ABSTRACT
As part of a project investigating ground-borne vibration using a geotechnical centrifuge, which involves very small strain shear waves, the need for an accurate measurement of small strain shear modulus (G max ) arose. G max can be back-calculated from measured shear wave velocities (v s ). Previous researchers have measure v s in-flight by using an air-hammer device and sensitive accelerometers to detect the speed of the generated shear wave. However, issues relating to inaccurate position measurement of the accelerometers, background noise, and the recording of very small signals at sufficiently high frequency can cause errors in the measurement of v s . This paper compares centrifuge air-hammer based measurements of v s against those obtained from a bender element system integrated into a triaxial apparatus. The paper details the testing methodologies adopted and provides results which indicate that the two methods agree well with each other and with predicted values from literature. The paper highlights how the precise processing methodology adopted can affect the accuracy of the obtained values of v s .
