Compression and shear wave sonic velocity measurements in hard rock

Compression wave sonic velocity (Vp) is routinely measured in rock testing laboratories. Shear wave sonic velocity (Vs) measurement for further application to geomechanical studies is not routinely conducted. This paper outlines the establishment of a laboratory testing technique including waveform analysis for the determination of shear wave velocity. The paper outlines the measurement of compressional and shear wave sonic velocities using ultrasonic pulse transmission technique, for several hard rock lithologies recovered during routine (NQ/HQ/PQ) exploration core drilling. Shear wave sonic velocities were measured using a pair of shear piezoelectric transducer elements. Measured shear wave sonic velocities are compared with fundamental and empirical formulas used to predict shear wave sonic velocity, in order to verify the method. This paper discusses the need for an Australian Standard that includes a provision for the measurement of shear wave sonic velocity. Measured results are used to calculate dynamic moduli of rock samples and are compared with static moduli. The application of dynamic moduli to geotechnical characterisation of the rock mass is explored.