EP4314415A1

EP4314415A1 - Method for forming a wall structure in the ground by drilling and wall structure formed by drilling

Info

Publication number: EP4314415A1
Application number: EP22774403.4A
Authority: EP
Inventors: Juhani VÄLISALO
Original assignee: Pirkan Laatupalvelu Oy
Current assignee: Pirkan Laatupalvelu Oy
Priority date: 2021-03-25
Filing date: 2022-03-25
Publication date: 2024-02-07

Abstract

The invention relates to a method for forming a wall structure (10) in the ground (100) by drilling, wherein the wall structure (10) extends in contact with a body of water (111) in the form of a harbour structure (116), - a plurality of substantially vertical drill holes (12) are drilled next to each other so as to extend into the floor of the body of water (111) by a distance that is a partial length of the length of the drill pile (16), wherein the drill piles (16) are joined to one another by means of linking elements (14), - concrete (18) is poured into each drill pile (16) using the drill pile (16) as formwork, - at least a part of said adjacent drill piles (16) is raised at least partially out of the drill hole (12) after the pouring of the concrete (18) but before the concrete (18) sets, whereby the concrete (18) expands laterally into the ground (100) of the drill hole (12) and forms a continuous water-impermeable wall structure (10).

Description

METHOD FOR FORMING A WALL STRUCTURE IN THE GROUND BY DRILLING AND WALL STRUCTURE FORMED BY DRILLING

The invention relates to a method for forming a wall structure in the ground by drilling, wherein the wall structure extends in contact with a body of water in the form of a harbour structure, wherein

- a plurality of substantially vertical drill holes are drilled next to each other in the ground using a drilling apparatus utilizing a pilot bit and an reamer while simultaneously flush ing the drill hole with a medium so as to remove drilling debris from the drill hole and transporting into each drill hole behind the drilling apparatus a non-rotating drill pile provided with longitudinal linking elements, wherein the adjacent drill piles are joined to one another in a row by means of the linking elements so as to form a wall structure, the drill piles being smaller in diameter than the drill hole, and

- concrete is poured into each drill pile using the drill pile as formwork.

The invention also relates to a wall structure that can be formed by drilling.

A drill pile wall is a watertight retaining wall structure generally used in soft floor ground as well as frequently in non-cohesive soil. Drill pile walls are frequently constructed from drillable or percussable drill piles comprising steel linking elements for joining the drill piles to one another so as to form a retaining wall structure. The bottom end of the respective drill piles is usually supported by drilling the same into the bedrock. Drill piles provided with linking ele ments for drill pile walls and/or combiwalls are manufactured, for example, by SSAB, whose known drill piles comprising an interlock with the product designation RD RM/RF or E21 are suitable for the construction of drill pile walls. During the construction of a wall structure, SSAB's round drill piles are drilled into the ground, filled with concrete and finally sealed, for example along the RF interlock channel. A problem with such a structure is the expense of its construction, the cost of a completed width of wall structure amounting to several hundred euros and sometimes even more than 1000 euros per square metre of drill piles.

When building a drill pile wall in contact with a body of water or close to the shore, it is necessary to use drill piles that are very long so that the drill piles extend far enough into the ground for a sturdy mooring of the drill pile wall. This further increases the material costs in terms of drill piles. A further problem is that the drill piles adhere very poorly to the ground due to their slippery surface, which increases the need to drill the drill piles deeper into the ground formed by the floor of the body of water.

It is an object of the invention to provide a method for forming a wall structure in the ground in contact with a body of water body by drilling that is less expensive and more reliable than the methods of the prior art. The characteristic features of this invention are indicated in the attached patent claim 1. A further object of the invention is to provide a wall structure in contact with a body of water that can be formed by drilling that is less expensive and more reliable than the drillable wall structures of the prior art. The characteristic features of this invention are indicated in the attached patent claim 12.

This object can be achieved with a method for forming a wall structure in the ground by drilling, wherein the wall structure extends in contact with a body of water in the form of a harbour structure, in which method a plurality of substantially vertical drill holes are drilled next to each other in the ground using a drilling apparatus utilizing a pilot bit and an reamer while simultaneously flushing the drill hole with a medium so as to remove drilling debris from the drill hole and transporting into each drill hole in the wake of the drilling apparatus a non-rotating drill pile provided with longitudinal linking elements, wherein the adjacent drill piles are joined to one another in a row by means of the linking elements so as to form a wall structure, the drill piles being smaller in diameter than the drill hole. The linking elements are inter locking elements that bind the drill piles in alignment rela tive to each other in a transverse direction of the same, wherein one linking element is a long linking element that extends beyond the diameter of the reamer of the drilling ap paratus into the linking element of the drill pile in the adjacent drill hole and the other is a short linking element to which the long linking element of the adjacent drill pile connects. The drill holes are drilled so as to extend into the ground of the floor of the body of water by a distance that is a partial length of the length of the drill pile. In the method, concrete is also poured into each drill hole using the drill pile as formwork, reinforcements are installed in the concrete in the drill hole so as to strengthen the wall structure, and at least a part of the adjacent drill piles is raised at least partially out of the drill hole by at least a part of the length of the drill hole in the area of the ground of the floor of the body of water after the pouring of the concrete but before the concrete sets whereby the fluid concrete paste becomes rigid. The concrete compacting into concrete piles in each drill hole thereby expands laterally into the concrete of the adjacent drill pile as well as into the ground of the drill hole and forms a continuous water-impermeable wall structure with the concrete piles of the adjacent drill holes. The drill pile remains part of the wall structure in the part above the ground in the body of water.

Advantages of the method according to the invention are its excellent economic efficiency and good final result in terms of the wall structure. By raising at least a part of the drill piles at least partially out of the drill holes, the concrete poured into the drill piles is able to expand in the drill hole in contact with the ground, thus forming a strong bond between the wall structure and the ground. At the same time, the raised drill piles remain so as to form a durable and tight structure against the water of the body of water on the side above the ground. Moreover, the drill piles serve as a structure in which attachments for additional structures can be readily provided. The cost of the reinforcements left in the wall structure is only a fraction of the cost of the drill piles. Moreover, the method according to the invention provides a very strong and advantageously watertight wall structure that is easy to con struct even in hard ground unlike excavation piles. Pile-driv ing with a drillable pile is also less expensive in soft ground than drilling an excavation pile or building a so-called "se cant" excavation pile wall with excavation piles. With the method according to the invention, the linking elements used in the drill piles ensure a correct spacing of the holes in drilling operations extending up to a depth of 50 m and in which it would be very difficult, if not impossible, without the linking elements to align the drill piles with sufficient precision so as to obtain a watertight and continuous wall structure.

With the method according to the invention, it is not necessary to drill into the bedrock, as the concrete pile embedded in the ground in the wall structure is fixed directly to the ground via its outer surface and does not migrate downwards under the force of gravity or rise upwards under the influence of waves. The pile walls according to the prior art must be drilled into the bedrock or otherwise anchored in the ground or in backfill transported to the other side of the wall structure because, with the drill piles according to the prior art which extend over the entire height of the wall structure, their slipperi ness causes the drill pile to migrate downwards due to the force of gravity if the drill piles are not supported from below by bedrock, or to rise upwards if the drill piles are not securely anchored.

In other words, the drill piles are used in the method as an temporary formwork in the manner of excavation piles in the foundational part of the wall structure that remains embedded in the ground under the body of water. By means of the drill piles, a reliable and robust formwork is thus provided in a convenient manner for the part of the wall structure to be cast while the formation of a watertight concrete wall structure is rendered possible in an inexpensive manner even below the sur face of the floor of the body of water, where pouring concrete without a formwork structure would be impossible. Moreover, the method according to the invention is considerably simpler to use than excavation piles with which the number of method steps required for the construction of a single excavation pile is considerably larger.

Ground in this context is understood merely as stable ground in its original state under the body of water, for example moraine. The ground material heaped on the other side of the wall structure following the formation of the wall structure, on the other hand, or the temporary backfill on the stable ground from the body of water, is commonly called backfill. In the method, the part of each raised drill pile that extends beyond the concrete pile is preferably cut off. By reusing the cut-off parts of the drill piles, it is possible to save on material costs in the construction of the wall structure.

The part to be cut can be 0 - 10 m in length. The part to be cut can thereby be utilized for some other purpose, for example joined to another cut part.

Preferably, after the raising of the drill piles, an amount of concrete equivalent to 1 - 25% of the amount of concrete already poured into the drill pile is added into the drill pile. This enables a sturdier wall structure.

The length of the drill pile that remains in the wall structure is preferably 3 - 15 m. The wall structure can thereby be employed in most bodies of water.

The aforementioned partial length can be 10 - 90 %, preferably 15 - 30 %, of the length of the drill pile. The wall structure is thereby able to adhere to the ground over a section that is long enough to ensure the stability and immobility of the wall structure.

Preferably, the drill piles are raised by at least 1 m in order to allow the concrete to spread and at most by a length such that the drill pile remains in the ground in the drill hole so as to protect the concrete pile from the open water. A minimum lift of 1 m ensures that a sufficiently large contact surface area is created in the wall structure between the concrete piles and the ground in order to ensure a reliable fixation of the wall structure. Moreover, by leaving a sufficient amount, preferably at least 3 m, of the drill pile in the ground in the drill hole, it is possible to ensure that the movement of the water in the body of water does not erode the ground around the drill pile and come into direct contact with the concrete piles, which would compromise the durability of the wall structure.

In the method, the drill piles are preferably drilled until non-cohesive soil is reached. Non-cohesive soil fixates the bottom edge of the structure in position, which prevents move ments of the topsoil layers from being able to move the struc ture in a horizontal direction.

The drill piles are drilled 4 - 15 m, preferably 5 - 10 m, into the ground in order to fixate the wall structure in the stable ground. It is thereby possible to ensure that the concrete piles to be formed in the ground in the wall structure have a sufficiently large bonding surface area with the ground in order to provide a sturdy fixation of the wall structure. More over, this ensures that the wall structure has a sufficient flexural strength.

According to one embodiment of the method, it is possible to drill the adjacent drill holes so that the cross-sections of the adjacent drill holes intersect at at least one point, thus allowing the linking elements of the drill piles to be connected to one another. At the same time, the concrete that fills the adjacent drill holes joins the concrete piles to one another, thus producing a watertight structure in an economical manner. Alternatively, the drill holes can be tangent to one another, without intersecting, in which case the thin layer of ground left between the drill holes is broken up by pushing by means of the linking element during the installation of the drill pile.

The drill hole can be 200 - 2000 mm, preferably 600- 1200 mm, in diameter. With a diameter of the drill hole of this magnitude, it is possible to arrange an adequate number of reinforcements in the drill hole in order to render the struc ture strong enough to withstand the forces acting on it.

The drill pile is preferably carried in the wake of the drilling apparatus by pulling or pushing by means of a carrying shoulder structure. The drill pile can thus be guided into the hole without rotation.

In the most preferable embodiment of the method, the drill piles are flushed using water as the medium, which conducts the drilling debris upwards and out of the drill pile. Flushing with water causes very little stress on the ground surrounding the drill hole. In addition, the interior of the drill pile is kept clean.

In an alternative embodiment of the method, the drill piles are flushed using water as the medium, which conducts the drilling debris upwards inside the drill pile. Flushing with water causes very little stress on the ground surrounding the drill hole.

In a further alternative embodiment of the method, the drill piles are flushed using air as the medium, which conducts the drilling debris upwards inside the drill pile.

In a preferable embodiment of the method, protruding supports are welded, before the drill pile is drilled into the ground, to the end of each drill pile that enters the drill hole first, wherein the protruding supports are welded to the side of the drill pile facing the already drilled adjacent drill hole, respectively on the same side with respect to the point of intersection with the adjacent drill hole in order to support the drill pile during its movement into the drill hole by means of the protruding support so as to keep the drill pile straight during drilling. When a drill hole is drilled next to an ex isting drill hole, a sector of the reamer of the drilling apparatus can rotate in the pre-existing drill hole so that no resistance to forward progress is met at that point. Most of the reamer, however, works against the ground, which resists the forward progress of the bit of the drilling apparatus. As a result, the drill pile being pulled behind the drilling ap paratus can veer towards the adjacent drill hole, especially during the drilling of a section of bedrock. By means of the protruding supports, the drill pile can be supported against the intact ground, for example bedrock, whereby the drill pile is unable to incline towards the adjacent drill hole but rather progresses straight ahead.

According to a first embodiment, the linking elements of each drill pile include male linking elements or female linking elements or both, wherein the female linking elements are di mensioned to be partially loose relative to the male linking elements, thus leaving an open space in the female linking element for the injection of a medium. In the method, concrete is injected via the female linking element into the drill hole at the same time as each drill pile is being raised preferably under vibration out of the drill hole, thus ensuring that the concrete piles in the adjacent drill holes are joined to each other following the raising of the piles so as to form a single water-impermeable wall structure. It is thus possible to ensure the tightness of the wall structure by injecting concrete to a point in the wall structure that would otherwise be the weakest. The connecting surface area between concrete piles drilled next to each other can be kept as small as possible so that the effective dimensions of the concrete piles in the wall struc ture are as large as possible, since the tightness of the joints between the concrete piles can be ensured by means of the injection. According to another embodiment of the method, an injection tube is joined to the outer surface of each drill pile using fixation means in order to fix the injection tube to the bottom of the drill hole, while utilizing the mass of the concrete poured in addition to the fixation means, and a sealant is injected into the drill hole after the raising of the drill pile in order to ensure the tightness of the wall structure. It is thus also possible to ensure the tightness of the wall structure using a separate injection tube, which is less prone to clogging than female linking elements.

In an alternative embodiment of the method, at least one hollow reinforcement with a reserve pipe inside is installed with the reinforcements, which hollow reinforcement is left empty during the pouring of the concrete. The reserve pipe permits an in jection of, for example, a sealant in order to improve the tightness of the wall structure or a follow-up drilling via the reserve pipe.

The reinforcements are preferably installed inside the drill piles before the concrete is poured, whereby they are easy to install.

Reinforcements are preferably arranged inside each drill pile. This yields a very strong wall structure.

Alternatively, the reinforcements can be vibrated into the al ready poured concrete in the drill piles. This approach can require special arrangements for the pushing of the reinforce ments.

The reinforcements are preferably rebars. Rebars provide the concrete pile with a very high strength at a very low cost. Alternatively, the reinforcements can be, for example, compo site reinforcements, fibre composite reinforcements, fibre re inforcements or other reinforcement structures suited to the application.

In the method, following the raising of the drill piles, a transverse support structure can be installed between the con crete piles by vibration for the reinforcement of the wall structure.

According to one embodiment, vibration can be employed to re deploy the reinforcements installed obliquely in the drill pile as transverse reinforcements.

Alternatively, the transverse support structure can also be, for example, a steel rebar to be installed transversely between the vertical reinforcements in the wall structure.

According to one embodiment of the method, oblique reinforce ments are employed, which are installed at an angle of 45° - 70° relative to the longitudinal direction of the drill piles in the longitudinal direction of the wall structure prior to the pouring of the concrete, which oblique reinforcements are installed in the interstice between the drill piles of the wall structure in part by the action of the pressure caused by the pouring of the concrete as well as preferably under vibration. It is thereby possible to reinforce the wall structure at the part of the wall structure between the concrete piles.

According to one embodiment, a thickness of a steel rebar used for the rebars acting as reinforcements can be 10 - 25 mm, preferably 12 - 18 mm. This provides the structure with an adequate strength. Preferably, all drill piles are filled with concrete before the drill piles are raised. This allows the concrete of adjacent drill piles to spread and merge before the concrete sets or before the cement paste hardens to a state in which the fluid paste becomes rigid.

According to one embodiment, the reinforcements include verti cal reinforcements and spring reinforcements connected to the vertical straight reinforcements, the spring reinforcements be ing adapted to be compressed inside the drill pile and to deploy in a substantially transverse direction of the drill piles as well as in a longitudinal direction of the wall structure during the raising of the drill pile in order to reinforce the wall structure. Such a structure ensures that the wall structure ultimately also has reinforcements between the vertical straight reinforcements, where an installation of rebars in the context of an installation of drill piles is otherwise not possible.

Preferably, all drill piles are raised by at least a part of the length of the drill hole in the area of the ground of the floor of the body of water. This minimizes the consumption of drill piles and at the same time ensures that, at least along a part of the height of the wall structure, the concrete piles are in direct contact with the ground so as to fix the wall structure in the ground.

Preferably, the drill piles are raised by vibration so that the concrete in the concrete piles is compacted as a result of the vibration. This is the most cost-efficient and easiest way to raise the drill piles out of the drill holes while the vibration simultaneously optimizes the sealing of the concrete. The frequency of the vibration during the raising of the drill piles can be 33 - 45 Hz. The vibration occurring at this fre quency is optimal in terms of concrete compaction and provides a watertight concrete pile as the concrete hardens. As the frequency decreases, the wavelength acting on the ground in creases along with the force, i.e. the vibration of the concrete can be carried out at a desired force in order to achieve the best results and concrete permeation.

Alternatively, the drill piles could be raised with a large force without vibration provided that an integrated or separate layer of friction-reducing material is employed on the inner surfaces of the drill piles between the concrete and the drill pile.

According to an embodiment of the method, a liquid lubricant is fed into the drill hole on the outside of the drill pile between the drill hole and the drill pile in order to reduce the friction between the drill pile and the drill hole. Water or some other liquid lubricant reduces the friction between the drill pile and the drill hole during lifting and thereby fa cilitates the raising of the drill piles from the drill holes in the upward direction. Especially when drilling types of rock like limestone or volcanic rock, the rock is ground into fine grains during drilling and, when it reacts with moisture, tends to harden like concrete on the surface of the drill pile, which interferes with drilling and the raising of the drill piles. For these operations, the feeding of a liquid lubricant is particularly important.

The liquid lubricant is preferably water, but can also be a mixture of water and a polymer or, for example, bentonite. Water is naturally the most advantageous option in terms of its price. The liquid lubricant can be fed into the drill hole via a separate channel attached to the outer surface of the drill pile or via the female linking element of the drill pile. The use of a separate channel is possible because the diameter of the drill pile is smaller than the diameter of the drill hole so that space is left between the drill pile and the drill hole for a separate channel.

The drill piles can also be raised hydraulically by means of a cylinder. This is standard practice for raising drilling equip ment.

The drill piles are preferably raised in the order of concret ing. The concrete is thus prevented from having the time to bond to the drill piles that were concreted first before the raising of the drill piles, which facilitates the raising of the drill piles.

Partially raising in this context is understood as raising the drill pile by at least 0.5 m or more, and does not mean, for example, the back-and-forth movement potentially caused by per cussion drilling.

According to one embodiment, following the raising of the drill piles and the hardening of the concrete pile, a sealant is fed via the aforementioned reserve pipe in order to ensure the tightness of the wall structure. It is thereby possible to ensure that no cracks or other analogous untight points remain in the hardened concrete pile.

A hardening of the concrete in this context is understood as a hardening of the concrete to at least 60% of its final strength. According to an embodiment of the method, at least one protrud ing plough element is respectively welded, prior to the drill ing of the drill pile into the ground, to the end of the drill pile that enters the drill hole first next to the linking element, which protruding plough element is continuous over a sector of the outer circumference of the drill pile and pro trudes from the drill pile by at most the same distance as the reamer used in the drilling apparatus, the protruding plough element dislodging the ground during the raising of the drill pile in order to optimize the joining of the concrete piles. The protruding plough element thus "ploughs" the ground in front of it to the side, thus widening the connection between two adjacent drill holes and enabling an efficient spreading of the concrete from one drill hole to the other, thereby connecting the adjacent concrete piles to one another in an effective manner. At the same time, the protruding plough ele ment can create a negative pressure in its wake as the concrete surrounds it and fills the space left in the drill hole by the drill pile during the raising and vibration of the drill pile. The negative pressure for its part effectively sucks concrete into the space between the drill holes, thereby joining the concrete piles.

According to one embodiment, there are two protruding plough elements, one fixed on either side of a sole linking element or more or less fixed in said linking element.

According to an embodiment of the method according to the in vention, drill piles are used in which protruding plough ele ments are attached on either side of each linking element.

According to one embodiment, the protruding plough elements are welded structures made of steel plate and comprising two ends, of which a first end is fixed or is more or less fixed in the linking element and the other end is fixed further away from the linking element, the first end being further away from the end of the drill pile which is connected to the bit of the drilling apparatus and the other end being closer to said end of the drill pile. In other words, the protruding plough ele ments form a wedge-shaped plough in the direction of the raising of the drill pile. A protruding plough element in the form of a plough causes less drag against the ground during the raising of the drill pile.

Alternatively, the protruding plough element can also be, for example, an encased structure.

According to one embodiment, a separate intermediate linking element which forms two female linking elements is used between the drill piles for attaching the drill piles to each other, wherein the drill piles comprise only male linking elements. In this case, every drill pile can be symmetrical.

Preferably, a short linking element and a long linking element are arranged on opposite sides of the drill pile with respect to one another in order to maximize the progression of the wall structure. Fewer drill holes and linking elements are required for a desired wall-structure length in this manner than if the linking elements were formed differently.

The wall structure can be formed in casting sections consisting of 2 - 100, preferably 5 - 50, drill piles before the raising of the drill piles. It is thereby possible to produce a maximum length of the wall structure before the drill piles have to be raised before the concrete sets.

The length of a linking element of the drill piles used to form the wall structure is 3 - 50% of the diameter of the drill pile. The interstice between drill piles is thus not too long, which would weaken the wall structure as a whole.

Preferably, the diameter of the drill hole is 100 - 120% of the combined diameter of the drill pile and the corresponding link ing element. The drill pile is thus firmly installed in the drill hole and the concrete placed inside the drill pile fills the drill hole following the raising of the drill pile.

According to one embodiment, a retardant is used in at least a part of the concrete piles to be cast in order to delay the setting of the concrete. By using a retardant, the wall struc ture can be constructed in longer casting sections at a time. Moreover, a retardant can be used, for example, in the last drill pile of a casting section, wherein said last drill pile is optionally not raised until casting of the subsequent cast ing section, which is attached to the drill piles of the pre ceding casting section, has begun. The parts of the wall struc ture formed in the casting sections can thereby by joined to gether in a reliable manner.

The concrete used can have a consistency of S2 or S3 according to the BY50 standard, whereby it is easy to pump and allows reinforcements to be embedded after the pouring of the concrete. Moreover, the concrete is pliable enough that the raising of the drill piles can occur readily.

In the method, it is possible to provide a transverse support beam in a bare wall structure on a side of the wall structure under construction. For example, a building can thereby be attached by means of the support beam to the wall structure and, via the wall structure, to the ground. The wall structure can be anchored in a stable layer of the ground on the opposite side of the wall structure relative to the transverse support beam. The anchoring makes it possible to ensure a stable structure of the wall structure in all situations in a manner known in the prior art.

In a preferred embodiment of the method, drill piles with link ing elements which interlock based on shape in the transverse direction of the drill pile are employed. The linking elements thereby keep the drill piles precisely aligned with one another, which renders the wall structure durable and compact.

In a preferred embodiment of the method, drill piles are em ployed the linking elements of which include a stem part ex tending in a radial direction of the drill pile and comprising a first end and a second end, wherein the first end is attached to the drill pile and a hooked interlocking part is attached to said second end. By means of such linking elements, it is possible to provide the drill pile with a transverse shape based interlocking support while still allowing the drill piles to be installed with precision in the longitudinal direction.

The hooked interlocking part can include an interlocking arm which projects at an angle relative to the stem part from the second end of the stem part back towards the drill pile, thus forming a shape based interlocking structure.

In a preferred embodiment of the method, at least a part of the drill piles is raised at least partially, which causes the concrete inside the drill piles to spread into the drill hole, the drill piles are pushed back into the drill hole, whereby the lower end of the drill pile is partially embedded in the concrete such that the concrete provides a sealing between the drill pile and the drill hole. At the same time, a contact surface between the lower end of the drill pile and the ground material of the drill hole is also provided via the concrete.

The object of a wall structure according to the invention can be achieved with a wall structure that can be formed by drill ing, said wall structure comprising a plurality of adjacent concrete piles joined to one another as well as to a stable layer of the ground, said concrete piles including reinforce ments installed in the interior of the concrete piles and having a cross-sectional shape that is substantially circular, wherein the concrete piles form an outer surface of the wall structure over at least a portion of the height of the wall structure and each concrete pile has an outer surface. The length of the portion is at least 1 m and at most such that the drill pile remains in the ground in the drill hole so as to protect the concrete pile from the open water. At the part of the wall structure that extends into the ground, each concrete pile is connected by a fully integrated concrete structure to each adjacent concrete pile by a sector of 1° - 50°, preferably 5° - 15°, of the cross-section of the concrete pile, the concrete structure having a contact surface formed on its outer surface on both sides of the wall structure in direct contact with the stable layer of the ground, said contact surface being inte grated in the stable layer of the ground. At the part of the wall structure above the ground, drill piles attached to each other by means of linking elements form the outer surface of the wall structure, while the concrete piles respectively run continuously inside the respective drill piles. The linking elements are interlocking linking elements that bind the drill piles in alignment relative to each other in a transverse di rection of the same, wherein one linking element is a long linking element that extends beyond the diameter of the reamer of the drilling apparatus into the linking element of the drill pile in the adjacent drill hole and the other is a short linking element to which the long linking element of the adjacent drill pile connects. The wall structure further includes a substan tially transverse harbour structure formed at the upper end of the drill piles.

This type of structure is less expensive to produce since fewer expensive drill piles remain in the completed wall structure and, moreover, the fixing of the wall structure to the ground can be brought about effectively by means of concrete piles without a separate anchoring or at least using less anchoring. In the wall structure according to the invention, the connect ing surface area between adjacent concrete piles is considera bly smaller than in wall structures according to the prior art and is always the same, i.e. constant, thanks to the linking elements utilized by the drill piles. Due to the small connect ing surface area, the effective dimensions of the concrete piles in the wall structure are large and the wall structure can be formed with less drilling than with wall structures of the prior art. As a result of the contact surface in direct contact with the ground, the wall structure does not need to extend into the bedrock since the contact surface fixes the wall structure to the surrounding ground, thus preventing it from migrating downwards or rising upwards.

An interlocking linking element in this context is understood as a linking element that binds adjacent drill piles to one another in a transverse direction of the drill piles so that the respective positions of the drill piles are constant rela tive to each other over the entire length of the drill piles. Moreover, the interlocking linking element makes it possible to slide the drill piles into position relative to each other in the longitudinal direction of the drill pile. A harbour structure in this context is most preferably under stood as a wharf structure, but can also be understood as other supporting structures located in a harbour on top of which a separate end structure can be built.

Preferably, the harbour structure includes the necessary means for mooring a vessel. Such means can include at least mooring posts for mooring vessels.

The wall structure preferably has two sides, wherein there is ground over the entire height of the wall structure on one side and open water over at least a part of the height of the drill piles on the other side.

The aforementioned contact surface is preferably formed on the outer surface of the concrete pile directly against the inner surface of the drill hole, the inner surface being formed by means of the reamer of the pilot bit of the drilling apparatus and the flushing of the drilling apparatus during drilling. Due to the rotary motion and the flushing of the reamer of the drilling apparatus, the inner surface of the drill hole is porous and thereby forms a large contact surface area for the contact surface of the concrete pile spreading against it. No such surface occurs, for example, with percussion piles or secant piles because in these methods the drill pile is driven or pushed into the ground, thereby creating around the drill pile a compacted layer of ground material into which the ground displaced by the drill pile is compacted while both the contact surface area and the coefficient of friction between the ground material and the contact surface of the concrete pile are re duced. In addition, the ground material is removed in these methods at the site of the percussion piles and secant piles from inside the pile by means of an auger drill without flushing. Instead, the drill piles are so-called non-displace ment piles.

In other words, in the wall structure according to the inven tion, the concrete piles have a contact surface that is in contact with the essentially natural and uncompacted ground material of the drill hole, which increases the contact surface area and thus the strength of the bond. To put it another way, the ground material on the inner surface of the drill hole is not disturbed.

By an integrated concrete structure in this context, it is understood that the concrete of adjacent concrete piles merges to form a continuous concrete structure.

By an integration of the contact surface in a stable layer in this context, it is understood that the concrete, as it hardens, bonds directly with a stable layer of the ground, thus fixing the wall structure in place so that the wall structure cannot migrate downwards or rise upwards like a slippery wall struc ture made of drill piles.

In other words, the wall structure according to the invention preferably consists, with respect to its portion that remains in the ground, predominantly of adjacent concrete piles and reinforcements arranged inside at least one concrete pile, and, with respect to its part above the ground, of a structure formed from drill piles which contain the concrete piles and their reinforcements.

In other words, the concrete piles of the wall structure are in direct contact with the ground. In the method, the concrete thus bonds firmly to the ground along the entire length of the concrete pile. The portion is preferably at least 1 m in length and at most such that the drill pile remains in the ground in the drill hole so as to protect the concrete pile from the open water. The drill pile is thus raised far enough so as to allow the concrete to come into contact with the ground while enough of the drill pile remains inside the ground so as to prevent water from coming into contact with the concrete piles.

The volume of the wall structure can be 1 - 25% greater after the raising of the drill piles than the volume of the wall structure before the raising of the drill piles. The larger amount of concrete renders the wall structure sturdier.

The stable layer of the ground preferably serves as formwork for the part of the wall structure consisting of concrete piles.

The wall structure is preferably watertight. This is achieved by vibration by means of the raisable drill piles, which compact the concrete watertight.

The concrete piles of the wall structure are preferably in one row. The length of the wall structure can thus be maximized with a minimum number of concrete piles. This is possible due to the use of drill piles provided with linking elements, as the concrete piles can thereby be formed at a correct distance from one another with sufficient accuracy to form a continuous and durable wall structure.

According to one embodiment, the linking elements of the drill piles include male linking elements protruding from the main shape of the drill pile and female linking elements attached to the male linking elements by welding. The male linking ele ments preferably form part of the internal volume of the drill pile. The width of the male linking element can be 20 - 50% of the diameter of the drill pile. A very sturdy wall structure is achieved with this type of drill pile while the interstices between the drill piles are also quite thick and sturdy.

A diameter of the concrete pile can be 200 - 2000 mm, preferably 600 - 1200 mm. A concrete pile diameter of this magnitude allows a sufficient number of reinforcements to be arranged in the concrete pile so as to render the wall structure strong enough to withstand the forces acting on it.

The wall structure can be 1 - 50 m, preferably 5 - 30 m, most preferably 20 - 30 m, in height depending on the drilling equipment used.

As reinforcements, the wall structure preferably includes ver tical reinforcements and oblique reinforcements, which are ar ranged at an angle of 45° - 70° relative to the longitudinal direction of the drill piles in the longitudinal direction of the wall structure prior to the pouring of the concrete, the oblique reinforcements being installed in the interstice be tween the drill piles of the wall structure in part by the action of the pressure caused by the pouring of the concrete. This makes it possible to reinforce the wall structure with respect to the part of the wall structure between the concrete piles.

As reinforcements, the wall structure preferably includes ver tical reinforcements and transverse reinforcements, which tie together the vertical reinforcements in the different concrete piles in order to strengthen the wall structure. By means of the transverse reinforcements, it is possible to achieve a strong wall structure even if the drill piles were to be removed entirely. According to one embodiment, the transverse reinforcements are spring reinforcements connected to the vertical reinforcements, the spring reinforcements being adapted to be compressed inside the drill pile and to deploy in a substantially transverse direction of the drill piles as well as in a longitudinal direction of the wall structure in order to reinforce the wall structure during the raising of the drill pile. The spring reinforcements can be installed simultaneously with the instal ment of the reinforcements, whereby their installation does not require a separate step following the pouring of the concrete.

According to a second embodiment, the transverse reinforcements are reinforcements deployable by means of vibration, which are installed inside the drill pile prior to the pouring of the concrete. This type of transverse reinforcement does not need to be welded to the vertical reinforcements nor is a separate step required to place them in their operational position in cases where the drill pile is raised by vibration.

According to a third embodiment, the transverse reinforcements are reinforcements that can be embedded in the poured concrete by vibration.

The concrete of the concrete piles can be ordinary concrete reinforced with separate reinforcements or, alternatively, macrofibre or steel fibre concrete in which macrofibres or steel fibres form at least a part of the reinforcements. Macro fibre concrete is understood to mean concrete containing an even distribution of plastic fibres in lengths of 10 - 50 mm, depending on the type of fibre. Steel fibre concrete is under stood to mean concrete containing an even distribution of small pieces of steel wire, which can be, for example, 25 - 60 mm in length and 0.4 - 1.05 mm in diameter. The drill pile is preferably circular with respect to its cross- section in both the method and the wall structure according to the invention, whereby a hollow volume is provided in its in terior for the concrete and the reinforcements. The drill pile thus functions as an ad hoc formwork in the method according to the invention in order to form the concrete piles of the wall structure according to the invention at the part of the wall structure that extends into the ground.

According to one embodiment, the wall structure includes a transverse support beam joined to the outer surface of the concrete piles in the bare wall structure on a side of the wall structure under construction.

The wall structure can include anchors in order to anchor the wall structure in a stable layer of the ground on the opposite side of the wall structure relative to the transverse support beam.

According to one embodiment, the wall structure includes a sealing formed by the concrete between the drill pile and the drill hole, which is produced by raising the drill pile and pushing the drill pile back into the concrete. This improves the attachment of the drill pile to the ground.

The aforementioned seal can be formed over a length of 30 - 300 cm at the lower end of the drill pile.

Advantageous applications of the method and wall structure ac cording to the invention include retaining wall structures, building foundations, parking garages, docks, road and railway structures, bridges and the containment of contaminated ground material (so-called cutoff walls). The invention is illustrated in the following in detail with reference to the attached drawings illustrating embodiments of the invention, wherein

Figure la shows a first step of the method according to the invention in which a drilling apparatus is supported on a drilling platform,

Figure lb shows a second step of the method according to the invention in which a drill pile is drilled into ground under water by means of the drilling apparatus,

Figure lc shows a third step of the method according to the invention in which the drill pile is drilled into the ground under water and the drilling apparatus is raised out of the drill pile and drill hole,

Figure Id shows a fourth step of the method according to the invention in which reinforcements are in stalled inside the drill pile and the drill pile is filled with concrete,

Figure le shows a fifth step of the method according to the invention in which the drill pile is raised upwards by means of the drilling apparatus,

Figure If shows a sixth step of the method according to the invention in which the part of the drill pile that extends beyond the concrete pile is cut off and the land-facing wall of the wall structure is filled with backfill,

Figure lg shows an alternative situation to the one shown in Figure lc in a second step of the method according to the invention in which the drill pile is drilled into the ground under water and the drilling apparatus is raised out of the drill pile and drill hole, the drilling being carried out from a backfill,

Figure 2a shows a step of the method according to the invention in which a drill hole is drilled in the ground and a drilling apparatus pulls a non rotating drill pile into the drill hole in its wake,

Figure 2b shows a step of the method according to the invention in which a wall structure is extended by drilling adjacent drill holes and installing in the drill holes adjacent drill piles inter locked by means of linking elements,

Figure 2c shows a step of the method according to the invention in which rebars are installed inside the drill piles arranged in the drill holes,

Figure 2d shows a step of the method according to the invention in which concrete is poured into the drill piles arranged in the drill holes,

Figure 2e shows a step of the method according to the invention in which the drill piles are raised upwards from the drill holes by vibration,

Figure 3 shows an axonometric view, with the ground in front of the structure removed, of a completed wall structure according to the invention,

Figure 4 shows an embodiment of a drilling apparatus used in the method as a whole,

Figures 5a - 5e show a wall structure of a pilot bit according to an embodiment of the drilling apparatus used for drilling the drill piles as well as steps of the method in cross-sectional views,

Figures 6a and 6b show different linking elements between the drill piles, Figure 7 shows a supplemental sealing of the wall struc ture according to a further embodiment in a view from above,

Figure 8 shows an embodiment of the wall structure in which the rebars include a hollow rebar and a reserve pipe,

Figure 9 shows an embodiment of the method in which the outer surface of the drill pile includes a sep arate channel for feeding a liquid lubricant,

Figures 10a and 10b show a wall structure in which anchor bolts are used for attachment to the bedrock,

Figure 11 illustrates a step of the method according to the invention in the construction of a wall structure according to the invention,

Figure 12 shows a drill pile and protruding plough ele ments formed on its surface according to an em bodiment in a view in a longitudinal direction of the wall structure,

Figures 13a and 13b show the formation of a wall structure according to the invention using drill piles ac cording to a further embodiment,

Figures 14a and 14b show oblique reinforcements according to a further embodiment.

The most common embodiment of a reinforcement used in the method and wall structure, i.e. rebars, is shown in the embodiments shown in Figures la - 14b. It is understood, however, that the embodiments illustrated in the figures can also be implemented in an analogous fashion while using composite reinforcements.

The method according to the invention is intended for the for mation of a wall structure in contact with a body of water, preferably at a shore or in a body of water close to the shore, for example in a harbour. As illustrated in greater detail in Figure 4, a drilling or analogous apparatus 102 can be supported during drilling on a platform 110, which is in turn supported on the ground 100 by means of support legs 112. Alternatively, drilling can be carried out from the top of a backfill made in the body of water as illustrated in Figure lg.

As shown in Figures 2a and 5a, the erection of the wall struc ture 10 according to the invention begins with the drilling of drill piles 16 into the ground 100. A drilling apparatus that can be used for flushing with a medium can be used as the drilling apparatus 102, which can be any type of apparatus intended for drilling drill piles by means of which a non rotating drill pile can be pulled behind it or pushed. The medium can be a liquid or air. Most preferably, the medium is a liquid by means of which drilling debris is flushed along the outer surface of the drill pile upwards in the drill hole. Alternatively, the drilling debris can be flushed by means of a liquid or air inside the drill pile. The drilling apparatus is preferably percussive, although it can also be exclusively rotary. Figure 4 shows an example of a drilling apparatus 102, which includes the following main parts: a bit 70, a reamer 56, a drill rod 72, a rotary device 74 and a pressurized-medium pumping unit 76. The drilling apparatus can be, for example, a drilling apparatus manufactured by the Finnish company Epiroc Oy. The drilling apparatus must be such that it is able to transport the drill pile into the drill hole without rotating the drill pile 16, since the drill pile 16 includes longitudinal linking elements 14 which prevent the rotation of the drill pile 16.

The drill pile is preferably pulled behind the pilot bit 52 in the drilling apparatus 102, the drill pile 16 being connected in a non-rotating manner to the rear of the rotating pilot bit 52 by means of a ground shoe 54, as illustrated in Figure 5a. As shown in Figure 5a, the drill pile 16 includes a carrying shoulder structure 55 by means of which the drill pile is either pulled or pushed, depending on the drilling apparatus, behind the drill into the drill hole. The drilling apparatus can also include further means for pushing the drill pile by its end into the drill hole. In addition to the pilot bit, the drill hole 12 is widened by means of the reamer 56 so that a drill pile 16 provided with a linking element 14 can enter the drill hole in the wake of the pilot bit 52 without damaging the linking element 14 or pushing it against the ground 100, whereby, for example, the female linking element 30 would be filled with ground. The reamer 56 can be, for example, a reamer bit or a ring bit.

The drill hole 12 is preferably drilled to a depth in the ground 100 that the drill hole 12 reaches the so-called stable layer in the ground 100, said stable layer being stationary and not moving in a horizontal direction. The stable layer is indicated in Figure 3 by the reference number 60. Such a layer can be a layer of so-called non-cohesive soil. A sufficient depth di mension by which the drill hole should preferably extend into the stable layer is at least one metre, preferably 2 - 4 m. This is, however, not imperative in all situations. During drilling, the drill hole is simultaneously flushed in order to remove drilling debris from the drill hole. Flushing is pref erably carried out by means of a liquid along the outer surface of the drill pile up and out of the drill hole, although the fluid and drilling debris can also be conducted into the drill pile. Air can also be employed in the flushing as an alternative to a liquid. When the drill hole 12 has been drilled to a sufficient depth, the pilot bit 52 is detached from the ground shoe 54, for example by means of a bayonet mount, and is raised out of the drill hole 12 while the drill pile 16 remains in the drill hole 12. Depending on the design of the reamer 56, the reamer 56 either remains in the drill hole with the drill pile or is raised out of the drill hole. Figures le, If and 3 indicate the part of the wall structure 10 in the stable layer, preferably in moraine, i.e. the concrete piles 22, by the ref erence number 43, the portion of the drill pile 16 that remains in the stable layer of the ground 100 by the reference number 45, and the part of the drill piles that remains above the ground 100 in contact with the water by the reference number 47.

As illustrated in Figures 2b and 5b, during the construction of the wall structure 10 in the method according to the inven tion, a plurality of adjacent drill holes 12 are formed next to each other, into each of which a drill pile 16 is pulled in the wake of the pilot bit 52 as illustrated in Figure lc. In the case of adjacent drill piles 16, a new drill pile 16 is installed together with a drill pile 16 already drilled into the ground such that the drill piles 16 are joined together by means of the linking elements 14. The linking elements 14 are placed so as to be in alignment during the pulling of the new drill pile 16 such that the new drill pile 16 slides in the longitudinal direction of the linking elements 14 in the link ing element 14 of the already drilled drill pile 16. By means of the interlocked drill piles 16, an ad hoc formwork is pro vided for the wall structure 10 to be cast.

The linking elements 14 of each drill pile 16 include a long linking element 44 and a short linking element 46, as shown in Figures 2a - 2e. When a new drill pile 16 is drilled next to a previously drilled drill pile 16, the long linking element 44 of the new drill pile extends beyond the diameter of the reamer with respect to a centreline of the drill pile 16. The long linking element 44 is positioned so as to connect to the short linking element of the already drilled drill pile 16. The reamer thus widens the drill hole 12 during drilling so that the adjacent drill holes 12 intersect at a point of intersection 50, thus forming a connection between the drill holes 12. Using this connection, the long linking element 44 follows in the wake of the reamer along the short linking element 46 of the adjacent drill pile 16, the reamer not hitting either of the two linking elements 14. The first drill pile can be designed differently and comprise merely two short linking elements, since there are as yet no adjacent drill holes and the linking element thus does not have to extend further with respect to a centreline of the drill pile than the reamer of the drilling apparatus. Alternatively, there can be merely one short linking element on the first drill pole.

The continuous linking element 14 includes, as illustrated in Figure 9, a stem part 120 extending in a radial direction of the drill pile 16 and comprising a first end 122 and a second end 124, wherein the first end 122 is attached to the drill pile 16 and a hooked interlocking part 126 is attached to the second end 124. The hooked interlocking part 126 provides an interlocking fixation with the hooked interlocking part 126 of the linking element 14 of the adjacent drill pile 16, which prevents horizontal movements of the drill piles relative to each other. This is because the drill piles are neither able to move towards each other when the linking element grips the outer surface of the adjacent pile nor away from each other since the hooked interlocking parts prevent a movement in this direction. Moreover, the length of the shorter linking element with respect to the stem part and the hooked interlocking part is such that the linking element of the adjacent drill pile can only be installed against this linking element via the longi tudinal movement of the drill pile. The hooked interlocking part 126 is preferably formed by an interlocking arm 128. In other words, the distance between the tip of the interlocking arm 128 of the short linking element and the outer surface of the drill pile is less than the length of the interlocking arm 128 in the longitudinal direction of the stem part 120 of the linking element 14 between the ends 122 and 124 of the stem part 120.

Alternatively, the linking elements 14 of the drill piles 16 can be as illustrated in Figures 13a and 13b in which the linking elements 14 include male linking elements 86 and female linking elements 88 attached by welding to the male linking elements. The female linking element 88 can be attached to the male linking element 86 on the outer surface of the drill pile 16 by means of a weld 90. An advantage of this type of drill pile is the formation of the male linking elements 86 as a protrusion of the inner part of the drill pile 16, whereby the poured concrete is also guite wide at the interstices 35 between the main shapes of the drill piles. This results in a sturdier wall structure.

The adjacent drill holes 12 can also be drilled in such a manner that a thin layer of ground remains between them, which is adapted to be broken up by the linking element 14 (not illus trated) of the drill pile 16. The maximum dimensions of this layer of ground depend on the properties of the ground. In soft ground, the linking element 14 is able to push through a wide layer of ground and still join the adjacent drill piles to gether. The linking element can also be channelled, for example for steel rebars or injection. The interstice 35 that remains between the main shapes of the drill piles can be in the order of the diameter D of the pipe so that the dimensions of the interstice would be 0 - D; preferably, however, it is 0 - D/2. Naturally, the dimensions of the interstice can be limited by the fact that the concrete poured into each drill pile must join the concrete mass of the adjacent pile when the drill piles are pulled up.

As illustrated in Figures 2b - 2d, the drill piles 16 can include protruding supports 26, which support the drill pile 16 against the inner surface of the drill hole 12 and prevent the drill pile from veering towards the adjacent drill hole 12. The height of the protruding supports 26 can be such that they extend slightly beyond the reamer with respect to a centreline of the drill pile in a radial direction of the drill pile. When the reamer makes a drill hole that is, e.g., 54 mm larger than the diameter of the drill pile, the diameter at the site of the protruding supports can be as much as 56 - 58 mm larger than the diameter of the drill pile. The protruding supports thereby run against the ground and wear slightly when installed firmly against the ground. The protruding supports 26 can have a side profile the shape of which is reminiscent of a shark's fin, as illustrated in Figure 5a, whereby they advance smoothly behind the drilling apparatus into the drill hole. It is understood that, contrary to Figures 2b - 2d, the protruding supports can also be blunt and, for example, semi-circular in terms of the shape of its side profile or configured in another manner so as to be suitable for the intended application.

When the desired width of the wall structure 10 to be formed has been reached by drilling into the ground 100 a desired number of drill piles 16 connected to each other by means of linking elements 14, reinforcements 20 can be installed inside the drill piles 16, as illustrated in Figures Id, 2c and 5c. Resources permitting, the installation of the reinforcements 20 can begin for a part of the drill piles 16 while other drill piles 16 are still being drilled into the ground 100, as il lustrated in Figure 5b. Preferably, in the reinforcement, re bars or some other analogous reinforcing bars used for reinforcement are lowered into the drill pile 16. The rebars are preferably welded into a circular structure consisting of a uniform arrangement of rebars. The amount of rebar reinforce ment is determined according to the strength required by the wall structure, said strength in turn being determined by the requirements of the environment of operations.

Preferably, after the installation of the reinforcements 20, concrete 18 is poured into the drill piles 16 as illustrated in Figures le and 2d, in which concrete 18 the reinforcements 20 remain. The drill pile 16 acts as formwork for the concrete 18. The concrete 18 fills the interior of the drill pile 16, thus forming a concrete pile 22 of reinforced concrete. If necessary, a selected binder can be mixed into the concrete 18 in order to improve the water tightness of the concrete 18.

Alternatively, the concrete can be poured into the drill piles already before the installation of the reinforcements, in which case, however, it is necessary to press the reinforcements into the freshly poured concrete by vibration.

As illustrated in Figures 5b - 5e, the reinforcements 20 can include, in addition to vertical straight reinforcements 21, also transverse reinforcements which provide a diagonal sup port. The transverse reinforcements are preferably spring re inforcements 92, which can be welded to the vertical reinforce ments 21. Spring reinforcements are one embodiment of oblique reinforcements. The spring reinforcements 92 can include a welded part 91 and, in the final wall structure, a transverse support part 93 in a transverse direction of the concrete piles, as well as a joint between them. In Figures 5b - 5e, the spring reinforcements 92 are torsion springs in which the welded part 91 is welded to the vertical reinforcements 21 and the trans verse support part 93 is tensioned against an inner wall of the drill pile 16 during the installation of the reinforcements in the drill pile 16 before finally being released substantially in a transverse direction of the drill pile 16 during the raising of the drill pile 16, thus also providing reinforce ments in the area of the linking elements of the drill piles 16 between the concrete piles 22.

As an alternative to the torsion spring illustrated in Figures 5b - 5e, it is also conceivable for the spring reinforcement 92 to be a straight spring 95 as illustrated in Figures 14a - 14b, which can be attached to a clasp 96 surrounding the ver tical reinforcements 21. The vertical reinforcements 21 are also tied together here by means of an installation band 94.

2 - 100 drill piles, preferably 5 - 50 drill piles, can be drilled into the ground in one substantially uninterrupted casting section before the raising of the drill piles is ini tiated. The drill piles are raised before the concrete sets and the fluid concrete paste becomes rigid, after which the con crete begins to harden and it becomes very difficult or even impossible to raise the drill pile without breaking the struc ture of the concrete pile. The length of a casting section can be influenced by using retarders in the concrete mixture, which delay the setting of the concrete and thus lengthen a time period for raising the drill piles.

When the drill piles 16 have been filled with concrete 18, the drill piles 16 can be raised upwards one at a time from the drill holes 12, as illustrated in Figure le, as the concrete 18 sets inside the drill piles, changing from a fluid, pliable concrete mass to a rigid mass, as illustrated in Figures 5c and 5d. The drill pile 16 is attached by its upper end to a lifting apparatus, which slowly lifts the drill pile 16 while simulta neously preferably vibrating the drill pile 16. For example, a vibratory lifting apparatus known under the product designation MRZV-VV from the German manufacturer ABI GmbH or LRB255 from Liebherr can be employed as the lifting apparatus. The lifting apparatus grabs the end of the drill pile and raises it upwards in the drill holes while simultaneously vibrating. The vibra tion of the drill pile 16 simultaneously vibrates the concrete 18 inside the drill pile 16, thereby compacting it. While the drill pile 16 is being removed from between the still fluid concrete 18 and the drill hole 12, the concrete 18 spreads laterally under the force of gravity, thus filling the drill hole 12 and forming a concrete pile 22 while spreading between the interconnected drill holes 12 and forming one continuous wall structure 10. At the same time, the vibration of the drill pile 16 compresses the still fluid concrete 18 in the drill hole 12 against the ground 100. In other words, the outer surface 23 of the concrete pile 22 forms a contact surface 25 against the ground 100, which is illustrated in Figures 2e and 3. In cases where spring reinforcements are used in the wall structure, the spring reinforcements are able to deploy between the concrete piles, thus reinforcing the overall wall struc ture. Alternatively, the drill piles can also be raised with no vibration; however, vibration is advantageous in terms of the implementation of the invention since it simultaneously compacts the concrete.

The upper limit for the raising of the drill piles 16 is a maximum of 3 m above the upper surface of the ground 100, beyond which the drill piles 16 must not be lifted since the movement of the water masses could otherwise slowly erode the ground around the drill piles and eventually leave the concrete piles exposed to the water. A steel drill pile readily withstands the long-term stress and loads caused by the water. As illustrated in Figure 3, the wall structure 10 can also include transverse reinforcements 19 which can be vibrated af ter the pouring of the concrete and the raising of the drill piles, said transverse reinforcements 19 preferably being ar ranged between the vertical reinforcements so that the vertical reinforcements 21 act as guides during the installation of the transverse reinforcements 19.

As illustrated in Figure 3, it is also possible to provide a support beam 71 connected to the wall structure, which support beam 71 is preferably cast transversely in the bare wall struc ture 10 on a side 73 of the wall structure 10 under construc tion. The side 73 of the wall structure 10 under construction is understood as the side on which a building or analogous object to be constructed is preferably provided while the op posite side of the wall structure 10 is in turn the stable side 77. The wall structure 10 can also be anchored in a stable layer 60 of the ground 100 on the opposite side of the wall structure 10 relative to the transverse support beam 71 by means of anchors 77. An anchor 77 in this case runs through both the support beam 71 and the concrete pile 22 of the wall structure 10 and extends further into the stable layer 60 of the ground 100, thus fixing the wall structure 100 more firmly in place.

Different linking elements 14 can be employed for joining the drill piles 16 during the drilling of the piles, as illustrated in Figures 6a and 6b. In Figure 6a, each drill pile has both a male linking element 28 and a female linking element 30. Figure 6b in turn shows drill piles 16 which only have male linking elements 28, the drill piles 16 being joined by means of an intermediate linking element 42. The intermediate linking ele ment 42 includes two female linking elements 30. If one desires to improve the tightness of the wall structure in a manner other than by modifying the components of the concrete, the method comprises the possibility of employing an injection of concrete according to a first embodiment in con nection with the raising of the drill piles. Concrete can be injected through the female linking element at the same time as the drill pile is being raised. Additional concrete can thereby be provided in the area between the concrete piles in the wall structure, which reinforces the structure and improves its tightness.

According to a second embodiment, an injection pipe can be temporarily fixed to the drill pile by means of fixing means, the injection pipe being released from the drill pile during the pouring of the concrete into the drill pile or during the raising of the drill pile and remaining at the bottom of the drill hole under the weight of the concrete. An injection pipe 34 is shown in Figure 7 and can be located either inside the concrete pile 22 in the concrete 18, as shown in Figure 7, or outside the concrete pile 18. The injection tube 34 can be slit along its length, except at the ends, whereby the concrete is able to fill any remaining cavities in the concrete piles during the injection. The diameter of the injection tube can be, for example, 15 - 25 mm. The fixing means can be, for example, a strip of sheet metal lightly welded to the side of the drill pile, which presses the injection tube against the drill pile during the drilling of the drill pile and detaches under the weight of the concrete or during the raising of the drill pile, the concrete pushing the injection tube underneath it into the drill hole. Additional concrete or sealant with which the tight ness of the wall structure is ensured can thereby be injected into the drill hole after the raising of the drill pile. The injection pipe can be, for example, a steel reserve pipe. It is understood in this context that the protruding supports disclosed in the present application can generally also be employed as part of the drill piles in a drill-pile wall struc ture, nor is their use exclusively limited to the method ac cording to the invention. The protruding supports can thus be a part of the drill pile and attached to the outer surface of the drill pile, at the end of the drill pile on the side of the reamer of the drilling apparatus, wherein the drill pile is 1 - 4 mm larger in diameter than the drill hole to be drilled at the site of the protruding supports. The protruding supports thereby stabilize the drill pile to be installed, especially during the drilling of the portion in the bedrock, where the lateral loads acting in the direction of the previously drilled pile are greatest for the installed pile.

As illustrated in Figures 2a - 2d and 12, in one embodiment of the method according to the invention, at least one protruding plough element 82 is welded, prior to the drilling of the drill pile 16 into the ground 100, to the end 84 of each drill pile 16 that enters the drill hole 12 first next to the linking element 14, which protruding plough element 82 is continuous over a sector of the outer circumference of the drill pile 16 and protrudes from the drill pile 16 by at most the same dis tance as the reamer used in the drilling apparatus 102. The purpose of the protruding plough element 82 is to dislodge the ground 100 during the raising of the drill pile 16 in order to optimize the joining of the concrete piles 22. The protruding plough element 82 thus "ploughs" the ground 100 in front of it to the side, thus widening the connection between two adjacent drill holes 12, said connection merely being as wide as a linking element in some cases, and enabling an efficient spread ing of the concrete from one drill hole 12 to the other, thereby connecting the adjacent concrete piles 22 to one another in an effective manner. At the same time, the protruding plough element 82 can create a negative pressure in its wake as the concrete surrounds and fills the space left in the drill hole by the drill pile during the raising and vibration of the drill pile. The negative pressure for its part effectively sucks concrete into the space between the drill holes, thereby join ing the concrete piles.

In the embodiment shown in Figure 12, the protruding plough elements 82 are plates welded to the drill pile 16 at an angle in the order of, for example, 30° - 60°, preferably 40° - 50°, relative to the longitudinal direction of the drill pile 16. This is a preferred embodiment, although it is understood that the protruding plough element can also be an encased structure or some other element protruding in a transverse direction of the drill pile that dislodges the ground in front of it during the raising of the drill pile. The protruding plough element can be formed in the drill pile over a minimum sector of 1°, preferably 5°, of the perimeter of the drill pile and a maximum sector of 50°, preferably 15°.

Figure 8 illustrates an embodiment of the method according to the invention in which the reinforcements 20 preferably in clude, in each drill pile 16, at least one hollow reinforcement in which a reserve pipe 72 is arranged. The reserve pipe 72 is protected during the pouring of the concrete into the drill pile 16, whereby the reserve pipe 72 remains empty. When the drill piles are partially raised, a sealing mass or concrete can be fed via the reserve pipe in order to ensure the tightness of the concrete piles of the wall structure. Alternatively, the drill piles can be drilled only as far as the surface of the bedrock, at which point a fixation hole can be drilled into the bedrock via the reserve pipes, via which fixation hole the concrete pile can be fixed to a reinforcement by an anchor bolt fixed in the fixation hole and thus in the bedrock. It is understood that, although the outer surface of the concrete pile 22 is shown as an even circular shape in Figures 7 and 8, in reality it adapts to the shape of the inner surface of the drill hole 12 as illustrated in Figure 2e.

Figure 9 shows an embodiment of the method according to the invention in which separate channels 80 are formed on the outer surfaces of the drill piles 16, via which liquid lubricant can be fed to the outer side of the drill piles 16 into the drill hole 12. The liquid lubricant that remains between the drill hole 12 and the drill pile 16 facilitates the raising of the drill piles by reducing the friction between the drill piles and the drill hole. Instead of separate channels, the liquid lubricant can also be fed via, for example, the female linking elements of the drill piles or using a separate channel formed in conjunction with the linking elements.

Alternatively to the use of a lubricant, a separate layer of material 29 suitable for reducing the friction between the concrete and the drill pile can be employed on the inner surface 27 of the drill pile 16, as illustrated in Figure 2c. The layer of material 29 can be, for example, Teflon.

According to the embodiment illustrated in Figures 10a and 10b, the drill piles of the wall structure can be drilled as far as the upper surface of the bedrock 65 constituting a stable layer 60. The reinforcement 20 includes a hollow reserve pipe 72, which is left empty during the pouring of the concrete and via which a fixation hole 62 can be drilled into the bedrock 65, as illustrated in Figure 10a. Finally, the wall structure is fixed by installing a fixation bolt 64 in the fixation hole 62 via the reserve pipe 72, said fixation bolt 64 mooring the concrete piles 22 in position in the bedrock 65 horizontally. As illustrated in Figure 11, it is also possible for the wall structure to be formed in such a manner that a drill pile 16 lying between an uppermost and a lowermost drill pile 16 in a line is drilled to one side of the line on a side of the line where the pressure of the ground against the future wall struc ture will be greater. This single offset drill pile 16 can be smaller in diameter than the other drill piles. When the drill piles are partially raised out of the drill holes 12, the pressure of the ground presses the concrete pile lying outside the line tightly against the concrete piles in line, thereby ensuring the tightness of the wall structure. The offset drill pile can be otherwise analogous in design to the other drill piles, although its linking elements and those of the connected drill piles must be arranged in a compatible manner relative to one another on the circumference of the drill pile.

When the drill piles 16 have been raised at least partially out of the portion of the drill hole 12 in the ground 100, the portion of the drill pile 16 that extends beyond the top end of the concrete pile 22 can be cut off, as illustrated in Figure If, and used, for example, in another object on its own or by joining two sections together. Optionally, this part can also be left intact. A harbour structure 116, for example a beam 114, to which the fenders of harbour ships can be attached, can be easily attached to the steel structure of the drill pile 16 at the upper end of the drill pile 16. A remaining area on a side of the wall structure 10 under construction can be filled with backfill if the structure under construction does not fill that area. The excess portion of the drill piles can only be cut off after filling of the backfill to avoid that backfill ends up in the body of water. If the method according to the invention is carried out from the backfill, as illustrated in Figure lg, the backfill 116 remaining on the side of the wall structure 10 facing the body of water 111 is lifted out of the water body after the completion of the wall structure 10 in order to provide a sufficient water depth.

According to one embodiment, the drill piles can also be driven back towards the drill hole after being raised, whereby the drill pile is pushed deeper into the ground than the concrete pile.

In an aspect that does not form part of the invention, it is conceivable that the idea of the method and wall structure according to the invention can also be implemented without the reinforcements arranged inside at least one drilling pile.

Claims

1. A method for forming a wall structure (10) in the ground (100) by drilling, wherein the wall structure (10) ex tends in contact with a body of water (111) in the form of a harbour structure (116), wherein

- a plurality of substantially vertical drill holes (12) are drilled next to each other in the ground (100) using a drilling apparatus (102) utilizing a pilot bit (52) and an reamer (56) while simultaneously flushing the drill hole (12) with a medium so as to remove drilling debris from the drill hole (12) and transporting into each drill hole (12) behind the drilling apparatus (102) a non-rotating drill pile (16) provided with longitudinal linking elements (14), wherein the adjacent drill piles (16) are joined to one another in a row by means of the linking elements (14) so as to form a wall structure (10), the drill piles (16) being smaller in diameter than the drill hole (12), and

- concrete (18) is poured into each drill pile (16) using the drill pile (16) as formwork, characterized in that

- the linking elements (14) are interlocking linking elements that bind the drill piles (16) in alignment relative to each other in a transverse direction of the same, wherein one linking element (14) is a long linking element (44) that extends beyond the diameter of the reamer (56) of the drilling apparatus (102) into the linking element (14) of the adjacent drill pile (16) in the adjacent drill hole (12) and the other is a short linking element (46) to which the long linking element (44) of the adjacent drill pile (16) connects,

- said drill holes (12) are drilled to extend into the ground (100) of the floor of the body of water (111) by a distance that is a partial length of length of the drill pile (16), - reinforcements (20) are installed in the concrete (18) in the drill hole (12) to strengthen the wall structure (10),

- at least a part of the adjacent drill piles (16) is raised at least partially out of the drill hole (12) by at least part (43) of the length of the drill hole (12) in the area of the ground (100) of the floor of the body of water (111) after the pouring of the concrete (18) but before the concrete (18) sets whereby the fluid concrete paste becomes rigid, whereby the concrete (18) compacting into concrete piles (22) in each drill hole (12) expands laterally into the concrete (18) of the ad jacent drill pile (16) as well as into the ground (100) of the drill hole (12) and forms a continuous water-impermeable wall structure (10) with the concrete piles (22) of the adjacent drill holes (12), the drill pile (16) remaining part of the wall structure (10) in the part (47) of the wall structure (10) above the ground (100) of the body of water (111).

2. The method according to claim 1, characterized in that the length of the drill pile (16) that remains in the wall structure (10) is 3 - 15 m.

3. The method according to claim 1 or 2, characterized in that said partial length is 10 - 90 %, preferably 15 - 30 %, of the length of the drill pile (16).

4. The method according to any of claims 1 - 3, charac terized in that the drill piles (16) are raised by at least 1 m in order to allow the concrete (18) to spread and at most by a length such that the drill pile (16) remains in the ground (100) in the drill hole (12) so as to protect the concrete pile (22) from the open water.

5. The method according to any of claims 1 - 4, charac terized in that a part of each raised drill pile (16) that extends beyond the concrete pile (22) is cut off.

6. The method according to claim 5, characterized in that the part to be cut off is 0 - 10 m in length.

7. The method according to any of claims 1 - 6, charac terized in that, after the raising of the drill piles (16), an amount of concrete equivalent to 1 - 25% of the amount of concrete (18) already poured into the drill pile (16) is added into the drill pile (16).

8. The method according to any of claims 1 - 7, charac terized in that drill piles (16) with linking elements (14) which interlock based on shape in the transverse direction of the drill pile (16) are employed.

9. The method according to any of claims 1 - 8, charac terized in that drill piles (16) are employed the linking ele ments (14) of which include

- a stem part (120) extending in a radial direction of the drill pile (16) and comprising a first end (122) and a second end (124), wherein the first end (122) is attached to the drill pile (16),

- a hooked interlocking part (126) attached to the said second end (124).

10. The method according to any of claims 1 - 9, charac terized in that a harbour structure (116) is formed at the upper end of the drill piles (16) in their operational position in a substantially transverse direction of the wall structure (10).

11. The method according to claim 10, characterized in that the hooked interlocking part (126) includes an interlock ing arm (128) which protrudes at an angle relative to the stem part (120) from the second end (124) of the stem part (120) back towards the drill pile (16), thus forming a shape-based interlocking structure.

12. A wall structure (10) that can be formed in contact with a body of water by drilling, the wall structure (10) comprising a plurality of adjacent concrete piles (22) joined to one another as well as to a stable layer (60) of the ground (100), the concrete piles (22) including reinforcements (20) installed in an interior of the concrete piles (22) and having a cross-sectional shape that is substantially circular, wherein the concrete piles (18) form an outer surface of the wall structure (10) over at least a portion of height of the wall structure (10) and each concrete pile (22) has an outer surface (23), characterized in that

- at least at the part of the wall structure (10) that extends into the ground (10) by a distance, each concrete pile (18) is connected by a fully integrated concrete structure to each adjacent concrete pile (18) by a sector of 1 - 50°, preferably 5° - 15°, of the cross-section of the concrete pile (18), the concrete structure having a contact surface (25) formed on the outer surface (23) on both sides of the wall structure (10) in direct contact with the stable layer (60) of the ground (100), the contact surface (25) being integrated in the stable layer (60) of the ground (100), and, at the part of the wall structure (10) above the ground, drill piles (16) attached to each other by means of linking elements (14) form the outer surface of the wall structure (10), while the concrete piles (14) respectively run continuously inside the respective drill piles (16),

- the linking elements (14) are interlocking linking elements that bind the drill piles (16) in alignment relative to each other in a transverse direction of the same, wherein one linking element (14) is a long linking element (44) that extends beyond a diameter of a reamer (56) of a drilling apparatus (102) into the linking element (14) of the adjacent drill pile (16) in the adjacent drill hole (12) and the other is a short linking element (46) to which the long linking element (44) of the adjacent drill pile (16) connects, and the wall structure (10) further includes a substantially transverse harbour structure (116) formed at the upper end of the drill piles (16).

13. The wall structure according to claim 12, character ized in that the thickness of the wall structure (10) is 1 - 25% greater along the concrete piles (18) of the wall structure (10) than along the drill piles (16) of the wall structure.

14. The wall structure according to claim 12 or 13, char acterized in that the length of the portion is at least 1 m and at most such that part of the drill pile (16) remains in the ground (100) in the drill hole (12).

15. The wall structure according to any of claims 12 - 14, characterized in that the short linking element (46) and the long linking element (44) are arranged on opposite sides of the drill pile (16) with respect to one other in order to maximize progression of the wall structure (10).