# Bearing Capacity of Shallow Foundations on Unsaturated Silty Soils
## 2 Materials and Methods  
### Material  
Soil samples taken from the city of Adapazar were used in the experimental studies to examine the change in the UBC of the shallow footings on unsaturated soils. The samples were taken from the Yenigun District of Adapazar (Turkey), at a depth of 3-4 m. The properties of the silty soil sample used in this study according to ASTM D4318 [49] are given in Table 2. The soil sample was classified as low plasticity silt (ML) according to the USCS. Figure 3 shows the grain size distribution curve of the sample.  
\begin{table}
\begin{tabular}{c c c} \hline \hline
**Authors** & **UBC Equation** & **Soil Type** \\ \hline [PERSON] et al. (1997) [12] & \(q_{ult}=\left\{c^{\prime}+(u_{a}-u_{w})_{b}tan\mathcal{O}^{\prime}+[(u_{a}-u_{ w})-(u_{a}-u_{w})_{b}]tan\mathcal{S}^{b}\right\}N_{c}+\frac{1}{2}B\gamma N_{\gamma}\) & - \\ [PERSON] \& [PERSON] (2007) [14] & \(q_{ult}=\left\{[c^{\prime}+(u_{a}-u_{w})_{b}tan\mathcal{O}^{\prime}-5^{\Psi} tan\mathcal{O}^{\prime}]+(u_{a}-u_{w})_{AVE}S^{\Psi}tan\mathcal{O}^{\prime}\right\}N_{c} \xi_{c}+\) & Poorly graded sand \\ [PERSON] \& [PERSON] (2013) [18] & \(q_{ult(unstat)}=\left[\frac{q_{u(unstat)}}{2}\right]\times\left[1+0.2\frac{B}{L} \right]\times N_{unstat}\) & Low plasticity clay \\ [PERSON] \& [PERSON] (2016) [32] & \(S_{e}=\left(\frac{1}{1+\left\{-ln\left(1+\frac{1}{\xi}\right)e^{-\gamma max}- \frac{\xi}{4}\right\}^{\pi}}\right)^{\pi-1/a}\) & - \\ [PERSON] et al. (2017) [42] & \(q_{ult}=[c^{\prime}+(\chi^{\delta})_{AVE}tan\mathcal{O}^{\prime}]N_{c}d_{c}+q_ {ult}N_{d}q_{d}+0.5\gamma BN_{\gamma}d_{\gamma}\) & - \\ [PERSON] et al. (2020) [37] & \(q_{ult}=[c^{\prime}+c_{AVE}]N_{c}\xi_{c}+qN_{q}\xi_{q}+0.5B\gamma_{T}N_{\gamma}+ s(N_{s})_{est}tan\mathcal{S}^{b}\xi_{s}\) & Poorly graded sand \\ [PERSON] et al. (2020) [17] & \(q_{ult}=\left[c^{\prime}+(u_{a}-u_{w})_{m}tan\mathcal{S}^{b}\right]N_{c}^{M}+ \sigma_{0}N_{q}^{M}\frac{1}{2}(B\gamma_{T}-u_{a})N_{\gamma}N_{\gamma}^{M}\) & Sand \\ \hline \hline \end{tabular}
\end{table}
Table 1: Bearing capacity models for unsaturated soil.  
Figure 2: The relationship between \(\Psi\) and \(I_{p}\)[14].  
The mineralogical composition of the silt used in this study was determined with an X-ray diffraction analysis and is shown in Table 3. It indicates that elements such as calcium oxide and magnesium oxide, which are the primary cementing agents in the soil, are present in significant amounts in the soil sample [50; 51]. However, studies in the literature have demonstrated that the cementing bonds that are disrupted in remolded samples do not re-form [50; 52]. As a result, when compared to experiments carried out on in situ or undisturbed materials, the cohesiveness of the remolded samples is lower. Furthermore, research suggests that the shear resistance angle is less influenced than the cohesion value [53].  
\begin{table}
\begin{tabular}{c c c} \hline
**Property** & **Value** & **Symbol and Unit** \\ \hline No 200\# & 89 & FC (\%) \\ Liquid limit & 35.8 & LL (\%) \\ Plastic limit & 25.2 & PL (\%) \\ Plasticity index & 10.6 & IP (\%) \\ Specific gravity & 2.692 & Gs \\ Clay ratio & 17 & C (\%) \\ Salt ratio & 72 & M (\%) \\ Sand ratio & 11 & S (\%) \\ \hline \end{tabular} Soil class: Low Plasticity Silt (ML)  
\end{table}
Table 2: Physical properties of the soil used in the experimental study.  
Figure 3: Grain-size distribution of samples used in the study.