AU2012205694A1 - Sheet pile connecting elements for use in pipe pile retaining walls - Google Patents

Abstract

A weld-on connecting element fox a pipe sheet pile wall assembly includes (1) a base end configured to be welded to a pipe pile wall member, (2) an elongate neck strip having a substantially uniform width and having a length, extending from the base end along a predetermined main assembly direction (X) to an opposite end, which length is at least five times greater than said width, and (3) a claw strip provided at the opposite end having two claw strip members that form an oval-shaped lock chamber with their free ends facing each other to form an open jaw. The claw strip is adapted to partially surround and interlock with a head strip of another, matching connecting element. The space between the two claw-strip members is at least partially filled with a malleable sealant material, installed prior to welding the connector to the pipe piles.

Description

WO 2012/096936 PCT/US2012/020745 1 SHEET PILE CONNECTING ELEMENTS FOR USE IN PIPE PILE RETAINING WALLS BACKGROUND OF THE INVENTION Sheet pile and pipe pile retaining walls have many uses. For example, they are often installed as barriers at seaport facilities to provide vertical walls between land and sea. Fig. 1 illustrates just such a retaining wall made of a row of steel pipes, arranged side by side, which were rammed into the sea floor beneath the water. The pipes extend down through the sandy earth to the bedrock, providing a long lasting barrier, the life of which is limited only by the deleterious effects of corrosion. Fig, 1 shows a pipe pile 32, one of many in the seaside retaining wall 60. The wall supports the earth 62, on one side, from eroding and falling into to the sea 64, on the other. The pipes of the wall, represented by the single pipe 32, pass through the sandy earth 66 beneath the sea floor and are preferably of sufficient length to reach the bedrock 68 below. Although the average level of the sea varies with the tides within a certain range, indicated by the double arrow 70, and waves splash against the wall within a certain average range, indicated by the double arrow 72, the wall of pipes is constructed considerably higher so as to protect against storms and other contingencies. To achieve the total length of pipe required, the pipes are transported to the construction site in convenient (e.g. 20 foot) lengths and WO 2012/096936 PCT/US2012/020745 2 welded end-to-end when they are installed. Depending on the total length of the pipe piles required, and upon the preferences of the contractor, the pipe sections can either be rammed, section by section, and welded together during the ramming process, or they can be welded first, end to end, and rammed as a single lengthy unit. The pipes 32 may be connected together in the manner shown in Figs. 2 and 3, by sheet pile connecting elements 34 that are welded onto opposite sides of each pipe pile prior to ramming the pipe, with its connector, into the earth. The connector on one side of the pipe is interlocked with the mating connector on the previously installed, adjacent pipe prior to ramming, so that the connector of the rammed pipe slides along the mating connector of the installed pipe during the ramming process. Fig. 2 shows such a series of pipe piles 32, arranged along a horizontal line 33 and connected together by the intermediate connecting elements 34, which are affixed to the external, curved surfaces of the piles by welding. Fig. 3 illustrates how two such pipe piles 32 are joined by such connecting elements 34, the details of which are presented in Fig. 4. Prior to ramming, a "male" connecting element 36 is welded to one side of each pipe 32 and a "female" connecting element 38 is welded to the opposite side, over the entire length (or nearly the entire length) of the pipe. The pipes are then driven into the earth, one at a time, with the male connecting element 36, welded to one pipe, inserted in and interlocked with the female WO 2012/096936 PCT/US2012/020745 3 connecting element 38 that is welded to the next, adjacent pipe. Water leakage in the interlock joint between the male and female interlocks can be substantially reduced by the use of a sheet piling interlock sealant, such as the commercial sealant available from PilePro, LLC, Austin, TX, under the registered trademark WADIT. This sealant can be used with all types of hot rolled and cold formed sheet piling interlocks in every type of environment (tropical to arctic), and particularly in marine applications. In addition to seaside retaining walls of the type shown in Fig. 1, such a sealant is useful in any sheet piling project where water leakage through the wall presents a problem, such as with cofferdams and with cutoff walls for site remediation. Tests have shown that leakage through sheet pile walls can be reduced by 95% when interlock sealants are used. Sealed Joint sheet pile cutoff walls are anywhere from 100 to 10,000 times more effective as groundwater flow barriers (sealed walls typically exhibit hydraulic conductivity in the 10-7 to 10-10 cm/sec range) than unsealed interlock walls. Although the sealant is normally inserted in the female interlock claw of Z-shaped or U-shaped sheet piling at the manufacturing facility, or subsequently at the location of a distributor, prior to delivery of the sheet piling and its final installation at the job site, the sealant can also be shipped to the job site where it is heated to its softening temperature in the range of 200 to 300* WO 2012/096936 PCT/US2012/020745 4 Fahrenheit and injected into the claws of the sheet piles and/or sheet pile connectors just prior to ramming. This latter procedure has been used for projects, such as seawalls of the type shown in Fig. 1, where it is necessary to weld the sheet pile connectors to sheet piling or pipe piling at the job site. In this case, the sealant is inserted in the claws of the connecting elements following the welding step to avoid heating the sealant during welding. The heat applied to the base of a connecting element by arc welding is conducted through the element to its claw, causing the sealant to run and disperse. As a result, the claw does not seal properly with the round head of the mating male connecting element. Installing a sealant, such as WADIT@, in a connector claw at a job site is extremely inconvenient at best, and adds an extra, time-consuming step to the installation process. SUMMARY OF THE INVENTION It is a principal object of the present invention to provide a weld-on sheet pile connecting element which can be welded to a pipe pile during installation at a project job site without causing a pre-installed sealant to run or disperse due to the heat of welding. It is a further object of the present invention to provide a method of installing a sealed and welded pipe pile retaining wall using weld-on sheet pile connectors for which the sealant has been applied to the claws of the connectors prior to welding.

WO 2012/096936 PCT/US2012/020745 5 These objects, as well as other objects which will become apparent from the discussion that follows, are achieved, in accordance with the present invention, by providing a weld on connecting element, of the type having a female interlock claw strip, with such a size and shape that sufficient heat is dispersed during the welding process to avoid softening and/or melting of a sealant having a melting temperature in the range of 200 to 300* F. The sealant WADIT@E, in particular, has a melting temperature of approximately 260* F, which is within this range. More particularly, the present invention provides for a weld-on profile connector forming part of an elongate sheet pile connecting element for use in a pipe pile wall assembly comprising (a) a plurality of supporting, elongate pipe pile wall members with their longitudinal axes arranged substantially in parallel and disposed along a common horizontal line, and (b) a plurality of sheet pile connecting elements arranged in parallel with, and welded to, the pipe pile wall members. The weld-on connector is formed of two separate connector elements: both a male and a female element. The female element has (1) a base end configured to be welded to a pipe pile wall member; (2) an elongate neck strip having a substantially uniform width and having a length, extending from the base end along a predetermined main assembly direction (X) to an opposite end, which is at least five times greater than the width; and (3) a claw strip provided at the opposite end having two claw strip members that form WO 2012/096936 PCT/US2012/020745 6 an oval-shaped lock chamber with their free ends facing each other to form an open jaw. The claw strip is adapted to partially surround and interlock with a head strip of the other, matching weld-on connecting element 36. According to the invention, the space between the two claw strip members is at least partially filled with a malleable sealant material, installed prior to welding the connector to the pipe piles. In a preferred embodiment of the weld-on connector element, the two claw strip members are mirror images of each other about the main assembly direction (X). Also, in this embodiment the width of the neck strip is substantially equal to the width of each of the claw strip members. To insure that the sealant does not overheat during welding, it is preferable that the length of the neck strip be not only five, but at least six times greater than its width. This relationship is achieved, for a neck strip having a width of approximately 11.5 mm, if the length of the element, extending from a bottom surface of the base end, configured to be welded to a pipe pile wall member, to a point at the center of the lock chamber, is equal to approximately 88 mm, so that the length of the neck strip alone is approximately 76 mm. For a full understanding of the present invention, reference should now be made to the following detailed description of the preferred embodiments of the invention as illustrated in the accompanying drawings.

WO 2012/096936 PCT/US2012/020745 7 BRIEF DESCRIPTION OF THE DRAWINGS Fig. I is a cross-sectional view of a seaside retaining wall (not to scale) of the type to which the present invention relates. Fig. 2 is an illustration of a row of pipe piles of the type to which the present invention relates, Fig. 3 is a plan view showing two pipe piles linked together by male and female connecting elements, welded to the exterior pipe pile surfaces. Fig. 4 is a detailed plan view of the male and female connecting elements shown in Fig. 3. Fig. 5 is a detailed plan view showing another embodiment of male and female connecting elements that may be used to connect pipe piles. Fig. 6 is a plan view of two pipe piles linked by two Z shaped sheet piles. Fig. 7 is a detailed plan view of the male connecting element shown in Figs. 3 and 4. Fig. 8 is a detailed plan view of the female connecting element shown in Figs. 3 and 4. Fig. 9 is a plan view of the female connecting element of Figs. 3, 4 and 8 with the sealant inserted.

WO 2012/096936 PCT/US2012/020745 8 DESCRIPTION OF THE PREFERRED EMBODIMENTS The preferred embodiments of the present invention will now be described with reference to Figs. 1-9 of the drawings. Identical elements in the various figures are designated with the same reference numerals. According to the invention, it has been discovered that when the sealant is pre-inserted in the claw of the long, weldable connecting element of the type shown in Figs, 4 and 8, prior to welding, heat applied during the welding process does not have a deleterious effect on the sealant. This is apparently due to the fact that the heat of welding is not conducted sufficiently rapidly down the length of the connecting element to melt or otherwise impair the sealant. Fig. 5 shows another type of sheet pile connector 40 that may be used between adjacent pipes 32 to connect the pipes closely together, thus increasing the strength of the retaining wall. This connector 40, which is similar to the connector described in detail in the U.S. Patent No. 7,168,214, comprises a short male element 42 having a head strip 44 and a short female element having an corresponding, interlocking claw strip 46. Conventional Z-shaped sheet piles may also be used as connectors between the load bearing pipe piles, allowing the pipes to be spaced much farther apart in cases where great wall strength is not required. Fig. 6 shows two pipe piles 32, also arranged side by side and longitudinally in parallel, which are separated by two Z-shaped sheet piles WO 2012/096936 PCT/US2012/020745 9 50 and 52 connected to male and female connecting elements 46 and 42, respectively. These connecting elements are, in turn, welded to the external surfaces of the pile piles. If the sealant is pre-applied to the short, weldable female connecting element 46 prior to ramming, the sealant, which hardens somewhat but remains fluid with a high viscosity, melts in part and flows out of the claw when the connecting element is welded. Thereafter, when the respective male connecting element is rammed into the female connector, the resulting seal is inadequate. Figs. 7 and 8 detail the preferred dimensions of the male and female connectors 36 and 38 respectively, that are illustrated in Fig. 4 in interlocked relationship. Fig. 7 shows the end face of the male connecting profile strip (connecting element) 36. This profile strip 36 has a constant cross section when viewed longitudinally, and is in the form of a welded-on strip. For this, the connecting profile strip 36 possesses a base 62, shown to the left in Fig. 7, having a slightly arched cross-sectional shape that simplifies welding of this base onto the arched cross section of the pipe pile 32. A neck strip 64 projects from the base 62 along a main assembly direction X whose free end is shaped into a head strip 66. The head strip 66 possesses an oval cross section with the main axis of the oval head strip 66 extending perpendicular to the main assembly direction X. The head strip 66 matches the shape and form of the head strip of a conventional ball-and-socket sheet pile connection.

WO 2012/096936 PCT/US2012/020745 10 The greatest dimension a of the head strip 66 along the main assembly direction X is about 2 to 2.5 times the thickness b of the neck strip 64. The length c of the neck strip 64 viewed along the main assembly direction X is approximately five times of the greatest dimension d of the head strip 66 viewed along the main assembly direction X, as is shown by the dashed imaginary projection of the oval. Fig. 8 shows the end face of a the female connection profile strip (connecting element) 38 based, The connection profile strip 38 also possesses a base 72 with arched shape, from which a neck strip 74 projects along the main assembly direction X. A claw strip 76 with a C-shaped cross section is formed at the free end of the neck strip 74. The C-shaped claw strip 76 is formed of two arc-shaped, mirror-image claw strips 78 that form a lock chamber 80 and whose free ends point toward each other defining a jaw 82. The arc-shaped progression of the claw strips 78 provide the lock chamber 80 with an essentially oval cross section. The lock chamber 80 is thus of such dimensions that it can receive the head strip 66 of the male connecting profile strip 60 shown in Fig. 7. In the illustrated embodiment, the greatest dimension e of the lock chamber 80 perpendicular to the main assembly direction X is larger than the greatest dimension a of the head strip 66 of the male connecting profile strip 60 perpendicular to the main assembly direction X by a factor of about 1.2.

WO 2012/096936 PCT/US2012/020745 11 The jaw 82 of the claw strip 76 is, in turn, shaped such that the center lines 84 of the free ends of the two claw strips 78 intersect with the axis of symmetry of the claw strip 76 at a point S outside the jaw 82. For this, the separation of the intersection point S to the jaw 82 is preferably 0.5 to 1.5 times the width f of the claw strips 78 which, in turn, is approximately the same as the width of the neck strip 74. The length g of the neck strip 74 essentially corresponds to the length c of the neck strip 64 of the male connecting profile strip 36. The lock chamber 80 of the claw strip 76, thus dimensioned, ensures a secure hold of the claw strip 76, while the head strip 66 on the other hand may be pivoted within a predetermined pivot range within the lock chamber 80. Fig. 9 is an end view of the weldable female connecting element 36 with the sealant 86 pre-installed in the claw in accordance with the invention. It has been discovered that when the sealant is pre-inserted in the claw of a long connecting element of this type prior to welding, heat applied during the welding process does not have a deleterious effect on the sealant. This is apparently due to the fact that the heat of welding is not conducted sufficiently rapidly down the length of the connecting element to melt or otherwise impair the sealant. By providing the female connecting element with a neck strip having a length that is at least five times its width, and preferably even more than six times its width, the heat of welding that is conducted from the base end of the element to the claw strip at its opposite end is insufficient to melt the sealant.

WO 2012/096936 PCT/US2012/020745 12 There has thus been shown and described an improved sheet pile connecting elements for use in pipe pile retaining walls, which fulfill all the objects and advantages sought therefor. Many changes, modifications, variations and other uses and applications of the subject invention will, however, become apparent to those skilled in the art after considering this specification and the accompanying drawings which disclose the preferred embodiments thereof. All such changes, modifications, variations and other uses and applications which do not depart from the spirit and scope of the invention are deemed to be covered by the invention, which is to be limited only by the claims which follow.

Claims (18)

1. A weld-on sheet pile connecting element for use in a pipe pile wall assembly comprising (a) a plurality of supporting, elongate pipe pile wall members with their longitudinal axes arranged substantially in parallel and disposed along a common horizontal line, and (b) a plurality of sheet pile connecting elements arranged in parallel with, and welded to, said pipe pile wall members, said weld-on connecting element comprising (1) a base end configured to be welded to a pipe pile wall member, (2) an elongate neck strip having a substantially uniform width and having a length, extending from the base end along a predetermined main assembly direction (X) to an opposite end, which length is at least five times greater than said width, and (3) a claw strip provided at the opposite end having two claw strip members that form an oval-shaped lock chamber with their free ends facing each other to form an open jaw, said claw strip being adapted to partially surround and interlock with a head strip of another, matching connecting element; wherein the space between the two claw-strip members is at least partially filled with a malleable sealant material.

2. The weld-on profile connector of claim 1, wherein the two claw strip members are mirror images of each other about the main assembly direction (X). WO 2012/096936 PCT/US2012/020745 14

3. The weld-on profile connector of claim 1, wherein the length of the neck strip is at least six times greater than its width.

4. The weld-on profile connector of claim 1, wherein the width of the neck strip is substantially equal to the width of each of the claw strip members,

5. The weld-on profile connector of claim 1, wherein the melting point of the sealant material is in the range of 200 to 300 0 F.

6. The weld-on profile connector of claim 1, wherein the melting point of the sealant material is substantially equal to 260'F.

7. The weld-on profile connector of claim 1, having a length, from a bottom surface of the base end configured to be welded to a pipe pile wall member to a point at the center of said lock chamber, equal to approximately 88 mm.

8. The weld-on profile connector of claim 1, wherein the length of the neck strip is approximately 76 mm.

9. The weld-on profile connector of claim 1, wherein the width of the neck strip is approximately 11.5 mm.

10. In a method of installing a pipe pile wall assembly comprising (a) a plurality of supporting, elongate pipe pile wall members with their longitudinal axes arranged substantially in parallel and disposed along a common horizontal line, and (b) a plurality of sheet pile WO 2012/096936 PCT/US2012/020745 15 connecting elements arranged in parallel with, and welded to, said pipe pile wall members, said weld-on connecting element comprising (1) a base end configured to be welded to a pipe pile wall member, (2) an elongate neck strip having a substantially uniform width and having a length, extending from the base end along a predetermined main assembly direction (X) to an opposite end, which length is at least five times greater than said width, and (3) a claw strip provided at the opposite end having two claw strip members that form an oval-shaped lock chamber with their free ends facing each other to form an open jaw, said claw strip being adapted to partially surround and interlock with a head strip of another, matching connecting element; said method comprising: at least partially filling the space between the two claw-strip members with a malleable sealant material; and thereafter welding the said connecting element to a pipe pile; and thereafter ramming said pipe pile into the ground.

11. The method defined in claim 10, wherein the two claw strip members are mirror images of each other about the main assembly direction (X).

12. The method defined in claim 10, wherein the length of the neck strip is at least six times greater than its width. WO 2012/096936 PCT/US2012/020745 16

13. The method defined in claim 10, wherein the width of the neck strip is substantially equal to the width of each of the claw strip members.

14. The method defined in claim 10, wherein the melting point of the sealant material is in the range of 200 to 3000F.

15. The method defined in claim 10, wherein the melting point of the sealant material is substantially equal to 2600F.

16. The method defined in claim 10, wherein said connecting element has a length, from a bottom surface of the base end configured to be welded to a pipe pile wall member to a point at the center of said lock chamber, equal to approximately 88 mm.

17. The method defined in claim 10, wherein the length of the neck strip is approximately 76 mm.

18. The method defined in claim 10, wherein the width of the neck strip is approximately 11.5 mm.