## 1 Introduction
### Sampling Site  
The sampling point for this study is located in the southern part of Quito, Ecuador, at 0\({}^{\circ}\)20\({}^{\prime}\)22.27\({}^{\prime\prime}\) S latitude and 78\({}^{\circ}\)33\({}^{\prime}\)52.05\({}^{\prime\prime}\) W longitude, at an approximate elevation of 3182 m above sea level (m.a.s.l.) in the El Rocio de Guamani sector. It is located below the highest point of the Caupicho River Basin in the inter-Andean valley region near Atacazo Hill (Figure 4). According to [PERSON] [39], alluvial deposits predominate in El Rocio de Guamani because of steep slopes, leading to sediment transport through the action of water currents. When locating the drilling point on the water table zoning map (Figure 5), which was created based on data from 115 boreholes that described water tables ranging from superficial to more than 10 m deep, it was found that the area had a water table below 10 m. Consequently, the soil behavior is predominantly unsaturated. \begin{table}
\begin{tabular}{l l l} \hline \hline
**Author** & **Elastic Modulus Equation** & **Parameters** \\ \hline [PERSON] et al. [35] & E\({}_{\text{unsat}}=\text{E}_{\text{s}}\,\times\,\left[1+\left(\alpha\,\,\times \,\left(\frac{(\text{i}_{\text{a}}-\text{i}_{\text{w}}_{\text{o}})}{(\text{p} _{\text{s}}/100)}\right)\,\times\,\,\theta^{\beta}\right)\right]\) & E\({}_{\text{unsat}}\): Unsaturated elastic modulus \\  & E\({}_{\text{s}}\): Saturated elastic modulus \\  & \(\theta\): Water Content \\  & P\({}_{\text{a}}\): Atmospheric pressure \\  & \(\alpha\), \(\beta\): Fitting parameters \\  & E\({}_{\text{d}}\): Dry state elastic modulus \\  & \(\theta_{\text{d}}\) : Water content in dry state \\  & \(\theta_{\text{s}}\) : Water content in saturated state \\  & m : Fitting parameter \\  & E\({}_{\text{c}}\): Elastic modulus due to capillary hardening \\  & E\({}_{\text{a}}\): Elastic modulus due to adsorptive hardening \\  & E\({}_{\text{s}}\): Saturated elastic modulus \\  & E\({}_{\text{d}}\): Dry elastic modulus at capillary regimen \\  & E\({}_{\text{d}}\): Dry elastic modulus at adsorptive regimen \\  & E\({}_{\text{d}}\): Water content at dry state in capillary regimen \\  & \(\theta_{\text{d}}\): Water content at dry state in capillary regimen \\  & m : Fitting parameter \\  & k : Slope or rate of adsorptive hardening \\  & \(\theta_{\text{a}}^{\text{E}}\) max : Affected range of adsorptive water for elastic modulus \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Summary of unsaturated elastic modulus models. Figure 4: Location where the samples were collected. According to [PERSON] [40], the interannual variability of precipitation in the sampling area of southern Quito ranged from a minimum of 0 mm/month to a multiyear average maximum of 300 mm/month, from 1981 to 2014. This pronounced variability caused significant annual fluctuations in the soil water content. Analysis of the precipitation pattern revealed two distinct peaks: a primary peak in April (the wettest month) and a secondary, less-intense peak in October. [PERSON] et al. [41] investigated the effect of 56 days of sample storage on the unconfined compressive strength of silty soil from the El Rocio sector of Guamani, collected at a depth of 1.30 m. They found that, over time, the samples experienced moisture loss, which led to increases in both the peak compressive strength and elastic modulus. This enhancement was attributed to the suction effect resulting from a reduced degree of saturation, reaching its maximum after 28 days of storage when the saturation levels ranged between 68% and 74% and the unconfined compressive strength varied between 150 and 160 kPa. However, the study was limited to characterizing the relationship between storage time and soil strength without providing a detailed analysis of matric suction behavior. In contrast, [PERSON] et al. [42] and [PERSON] and [PERSON] [43] conducted mineralogical analyses using X-Ray diffraction on soils from southern Quito, near Atacazo Hill.