WO2017060567A1

WO2017060567A1 - A tubular pile for a pile wall and method for forming a pile wall

Info

Publication number: WO2017060567A1
Application number: PCT/FI2016/050691
Authority: WO
Inventors: Jouko Lehtonen; Mikko Mattila; Pasi Korte; Antti Leino
Original assignee: Robit Oyj
Priority date: 2015-10-06
Filing date: 2016-10-05
Publication date: 2017-04-13
Also published as: FI20155699A

Abstract

The present application concerns a tubular pile (1a, 1b) for a pile wall (10, comprising a tubular body (2) having an outer surface (3) and an inner surface (4) defining an inner space (4a). The pile further comprises a female connector (5) element, and a male connector element (6). The female connector element (5) and the male connector element (6) are arranged to correspond to each other so as form operationally interlocking shapes, and the female connector element (5) is arranged to longitudinally receive the male connector element (6) of an adjacent pile (1b) of a pile wall (10). A portion of reduced diameter (5a) of the female connector element (5) is formed by a groove extending on the tubular body radially towards the inner space (4a). The tubular pile (1a, 1b) comprises at least one tab (9) extending over the female connector (5) for increasing the pile's structural capacity to endure forces imparted upon it during installation.

Description

A TUBULAR PILE FOR A PILE WALL AND METHOD FOR FORMING A PILE WALL

FIELD OF THE INVENTION

The present invention relates to tubular piles for a pile wall. More specifically, the present invention concerns such piles having male/female connector elements enabling two adjacent piles of a pile wall to be connected to each other.

The present invention additionally concerns an arrangement for drilling such a tubular pile, a pile wall comprising such tubular piles and a method for forming a pile wall from such tubular piles. DESCRIPTION OF PRIOR ART

Retaining walls are used for resisting lateral pressure, when a change in ground elevation is present. The lateral pressure may be caused, e.g. by the ground material or water pressure. Pile walls, such as tubular pile walls, are a well-known type of retaining walls.

Conventionally, steel or iron pipes have been used as tubular piles. Corresponding female and male connector elements have been attached, by e.g. welding onto the outer surface of the pipe so as to extend radially therefrom, so that adjacent piles in pile wall may be connected to each other using said connector elements. Publication WO 2012/096679 A1 discloses an example of such a pile.

When the ground material, in to which the pile wall is to be formed, is hard, the piles can not be driven. Instead, a hole has to be drilled, into which hole the pile is introduced. The diameter of the drilled hole has to be sufficiently wide enough to accommodate the pile and any connector element extending from the pile. On the other hand, it is generally desirable to maintain the drill hole diameter as small as possible because a smaller hole is faster to drill and the associated material, manufacturing and equipment costs are smaller.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a tubular pile for a pile wall, which tubular pile enables faster formation of the pile wall and facilitates reduction of the associated material and equipment costs. It is a further object of the present invention to provide a tubular pile enabling the formation of a pile wall having improved stiffness and water retaining capability.

In order to achieve the objective mentioned above, the present invention provides a tubular pile in accordance with the characterizing portion of Claim 1 . Particularly, the present invention is based on the concept that a female connector element of a dovetail-like connection between adjacent piles in pile wall is formed to the tubular body of the pile. Hence, if the pile is drilled, the drilled hole into which the pile is introduced, does not have be dimensioned to accommodate a female or male connector element, which have conventionally been separate elements located on the outer surface of a pile. Consequently, a smaller drill bit can be used, contributing to reduced equipment costs. Furthermore, the tubular pile according to the present invention can be accurately and reliably introduced even into ground comprising solid rock material, as the tubular pile enables the use of contemporary drilling methods, such as the use of a concentric ring bit in drilling. Also, because a smaller hole requires less material to be removed from the ground, the drilling is faster, thus making the formation of the pile wall faster as well. Furthermore, because a smaller hole is used, less injection material is needed, should the pile be injected, thus contributing to reduced material costs.

Another important aspect is that, because the female connector element is formed of the tubular body of the tubular pile according to the present invention, adjacent piles in a pile wall can be positioned closer to each other, even so that the tubular bodies of the piles are in contact. As the adjacent piles are closer to each other, the water retaining capacity and the stiffness of the pile wall increases. Also, as the adjacent piles are close together, even less injection material is needed, should the piles be injected.

Furthermore, because the female connector element is formed of the tubular body, the female connector element can be constructed rather freely, because the dimensions of the female connector element are not constricted by other factors than the tubular body itself For example, the female connector element may be constructed to provide a sufficiently loose fitting connection with a male connector element, so that the tubular piles may be withdrawn from the ground after the retaining wall is no longer needed. Hence, this enables the tubular piles according to the present invention to be re-used, reducing the relative cost of the tubular pile itself. Accordingly, the tubular pile may be used to form a temporary structure, which conventionally have been formed using sheet piles. However, sheet piles can not be drilled into the ground, hence rendering sheet piles unsuitable for hard ground. It is yet a further object to provide an arrangement for drilling a tubular pile according to the present invention, a pile wall formed of piles according to the present invention, and a method for forming a pile wall from tubular piles according to the present invention.

In order to achieve the objective mentioned above, the present invention provides an arrangement in accordance with the characterizing portion of Claim 20. In order to achieve the objective mentioned above, the present invention provides a pile wall in accordance with the characterizing portion of Claims 21 .

In order to achieve the objective mentioned above, the present invention provides a method in accordance with the characterizing portion of Claim 22.

Although certain advantages of the present invention are particularly prominent when the piles are introduced into the ground by drilling, it should be appreciated that tubular pile may be introduced to the ground, and the pile wall may be formed using any suitable technique, such as drilling, driving, vibrating or jacking.

It is to be understood that both the foregoing general description and the following detailed description are exemplary, and are intended to provide further explanation of the invention as claimed. Other advantages and features of the invention will be apparent from the following description, drawings and claims.

BRIEF DESCRIPTION OF THE DRAWINGS

In the following, the invention is described in greater detail referring to the enclosed drawing, in which:

Fig. 1 illustrates a perspective cross-section view of a portion of two identical piles in a pile wall, as seen from either end of the piles, according to an embodiment of the present invention;

Fig.2 illustrates a perspective cross-section view of a portion of two identical piles in a pile wall, as seen from either end of the piles, according to another embodiment of the present invention;

Fig.3 illustrates a perspective cross-section view of a portion of two identical piles in a pile wall, as seen from either end of the piles, being equipped with a female restriction element;

Fig.4 illustrates a perspective cross-section view of a portion of two identical piles in a pile wall, as seen from either end of the piles, being equipped with a male restriction element;

Fig. 5 illustrates a perspective cross-section view of a portion of two identical piles in a pile wall, as seen from either end of the piles, being equipped with sectional separate consecutive male connector elements;

Fig. 6 illustrates the arrangement of Fig. 5 being further equipped with male restriction elements Fig. 7 illustrates a perspective cross-section view of a portion of two identical piles in a pile wall, as seen from either end of the piles, being equipped with tubular male connector elements;

Fig. 8 illustrates a perspective cross-section view of a portion of two identical piles in a pile wall, as seen from either end of the piles, being equipped with tabs extending over the female connector element, and

Fig. 9 illustrates a perspective detailed view of arrangement for a separate male connector element.

It is to be understood that the enclosed drawing present exemplary illustration and should not be interpreted in in restricting manner.

DETAILED DESCRIPTION OF THE INVENTION

A tubular pile 1 a, 1 b for a pile wall 10 according to the invention comprises a tubular body 2 extending longitudinally between a first end and a second end of the tubular pile 1 a, 1 b. The tubular body 2 has an outer surface 3 and an inner surface 4, which defines an inner space 4a. In connection with the present invention, the expression tubular is used to describe an elongate object than has a shape defining an inner space. Particularly, it should be understood that in this context, the term tubular should not be interpreted as restricting the cross-section shape of a tubular object, nor does the inner space defined by the shape need to be a fully closed profile.

The tubular pile 1 a, 1 b further comprises a female connector element 5 extending at least a distance between the first end and the second end of the tubular pile 1 a, 1 b. The female connector element 5 comprises a portion of reduced diameter 5a and a portion of increased diameter 5b. The tubular pile 1 a, 1 b also comprises a male connector element 6 extending at least a distance between the first end and the second end of the tubular pile 1 a, 1 b, wherein said male connector element 6 extends radially outwards from an outer surface 3 of the tubular body and comprises a portion of reduced diameter 6a, and a portion of increased diameter 6b.

In connection with the present invention, the expression portion of increased diameter is used to describe the dimension of the portion in question with respect to the portion of decreased diameter. Respectively, the expression portion of decreased diameter is used to describe the dimension of the portion in question with respect to the portion of increased diameter. Particularly, the diameter refers to the dimension of the portion's cross-section, as seen from either end of the pile, in the direction perpendicular to the direction in which adjacent tubular piles 1 a, 1 b are adjoined to each other. It should also be understood that shape of the portions of decreased diameter 5a, 6a and the portions of increased diameter 5b, 6b are not limited to the examples provided, but may be chosen freely as long as their functionality remains as described herein.

The portion of reduced diameter 5a of the female connector element 5 and the portion of reduced diameter 6a of the male connector element 6, and correspondingly, the portion of increased diameter 5b of the female connector element 5 and the portion of increased diameter 6b of the male connector element 6 are arranged to correspond to each other so as to form operationally interlocking shapes. The female connector element 5 is arranged to longitudinally receive a male connector element 6 of an adjacent pile 1 b of a pile wall 10 so as to adjoin the adjacent piles 1 a, 1 b laterally. Particularly, the portion of reduced diameter 5a of the female connector element 5 is formed by a groove extending radially on the tubular body towards the inner space 4a of the tubular body 2.

In connection with the present invention, the expression adjacent pile is used to describe a pile adjacent, in the lateral direction of said pile, to another pile in a pile wall 10, i.e. a neighboring pile.

In other words, the portions of increased diameter 5b, 6b and portions of decreased diameter 5a, 6a of both the female connector 5 and the male connector 6 male connector form a sliding dovetail -type joint between two adjacent piles 1 a, 1 b. When connected, the portion of increased diameter 6b of the male connector element 6 of the adjacent tubular pile 1 b, is nested within the portion of increased diameter 5b of a female connector element

5 of the tubular pile 1 a. Respectively, the portion of decreased diameter 6b of the male connector element 6, extending between its respective tubular pile 1 b and the portion of increased diameter 6b of the male connector element 6, is nested in the portion of decreased diameter 5a of the female connector element 5 of the tubular pile 1 a. As the portion of increased diameter 6b of the male connector element 6 is larger than the portion of decrease diameter 5a of the female connector element 5, the lateral movement between the adjoined tubular piles 1 a, 1 b away from each other is prevented. As described above, two tubular piles 1 a, 1 b may be adjoined together by introducing, in the piles' 1 a, 1 b longitudinal direction, the male connector element 6 within the female connector element 5.

Fig. 1 illustrates a perspective drawing of a section of two identical tubular piles 1 a, 1 b forming a part of a pile wall 10 according to an embodiment of the present invention, as seen from an end of the piles. On the outer surface 3 of the tubular body 2 there is a groove extending radially towards the inner space 4a, and axially along the longitudinal direction of the tubular pile 1 . That is to say, the groove is in the shape of an recessed area on the outer surface 3 of the tubular body 2.The recessed area comprises a neck portion forming the portion of reduced diameter 5a of the female connector element 5, and a base portion forming the portion of increased diameter 5b of the female connector element 5. The tubular pile further comprises a male connector element 6 extending radially outwards from the outer surface 3 of the tubular body. The male connector element 6 comprises a portion of reduced diameter 6a, and a portion of increased diameter 6b. Preferably, but not necessarily, at least one opening is provided extending between the portion of increased diameter 5b and the inner space 4a of the tubular body 2 so that any loose ground material introduced within the female connector element 5 may discharge to the inner space 4a. Thus, the risk of the female connector 5 clogging up during formation of the pile wall 10 is reduced.

Fig. 2 illustrates a perspective drawing of a section of two identical tubular piles 1 a and 1 b forming a part of a pile wall 10 according to another embodiment of the present invention, as seen from an end of the piles. A groove extending through the tubular body 2, i.e. from the outer surface 3 to the inner surface 4, forms the portion of decreased diameter 5a of the female connector element 5. Correspondingly, at least a part of the inner surface 4a of the tubular body 2 forms the portion of increased diameter 5b of the female connector element 5. A male connector element 6, having a portion of decreased diameter 6a and a portion of increased diameter 6b, extends radially outwards from the outer surface of the tubular body 6.

Fig. 3 illustrates a similar arrangement to that of Fig. 2, further equipped with a female restricting element 7 extending from the inner surface 4 towards the inner space 4a so as form, along with the inner surface, the portion of increased diameter 5b of the female connector element 5. When the portion of increased diameter 6b of the male connector element 6 of an adjacent pile 1 b is positioned in the portion of increased diameter 5b of the female connector element 5 formed by the female restricting element 7, together with at least a portion of the inner space 4a, the lateral motion between the adjacent piles 1 a, 1 b is confined both towards and away from each other. The female restricting element 7 and the portion of increased diameter 6b of the male connector element 6 may also be arranged such that the lateral movement between the adjoined piles 1 a, 1 b is substantially blocked all together

Also Fig. 4 illustrates a similar arrangement to that of Fig. 2, in which a tubular pile 1 b is further equipped with a male restricting element 8 extending from the portion of decreased diameter 6a, so as to confine a portion of the tubular body 2 surrounding the portion of decreased diameter 5a of a female connector element 5 of the adjoined tubular pile 1 a. The male restricting element 8 thus prevents lateral movement between two adjoined piles 1 a, 1 b towards each other by abutting the outer surface 3 of the tubular body 2. Preferably, but not necessarily, the male restricting element 8 extends from the portion of decreased diameter 6a of the male connector element on a side thereof opposite to the portion of increased diameter 6b. The male restricting element 8 may alternatively, or additionally, extend from the portion of decreased diameter 6a of the male connector element 6 on the same side of said portion of decreased diameter 6a as the portion of increased diameter 6b, so as to form, together with the portion of increased diameter 6b, a space (not illustrated) for receiving a portion of the tubular body 2 surrounding the portion of decreased diameter 5a of an female connector element 5 of an adjacent pile 1 b. When a portion of the tubular body 2 surrounding the portion of decreased diameter 5a of a female connector element 5 of an adjacent pile 1 b is positioned in the space formed by the male restricting element 8 and the portion of increased diameter 6b of the male connector element, the lateral motion between the adjacent piles 1 a, 1 b is confined both towards and away from each other. The male restricting element 8 and the portion of increased diameter 6b of the male connector element 6, along with the portion of the tubular body 2 surrounding the portion of decreased diameter 5a of a female connector element 5, may also be arranged such that the lateral movement between adjacent piles 1 a, 1 b is substantially blocked all together.

Fig. 5 illustrates an alternative arrangement for providing a male connector element 6 on the outer surface of the tubular body 2. In this arrangement, the male connector element 6 is provided as a separate section, extending at least a distance along the tubular body between the first end and the second end. Preferably, but not necessarily, the male connector element 6 is formed of T-profile sections, as this this is a readily available economical component. However, any other construction for the male connector element 6 described herein may be used. Preferably, but not necessarily, the separate male connector element 6 may be provided as two or more separate consecutive sections, each extending at least a distance along the tubular body between the first end and the second end. The arrangement of Fig. 5 is found particularly advantageous, as the male connector element 6 does not extend along the whole length of the tubular pile, thus reducing the material costs of manufacturing the tubular pile.

Fig. 6 illustrates the tubular pile 1 of Fig. 5 being further equipped with male restricting elements 8, separate from the male connector elements 6. Such separate male restricting element 8 may be positioned, for example, at the first end of the tubular pile 1 , at the second end of the tubular pile 1 , between two successive male connector element 6, or any combination thereof. Preferably, the separate male restricting elements 8 are dimensioned, when adjoined, to abut the outer surface of an adjacent pile 1 a, 1 b. The separate male restricting element 8 thus prevents lateral movement between two adjoined piles 1 a, 1 b towards each other by abutting the outer surface 3 of the tubular body 2. The separate male constricting element 8 should wide enough to not fit in the portion of decreased diameter 5a of the female connector element 5 of an adjacent tubular pile. Furthermore, the separate male restricting element 8 should extend radially from the outer surface 3 a distance less than that of the male connector element 6, so that the male restricting element 8 does not prevent the male connector element 6 from interlocking with the female connector element 5 of an adjacent pile 1 a, 1 b. The arrangement of Fig. 5 is found particularly advantageous, as the male restricting element 8 does not extend along the whole length of the tubular pile, thus reducing the material costs of manufacturing the tubular pile.

The use of a female restricting element 7, a male restricting element 8, or both, enables the portion of reduced diameter 6b of the male connector element to be dimensioned such that adjacent piles 1 a and 1 b of pile wall are located at a desired distance from each other, while still maintaining a rigid connection, i.e. a minimal lateral motion clearance, between the adjacent piles 1 a, 1 b.

A further male restricting element (not illustrated) may extend from the portion of increased diameter 6b of the male connector element 6 towards the outer surface 3 so as to provide a further support point between the male connector element and the female connector element of an adjoined tubular pile 1 a, 1 b.

A tubular pile 1 a, 1 b may be provided with a tubular male connector element 6. A tubular male connector element 6 is particularly advantageous when the pile 1 a, 1 b is to be injected, as the tubular male connector element 6 may be used conducting the injection material.

Fig. 7 illustrates a tubular portion of increased diameter 6b may be provided, from which a strip-like portion of decreased diameter 6a extends up to the outer surface of the tubular body 2. The tubular male connector element 6 may alternatively be implemented as a single tubular form directly attached to the outer surface 3 of the tubular body. Preferably, but not necessarily, the tubular male connector element 6 is dimensioned so as to contact the inner surface 4a of a tubular pile 12a, when adjoined to an adjacent tubular pile 1 b. Such dimensioning further improves the support between two adjoined piles 1 a, 1 b. Additionally, the tubular male connector element 6 may comprise an opening for enabling the injection material to distribute more evenly. Preferably, but not necessarily, the female connector element 5 and the male connector element 6 of any of the embodiments described above are arranged such that, when two tubular piles 1 a, 1 b are attached to each other with a female connector element 5 and a corresponding male connector element 6, a substantially rigid connection is formed between the two piles 1 a, 1 b in a lateral direction of the tubular piles 1 a, 1 b.

Preferably, but not necessarily, the female connector element 5 and the male connector element 6 correspond to each other such that, when two piles 1 a, 1 b are adjoined, the female connector element 5 receives substantially the whole of the male connector element 6. This enables two piles 1 a, 1 b to be adjoined together substantially laterally abutting each other. Accordingly, as the female connector element 5 is arranged to accommodate the whole male connector element 6, the drilled hole does not need to accommodate the male connector element 6, either. Furthermore, a yet smaller hole needs to be drilled for the tubular piles 1 a, 1 b.

The portion of increased diameter 6b of the male connector 6 may be arranged to correspond to the inner space 4a such that, when the pile 1 a is adjoined to an adjacent pile 1 b of a pile wall 10, the portion of increased diameter 6b of the male connector 6 is in contact with the inner surface 4 of the pile 1 a. Accordingly, the respective support between two adjoined tubular piles 1 a, 1 b is further increased. This may be done, for example, by dimensioning the portion of increased diameter 6b of the male connector 6 sufficiently wide, and correspondingly, dimensioning the portion of decreased diameters 6a of the male connector 6 sufficiently short. Alternatively, the portion of increased diameter 6b of the male connector 6 may be provided having a curved shape, or being inclined with respect to the portion of decreased diameter 6a of the male connector. Preferably, but not necessary, the portion of increased diameter 6b of the male connector element 6 is curved such that the cross-section, as seen from either end of the pile, of the portion of increased diameter 6b of the male connector element 6 corresponds to the curvature of a portion of the inner space 4a forming the portion of increased diameter 5b of the female connector element 5.

Preferably, but not necessarily the female connector element 5 extends towards the second end from a distance of the first end. Alternatively, or in addition, the female connector element 5 may extend towards the first end from a distance of the second end. Such arrangements provide a tubular pile 1 a, 1 b having an unbroken circumference at an end of the tubular pile. This increases the pile's structural capability to endure forces imparted onto it during e.g. drilling of the pile. It is particularly important for a tubular pile 1 a, 1 b according to the present invention not to deform during installation, as this could deform the connector element 5, 6 unusable. Preferably, the length of an unbroken circumference at either end of the tubular pile has a longitudinal dimension of 5-150mm, more preferably, 10-100mm, most preferably 25-75mm

Fig. 8 illustrates a tubular pile 1 provided with at least one tab 9 extending over the female connector element 5, preferably the portion of decreased diameter 5a thereof, for increasing the pile's 1 a, 1 b structural capability to endure the forces imparted upon it during installation and resist deformation. Such a tab 9 may be formed, e.g. by providing the tubular body 2 with a section of unbroken circumference or a separate band surrounding at least a part of the circumference of the tubular body 2. Furthermore, such tabs 9 may be positioned freely at the first end, at the second end, between the first end and the second end, or any combination thereof.

During installation, the tab 9, i.e. a section of unbroken circumference or a separate band as described above, may be cut where necessary for enabling the male connector element 6 to be inserted within the female connector element 5. Alternatively, or additionally, the tab 9, i.e. a section of unbroken circumference or a separate band may be constructed such that inserting the male connector element 6 into the female connector element 5 brakes the tab 9, i.e. the section of unbroken circumference or the separate band. Such a construction may be achieved, for example, by providing the tab 9, i.e. the section of unbroken circumference or the separate band with a suitable material thickness.

Fig. 9 illustrates a separate male connector element 6, which further facilitates the braking of the tab 9, i.e. the section of unbroken circumference or separate band. Particularly, the portion of reduced diameter 6a is provided with a sharp edge arranged at an end of thereof for braking through the tab 9, i.e. the section of unbroken circumference or separate band. A male connector element 6 provided with a sharp edge may be made, at least at the area containing the sharp edge, of different material, particularly harder material, than rest of the tubular pile 1 a, 1 b.

Naturally, connector elements 5 and 6 of a tubular pile 1 a, 1 b according to the present invention may be positioned as desired on the circumference of the tubular body 2. Although the examples illustrated in the enclosed drawing show an angular position of 180° between the female connector element 5 and the male connector element 6, it should be understood that other angular positions may be used in order to provide a pile wall 10 with a desired shape or path. Additionally, a tubular pile 1 a, 1 b according to the present invention may comprise any given number of female connector elements 5, male connector elements 6, or both, for forming a pile wall 10 having intersecting sections. The female connector element 5, the male connector elements 6, or both may also be provided having an inclination with respect to the longitudinal direction of the pile 1 a, 1 b. This enables adjoining tubular piles 1 a, 1 b together such that the adjacent piles 1 a, 1 b have an inclination with respect to each other. This is a particularly beneficial arrangement, should a pile wall having a section of a fan-like pattern, i.e. a radial pattern, be desired. Particularly, for the ease of manufacturing, a tubular pile 1 a, 1 b having a male connector element 6, at least the portion of increased diameter 6b of which is inclined with respect to the longitudinal direction of the pile 1 a, 1 b, may be used. Preferably, but not necessarily, this may be done by providing a plurality of male connector element 6 disposed along the longitude of the tubular pile 1 a, 1 b.

By providing tubular piles 1 having female connector elements, 5 male connector elements 6, or both, equipped with different angular positions and longitudinal inclinations, a pile wall 10 of a complex shapes, such as a frustum shape, conical shape pattern, or any combination thereof, may be provided. The tubular pile 1 a, 1 b according to the present invention may be produced using any suitable manufacturing method available.

Particularly, profile extrusion, roll forming and machining from a tube profile have been found suitable manufacturing methods. Additionally, the tubular pile 1 a, 1 b may be manufactured by producing two or more sections, for example of formed sheet metal, which are attached to each other, preferably along the male connector element 6, so as to produce the tubular pile 1 a, 1 b.

Moreover, it should appreciated, that the embodiments described herein may be readily combined with each so as to provided desired characteristics for a tubular pile 1 a, 1 b according to the present invention.

According to a further embodiment of the present invention, an arrangement is provided for drilling a tubular pile 1 a, 1 b. The arrangement comprises a casing shoe rotatably attachable to a drilling equipment. The arrangement further comprises a tubular pile 1 a, 1 b according to any of the embodiment described above. The tubular pile 1 is fixed to the casing shoe, by e.g. welding, so as to abut the casing shoe longitudinally. It has been surprisingly found, that the casing shoe further increases the structural strength of the tubular pile 1 , and thus, its capability to endure forces imparted onto it during e.g. drilling of the pile. It is particularly important for a tubular pile 1 a, 1 b according to the present invention not to deform during installation, as this could deform the connector element 5, 6 unusable. Preferably, but not necessarily, the arrangement further comprises a concentric ring bit. According to a further embodiment of the present invention, a pile wall 10 is provided. The pile wall 10 comprises at least two tubular piles 1 a, 1 b according to any of the embodiments described above. The tubular piles 1 a, 1 b are adjoined to each other with their corresponding female and male connector elements 5, 6 so as to form a pile wall 10. According to a further embodiment of the present invention, a method for forming a pile wall 10 is provided. Firstly, a first tubular pile 1 a according to any of the embodiments described above is provided. The first tubular pile 1 a is then drilled into the ground. A subsequent tubular pile 1 b is also provided. The female connector element 5 or the male connector element 6 of the subsequent tubular pile 1 b is aligned with the corresponding male connector element 6 or female connector element 5 of the first tubular pile 1 a, respectively. After the alignment, the subsequent tubular pile 1 b is drilled into the ground such that the corresponding connector elements 5, 6 of the first tubular pile 1 a and the subsequent tubular pile 1 b interlock with each other. Preferably, but not necessarily, the drilling is carried out using a drilling equipment comprising a concentric ring bit. Compared to eccentric drill bits, this provides superior penetration capabilities, particularly when solid rock is present in the ground.

According to a further embodiment of the present invention, the method may additionally comprise, prior to drilling the first tubular pile 1 a into the ground, providing a first casing shoe rotatably attachable to a drilling equipment, and attaching the first tubular pile 1 a to the first casing shoe. The method may additionally comprise, prior to drilling the subsequent tubular pile 1 b into the ground, providing a subsequent casing shoe rotatably attachable to the drilling equipment, and attaching the subsequent tubular pile 1 b to the subsequent casing shoe. Again, the method may additionally comprise, prior to drilling the subsequent tubular pile 1 b into the ground, attaching the subsequent casing shoe to the drilling equipment. As described, the use of a casing shoe, has surprisingly been discovered to prevent deformation of the tubular piles 1 a, 1 b during drilling

According to a further embodiment of the present invention, the method may additionally comprise, after introducing the first tubular pile 1 a into the ground, aligning the male connector element 6 of the subsequent tubular pile 1 b with the corresponding female connector element 5 of the first tubular pile 1 a. Further, the subsequent tubular 1 b pile may be drilled into the ground such that the male connector element 6 of the subsequent tubular pile 1 b is introduced with the corresponding female connector element 5 of the first tubular pile 1 a so that the first tubular pile 1 and the subsequent tubular pile interlock with each other. When the formation of the pile wall 10 is carried out such that the female connector element 5 is on the leading side of the pile wall, the subsequently drilled hole does not need to accommodate the male connector element 6 of the subsequent tubular pile 1 b, either, because it is directly introduced into the female connector element 5 of the first tubular pile 1 . Conventionally, piles have not been oriented so that the female connector element is positioned on the leading side of the pile wall, because lose ground material has potentially clogged the female connector, thus preventing adjoining the subsequent tubular pile. In the present invention this problem is avoided as the female connector element 5 is at least partly formed within the tubular body 2 providing a sufficient discharge route for the loos ground material introduced in the female connector element. Alternatively, if the female connector element 5 is not directly within the tubular body (as with the embodiment illustrated in Fig. 1 , a discharge channel may be provided, for example by forming at least one opening extending between the portion of increased diameter 5b and the inner space 4a of the tubular body 2.

Claims

1 . A tubular pile (1 a, 1 b) for a pile wall (10, comprising:

- a tubular body (2) extending longitudinally between a first end and a second end, said tubular body having an outer surface (3) and an inner surface (4) defining an inner space (4a);

- a female connector (5) element extending at least a distance between the first end and the second end, the female connector element comprising a portion of reduced diameter (5a), and a portion of increased diameter (5b);

- a male connector element (6) extending at least a distance between the first end and the second end, wherein said male connector element (6) extends radially from an outer surface (3) of the tubular body and comprises a portion of reduced diameter (6a), and a portion of increased diameter (6b), wherein

the portion of reduced diameter (5a) of the female connector element (5) and the portion of reduced diameter (6a) of the male connector element (6), and correspondingly, the portion of increased diameter (5b) of the female connector element (5) and the portion of increased diameter (6b) of the male connector element (6) are arranged to correspond to each other so as form operationally interlocking shapes, and wherein

the female connector element (5) is arranged to longitudinally receive an male connector element (6) of an adjacent pile (1 b) of an pile wall (10) so as to adjoin adjacent piles (1 a, 1 b) of an pile wall (10), and

the portion of reduced diameter (5a) of the female connector element (5) is formed by a groove extending on the tubular body radially towards the inner space (4a) of the tubular body (2),

characterized in that the tubular pile (1 a, 1 b) comprises at least one tab (9) extending over the female connector element (5) for increasing the pile's (1 a, 1 b) structural capability to endure the forces imparted upon it during installation and resist deformation, said tab being preferably in the form of a section of unbroken circumference provided on the tubular body (2) or a separate band surrounding at least a part of the circumference of the tubular body (2).

2. The tubular pile (1 a, 1 b) of Claim 1 , characterized in that the groove is in the shape of an recessed area on the outer surface (3) of the tubular body (2), said recessed area having a neck portion forming the portion of reduced diameter (5a) of the female connector element (5), and a base portion forming the portion of increased diameter (5b) of the female connector element (5)

3. The tubular pile (1 a, 1 b) of Claim 2, characterized at least one opening is provided extending between the portion of increased diameter (5b) and the inner space (4a) of the tubular body (2).

4. The tubular pile (1 a, 1 b) of Claim 1 , characterized in that and the groove forming the portion of decreased diameter (5a) of the female connector (5) extends through the tubular body (2), and the portion of increased diameter (5b) of the female connector element (5) is formed at least partly by the inner space (4a) of the tubular body (2).

5. The tubular pile (1 a, 1 b) of Claim 4, characterized in that the portion of increased diameter (6b) of the male connector (6) is arranged to correspond to the inner space (4a) such that, when the pile (1 b) is adjoined to an adjacent pile (1 a) of a pile wall (10), the portion of increased diameter (6b) of the male connector (6) is in contact with the inner surface (4) of an adjacent pile (1 a).

6. The tubular pile (1 a, 1 b) of Claim 4 or 5, characterized in that the cross-section, as seen from either end of the pile (1 a, 1 b), of the portion of increased diameter (6b) of the male connector element (6) corresponds to the cross-section of a portion of the inner space (4a) forming the portion of increased diameter (5b) of the female connector element (5).

7. The tubular pile (1 a, 1 b) according to any of the preceding Claims 4-6, characterized in that the cross-section, as seen from either end of the pile (1 a, 1 b), of the portion of increased diameter (6b) of the male connector element (6) is curved.

8. The tubular pile (1 a, 1 b) of Claim 4-7, characterized in that the cross-section, as seen from either end of the pile (1 a, 1 b), of the portion of increased diameter (6b) of the male connector element (6) corresponds to the curvature of a portion of the inner space (4a) forming the portion of increased diameter (5b) of the female connector element (5).

9. The tubular pile (1 a, 1 b) according to any of the preceding Claims 4-8, characterized in that the pile (1 a, 1 b) further comprises at least one female restricting element (7) extending from the inner surface (4) towards the inner space (4a) so as to form, along with the inner surface, the portion of increased diameter (5b) of the female connector element (5).

10. The tubular pile (1 a, 1 b) according to any of the preceding Claims, characterized in that the pile (1 a, 1 b) further comprises at least one male restricting element extending from the portion of increased diameter (6b) of the male connector element (6) towards the outer surface (3).

1 1 . The tubular pile (1 b) according to any of the preceding Claims characterized in that the pile (1 b) further comprises at least one male restricting element (8) extending from the portion of decreased diameter (6a) of the male connector element (6) so as to confine a portion of the tubular body (2) surrounding the portion of decreased diameter

(5a) of a female connector element (5) of an adjoined tubular pile (1 a).

12. The tubular pile (1 a, 1 b) according to any of the preceding Claims, characterized in that, the male connector element (6) is provided as a separate section, extending at least a distance along the tubular body between the first end and the second end, the male connector element (6) being preferably provided as two or more separate consecutive sections, each extending at least a distance along the tubular body (2) between the first end and the second end.

13. The tubular pile (1 a, 1 b) of any preceding Claim, characterized in that the male restricting elements (8) are provided separate from the male connector elements (6), preferably positioned at the first end of the tubular pile (1 ), at the second end of the tubular pile (1 ), between two successive male connector element (6), or any combination thereof.

14. The tubular pile (1 a, 1 b) according to any of the preceding Claims, characterized in that the male connector element (6), preferably the portion of increased diameter (6b) thereof, is tubular.

15. The tubular pile (1 a, 1 b) of any preceding Claim, characterized in that the female connector element (5) extends towards the second end from a distance of the first end, the female connector element (5) extends towards the first end from a distance of the second end, or both.

16. The tubular pile (1 a, 1 b) according to any of the preceding Claims, characterized in that the male connector element (6) is provided with a sharp edge arranged at an end of thereof, preferably on the portion of reduced diameter (6a).

17. The tubular pile (1 a, 1 b) of any preceding Claim, characterized in that the female connector element (5) and the male connector element (6) are arranged such that, when two adjacent tubular piles (1 a, 1 b) are attached to each other with a female connector element (5) and a corresponding male connector element (6), a substantially rigid connection is formed between said two adjacent piles (1 a, 1 b) in a radial direction of the tubular pile (1 a, 1 b).

18. The tubular pile (1 a, 1 b) of any preceding Claim, characterized in that the female connector element (5) and the male connector element (6) are arranged to correspond to each other such that, when adjoined to an adjacent pile (1 b), the female connector element (5) receives substantially the whole of the male connector element (6).

19. The tubular pile (1 a, 1 b) according to any of the preceding Claims, characterized in that at least a portion of the female connector element (5), the male connector element (6), or both, are inclined with respect to the longitudinal direction of the pile (1 a, 1 b), preferably at least the portion of increased diameter (6b) of the male connector element (6) is inclined with respect to the longitudinal direction of the pile (1 a, 1 b).

20. An arrangement for drilling a tubular pile (1 a, 1 b), said arrangement comprising a casing shoe rotatably attachable to a drilling equipment, characterized in that said arrangement further comprises a tubular pile (1 a, 1 b) according to any of Claims 1 - 20, the tubular pile abutting the casing shoe longitudinally and being fixed thereto.

21 . A pile wall, characterized in that said pile wall comprises at least two tubular piles (1 a, 1 b) according to any of the Claims 1 -19 adjoined to each other with their corresponding female and male connector elements (5, 6) so as to form a pile wall (10).

22. A method for forming a pile wall, characterized by comprising the following steps:

- providing a first tubular pile (1 a) according to any of Claims 1 -19;

- drilling the first tubular pile (1 a) into the ground;

- providing a subsequent tubular pile (1 b) according to any of Claims 1 -19; - aligning the female connector element (5) or the male connector element (6) of the subsequent tubular pile (1 b) with the corresponding male connector element (6) or female connector element (5) of the first tubular pile, respectively, and

- drilling the subsequent tubular (1 b) pile into the ground such that the corresponding connector elements (5; 6) of the first tubular pile (1 a) and the subsequent tubular pile (1 b) interlock with each other.

The method for forming a pile wall according Claim 22, characterized by further comprising the following steps:

- prior to drilling the first tubular pile (1 a) into the ground, providing a first casing shoe rotatably attachable to a drilling equipment bit, and attaching the first tubular pile (1 a) to the first casing shoe;

- prior to drilling the first tubular pile (1 a) into the ground, attaching the casing shoe to the drilling equipment, and after drilling the first tubular pile (1 a) into the ground, detaching the first casing shoe from the drilling equipment;

- prior to drilling the subsequent tubular pile (1 b) into the ground, providing a subsequent casing shoe rotatably attachable to the drilling equipment, and attaching the subsequent tubular pile (1 b) to the subsequent casing shoe;

- prior to drilling the subsequent tubular pile (1 b) into the ground, attaching the subsequent casing shoe to the drilling equipment.

The method for forming a pile wall according Claim 22 or 23 characterized by further comprising the following steps:

- aligning the male connector element (6) of the subsequent tubular pile (1 b) with the corresponding female connector element (5) of the first tubular pile (1 a)

- drilling the subsequent tubular (1 b) pile into the ground such that the male connector element (6) of the subsequent tubular pile (1 b) is introduced with the corresponding female connector element (5) of the first tubular pile (1 a) so that the first tubular pile (1 a) and the subsequent tubular pile interlock with each other.