Evaluation of geotechnical stability of road using GPR

Recently the road networks are more and more exposed to an increased landslide risk. It is generally caused by heavy weather conditions and a severe deficit of maintenance. Usually, it is easy to locate the damage as it becomes visible whereas it is difficult to identify the causes. In order to diagnose the damage before it becomes visible and severe, to identify the main cause and to implement the most effective rehabilitation measure, we propose the use of Ground Penetrating Radar for geotechnical inspection of pavement and sub-pavement layers. Different equipments were used and a survey protocol was tested in several situations characterized by landslide movements with different degrees of severity. For the inspection, 600, 1000 and 1600 MHz antennae were used. The 1 GHz horn antenna was used for a first survey at traffic speed in order to reduce traffic interference and to locate any possible anomaly. The other dipole antennae were used for more detailed investigations. GPR data were post-processed in the time and frequency domain, using the “Surface reflection method” and the Rayleigh scattering. This approach provides an innovative method that can be applied for accurate and non-invasive monitoring of alert conditions near to road pavements.