Rock property determination

Abstract

Mining projects vary greatly in their location and rock properties. Despite this, the testing processes used to determine how they will behave geotechnically have become remarkably similar and more of a rote process. Test methods should be carefully tailored to suit all the possible behaviours of the rock mass. In underground mining, the properties of the underground structure are inherited rather than specified, and need to be determined. Usually, parts of the underground structure are required to collapse to yield ore, while others need to resist all manner of deformation and remain safely open. This paper reviews useful testing techniques with a particular focus on measuring what is appropriate for the situation. The paper starts by presenting some new ways of looking at uniaxial testing and the use of some simple tests to measure tensile and shear strength. It reviews the measurement of anisotropy, linear and non-linear elasticity, poroelasticity, plasticity and the multiple forms of failure. These include shear failure and tensile failure. Some of the questions surrounding anisotropy are reconsidered. Finally, the paper looks at how these measurements may be used.