ESTUDO DA ERODIBILIDADE EM HORIZONTES DE TALUDES DE CORTE RODOVIÁRIO POR MEIO DE PROCEDIMENTOS DE LABORATÓRIO E DE CAMPO

Abstract

Erodibility is commonly defined as the proneness which soil particles have for being carried by erosive agent action. Although many studies with agronomic and geotechnical focus have already been developed, there are still gaps regarding cut road slopes, mainly due to the different conditions existing among soil structure. This work presents the erodibility study of soils in cut slopes located in the Quadrilátero Ferrífero region, formed by two horizons with antagonist behavior against erosion. By studying materials under the same environmental conditions, the interference of other parameters can be minimized, conditioning the effect of erosion mainly to the intrinsic soil properties. The disturbed and undisturbed samples were collected and tests of physical, chemical, mineralogical characterization and MCT methodology in laboratory were performed. Soil resistance was evaluated “in situ” condition, by mini vane test and portable penetrometer. As a direct estimation methodology, an erosimeter is proposed to assess soil losses based on South African “Council for Scientific and Industrial Research” (CSIR) erosion resistance test. Clay fractions are higher in resistant horizons (HS), while silt fraction tends to be higher in susceptible soils (HI). The wet aggregate stability test is very efficient in distinguishing potentially erodible soils. The chemical parameters pH (Δ pH), CEC, organic matter and major oxides combined with weathering coefficients show that soils with a higher degree of weathering are less susceptible to erosion processes. The MCT methodology, mainly the tablets test and erodibility criterion, illustrate the different behavior between resistant and susceptible horizons, demonstrating that the lateritic properties confer resistance to erosion. The “in situ” strength and soil mass losses obtained by the erosimeter are promising in the erodibility investigation, allowing to distinguish the behavior of resistant and erodible soils. The post-test contextualization proved to be interesting, since it allowed to verify the sensitivity of the methods used in relation to soil behavior in the field, making it possible to formulate a procedure for erodibility investigation in cut slopes, with emphasis on soil losses determined by the proposed erosimeter.