Rock mechanical characterization of an argillaceous host rock of a potential radioactive waste repository

Citation
J. Renner et al., Rock mechanical characterization of an argillaceous host rock of a potential radioactive waste repository, ROCK MECH R, 33(3), 2000, pp. 153-178
Citations number
38
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Geological Petroleum & Minig Engineering
Journal title
ROCK MECHANICS AND ROCK ENGINEERING
ISSN journal
0723-2632 → ACNP
Volume
33
Issue
3
Year of publication
2000
Pages
153 - 178
Database
ISI
SICI code
0723-2632(200007/09)33:3<153:RMCOAA>2.0.ZU;2-S
Abstract
The physical properties of foliated marls and shales from the Swiss Central Alps were investigated in the laboratory as part of the site characterizat ion of a potential low and intermediate level radioactive waste repository. The rocks were first characterized by density, porosity and water content, then P-wave velocity measurements and uniaxial compression tests were cond ucted on samples oriented parallel, perpendicular and similar to 45 degrees inclined to the foliation. Correlations between P-wave velocities, Young's moduli, and uniaxial strengths and directional dependence of compressibili ty and permeability (determined at elevated hydrostatic pressures) revealed that two distinct families of microcracks cause the significant anisotropy . The pressure and time dependence of strength was then measured in triaxia l compression, creep, and relaxation tests. In triaxial compression at room temperature, confining pressures up to 90 MPa and strain-rates as low as 1 0(-8) s(-1) failure occured after small inelastic strains. Failure strength exhibits a strong pressure and a weak strain-rate dependence. The low fric tion coefficient of clay minerals appears to dominate the bulk frictional p roperties. Micromechanical modeling of triaxial compression, creep, and rel axation tests suggests that inelastic deformation is accommodated by subcri tical crack growth.