DK2728070T5

DK2728070T5 - A method for driving and anchoring a pile in the ground and pile

Info

Publication number: DK2728070T5
Application number: DK12190848.7T
Authority: DK
Inventors: Mark Dipl-Ing Krischik
Original assignee: Aug Prien Bauunternehmung Gmbh & Co Kg
Priority date: 2012-10-31
Filing date: 2012-10-31
Publication date: 2015-02-16
Also published as: EP2728070B1; PL2728070T3; DK2728070T3; EP2728070A1

Description

The invention relates to a method for driving in and anchoring a driven pile in the ground, said driven pile having a foot in the region of the front end and having a head in the region of the rear end. The invention also relates to a driven pile having the features of the preamble of claim 4.

Driven piles have been known for a long time as means for forming foundations for constructions and also for stabilising constructions, in particular on wet subsoil and in the vicinity of or on water, for example to cross-stabilise sheet pile walls. This is particularly significant when, for example during building work, construction pits are to be excavated, secured with sheet pile walls and said sheet pile walls are to be cross-stabilised. However, driven piles are likewise used for anchoring permanent constructions, such as sluice constructions, bank walls and water structures of this type, but also for superstructures and the like.

Various measures and options are known for introducing piles. In a first method, piles are driven into the ground by applying ramming impulses, acting in the direction of the longitudinal axis of the pile, to the respective pile heads. In another method, the pile, which is also often referred to as a vibrating pile in said method, but is also referred to as a driven pile here to simplify the terminology, is jolted into the ground by vibrations which act in the longitudinal direction of the pile at a higher frequency compared to conventional ramming.

Depending on the geological nature of the subsoil, the pile driving method or the foundation of a driven pile by vibration is the more advantageous variant. Thus, cohesive soil formations (for example soil which contains clay or loam) are suited to a pile ramming method by applying ramming impulses, whereas driven piles cannot be introduced, or can only be introduced with great difficulty by being jolted into soil formations of this type. However, non-cohesive subsoil (containing sand) is very well suited to the use of vibration methods. In said methods, the subsoil can be easily displaced by vibration and a channel can be formed for driving in the pile.

In the various methods, approaches are known in which a hardening material, such as in particular concrete or mortar is introduced into a space between the pile foot and the surrounding ground to stabilise the anchorage of the driven pile in the subsoil. This takes place in particular in the vibration methods during the introduction of driven piles into non-cohesive subsoil, since there, unlike in very tenacious layers of soil of a cohesive nature, a primary anchoring of the pile does not have the same stability without additional measures being taken. Thus there, the hardening material, in particular concrete, is used to penetrate shaken-free spaces and to thereby anchor the driven pile in the subsoil.

In this respect, driven piles exist which have very different cross-sectional profiles. Thus, DE-GM 75 40 863 discloses a driven pile having an H profile which tapers at the foot of the pile to form a ramming edge. Positioned over the H profile in the region of the pile foot is a foot reinforcement in the form of displacement plates which, when the pile is driven in, is intended to promote penetration into the ground or subsoil and clear a space which is rectangular or square in cross section. AT 229 230 describes a driven pile comprising an inner cavity, through which cement slurry or cement mortar can be introduced into the region of the pile foot and can there be pressed out under high pressure. This driven pile is provided in particular to create underwater foundations. A pile shoe which tapers in the lower region displaces the soil in the region of the pile foot and leaves behind an annular space which runs around the hollow pile and is filled with the issuing material such as cement slurry or cement mortar to anchor the pile thus in the ground. EP 2 374 943 A2 discloses a ramming mandrel which has a hollow shaft through which hardening material is introduced into the region of the mandrel foot and can there be discharged and injected. For this purpose, arranged in the ramming mandrel shown there (embodiment according to Fig. 9a and 9b) is a tapering mandrel shoe which simultaneously also serves as a valve for opening and closing the discharge for the hardenable mass. After reaching a ramming depth, the mandrel is removed from the ramming hole, the valve is opened and the ramming hole is filled with hardenable material to form a concrete anchoring pile.

The inventors have recognised that the known methods for driving in and anchoring a driven pile and driven piles known according to the prior art have shortcomings, in particular if the subsoil into which this pile is to be driven is composed of a plurality of layers alternating between non-cohesive (sandy) soil layers and cohesive (clay or loam) soil formations. Mixed soil structures of this type and geological conditions having layers which have to be penetrated for an adequate foundation of a single driven pile in a plurality of successive layers are encountered relatively frequently. Thus for example, in the North German Plane, there are such formations which have formed glacially and have been produced due to successive depositions in the moraine landscape typical of this region. To achieve adequate stability for high load-bearing capacities in soil formations of this type with the known driven piles and known methods, very long piles often have to be used which are ultimately very difficult to handle and the introduction of which into the subsoil is expensive and laborious. Furthermore, it is generally impossible for vibration methods to be used in subsoils of this type, because these methods cannot traverse cohesive layers, such as loam or clay layers, as described above.

Therefore, the object of the invention is to provide an improved method for driving a pile into the ground and to provide a driven pile of an optimum design for this purpose.

This object is achieved according to the invention in different aspects, namely by a method according to the features of claim 1 with advantageous developments according to the features of dependent claims 2 and 3, in a further aspect by a driven pile having the features of claim 4, in relation to which advantageous developments are stated in dependent claims 5 to 15, and finally also by a system having the features of claim 16.

Thus, in a first aspect, the invention consists of a method for driving in and anchoring a driven pile in the ground, said driven pile having a foot in the region of the front end and having a head in the region of the rear end. According to the invention, in the method, the driven pile which has an enlarged cross section in the region of the pile foot compared to the cross section of the rest of the pile, is driven into the ground by applying onto the pile head ramming impulses which act in the longitudinal direction of the pile, with the pile foot preceding and at the same time, a pipe running on the pile injects a suspension of a hardenable material as far as the pile foot into the region in which the cross section is tapered compared to the region having an enlarged cross section towards the pile head.

According to the invention, in this respect the suspension has a viscosity of at most 250 mPa*s, in particular at most 200 mPa*s, and is injected at least temporarily at a pressure of at least 10 bar, preferably at least 25 bar, preferably at least 50 bar, in particular up to 100 bar. The viscosity of the suspension can also adopt lower values as the upper limit, for example at most 150 mPa*s, 100 mPa*s or 50 mPa*s.

In particular in the pile foot, the region having an enlarged cross section is provided with an additional oversize on the respective surfaces of at most 10 cm, in particular < 5 cm, in many cases also < 2.5 cm so that a gap which is excavated in excess and into which the suspension of the hardenable material is injected, has a correspondingly small gap width. The combination of the gap which is formed when the pile is driven in and is designed in particular with a small width and the injection of the suspension of the hardenable material having a viscosity of at most 250 mPa*s, in particular at most 200 mPa*s allows the pile to be driven in and anchored by the method according to the invention both in cohesive soil layers, such as clay-containing layers, and in non-cohesive formations, such as sandy layers. In particular, the method according to the invention also allows a pile to be securely anchored in soil formations which have different superimposed layers comprising layers with non-cohesive characteristics and layers of cohesive material. In tests using piles which are approximately 30 m long (piles up to a length of 60 m were produced) which were driven into the subsoil and anchored therein by the method according to the invention, it was possible to achieve load-bearing capacities and tensile strengths of up to 8,000 kN (corresponding to a load of approximately 800 t), and this was in particular in the mentioned mixed-layer ground which is difficult to handle in conventional methods for driving in piles.

In this respect, the method according to the invention can be used for driving in and anchoring piles to be introduced vertically into the subsoil, but also for those which require a pile to be driven in obliquely, deviating from a vertical and directed about a predetermined angle to the vertical, for example to anchor a vertical sheet pile wall of an excavation pit against the effective ground or water pressure.

In the method according to the invention, the suspension is advantageously a suspension of cement, fly ash, optionally other binders and water, to which concrete additives, such as liquefiers and/or retarders can be added if appropriate. In order for the suspension to be injected under the stated high pressures, it is important that the suspension contains a fine-grain material in the contained solids and is not mixed for example with gravel or with a coarse-grain material of this type.

To prevent the injected suspension from being "blown out" of the inlet region in which the pile passes into the ground to be anchored at the surface, the method according to the invention can be implemented such that first of all, the pile is introduced into the ground over a first longitudinal portion without the suspension being injected, the suspension then being injected after the driven foot has reached a predetermined initial depth. This predetermined initial depth can be for example 5 m or more up to for example 10 m or even 20 m. In this respect, it is important that an adequately deep further portion follows in which the pile is driven into the subsoil and in which the suspension of the hardenable material, which can be, for example, a suspension containing binder, in particular cement, is injected.

In practice, particularly when the local geological conditions produce a soil profile having horizontally layered regions which have different characteristics, in particular regions of alternately non-cohesive and cohesive layers, the injection pressure, required for introducing the suspension is controlled according to a soil profile with the drive length, which reveals the position of the soil profile in which the pile foot is located and thereby the introduction site of the injected suspension. Thus, to form a satisfactory anchorage in cohesive soil layers, for example in clay-containing layers, a higher injection pressure is required than for binding in a non-cohesive soil portion, for example in a soil layer having a high sand content. Thus, in the method according to the invention, subject to the penetration depth of the pile foot and to the progression of the driving in of the pile, very different injection pressures for the suspension can be provided. In some soil layers, these pressures can be very low, significantly less than 10 bar and thus also less than 25 bar (to almost 0 bar, i.e. just allowing the suspension to "seep in"), whereas in other soil portions, they can rise considerably to an injection pressure of 100 bar, currently provided as the maximum pressure. Depending on the technical design of the suspension lines and pumps, if appropriate, even pressures of more than 100 bar can be achieved and can be advantageous.

It is advantageous in particular for monitoring and quality control of the driving-in and anchoring operation if profile curves of different measured quantities are taken over the drive length of the driven pile, in particular the injection pressure of the suspension and/or the throughflow amount of the suspension which is introduced. It is also possible for data relating to the drive depth to be collected subject to the respectively applied ramming impulses or for data to be collected relating to the impulse intensity subject to the drive-in depth of the pile. On the one hand, all these data can be evaluated for comparison with the previously recorded geological profile to establish whether the behaviour of the driven pile and of the ramming system reflects the circumstances and expectations previously established on the basis of geological tests. On the other hand, these data can be used for validating model calculations, from which a load bearing capacity of the driven-in and anchored pile is calculated.

In the method according to the invention, the pile can be driven in in particular without a tapered pile shoe which opens out into a point or cutting edge, in particular if the pile is formed from a pile body which has an H-shaped or double-T-shaped cross-sectional profile.

The driven pile according to the invention which can be driven into the ground and anchored therein by means of the method described above and is particularly suitable for and is designed for this method has a body which is formed from an H-profile and has a foot joining a front end and a head delimited by a rear end. It is distinguished in that in the region of the pile foot, a material thickening is provided which extends along the surface of the H profile in a direction transverse to the longitudinal direction and is substantially closed around the profile on all surfaces. According to the invention, this material thickening protrudes by an amount d beyond the adjoining surface of the H profile, this amount being: 0.5 cm < d < 10 cm, in particular 0.5 cm < d < 5 cm. A greater lower limit of for example 1.5 cm can occasionally be particularly advantageous. Furthermore, in the case of the driven pile according to the invention, a continuous feed pipe is provided in the longitudinal direction of the pile body from the head to the foot and is fixed to the pile body, and it opens into at least one discharge opening in the region of the pile foot above the material thickening. In the present context, "above the material thickening" means in a region viewed from the front end of the pile body on the other side of the material thickening.

The driven pile according to the invention terminates at its front end in a particularly blunt manner, i.e. it does not have a ramming shoe or a shape with a taper formed as a point or cutting edge. The feed pipe is in particular understood as being continuous in that it is formed in a continuous piece without interposed coupling pieces or coupling sleeves. This is relevant in particular because a suspension of a hardenable material is injected under a temporarily high pressure through this feed pipe while the pile according to the invention is driven in and anchored. The pressures which occur in the course of this can be up to 100 bar, possibly even higher, so that in particular if coupling pieces or coupling sleeves are stressed due to contact with surrounding soil components when the pile is driven into the ground, they run the risk of not being able to withstand the high pressures and of breaking off.

What is unique about the driven pile according to the invention is that when the pile is driven in by ramming, i.e. when ramming impulses are applied to the pile head, which impulses act in the longitudinal direction of the pile, the material thickening produces a gap between the pile body and the surrounding ground into which the suspension is injected under pressure, sometimes under high pressure of at least 10 bar, preferably at least 25 bar, in particular up to 100 bar and after hardening, it forms a correspondingly pressed in anchoring and thus provides a high tensile stability and pressure stability and bearing force of the driven pile in the longitudinal direction thereof. In this case, it is particularly important that the material thickening is of a relatively low thickness of at most 10 cm, sometimes at most 5 cm, but is also of an adequate thickness of at least 0.5 cm, sometimes at least 1.5 cm. The adequate thickness of at least 0.5 cm ensures that an adequately wide gap is provided to be able to inject therein a sufficient amount of hardening suspension. However, with a greater protrusion than the maximally provided 10 cm, the material thickening would produce an excessively wide gap in the ground into which a suspension of a hardenable material, introduced under high pressure, could no longer be introduced with the desired pressing-in effect and with the successful build-up of pressure or the hardened mass could no longer reliably transfer the ensuing forces to the surrounding ground. The amount d is particularly advantageously within a range of 0.5 cm < d < 2.5 cm, and is in particular 2 cm.

The discharge opening of the feed pipe can be in particular a single one which is directed in particular towards the pile foot. Not only for a design of this type, but in particular in the case of such a design, to prevent a blockage of the discharge opening by soil which is released and penetrates thereinto when the pile is driven in, a diversion console can be provided in a region opposite the discharge opening in the longitudinal direction of the pile body towards the front end. This diversion console has in particular a length and/or a width which protrudes from the surface of the rest of the pile body and is sufficient to shadow the discharge opening of the feed pipe to a satisfactory extent. This diversion console can be integrated into the region of the material thickening, but can protrude by a greater extent beyond the adjoining surface of the H profile than the material thickening. In this respect, the diversion console is also to be understood to be a further protrusion of the material thickening in the region opposite the discharge opening in the mentioned manner. In particular in order to prevent the diversion console from breaking off when the pile is driven in, optionally to also provide a diversion structure for displaced soil, it is also possible for guide and support structures to be provided which extend in the longitudinal direction of the pile body, are positioned obliquely starting from a region of the pile body facing the front end extending as far as the diversion console and are connected to said console.

In a further advantageous embodiment, in the case of the driven pile according to the invention, through-openings can be formed in the region of the pile foot, arranged in particular in a longitudinal portion of the pile body which is positioned between the discharge opening of the feed pipe and the peripheral material thickening and guided through the surface portions of the H profile. In the context of the invention, the driven pile according to the invention can have a plurality of feed pipes which open out in particular in the different cross-sectional portions of the H profile substantially into the same longitudinal portion. However, it is a particularly significant aspect of the invention and is considered to be advantageous if only one feed pipe is provided. This reduces the necessary complexity, but still provides the established outstanding anchoring results of a driven pile according to the invention. To then achieve in the region of the pile foot an optimum distribution of the hardening material which is present as a suspension and is injected via the feed pipe, the mentioned through-openings are advantageously provided. The hardening material, which is present as a suspension, does not only have to be distributed thus along the gaps surrounding the H profile or along the continuous gap, but the material is then also distributed around the driven pile by flowing through the through-openings. Overall, this means a better distribution of the injected suspension and consequently a better anchoring of the pile in the subsoil.

In principle, the feed pipe can be formed in different ways in the context of the invention, for example it can also be formed as a pipeline. However, it is preferred for the feed pipe to be a flexible hose line. If the hose is designed in particular for conducting the suspension under high pressure and if it is provided with an appropriately reinforced wall, a flexible hose line of this type can be mounted very easily on the driven pile, in particular in a continuous manner. Hose lines of this type are available as endless products, can be cut to size for the production of the drive pile according to the invention and fixed to the pile. However, for such a use of a hose line as a feed pipe which is considered to be advantageous, it is then also advantageous and preferred according to a development of the invention for the hose line to be reinforced in the region of the discharge opening by a tubular portion which preferably consists of a metal material, such as brass or low alloy steel ("construction steel") and which surrounds said hose line. Instead of a tubular portion surrounding the hose line, a tubular portion can also be selected equally effectively which adjoins one end of the hose line and is rigidly connected to the hose line. This tubular portion having a fixed pipe wall provides a particularly stable and protected discharge region with the discharge opening arranged therein.

The feed pipe is advantageously fixed on the central portion, referred to as the web, of the pile body which extends between the outer profile portions, referred to as the flanges, and connects these to the H profile. The fixing of the feed pipe to this profile portion positions the feed pipe in a central portion of the pile, which is advantageous during the ramming-in procedure of the pile.

For securing the feed pipe to the pile body, U clamps are advantageously provided, the free ends of which are guided through openings in a profile surface and are screwed thereon, and by means of which the feed pipe is held and fixed on the pile body.

Finally, according to a further advantageous embodiment of the invention, it is preferred that a distance a is provided between the front end and the peripheral material thickening on the pile foot, viewed in the longitudinal direction of the pile body, the following relationship preferably applying to said distance a: 5 cm < a < 100 cm, in particular 5 cm < a < 50 cm, preferably 15 cm < a < 25 cm. In a particular embodiment, this distance a can be 20 cm. In this manner, for the driven pile according to the invention which, as stated above, manages without a ramming shoe tapering into a cutting edge or into a point, a penetration region is provided which ensures the further penetration of the pile into the ground before the soil is further displaced by the peripheral material thickening to form the gap. This reliably allows a precise guidance of the pile with the formation of the gap.

The body of the driven pile according to the invention is formed in particular from steel.

Finally, the invention also provides a system comprising a driven pile having the characteristics described above, a pile driver, a suspension pressure pump having a high pressure suspension line for connection to the end of the feed pipe located in the region of the rear end of the pile body and a suspension of a hardenable material. A method of the type described at the outset for achieving the object can be implemented by means of this system. The suspension contained in the system is preferably a suspension of cement, fly ash and water and optionally further binders and/or concrete additives, such as liquefiers and/or retarders. The suspension pressure pump can advantageously convey and feed in a suspension of this type at a pressure of at least 10 bar, in particular at least 25 bar, in particular up to at least 100 bar through the high pressure suspension line and the feed pipe as far as the discharge opening thereof. Consequently, it has an appropriately adequately high compression capacity on its high pressure side.

Further advantages and features of the invention can be found in the following description of an embodiment with reference to the accompanying drawings, in which:

Fig. 1 is a sectional side view of a driven pile according to the invention in a segment next to the pile foot,

Fig. 2 is a plan view of the portion shown in Fig. 1, viewed from the left- hand side in Fig. 1,

Fig. 3 is a view of the driven pile from above along line E-E in Fig. 1 and 2,

Fig. 4 is a sectional view through the driven pile according to the sectional line and view line D-D in Fig. 1 and 2,

Fig. 5 shows a shoring example of driven piles according to the invention for securing an excavation pit located in the water region, and

Fig. 6 shows in diagrams a) to d) measured values for different parameters, as recorded during a ramming-in procedure of a pile according to the invention by the method of the invention.

The illustrations in the drawings are schematic and in particular merely serve to explain the essential features of the invention and are not necessarily true to scale.

The driven pile 1 shown in different detail views and sectional views in Fig. 1 to 4 is described first of all with reference to Fig. 1 to 4. The driven pile 1 has a body 2 which, as can be seen clearly in particular in Fig. 3 and 4, is in the shape of an H profile, also known as a double-T-profile or also as an I-profile. Here, the pile body 2 is formed from steel in a manner known per se.

In Fig. 1 and 2, of the pile body, only a portion comprising the front end 3 and a portion comprising the pile foot 4 opening out into the front end 3 are shown. The further longitudinal extent of the pile 1 which, overall, can have a length of several tens of metres, for example 30 m, up to 60 m or even more, is not shown here. Thus, the rear end, opposite the front end 3 in the longitudinal direction of the pile 1, with the pile head is also not shown. This pile head can be provided with reinforcements to reliably introduce the ramming impulses. A peripheral material thickening 5 which is positioned at a distance from the front end 3 and which leads to a local widening of the H profile can be seen in Fig. 1 and 2. This peripheral material thickening 5 has a thickness d by which it increases or reinforces the external dimensions of the H profile of the pile body 2 in the region in which it is applied. This material thickening 5 is formed by steel strips which are welded onto the pile body 2 and have a height h over which the material thickening 5 extends in the longitudinal direction of the pile body 2. The material thickening 5 is guided all around the H profile and it extends parallel to the front end 3 or runs substantially perpendicularly to the longitudinal extent of the pile body 2. The thickness d of the material thickening 5 is from 0.5 cm to at most 10 cm, advantageously from 0.5 cm to at most 5 cm, in particular from 1.5 cm to 2.5 cm and in this embodiment it preferably measures 2 cm. In this embodiment, the height h can be 5 cm, the distance a is in particular in a value range of from 5 cm to 100 cm, preferably 5 cm to 50 cm, in particular 15 cm to 25 cm and is more preferably 20 cm here.

It can also be seen here that the front end 3 of the pile 1 is of a "blunt" formation, i.e. it does not have a ramming shoe or a shape which is tapered into a point or cutting edge.

These drawings also show a feed pipe 6 which extends in the longitudinal direction of the pile body 2 and extends over the entire length of the pile 1, i.e. from the ramming head (not shown here) and rear end of the pile 1 into the region of the pile foot 4 and there it opens out into a discharge opening 7. In this embodiment, the feed pipe 6 consists of a hose which is stable under high pressure and is guided in one piece starting from the pile head along the pile body 2 as far as the pile foot 4. It is fixed on the pile body 2 by U-shaped retaining and clamping brackets 8 which are guided through openings in a profile portion and are secured and held on the side opposite the feed pipe 6 by screw nuts which are screwed onto the free ends of the brackets provided with corresponding threads.

In the embodiment shown, the feed pipe 6 is fixed approximately centrally on a central profile portion 9, the web, of the H profile which interconnects the two side profile portions 10, 11, the flanges.

On the lower portion thereof in the region of the discharge opening 7, the feed pipe 6 is formed by a fixed tubular portion 12 or is reinforced by a fixed tubular portion 12 of this type which is placed around the flexible hose to stabilise the sensitive region of the discharge opening 7. In addition, protective plates 13 which are attached in a roof-like manner are positioned over the feed pipe 6 in the region of the pile foot 4, also in a portion in which said feed pipe is still guided as a hose. These protective plates which are positioned in a roof-like manner are welded to the central profile portion and are also used to protect the feed pipe 6 in the region of the pile foot 4. Arranged opposite the discharge opening 7 and positioned closer to the front end 3 of the pile body 2 is a diversion console 14 which protrudes from the H profile, here from the central profile portion 9, by a greater amount than the peripheral material thickening 5. Viewed from the discharge opening 7 on the far side of the material thickening 5, the diversion console 14 is supported by guide and support plates 15 which, starting from a portion close to the front end 3 of the pile body 2, extend from a region relatively close to the H profile, more precisely to the central profile portion 3 thereof, extending obliquely outwards as far as the diversion console 13 and are connected to said console. These guide and support plates 15 additionally support the diversion console 14 against the stresses which will be described in greater detail in the following.

Furthermore, through-openings 16 can be seen in the region of the pile foot 4 which are arranged in a portion between the discharge opening 7, the feed pipe 6 and the peripheral material thickening 5 and are guided through the profile portions 9, 10, 11.

The driven pile 1, shown in Fig. 1 to 4, is used as follows:

The pile 1, leading with its ramming foot 4 and the front end 3, is driven into the subsoil or ground by ramming impulses which are applied to the pile head (not shown in greater detail here) and act in the longitudinal direction of the pile body 2. In so doing, the profile portions 9, 10, 11 equally cut a path into the subsoil with their front edges opening out into the front end 3. Due to the peripheral material thickening 5 which joins the pile foot 4 at a distance a from the front end 3, a gap surrounding the H-profile-shaped pile body 2 is excavated while the pile 1 is driven in, which gap substantially has a thickness of the amount d. During the driving-in procedure of the pile 1, this gap is filled with suspension which is injected into the gap under pressure via the feed pipe 6 and through the discharge opening 7, and it consists of a hardenable material, in particular a concrete mixture of a low viscosity of at most 250 mPa*s, more particularly at most 200 mPa*s or even less. The highly fluid hardenable material which is injected via the feed pipe 6 during the ramming procedure flows against the diversion console 14 under high pressure, these pressures typically amounting to 10 bar and more, and sometimes amounting to 100 bar at least temporarily during the ramming procedure. The diversion console 14 is additionally held by the guide and support plates 15 so that it does not break off due to the high pressure prevailing here. Diverted by the diversion console 14 and sealed downwards towards the front end 3 of the pile 1 by the material thickening 5, the suspension of hardenable material flows transversely to the longitudinal direction of the pile 1 and fills the gap. To facilitate distribution along the entire gap and to thereby promote filling of the gap with pressed-in hardenable material present as a suspension, the through-openings 16 are provided, through which this suspension can also spread and can fill all the spaces of the gap.

The diversion console 14 has a further function in addition to the impact deflection of the suspension of hardenable material impacting thereon under high pressure and leaving the feed pipe 6 through the discharge opening 7. It is used to divert soil which presses in the direction of the discharge opening 7, during the driving-in procedure of the pile 1, and to divert it away from the discharge opening 7. The guide and support plates 15 which assist with this diversion and promote the penetration of the diversion console protruding at a relatively great distance from the central profile portion 9 of the pile body 2 also perform a second function in this respect.

The pile 1 shown in Fig. 1 to 4 and described above is suitable in particular for use in soils of different constitutions. Thus, this pile can be driven into non-cohesive, e.g. sandy subsoils and can be successfully anchored therein in the same way as it can be introduced into cohesive, for example clay-containing soil layers and secured therein. The pile according to the invention is thus also suitable in particular for anchoring in subsoils which have alternating layers of both non-cohesive and cohesive soil material. Soil layers of the type which frequently occur in glacial geological portions, such as in the North German Plain, but also in regions of adjoining territories, for example in the Netherlands, could previously only be worked on with great difficulty to establish foundations using the known type of driven piles. To achieve correspondingly high tensile strengths in these regions, particularly long piles often had to be used, the driving procedure of which down to the required depths was always associated with considerable difficulties. With the design according to the invention, it is also possible for relatively short piles of a length of for example only 30 m to achieve high load strengths in difficult subsoils of this type. Thus, in tests, the inventors were able to achieve loading or bearing strengths of up to 8,000 kN, corresponding to approximately 800 t. The driven pile, designed as described above, is suitable both for anchoring vertically and for driving obliquely into the subsoil. Longer piles can also be produced, and thus foundations with driven piles designed thus of lengths of up to 60 m are possible with currently conventional devices.

Fig. 5 schematically shows an example of use of the driven piles according to the invention. This drawing shows an excavation pit B which projects below a water line WL and is shored up by sheet pile walls S. An excavation pit B of this type can be created for example in the field of port or sluice construction in natural or artificial watercourses for appropriate building operations. However, it can also be created in the field of civil engineering where high groundwater levels or building operations to be carried out to a particularly great depth in the ground necessitate excavation pits B of this type. It is thus known for example from the construction activity in the centre of Berlin which was carried out intensively after German reunification that extensive, deep excavation pits were excavated there which were used for construction work below the water level. Here, sheet pile walls S were initially also driven into the subsoil and were then secured against transverse loads with obliquely extending driven piles 1, as shown in Fig. 5, before the excavation pits were pumped until they were empty and drained in a subsequent step. Fig. 5 shows how additional piles 1 are anchored vertically and also transversely thereto in the bottom of the excavation pit B to further stabilise the building site. All these piles 1 can be, and advantageously are, the driven piles according to the invention shown in a detail view in Fig. 1 to 4.

To drive these piles 1 into the ground and to anchor them therein, as shown for example in Fig. 5, a method described above with reference to Fig. 1 to 4 and a corresponding system are used. For this purpose, in addition to the pile designed according to the invention, a pile driver (not shown in greater detail here) is required comprising a driven pile guidance means which also allows an oblique driving-in direction of the pile 1. Using this pile driver, which can exert appropriate ramming impulses on the head of the pile, the impulses exerted in the longitudinal direction of the pile 1 or of the body 2 thereof are transferred, thus ensuring that the pile 1 is driven in its longitudinal direction. Furthermore, in this system, a suspension pressure pump is required which can convey a suspension of a hardenable material, for example a concrete, thus for example a mixture of water, cement, fly ash, optionally further binders and optionally concrete additives, such as liquefiers and/or retarders, and can discharge it on a high pressure side under high pressure, in particular under a pressure which can be regulated, into a high-pressure suspension line which, for its part, can be connected in turn to the end of the feed pipe located in the region of the rear end of the pile body. In addition, an appropriate suspension of hardenable material is required, which in practice is stored in a storage container connected to the suspension pressure pump on the suction side.

When the piles 1 are driven into the subsoil, they can be driven over a first drive distance initially without the suspension being injected to prevent highly pressurised suspension from escaping or shooting out of the inlet site. Upon reaching a predetermined minimum depth, the procedure of injecting the suspension can commence. In so doing, the suspension is typically not always injected at a constantly high pressure, instead the injection pressure is typically kept at a minimum pressure of for example 10 bar or 25 bar or 50 bar and is sometimes higher, subject to the geological formations of the subsoil through which the discharge opening of the pile foot passes. If relatively greatly compacted layers and/or cohesive layers are present here, a higher injection pressure can be selected, typically a pressure of up to 100 bar. If layers of a relatively low compactness and/or non-cohesive or sandy layers can be found there, the injection pressure can be reduced to a pressure of almost 0 in an extreme case, for example in the case of purely organic soil layers such as subterranean layers of peat.

For quality control and to check the conformity of the retention of the pile in the ground with the previously calculated values, the course of the injection pressure and the course of the supplied volume of suspension is advantageously recorded, correlated with the advancing penetration depth of the pile into the subsoil to acquire data therefrom relating to the compression and also to draw conclusions about the structure of the subsoil. In particular if the pile is introduced into relatively deep layers, there are often no exact geological data, for example provided by means of drilling cores, cone penetration tests or similar exploration work, about the layers of soil found there. Thus, an objective of the corresponding monitoring procedure is in particular to confirm here the previously determined nature of the soil and profiling and to indicate differences.

Fig. 6 represents in the individual illustrations a), b), c) and d) four different diagrams with measured values for different method parameters which have been recorded during a ramming procedure of a pile according to the invention into the subsoil by the method of the invention. In diagram a), the driving-in depth of the pile is plotted in metres (from 0 m to 30 m, with whole metres in front of the colon and decimal places after the colon) on the vertical axis, and the injection pressure of the suspension of hardenable material is plotted in bar on the horizontal axis. In this case, the start of the vertical axis with 0 m does not correspond to the earth's surface at the driving-in site, but rather denotes a point located in the depth of the ground from which the supply of the suspension and the pressing-in of the space excavated around the pile profile starts.

It can be seen that, in this case, the method has been implemented with a set "normal pressure" of approximately 25 bar. Here, a drop in pressure to almost 0 bar in the region between the driving-in depths of 3 m and 4 m is an artefact determined by the system. In the region up to approximately 10 m driving-in depth, the foot of the pile passes through soil layers of mainly non-cohesive material, and therefore the suspension was only injected at the normal pressure of 25 bar as the minimum pressure. In the region between 10 m and 11m, the injection pressure initially increases in pronounced swings and then in a continuously abrupt manner and is regulated at 100 bar in the region between approximately 11 m and approximately 14 m. There, the ramming foot of the pile crosses a soil layer of cohesive material. The pressure increased due to the continued supply of the suspension by the suspension pump. At 100 bar, the system was regulated for safety reasons, as otherwise, with further increasing pressures, there was a risk of damage to the suspension lines and/or to the suspension pump. If this material had higher compressive strengths, it would be possible to operate at even higher pressures.

In the region between a ramming depth of approximately 14 m and 17 m, the pressure then slowly dropped away, but still remained above the value of the normal pressure for this portion, which was 25 bar. Between the ramming depth of 17 m and approximately 19 m, it was again possible to see a slight increase in pressure until at approximately 19 m, the pressure again increased abruptly to a pressure of 100 bar, at which the system was again regulated.

In the region between a ramming depth of approximately 14 m and 19 m, the soil layer was less cohesive or had a greater content of non-cohesive material, and therefore the injected suspension was able to penetrate more easily into the surrounding soil, and the pressure could fall. However, the layer in this region was still more resistant to penetration of the suspension than the soil layer at the start of the ramming in the region between the ramming depth of 0 m and approximately 10 m.

In the region between a ramming depth of approximately 19 m and approximately 23 m, the pile foot crossed a soil layer having characteristics similar to those of the layer in the region between a ramming depth of 11 m and 14 m, and therefore the high pressure level of the regulating pressure of 100 bar, set as the maximum possible pressure, was maintained.

In the last portion, there was an adjoining layer of non-cohesive material into which the pile foot was then driven in the region from a ramming depth of approximately 23 m to the final depth of 30 m and in which the pressure initially slowly dropped in a transition region between 23 m and 24 m and was then maintained at the normal pressure of 25 bar set here.

Here, it should again be stressed that the normal pressure can also assume a low value as long as this is at least temporarily at least 10 bar.

The diagram in illustration b) of Fig. 6 shows in a similar graph the throughflow amount of introduced suspension plotted in l/min on the horizontal axis, with the ramming-in depth plotted in metres on the vertical axis. It can be clearly seen that the course of the throughflow amount correlates with the pressure profile to the extent that in the regions in which the injection pressure increases, the soil has a low permeability, the throughflow amount of the suspension drops to a throughflow of zero. In regions in which the soil layer was formed from non-cohesive material, greater amounts of suspension were introduced per unit of time, since it could penetrate more effectively into the surrounding ground.

Diagram c) shows the ramming energy, applied during ramming, per driven-in metre in kJ/m on the horizontal axis, with the same depth course plotted along the vertical axis. This ramming energy is an indication of the soil composition of the layer crossed by the pile foot. A high ramming energy expended per driven-in metre is indicative of a layer having a high compactness, while low ramming energy to be expended per driven-in metre indicates a crossed layer having a low compactness. Thus, it can be seen here that the compactness increases significantly in particular in a ramming-in depth of from approximately 17 m.

The last diagram d) shows, plotted in l/m on the horizontal axis, the volume of suspension of hardenable material, introduced per rammed-in metre in the different ramming-in depths (the ramming-in depth is again plotted on the vertical axis with the same scaling as in diagrams a), b) and c)). This graph also shows a correlation with the courses of the pressure curve according to diagram a) and with the throughflow amount curve according to diagram b). Where the pressure was high and the throughflow amount of the suspension was low, the volume introduced per metre of drive length also decreases. The volume introduced per metre of drive length is a parameter of the method calculated in a previous model. Here, a volume of approximately 1.5 to 2.5 times the volume formed by the cross section of the pile in the region of the increased cross section with a corresponding drive is currently desired and predetermined as a benchmark.

List of reference signs 1 driven pile 2 pile body 3 front end 4 pile foot 5 material thickening 6 feed pipe 7 discharge opening 8 U-shaped retaining and clamping brackets 9 central profile portion 10 side profile portion 11 side profile portion 12 tubular portion 13 protection plate 14 diversion console 15 guide and support plates 16 through-opening a distance d thickness h height B excavation pit S sheet pile wall WL water line

Claims

1. Fremgangsmåde til at nedramme og forankre en piloteringspæl i jorden, hvor piloteringspælen har en pælfod i området af en forreste ende og et pælhoved i området afen bageste ende, hvor piloteringspælen, som i området af pælfoden har et tværsnit som er forstørret i forhold til tværsnittet af resten af piloteringspælen, drives ned i jorden ved påføring af ramningsimpulser som virker i dens længderetning på pælhovedet med pælfoden forrest, og ved at en suspension af et hærdbart materiale presses simultant via et rør som forløber ved piloteringspælen, til pælfoden ind i området i hvilket tværsnittet tilspidses i forhold til området med forstørret tværsnit i retningen af pælhovedet, hvor suspensionen har en dynamisk viskositet på højst 250 mPa*s, i særdeleshed ved højst 200 mPa*s, og mindst midlertidigt med et tryk på mindst 10 bar, fortrinsvis på mindst 25 bar, i særdeleshed presses med op til 100 bar.A method of ramming and anchoring a pilot pile in the ground, wherein the pilot pile has a pile foot in the region of a front end and a pile head in the region of the rear end, wherein the pilot pile, which in the region of the pile foot, has a cross-section enlarged relative to the cross-section of the remainder of the pilot pile, driven into the ground by applying ram pulses acting in its longitudinal direction to the pile head with the pile foot in front, and by simultaneously pushing a suspension of a curable material through a tube extending at the pilot pile into the pile foot said cross-section being tapered relative to the enlarged cross-sectional region in the direction of the pile head, the suspension having a dynamic viscosity of not more than 250 mPa * s, in particular at not more than 200 mPa * s, and at least temporarily with a pressure of at least 10 bar, preferably at at least 25 bar, in particular pressed up to 100 bar.

2. Fremgangsmåde ifølge krav 1, kendetegnet ved at suspensionen er en suspension af cement, flyveaske, eventuelt andre bindemidler og vand såvel som eventuelt betonadditiver, såsom flydemidler og/eller forsinkere.Process according to claim 1, characterized in that the suspension is a suspension of cement, fly ash, optionally other binders and water as well as optionally concrete additives such as flow agents and / or retarders.

3. Fremgangsmåde ifølge et hvilket som helst af de foregående krav, kendetegnet ved at piloteringspælen indføres i jorden over et første langsgående afsnit uden at trykke suspensionen ind, efter at have nået en forud indstillet initial dybde af nedramningsfoden indføres i jorden hvor suspensionen trykkes ind.Method according to any one of the preceding claims, characterized in that the pilot pile is introduced into the ground over a first longitudinal section without pressing the suspension, after reaching a preset initial depth of the ramming foot is introduced into the ground where the suspension is pressed.

4. Piloteringspæl med et pællegeme (2) dannet af en H-profil som har en pælfod (4) som munder ud i en forreste ende (3) af pællegemet (2) og et pælhoved afgrænset af en bageste ende af pællegemet (2), kendetegnet ved at der i området af pælfoden (4) langs overfladen af H-profilen i en retning vinkelret på den langsgående retning er en materialefortykkelse (5) som i det væsentlige er lukket om profilen og som strækker sig rundt på alle overflader, hvilken materialefortykkelse rager frem med en værdi d over den tilstødende flade af H-profilen, gældende 0,5 cm < d < 5 cm, og at et gennemgående tilførselsrør (6) løber i langsgående retning af pællegemet (2) begyndende fra pælhovedet til pælfoden (4) og er fastgjort på pællegemet (2), hvilket tilførselsrør i området af pælfoden (4) over materialefortykkelsen (5) munder ud i mindst en udledningsåbning (7).Pilot pile with a pile body (2) formed by an H-profile having a pile foot (4) leading to an anterior end (3) of the pile body (2) and a pile head bounded by a rear end of the pile body (2) , characterized in that in the region of the pile foot (4) along the surface of the H-profile in a direction perpendicular to the longitudinal direction is a material thickness (5) which is substantially closed about the profile and which extends around all surfaces, which material thickness protrudes with a value d over the adjacent surface of the H profile, applicable 0.5 cm <d <5 cm, and that a through-feed tube (6) runs in the longitudinal direction of the pile body (2) starting from the pile head to the pile foot ( 4) and is secured to the pile body (2), which supply pipe in the region of the pile foot (4) over the material thickness (5) opens into at least one discharge opening (7).

5. Piloteringspæl ifølge krav 4, kendetegnet ved at der for værdien d gælder at 0,5 cm < d < 10 cm, i særdeleshed 0,5 cm < d < 5 cm.Pilot pile according to claim 4, characterized in that the value d applies to 0.5 cm <d <10 cm, in particular 0.5 cm <d <5 cm.

6. Piloteringspæl ifølge et af kravene 3 eller 4, kendetegnet ved at en afledningskonsol (14) er tilvejebragt på pælfoden (4) i et afsnit modstående udledningsåbningen (7) i langsgående retning af pællegemet (2) i retningen af den forreste ende (3).Pilot pile according to one of claims 3 or 4, characterized in that a drain bracket (14) is provided on the pile foot (4) in a section opposite the discharge opening (7) in the longitudinal direction of the pile body (2) in the direction of the front end (3). ).

7. Piloteringspæl ifølge krav 6, kendetegnet ved at afledningskonsollen (14) er integreret i området af materialefortykkelsen (5) men rager frem med en større værdi end materialefortykkelsen (5) over den tilstødende flade af H-profilen.Pilot pile according to claim 6, characterized in that the drain bracket (14) is integrated in the region of the material thickness (5) but protrudes with a greater value than the material thickness (5) over the adjacent surface of the H-profile.

8. Piloteringspæl ifølge et af kravene 5 eller 6, kendetegnet ved lede- og støttestrukturer (15) forbundet med afledningskonsollen og som løber i langsgående retning af pællegemet (2) begyndende fra et område som vender mod den forreste ende (3) af pællegemet (2), skråtstillet op til afledningskonsollen (14).Pilot pile according to one of Claims 5 or 6, characterized by guide and support structures (15) connected to the drain bracket and running longitudinally of the pile body (2) starting from a region facing the front end (3) of the pile body ( 2), inclined up to the drain bracket (14).

9. Piloteringspæl ifølge et af kravene 4 til 8, kendetegnet ved gennemgangsåbninger (16) som strækker sig igennem områdeafsnittene (9, 10, 11) af H-profilen og anbragt i området af pælfoden (4), i særdeleshed i et langsgående afsnit af pællegemet (2) mellem udledningsåbningen (7) af tilførselsrøret (6) og den perifere materialefortykkelse (5).Pilot pile according to any one of claims 4 to 8, characterized by passage openings (16) extending through the area sections (9, 10, 11) of the H-profile and arranged in the region of the pile foot (4), in particular in a longitudinal section of the pile body (2) between the discharge opening (7) of the supply pipe (6) and the peripheral material thickness (5).

10. Piloteringspæl ifølge et af kravene 4 til 9, kendetegnet ved en fleksibel slangeledning som tilførselsrør (6).Pilot pole according to one of claims 4 to 9, characterized by a flexible hose line as supply pipe (6).

11. Piloteringspæl ifølge krav 10, kendetegnet ved at slangeledningen er forstærket i området af udledningsåbningen (7) med et rørformet afsnit (12) som omgiver den.Pilot pole according to claim 10, characterized in that the hose line is reinforced in the region of the discharge opening (7) with a tubular section (12) surrounding it.

12. Piloteringspæl ifølge et af kravene 4 til 11, kendetegnet ved at tilførselsrøret (6) er fastgjort på den centrale del (9) af pællegemet (2) som løber mellem de udvendige profilafsnit (10, 11) og forbinder afsnittene af H-profilen.Pilot pile according to one of claims 4 to 11, characterized in that the feed pipe (6) is fixed to the central part (9) of the pile body (2) which runs between the outer profile sections (10, 11) and connects the sections of the H profile .

13. Piloteringspæl ifølge et af kravene 4 til 12, kendetegnet ved at tilførselsrøret (6) holdes på pællegemet (2) ved hjælp af U-klemmer (8), hvor U-klemmernes frie ender er ført igennem åbninger i et profilafsnit (9) og påskruet dertil.Pilot pole according to one of claims 4 to 12, characterized in that the supply pipe (6) is held on the pile body (2) by means of U-clamps (8), the free ends of the U-clamps passing through openings in a profile section (9). and screwed thereto.

14. Piloteringspæl ifølge et af kravene 4 til 13, kendetegnet ved at der er en afstand a mellem den forreste ende (3) og den perifere materialefortykkelse (5) på pælfoden (4) i langsgående retning, hvor den har fortrinsvis 5 cm < a < 100 cm, i særdeleshed 5 cm < a < 50 cm, fortrinsvis 15 cm < a < 25 cm.Pilot pile according to one of claims 4 to 13, characterized in that there is a distance a between the front end (3) and the peripheral material thickness (5) of the pile foot (4) in the longitudinal direction, preferably having 5 cm <a <100 cm, in particular 5 cm <a <50 cm, preferably 15 cm <a <25 cm.

15. Piloteringspæl ifølge et af kravene 4 til 14, kendetegnet ved at pællegemet (2) er fremstillet af stål.Pilot pile according to one of claims 4 to 14, characterized in that the pile body (2) is made of steel.

16. System bestående af en piloteringspæl (1) ifølge et af de foregående krav 4 til 15, en pælnedrammer, en suspensionstrykpumpe med en højtrykssuspensionsledning til forbindelse med enden af tilførselsrøret (6) anbragt i området af den bageste ende af pællegemet, såvel som en suspension fremstillet af hærdbart materiale.A system consisting of a pilot pile (1) according to one of the preceding claims 4 to 15, a pile drummer, a suspension pressure pump with a high pressure suspension line for connection to the end of the supply pipe (6) arranged in the region of the rear end of the pile body, as well as a suspension made of curable material.