M. Quecedo

Modelling of Landslides: (II) Propagation

This paper presents a numerical model wich can be used to simulate phenomena such as flowslides, avalanches, mudflows and debris flows. The proposed approach is eulerian, and balance of mass and momentum equations are integrated on depht. Depending on the material involved, the model can implement rheological models such as Bingham or frictional fluids. A simple dissipation law allows the approximation of pore pressure dissipation in the sliding mass. Finally some applications are presented.

Modelling of debris flows and flow slides

ABSTRACT This paper presents a numerical model which can be used to simulate phenomena such as flowslides, avalanches, mudflows and debris flows. The proposed approach is la- grangian, and balance of mass and momentum equations are integrated on depth. Depending on the material involved, the model can implement rheological models such as Bingham orfrictional fluids. A simple dissipation law allows the approximation of pore pressure dissipation in the sliding mass. Finally, some applications are presented.

An eulerian model for soil dynamics: application to fast slope movements

ABSTRACT This paper presents a theoretical framework to model soil behaviour under dynamic conditions. The equations describing the coupling between the solid skeleton and the pore fluids are presented following an eulerian approach based on the mixture theory that can provide an unified formulation for both initiation and propagation phases of fast landslides, such as avalanches of rocks and granular materials, flowslides and debris flows.

An eulerian model for soil dynamics: application to fast slope movements: (III) Rheological models

ABSTRACT This paper presents some useful rheological models that can be used to characterize the soil behaviour in fast landslides. The approach followed is based on a general formulation of the stress tensor in terms of I, D and D 2 where D is the rate of deformation tensor. Then we particularize it to simple shear flow conditions and compare it to some simple rheological laws. From here, expressions valid for general flow conditions are proposed.

An eulerian model for soil dynamics: application to fast slope movements: (II) A simple velocity-pore pressure formulation

ABSTRACT This paper presents an eulerian approach that can be used to model the propagation phase of catastrophic landslides. In the case of material composed by a solid skeleton and pore fluids, two physical phenomena must be considered: i) the propagation and, ii) the consolidation and dissipation of pore pressures. The PDEs are integrated in depth and solved with the Finite Element Method using the Taylor-Galerkin algorithm. Its possible to take into account the curvature effect of the bed of the slide using a curvilinear reference system or adding the contribution of the centrifuge force to the bottom friction force. A simple frictional fluid flow example shows the influence of the curvature effect. Role of pore pressure dissipation is analyzed modelling the Aberfan flowslide (1966).

Numerical Modeling of Initiation and Propagation Phases of Landslides

This paper deals with initiation and propagation of landslides, for which suitable numerical models are presented. Concerning the initiation phase, we present a coupled displacement-pore pressure formulation (u-pw) proposed by Zienkiewicz and co-workers. Particular attention is paid to capture of the failure surface where strain localizes. An example is presented where the triggering mechanism is the pore pressure changes induced by rainfall. Once failure has been triggered, propagation is analyzed using an Eulerian formulation of the balance of mass and momentum equations. Two simplified, one-phase models are presented for the two extreme cases of dry granular flows and mudflows. The first model uses a level set algorithm to track the free surface, and is suitable for length scales of 100 m. For longer distances of propagation, we propose a depth integrated model which is discretized using a Taylor-Galerkin technique.