Integrated Platform for Assessment the Risk of Shallow Landslides Triggered by Rainfall
Slope Stability, Probability of Failure, Surface Landslide, Infinite Slope, FOSM, Unsaturated Soils, Hazard
In recent years, records of human losses associated with mass movements have increased significantly, becoming a latent hazard to communities in mountainous regions. Bearing in mind that the rupture of a massif is not always achieved under saturated conditions and that in some cases, the analysis of the unsaturated phenomenon may be more reliable, this research proposes an integrated platform for assessing the probability of failure in the unsaturated condition, which is the main input for assessing the risk of landslides triggered by precipitation events. In this work, the uncertainties associated with the physical, hydraulic and resistance parameters that define slope stability are incorporated by applying the First-Order Second-Moment Method (FOSM). To do this, the analytical stability model proposed by Cavalcante and Mascarenhas in 2021 is implemented, which was developed for unsaturated porous media considering a transient analysis. To implement the model, a computational routine was developed in the Wolfram Mathematica programming language. The methodology proposed in this research is validated using information from Gerscovich's work published in 1994, which analyzed a landslide associated with precipitation in the Rio de Janeiro region. The implementation of the methodology developed in this thesis demonstrated the importance of migrating from deterministic analysis to probabilistic analysis, making it easier for engineers to use tools that allow them to determine the statistical moments of the properties involved in the physical phenomena and their importance in the scenario chosen for stability analysis. The use of FOSM produced good results in obtaining the probability of failure in the cross-section of the slope, and had a positive performance in terms of computational cost. The analyses carried out for the case study showed the importance of analyzing the previous rainfall to define the initial state prior to the failure event, as this scenario is indispensable for obtaining more realistic hazard profiles. Finally, it is shown that the transient probabilistic approach to slope stability is an excellent alternative for assessing the hazard associated with the occurrence of a mass movement, since, depending on precipitation events, the state of humidity and stress varies within the massif, also changing the statistical dispersion of physical properties along the slope.