Large-Scale Direct-Simple Shear (LDSS) Testing on Copper Mine Tailings

This Master's thesis presents an experimental testing program conducted to assess the properties of coarse tailings from two Arizona copper mine heap leach pads. This testing program was motivated by recent failures in tailings impoundments, which has prompted a re-evaluation of tailings deposit stability worldwide. The testing was conducted using a unique large-scale Direct-Simple Shear (LDSS) device at Arizona State University (ASU). Prior to testing the tailings, the LDSS device had to be rehabilitated, as it had not been used for several years. The testing program included one-dimensional compression testing, shear wave velocity measurement, and monotonic shearing under constant volume conditions. The test results demonstrate the effectiveness of the LDSS device in obtaining representative data for tailings under monotonic loading. Recommendations for future improvements of the LDSS include enhancing the connection of monitoring instruments, utilizing more sophisticated software for shear wave velocity measurements, and optimizing the control system. The thesis contributes to geotechnical engineering by improving understanding and evaluation of tailings properties, thereby enhancing safety and environmental sustainability in the mining industry.