# Study on the Influence of Groundwater Variation on the Bearing Capacity of Sandy Shallow Foundation
## 2 Experimental Tests
### Analysis of Simulation Results  
Figure 11 is the p-s curve under different water-level fluctuation ranges. It can be concluded that, with the gradual increase in the fluctuation range, the foundation bearing capacity has a decreasing trend. This trend is in different water-level heights. When the water level height is 100 mm, the fluctuation range increases from 5 mm to 10 mm. The foundation bearing capacity decreases from 294.9 kPa to 287.8 kPa, and the decrease is 2.37%. The decrease is very small, which means that the fluctuation range brings less influence compared with the influence of the water-level height on the foundation bearing capacity. The main reason for the decrease in the bearing capacity is that the increase in fluctuation range will make the area affected by the water table line increase, and the water content of the upper soil layer will rise under the action of the capillary phenomenon, thus reducing the internal friction angle and cohesion of the soil and resulting in a decrease in the shear strength.  
The different water-level fluctuation form of the foundation load-displacement curve is shown in Figure 12. It can be found that different water-level fluctuation forms also influence the foundation bearing capacity. Specifically, the bearing capacity of foundation is larger under a linear water level, medium under a sinusoidal water level and smaller under random function distribution. The influence of the fluctuation form is also relatively small. The foundation bearing capacity is affected by the main reason that fluctuation makes the capillary phenomenon intensify. Water rises from below to above the groundwater level due to capillarity, which increases the saturation of the topsoil. The soil cohesion and  
Figure 11: The p–s curves under different water level fluctuation ranges: (**a**) 50 mm water level, (**b**) 100 mm water level and (**c**) 150 mm water level.  
internal friction angle are reduced, and the shear strength is decreased. As the fluctuation frequency increases, the impact of the capillary phenomenon increases.  
Figure 13 shows the p-s curve at the upper right corner point of the model, the location of the midpoint of the loading plate. The analysis of the figure shows that, with the increasing height of the water level, the bearing capacity of the foundation has a significant decrease. The bearing capacity of the foundation drops from 378.7 kPa to 335.2 kPa as the water level rises from 0 mm to 50 mm. There is a decrease of 11.5%. When the water level rises from 50 mm to 100 mm, the bearing capacity of the foundation drops from 336.8 kPa to 281.4 kPa. There is a decrease of 16.4%. When the water level rises from 100 mm to 150 mm, the bearing capacity of foundation decreases from 281.4 kPa to 191.2 kPa; the rate of decrease is 32.1%. This means that the submerging effect of the water level on the foundation obviously reduces the bearing capacity of the foundation, and the rate of decrease increases with the increase in the water level. This is basically consistent with the conclusion drawn from the test.  
Figure 12: The p-s curves under different forms of water-level fluctuations: (**a**) 50 mm water level, (**b**) 100 mm water level and (**c**) 150 mm water level.