Moderate to Very Deep (> 150 m to > 600 m) Vs Profiling in Engineering Studies Using Large, Frequency-Controlled, Active Sources and Rayleigh-Type Surface Waves

Abstract

Significant advances have occurred over the past 25 years in shear-wave velocity (VS) profiling of geological materials using active-source, surface-wave measurements. In the early part of this period, improvements in digital equipment for recording and real-time, spectral-analysis processing in the field greatly increased the usefulness of the measurements. The VS profiling began with the Spectral-Analysis-of-Surface-Waves (SASW) method and generally involved profiling depths of 0.1 to 60 m. In the past 15 years, larger active sources, called vibrosises in the exploration industry, have been constructed. Two larger sources, named Liquidator and T-Rex, are discussed. They are operated in a stepped-frequency, downward-sweeping mode. The operating mode and field procedures are discussed. VS-profiling ranging over depths from moderate to very deep (> 150 m to > 600 m) are presented. © 2018 SEG