Failure of granite under constant loading

Abstract

The study of failure of a rock under constant loading is essential to the design and construction of excavations in the rock for mines, tunnels, and nuclear waste repositories. A series of uniaxial constant loading tests has been performed to study the deformation characteristics, damage accumulation and strength degradation of granite with time. The results show that the axial deformation remains almost constant before failure, while the lateral strain increases. The strain path plots show that the octahedral shear strain increases linearly with the mean strain indicating that tensile and shear-slip cracks develop simultaneously. By varying the stress level, it is shown that a shorter time is required to fail the rock if the stress level is higher. In this study, damage is quantified by the inelastic volumetric strain, the degradation of dynamic elastic properties, and the cumulative acoustic emission (AE) count. The results demonstrate that the cumulative AE count is a better indicator of damages. © 2004 Elsevier Ltd.