June 22 - 25, 2025
Delta Hotel and Conference Centre
Ottawa, Ontario, Canada
Biography
Richard Wan is a Professor with the Department of Civil Engineering at the University of Calgary. He holds a diplôme d’ingénieur from the Ecole Nationale des Travaux Publics de L’Etat (ENTPE), an MSc in geotechnical engineering from the University of Ottawa, and a PhD. in geomechanics from the University of Alberta. He is the recipient of the first Robert J. Melosh medal in Finite Element Analysis.
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He has many years of experience in geomechanics with special emphasis on continuum mechanics, micromechanics, experimental mechanics, soil and rock mechanics, constitutive laws for engineering materials and computational modelling of complex geotechnical structures via a multiscale and multiphysics approach. He sits on the Editorial Board of several leading International Journals in geomechanics and is a member of the TC103 (Numerical Methods) of the ISSMGE. His research expertise covers the fields of Geomechanics, Micromechanics and Computational Mechanics with applications such as energy resource extraction, cold regions engineering, stability of unsaturated dykes, and Superpave highway design. Lately, he has had a keen interest in extending geomechanics theories in thermodynamics views via concepts of entropy in dissipative systems with ramifications to complex systems. This has led to a recent NSERC transdisciplinary project such as the modelling of a pandemic using a mechanistic, multiscale approach.
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He has supervised and graduated over 50 PhD students with three of them being professors in major Canadian Universities. He works within an international research network and is the author of over 150 publications and has published 3 books.
Abstract
At the dawn of the Anthropocene, emerging unsaturated soil problems associated to infrastructure, energy and the environment demand solutions that lie beyond basic tenets of geotechnical engineering. The talk covers recent developments in granular mechanics, multiscale approaches, and numerical simulations to uncover the characteristic behaviours of unsaturated soils at the grain and pore scales. Traditionally, one can distinguish disparate water saturation (capillary) regimes in a soil as fluid penetrates or emerges from it. One swings from an extreme setting where pendular water cohesively holds together pairs of particles in the form of a liquid bridge, to another extreme where water exclusively invades the void space so that particles could be fully immersed as in a slurry. Such transitions between all these capillary regimes are modelled in a unified way using a new numerical framework that computes complex formation, coalescence, and rupture of water menisci following solid skeleton deformation. This coupled approach successfully captures water or air invasion dynamics as well as capillary-induced stresses during wetting or drying processes. Finally, the model is upscaled to the geostructure to illustrate both material and hydraulic instabilities in the form of a shallow flow failure in an unsaturated slope subjected to wetting and drying.