Selection of shear strength profile for desiccated tailings to support an upstream raise Williams, D.J.; Paterson, S.; Yau, R.; Goddard, D.
The shear strength profile of existing tailings is crucial for supporting an upstream embankment raise for a conventional surface slurried tailings storage both safely and with acceptable settlements. The existing tailings will need to be desiccated in order to provide adequate bearing capacity for the raise, and will require geotechnical investigation to demonstrate this. Typical geotechnical investigation methods include in situ vane shear testing and cone penetration testing (CPT), usually including pore pressure measurement and possibly including seismic measurements. The vane shear and CPT may use the same rig. Heavily desiccated tailings may allow direct access using a conventional rig. Otherwise, a rig with wide tracks may be required, or access roadways may have to be constructed over the tailings. The data from these tests are then interpreted to determine the shear strength profile for the desiccated tailings, to enable geotechnical slope stability and settlement analyses of the proposed upstream embankment raise. The paper describes a case study of the geotechnical investigation, test data interpretation and geotechnical design considerations for a proposed upstream embankment raise on heavily desiccated tailings. The focus is on test data interpretation, which is an area that is often deficient.
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