Contribuição aos estudos de correlação chuva vs escorregamentos aplicação às ocorrências da Comunidade da Formiga no ano de 2010.

Abstract

In 2010, the city of Rio de Janeiro registered an extensive number of mass movements. In this period 627 mass movements, particularly concentrated in the months of March and April, were recorded by Geo-Rio Foundation. Among these, 27 occurred in a slope of Tijuca Massif, where Formiga Community is located. For the development of the correlation rain versus soil mass movement in Formiga Community, it was necessary to assess landslides and rainfall event recordings in 2010 at Tijuca s pluviometrical station. According to the critical rainfall rates adopted by GeoRio, 4 landslides did not fit its criteria. This study aimed to focus specifically these four events in 2010. Therefore, a survey was conducted in order to examine all available information in the area such as topography, in situ surveys, tests, etc. The slope has a concave shape forming a gulley at its central region. Residual soil thickness ranging from 2.5m to 18m and massif rock outcrops were observed at the top of the slope. Direct shear test results were available. Visits to the community in 2015 showed the impossibility to access the specific sites of the four landslides. As a result, the studies focused on the critical conditions of the slope based on topography and strength parameters. These analyses demonstrated the importance of apparent cohesion on stability of slopes. Probabilistic analyses showed that the uncertainties in the strength parameters are significative. Thus, the slopes are potentially unstable.