Two-phase SPH modelling of a real debris avalanche and analysis of its impact on bottom drainage screens

Saeid M Tayyebi,Pedro Navas,Ángel Yagüe,Manuel Pastor,Miguel Molinos,Diego Manzanal,Miguel M Stickle

doi:10.1007/s10346-021-01772-9

Abstract

Rapid flow-like landslides, particularly debris flows and debris avalanches, cause significant economic damage and many victims worldwide every year. They are usually extremely fast with the capability of travelling long distances in short times, sweeping away everything in their path. The principal objective of this paper is to test the ability of the ‘GeoFlow-SPH’ two-phase model developed by the authors, to reproduce the complex behaviour of natural debris avalanches where pore-water pressure evolution plays a key role. To reach this goal, the model is applied to reproduce the complex dynamic behaviour observed in Johnsons Landing debris avalanche including the observed bifurcation caused by the flowing out of part of the moving mass from the mid-channel. Initial thickness deposit trim-line, distribution of deposit volume, and the average velocities were provided for this real case, making it an appropriate case to validate the developed model. The paper also contributes to evaluate the SPH-FD model’s potentialities to simulate the structural countermeasure, like bottom drainage screens, used to reduce the impact of debris flows. The analysis of the results shows the adequacy of the proposed model to solve this complicated geophysical problem.

Highlights

Landslides are a major natural hazard and can be defined as a continuous movement of materials triggered from the unstable hill slope due to natural processes or anthropic actions
This paper presented two computational simulations using a depthintegrated two-phase smoothed particle hydrodynamics (SPH) model capable of considering pore-water pressure evolution in debris flows
The consolidation equation is discretized using the finite difference method for the particular flows crossing over terrain with high permeability

Summary

Introduction

Landslides are a major natural hazard and can be defined as a continuous movement of materials triggered from the unstable hill slope due to natural processes or anthropic actions. The most catastrophic landslides, debris flows, are usually extremely rapid with the capability of traveling long distances in very short times sweeping away everything in their path, even in areas that had been considered safe, causing a large number of casualties and economic damage throughout the world every year. In recent years, these catastrophic events have attracted significant attention due to the growing population in areas with a high risk of natural disasters and climate changes, which increase the frequency and intensity of these catastrophic landslides. Unlike debris flows, they do not confine in an established channel Nicol et al (2013)

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Conclusion