A depth-integrated sph model for flow-like landslides on a fixed Cartesian coordinate system.

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Xilin Xia, Qiuhua Liang

Thursday 2 july 2015

15:20 - 15:35h at Oceania (level 0)

Themes: (T) Water engineering, (ST) Computational methods

Parallel session: 12E. Engineering - Computational

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Flow-like landslide is one of the most disastrous natural hazards that may lead to heavy losses of lives and properties around the world. Prediction of run-out distance and velocity using modern computer models may help mitigate the catastrophic impacts of such events by means of defining impact area and estimating the intensity of such events. Being a fully Lagrangian meshless numerical method that can trace the flow extent accurately without suffering grid distorting and twisting as the traditional mesh-based methods do, the Smoothed Particle Hydrodynamics (SPH) may provide a promising tool for simulating flow-like landslides. Currently, most of the SPH models have been reported to solve the Navier-Stokes equations, which are computationally prohibitive for large-scale simulations. In this work, a new SPH model is developed to solve the depth-averaged governing equations for flow-like landslides instead of full mathematical model to achieve adequate solution accuracy at a manageable computational cost. To facilitate practical simulations, e.g. enabling easy integration with GIS data, the mathematical model is specifically derived on a fixed Cartesian coordinate system in which the vertical dimension is parallel to the direction of gravity with including the vertical acceleration which cannot be neglected in flow on steep slopes. Two other major forces regulating the dynamic behavior of flow-like landslides are the internal pressure and friction between flow mass and ‘channel’ bed. Because soil or gravel may be considered as Mohr-Coulomb materials, i.e. the shear stress is only dependent on normal stress, the internal pressure and friction can be described by the model derived by Savage and Hutter [1]. The numerical techniques developed in Xia et al. [2] including well-balanced formulation and shock-capturing scheme are adopted and implemented in the new model for robust simulations. Finally, the model is validated by applying it to reproduce several laboratory tests and satisfactory results are obtained. References [1] Savage SB, Hutter K. The motion of a finite mass of granular material down a rough incline. J Fluid Mech 1989;199:177–215. [2] Xia X, Liang Q, Pastor MM, Zou W, Zhuang Y. Balancing the source terms in a SPH model for solving the shallow water equations. Adv Water Resour 2013;59:25–38.