Investigation of cable bolts for stress corrosion cracking failure

Abstract

Premature failure of cable bolts due to stress corrosion cracking (SCC) in mining and civil industries is a worldwide problem with limited cost-effective solutions. A load frame capable of applying tensile loads was designed and constructed to simulate and examine SCC of full-size cable bolts (up to 2.4 m in length) under simulated in-situ conditions. The tension loading apparatus was used to conduct periodically increasing strain rate (PISR) tests on cable bolts in simulated underground environments. The PISR test was appropriate and reliable for examining SCC susceptibility of TG and Superstrand cable bolts including the effects of wire arrangement, galvanisation and indentation. Overall, TG cable bolts were more susceptible to SCC than Superstrand cable bolts. In each type of cable bolt, the one with plain wires was approximately 30% more resilient to SCC in terms of time to failure than the one with indented wires. Galvanising was not able to prevent SCC, however it considerably delayed SCC occurrence. The results of this study provided detailed insight into SCC of different types of cable bolts and can be further used for setting up optimal support regimes in different geological and environmental conditions.