DEL 149
PEBSTER (Embankment with Basal STEel ReinforcementPiled )
Introduction
Piled embankments are being applied for the construction of roads and railways on soft soil. A piled embankment consists of a field op piles, with on top of that an embankment. Piled embankments are applied for the construction of roads and railways on soft soil.
A horizontal reinforcement layer is applied above the piles, at the base of the embankment. This is the basal reinforcement. A new, innovative development is the application of corrosion-free steel grid basal reinforcement. This new reinforcement type may improve the resilience and sustainability of piled embankments.
The existing calculation models for designing piled embankments were developed for geosynthetic basal reinforcement. They do not apply for steel reinforcement due to the high bending stiffness of the steel. This project looks at the behaviour of piled embankments with steel reinforcement. It is the purpose to develop a calculation model to design the steel reinforcement of a piled embankment. In addition, this project looks at the influence of the pile stiffness of the piles and how the subsoil consolidation behaviour affects on the development of soil arching.
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Fig. 1. (a) A steel-reinforced piled embankment; (b) Load distribution: A- load transferred to the piles directly via soil arching, B- load transferred to the piles via the basal reinforcement, C- load carried by the soil.
Consortium
Private partners
- Keller Polska Sp. z o.o., ul. Poznańska 172, 05-850 Ożarów Mazowiecki, Poland
- Keller Holding GmbH, Kaiserleistraße 8, 63067 Offenbach, Germany
- Keller Fondations Spéciales, 2 rue Denis Papin, CS 69224 Duttlenheim, 67129 Molsheim Cedex, France
- SHM System Sp. z o.o, Sp. kom., ul. Jana Pawła II 82A, 30-444 Kraków, Poland
Knowledge Institutes
- TU Darmstadt, Institute of Geotechnics, Franziska-Braun-Straße 7, 64287 Darmstadt, Germany
- Deltares, Boussinesqweg 1, 2629 HV Delft, The Netherlands
Public partner
- GEOLAB (a four-year Horizon 2020 project (2021 – 2025) funded by the European Union H2020 Research and Innovation Programme (project-geolab.eu)
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SmallFig. 3. Setup of the small-scale model tests (Deltares). This will undergo modifications for this proposed studyTest set-up, DFOS sensors, cross-sections, installation of displacement transducers.
Activities
- Scaled Small-scale tests at the Deltares Model Hall.
- Nearly full-scale tests in a deep test pit at the University of Darmstadt.
- The application of modern DFOS technology to gives a 3D picture of the deformations and soil strains in the embankment and steel strains.
- Analytical and 3D FEM simulations and analyses.
- Development of a calculation model to design the steel reinforcement of a piled embankment.
Large-scale test (TU Darmstadt), 16 piles centre-to-centre 1.25 m, sand being pluviated, DFOS sensors for measuring 3D deformations installed, cross-section, DFOS for soil strains and pressure cells installed.
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Selection of Results
First small-scale test: measured and calculated soil arching A (load exerted on the piles, above the basal reinforcement), using three European models. H&R refers to the model of Hewlett & Randolph 1988. Surcharge loads are indicated (0 to 100 kPa).
First small-scale test: Steel strains, measured on top of the top steel bar in x-direction. a. after consolidation without surcharge load, b. after increasing the surcharge load to 25 kPa, and c. after consolidation with surcharge load at 25 kPa.
DFOS result in
Fig. 4. Test pit for the large-scale test at TU Darmstadt: vertical deformations at Level 1 after the installation of the first 1.05 m of the embankment.
Comparison of the measured (DFOS result) and calculated deformations of the steel reinforcement in the large-scale test. Calculations with the CA model, that was adopted in CUR226.
Products
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/ planning
The official products of this TKI programme project are:
May 2022 | Test set-up of Deltares modified, and scaled tests conducted. |
April 2023 | Test set-up TU Darmstadt made, and nearly full-scale test conducted. |
2024 |
- 2023
Proceedings paper tests Deltares tests
- 2023
Proceedings paper tests Deltares tests
Two proceedings papers about the small-scale tests at Deltares were written and presented at the corresponding conferences: van Eekelen, S.J.M, Schneider, M., Hell, M., Wittekoek, B., Makowska, K., Zdanowicz, K., Pandrea, P., Sieńko, R., Schauber, P., Topolnicki, M., Zachert, H., (2024). 3D small-scale tests on steel-reinforced piled embankments. In: Proc. ECSMGE 24, Lisbon, Portugal. van Eekelen, S.J.M, Schneider, M., Hell, M., Makowska, K., Zdanowicz, K., Wittekoek, B., Pandrea, P., Sieńko, R., Schauber, P., Topolnicki, M., Zachert, H. (2024b). Distributed Fibre Optic Sensing (DFOS) in 3D small-scale tests on steel-reinforced piled embankments. Proc. ECPMG 24, Delft, The Netherlands. | |
2024 | Four proceedings papers about the nearly full-scale tests at TU Darmstadt were written and presented at the corresponding conferences: Schneider, M., Hell, M., Wittekoek, B., van Eekelen, S.J.M., Schauber,P., Pandrea, P., Topolnicki, M., Makowska, K., Zachert, H. (2024a). Untersuchungen zum Tragverhalten von Piled Embankments im Großversuch. In: Proc. Mitteilungen des Institutes für Geotechnik der Technischen Universität Darmstadt, Germany, Heft Nr. 144, 2024. Schneider, M., Hell, M., Wittekoek, B., Pandrea, P., van Eekelen, S.J.M., Topolnicki, M., Makowska, K., Sieńko, R., Zachert, H. (2024b). Large-scale test on the load bearing and deformation behaviour of basal steel-reinforced piled embankments. In: Proc. ECSMGE 24, Lisbon, Portugal. Schneider, M., Hell, M., Wittekoek, B., Pandrea, P., van Eekelen, S.J.M., Topolnicki, M., Makowska, K., Sieńko, R., Zachert, H. (2024c). High-density spatial measurements on a 3D large-scale model of a basal steel-reinforced piled embankment. In: Proc. ECPMG, Delft, Netherlands. Schneider, M., Hell, M., Wittekoek, B., Makowska, K. (2024d). 3D Trag- und Verformungsverhalten stahlbewehrter Erdkörper auf vertikalen Traggliedern. In: Proc. Baugrundtagung 2024, Germany. |
2025 |
Paper in Dutch magazine |
2026 | Journal paper with the results of the tests in both labs, and recommendations for the design of a steel reinforcement for piled embankments. |
More information?
Please, contact Suzanne.vanEekelen@deltares.nl.
Fig. 2. Distributed Fibre Optic Sensors: (a) glued bare optical fibre, (b) EpsilonSensor, (c) 3DSensor. Special versions of these sensors were developed for the PEBSTER test series.