Simulation of debris flow on an instrumented test slope using an updated Lagrangian continuum particle method
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RESEARCH PAPER
Simulation of debris flow on an instrumented test slope using an updated Lagrangian continuum particle method Alomir H. Fa´vero Neto1 • Amin Askarinejad2 • Sarah M. Springman3 • Ronaldo I. Borja1 Received: 26 September 2019 / Accepted: 16 March 2020 Ó Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract We present an updated Lagrangian continuum particle method based on smoothed particle hydrodynamics (SPH) for simulating debris flow on an instrumented test slope. The site is a deforested area near the village of Ruedlingen, a community in the canton of Schaffhausen in Switzerland. Artificial rainfall experiments were conducted on the slope that led to failure of the sediment in the form of a debris flow. We develop a 3D mechanistic model for this test slope and conduct numerical simulations of the flow kinematics using an SPH formulation that captures large deformation, material nonlinearity, and the complex post-failure movement of the sediment. Two main simulations explore the impact of changes in the mechanical properties of the sediment on the ensuing kinematics of the flow. The first simulation models the sediment as a granular homogeneous material, while the second simulation models the sediment as a heterogeneous material with spatially varying cohesion. The variable cohesion is meant to represent the effects of root reinforcement from vegetation. By comparing the numerical solutions with the observed failure surfaces and final free-surface geometries of the debris deposit, as well as with the observed flow velocity, flow duration, and hot spots of strain concentration, we provide insights into the accuracy and robustness of the SPH framework for modeling debris flows. Keywords Debris flow Debris slide Granular flow Meshless method Slope Smoothed particle hydrodynamics Updated Lagrangian
1 Introduction The past decades have seen significant development in computational methods for problems in fracture mechanics, damage modeling, strain localization, and unsaturated soil mechanics. For this type of problems, the finite element method remains the preferred computational platform [35, 43, 52, 53, 62, 73, 75], even as a number of continuum particle methods have also emerged as viable alternatives in recent years [35, 58–60, 62]. However, when it comes to modeling debris flow, where the motion is so chaotic that & Ronaldo I. Borja [email protected] 1
Department of Civil and Environmental Engineering, Stanford University, Stanford, CA 94305, USA
2
Department of Geoscience and Engineering, Delft University of Technology, Delft, The Netherlands
3
Department of Civil, Environmental and Geomatic Engineering, ETH Zu¨rich, Zu¨rich, Switzerland
element connectivity is difficult to impose, the finite element method may not be an appropriate platform to use, since it suffers from severe mesh distortion that impacts on its accuracy and overall performance. For this type of problem, continuum particle methods may have some dist
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