A two-phase sph depth integrated model for debris flow propagation considering pore water pressure evolution
- Autores: Saeid Moussavi Tayyebi
- Directores de la Tesis: Manuel Pastor Pérez (dir. tes.), Miguel Martín Stickle (codir. tes.)
- Lectura: En la Universidad Politécnica de Madrid ( España ) en 2019
- Idioma: español
- Tribunal Calificador de la Tesis: Diego Guillermo Manzanal (presid.), Pablo Mira Mc Williams (secret.), Mila Enriqueta Sanchez de Vilanova (voc.), José Úbeda Palenque (voc.), Elena González Gomez (voc.)
- Programa de doctorado: Programa de Doctorado en Ingeniería de Estructuras, Cimentaciones y Materiales por la Universidad Politécnica de Madrid
- Materias:
- Enlaces
- Tesis en acceso abierto en: Archivo Digital UPM
- Resumen
Landslides are a geological phenomenon which occur frequently in mountainous regions or along rivers, causing major economic damage and a large number of casualties around the world. Development of continuous based models to represent the propagation of these geophysical mass flows, from initiation to deposit in the run-out zones, is not an easy task due to the complexity of the phenomenon. Moreover, many of the interesting fast catastrophic landslides, such as debris flows, involve more than one phase where the coupling between the phases plays a fundamental role. Such multiphase materials can be properly described by using a multiple set of nodes for different phases, and a suitable drag law to take into account the interaction between particles.
The principal objective of this Doctoral Thesis is to develop mathematical and numerical modelling for simulating debris flows in which considering the effect of excess pore-water pressure is essential for risk analysis. A debris flow consists of low to high permeable soil in which lateral spreading could be highly affected by excess pore-water pressure. The numerical modeling of these types of debris flow has not been investigated until now.
In this study, the two-phase model proposed by Pastor et al. (2017) is extended and also an improvement in description of excess pore pressure evolution (Pastor et al., 2015) is presented in order to take into account with more precision changes caused not only by vertical consolidation and height variations, but also by new considerations which include changes of basal surface permeability and porosity variations.
The new mathematical approach is based on the depth integrated mathematical model of Zienkiewicz and Shiomi (1984), and is capable to reproduce the propagation of debris flows with soil permeability ranging from high to low.
These mathematical equations are discretized by using Smooth Particle Hydrodynamic (SPH) technique where a double set of nodes, one to represent the movement of the solid particles and another to represent the movement of the fluid particles, is defined. As a novelty, this Doctoral Thesis provides a contribution to enhance the two-phase numerical model with adding a 1D finite difference grid to each SPH node that represents a solid particle in order to improve the description of excess pore-water pressure (SPH-FD model).
The performance and limitations of the model is assessed using a series of benchmark exercises, including (i) dam break problem to show the main features of the model, (ii) flume tests equipped with a (permeable) rack which performed in Trondheim, and (iii) two real cases for which we have had access to their reliable information.
The good results obtained from the validation analysis of the mentioned benchmarks indicated that the proposed model is capable to properly reproduce the propagation velocity, runout distance and deposit thickness of the debris flows, and more importantly to correctly performs the time-space evolution of excess pore-water pressures during the whole propagation stage from initiation to propagation over an impermeable and permeable bottom boundary, and up to deposition.
