# The Effect of the Water Table on the Bearing Capacity of a Shallow Foundation
## 3 Influence of Immersion on the Bearing Capacity of Shallow Buried Foundation
### Determination of Immersion Critical Groundwater Depth
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline \multicolumn{1}{c}{**Groundwater to**} & \multicolumn{1}{c}{**z/(b/2)**} & \multicolumn{1}{c}{\(P_{\rm z}\) **(kPa)**} & \multicolumn{1}{c}{\(P_{\rm c}\) **(kPa)**} & \multicolumn{1}{c}{\(f_{\rm ac}\) **(kPa)**} & \multicolumn{1}{c}{\(P_{\rm Z}+P_{\rm CZ}\)**} \\ \multicolumn{1}{c}{**Foundation Bottom z (m)**} & \multicolumn{1}{c}{**z/(b/2)**} & \multicolumn{1}{c}{\(P_{\rm z}\) **(kPa)**} & \multicolumn{1}{c}{\(P_{\rm c}\) **(kPa)**} & \multicolumn{1}{c}{\(f_{\rm ac}\) **(kPa)**} & \multicolumn{1}{c}{\(P_{\rm Z}+P_{\rm CZ}\)**} \\ \hline
0.3 & 0.3 & 106.43 & 46.67 & 142.52 & 153.10 \\
0.4 & 0.4 & 104.47 & 48.50 & 144.35 & 152.97 \\
0.5 & 0.5 & 100.77 & 50.33 & 146.18 & 151.10 \\
0.6 & 0.6 & 97.072 & 52.16 & 148.01 & 149.23 \\
0.7 & 0.7 & 92.07 & 53.99 & 149.84 & 146.05 \\
0.8 & 0.8 & 87.06 & 55.82 & 151.67 & 142.88 \\
0.9 & 0.9 & 81.62 & 57.65 & 153.50 & 139.26 \\
1 & 1 & 76.18 & 59.48 & 155.33 & 135.65 \\ \hline \hline \end{tabular}
\end{table} 
Table 11: Calculation results of foundation bearing capacity (b = 2.0 m, d = 2.25 m). the bearing capacity of the foundation is related to the cohesion, internal friction angle of the foundation soil, and the weight of soil mass above and below the foundation bottom. Therefore, the storage state and dynamic changes of groundwater have a significant impact on the bearing capacity of the foundation. Figure 7 is a schematic diagram of the safe depth affected by the groundwater level rise. It can be seen from the figure that \(P_{x}+P_{cz}\) decreases with the increase of z, and \(f_{ac}\) increases with the increase of z. The x-axis coordinate of the intersection is the safe depth affected by the groundwater level rise. When b = 1.5 m and d = 2.5 m, the limit depth is 0.40 for the influence of groundwater level rise. When b = 2.0 m and d = 2.5 m, the limit depth of the impact of groundwater level rise was 0.520. When b = 2.5 m and d = 2.5 m, the limit depth of the impact of groundwater level rise was 0.650. When b = 3.0 m and d = 2.5 m, the limit depth was 0.780 for the impact of groundwater level rise. When b = 2.0 m and d = 2.0 m, the limit depth for the impact of groundwater level rise was 0.70. When b = 2.0 m and d = 2.25 m, the limit depth was 0.625 for the impact of groundwater level rise. When b = 2.0 m and d = 2.75 m, the limit depth for the impact of groundwater level rise was 0.398. When the water level rises, the cohesion force and the internal friction angle gradually decrease with the increase of saturation, the effective weight of the soil decreases, and the pore water pressure gradually increases. Therefore, with the rise of the water table, the bearing capacity of the groundwater table shows a decreasing trend. Figures 8 and 9 show the variation curves of the limit depth affected by the rise of the groundwater level with the width and burial depth of the basement. It can be seen that under generally similar other conditions, the limit depth of the influence of the rise of the groundwater level on the independent foundation increases with the increase of the width of the foundation and decreases with the increase of the buried depth of the foundation. According to Formula (3), when the foundation width increases, the ultimate bearing capacity of the foundation also increases. As the burial depth increases and the foundation width remains unchanged, it can be seen from \((F_{k}+G_{k})/A\) that the sum of the additional stress and self-weight stress at the groundwater table will gradually decrease. Therefore, the bearing capacity of the foundation will also gradually decrease, and the allowable safety depth will decrease with the increase of the buried depth of the foundation.