Abstract
The choice of a pure cohesive or a pure frictional viscoplastic model to represent the rheological behaviour of a flowslide is of paramount importance in order to obtain accurate results for real cases. The principal goal of the present work is to clarify the influence of the type of viscous model—pure cohesive versus pure frictional—with the numerical reproduction of two different real flowslides that occurred in 1966: the Aberfan flowslide and the Gypsum tailings impoundment flowslide. In the present work, a depth-integrated model based on the Biot–Zienkiewicz formulation, enhanced with a diffusion-like equation to account for the pore pressure evolution within the soil mass, is applied to both 1966 cases. For the Aberfan flowslide, a frictional viscous model based on Perzyna viscoplasticity is considered, while a pure cohesive viscous model (Bingham model) is considered for the case of the Gypsum flowslide. The numerical approach followed is the SPH method, which has been enriched by adding a 1D finite difference grid to each SPH node in order to improve the description of the pore water evolution in the propagating mixture. The results obtained by the performed simulations are in agreement with the documentation obtained through the UK National Archive (Aberfan flowslide) and the International Commission of large Dams (Gypsum flowslide).
Highlights
Flowslides are rapid flows, either saturated or unsaturated, where the material has a high compaction tendency, a low density and is characterised by a metastable structure
A depth-integrated model based on the v − pw Biot–Zienkiewicz formulation, enhanced with a diffusion-like equation to account for the pore pressure evolution within the soil mass, is applied to the Aberfan flowslide and Gypsum tailings impoundment flowslide that both occurred in 1966
In the case of the Gypsum flowslide, a pure cohesive viscous model—the Bingham model—is considered, while for the Aberfan flowslide, a frictional viscous model based on Perzyna viscoplasticity is developed
Summary
Flowslides are rapid flows, either saturated or unsaturated, where the material has a high compaction tendency, a low density and is characterised by a metastable structure. Depth-integrated models have been found to provide a suitable approximation for many 3D problems These types of models result in an excellent compromise between accuracy and computational cost and have been applied to landslides since the work of Savage and Hutter [1]. A depth-integrated model based on the v − pw Biot–Zienkiewicz formulation, enhanced with a diffusion-like equation to account for the pore pressure evolution within the soil mass, is applied to the Aberfan flowslide and Gypsum tailings impoundment flowslide that both occurred in 1966. It has been described by Jeyapalan et al [42], and Pastor et al [12], who modelled the problem using a depth-integrated finite element model assuming that the material behaved as a Bingham fluid. This parametric study has the objective of showing the non-negligible differences that arise when it comes to choosing thehas objective of showing the non‐negligible differences that arise when it comes to choosing the the right right parameters the description of the phenomena.
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