In Pipe GPR Survey, London

Project summary

The water main consists of a concrete pipe that has been relined with a glass-reinforced plastic (GRP) pipe. Grout has been injected between the GRP and the concrete pipes.

The brief

The purpose of the survey was to determine the presence and location of voiding within the grout, between the GRP and concrete materials.

The challenges

Due to the confined nature of the pipe, it was not possible to allow people within the pipe to scan. Therefore, a remote data collection method was used. This was undertaken using a pipe inspection vehicle that had been custom made for the project by Water Services Group.

Previous trial scans have been undertaken on other sections of the pipe. These were found to provide the methodology of the process and resulted in good quality data.

Our work

The data was collected by Water Services Group who utilised a remote pipe inspection vehicle (PIV), fitted with a ground penetrating radar (GPR) antenna. A Utsi GV3 GPR system, utilising a 4GHz antenna, was used to collect the data alongside a CCTV system. A robotic arm attached to the crawler allowed for the remote positioning of the GPR against the surface at the correct locations.

Results

The data was analysed, and potential defects were identified, located, and mapped. Murphy Geospatial was able to provide both Water Services Group and the end client a comprehensive analysis of the tunnel lining and the location and type of defects present therein.