Abstract
Uniaxial compressive strength (UCS) is one of the basic and important descriptors for rock mechanics and rock mass strength determination. Field estimated strength (FES) and field testing are commonly used in conjunction with laboratory-tested UCS values for geotechnical design. Commonly used field testing techniques include point load testing and Leeb/Equotip testing. In support of field testing techniques, a number of existing publications deal with the correlation between rock strength and sonic velocity, measured as part of downhole geophysics surveys or from laboratory testing.
To add to this knowledge base, this paper demonstrates the application of sonic velocity measurements using a handheld ultrasonic pulse velocity (UPV) tester. UPV is an acoustic non-destructive test method most often used to evaluate the relative quality of rock or concrete structures, and to identify the presence of internal flaws such as cracks or voids.
For this paper, the UPV tester has been used to measure the sonic velocity on drill core to assist with rock strength estimation. Four case studies are given showing the correlation between the measured sonic velocity, field-estimated strength and laboratory strength testing at the four sites. Because this is a relatively new application, the limitations found are presented, as well as suggested workflows and future applications.
Authors
- Diane Walker, SRK Consulting, Australia
- Callen Banff, AngloGold Ashanti, Australia
- Julian Venter, AngloGold Ashanti, Australia
