the upper part of the roadbed with a hole depth of more than 20 m. The maximum surface settlement monitoring point is located near the monitoring point on the southernmost side of the slope, which is about 40 mm.  
Figure 16: The monitoring values on the 30 th day.  
Figure 17: The monitoring values on the 35 th day.  
The on-site preloading test demonstrated that the settlement and deformation of the high-embankment fill fell within the range of 23 mm to 40 mm. These settlement values can be effectively managed through suitable compaction methods and settlement allowances, thereby alleviating potential post-construction settlement issues. The monitoring results closely correlated with the numerical simulation findings, affirming the successful control of post-construction settlement in this challenging ultra-high-fill scenario.  
Long-term observations conducted two years after the road's opening, along with the driving experience, were consistent with the earlier test predictions. This validates the accuracy and reliability of the applied methods in ensuring the stability of the high-embankment fill.  
Figure 18: The monitoring values on the 44 th day.