## 2 Experimental Setup
### Test Procedure  
First of all, the soil box was filled with the sand at a relative density of 60%, achieved through a mobile pluviator. The dried sand was then poured from the mobile pluviator hopper at a height of 0.45 m. The height of the fall was kept constant for a sand layer of 0.15 m by providing marks inside the soil box to ensure a relative density of 60%. In this way, the soil was rained into the soil box in 10 equal layers of 0.15 m thickness. During the air pluviation process, the hopper was constantly moved through the wheels in three dimensions to achieve a uniform sand surface. The model piled raft was placed exactly  
Figure 5: Mobile pluviator installed above the soil box. Figure 6: Shutters of different porosity. in the center of the soil box after the soil box was filled to a height of 1.2 m through air pluviation. Following the placement of the model piled rafts, air pluviation continued until the soil level reached a height equal to two-thirds of the pile length, as shown in Figure 7. The raft was then removed, and the remaining soil was poured into the soil box via air pluviation to the final depth. To avoid soil disturbance, the raft was installed above the piles again, with each pile held in place with a special type of wrench. The excess sand was removed and the leveling of the model piled raft was checked with the leveling tool. Pile load cells, vertical load cells, and transducers were connected to the computer-controlled data logger, as shown in Figure 8.  
A vertical load cell of a 10 t capacity was installed for vertical load measurement. After checking all connections and arrangements, the model piled raft was then subjected to a vertical static load of 5250 N through the steel plates, and all data were stored in a MATLAB text file. A vertical static loading assembly was designed and fabricated out of steel plates and had the total load capacity of 5250 N, as shown in Figure 8. As for as our experimental testing, it involved the special arrangement of installing the LVDTs with the capacity of 25 mm on both sides of the raft for vertical settlement determination during the application of the vertical loads, as shown in Figure 9.  
Figure 8: Experimental work arrangements in the field. Figure 7: Piled raft model placement during air pluviation. After the vertical static loading test, a connection for lateral load cells was made and connected with the data logger. The purpose of applying the vertical load first, then the lateral load, was to simulate the actual condition. As is commonly observed, the foundation is loaded with a superstructure load and then endangered with various types of lateral loads, such as wind load, earthquake, and water pressures, among others. The vertical transducers (LVDTs) were removed, and the lateral transducers were installed and connected to the side of the raft. The lateral load of 1500 N was applied through the hydraulic lateral load machine, and the load cell data were stored in the MATLAB text file. This type of loading machine, shown in Figure 10, is hydraulic and based on having two hydraulic motors equipped with chains. A load cell installed in this machine was of 50 KN capacity and installed at the front of the hydraulic jack, through which a lateral point load was applied by a 50 KN capacity lateral load hydraulic machine, which was fabricated especially for this purpose. The rate of application of the load by the hydraulic pumps was maintained at a very slow rate and was approximately equal to 4.9 N/s. The purpose of applying the load at this much slower rate was to capture the lateral load distribution with the increase in lateral load. As the model piled raft was very small, it needed special attention to data acquisition to obtain a clear insight into the model resistance. In the data acquisition system, a data logger was used, as shown in Figure 11. The data logger worked at the frequency of 10 readings per second and its was voltage controlled.