Paired Crosshole S-Wave Measurements to Access Soil Stess History

The crosshole survey, e.g. seismic crosshole testing is a common geophysical method to determine soil dynamic properties of soils with high resolution between boreholes. Engineers use these key parameters to predict the response of soils to dynamic loading. An alternative investigation approach to conventional drilling is the use of mobile pushing devices, i.e. Direct-Push procedures. By placing geophysical tools into the pushing rods geophysical methods become more flexible and adaptive drilling and investigation techniques can be implemented more expeditiously. A complete crosshole dataset of paired S-wave data (SV- and SH-waves) was acquired between previously installed PVC cased boreholes and the Direct-Push borehole. The in-situ profiles of paired shear wave velocity profiles (SH and SV) can be used to evaluate the stress history of soils. This paper describes the combination of a Direct-Push system and paired S-wave crosshole measurements as a cost-effective alternative to standard investigation techniques and as a tool to support geotechnical engineers to predict dynamic soil parameters. The methodology was successfully tested at the site for Technical Safety (TTS) in Horstwalde (Germany).