PROPRIEDADES GEOLÓGICO-GEOTÉCNICAS DE UM SOLO COLUVIONAR EM ENCOSTA NATURAL CORTADA POR UMA DUTOVIA

The Serra do Mar, in the state of Paraná, Brazil, is marked by a relief with unstable areas, which is eventually subjected to mass movements along their slopes, primarily caused by the large amounts of rainfall that occur in such area. Within this scenario fits a pipeline conduit for the transportation of fuels, often bordering slopes in a situation of precarious balance. It is widely known that lithological, structural and geomorphic features play a major role in the slopes stability. Thus, it is important to understand the dynamics of these movements in order to preserve the physical integrity of the duct. Areas where the slope represents critical points of instability were selected for the study along the pipeline section. The main objective of this work is to investigate the geological and geotechnical features of the area cut by the pipeline in order to assess possible mass movements. This work was achieved by a combination of field research, remote sensing, characterization of the colluvial soils and obtaining of geomechanical and hydraulic parameters.

Issues relating to classification of colluvial soils in young morainic areas (Chełmno and Brodnica Lake District, northern Poland)

Colluvial soils (in Polish: gleby deluwialne) are an important part of the soil cover in young morainic landscapes of northern Poland. They evolved as a result of the accumulation of eroded material at the foot of the slopes and bottoms of closed depressions. The aim of this study was to determine the systematic position of colluvial soils commonly found in the Chełmno and Brodnica Lake District, northern Poland. Ten soil pits located in different types of landscapes were selected for testing soil properties. The colluvial material is characterized by diversified properties: thickness, particle-size distribution, organic carbon content, color, pH, and base saturation. As a result, the investigated soils represent broad spectrum of typological units according to Polish Soil Classification (2011). Some of them contain epipedons mollic and meet the criteria of colluvial chernozemic soils. They were found mainly on buried black earths in areas with small slope inclinations. Many pedons contain pale colored acidic colluvial material with low base saturation and low organic carbon content and must be classified as other types: arenosols (in Polish: arenosole) or rusty soils (in Polish: gleby rdzawe). These soils occur mostly in areas with intensive relief and overlay the different soil types, including rusty soil and organic soils. They are formed as a result of soils lessivés and rusty soils truncation. An introduction of the additional units of “proper colluvial soils” which have epipedon ochric, and “rusty-colluvial soils” with endopedon sideric to the next edition of Polish Soil Classification would enable a more precise expression of the genesis of these soils in the type rank. Moreover, the definition of chernozemic colluvial soils could be extended to colluvial soils with umbric horizon. Classifying soils derived from colluvial material as soils of other types leads to the disappearance of this units on maps and underestimation of the impact of denudation on the soil cover.