EP2102418A2

EP2102418A2 - Foundation system for the forming of a foundation pile in the ground

Info

Publication number: EP2102418A2
Application number: EP07860869A
Authority: EP
Inventors: Marinus Teunis Van Leeuwen Jr.
Original assignee: VERTICAL DEV BV; Vertical Development BV
Current assignee: Gebr Van Leeuwen Harmelen BV
Priority date: 2006-12-13
Filing date: 2007-12-11
Publication date: 2009-09-23
Also published as: EP2102419A2; WO2008072951A2; NL1033050C2; WO2008072951A3; WO2008072950A3; WO2008072950A2

Abstract

A foundation system for the excavating in the ground of a pit to be filled with a hardenable mass for the forming after hardening of a foundation pile, comprising a rod-like drive-in member (2), a drill head (3) connected to the lower end of the drive-in member (2), an installation for the lowering into the ground of the drive-in member (2) together with the drill head (3). The drill head (3) comprises a housing (4) having a drive shaft (7) which is rotatable with respect to the housing (4), a drive unit (5) for the driving in rotation, by- means of driving of the drive shaft (7), of at least one digging member (8) positioned on the underside of the drill head (3) being provided in the housing (4), a power supply (6) being provided for the supplying of energy to the drive unit (5), which power supply (6) extends from an energy source above ground to the drive unit (5) in the housing (4) of the drill head (3).

Description

Title: Foundation system for the forming of a foundation pile in the ground

The invention relates to a foundation system for the excavating in the ground of a pit to be filled with a hardenable mass for the forming after hardening of a foundation pile.

Known in the art is a foundation system in which a bucket with a scoop base is screwed into the base, which bucket is then filled with soil, after which the bucket is raised out of the ground in order to discharge the soil. This process is repeated until a desired depth has been reached. In order to prevent the pit from wholly or partially collapsing, the pit is filled during excavation with a bentonite-containing suspension which serves as a support liquid. As a result, for each excavation step, the bucket should be moved once downwards and upwards through the support liquid. A pit is thus gradually excavated in the ground. The pit is subsequently filled with concrete which in this case expels the support liquid, so after hardening a concrete foundation pile is formed.

A drawback of the prior-art system is that this gradual excavation and subsequent forming of a foundation pile is a time-consuming process, soil being excavated effectively for less than 10 percent of the required time. A further drawback is that the excavated soil can become contaminated with the support liquid. Finally, despite the presence of the support liquid, there is a risk of damage to the previously formed pit wall because the bucket has to be moved a plurality of times along this location.

For example, EP 00160736 discloses a foundation system in which a bucket is provided at the lower end of a telescopically extendable tube assembly for the excavating of soil.

In addition, it is known in the art to excavate a pit in the ground with the aid of a rod provided with a propeller blade. During excavation, the rod is driven in rotation and lowered into the ground. In this case, the propeller blade removes the soil and discharges it upwards. Thus a pit is excavated in the ground which, once the desired depth has been reached, is filled with concrete, so after hardening a concrete foundation pile is formed.

A drawback of this prior art method is that relatively high forces are necessary to excavate the pit, especially if foundation piles having large cross sections or lengths have to be formed. In addition, in this case too, there is a risk of premature collapsing of the excavated pit, whereas temporary filling of the previously excavated pit portion with a support liquid will lead to marked contamination of the excavated soil with the support liquid.

The object of the present invention is to overcome at least some of the above-mentioned drawbacks or else to provide a usable alternative. In particular, the object of the invention is to provide an environmentally-friendly foundation system allowing in a broad range of soil types reliable, rapid and efficient excavation of a pit which can subsequently be filled with a hardenable mass for the forming of a foundation pile.

This object is achieved by a foundation system according to claim 1. The system comprises in this case a rod-like drive-in member having a drill head connected to the underside thereof. The drill head comprises a housing having a drive shaft which is rotatable with respect to this housing. A drive unit for the driving in rotation via the drive shaft of the at least one digging member is provided in the housing. The drive unit is provided with energy by means of a power supply extending from an energy source above ground to the drive unit in the housing of the drill head. Also provided is an installation for the lowering into the ground, during driving of the digging member, of the drive-in member together with the drill head. A pit can thus be formed in the ground in a continuous excavating process, while the forces required to do this are relatively low. The rod-like drive-in member and a large portion of the drill head do not have to be driven in rotation.

It will be noted that WO 03/085208 has previously disclosed a system for the forming of a foundation element in the ground, using a drill head provided with its own drive unit. The drive unit is located within a housing and is powered from an energy source located above ground. However, the drill head is in this case not connected to the lower end of a rod-like drive-in member and is not lowered into the ground by a drive-in member. The drill head itself digs down into the ground. Simultaneously with the drilling process, tube segments are pressed into the ground with the aid of a press installation in the pit excavated by the drill head. However, these tube segments are not intended to drive the drill head forward into the ground but rather are, if necessary, drawn into the ground along with the drill head. Furthermore, these tube segments are intended to be left behind in the ground where they form the pit wall of the foundation element. Once the desired depth has been reached, the drill head is then removed, through the tube segments which are left behind, up out of the pit thus formed, for which purpose the drill head is configured with smaller radial dimensions than the tube segments.

In a particular embodiment according to the present invention, the drill head comprises a flushing chamber which is positioned above the digging member in the housing and has a supply and discharge extending from the drill head to a position above ground. The supply is used in this case for the pressurized introduction during drilling of a flushing liquid into the flushing chamber. The discharge is used to discharge during drilling the supplied flushing liquid mixed with soil removed by the digging member out of the flushing chamber. Soil which is removed by the digging member passes directly into the flushing chamber. The removed soil is in this case pressed continuously into the flushing chamber by the digging member and the drill head which advances downwards together with the rod- like drive-in member. The soil which is released can mix in the flushing chamber with the flushing liquid and easily be discharged via the discharge. It is in this case possible to discharge the flushing liquid containing the removed soil via a suitable pipe system to far outside the immediate working area, for example to a sludge repository. It has been found that the use of a flushing chamber of this type allows water, for example water from a nearby lake or river, itself to serve as a highly effective flushing liquid without further additions to increase viscosity. A further advantage is that the discharge of removed soil does not necessarily lead to contamination of the remainder of the drill head, of the previously excavated pit portion and of the working environment above ground. In particular, if the previously excavated pit portion is filled with a support liquid, this advantageously does not give rise to contamination of the removed soil with the support liquid.

The pressure of the flushing liquid supplied in the flushing chamber is preferably set to an excess pressure slightly higher than the prevailing groundwater pressure in the surrounding soil. In particular, the excess pressure is in this case approx. 0.1 - 0.3 bar. This excess pressure ensures that the soil at the site of the digging member can be discharged in a controlled manner. This reduces the risk of undesirable disturbances in the surrounding soil and thus the risk of scouring and subsidence. The use of the flushing chamber at a slight excess pressure allows the discharge rate of the soil mixture to be precisely adapted to the desired drilling speed.

In one embodiment, the underside of the flushing chamber is delimited in the housing by a base plate provided with inlets. This increases the efficiency with which the flushing liquid mixes with the removed soil particles.

Further preferred embodiments are defined in the dependent sub- claims .

The invention also relates to a method according to claims 26 - 28, to an assembly consisting of a drive-in member and a drilling head according to claim 29 and also to a foundation pile according to claim 30.

The invention will be described hereinafter in greater detail with reference to the appended drawings, in which:

Figure 1 is a schematic view in longitudinal section of an embodiment of the foundation system according to the invention during excavation of the pit;

Figure 2 is a schematic view in cross section of a variation of the drilling head in Figure 1; Figures 3a, b, c and d show successive steps of a method according to the invention using a foundation system according to Figure 2;

Figure 4 is a view corresponding to Figure 2 containing different types of drilling members; and

Figures 5a, b, c and d show successive steps corresponding to Figure 3 utilizing a Kelly bar and a crane installation.

In Figure 1, the foundation system is denoted in its entirety by reference numeral 1. The foundation system 1 comprises a rod-like drive-in member 2 formed in this case by a telescopically extendable rod. The lower end of the drive-in member 2 is connected to a drill head 3. The drill head 3 comprises a housing 4 containing a drive unit 5 formed in this case by a hydraulic motor, and in particular a hydraulic motor having two directions of rotation, which is powered by means of a hydraulic line 6 from a pressure reservoir located above ground. The drive unit 5 connects to a drive shaft 7 which is mounted in the housing 4 so as to be able to rotate and to which a digging member 8 is connected. The digging member 8 is in this case formed by a wheel dredge, located on the underside of which are a plurality of cutter heads 9 which extend downwards and between which feed-through openings are provided for allowing removed soil particles to pass upwards.

Located above the digging member 8 is a flushing chamber 10 which is in this case delimited by wall parts of the housing 4 and the digging member 8. Connected to the flushing chamber 10 is a supply 14 for the pressurized supplying thereto of a flushing liquid. Also connected to the flushing chamber 10 is a 'discharge 15 for the discharging therefrom of the supplied flushing liquid mixed with the soil particles removed by the digging member 8.

A pit 16 is excavated in the ground 17 by activating the drive unit 5 and at the same time lowering the drive-in member 2 into the ground. Before the drilling process, an insert sleeve 18 is pressed into the ground. The insert sleeve 18 serves to guide the drill head 3 during excavation of an initial portion of the pit precisely into a desired position in the ground 17 and also to prevent undesirable collapsing of the crushable pit portion. Once the drilling process has been completed, this insert sleeve 18 can, if necessary, be removed again from the ground.

The foundation system 1 further comprises a supply 20 for the supplying during drilling of a support liquid to the previously excavated pit portion. The support liquid is, in particular, a bentonite-containing suspension. The supply 20 in this case opens at the top in the excavated pit portion.

The outer circumferential wall of the housing 4 of the drill head 3 is configured to rest during excavation directly against the earth circumferential wall of the pit 16 excavated by the digging member 8. The housing 4 has for this purpose a substantially cylindrical outer circumferential wall part. As a result of the fact that this cylindrical outer circumferential wall part of the housing 4 moves downwards along the wall, excavated immediately beforehand, of the pit 16, it advantageously helps to reinforce the pit wall.

A possible method for the forming of a foundation pile in the ground using the foundation system 1 includes the following steps.

Firs^'tly, the insert sleeve 18 is conveyed into the ground, for example by means of ramming or vibrating. Subsequently, the assembly consisting of the drive-in member 2 and the drill head 3 is guided into the portion of the insert sleeve 18 that protrudes above ground with the aid of an installation (not shown) . The installation comprises for this purpose, for example, a crane installation provided with gripping means which are configured to act on the drive-in member 2. By then telescopically extending, for example hydraulically, the drive-in member 2, the drill head 3 can be lowered while digging into the ground 17 with a desired insertion force. The drive unit 5 is thus activated, as are the pumps connected to the supply 14 and discharge 15. Afterwards, the assembly consisting of the drive-in member 2 and drill head 3 is gradually lowered into the ground using the digging member 8 which is driven in rotation. Once a specific initial pit depth has been reached, a pump connected to the supply 20 is activated for gradually supplying the support liquid into the pit. The rotational speed of the digging member 8, the drive-in speed of the drive-in member 2 and the pump speeds of the pumps connected to the supply and discharge are in this case precisely coordinated with one another.

As soon as the drill head 3 has passed the insert sleeve 18, the outer circumferential wall of the housing 4 of the drill head 3 enters during excavation of the remainder of the pit 16 into direct contact with the surrounding soil 17. Once the desired pit depth has been reached, the drive-in member 2 is telescoped, as a result of which the drill head 3 is brought back upwards through the support liquid 1.

Subsequently, a reinforcement can, if necessary, be attached in the excavated pit and a hardenable foundation mass is conveyed into the pit 16. As a result of the difference in specific weight between the foundation mass and the support liquid, the support liquid will in this case be displaced upwards out of the pit 16. However, preferably the support liquid is pumped out of the pit and stored for subsequent use at the same time as the hardenable foundation mass is supplied. Once the entire pit space has been filled with the foundation mass and the foundation mass has had time to harden, a foundation pile according to the invention is formed. The hardened mass of the foundation pile rests over the majority of the length of the foundation pile directly against the surrounding soil 17 which in some cases it even partially infiltrates.

Figure 2 shows an alternative embodiment of the drill head. The drill head 30 comprises in this case a housing having a cylindrical circumferential wall part 31. The housing contains a mounting flange 32 on which a drive 33 is mounted for the driving of a digging member 36 mounted on a drive shaft 35. The drive 33 is in this case formed by a hydraulic motor. The hydraulic motor has the advantage that it takes up little space, can produce a high output and is not sensitive to moisture and dirt. The upper side of the hydraulic motor can be connected to a hydraulic feed line (not shown) . Located below the mounting flange 32 is a base plate 40 provided with inlets. A flushing chamber 43 is delimited between the mounting flange 32 and the base plate 40. Connected to the flushing chamber 43 are a supply (not shown) for the supplying at a slight excess pressure of a flushing liquid and a discharge 45 for the discharging from the flushing chamber 43 of the supplied flushing liquid mixed with the soil particles removed by the digging member 36. As a result of the removal during operation of the soil by the digging member 36 and the simultaneous advancement of the drill head 30 down into the ground, the removed soil is automatically pressed into the flushing chamber 43 via inlets in the digging member 36 and the base plate 40 respectively. In the flushing chamber, the removed soil particles mix with the flushing liquid and this mixture can be conveyed upwards to outside the excavated pit via the discharge 45. The flushing liquid enters the flushing chamber 43 via the supply, strikes the base plate 40 and then sprays up on all sides. The resulting vortex advantageously ensures thorough mixing of the flushing liquid with the soil.

The inlets are preferably configured so as to widen toward the top. As a result, the soil particles entering the inlets will pass into the flushing chamber 43 as they are discharged.

It is possible temporarily to reverse the functions of the supply and discharge in order to flush blockages out of the flushing chamber. The reversal can advantageously be carried out above ground. A bypass containing an activatable valve can be provided between the supply and the discharge 45. The supply and discharge also contain activatable valves. The pipes can be efficiently flushed by activating these valves in a suitable manner.

The drill head 30 further comprises on its upper side a second digging member 50. The digging member 50 can be driven by a drive 51 which in this case is also formed by a hydraulic motor. A cover plate 52 provided with inlets is located below the digging member 50. Provided below the cover plate 52 is a second flushing chamber 54 extending annularly around the drive 51. Also provided on this flushing chamber 54 are a supply (not shown) for the supplying at a slight excess pressure of a flushing liquid and a discharge 55 for the discharging from the flushing chamber 54 of the supplied flushing liquid mixed with soil particles removed by the digging member 50. This provision of the second digging member 50 and the associated flushing chamber 54 with a supply and discharge 55 allows any non-uniformity of the bore hole to be drilled out and eliminated when the drill head 30 is withdrawn upwards. This will be described hereinafter in greater detail with reference to Figure 4.

Figure 3a shows the situation in which the drill head 30 is, when the digging member 36 is driven, at the same time lowered into the ground by exerting a downwards force on a rod-like drive-in member 57 connecting to the drill head 30. A support liquid 61 is introduced into the excavated pit portion 60 formed above the drill head 30 (see Fig. 3b) . During drilling, flushing liquid is supplied to the flushing chamber 43 where the flushing liquid mixes with removed soil particles, which mixture is subsequently discharged upwards via the discharge 45. The rod-like drive-in member 57 is in this case advantageously hollow in its configuration, thus allowing the supply and discharge and also the power supplies before the drives to extend therethrough. Once the desired final depth has been reached (Fig. 3c) , the drive 33 for the first digging member 36 is disconnected and the supply and discharge 45 after the flushing chamber 43 are shut off. Subsequently, the drive 51 before the second digging member 50 is activated and the supply and discharge 55 after the second flushing chamber 54 are activated. Subsequently, the drill head 30 can be drawn upwards out of the pit 60 by means of the rod-like drive-in member 57 (Fig. 3d) . The second digging member 50 in this case also eliminates any non-uniformity from the bore hole located above the drill head 30.

As may be seen in Figure 2, the drill head 30 is provided with equalizing pipes 64 containing shut-off valves 65. The equalizing pipes extend from the underside to the upper side of the drill head 30. When the drill head 30 is withdrawn upwards, the shut-off valves 65 are placed in the open position and thus ensure that the support liquid which is in the first place located only above the drill head 30 can flow away downwards toward the free space formed during the withdrawal below the drill head 30. In Figure 4, like components are denoted by the same reference numerals as in Figure 2. An alternative embodiment of the drill head, using other types of digging members, is shown. The left-hand half of Figure 4 shows in this case a first variation of the digging member, whereas the right-hand half of Figure 4 shows a second variation of the digging member. In both variations, the digging member comprises a plurality of fold-in digging elements 70 distributed over the circumference. The fold-in digging elements 70 extend in the radial direction as a kind of spoke and are able to hinge about hinge pins 71 connected to the remainder of the digging member. The digging elements are thus free to automatically hinge downwards as soon as the drill head 30 is raised. In addition, the digging elements 70 are free to automatically hinge upwards to a folded-out position as soon as the drill head 30 is placed on the ground and drilling is commenced. This has the advantage that, in the folded-out position, the digging elements 70 can have radial dimensions which are somewhat larger than the remainder of the drill head, whereas in the folded-in position they assume smaller radial dimensions. As a result, the digging elements 70 do not obstruct the drill head as it is drawn upwards out of the ground, thus reducing the risk of damage to the excavated drill pit wall and allowing the withdrawal forces advantageously to be reduced.

In order to ensure that the digging elements 70 do indeed fold upwards when positioned on the ground, they are downwardly delimited at angles of 30 degrees or less with respect to the horizontal.

The left-hand type of digging element 70a is distinguished in that a plurality of scoops positioned next to one another are provided on the underside thereof, whereas the right-hand type of digging element 70b is provided on its underside with a series of teeth. A specific type can be selected depending on the type of soil to be drilled into.

Figure 5 shows a variation of Figure 3. In this case too, like components are denoted by the same reference numerals. The major difference is that a different type of rod-like drive-in member is used in this case. The drive-in member consists in this case of an assembly of telescoped tubes which are configured in such a way that they can each be engaged with one another in an extended position by exerting a rotational force on the respective tubes. An example of a telescopic tube assembly of this type with rotational engagement is commercially available as a Kelly bar. For this purpose, use is made of a crane installation 80 comprising a drive 81 which is configured to act on the outer tube 82 in order to rotate the outer tube with respect to the drill head and the tubes already engaged therewith. In a variation, the drill head 30 can also be rotated while the outer tube is fixed. This also gives rise to engagement. Disengagement can be carried out by rotating the drive 81 or the drill head 30 respectively in the opposite direction. Figure 5c shows a position in which two inner tubes 84, 85 are guided out of the outer tube 82 and engage with respect thereto, after which the crane installation 80 has lowered the engaged tube assembly into the ground over a specific stroke while driving the drill head 30.

A hoisting wire 87, which is rigidly connected to a lower portion of the tube assembly, is provided for removing the drill head 30 upwards, as is shown in Figure 5d. By disengaging the tubes with respect to one another and subsequently raising the hoisting wire, the tubes are thus telescoped and drawn upwards together with the drill head 30 out of the excavated pit.

In addition to the abovementioned embodiments, a large number of variations are possible. The drive-in member may thus also be formed by a non-telescopically extendable rod, for example a segmented rod as shown in Figure 4, to which in each case a new rod part can be fastened in order to extend the rod. The drive-in installation in this case comprises, for example, gripping means which are configured to exert a continuous downwards force on the rod. The gripping means may also be provided so as to be able to move up and down in order in each case to secure a rod part, to press it downwards in order then to release this rod part, to move unimpeded upwards where it secures a new rod part. The installation for the lowering into the ground of the drive-in member together with the drill head is preferably configured to act on the outer circumferential wall of the drive-in member. It is also possible to provide in the drill head a different type of drive unit, for example an electric drive such as an electric motor. The digging member preferably has radial dimensions which are greater than or equal to those of the outer circumferential wall of the housing of the drill head. The digging member may be of a different type. The drill head has, in particular, radial dimensions larger than those of the drive-in member. More particularly, the outer circumferential wall of the housing of the drill head has radial dimensions which are at least two times larger than those of the drive-in member. The outer circumferential wall of the housing can have any desired shape. Preferably, the housing is cylindrical in its configuration. Both during excavation and during the bringing back upwards of the drill head, the outer circumferential wall of the drill head rests against the surrounding soil of the pit excavated by the digging member and thus reinforces the pit wall owing to the sliding forces which are produced. Both during excavation and during the bringing back upwards of the drill head, the outer circumferential wall is not in direct contact with the surrounding soil. This advantageously restricts the forces required.

The invention thus provides an efficient and reliable foundation system which can advantageously be used for all types of projects, in particular for the production of foundation piles having a length between 50 - 100 metres. These foundation piles are characterized by a high load bearing capacity, partly owing to the fact that the hardened foundation mass rests directly against or mixes to a certain extent with the surrounding soil.

Claims

1. Foundation system for the excavating in the ground of a pit to be filled with a hardenable mass for the forming after hardening of a foundation pile, comprising:

- a rod-like drive-in member (2) ;

- a drill head (3) connected to the lower end of the drive-in member (2);

- an installation for the lowering into the ground of the drive-in member (2) together with the drill head (3) ; characterized in that the drill head (3) comprises a housing (4) having a drive shaft (7) which is rotatable with respect to the housing (4), a drive unit (5) for the driving in rotation, by means of driving of the drive shaft (7) , of at least one digging member (8) positioned on the underside of the drill head (3) being provided in the housing (4), a power supply (6) being provided for the supplying of energy to the drive unit (5) , which power supply (6) extends from an energy source above ground to the drive unit (5) in the housing (4) of the drill head (3) .

2. Foundation system according to claim 1, wherein the drill head (3) comprises a flushing chamber (10) positioned above the digging member (8) in the housing (4) , to which flushing chamber (10) is connected at least one supply (14) for the pressurized introduction during drilling of a flushing liquid into the flushing chamber (10) , and to which flushing chamber (10) is connected at least one discharge (15) for the discharging during drilling of the flushing liquid mixed with soil removed by the digging member (8) out of the flushing chamber (10) .

3. Foundation system according to claim 2, wherein the underside of the flushing chamber (43) is delimited in the housing (30) by a base plate (40) provided with inlets.

4. Foundation system according to any one of the preceding claims, wherein the drive-in member (2) comprises a telescopically extendable tube assembly.

5. Foundation system according to claim 4, wherein the telescopically extendable tube assembly (82, 84, 85) comprises a rotational engagement system.

6. Foundation system according to any one of the preceding claims, wherein the drive unit (5) is a hydraulic motor.

7. Foundation system according to any one of the preceding claims, wherein a supply (14) is provided for the supplying during drilling of flushing liquid, which supply (14) opens out in the drill head (3) and extends to above ground.

8. Foundation system according to any one of the preceding claims, wherein a discharge (15) is provided for the discharging during drilling of the flushing liquid mixed with soil removed by the digging member (8) , which discharge (15) starts in the drill head (3) and extends to above ground.

9. Foundation system according to any one of the preceding claims, wherein a supply (20) is provided for the supplying during drilling of support liquid, in particular a bentonite-containing suspension, to an excavated pit portion formed above the drill head (3) .

10. Foundation system according to any one of the preceding claims, wherein the drill head (3) has a total height which is less than two metres .

11. Foundation system according to any one of the preceding claims, wherein there is provided an insert sleeve (18) which is intended to be fed into the ground before the excavation of the pit for the guiding during drilling of the drill head (3) along an initial portion in the ground.

12. Foundation system according to any one of the preceding claims, wherein the digging member (8) is a wheel dredge provided with a plurality of cutter heads (9) .

13. Foundation system according to any one of the preceding claims, wherein the digging member comprises a plurality of fold-in digging elements (70) .

14. Foundation system according to claim 13, wherein the fold-in digging elements (70) are configured for assuming in the folded-out position radial dimensions which are larger than the outer circumferential wall of the housing (31) and for assuming in the folded-in position radial dimensions which are smaller than the outer circumferential wall of the housing (31) of the drill head (30) .

15. Foundation system according to any one of the preceding claims, wherein the outer circumferential wall of the housing (4) of the drill head (3) is configured to rest during excavation directly against the earth wall of the pit (16) excavated by the digging member (8) .

16. Foundation system according to any one of the preceding claims, wherein the outer circumferential wall of the housing (4) of the drill head (3) is configured to rest, when the drill head (3) is brought back upwards, against the earth wall of the pit (16) excavated by the digging member (8) .

17. Foundation system according to any one of the preceding claims, wherein the housing (30) comprises a substantially cylindrical outer circumferential wall part (31) .

18. Foundation system according to any one of the preceding claims, wherein a second drive unit (51) is provided in the housing (31) for the driving in rotation of the at least one digging member (50) positioned on the upper side of the drill head (30) .

19. Foundation system according to claim 18, wherein the drill head (30) comprises a flushing chamber (54) positioned below the second digging member (50) in the housing.

20. Foundation system according to any one of the preceding claims, wherein there is provided an equalizing pipe (64) which is provided with an activatable shut-off valve (65) and extends from the underside to the upper side of the drill head (30) .

21. Foundation system according to any one of the preceding claims, wherein the drive-in member (2) is rigidly connected to the drill head (3) in the axial direction.

22. Foundation system according to any one of the preceding claims, wherein an installation is provided for the bringing back upwards after excavation of the drive-in member (2) together with the drill head (3) .

23. Foundation system according to any one of the preceding claims, wherein the installation for the lowering into the ground of the drive-in member (2) together with the drill head (3) is configured to act on the outer circumferential wall of the drive-in member (2) .

24. Foundation system according to any one of the preceding claims, wherein the outer circumferential wall of the housing (4) of the drill head (3) has radial dimensions which are larger than those of the drive-in member (2) .

25. Foundation system according to any one of the preceding claims, wherein the outer circumferential wall of the housing (4) of the drill head (3) has radial dimensions which^' are at least two times larger .than those of the drive-in member (2) .

26. Method for the forming of a foundation pile in the ground, including the following steps:

- the excavating in the ground of a pit using a foundation system (1) according to any one of the claims 1 - 25;

- the filling of the pit (16) with a hardenable mass during or after removal of the drive-in member (2) together with the drill head (3) for the forming after hardening of the foundation pile.

27. Method according to claim 26, wherein the outer circumferential wall of the housing (4) of the drill head (3) is in direct contact during excavation of the pit (16) with the surrounding soil over the majority of the drilling path.

28. Method according to either claim 26 or claim 27, wherein the outer circumferential wall of the drive-in member (2) is not in direct contact with the surrounding soil (17) during excavation of the pit (16) .

29. Assembly consisting of a drive-in member (2) and a drill head (3) for use in a foundation system (1) according to any one of claims 1 - 25.

30. Foundation pile formed using a foundation system according to any one of claims 1 - 25, which foundation pile comprises a hardened mass, in particular concrete, wherein the hardened mass rests directly against the surrounding soil.