# Model Test on the Behaviors of Deep Excavation with Lateral Confined Water
## 3 Results
### Analysis of Vertical Displacement of the Ground Surface
To mitigate the increase in inward deformation of the diaphragm wall caused by the rise in lateral confined aquifer pressure, the axial force in  
Figure 15: Vertical displacement at the ground surface: (**a**) left side; (**b**) right side. the fourth level of strut increases accordingly. In contrast, in the non-confined aquifer layer (clay layer) above the confined aquifer, the rise in lateral confined water pressure mainly increases vertical pore water pressure, causing the soil above to uplift (Figure 15). The horizontal displacement of the diaphragm wall is relatively small (Figure 12), so the axial forces of the first three struts do not show significant changes. In practical excavation projects, an increase in the confined water level at the sidewalls leads to higher axial forces on the supporting system. This is particularly evident for the fourth level of strut, which is within the confined water depth range, and the second level of strut, which bears the highest axial force. To ensure the stability of the excavation, it is necessary to consider designing stiffer support systems or increasing the number of struts. Figure 17 shows the deformation patterns of the diaphragm wall at lateral confined water levels of 396 mm and 432 mm. Both deformation patterns are approximately parabolic. As the lateral confined water level rises to 432 mm, the diaphragm wall shifts further inward. At the confined aquifer depth, the pore water pressure is higher than in the non-confined aquifer, resulting in a larger inward displacement of the diaphragm wall in the confined aquifer range. The increase in pore water pressure vertically acting on the diaphragm wall exacerbates the deformation. If the assumption is made that the diaphragm wall does not shift inward when the lateral confined water level rises, the increase in external water pressure would lead to a larger horizontal pressure acting on the diaphragm wall [24]. However, since the model diaphragm wall is made of flexible aluminum alloy, deformation occurs when external forces are applied. Therefore, the assumption that the diaphragm wall would not shift inward is unrealistic. In the highly permeable fine sand confined aquifer, water pressure can quickly transmit through the layer, and the water pressure of the diaphragm wall in the aquifer is larger, which easily leads to a shifting inward. In contrast, in the low-permeability clay impervious layer, the rise in lateral confined water level mainly causes upward displacement of the upper clay layer, while the diaphragm wall experiences a smaller increase in water pressure. In conclusion, lateral confined aquifer pressure significantly affects the deformation of the diaphragm wall. As the confined water level increases, the inward displacement of the diaphragm wall becomes more pronounced, with the confined aquifer depth range being particularly susceptible to the effects of lateral confined water pressure. Figure 16: Chart of strut axial force under different lateral confined water levels. The rise in the confined water level at the sidewalls in real-world projects can also cause the diaphragm wall to shift inward toward the pit, leading to increased axial forces in the struts, aggravated surface settlement, and a heightened risk of excavation instability. During the design phase, it is crucial to predict the effects of changes in the confined water level on the diaphragm wall, and design adequate strength and stiffness accordingly. In the construction phase, appropriate measures should be taken to lower the confined water level to reduce diaphragm wall deformation.