Field of the Invention

The present disclosure relates to groundworks. More particularly, but not exclusively, this invention

concerns a kit of parts comprising a groundworks

apparatus, such as a piling apparatus, and two sets of impression-forming elements for use in differently sized foundation excavations. Aspects of the invention also relate to a groundworks apparatus, a method of creating impressions in a foundation excavation and a method of modifying a groundworks apparatus.

Background of the Invention

Groundworks includes the work related to formation of the foundations for a building structure (such as commercial buildings, residential buildings,

habitable/non-habitable buildings, bridges, and other civil constructions requiring groundworks) . Various different types of foundation structures can be used, such as diaphragm walls, and piles. The formation of concrete piles using essentially smooth-sided bores (for example to create a contiguous, interlocking or secant series of piles) is well known.

Some disclosures have suggested forming impressions in the sides of the bore prior to the casting of the pile. When the concrete is then cast in the bore, it occupies the volume of the impressions. This is thought to improve the strength of the piling by increasing the skin friction at the excavation wall to create a larger pull out resistance and/or by providing a piling

structure that better reacts loads into the ground.

Examples of apparatus for forming impressions in the walls of pile bores are disclosed in US 5908268 and

WO2014059537 :

US2908268 discloses a piling apparatus that is arranged to be inserted into a pile bore. Pressure is applied to horizontally acting pressers to form

impressions in the wall of the bore, and the apparatus is then moved vertically so that a plurality of impressions can be formed within the pile bore.

WO2014059537 also discloses an apparatus that is inserted into a pile bore. The apparatus forms

impressions in the wall of the bore via hydraulically activated rams that extend a predetermined distance outwardly .

The piling apparatus are designed to operate in a specific size of foundation excavation (for example insertion into a bore that has been excavated using an auger of a specific diameter) . For example, US 5908268 discloses an arrangement in which a vertical pressing board is almost the same in outer diameter as the bored hole. In some embodiments of US 5908268, this vertical pressing plate is provided with a convex portion to create an impression in the side of the bore. In

WO2014059537 the bore is lined with a hollow pile and the piling apparatus is lowered into the hollow pile to make protrusions in the annular side wall. The apparatus includes a support member shaped to extend out to abut the inner surface of the wall of the pile.

Thus, the apparatus in either of the above-mentioned prior art arrangements may be suitable for use in a bore of diameter D, but would not be suitable for use in diameters that are smaller than D because the apparatus could not fit into the bore. The apparatus would also not be suitable for use in bores have diameters greater than D because the displacement stroke (or the

combination of the stroke with force) of the actuators would not be sufficient to create the required

impressions in the sides of the bore.

This is reflective of the approach in piling

activities more generally; the apparatus needed for each different excavation and/or follow up activity tends to be bespoke to suit the varying requirements of each job.

This approach to piling activities tends to limit the flexibility of the apparatus for use elsewhere.

The present invention seeks to mitigate at least some of the above-mentioned problems. Alternatively or additionally, the present invention seeks to provide an improved piling apparatus of the type that forms

impressions in foundation excavations.

Summary of the Invention

The present invention provides, according to a first aspect, a kit of parts comprising: a groundworks

apparatus for insertion into a foundation excavation, the apparatus comprising an actuation assembly, a first set of impression-forming elements mounted for movement by the actuation assembly, the first set of impression forming elements moveable by a displacement stroke of the actuation assembly between a retracted configuration in which the impression-forming elements are retracted such that the apparatus can move along the foundation

excavation, and an extended configuration in which the impression-forming elements extend outwards to create an impression in the side of the excavation; and wherein the kit comprises a second set of impression-forming elements for fitting onto the apparatus to move between a

retracted and an extended configuration, wherein the second set of impression-forming elements is configured for operation in a different-width excavation than the first set, such that, when fitted onto the apparatus, the second set of impression-forming elements extend, under the displacement stroke of the actuation assembly, to a different width than those of the first set.

Providing a kit of parts having an apparatus and at least two sets of impression-forming elements, with one being configured for operation in a wider foundation excavation, has been found to be especially beneficial because it enables the same apparatus to be configured for differently sized foundation excavations.

In embodiments of the present invention, the second set of impression-forming elements extend, under the displacement stroke of the actuation assembly, to a different width than those of the first set. Thus, the second set of impression-forming elements is arranged to extend to a different width than the first set, under a given actuation distance. During actual use, the

apparatus need not necessarily use precisely the same stroke displacement with the first and second sets of impression-forming elements, but in preferred embodiments the displacement stroke during use of the first set of impression-forming elements is the same as the

displacement stroke during use of the second set of impression-forming elements.

Each set of impression-forming elements may comprise a plurality, and more preferably a multiplicity, of impression-forming elements. Each impression-forming element may comprise a plate for abutment against the side of the foundation excavation. Each impression forming element may comprise at least one protrusion extending from the plate to create the impression in the side of the foundation excavation. Each impression forming element may comprise at plurality or a

multiplicity of protrusions extending from the plate to create the impression in the side of the foundation excavation. The plate is preferably for abutment against the side of the foundation excavation. In some

embodiments, the plate may be relatively thin to avoid excess weight, but it need not necessarily be so. For example, in some embodiments, the plate may comprise a relatively thick structure.

Each of the second set of impression-forming

elements may further comprise a support arm for

connecting the plate to the apparatus. The length of the support arm may enable the second set to operate at a different width than the first set of impression-forming elements. The support arm on the second set of

impression-forming elements may be a different length, for example longer, than a corresponding support arm on each of the impression-forming elements in the first set of impression-forming elements

In some embodiments of the invention, the second set of impression-forming elements may be retrofittable to replace the first set of impression-forming elements.

For example, the first set of impression-forming elements may be releasably connected to the apparatus such that they can be removed and replaced by the second set. The second set, may, for example, have a longer support arm to enable them to extend at a greater width. The second set of impression-forming elements may be releasably connected to the apparatus such that they can be removed and replaced by the first set for subsequent operations. Providing a detacheable connection, preferably

repeatably detachable and re-attachable, enables the apparatus to be repeatedly assembled, disassembled and reassembled, for example for different diameter bores.

In other embodiments, the second set of impression forming elements may be adapted to be fitted on top of the first set. For example, the first set of elements may remain in place when the second set of elements is fitted to the apparatus. The second set of elements may be releasably connected to the first set of elements.

Such an arrangement has been found to be beneficial because it does not require any changes to the interface between the actuation assembly and the first set of impression-forming elements.

Embodiments of the invention may be applicable to any foundation excavation. The foundation excavation may be a trench. More preferably the foundation excavation is a bore for piling. In embodiments in which the foundation excavation is a bore, references to the

'width' of the excavation will be understood to be directly transferable to 'diameter' of the bore. For example, the first set of impression-forming elements may be for use in a first diameter bore, and the second set of impression-forming elements may be for use in a second, different, diameter bore. Furthermore,

references to the groundworks apparatus may be

interchangeable with a 'piling apparatus' .

The present invention has been found to be

especially beneficial with respect to piling activities, because in such an arrangement the displacement of the actuation assembly tends to be limited by the diameter of the bore. For example when using hydraulic rams, the rams tend to extend across the diameter of the bore, so the maximum displacement tends to be limited to no more than that diameter. Using differently sized sets of impression forming elements has been found to be

especially attractive with such an arrangement.

In embodiments for bores, the plate of each

impression-forming element may be curved in an arc. The plates of the impression-forming elements of the first set may be curved in the arc of a first diameter circle. The plates of the impression-forming elements of the second set may be curved in the arc of a second diameter circle, the second diameter being different than the first diameter. The plates may be curved in an arc to substantially match the curvature of the bore into which they are configured to be inserted. Such an arrangement is beneficial in ensuring relatively uniform contact between the plate and the side of the bore; this may assist in the formation of a well-formed impression in the side of the bore.

In apparatus for use in a bore, the plurality of the impression-forming elements may be circumferentially spaced around the apparatus. The plates may be shaped such that the arcs lie along a circumference of a common circle. The plates may be arranged substantially end-to- end, and/or may lie along a circumference of a common circle, when the set of impression-forming elements are in the retracted configuration. It will be appreciated that in such an arrangement the curvature of the plates will not exactly match the curvature of the bore (given that would be a slightly larger diameter) . Nevertheless, the difference is typically sufficiently small not to cause a problem (or can be dealt with by using longer protrusions on some parts of the plate, to offset any spacing differences) .

In apparatus for use in a non-circular excavation (for example a trench) the impression-forming elements may be located on opposing sides of the apparatus.

The kit of parts may comprise a third set of

impression-forming elements. The third set of

impression-forming elements may be configured for

operation in a different-width foundation excavation than the second and first sets, such that, when fitted onto the apparatus, the third set of impression-forming elements extend, under the displacement stroke of the actuation assembly, to a different width than those of the second and first sets. The kit of parts may comprise one or more further sets of impression-forming elements, each being configured for operation in a progressively wider foundation excavation. In this manner, the kit of parts may provide an apparatus having a comprehensive suite of impression-forming elements that allow the apparatus to be used in a wide range of foundation excavations .

The actuation assembly may be hydraulically powered. In such embodiments, the apparatus may comprise a

manifold for receiving a hydraulic feed. The hydraulic feed is preferably an external feed. The actuation assembly may comprise a set of hydraulic jacks. Each hydraulic jack may be associated with an impression forming element in the set.

The actuation assembly may be electrically powered. In some embodiments, the apparatus may comprise an electrical power module. The electrical power module may comprise batteries. The actuation assembly is configured to move the first set of impression-forming elements by the

displacement stroke. The actuation assembly may take a number of forms. For example, in some embodiments the actuation assembly may comprise a hydraulic jack. For example, in some other embodiments the actuation assembly may comprise a mechanical linkage, such as a scissor mechanism.

The second set of impression-forming elements is preferably configured for operation in a wider foundation excavation than the first set. When fitted onto the apparatus, the second set of impression-forming elements may extend, under the displacement stroke of the

actuation assembly, to a greater width than those of the first set. For these embodiments, it will be appreciated that references herein to 'a different-width' or

corresponding terminology on other features, can be replaced by wider/greater etc. as required.

According to another aspect of the invention there is provided a piling apparatus for insertion into a bore, the piling apparatus comprising: an actuation assembly; and a first set of impression-forming elements mounted for movement by the actuation assembly, the first set of impression-forming elements being moveable by a

displacement stroke of the actuation assembly between a retracted configuration in which the impression-forming elements are retracted such that the apparatus can move along the bore, and an extended configuration in which the impression-forming elements extend outwards to create an impression in the side of the bore; and wherein the apparatus is configured to receive a second set of impression-forming elements for fitting onto the piling apparatus to move between a retracted and an extended configuration, the second set of impression-forming elements being configured for operation in a different- dimeter bore than the first set, such that, when fitted onto the apparatus, the second set of impression-forming elements extend, under the displacement stroke of the actuation assembly, to a different diameter than those of the first set.

It will be understood by the skilled person that the displacement stroke preferably refers to the movement of the actuation assembly from the stowed position (for example where the assembly occupies its minimum

diameter), to an extended position, (for example where the assembly occupies its maximum diameter as configured at that moment) . It is therefore understood that for the same displacement stroke of the apparatus, when the second set of impression forming elements is fitted onto the first set of impression forming elements of the apparatus, different minimum and maximum diameters of the apparatus are achieved. It will also be appreciated that the displacement stroke is not limited to the stroke of a hydraulic jack or alike - for example the 'stroke' will be understood to equally apply to the displacement of other actuation assemblies such as mechanical linkage arrangements .

The apparatus may comprise an interface at which the second set of impression-forming elements may be

detachably connected.

According to another aspect of the invention there is provided a piling apparatus for insertion into a bore, the piling apparatus comprising: an actuation assembly; a first set of impression-forming elements mounted for movement by the actuation assembly, the first set of impression-forming elements, moveable by a displacement stroke of the actuation assembly between a retracted configuration, and an extended configuration; and a second set of impression-forming elements fitted onto the first set, the second set being moveable between a retracted configuration in which the impression-forming elements of the second set are retracted such that the apparatus can move along the bore, and an extended configuration in which the impression-forming elements of the second set extend outwards to create an impression in the side of the bore beyond the reach of the first set of elements .

The first and second sets of impression-forming elements may be concentrically mounted on the apparatus. The first set of elements may comprise an interface at which the second set of impression-forming elements may be detachably connected.

According to another aspect of the invention there is provided a piling apparatus for use in a bore, the piling apparatus comprising: an actuation assembly; an interface for receiving a plurality of different sets of impression-forming elements, each set being suitable for a different diameter bore; and each of the sets of impression-forming elements being configured to be actuatable by the actuation assembly between a retracted configuration in which the impression-forming elements are retracted such that the apparatus can move along the bore, and an extended configuration in which the

impression-forming elements extend outwards to create an impression in the side of the bore.

Providing the apparatus with an interface for receiving a plurality of different sets of impression forming elements enables the same 'base' apparatus to be used in a number of differently sized foundation excavations. The same 'base' apparatus can therefore be used for numerous different projects, with differently sized excavations.

According to another aspect of the invention there is provided a method of creating impressions in the side of a bore using a piling apparatus, the method comprising the steps of: assessing the diameter of the bore;

selecting a set of impression-forming elements, from a plurality of different sets of impression-forming

elements, for fitting to the piling apparatus such that it is operable to create impressions in that diameter of bore; fitting the set of impression-forming elements to the piling apparatus; inserting the apparatus into the bore with the set of impression-forming elements in a retracted configuration; and actuating the set of impression-forming elements into an extended

configuration in which the impression-forming elements extend outwards to create an impression in the side of the bore.

In some embodiments, the method may comprise the step of fitting a second set of impression-forming elements onto to the piling apparatus, without

necessarily removing a first set of impression-forming elements. In some embodiments, the step of fitting the set of impression-forming elements (for example the second set) may comprise the preceding step of removing a different set of impression-forming elements (for example the first set) .

According to another aspect of the invention there is provided a method of modifying a piling apparatus comprising the steps of: selecting, from a plurality of different sets of impression-forming elements, a set of impression-forming elements for fitting to the piling apparatus such that it is operable to create impressions in a bore having a first diameter; fitting the selected set of impression-forming elements to the piling

apparatus .

According to another aspect of the invention, there is provided a substantially cylindrical, elongate, piling apparatus for insertion into a bore. The piling

apparatus comprises: an actuation assembly; and a first set of indentation-forming elements mounted for movement by the actuation assembly. The first set of indentation forming elements comprises: a linear support arm; and an arcuate indentation-forming plate, the plate being fixably connected to the linear support arm. The first set of indentation-forming elements are moveable by a displacement stroke of the actuation assembly between a retracted configuration such that the apparatus can move along the bore, and an extended configuration in which the indentation-forming elements extend outwards to create an indentation pattern in the side of the bore.

An interface is located on the first set of indentation elements for receiving a plurality of different sets of indentation-forming elements, each set comprising a plate of a different radius of curvature to be suitable for use in a different diameter bore.

It will of course be appreciated that features described in relation to one aspect of the present invention may be incorporated into other aspects of the present invention. For example, the methods of the invention may incorporate any or all of the features described with reference to the apparatus of the

invention and vice versa. Furthermore, any features described with reference to the kit of parts may equally be applicable to aspects of other apparatus and/or methods of the invention. Yet further, any references to features in the groundworks apparatus for use in a foundation excavation, are applicable to the more

specific embodiment of the piling apparatus for use in a bore (and vice versa) .

Description of the Drawings

Embodiments of the present invention will now be described by way of example only with reference to the accompanying schematic drawings of which:

Figures la-ld show schematic side views of an

apparatus according to a first embodiment, forming impressions in a pile bore;

Figure 2a is a longitudinal part of the apparatus in Figures la-ld;

Figure 2b is an axial section view through the part of Figure 2a;

Figure 3a illustrates the arrangement in Figure 2a but with a second impression-forming element attached;

Figure 4 shows the apparatus of the first embodiment with a third impression-forming element fitted

Figures 5a and 5b show impression-forming elements within two different sets of impression forming elements, in a kit of parts according to a second embodiment of the invention;

Figure 6 shows a longitudinal section view of the apparatus of the second embodiment;

Figure 7 shows a perspective view of the apparatus of the second embodiment with no impression forming elements fitted; Figures 8a to 8c show the different diameters of the apparatus when different sets of impression forming elements are fitted according to the second embodiment.

Detailed Description

The invention will be more fully understood and further advantages will become apparent when reference is made to the following detailed description of embodiments of the invention, wherein like reference numerals denote similar elements.

Figures la to Id schematically show an apparatus and method of forming impressions in pile bores, according to a first embodiment of the invention. A bore 4 was first created using a Kelly Bar fitted with an auger.

In the arrangement in Figure la, the impression forming apparatus 1 is connected to a rig 3, which is arranged to lower the impression-forming apparatus 1 in to the pile bore 4 (a longitudinal part 101 of the piling apparatus is indicated for further detailed description below) .

Figure lb shows the impression-forming apparatus 1 in its descent into the pile bore 4. Figure lc shows the impression-forming apparatus 1 undergoing radial

expansion within the pile bore 4, pressing against the bore wall 2, forming impressions 2a. The apparatus 1 of Figure lc has a plurality of vertically spaced radially extending rams. For deeper bores, it may be necessary to sequentially translate the apparatus in a vertical direction to create a plurality of impressions 2a in the bore wall 2. Although Figures la-lc show the apparatus being lowered using a piling rig, it is also possible to lower the apparatus in other ways, such as suspending the apparatus on a cable held by a crane.

Figure 2a shows a longitudinal part of a piling apparatus 101 in more detail, and reference is now made to that illustration (it will be appreciated that the characteristics of this part are repeated along the length of the apparatus) . In general terms, the

apparatus comprises a cylindrical housing 110 containing actuation assembly 102. A first set of impression forming elements 104 is mounted on the apparatus for movement by the actuation assembly 102 between a

retracted and extended configuration (discussed in more detail below) . For the sake of clarity, Figure 2a only shows a single impression-forming element 104, but in practice there are a total of four impression-forming elements, equally spaced around the circumference of the apparatus (i.e. spaced apart by 90 degrees in this embodiment) . In Figure 2a, it can be seen that the other three impression-forming elements 104 (not shown) could be attached to the exposed, free, rams 107. All the impression-forming elements 104 together form a first set of elements.

The longitudinal section of the apparatus shown in Figure 2a is part of a longer cylindrical string 1 forming the piling apparatus, as shown in figures la to Id. Accordingly, the apparatus also comprises other impression-forming elements, within the first set, located longitudinally above and below the part of the apparatus shown in Figure 2a.

Each of the impression-forming elements in the first set 104 comprises an arcuate plate 104c, having a curvature centred on the longitudinal axis 111 (labelled in figure 2b) of the apparatus. The arcuate plate 104c has several impression nodules 104b extending therefrom.

The actuation assembly 102 is housed within the cylindrical housing 110 and comprises a multiplicity of perpendicularly orientated hydraulic rams stacked in alternating layers along the length of the apparatus.

Each ram protrudes, in its retracted state, slightly beyond the housing, but is extendable radially outwards (discussed in more detail below) by a displacement stroke .

In accordance with typical piling methods, the piling apparatus 101 of the first embodiment of the invention would be attached, during use, to a cable or Kelly bar and lowered into a bore (for example from a crane or piling apparatus respectively) .

Figure 2b is a sectional-plan view of the apparatus 101 during use in such a bore. The apparatus 101 has been lowered with the rams in the actuation assembly 102 retracted such that the impression-forming elements 104 are in a retracted configuration such that the plates 104c are substantially end-to-end around the

circumference of the apparatus. In this configuration the radius Ra of the apparatus is slightly less than the radius Rb of the bore. The apparatus can therefore be readily inserted into the bore.

In the first embodiment of the invention, the first set of elements 104 is moveable from this retracted configuration into an extended configuration, shown in dashed lines of the right-hand side of Figure lb.

In the extended configuration, the hydraulic rams in the actuation assembly 102 are extended to push the impression-forming elements 104 radially outwards by a displacement stroke DS . In doing so, the outer surface of the plate 104c moves to the radius Rb of the bore and abuts the side wall of the bore. The curvature of the plate 104c is such that the plate creates a tight fit against the side wall of the bore, and the nodules 104b create impressions in the side of the bore by virtue of them protruding beyond the plate. This process occurs around the circumference and the length of the apparatus 101 such that the sides of the bore are populated with numerous indentations.

When the apparatus is removed and the concrete is then cast in the bore, it occupies the volume of the impressions. This is thought to improve the strength of the piling by increasing the skin friction at the bore wall to create a larger pull out resistance and/or by providing a piling structure that better reacts loads into the ground.

Broadly speaking, similar impression-forming

functionality as that described above is provided in some prior art assemblies such as US 5908268 and WO2014059537. However, a problem with these arrangements is that they can only be used in essentially one diameter of bore. Embodiments of the present invention seek to provide an improved apparatus .

In the first embodiment of the invention, there is a kit of parts comprising a second set of impression forming elements for fitting onto the apparatus. Figure 3 is a perspective view of the part of the piling

apparatus in Figure 2a, but with an impression-forming element 105 from the second set of elements fitted onto it .

For the sake of clarity, only one element 105 from the second set is shown, but in practice a respective second impression-forming element 105 is stacked on top of each and every one of the first set of impression forming elements 104 on the apparatus 101. All the second impression-forming elements 104, together form the second set of impression-forming elements.

Each of the second impression-forming elements 105 comprises an arcuate plate 105c, having a curvature centred on the longitudinal axis 111 of the apparatus.

The arcuate plate 105c has several impression nodules 105b extending therefrom.

Importantly, each of the second impression-forming elements also comprises a pair of spacer arms 105a extending radially out from the rear of the plate. The spacer arms are arranged for detachable connection onto the plate of the first impression-forming element via a sleeve. The spacer arms 105a comprise a male connecting portion that fits into a female connecting portion 104d, which is attached to the first impression forming

element. To detachably secure the spacer arm to the female connecting portion, a pin or bolt may be secured through the hole common to both the spacer arm and the female connecting portion. This connection is shown in Figure 3 (and also in Figure 2b for the connection between the ram and the first impression forming element 104) . It will be appreciated by the skilled person that the male and female portions may be the other way around, that is to say that the second impression-forming element may have a pair of spacer arms extending radially out from the rear of the plate that have the female

connection, and the first impression forming element may have a male connecting portion. Furthermore, the skilled person will also appreciate that the female connecting portion 104d as shown in figure 3 is not to scale, and that in some embodiments the impression forming nodules 104b and 105b may protrude further from the arcuate plate (104 and 105 respectively) than the female connecting portion 104d. The spacer arms effectively create a radial extension of 5R to the radius of the apparatus. Correspondingly, the curvature of the arcuate plate 105 is lower (i.e. it has a greater radius of curvature) than the curvature of the plate 104c in the first impression forming element 104, such that the curvature of the plate 105 substantially matches the curvature of an increased diameter bore on which the apparatus is to be used.

During use, the rams of the actuation assembly 102 are extended by their displacement stroke DS in the same manner as described with reference to Figure 2b.

However, since the second set of impression-forming elements 105 has been attached onto the apparatus, this movement results in displacement of the second elements to a greater radius than that of the first elements. In other words, by the addition of the second set of impression-forming elements 105, the apparatus 101 has been configured for use in a larger diameter bore.

Such an arrangement has been found to be beneficial because the apparatus of the first embodiment of the invention can then be used in two different diameter bores and does not need to be bespoke to a specific proj ect .

Since the second set of impression-forming elements 105 are detachably connected to the first set, the apparatus can later be reconfigured back for use in a smaller diameter bore. In addition, the first embodiment of the invention provides a kit of parts comprising yet more sets of impression-forming elements that are

suitable for attachment onto the apparatus for use in even larger diameter bores. Such an arrangement is illustrated in Figure 4.

The upper image in Figure 4 shows the apparatus with a third impression-forming element 106 fitted (only one being shown for clarity) . The third impression-forming element 106 is similar to the second 105 in that it comprises a corresponding arcuate plate 106c, nodules 106b and support arms 106a. The support arms are

detachably connected to the second plate (which is in turn attached to the first set) .

As best illustrated in the lower image of Figure 4, the first set of impression-forming elements 104 enables the apparatus to be operable in a bore of radius rl .

However, due to the limited reach of the actuation assembly the apparatus is not suitable in meaningfully larger radius bores. Adding the second set of elements

105, enables the apparatus to be operable in a bore of a greater radius r2. Due to the extra size, it is then no longer possible for use in a smaller bore of radius rl, and due to the limited reach of the actuation assembly the apparatus is not suitable in meaningfully larger radius bores than r2. Adding the third set of elements

106, enables the apparatus to be operable in a bore of an even greater radius r3. Due to the extra size, it is then no longer possible for use in a smaller bores of radii rl or r2 though.

The present invention therefore provides a flexible piling apparatus, for forming impressions in the sides of the bore that can be selectively used in differently diameter bores.

It will be appreciated that in further embodiments of the invention (not shown) , there may one or more additional layers of impression-forming elements, the number selected such that the apparatus can extend, with the elements in the extended configuration, to contact the wall of the bore and form impressions therein.

Figures 5a and 5b show impression-forming elements within two different sets of elements, in a kit of parts according to a second embodiment of the invention. The first set (Figure 5a) is for a small diameter bore, and the second set (figure 5b) is for a larger diameter bore.

The structure of the elements is broadly similar to the first embodiments (in that each comprises a curved plate 204c, 205c, support arms 204a, 205a, and

protrusions 204b, 205b (not shown in Figures 5a/5b but shown in Figure 6) . However, in the second embodiment of the invention, the second set is designed to replace the first set as a retrofit, rather than be fitted onto them, as will now be explained with reference to Figures 6 and 7.

Figure 6 shows the apparatus 201 with one of the first impression-forming elements 204 mounted onto it.

The support arms 204a are received in a releasably lockable connection to the end of the rams of the

actuation assembly 202. More specifically, the rams' connection interface 207 form a sleeve over the end of the support arms 204a and are held in place by a bolted connection. Such a configuration is like that shown in figure 2b.

The connection interface 207 at the end of the rams is configured to also receive the (longer) support arms of the second impression-forming element 205 in place of the arms of the first elements 204. Thus, the first element 204 can be unbolted and removed, and replaced by the second impression-forming element 205 to prepare the piling apparatus for use in a larger diameter bore. In this respect the apparatus in the second embodiment includes a core unit, without any impression-forming elements, but comprising the cylindrical housing 210 and the actuation apparatus 202 having connection interfaces 207. The connection interfaces 207 are in the form of the relatively narrow female connectors with suitable bolt holes for locking once the (male) sleeve connectors on the ends of the support arms are received on them.

This core unit, shown in Figure 7, can be used with a wide variety of impression-forming elements depending on the size of the bore required for a given project.

Figures 8a to 8c show the apparatus in the second embodiment with three different impression-forming elements 204, 205, 206 fitted. Each of the impression forming elements comprises a rearward pair of support arms 204a, 205a, and 206a that are all adapted to attach to the interface 207 on the end of the rams in the actuation assembly 202. As readily identifiable in

Figures 8a to 8c, the curvature of the plates in each impression-forming element is centred on the longitudinal axis of the apparatus and is commensurate with their spacing from it, such that they create a snug fit against the sides of the bore.

According to another embodiment (not shown) there is provided a groundworks apparatus for use in a trench.

The apparatus is similar to the above-described

embodiments except that it is configured for different width trenches. The kit of parts therefore comprises a series of different width impression forming elements that are selectively attachable onto the apparatus depending on the width of the trench excavation. Where in the foregoing description, integers or elements are mentioned which have known, obvious or foreseeable equivalents, then such equivalents are herein incorporated as if individually set forth. Reference should be made to the claims for determining the true scope of the present invention, which should be construed so as to encompass any such equivalents. It will also be appreciated by the reader that integers or features of the invention that are described as preferable,

advantageous, convenient or the like are optional and do not limit the scope of the independent claims. Moreover, it is to be understood that such optional integers or features, whilst of possible benefit in some embodiments of the invention, may not be desirable, and may therefore be absent, in other embodiments.