Funding Project Management Coordination 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
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Funding Project Management Coordination Structural Approaches – Dikes, Reservoirs and Dams IMPROVEMENT OF THE GENERAL RESISTANCE OF DIKES AGAINST EROSION.
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Funding Project Management Coordination
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
11.04.23 | Institut für Wasserbau und Wasserwirtschaft | Fachgebiet Wasserbau | Prof. Dr. -Ing habil U. Zanke | Dipl. -Ing. T. Kubetzek | 2
• 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
Introduction
Experiment Set-up
Dimensioning
Measurement program
Outlook
Introduction
11.04.23 | Institut für Wasserbau und Wasserwirtschaft | Fachgebiet Wasserbau | Prof. Dr. -Ing habil U. Zanke | Dipl. -Ing. T. Kubetzek | 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
11.04.23 | Institut für Wasserbau und Wasserwirtschaft | Fachgebiet Wasserbau | Prof. Dr. -Ing habil U. Zanke | Dipl. -Ing. T. Kubetzek | 4
Introduction
Experiment set-up
Dimensioning
Measurement program
Outlook
Experiment set-up
11.04.23 | Institut für Wasserbau und Wasserwirtschaft | Fachgebiet Wasserbau | Prof. Dr. -Ing habil U. Zanke | Dipl. -Ing. T. Kubetzek | 5
Introduction
Experiment set-up
Dimensioning
Measurement program
Outlook
Experiment set-up
• 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
11.04.23 | Institut für Wasserbau und Wasserwirtschaft | Fachgebiet Wasserbau | Prof. Dr. -Ing habil U. Zanke | Dipl. -Ing. T. Kubetzek | 6
Introduction
Experiment set-up
Dimensioning
Measurement program
Outlook
Experiment set-up
11.04.23 | Institut für Wasserbau und Wasserwirtschaft | Fachgebiet Wasserbau | Prof. Dr. -Ing habil U. Zanke | Dipl. -Ing. T. Kubetzek | 7
Introduction
Experiment set-up
Dimensioning
Measurement program
Outlook
Experiment set-up
• 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
11.04.23 | Institut für Wasserbau und Wasserwirtschaft | Fachgebiet Wasserbau | Prof. Dr. -Ing habil U. Zanke | Dipl. -Ing. T. Kubetzek | 8
Introduction
Experiment set-up
Dimensioning
Measurement program
Outlook
Experiment set-up
• Fixing by pegs– State of construction– Worst case scenario
• Stabilization by root penetration– Common loading case– Difficult to calculate– Laboratory test of shear resistance
11.04.23 | Institut für Wasserbau und Wasserwirtschaft | Fachgebiet Wasserbau | Prof. Dr. -Ing habil U. Zanke | Dipl. -Ing. T. Kubetzek | 9
Introduction
Experiment set-up
Dimensioning
Measurement program
Outlook
Dimensioning
– 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
11.04.23 | Institut für Wasserbau und Wasserwirtschaft | Fachgebiet Wasserbau | Prof. Dr. -Ing habil U. Zanke | Dipl. -Ing. T. Kubetzek | 10
Introduction
Experiment set-up
Dimensioning
Measurement program
Outlook
Dimensioning
– 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
11.04.23 | Institut für Wasserbau und Wasserwirtschaft | Fachgebiet Wasserbau | Prof. Dr. -Ing habil U. Zanke | Dipl. -Ing. T. Kubetzek | 11
Introduction
Experiment set-up
Dimensioning
Measurement program
Outlook
Dimensioning
• 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
Shear stress against the overflow
0
500
1000
1500
2000
0,0 0,5 1,0 1,5 2,0 2,5
q [m³/s/m]
max
t 0 [
N/m
²]
11.04.23 | Institut für Wasserbau und Wasserwirtschaft | Fachgebiet Wasserbau | Prof. Dr. -Ing habil U. Zanke | Dipl. -Ing. T. Kubetzek | 12
Introduction
Experiment set-up
Dimensioning
Measurement program
Outlook
Dimensioning
• 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
Experiment 5Ad = 12mm; L = 500mm
0
10
20
30
40
50
60
70
80
0 500 1000 1500 2000 2500 3000 3500
Force [N]
Lo
ad
-dis
pla
ce
me
nt
[mm
]
11.04.23 | Institut für Wasserbau und Wasserwirtschaft | Fachgebiet Wasserbau | Prof. Dr. -Ing habil U. Zanke | Dipl. -Ing. T. Kubetzek | 13
Introduction
Experiment set-up
Dimensioning
Measurement program
Outlook
Dimensioning
• 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
11.04.23 | Institut für Wasserbau und Wasserwirtschaft | Fachgebiet Wasserbau | Prof. Dr. -Ing habil U. Zanke | Dipl. -Ing. T. Kubetzek | 14
Introduction
Experiment set-up
Dimensioning
Measurement program
Outlook
Dimensioning
• 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
11.04.23 | Institut für Wasserbau und Wasserwirtschaft | Fachgebiet Wasserbau | Prof. Dr. -Ing habil U. Zanke | Dipl. -Ing. T. Kubetzek | 15
Introduction
Experiment set-up
Dimensioning
Measurement program
Outlook
Measurement program
• 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
11.04.23 | Institut für Wasserbau und Wasserwirtschaft | Fachgebiet Wasserbau | Prof. Dr. -Ing habil U. Zanke | Dipl. -Ing. T. Kubetzek | 16
Introduction
Experiment set-up
Dimensioning
Measurement program
Outlook
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
11.04.23 | Institut für Wasserbau und Wasserwirtschaft | Fachgebiet Wasserbau | Prof. Dr. -Ing habil U. Zanke | Dipl. -Ing. T. Kubetzek | 17