MERON ASSEFA ZEGEYE, HENOK FIKRE GEBREGZIABHER
Vegetation has a good influence on stability of slopes due to its root cohesion that provides additional strength to the soil layer and its hydrological effect involving evapo-transpiration which leads to increase in soil suction and reduction in pore water pressure, consequently increasing the effective soil strength. Vetiveria zizanioides or vetiver grass, one of the famous slope stabilizing plants, has extensively been used in many tropical and subtropical countries. Quantitative studies of how much contribution the grass really provides towards slope stabilization are relatively scarce having focus on engineering methods which are relatively costly and with no ecological benefit. With the aim of investigating the mechanical behavior of grass stabilized slope, the properties of vetiver grass have been determined from laboratory experiments and incorporated in the nonlinear Finite Element model using PLAXIS 2D software. The parametric studies on different ground types, slope geometric conditions and spatial distribution of vetiver grass confirmed that the effect of the grass is higher on soils of lower cohesion and steeper inclination. It has also been found out that better improvements can be achieved when the grass extends beyond the toe, in excess of the slope face.