Hysteresis phenomenon of a tropical soil profile observed by means of soil water characteristic curves obtained in laboratory and field

Brunno Henrique Bonder, Miriam Gonçalves Miguel

In the proceedings of: GEO2011: 64th Canadian Geotechnical Conference, 14th Pan-American Conference on Soil Mechanics and Geotechnical Engineering, 5th Pan-American Conference on Teaching and Learning of Geotechnical Engineering

Session: Behaviour of Unsaturated Soils

ABSTRACT: This research presents the soil-water characteristic curves (SWCC) for a tropical soil profile from the region of Campinas, Brazil. This profile consists of colluvial, lateritic and collapsible silty clay about 6.5m thick. From this profile, soil samples were collected and submitted to geotechnical characterization and mineralogical tests. From the soil samples, specimens were made and used to determine the SWCC using the filter paper method with wetting and drying paths. In the field, matric suction was obtained by conventional tensiometers, installed in the soil profile during the period of one year. Impregnated thin-layer plates were prepared with undisturbed samples, to obtain their structures along the profile. The SWCCs were bimodal, typical of tropical soils with macro and micro-aggregated structures. The SWCCs obtained by wetting and drying evidenced the hysteresis phenomenon. In the field, several wetting and drying paths were obtained.

RÉSUMÉ: Cette recherche présente les courbes caractéristiques sol-pical de la région de Campinas, Brésil. Ce profil se compose ferralitique. De ce profil, les échantillons de sol ont été rassemblés et soumis à une caractérisation géotechnique et à des essais minéralogiques. Des spécimens ont été faits avec ces échantillons de sol et utilisés pour déterminer la CCSE par la méthode du papier filtre avec chemins par des tensiomètres conventionnels. Des lames minces impregnées ont été preparées avec des échantillons non-remaniés pour obtenir leurs structures le long du profil. Les CCSEs ont été bimodales, typiques des sols tropicaux avec des structures macro et micro-agrégées. Les Sur le terrain, plusieurs chemins de

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