Hydro-Mechanical Effect of Vetiver Root on Laterite Soil

Soil bioengineering is a technique that uses vegetation in engineering design. Stabilizing slopes using grass roots can be considered as a soft type disaster mitigation measure for building a sustainable and resilient society from the perspective of its socio-economic benefits. The applicability of plant roots in slope stability can be understood by studying its hydrological and mechanical attributes. Hence the aim of this study is to identify the contribution of these two factors in stabilizing slopes by considering root–soil interaction. Plant roots act as a structural element to provide mechanical reinforcement, and when transpiration becomes significant, it induces soil suction which enhances the soil shear strength and reduces the hydraulic conductivity. Out of several grass species, vetiver grass (Crysopogon zizanioides) has various predominant qualities in its availability, faster growth and root biomass which ensure its use in geotechnical and geo-environmental engineering. Hence, the effect of vetiver grass roots on soil water retention curves (SWRC), permeability (k) functions and shear strength parameters have been experimentally investigated on lateritic soil. Thus, this paper focuses on quantifying the root contribution in improving the shear strength parameters: cohesion and friction angle along with permeability functions and further to develop SWRC to measure soil suction for different root biomass. Results of this study can be used as a tool for engineers in establishing a sustainable mitigation measure for a region where the impacts due to landslides are severe and vulnerabilities are the greatest.