A mechanical erosion model for two-phase mass flows: Tackling a long standing dilemma of mass mobility.

München

2017

BandaufführungSonderdruck

12216S

202734

Landslides and debris flows can dramatically increase their volume and destructive potential, and become exceptionally mobile by entraining bed sediment and fluid. Additionally changes in flow bed by erosion-deposition mechanisms, and thus changes in the driving force components, play a critical role in debris flow dynamics. Usually erosion related geophysical mass flows are more mobile than without erosion. However, this fact has never been explained mechanically explicitly and unambiguously. In literature, it is mentioned that erosion results in shorter travel distance due to the energy lost in erosion, but it has also been argued that, e.g., due to the added mass, the debris travels longer distance. The dilemma of erosion and flow mobility however is, that no clear explanation and derivation exists to mechanically explicitly describe the state of mobility. To cope with these challenges a two-phase variably saturated erodible basal morphology is introduced and allows for the evolution of erosiondepositiondepths, incorporating the inherent physical process including momentum and rheological changes of the flowing mixture.