Deterministic Modeling of Pasir Panjang Debris Flow Using Smoothed Particle Hydrodynamics (SPH)

Abstract

The debris flow can be modeled as non-Newtonian flow using physical and mathematical modeling methods based on rheological property measurements and movement parameters. The numerical simulation in this research used smoothed particle hydrodynamics (SPH) to solve the momentum and energy equations. The debris flow modeled in this research is located in the Bentarsari Basin, which is surrounded by hills composed of volcanic breccia from the Kumbang Formation (Tpk) and tends to be more susceptible to landslides and may become debris flows. The results of the numerical simulation begin with the collapse of the natural dam and become debris flow with 8.8 m maximum thickness. The debris flow destroyed the bridge in the 40s with 100 kPa pressure. A speed of 6 m/s was reached at 120 s. A small hill in the deposition area was hit by debris flow at 130 s causing 18 casualties. The debris flow enters the deposition area at the 150 s. The debris flow average velocity shows relatively transverse pattern (1-126 s), constant pattern (126-289 s), and random pattern (after 289 s). The debris flow average pressure shows steep negative gradient pattern (1-47 s) and relatively flat pattern (after 47 s). The average debris flow thickness shows a steep negative gradient pattern (1-13 s) and a gentle negative gradient pattern (after 13 s). The results of debris flow modeling using SPH can simulate the debris flow segregation process, which usually cannot be captured by conventional debris flow modeling software.