INFLUENCE OF GRASSROOTS ON THE STABILITY OF SLOPES: EXPERIMENTAL MODELLING AND NUMERICAL ANALYSIS

Abstract

Debris flow disasters were caused by surface erosion with high rainfall, especially in mountain villages on the island of Bali. This research aims to understand the stability behavior of volcanic soil due to physical and mechanical conditions based on numerical analysis with Plaxis 3D software. The experiment was used by planting in a test box in the form of a steel frame and equipped with a rainfall simulator to determine slope stability due to planting a combination of elephant grass and vetiver. Numerical results for volcanic soil conditions without vegetation show a soil tension of 0.6854 kN/m2. Model results after four days, there was a decrease of 0.0001m, and after 33 days there was a decrease of 0.0000064 m for the slope 45°. The safety factor of slopes without vegetation is 0.8, so this condition has the threat of landslides and surface erosion. Experimental results show that adding elephant grass combined with vetiver grass can reduce erosion by 94.6% on slope 45o and 92.67% on slope 60o. The effectiveness of the resulting runoff reaches 55.48% on slope 45o and 53.89% on slope 60o. This increase in effectiveness was caused by the development of elephant grassroots, which spread horizontally, thereby increasing the bond with the top layer of soil.