EP3645795A1

EP3645795A1 - Top-to-bottom construction system

Info

Publication number: EP3645795A1
Application number: EP18822765.6A
Authority: EP
Inventors: John Jarvie; Gregory Paul Mullane
Original assignee: Armour Wall Group Pty Ltd
Current assignee: Armour Wall Group Pty Ltd
Priority date: 2017-06-26
Filing date: 2018-06-26
Publication date: 2020-05-06
Also published as: WO2019000031A1; CN110869563A; US20200149240A1; AU2018293555A1; NZ759839A; EP3645795A4

Abstract

Disclosed is a nesting element for use in a hollow pile. The nesting element is configured to be retained at an opening defined in a wall of the pile. The nesting element comprises a surface that is configured such that, in use, the surface substantially conforms to an internal profile at a transverse cross-section of the pile. Also disclosed are a pile system that employs one or more nesting elements in one or more respective piles, and an installation system for installing the pile system into the ground. Additionally, a method of constructing a retaining wall using the pile system and installation system is disclosed.

Description

TOP-TO-BOTTOM CONSTRUCTION SYSTEM

TECHNICAL FIELD

The following disclosure relates to a construction methodology that employs a series of piles such as sheet piles used for retaining walls.

BACKGROUND ART

Underground basements, car parks, cellars, etc. are usually built from the bottom up. The site is first excavated, prior to driving into the ground and supporting thereat interlocking panels that form a continuous barrier/retaining wall at the perimeter of the site. The resultant continuous barrier/retaining wall enables permanent works to proceed within the excavated space. In practice, a plurality of elongated, vertically oriented, optionally interlocking panels are driven into the earth to a depth sufficient to support the panels in an upright attitude, although typically some bracing, anchoring or tieback at the panel upper ends is required.

The panels may take the form of extruded structural panels that are provided with male and female opposed edges so that similar panels can be locked together at their adjacent side edges to form a continuous barrier/retaining wall.

It is to be understood that, if any prior art is referred to herein, such reference does not constitute an admission that the prior art forms a part of the common general knowledge in the art, in Australia or any other country.

SUMMARY

Disclosed herein is a nesting element for use in a hollow pile. The nesting element is configured to be retained at an opening defined in a wall of the pile.

The nesting element comprises a surface that is configured such that, in use, the surface substantially conforms to an internal profile at a transverse cross-section of the pile. For example, the opening may be defined in a side wall of the pile and the nesting element may be inserted into the pile (e.g. via the side wall opening or slid through from an open end of the pile hollow cross-section) to locate and be retained adjacent to the opening (e.g. with the surface at an in-use location that is at or just above the side wall opening).

Such a nesting element can allow a hollow pile to be employed in a top-to- bottom construction methodology, as will be described hereafter.

When it is stated that the surface "substantially conforms to an internal profile at a transverse cross-section of the pile" it should be understood that this does not imply that the surface abuts or contacts an internal surface of the pile. In this regard, the surface of the nesting element may be spaced from the pile internal surface but be sufficiently close so as not to allow cementitious material (e.g. concrete) that is poured into the pile from above the nesting element to pass through to a lower section of the pile.

In one embodiment the nesting element may comprise a flange. The nesting element surface may extend generally orthogonally from the flange. The flange may be configured to be arranged against an interior or exterior surface of the hollow pile to be retained thereat in use. The flange may thus help to support the surface in the pile. In some embodiments, the flange may be riveted to the interior or exterior surface of the pile adjacent the opening. For example, the flange may be affixed to the interior or exterior surface of the hollow pile, such that weight of cementitious material on the surface is resisted and borne by the flange. A means other than a flange may be employed to retain the surface at the pile wall opening. For example, the nesting element may be configured to be affixed, such as by one or more fasteners, adhesive, etc.

In one embodiment the nesting element may further comprise at least one side wall that extends from the surface in a direction opposite to the flange. The at least one side wall may be configured to locate adjacent to an interior surface of the hollow pile in use. The at least one side wall can increase the structural rigidity of the nesting element such that it is better able to support the

cementitious material that impinges and weighs upon the surface when poured into the pile from above the nesting element.

In one embodiment the nesting element may be configured to support one or more reinforcing bars that, in-use, extend vertically through the pile. For example, the surface may be provided with one or more holes therethrough, each sized for a respective one of the one or more reinforcing bars. The nesting element may thus support the rods at the surface, and may maintain a spacing between adjacent rods (i.e. as cementitious material flows into the pile). Where the pile has multiple nesting elements, these may work together to support the rods and maintain a spacing between adjacent rods along the length of the pile.

The nesting element as disclosed herein may be used with a hollow pile that takes the form of a sheet pile. The sheet pile may have a rectangular box section that extends for a length of the sheet pile. Accordingly, the nesting element may be correspondingly dimensioned to nest in the rectangular box section (i.e. that is shaped to closely face the interior surfaces of the box section). Forming the nesting element as a prism can provide it with a high degree of structural integrity. Such a shape is also easy to mass produce. In some embodiments, the sheet pile and corresponding nesting element may have a substantially square cross-section.

In one embodiment, the surface of the nesting element that blocks or restricts the flow of cementitious material through the hollow pile may define an in-use upper surface of the nesting element. The nesting element may further comprise two opposing side walls that each extend downwardly in use from respective opposing side edges of the upper surface. The nesting element may additionally comprise a rear wall that extends downwardly in use from a rear edge of the upper surface. Each of the side walls and rear wall may closely face or abut a corresponding surface of the box section of the hollow pile, to better support the nesting element within the box section.

In one embodiment the nesting element may be open at at least two sides or "faces" thereof. These two "faces" may be adjacent to one another. A first of the two open faces may be arranged to open outwardly of the sheet pile at the wall opening in use. A second of the two open faces may be arranged to face arranged to open downwardly in the sheet pile in use. The first open face can allow cementitious material to flow into the hollow pile, whereas the second open face can allow cementitious material to flow down into the hollow pile. The flow of cementitious material into the hollow pile may occur, for example, when an adjacent floor slab is being poured at the construction site. In this way, the floor slab can become "keyed" to the retaining wall.

In one embodiment of the nesting element, the nesting element may be supported in use at the sheet pile side wall opening by a flange that surrounds a perimeter of the second open face. The flange may extend generally orthogonally out from each of the upper surface and side walls.

Also disclosed herein is a pile system. The pile system comprises a hollow pile that has at least one opening defined in a wall of the pile. The pile system also comprises a nesting element that is as defined above. The nesting element can be configured such that it is able to be inserted into the pile via the opening or through the hollow cross-section and retained adjacent to the at least one opening of the hollow pile.

The pile system can allow each such hollow pile to be employed in a top- to-bottom construction methodology, as will be described hereafter. For example, the pile system can be used to construct a retaining wall to be located at a perimeter of a construction site such as an underground basement, car park, cellar, etc. In this regard, the pile system may comprise a plurality of hollow piles and associated nesting elements, which may be pre-assembled (e.g. prior to being brought to site).

In one embodiment the hollow pile may have a plurality of openings defined in and spaced out along the side wall of the pile. Each opening may be located to correspond to an adjacent floor level in use of the pile (e.g. each opening may correspond to an adjacent floor slab of e.g. the underground construction). A nesting element may be provided for each pile side wall opening.

In one embodiment the hollow pile may comprise a sheet pile having a rectangular box section extending for its length. In this embodiment the nesting element may be correspondingly dimensioned to nest in the rectangular box section (e.g. having the features as set forth above).

In one embodiment the system may comprise a plurality of hollow piles. In one embodiment, each of the hollow piles may be configured to be connected to each other along their length. In such an embodiment, when the hollow piles are connected together, they may thereby form a substantially self- supporting wall.

In one embodiment, each of the hollow piles may comprise at least one male clutch and at least one corresponding female clutch. The male clutch can project from a side wall of the hollow pile to extend longitudinally along the length of the side wall. The female clutch can be formed at a side wall of the hollow pile to extend longitudinally along the length of the side wall. The male and female clutches may be aligned on adjacent piles so as to form a substantially smooth face along the wall when the hollow piles are connected together in-use via their clutches.

In one embodiment, the male clutch may be formed to project from an intermediate location along the side wall or along a distal end of the side wall. A female clutch can be respectively formed within the side wall at an intermediate location along the side wall or along a distal end of the side wall.

In one embodiment, a rebate may be provided within and along the length of the or each female clutch such that, in use, a sealing bead may be inserted into the rebate in use.

In one embodiment, when the hollow piles have been connected together to form the wall, the system may be configured to have a cementitious material poured into the connected piles at an open upper end of each of the hollow piles.

In one embodiment, prior to pouring the cementitious material into the open upper end of each of the hollow piles, the system may be configured to receive reinforcing vertically through each of the hollow piles.

In an alternative embodiment the system may further comprise a plurality of king piles. Each king pile may take the form of a cylindrical (e.g. tube) pile. In use, each hollow pile may have a king pile arranged along either side thereof. Thus, for example, a retaining wall may be constructed that has alternating hollow (e.g. sheet) piles and king piles. In the alternative embodiment each of the hollow piles and king piles may be configured along respective sides thereof to be connected to each other along their length. For example, when the hollow and king piles are connected together, they may form a substantially self-supporting wall. The sheet and king piles may be as set forth in WO 2017/063021, the relevant contents of which are incorporated herein by reference.

In the alternative embodiment, when the hollow and king piles have been connected together to form the wall, the system may have a cementitious material (e.g. concrete) poured into the piles at an open upper end of each of the hollow and king piles. Thus, the system can also act as formwork for the cementitious material when e.g. forming the retaining wall.

In the alternative embodiment, prior to pouring the cementitious material into the open upper end of each of the hollow and king piles, reinforcing (e.g. one or more reinforcing bars) may be arranged vertically in each of the hollow and king piles. The reinforcing bars may extend longitudinally through each pile. The reinforced piles may be pre-assembled (e.g. prior to being brought to site).

Also disclosed herein is an installation system for installing the pile system disclosed above into the ground. The installation system comprises a first mandrel with an elongate tubular internal profile that is correspondingly dimensioned to an external profile of the hollow pile. The first mandrel can be formed (e.g. of a thick and/or toughened steel, etc.) to be pile-driven into the ground, rather than driving the hollow pile into the ground.

In one embodiment, the installation system may further comprise a second mandrel. The second mandrel can also be formed to be pile-driven into the ground, rather than driving a further hollow pile into the ground.

The second mandrel may have an elongate channel with opposing elongate side walls that are connected to one another by a rear wall. Each opposing elongate side wall may be configured to connect with a side wall of an adjacent first mandrel or a rear or side wall of an adjacent and further second mandrel. The connection between mandrels may be configured such that, in use, when the first mandrel has been driven into the ground, the first mandrel is able to guide the second mandrel whilst it is driven into the ground. Thus, the first and second mandrels can be configured to work together.

In one embodiment, each side wall of the second mandrel may comprise a female clutch that, in use, may be configured to engage a corresponding and respective male clutch (or clutches) that project from one of:

opposing sides of an adjacent first mandrel;

opposing side walls of an adjacent second mandrel; the same side wall of an adjacent second mandrel.

This may prevent twisting or distortion of the channel shaped second mandrels as they are driven by a pile-driving apparatus.

In one embodiment, each of the first and second mandrels may comprise a flange that projects substantially perpendicularly away from a side wall thereof. The flange may be configured to facilitate gripping of the mandrel by a pile driving mechanism. The flange may also act as a spine to prevent deflection and buckling of the mandrels in use during pile-driving.

In some embodiments, the installation system may be reusable. Typically all components thereof may be fabricated from strong, tough materials (e.g. treated metals such as toughened/strengthened steel, etc.).

Also disclosed herein is a drive system. The drive system may be used for driving into the ground a pile system as set forth above. The drive system may comprise a mandrel that is configured for location with respect to an open in-use upper end of the hollow pile. The mandrel may be operated at height from e.g. a crane or other like vehicle on a construction site and may thus act as a pile driver.

The mandrel may comprise a head that is configured so as to act on the hollow pile upper end to cause an in-use lower end of the hollow pile to be driven into the ground. The head may be dimensioned to effectively close the open upper end during pile driving.

In one embodiment the hollow pile may be of a type that comprises a hollow section having two sets of flanges that extend out from opposite sides of the hollow section. When the hollow pile is so configured, the mandrel may be configured to comprise two spaced elongate pin members that each extend from the mandrel head to locate and extend between a respective one of the sets of flanges. In this way, the mandrel can be suited to better engage with the hollow pile during pile driving. After pile driving, the mandrel can be withdrawn from the hollow pile.

In one embodiment each pin member may be configured to extend beyond the hollow pile lower end in use. Each pin member may further comprise a pointed end to facilitate its insertion into the ground.

In one embodiment the hollow pile may be of a type that comprises a hollow section in the form of a box section. The box section may have opposing side walls. One of the sets of flanges may extend in a first direction as a continuation of the box section side walls. The other of the sets of flanges may extend in a second opposite direction as a continuation of the box section side walls. The hollow pile may, in this regard, be take the form of sheet pile, and may be as set forth in WO 2017/063021, the relevant contents of which are incorporated herein by reference. The mandrel can be shaped accordingly to suit such a hollow pile.

In one embodiment the drive system may further comprise at least one attachment for location at an in-use open lower end of the hollow pile. The attachment may be force-fit into the pile lower end, to be secured thereto during pile driving. The attachment may remain in place after pile driving. The attachment may be configured to prevent ground matter from entering the hollow pile during driving of the hollow pile lower end into the ground. For example, the attachment may protrude to a pointed end to facilitate its insertion into the ground.

In one embodiment the drive system may further comprise at least one detachable cover for each nesting element when the latter is located at the hollow pile side wall opening. The cover may be releasably secured to the nesting element at the side wall opening (i.e. for subsequent removal during a

construction phase - i.e. to allow for the inflow of cementitious material into the pile). The cover may be configured to prevent ground matter from entering the hollow pile during driving of the pile into the ground.

Also disclosed herein is a method of constructing a retaining wall.

In one embodiment, the method comprises driving into ground a first mandrel as described above, then removing ground from within an interior of the first mandrel.

In one embodiment the method may further comprise driving into the ground a second mandrel as defined above, such that the side walls of the second mandrel connect with the first mandrel to be guided thereby. Ground from within an interior of the second mandrel may then be removed.

In one embodiment, the method may further comprise driving into the ground a further second mandrel, such that the side walls of the second mandrel may connect with the second mandrel existing in the ground to be guided thereby. Ground from within an interior of the further second mandrel may then be removed.

In one embodiment, the method may further comprise locating a hollow pile as defined above within the first mandrel.

In one embodiment, the method may further comprise removing the first mandrel from the ground. A hollow pile as defined above may then be located within the second mandrel such that the hollow pile can connect to the adjacent hollow pile that was located within the first mandrel. The ground within the second mandrel may then be removed.

In one embodiment, the method may further comprise locating a hollow pile as defined above within a further second mandrel such that the hollow pile can connect to the adjacent hollow pile that was located within the second mandrel. Ground from within an interior of the further second mandrel may then be removed.

In one embodiment, the method may further comprise arranging one or more elongate reinforcing bars to extend vertically through and for a length of each hollow pile. For example, each elongate reinforcing bar may extend vertically through one or more nesting elements arranged in each hollow pile.

In one embodiment, the method may further comprise pouring a cementitious material into the hollow pile at an in-use open upper end thereof. The cementitious material may flow down inside the pile until it reaches a surface of an in-use uppermost nesting element located at a respective wall opening.

In an alternative embodiment, the method may further comprise driving a pile system into the ground. The pile system may comprise a hollow pile having at least one opening defined in a wall thereof. The pile can be as set forth above. The at least one wall opening can have a nesting element retained thereat. The nesting element can be as set forth above and can be inserted in the opening.

One mode of implementing the method is as a top-to-bottom construction methodology, as further described hereafter. The method can also allow for underground and above ground construction to take place simultaneously.

In one embodiment a plurality of hollow piles may be driven into the ground to form the retaining wall. The plurality of hollow piles may be interconnected so as to form the retaining wall.

For example, in the alternative embodiment each hollow pile may be interconnected to an adjacent hollow pile via an intermediate, optionally hollow, king pile. Each king pile may be driven into the ground so as to form part of the retaining wall. The hollow and king piles may be driven into the ground in sequence moving along a line of the retaining wall.

In the alternative embodiment each hollow pile and each king pile may be interconnected along respective adjacent longitudinal sides thereof. The manner of interconnection may be by way of complementary male and female clutches, such as those as set forth in WO 2017/063021, the relevant contents of which are incorporated herein by reference.

In the alternative embodiment each hollow pile and each king pile may have one or more elongate reinforcing bars arranged to extend vertically therein for a length of the pile. These may be pre-assembled in each pile (e.g. prior to being brought to site). In an embodiment the method may further comprise pouring a cementitious material into each hollow pile at the in-use open upper end thereof. The cementitious material can flow down inside the pile until it reaches a surface of an in-use uppermost nesting element located at a respective wall opening.

In the case of a king pile, the cementitious material can flow down to a base thereof. The king piles can support a remainder of the retaining wall, whereby top-to-bottom construction of the site can now commence.

In an embodiment of the method, the retaining wall may be constructed along a perimeter of a construction site (i.e. to surround the site).

In one mode of implementing the top-to-bottom construction method, a slab of cementitious material may be formed at the ground within the construction site perimeter (i.e. as defined by the retaining wall). Optionally, at this time, one or more slab support columns may first be formed into the ground spaced discretely within the construction site. These slab support columns may extend for the full depth of the construction site.

In this mode of the method, ground under the slab may now be excavated down to a level that aligns with a (first) line of nesting elements arranged in the hollow piles of the retaining wall at the site perimeter, the line of nesting elements being at a level that corresponds to a next floor slab.

In this mode of the method, the cementitious material for the next floor slab may be poured at the excavated ground level within the construction site perimeter. This next floor slab may optionally make use of (e.g. be connected to so as to be supported by) the one or more slab support columns.

In this mode of the method, prior to pouring the next slab at the excavated ground level, a cover at each pile wall opening at each of a line of nesting elements may be removed. Thus, when the next floor slab is formed (i.e. poured), the cementitious material can also flow in through each of the pile wall and nesting element openings and into the respective hollow pile, so as to fill up the pile, either to a surface of a next lower nesting element, or to a base of the hollow pile (i.e. depending on how long each pile is, how many nesting elements it has, and how many underground floors are being formed).

In this mode of the method, ground under the next floor slab may now by excavated down to a further level that aligns with an additional lower (second) line of nesting elements in the hollow piles in the retaining wall, the additional line of nesting elements being at a level that corresponds to a further floor slab.

In this mode of the method, a further floor slab may now be formed on ground at the excavated further level. Then, the further steps similar to those as set forth above may be performed.

In this mode of the method, and as required, ground under the further floor slab may be excavated and a yet further floor slab may be poured. Then, the further steps similar to those as set forth above may be repeated until, eventually, a final base floor slab is formed at a lowermost level corresponding to a base of the retaining wall. This can complete this mode of implementing the top-to- bottom construction method.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments will now be described by way of example only, with reference to the accompanying drawings in which Figure 1 shows an axonometric projection of a first nesting element embodiment in the form of a stopper element.

Figure 2 shows an axonometric projection of the stopper element of Fig. 1 with optional reinforcement rods inserted therethrough.

Figure 3 shows an axonometric projection of the stopper element of Fig. 1 retained in an opening in a wall of a hollow pile in the form of a sheet pile.

Figures 4a, 4b and 4c each show an axonometric projection of the sheet pile, with: Fig. 4a showing the sheet pile prior to the pouring of cementitious material thereinto; Fig. 4b showing the sheet pile post the pouring of cementitious material into the top of the sheet pile; and Fig. 4c showing the sheet pile post the pouring of cementitious material into the pile system via an opening through the stopper element.

Figure 5 shows an axonometric projection of a hollow king pile for use with the sheet pile of Figs. 3 and 4, as part of a pile system.

Figure 6 shows a plan view of the king pile of Fig. 5 when attached at a corner to two sheet piles of Fig. 4, each filled with a cementitious material.

Figure 7 shows an axonometric projection of a pile system comprising a plurality of alternating sheet and king piles, with a stopper element retained in an opening in a side wall of each sheet pile.

Figures 8a and 8b respectively show an axonometric projection (Fig. 8a) and side view (Fig. 8b) of a pile system akin to Figs. 6 & 7, with a floor slab formed at the level of each of a horizontal line of stopper elements, as well as showing a basement level floor slab, and ground level floor slab (Fig. 8a). Figures 9a, 9b and 9c respectively show axonometric projections of components of a pile drive system, with: Fig. 9a showing a pile driving mandrel that comprises a head and two pins that are configured to protrude through flanges of the sheet pile; Fig. 9b showing the sheet pile prepared for installation with a detachable cover over the stopper element; and Fig. 9c showing the sheet pile prepared for installation through the fitting of a wedge attachment at a lower open end of a box section of the sheet pile.

Figures 10a to lOe respectively show side schematic cross-sectional views of one mode of the sequence/stages of constructing a top-to-bottom underground construction. Figure 11 shows an axonometric projection of a second nesting element embodiment, also in the form of a stopper element. Figure 12 shows an axonometric projection of an alternative hollow pile embodiment in the form of a square box-section sheet pile.

Figure 13 shows, in axonometric projection, an elongate form of the square box- section sheet pile of Figure 12, and illustrating an opening for the stopper element of Figure 11.

Figure 14 shows, in axonometric projection, a series/sequence of elongate square box-section sheet piles of Figure 13, being joined together to form a retaining wall.

Figures 15A, 15B and 15C show, in axonometric projection, three different mandrel types that can be used for driving into the ground to enable the elongate square box-section sheet piles of Figure 13 to be inserted therein.

Figure 16 shows, in axonometric projection, two of those three mandrel types joined together as they would be after being driven into the ground by a pile- driving apparatus. Figure 17 shows, in axonometric projection, one of the mandrel types after having been driven into the ground and then excavated, with a square box-section sheet pile of Figure 13 inserted therein.

Figure 18 shows a schematic plan of a number of (four different) mandrel types as they would be arranged to define a retaining wall having a rectangular perimeter.

DETAILED DESCRIPTION OF SPECIFCIC EMBODIMENTS

In the following detailed description, reference is made to accompanying drawings which form a part of the detailed description. The illustrative embodiments described in the detailed description, depicted in the drawings and defined in the claims, are not intended to be limiting. Other embodiments may be utilised and other changes may be made without departing from the spirit or scope of the subject matter presented. It will be readily understood that the aspects of the present disclosure, as generally described hereafter and illustrated in the drawings can be arranged, substituted, combined, separated and designed in a wide variety of different configurations, all of which are contemplated in this disclosure.

The method of construction as described herein can be deployed in a so- called "top-to-bottom" construction methodology. The method can make use of a sheet pile such as those used for retaining walls, but modified for the top-to- bottom construction methodology. More particularly, the disclosure relates to the formation of a retaining wall structure at the perimeter of a construction site such as an underground basement, car park, cellar, etc. and upon which e.g. a multistory construction may be erected.

Also described herein is a nesting element in the form of a stopper element, one or more of which can be used to modify each sheet pile, to make the sheet pile suitable for a stage-wise pouring thereinto of a cementitious material such as concrete. The stopper elements can enable floor slabs of the underground construction to key into each modified sheet pile as part of the top-to-bottom construction methodology. Also disclosed are components of a pile driving system which enable each modified sheet pile to be driven into the ground to form the retaining wall. The top-to-bottom construction methodology described herein can reduce time and construction costs, as well as simplifying existing underground construction techniques.

Referring firstly to Figure 1, an embodiment of a nesting element is shown in the form of a stopper element (100). The stopper element (100) is configured for use in a hollow pile in the form of a generally rectangular sheet pile (200) as best shown in Figure 3. The stopper element (100) is configured such that it is able to be retained at or adjacent to an opening (230) defined in a wall of the sheet pile (200). This modifies the sheet pile (200), the effect of which will be explained hereafter. Whilst the stopper element (100) is depicted as a rectangular prism in Figure 1, as will also be explained hereafter, the stopper element (100) can take a number of other forms.

The opening (230) is defined in a side wall (240) of the sheet pile (200) to open into an elongate box section (201) of the sheet pile that extends generally centrally through the pile and provides a main structural "spine" thereof. In the embodiment of Figures 3 & 4, the stopper element ( 100) is inserted into this side wall opening to locate and be retained adjacent to opening (230); e.g. an in-use upper surface (102) of the stopper element assumes an in-use location that is located at (or may locate just above) an upper part of the side wall opening. However, as will be explained hereafter, when the stopper element (100) takes other forms it may, for example, be inserted into the pile via an open upper end of the box section (201).

The stopper element (100) can allow the sheet pile (200) to be employed in a top-to-bottom construction methodology. In this regard, the upper surface (102) of the stopper element (100) can stop the flow of a pour of concrete down through the box section (201), which has a number of benefits in the top-to- bottom methodology, as will also be described hereafter.

The upper surface (102) of the stopper element (100) is also configured such that, when the stopper element is located at the opening (230), surface (102) substantially conforms to an internal profile at a transverse cross-section of the box section (201). This substantial conformity does not exclude the upper surface (102) being spaced from an internal surface (210) of the sheet pile (200), but it does require the surface (102) to be sufficiently close to surface (210) so as not to allow concrete (150) that is poured into an open upper end of the box section (201) to pass through to a lower section of the pile.

As will be described in greater detail hereafter, this "concrete-stop" feature enables the sheet pile to be "tied" to a floor slab as the top-to-bottom construction method proceeds. This in turn means that construction is able to continue above and below the pile level presently under construction, i.e. once the concrete ( 150) has cured at a given level. This may be advantageous in improving the efficiency of the construction, potentially reducing construction times and associated costs. Furthermore, for a small span floor area, the stopper element (100) can enables each sheet pile to "key" to and thus support a floor slab (Figure 8a, 410), such that the pile retaining wall substantially supports the floor slab. Usually, however, separate slab support columns are provided to support each floor slab as each is constructed.

In the embodiment depicted, the stopper element (100) takes the form of a rectangular prism that is readily fabricated (e.g. welded from plate, moulded from tough plastic, etc.). The stopper element (100) comprises at least one, and in this case two side walls (20) that each extend downwardly in use from respective opposing side edges (21, 22) of the surface (102). The stopper element (100) additionally comprises a rear wall (25) that extends downwardly in use from a rear edge (23) of the surface (102). In use, each of the side walls (20) and rear wall (25) may closely face or abut a corresponding surface of the box section (201) of the sheet pile (200), to better support the stopper element (100) within the box section. The side walls (20) and rear wall (25) increase the structural rigidity of the stopper element (100) such that it is better able to support concrete (150) that impinges and weighs upon the surface (102) when poured into the box section (201) of the sheet pile (200) from above.

The stopper element (100) comprises a flange in the form of a peripheral retention lip (30) that surrounds a front face of the stopper element (100), with the lip (30) being connected to each of the surface (102) and side walls (20) and extending generally orthogonally therefrom. The lip (30) is configured to be arranged against an exterior surface of the sheet pile (200) and retains the stopper element (100) at the opening (230). The lip (30) helps to support the stopper element (100), such that the weight of concrete (150) on the surface is resisted and generally borne by the lip (30). The lip (30) may be affixed to the exterior surface of the sheet pile (e.g. bolted, screwed, adhered, etc.). Whilst the flange is shown in the form of a peripheral lip, it may simply comprise one or more tabs, etc. that can enable the stopper element (100) to be retained (e.g. affixed) at the opening (230).

When the pile is not in a sheet form, and has a different cross-sectional profile (e.g. tubular, triangular, square, hexagonal, etc.), the stopper element (100) can be reshaped accordingly, such as by assuming the shape as depicted in the embodiment of the stopper element (100') shown in Figure 1 1. In any case, typically the stopper element is shaped to sufficiently correspond to the pile transverse cross-section so as not to allow concrete that is poured into the pile to pass therethrough into a lower section of the pile.

Regarding the stopper element (100') as shown in Figure 1 1, it is shaped and configured to suit to a hollow pile (200'). In Figures 1 1 to 14, reference numerals that are denoted by an apostrophe correspond to the described elements as referred to previously and hereafter.

As shown in Figures 12, 13 and 14, the hollow pile (200') can have a cross-sectional profile wherein a pair of female clutches (220a') are formed within two of the side walls (240') at an intermediate location along each respective side wall (240').

A pair of male clutches (220b') are formed to project from an intermediate location along a different side wall (240') to that of the female clutches. It is understood that a single side wall could have any number of either male or female clutches, or alternatively could have both male and female clutches, as suitable, to resist the tensile or torsional force loading on the clutches in use. The sheet pile (200') has an opening (230') that is defined in a side wall (240') of the pile (200') at which the stopper element shown in Figure 1 1 (100') can be aligned. The stopper element (100') shown in Figure 11 is configured such that it can be slid through the hollow cross section of the pile (200') and retained (e.g. rivetted) adjacent to the opening (230'), such that the in-use upper surface ( 102') of the stopper element (100') assumes an in-use location that is located at (or it may locate just above) an upper part of the side wall opening (230'). To facilitate its retention adjacent to the opening, the stopper element (100') comprises a flange in the form of a peripheral retention lip (30') that projects orthogonally upwards in use from a front face of the stopper element (100'), with the lip (30') being adapted such that it can be riveted to the inside of the hollow pile (200').

Referring now to Figure 2, the stopper element (100) is open at two adjacent

"faces" (50, 70) thereof (likewise in the stopper element (100')). The second face (50) is arranged to face downwardly in the box section (201) of sheet pile (200) in use. The first open face (70) is arranged to face outwardly at the sheet pile wall opening (230). The openings (50, 70) an allow concrete (150) to flow into the sheet pile and then down into the box section (201). This flow of concrete occurs when, for example, an adjacent floor slab (e.g. slab 410 to 430 in Figs. 8a & 8b) is being poured at the construction site. In this way, the floor slab can become "keyed" to the retaining wall.

The stopper element (100) can be configured to support one or more optional reinforcing bars/rods (1 10) that extend vertically in use through the box section (201) of the sheet pile (200). For example, the surface (102) can be provided with one or more holes (40) therethrough, each sized for a respective one of the reinforcing bars/rods (1 10). The stopper element (100) supports the reinforcing bars/rods (1 10) at the surface (102), and maintains a spacing between adjacent reinforcing bars/rods as concrete (150) flows into the sheet pile. Where the sheet pile (200) has multiple stopper elements (100) spaced out along its length, these work together to evenly support the reinforcing bars/rods (1 10) through the box section (201), maintaining a spacing between adjacent reinforcing bars/rods along the length of the sheet pile (200).

Typically, a plurality of sheet piles (200) with associated stopper elements (100) are pre-assembled (e.g. prior to being brought to a construction site). Each sheet pile may (Fig. 4a) or may not (Fig. 3) be pre-assembled with the reinforcing bars/rods (110) extending through the box section (201). The plurality of sheet piles (200) can be joined to each other, as described below. In practice, however, in deployment of the pile system described herein, the sheet piles (200) are deployed in conjunction with a plurality of king piles (300) - see Figs. 5-7.

Each king pile (300) takes the form of a cylindrical (e.g. tube) pile. In use, each sheet pile (200) has a king pile (300) arranged and connected along either side thereof, such as depicted in Figures 6 & 7. Thus, the retaining wall (W) is constructed with alternating sheet piles (200) and king piles (300), including at the corners thereof (Fig. 6). Typically, each sheet pile (200) has a plurality of openings (230) defined in and spaced out along the side wall (240) of the pile (200). For example, for a 12 metre length side wall (i.e. a length that can be permissibly transported on a truck), three intermediate openings (230) can be provided at 3 meter intervals along its length.

Each opening (230) is located to correspond to an adjacent floor level in use of the pile (200). For example, as shown in Fig. 8, and moving down from a ground level floor slab (400), a first opening (230) corresponds to an adjacent first underground floor slab (410), a second opening (230') corresponds to an adjacent second lower underground floor slab (420), and a third opening (230") corresponds to an adjacent third lower underground floor slab (430). Each of these slabs is spaced above a base level floor slab (450). The base slab (450) may also be keyed into respective base openings defined in each sheet pile side wall (240) - not shown, but as indicated in Fig. 8a. A stopper element (100) is provided at each of these side wall openings (230, 230', 230", etc.).

Each of the sheet piles (200) and king piles (300) are configured along respective sides thereof to be connected to each other along their length, such as depicted by Figure 7. For example, when the hollow (200) and king (300) piles are connected together, they are able to form a substantially self-supporting wall. The sheet piles (200) and king piles (300) may be as set forth in WO

2017/063021, the relevant contents of which are incorporated herein by reference.

In this regard, as depicted in Figure 3, each sheet pile (200) has two sets of flanges (220) that extend out from opposite sides of the box section (201). One set of flanges comprises male clutches (220b) along a distal edge thereof, and the other set of flanges comprises female clutches (220a) along a distal edge thereof. Likewise, on the king pile (300) - i.e. male clutches (320b) and female clutches (320a). The interconnection between sheet piles, or between each sheet pile and a respective king pile, is by way of complementary male (220b, 320b) and female (220a or 320a) clutches being slid together longitudinally. The sheet pile (200) and king pile (300) are thus interconnected along respective adjacent longitudinal sides thereof such as depicted in Figure 6 corner or Figure 7 (wall section). Once the sheet (200) and king (300) piles have been connected together, and optionally reinforced, to form the wall, concrete (150) is poured into the piles at an open upper end of each of each pile such as that depicted in Figures 4b, 4c and 6. Thus, the pile system can also act as form work for the concrete when forming the retaining wall.

In an alternative embodiment, as shown in Figures 13 and 14, each hollow sheet pile (200') can be located adjacent to another hollow sheet pile (200'), without requiring the use of king piles. In this regard, adjacent hollow sheet piles (200') are connected by sliding together longitudinally along complementary male (220b') and female (220a') clutches. In this embodiment, not every sheet pile (200') need have openings (230') for respective stopper elements (100'). For example, every second or third pile (200') may have openings (230') pre-cut therein, or in some embodiments, openings may be cut in piles that are a predetermined distance apart from one another (e.g. 1 metre). Such spacings have been observed to provide sufficient load bearing connections from a floor through to the pile.

In some embodiments, the sheet piles and stopper elements can be manufactured from plastics or composite materials. In other embodiments, the sheet piles and stopper elements can be manufactured from steel.

To drive the sheet piles (200) into the ground a pile driving installation system is employed.

As depicted in Fig. 9a, the pile driving installation system comprise a mandrel (500). The mandrel (500) comprises a head (550) that is configured to impact on the sheet pile (200) upper end to cause an in-use lower end of the sheet pile to be driven into the ground. The head (550) is dimensioned to effectively extend over the entire upper end and thereby close the sheet pile at this end during pile driving. The mandrel (500) is operated at height from e.g. a crane or other like vehicle on a construction site to act as the pile driver.

The mandrel (500) further comprises two spaced elongate pin members (510) that each extend from the mandrel head (550) to locate and extend between a respective one of the sets of sheet pile flanges (220). In this way, the mandrel (500) better engages with the sheet pile (200) during pile driving. After pile driving, the pin members (510) can be slidingly withdrawn from the sheet pile (200). Each pin member (510) is configured to extend beyond the sheet pile (200) lower end in use as shown. Each pin member (510) further comprises a pointed end (520) to facilitate its insertion into the ground.

The drive installation system further comprises an attachment in the form of a wedge (530) for location at an in-use open lower end of the sheet pile (200) as depicted in Figure 9c. The wedge (530) may be force-fit into the pile (200) lower end, to be secured thereto during pile driving. The wedge (530) remains in place after pile driving. The wedge (530) is configured to prevent ground matter (earth) from entering the sheet pile (200) during pile driving. The wedge (530) protrudes to a pointed end (531) to facilitate its insertion into the ground.

The drive installation system further comprises a detachable cover plate (560) for each stopper element (100), when the latter is located in the sheet pile (200) side wall opening (230). The cover plate (560) is releasably secured to the stopper element (100) at the side wall opening (230) (i.e. for subsequent removal during a construction phase - i.e. to allow for the inflow of concrete into the sheet pile). The cover plate (560) is also configured to prevent ground matter (earth) from entering the hollow pile during driving of the sheet pile into the ground.

In an alternative embodiment of the pile driving installation system, box section mandrels can be used instead of driving the individual sheet piles. This alternative installation system comprises a first box section mandrel (600) as shown in Figure 15 A. The first box section mandrel (600) has an elongate tubular internal profile that is correspondingly dimensioned to an external profile of the hollow pile (200). The first mandrel (600) is driven into the ground (e.g. by a suitable pile-driving installation mechanism). The ground (e.g. earth) entrained within the first mandrel can then be removed by drilling, auger, screw, or any other appropriate method as known to those skilled in the art. Once emptied, a sheet pile (200) can then be located within the hollow first mandrel (600).

A second mandrel (610), as illustrated in Figures 15B and 15C can be driven into the ground adjacent the first mandrel (600), as shown in Figure 16. The second mandrel (610) can be driven either prior to or after drilling of the ground from within the first mandrel (600).

In some embodiments, it may be advantageous to drive the first mandrel (600) and multiple second mandrels (610) prior to drilling, and then to drill out each thereafter. In some embodiments, there may be a need only to use two second mandrels (610), i.e. that are reused repetitively to create the entire retaining wall.

The second mandrel can generally take the form of elongate channel having opposing elongate side walls (640) that are connected to one another by a rear wall (630). Each side wall (640) has a female clutch (622) proximal the distal ends of the side wall (64), the female clutch (622) being configured to engage a corresponding and respective male clutch (620) of an adjacent mandrel. The corresponding and respective male clutch (620) may project from one of either; the opposing sides walls (640A or 640B) of an adjacent first mandrel (600), the opposing side walls (640) of an adjacent second mandrel (61 OA) or the same side wall of an adjacent second mandrel (6 IOC). As can be seen in Figure 18, the second mandrel can have multiple different configurations (such as 610A-D) to enable the mandrel system to turn corners or forms other angles and shapes as needed. For example, Figure 15C shows a mandrel wherein the rear wall (630) of the second mandrel (610B) has a pair of female clutches (624) formed within the rear wall (630) at an intermediate location thereon. Figure 18 shows a mandrel (610D) that replaces one of the female clutches with a channel clutch (61 1). The channel clutch is shaped and sized (i.e. it is sufficiently wide) to receive laterally therein an adjacent female clutch of the mandrel (6 IOC).

Regardless of the specific configuration, the connection of male and female clutches between mandrels enables the guided driving of a subsequent "second" mandrel (either after a first or a second mandrel) into the ground.

The pile driving installation system, where box section mandrels are used, can be advantageous in that the clutches of the sheet piles are not exposed to contamination with dirt nor are they subjected to shear and other damaging impact forces during the driving process. In some embodiments, as seen in Figures 15 to 18, the first (600) and second (610) mandrels can be provided with a flange (650) that projects substantially perpendicularly away from a side wall so as to facilitate gripping of the mandrel by a pile driving mechanism.

Figures 16 and 18 each depict an array of mandrels that can be arranged to create different configurations of retaining wall, such as a straight wall as depicted in Figure 14, or a wall having a rectangular perimeter as depicted in Figure 18.

In each case, a first mandrel (600) is driven into the ground, and a second mandrel (610) is driven adjacent to the first mandrel (600). The first (600) and second (610) mandrels are aligned to connect along their clutches, and the second mandrel (610) is thus guided into the correct alignment alongside the first mandrel (600) during driving. Further, additional second mandrels (610) can then be driven into the ground alongside either the first (600), second (610), etc. mandrels as required. The ground within an interior of the first mandrel (600) and second mandrel (61) is then removed (such as by drilling, etc.). A sheet pile (200') can then be located within the hollow first mandrel (600). Once the first mandrel (600) is removed from the ground, a second sheet pile (200') can then be located within the hollow second mandrel (610) that sits adjacent the sheet pile (200') by sliding the second sheet pile along the clutches (i.e. as shown in Figure 14). The second mandrel (610) is then removed from the ground and the process repeated until the retaining wall is constructed. As set forth herein, the sheet piles (200') can have a series of discretely spaced reinforcing bars/rods arranged to extend vertically therein. Thereafter, concrete in-pouring can commence, and the top-to-bottom construction of the site can take place.

Figure 10 depicts an embodiment of a method of constructing a retaining wall such as those depicted in Figures 7 or 8. As depicted in Figure 10a, the method first comprises driving the pre-prepared king (300) and sheet (200) piles into the ground to form a retaining wall perimeter at the construction site. The sheet (200) and king (300) piles are driven into the ground to be interconnected in sequence moving along a line of the retaining wall, until the perimeter wall is completed. The method then comprises pouring concrete (150) into each pile (200, 300) at the in-use open upper end thereof. Each may be reinforced as set forth above. The concrete flows down inside each sheet pile until it reaches a surface (102) of the uppermost stopper element (100) located at a respective wall opening (230) such as depicted in Figure 4b. In the case of a king pile (300), and between the sheet pile flanges (220) the concrete flows down to a pile bottom thereof. The filled king piles (300) and filled flanges (220) thus support a remainder of the retaining wall, whereby top-to-bottom construction of the site can now commence.

As also depicted in Figure 10a, the method also comprises forming a number of slab support columns (290) deep into the ground (i.e. beyond the retaining wall) and spaced discretely within the construction site perimeter.

As depicted in Figure 10b, the method next comprises surface excavation and the forming of the ground level floor slab (400) over the slab support columns (290).

The top-to-bottom construction methodology to be implemented will be described hereafter with further reference to Figures 10c to lOe. It should be noted that this method can also allow for underground and above ground construction to take place simultaneously.

As depicted in Figure 10c, the method next comprises excavating ground under the slab (400) down to a level that aligns with a second line of nesting elements (100) arranged at openings (230') in the sheet piles (200), i.e. at the level that corresponds to the floor slab (420) - Fig. 8b & 10c. The exposed cover plates (560) are then removed, and formwork and reinforcing for the floor slab are then constructed. The floor slab (420) is then poured with concrete, with the floor slab connecting to so as to be supported by the slab support columns (290). The concrete also flows into the sheet pile via each open stopper element (100) at opening (230), then flowing into the box section (201) of the respective sheet pile (200), so as to fill it up to a next lower stopper element located at the level of floor slab (430). As depicted in Figure lOd, the method next comprises excavating ground under the slab (420) down to a level that aligns with a bottom line of stopper elements (100) arranged at lowermost openings in the sheet piles (200), i.e. at the level that corresponds to the base level floor slab (450). The exposed cover plates (560) are removed, and formwork and reinforcing for the base level floor slab is constructed. The floor slab (450) is then poured with concrete, with the floor slab connecting to so as to be supported by the slab support columns (290). The concrete also flows into the sheet pile via each open stopper element (100) at opening (230), then flowing into the box section (201) of the respective sheet pile (200), so as to fill it up down to each wedge (530).

As depicted in Figure lOe, the method now comprises building formwork for each of the floor slabs (410 and 430). This formwork can simply be erected on the already poured (and sufficiently cured) floor slabs (420 and 450) respectively. The exposed cover plates (560) are removed at each of the levels for floor slabs (410 and 430). Each floor slab (410 and 430) is then poured with concrete, with each floor slab connecting to so as to be supported by the slab support columns (290). The concrete also flows into the sheet pile via each open stopper element (100) at opening (230), and then flows into the box section (201) of the respective sheet pile (200), so as to fill it up down to each now concreted stopper element located at floor slabs (420 and 450) respectively.

In an alternative mode of the top-to-bottom method, each floor slab (410, 420, 430, 450) may be formed in sequence, moving down floor-by-floor from the ground level floor slab (400). Thus, each level is excavated is sequence. Variations and modifications may be made to the parts previously described without departing from the spirit or ambit of the disclosure.

In the claims which follow and in the preceding description, except where the context requires otherwise due to express language or necessary implication, the word "comprise" or variations such as "comprises" or "comprising" is used in an inclusive sense, i.e. to specify the presence of the stated features but not to preclude the presence or addition of further features in various embodiments.

Claims

A nesting element for use in a hollow pile, the nesting element being configured to be retained at an opening defined in a wall of the pile, the nesting element comprising a surface that is configured such that, in use, the surface substantially conforms to an internal profile at a transverse cross- section of the pile.

A nesting element as claimed in claim 1, wherein the nesting element is configured such that it is able to be positioned adjacent to the opening, which is defined in a side wall of the pile.

A nesting element as claimed in claim 1 or 2, wherein the surface extends generally orthogonally from a flange, and wherein the flange is configured to be arranged against an interior or exterior surface of the hollow pile to be retained thereat in use.

A nesting element as claimed in claim 3, wherein the nesting element further comprises at least one side wall that extends from the surface in a direction opposite to the flange.

A nesting element as claimed in claim 4, wherein the at least one side wall is configured to locate adjacent to an interior surface of the hollow pile in use. A nesting element as claimed in any one of the preceding claims, wherein the nesting element is configured to support one or more reinforcing bars that in- use extend vertically through the pile.

A nesting element as claimed in claim 6, wherein the surface is provided with one or more holes therethrough, each sized for a respective one of the one or more reinforcing bars, to support the rods at the surface, and to maintain a spacing between adjacent rods.

A nesting element as claimed in any one of the preceding claims, wherein, when the hollow pile comprises a sheet pile having a rectangular box section extending for its length, the nesting element is correspondingly dimensioned to nest in the rectangular box section.

9. A nesting element as claimed in claim 8, wherein the surface defines an in-use upper surface of the nesting element, with the nesting element comprising two opposing side walls that each extend downwardly in use from respective opposing side edges of the upper surface, and a rear wall that extends downwardly in use from a rear edge of the upper surface.

10. A nesting element as claimed in claim 9, wherein the nesting element is open at at least two sides thereof, with the two open sides being adjacent to one another; wherein a first of the two open sides is arranged to open outwardly of the sheet pile at the wall opening in use, and a second of the two open sides is arranged to open downwardly in the sheet pile in use.

11. A pile system comprising:

a hollow pile that has at least one opening defined in a wall of the pile; and a nesting element as defined in any one of the preceding claims, the nesting element being configured such that it is able to be retained at the at least one opening of the hollow pile.

12. A pile system as claimed in claim 11, wherein the opening is defined in a side wall of the pile, and wherein the nesting element is configured such that it is able to be inserted into the pile side wall via or adjacent to the opening.

13. A pile system as claimed in claim 11 or 12, wherein the hollow pile has a plurality of openings defined in and spaced out along the wall of the pile, with each opening being located to correspond to an adjacent floor level in use of the pile, and with a nesting element being provided for each opening.

14. A pile system as claimed in any one of claims 11 to 13, wherein the hollow pile comprises a sheet pile having a rectangular box section extending for its length, and wherein the nesting element is correspondingly dimensioned to nest in the rectangular box section.

15. A pile system as claimed in any one of claims 11 to 14, the system comprising a plurality of hollow piles.

16. A pile system as claimed in claim 15, wherein each of the hollow piles are configured to be connected to each other along their length whereby, when the hollow piles are connected together, they are thereby able to form a substantially self-supporting wall.

17. A pile system as claimed in claim 16, wherein each of the hollow piles

comprises at least one male clutch and at least one corresponding female clutch, the male clutch projecting from a side wall of the hollow pile to extend longitudinally along the length of the side wall, and the female clutch being formed at a side wall of the hollow pile to extend longitudinally along the length of the side wall, the male and female clutches able to be aligned on adjacent piles whereby, when the hollow piles are connected together in-use via their clutches, they are thereby able to form a substantially smooth face along the wall.

18. A pile system as claimed in claim 17, wherein the male clutch is formed to project from an intermediate location along the side wall or is formed along a distal end of the side wall, and wherein the female clutch is respectively formed within the side wall at an intermediate location along the side wall or is formed along a distal end of the side wall.

19. A pile system as claimed in claim 18, wherein a rebate is provided within and along the length of the or each female clutch such that, in use, a sealing bead may be inserted into the rebate in use.

20. A pile system as claimed in claim 19, wherein, when the hollow piles have been connected together to form the wall, the system is configured to have a cementitious material poured into the connected piles at an open upper end of each of the hollow piles.

21. A pile system as claimed in claim 20, wherein, prior to pouring the

cementitious material into the open upper end of each of the hollow piles, the system is configured to receive reinforcing vertically through each of the hollow piles.

22. An installation system for installing into ground the pile system as claimed in any one of claims 11 to 21, the installation system comprising a first mandrel having an elongate tubular internal profile that is correspondingly dimensioned to an external profile of the hollow pile.

23. An installation system as claimed in claim 22, wherein the installation system further comprises a second mandrel, the second mandrel comprising an elongate channel having opposing elongate side walls that are connected to one another by a rear wall, each side wall being configured to connect with a side wall of an adjacent first mandrel or a rear or side wall of an adjacent and further second mandrel, the connection being configured such that, in use, when the first mandrel has been driven into the ground, the first mandrel is able to guide the second mandrel whilst being driven into the ground.

24. An installation system as claimed in claim 23, wherein each side wall of the second mandrel comprises a female clutch that, in use, is configured to engage a corresponding and respective male clutch, the male clutch(es) projecting from one of:

opposing sides of an adjacent first mandrel;

opposing side walls of an adjacent second mandrel;

- the same side wall of an adjacent second mandrel.

25. An installation system as claimed in any one of claims 22 to 24, wherein each of the first and second mandrels comprises a flange that projects substantially perpendicularly away from a side wall thereof, the flange configured to facilitate gripping of the mandrel by a pile driving mechanism.

26. A method of constructing a retaining wall, the method comprising:

driving into ground a first mandrel as set forth in any one of claims 22 to 25;

removing ground from within an interior of the first mandrel.

27. A method as claimed in claim 26, the method further comprising:

driving into the ground a second mandrel as defined in claim 23 or 24, such that the side walls of the second mandrel connect with the first mandrel to be guided thereby;

removing ground from within an interior of the second mandrel.

28. A method as claimed in claim 27, the method further comprising: driving into the ground a further second mandrel, such that the side walls of the second mandrel connect with the second mandrel existing in the ground to be guided thereby;

removing ground from within an interior of the further second mandrel.

29. A method as claimed in any one of claims 26 to 28, the method further

comprising locating a hollow pile as defined in any of claims 11 to 21 within the first mandrel.

30. A method as claimed in claim 29, the method further comprising:

removing the first mandrel from the ground;

locating a hollow pile as defined in any of claims 11 to 21 within the second mandrel such that the hollow pile connects to the adjacent hollow pile that was located within the first mandrel;

removing the second mandrel from the ground.

31. A method as claimed in claim 30, the method further comprising:

locating a hollow pile as defined in any of claims 11 to 21 within a further second mandrel such that the hollow pile connects to the adjacent hollow pile that was located within the second mandrel;

removing the further second mandrel from the ground.

32. A method as claimed in any one of claims 29 to 31, the method further

comprising arranging one or more elongate reinforcing bars to extend vertically through and for a length of each hollow pile, whereby each elongate reinforcing bar extends vertically through one or more nesting elements arranged in each hollow pile.

33. A method as claimed in any one of claims 29 to 32, the method further

comprising pouring a cementitious material into the hollow pile at an in-use open upper end thereof, with the cementitious material flowing down inside the pile until it reaches a surface of an in-use uppermost nesting element located at a respective wall opening.

34. A method as claimed in any one of claims 29 to 33, wherein the retaining wall is constructed along a perimeter of a construction site.

35. A method as claimed in claim 34, wherein a slab of cementitious material is formed at the ground of the construction site perimeter, optionally with one or more slab support columns having first been formed into the ground.

36. A method as claimed in claim 35, wherein ground under the slab is excavated down to a level that aligns with a line of nesting elements arranged in the hollow piles of the retaining wall at the site perimeter, the line of nesting elements being at a level that corresponds to a next floor slab.

37. A method as claimed in claim 36, wherein the cementitious material for the next floor slab is poured at the excavated ground level within the construction site perimeter, the next floor slab optionally making use of the one or more slab support columns.

38. A method as claimed in claim 37, wherein prior to pouring the next floor slab at the excavated ground level, a cover at each pile wall opening at each of a line of nesting elements is removed such that, when the next floor slab is poured, the cementitious material is able to flow in through each of the pile wall and nesting element openings and into the respective hollow pile, so as to fill up the pile, either to a surface of a next lower nesting element, or to a base of the hollow pile.

39. A method as claimed in claim 38, wherein ground under the next floor slab is excavated down to a further level that aligns with an additional lower line of nesting elements in the hollow piles in the retaining wall, the additional line of nesting elements being at a level that corresponds to a further floor slab.

40. A method as claimed in claim 39, wherein a further floor slab is poured at the excavated further level, and steps similar to those as set forth in claims 37 to 39 are performed.

41. A method as claimed in claim 40, wherein, as required, ground under the further floor slab is excavated and a yet further floor slab is poured, with steps similar to those as set forth in claims 37 to 39 being repeated until a final base floor slab is formed at a lowermost level corresponding to a base of the retaining wall.