Compressibilidade de uma argila orgânica mole do bairro de Chão de Estelas no Recife

Abstract

The origin of Recife´s plain is riverine and marine. Deposits of organic soft clay are spread in more than 50% of its area, which creates a favorable scenery for a occurrence of differential repression in several constructions foundations localized over these deposits. The present work treats of a geotechnical investigation of the a soft organic clay of the Chão de Estrelas s neighborhood. In this location many not deformed samples of this material were taken in the Beberibe riverside margin s that resulted in parameters of compressibility used as reference in the accomplishment of a road project for the neighborhood. This research, however, used the same soft organic clay sample´s of the Chão de Estrelas s neighborhood to accomplish a complementation of that first study. Besides, a vast collection of literature references on the compressibility of organic soft clay gave support to this study. The general objective this thesis is the analysis of the compressibility of a organic soft clay through of the vertical or radial drainage oedometer test; and, specifically, to study the influence of the preview drying these materials in the obtaining of the natural humidity these samples; to analyze the quality of this organic soft samples clays and to propose the correction of the field compressibility graph line´s; to make a comparison between the fists studies result´s or compressibility parameter s already classified and the news complements result´s by this work, and, in general, with results found in the plain of Recife city; to find accurate value to the pre-compression stress; and, to analyze the results of the compressibility parameters of the a unstructured sample with the results of the a structured sample in the same condition e depth. To achieve those goals, the research used five samples taken from two islands, this term refers to a region studied, called Island 1 e Island 2, respectively, referring of the borehole 203A e 208A. Of the Island 1 were taken in the three depths; while on the second Island were taken in the two depths; being executed two drainage rehearsals by each depth, five vertical drainage rehearsals and five radial drainage rehearsals. It were still accomplished for another vertical drainage rehearsals with a unstructured organic soft clay sample, totalizing 11 rehearsals. In all those rehearsals were used small adjustment or increments of the stress, always using less stress that the before stress, (Δσ/ , only in the area that precedes the virgin compression, way to define the best pre-compression stress value. The results of the compressibility parameters found in this work are in accordance with the literature values. The forms of the compressibility curves and the compression parameters values by the vertical and radial drainage rehearsals are shown similar. The plasticity index suffer influence of the previous drying of the material. The value of the pre-compression stress came closer in comparison with the results of the first study that based the road project for the Chão de Estrelas s neighborhood. This work demonstrated by the reconstruction of the curve of compressibility of the field that good quality organic soft clay samples´s suffer some percentual of the unstructured situation.