Avaliação da influência de raízes de Zoysia japonica na resistência ao cisalhamento de um solo arenoso

Abstract

The technique of strengthening the soil with natural fiber (roots) has been known for centuries and the use of vegetative material for its stabilization is part of this discipline composed by a set of techniques, known as natural engineering. The vegetation contributes to the stability of the soil, mainly by the increase of shear resistance via reinforcement offered by the roots, forming a reinforcement system known as soil-root. Even with the growing employment of Natural engineering in infrastructure works, the information on the technical properties of the plants used in these interventions is still scarce. In this sense, the present work aims to study the influence of the roots in the shear resistance of a sandy soil of alluvial origin, located in the Veneto Valley district in São João do Polêsine, Rio Grande do Sul. In order to achieve the proposed objectives, direct shear tests were carried out with undeformed samples and reconstituted samples in laboratory without roots and with the addition of three different root rates: 64, 127 and 191 roots, from the grassy Emerald (Zoysia japonica Steud). The humidity conditions of the samples used in the tests were natural and saturated for the normal tensions of 9, 15, 25, 50, 80, 100 and 200 kpa and for the dry air condition for vertical tensions of 25, 50, 80, 100 and 200 kpa. In addition, tests were carried out to obtain the soil water retention curve, tests of physical and chemical characterization of the material under study. From the analysis of the results obtained in the course of the research it was evidenced that the roots provide an increase in the parameters of resistance of the soil in study and that these are proportionate to the increase of existing roots in the sample, as well as of the Humidity condition of the assay. Been evidenced greater values of the resistance parameters for the air-dried samples and the flooded samples are shown in the smallest values.