# Model Test on the Behaviors of Deep Excavation with Lateral Confined Water
## 3 Results
### Analysis of Horizontal Displacement of Diaphragm Wall
The horizontal displacement is relatively small during the excavation of the shallow soil layers, but when excavation reaches the depth of the lateral confined aquifer, the increase in horizontal displacement is more pronounced. Notably, after the excavation of the fourth soil layer, the maximum horizontal displacement of the deep diaphragm wall exceeds the 0.5%\(D\) limit. To further analyze the variation in horizontal displacement at the top of the diaphragm wall, the displacement curves measured by the dial gauges (543-470B, Suzhou Quantum Instruments Co., Ltd., Suzhou, China) at the top (0 m) are shown in Figure 13. The horizontal displacement exhibits a trend of inward displacement, outward displacement and inward displacement, consistent with the results obtained by the laser rangefinder (Figure 12). When the lateral confined water level was raised to 396 mm (O), both sides of the diaphragm wall top experienced noticeable inward displacement (0.5 mm) due to the pressure from the confined aquifer. After the installation of the first level of strut (Z1), the redistribution of earth pressure caused a reduction in the inward pressure on the diaphragm wall. However, due to the unbalanced pressure effect of the strut, the wall top shifted outward. As excavation deepened (K2-K3), the stiffness of the struts was insufficient to fully counteract the unloading effect, and the inward movement of the diaphragm wall continued. After the excavation reached the depth of the lateral confined aquifer (K4), the inward displacement at the diaphragm wall top also increased. The final horizontal displacements at the top of the left and right diaphragm walls were 1.30 mm and 1.51 mm, respectively, which are consistent with the measurements from Figure 12 (1.31 mm and 1.55 mm). To investigate the influence of lateral confined water pressure on horizontal displacement at the corresponding depth, the horizontal displacement duration curves at a depth of 275 mm are analyzed (Figure 14). Positive and negative values represent the outward and inward displacement of the diaphragm wall, respectively. The installation depth of the fourth level of strut was 270 mm. Due to the prestress applied by the installation of the fourth level of strut (Z4), the diaphragm wall moved outward by approximately 0.2 mm. When the lateral confined water level was raised to 432 mm (F), the diaphragm wall gradually shifted inward and eventually stabilized. The horizontal displacements at  
Figure 13: Horizontal displacement of diaphragm wall top in each test stage. the left and right sides at 275 mm depth increased to \(-1.56\) mm and \(-1.30\) mm, respectively, which are approximately 7.8 times (left side) and 6.5 times (right side) greater than the initial displacement of 0.2 mm. This indicates a change in the displacement direction of the diaphragm wall, accompanied by a notable increase in displacement. This analysis shows that the lateral confined aquifer pressure induces the inward displacement of the diaphragm wall. When the prestress of the strut is insufficient to resist this effect, the direction of displacement changes from outward to inward, and as the confined aquifer pressure increases, the pore water pressure increases, leading to greater lateral pressure on the diaphragm wall (Figure 8). Consequently, the inward horizontal displacement of the diaphragm wall becomes more pronounced.