# The Effect of the Water Table on the Bearing Capacity of a Shallow Foundation
## 1 Introduction
### Influence of Saturation on Mechanical Property of Building Foundations  
To analyze the influence of reservoir water table changes on the bearing capacity of building foundations, laboratory compression and consolidation quick shear tests with different saturation levels were carried out on typical low liquid limit clay in undisturbed samples of building foundations in Luohuang Town. Using the principle of water content to control saturation, samples with different saturation were prepared by dehumidifying or adding water to the undisturbed soil in its natural state. Four kinds of saturation were prepared for typical soil samples (LTC1\(-\)1, LTC2\(-\)4), respectively, while other conditions were controlled to be as similar as possible, and the influence of saturation on the mechanical properties of building foundation soil was analyzed. For the test operation and data arrangement, please refer to _Specification for soil test (SL 237-1999)_[34]. Table 3 shows the basic mechanical properties of typical soil samples in Luohuang Town under different saturation conditions. It can be seen from Table 3 that when the saturation of the LTC1\(-\)1 soil sample increased from 51.0% to 100.0%, its compressive index increased from 0.252 MPa\({}^{-1}\) to 0.399 MPa\({}^{-1}\) and the compressive modulus decreased from 7.24 MPa to 4.02 MPa. The cohesive force was reduced from 26.0 kPa to 6.5 kPa, and the internal friction angle was reduced from 27.3\({}^{\circ}\) to 24.1\({}^{\circ}\). When the saturation of the LTC2\(-\)4 soil sample increased from 46.50% to 100.0%, its compressive index increased from 0.195 MPa\({}^{-1}\) to 0.297 MPa\({}^{-1}\), and the compressive modulus decreased from 9.28 MPa to 6.02 MPa. The cohesion force was reduced from 26.9 kPa to 11.1 kPa, and the internal friction angle was reduced from 27.8\({}^{\circ}\) to 23.1\({}^{\circ}\). \begin{table}
\begin{tabular}{p{56.9 pt} p{56.9 pt} p{56.9 pt} p{56.9 pt} p{56.9 pt} p{56.9 pt} p{56.9 pt} p{56.9 pt}} \hline \hline \multicolumn{1}{c}{\multirow{2}{*}{\begin{tabular}{} \end{tabular} }} & \multicolumn{2}{c}{**Sail Type**} & \multicolumn{1}{c}{**Sail Type**} & \multicolumn{1}{c}{**Saturation**} & \multicolumn{2}{c}{**Mechanical Property Index**} & \multicolumn{2}{c}{**Consolidation of Quick**} \\ \multicolumn{1}{c}{\multirow{2}{*}{\begin{tabular}{} \end{tabular} }} & \multicolumn{1}{c}{**Depth**} & & & \multicolumn{1}{c}{**Compression Index**} & \multicolumn{2}{c}{**Shear Index**} \\ \multicolumn{1}{c}{\multirow{2}{*}{\
\begin{tabular}{} \end{tabular} }} & \multicolumn{1}{c}{**Classification Criteria**} & \multicolumn{1}{c}{**Sr**} & \multicolumn{1}{c}{**\(a_{\textbf{v1-2}}\)**} & \multicolumn{1}{c}{**\(E_{\textbf{s1-2}}\)**} & \multicolumn{1}{c}{**\(C_{\textbf{cq}}\)**} & \multicolumn{1}{c}{**\(\Phi_{\textbf{cq}}\)**} \\ \multicolumn{1}{c}{\multirow{2}{*}{
\begin{tabular}{} \end{tabular} }} & \multicolumn{1}{c}{**m**} & **SL 237-1999**[33] & **\%** & **MPa-1** & **MPa** & ** kPa** & \(\circ\) \\ \hline \multirow{3}{*}{LTC1\(-\)1} & \multirow{3}{*}{2} & \multirow{3}{*}{Low liquid limit clay} & 51.0 & 0.252 & 7.24 & 26 & 27.3 \\  & & & 70.5 & 0.315 & 5.91 & 16.3 & 25.5 \\  & & & 84.2 & 0.378 & 4.89 & 11.9 & 24.8 \\  & & & 100 & 0.399 & 4.02 & 6.5 & 24.1 \\ \hline \multirow{3}{*}{LTC2\(-\)4} & \multirow{3}{*}{2.5} & \multirow{3}{*}{Low liquid limit clay} & 46.5 & 0.195 & 9.28 & 26.9 & 27.8 \\  & & & 66.8 & 0.233 & 8.05 & 18.5 & 26.4 \\ \cline{1-1}  & & & 84.6 & 0.264 & 6.79 & 12.2 & 24.5 \\ \cline{1-1}  & & & 100 & 0.297 & 6.02 & 11.1 & 23.1 \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Effect of saturation on mechanics index of soil in Luohuang Town. Figures 2 and 3 show the variation curves of the compressive and mechanical indexes of Luohuang Town LTC1\(-\)1 and LTC2\(-\)4 soil samples with saturation. It can be seen from the figure that under the same other conditions, with the increase of saturation, the compressive index of low liquid limit clay gradually increases, while the compressive modulus gradually decreases.