Fracture growth around openings in thick-walled cylinders of rock subjected to hydrostatic compression
Cylindrical specimens of rock into which holes of circular, elliptical, and rectangular cross section had been cut, were tested in hydrostatic compression, in order to study the growth of fractures around the holes. The rock types used were an isotropic, homogeneous sandstone and anisotropic, argillaceous quartzite and the relative sizes of specimens and holes were such as to eliminate boundary effects for at least one of the specimen geometries. Failure around the circular holes initiated by shearing at diametrically opposite points and spalling continued at these loci until the opening was sufficiently large for ultimate collapse of the specimen to occur. In the elliptical and rectangular specimens, spalling along similar shear planes occurred at the ends of the long axes of the holes. However, if the applied hydrostatic pressures were sufficiently large and were held for a sufficiently long time, a second set of conjugate shear fractures appeared, along which movement was such as to cause material to move into the opening. In addition, extension cracks parallel to the long axes of the holes tended to form in the region above the opening and these cracks often coalesced with shear cracks radiating out from the ends of the holes to form a series of domical cracks. (11 refs.)
- Research Organization:
- Witwatersrand Univ., South Africa
- OSTI ID:
- 5042928
- Journal Information:
- Int. J. Rock Mech. Min. Sci.; (United States), Vol. 10:3
- Country of Publication:
- United States
- Language:
- English
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