Efficient Tunnel Inspection Methods: Seeking Suggestions

[Axefly]

Good afternoon

I'm doing geological surveying, magnetronomy, Orthomosiac photography and visual inspection of structures, with our UAV's

I am currently developing a radar/laser guided system for inspecting hydro-electric tunnels. I want to incorporate it with a 360deg photo of the tunnel diameter.

Does anyone have any good ideas on how to approach this and if there are any better ways of doing this ?

 

[etudiant]

Interesting challenge.
Hydro tunnels can be miles long and are rarely empty after they have been dug. So getting power to your system will be problem one. Guidance will be problem two, no reliable GPS underground, radar and water don't mix, laser in water has range and absorption issues. A power/tether cable can give pretty basic location data.
Afaik, the major concern in hydro tunnels are leakage and wall failures. The early signs of either are not that obvious, so getting a good understanding of what you are looking for is probably a reasonable start.

 

[Axefly]

Thanks Etudiant :)

 

[rollingstein]

Will that be a flying vehicle or a boat / sub like thing?

A tether cable plus a sonar ping (radial location) might give you enough localization data. To test wall integrity one way is some sort of sonar or ultrasound pulse. Leakage should be harder to monitor.

 

[Axefly]

Thanks Rollenstein sounds interesting, however the vehicle won't be submersed the tunnel would not be completely dry.

We are toying around a "leaky cable" system, that we will drive out with a tracked vehicle attached to a strong cable for retrieval.
This way we can send radio signals along the cable.
The other idea is to go very low frequency, but then we have to beg the military for some help to use their frequencies...

i appreciate any suggestions.

 

[Axefly]

This is purely for visual inspections. The tunnels will be drained during our testing, and we have geo-hydrologists that will measure the hydraulic conductivity with packer systems around the tunnels, this will show up any leakage into the surrounding bedrock and earth.
We do hydraulic conductivity testing as part of our service as well.

 

[etudiant]

Depending on the site (some tunnels are very steep), an electrically driven tracked vehicle dragging a power cable along with a fiber optics link would seem a possibility. That gives you all the bandwidth you might want.