To predict the morphology of debris flow deposits, a control volume finite-element model (CVFEM) is proposed, balancing material fluxes over irregular control volumes. Locally, the magnitude of these fluxes is taken proportional to the difference between the surface slope and a critical slope, dependent on the thickness of the flow layer. For the critical slope, a Mohr-Coulomb (cohesive-frictional) constitutive relation is assumed, combining a yield stress with a friction angle. To verify the proposed framework, the CVFEM numerical algorithm is first applied to idealized geometries, for which analytical solutions are available. The Mohr-Coulomb constitutive relation is then checked against debris flow deposit profiles measured in the field. Finally, CVFEM simulations are compared with laboratory experiments for various complex geometries, including canyon-plain and canyon-valley transitions. The results demonstrate the capability of the proposed model and clarify the influence of friction angle and yield stress on deposit morphology. Features shared by the field, laboratory, and simulation results include the formation of steep snouts along lobe margins.
Bibliographical noteFunding Information:
This research has been supported by the Ministry of Science and Technology, Taiwan (grant nos. MOST110-2636-M-005-001 and MOST108-2911-I-002-564).
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