Coupler for coupling driven steel pipe piles

Abstract

A coupler for coupling together a lead pile segment and an extension pile segment of a driven pile comprises: a cylindrical pipe segment, having first and second formed ends and a cylindrical body extending therebetween, each of the first and second formed ends having an inner diameter that is greater than an inner diameter of the cylindrical body. The first formed end is sized to snugly receive an end of the lead pile segment and the second formed end is sized to snugly receive an end of the extension pile segment. Each of the first and second formed ends has an initial length. When an axial force is applied to the extension pile segment, each of the first and second formed ends undergo secondary end forming to thereby achieve a final length of each formed end, wherein the final length exceeds the initial length of each formed end.

Claims

1. A coupler for coupling together a lead pile segment and an extension pile segment of a driven pile, the coupler comprising: opposite first and second cylindrical formed ends, each end of the first and second cylindrical formed ends opening in an opposite direction of the other formed end; wherein each of the first and second cylindrical formed ends transition, via a corresponding first or second radiused bend, to an at least one cylindrical hollow member extending between the opposite first and second cylindrical formed ends, wherein the first and second cylindrical formed ends, the at least one cylindrical hollow member and the first and second radiused bends together form a single coupler; wherein each of the first and second cylindrical formed ends have an inner diameter that is greater than an outer diameter of the at least one cylindrical hollow member; wherein the first cylindrical formed end is sized to snugly receive an end of the lead pile segment, the lead pile segment bearing against the first radiused bend, and the second cylindrical formed end is sized to snugly receive an end of the extension pile segment, the extension pile segment bearing against the second radiused bend; and wherein the coupler comprises first and second external rings, the first external ring affixed to an external surface of the at least one cylindrical hollow member and proximate to the first radiused bend and the second external ring affixed to the external surface of the at least one cylindrical hollow member and proximate to the second radiused bend of the coupler; and wherein, when an axial force is applied to the extension pile segment to drive the ends of the lead and extension pile segments into the coupler, the end of the lead pile segment is cold extruded through a section of the at least one cylindrical hollow member that is encircled by the first external ring and the end of the extension pile segment is cold extruded through a section of the at least one cylindrical hollow member that is encircled by the second external ring.

2. The coupler of claim 1 wherein the first external ring is affixed to the external surface of the at least one cylindrical hollow member and adjacent to, so as to abut against, the first radiused bend, and wherein the second external ring is affixed to the external surface of the at least one cylindrical hollow member and adjacent to, so as to abut against, the second radiused bend.

3. The coupler of claim 1 wherein the at least one cylindrical hollow member comprises at least one pipe segment.

4. The coupler of claim 1 wherein the at least one cylindrical hollow member comprises a first pipe segment adjacent the first cylindrical formed end and a second pipe segment adjacent the second cylindrical formed end.

5. The coupler of claim 4 wherein each segment of the first and second pipe segments comprises a plate end opposite of the respective first and second cylindrical formed ends, and the coupler further comprising a plate affixed to the plate ends of each of the first and second pipe segments.

6. The coupler of claim 5 wherein a diameter of the plate is substantially equal to an outer diameter of the plate end of the first and second pipe segments.

7. The coupler of claim 5 wherein the inner diameter of the first cylindrical formed end is greater than or less than the inner diameter of the second cylindrical formed end.

8. The coupler of claim 7 wherein the plate has a diameter approximately equal to an outer diameter of the plate end of the first or second pipe segment having the greatest outer diameter.

9. The coupler of claim 5 wherein the first external ring is affixed to an external surface of the first pipe segment between the plate and the first cylindrical formed end and the second external ring is affixed to an external surface of the second pipe segment between the plate and the second cylindrical formed end; wherein, when the axial force is applied to the extension pile segment the ends of the lead and extension pile segments are driven towards the plate, and the end of the lead pile segment is cold extruded through a section of the first pipe segment that is encircled by the first external ring and the end of the extension pile segment is cold extruded through a section of the second pipe segment that is encircled by the second external ring.

10. The coupler of claim 9 wherein the first external ring is affixed to the external surface of the first pipe segment and adjacent to, so as to abut against, the first radiused bend, and wherein the second external ring is affixed to the external surface of the second pipe segment and adjacent to, so as to abut against, the second radiused bend.

11. The coupler of claim 1 wherein a wall thickness of each of the opposite first and second cylindrical formed ends is equal to or greater than a wall thickness of the corresponding lead pile segment or extension pile segment of the driven pile.

12. The coupler of claim 1 wherein the at least one cylindrical hollow member is at least one elongated cylindrical hollow member.

Description

BRIEF DESCRIPTION OF THE FIGURES

(1) FIG. 1A is a profile view of a prior art pile coupling wherein the two pile segments are spliced together by welding and using a reinforcing backing ring;

(2) FIG. 1B is a sectional view of a prior art pile coupling comprising a welded fit splice sleeve;

(3) FIG. 1C is a sectional view of a prior art pile coupling comprising a drive fit splice sleeve;

(4) FIG. 1D is a perspective view of a prior art pile coupling comprising a rebar cage;

(5) FIG. 1E is a sectional view of a prior art pile coupling comprising a spigot and socket coupler manufactured of ductile iron;

(6) FIG. 2A is a sectional view of the ends of lead and extension pile segments inserted into opposite ends of an embodiment of a pile coupler, the pile coupler comprising a cylindrical pipe segment with first and second opposite formed ends;

(7) FIG. 2B is a sectional view of the embodiment of a pile coupler illustrated in FIG. 2A, where application of a driving force to the extension pile segment has resulted in secondary end forming at the first and second opposite formed ends of the coupler;

(8) FIG. 3A is a sectional view of the ends of lead and extension pile segments inserted into opposite ends of a further embodiment of a pile coupler, the pile coupler comprising a cylindrical pipe segment with first and second opposite formed ends and first and second external rings positioned adjacent to the first and second opposite formed ends;

(9) FIG. 3B is a sectional view of the embodiment of a pile coupler illustrated in FIG. 3A, where application of a driving force to the extension pile segment has resulted in secondary end forming and cold extrusion through the external ring sections at the first and second opposite formed ends of the coupler;

(10) FIG. 4 is a sectional view of the ends of lead and extension pile segments inserted into opposite ends of a further embodiment of a pile coupler, the pile coupler comprising two cylindrical pipe segments welded to plate, the free ends of each cylindrical pipe segment comprising a formed end to provide first and second opposite formed ends of the coupler;

(11) FIG. 5A is a sectional view of the ends of lead and extension pile segments inserted into opposite ends of a further embodiment of a pile coupler, the pile coupler comprising two cylindrical pipe segments welded to plate, the free ends of each cylindrical pipe segment comprising a formed end to provide first and second opposite formed ends of the coupler, wherein the two cylindrical pipe segments of the pile coupler in FIG. 5A are longer than the two cylindrical pipe segments of the pile coupler in FIG. 4;

(12) FIG. 5B is a sectional view of the embodiment of a pile coupler illustrated in FIG. 5A, where application of a driving force to the extension pile segment has resulted in secondary end forming at the first and second opposite formed ends of the coupler;

(13) FIG. 6A is a sectional view of the ends of lead and extension pile segments inserted into opposite ends of a further embodiment of a pile coupler, the pile coupler comprising two cylindrical pipe segments welded to plate, the free ends of each cylindrical pipe segment comprising a formed end to provide first and second opposite formed ends of the coupler and first and second external rings positioned and affixed adjacent to the first and second opposite formed ends;

(14) FIG. 6B is a sectional view of the embodiment of a pile coupler illustrated in FIG. 6A, where application of a driving force to the extension pile segment has resulted in secondary end forming and cold extrusion through the external ring sections at the first and second opposite formed ends of the coupler.

DETAILED DESCRIPTION

(15) As shown in FIGS. 2A and 2B, an embodiment of the pile coupling 10 of the present disclosure comprises a cylindrical pipe segment 12. The cylindrical pipe segment 12 has opposite first and second formed ends 15, 17, and a cylindrical body 13 extending therebetween. The cylindrical body 13 has an outer diameter OD1, and each of the formed ends 15, 17 have an outer diameter OD2, OD3, respectively. The outer diameters OD2, OD3 of the formed ends 15, 17 are greater than the outer diameter OD1 of the cylindrical body 13. The formed end 15 smoothly transitions to the cylindrical body 13 of the cylindrical pipe segment 12 with a smooth, radiused bend 16. Likewise, the formed end 17 smoothly transitions to the cylindrical body 13 of the cylindrical pipe segment 12 with a smooth, radiused bend 18.

(16) The inner diameter ID2 of the formed end 15 is sized to snugly receive the end 21 of the extension pile segment 20. For example, the inner diameter ID2 of the formed end 15 may be equal to, or approximately equal to, the outer diameter OD4 of the extension pile segment 20, so that the formed end 15 of the coupler 10 snugly receives the end 21 of the extension pile segment 20. Likewise, the inner diameter ID3 of the formed end 17 may be equal to, or approximately equal to, the outer diameter OD5 of the lead pile segment 30, so that the formed end 17 of the coupler 10 snugly receives the exposed end 32 of the lead pile segment 30, the exposed end 32 of the lead pile segment 30 protruding from the ground G. Although the embodiment illustrated in FIGS. 2A and 2B shows that the outer diameters OD4, OD5 of the extension and lead pile segments are approximately equal, and the inner diameters ID2, ID3 of the formed ends 15, 17 are approximately equal, it will be appreciated that the couplers disclosed herein may be configured for coupling together pile segments having different outer diameter measurements. In such embodiments (not shown), the coupler 10 would be manufactured so that the inner diameters ID2, ID3 of the formed ends 15, 17 are appropriately sized to receive the outer diameters of the lead and extension pile segments that are to be coupled together. Likewise, throughout the rest of this description, it will be appreciated that the formed ends 15, 17 of the different embodiments of a coupler 10 may have inner and outer diameters, respectively, that are equal to each other (in cases where two pile segments to be coupled together have equal diameters). In other embodiments, the formed ends 15, 17 of the different embodiments of a coupler described herein may have inner and outer diameters, respectively, that are not equal to each other (in cases where the two pile segments to be coupled together have different diameters).

(17) FIG. 2B shows the movement of the ends 21, 32 of the extension and lead pile segments 20, 30 towards one another and through the coupler 10, after an axial driving force F has been applied to the driven end (not shown) of the extension pile segment 20. As shown in FIG. 2B, after an axial driving force F has been applied, the ends 21, 32 of the extension and lead pile segments 20, 30 are closer to one another, as compared to FIG. 2A. As well, a final length L1b of the formed end 15 and a final length of L2b of the formed end 17 have each increased, as compared to the initial lengths L1a, L2a of the formed ends 15, 17 shown in FIG. 2A.

(18) Due to the application of the axial driving force F to the driven end of the extension pile segment 20, the force F has pushed the end 21 of the extension pile segment 20 into coupler 10, so that the end 21 progresses axially further into the coupler 10. This movement of the end 21 into the coupler 10 causes the radial deformation of the walls of the cylindrical pipe segment 12, a process referred to herein as secondary end forming. The secondary end forming process thereby increases the initial length L1a of the first formed end 15 to a final length L1b. The Applicant has discovered that secondary end forming in the coupler 10 occurs above a certain threshold value of the axial force F that is applied to the extension pile segment 20. The threshold value is strongly correlated to the yield strength of the material of the pipe (or pipes) used to manufacture the coupler 10. The threshold value is also strongly correlated to the ratio of the diameter of the pipe segment (D) to the thickness of the wall of the pipe (t) used to manufacture the coupler 10. Generally speaking, the threshold value of the axial force F for initiating the secondary end forming process in the coupler 10, during installation of an extension pile segment using the couplers 10 described herein, will increase when a higher yield strength pipe is used to manufacture the coupler 10. Furthermore, a greater thickness (t) of the pipe used to manufacture the coupler 10 will also increase the threshold value of the axial force F required to initiate secondary end forming in the coupler 10 during installation of an extension pile segment.

(19) Furthermore, the end 21 of the extension pile segment 20 pushes on the radiused bend 16, and the frictional force between the exterior surface 20a of the end of the extension pile segment 20 and the interior surface 15a of the formed end 15 of the coupler, transmit the driving force F to the coupler 10 to move the coupler 10 towards the ground G. The driving force F causes the end 32 of the lead pile segment 30 to exert a force on the radiused bend 18 of the formed end 17, thereby radially deforming the walls of the cylindrical pipe segment 12 as the end 32 of the lead pile segment 30 pushes further into the coupler 10. This also causes secondary end forming that increases the initial length L2a of the second formed end to a final length L2b. For example, not intended to be limiting, the secondary end forming process may result in increasing the initial lengths La, L2a of each of the formed ends 15, 17, shown in FIG. 2A, by a distance of approximately six to twelve inches (15 cm to 30 cm), to arrive at the final length L1b, L2b of the formed ends 15, 17 shown in FIG. 2B. Furthermore, the frictional force between the exterior surface 30a of the end of the lead pile segment 30 and the interior surface 17a of the formed end 17 of the coupler, and the frictional force between the exterior surface 20a of the end of the extension pile segment 20 and the interior surface 15a of the formed end 15 of the coupler, increases with the increased lengths L1b, L2b of the formed ends 15, 17, which provides increased lateral and tension force resistance of the pile coupling. Such lateral and tension resistance of the resulting coupling may be obtained, in some embodiments, without any welding between the pile segments and the coupler 10.

(20) As the driving force F continues to be applied to the driven end of the extension pile segment 20, both the lead and extension pile segments 30, 20 are driven further into the ground G while at the same time providing for tighter coupling of the segments 20, 30, as the exposed ends 21, 32 of the extension and lead pile segments 20, 30 move further into the coupler 10.

(21) The Applicant has found that the secondary end forming process, whereby the initial length L1a, L2a of each of the formed ends 15, 17 of the coupler 10 is increased to reach a final length L1b, L2b, which provides for a stronger coupling with increased frictional resistance to compressive, lateral and tension loads, as compared to other coupling methods. With this increased frictional resistance, the extension pile segment 20 resists being pulled apart upwardly in direction B, bending laterally, or compressing downwardly in direction F once the pile installation has been completed to design specifications.

(22) Optionally, after the driving force F has been applied but before the coupler 10 is driven beneath the surface of the ground G, a fillet weld (not shown) may be applied at ends 15 and 17, at the junction with the lead pile segment 30 and the extension pile segment 20, to provide additionally increased resistance to tension forces applied to the extended pile in direction B. Thus, in such embodiments, once a fillet weld is applied to the coupler 10 at either end connection coupler 10 to pile segments 20 and 30, no additional secondary end forming would occur, and the formed end serves the function of fitting over the exposed end 32 of the lead segment. Although the optional installation method of applying a fillet weld involves field welding, the Applicant finds such field welding is minimal as compared to other coupling methods known in the art. Furthermore, applying fillet weld avoids the cost of requiring a pre-manufactured coupling sleeve added to the pile segments, as is known in the prior art and shown, for example in FIGS. 1B and 1C.

(23) In the embodiment illustrated in FIGS. 3A and 3B, the coupler 10 further comprises external affixed or welded ring portions. The illustrated embodiment, for example, includes two external rings 45, 47, which is a metal ring having an inner diameter ID1 that is approximately equal to an outer diameter OD1 of the cylindrical body 13 of the cylindrical pipe segment 12, such that the external rings 45, 47 encircle the cylindrical body 13. In the illustrated embodiment of FIGS. 3A and 3B, the external rings 45, 47 are positioned adjacent to the radiused bends 16, 18 of the first and second formed ends 15, 17. However, in other embodiments (not illustrated), the external rings 45, 47 may be positioned on the cylindrical body 13 at a distance from the radiused bends 16, 18, which configuration would allow additional secondary end forming to occur when the driving force F is applied to the extension pile segment 20. The coupler 10 may thus be configured in different ways to provide for different properties of the pile coupling, such as providing for additional tension, compression or lateral (bending moment) resistance, or to control for the extent of secondary end forming that occurs or the distance that the pile segments are driven into the coupling 10 during installation.

(24) When an axial driving force F is applied to the extension pile segment 20, as shown in FIG. 3B, the end 21 of the extension pile segment will travel downwards in direction A such that the extension pile segment 20 is driven farther into the coupling 10. However, because the external ring 45 exerts radial tension against the exterior surface 13a of the cylindrical body 13, the walls of the cylindrical body 13 resist radially outward deformation at the location of the external ring 45. Thus, the secondary end forming process is prevented up to a threshold driving force applied by the piling rig hammer. If the driving force is increased beyond that threshold, the end 21 of the extension pile segment 20 will begin to compress radially inwardly, and extrude through the inner diameter ID4 of the cylindrical body 13 of the coupler 10, as shown in FIG. 3B. The resulting extruded portion 23 of the end 21 of the extension pile segment 20 has an outer diameter OD7 that is approximately equal to the inner diameter ID4 of the cylindrical body 13 of the coupler 10. Furthermore, a final length L3b of the overlapping portion between the extension pile segment 20 and the coupler 10, shown in FIG. 3B, is greater than the initial length L3a of the overlapping portion between the extension pile segment 20 and the coupler 10, shown in FIG. 3A.

(25) Advantageously, and likewise, when the axial driving force F is applied to the extension pile segment 20, because of the external ring 47 exerting radial tension against the exterior surface 13a of the cylindrical body 13, the walls of cylindrical body 13 resist radially outward deformation, and thus secondary end forming is prevented up to a threshold driving force. However, if the driving force is increased beyond that threshold, the coupler 10 moves downward in direction A, and the exposed end 32 of the lead pile segment 30 moves further into the coupler 10 by starting to compress radially inwardly to thereby extrude through the inner diameter ID4 of the cylindrical body 13 of the coupler 10. A final length L4b of the overlapping portion between the lead pile segment 30 and coupler 10, shown in FIG. 3B, is greater than the initial length L4a of the overlapping portion between the lead pile segment 30 and the coupler 10, shown in FIG. 3A. The resulting extruded portion 33 of the end 32 of the lead pile segment 30 has an outer diameter OD6 that is approximately equal to the inner diameter ID4 of the cylindrical body 13 of the coupler 10. Applicant has discovered that this extrusion action greatly increases the friction resistance between the outer walls of the extension segment 20 and the lead segment 30, and the inner wall of coupler 10, providing a further increase in the resistance of the coupling to compressive, lateral (bending moment) and tension loads applied to the installed pile. Additionally, the Applicant hypothesizes that the dual overlapping areas between pile segments and the coupler, created through the extrusion process, lend additional resistance of the installed coupling to compressive, lateral (bending moment) and tension loads applied to the installed pile. A further advantage of the two areas of overlap, as between the lead and extension pile segments 30, 20 and the coupler 10, is that such dual areas of overlap and frictional engagement allows for higher capacities of the installed pile using shorter couplers, with less secondary forming and/or cold extrusion distance required to attain such higher capacity of the installed pile to resist compressive, lateral and tension loads applied to the installed pile, as compared to coupling methods that involve only a single area of overlap between the coupler and the lead or extension pile.

(26) In further embodiments, with reference to FIGS. 4 to 6B, a coupler 10 has opposite first and second formed ends with a plate inserted between the first and second formed ends. In one such embodiment, illustrated in FIG. 4, the coupler 10 comprises first and second cylindrical pipe segments 14, 19. Each cylindrical pipe segment has a formed end 14a, 19a and an opposite plate end 14b, 19b, the plate ends 14b, 19b each welded to opposite planar surfaces of a central plate 40. Each cylindrical pipe segment 14, 19 also has a body portion 14c, 19c, the body portion 14c, 19c each having an outer diameter OD10 that is less than an outer diameter OD11 of the corresponding formed end 14a, 19a.

(27) In use, the end 21 of the extension pile segment 20 and the exposed end 32 of the lead pile segment 30 are each inserted into the respective formed ends 14a, 19a before a driving force is applied to the extension pile segment 20. Although not shown in the example embodiment of FIG. 4, when a driving force is applied to the extension pile segment 20, a secondary end forming process may occur as the end 21 of the extension pile segment 20 pushes past the radiused bend 16, driving the end 21 of the extension pile segment 20 further into the coupler 10 towards the plate 40 by radially deforming the walls of the first cylindrical pipe segment. Similarly, secondary end forming may occur as force is applied to the coupler 10, thereby moving the coupler 10 downward in direction A and causing the exposed end 32 of the lead pile segment 30 to push upwardly against the radiused bend 18 of the formed end 19a, thus radially deforming the walls of the second cylindrical pipe segment 19 as the exposed end 32 moves towards the plate 40. In the example shown in FIG. 4, the length L5 of the body portions 14c, 19c of the cylindrical pipe segments 14, 19 are relatively short, which may allow a limited amount of secondary end formation to occur before the ends 21, 32 of the pile segments 20, 30 are stopped by the welds 42 that affix the first and second cylindrical pipe segments 14, 19 to the opposite planar surfaces of the plate 40.

(28) Once the ends 21, 32 of the extension and lead pile segments 20, 30 come into close proximity to the exterior welds 42, the walls of the cylindrical pipe segments 14, 19 are restricted from further radial expansion of the respective body portions 14c and 19c.

(29) In a preferred embodiment, without intending to be limiting, the initial lengths L6a, L6a of the formed ends 14a, 19a may be in the range of at least six to twelve inches (15 to 30 cm). The applicant has found that, although the initial lengths L6a, L6a of the formed ends 14a, 19a may be less than six inches, if the initial length L6a of each of the formed ends 14a, 19a is too short, the reduced overlap between the pile segments 20, 30 and the coupler's cylindrical pipe segments 14, 19, prior to or during when the driving force is applied, may cause the pile segments to become unstable and move out of position such that the coupler cannot be installed. Furthermore, if the final length of the overlapping region between the pile segments and the coupler is too short, the coupling may not provide sufficient resistance to the forces acting on the installed pile. These factors, in addition to the factors of the specifications of the installed pile and the lengths of the pile segments used for installation, may inform selection of the initial length of the formed ends of the coupler 10.

(30) The embodiment illustrated in FIGS. 5A and 5B is similar to the embodiment illustrated in FIG. 4, except that the initial lengths L5a, L5a of the body portions 14c, 19c of each cylindrical pipe segment 14, 19, shown in FIG. 5A, is greater than the initial lengths L5, L5 of the body portions 14c, 19c of each cylindrical pipe segment 14, 19 shown in FIG. 4. When a driving force F is applied to the extension pile segment 20, the end 21 of the extension pile segment 20 pushes against the radiused bend 16 of the formed end 14a and thereby radially deforms the walls of the first cylindrical pipe segment 14 in a secondary end forming process. Likewise, the coupler 10 is forced downwardly by the driving force F applied to the extension pile segment 20, therefore causing the exposed end 32 of the lead pile segment 30 to be pushed further into the coupler 10. The exposed end 32 pushes against the radiused bend 18, and when sufficient force F is applied, the exposed end 32 radially outwardly deforms the walls of the second cylindrical pipe segment 19 via a secondary end forming process. As a result of the secondary end forming processes acting on the first and second cylindrical pipe segments 14, 19 of the coupler 10, the final lengths L6b, L6b of the formed ends 14, 19, as shown in FIG. 5B, are greater than the initial lengths L6a, L6a of the formed ends 14, 19 shown in FIG. 5A. Similar to the embodiment illustrated in FIG. 4, it appears that the weld seams 42, affixing the plate ends 14b, 19b of the cylindrical pipe segments 14, 19 to respective opposite planar surfaces of the plate 40, limits the radially outward expansion of each respective cylindrical pipe segment 14, 19 when the ends 21, 32 of the extension and lead pile segments 20, 30 reach a location proximate to the welds 42, thus preventing further secondary end formation.

(31) Referring to FIGS. 6A and 6B, a further embodiment of the coupler 10 is similar to the embodiment illustrated in FIGS. 5A and 5B, except that the coupler 10 of FIGS. 6A and 6B further comprises first and second external rings 45, 47 welded or otherwise affixed to an exterior surface of each of the body portions 14c, 19c of the first and second cylindrical pipe segments 14, 19. As shown in FIG. 6A, before a driving force is applied to the extension pile segment 20, the end 21 of the extension pile segment 20 has an initial outer diameter OD12. The initial outer diameter OD12 of the extension pile segment 20 is approximately equal to the inner diameter ID10 of the formed end 14a, such that the end 21 of the extension pile segment 20 is snugly received within the formed end 14a. Likewise, the outer diameter OD13 of the end 32 of the lead pile segment 30 is approximately equal to the inner diameter ID11 of the formed end 19a, such that the end 32 of the lead pile segment 30 is snugly received within the formed end 19a.

(32) When a driving force F is applied to the extension pile segment 20, the end 21 of the extension pile segment pushes against the radiused bend 16 of the formed end 14a. However, secondary end forming is prevented by the external ring 45 encircling, and welded to, the exterior surface of the body portion 14c of the first cylindrical pipe segment 14, up to a threshold axial driving force. Once that threshold driving force is exceeded, the end 21 of the extension pile segment is radially inwardly compressed, so as to be cold extruded through, the section of the body portion 14c that is encircled by the external ring 45, as shown in FIG. 6B. As a result of the cold extrusion process, a final outer diameter OD14 of the end 21 of the extension pile segment 20, as shown in FIG. 6B, is less than the initial outer diameter OD12 of the end 21 of the extension pile segment 20, as shown in FIG. 6A. As well, the final outer diameter OD14 of the end 21 of the extension pile segment 20 is approximately equal to the inner diameter ID13 of the body portion 14c of the first cylindrical pipe segment 14.

(33) Likewise, the driving force F is transmitted through the coupler 10 to move the coupler 10 downwardly in direction A. In the initial position before the driving force F is applied, as shown in FIG. 6A, the exposed end 32 of the lead pile segment 30 is resting against the radiused bend 18 of the formed end 19a, and the exposed end 32 has an initial outer diameter OD13 that is approximately equal to the inner diameter ID11 of the formed end 19a. When the driving force F is applied, as shown in FIG. 6B, the external ring 47, welded to an exterior surface of the body portion 19c of the second cylindrical pipe segment 19, prevents the outward radial deformation of the walls of the second cylindrical pipe segment, up to a threshold axial driving force applied to the extension pile segment 20. However, once the axial driving force F exceeds the threshold, the coupler 10 moves downward in direction A, forcing the exposed end 32 of the lead pile segment 30 to compress radially inwardly, and cold extrude through, the section of the body portion 19c that is encircled by the external ring 47. As viewed in FIG. 6B, the final outer diameter OD15 of the exposed end 32 is now less than the initial outer diameter OD13 of the exposed end 32 of the lead pile segment 30. The final outer diameter OD15 of the exposed end 32 is approximately equal to the inner diameter ID12 of the body portion 19c of the second cylindrical pipe segment 19. As described herein regarding the external ring embodiments of FIGS. 3A and 3B, the Applicant has likewise found that, in respect of the external ring embodiments of FIGS. 6A and 6B, the cold extrusion process occurring at both ends of the coupler 10 described herein may increase the resistance of the installed pile coupling to tension, compression and lateral forces. Additionally, the embodiment shown in FIGS. 6A and 6B includes a plate 40, and the plate and/or the adjacent weld seams 42 may bear some or all of the loads applied to the coupling 10 after installation, further increasing the load limit of the installed pile coupling.

(34) In the embodiments incorporating a plate 40, it will be appreciated that the plate 40 may include a central cut-out (not shown), which would allow for pouring concrete or other materials through the hollow center of the pile segments as may be required for certain applications. It will also be appreciated that the embodiments described herein are not meant to be limiting, but rather, are intended to provide examples of the pile couplings that are included in the scope of the present disclosure. Different combinations of the plate, external ring and formed end characteristics of the pile couplings described herein may be desirable for particular applications and are thus intended to be included in the scope of the present disclosure.

(35) In summary, when the driving force applied to the extension pile exceeds the yield strength of the formed end, secondary end forming may occur (as illustrated, for example, in FIGS. 2A, 2B, 5A and 5B). When secondary end forming occurs, there is increased friction in the resulting coupling, between the inner wall of each of the two formed ends of the coupler and the outer walls of the ends of the lead and extension pile segments, thus providing the pile coupling with higher resistance to compressive, lateral and tension forces acting on the installed pile.

(36) For embodiments in which external rings are added to the coupler, spaced apart from the formed end, the driving (compressive) force applied may be adjusted such that the ends of the extension and lead pile segments perform secondary end forming until the pile segment ends abut against the external ring portion (not shown). In such embodiments, the final length of the formed end of the extension pile, and therefore the extent of secondary end forming that occurs, may be configured by selecting the distance between the respective external rings and the corresponding formed ends of the coupler. Additionally, configuring the pile coupling to have a specified final length of the formed ends (via the secondary end forming process) may also increase the installed pile's resistance to lateral (bending) forces.

(37) Optionally, rather than spacing apart the formed end from the external ring, the coupler may be manufactured so that each external ring abuts against the shoulder of each respective formed end. In such cases, secondary end forming will not occur, but the cold extrusion process will nevertheless provide greater resistance to the tension forces. Examples of such embodiments are shown in FIGS. 3A, 3B, 6A and 6B. In each of the embodiments disclosed herein, the coupler 10 provides for secondary end forming and/or cold extrusion to occur at both ends of the coupler 10, which advantageously provides for two areas of increased frictional engagement to be formed on each installed coupler 10, thereby providing for an overall increase in the resistance of the coupling to lateral (bending), tension and compressive forces acting on the installed pile, as compared to other couplings which provide for only one area of overlap between the coupler and the lead or extension pile segment.

(38) Embodiments of the coupler incorporating a plate positioned in-between the first and second formed ends may offer several advantages. Firstly, the plate provides for controlling the amount of secondary end forming that occurs, by limiting the travel of the ends 21, 32 of the pile segments when a driving force is applied. That is, if the ends 21 or 32 are pushed far enough into the coupler 10 to reach the weld seam 42 between the cylindrical pipe segment and the plate 40, the ends 21 or 32 of the respective extension and lead pile segments 20, 30 will not be able to move further into the coupling 10. Additionally, the plate 40 and/or the weld seam 42 may bear some of the compression and lateral forces applied to the installed pile, which may increase the overall load that the installed pile is capable of bearing. These, and other advantages of the various embodiments described herein, will be recognized by persons skilled in the art.

(39) Further advantageously, for applications requiring coupling together pile segments having different diameters, the inner diameters ID10, ID11 of the formed ends 14a, 19a of the first and second cylindrical pipe segments 14, 19 may not be equal to one another. Thus, the inner diameters ID10, ID11 of the formed ends 14a, 19a of any of the embodiments of the coupler 10 having a central plate 40, may be configured to couple with lead and extension pile segments 30, 20 having different outer diameters OD13, OD12. Due to the ease of manufacturing the couplers 10 disclosed herein, which may, for example, be manufactured out of scrap segments of pipe and plates, it is relatively fast and inexpensive to manufacture couplers 10 that are customized to fit lead and extension pipe pile segments of various different diameters.

(40) An additional advantage of the couplers disclosed herein includes that the initial lengths of the formed ends may be configured to provide for improved alignment and stability of the pile segments to be coupled together, prior to applying the driving force F. The initial length of the formed ends, on each end of the coupler 10, may be configured to allow for sufficient overlap between the coupler's formed ends and the ends 21, 32 of the respective extension and lead pile segments 20, 30 to prevent lateral movement of the extension pile segment, relative to the central axis of the lead pile segment, such that the central axes of the lead and extension pile segments are substantially co-linear. Furthermore, there is a snug fit between the coupler's formed ends and the ends 32, 21 of the lead and extension pile segments, whereby the respective outer diameters of the lead and extension pile segments and the inner diameters of the corresponding formed ends of the coupler are approximately equal to one another. The combined features of the relative length of each of the formed ends, and the relatively snug fit between the coupler's formed ends and the ends of the lead and extension pile segments, provides for the self-alignment of the extension pile segment with the lead pile segment, such that the extension and lead pile segments are approximately co-linear when initially inserted into the coupler 10, prior to applying the driving force F.

(41) This self-alignment feature, and the relative stability of the lead and extension pile segments upon initial insertion into the coupler, provides for more consistent alignment of the extension pile segment with the lead pile segment during installation, leading to an installed pile that is capable of bearing higher loads, as compared to an installed pile where the lead and extension pile segments are mis-aligned or bent at a coupling between two segments.

(42) A further advantage of the couplers disclosed herein, is that the couplers provide for increased tension resistance at the coupling, without requiring welding or other mechanical fastening of the coupler to the pile segments. In some embodiments of the present disclosure, eliminating welding or mechanical fastening between the pile segments and the coupler may reduce the time and expense required for installation of the pile segments. Additionally, as some mechanical fasteners and/or associated flanges for some coupling designs may protrude outwardly from the outer diameter of the coupling, such mechanical fasteners or flanges may increase ground disturbance when the coupling is driven beneath the ground surface. This ground disturbance, during pile installation, may require increased driving force for driving the pile, and may result in forming a cavity between the installed pile and the soil. Whereas, the couplers disclosed herein do not require mechanical fasteners or flanges. The coupler disclosed herein may only protrude outwardly of the respective pile segments by the wall thickness of the coupler. Thus, the design of the couplers disclosed herein reduce or eliminate the ground disturbance that may otherwise occur during pile installation using other couplers known in the art.

(43) The couplers and methods disclosed herein are described in language that is more or less specific as to structural and methodical features. It will be appreciated, however, that the present disclosure is not limited to the specific features shown and described, since the specific features herein disclosed comprise preferred forms of implementing the disclosed couplers, and variants on the features described herein are intended to be included in the scope of the present disclosure described, or described and claimed, herein.

(44) Further, aspects herein have been presented for guidance in the construction and/or operation of illustrative embodiments of the disclosure. Applicant considers these described illustrative embodiments to also include, disclose and describe further inventive aspects in addition to those explicitly disclosed. For example, the additional inventive aspects may include less, more and/or alternative features than those described in the illustrative embodiments. In more specific examples, Applicants consider the disclosure to include, disclose and describe couplers which include less, more and/or alternative steps than those couplers explicitly disclosed, as well as systems, devices or apparatuses which includes less, more and/or alternative structure than the explicitly disclosed structure.