IE83233B1 - Collet connector for piles - Google Patents

Description

Collet Connector for Piles The present invention relates to pile connection devices and in particular, to pile connection devices for use in forming pile joints.

Piles are conventionally used for driving into the ground to support structures such as buildings. They may be provided in sections for driving in end-to-end relationship to form the complete pile. Piles may be required to bear tension as well as compression during use. according to the circumstances of use. Connection arrangements which can bear tension are therefore necessary in these circumstances. to The present invention provides a pile connection device for use in V connecting pile sections of the type which comprise a body of cementitious material through which at least one elongate reinforcing member extends, the device comprising first and second attachment arrangements which, in use. attach to ends of reinforcing members of respective pile sections, thereby connecting the sections, and wherein at least one of the attachment arrangements is in the form of a collet arrangement which receives the end of a reinforcing member when pushed thereon, and which grips the said end substantially to prevent removal thereafter.

Preferably, the first attachment arrangement is a collet arrangement as aforesaid. the other attachment arrangement providing for permanent attachment to a reinforcing member during manufacture of a pile section. The said other attachment arrangement may comprise a tubular deformable member for attachment by crimping around a reinforcing member.

Alternatively, both attachment arrangements of the device may be collet arrangements as aforesaid. whereby the device, in use. is operable to connect adjacent pile sections by pushing the collet arrangements over the ends of the reinforcing members of respective pile sections.

The or each collet arrangement may comprise a plurality of collar parts which together define between them a space for receiving a reinforcing member to form a collar therearound, the collar parts together defining a tapering outer surface for the collar and being located within a tapering passage, and there being resilient bias means operable to urge the collar toward the narrow end of the passage. whereby an elongate member may be pushed into the space from the narrow end of the passage by moving the collar against the resilient bias to allow the space to expand, the elongate member being thereafter gripped against removal through the narrow end by contraction of the collar as it is drawn toward the narrow end. The outer surface and the passage are preferably frusto-conical.

The invention also provides a pile section for connection in end-to—end relationship with like pile sections, and comprising a body of cementitious material through which at least one elongate reinforcing member extends, the or each reinforcing member having a first, male end exposed by the cementitious body, and the pile section comprising a connection device according to any of the preceding definitions, attached to the second end of the or each reinforcing member to provide the or a collet arrangement exposed for receipt of the male end of a reinforcing member of another pile section, thereby connecting the pile sections together.

The invention also provides a method of connecting pile sections of the type comprising a body of cementitious material through which at least one elongate reinforcing member extends. the ends of which are proud of the cementitious body. wherein connection devices according to the first aspect of the invention and each having two collet arrangements as aforesaid are pushed over the ends of reinforcing members of respective pile sections.

Examples of the present invention will now be described in more detail. by way of example only, and with reference to the accompanying drawings. in which:- Fig. 1 is a highly schematic illustration of a sectional pile being driven into the ground, the sections being connected by joints formed in accordance with the present invention; Fig. 2 illustrates in more detail and on an enlarged scale, a joint between two sections of the pile of Fig. 1; Fig. 3 illustrates a connection device used in the joint of Fig. 2. on an enlarged scale; and Fig. 4 illustrates the manner in which a modified version of the connection device of Fig. 3 can be used for interconnecting pile sections.

Fig. 1 illustrates a sectional pile made of several pile sections 10, driven into the ground 12 with the sections 10 in end—to-end relationship. Pile driving is achieved by appropriate equipment 14, such as a hammer. vibrator or the like. illustrated schematically as applying a downward force 16 to the exposed upper end of the upper pile section 10.

Each pile section 10 is joined to the pile sections above and below by means of a joint designed to remain connected under compression and tension forces, so that the complete pile formed by the pile sections 10 can bear tension as well as compression during use.

A joint is illustrated in more detail in Fig. 2. generally at 20.

In this example, each pile section is in the form of a body 22 of cementitious material. such as concrete. Elongate reinforcing bars 24 attend through the body 22. Two bars 24 are illustrated in Fig. 2. It will be readily apparent to the skilled man that alternatively. a single bar 24 could be used. preferably located axially along the pile section 10, or a greater number of bars 24 could be used. The choice of number and location of reinforcing bars 24 will depend on the intended purpose of the pile being formed. and thus on the loadings to be carried.

For ease of reference in Fig. 2, the pile sections shown in Fig. 2 are given reference numerals 10a and lob representing. respectively, the upper and lower pile sections shown in that drawing. As can be seen, the bars 24 of the upper section 10a project down from the body 22, to be proud of the body 22. A band 26 may be provided around the bodies 22 of both sections 10a, 10b to strengthen the bodies 22, particularly against splitting during compressive loading.

The projecting ends of the bars 24 form a male component of the joints, while the upper end of the section 10b is formed as a female portion of the joint, as can now be described.

Within the body 22 of the section lob. the bars 24 end some distance below the upper face 28 of the lower pile section 10b. They carry connection devices 30, each of which is the same in form and thus only one needs to be described in detail. One of the devices 30 is shown on an enlarged scale on Fig. 3. to which reference should also be made.

The device 30 consists of two main parts. namely a lower crimp portion 32, and an upper collet arrangement 34. The crimp portion 32 consists of a length of tubular material fitted over the bar 24 at the lower end of the crimp portion 32, the walls of the crimp portion 32 then being crimped at 36 to grip the bar 24, thereafter securing the crimp portion 32 to the bar 24. The crimp portion 32 is crimped to the bar 24 during manufacture of the section 10b. before the bar 24 is embedded in the body 22.

The collet arrangement 34 includes a tube member 40 which has a lower mouth at 42. having an internal thread at 38, allowing the tube member 40 to be threadedly secured to the crimp portion 32. which is externally threaded at 38, thereby mounting the collet arrangement 34 on the bar 24 by way of the crimp portion 32 acting as an intemiediate member.

The internal walls of the tube member 40 are parallel sided at the lower mouth, to allow threaded engagement, as aforesaid. However, the walls taper together toward the upper end 44 of the collet arrangement 34. forming an upper mouth 46 which is narrower than the passage 48 lower down the collet arrangement 34. The tapering walls of the passage 48 below the mouth 46 form a generally frusto-conical passage, the significance of which will become apparent below.

A set of collar parts 50 are provided within the frusto-conical section of the passage 48. There may be three or more parts 50 arranged around the walls of the passage 48. The collar parts 50 define between them a space 52 which has parallel sides. aligned with the axis of the passage 48 and the bar 24, but outer surfaces which are tapered. preferably being substantially frusto-conical and complementary with the frusto-conical walls of the passage 48.

Accordingly, movement of a collar part S0 toward or away from the upper mouth 46 will cause the part 50 to move closer to, or away from the central axis 54 of the passage 48 and bar 24, while the inwardly facing face of the part 50 will remain parallel with the axis 54. Moving the collar parts 50 in this way will cause the space 52 to contract or expand according to the axial position of the parts 50. Circumferential gaps between adjacent collar parts 50 will also increase or reduce.

The collar parts 50 are resiliently urged toward the upper mouth 46, thus to the position in which the space 52 is most contracted. by means of a helical compression spring 56 which acts between the lower edges of the collar parts 50, and the upper edge of the crimped portion 32.

By virtue of the arrangements described above, a joint can be formed between the sections 10a, 10b by introducing the exposed lower end of the bar 24 of the section 10a into the upper mouth 46 of the collet arrangement 34. As the bar 24 penetrates further into the collet arrangement 34. the collar parts 50 will tend to be pushed down the passage 48 against the action of the spring 56, thus allowing them to move apart, releasing any grip on the bar 24 and allowing free downward movement of the bar 24. The bar 24 will be free to pass down through the spring 56 until eventually being arrested by abutment with the upper end of the bar 24 of the section 10b.

Thereafter, any attempt to remove the bar from the mouth 46 will tend to cause the collar parts 50 to be pulled toward the mouth 46 and thus to be pressed laterally inwardly, to grip the bar 24. As the withdrawing force is increased. so the gripping force is also increased. thus resulting in a secure joint which cannot be disconnected without deliberately damaging the section 10a. lob. The pile joint thus formed is therefore capable of conveying tension forces between adjacent sections 10.

When the joint is formed, the end faces of the pile sections 10 may be in abutment or alternatively, a gasket 58 may be provided between them.

It will be apparent from the above description that pile sections manufactured in the manner described can be connected together in a simple manner, merely by introducing the exposed bar ends into the collet mouths. the pile sections thereafter being driven together by virtue of the pile driving process. The result is a joint which is readily and reliably formed. requiring no mechanical adjustment or manual intervention, locking or the like, other than to ensure that the bars enter the mouths 46. Consequently, the final performance of the joint can reliably be assumed on the basis of the method of manufacture of the pile section 10, being substantially independent of the skill of workers used for installing the piles.

A modified form of the connection device can now be described. with reference to Fig. 4.

Fig. 4 illustrates pile sections which each consist of a body 62 of cementitious material, through which elongate reinforcing bars 64 extend, and which are exposed at the end faces 66 of the body 62. The end faces 66 are recessed at 67, so that the ends 68 of the bars 64 are exposed but do not project beyond the end faces 66. Both ends of both pile sections have the same form as is shown in Fig. 4. The ends 68 of the reinforcing bars 64 are used for connecting pile sections together by means of devices 70, in accordance with the invention. Each device 70 consists of two collet arrangements 72, each of the type described above in relation to Figs. 2 and 3, and arranged “back-to- back", i.e. to face in opposite. axially aligned directions. An intermediate member 74. in the form of a short, externally threaded tube, is threadedly attached to both collet arrangements 72 (in the manner in which the crimp portion 32 is attached to the collet arrangement 34 in Figs. 2 and 3) to connect them together. The devices 70 can therefore receive bar ends 68 from two adjacent pile sections 60. As these are introduced into the collet arrangements 72. they will be irreversibly held. thus forming a secure joint between the pile sections 60. the strength of the joint being set by the construction of the devices 70, as has been described above. The combined depth of the recesses 67 is such that the reinforcing bar ends 68 can be driven home to fully engage the devices 70 as the end faces 66 come into abutment. The joint is thus able to bear compression forces by direct contact between the faces 66, and tension forces between the bars 64. through the devices 7.

Various modifications can be made to the apparatus described above, without departing from the scope of the present invention. In particular, many different shapes, sizes and relative shapes and sizes of the various components can be chosen. according to the loads to be encountered in use, the strength of materials from which components are manufactured. and the like, as will be apparent to the skilled reader.

Claims (11)

Claims

1. A pile connection device for use in connecting pile sections of the type which comprise a body of cementitious material through which at least one elongate reinforcing member extends. the device comprising first and second attachment arrangements which. in use, attach to ends of reinforcing members of respective pile sections. thereby connecting the sections. and wherein at least one of the attachment arrangements is in the form of a collet arrangement which receives the end of a reinforcing member when pushed thereon. and which grips the said end substantially to prevent removal thereafter.

2. A pile connection device according to claim 1. in which the first attachment arrangement is a collet arrangement, the second attachment arrangement providing for permanent attachment to a reinforcing member during manufacture of a pile section.

3. A pile connection device according to claim 2. in which the second attachment arrangement comprises a tubular deformable member for attachment by crimping around one of the reinforcing members.

4. A pile connection device according to claim 1, in which the first and second attachment arrangements are collet arrangements. whereby the device. in use, is operable to connect adjacent pile sections by pushing the collet arrangements over the ends of the reinforcing members of respective pile sections.

5. A pile connection device according to any preceding claim. in which the or each collet arrangement comprises a plurality of collar parts which together define between them a space for receiving a reinforcing member to form a collar therearound. the collar parts together defining a tapering outer surface for the collar and being located within a tapering passage. and there being resilient bias means operable to urge the collar toward the narrow end of the 9 passage, whereby an elongate member may be pushed into the space from the narrow end of the passage by moving the collar against the resilient bias to allow the space to expand. the elongate member being thereafter gripped against removal through the narrow end by contraction of the collar as it is drawn toward the narrow end.

6. A pile connection device according to claim 5. in which the outer surface and the passage are frusto-conical.

7. A pile section for connection in end—to-end relationship with like pile sections, and comprising a body of cementitious material through which at least one elongate reinforcing member extends. the or each reinforcing member having a first male end exposed by the cementitious body, and the pile section comprising a connection device according to any preceding claim, attached to the second end of the or each reinforcing member to provide the or a collet arrangement exposed for receipt of the male end of a reinforcing member of another pile section, thereby connecting the pile sections together.

8. A method of connecting pile sections of the type comprising a body of cementitious material through which at least one elongate reinforcing member extends. the ends of which are proud of the cementitious body. wherein connection devices according to claim 4. or any claim dependent on claim 4. and each having the first and second attachment arrangements in the form of collet arrangements are pushed over the ends of reinforcing members of respective pile sections.

9. A pile connection device, substantially as described above, with reference to the accompanying drawings.

10. A pile section. substantially as described above. with reference to the accompanying drawings.

11.. . A method of connection pile sections, substantially as described above, with reference to the accompanying drawings. MACLACHLAN & DONALDSON Applicants’ Agctns,