Determining the viscosity and yield surface of marine sediments using modified Bingham models

摘要

The rheology of marine sediment-laden flows in a submarine environment is examined. The viscosity and yield stress of marine sediments are key parameters controlling landslide mobility: the former is related to the peak velocity and the latter is related to the final deposition of debris flow. One of the simplest rheological models is the ideal plastic Bingham model, which is often applied to diverse materials. For marine sediments, the flow behavior can be approximated by modified Bingham models, such as the bi-viscosity and Papanastasiou models. The flow of viscoplastic materials can then be described by unyielded (local shear stress τ is lower than a yield stress τ _y), yield surface (τ = τ _y), and post-yield (τ > τ _y) characteristics. It is concluded that modified Bingham models with a proper choice of flow parameters can be used to predict the unyielded, yielding and yielded zones for marine sediments. It is also demonstrated that in some cases the yield surface can be effectively obtained using the relationship between viscosity and shear rate.