Elephant Grass Root Reinforcement for Mitigating Earthquake-Induced Debris Flow in Saturated Volcanic Soil

I Nengah Sinarta; Kadek Windy Candrayana; I Made Kusuma Wiranata

doi:10.48084/etasr.16713

Authors

I Nengah Sinarta Department of Civil Engineering, Faculty of Engineering and Planning, University of Warmadewa, Indonesia | Master Program of Infrastructure and Environmental Engineering, University of Warmadewa, Indonesia https://orcid.org/0000-0002-7095-1501
Kadek Windy Candrayana Department of Civil Engineering, Faculty of Engineering and Planning, University of Warmadewa, Denpasar, Indonesia
I Made Kusuma Wiranata Department of Civil Engineering, Faculty of Engineering and Planning, University of Warmadewa, Denpasar, Indonesia

Volume: 16 | Issue: 2 | Pages: 34084-34089 | April 2026 | https://doi.org/10.48084/etasr.16713

Received: 5 December 2025 | Revised: 3 January 2026, 22 January 2026, and 9 February 2026 | Accepted: 25 February 2026 | Online: 2 March 2026

Corresponding author: I Nengah Sinarta

Abstract

Indonesia's volcanic slopes are instable due to their high porosity, rapid saturation, and frequent seismic activity. Vegetation-based bioengineering offers a sustainable alternative to conventional structural solutions, but with rainfall and earthquake loading, effectiveness is reduced. This study examines how elephant grass roots (Pennisetum purpureum cv. Odot), influence the behavior and stability of saturated volcanic soil under dynamic conditions. Consolidated-Undrained (CU) triaxial tests, direct shear tests, pore-water pressure measurements, and shaking-table simulations of local earthquake acceleration, were examined throughout the experiments. Slope stability was evaluated using a pseudo-static approach to estimate changes in shear strength, pore-water pressure, Factor of Safety (FOS), and debris-flow length. The laboratory tests indicate that elephant grass roots increase soil cohesion by over 300% and reduce pore water pressure from 100 kPa to 60 kPa. Consequently, the FOS increased from 0.95–1.00 in non-vegetated slopes to 1.10–1.23 in vegetated conditions, and the debris flow length decreased by up to 18% demonstrating the significant biomechanical potential of elephant grass for stabilizing volcanic slopes under dynamic loading.

Keywords:

elephant grass, bioengineering, debris flow, earthquake

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