Funding

1. Funding Coordination Project Management Structural Approaches – Dikes, Reservoirs and Dams IMPROVEMENT OF THE GENERAL RESISTANCE OF DIKES AGAINST EROSION DURING DIKE OVERFLOW Tobias Kubetzek, Jesper Steuernagel, Hendrik Ramm, Nicole Saenger, Ulrich Zanke

2. Introduction Introduction Experiment Set-up Dimensioning Measurement program Outlook • Urbanization brought a great damage potential to the areas along the rivers and to former floodplains. This trend has not been stopped yet • During the last flood periods several dams and dikes broke, causing enormous damage and the loss of many lives • As a consequence of the climate change the sea level and the river gauges will rise. Dikes existing could lose their protectional function within the next years • In the near future the majority of the German river dikes must be redeveloped 08.10.2014 | Institut für Wasserbau und Wasserwirtschaft | Fachgebiet Wasserbau | Prof. Dr. -Ing habil U. Zanke | Dipl. -Ing. T. Kubetzek | 2

3. Introduction Introduction Experiment Set-up Dimensioning Measurement program Outlook • Dikes effected by overflow must be built as an overflow structure, otherwise overflowing water erodes the top and the landside of the dike • In general erosion leads to a quick collapse of the dike • Common overflow section of dikes are protected by armourstones or concrete sealing. These methods are not suitable for the long distances of river dikes • Conventional structures of geosynthetics are not practicable for redevelopement 08.10.2014 | Institut für Wasserbau und Wasserwirtschaft | Fachgebiet Wasserbau | Prof. Dr. -Ing habil U. Zanke | Dipl. -Ing. T. Kubetzek | 3

4. Experiment set-up Introduction Experiment set-up Dimensioning Measurement program Outlook 08.10.2014 | Institut für Wasserbau und Wasserwirtschaft | Fachgebiet Wasserbau | Prof. Dr. -Ing habil U. Zanke | Dipl. -Ing. T. Kubetzek | 4

5. Experiment set-up Introduction Experiment set-up Dimensioning Measurement program Outlook • Full scale research dike (dimensions of a common dike along the Rhine, Germany) • A closed sheeting and a high capacity propeller pump enable the overtopping of the dike • Two experimental areas • Weir heads according to the width of the spillway slab 08.10.2014 | Institut für Wasserbau und Wasserwirtschaft | Fachgebiet Wasserbau | Prof. Dr. -Ing habil U. Zanke | Dipl. -Ing. T. Kubetzek | 5

6. Experiment set-up Introduction Experiment set-up Dimensioning Measurement program Outlook 08.10.2014 | Institut für Wasserbau und Wasserwirtschaft | Fachgebiet Wasserbau | Prof. Dr. -Ing habil U. Zanke | Dipl. -Ing. T. Kubetzek | 6

7. Experiment set-up Introduction Experiment set-up Dimensioning Measurement program Outlook • Revetment with new combinations of geosynthetics • Erosion control mat • Geogrid (top layer) • Non woven geotextile • Geogrid (bottom layer) • Top soil not as sacrificial layer but as part of the revetment • Stable with and without vegetation 08.10.2014 | Institut für Wasserbau und Wasserwirtschaft | Fachgebiet Wasserbau | Prof. Dr. -Ing habil U. Zanke | Dipl. -Ing. T. Kubetzek | 7

8. Experiment set-up Introduction Experiment set-up Dimensioning Measurement program Outlook • Fixing by pegs • State of construction • Worst case scenario • Stabilization by root penetration • Common loading case • Difficult to calculate • Laboratory test of shear resistance 08.10.2014 | Institut für Wasserbau und Wasserwirtschaft | Fachgebiet Wasserbau | Prof. Dr. -Ing habil U. Zanke | Dipl. -Ing. T. Kubetzek | 8

9. Dimensioning Introduction Experiment set-up Dimensioning Measurement program Outlook • Erosion of top soil and vegetation • Gliding of the top soil on the geosynthetics • Gliding of the geosynthetics on the ground • Erosion beneath the geosynthetics • Failure of the geosynthetics or the anchorage 08.10.2014 | Institut für Wasserbau und Wasserwirtschaft | Fachgebiet Wasserbau | Prof. Dr. -Ing habil U. Zanke | Dipl. -Ing. T. Kubetzek | 9

10. Dimensioning Introduction Experiment set-up Dimensioning Measurement program Outlook • Erosion of top soil and vegetation • Gliding of the topsoil on the geosynthetics • Gliding of the geosynthetics on the ground • Erosion beneath the geosynthetics • Failure of the geosynthetics or the anchorage 08.10.2014 | Institut für Wasserbau und Wasserwirtschaft | Fachgebiet Wasserbau | Prof. Dr. -Ing habil U. Zanke | Dipl. -Ing. T. Kubetzek | 10

11. Dimensioning Introduction Experiment set-up Dimensioning Measurement program Outlook • Wire heads up to 1.0 m causes shear stresses of approx. 900 N/m² • Investigation of heads up to 0.3 m • Loads have to be transferred by pegs 08.10.2014 | Institut für Wasserbau und Wasserwirtschaft | Fachgebiet Wasserbau | Prof. Dr. -Ing habil U. Zanke | Dipl. -Ing. T. Kubetzek | 11

12. Dimensioning Introduction Experiment set-up Dimensioning Measurement program Outlook • Minimization of load-displacement • Search for an optimal pitch • Reduction of effort while increase in efficiency • Reduction of the number of parts lowers the cost of deployment and maintenance 08.10.2014 | Institut für Wasserbau und Wasserwirtschaft | Fachgebiet Wasserbau | Prof. Dr. -Ing habil U. Zanke | Dipl. -Ing. T. Kubetzek | 12

13. Dimensioning Introduction Experiment set-up Dimensioning Measurement program Outlook • Finite-Element-Method (FEM) simulation of the deformation • ABAQUS 2-D-model • FEM-simulation of the estimated forces during the overflow • ABAQUS 3-D-model • Adaption of the peg pitch • Adaption of the top anchorage 08.10.2014 | Institut für Wasserbau und Wasserwirtschaft | Fachgebiet Wasserbau | Prof. Dr. -Ing habil U. Zanke | Dipl. -Ing. T. Kubetzek | 13

14. Dimensioning Introduction Experiment set-up Dimensioning Measurement program Outlook • Starting conditions • Peg dimension of 0.5 m length and Ø=12 mm • Spillway slab of 20 m to 12 m • Starting pitch 1 x 1 m • Non-vegetated (worst case) revetment 08.10.2014 | Institut für Wasserbau und Wasserwirtschaft | Fachgebiet Wasserbau | Prof. Dr. -Ing habil U. Zanke | Dipl. -Ing. T. Kubetzek | 14

15. Measurement program Introduction Experiment set-up Dimensioning Measurement program Outlook • Pressure sensor • Indikation of turbulences • Area scanner • Deformation of the geosynthetics • Ground radar • Erosion beneath the geosynthetics • Change in density of / rearrangement in the subsoil • If applicable • Resistance strain gauges on the geogrid • Turbidity sensor • Indication of erosion 08.10.2014 | Institut für Wasserbau und Wasserwirtschaft | Fachgebiet Wasserbau | Prof. Dr. -Ing habil U. Zanke | Dipl. -Ing. T. Kubetzek | 15

16. Outlook Introduction Experiment set-up Dimensioning Measurement program Outlook • Short-term experiments in 2008 • Certification of the effectivity of the geosynthetic combination (stability in a worst case scenario) • Optimizing the pitch for the pegs • Long-term experiment (winter 2008 / spring 2009) • Laboratory test of the shear resistance • Overflow on the vegetated testing area • Experiments with alternative erosion protection measures • Aim • Consideration of our results in the guidance for the remediation of the river dikes in Hesse, Germany 08.10.2014 | Institut für Wasserbau und Wasserwirtschaft | Fachgebiet Wasserbau | Prof. Dr. -Ing habil U. Zanke | Dipl. -Ing. T. Kubetzek | 16

17. End Introduction Experiment set-up Dimensioning Measurement program Outlook Thank you for your attention 08.10.2014 | Institut für Wasserbau und Wasserwirtschaft | Fachgebiet Wasserbau | Prof. Dr. -Ing habil U. Zanke | Dipl. -Ing. T. Kubetzek | 17