Millimetre-wave technology able to provide range and angular measurements with a very high accuracy

 

State of the art

 

Geothermal based building retrofitting involves complex operations, such as drilling and digging, which may in principle interfere with the stability of buildings close to the work area; as a matter of fact, ground in the vicinity of the buildings under retrofitting may be subjected to movement or even collapse when drilling/digging and this can compromise the stability of that building. A possible effective solution to perform building stability monitoring is the GBInSA R technology, which nowadays is a key tool able of remotely monitoring millimetre displacements at large distance (up to several kilometres). Typical applications are: slope stability monitoring in mining plants, landslide monitoring in risk areas close to civil buildings, bridge load testing and stability monitoring. Unfortunately, available technologies use signals with a main frequency around 16 GHz and this does not permit to achieve a high resolution and neither to measure the displacement of the building in 3-D.

 

The GEOFIT solution

 

A radar that uses a millimetre wave technology (W band) has been recently designed and this is theoretically able to provide both range and angular measurements with a very high accuracy (< 0.1 millimiters). This technology is theoretically exploitable for monitoring the stability of a building in 3-D. The use of a monitoring system based on the radar technology is not new and allows to remotely monitor the displacements of thousands of points over a surface, with a high accuracy and without the need of installing any reflector. Therefore, this radar has the potential to be a perfect tool to assess the stability of the buildings interested by the retrofitting operations providing high accuracy stability information from thousands of measurement points. However, the technology at the state of the art cannot be fully exploited due to some intrinsic limitations that need to be solved by GEOFIT.

 

The GEOFIT contribution

 

Specifically, the research will address:

  1. The capability of obtaining a fast acquisition, as well as a large field of view, with three-dimensional spatial resolution (range, azimuth, elevation) in order correctly identify the position of possible displacement over the whole building surface.
  2. The capability of overcoming phase ambiguity, peculiar limitation of radar interferometry, in order to enable the completion of the measurement in a small amount of time. In other words, this phase ambiguity is currently limiting the capability of the radar to measure the frequency of resonance of the monitored structure. Hence, the development of such a radar system will both substantially improve the state-of-art of GBinSAR technology, and introduce a novel safety monitoring tool capable to provide useful information on the stability of buildings.

 

Technology readiness level improvement: From TRL6 to TRL7