Uso de ensaios geotécnicos na concepção de projetos de recuperação de áreas degradadas: estudo de caso da voçoroca do Jardim Botânico da UFJF, em Juiz de Fora (MG)

Abstract

One of the main factors for the expansion of degraded areas in Brazil and around the world are erosion processes, which can be caused by different agents. Degraded Area Recovery Plans (PRAD) are made to recover these areas. However, the majority of Degraded Area Recovery Projects (PRAD) propose solutions without considering some intrinsic characteristics of soil, such as shear strength and erodibility. Therefore, this research aims to evaluate the use of simple, fast and viable geotechnical tests to understanding the erodibility of a soil from a gully situated in UFJF Botanical Garden, in Juiz de Fora (MG), in order to elaborate a conceptual PRAD. For this purpose, the methodology used was based in a collection of samples for laboratory tests, namely: chemical characterization test, direct shear test and modified Inderbitzen test, and then the stability analysis and the proposition of recovery techniques were done. According to the results of the chemical characterization test, the soil has medium to high acidity, a deficiency in important nutrients, a low organic matter index and a high aluminum saturation index. In the direct shear test, the parameters obtained were: null cohesive intercept and friction angle between 36° and 37.5°. According to the slope stability analysis by GeoSlope software, the 32° angle met the minimum safety factor of 1.2 and was the angle used in the modified Inderbitzen test, in which the samples presented high speed in the erosive process and were classified in a range with the lowest resistance to erosion. From these results, it was possible to propose measures to improve the chemical quality of the soil, which is important for the growth of vegetation; to identify which angle is suitable for re-sloping, taking into account the required safety factor; and to propose more appropriated techniques to contain erosive processes. Therefore, it was confirmed the relevance of carrying out the geotechnical tests, which allowed the elaboration of a well-founded and directed conceptual PRAD, with geotechnical justifications for the full recovery of the gully under study