A Discussion on the Use of Geophysical Methods When Assessing Ground Conditions for Remediation Design of Road Embankment Failures

A common problem faced following a road embankment failure is undertaking site investigation, for remediation design, safely. Failure sites are often unstable and traditional methods of investigation (e.g., boreholes) pose a significant safety hazard to those undertaking the investigation and could induce further instabilities at the site. In addition to the hazards of the failure, road corridors often have to remain open to continue to provide vital transport connections for the continuation of freight movement, people movement, and emergency services (e.g., ambulance, fire and rescue) which adds further constraints when choosing site investigation methods. Geophysical techniques provide a potentially safer alternative to traditional boreholes when investigating failure sites with the ability to be flexible with the continuation of road traffic. This paper presents a discussion of the advantages and limitations of some of the available geophysical techniques that could be utilized when conducting geotechnical site investigations at road embankment failures. A recent case study of a road embankment failure is also presented where the use of geophysical methods was utilized due to borehole drilling being deemed unsafe at the failure site.