## 4 Results and Analysis
### Comparative Analysis of the Displacement Response of the Foundation  
In order to ensure the correct setting of ground fissure contact properties and vibration load, the numerical results in this study were verified according to the physical model test results in reference [44]. The train load is simulated by a moving exciter, and the specific test process is shown in the above reference. The displacements of the physical model test and the numerical model were compared, as shown in Figure 8a. By comparing the results of the physical model test and the numerical model test, it can be seen that the stress of  
Figure 7: Measuring line position. the natural foundation obtained through numerical simulation is the same as the changing trend of the stress curve of the natural foundation measured using the model test, which is manifested by the oscillation at the ground fissure, and the average displacement of the hanging wall is greater than that of the football. In summary, the comparison results show that the train load application and the ground fissure contact relationship of the numerical model are reasonable. On this basis, the displacement changes of the high-speed railway crossing ground fissure sites at three angles were analyzed. In the ground fissure zone, the displacement induced by train vibration load increased in the hanging wall of the natural and composite foundation, while decreasing in the football, and the jumping phenomenon was more significant in the natural foundation. Meanwhile, as the intersection angle \(\theta\) between the high-speed railway and ground fissures decreases, the influence range of ground fissures on both types of foundations increases (Figure 8). When \(\theta=90^{\circ}\), the influence range of the composite foundation was reduced by 2 m in the hanging wall and by 5 m in the football compared with the natural foundation. When \(\theta=60^{\circ}\), the hanging wall shrank by 5 m and the football shrank by 8 m. When \(\theta=30^{\circ}\), the hanging wall shrank by 7 m and the football shrank by 8 m. It can be seen that the composite foundation with the pile-raft structure enhanced the ability of the foundation to resist the deformation and damage caused by the ground fissure and effectively reduced the influence range of the ground fissure. Therefore, when the actual construction cannot avoid crossing the ground fissure zone at a small angle, the pile raft can be adopted in the foundation. Figure 9 is the horizontal variation curve of the displacement amplitude inside the foundation (measuring lines 4 and 5; see Figure 7). The displacement of the composite foundation is symmetrically distributed along the center line of the subgrade, and the displacement at the center line of the high-speed railway reaches the maximum. The displacement of the hanging wall is greater than that of the football along the horizontal direction. The load of the central line is large, and on both sides, it is small. However, the difference in displacement response within the embankment is smaller than that of the  
Figure 8: (**a**) Comparison of the physical model and the \(\theta=90^{\circ}\) numerical model; (**b**) \(\theta=60^{\circ}\); (**c**) \(\theta=30^{\circ}\); (**d**) schematic diagram of the location of the survey line and the cross-ground fissures at different angles. foundation outside the embankment toe. The concrete baseplate and CFG pile reduce the differential deformation of the hanging wall and footwall of the ground fissure. Therefore, during the operation of the high-speed railway, the differential settlement of the embankment on both sides of the ground fissure should be concentrated on to avoid ponding in the location of the ground fissure, which will reduce the foundation strength and affect the stability of the high-speed railway. Figure 10 shows the variation in the displacement of the natural foundation and composite foundation along the buried depth on measuring lines 2 and 3 (see Figure 7) of the site orthogonal to the ground fissure.