Effect Of Slope Angle On The Runout Evolution of Granular Column Collapse for Varying Initial Volumes

TL;DR

This study investigates how slope angle influences the runout distance of granular column collapses in submarine environments using advanced numerical modeling, revealing a volume-dependent threshold for increased runout under submerged conditions.

Contribution

It introduces a coupled LBM-DEM numerical approach to analyze the effect of slope angle and initial volume on submarine granular landslides, highlighting hydrodynamic interactions.

Findings

Submerged columns can have larger runouts than dry ones above a certain volume.

The threshold volume for increased runout decreases as slope angle increases.

Hydrodynamic effects like pore pressure and vortices significantly influence collapse behavior.

Abstract

In nature, submarine slope failures usually carry thousands of cubic-meters of sediments across extremely long distances and cause tsunamis and damages to offshore structures. This paper uses the granular column collapse experiment to investigate the effect of slope angle on the runout behavior of submarine granular landslides for different initial volumes. A two-dimensional coupled lattice Boltzman and discrete element method (LBM-DEM) approach is adopted for numerically modeling the granular column collapse. Columns with four different slope angles and six different volumes are modelled under both dry and submerged conditions. The effects of hydrodynamic interactions, including the generation of excess pore pressures, hydroplaning, and drag forces and formation of turbulent vortices, are used to explain the difference in the runout behavior of the submerged columns compared to the dry columns. The results show that at any given slope angle, there is a threshold volume above which the submerged columns have a larger final runout compared to their dry counterpart, and this threshold volume decreases with slope angle.