Today, Deltares will start a unique experiment with geotextile on the IJkdijk in Groningen.
The 15 m wide and 0,5 m long textile has been positioned vertically on the test dike. Over a period of one week, tests will be conducted to see if this approach can counteract piping. Sensors and water-pressure meters will be used for monitoring. Geotextile has been used in hydraulic engineering for some time now but using it to deal with piping is an entirely new application.
Piping has an enormous impact on the stability of a dike and it is therefore absolutely essential to confine this process. Previous studies have shown that it is one of the most important dike failure mechanisms. It occurs at the sand-clay interface, when water levels are high. The resulting pressure can force water to seep through the base of a dike. This water may take grains of sand with it, creating tubular openings (pipes) under the dike, which get bigger and bigger, endangering the stability of the structure. If piping is not confined, it can weaken the dike with the result that it can sag and, in the worst case, cause it to collapse.
If the dike passes the test, geotextile could be used as a cheaper alternative to the current measures in place to stop piping, such as widening dikes using berms or putting in sheet piling. If the experiment works out, the textile can be tested on a number of sites on a stretch of dike in the Rivierenland area.
[mappress]
Dredging Today Staff, September 24, 2012; Image: deltares