2013 Practical Considerations for the Triaxial Testing of Mine Wastes

Triaxial testing of mine wastes is commonly undertaken to provide shear strength estimates for stability assessments of mine waste storage facilities. When planning triaxial tests however, the omission of carefully planned testing instructions may produce shear strength parameters which are inaccurate, or not suited to the assessments being undertaken. This paper details various issues that should be considered when planning triaxial testing of mine wastes. Test results have demonstrated that; test type and initial confining stress are important to define failure envelopes over appropriate stress ranges (which may be particularly important for mine wastes exhibiting curved failure envelopes); laboratory saturation of unsaturated mine wastes may return conservative shear strengths; oversize particles may compromise the reliability of calculated shear strengths, and multistage tests may provide reasonably reliable drained shear strengths, but may overestimate undrained shear strengths.