Developments in a non‐destructive method of determining rock strength

Material strength is an important variable for any study of the relationships between rock mass geomechanical characteristics and landform development. Standard field and laboratory tests for measuring strength present a variety of problems to the geomorphologist. Recent studies (Allison, 1988) have described a laboratory based non‐destructive method for indirectly determining material strength, by measuring Dynamic Young's Modulus. Data presented here suggest that the same apparatus can be used as a field technique. Tests have been conducted on the Devonian limestone of the Napier Range, Western Australia. Laboratory results obtained using the non‐destructive ultrasonic apparatus have a high correlation with triaxial Hoek Cell tests. Results from on‐site tests have much greater accuracy than data collected using the Schmidt hammer, which is currently the most widely used geomorphological field technique for determining rock strength.