Thirty-Ninth Canadian Geotechnical Colloquium: Unsaturated soil mechanics--bridging the gap between research and practice

The majority of geoengineering applications occur in the unsaturated (vadose) zone, which is the near-surface region forming the connection between meteorological phenomena above and saturated ground below. The key characteristic of the unsaturated zone is that water is in tension or, put another way, pore-water pressure is negative. Moisture content, as well as most material properties, vary spatially and temporally in the unsaturated zone and coupled processes are common. In geoengineering applications in the vadose zone, unsaturated soils may be present during part or all of their design lives. The question is how or when to consider the unsaturated soils' principles in an analysis or design. Although most geoengineering applications have an unsaturated component, use of unsaturated soil mechanics in practice lingers behind the prolific number of publications due the uncertain benefit of accounting for unsaturated effects, complexity, and conservativeness among other reasons. The focus of this colloquium is to continue bridging the gap by illustrating unsaturated soils' principles using application-driven examples in the areas of capillarity as well as flow, strength, and deformation phenomena. As principles of unsaturated soils become more understood and demand increases for incorporating climate change effects in design, use of unsaturated soils' principles in practice will continue to increase. Key words: unsaturated soils, capillarity, seepage, strength, expansive soils. La majorite des applications de geoingenierie se produisent dans la zone insaturee (<< vadose >>), qui se situe dans la region proche de la surface, faisant ainsi le lien entre les phenomenes meteorologiques ci-dessus et le sol sature ci-dessous. La caracteristique cle de la zone insaturee est que l'eau est en tension ou, en d'autres termes, la pression de l'eau interstitielle est negative. La teneur en humidite, ainsi que la plupart des proprietes du materiau, varient dans l'espace et dans le temps dans la zone non saturee et les processus couples sont courants. Dans les applications de geoingenierie dans la zone vadose, les sols non satures peuvent etre presents pendant tout ou partie de ses durees de vie. La question est de savoir comment ou quand tenir compte des principes des sols non satures dans une analyse ou un plan. Bien que la plupart des applications de geoingenierie comportent une composante insaturee, l'utilisation de la mecanique des sols insatures persiste derriere le nombre important de publications en raison des avantages incertains de la prise en compte des effets insatures, de la complexite et de la prudence parmi d'autres raisons. L'objectif de ce colloque est de continuer a combler le fosse en illustrant les principes des sols non satures en utilisant des exemples axes sur l'application dans les domaines de la capillarite ainsi que des phenomenes d'ecoulement, de resistance et de deformation. Au fur et a mesure que les principes des sols insatures deviennent mieux compris et que la demande augmente pour incorporer les effets du changement climatique dans la conception, l'utilisation des principes des sols non satures dans la pratique continuera d'augmenter. [Traduit par la Redaction] Mots-cles: sols insatures, capillarite, suintement, force, sols expansifs.
Introduction The majority of geoengineering applications occur in the unsaturated, or vadose zone, which can be up to hundreds of metres in depth depending on the ground profile and climate. [...]