Abstract

Submarine run-out is one of the most catastrophic natural hazards which can cause severe damage to offshore infrastructure. The motion of submarine run-out is best described by a non-Newtonian fluid model once a block of sediment collapses to form a fully mobilised flow. The Bingham fluid model is the simplest and most-widely used model for this approach. The parameters involved in the model are back-calculated using the evidence of previous run-out events, and are used for the risk assessment of future events. However, the parameters obtained by back calculation could vary by orders of magnitude from event to event, indicating that the simple fluid model is incapable of describing the entire process of submarine run-out. In this study, we propose a new method for simulating submarine run-out based on the Material Point Method (MPM) and critical state soil mechanics. It is important that our simulations do not rely on back-calculations and can be performed using soil parameters derived from conventional soil tests. The goal of this study is to develop a model that can simulate the entire process of submarine run-out from initiation to deposition. We also investigated the undrained shear strength of sea sediments to see the capability of critical state concepts at a high range of water content.