Estudo do comportamento mecânico de um solo fino compactado e estabilizado quimicamente para utilização em barragens de pequeno porte

Abstract

The research reported in this final course assignment aims to analyze the effect on the mechanical behavior of a fine soil compacted and chemically stabilized with lime and rice husk silica, aiming its use in small dams. Lime is widely used in soil improvement, the difference now is the inclusion of some percentages of rice husk sílica, a product derived from rice husk ashes; these ashes which, until recently, were found in waste groups generated in great volumes annually; and often disposed improperly in the environment, without any technical criteria. The methodology of this work consisted in the study and development of an experimental program of tests that allowed the knowledge and improvement in the properties of a fine soil extracted from a small earthen dam located in Alegrete, RS, with the use of different percentages of lime and rice husk silica. The results of soil samples molded without adding any stabilizing agent were compared with samples with different contents of these materials and, thus, it is proven the performance of the different mixes that were studied. It were performed granulometry tests, Atterberg limits and MCT (Miniature, Compacted, Tropical) for the natural soil and compaction tests, direct shear and triaxial compression. The mixture with best performance against the direct shear test, in respect to the friction angle and cohesion, was the mixture with addition of 2% of silica. For the triaxial compression test, results could be obtained for two mixtures. However, there is still a need to achieve more results in the equipment for its calibration. The obtained results for the two mixtures studied diverged from direct shear test, but still was possible to obtain the failure envelope for the mixtures tested. The stabilization of non lateritic clay soil with silica was effective, allowing the use of these materials in small dams and minimize the problem of deposition of rice husk ash, the generator product of rice husk silica used in this research.