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Full-scale field validation of innovative dike monitoring systems


A new equilibrium model for arching in basal reinforced piled embankments

12 A.R. Koelewijn / ing. G. de Vries / ing. H. van Lottum

ir. S.J.M. van Eekelen / ir. A. Bezuijen

Some special technics used in the North-South Line ir. G.A. van Zwieten


Magic on a square foot ir. B.J. Admiraal

16 18

Seismic ground prediction system on a tunnel boring machine ing. R. Reijnen / G. Drijkoningen

Construction of the new A74 motorway at Venlo (NL)

Geosynthetic Reinforced Earth (GRE) used as bridge abutment and soil pressure relief ing. C.A.J.M. Brok / dipl.-ing. O. Detert


Stabilisation of unbound granular layers – reinforcement required? dipl.-ing. L. Vollmert / dipl.-ing. C. Psiorz

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Full-scale field validation of innovative dike monitoring systems A.R. Koelewijn Specialist R&D Deltares

ing. G. de Vries Geotechnical Consultant Deltares

ing. H. van Lottum Senior Geotechnical Consultant, Deltares

All illustrations are property of Deltares.

tion of soft peat and clay. After construction, it was 4m high, 50m long at crest level, with a crest width of 3m and side slopes of 1:1.5 (V:H). The core was made of sand, with a 0.5m thick clay layer. Figure 2 shows a cross-section of the dike at the start of the test, i.e. after consolidation resulting in a settlement of 0.99m.

Figure 1 - Cross-section of South dike at start of test, showing settled geometry and indicating positions of reference monitoring.

Introduction 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. 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 proces-

sing 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 one of the dikes is described, viz the South dike, followed by its instrumentation. Next, the results are described, first regarding the failure of the dike, then for the monitoring systems and for the information systems. Finally, conclusions are drawn. The full experiment, including the other two test dikes, is described in Koelewijn et al. (2013).

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. The South dike was built on a 4.5m thick composi-



The designed failure modes of this dike were slope stability with a deep sliding plane through the subsoil with a minimum deformation of 20cm and rupture of the clay cover by high pore pressures inside the sand core as a result of saturating this core with water.

Instrumentation For the instrumentation a clear distinction is made between the reference monitoring and the instruments of the participating companies. The reference monitoring was required to closely monitor the course of the tests, while the other instruments were validated and the measurements were used to make updated predictions of the failures. A total of nine companies participated with their instruments – some in all tests, others in only one or two. Each of these companies were invited to use their own measurements to give an initial prediction of the failure mode and the conditions at which failure would occur, and to update this prediction at least every 24 hours. Three companies providing dike safety information systems participated in all three tests. These companies had access to the data of the monitoring systems being validated through a central data base. The data of the reference monitoring was not disclosed during the tests. The reference monitoring at the South dike consisted of 34 pore pressure meters and six automatic inclinometers. Twenty-six pore pressure meters were installed in two cross-sections each 13m from the centre line, as indicated in figure 2, six pore pressure meters were installed in six water tanks

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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. The failure process of this dike is analysed in some detail. All tests were done to validate monitoring systems and dike safety information systems. Several systems performed well.

Figure 3 - South dike during failure: fracturing of slope of ditch. Table 2 - Horizontal deformations measured by inclinometers around failure, in mm. Time

Figure 2 - Horizontal displacements at toe of dike until close to failure. Table 1 - Safety factors calculated for the South dike. Situation Dike completed Start of test

Date & Time


East in toe

Middle - crest

Middle in berm

West in berm

West in toe 135

1:53 pm





2:13 pm






2:27 pm






2:30 pm







June 26, 5:00 pm

1.46 1.50

Sept. 3, 12:12 pm

1.74 1.82

Before last excavation

Sept. 5, 9:00 am

1.24 1.38

After last excavation

Sept. 5, 5:00 pm

1.05 1.08

Start of last infiltration

Sept. 8,1:53 pm

1.01 1.05

Max. pore pressures

Sept. 8, 2:13 pm

0.92 0.95

Visible failure

Sept. 8, 2:27 pm

0.94 0.98

on top of the crest and the remaining two were installed in the basin on the non-failing side of the dike and in the ditch which was excavated during the test to reduce the overall stability. The inclinometers were distributed along the centre line and both instrumented cross-sections. The seven companies participating in this test installed the following equipment: - glass fibre optics woven into geotextile, measuring temperature and strain approximately every metre in three parallel lines along the whole length of the dike, on ground level and on two higher levels; - a system of six extremely accurate inclination instruments, each mounted on top of a 5.6m steel rod placed on the slope of the dike (three on the side of the failure, three on the other side); - a Fast Ground Based Synthetic Aperture Radar system, measuring a two-dimensional displacement field of the slope at the side of the failure

every five seconds; - a total of four tubes measuring temperature and strain profiles over depth employing glass fibre optics: two vertical tubes 5.5m long halfway the slope at the side of the failure, one vertical tube 3.5m long at the toe at the same side in the centre line and one horizontal tube along the whole toe of the dike; - a thermic infrared camera facing the downstream slope, with a resolution of 640x480 pixels and an accuracy of 0.05 K; - one controllable drainage tubes with measurements of pore pressure, temperature and discharge, located inside the sand core, close to the toe at the side of the failure; - eight instruments measuring pore pressure, temperature and local inclination distributed over two cross-sections 10m away from the centre line, in each cross-section one instrument in the sand core close to the toe and three instruments distributed over depth in the soft soil deposits under the toe.

Results of the test The test on the South dike started on September 3rd at 12:12 pm, by the infiltration of water into the sand core. The next day, a small excavation was made in front of the dike. This had a limited effect on the dike, as shown in figure 2 by the horizontal displacements at the toe of the dike. The next day, a final excavation was made and on the basis of slope stability calculations it was decided to



continue by hydraulic loading only. In order to acquire a lot of measurement data, several days were taken to raise the phreatic surface in the sand core and to fill the water tanks on top. Finally, failure occurred on September 8th, at 2:27 pm, after 122.26 hours, see Figure 3. Table 1 shows the results of slope stability calculations at characteristic moments applying the models of Bishop (1955) and Van (2001). The latter is a geometrically more flexible variant to Bishop’s model. The results correspond well to the deformation behaviour shown in figure 2: close to the critical value of 1, the deformations quickly increase. These results may even draw some suspicion, but it should be borne in mind that quite advanced soil investigations had been carried out prior to the test (Zwanenburg et al. 2011, Koelewijn and Bennett 2012) and detailed actual measurements of pore pressures were available. Moreover, the model by Bishop has already long ago been described as surprisingly accurate for conditions close to failure (Spencer 1967). Table 2 gives the measured values of the horizontal deformations during the last phase of the test for all inclinometers except one at the East side, which failed. The pre-set deformation criterion for a successful test was exceeded at the moment the maximum pore pressures were recorded.

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Performance of the monitoring systems All monitoring systems were judged by their accuracy, range, density of measurements, measurement frequency, redundancy, robustness, time to install and adjust, processing time, interpretation and quality of prediction. Note that several of these factors are not only influenced by the instrumentation, but also by the strategy adopted by the company. It should also be noted that successful application of any technique depends on the actual conditions and environment. An extensive evaluation of the results by the above criteria indicated a good to excellent performance in this test of the tubes measuring strain and temperature profiles (the design could still be improved, however) and the ground based SAR (robustness to field conditions could be improved). The other systems performed as expected or worse.

Performance of the information systems The information systems were judged by their ability to combine data of different sources, the application of various techniques and methods to arrive at meaningful information, the clarity of statements and the quality of prediction. Two companies performed well, one employing advanced data driven modelling and anomaly detec-

tion to improve finite element calculations, the other one focusing more on an engineer’s approach employing both modern technology and visual observations to update their predictions during the test. The third company restricted its efforts mainly to producing all kinds of graphical presentations of the measured data, but hardly combining data of different sources.

Conclusions The South dike failed according to one of the designed failure modes. Instrumentation of seven companies was tested here, including a novel technique to measure strain and temperature and fast ground based SAR as promising new monitoring techniques. Employing monitoring data led to an improvement of the prediction of failure, especially if different types of monitoring were used. It appeared that real-time advanced modelling further improves the knowledge on the actual and expected condition of dikes.


References – Beek, V.M. van, Knoeff, H. and Sellmeijer, H. 2011. Observations on the process of backward erosion piping in small-, medium- and full-scale experiments, European Journal of Environmental and Civil Engineering 15(8), 1115-1137. – Bishop, A.W. 1955. The use of the slip circle in the stability analysis of slopes. Géotechnique 5 (1), 7-17. – Koelewijn, A.R. and Bennett, V.G. 2012. Levee failure prediction competition 2012, – Koelewijn, A.R., Vries, G. de & Lottum, H. van 2013. Full-scale field validation of innovative dike monitoring systems, Proc. 18th Int. Conf. Soil Mech. Geot. Eng., Paris. – Spencer, E. 1967. A method of analysis of the stability of embankments assuming parallel inter-slice forces, Géotechnique 17(1), 11-26. – Van, M.A. 2001. New approach for uplift induced slope failure, Proc. XVth Int. Conf. Soil Mech. Geot. Eng., Istanbul, 2285-2288. – Zwanenburg, C., Haan, E.J. den, Kruse, G.A.M. and Koelewijn, A.R. 2012. Failure of a trial embankment on peat in Booneschans, the Netherlands. Géotechnique 62 (6), 479-490. 쎲

Acknowledgements are made to Staatsbosbeheer for providing the test site at Booneschans, the Dutch Ministry of Economic Affairs, Agriculture and Innovation for the financial support and all participating companies for their efforts.

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N55 GEO Special_Opmaak 1 17-07-13 16:06 Pagina 9

A new equilibrium model for arching in basal reinforced piled embankments

Figure 1 – Calculating the geosynthetic reinforcement (GR) strain comprises two calculation steps.

Design of basal reinforced piled embankments Many analytical design models for the design of piled embankments distinguish two calculation steps. Step 1 is the arching behaviour in the fill. This “arching step” divides the total vertical load into two parts: load part A, and the ‘rest load’ (B+C in figure 1). Load part A, also called the ‘arching’, is the part of the load that is transferred to the piles directly. Calculation step 2 describes the load-deflection behaviour of the geosynthetic reinforcement (GR) (see figure 1). In this calculation step, the ‘rest load’ is applied to the GR strip between each two adjacent piles, and the GR strain is calculated. An implicit result of step 2 is that the ‘rest load’ is further divided into load part B, which goes through the GR to the piles, and part C, resting on the subsoil, as indicated in figure 1. This paper focuses on calculation step 1 only and thus on the determination of the load distribution in the load transfer platform. The two most interesting results of the arching step are: 1. The calculated value for the arching A (kN/pile) 2. The load distribution of B+C (kN/pile)

Van Eekelen et al. (2012a, b and 2013a, b) showed that introducing a GR in a piled embankment results in a more efficient transfer of load to the piles in the form of an arching mechanism. The load B+C is then concentrated on the GR strips between each two adjacent piles, and the load distribution on these strips approaches the inversed triangular shape, as shown in figure 1 (right hand side of the figure). The concentration of load on the strips between the piles is only found for GR basal reinforced piled embankments, not for piled embankments without GR. Therefore, it is necessary to make a distinction between arching models for piled embankment with and without GR. This paper focuses on GR reinforced piled embankments only.

Equilibrium models describing arching In equilibrium models, an imaginary limit-state stress-arch is assumed to appear above the void (in this case the GR) between stiff elements. In the 3D situation these stiff elements are piles, in the 2D situation they are walls. The pressure on the GR is calculated by considering the equilibrium of the arch. In most models, the arch has a thickness.

ir. S.J.M. van Eekelen Deltares, Unit Geo-Engineering and Delft University of Technology, Netherlands

ir. A. Bezuijen Ghent University, Belgium and unit Geo-Engineering Deltares, Netherlands

The model of Hewlett and Randolph (1988, see figure 2) is adopted in the French ASIRI guideline (2012) and suggested in BS8006 (2010) as an alternative for the originally empirical model in BS8006. Another frequently applied equilibrium model is the model of Zaeske (2001, also described in Kempfert, 2004). See figure 3. This model is adopted in the German EBGEO (2010) and the Dutch CUR226 (2010), and is hereafter called EBGEO. Both models are further explained in Van Eekelen and Bezuijen (2013c) and calculate the pressure on the subsurface below the arches in one point. They then assume that this pressure is the same everywhere between the piles, resulting in an equally distributed pressure on the GR. Figure 4 shows a new model, which is the concentric arches model presented by Van Eekelen et al. (2013b). It is an extension of Zaeske (2001) and Hewlett and Randolph (1988).

Concentric Arches In the concentric arches model, 3D concentric arches (hemispheres) occur above the square between each four piles (Figure 4). These hemispheres exert part of the load to their subsurface, the GR square between the four piles. The rest of the load is transported laterally in the direction of the GR strips. The load is then further transported along the 2D arches, in the direction of the pile caps. The 2D arches also exert part of the load to their subsurface (the GR strips). Thus, both the 3D hemispheres and the 2D arches exert a load on its GR subsurface, and this exerted force increases towards the exterior. The part of the load not resting on the GR is the load on the piles (arching A). Following Hewlett and Randolph (1988), the radial stress Ȝr and tangential stress Ȝᒕ in the 2D

Abstract Several analytical models are available for describing arching in basal reinforced piled embankments. Between them are limit state equilibrium models. Two of them are frequently applied in Europe. One of them is the model of Zaeske (2001). The other model is the model of Hewlett and Randolph (1988). This paper consi-


ders these two models along with a new model: the Concentric Arches Model (Van Eekelen et al. 2013b). This model is an extension of the first two models. The paper gives a graphical presentation of the three models and validates them with numerical calculations and field measurements.


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and 3D arches are calculated by assuming radial equilibrium of the crown element and assuming that: – The principal stresses follow the arches with Ȝᒕ the major principal stress and Ȝr the minor principal stress. – The arches are in a nearly-plastic situation:

Figure 2 – Hewlett & Randolph (1988) consider the ‘crown’ element of the 3D hemisphere, resulting in Acrown and the ‘toe’ element (just above the pile cap) of the plane strain arch, resulting in Atoe, as indicated in this figure. The lowest A is normative.

Where Kp (-) is the Rankine passive earth pressure coefficient and ᒌ (o) is the friction angle. The forces exerted on the subsurface (the GR) are calculated by integrating the tangential stress over the GR area. This is fully elaborated and presented in Van Eekelen et al. (2013b). The resulting load distribution in figure 5 shows that the load is indeed concentrated on the GR strips, and the load distribution on the GR strips indeed approaches the inversed triangular load distribution found earlier in model tests, numerical analysis and field measurements (Van Eekelen et al., 2012a, b and 2013a).

Results and discussion Both Hewlett and Randolph (1988) and Zaeske (2001) determine the pressure exerted on the GR at the central point between four piles only. They continue with assuming that the entire GR area is loaded with this pressure, thus resulting in an equally distributed load on the GR. The concentric arches model, however, gives a load distribution that resembles the observed load distribution: a concentration on the GR strips between adjacent piles, and approximately an inversed triangular load distribution on the GR strips.

Figure 3 – Zaeske (2001) considers the equilibrium of the crown elements of the 3D concentric scales.

Hewlett and Randolph (1988) and Zaeske (2001) compared their analytical model with measure-

Figure 4 – Van Eekelen et al. (2013b), the new concentric arches model. The load is transferred along the 3D hemispheres towards the GR strips and then via the 2D arches towards the pile caps.

Figure 5 – Concentric Arches model: resulting load distribution (kPa) for the Woerden case of figure 7a.



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Figure 6 – Variation of embankment height H, comparison analytical models with numerical calculations of Le Hello et al. (2009).

Figure 7 – Comparison calculated arching A with field measurements: (a) highway exit Woerden,

ments in scaled model tests without GR. Since we consider models to design the GR, and since the application of GR has a large influence on the arching mechanism, it would be better to compare with measurements in situations with GR. Figure 6 compares results of the considered analytical models with numerical calculations of Le Hello et al. (2009) and figure 7 with two cases of field measurements (Van Eekelen et al., 2012c and Van Duijnen et al., 2010). In these figures H (m) is the embankment height, a (m) the (equi-valent) width square pile cap, d (m) the (equi-valent) diameter of circular pile cap, sx and sy (m) the centre-to-centre distance of the piles along and across the road, sd (m) the diagonal centre-to-centre distance piles, ȍ (kN/m3) the unit fill weight, p (kPa) the surcharge load and ᒌ (o) the friction angle.

concentric arches model (Van Eekelen et al. 2013b) finds a load concentration on the GR strips, and approximately an inversed triangular load distribution on those GR strips. This is more in accordance with observations in scaled model tests, numerical analysis and field measurements. The considered numerical calculations agree best with the concentric arches model. Measurements in the field agree equally well with the concentric arches model and the model of Zaeske (2001).

The figures, as well as most other comparisons in Van Eekelen et al. (2013b), show that the concentric arch model agrees best with the numerical calculations, and most measurements in the scaled model tests. For the considered field test, the model of Zaeske and the new concentric arches model give comparable good results. It should be noted, that the measured arching A during the passage of the design load in Houten was higher than predicted with any of the analytical models, giving a safe design.

Conclusions It is important to make a distinction between models for piled embankments with or without geosynthetic basal reinforced (GR). In the case with GR, the load is concentrated on the GR strips between the piles (and the piles), and the load distribution on the GR strips is inverse triangular. This paper deals with the situation with GR. The models of Hewlett and Randolph (1988) as well as Zaeske (2001) result in an equally distributed load on the GR between the piles. The

Netherlands (Van Eekelen et al., 2012c) and (b) a railway in Houten, Netherlands (Van Duijnen et al., 2010).

Acknowledgements The financial support of Deltares and the financial support and fruitful discussions with manufacturers Naue, TenCate and Huesker is greatly appreciated.

References – ASIRI, 2012. Recommandations pour la conception, le dimensionnement, l'exécution et le contrôle de l'amélioration des sols de fondation par inclusions rigides, ISBN: 978-2-85978-462-1 (in French with in the appendix a digital version in English). – BS8006-1:2010. Code of practice for strengthened/reinforced soils and other fills, BSI 2010, ISBN 978-0-580-53842-1. – CUR 226, 2010. Ontwerprichtlijn paalmatrassystemen (Design Guideline Piled Embankments), ISBN 978-90-376-0518-1 (in Dutch). – EBGEO, 2010 Empfehlungen für den Entwurf und die Berechnung von Erdkörpern mit Bewehrungen aus Geokunststoffen e EBGEO, vol. 2. German Geotechnical Society, Auflage, ISBN 978-3-43302950-3. (in German, also available in English, 2011, ISBN 978-3-433-02983-1). – Hewlet, W.J., Randolph, M.F., 1988. Analysis of piled embankments. Ground Engineering, April 1988, Volume 22, Number 3, 12-18. – Kempfert, H.-G., Göbel, C., Alexiew, D., Heitz, C., 2004. German recommendations for reinforced embankments on pile-similar elements. In: Proceedings of EuroGeo 3, Munich, pp. 279-284.



– Le Hello, B., Villard, P., 2009. Embankments reinforced by piles and geosynthetics – Numerical and experimental studies with the transfer of load on the soil embankment. Engineering Geology 106 (2009) pp. 78 – 91. – Van Duijnen, P.G., Van Eekelen, S.J.M., Van der Stoel, A.E.C., 2010. Monitoring of a Railway Piled Embankment. In: Proceedings of 9 ICG, Brazil, pp. 1461-1464. – Van Eekelen, S.J.M., Bezuijen, A., Lodder, H.J., van Tol, A.F., 2012a. Model experiments on piled embankments Part I. Geotextiles and Geomembranes 32: 69-81. – Van Eekelen, S.J.M., Bezuijen, A., Lodder, H.J., van Tol, A.F., 2012b. Model experiments on piled embankments. Part II. Geotextiles and Geomembranes 32: 82-94 Geotextiles and Geomembranes 35: 119 and its corrigendum in Geotextiles and Geomembranes volume 32 (2012) pp. 82-94. – Van Eekelen, S.J.M., Bezuijen, A., 2012c. Does a piled embankment ‘feel’ the passage of a heavy truck? High frequency field measurements. In: proceedings of the 5th European Geosynthetics Congress. Valencia. Vol 5. pp. 162-166. – Van Eekelen, S.J.M. and Bezuijen, A., 2013a, Dutch research on piled embankments, Proceedings of Geo-Congres, California, March 2013. – Van Eekelen, S.J.M., Bezuijen, A., van Tol, A.F., 2013b. An analytical model for arching in piled embankments. To be published in Geotextiles and Geomembranes. – Van Eekelen, S.J.M. and Bezuijen, A., A.F., 2013c. Equilibrium models for arching in basal reinforced piled embankments, In: Proceedings of the 18th Int. Conf. on Soil Mechanics and eot. Eng. Paris 2013. – Zaeske, D., 2001. Zur Wirkungsweise von unbewehrten und bewehrten mineralischen Tragschichten über pfahlartigen Gründungselementen. Schriftenreihe Geotechnik, Uni Kassel, Heft 10, February 2001 (in German).

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Some special techniques used in the North-South Line

Figure 1 – Control panel.

Introduction Because of accessibility of the Amsterdam City Center, the city counsel decided for building a metro-line from the North to the South of Amsterdam. The line gets 8 stations and has a length of 9,7 kilometers. It is expected the North-South line is ready for use in 2017, and it will approximately transportate 200.000 travelers a day. VSF performed on the route of the line some special technics.

Work in compressed air At Station Ceintuurbaan “de Pijp” and Station “Vijzelgracht” compressed air is used for building the last part of these deep stations. Both Stations had to be digged out to a depth of about 30 meters. To prevent cracking of the soil by upward pressure of the groundwater, work in compressed air is used. At both stations, work in compressed air was thought of in the building specifications. At Vijzelgracht, work in compressed air was reconsidered, and crossed off the scope. After some setbacks with leaks in the diaphragm wall, and settlement of the old weavershouses, the risk in the subsoil was seen as a problem, so it would be irresponsible to take the risk of failure. Station Vijzelgracht was our second deep station for work in compressed air

ir. G.A. (Gerard) van Zwieten Projectmanager at Volker Staal en Funderingen bv

Figure 2 – Pneumatic sinking.

in Amsterdam. VSF is the only experienced company in The Netherlands for large building pits with the use of compressed air. VSF provided all the equipment for the compressed air work, as Compressor Station and Airlocks for the personnel. The Airlocks for the digged out soil, rebar, concrete and equipement where build by the main contractor, these were made of concrete. VSF provided also the medical support, operation of the airlocks and the compressor station and last but not least, continues control of the working chamber for the right pressure and health of the people below.

for treatment of possibility of decompression illness. All personnel got a health inspection, and when healthy for the job, a dive approval. The airlock attendants are skilled and experienced personnel which had a MAD-A training. They looked after about 16000 ‘dives’ at Vijzelgracht and Ceintuurbaan. Some figures: Working Chamber at Ceintuurbaan: 26000 m3 Working Chamber at Vijzelgracht: 54000 m3

Caissonsinking We installed 12 electric compressors to get the working chamber in compressed air. As a backup for the power supply, an emergency power supply was installed. When this backup would fail or when there wouldn’t be enough air supply, 3 large dieselcompressors where present as a second back up. To be sure of good quality of air, air was filtered by two separate filter lanes. Entering the working chamber was possible via the 3 airlocks for personnel. In case of emergency, people in the working chamber could escape via the 3 escape airlocks. There was a recompression tank available on site,



On another location, ‘Het Natte Damrak’ in front of the Central train station of Amsterdam, part of canals of Amsterdam. VSF performed the pneumatic sinking of 3 caissons. Before start of building the caissons, first a sheetpile wall is installed in the canal and the building location is purged for debris on the canal bottom and wooden piles of old quay walls. A Workisland was made in between the sheetpile wall, to build the caissons with the cutting edges. The First and biggest caisson had to be sunken to a

N55 GEO Special_Opmaak 1 17-07-13 16:06 Pagina 13

Figure 4 – Caisson after sinking.

Figure 3 – Caisson before sinking.

depth of 25 m below surface. With measurements of 58 m in length and 18 meters wide. This caisson is also a bridge foundation and startpit for the tunnel drilling machine, it is sunken down in 2 parts because of its tallness. Two of the caissons are sunk down in 2006, and the last one in between in 2012. The large gap in time has to do with traffic continuity over the old bridge and local environment. Method of Sinking down is using several hydraulic ejectors and pumping out the wet subsoil. By undermining its own foundation, the caissons are controlled sunken. People working below work also in compressed air. After about 12 meters a new forest of 150 wooden piles were discovered, it appeared to be all driven through piles. Caissons are parked with an accuracy of 20 mm to the goalposition, the working chambers are concreted for mass to avoid buoyancy.

Figure 5 – Frozen soil.

Groundfreezing All Caissons were in position, but had to be connected. VSF got the contract for this in combination with the caissonsinking. Caisson were all positioned about 60 cm one-to-the-other. One had to be connected to a diaphragm wall. Freezing method used is liquid nitrogen with a temperature of minus 196 degrees Celcius, the horizontal freezing tubes were embedded in the poured concrete, also a lot of temperature measuring points. The vertical freezing tubes are installed with a drill rig. Freezing in of the soil is done in about 2 weeks, removing the bulkhead and subsoil and installing the rebar and concreting took about 3 weeks per joint. In this period about 1 or 2 tanktrailers a day were on the job, each joint was about 120 m3 of frozen soil. 쎲

Figure 6 – Liquid nitrogen tank.



N55 GEO Special_Opmaak 1 17-07-13 16:06 Pagina 14

Magic on a square foot ir. B.J. (Bartho) Admiraal Innovation Manager at Volker Staal en Funderingen bv

In The Hague the famous museum Mauritshuis is undergoing an extension of “only” 10 x 15 m2. The collection of the museum consists of masterpaintings from mainly The Golden Age of the Netherlands in the 17th century, originally collected by the former stadthouder Prince William V of Oranje Naussau. The location of the building is in the centre of The Hague next to the houses of parliament and the office (‘The Little Tower’) of the prime-minister. So any disturbance of this historic environment should be avoided, like noise, vibrations, traffic collisions, etc.

Geotechnical the situation can be described as fine sands except for a thin peat layer at minus 16 m. All buildings have foundation slabs and thus have no pile-foundations. Like in most places in the Netherlands groundwater level is nearly the surface level. The main renovation and extension of the museum takes place in the underground and can defined as follows. The existing 2 story storage cellar will be transformed into an underground entrance-hall. Therefore new tension piles and strengthening of the structure is needed. so the piles have to be made



through the floor, below the water-table. Under the Mauritshuis, directly adjacent to the cellar a lift shaft will be constructed in the ground. Opposite of the museum an existing monumental building has come in possession and will be transferred into an extension of the Mauritshuis. The connexion will be made under ground and therefore a 2 story cellar-construction has to be made under the existing building. Under the road between the 2 buildings a cellar has to be constructed in order to connect and to create a large hall for exposition purposes.

N55 GEO Special_Opmaak 1 17-07-13 16:06 Pagina 15


VSF made a winning bid by offering a robust design based on flexible use of several special foundation techniques, like permeation grouting, jetgrouting, cutter-soil-mixing, ground-anchors and gewi-piles. Recognised knowledge, experience and reliability forms a base for trust and cooperation with the client and his technical advisors. The wide range of equipment and available techniques makes it possible to use the best solution for every situation.

Each day several crews with tiny machines vanished through the small entrees and stairways into the existing cellars, coming up again at the end of the day. In the limited space they created the watertight retaining walls. At the surface larger equipment could be used. After a period of 3 months working the E-day was there. Excavation of a building pit, especially with such techniques under these circumstances, is always exciting.



Due to the craftsmanship of all involved employees also this project was a success. The excavation could take place in a controlled way without significant leakages or building movements out of the tight limits. 쎲

N55 GEO Special_Opmaak 1 17-07-13 16:06 Pagina 16

Seismic ground prediction system on a tunnel boring machine

ing. R. Reijnen MI-Partners

dr. ir. G. Drijkoningen TU Delft

MI-Partners has developed a seismic vibrator for the TU Delft that is based on electromagnetic actuation, see figure 1.

Figure 1 – Photograph of the surface vibrator.

The Dutch company MI-Partners and the Technical University of Delft are two partners in the European Consortium NeTTUN. NeTTUN stands for “New Technologies for Tunnelling and Underground works”. This consortium, led by the French Tunnel Boring Machine (TBM) builder NFM, consists of 21 companies and institutes from 9 countries throughout Europe. Its goal is to significantly improve the drilling of tunnels. One of these improvements is to increase the safety of tunnel boring. Currently tunnel boring is done almost blind and hence, obstacles and change of soil structure can lead to delays, soil collapse and even accidents. Therefore, MI-Partners and the TU Delft are developing technology that can make a map of the soil in front of the boring head. TU Delft has a lot of experience in seismic imaging whereas MI-Partners uses its mechatronic knowledge from the high-tech industry for this challenging task. MI-Partners is a company based in Eindhoven that is active in mechatronic innovation. Its 30 employees develop innovative concepts for customers active in high-tech areas such as the semiconductor industry, healthcare and for technical

Figure 2 - Surface vibrator schematically depicted.

research institutes. These concepts usually start with the derivation of the specifications and end at a prototype level. Although the application changes over various projects, they all have in common that a high accuracy, a high speed or preferably both are needed. The knowledge MI-Partners has gained in working for customers like Philips and ASML can also be used for the development of this soil imaging device.

Surface vibrator It is not the first time that TU Delft and MIPartners work together on seismic imaging. This method is frequently used e.g. in the oil drilling industry to search for new oil fields. With this method, the surface of the ground is agitated and reflections of this agitation from the ground are measured with an array of sensors (usually geophones). This agitation can be done with dynamite, but its drawback is the fact that it damages the soil structure. Therefore, seismic vibrators are widely used that agitate the ground in a controlled, reproducible manner. Hereto, often hydraulic vibrators are used. However, these have a drawback that the hydraulics limit the use at low frequencies. Therefore, in the recent past



This vibrator can generate a wave force of 6700 N over a frequency range of 2 to 200 Hz. The principle of electromagnetic actuation is widely used in e.g. the semiconductor industry but is quite new in seismology. The benefits of this type of actuation are the fact that these actuators are very accurate and on the other hand they can offer a wide frequency range. A schematic drawing of the vibrator is shown in figure 2. It consists of a base plate of 200 kg on which the coils for the actuator are mounted. The magnets for the actuators are mounted on a reaction mass that weighs 1000 kg. Accelerometers measure the acceleration of the baseplate and the reaction mass. These data are used to compute the weighted ground force:

The knowledge of this force is needed in combination with the data received from the geophones to obtain the image map of the soil.

Vibrator on a TBM For the vibrator of the TBM a dedicated vibrator will be developed using the knowledge obtained from the surface vibration mentioned in the previous section. The main differences with this TBM vibrator compared to the surface vibrator of figure 1 are summarized in table 1. This vibrator will be mounted in the boring head of the TBM. Furthermore a range of sensors is also mounted on the boring head to measure the reflections from the ground (figure 3). During excavation the vibrator and the sensors are retracted inside the boring head to prevent damage. Every time a new mapping is desired the vibrator and sensors are placed on the bore front and the measurements are performed. Each measurement is repeated several times at several angles of the boring head. MI-Partners will design and build a TBM vibrator and the protection and retraction system for both the sensors and vibrator. TU Delft will develop the translation of the data that comes from the

N55 GEO Special_Opmaak 1 17-07-13 16:06 Pagina 17

Abstract The Dutch company MI-Partners and the Technical University of Delft are two partners in the European Consortium NeTTUN. This consortium consisting of 21 partners has the goal to significantly improve tunnel boring. MI-Partners and the TU Delft will develop a system that generates a map of the soil in front of the boring head. Using this map the tunnel boring process can be made more robust and safer.

Table 1

Surface vibrator

TBM vibrator

Use Environment Dimensions Positioning

Stand-alone Atmospheric; open air ‘Unlimited’ Manual

Typical mass

Baseplate: 200 kg Reaction mass: 1000 kg

In TBM >> 5 bar; > 50°C; dirt Limited by TBM dimensions Automatically; retraction during excavation Baseplate: 50 kg Reaction mass: 80 kg

sensors and vibrator into the image map of the ground. The biggest challenge is to combine the precision equipment and sensitive measurement devices into the harsh environment of a tunnel boring machine. The vibrator and the sensors should have to work accurately under a wide range of environmental properties. The local temperature and pressure can change over a wide range, and fur-

Figuur 3 - Schematic picture of the vibrator and sensors mounted on the TBM. The force wave is sent by the vibrator and its reflections are sensed in various ways depending on the soil structure.

thermore all obstacles that are present in the ground should not damage the vibrator and the sensors. Hereto, predictive modelling is used, where the behaviour of the system under these various circumstances is modelled e.g. in Finite Element models. At the end of this year a stand-alone prototype TBM vibrator will be finished which will be tested in the field during 2014. At the end of 2016 the

system should be fully integrated onto the TBM which will lead to a safer way of making tunnels.

Acknowledgements This research is part of the NeTTUN project, which receives funding from the European Commission’s Seventh Framework Programme for Research, Technological Development and Demonstration (FP7 2007-2013) under Grant Agreement 280712. 쎲

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N55 GEO Special_Opmaak 1 17-07-13 16:06 Pagina 18

Construction of the new A74 motorway at Venlo (NL)

Geosynthetic Reinforced Earth (GRE) used as bridge abutment and soil pressure relief

Figure 1 – The Muralex GRE system meets stringent construction and architectural design requirements (typical bridge abutment). The construction of a new section of the A74 motorway near Venlo (Netherlands) will address the increased cross-border traffic, thus relieving the pressure on the existing border roads. The A74 is planned to link the A73 (NL) and A61 (DE) motorways, providing a rapid direct link between the two neighbouring countries. The route of the motorway required the construction of several new bridges. In the search for an economical solution to integrate bridges KW 4, KW 4A and KW 5 into the landscape, the choice was made in favour of “Geosynthetic Reinforced Earth” (GRE) systems from HUESKER. The design calculations for these structures were undertaken in line with the guidelines outlined in EBGEO 2010 for the design of geosynthetic reinforced earthworks.

Building structure The individual bridges were erected using the ‘wrap around’ construction method with Fortrac® geogrids. This flexible construction method is especially suitable for soft non-homogenous

HaTe® nonwoven material was used as erosion protection on the exposed area of the geogrids. Instead of lost formwork in the form of angled steel reinforcement mesh, the KW 4 and KW 4A bridge abutments were erected using large panel formwork. This achieves particularly economical building progress and a flat slope face at the same time. The Fortrac® Natur GRE system functions as an approach ramp for the bridge structure of the KW 4, standing approx. 7.0 m high. It also relieves soil pressure on the abutment which is clad with concrete panels. The limits of the horizontal wall deformations and the intended fill material, containing a high percentage of fly ash, required the use of a high tensile, low strain reinforcement which was also resistant to alkaline environments. Consequently, Fortrac® MP was found to be the most suitable choice of material.

The measures taken on the A73/A74 demonstrate convincingly the use of innovative construction methods even with complex civil engineering structures.


Director HUESKER Synthetic BV Netherlands

dipl.-ing. Oliver Detert Engineering Department HUESKER Synthetic GmbH Germany

Figure 2 - KW 4A: Bridge abutment during construction.

subsoil conditions.


ing. C.A.J.M. Brok

The special properties of the polyvinyl alcohol (PVA), the yarn used in this product, ensure longterm resistance while complying with the permitted deformations.

KW 4A This structure spans the Wilderbeek stream and also allows animals to pass under the A74. One of the bridge abutments was constructed as a geosynthetic reinforced support structure using the Muralex® GRE system. The bridge superstructure, which carries heavy goods traffic, was supported directly on the earthworks and was reinforced by high-modulus, low-creep Fortrac® MP geogrids. The tight time schedule to implement the project required intensive preloading of the soft subsoil in order to reduce long-term settlement to a reasonable level. The maximum height of KW 4A is 11.0 m at the edges and 9.0 m at the support points. The spacing of the geogrid layers is a uniform 0.5  m. The

As a result of positive experiences gained world-wide with the Muralex® GRE system, it can be expected that this cost-efficient construction method, which also produces aesthetically pleasing designs, will gain greater acceptance.


N55 GEO Special_Opmaak 1 17-07-13 16:06 Pagina 19

Figure 3 - View of stripped formwork on front surface (KW 4).

Figure 4 - Use of large panel formwork to aid installation of the KBE Muralex® system (KW 4A)

Muralex® GRE system consists of a static supporting GRE base and a slim facing steel grid construction which can either be backfilled with stone or preseeded soil. The design also permitted the staggered placement of the steel grid construction, thus preventing the detrimental impacts of different settlement rates between the cladding and the GRE. If subjected to damage caused by vehicle impact or other ‘unplanned’ loading, the steel grid facing is easily replaced, as the cladding is non load-bearing.

KW 5 KW 5 is also designed with a complex architecture and offers pedestrians and cyclists a safe means of crossing the A74. The Fortrac® Natur GRE system was used here to relieve soil pressure on the abutments. The embankments designed with extra-steep slopes minimised the area of land used and reduced fill import compared with non reinforced embankments. Location Client Contractor Construction period Products

Figure 5 - Preloaded bridge abutment designed with KBE Muralex®.

A73/A74 at Venlo (Netherlands) Rijkswaterstaat – Ministerie van Verkeer & Waterstaat Dura Vermmer Divisie Infra B.V. Groete Projecten A74 March – May 2011 Fortrac® 110/25-20/30MP, Fortrac® R 200/30-30MP, Fortrac® R 400/30-30MP, Fortrac® 80/30-20T, 55/30-20T, HaTe® B 150 K3 HaTe® BS 12 Muralex® GRE 쎲

Figure 6 - Completed bridge abutment designed with KBE Fortrac® Natur.



N55 GEO Special_Opmaak 1 17-07-13 16:06 Pagina 20

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N55 GEO Special_Opmaak 1 17-07-13 16:06 Pagina 21

Stabilisation of unbound granular layers – reinforcement required?

Figure 1 - Outstanding performance of a biaxial geogrid in a performance-related test setup (after Christopher et al., 2008).

The behaviour of unbound base courses is improved by the use of geogrids. The latest results from large-scale testing carried out by e.g. Cuelho & Perkins (2009) show the effects of different geogrid products as well as performance-related tests by e.g. Christopher et al. (2008). Some prod-ucts provide characteristics for an ideal support of a ductile behaviour of unbound granular layers and reduced rutting (figure 1). Usually the behaviour of the reinforcement is

defined by the simplification of compound effect and membrane theory. The compound effect is the basis for the composite of reinforcement and surrounding soil while the membrane effect provides the ability for absorbing tensile forces: - A product which provides only an outstanding interaction with the surrounding soil can first provide a beneficial stabilisation effect when movement of the grain structure takes place and shear-strain is restrained by the absorption of tensile forces. - A product which provides high tensile strength to act as a membrane cannot mobilise its strength if no interaction with the surrounding soil is given. The latter would only take place at great deformation of the structure when the soil has already failed due to large shear displacements. That leads to the logical conclusion: Both effects for themselves cannot provide stabilisation or reinforcement of the granular layer; it is the combination and interaction of both which results in the beneficial effects of a suitable reinforcement product (figure 2). Not only thin and unpaved granular layers lead to plastic strains in the reinforcement product. Also in relatively stiff constructions (e.g. base courses

dipl.-ing L. Vollmert BBG Bauberatung Geokunststoffe GmbH & Co. KG Espelkamp, Germany

dipl.-ing C. Psiorz BBG Bauberatung Geokunststoffe GmbH & Co. KG Espelkamp, Germany

for paved roads) plastic strains are documented, also considering that these are relatively low compared to the elastic strains (Vollmert, 2013). The plastic strains are the result of the construction stage (trafficking and compaction), when the bearing capacity of the layers is initially relatively low and supplemented by plastic strains accumulated during service life. To restrain the amount of plastic strains – even when occurring at low strain of some per mill – the absorption of tensile forces is necessary and supplementary performance reliability of tensile strength should be provided (figure 3). Relaxation and creep should be discussed to withstand even small plastic deformations. The design goal for a good performance of a product is the optimal combination of the main parameters as interaction behaviour (by friction and interlocking), radial stiffness and absolute tensile strength (to provide satisfactory robustness), even under long-term aspects. Therefore, effective and long-term reliable stabilisation of unbound granular soils and layers requires beneficial geosynthetic reinforcement as defined in international standards and regulations. 쎲

Figure 3 - Radial stiffness of different geogrids and supplementary performance reliability.

Figure 2 - Definition of stabilisation with or without beneficial reinforcing effect.



N55 GEO Special_Opmaak 1 17-07-13 16:06 Pagina 22

Click-on modules for A.P. van den Berg’s digital cone (Icone)

Additional parameters measured in a single CPT F

or 45 years A.P. van den Berg has been active in the design and supply of advanced equipment for onshore, near shore and offshore in-situ soil investigation. A.P. van den Berg can provide complete or partial systems including pushing equipment, tools and data acquisition systems. A.P. van den Berg is recognized for its innovative strength and supplies proven technology. The head office is based in Heerenveen, The Netherlands. An extensive web of professional agents and representatives all over the world, market the knowledge and expertise of A.P. van den Berg.

process may also negatively affect the accuracy of the information obtained.

The Icone and Icontrol The engineers from A.P. van den Berg have developed a measuring system which eliminates these drawbacks. It consists of a digital data logger “Icontrol” and a digital “Icone”, measuring the traditional CPT parameters: cone tip resistance (q c ), sleeve friction (f s ), pore water pressure (u) and inclination (I x/y ). The unique Icone concept combines strength and reliability and provides excellent value for money. The Icone is mechanically 40% stronger than its predecessor, the analogue cone, and at the same time more accurate, more reliable and easier to maintain. Calibration data is stored in the cone itself, so USB sticks are no longer necessary. With a minimal investment, this high quality data acquisition system can also be integrated in existing CPT rigs.

Icone now extendable with click-on modules

The demand to build a comprehensive and accurate picture of the subsoil by using additional parameters from in-situ soil investigation is increasing. For example it may be required to derive the in-situ properties of both soil stratigraphy and soil elasticity to design a foundation that is subject to vibration; or both the soil density and soil electrical conductivity to allocate contaminated layers and predict future distribution. In general these parameters can only be acquired by separate systems (seismic, conductivity, magneto, etc.) and in subsequent tests. Apart from being time consuming, this


By moving to smart digital communication, sufficient bandwidth over a thin flexible measuring cable was created to accommodate additional parameters, without the need for changing cones, cables or control boxes. The Icone is easily extendable by click-on modules to measure addi-tional parameters in a single CPT test and any module is automatically recognized by the Icontrol, thus creating a true plug & play system. The modules shown on the right are already available.

Curious? Visit our booth No. 55 on the 18th International Conference on Soil Mechanics and Geotechnical Engineering in Paris (France) from 2 to 6 September 2013. We will demonstrate the Icone with some of the click-on modules and can provide detailed information.


N55 GEO Special_Opmaak 1 17-07-13 16:06 Pagina 23



- Shear wave left, shear wave right and compression wave - Elasticity modulus - Poisson's ratio


- Soil investigation in very soft soils - Undrained shear strength - Remoulded shear strength


- Detection of sand/clay layers - Tracking of saltwater-carrying layers - Detection of contamination

- 3-dimensional detection of the magnetic field - Detection of sheet piling, ground anchors and unexploded objects

You can also contact us at: +31 513 631355



N55 GEO Special_Opmaak 1 17-07-13 16:06 Pagina 24

soft so ft soil so oil p ti expertise Deltares has unique exper tise in the field of soft soils. Throughout the world, we work on smar t solutions for: šš F looding šš Land subsidence

We aim towards the sustainable enhancement for the living environment, with technological solutions. Putting into practice our strategic pr inciple: ‘Enabling Delta life’.

šš Dikes and embankments šš Tunnels and underground construction

D Deltares eltares iis sa an n iindependent ndependent iinstitute nst itute ffor or applied applied

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rresearch esearch in in the the field field o off w water, ater, s subsurface ubsur face and and

Services that we can provide in this area: š Online monitor ing š šš Forensic engineer ing š Advanced numer ical modelling (MPM) š š Physical modelling š š Field exper iments š | | +31 88 335 72 00

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