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Full-scale field validation of innovative dike monitoring systems
Validation de systèmes de surveillance innovants pour digues à grande échelle
Koelewijn A.R., Vries (de) G.
Deltares
Lottum van H.
IJkdijk Foundation & Deltares
ABSTRACT: Three large scale field tests on dikes have been carried out at the IJkdijk test site in the Netherlands. Two tests involved
piping, micro-instability of the sand core and erosion from overtopping. Both dikes failed on micro-instability. The third test involved
slope stability with a deep sliding plane. All tests were done to validate monitoring systems and dike safety information systems.
Several systems performed well.
RÉSUMÉ : Trois essais à grande échelle sur digues sont exécutés sur le site de l’Ijkdijk aux Pays-Bas. Deux essais étaient concernés
par un phénomène de renard, de déstabilisation par fluidisation de sable du cœur de la digue et d’érosion par surverse. Ces digues
s’éffondraient par fluidisation de sable. Le troisième essai impliquait le mode de rupture de pente. Tous les essais ont été effectués
pour valider les systèmes de surveillance des digues. Plusieurs systèmes ont donné de bons résultats.
KEYWORDS: dike, embankment, full-scale test, slope stability, piping, microinstability, monitoring, information systems.
1 INTRODUCTION TO THE IJKDIJK TESTS
1.1
The IJkdijk research program
The IJkdijk (Dutch for ‘calibration dike’) is a Dutch research
program with the two-fold aim to test any kind of sensors for
the monitoring of levees under field conditions and to increase
the knowledge on dike failure mechanisms.
Since 2007, several purpose-built dikes have been brought to
failure at the IJkdijk test site at Booneschans, in the North-East
of the Netherlands. Past experiments include a large stability
test (Zwanenburg et al. 2012) and four field tests on backward
seepage erosion or piping (van Beek et al. 2011). The tests
presented in this article include these and other failure modes.
For the near future, a test on static liquefaction is planned.
Meanwhile, the outcome of these tests has been implemented
in practice by instrumenting several regular dikes, i.e.
embankments with the function to protect the hinterland against
flooding. By the end of 2012, this advanced surveillance by
sensor equipment had been placed in ten different dikes in the
Netherlands, United Kingdom, Germany and China.
1.2
All-in-One Sensor Validation Test
The main purpose of the All-in-One Sensor Validation Test
(AIO-SVT) was to test the predictive power of full-service dike
sensor systems, i.e. sensor in and on dikes combined with data
processing and an information system providing a timely,
reliable warning in case failure may occur. The application of
such systems into practice will be a major improvement to the
current state-of-the-art of dike management. In addition,
contributing sensor systems were also tested and validated on
their own. Another reason to carry out this test, in accordance
with the two-fold aim of the IJkdijk,is to learn more on dike
failure mechanisms, including failure prevention methods.
The AIO-SVT involved three dikes, which were all brought
to failure. First, the geotechnical design of each dike is
described, followed by the instrumentation. Next, the results are
described, first regarding the failures of the dikes, then for the
monitoring systems and finally for the information systems.
Finally, conclusions are drawn.
2 DESIGN OF THE EXPERIMENTS
The experiments were designed in such a way that each dike
could fail to different failure modes. The duration of each
experiment was planned to be at least several days, with a
maximum of one week, to allow the participating companies to
collect a reasonable amount of data under varying conditions.
2.1
West and East dikes
The West and East dikes, named after their respective locations
on the test site, were in many ways comparable. Both test dikes
were 3.5m high, 15m long and 15m wide at their base, see
Figure 1. The lower part of each dike was made of a 0.7m well-
compacted clay layer, with a 1.7m high less-compacted small
clay dike at the upstream side on top, a sand core behind this
small clay dike and a cover of organic clay. This composition is
found in many smaller dikes around the country. The base
consisted of a uniform sand with a thickness of 3m with an
impermeable foil below, to separate this test layer from the
subsoil. Under the West dike, the sand has a d
50
of 0.296mm
and a uniformity coefficient U=d
60
/d
10
of 1.69. Under the East
dike, the d
50
is 0.180mm and U=1.73. The upstream reservoir is
enclosed by a 3.7m high dike. The size of the reservoir is about
2000m
3
.
By design, failure could occur from piping through the base,
micro-instability of the sand core and overtopping of the crest
Figure 1. Cross-section of West and East dikes.
