Acessibilidade / Reportar erro

Shear strength of soils and slopes covered with vetiver

Vegetated slopes are more resistant to mass movement and erosion by water. The vegetation contributes to the soil stability, especially by increasing the shear strength provided by roots. Plant species that have been most effective in stabilizing unstable slopes are the grasses, belonging to the family Gramineae. One specimen of this family, vetiver (Chrysopogon zizanioides (L.) Roberty), has proved very effective in slope stabilization. With the objective of evaluating the improvement of soil shear strength parameters at different times after vetiver planting, direct shear tests were carried out on soil without vegetation and soil with vetiver grass one, two, three and four years after planting. Direct shear tests were also carried out on the same slope soil without vegetation and covered with vetiver grass. The results of direct shear tests with soil slope samples were evaluated by three limit equilibrium methods to determine an average safety factor for the slopes. From the direct shear tests, the parameters cohesion and angle of internal friction were determined, which showed that vetiver grass increased apparent soil cohesion, which became significant three years after planting vetiver. The vetiver grass induced an improvement in resistance parameters with a consequent increase in the safety factor of slopes and increase in soil shear strength, contributing to slope stabilization of shallow ruptures.

vegetation; shear strength parameters; slope stabilization


Sociedade Brasileira de Ciência do Solo Secretaria Executiva , Caixa Postal 231, 36570-000 Viçosa MG Brasil, Tel.: (55 31) 3899 2471 - Viçosa - MG - Brazil
E-mail: sbcs@ufv.br