## 4 Conclusions  
This research analyzed slope stability behavior under rainfall infiltration conditions using two types of soil: a poorly graded sand with 6.5% fines (SP-SM) and a well-graded sand with 11.9% fines (SW-SM). Numerical models were developed in Plaxis 2D to simulate the effect of water infiltration on slopes, considering different rainfall durations with an intensity of 30 mm/hr and evaluating the impact on the safety factor for each soil type. The results revealed that SW-SM soil, with its higher fine content and better gradation, exhibited a more significant decrease in its safety factor as rainfall duration increased, reaching levels close to instability after 24 h of continuous precipitation. This is due to its greater suction retention capacity and water accumulation, which increase saturation and reduce the material's shear strength. In contrast, SP-SM soil showed lower sensitivity to infiltration, maintaining its safety factor relatively stable even during prolonged rainfall. This low sensitivity is attributed to its lower fine content and more permeable structure, allowing rapid infiltration dissipation without drastically affecting the soil's internal suction. Additionally, the analysis of initial safety factors without rainfall showed that slopes composed of SW-SM soil were significantly more stable in the absence of rainfall than those with SP-SM soil, due to its higher cohesion and lower saturated unit weight. However, under rainfall conditions, SW-SM soil experienced greater suction loss and reduced its safety factor, making it more prone to instability during prolonged rainfall events. This study provides important contributions to the practice and theory of slope stability under rainfall infiltration conditions. In practical terms, the results provide a detailed approach to evaluate the impact of rainfall on slopes with soils of different mechanical and hydraulic characteristics, which can be applied in geotechnical designs and risk mitigation strategies in regions prone to heavy rainfall. At the theoretical level, the analysis reinforces understanding how soil properties, such as cohesion, fines content, and permeability, interact with rainfall conditions to influence the safety factor and slope stability. However, this study has some limitations. The simulations were performed under ideal conditions without considering external factors such as vegetation, subsurface drainage conditions or seismic events, which could significantly influence the results. Inaddition, the analysis focused only on two soil types and did not include broader variations in mechanical or hydraulic properties. Future studies could build upon this work by expanding the range of soil types considered, including silty and clayey sands, and by performing sensitivity analyses on key hydro-mechanical parameters such as initial suction, permeability, and van Genuchten parameters (e.g., \(\alpha\), \(n\), \(\theta\)r, \(\theta\)s). These analyses would help quantify the influence of soil-water retention behavior on pore pressure evolution and safety factor variation. Additionally, future research could explore the effect of slope geometry, such as changes in inclination and height, on stability under different rainfall scenarios. A promising direction also involves integrating soil-vegetation interactions through coupled hydro-mechanical models that account for root reinforcement and evapotranspiration, offering a more realistic representation of natural slopes. Moreover, the adoption of stochastic or probabilistic rainfall models could improve the identification of threshold conditions for failure. Collectively, these methodological enhancements would improve the generalizability, accuracy, and practical relevance of slope stability assessments in areas exposed to intense or prolonged precipitation. Conceptualization, R.G.-S. and P.F.F. ; methodology, R.G.-S.; software, J.B.; validation, R.G.-S. and P.F.P.