Osni José Pejon

Analysis of cyclic swelling of mudrocks

Mudrocks are very common rocks that when in contact with water can present considerable volume change and breakdown. The many factors interacting in the swelling phenomenon complicated the approach required to carry out the present work, which focuses on the impact of cyclic wetting and drying on swelling behavior of mudrocks. The samples studied are Cretaceous Age mudrocks (Terres Noires) from the French Alps, Toarcien mudrocks from the Banassac area (south of France), and Tertiary Age mudrocks from the French Central Massif (Marnes of Limagne). Analyses of grain-size distribution, mineralogical composition, pore-size distribution, and cation-exchange capacity were made. Scanning electron microscopy (SEM) registered the condition of samples before and after free and pressure swelling tests. The results showed the importance of rock texture and structure in addition to mineralogical composition. Cyclic wetting and drying of the samples demonstrated the different mudrock behaviors that could be determined with the coefficient proposed in this work.

Engineering geological mapping developed in the Fortaleza Metropolitan Region, State of Ceara, Brazil

Abstract Engineering geological mapping was carried out, at a scale of 1:100,000, in the Fortaleza Metropolitan Region, located in northeastern Brazil, to provide engineering geological information as an aid in planning land use and occupation. In this study, eight basic maps were produced drawing: urban areas, lithology, unconsolidated materials in addition to geomorphological map showing slopes, water resources, engineering geological zoning and distribution of geological–geotechnical environmental problems based on information collected through field and laboratory investigations. The region was divided into nine engineering geological zones analyzed in terms of geohazard susceptibility and foundation, excavation and waste disposal conditions.

Application of induced polarization and resistivity to the environmental investigation of an old waste disposal area

Abstract Waste disposal in dumpsites, or even in sanitary landfills, can generate contamination plumes in the subsurface. The detection and delineation of the shape of the contaminant plume can be assessed using monitoring systems or different site investigation methods, including geophysical methods. This paper presents the results of a geophysical survey conducted to map the soil contamination produced by a waste disposal site located at a geological vulnerable area, characterized by a trench that resulted from the collapse of sandy soils due to erosion. This paper aims to show the improvement in mapping a waste deposit and the contamination produced in sandy soils by integrating resistivity and induced polarization methods. The results of three survey lines performed to map the site are presented—two across the deposit and one external to it; and resistivity, chargeability and normalized chargeability sections were generated. The geoelectrical sections interpretation was integrated with information from monitoring wells to help the characterization of the waste area and to evaluate soil and groundwater contamination. The results show that resistivity identifies the wastes, the contaminated soil and the contamination plume, but it does not distinguish these zones. Normalized chargeability, on the other hand, is more effective in distinguishing the areas with wastes from the areas impacted by the contamination plume.

Elaboração de cartas de zoneamento geotécnico: exemplo da folha de Piracicaba, São Paulo - escala: 1.100.000

This work presents the general engineering geological zoning map of the Piracicaba region at the 1:100.000 scale and the rules adopted for the elaboration of this graphic document in regional engineering geological mapping. Other aspects are discussed, such as the importance of the general engineering geological zoning map in the elaboration of other most specific maps and the fundamental attributes.

Mapeamento geotécnico regional na escala 1:100.000: considerações metodológicas

Methodological considerations are presented on the choice, obtention and graphic representation of attributes in engineering geological mapping, especially at the 1: 100.000 scale. In this scale the selection of attributes should be done by matrices permitting the analysis of relationships among attributes. Such an analysis showed that there are strong relations among the geologic attributes and other kinds considered. Specific and general engineering geological zoning maps are efficient mechanisms for graphic representations of the attributes and for interpretation.