Hideo Sekiguchi

Dynamics of Submarine Liquefied Sediment Flows: Theory, Experiments and Analysis of Field Behavior

This paper describes an extension of the computational code LIQSEDFLOW. The salient features of the code lie in the capabilities to describe the multi-phased physics of subaqueous sediment gravity flows. Specifically, it combines Navier-Stokes/continuity equations and equations for advection and hindered settling of grains for a liquefied soil domain, with a consolidation equation for the underlying, progressively solidifying soil domain, via a transition layer that is characterized by zero effective stress and a small yet discernable stiffness. Evolutions of the flow and solidification surfaces are traced as part of solution by using a volume-of-fluid (VOF) technique. The predicted features of gravity flows of initially fluidized sediments with different concentrations conform to the observed performances in two-dimensional flume tests. The submarine flow slide that occurred in 1980 on the Klamath River delta, California is also discussed. The present results demonstrate the crucial role of two-phase physics, particularly solidification, in reproducing the concurrent processes of flow stratification, deceleration, and redeposition, as well as in the formation of scarps and terrace in submarine liquefied sediment flows.