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J.C. Pol
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1
Internal erosion is a significant cause of failure in dams, levees and other hydraulic structures. This article studies the time-dependent reliability of such structures under Backward Erosion Piping (BEP), a form of internal erosion in the foundation. First, a physics-based time-dependent piping failure model is presented. Second, a time-variant reliability analysis method is presented which allows to quantify how the reliability evolves over the years due to cumulative pipe growth over multiple flood events. Finally, these models are used to study the importance of time-dependence for reliability estimates of flood defenses in The Netherlands. The findings show that, particularly in coastal areas, incorporating time-dependence significantly reduces the computed failure probability. Reductions vary widely, ranging from a factor of 5 to more than (Formula presented.) depending on flood duration and levee properties. Therefore, reliability estimates for levees can be improved by incorporating time-dependent pipe development in the BEP failure model, and thereby contribute to avoiding unnecessary reinforcements.
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Internal erosion is a significant cause of failure in dams, levees and other hydraulic structures. This article studies the time-dependent reliability of such structures under Backward Erosion Piping (BEP), a form of internal erosion in the foundation. First, a physics-based time-dependent piping failure model is presented. Second, a time-variant reliability analysis method is presented which allows to quantify how the reliability evolves over the years due to cumulative pipe growth over multiple flood events. Finally, these models are used to study the importance of time-dependence for reliability estimates of flood defenses in The Netherlands. The findings show that, particularly in coastal areas, incorporating time-dependence significantly reduces the computed failure probability. Reductions vary widely, ranging from a factor of 5 to more than (Formula presented.) depending on flood duration and levee properties. Therefore, reliability estimates for levees can be improved by incorporating time-dependent pipe development in the BEP failure model, and thereby contribute to avoiding unnecessary reinforcements.
Backward erosion piping (BEP) is a failure mechanism of hydraulic structures like dams and levees on cohesionless foundations subjected to seepage flows. This article models the time-dependent development of BEP using numerical simulation of the erosion process. A 3-dimensional finite element equilibrium BEP model is extended with a formulation for the sediment transport rate. The model is compared to and calibrated with small- and large-scale experiments. Finally, a large set of simulations is analyzed to study the effects of factors such as grain size, scale (seepage length) and overloading on the rate of pipe progression. The results show that the development of BEP in the small-scale experiments is predicted well. Challenges remain for the prediction at larger scales, as calibration and validation is hard due to limited large-scale experiments with sufficiently accurate measurements. The results show that the progression rate increases with grain size and degree of overloading and decreases with seepage length, which is consistent with experimental observations. The model results provide a better physical basis for incorporating time-dependent development in the risk assessment and design of levees.
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Backward erosion piping (BEP) is a failure mechanism of hydraulic structures like dams and levees on cohesionless foundations subjected to seepage flows. This article models the time-dependent development of BEP using numerical simulation of the erosion process. A 3-dimensional finite element equilibrium BEP model is extended with a formulation for the sediment transport rate. The model is compared to and calibrated with small- and large-scale experiments. Finally, a large set of simulations is analyzed to study the effects of factors such as grain size, scale (seepage length) and overloading on the rate of pipe progression. The results show that the development of BEP in the small-scale experiments is predicted well. Challenges remain for the prediction at larger scales, as calibration and validation is hard due to limited large-scale experiments with sufficiently accurate measurements. The results show that the progression rate increases with grain size and degree of overloading and decreases with seepage length, which is consistent with experimental observations. The model results provide a better physical basis for incorporating time-dependent development in the risk assessment and design of levees.
During the July 2021 Flood, the main flood defences along the River Meuse in the Netherlands performed well and did not breach. This paper is meant to document the various incidents on the flood defence system. As such, it provides an overview and description of the reported incidents related to flood defences, including a few breaches in minor flood defences. The incidents include overflow of embankments, sand boils, internal erosion at structures, and damage to a large weir and an outflow structure. Also, two local flood defences breached: an emergency embankment at Horn and an embankment in Roermond. During the event, the media reported on a dike breach at Meerssen/Bunde, however, after further investigation, it appeared that the concentrated outflow there was fuelled from a forgotten buried culvert.
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During the July 2021 Flood, the main flood defences along the River Meuse in the Netherlands performed well and did not breach. This paper is meant to document the various incidents on the flood defence system. As such, it provides an overview and description of the reported incidents related to flood defences, including a few breaches in minor flood defences. The incidents include overflow of embankments, sand boils, internal erosion at structures, and damage to a large weir and an outflow structure. Also, two local flood defences breached: an emergency embankment at Horn and an embankment in Roermond. During the event, the media reported on a dike breach at Meerssen/Bunde, however, after further investigation, it appeared that the concentrated outflow there was fuelled from a forgotten buried culvert.
The Shields–Darcy (SD) model by Hoffmans and Van Rijn (Citation2018) describes the resistance of hydraulic structures to backward erosion piping, which is a form of internal erosion. In the article being discussed, Hoffmans compares the SD model to the model by Sellmeijer et al. (Citation2011), focusing on field scales. This Discussion presents finite element simulations that deviate from Hoffmans’ conclusions that the model by Sellmeijer et al. (Citation2011) results in an unrealistically low critical gradient. As both the SD and Sellmeijer models fit reasonably well to laboratory experiments (Hoffmans & Van Rijn, Citation2018), extrapolation to field scales (say aquifer thickness D > 5 m, seepage length L > 10 m) is important, particularly since these models are used for the design of flood defences. Hoffmans addresses this issue by analysing the resistance as function of aquifer depth D. Hoffmans recommends checking the outcomes of the SD model with a mathematical piping model like that of Van Esch et al. (Citation2013).
...
The Shields–Darcy (SD) model by Hoffmans and Van Rijn (Citation2018) describes the resistance of hydraulic structures to backward erosion piping, which is a form of internal erosion. In the article being discussed, Hoffmans compares the SD model to the model by Sellmeijer et al. (Citation2011), focusing on field scales. This Discussion presents finite element simulations that deviate from Hoffmans’ conclusions that the model by Sellmeijer et al. (Citation2011) results in an unrealistically low critical gradient. As both the SD and Sellmeijer models fit reasonably well to laboratory experiments (Hoffmans & Van Rijn, Citation2018), extrapolation to field scales (say aquifer thickness D > 5 m, seepage length L > 10 m) is important, particularly since these models are used for the design of flood defences. Hoffmans addresses this issue by analysing the resistance as function of aquifer depth D. Hoffmans recommends checking the outcomes of the SD model with a mathematical piping model like that of Van Esch et al. (Citation2013).
Journal article
(2023)
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Johannes C. Pol, Paulina Kindermann, Mark G. van der Krogt, Vera M. van Bergeijk, Guido Remmerswaal, Willem Kanning, Sebastiaan N. Jonkman, Matthijs Kok
Structural reliability analysis often considers failure mechanisms as correlated but non-interacting processes. Interacting failure mechanisms affect each others performance, and thereby the system reliability. We describe such interactions in the context of flood defenses, and analyze under which conditions such interactions have a large impact on reliability using a Monte Carlo-based quantification method. We provide simple examples and an application to levee failure due to landward slope instability and backward erosion piping (BEP). The examples show that the largest interaction effects are expected when the trigger mechanism is relatively likely to occur and the affected mechanism has a relatively large contribution to the system reliability. For the studied levee example, interactions between slope instability and BEP increased the failure probability up to a factor 4. Implications for the assessment and design of flood defenses are discussed.
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Structural reliability analysis often considers failure mechanisms as correlated but non-interacting processes. Interacting failure mechanisms affect each others performance, and thereby the system reliability. We describe such interactions in the context of flood defenses, and analyze under which conditions such interactions have a large impact on reliability using a Monte Carlo-based quantification method. We provide simple examples and an application to levee failure due to landward slope instability and backward erosion piping (BEP). The examples show that the largest interaction effects are expected when the trigger mechanism is relatively likely to occur and the affected mechanism has a relatively large contribution to the system reliability. For the studied levee example, interactions between slope instability and BEP increased the failure probability up to a factor 4. Implications for the assessment and design of flood defenses are discussed.
Journal article
(2022)
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Johannes C. Pol, Willem Kanning, Vera M. van Beek, Bryant A. Robbins, Sebastiaan N. Jonkman
Backward erosion piping (BEP) is a form of internal erosion which can lead to failure of levees and dams. Most research focused on the critical head difference at which piping failure occurs. Two aspects have received less attention, namely (1) the temporal evolution of piping and (2) the local hydraulic conditions in the pipe and at the pipe tip. We present small-scale experiments with local pressure measurements in the pipe during equilibrium and pipe progression for different sands and degrees of hydraulic loading. The experiments confirm a positive relation between progression rate and grain size as well as the degree of hydraulic overloading. Furthermore, the analysis of local hydraulic conditions shows that the rate of BEP progression can be better explained by the bed shear stress and sediment transport in the pipe than by the seepage velocity at the pipe tip. The experiments show how different processes contribute to the piping process and these insights provide a first empirical basis for modeling pipe development using coupled seepage-sediment transport equations.
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Backward erosion piping (BEP) is a form of internal erosion which can lead to failure of levees and dams. Most research focused on the critical head difference at which piping failure occurs. Two aspects have received less attention, namely (1) the temporal evolution of piping and (2) the local hydraulic conditions in the pipe and at the pipe tip. We present small-scale experiments with local pressure measurements in the pipe during equilibrium and pipe progression for different sands and degrees of hydraulic loading. The experiments confirm a positive relation between progression rate and grain size as well as the degree of hydraulic overloading. Furthermore, the analysis of local hydraulic conditions shows that the rate of BEP progression can be better explained by the bed shear stress and sediment transport in the pipe than by the seepage velocity at the pipe tip. The experiments show how different processes contribute to the piping process and these insights provide a first empirical basis for modeling pipe development using coupled seepage-sediment transport equations.
Backward erosion piping (BEP) is a type of internal erosion responsible for the failure of many dams and levees. BEP occurs when small, shallow erosion channels progress upstream through foundation sands beneath the structure. As analysis of BEP involves coupling two different sets of flow equations to describe the groundwater flow and erosion pipe flow, the solution contains a singularity in the gradient field at the juncture of the soil and pipe domains. In addition, the erosion process is highly localized, often occurring over length scales of 1 cm or less. While it is well known that singularities and localized phenomena cause high errors in numerical solutions, there has been no assessment of the magnitude of these errors in BEP numerical models. This study evaluates the magnitude of error in BEP finite element models through comparison of numerical results to measurements from a highly instrumented BEP experiment. The results indicate that discretization errors related to the pipe geometry can cause 50%–300% error in the solution near the pipe tip when the pipe is represented via linear, 1D elements. These errors are significant and must be considered for models that assess pipe progression based on the local solution near the pipe tip. Results also indicate that the pipe width must be modeled as twice the physical pipe width to accurately represent the pipe flow when assuming a rectangular cross sectional shape for the erosion pipe.
...
Backward erosion piping (BEP) is a type of internal erosion responsible for the failure of many dams and levees. BEP occurs when small, shallow erosion channels progress upstream through foundation sands beneath the structure. As analysis of BEP involves coupling two different sets of flow equations to describe the groundwater flow and erosion pipe flow, the solution contains a singularity in the gradient field at the juncture of the soil and pipe domains. In addition, the erosion process is highly localized, often occurring over length scales of 1 cm or less. While it is well known that singularities and localized phenomena cause high errors in numerical solutions, there has been no assessment of the magnitude of these errors in BEP numerical models. This study evaluates the magnitude of error in BEP finite element models through comparison of numerical results to measurements from a highly instrumented BEP experiment. The results indicate that discretization errors related to the pipe geometry can cause 50%–300% error in the solution near the pipe tip when the pipe is represented via linear, 1D elements. These errors are significant and must be considered for models that assess pipe progression based on the local solution near the pipe tip. Results also indicate that the pipe width must be modeled as twice the physical pipe width to accurately represent the pipe flow when assuming a rectangular cross sectional shape for the erosion pipe.
Project Summary D3 - Time-dependent piping and interactions
A framework for safety assessment with time-dependent failure processes
This paper presents the numerical interpretation of a recent experiment on a real-scale levee physical model, in order to investigate the process of Backward Erosion Piping (BEP) and validate a recently proposed finite element formulation able to model both the simultaneous processes observed in backward erosion piping, i.e. the propagation of the pipe tip and the enlargement of the conduit cross-section, as well as the time-dependent effects. In previous papers, the numerical formulation already demonstrated its ability in reproducing available experimental data of full-scale physical models of levees, e.g. for the IJkdijk and for the Delta Flume tests. In the present work, as a further validation for the aforementioned formulation, we consider the numerical interpretation of the regressive localized internal erosion observed in the newly constructed real-scale levee at the Flood Proof Holland facility test site in Delft, The Netherlands. This test was mainly focused on the experimental evaluation of the time-dependent effects typically observed in these phenomena. To this purpose the levee foundation was equipped with an effective and accurate pore water pressure monitoring system. The aforementioned formulation was considered for the numerical interpretation of the test, in view of its ability in modeling the time-dependent effects in backward erosion piping. Indeed, a good agreement between calculated and measured piezometric heads and pipe tip propagations was obtained.
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This paper presents the numerical interpretation of a recent experiment on a real-scale levee physical model, in order to investigate the process of Backward Erosion Piping (BEP) and validate a recently proposed finite element formulation able to model both the simultaneous processes observed in backward erosion piping, i.e. the propagation of the pipe tip and the enlargement of the conduit cross-section, as well as the time-dependent effects. In previous papers, the numerical formulation already demonstrated its ability in reproducing available experimental data of full-scale physical models of levees, e.g. for the IJkdijk and for the Delta Flume tests. In the present work, as a further validation for the aforementioned formulation, we consider the numerical interpretation of the regressive localized internal erosion observed in the newly constructed real-scale levee at the Flood Proof Holland facility test site in Delft, The Netherlands. This test was mainly focused on the experimental evaluation of the time-dependent effects typically observed in these phenomena. To this purpose the levee foundation was equipped with an effective and accurate pore water pressure monitoring system. The aforementioned formulation was considered for the numerical interpretation of the test, in view of its ability in modeling the time-dependent effects in backward erosion piping. Indeed, a good agreement between calculated and measured piezometric heads and pipe tip propagations was obtained.
Structural flood protection systems such as levees are an important component in flood risk reduction strategies. Levees can fail through various failure mechanisms; this thesis focuses on the mechanism Backward Erosion Piping (BEP) which occurs when a sandy levee foundation is eroded by groundwater flow. To assess whether a levee's reliability complies with safety standards, authorities use models which describe the levee properties and failure mechanisms.
This thesis aims to extend the current failure model by considering piping as a time-dependent erosion process instead of the current assumption of immediate failure once a critical threshold is exceeded. Therefore, it is shown how time-dependent development of backward erosion piping can be quantified and how it affects levee reliability analyses. This is achieved by a combination of literature review, analysis of previous experiments, additional experiments on different scales, numerical modeling and probabilistic modeling.
The following key findings were established. Analysis of historical levee failures due to BEP and previous experiments indicates that there can be significant time between initiation and breach, highlighting the importance of time-dependence for piping. The rate of pipe progression in experiments can be explained by the sediment transport rate, which is shown to depend on the pipe flow conditions. A numerical groundwater flow model which includes this sediment transport process can predict the pipe development in small-scale experiments. Relations between the progression rate and levee properties and hydraulic loads as derived with this numerical model can be used efficiently in reliability analyses. These analyses show that including time-dependent pipe development in BEP analyses has a significant impact on the levee failure probability, both in coastal and riverine water systems.
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This thesis aims to extend the current failure model by considering piping as a time-dependent erosion process instead of the current assumption of immediate failure once a critical threshold is exceeded. Therefore, it is shown how time-dependent development of backward erosion piping can be quantified and how it affects levee reliability analyses. This is achieved by a combination of literature review, analysis of previous experiments, additional experiments on different scales, numerical modeling and probabilistic modeling.
The following key findings were established. Analysis of historical levee failures due to BEP and previous experiments indicates that there can be significant time between initiation and breach, highlighting the importance of time-dependence for piping. The rate of pipe progression in experiments can be explained by the sediment transport rate, which is shown to depend on the pipe flow conditions. A numerical groundwater flow model which includes this sediment transport process can predict the pipe development in small-scale experiments. Relations between the progression rate and levee properties and hydraulic loads as derived with this numerical model can be used efficiently in reliability analyses. These analyses show that including time-dependent pipe development in BEP analyses has a significant impact on the levee failure probability, both in coastal and riverine water systems.
...
Structural flood protection systems such as levees are an important component in flood risk reduction strategies. Levees can fail through various failure mechanisms; this thesis focuses on the mechanism Backward Erosion Piping (BEP) which occurs when a sandy levee foundation is eroded by groundwater flow. To assess whether a levee's reliability complies with safety standards, authorities use models which describe the levee properties and failure mechanisms.
This thesis aims to extend the current failure model by considering piping as a time-dependent erosion process instead of the current assumption of immediate failure once a critical threshold is exceeded. Therefore, it is shown how time-dependent development of backward erosion piping can be quantified and how it affects levee reliability analyses. This is achieved by a combination of literature review, analysis of previous experiments, additional experiments on different scales, numerical modeling and probabilistic modeling.
The following key findings were established. Analysis of historical levee failures due to BEP and previous experiments indicates that there can be significant time between initiation and breach, highlighting the importance of time-dependence for piping. The rate of pipe progression in experiments can be explained by the sediment transport rate, which is shown to depend on the pipe flow conditions. A numerical groundwater flow model which includes this sediment transport process can predict the pipe development in small-scale experiments. Relations between the progression rate and levee properties and hydraulic loads as derived with this numerical model can be used efficiently in reliability analyses. These analyses show that including time-dependent pipe development in BEP analyses has a significant impact on the levee failure probability, both in coastal and riverine water systems.
This thesis aims to extend the current failure model by considering piping as a time-dependent erosion process instead of the current assumption of immediate failure once a critical threshold is exceeded. Therefore, it is shown how time-dependent development of backward erosion piping can be quantified and how it affects levee reliability analyses. This is achieved by a combination of literature review, analysis of previous experiments, additional experiments on different scales, numerical modeling and probabilistic modeling.
The following key findings were established. Analysis of historical levee failures due to BEP and previous experiments indicates that there can be significant time between initiation and breach, highlighting the importance of time-dependence for piping. The rate of pipe progression in experiments can be explained by the sediment transport rate, which is shown to depend on the pipe flow conditions. A numerical groundwater flow model which includes this sediment transport process can predict the pipe development in small-scale experiments. Relations between the progression rate and levee properties and hydraulic loads as derived with this numerical model can be used efficiently in reliability analyses. These analyses show that including time-dependent pipe development in BEP analyses has a significant impact on the levee failure probability, both in coastal and riverine water systems.
Hoogwater 2021
Feiten en Duiding
Report
(2021)
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J. Schlumberger, M. van Haren, D. Wüthrich, undefined More authors, Guus Rongen, Bart Strijker, Joost Pol, Matthijs Kok, Bas Kolen, Stephan Rikkert, Roelof Moll, Kymo Slager, Sebastiaan N. Jonkman
In juli 2021 zijn grote delen van Limburg getroffen door hevige regenval en overstromingen. Ook delen van België en Duitsland overstroomden met zeer veel schade en verlies aan mensenlevens tot gevolg. Dit betrof een extreme en ongeëvenaarde gebeurtenis met enorme impact. Daarom is naar aanleiding van de overstromingen deze verkenning uitgevoerd om een eerste stap te maken om beschikbare informatie over deze gebeurtenis te verzamelen en analyseren. Het onderzoek is uitgevoerd door een breed consortium (TU Delft, Deltares, HKV Lijn in Water, VU Amsterdam, Universiteit Utrecht, KNMI, WUR, Erasmus MC en Universiteit Twente) in opdracht van het Expertise Netwerk Waterveiligheid (ENW). Een overstroming heeft effect op de hele maatschappij. Daarom zijn niet alleen hydrologische en civieltechnische onderwerpen beschouwd, maar ook de maatschappelijke gevolgen van overstromingen, de crisisrespons en de gezondheidseffecten.
Contributors (in alphabetical order):
Nathalie Asselman (Deltares), Hermjan Barneveld (HKV / Wageningen UR), Jules Beersma (KNMI), Eline Boelee (Deltares), Wouter Botzen (VU Amsterdam), Eefke Copper (TU Delft), Dim Coumou (KNMI), Karin de Bruijn (Deltares), Anniek de Jong (Deltares), Jurjen de Jong (Deltares), Hans de Moel (VU Amsterdam), Ferdinand Diermanse (Deltares), Astrid Fischer (Evides) , Gert-Jan Geerling (Deltares), Marie-Louise Geurts (WML), Rob Groenland (KNMI), Mark Hegnauer (Deltares), Bas Jonkman (TU Delft), Nicole Jungermann (KNMI), Frans Klijn (Deltares), Andre Koelewijn (Deltares), Matthijs Kok (HKV / TU Delft), Elco Koks (VU Amsterdam), Bas Kolen (HKV / TU Delft), Marion Koopmans (Erasmus MC), Laurens Leunge (Deltares), Hans Middelkoop (Utrecht University), Roelof Moll (TU Delft), Jaap Mos (Dunea), Sjoukje Philip (KNMI), Gerbert Pleijter (HKV), Joost Pol (HKV / TU Delft), Stephan Rikkert (TU Delft), Guus Rongen (TU Delft), Rinus Scheele (KNMI), Julius Schlumberger (TU Delft), Peter Siegmund (KNMI), Kymo Slager (Deltares), Frederiek Sperna Weiland (Deltares), Bart Strijker (HKV / TU Delft), Henk v.d. Brink (KNMI), Janko van Beek (Erasmus MC), Marion van den Bulk (TU Delft), Bart van den Hurk (Deltares), Tim van Emmerik (Wageningen UR), Kees van Ginkel (VU Amsterdam / Deltares), Mick van Haren (TU Delft), Margreet van Marle (Deltares), Malou van Schaijk (TU Delft), Dennis Wagenaar (Nanyang TU), Davide Wüthrich (TU Delft) ...
Contributors (in alphabetical order):
Nathalie Asselman (Deltares), Hermjan Barneveld (HKV / Wageningen UR), Jules Beersma (KNMI), Eline Boelee (Deltares), Wouter Botzen (VU Amsterdam), Eefke Copper (TU Delft), Dim Coumou (KNMI), Karin de Bruijn (Deltares), Anniek de Jong (Deltares), Jurjen de Jong (Deltares), Hans de Moel (VU Amsterdam), Ferdinand Diermanse (Deltares), Astrid Fischer (Evides) , Gert-Jan Geerling (Deltares), Marie-Louise Geurts (WML), Rob Groenland (KNMI), Mark Hegnauer (Deltares), Bas Jonkman (TU Delft), Nicole Jungermann (KNMI), Frans Klijn (Deltares), Andre Koelewijn (Deltares), Matthijs Kok (HKV / TU Delft), Elco Koks (VU Amsterdam), Bas Kolen (HKV / TU Delft), Marion Koopmans (Erasmus MC), Laurens Leunge (Deltares), Hans Middelkoop (Utrecht University), Roelof Moll (TU Delft), Jaap Mos (Dunea), Sjoukje Philip (KNMI), Gerbert Pleijter (HKV), Joost Pol (HKV / TU Delft), Stephan Rikkert (TU Delft), Guus Rongen (TU Delft), Rinus Scheele (KNMI), Julius Schlumberger (TU Delft), Peter Siegmund (KNMI), Kymo Slager (Deltares), Frederiek Sperna Weiland (Deltares), Bart Strijker (HKV / TU Delft), Henk v.d. Brink (KNMI), Janko van Beek (Erasmus MC), Marion van den Bulk (TU Delft), Bart van den Hurk (Deltares), Tim van Emmerik (Wageningen UR), Kees van Ginkel (VU Amsterdam / Deltares), Mick van Haren (TU Delft), Margreet van Marle (Deltares), Malou van Schaijk (TU Delft), Dennis Wagenaar (Nanyang TU), Davide Wüthrich (TU Delft) ...
In juli 2021 zijn grote delen van Limburg getroffen door hevige regenval en overstromingen. Ook delen van België en Duitsland overstroomden met zeer veel schade en verlies aan mensenlevens tot gevolg. Dit betrof een extreme en ongeëvenaarde gebeurtenis met enorme impact. Daarom is naar aanleiding van de overstromingen deze verkenning uitgevoerd om een eerste stap te maken om beschikbare informatie over deze gebeurtenis te verzamelen en analyseren. Het onderzoek is uitgevoerd door een breed consortium (TU Delft, Deltares, HKV Lijn in Water, VU Amsterdam, Universiteit Utrecht, KNMI, WUR, Erasmus MC en Universiteit Twente) in opdracht van het Expertise Netwerk Waterveiligheid (ENW). Een overstroming heeft effect op de hele maatschappij. Daarom zijn niet alleen hydrologische en civieltechnische onderwerpen beschouwd, maar ook de maatschappelijke gevolgen van overstromingen, de crisisrespons en de gezondheidseffecten.
Contributors (in alphabetical order):
Nathalie Asselman (Deltares), Hermjan Barneveld (HKV / Wageningen UR), Jules Beersma (KNMI), Eline Boelee (Deltares), Wouter Botzen (VU Amsterdam), Eefke Copper (TU Delft), Dim Coumou (KNMI), Karin de Bruijn (Deltares), Anniek de Jong (Deltares), Jurjen de Jong (Deltares), Hans de Moel (VU Amsterdam), Ferdinand Diermanse (Deltares), Astrid Fischer (Evides) , Gert-Jan Geerling (Deltares), Marie-Louise Geurts (WML), Rob Groenland (KNMI), Mark Hegnauer (Deltares), Bas Jonkman (TU Delft), Nicole Jungermann (KNMI), Frans Klijn (Deltares), Andre Koelewijn (Deltares), Matthijs Kok (HKV / TU Delft), Elco Koks (VU Amsterdam), Bas Kolen (HKV / TU Delft), Marion Koopmans (Erasmus MC), Laurens Leunge (Deltares), Hans Middelkoop (Utrecht University), Roelof Moll (TU Delft), Jaap Mos (Dunea), Sjoukje Philip (KNMI), Gerbert Pleijter (HKV), Joost Pol (HKV / TU Delft), Stephan Rikkert (TU Delft), Guus Rongen (TU Delft), Rinus Scheele (KNMI), Julius Schlumberger (TU Delft), Peter Siegmund (KNMI), Kymo Slager (Deltares), Frederiek Sperna Weiland (Deltares), Bart Strijker (HKV / TU Delft), Henk v.d. Brink (KNMI), Janko van Beek (Erasmus MC), Marion van den Bulk (TU Delft), Bart van den Hurk (Deltares), Tim van Emmerik (Wageningen UR), Kees van Ginkel (VU Amsterdam / Deltares), Mick van Haren (TU Delft), Margreet van Marle (Deltares), Malou van Schaijk (TU Delft), Dennis Wagenaar (Nanyang TU), Davide Wüthrich (TU Delft)
Contributors (in alphabetical order):
Nathalie Asselman (Deltares), Hermjan Barneveld (HKV / Wageningen UR), Jules Beersma (KNMI), Eline Boelee (Deltares), Wouter Botzen (VU Amsterdam), Eefke Copper (TU Delft), Dim Coumou (KNMI), Karin de Bruijn (Deltares), Anniek de Jong (Deltares), Jurjen de Jong (Deltares), Hans de Moel (VU Amsterdam), Ferdinand Diermanse (Deltares), Astrid Fischer (Evides) , Gert-Jan Geerling (Deltares), Marie-Louise Geurts (WML), Rob Groenland (KNMI), Mark Hegnauer (Deltares), Bas Jonkman (TU Delft), Nicole Jungermann (KNMI), Frans Klijn (Deltares), Andre Koelewijn (Deltares), Matthijs Kok (HKV / TU Delft), Elco Koks (VU Amsterdam), Bas Kolen (HKV / TU Delft), Marion Koopmans (Erasmus MC), Laurens Leunge (Deltares), Hans Middelkoop (Utrecht University), Roelof Moll (TU Delft), Jaap Mos (Dunea), Sjoukje Philip (KNMI), Gerbert Pleijter (HKV), Joost Pol (HKV / TU Delft), Stephan Rikkert (TU Delft), Guus Rongen (TU Delft), Rinus Scheele (KNMI), Julius Schlumberger (TU Delft), Peter Siegmund (KNMI), Kymo Slager (Deltares), Frederiek Sperna Weiland (Deltares), Bart Strijker (HKV / TU Delft), Henk v.d. Brink (KNMI), Janko van Beek (Erasmus MC), Marion van den Bulk (TU Delft), Bart van den Hurk (Deltares), Tim van Emmerik (Wageningen UR), Kees van Ginkel (VU Amsterdam / Deltares), Mick van Haren (TU Delft), Margreet van Marle (Deltares), Malou van Schaijk (TU Delft), Dennis Wagenaar (Nanyang TU), Davide Wüthrich (TU Delft)
Progression Rate of Backward Erosion Piping
Small Scale Experiments
Conference paper
(2021)
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J.C. Pol, W. van Klaveren, W. Kanning, V.M. van Beek, B. Robbins, Sebastiaan N. Jonkman
Most research on backward erosion piping (BEP) focuses on the critical conditions leading to failure. This paper studies the development of piping over time once the critical conditions are exceeded, which is useful to estimate time to failure. A commonly used small scale rectangular box setup is modified in order to monitor pore pressures and pipe pressures with a high spatial and temporal resolution. The experimental program includes three different sand types to study the effects of grain size and compaction, and different degrees of hydraulic loading. The results indicate that the transport of particles in the pipe affects the progression rate, and that the progression rate is related to the bed shear stress in the pipe.
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Most research on backward erosion piping (BEP) focuses on the critical conditions leading to failure. This paper studies the development of piping over time once the critical conditions are exceeded, which is useful to estimate time to failure. A commonly used small scale rectangular box setup is modified in order to monitor pore pressures and pipe pressures with a high spatial and temporal resolution. The experimental program includes three different sand types to study the effects of grain size and compaction, and different degrees of hydraulic loading. The results indicate that the transport of particles in the pipe affects the progression rate, and that the progression rate is related to the bed shear stress in the pipe.
This paper presents a large-scale backward erosion piping experiment aimed at studying the erosion rate. This temporal aspect of piping complements previous research that focused on the critical head. To study the progression rate in realistic conditions, an experiment was carried out on a 1.8 m high levee with a cohesive blanket on a sandy foundation. The pipe was guided along a row of pore pressure transducers in order to measure its temporal development. Pipe development in space and time was successfully derived from pore pressure changes, showing an average progression rate of 8 m/day during the progressive erosion phase. The results show a relation between upstream gradient and progression rate. Furthermore, analysis of the eroded sand mass shows a relatively large pipe volume compared to existing lab tests, and an approximately linear relation between pipe length and volume. The results and insights from this study can be used to validate and improve transient piping models, leading to more accurate dam and levee safety assessments.
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This paper presents a large-scale backward erosion piping experiment aimed at studying the erosion rate. This temporal aspect of piping complements previous research that focused on the critical head. To study the progression rate in realistic conditions, an experiment was carried out on a 1.8 m high levee with a cohesive blanket on a sandy foundation. The pipe was guided along a row of pore pressure transducers in order to measure its temporal development. Pipe development in space and time was successfully derived from pore pressure changes, showing an average progression rate of 8 m/day during the progressive erosion phase. The results show a relation between upstream gradient and progression rate. Furthermore, analysis of the eroded sand mass shows a relatively large pipe volume compared to existing lab tests, and an approximately linear relation between pipe length and volume. The results and insights from this study can be used to validate and improve transient piping models, leading to more accurate dam and levee safety assessments.
Backward erosion piping is an important failure mode of dikes and dams. The time required for the backward erosion process to result in dike failure is expected to be an important factor in the safety of dikes. This holds especially in coastal and estuarine areas which are dominated by storm surge, and pipes may not fully develop during a storm. Furthermore, insight in the duration of the various piping stages can assist in developing effective emergency mitigation measures. However, the temporal development of piping is hardly studied quantitatively, as most experimental and modelling studies focus on the critical head. Also data of real breaches is generally insufficient to determine the time to failure. As a result, currently the contribution of time required for pipe growth cannot be quantified in a deterministic and reliability analysis. In this study, it is investigated how the pipe progression rate can be predicted and applied to dike reliability. The data analysis is based on a composition of 45 small, medium and large scale experiments from six studies. Advancement rates are related to the applied hydraulic gradient and soil properties using a multivariate analysis. From the analysis we derive an empirical model for the advancement rate, including a quantification of the uncertainty. This model is applied in a reliability analysis of a hypothetical coastal and riverine dike. The results of our analysis may be used to validate transient numerical piping models, perform time-dependent probabilistic dike safety analysis and support emergency response.
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Backward erosion piping is an important failure mode of dikes and dams. The time required for the backward erosion process to result in dike failure is expected to be an important factor in the safety of dikes. This holds especially in coastal and estuarine areas which are dominated by storm surge, and pipes may not fully develop during a storm. Furthermore, insight in the duration of the various piping stages can assist in developing effective emergency mitigation measures. However, the temporal development of piping is hardly studied quantitatively, as most experimental and modelling studies focus on the critical head. Also data of real breaches is generally insufficient to determine the time to failure. As a result, currently the contribution of time required for pipe growth cannot be quantified in a deterministic and reliability analysis. In this study, it is investigated how the pipe progression rate can be predicted and applied to dike reliability. The data analysis is based on a composition of 45 small, medium and large scale experiments from six studies. Advancement rates are related to the applied hydraulic gradient and soil properties using a multivariate analysis. From the analysis we derive an empirical model for the advancement rate, including a quantification of the uncertainty. This model is applied in a reliability analysis of a hypothetical coastal and riverine dike. The results of our analysis may be used to validate transient numerical piping models, perform time-dependent probabilistic dike safety analysis and support emergency response.
Apart from the soil erodibility parameter, the critical shear stress is the most important parameter in predicting erosion rates. On the basis of experiments several empirical formulas have already been de-veloped which relate the critical shear stress to soil properties. Based on these findings and supported by new large scale experiments, a new predictive relation between the critical shear stress and soil properties is proposed here. In support of this study, Delft University of Technology collaborated with Saitama University in the preparation and execution of a large scale levee erosion experiment in Janu-ary 2019. The erosion experiments were performed in the on a 1.8m high levee with a sand core and respectively clay and loam cover types. The cover types were subjected to a constant overflow dis-charge of approximately 70 l/m/s. The test levee was constructed in the Flood Proof Holland test pol-der in Delft, The Netherlands. During the experiment, time lapse measurements of the erosion depth were obtained at 15 locations along the landside slope. Before and after overflow tests were performed on each cover type, soil samples were collected along the landside slope at 8 locations. This paper out-lines how these large experiments were used to evaluate the effectiveness and application limit of the new predictive equation for the critical shear stress. A comparison between the predicted and meas-ured erosion rates shows that by applying the new empirical relation for the critical shear stress, meas-ured erosion rates could be predicted around ±30 % errors.
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Apart from the soil erodibility parameter, the critical shear stress is the most important parameter in predicting erosion rates. On the basis of experiments several empirical formulas have already been de-veloped which relate the critical shear stress to soil properties. Based on these findings and supported by new large scale experiments, a new predictive relation between the critical shear stress and soil properties is proposed here. In support of this study, Delft University of Technology collaborated with Saitama University in the preparation and execution of a large scale levee erosion experiment in Janu-ary 2019. The erosion experiments were performed in the on a 1.8m high levee with a sand core and respectively clay and loam cover types. The cover types were subjected to a constant overflow dis-charge of approximately 70 l/m/s. The test levee was constructed in the Flood Proof Holland test pol-der in Delft, The Netherlands. During the experiment, time lapse measurements of the erosion depth were obtained at 15 locations along the landside slope. Before and after overflow tests were performed on each cover type, soil samples were collected along the landside slope at 8 locations. This paper out-lines how these large experiments were used to evaluate the effectiveness and application limit of the new predictive equation for the critical shear stress. A comparison between the predicted and meas-ured erosion rates shows that by applying the new empirical relation for the critical shear stress, meas-ured erosion rates could be predicted around ±30 % errors.