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Land protection by improvement of Dike construction

Final Report Summary - PRODICON (Land protection by improvement of Dike construction)

Flood disasters account for about a third of all natural catastrophes throughout the world (by number and economic losses) and are responsible for more than half of the fatalities. Trend analyses reveal that major flood disasters and the losses generated by them have increased drastically in recent years. For this reason it is important to take appropriate steps without delay. On the one hand, the efforts that are being taken to combat climate change must be stepped up, while on the other hand we must pay more attention to flood protection and loss minimisation or prevention.

These disasters could be significantly attenuated by improved technical flood protection. One main part of flood protection is the dike rehabilitation of existing dikes (some of them were built more than 150 years ago) as the majority of existing dikes do not fulfil the existing safety standards. Existing dike rehabilitation techniques are quite often expensive with a limited field of application.

The proposed PRODICON system targeted this problem by developing a universal dike rehabilitation technology applicable to all types and states of dikes. The PRODICON technology is an innovative and economical technology for dike rehabilitation due to the on-site and in situ preparation of the novel dike sealing material. By applying the PRODICON technology during dike rehabilitation transport processes can be minimised significantly. Beside the material development the PRODICON project aimed to develop a novel technique for the application of dike sealing material. The novel technique can also be applied to wetted and softened dikes where the usual technologies must fail due to heavy construction machines — this could be seen very impressive during and after the recent flood disasters.

The properties of the new dike sealing material are low water permeability, high erosion resistance, high stability and good processing qualities. The so-called MTG (modified clay mixture) consists mainly of a mixture of clayey materials. An additive breaks up the water film surrounding the individual granules and the mixture penetrates into the pores of the soil. This leads to stronger adhesion forces, which make the individual particles of the soil cling to one another. The result is the pore volume is reduced and thus the coefficient of permeability [kf value] is minimised.

The MTG is mixed and prepared in a specially designed and manufactured mixing and transportation plant. The mixture is placed in the structure through boreholes. For this purpose the tube-a-sleeve (TAS) or vibrating lance technique is applied, which is well know from the soil injection method. A special technique is the use of rotating drill rods which simultaneously serve as injection lances. It is also possible to use the spray application process or to inject into existing masonry for other application areas. No rigid injection body is formed, so that any subsoil displacements are compensated for and no new leaks will occur. In many cases, passivation may help to avoid soil replacement. This environmentally friendly technique allows injection to be carried out in all groundwater zones. In comparison with conventional sealing methods, the use of MTG is a more cost effective option.

With the PRODICON material, leaching through the dike and a washout of the dike material will be avoided. The plant is based on a conventional excavator, on which modified equipment units are combined. The finished sealing material is delivered by suitable pumping equipment to the site and installed. A very good intermixture of the injected material and the in-situ soil was realised and damaged dike sections were stabilised. As both field tests finished with such convincing results, the PRODICON technology is now ready for commercial launch and further application on different damaged dikes and dams.

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