Jetting-Assisted Sheet Pile driving

Jetting as an aid to sheet pile installation

Although jetting-assisted sheet pile driving is a known technique, the results obtained with it are too often held confidential or lost in the unfathomed depths of archived projects. Because information is not generally made sufficiently public, the technique does not get the attention it deserves, and when it actually is used, the methods tend to be contractorspecific, not taking account of the results of broader research and experience by others. 

This brochure is merely intended to make public the results of experiments instigated by ArcelorMittal in France, experiments which back up previous studies by geotechnical experts in Germany, to disperse any doubts project owners and designers might have about the technique, and to highlight some basic guidelines for contractors. 

Questions people have about jetting assisted sheet pile driving are: 

  • what are the advantages of the technique? 
  • what kinds of soil are suitable for the technique? 
  • what are the principles for optimizing the jetting technique for different soil types? 
  • what happens to the surrounding ground? 

The paper “Jetting-Assisted Sheet Pile Driving” reprinted below was presented at the 9th International Conference on Piling and Deep Foundations held in Nice in June 2002*. 

It sums up the results of instrumented trials carried out between 1998 and 2001 on four sites under different geological conditions: 

  • clay at Mittersheim, in eastern France 
  • gravel at Strasbourg, near the Rhine 
  • sand and gravel at Lyon 
  • molasse at Toulouse. 

* Minor editorial change in December 2013

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en English AMCRPS_Jetting_Assisted_Sheet_Pile_Driving_GB.pdf de German AMCRPS_Rüttelspülverfahren_beim_Einbringen_von_Spundbohlen.pdf fr French AMCRPS_Lançage_technique_aide_mise_en_oeuvre.pdf
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Since 1997, ArcelorMittal, in partnership with the Laboratoire Central des Ponts et Chaussées and the Laboratoire Régional des Ponts et Chaussées de Strasbourg, has been carrying out a vast study to qualify and quantify the improvement jetting can make to vibratory driving of sheet piles and understand its effect on the surrounding soil.

The rigid steel jetting pipes are usually welded to the pile, with hoses connecting them to the jetting pumps. The water jet loosens the soil, reducing the resistance to penetration of the pile toe during driving.

Under some ground conditions, the water flowing along the pile acts as a lubricant and could reduce skin friction. Jetting enables sheet piles to be successfully driven into dense soils. It generally speeds up pile installation and reduces induced vibration, without damaging the piles.

Photo 1 shows the jets emerging from the pipes at the pile toe. It was taken during a test of jet operation, prior to driving.

Site characteristics

The soil at Mittersheim was clay, slightly overconsolidated beyond a depth of 5 m, requiring the use of a heavy pile hammer beyond 6 m penetration depth.

Consistency of the soil was medium to good, with the following characteristics:

  • pι* = 0.6 to 2.5 MPa
  • wι = 50% to 60%, Iρ = 20 to 35
  • φ = 25° to 30° with c’ = 0 to 20 kPa.

Configurations investigated

The following configurations were investigated:

  • AZ 18 and L 3S sheet piles, length 9 m, driven as double piles;
  • 2, 4 or 5 jets per double pile;
  • open jet pipe end or directed jet.

Toulouse

Site characteristics
The second trial concerned highly pervious Rhine materials (0-60 mm gravel with a few >100 mm cobbles, poorly graded with no fine sand, overlain by local silt which was stripped from the trial site).

Mechanical properties were poor
(2.0 MPa < pι* < 4.7 MPa).

The water table was found 1.30 m below ground level.

Under these conditions, the trial was intended to see if installation time and vibration would be reduced. 

A preliminary test had shown that standard vibratory driving alone was possible.