Mining Publication: Technology News 476 - Instrumented King Wire for Monitoring Cable Bolts

• Cable bolts
• Mechanical strain
• Roof falls
• Strain gauges

A cable bolt can be a strain-measuring device as well as a supporting device in underground mines. Placing instruments on a cable bolt allows certain characteristics of a rock mass, such as high strain and load, to be evaluated during mining and provides a means for mining engineers and mine inspectors to forecast a potential roof fall. Thousands of cable bolts are installed in U.S. mines each year. Studies performed by NIOSH researches show that support loads can exceed the yield point of the steel, which can result in unstable ground conditions that pose direct safety hazards for underground workers. Rock falls can also create secondary hazards, such as carved escape ways and blocked ventilation passages. Development of methods and tools to assist in the evaluation and selection of rock supports could reduce the number of unplanned rock falls significantly.