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Title:
A SHEET PILE
Document Type and Number:
WIPO Patent Application WO/2003/054308
Kind Code:
A1
Abstract:
A sheet pile (28, 30) is disclosed for supporting sub-surface material when the sheet pile has been driven in use into the ground. The sheet pile (28, 30) includes a plurality of substantially flat sheet pile portions (14, 16, 18, 20) and a plurality of fold regions (34), each fold region being disposed at a junction between adjacent substantially flat sheet pile portions and having a substantially rounded cross sectional profile. The sheet pile (28, 30) has a transverse cross section of substantially corrugated configuration including a central trough of substantially flat configuration and first and second crests of substantially flat configuration adjacent the central trough. Transverse dimensions of the central trough and the first and second crests are selected such that optimum strength is obtained; that is, the first and second crests are sufficiently small so as to avoid buckling of the sheet pile at the respective crest or trough during use and are sufficiently large so that strength advantages of substantially flat crests and troughs are obtained.

Inventors:
MENZ GRAHAM HARGRAVE (AU)
Application Number:
PCT/AU2002/001730
Publication Date:
July 03, 2003
Filing Date:
December 20, 2002
Export Citation:
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Assignee:
MENZ GRAHAM HARGRAVE (AU)
International Classes:
E02D5/04; (IPC1-7): E02D5/04
Domestic Patent References:
WO1992019819A11992-11-12
Foreign References:
EP0343913B11994-01-26
GB2300442A1996-11-06
Attorney, Agent or Firm:
Starkie, Steven John (256 Adelaide Terrace Perth, Western Australia 6000, AU)
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Claims:
THE CLAIMS DEFINING THE INVENTION ARE AS FOLLOWS:
1. A sheet pile for supporting subsurface material when the sheet pile has been driven in use into the ground, the sheet pile including a plurality of substantially flat sheet pile portions and a plurality of fold regions, each fold region being disposed at a junction between adjacent substantially flat sheet pile portions and having a substantially rounded cross sectional profile, the sheet pile having a transverse cross section of substantially corrugated configuration including a central trough of substantially flat configuration and first and second crests of substantially flat configuration adjacent the central trough, transverse dimensions of the central trough and the first and second crests being selected such that optimum strength is obtained.
2. A sheet pile as claimed in claim 1, wherein the sheet pile includes a single fold region between each transverse side of the sheet pile and an adjacent substantially flat sheet pile portion extending between a crest and a trough.
3. A sheet pile as claimed in claim 1 or claim 2, wherein two crests and three troughs are provided.
4. A sheet pile as claimed in claim 1 or claim 2, wherein three crests and four troughs are provided.
5. A sheet pile as claimed in any one of claims 1 to 4, wherein the transverse dimension of the central trough is substantially equal to the transverse dimension of each of the first and second crests.
6. A sheet pile for supporting subsurface material when the sheet pile has been driven in use into the ground, the sheet pile including a plurality of substantially flat sheet pile portions and a plurality of fold regions, each fold region being disposed at a junction between adjacent substantially flat sheet pile portions and having a substantially rounded cross sectional profile, the sheet pile having a transverse cross section of substantially corrugated configuration including a central trough of substantially flat configuration and first and second crests of substantially flat configuration adjacent the central trough, transverse dimensions of the central trough and the first and second crests being sufficiently small so as to avoid buckling of the sheet pile at the respective crest or trough during use and being sufficiently large so that strength advantages of substantially flat crests and troughs are obtained.
7. A method of forming a sheet pile for supporting subsurface material when the sheet pile has been driven in use into the ground, said method including the steps of : forming a sheet of material so as to define a sheet pile having a transverse cross section of substantially corrugated configuration including a plurality of substantially flat sheet pile portions and a fold region at each junction between adjacent substantially flat sheet pile portions, each fold region having a substantially rounded cross sectional profile, the sheet pile including a central trough of substantially flat configuration and first and second crests of substantially flat configuration adjacent the central trough; and selecting transverse dimensions of the central trough and the first and second crests such that optimum strength is obtained.
8. A method as claimed in claim 7, wherein the step of forming the sheet of material includes the substep of forming the sheet of material so as to define a single fold region between each transverse side of the sheet pile and an adjacent substantially flat sheet pile portion.
9. A method as claimed in claim 7 or claim 8, wherein the step of forming the sheet of material includes the substep of forming the sheet of material so that the transverse dimension of the central trough is substantially equal to the transverse dimension of each of the first and second crests.
10. A method as claimed in any one of claims 7 to 9, further including the step of selecting a depth dimension of the sheet pile such that the depth is sufficiently small to avoid buckling during use but not so small that strength advantages of a corrugated configuration cross section are negated.
Description:
A SHEET PILE FIELD OF THE INVENTION The present invention relates to a sheet pile for supporting sub-surface material when the sheet pile is driven in use into the ground.

BACKGROUND OF THE INVENTION The mechanics of a pile driving operation are generally well understood. In one method, vibratory hammers are used to impart vibrations to a sheet pile so as to reduce soil resistance and thereby cause insertion of the sheet pile into the ground. Although comparatively low impact forces are required to drive the pile into the ground, the sheet pile must nevertheless be capable of withstanding the driving force imparted by the vibratory hammers, and of withstanding forces imparted by sub-surface material adjacent the sheet pile when the sheet pile has been driven into the ground and sub- surface material removed from one side of the sheet pile.

In recent times, the trend has been to use relatively thin sheet piles of the order of 3mm to 5mm thickness with fold lines interspersed along the width of the sheet pile so as to define a corrugated transverse profile with each fold line defining a longitudinal edge.

However, a disadvantage associated with this type of sheet pile is that weakening and/or tearing of the sheet pile can occur along the edges during or after the sheet pile has been driven into the ground, in particular adjacent transverse sides of the sheet pile.

SUMMARY OF THE INVENTION The applicant has discovered that by replacing the fold lines with fold regions of generally rounded cross sectional profile and by appropriately selecting the width of flat portions of the crests and troughs of a corrugated sheet pile, the strength of the sheet pile for a given sheet pile thickness can be optimised. The width of the flat portion of each crest and trough is selected so as to be sufficiently small to avoid buckling of the

sheet pile at the respective crest or trough during use, though not too small such that strength advantages of generally flat crests and troughs is negated. In this way, it becomes possible to produce a sheet pile of relatively high strength and relatively large overall width using relatively thin sheet pile material, for example of the order of 3mm, and a relatively strong sheet pile of comparable width and strength to known (thicker) sheet piles can be produced at less cost.

In accordance with a first aspect of the present invention, there is provided a sheet pile for supporting sub-surface material when the sheet pile has been driven in use into the ground, the sheet pile including a plurality of substantially flat sheet pile portions and a plurality of fold regions, each fold region being disposed at a junction between adjacent substantially flat sheet pile portions and having a substantially rounded cross sectional profile, the sheet pile having a transverse cross section of substantially corrugated configuration including a central trough of substantially flat configuration and first and second crests of substantially flat configuration adjacent the central trough, transverse dimensions of the central trough and the first and second crests being selected such that optimum strength is obtained.

In accordance with a second aspect of the present invention, there is provided a sheet pile for supporting sub-surface material when the sheet pile has been driven in use into the ground, the sheet pile including a plurality of substantially flat sheet pile portions and a plurality of fold regions, each fold region being disposed at a junction between adjacent substantially flat sheet pile portions and having a substantially rounded cross sectional profile, the sheet pile having a transverse cross section of substantially corrugated configuration including a central trough of substantially flat configuration and first and second crests of substantially flat configuration adjacent the central trough, transverse dimensions of the central trough and the first and second crests being sufficiently small so as to avoid buckling of the sheet pile at the respective crest or trough during use and being sufficiently large so that strength advantages of substantially flat crests and troughs are obtained.

Preferably, the sheet pile includes a single fold region between each transverse side of

the sheet pile and an adjacent substantially flat sheet pile portion extending between a crest and a trough.

In one embodiment, two crests and three troughs are provided. In an alternative embodiment, three crests and four troughs are provided.

Preferably, the transverse dimension of the central trough is substantially equal to the transverse dimension of each of the first and second crests.

In accordance with a third aspect of the present invention, there is provided a method of forming a sheet pile for supporting sub-surface material when the sheet pile has been driven in use into the ground, said method including the steps of : forming a sheet of material so as to define a sheet pile having a transverse cross section of substantially corrugated configuration including a plurality of substantially flat sheet pile portions and a fold region at each junction between adjacent substantially flat sheet pile portions, each fold region having a substantially rounded cross sectional profile, the sheet pile including a central trough of substantially flat configuration and first and second crests of substantially flat configuration adjacent the central trough ; and selecting transverse dimensions of the central trough and the first and second crests such that optimum strength is obtained.

Preferably, the step of forming the sheet of material includes the sub-step of forming the sheet of material so as to define a single fold region between each transverse side of the sheet pile and an adjacent substantially flat sheet pile portion.

Preferably, the step of forming the sheet of material includes the sub-step of forming the sheet of material so that the transverse dimension of the central trough is substantially equal to the transverse dimension of each of the first and second crests.

Preferably, the method further includes the step of selecting a depth dimension of the sheet pile such that the depth is sufficiently small to avoid buckling during use but not so small that strength advantages of a corrugated configuration cross section are

negated.

BRIEF DESCRIPTION OF THE DRAWINGS The present invention will now be described, by way of example only, with reference to the accompanying drawings, in which: Figures la and lb are diagrammatic perspective and end views respectively of a first prior art sheet pile; Figures 2a and 2b are diagrammatic perspective and end views respectively of a second prior art sheet pile, the second prior art sheet pile being associated with and connectable to the first prior art sheet pile shown in Figures la and lb ; Figures 3a and 3b are diagrammatic perspective and end views respectively of a first sheet pile in accordance with the present invention; Figures 4a and 4b are diagrammatic perspective and end views respectively of a second sheet pile in accordance with an embodiment of the present invention, the second sheet pile being associated with and connectable to the first sheet pile shown in Figures 3a and 3b ; Figures 5 to 12 are diagrammatic perspective and end views of associated first and second sheet piles of alternative embodiments of the present invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS Referring to Figures 1 and 2 of the drawings, there is shown first and second prior art sheet piles 10 and 12. The prior art sheet piles 10,12 are of generally corrugated transverse cross-section and are formed by folding along fold lines 26 to produce elongate edges. By providing corrugated piles, the likelihood of buckling of the piles in use is reduced. In addition, a corrugated profile facilitates the use of two sets of clamping jaws during a pile driving operation.

An embodiment of first and second sheet piles 28,30 in accordance with the present invention is shown in Figures 3 and 4.

The first and second sheet piles 28,30 include first flat portions 14 generally disposed in a first plane and second flat portions 16 generally disposed in a second plane parallel to the first plane. The first and second flat portions 14,16 are interconnected by further flat portions hereinafter referred to as first and second intermediate portions 18,20, each of which defines an obtuse angle with an adjacent first flat portion 14 and an adjacent second flat portion 16. Elongate sides of the first sheet pile 28 are provided with first and second end portions 22,24. Elongate sides of the second sheet pile 30 are provided with first end portions 22. In this embodiment, the first and second flat portions 14,16 are approximately equal in width.

The first sheet pile 28 also includes connection means, hereinafter referred to as a clutch 27, for facilitating connection of the first sheet pile 28 to the second sheet pile 30. In order to connect the first and second sheet piles 28,30 together, a first end portion 22 of the second sheet pile 30 is inserted between the clutch 27 and an adjacent second intermediate portion 20 of the first sheet pile 28.

The first and second sheet piles 28,30 are also provided with end fold regions 32 of generally rounded cross-sectional profile and intermediate fold regions 34 also of generally rounded cross-sectional profile.

The width of each of the first and second flat portions 14,16 is selected so that for the sheet pile material used the width is sufficiently small to avoid buckling of the respective first or second flat portion 14,16 during use but not so small that strength advantages of the respective first or second flat portion 14,16 are negated.

The depth of the sheet pile, that is, the distance between adjacent flat portions 14,16 is also selected so that for the sheet pile material used the depth is sufficiently small to avoid buckling of the first and second intermediate portions 18,20 during use, but not

so small that strength advantages of the corrugated profile shape are negated.

For a 3 mm thickness sheet pile, the width of the central trough is within the range 100 mm to 200 mm, the width of the crests is in the range of 100 mm to 200 mm, and the depth is in the range 140 mm to 190 mm. However, in the presently described embodiments, the width of the central trough is approximately 150 mm for all embodiments. This is so that all embodiments are receivable in the same contoured jaw of a pile driving apparatus.

It will be understood that by providing a rounded profile at intersections between portions 14,16, 18,20, 22,24 of a sheet pile 28,30 instead of an edge, additional rigidity and strength is imparted to the sheet piles 28,30 and the likelihood of weakening and/or tearing of the sheet pile at the intersections is reduced relative to the prior art sheet piles.

In addition, it will be understood that since transverse sides of the first and second sheet piles 28,30 are provided with a single end fold region 32 between the relevant first or second end portion 22,24 and adjacent first or second intermediate portion 18,20, the efficacy of the connection in use between the first and second sheet piles 28,30 is increased relative to the connection between the first and second prior art sheet piles 10, 12.

It will also be understood that by providing a single fold region between the relevant first or second end portion 22,24 and adjacent first or second intermediate portion 18, 20, less folding operations are required in order to form the sheet piles 28,30 shown in Figures 3 and 4 than are required to form the prior art sheet piles 10,12. This is because the prior art sheet piles have two fold lines present between the relevant first or second end portion 23,24 and adjacent first or second intermediate portion 18,20 instead of one. This reduction in the required fold operations translates to a reduction in production cost of approximately 20%.

Alternative embodiments of first and second sheet piles are shown at 36 and 38 in

Figures 5 and 6, at 40 and 42 in Figures 7 and 8, at 44 and 46 in Figures 9, and at 48 and 50 in Figures 11 and 12.

It will be understood that Figures 5 to 8 illustrate alternative embodiments of sheet piles in accordance with the present invention, each of the sheet piles shown in these Figures having features which correspond to the features shown in Figures 3 and 4, but the transverse cross-sectional profiles of these sheet piles being different to the transverse cross-sectional profile of the sheet pile shown in Figures 3 and 4. Figures 9 to 12 show further alternative embodiments of sheet piles in accordance with the present invention, each of the sheet piles in these Figures having substantially rounded fold regions, but the clutch 27 in these embodiments being disposed at a greater distance from the adjacent second end portion 24 than is the case with the embodiments shown in Figures 3 to 8.

Modifications and variations as would be apparent to a skilled addressee are deemed to be within the scope of the present invention.