Abstract
A subcritical crack growth due to stress corrosion has been identified as a source of time-dependent fracture of rocks in brittle fields. The stress corrosion cracking was investigated in humid air by using the double-torsion technique for three rocks of different origin, Murata basalt, Oshima granite and Ogino tuff. The subcritical crack growth was found to be strongly dependent on the directions of crack opening and crack propagation. The maximum growth rate was higher by several orders of magnitude than the minimum one for the same rock. The anisotropy in the crack propagation was controlled by microcracks for Oshima granite and by the fabric for other rocks.
