The impact of hydraulic gradients and boundary conditions on the microstructural stability of clayey backfills with special respect to the risk of piping and erosion
2012 (English)In: Journal of Earth Sciences and Geotechnical Engineering, ISSN 1792-9040, E-ISSN 1792-9660, Vol. 2, no 1, 89-112 p.Article in journal (Refereed) Published
Disposal of hazardous waste like high-level radioactive waste (HLW) is made by confining it in canisters surrounded by dense, ductile “buffer” clay for placement in deposition holes at a few hundred meters depth in crystalline rock. The concept favoured by authorities in Sweden, Finland and Canada implies that the holes are bored from blasted or bored tunnels to be tightly backfilled by stacking compacted blocks of clay in the center and filling the remaining space between the blocks and the rock with blown-in clay pellets. The problem with this is that water flowing in from the rock can cause piping and erosion of the pellet filling, which can turn it into mud and disturb the placement of canisters and buffer clay. The controlling parameter is the rate of inflow of water per inflow point, which is determined by the structure and hydraulic conductivity of the rock. The paper describes a simple model of the mechanisms in penetration of water into the pellet fill and provides a basis for estimating the required rate of backfilling for avoiding critical conditions. The study indicates that such conditions will be caused irrespective of the rate of water inflow per point if the backfilling rate is low.
Place, publisher, year, edition, pages
2012. Vol. 2, no 1, 89-112 p.
Backfilling, Clay, Hydraulic gradient, Microstructure, Piping, Radioactive waste, Civil engineering and architecture - Geoengineering and mining engineering
Samhällsbyggnadsteknik och arkitektur - Geoteknik och gruvteknik
Research subject Soil Mechanics
IdentifiersURN: urn:nbn:se:ltu:diva-16183Local ID: fc748cb5-cd81-4791-b77b-b4f459a3fcc9OAI: oai:DiVA.org:ltu-16183DiVA: diva2:989159
Validerad; 2012; 20120530 (svek)2016-09-292016-09-29Bibliographically approved