Theoretical and experimental analysis of debris flow: rheology and two – phase modelling

To predict debris flow dynamics a numerical model, based on 1D De Saint Venant (SV) equations, was developed. The McCormack-Jameson shock capturing scheme was employed for the solution of the equations, written in a conservative law form. This technique was applied to determine both the propagation and the profile of a two-phase debris flow resulting from the instantaneous and complete collapse of a storage dam. To validate the model, comparisons have been made between its predictions and laboratory measurements concerning flows of water and homogeneous granular mixtures in a uniform geometry flume reproducing dam-break waves. Agreement between computational and experimental results is considered very satisfactory for mature (non-stratified) debris flows, which embrace most real cases. To better predict immature (stratified) flows, the model should be improved in order to feature, in a more realistic way, the distribution of the particles of different size within the mixture. On the whole, the proposed model can easily be extended to channels with arbitrary cross sections for debris flow routing, as well as for solving different problems of unsteady flow in open channels by incorporating the appropriate initial and boundary conditions.