Palestrante Confirmado – SPD
Prof. Eduardo Alonso
Palestra: Triggering and motion of landslides
Eduardo Alonso has been Professor of Geotechnical Engineering at the Civil Engineering School of UPC since 1986. He is a past Dean of the School and a past Vice-Rector for research at UPC.
His main research interests have focused on stochastic analysis of soil heterogeneity, unsaturated soil mechanics, rockfill mechanics, coupled thermos-hydro-mechanical analysis and some chemo-mechanical interactions.
He has maintained over the years a special interest in landslide phenomena, a fascinating subject which receives attention in engineering geology, rock mechanics and soil mechanics. Recently he has contributed to the development of new computational techniques, the Material Point Method in particular, capable of addressing the static and dynamic aspects of landslide instability.
He has lectured in many countries and he has also acted as a consultant in a variety of geotechnical engineering projects in several countries. He is member of the Royal Academy of Engineering of Spain and he is the immediate past editor of ICE journal Géotechnique. Past honorary talks include Coulomb, Buchanan, Sowers, Croce, Heim, Kezdi, Rocha, BGA Touring, Rankine and Leonards lectures.
Resumo da Palestra
The velocity and motion of landslides, once equilibrium is lost, is a necessary information to estimate the expected damage. The lecture will describe concepts and modelling techniques addressing this problem. Physical phenomena and deformation mechanisms leading to fast sliding velocity will be first explored. The explanation provided by thermal pressurization of pore water in the sliding surface will be described and applied to simple but common sliding geometries. Criteria to decide in practice if a rapid motion is likely to occur will be given.
At the other extreme of landslide mobility, slow creeping motions are often found in natural and man-made environments. A relevant question is their evolution in time and the risk for a sudden acceleration. This question will be addressed for some sliding mechanisms.
Generalization to arbitrary geometries will be done by means of a calculation procedure, the Material Point Method, which was formulated for a three-phase granular medium. This computational tool, in the domain of continuum mechanics, provides also the opportunity of examining the transition from static impending failure to the subsequent dynamic motion. The material point formulation was adapted to incorporate thermal water pressurization in shearing surfaces generated by strain localization. The implication of this phenomenon, which enhances landslide mobility, will be discussed.
The lecture closes with a critical examination of the advances described and the prospects for improvements in predicting landslide mobility.