The planned isolation of nuclear waste in mined rock repositories poses unusual requirements for rock mass characterization. This paper describes recently developed block test methods for characterizing and quantifying the thermal, mechanical and hydraulic properties of rock masses. The heated block test, recently conducted in situ on an 8m3 block of jointed gneiss, provides normal stress and temperature-dependent data such as deformation modulus, joint stiffness, joint permeability, thermal expansion, thermal conductivity and dynamic elastic modulus. Simpler tests conducted on singly jointed blocks or on jointed drill core provide joint roughness data. This is incorporated in recently developed constitutive models which describe the coupling of normal displacement, shear displacement, shear strength, dilation and permeability.
Die geplante Isolierung von radioaktivem Abfall in abgebauten Gesteinsabflallen stellt ungewöhnliche Anforderungen an Felsgesteinkennzeichnung. Dieser Bericht beschreibt kuerzlich entwickelte Blocktestmethoden zur Kennzeichnung und quantitativen Bestimmung der Warmeeigenschaften und der mechanischen und hydraulischen Eigenschaften der Felsmasse. Der HeiBblocktest, der kuerzlich "in-situ" auf einem 8m3 groBen Block von geklueftetem Gneis durchgefiuehrt wurde, gibt normale Spannungs- und Temperaturabhangigkeitswerte wie Verzerrungsmodul, Verbindungssteifigkeit, Verbindungsdurchlassigkeit, Warmeausdehnung, Warmeleitfahigkeit und Dynamik elastizitatsmodul. Einfachere Messungen, die an einzeln gekliuefteten Blcoks oder an gekluefteten Bohrkernen vorgenommen wurden, geben Kluftrauhigkeitswerte an. Diese sind miteingeschlossen in kiuerzlich entwickelte zusammenfassende Modelle, die die Kupplung normaler Verlagerung, Scherverlagerung, Scherfestigkeit, Dehnung und Durchaissigkeit beschreiben.
L''isolation projetee des dechets nucleaires dans des depôts de roche extraites presente des exigences peu commune pour la caracterisat ion de la masse de roche. Cette etude decrit les methodes, recemment developpees, des essais des blocs pour caracteriser et pour quantifier les proprietes thermiques, mechaniques et hydrauliques des masses de roche. L''essai du bloc chaud, recemment conduit in situ sur un bloc de gneiss jointe (de 8m3) fournit l''indication normale qui depend de la force et de la temperatureˆ par exemple, le coefficient de la deformation, la durete de la jointure, la permeabilite de la jointure, l''expansion thermique, la conductivite thermique et le coefficient dynamique et elastique. Des essais plus simples qu''on a conduits sur des blocs individuellement jointes ou sur le centre jointe d''un trepan ·fournissent les indications de la rugosite des jointures. Tout ça est incorpore dans des modeles de base, recemment developpes, qui decrivent le couplage du deplacement normal, du deplacement du cisaillement, de la force du cisaillement, de la dilation et de la permeabilite.
Characterization of rock masses is usually associated with construction and excavation projects such as dams, tunnels, mines, etc. In general the parameters of most importance are associated with deformation moduli, shear strength and permeability, each a function of stress and orientation. Civil engineering experience suggests that the natural joint sets have most effect on the magnitude of these parameters. Jointing is also responsible for their directional anisotropy.
The planned isolation of nuclear waste in mined rock repositories poses additional problems in rock mass characterization. The extended time scale and the thermal load associated with long-term isolation add to the number of significant parameters that need to be quantified. Numerical modeling of potential groundwater and radionuclide transport through changing stress and temperature regimes demands an advanced level of input data. Particular emphasis falls on accurate joint characterization, in particular on the manner in which the hydraulic, thermal and mechanical properties should be coupled.
The schematic block diagram shown in Figure 1 represents the 8 m3 in situ test recently completed by Terra Tek for the Office of Nuclear Waste Isolation. The objective was to demonstrate a suitable method for obtaining appropriate hydrothermomechanical data for modeling
