The effects of broadleaf carpet grasses (axonopus compressus) on shallow slope stability

Abstract

Shallow landslide is the slope failure phenomena that is a frequently occur geotechnical problem in tropical rainforest region such as Malaysia. For grass where the fine root distribution with depth is consistent and easily defined, the fine root network play the role important as geosynthetic mesh by providing apparent enhanced cohesion that increase the strength of the soil. This study is to evaluate the effects of broadleaf carpet grass on shallow slope stability in terms of factor of safety (FOS). A slope geometry is drawn up and fed into the Microsoft Excel based SLIP4EX program for stability calculation. The additional parameters from grass effect is included in the analysis. This study can be concluded that broadleaf carpet grasses provided additional effective cohesion c?v of 1.43kPa to soil strength, and root reinforcement 0.297kN/m2 on slip surface. For case study, thee effects of carpet grass added 29.56% to FOS at 0.3 m depth slip plane. For parametric study of slope angles, the steepest slope of 1V:1H shows the carpet grasses added 29.53%. to FOS. Results of FOS also show that shallow slope stability is sensitive to effective cohesion c?, while internal angle of friction ?? has little effect on it. Bare soils results show that shallow slope failure prone to occur when the slope has effective cohesion c? less than 2.40 kPa in slope angle of 1V:1H. For the same slope after the inclusion of grass, shallow slope failure prone to occur only when the slope has effective cohesion c? less than 0.56 kPa.