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Research

 

 

This covers:

 

  • new economic piling sections
  • installation of piling (driveability, nuisance)
  • new applications for steel sheet piling
  • enhanced design methods for retaining walls
  • durability (corrosion protection systems, design)

 

The following presentation of five representative research projects is by no means exhaustive.

  • Behaviour of hot rolled and extruded corner sections under realistic conditions
  • AZ®-piles used as intermediary elements in combined tube-sheet pile-walls loaded by high water pressure
  • The impervious steel sheet pile wall
  • Oblique bending of double U-piles: influence of the retained soil
  • "Grenzen des Einsatzes induktiver Näherungsschalter zum Nachweis von Schlosssprüngen in Stahlspundwänden"

 

1. Behaviour of hot rolled and extruded corner sections under realistic conditions

On behalf of the Research Department of ArcelorMittal Belval & Differdange, tests have been carried out by the Public Research Centre Henri Tudor in Luxembourg. The difference in behaviour of hot rolled and extruded corner sections under realistic conditions should be evaluated through laboratory tests.

The first corner section was hot rolled, i.e. produced the same way than sheet piles and beams. The second one was extruded, a common process for producing profiles with complicated geometries. Both connectors fulfil the requirements of EN 10248 regarding minimum interlock interference.

The connector was rigidly fixed on one side and threaded in a sheet pile profile on the other side. This means that the load tests were done under conditions close to real life situations as the connector is normally welded on one side to a stiff support and threaded in another pile on the other side to simulate the flexibility of a sheet pile wall.

Due to its outstanding geometry, designed specifically for Larssen interlocks, the C9 can stand up to 15 to 25 % higher loads which corresponds to 100 to 200 kN per running meter of connector and this despite its lower yield strength.

Deformations in both cases are endorsed almost solely by the sheet pile; the corner section contributing less than 10 % to the total elongation. The deformations of the 2 tested corner sections turned out to be of the same magnitude.

 

2. AZ®-piles used as intermediary elements in combined tube-sheet pile-walls loaded by high water pressure

AZ® double sheet piles turned out to be highly efficient (width >= 1,26m) if used as intermediary elements in combined walls. Especially when they are loaded by high water pressures they turned out to behave even better than U-piles.

In collaboration with the University of Liège both laboratory tests and finite element simulations were carried out. During the tests airbags were used to simulate the water pressure and the sheet piles were fixed using the same connectors as in combined walls. The results showed that the AZ® piles are able to cope with water pressures up to 45 m (ultimate limit state) and that they are able to introduce safely the resulting loads into the tubes via the connectors.

The test results were used to calibrate a finite element model thus allowing to cover the whole range of AZ® piles and steel grades. The influence of driving imperfection was also determined numerically.

 

3. The impervious steel sheet pile wall

ArcelorMittal Commercial RPS has developed several watertightening systems for steel sheet pile walls which can cope with normal to very high requirements regarding the water tightness of sheet pile walls. This research covered various aspects as:

  • development of a range of watertightening systems: systems based on bituminous filler material for normal requirements, systems based on water swelling filler materials for very high requirements;
  • design (equivalent k-value, the joint resistance, the seepage calculation, analytical approaches, probabilistic design approach);
  • installation procedures for the different systems, in-situ measurements for quality assurance, behaviour of the systems under extreme environmental conditions (waste disposals);
  • designing turn-key solutions for almost every type of application.

  

DELFT GEOTECHNICS developed on behalf of ArcelorMittal Commercial RPS the measurement equipment and the analytical model. ArcelorMittal Commercial RPS made a whole range of field and laboratory tests to select the best water tightening system and to determine the influence of various parameters (soil, driving method, pile, type of fluid, water pressure,...) on the performance of the system. ArcelorMittal Commercial RPS established procedures on how to install the watertightening system and continuous to improve the systems by monitoring several job sites.

 

4. Oblique bending of double U-piles: influence of the retained soil

ArcelorMittal Commercial RPS sponsored a research project executed at TU DELFT aiming at the determination of the influence, of the retained soil on the oblique bending behaviour of double U-piles. A three dimensional finite element simulation (DIANA) of both the soil and the sheet piling was used to analyse this complex problem. In a first step a cantilever wall was dealt with.

 Deformed meshes of the perfectly smooth 3D-sheet pile wall with the tensile- and compressive stresses (N/m2) due to the moments My(x) and Mz(x) after 2.7m excavation (a): Front view with transverse deformations (b): 3D-view with transverse- and lateral deformations (deformations scaled up x5).

 

Deformed meshes of the perfectly rough 3D-sheet pile wall with the tensile- and compressive stresses (N/m2) due to the moments My(x) and Mz(x) after 2.7m excavation (a): Front view with transverse deformations (b): 3D-view with transverse- and lateral deformations (deformations scaled up x10).

 

  

The equivalent stress q after an excavation of 2.7 meter in case of a perfectly smooth resp. perfectly rough sheet pile wall (N/m2).

In a second step the model will be used to cover propped retaining walls and to determine the effect of water pressures as well as several measures to impede the occurrence of oblique bending. 
 

5.Limits on use of inductive sensors for detecting sheet pile declutching

In the clutches of inductive sensors - Sheet pile walls under surveillance....

Inductive sensors have proved themselves to be robust and reliable limit switches and position detectors in countless machines and systems, even under extreme conditions. Some unfavourable conditions can induce operational or reading errors however, and identifying the error is generally long and difficult. The example of sheet pile walls can help identify similar problems quickly and thus avoid them.

 

 Films showing the testing

  

 

 

 

   

 

 

 

More information available under: sheet-piling@arcelormittal.com

 

ArcelorMittal Commercial RPS in collaboration with ArcelorMittal Esch, Research and Development and external partners is committed to research in the field of steel sheet piling.