A Dilatant Two-Fluid Debris Flow Model for Hazard Analysis in Changing Mountain Environments
Gravitationally driven flows of mud and sediment debris are causing a growing threat to mountain populations. Rock/ice avalanches, glacier lake outburst floods (GLOFs) and debris flows are in- creasingly a result of a global temperature rise, which is leading directly to the thawing of mountain perm...
| Main Author: | |
|---|---|
| Other Authors: | , , , |
| Format: | Doctoral or Postdoctoral Thesis |
| Language: | English |
| Published: |
ETH Zurich
2023
|
| Subjects: | |
| Online Access: | https://hdl.handle.net/20.500.11850/623278 https://doi.org/10.3929/ethz-b-000623278 |
| Summary: | Gravitationally driven flows of mud and sediment debris are causing a growing threat to mountain populations. Rock/ice avalanches, glacier lake outburst floods (GLOFs) and debris flows are in- creasingly a result of a global temperature rise, which is leading directly to the thawing of mountain permafrost and melting of glaciers. When coupled with extreme precipitation events, the mobiliza- tion of loose sediments leads to dangerous water-saturated flows that can cause human fatalities and severe infrastructure damage. Understanding the dynamics of debris flows is essential to develop land planning and technical measures to protect mountain communities. Numerical modeling of debris flows provides hazard engineers with a predictive tool to help plan and construct mitigation measures, including developing real-time warning systems. With the recent increase in computer power, it is now possible to simulate debris flow motion from initiation to run-out. Numerical modeling therefore links initial conditions, including precipitation and sediment availability, to flow conditions in the torrent and run-out fan. Despite recent progress, the application of numerical models is limited by the lack of understanding of the general kinematical behavior of two-phase flows, including the frictional interaction of fluid-solid mixtures with the basal surface, as well as the shearing interaction between the solid and fluid phases. The rheological problem is compounded by the complex interaction of the debris with the basal surface leading to bed erosion. Modeling debris flow motion with entrainment involves accurately predicting the interplay between debris flow composition (time evolution of the solid-fluid components) coupled with the geological setting. The lack of understanding of these complex physical processes and geo-mechanical feedbacks is preventing a reliable, and predictive, application of debris flow models in engineering practice. In this thesis, we develop, test and calibrate a depth-averaged, two-fluid debris flow ... |
|---|