## 2 Model Experiments
### Results and Discussion
#### 2.5.2 Maximum Dynamic Earth Pressure  
As shown in Figure 5a, the reinforced geogrid has a certain constraining effect on vertical earth pressure. For example, at a depth of 250 cm, the vertical earth pressure on unreinforced condition is 252 kPa, while the minimum vertical earth pressure on reinforced condition is only 118.2 kPa (A\({}_{3}\)). Figure 5b shows that vertical earth pressure (\(-\)250 cm) decreased by nearly 135 kPa in the reinforced condition. As the depth increases, the constraining effect weakens. Particularly, at depths below \(-\)3.25 m, the constraining effect decreases faster. Above the depth of 3.25 m, the vertical earth pressure decreases sharply (Figure 5c). Furthermore, with increasing C, vertical earth pressure gradually equals to the earth pressure of the unreinforced condition.  
Figure 4: The vertical displacement under three factors: (**a**) embedded ratio; (**b**) number of reinforced layers; (**c**) interval of reinforced layers.  
Below -3.25 m, the constraining effect is so weak that it is consistent with that of unreinforced condition (Figure 5a-c). The deep soil is difficult to compact due to the insufficient vertical earth pressure. The reason is that most of the tamping energy is borne by the reinforced geogrid and a small amount of the energy is transmitted to the deep soil. Note that deep soil compaction could be incomplete if the vertical earth pressure is too small, but the excessive vertical earth pressure could cause large deformation of the reinforced geogrid. In addition, a large upheaval induced by unloading rebound that occurs after construction is harmful to the long-term consolidation and stability of the foundation.  
Figure 6a shows constraint on lateral earth pressure by reinforcement. When the reinforced geogrid was embedded at a deeper position (A\({}_{3}\) = 12 cm), the lateral earth pressure decreased largely and was constrained by almost 24% compared with that of unreinforced condition. The degree of constraint gradually increases with the increase of A. The lateral earth pressure on the condition of A\({}_{2}\) is consistent with that of unreinforced condition. Figure 6b shows the lateral earth pressure changes against the depth, which is similar to the change of vertical pressure. Constrained pressure at a depth of 3.25 m is large and reaches 12.9 kPa approximately under reinforcement. However, B has little effect on lateral earth pressure, since in the conditions of B\({}_{1}\), B\({}_{2}\), B\({}_{3}\), and B\({}_{4}\), the trend of lateral earth pressure is virtually the same. As shown in Figure 6c, C has a significant constraint on lateral earth pressure. When the interval is 8 cm, the constraining effect on the lateral earth pressure reaches its maximum. When the depth is greater than 2.5 m, under different intervals of the geogrid, the trend of lateral earth pressure is different to each other. In the conditions of all intervals (2 cm, 4 cm, 6 cm, and 8 cm) of reinforced layers, the lateral earth pressure at any depth is less than that of the unreinforced condition.  
Figure 5: The vertical earth pressure under different reinforced factors: (**a**) embedded ratio; (**b**) number of reinforced layers; (**c**) interval of reinforced layers.  
In conclusion, reinforcement has a significant constraining effect on lateral earth pressure.