Estudo das características geotécnicas e análise de estabilidade de taludes de solos residuais em Areia-PB.

Abstract

Mass movements can be caused by factors in different categories such as geological factors, climate change and human activities. From a geological point of view, the soil profile and the geotechnical properties of the materials that compose it are crucial in influencing slope instability. From the perspective of climate change, the intensity of rainfall is one of the main triggers of mass movements. Included by the Mineral Resources Research Company (CPRM) as a danger zone for flooding, landslides and river overflows due to rain in 2017, the municipality of Areia/PB presents landslides that occur mostly in the rainy season. Such events lead to the presumption that the infiltration of rainwater is responsible for the rupture of the city's slopes. Thus, the studies proposed in this research aim to determine the influence of rainfall on the stability of the slopes present in the municipality. The identification of areas susceptible to mass movements was based on the CPRM report and comparison with maps of the municipality's geomorphometric variables created from Remote Sensing data. The standard penetration tests of the slopes identified soils that have consistencies varying from soft to hard along the depths of the slopes belonging to the risk areas. Presence of a water table was not identified on the slopes, indicating that the soils were in an unsaturated state. The soils presented lower shear stresses when flooded and in their natural moisture content they presented variations indicative of the heterogeneity in the samples resulting from the weathering. In their natural moisture content, the soils showed significantly greater deformations when flooded with a sudden and large decrease in volume, evidencing a high potential for collapse. It was concluded that antecedent precipitation appears to have a greater influence on stability, so daily precipitation alone cannot be used as a determinant for landslide. Lastly, it is important to note that the role of antecedent precipitation in slope stability will not be the same for slopes in different locations that have soils with different properties, different surface conditions, variable tropical rainfall or different microclimatic conditions.