# Model Test on the Behaviors of Deep Excavation with Lateral Confined Water
## 3 Results
### Analysis of Horizontal Displacement of Diaphragm Wall  
The horizontal displacement curves of the diaphragm walls are shown in Figure 12, with inward displacement towards the pit defined as positive. When the lateral confined water level was raised to 396 mm (O), the horizontal displacement at the top of the diaphragm walls on the left and right sides were 0.55 mm and 0.36 mm, respectively. After the excavation of the first soil layer (K1), due to the shallow excavation depth (30 mm), the average increase in horizontal displacement at the top of the diaphragm wall was only 0.07 mm. After the installation of the first level of strut (Z1), the diaphragm wall shifted outward due to the prestress applied by the strut, with the maximum horizontal displacement reaching \(-\)0.32 mm. Following the excavation of the second soil layer (K2), the diaphragm wall, under the unloading effect from excavation, began to shift inward. After the second level of strut was installed (Z2), the movement of the diaphragm wall inward was constrained, with the horizontal displacement at a depth of 100 mm reduced by 0.15 mm. After the excavation of the third soil layer (K3), the inward horizontal displacement of the diaphragm wall increased with depth, reaching a maximum horizontal displacement of 1.31 mm at a depth of 150 mm. Compared to the previous stage, the horizontal displacements at the left and right sides increased by 0.53 mm and 0.45 mm, respectively. After the installation of the third level of strut (Z3), the horizontal displacement continued to increase. This could  
Figure 11: Diachronic curves of strut axial force. be attributed to the maximum positive bending moment of the diaphragm wall at a depth of 200 mm (Figure 9), making it difficult for the third level of strut to resist the inward bending of the diaphragm wall at that depth. After the excavation of the fourth soil layer (K4), the excavation reached the lateral confined aquifer depth, and the water pressure from the confined aquifer further impacted the diaphragm wall, leading to a significant increase in horizontal displacement within the lateral confined aquifer depth range. The maximum horizontal displacements at the left and right sides were 2.05 mm (0.68%D, where \(D\) is the excavation depth) and 2.21 mm (0.73%D), respectively, exceeding the limit values of 0.5%D-0.6%D as specified by MOHURD (2019) [21]. After the installation of the fourth level of strut (Z4), the diaphragm wall continued to shift inward above a depth of 200 mm, while below that depth, the diaphragm wall slightly shifted outward under the influence of the strut. However, the maximum horizontal displacement still did not meet the MOHURD (2019) requirements [21]. After the lateral confined water level was raised to 432 mm (F), the horizontal displacements at different depths increased, with the maximum horizontal displacements at the 250 mm depth on the left and right sides reaching 3.68 mm and 3.85 mm, respectively, which were 2.8 and 2.5 times larger than the displacement at the top of the diaphragm wall. The analysis of the horizontal displacement of the diaphragm wall reveals that the displacement is influenced by a combination of soil excavation, changes in lateral confined water level, and the installation of struts. Excavation-induced unloading disrupts the  
Figure 12: Horizontal displacement of diaphragm walls: (**a**) left side; (**b**) right side. original pressure equilibrium, causing the diaphragm wall to move inward. Strut installation provides additional resistance, limiting the inward movement of the diaphragm wall. However, the unbalanced pressure from the struts may cause the diaphragm wall to shift outward. When the excavation reaches the lateral confined aquifer, the diaphragm wall tends to move inward, with the horizontal displacement increasing most significantly within the confined aquifer depth range.