ANALYSES OF LONGITUDINAL SPLITTING OF UNIAXIALLY COMPRESSED ROCK CYLINDERS

Failure of uniaxially compressed rock cylinders by sudden splitting parallel to the direction of loading has been a puzzle for many years. This paper describes several mechanisms that might cause, or at least contribute to such splitting. If a specimen has a slightly bent or barrel-like shape due to imperfect machining, then there will be radial tensions in parts of the compressed specimen that might lead to splitting. Buckling away from an internal fracture or flaw, or interaction of a growing crack with the free surfaces might also produce tensions responsible for splitting. However, prior weakening of the specimen by microcrack growth is probably necessary before any of these processes can result in splitting of a sample. Qualitatively, it seems likely that some specimens split in shear on planes making a small angle to the direction of applied compression because of anisotropy caused by small cracks parallel to the applied stress. © 1979.