Infiltration analysis in a slope of Serra do Mar for different precipitation scenarios

Rainfall-triggered landslides are hazards that will become more frequent with the intensification of extreme rainfall due to climate change. In Brazil, landslides are already an issue on mountainous regions like Serra do Mar, where the study site is located, and the effects of different rainfall values on the slope’s stability is a key question for risk management. Rainwater infiltration is one of the main landslide triggers and it involves processes that can reduce soil suction, which affects soil shear strength. To investigate how rainwater infiltration affects soil suction profiles in the study site, hydromechanical simulations were carried out for different rainfall scenarios and initial conditions, defined from analyses of available instrumentation records on the region. Geotechnical and hydromechanical characteristics were obtained from previous studies. Three slope sections were analyzed and showed that the higher initial soil water content, the smaller the influence of rainwater infiltration on suction. Finally, the results showed that increasing rainfall values make the average suction obtained from different cross sections become more dispersed than the average suction obtained for low rainfall values. The higher dispersion of suction values ​​in the rainiest scenarios results in greater degrees of geohazard due to increasing uncertainty on this aspect. Therefore, knowing suction values ​​at different depths of the slope and at different rainfall scenarios helps in the preparation of monitoring plans to maintain the safety of highway users and mitigate risks.