Strength of Rock-Like Specimens with Pre-existing Cracks of Different Length and Width

Excerpt

Discontinuities play a key role in the failure process of rock and rock mass. Small fractures can decrease the strength of rock while large-scaled joints can have a significant effect on the overall stability of rock mass (Eberhardt et al. 2004). Discontinuities are often separated by intact rocks, which are known as “rock bridges”. These rock bridges contribute to the stability of jointed rock mass by providing a strength reserve (Gehle and Kutter 2003) that needs to be broken first before failure can take place. In recent years, a number of experimental studies have been performed to investigate the mechanism of crack propagation in rock-like material under uniaxial (Shen et al. 1995; Wong and Chau 1998; Sagong and Bobet 2002; Xu et al. 2013; Yin et al. 2014; Cao et al. 2015), biaxial (Bobet and Einstein 1998), and shear (Gehle and Kutter 2003) stress conditions. It was revealed that under load conditions, wing cracks first appear at the tips of pre-existing cracks (flaw) while shear cracks typically lead to coalescence and failure. The aforementioned studies also indicated that the process of coalescence was rather complex and depended on the rock material and geometry of pre-existing cracks. …