Failure Mechanism of Unbonded Prestressed Thru-Anchor Cables: In Situ Investigation in Large Underground Caverns

Excerpt

Prestressed rock anchor cables are commonly utilized in geotechnical and mining engineering (Peliua et al. 2000; Tezuka and Seoka 2003; Koca et al. 2011) because their installation increases the effective strength and stability of the reinforced rock (Maejima et al. 2003; Li et al. 2012). Nevertheless, in some cases, prestressed cables have failed in large underground caverns or tunnels because of excessive deformation of the anchored rock mass or inadequate assumptions used when designing the cables (Li 2004; Lu et al. 2011; Gong et al. 2011). During the failure process of anchor cable, the stress redistribution and progressive deterioration of the reinforced mass rock can adversely affect the overall stability of the free surface, manifested as large deformation or indeed collapse of rock mass (Galvez et al. 2006; Zhu et al. 2010). Therefore, a deeper understanding of the mode and mechanism of prestressed anchor cable failure will better inform the design process of anchor cables to mitigate future failures. …