Determination of shear wave velocity in bender element testing using objective criteria in time domain

Bender element (BE) testing is widely used in geology and geotechnical engineering to measure shear wave velocity, essential for characterising geomaterial stiffness. However, accurate determination of the shear wave arrival time (T_s) in BE tests remains challenging due to near-field effects, boundary reflections, and wave attenuation. Existing time-domain approaches for T_s estimation, including First-to-First, Peak-to-Peak, Wave Inflection, and Cross-Correlation, often rely on subjective interpretations. Leveraging a comprehensive experimental program of over 400 BE tests conducted on six different dry sands at various input excitation frequencies (4–30 kHz), this study introduces objective methods for T_s determination using direct time-domain and cross correlation approaches. The proposed methods are benchmarked against the results from resonant column (RC) tests to assess their reliability and accuracy. The results reveal that the accuracy of the estimation methods depends on the frequency range of the transmitted wave due to the inherently dispersive nature of waves in BE testing. It is shown that the first peak in the received signal exceeding 30 % of the maximum amplitude (PK30) is the most consistent and reliable indicator of T_s across the studied frequency range.