Evaluation of tunnel condition presents a challenging problem. Roadway and rail tunnels, by their very design are subject to a constant presence of moisture, even in relatively dry climates. This leads to a number of problems such as corrosion of embedded reinforcement, voids between the liner and base material, and water flow through and behind the liner, which sometimes appears in locations remote to the water source.

Penetradar Corporation has developed a multi-sensor, NDT system that combines ground penetrating radar (GPR), infrared thermography (IRT) and high resolution imaging (HRI) technologies to detect and identify many types of tunnel liner defects. The system is entirely mobile and rapid, and can assess the condition all parts of roadway and rail tunnel liner without the need for prolonged tunnel closures.

Non-Destructive Evaluation Of Tunnel Liners

Using Ground Penetrating Radar, Infrared Thermography and High Resolution Imaging

Typical Results of NDT Tunnel Inspection

The results of the nondestructive evaluation of the tunnel lining are both quantitative and graphical. Locations of defects are graphically shown as an “unfolded” 2D plot and quantities are provided in numerical format. The use of NDT technologies can provide a more complete and comprehensive assessment of the current condition of a tunnel liner and help to prioritize repairs.

Contact us for more information on non-destructive tunnel liner inspection or to find out whether this technology may be suitable in your application.

Results of the NDT inspection are shown above in the form of plan-view mappings depicting high resolution (video) images, thermal images, and GPR signal strength (attenuation) and dielectric constant. The methods detect conditions such as water flow behind tiles, deteriorated concrete, water saturated concrete and debonded tiles.

Penetradar’s Tunnel Inspection System – GPR Inspection of Tunnel Liner