# The Effect of the Water Table on the Bearing Capacity of a Shallow Foundation
## 1 Introduction
### Mechanical Properties of Soil  
The original ring-knife soil sample with area S = 30 cm\({}^{2}\) and height H = 2 cm was prepared in the laboratory. Using the DGY-2H consolidation instrument and DJY-4 direct shearing instrument, laboratory compression and consolidation quick shear tests under natural and saturated conditions were carried out for the low liquid limit clay of the building foundation in the reservoir area. The saturation adopts the pumping saturation method. For the compression test, LTC1\(-\)1, LTC1\(-\)2, LTC1\(-\)3, and LTC1\(-\)4 samples were used. Low liquid limit clays in the natural and saturated state were taken for each sample. The loading pressures were 50 kPa, 100 kPa, 150 kPa, 200 kPa, 250 kPa, and 300 kPa, respectively. For the shear test, the selection of soil samples is the same as that of the compression test. The loading pressure is changed to the consolidation pressure of 100 kPa, 200 kPa, 300 kPa, and 400 kPa, and the shear rate is set to 0.828 mm/min. For the test operation and data arrangement, please refer to the _Specification for soil test (SL 237-1999)_[34]. Table 2 gives the basic mechanical properties of low-liquid limit clay in natural and saturated states. It can be seen from Table 2 that in the natural state, the compressibility a\({}_{v1-2}\) of Lu-ohuang Town's low liquid limit clay was 0.190 MPa\({}^{-1}\)-0.291 MPa\({}^{-1}\), the average value was 0.254 MPa\({}^{-1}\), the compressive modulus \(E_{\text{s1-2}}\) was 6.160 MPa\({}^{-8.85}\) MPa, the average value was 7.195 MPa, \(C_{\text{cq}}\) was 8.9 kPa\({}^{-2}\)6 kPa, the average value was 15.88 kPa, \(\Phi_{\text{cq}}\) was 23.3\({}^{\circ}\)-27.3\({}^{\circ}\), and the average value was 25.83\({}^{\circ}\). Under the saturated state, its compressibility a\({}_{v1-2}\) was 0.214 MPa\({}^{-1}\)-0.399 MPa\({}^{-1}\), the average value was 0.320 MPa\({}^{-1}\), compressive modulus \(E_{\text{s1-2}}\) was 4.02 MPa\({}^{-7.86}\) MPa, the average value was 5.67 MPa, \(\Phi_{\text{cq}}\) was 3.0 kPa\({}^{-11.1}\) kPa, the average value was 7.73 kPa, \(\Phi_{\text{cq}}\) was 23.1\({}^{\circ}\)-29.0\({}^{\circ}\), with an average value of 24.23\({}^{\circ}\). It can be seen from the above analysis that the cohesion \(C_{\text{cq}}\) of the low liquid limit clay in Luohuang Town has a certain discreteness under natural and saturated conditions, and the other indicators have little difference. Through the statistical analysis of the test results, it was suggested that the average value of soil mechanics parameters in Luohuang \begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline \multirow{3}{*}{\begin{tabular}{c} **Soil** \\ **Sample** \\ **Number** \\ **Number** \\ **(m)** \\ \end{tabular} } & \multirow{3}{*}{\begin{tabular}{c} **Sampling** \\ **Depth** \\ **(m)** \\ \end{tabular} } & \multirow{3}{*}{\begin{tabular}{c} **Natural Physical** \\ **Property Index** \\ **Water** \\ **Content** \\ \end{tabular} } & \multirow{3}{*}{**Soil Type**} & \multirow{3}{*}{**Sample State**} & \multirow{3}{*}{\
\begin{tabular}{c} **Compression** \\ **Index** \\ **\end{tabular} } & \multirow{3}{*}{
\begin{tabular}{c} **Consolidation** \\ **Quick Shear** \\ **\end{tabular} } \\  & & & & & & \(a_{v1-2}\) & \(E_{\text{s1-2}}\) & \(C_{\text{cq}}\) & \(\Phi_{\text{cq}}\) \\  & & & & & \(MPa^{-1}\) & MPa & kPa & \(\circ\) \\ \hline LTC1-1 & 2 & 15.8 & 51.0 & Low liquid & Natural & 0.252 & 7.24 & 26 & 27.3 \\  & 15.8 & 55.1 & limit clay & Saturation & 0.399 & 4.02 & 6.5 & 24.1 \\ LTC1-2 & & 17.5 & 58.9 & Low liquid & Natural & 0.291 & 6.16 & 17.2 & 25.8 \\  & & 17.5 & 61.3 & limit clay & Saturation & 0.369 & 4.78 & 10.3 & 24.7 \\ LTC2-3 & 2.5 & 25.2 & 99.8 & Low liquid & Natural & 0.190 & 8.85 & 8.9 & 26.9 \\  & & 25.2 & 99.8 & limit clay & Saturation & 0.214 & 7.86 & 3.0 & 25.0 \\  & & 27.9 & 89.0 & Low liquid & Natural & 0.283 & 6.53 & 11.4 & 23.3 \\  & & 27.9 & 95.4 & limit clay & Saturation & 0.297 & 6.02 & 11.1 & 23.1 \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Luohuang Town mechanical properties test results.