DEL108 – 11204462 Improved Axial Capacity of Piles in Sand (IPad)

Aanleiding van het project

Because of the soft soil conditions, the majority of engineered structures in (the western part of) the Netherlands are founded on deep (piled) foundations. In simple terms, a pile is a slender structural element (steel or concrete column) that uses soil-structure interaction to transfer loads to deeper, stronger soil layers. The Port of Rotterdam (POR) and Rijkswaterstaat (RWS) are amongst the biggest consumers of piles in the Netherlands.

Numerical models capable of modelling pile installation are not developed and thus designers rely on semi-empirical design approaches (using alpha factors linked to in-situ Cone Penetration Tests, which are used to characterize the soil deposits).

Despite the lack of incidence of pile failures changes to pile design standards (as of January 1st 2017) has resulted in the installation of longer or more piles, and increases in both construction time and associated installation risks. The direct impact is an estimated increase in construction costs of 10-20% for all deep foundation projects in the Netherlands. The change in design standards arose due to a gap in the knowledge surrounding some key aspects of deep foundation behavior that include: soil fatigue effects during cyclic pile installation and loading, soil ageing around piles, the effects of natural soil stratification and the use of potentially conservative limiting soil strength values in the Dutch NEN design code.

Doel van het project

This project will develop a holistic solution to solve this problem involving field testing, lab and numerical modelling in conjunction with advanced statistical approaches to provide accurate calculation procedures to determine the axial capacity of a pile.

Omschrijving van de activiteiten

Activiteit Type activiteit Rol partijen
Y1 Field work: pile test 1 Industrieel onderzoek Deltares, Havenbedrijf Rotterdam, NVAF, TU-Delft
Y1 Numerical analyses: set up soil model Fundamenteel onderzoek Deltares, TU-Delft
Y1 Statistical approach: set up soil model Industrieel onderzoek Deltares, Havenbedrijf Rotterdam, TU-Delft
Y1 Centrifuge tests Fundamenteel onderzoek Deltares, TU-Delft
Y2 Field work: pile test 2 Industrieel onderzoek Deltares, NVAF, Rijkswaterstaat, TU-Delft
Y2 Field work: interpretation pile tests Industrieel onderzoek Deltares, Fugro, Gemeente Rotterdam, TU-Delft
Y2 Numerical analyses: installation/ageing Fundamenteel onderzoek Deltares, TU-Delft
Y2 Statistical approach: load model parameters Industrieel onderzoek Deltares, TU-Delft
Y2 Centrifuge tests Fundamenteel onderzoek Deltares, TU-Delft
Y3 Field work: interpretation pile tests Industrieel onderzoek Deltares, Fugro, Gemeente Rotterdam, TU-Delft
Y3 Numerical analyses: installation/ageing Fundamenteel onderzoek Deltares, TU-Delft
Y3 Statistical approach: design approach Industrieel onderzoek Deltares, Fugro, Gemeente Rotterdam, TU-Delft
Y3 Interpretation centrifuge tests Industrieel onderzoek Deltares, TU-Delft
Y4 Implementation in guidelines Experimenteel onderzoek Deltares, Fugro, Gemeente Rotterdam, Havenbedrijf Rotterdam, NVAF, Rijkswaterstaat, TU-Delft
Y4 Writing Theses Experimenteel onderzoek Deltares, TU-Delft
Op basis van de verdeling van de activiteiten naar fundamenteel, industrieel en experimenteel onderzoek, en op basis van budget wordt een maximaal subsidie vergoedingspercentage geschat van 60%.

Verwachte resultaten

Volgnr Wat (publicaties: de aangegeven datum is het moment van indienen van het eerste concept) Wanneer (jaar)
1 Journal Paper describing the full-scale field tests at the Port of Rotterdam 2020
2 Conference Paper on the implications for full-scale field tests on pile design practice 2020
3 Journal paper on ageing tests performed at the Port of Rotterdam 2021
4 Conference Paper on the geotechnical characterisation of the Port of Rotterdam Pile Test bed. 2020
5 Journal Paper describing the full-scale field tests at the Rijkswaterstaat Pile Test Site 2019/2020
6 Journal Paper investigating limiting base resistance values for piles in very dense sand based on centrifuge testing 2021
7 Magazine article on the implications of developing national pile test sites for pile design practice – A case study at the Port of Rotterdam 2021
8 Horizontal and vertical spatial variability of sand deposits in the Port of Rotterdam and their implication on pile design practice in the Netherlands and beyond 2022
9 Journal paper on large displacement finite element analyses on modelling displacement pile behaviour 2022
10 Journal Paper – Reliability based pile design from full-scale load tests in the Netherlands 2022
11 Conference paper on the CPT averaging method 2020

Innovativiteit

De bestaande aanpak zoals beschreven in de huidige ontwerpnorm wordt in zijn geheel tegen het licht gehouden en ter discussie gesteld. De alpha-factoren, het hoe om te gaan met variatie in conusweerstand en de limietwaarden worden tegen het licht gehouden op basis van veldproeven en laboratoriumproeven. Ook aspecten die nog niet in de norm zijn opgenomen, als (vermoeiings-)effecten door cyclische belasting en toename van paalcapaciteit in de tijd worden nader onderzocht. Dit alles om tot een nieuwe aanpak te komen die beter aansluit bij het werkelijke gedrag van paalfunderingen.

Valorisatie

The outputs of the project are expected to result in project specific saving in foundation costs of between 10-20%. Given POR current invest around €80,000,000 per annum in foundations the potential for cost savings and increased competitiveness are strong. The proposal leader has delivered similar of higher cost savings in a number of previous projects in the onshore and offshore sector.
Welk product (zie boven)? Wie gaat het gebruiken? Wie gaat ervoor zorgen, en hoe?
1,2, 3, 4, 5, 6, 7, 8 , 10, 11 Pile designers and end users To ensure maximum impact of the work, i.e. a quick uptake in industry and Dutch and European standard procedures, the consortium includes researchers, designers, code developers, numerical modelers and end users (including an advisory board that will be chaired by Prof. Frits van Tol lead author of CUR 229 and Mr. Adriaan van Seters chair of Dutch National Standards group for geotechnical engineering and liaison with Eurocode). Utilisation will occur on a staged basis through-out the project, with application to design practice at the Port of Rotterdam within one year, at a National Level through a revised National design approach within 24 Months and on a European level through adaptions to the Eurocode by the project end.

Link naar projectresultaten…