GB2314575A - Sheet piling - Google Patents

Abstract

Interlocking sheet piling (60, 62) is made of extruded hollow section reinforced structural plastics, and is anchored in position, after being lightly driven into place, by anchor pins (64) extending through passages in the individual piles and deep driven into the waterway bed, and ground anchors (66) locked in open channels (87) on the rear faces of some of the piles, retained by infill (104). The installed piling is covered by capping (68).

Description

SHEET PILING This invention relates to sheet piling, including piling for use in waterside locations, such as the banks of rivers, canals and lakes.

Sheet piling forms a continuous sheet or barrier to resist lateral pressure and may be used as a retaining wall or as a waterway bank. It can be contrasted with the use of foundation piles or mooring piles individually or in groups without forming a continuous barrier. The individual piles that go to make up a continuous run of sheet piling are referred to herein as sheet piles.

Sheet piling, consisting of a line of interlocked sheet piles, is generally installed by driving successive piles into the underlying ground. The piles need to be strong, to take the driving forces, yet thin, to cut into the ground. The usual material is steel, which may be galvanised for corrosion resistance. The piles are consequently heavy, and require heavy machinery to install them. Their appearance may be unsightly, and zinc may leach into the surrounding soil and water.

In order to provide a satisfactory sheet pile that can be made of a variety of materials, including alternatives to galvanised steel, conventional designs need to be changed.

Further, riparian sheet piling may be held upright against the pressure of bankside infill by means of tie bars to secondary anchor piles set back into the bank by about 2 or 2% metres.

If this area is built up or paved, the installation of the anchors and subsequent making good of the disturbed ground can be an expensive operation. It would be useful to avoid the associated additional labour, machinery and materials costs.

The present invention concerns aspects of the sheet piling described below. The scope of the invention extends to all novel aspects of the piling whether individually or in combination with any of the other features disclosed herein.

According to the invention, a sheet pile comprises some or all of the elements and features disclosed in the following description.

More specifically, in one aspect of the invention a sheet pile may comprise a through passage and an anchor pin extending therethrough, the anchor pin being moveable along the passage to an extent that it can be driven into an underlying ground base on which the piling may stand. The passage suitably extends substantially the whole length of the pile. It is normally straight, although curvature is possible.

To enable adjacent piles to interlock, the piles can be provided at or adjacent their side edges with complementary, longitudinally slideable, engagement means, as are well known in the art of sheet piling. If these are categorised, for convenience, as respectively male and female, a pile can have one male and one female edge, or alternate piles can have two male and then two female edges, or in some instances more than two edges may be present, where runs of sheet piling intersect.

In a more specific aspect of the invention, interlocking sheet piling may comprise a plurality of sheet piles interlocking through complementary, longitudinally slideable, engagement means, wherein the piling includes longitudinal through passages and anchor pins extending therethrough into an underlying ground base.

A method of installing such a sheet pile may comprise locating a lower edge of the pile over a ground base, such as soil or subsoil or the bed of a waterway, and driving the anchor pin through the said passage into the ground base. The lower edge will usually be driven into the ground base as well, to assist in locating and supporting the pile and to seal between the front and rear faces of the pile, but the depth of penetration may be less than would be required for a pile that was entirely reliant on ground penetration for its support.

Accordingly, the piles may be made of materials of lower strength than the steel normally used for sheet piling. This allows weight reduction, and corresponding cost savings with regard to the machinery and labour needed to place the piles in position. Plastics materials in particular, optionally reinforced with fibres such as glass or carbon, may be used.

Careful selection of appropriate materials allows the possibility of numerous other advantages, such as corrosion resistance, self colour, manufacture by extrusion processes, and the use of hollow sections.

Hollow section sheet piles may be formed with front and rear faces, which will form the front and rear faces of the sheet piling, the faces being separated by one or more webs, between which are voids. The webs and voids may extend longitudinally of the pile, in effect vertically when considered in terms of the installed pile. A void may be used as the passage for the anchor pin. Webs at the two opposite sides of the pile, extending between the front and rear faces, would then form the side edges of the pile, and may carry the engagement means.

Internal webs may also be formed, typically perpendicular or parallel to the front and rear faces.

Although such a hollow section pile is thicker than most conventional sheet piling, it can be successfully driven a sealing distance into the ground base, because the lower end of the pile still consists only of a plurality of relatively thin face and web members around the void or voids, which members can cut relatively freely into the ground.

Since sheet piling is, in effect, a continuous wall, the individual sheet piles making it up are not limited to any particular width (distance between opposite side edges). A plurality of narrow piles may be used to form small radius bends, wide piles may be used on straight runs, and narrow and wide piles may usefully be alternated, with the narrow piles accommodating the anchor pins.

The anchor pins may also be of a variety of shapes and materials. Apart from plain round sections, the pins may be finned to increase their surface and hence their grip in the ground base. They may also be shaped to fit a drift, to enable a pin to be driven cleanly into the passage without damaging the passage top; for this purpose, a tubular pin is convenient, allowing a drift with a centre spike to be used to sink the pin into the passage in the pile.

In another aspect of the invention, a sheet pile may comprise a longitudinal channel open to a face of the pile, said channel retaining a ground anchor extending outwardly away from the pile. The ground anchor may be slideable along the channel.

In preferred embodiments, the anchor is freely slideable when dropped into the channel and the latter is substantially vertical, but is provided with means whereby it can be locked at a selected location in the channel. Locking may be achieved by changing the orientation of the anchor in the channel, and/or by applying pressure to the ground anchor. Locking may also be achieved by clamping the anchor at a desired location in the channel, for example by means of a clamping screw.

A preferred ground anchor may comprise a first arm engaged with the channel, a second arm extending outwardly away from the pile, and an anchor plate deployed on the second arm.

The channel may be formed from inturned flanges along one face of the pile. Such flanges may also serve to reinforce the pile.

The invention also extends to a method of lining a waterway bank with sheet piling, and a waterway with banks so lined.

The invention is illustrated by way of example in the accompanying drawings, in which: Figure 1 is a perspective view showing the top end of one sheet pile and part of an adjacent identical interlocking pile in a first embodiment of the invention; Figure 2 is a plan view corresponding to Figure 1; Figure 3 is a partial plan view of the central section of the pile, showing an anchor channel and a ground anchor tie in it; Figure 4 is a perspective view, partially transparent, of the arrangement shown in Figure 3; Figure 5 is an illustrative view of the pile in position at a waterway bank, the pile being shown as a section on A-A of Figure 3; Figure 6 is a perspective view showing a second embodiment of the invention, with a wide sheet pile engaged between two narrow sheet piles, all of extruded hollow sections; Figure 7 is a plan view of the wide pile; Figure 8 is a plan view of a narrow pile with an anchor pin; and Figure 9 is a side elevation of the ground anchor shown in Figure 6.

Figures 1 to 5 illustrate a first embodiment of the invention.

Although the drawings show variations in the dimensions of the anchor channel, each pile is essentially the same.

Each sheet pile 10 comprises a web 12 with parallel interlocking longitudinal side edges 14, 15 formed respectively of complementary, longitudinally slideable, male and female engagement means, and has a top edge 17 and a bottom edge 18 between them.

The female edge 15 is of part circular section, open over a short arc. The male edge 14 is a complete circle (although it could be less than complete) dimensioned to fit and slide and turn within the female edge, but not to pull out sideways.

The piles are made of glass fibre reinforced structural plastics material. They are desirably extruded, optionally under tension ("pultrusion"). Consequently they are of uniform cross section as produced, but the top and bottom edges in particular may be modified after the extruded lengths are cut into individual sheet piles.

Anchor pin 30 extends through the centre of the linked pile edges and is driven into the waterway bed 32. Pin 30 may be a cut length of plain steel bar, reinforcing bar, or galvanised steel tube, for example. The lower edges 18 of the piles are also driven into the bed 32, but a relatively short way, sufficient to effect a secure join and seal. The installation of the piling is similar to the installation of conventional interlocking steel sheet piling, except that the driving is in two parts, namely shallow driving of the piles and deep driving of the pins.

The sheet driven depth may be about 300mm, as opposed to say 1000mm for conventional steel sheets. The anchor pins 30 on the other hand may be driven to a much greater depth, 1000mm or more, into the ground base, ie into the waterway bed.

The rear or bankside face 20 of the web has a channel 22 formed thereon between two inturned flanges 24. The channel is open, by virtue of slot 26 between the facing inturned edges of the flanges.

A ground anchor tie 40 consists of a head portion 44 in the form of a plate connected to a body portion 46 by an arm or neck 42. The neck extends through slot 26 so that the head is inside the channel 22 and the body is outside the channel.

Nibs 48 on the head and optionally the body are so positioned and dimensioned that the anchor can slide freely along the channel in a particular orientation, but changing the orientation, even marginally, causes the nibs to bear against the channel sides (the flanges 24 and the included part of the web 20) to lock the anchor tie in the channel.

The anchor tie may be metallic, to give it weight and strength.

A suitable material is ductile cast iron, which corrodes only slowly when buried in low oxygen conditions, and can be manufactured with strengthening ribs.

After the installation of the interlocked sheet piling, ground anchor ties 40 can be dropped, tilted so as to freely slide, into the channels 22 of each pile or of selected piles. The rear, bankside faces of the piles are then infilled with dredgings or other material, optionally including concrete 50, which apply pressure to the ground anchor ties to turn and lock them in their channels. Thereafter the ties serve to hold the piling upright against pressure from the banks.

The flanges 24 brace the plastic webs of the piles. If the pile widths are increased from say 300mm to 500mm, further strengthening ribs or webs may be required. The piles may also be made of double skin sections, such as rectangular hollow sections, with cross bracing webs. It can be seen that the use of mouldable or extrudable materials permits a much wider variety of pile sections than are available for rolled steel piles, and the use of anchor pins allows less robust sheet materials to be used. Plastics in particular can be self coloured, either for environmental acceptance, or for colour coding moorings, service points and the like.

The second embodiment of the invention shown in Figures 6 to 9 illustrates the use of a rectangular hollow section system of piling referred to above, made up of two alternating extruded reinforced plastics sheet pile sections, with internal webs and voids.

The sheet piling consists of narrow piles 60, which are in fact narrower than their depth between front and rear faces, and wide piles 62. Both types of pile have internal voids between strengthening webs, as will be described, but the more compact design of the narrow piles, with smaller voids, gives them particular strength, and they are reinforced by anchor pins 64 passing through their central voids, which makes it appropriate to use these piles for mounting ground anchors 66. After installation, the top edges of the piles, with their open voids, are covered by plastics capping 68.

As shown in Figures 6 and 7, the wide sheet piles 62 consist of opposed front and rear skins 72, 73, forming the two exposed faces of the pile in the assembled piling, joined by webs 74, to form a plurality of substantially rectangular, almost square section voids 75 between them. The webs on the opposite side edges are formed with undercut channels 77 to form the female components of longitudinally slideable engagement means. Face 73 is formed with clearly radiused side edge corners 79, which allows greater tolerance in the alignment of adjacent piles, so that corners can be more readily negotiated. Since the wide piles are otherwise symmetrical, they can be installed with either of the faces 72, 73 acting as the front or rear face as desired.

The narrow piles 60 shown in section in Figure 8 have a continuous front face 82, and a rear face 83 formed by the inturned ends of side webs 84, thus forming an open channel 87 between the said rear face 83 and the rearmost of two strengthening webs 86 which join the side edges 84 internally of the pile, parallel to the front and rear faces.

Male engagement means 89, adapted to be slideably received within undercut channels 77 to connect adjacent piles 60 and 62 while allowing relative longitudinal movement between them, are formed midway along opposite side edges 84, and the central rectangular void 88 formed between the opposite side edges 84 and the two internal webs 86 accommodates tubular galvanised steel anchor pin 64. Void 88 accordingly forms a longitudinal through passage for the anchor pin, which, being substantially longer than the pile, can be driven into the underlying ground base on which the pile rests, in a similar manner to that described in relation to the first embodiment of the invention.

The channel 87 accommodates the square head 92 of a screw threaded bolt, such that the bolt can slide down the channel but the head is prevented from turning. A nut 94 on the bolt outside the channel enables a bar 96, through which the bolt passes, to be clamped by the bolt to the pile 60.

Bar 96 forms a first arm of the ground anchor 66, as shown in Figure 9. The lower end of arm 96 is joined by an approximately right angled bend to a second arm 98, extending outwardly away from the pile, to which is welded a flat anchor plate 100. To prevent arm 98 bending under stress, a tie bar 102 connects the furthest ends of the two arms. The ground anchor 66 is suitably made of galvanised mild steel.

After installing the sheet piling, by lightly driving alternating piles 60, 62 in interlocking relationship on to and sealingly in to a waterway bed, and deeply driving anchor pins 64 into the bed through passages 88 in the narrow piles, all necessary ground anchors can be slid into position on the rear or bankside face of the piling, by inserting the square head 92 of the lower clamping bolt on the first arm into the top end of the channel 87, followed by the square head 92 of the upper clamping bolt as the ground anchor 66 is lowered into position.

Usually, it is only necessary to tighten the nut 94 on the uppermost bolt to secure the upper arm 96 against the rear face 83 of the narrow pile. The anchor can then be covered with infill 104 (Figure 6) to fix the piling firmly in place.

Finally, capping 68 provides a neat and weatherproof finish.

As compared with the previous practice of providing secondary anchor piles a good two metres back from the sheet piling, satisfactory anchorage can be achieved in this way with a second arm 96 only some 30cm or so long, so that the ground behind the piling need not be disturbed for more than about half a metre.

Claims (22)

1 A sheet pile comprising a longitudinal through passage and an anchor pin extending therethrough, the anchor pin being moveable along the passage to an extent that it can be driven into an underlying ground base on which the pile may stand.

2 A sheet pile according to claim 1 wherein the sheet pile is provided at or adjacent a side edge with engagement means, adapted to be slideably engageable with complementary engagement means that may be carried at or adjacent a side edge of an adjacent pile.

3 A sheet pile according to claim 2 wherein the complementary engagement means are respectively male and female, wherein the male is receivable within the female by sliding longitudinally relative thereto.

4 A sheet pile according to any one of the preceding claims comprising spaced apart front and rear faces separated by at least one internal void.

5 A sheet pile according to claim 4 comprising a plurality of said voids separated by webs.

6 A sheet pile according to claim 4 or claim 5 wherein the longitudinal through passage through which the anchor pin extends is a said void.

7 A sheet pile according to any one of claims 1 to 6 wherein the anchor pin is tubular.

8 Interlocking sheet piling comprising a plurality of sheet piles interlocking through complementary, longitudinally slideable, engagement means, wherein the piling includes longitudinal through passages and anchor pins extending therethrough into an underlying ground base.

9 Interlocking sheet piling according to claim 8 wherein said plurality of sheet piles comprise at least one sheet pile according to any one of claims 2 to 6.

10 A method of lining a waterway bank with sheet piling, comprising placing a continuous wall of sheet piles as claimed in any one of claims 1 to 6 upright in interlocking relationship on the bed of the waterway along the said bank, and driving an anchor pin through the longitudinal through passage of at least one said sheet pile into the underlying ground base on which the pile stands.

11 A waterway having a bank lined by a method according to claim 10.

12 A sheet pile comprising a longitudinal channel open to a face of the pile, said channel retaining a ground anchor extending outwardly away from the pile.

13 A sheet pile according to any one of claims 1 to 6 comprising a longitudinal channel open to a face of the pile, said channel retaining a ground anchor extending outwardly away from the pile.

14 A sheet pile according to claim 12 or claim 13, wherein the ground anchor is slideable along the channel.

15 A sheet pile according to claim 14, wherein the anchor is freely slideable when dropped into the channel and the channel is substantially vertical, and is provided with locking means whereby it can be locked at a selected location in the channel.

16 A sheet pile according to claim 15, wherein said locking means comprises a clamping screw.

17 A sheet pile according to any one of claims 12 to 16 wherein the ground anchor comprises an anchor plate deployed on an arm extending outwardly away from the pile.

18 A sheet pile according to any one of claims 1 to 6 or 12 to 17 manufactured by extrusion of reinforced plastics.

19 A method according to claim 10 wherein the sheet pile is in accordance with any one of claims 12 to 17, including the step of inserting the ground anchor into the channel after the installation of the interlocked sheet piling, locking the ground anchor in the channel, and infilling between the bank and the piles over the ground anchor.

20 A sheet pile substantially as hereinbefore described with reference to and as illustrated in any of the accompanying drawings.

21 Interlocking sheet piling substantially as hereinbefore described with reference to and as illustrated in any of the accompanying drawings.

22 A method of lining a waterway bank with sheet piling substantially as hereinbefore described with reference to and as illustrated in any of the accompanying drawings.