Abstract. Mass movements such as debris flows and landslides differ in behaviour due to
their material properties and internal forces. Models employ generalized
multi-phase flow equations to adaptively describe these complex flow types.
Such models commonly assume unstructured and fragmented flow, where internal
cohesive strength is insignificant. In this work, existing work on two-phase
mass movement equations are extended to include a full stress–strain
relationship that allows for runout of (semi-)structured fluid–solid
masses. The work provides both the three-dimensional equations and
depth-averaged simplifications. The equations are implemented in a hybrid
material point method (MPM), which allows for efficient simulation of
stress–strain relationships on discrete smooth particles. Using this
framework, the developed model is compared to several flume experiments of
clay blocks impacting fixed obstacles. Here, both final deposit patterns and
fractures compare well to simulations. Additionally, numerical tests are
performed to showcase the range of dynamical behaviour produced by the model.
Important processes such as fracturing, fragmentation and fluid release are
captured by the model. While this provides an important step towards
complete mass movement models, several new opportunities arise, such as
application to fragmenting mass movements and block slides.
Global stability conditions for three-dimensional Lotka-Volterra systems
