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D6) Sheet pile reinforcement

Start: 09/2017
End: 09/2021
Status: Active

Contact details

Arny Lengkeek

Delft University of Technology

Outcome

This project developed an adjusted soil behaviour type chart that includes organic clays and peats and a new set of cone penetration tests (CPT) based on correlations for unit weight, strength, and stiffness parameters of organic soils. Moreover, we developed a new relationship based on critical state soil mechanics, linking the effective strength parameters to undrained strength parameters currently used in existing approaches for slope instability analysis. Finally, we carried out a back analysis of the Eemdijk full-scale dike failure test, consisting of three tests: (1) a ground dike, (2) a sheet pile reinforced dike and (3) pull-over tests on sheet pile panels. The interpretation of test measurements provided valuable insights into the sheet pile performance to extreme loading conditions that are not easily found in practice due to the strict design requirements.

Eemdijk full-scale test; dike with sheet pile reinforcement after to failure. Photo by Arny Lengkeek https://www.instagram.com/eemdijk_damwandproef/

Motivation and practical challenge

As a senior engineer with about 20 years of practical experience on hydraulic and geotechnical projects in the Netherlands and abroad, my motivation is related to better combining the dike engineering theory with practice. Therefore, this project builds upon the current modelling approaches for the stability assessment of dikes with sheet pile reinforcement and my experience in soil parameter determination and constitutive models (i.e. soil responses to different mechanical loading conditions). These two types of knowledge come together in interpreting the soil investigation tests and related parameters, which are input for the advanced finite element method (FEM) models used for the stability, the strength of the sheet pile and the deformation assessment. Moreover, the Eemdijk full-scale test was a unique experiment that allowed me to validate the performance of relations or analytical models used in the dike engineering practice.

Research challenge

This project aims at improving the dike stability assessment general practice via an improved CPT-based classification and correlations for organic soils and more effective strength parameters using Critical State Soil Mechanics theory. In particular, the following research questions were formulated related to the “Eemdijk damwandproef” full-scale failure test:

  • How does a sheet pile reinforced dike perform towards and beyond failure in a full-scale test environment and how does this compare to an earthen dike?
  • To what extend can the full-scale test be modelled with FEM using existing constitutive models?

Innovative components

In The Netherlands and other deltas in the world, very soft and highly organic soils are omnipresent but absent in the existing international soil behaviour type charts. Therefore, an improved CPT-based correlation was developed to estimate the saturated soil unit weight for a wider range of soils, from sands to peats. A new theoretical model (CSR) was developed which can be implemented in the limit equilibrium method on slope stability analysis and provides the undrained shear strength based on effective strength and stiffness parameters. Finally, regarding the Eemdijk test, two parallel 60m long full-scale test dikes of which one was reinforced with a sheet pile were loaded until failure with:

  1. sheet pile pullover tests consisting of 4 sheet pile configurations in length and width.
  2. ground dike stability test where the water level in the sand core of the dike is step-wised increased by infiltration.
  3. sheet pile dike stability test to create a realistic load scenario and failure mechanism.

Relevant for whom and where?

Engineers who design dikes with structural inclusions, such as sheet piles, with finite element method (FEM) models. Engineers who use cone penetration tests (CPT) in soft organic soils for civil engineering projects in general.


The components of this research are developed for a range of typical dike sections for the Dutch riverine area, and for a case study of a full-scale test embankment in Eemdijk.

Progress and practical application

This project improved CPT-based correlations for the Dutch sedimentary soils and how characteristic soil values are calculated with observations and statistical methods. The Eemdijk full-scale test gave insight into the soil-structure interaction of the structurally reinforced dike on soft soil, loaded by high water and uplift conditions. The current design guideline for sheet pile wall reinforcement imposes strict deformation requirements without considering the plastic capacity of the sheet pile. Moreover, the sheet pile pullover tests showed that reducing the section modules for edge piles is not required given that these piles have a discontinued character (i.e. only connected on one side of the wall). Finally, a structural reinforcement with a continuous sheet pile has advantages after structural failure as it contributes to the water-retaining capacity of the dike. For a detailed description of each finding, please check the related outputs.

Recommendations for practice

  • We recommended using the updated CPT based classification given its improvements compared to previous correlations for the sedimentary deposits found in The Netherlands.
  • We further recommend using the new CSR model to compare effective strength and undrained strength parameters and reduce uncertainties in parameter determination and stability analysis. The new relation aligns with current practice based on the Stress History and Normalised Soil Engineering properties (SHANSEP) method.

Last modified: 22/11/2021

Contributing researchers

Arny Lengkeek

Delft University of Technology

Supervisory team

Wim Kanning

Delft University of Technology

prof.dr.ir. Bas Jonkman

Delft University of Technology

Ronald Brinkgreve

Delft University of Technology

User group

Project outputs

Application of geo-statistics and pairwise established CPT-based correlations for line infrastructure

A method to use CPT and laboratory tests to calculate characteristic values, on the basis of pairwise established CPT-based correlations. We illustrate the method in six cases accounting for regional and local variations, failure extent and availability of local CPTs.

22/11/2021

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Bevat: Conference proceedings

Eemdijk full-scale field test programme: ground dike and sheet pile dike failure test

Two similar test dikes were constructed at full scale (5m high, 25m wide, 60m long) to gain better understanding of the failure mechanism and deformations for both dikes, one of which served as a reference for the dike that had an 18m long sheet pile wall was installed.

01/09/2019

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Bevat: Conference proceedings

Eemdijk full-scale field test programme: sheet pile pullover tests

The full-scale pullover tests consisted of 4 sheet pile configurations to gain more insight in the soil-structure interaction and the structural behavior of sheet piles beyond maximum bending capacity.

01/09/2019

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Bevat: Conference proceedings

Impact of the Eemdijk full-scale test programme

This paper describes the rationale behind the test setup and operation of the test programme in relation to the current design codes and guidelines. First the set of knowledge questions to be resolved is considered. These questions gave direction to the type of failure tests, the required instrumentation and the impact of conclusions.

01/09/2019

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Bevat: Conference proceedings

CPT based unit weight estimation extended to soft organic soils and peat

A new correlation is proposed that can be used to estimate the saturated soil unit weight from sands to highly organic soils. Our proposal outperforms other considered correlations. The variation in the estimation is however still considerable and comparable to earlier studies.

21/06/2018

View publication

Bevat: Conference proceedings

News

Cross-Project Macro Stability Exploration (in Dutch)

22/11/2021

Within the total tasking of the Flood Protection Programme, the failure mechanism macro stability is the most important cost item for dike sections that...

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Eemdijk test: dike with sheet piles has collapsed (in Dutch)!

21/03/2018

The test dike with sheet piles collapsed on March 17 around 4 pm. The results of this trial will be used by all dike...

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All news