The invention relates to a steel pile, adapted to be driven into the ground and having along at least part of its lower terminal edge a thickened edge formation which comprises two strip portions positioned on either side of a web portion of the pile body and forming, together with said web portion, a fluid collecting and distributing passage which is connected with a fluid supply conduit that extends along the pile body downwardly, said passage comprising openings through which fluid under pressure may enter into the surrounding soil during pile driving. A pile of this type is disclosed in document EP 0 342 138.

With this well-known steel pile a passage system comprising a horizontally extending passage with downward- ly directed passages extending therefrom is cut in a central web of the pile body, said passage system being covered on either side of the web by said two strip porti¬ ons, with the exception of the lower end portions of said downwardly extending passages. The lower end portions of the downwardly extending passages constitute transverse openings through the central web, through which, when dri¬ ving the pile into the ground, fluid under pressure may enter laterally into the ground so as to facilitate ente¬ ring of the pile into the ground. The particular manner of providing a fluid passage system results in a rather complicated pile foot. Moreo¬ ver, the effect of the fluid jets discharging laterally from the fluid passage system is far from optimal.

The present invention aims at providing an improved pile.

Accordingly, the steel pile of the invention is characterized in that said two strips extend downwardly beyond the respective web portion, so that said fluid collecting and distributing passage is formed below the lower terminal edge of said web portion, and with the

openings of said passage directed substantially downward¬ ly. This results in a "fluid injecting" pile foot, which can be easily obtained by having said two strip portions extend below the lower terminal ends of the web of the pile body.

It is to be noted, that document GB 398 354 discloses a sheet pile, comprising a central fluid supply conduit that discharges in a pointed arch-shaped lower foot end of the pile. With this pile there is no horizontal fluid collecting and distributing passage from which fluid may enter into the ground during pile driving. With this well- known pile the fluid supply conduit may easily get bloc¬ ked.

In a preferred embodiment the pile according to the invention is characterized in that said two strip portions are making part of a steel tube that is fastened to the lower terminal edge of the respective web portion of the pile body, said tube being provided with downwardly direc¬ ted discharge openings. The invention also relates to a method for driving the pile of the invention into the ground by vibration, while simultaneously causing a fluid to discharge from the fluid collecting passage along the lower edge of the pile body. The method according to the invention is characteri- zed in that the supply of fluid is controlled to be just enough to bring the soil immediately below the lower terminal end of the pile body into a fluidized state. This facilitates driving of the pile in an optimal manner while leaving the ultimate interaction between the driven pile and the surrounding soil unaffected.

The term "pile" is to be interpreted in a broad sense and is intended to cover sheet piles, steel pipes and steel profiles.

The invention will be hereinafter further described by way of example with reference to the accompanying drawings in which:

Fig. 1 is a perspective view, showing two sheet piles

of the present invention in mutual engaging relationship;

Fig. 2A is a vertical cross-sectional view through the lower edge of a sheet pile, according to the line II- II in Fig. 1 and Fig. 2B is a cross-sectional view as shown in Fig. 2A, of a modification;

Fig. 3 shows a pipe-shaped form of a steel pile of the invention and

Fig. 4 is a perspective view of a steel pile of the invention in the form of a profile.

With reference to Fig. 1 two sheet piles 1 and 2 of a well-known trapezoid shape are diagrammatically shown. The sheet pile 1 has already been driven at the desired depth whereas the sheet pile 2 has to be driven further into the ground.

The sheet piles 1 and 2 have their longitudinal edge formations in mutual engaging relationship as is well known in the art. A relatively thick-walled steel tube 3 is attached, e.g. by welding, along the lower edge of the sheet piles 1 and 2. Said tube 3 is provided with down¬ wardly facing discharge openings 4. In the example shown in Fig. 1, the tube 3 is following the profile of the lower edge of the respective sheet pile and is connected to the lower end of a supply tube 5, which extends upward- ly along the body of the respective sheet pile.

In operation the supply tube 5 is connected with its upper end to a source of pressurized fluid (liquid) , which is supplied through the supply tube 5 to the tube 3 along the lower edge of the sheet pile entering into the ground and is discharged from the latter tube through said ope¬ nings 4.

While driving the sheet pile, by vibration or pus¬ hing, the fluid supply is controlled such that the dis¬ charging fluid brings the soil immediately below the lower edge of the sheet pile in a fluidized state. Depending on the type of the ground the required fluid pressure may vary e.g. between 10 and 100 bar.

In the example of Fig. 1 a central supply tube 5 is used and the tube 3 may have its ends closed. The tube 3 could also be connected to a supply conduit provided in the so-called "lock space" along the free longitudinal edge formation (to the right in Fig. 1) , which supply conduit would have to be removed prior to driving the next sheet pile.

In the modification shown in Fig. 2B a downwardly open collecting or pressure passage 3 ¹ is provided, which is confined by two strips 6 that are attached, e.g. by welding, on both sides of the lower portion of the respec¬ tive sheet pile. For the purpose of strengthening the strips 6 may be interconnected by bridging portions at regularly spaced locations. In the embodiment shown in Fig. 3 the steel pile is in the form of a steel pipe 10, having a substantially circular tube 11 of reduced diameter fastened, e.g. wel¬ ded, to its lower edge. The circular tube 11 is provided with downwardly directed discharge openings 12. The tube 11 may be in the form of two sections, which each cover a half of the circumference of the pipe 10 and are each connected with one end to the lower end of a supply con¬ duit 13, that extends along the inner side of the pipe 10 upwardly, whereas the two sections 11a are closed at the opposite ends.

In operation the supply conduits 13 are connected with their upper ends to a source of pressurized fluid (liquid) , which is supplied through the supply conduits 13 to the tube sections 11a along the lower edge of the pipe 10 entering into the ground. Driving of the pipe 10 is preferably effected by vibration. Especially with pipes of larger diameters less vibrating energy will be required for entering the pipe into the ground. It will be under¬ stood that a plurality of tube sections 2a, each connected to a supply conduit 13, may be used.

In the embodiment shown in Fig. 4 the steel pile is in the form of a H-profile 20, the lower edges at the foot

of the profile being provided with fluid injection tubes 21 having discharge openings 22. In this example the injection tubes 21 are supplied with fluid through two supply conduits 23 on either side of the web of the H.

The profile shown in Fig. 4 may e.g. be used for making so called "Berliner" walls, with which between individual H-profiles horizontally extending beams of wood can be inserted.