University of Manitoba Scholarship (login required)
Permanent URI for this collection
Browse
Browsing University of Manitoba Scholarship (login required) by Author "Alfaro, M"
Now showing 1 - 3 of 3
Results Per Page
Sort Options
- ItemRestrictedCompression and strength of dense sand at high pressures and elevated temperatures(2004-12-31T11:59:13Z) Graham, J; Alfaro, M; Ferris, GThe paper examines the stress-strain behaviour of densely compacted sand tested at pressures up to 80 MPa in one-dimensional compression and 7.2 MPa confining pressure in triaxial tests. Tests were performed at temperatures up to 100degreesC. The testing relates to a proposal by Atomic Energy of Canada Limited to fill containers of waste nuclear fuel with a crushed quartz sand to provide additional stiffness. No significant effects of temperature were encountered in either isotropic compression or triaxial shear.
- ItemRestrictedInstability of dykes at Seven Sisters Generating Station(2004-10-12T11:43:35Z) Garinger, B; Alfaro, M; Graham, J; Dubois, D; Man, AWater-retention dykes at Seven Sisters Generating Station in Manitoba have experienced irregular instabilities since they were heightened in the late 1940s. An investigation was undertaken to compare three locations at the site, one section of dyke that had experienced previous instability, a second section that had remained stable, and a third, background location that had not experienced dyke loading. The investigation included laboratory tests, field tests, and computer modelling. The laboratory tests indicated anisotropic stiffness and brittle strain-softening behaviour in the highly plastic clay beneath the dykes. Results from the stable and unstable sections showed greater brittleness and anisotropy at the unstable section. Pore fluid chemistry tests for cation and anion concentrations showed considerable reductions in concentrations of calcium and sulphate beneath the dykes compared with those of the background section. This suggested leaching of gypsum in the foundation soil. Computer modelling was done using seepage, stress-deformation, and slope stability software. Results indicated that the stable and unstable sections both had safety factors greater than unity if "post-peak" strengths were used. Both were close to unity if residual strengths were used. The results suggest that time- and location-dependent depletion of gypsum cementation bonds caused by seepage beneath the dykes has increased the brittleness and anisotropy and reduced stability with time.
- ItemRestrictedModified Cam-Clay modelling of temperature effects in clays(2001-06-30T11:24:55Z) Graham, J; Tanaka, N; Crilly, T; Alfaro, MThe Cam-Clay model for isothermal mechanical behaviour of clays has been extended to take account of the effects of temperature on stress-strain behaviour. The assumptions used in constructing the new model are based on published results and on new data presented in the paper. The model allows prediction of how heating and cooling affect volume changes, pore-water pressures, and strengths for both normally consolidated and overconsolidated saturated clays. It permits modelling of observed reductions in the overconsolidation ratio with increasing temperature. The model provides accessible qualitative explanations for temperature effects that were previously difficult to understand. It will also allow easy implementation for quantitative modelling in triaxial stress fields. Results predicted by the model are compared with data collected by the authors at temperatures up to 100 degreesC. The model does not account for changes that occur in clay minerals at higher temperatures, for example, in bentonites at temperatures higher than about 150 degreesC.