IES65200B2 - Pile - Google Patents

Abstract

A pile (10) has an iternally conical socket (13) at its first end (12) and an externally conical section (15) at its second end (14). The dimensions (17, 22, 26) and the conicity of the socket (13) and of the conical section (15) are selected so that the conical section is insertable and drivable into the socket (13) of a further pile (10) to such an extent that a self-securing connection is established between the two piles (10). The socket (13) of the conical section (15) each have a conicity with a taper ratio between 1:8 and 1:13. The term "taper ratio" is defined as the ratio of change in diameter to associated length. The tubular pile (10) is preferably formed from ductile cast iron, such as spheroidal graphite iron.

Description

PILE The present invention relates to a pile having an internally conical socket at its first end and an externally conical section at its second end, the dimensions and the conicity of the socket and of the conical section being selected such that the conical section is insertable and drivable into the socket of a further pile to such an extent that a self-securing connection is established between the two piles.

A pile of this kind is known from EP-A-0,285,584.

The known pile is assembled from a multiplicity of identical piles into a carrying structure for supporting longitudinally extending loads above the ground, in order for example to hold and to guide transmission lines and the like. In order to build up the structure, the lower piles are driven into the ground and further piles are then inserted into this base pile and the piles connected to it, until such time as the required height of the support structure is reached.

The known piles are of hollow, tubular form and may be made 565200 - 2 from ductile iron. The taper ratio in the interior of the socket and on the externally conical section is in the region between 1:14 and 1:20, the ratio of change in diameter to associated length being y understood by the term taper ratio. A taper ratio of 1:14 thus means that the diameter changes by exactly one unit of length over ♦ fourteen units of length.

It is also known to use piles as ram piles in any situation such as where for example piling or foundations for buildings are required. For this purpose, piles are placed one on the other and driven into the earth until such time as the required load-carrying capacity of for example 40 tons is achieved by the frictional engagement with the earth. For this purpose, sufficient piles are placed one above the other for these to extend 40 to 50 metres deep into the earth.

In particular for use for foundations for buildings etc., it is necessary for the self-securing connection between two successive piles to have a specific strength, so that this connection will not be undone by transverse forces, which may have in part tensile components. In the case of the support structure known from the above-mentioned EP-A-0,285,584, which is built up above the earth, retaining pins are provided for this purpose, which are inserted transversely through a socket and through the conical section inserted into this socket, in order to prevent an unintended separation of the connection.

While these retaining pins may be inserted without difficulty in the case of a support structure which is built upwards, this is not the case for piling being driven into the earth. In addition, the use of retaining pins has two further serious disadvantages. For the first, these retaining pins represent an additional structural component, which increases the overall costs of support structures of this kind. For the other, the use of additional retaining pins also - 35 means an increased expenditure of time in the assembly of the support structure, since in addition to the mutual engagement of conical - 3 section and socket, care must also be taken so that the through holes for the retaining pin, which are present both in the socket and also in the conical section, are aligned with one another after engagement together of conical section and socket. Since the connection is t self-securing on account of the taper ratio, a subsequent adjustment is only possible by the exercise of relatively great force, so that even * at the stage of pushing the components together, great care must be taken.

For all of these reasons, the known piles are not suitable for use as ram piles for the construction of foundations etc.

It is therefore an object of the present invention to develop a pile of the kind mentioned at the beginning in which the strength of the connection between socket and conical section is increased, while at the same time the manufacturing costs and the expenditure of time for assembly are to be reduced.

This object is achieved in the case of a pile as defined above by the socket and the conical section each having a conicity with a taper ratio between 1:8 and 1:13, the ratio of change in diameter to associated length being understood by the term taper ratio.

In this manner the task addressed by the invention is fully solved. It has in fact surprisingly been found that for the range according to the invention of the taper ratio, the connection between socket and conical section is frictionally and positively effective, so that screwing is no longer required. The connection can also withstand tensile forces, which may occur in connection with bending forces when driving piles placed one above the other into the earth.

As a consequence, it has also surprisingly been found, that a taper range of 1:8 to 1:13 brings special advantages in regard to the ’ mechanical stability of the connection, so that the new piles are especially effective as ram piles. Since no screwing action is required, only a single structural component is necessary, namely the - 4 new pile, in order to be able to achieve the required structures, which not only saves on material costs but also on construction time. j Overall, it is especially preferred for the pile to be formed as a tube.

It is thus of advantage for hollow piles of this kind to be injectable with concrete, after they have been driven into the earth one after the other in appropriate number, by which an increased bearing surface is achieved, as it corresponds to the diameter of the pile. In this manner, the load-carrying capacity may be further increased.

It is also further preferred for the pile to have, in the region of the conical section, a wall thickness which decreases towards the second end, for a substantially uniform internal diameter.

It is here of advantage for the conical section to have a degree of deformability increasing towards the second end on account of the reduced wall thickness, which facilitates the engagement together and driving-in of the conical section into the socket of the pile located beneath and thus reduces the assembly time.

It is further preferred for the pile to have an increased wall thickness in the region of the socket, which preferably is substantially constant over the length of the socket.

It is here of advantage that this outer cone of the socket corresponding to the inner cone ensures that sufficient material is present in the wall for annular tensile forces, which exist in the socket on account of the driven-in conical section and tend to enlarge this, do not lead to cracking of the socket. The external contour of * the socket brings about therefore, on account of its internal shape and the required wall thickness, the absorption of these annular tensile • 35 forces. - 5 Overall, it is preferred for the pile to be made from ductile cast iron.

This ductile cast iron, which may also be referred to as t spheroidal graphite iron, has a modulus of elasticity which is as good as that of steel, the material and production costs being however significantly reduced, which leads to a further advantage of the novel pile.

In an exemplary embodiment, it is then preferred for the socket to have an internally circumferential shoulder, against which the end face of the second end of a driven-in further pile abuts.

In this it is of advantage that the shoulder prevents the conical section from being driven in too far when erecting a piled structure or during the later continuous loading. This has on the one hand safety aspects, since if a pile is driven in too far, the socket of the next deeper pile may burst at some stage. On the other hand, the construction time is also reduced by this feature, since the abutment on the shoulder takes place after a definite driving-in distance into the socket, so that for further driving, the entire pile structure is now driven forward further into the earth.

It is thus then preferred for the end face of the first end to have a spacing from the shoulder which substantially corresponds to the free diameter of the socket.

It has been found that this geometrical relationship between the depth of the shoulder in the socket and the diameter of the socket itself leads to a very secure connection between socket and conical section, even in the case of piles which are 5 metres long.

It is further preferred for the pile to have a substantially constant inner diameter and a substantially constant outer diameter in a tubular region between socket and conical section, the wall thickness there being less than in the region of the socket. - 6 This feature is particularly of advantage not only from the point of view of stability but also in regard to a saving of material. It may also be mentioned that the tubular section may also extend in a conical manner to a very slight extent, so that the pile may thus be more easily removed from the mould. This taper amounts however to only l/10th of a millimetre over the entire length of the pile and enables the pile to be removed from the casting mould without having to be cooled to too great an extent, thus increasing the speed of production.

In general it is preferred for the external diameter of the pile in the transition region between the socket and the tubular region to reduce to the outer diameter according to a sigmoidal function.

In this it is of advantage that the transfer of the loading forces from the socket into the tubular region is achieved in an especially favourable and harmonious manner, the annular tensile forces being continuously transferred into the tubular region.

Further advantages will emerge from the description and the accompanying drawing.

It will be understood that the features previously mentioned and those still to be explained from the following discussion may be used not only in each of the combinations mentioned, but also in other combinations or in an individual installation, without departing from the scope of the present invention.

An exemplary embodiment of the invention is shown in the drawing and will be described in more detail in the following description.

The single drawing shows a longitudinal section through the novel pile, not to scale, the geometrical relationships being shown exaggerated for clarity. - 7 In the single drawing, a novel pile is indicated by reference 10. The pile 10 has a tubular region 11. Region 11 has at its first end 12 a socket 13 which is conical both internally and externally.

At its second end 14, region 11 has a section 15 which is outwardly conical. The outwardly conical section 15 tapers inwardly in its outer diameter to an end face 16 of the second end 14, this taper being indicated by reference 17. At the second end 14 and in the tubular region 11 between the socket 13 and the second end 14, the pile 10 has a substantially constant internal diameter 18, while the socket 13 has an internal diameter 22 which enlarges uniformly in the direction of an end face 21 of the first end 12. The outer diameter 23 of the socket 13 similarly enlarges uniformly in the direction of the end face 21.

At its inner end, the socket 13 has a transition to the internal diameter 18, with formation of a shoulder 25. This shoulder 25 is located at a spacing 26 from the end face 21, which substantially corresponds to the internal diameter 22.

While the conical section 15 has a wall thickness 27 which reduces in the direction of the end face 16, constant wall thicknesses 28 and 29 respectively are to be found in the region of the socket 13 and in the tubular section 11. The wall thickness 29 is thus greater than the wall thickness 28, which in turn is greater than the wall thickness 27. In the transition region between socket 13 and tubular section 11, the outer diameter 23 changes according to a sigmoidal function, so that there results a kind of S-shape in the cross-sectional representation.

The taper ratios for the outer diameter 17 of the conical section 15 and for the internal diameter 22 and the outer diameter 23 of the socket 13 are in the range between 1:8 and 1:13, the relationship of change in diameter to associated length being understood by the term taper ratio. A taper ratio of 1:8 thus means that the diameter changes by one unit of length over eight units of length. The region between 1:8 and 1:14 is shown in the drawing as more closely cross-hatched. - 8 It may also be remarked that the internal diameter 22 need not necessarily taper continuously inwardly beginning at the end face 21 right up to the shoulder 25, but that the socket 13 may have an internal annular region 31 in which the internal diameter 22 remains constant. This annular region 31 then begins before the shoulder 25. i The slope in the region of the conical section 15 and in the interior and exterior of the socket 13 is designated by angles or 32 and 33, which are in a range between 2.2° and 3.5°, so that the taper ratio mentioned comes to lie in the range between 1:8 and 1:13.

If the conical section 15 of a further pile 10 is now pushed into the socket 13, the external wall 34 of the conical section 15 comes into abutment with the socket 13 by way of its internal wall . The above-mentioned dimensions ensure that the section 15 cannot be pushed into the socket 13 without exercise of force. On driving-in of the section 15 into the socket 13, the socket 13 is somewhat expanded, the annular tensile forces occurring being taken up by the increased wall thickness 29. At the same time, the section 15 yields, which is facilitated by the reduced wall thickness 27. The section 15 is now driven into the socket 13 sufficiently far for the end face 16 to come into abutment against the annular shoulder 25. Since the pile 10 is formed in one piece from ductile cast iron, which has a modulus of elasticity as good as steel, there results a frictional and positive connection between socket 13 and conical section 15, which can also withstand tensile forces.

Claims (10)

1. A pile having an internally conical socket (13) at its first end (12) and an externally conical section (15) at its second end (14), the dimensions (17, 22, 26) and the conicity of the socket (13) and of the conical section (15) being selected such that the conical section (15) is insertable and drivable into the socket (13) of a further pile (10) to such an extent that a self-securing connection is established between the two piles (10), characterised in that the socket (13) and the conical section (15) each have a conicity with a taper ratio between 1:8 and 1:13, the ratio of change in diameter to associated length being understood by the term taper ratio.

2. A pile according to Claim 1, characterised in that it is tubular.

3. A pile according to Claim 2, characterised in that in the region of the conical section (15), the pile has a reducing wall thickness (27) towards the second end (14) for an internal diameter (18) which remains substantially constant.

4. A pile according to Claim 2 or Claim 3, characterised in that in the region of the socket (13), the pile has an increased wall thickness (29), which preferably is substantially constant over the length of the socket (13).

5. A pile according to any of Claims 1 to 4, characterised in that it is formed from ductile cast iron.

6. A pile according to any of Claims 2 to 5, characterised in that the socket (13) has an internal circumferential shoulder (25), against which there abuts the end face (16) of the second end (14) of a further pile (10) driven into the socket.

7. A pile according to Claim 6, characterised in that the end - 10 face (21) of the first end (12) is at a spacing from the shoulder (25), which substantially corresponds to the clear diameter (22) of the socket (13). * 58. A pile according to any of Claims 2 to 7, characterised in j that in a tubular region (11) between the socket (13) and the conical section (15), the pile has a substantially constant internal diameter (18) and a substantially constant external diameter (19), the wall thickness (28) being less than in the region of the socket (13).

8. 9. A pile according to Claim 8, characterised in that in the transition region between the socket (13) and the tubular region (11), the external diameter (23) reduces to the external diameter (19) according to a sigmoidal function.

9.

10. A pile as defined in Claim 1, substantially as described herein with reference to and as shown in the accompanying drawing.