A viscoplastic approach to the behaviour of fluidized geomaterials: application to the case of Aberfan flowslide.

PAOLA DUTTO; DIEGO MANZANAL; MIGUEL STICKLE; ÁNGEL YAGUE; MANUEL PASTOR

Aussois

Workshop; ALET Geomaterials workshop; 2014

ALERT Geomaterial network

Landslides can cause major economic damage and large number of casualties as it is possible to see from past events occurred all over the world. Being able to model these kind of hazards would then suppose the achievement of great benefits. Here a model that combines a depth integrated description of the soil-pore fluid mixture togetherwith a set of 1D models dealing with pore pressure evolution within the soil mass is presented. In this way, pore pressure changes caused by vertical consolidation, changes of total stresses resulting from height variations and changes of basal surface permeability can be taken into account with more precision. Concerning the material behaviour, the approach used is the one suggested by the Perzyna viscoplasticity, which has been extensivelyused in the past to model solid behaviour prior to failure. Three different yield criterion are considered in the framework of Perzyna´s model: a Von Mises, a Mohr Coulomb and a Cam Clay yield criterion. The obtained results lead to a good agreement with the results achieved using classical rheological models. Then, from Mohr Coulomb viscoplasticity, a simple shear rheological model is derived, providing the basal friction needed in depth integratedmodels. As an example that shows the performance of the proposed model, the case of the Aberfan flowslide, occurred in 1966, is presented.