## 4 Discussion  
### Mechanical Behavior in Unsaturated Soils: Effect of Suction and Sample Type  
Two distinct behavioral trends were identified in the analysis of the results: one corresponding to the low-suction range (0-500 kPa), and the other associated with the high-suction range (\(\geq\)500 kPa). This classification allows for a clearer comparison of the mechanical responses of the undisturbed and reconstituted samples, as shown in Table 13. The undisturbed samples fell entirely within the low-suction range, whereas the high-suction range reflected the behavior of the reconstituted samples under conditions of extreme desaturation. Figure 15(a) shows the shear strength behavior within the low-suction range. An exponential increase in the strength was observed, which was well captured by the proposed fitting equation. In contrast, Figure 15(b) illustrates the behavior under the high-suction range, where strength gradually diminished and eventually decreased after reaching a peak shear strength of 195.97 kPa at a matric suction of 2228.22 kPa, with a water content of 11.80% and a degree of saturation of 40.23%. The equation proposed for the low-suction range exhibited a good fit and provided reliable predictions of shear strength within that range. However, when applied to the high-suction range, the goodness of fit decreased because the equation failed to adequately represent the reduction in shear strength observed at higher matric suction levels. Moreover, a clear distinction was observed between undisturbed and reconstituted samples. In general, the undisturbed samples exhibited slightly higher shear strength values even when compared at similar degrees of saturation. Nevertheless, no consistent trend was identified across all the samples. Figure 16(a) illustrates that the relationship between the normal stress and shear strength exhibits an approximately linear trend within the low-suction range. In Figure 16(b), the inclusion of data from the high-suction range revealed a decrease in the rate of strength gain, resulting in a quadratic trend that reached a peak shear strength of 170 kPa at a degree of saturation of 40.23%. Figure 15: Tangent elastic modulus slopes for reconstituted samples. Furthermore, within the low-suction range, the undisturbed samples exhibited a level of data dispersion comparable to that of the reconstituted samples. However, unlike the reconstituted specimens, the undisturbed samples did not exhibit a clearly defined trend. Figure 18a,b illustrate the relationship between shear strength, total normal stress, and matric suction, providing a three-dimensional representation of the influence of suction on the mechanical behavior of the soil under total stress conditions. Figure 18a corresponds to the low-suction conditions and highlights the behavioral differences between the undisturbed and reconstituted samples. Notably, although the undisturbed samples only reached suction values of up to 38.72 kPa, their data points lay above the failure surface generated from the reconstituted samples. Figure 16: Curve relating shear strength and matric suction at: (**a**) Low-suction range; (**b**) High-suction range. Figure 17: Curve relating shear strength and total normal stress at: (**a**) Low-suction range; (**b**) High-suction range. Figure 18b incorporates the behavior under high-suction conditions and reveals the limitation of the \(\phi^{\text{b}}\) angle in maintaining a linear increase. Instead, \(\phi^{\text{b}}\) decreases as the matric suction increases beyond the peak strength, which, in this study, occurred when the reconstituted samples reached 40.23% saturation and a matric suction of 2228.22 kPa. This behavior is consistent with the findings of [PERSON] et al. [12], who reported that in salts, the shear strength increases to a nearly constant value or a peak, followed by a slight decline. Figure 19a shows the trend of the elastic modulus of the reconstituted samples within the low-suction range.