ANÁLISE DE DIFERENTES CENÁRIOS DE ESPACIALIZAÇÃO DOS PARÂMETROS DE RESISTÊNCIA AO CISALHAMENTO DOS SOLOS NO MAPEAMENTO DE ÁREAS SUSCETÍVEIS A DESLIZAMENTOS

Analysis of different spatialization scenarios of soil shear strength parameters in the mapping of susceptible areas to landslides

Abstract

The goal of this research is to analyze the influence of the spatial distribution of the soil shear strength on the mapping of susceptibility to landslides using mathematical modelling. Firstly, twenty Borehole Shear Tests were performed spatially distributed in entire Ribeirão Baú basin (Ilhota/SC), and a georeferenced database of soil shear strength parameters was developed. Fifteen scenarios with data spatialization were generated from the database of soil shear strength parameters. After, two hundred and ten scenarios were obtained using Shallow Landsliding Stability Model (SHALSTAB) for the modeling of susceptible areas to translational landslides. SHALSTAB performed worse on smaller scale scenarios. The modellings validation was performed using five hundred and twenty-six rupture surfaces estimated in the translational landslide scars occurred in the natural disaster of November 2008, for that Prediction Curves were generated and the Area Under the Curve were calculated. Also, a comparison was made between the scenarios with the highest predictive capacity through the Success (IA) and Error Indexes (IE) and the IA/IE rate. According to the validation results, the scenario with weighted average of the soil data using geotechnical units, with 1-m grid, presented the best fit with the November 2008 scars.

Keywords: Soil shear strength parameters. Landslides. Mapping of susceptible areas. SHALSTAB.