Professor Kalle Kirsimäe, University of Tartu
Senior Research Fellow Tiit Hang, University of Tartu
Professor Leena Katariina Korkiala-Tanttu, Aalto University, Finland
In thesis geotechnical properties of varved clays of western Estonia and oil shale retorting waste are discussed. Both soil types are very porous and consist about one part of solids and two parts of voids in volume and have maintained loose post-sedimentation state under considerable overburden due to geochemically determined bonding. Both soil types tend to lose that bonding as soon as equilibrium conditions change.
Bonding determines not only the ability of the solids to preserve their skeleton under the pressure of overburden, but also the strength. Degradation of these bonds means decrease of overall strength of frictional matter and may ultimately lead to a failure - landslide or yield of dams or waste depositories. Therefore, the knowledge of nature and timeframe of the processes inducing degradation of the bonds are of major importance in order to assess the long-term stability of the natural and man-made structures.
General goal of this thesis is to summarize and analyze geotechnical properties and long term behaviour of soft lateglacial varved clays and landfilled waste from oil shale retorting processes with respect to their environmental and compositional changes.