# Model Test on the Behaviors of Deep Excavation with Lateral Confined Water
## 1 Introduction
### Testing Procedure  
1. Soil filling: The soil is filled in layers, with each layer having a thickness of 10 mm. Fine sand is compacted by controlling the dry unit weight, with each layer being filled and saturated with water. Clay is filled by controlling the saturated unit weight, also in layers.
2. Installation of diaphragm wall: Once the soil layers are filled to the depth corresponding to the bottom of the diaphragm wall, Vaseline is applied to the sidewalls at the junction of the model box and the diaphragm wall at both ends. The diaphragm wall is then lowered into position, and a plastic film is applied at the junction between the diaphragm wall and the model box. One end of the plastic film is adhered to the sidewall of the model box, and the other end to the diaphragm wall. This film serves as a temporary fixation and water barrier for the diaphragm wall.
3. Installation of monitoring sensors: During the subsequent soil layer filling, the relevant sensors are embedded at the designated monitoring positions for each sensor.
4. Collection of initial sensor values: After completing the soil layer filling and sensor installation, the entire model system is allowed to settle for 24 h. The initial readings from each sensor are then collected.
5. Simulation of lateral confined water: Prior to excavation, the inlet valve is opened, and the water level in the confined aquifer is raised to 396 mm using the water tank to simulate the confined aquifer pressure on the sidewalls. After the excavation and installation of struts, the lateral confined water level is increased to 432 mm. During the test, the lateral confined water level is kept constant.
6. Dewatering, soil excavation, and strut installation: The excavation and dewatering process proceeds in layers. After excavating each layer to the desired depth, the system is stabilized for 30 min before installing the corresponding strut.  
The model test simulates the excavation deformation as a plane strain problem. To minimize boundary effects, Vaseline is uniformly applied to the model box sidewalls and both ends of the diaphragm wall, thereby reducing the friction between the model box sidewalls and the diaphragm wall. During the test, the junction between the diaphragm wall and the sidewall is treated with a plastic film to prevent any hydraulic connection between the inside and outside of the excavation. The transparency of the model box sidewalls allowed for visual inspection, confirming that no seepage paths were observed, thus validating the effectiveness of the plastic film barrier. Additionally, by folding the plastic film at the junction and reserving a part of the plastic film, the plastic film can prevent the constraint effect on the displacement of the diaphragm wall during the test to allow sufficient space for diaphragm wall displacement during the test. Observationsthrough the transparent sidewalls also confirmed that the reserved space in the film was effective in preventing the constraint of diaphragm wall movement.  
The test conditions for excavation and strut installation are summarized in Table 3, with a photo of the test setup shown in Figure 7.