Summer 2016

TenCate GeoDetect® is a tried and tested solution for detecting and limiting the effects of a sinkhole in a storage basin holding process water. It can be used in dykes, railways and basins for the storage of polluted liquids, as was recently the case in France.

Strain in earthworks is now easier to measure accurately by using fibre optic sensing technology in combination with geotextiles, such as TenCate GeoDetect®. This is a patented system based on geotextiles with interwoven optical sensors for monitoring soil strain in earthworks. It can be used to monitor either local earthworks such as walls and slopes or long infrastructures like roads, railways and dykes. The technology has now been in use in numerous countries for almost ten years.

geodetect france basin
The basin in France has an 
area of 300,000 m² and a storage capacity of 3.3 million m3

A recent example of the use of TenCate GeoDetect® relates to a basin in the east of France used for the storage of industrial, salted water. This former gravel pit is located near a river with a two- kilometre long peripheral dyke. The water in this basin is stored here for about six months of the year so as to be able to release the effluent into a nearby river when the water flow is high enough (in winter). The bottom of the pit is below the water table and is therefore lined with among other materials geotextiles and geomembrane.

geodetect novacarb
For strengthening TenCate Geolon® PET 1600 is being applied

Several years ago an increase in the quantity of chemicals was detected. A study and analysis of the settlements revealed a tear in the geomembrane. The cause was a three-metre deep circular cavity measuring some 6 m². 

sinkhole france
Sinkhole

At three other locations the clayey substratum proved to be no longer intact. In order to ease the strain that this caused, it was decided to install a reinforcement structure of the foundation with geotextile, combined with a detection and localization system of the cavity with the fibre optic sensor-enabled geotextile. This enables even very small soil strains to be detected so that action can be taken.

geodetect france basin to be monitored
The area to be monitored

The TenCate GeoDetect® solution using these materials and technology is now detecting any soil strain that occurs. Up to the present time the measures taken have proven effective.

Blue fabric (Tecawork Blue 65287)