Integrated Geophysical Methods for Geotechnical Subsurface Investigations

This research was funded through the New Hampshire Department of Transportation’s (NHDOT's) State Planning and Research (SPR) program and summarizes the NHDOT’s efforts to supplement conventional test borings and exploration techniques through the use of geophysics on several geotechnical projects. The Department’s geotechnical investigations often encounter bedrock or unstable soils at variable depths over short lateral distances. Test borings are point specific and may miss sudden depth changes and variations in the soil and rock properties. Additional borings can be expensive and time consuming and may even result in a more puzzling subsurface interpretation. Site conditions and/or highly conductive soil properties can sometimes limit the use of the NHDOT’s ground penetrating radar equipment, but through the implementation of additional geophysical techniques the Department has enhanced its capabilities. These geophysical investigative techniques have helped alleviate some of the uncertainties that arise when making subsurface interpretations based solely on conventional exploration methods. This report presents both successful and less successful case histories utilizing resistivity imaging and seismic refraction in conjunction with test borings and ground penetrating radar to characterize a geotechnical project’s subsurface conditions. The methods employed in using these geophysical techniques, the results of the geophysical investigations, and how these results were calibrated and verified are presented.


  • English

Media Info

  • Media Type: Web
  • Edition: Final Report
  • Features: Figures; Photos; Tables;
  • Pagination: 28p

Subject/Index Terms

Filing Info

  • Accession Number: 01140588
  • Record Type: Publication
  • Report/Paper Numbers: FHWA-NH-RD-13733E
  • Contract Numbers: 13733E, A000(050)
  • Created Date: Sep 24 2009 3:09PM