An Analytical Solution for the Run-Out of Submarine Debris Flows

Abstract

Submarine debris flows have a significant impact on offshore and coastal facilities. The unique characteristics of submarine debris flows involve large mass movements and long travel distances over very gentle slopes. To improve our insight and knowledge of the basic mechanism behind submarine debris flows, an analytical model was derived for the mobility of submarine debris flows. This model takes into account the mass change of debris flows induced by deposition, stagnation pressure, and the topography of the depositional area. One case study on the Palos Verdes debris flow proves its ability to predict the run-out distance of a submarine debris flow to a reasonable level of accuracy. On the gentle slopes, the submarine debris flow progressively loses mass due to deposition, which in turn influences the flow velocity. In addition, the results show that the slope angle and spreading angle of the debris depositional zone play important roles in the sliding process.

Keywords:

• Analytical solution
• run-out distance
• stagnation pressure
• submarine debris flow

List of Notation

Acknowledgements

This research work is part of the activities of the Schofield Centre at University of Cambridge. The work presented in the paper is part of the Modelling of Mudslide Runout Project which was a collaborative project between University of Cambridge and BP. We thank Dr. Stuart Haigh (University of Cambridge) and Professor Kenichi Soga (UC Berkeley) for comments that greatly improved the research results, and Mr. Takaaki Kobayashi for the assistance with the whole project. We also show our gratitude to Dr. Paul Dimmock (BP) for fully supporting this project and sharing his pearls of wisdom with us during the collaboration.