S-Space College of Engineering/Engineering Practice School (공과대학/대학원) Dept. of Energy Systems Engineering (에너지시스템공학부) Journal Papers (저널논문_에너지시스템공학부)
Thermally induced mechanical and permeability changes around a nuclear waste repository—a far-field study based on equivalent properties determined by a discrete approach
- Min, Ki-Bok; Rutqvist, J.; Tsang, Chin-Fu; Jing, Lanru
- Issue Date
- Int J Rock Mech Min Sci 2005;42:765-80
- A numerical investigation is conducted on the impacts of the thermal loading history on the evolution of mechanical response and
permeability field of a fractured rock mass containing a hypothetical nuclear waste repository. The geological data are extracted
from the site investigation results at Sellafield, England.
A combined methodology of discrete and continuum approaches is presented. The results of a series of simulations based on the
DFN–DEM (discrete fracture network–distinct element method) approach provide the mechanical and hydraulic properties of
fractured rock masses, and their stress-dependencies. These properties are calculated on a representative scale that depends on
fracture network characteristics and constitutive models of intact rock and fractures. In the present study, data indicate that the
large scale domain can be divided into four regions with different property sets corresponding to the depth. The results derived by
the DFN–DEM approach are then passed on to a large-scale analysis of the far-field problem for the equivalent continuum
The large-scale far-field analysis is conducted using a FEM code, ROCMAS for coupled thermo-mechanical process. The results
show that the thermal stresses of fractured rock masses vary significantly with mechanical properties determined at the
representative scale. Vertical heaving and horizontal tensile displacement are observed above the repository. Observed stress and
displacement fields also shows significant dependency on how the mechanical properties are characterized. The permeability changes
induced by the thermal loading show that it generally decreases close to the repository. However, change of permeability is small,
i.e., a factor of two, and thermally induced dilation of fracture was not observed. Note that the repository excavation effects were
not considered in the study.
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