The Dutch have developed various innovative techniques to reinforce dikes under difficult circumstances. One of these techniques is 'expanding columns'. Perforated steel tubes are driven through the core of the levee and the weak upper subsoil. After filling the tubes under high pressure with a mixture of concrete and bentonite, the tubes are standing like pikes in the sandy subsoil like shoulders underneath the levee. Filling the tubes under high pressure causes the expanding of the columns and the compression of weak soil so that the weak upper subsoil becomes more compact.

(ARCADIS, BAM Grondtechniek, DHV, Van Oord)