## 4 Results and Discussion
### The Raised Effective Formation Level
#### 4.4.2 The Raised Effective Formation Level for Deformation Analysis  
Based on finite element analysis, [PERSON] et al. [59] developed a correlation between the height of the earth berm and the effective uniform rise in formation level ahead of the cantilever embedded wall, giving an equivalent maximum wall movement [16; 19]. A series of numerical models are conducted to investigate the raised effective formation level for deformation analysis under both axisymmetric and plane strain conditions.  
Figure 16 illustrates the relationship between the raised effective formation level and the height of the earth berm in the deformation analysis. Additionally, the results of the studies by [PERSON] et al. [59] are included for comparison. It can be observed that under plane strain conditions, the relationship between the raised effective formation level and the height of the earth berm is similar to the findings in [PERSON]'s study. Initially, when the height of the earth berm is relatively low, the raised effective formation level increases linearly with the height of the earth berm. However, as the height of the earth berm increases, the raised effective formation level gradually approaches a constant value of 2.5 m. This implies that, under a given slope gradient and bottom width, there is a certain threshold height for the earth berm beyond which further increases have diminishing effects on reducing the horizontal displacement of the support structure. Moreover, it is noteworthy that [PERSON]'s method provides a reasonable estimation of the raised effective formation level for an earth berm without considering axisymmetric conditions. Compared to plane strain conditions, the relationship between the equivalent excavation depth and the height of the earth berm under axisymmetric conditions shows a similar trend of development. However, when the height of the earth berm exceeds 4.5 m, the equivalent excavation depth does not tend to reach a constant value but continues to increase gradually. Only when the height of the earth berm exceeds 6.0 m does the raised effective formation level approach a larger constant value of 3.6 m. This indicates that under axisymmetric conditions, the earth berm can be better utilized to reduce the lateral displacements of the supporting piles.  
Despite the importance and effect of the clay sensitivity in stability analysis [60; 61; 62], this concern due to the thickness of overburden is not considered. On the other hand, the challenges of converting the 1D to 3D spatial CPT-based spatial stratigraphic mapping of the classified subsurface soil types [63; 64; 65; 66] was not considered due to the scale of the model and study area. Moreover, the impact of the ground water was not taken into account in the numerical simulation, due to the fact that the effects of earth berms are not influenced by the ground water in the case history. The strength, stiffness, and constitutive model of the components in the PRSS may have an impact on the uncertainty of its behavior and therefore needs to be further investigated.  
Figure 15: Typical shape of the failure surface condition with raised effective formation level: (**a**–**c**) under axisymmetric conditions; (**d**–**f**) under plane strain conditions.