BACKGROUND OF THE INVENTION

[0001] The present invention concerns caps for piles. More particularly, but not exclusively, this invention concerns a cap for connecting to a pile within a bore. The invention also concerns a pile assembly. The invention also concerns a foundation system. The present invention also concerns a method of assembling a pile.

[0002] Hollow piles for use in construction are known per se. WO 2008/047161 discloses a method for making a hollow pile, by filling a bore with uncast concrete, and inserting a cavity forming means within the bore.

[0003] One problem that is associated with such piles is that when they are being manufactured, they can end up at differing heights. A time-consuming correction process then has to be employed to correct any height differences.

[0004] A further problem more specifically related to hollow piles occurs when the hollow pile is used for temperature control (e.g. having piping entering and leaving the hollow pile (used to transport heat to and from the pile)). In this arrangement, the piping may be exposed at the top of the pile and may be vulnerable to damage from the surroundings and from constructions thereupon.

[0005] The present invention seeks to mitigate the above-mentioned problems. Alternatively or additionally, the present invention seeks to provide an improved pile cap.

SUMMARY OF THE INVENTION

[0006] The present invention provides, according to a first aspect, a pile assembly located within a bore. The pile assembly comprises a pile and a cap located on top of the pile. The pile is a hollow pile and comprises a pile wall surrounding a cavity, to define a hollow interior of the pile. The cap comprises a top portion and a base portion below the top portion. The base portion is connected to the top of the pile wall, such that the cap encloses the top of the cavity. The base portion comprises a fluid inlet and a fluid outlet for conveying heat exchanging fluid, such that heat exchanging fluid can circulate around a heat exchanging loop in the cavity and/or in the pile wall, to exchange heat with a thermal medium within the cavity and/or with the pile wall. The heat exchanging fluid enters the base portion of the cap through the fluid inlet and exits the base portion of the cap through the fluid outlet.

[0007] The heat exchanging loop may be in the cavity. The heat exchanging loop may be in the pile wall. The assembly may comprise heat exchanging loops both in the cavity and in the pile wall. This this case, the pile cap may comprise fluid inlets and fluid outlets to each of these respective loops.

[0008] In the context herein, the term ‘loop’ is used with reference to any system in which the heat exchanging fluid may circulate. For example, the loop may be formed from a loop-shaped layout of pipe, as well as more complex circulatory layouts such as a Rygan system.

[0009] The pile wall may be an annular wall. The pile wall may be a concrete annular wall. The internal diameter of the pile wall may be at least 50%, optionally at least 60%, optionally at least 70%, optionally at least 80% and optionally at least 90% of the external diameter of the pile wall.

[0010] The provision of a cap having a fluid inlet and a fluid outlet means that the cap can be configured to protect pipework that is arranged to enter the cap (and thereby enter the pile when the cap is connected to the pile). Embodiments of the invention have been found to be especially beneficial because the inlet and outlet are on the base portion, below a top portion. Thus, the top portion may be arranged to protect the fluid inlet and outlet from above.

[0011] In addition, the provision of a cap may allow the construction of a cap of particular, and preferably more precise, dimensions, especially height dimensions. The choice of cap can be used to add a predetermined amount of height to the pile. By choosing caps of particular dimensions, it is possible to ensure that all of the piles within a potential building construction are all at the same height/level. [0012] The fluid inlet may be configured to engage with an inlet pipe. The inlet pipe may be arranged to supply fluid into the fluid inlet of the cap.

[0013] The fluid inlet may comprise a sleeve. The fluid inlet may comprise a bushing. The fluid inlet may comprise a thread. The thread may be configured to engage with a corresponding thread on the inlet pipe.

[0014] Having the fluid inlet configured to engage with an inlet pipe means that the pipe can be protected by the cap. In embodiments, having the inlet pipe engaging with the inlet (via a bushing for example) means that it is not necessary to feed the pipe through the cap, rather the cap includes its own short section of pipe within the fluid inlet. This reduces the need to do additional sealing of the inlet pipe to the cap. This also puts a break between the pipe within the cap (and pile) and the inlet pipe, which improves flexibility and robustness.

[0015] The fluid outlet may be configured to engage with an outlet pipe. The outlet pipe may be arranged to carry fluid away from the fluid outlet of the cap.

[0016] The fluid outlet may comprise a sleeve. The fluid outlet may comprise a bushing. The fluid outlet may comprise a thread. The thread may be configured to engage with a corresponding thread on the outlet pipe.

[0017] Similar to above, having the fluid outlet configured to engage with an outlet pipe may enhance the protection of the outlet pipework, while improving the flexibility and robustness of the pipe.

[0018] Either or both of the fluid inlet and/or outlet may comprise a sleeve for engagement with the respective inlet/outlet pipe, such that fluid can flow through the inlet and/or outlet pipe, through the sleeve and/or sleeves.

[0019] The use of a sleeve enables a tight fit with the respective inlet/outlet pipes, enabling a conduit through which heat exchanging fluid can flow in/out of the cap. The sleeve itself may at least partially act as a conduit, with respective pipes engaging with either end of the sleeve. [0020] The base portion of the cap may comprise a plurality of fluid inlets. The base portion may comprise a plurality of fluid outlets. Reference herein to features of a fluid inlet/outlet may be applicable to other fluid inlet/outlets on the pile cap.

[0021] The top portion may form an integral part of the pile cap, with the base portion.

[0022] The top portion may be attachable to the base portion. Once attached to the base portion, the top portion may be fixed to the base portion.

[0023] Alternatively or additionally, the top portion may be detachable from the base portion.

[0024] A detachable top portion means that access can be gained to the pipework located within the cap, without having to remove the entire cap. This may improve the reusability of the piles. Enhanced reusability is beneficial when a building is demolished, as the piles may still be able to be reused when a subsequent building is constructed thereupon. It may also save time when checking/maintaining the internal pipework, if only the top portion has to be detached, rather than the entire pile cap (which also entails detaching pipework, etc.)

[0025] Alternatively, or additionally, the detachable top portion may enable bespoke thicknesses of top portions to be used, which can be used to ensure that the relative heights of multiple pile assemblies within a foundation system are the same. The detachable top portion also closes off the top of the pile, protecting the internal pipework from load and damage.

[0026] The cap may be chosen from a set of caps, the thickness of each cap (measured along a direction parallel to the longitudinal axis of the pile assembly) being mutually different. The pile assembly may comprise a spacer, optionally located above the cap or between the cap and the pile wall. If the pile assembly comprises a plurality of pre-formed pile sections that are used to form the pile, then a spacer may be located between two pre-formed pile sections. The spacer may be used so that the top of the pile assembly is at a desired height. The spacer may optionally be chosen from a set of spacers, the thickness of the spacers being mutually different from one another.

[0027] The cap, when in place, may be substantially below ground level, for example, up to 10.0m below ground level, optionally up to 8.0m below ground level, optionally up to 6.0m below ground level and optionally up to 4.0m below ground level. The cap, when in place, may be at least from 0.5m below ground level, optionally at least 1.0m below ground level, optionally at least 2.0m below ground level and optionally at least 3.0m below ground level.

[0028] The depth of the cap below ground level may optionally depend on the diameter of the pile. For example, if a pile is narrow, then the depth of the cap below ground level may be lower than if the pile is wide.

[0029] In some embodiments, some or all of the top portion may be raised above the floor level. The top portion may comprise a channel for accessing the base portion. In some embodiments, the base portion may be open-toped, to allow access into the cavity of the pile (via the top portion). The channel in the top portion may allow access to the cavity, through the open-toped bottom portion.

[0030] The top portion may have a common central axis with the cap, when the top portion is attached to the cap.

[0031] The top portion may have substantially the same axis of symmetry as the remainder of the cap when the top portion is attached to the cap. The top portion may have substantially the same perimeter shape as the cap, when viewed in plan view. [0032] The top portion may cover substantially the whole upper surface of the base portion, when the top portion is attached to the base portion. Substantially the whole upper surface of the base portion may refer to at least 90% of the upper surface of the base portion. The top portion may cover more than the upper surface of the base portion. The top portion may extend over the edge of the upper surface of the base portion.

[0033] The top portion may be keyed to align with a corresponding key on the base portion. The top portion may comprise an alignment portion for alignment with the base portion. The base portion may comprise an alignment portion for alignment with the hollow pile.

[0034] Having an alignment portion for alignment ensures that the top portion is in the correct position. It also prevents the top portion from moving relative to the base portion once it is attached and in position. Both the top portion and the base portion may have alignment portions for alignment with each other and/or the pile (i.e. those features are not necessarily mutually exclusive).

[0035] The assembly may comprise a plurality of reinforcement members extending vertically within the pile wall. The base portion of the cap may comprise a plurality of openings, through which the reinforcement members are received. The top portion of the cap may comprise a plurality of openings, through which the reinforcement members are received. Each reinforcement member may pass through the pile wall, the base portion, and the top portion. The alignment portion may comprise the reinforcement members. The reinforcement members may be prestressed strands.

[0036] The fluid inlet may be located on a first side of the base portion. The fluid outlet may be located on a second side of the base portion. The first and second sides may be opposite each other. The base portion may be cuboidal in shape.

[0037] The base portion may comprise a plurality of valves. Each valve may be in fluid connection with the inlet and outlet respectively.

[0038] The use of valves enables control of any fluid that is entering and leaving the cap. The valves are also able to fluidly isolate the cap (and pile), such that maintenance can be performed on the pipework in and around the cap.

[0039] As mentioned above, the pile is a hollow pile and comprises a pile wall surrounding a cavity, to define a hollow interior of the pile. A plurality of pre-formed pile sections may form the pile wall. The pile sections may be tubes.

[0040] The pile sections may be formed from any type of cementitious material, such as concrete, for example pre-cast concrete. Use of pre-cast concrete has the advantage that the pile sections (or the section components) can be manufactured remotely from the site of the bore and then transported to the bore for use. Manufacturing the pile sections (or the section components) as pre-cast concrete, before their use in the bore, has the advantages of a) better quality assurance in a controlled environment, b) greater precision, and c) the opportunity to create bespoke surface qualities and that quality checks can be carried out on them before their installation in the ground. The pile sections may be reinforced concrete. At least two of the pile sections may have mutual ly-different lengths (length being measured along the longitudinal axis of the pile section). The use of different lengths of pile section facilitates the construction of a pile the height of which may be tailored to take into account the actual depth of the bore. Typically, a bore may be slightly (250- 500mm) deeper than intended. It is therefore useful to have available pile sections of different lengths.

[0041] Optionally one, optionally more than one, and optionally each, of the pre formed pile sections may comprise a wall portion that forms the pile wall.

[0042] The cap may be provided with one or more cap tensioning member channels for receiving a tensioning member, which may be used to draw the pile together. The cap tensioning member channels may be formed in a surface of the cap, for example, in an outer surface of the cap so that the tensioning members may extend around the cap. Alternatively or additionally, tensioning member channels may extend through the cap. For example, base tensioning member channels may comprise bores formed through the cap. The cap may be substantially cylindrical. The cap may be temporary or may be permanent.

[0043] The cap may be provided on an upper surface with a configuration for mating with a corresponding configuration provided on a tensioning jack. The upper surface of the cap may be provided with a female configuration (such as a recess) for mating with a corresponding male configuration provided on a tensioning jack. The cap may be provided with multiple such configurations.

[0044] The pile assembly optionally comprises a bottom portion below the pile wall. The bottom portion may be pre-formed e.g. pre-cast, and may comprise cementitious material, such as concrete. The bottom portion may have been formed in situ (e.g. by casting in situ). The bottom portion may be provided with one or more (for example, two) lugs for handling the pile section. Such lifting lugs may be used to lower and raise the bottom portion. Such lifting lugs may be provided with an aperture. The aperture may be used to receive a lifting hook, cable or the like to assist in lowering and/or raising the pile section. Such lifting lugs may be provided at, or proximate, the top of the bottom. The bottom portion may comprise one or more transport channels configured to allow the transport of a curable liquid material. Such channels may be configured to receive a curable liquid material from channels provided in an adjacent pile section. The bottom portion may comprise one or more outlet channels configured to convey a curable liquid material from a transport channel to an outlet. A curable liquid material may then be delivered to a space between the bore and the bottom portion of the pile assembly.

[0045] The pile cap may be provided with a reservoir for the storage of liquid grout. The pile cap may be provided with one or more grout conveying channels in fluid communication with the reservoir for the storage of grout. Optionally, at least one, optionally more than one and optionally each grout conveying channel may extend from the reservoir for the storage of grout to an outer portion of the pile cap, and optionally along an outer, circumferential surface of the pile cap. At least one, optionally more than one and optionally each grout conveying channel may be in fluid communication with respective liquid conveying channels in the wall of the pile. The pile cap may provide a suitable reservoir for grout or other such curable liquid that may be used with the pile. Without wishing to be bound by theory, during the construction of a pile comprising pre-formed multiple pile section, a sleeve may be used to surround the pile as the pile is being constructed. Once the pile is complete, the sleeve may be withdrawn. The sleeve may help retain grout present in the reservoir. As the grout-retaining sleeve is withdrawn, grout leaves the reservoir under the action of gravity, and falls between the pile and the bore. [0046] The present invention provides, according to a second aspect, a hollow pile system. The hollow pile system comprises a hollow pile having a top end, a cap, and a heat exchange pipe within the hollow pile. The heat exchange pipe is fluidly connected to the cap. The cap comprises a top portion and a base portion below the top portion. The base portion is connected to the top of the hollow pile such that the cap encloses the top of the hollow pile. The base portion comprises a fluid inlet and a fluid outlet, such that heat exchanging fluid can enter the heat exchange pipe through the fluid inlet and exit the heat exchange pipe through the fluid outlet.

[0047] The present invention provides, according to a third aspect, a cap suitable for use as the cap in the hollow pile assembly according to the first aspect.

[0048] The cap may be arranged to be located on top of the hollow pile. The cap may comprise a top portion and a base portion below the top portion. The base portion may be configured to be connected to the top of the pile wall, such that the cap encloses the top of the cavity. The base portion may comprise a fluid inlet and a fluid outlet for conveying heat exchanging fluid, such that heat exchanging fluid can enter the base portion of the cap through the fluid inlet and exit the base portion of the cap through the fluid outlet.

[0049] The present invention provides, according to a fourth aspect, a foundation system. The foundation system comprises a plurality of hollow pile assemblies according to the first aspect. At least two of the pile assemblies are fluidly connected to each other within a fluid network.

[0050] The at least two pile assemblies may be connected in series. The at least two pile assemblies may be connected in parallel.

[0051] The present invention provides, according to a fifth aspect, a method of assembling a hollow pile assembly. The method comprises the steps of: connecting a cap to a hollow pile, the cap comprising a top portion, a base portion, a fluid inlet, and a fluid outlet; passing heat exchanging fluid into the cap through the fluid inlet; exchanging heat between the heat exchanging fluid and a thermal medium located within the hollow pile; and passing fluid out of the cap through the fluid outlet. The hollow pile may be made by assembling a plurality of pre-formed pile sections into a hollow pile. The method may comprise drawing the pre-formed pile sections together. The pre-formed pile sections may have one or more features described above in relation to the first aspect of the present invention. The tensioning members may have one or more of the features described above in relation to the first aspect of the present invention. A bottom portion may be provided, optionally below the hollow pile. The bottom portion may have one or more of the features described above in relation to the first aspect of the present invention. The method may comprise drawing the bottom portion against the hollow pile. The method may comprise drawing the hollow pile against the cap. The cap may have one or more of the features described above in relation to the first aspect of the present invention.

[0052] The bottom portion may comprise one or more bottom portion tensioning member channels for receiving a tensioning member, each tensioning member being received by a respective bottom portion tensioning member channel. The use of the bottom portion tensioning member channels facilitates the correct positioning of the tensioning members, subsequent pre-cast sections and any cap.

[0053] The bottom portion may be sealed to the adjacent pile section to inhibit fluid passage therepast.

[0054] The method may comprise providing the cap on the stack of a plurality of pile sections.

[0055] 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 method of the invention may incorporate any of the features described with reference to the apparatus of the invention and vice versa.

DESCRIPTION OF THE DRAWINGS

[0056] Embodiments of the present invention will now be described by way of example only with reference to the accompanying schematic drawings of which: [0057] Figure 1 shows a side sectional view of a pile cap in a pile assembly according to a first embodiment of the present invention;

[0058] Figure 2 shows a side sectional view of a pile cap in a pile assembly according to a second embodiment of the present invention;

[0059] Figure 3 shows a side sectional view of a pile cap in a pile assembly according to a third embodiment of the present invention;

[0060] Figure 4a shows a perspective view of a pile cap in a pile assembly according to a fourth embodiment of the present invention;

[0061] Figure 4b shows a plan view of a pile cap according to the fourth embodiment of the present invention;

[0062] Figure 5 shows a foundation system according to a fifth embodiment of the present invention;

[0063] Figure 6 shows a schematic side-on view of another embodiment of a foundation system and a pile assembly in accordance with the present invention;

[0064] Figure 7A shows a schematic side-on view of a top portion of another embodiment of a pile assembly in accordance with the present invention;

[0065] Figure 7B shows a schematic side-on view of a top portion of yet another embodiment of a pile assembly in accordance with the present invention;

[0066] Figure 8 shows a schematic side-on view of an embodiment of a pile assembly in accordance with the present invention; and

[0067] Figure 9 shows a schematic representation of an embodiment of a method in accordance with the present invention

DETAILED DESCRIPTION

[0068] Embodiments of the present invention will now be described by reference to the accompanying exemplary figures, wherein like reference numerals denote similar elements. It will be understood by the skilled person that any reference to a “pile cap” is the same as any reference to a “cap”. The terms “pile cap” and “cap” interchangeably denote the same feature. When the “top portion” is connected to the “pile cap”, the entire apparatus (“pile cap” and “top portion”) is referred to as the “pile cap”. The same is true when the “top portion” is detached from the “pile cap”, as the “top portion” is a feature of the “pile cap” itself.

[0069] Figure 1 shows a side sectional view of a pile cap 10 in a pile assembly 5 according to a first embodiment of the present invention.

[0070] The pile cap 10 is enclosed and sealed at its upper surface by a top portion 12. The top portion 12 is integral with the rest of the pile cap 10 and the base portion 11. On a first side 14 of the base portion 11 , there is provided an inlet 16. The inlet 16 is a fluid inlet 16. The fluid in the embodiment of Figure 1 is a heat exchange liquid, for example a water-based mix. Although it is not visible from this view, the pile cap 10 is substantially cylindrical in shape when viewed in plan view (looking directly down at the top, upper surface).

[0071] The pile assembly 5 also comprises the pile 22, which comprises a hollow cylinder of concrete. The concrete cylinder forms a hollow concrete tube 24. The tube 24 forms the wall of the pile (also known as the pile wall). The tube 24 is reinforced with steel bars 28 through its longitudinal axis, schematically shown in Figure 1. In reality, of course, the reinforcement bars 28 would not be discontinuous, and would span substantially the entire length of the pile 22. The reinforcement bars 28 protrude past the top of the pile 22, and into the cap 10, securing the cap 10 in position. The pile also includes lateral protrusions 26, which increases the frictional resistance of the pile 22 with respect to the surrounding soil, thereby increasing the load capacity. [0072] The pile 22 has a hollow cavity 29 within the inner surface of the tube 24. The cavity 29 is filled with a thermal medium. The thermal medium is a heat exchange medium. The heat exchange medium is water-based.

[0073] The fluid inlet 16 and fluid outlet 18 include sleeves for pipework to pass therein. Although not shown in the figure for ease of visual clarity, the inlet elbow pipe 37 is flush against the inner surface of the sleeve of the inlet 16, and the outlet elbow pipe 39 is flush against the inner surface of the sleeve of the outlet 18.

[0074] To secure the inlet pipe 36 to the inlet 16 of the cap 10, and to the inlet elbow pipe 37, a first inlet coupler 32 is provided. The outlet pipe 38 is secured to the outlet 18 of the cap 10, and to the outlet elbow pipe 39 by a first outlet coupler 34. The couplers 32, 34 are any suitable coupler that may be suitable to be used to connect two pipes together.

[0075] In embodiments of the present invention, the couplers are any suitable means of connecting two pipes together, such as sleeves, bushings, couplers (double female connection), nipples (double male connection), welds, or unions, or any combination of such suitable connections, including flexible connections, for example.

[0076] Each of the elbow pipes 37, 39 have an elbow joint within a hollow void 20 of the cap 10. The elbow joint of each of the elbow pipes 37, 39 changes the direction of each of the elbow pipes 37, 39 from a horizontal direction towards a downwards direction (relative to the pile 22 when it is in the ground).

[0077] The inlet elbow joint 37 at its downwards portion then connects to a second inlet coupler 35, at the exit of the void 20 of the cap 10. The second inlet coupler 35 is of any of the types listed above. The second inlet coupler 35 connects the inlet elbow pipe 37 to the inlet heat exchange pipe 40. The inlet heat exchange pipe 40 carries fluid downwards to perform heat exchange with the surrounding environment within the pile 22.

[0078] As cold water flows through the inlet heat exchange pipe 40, heat is exchanged from the relatively warmer environment in the cavity 29, to the water in the heat exchange pipe 40. The now warmed water passes through the outlet heat exchange pipe 42 towards the outlet elbow pipe 39. The outlet elbow joint 39, at its downwards portion, connects to a second outlet coupler 33, at the exit of the void 20 of the cap 10. The second outlet coupler 33 is of any of the aforementioned types listed above. The second outlet coupler 33 connects the outlet elbow pipe 39 to the outlet heat exchange pipe 42. The now warmed water then flows through the outlet elbow pipe, through the first outlet coupler 34, and through the outlet pipe 38.

[0079] In embodiments of the present disclosure, the heat exchange taking place within the cavity 29 may be to cool warmer incoming water through the inlet heat exchange pipe 40 (i.e. to remove heat from the incoming water), and provide cooler return water through the outlet heat exchange pipe 42.

[0080] Figure 2 shows a side sectional view of a pile cap 110 in a pile assembly according to a second embodiment of the present invention. Similar to the pile cap 10 of figure 1 , the pile cap 110 of figure 2 is enclosed and sealed at its upper surface by a top portion 112, which is integral with the pile cap 110. On a first side 114 of the base portion 111, there is provided an inlet 116. The pile cap 110 is cylindrical in shape. The outlet 118 is provided opposite the inlet 116.

[0081] For the sake of conciseness, features present in figure 2 that are similar to features found in the embodiment of figure 1 in appearance and function will not be described in detail. The features of the embodiment of figure 2 that are similar to features present in the embodiment of figure 1 will use the same reference numeral of the figure 1 embodiment, but prefixed by the numeral “1”. For example, the protrusions 126 of figure 2 are similar in appearance and function to the protrusions 26 of figure 1.

[0082] At the inlet 116, there is provided an inlet valve 150. The inlet valve 150 is an inlet geothermal valve 150. In addition to the inlet valve 150 connecting the inlet pipe 136 to the inlet heat exchange pipe 140, the inlet valve 150 also connects the inlet pipe 136 to the inlet geothermal pipe 154. The inlet geothermal pipe 151 is embedded in the annular wall of the pile and also acts as another means of improving the heat efficiency of the system.

[0083] Cooler water flows in through the inlet pipe 136, into the inlet 116 and through the valve 150. The cooler water then splits at the valve 150 and flows through both the inlet geothermal pipe 154 and the inlet heat exchange pipe 140. The water in the inlet heat exchange pipe receives heat from the relatively warmer environment within the cavity 129 of the pile 122. The cooler water within the geothermal inlet pipe 154 also receives heat from the relatively warmer environment within the pile wall 124 and the surrounding ground 160. The now warmed water then flows back through the outlet heat exchange pipe 142 and the outlet geothermal pipe 155, joining at the outlet geothermal valve 152 at the outlet 118, then flowing through the outlet 138.

[0084] In embodiments of the present invention, there is provided a ground source heat pump that generates additional heat (by extracting said heat from the surrounding ground 160) to be exchanged with the cooler water flowing through either or both of the inlet pipes 140, 154. The ground source heat pump may be located external to the pile, within the surrounding ground, having a fluid connection to the inlet pipes and/or the cavity of the pile such that heat can be exchanged.

[0085] In embodiments of the present invention, the environment within the pile cavity 129 is used as a heat sink. Excess heat may be generate by above-ground processes, such as air conditioning units, or generators for example. This excess heat is transferred into a heat exchange fluid, such as water for example, which is pumped through the inlet pipe into the pile. The relatively warm water transfers some of its heat to the relatively cooler environment within the cavity of the pile, to the pile wall itself, and to the surrounding ground. This means that the pile itself, the cavity, and the surrounding ground may be used to store excess heat to be used at a later time when relatively cooler water requires warming.

[0086] Figure 3 shows a side sectional view of a pile cap 210 in a pile assembly 205 according to a third embodiment of the present invention. Similar to the pile cap 10 of figure 1 , and the pile cap 110 of figure 2, the pile cap 210 of figure 3 is enclosed and sealed at its upper surface by a top portion 212. However, the top portion 212 has been attached separately to the base portion 211. The top portion 212 is detachable from the base portion 211, enabling access to the interior of the pile cap 210 and the pile 222. On a first side 214, there is provided an inlet 216, with an outlet 218 provided opposite the inlet 216. [0087] The features of the embodiment of figure 3 that are similar to features present in the embodiment of figure 2 will use the same reference numeral of the figure 2 embodiment, but prefixed by the numeral “2” instead of the numeral “1”. For example, the inlet 216 of figure 3 is similar in appearance and function to the inlet 116 of figure 2.

[0088] One of the main differences between the pile cap 210 of figure 3 and the pile cap 110 of figure 2 is that the top portion 212 of the pile cap 210 is detachable from the base portion 211 of the pile cap 210. The top portion 212 is connected to the base portion 211 of the pile cap 210 along the join 213.

[0089] In embodiments of the present disclosure, the top portion, once attached to the base portion, is fixed to the base portion. The top portion may not, once attached to the base portion, be readily detachable from the base portion.

[0090] When installing the pile cap 210 on the pile 222, the internal inlet and outlet pipes 240, 242 are attached to the pile cap 210, and to the inlet and outlet 216, 218. The pile cap 210 along with the attached pipes 240, 242, is lowered into and above the cavity 229 of the pile 222, such that the lower surface of the pile cap 210 sits on the upper surface of the pile wall 224 of the pile 222. The reinforcement bars 228 pass through the pile cap 210 to secure it in place.

[0091] Then the top portion 212 is connected to the base portion 211 of the pile cap 210, similarly having the reinforcement bars 228 passing through such that the top portion is secured in position to the top of the pile cap. The reinforcement bars 228 prevent radial and circumferential movement of the pile cap 210 relative to the pile 222.

[0092] The top portion 212, when being connected to the base portion 211 of the pile cap 210, can be chosen from a selection of a number of top portions, each of the surfaces having different thicknesses. This can account for differing heights of piles 222 relative to the ground, and relative to other piles in a building construction or foundation system, such that each pile and pile cap are at the same level relative to each other. This facilitates a common pile height for all the piling. [0093] Figure 4a shows a perspective view of a pile cap 310 in a pile assembly 305 according to a fourth embodiment of the present invention.

[0094] As with the above description of the previous embodiments, any features present in the fourth embodiment of the present invention as shown in figure 4a, which are similar in appearance and function to features found in previously described features of the previous embodiments, will share the same two last numbers of the reference numeral. For example, the reinforcement bars 328 are similar in function and appearance to the reinforcement bars 228 of the third embodiment.

[0095] The pile cap 310 has a top portion 312. The base portion 311 of the pile cap 310 takes the shape of a hollow cylinder. Unlike the previous embodiments, the base portion 311 of the pile cap 310 of the embodiment of figure 4a is open at its upper surface when the top portion 312 is removed. This enables maintenance access (by a person for example) to the hollow void 320 of the pile cap 310 and the hollow cavity 329 of the pile 322. It also enables a more straightforward installation, as the pipes 340, 342 do not necessarily have to be connected to the pile cap 310 prior to the attachment of the pile cap 310 to the pile 322.

[0096] The top portion 312 is ordinarily connected to the base portion 311 of the pile cap 310 through the required number of reinforcement bars 328. The reinforcement bars 328 pass through the top portion 312, through the base portion 311 , and through the wall 324 of the pile 322. The reinforcement bars 328 therefore connect and secure the pile cap 310 (in a circumferential direction) to the pile 322. [0097] Three inlet pipes 336 take relatively cool water into the pile cap 310 and down through the three inlet heat exchange pipes 340 through the cavity 329 of the pile 322. The now warmer water passes through the outlet heat exchange pipe 342, into the void 320 of the pile cap 310, and out through the three outlet piles 338.

[0098] In other embodiments of the present invention, instead of cooler water being sent through the inlet pipe into the pile cavity, warmer water is sent instead. The water may be warmed by waste heat from other above-ground processes. The warmer water passing through the inlet heat exchange pipe may heat up thermal material within the cavity of the pile. The warmer water passing through the inlet heat exchange pipe may heat up the wall of the pile, and may heat up the ground surrounding the pile. The thermal material may be a liquid. The thermal material may be water. The thermal material may be a solid. The thermal material may be a granular solid, such as soil for example.

[0099] Also provided within the pile 322 is a device (not shown) that emits a wireless signal 360. The wireless signal 360 conveys information about the internal conditions of the pile 322. The internal conditional may indicate what the temperature of cavity 329 is, for example. This information may indicate whether it is suitable to use the particular pile to heat cooler water, or whether it is suitable to use the particular pile to cool warmer water (i.e. store heat in the pile, from said warmer water), for example.

[00100] Figure 4b shows a plan view of a pile cap 310 according to the fourth embodiment of the present invention. The pile cap 310 in figure 4b is shown without the top portion attached.

[00101] Figure 5 shows a foundation system according to fifth embodiment of the present invention.

[00102] The foundation system comprises two sets of piles 222 and pile caps 210. Each of the piles 222 and pile caps 210 are integrated with the heating and ventilation system of the building 1.

[00103] A second building 2 is also provided that also has a pair of two piles 222’ and pile caps 210’. In the event that the first building 1 requires heating, and building 2 does not require heating, then warm heating fluid may be obtained from either of the piles 222, 222’ acting as a heat reservoir and pumped through the first building 1. If both buildings are generating excess heat, then both buildings 1, 2 will utilise their respective piles 222, 222’ as heat sinks, to store the heat for later use. This may be assisted by a reverse heat pump in connection with the respective pile. The reverse heat pump may be located within the pile. [00104] Although the piles 222, 222’, pile caps, 210, 210’, and buildings 1, 2, have been depicted to be connected in series. This is merely schematic to show that the piles and buildings, according to an embodiment of the present invention, are fluidly connected. According to embodiments of the present invention, the some or all of the piles/pile caps are fluidly connected in parallel. This may have the advantage of improving the efficiency of the heat transfer.

[00105] Figure 6 shows a schematic cross-sectional view of a an example of an embodiment of a foundations system in accordance with the present invention which uses pre-formed pile sections that can be assembled into a pile. The components relating to heat exchange have been omitted for clarity. The foundations system is denoted generally by reference numeral 501. The foundations system 501 comprises multiple pile assemblies (in this case, eight, two of which are shown 502, 503) attached to a pile cover 504 which comprises a large disk of concrete. The foundations system 501 comprises a first pile assembly 502 located within a first bore 505. The first pile assembly 502 comprises a first hollow pile 700 comprising a plurality of pre-formed pile sections 502A, 502B, 502C, 502D that form a pile wall surrounding a cavity, to define a hollow interior of the pile.

[00106] A second pile assembly 503 is shown located within a second bore 506, and comprises a second hollow pile 800 comprising a plurality of pre-formed pile sections 503A, 503B, 503C, 503D that form a pile wall surrounding a cavity, to define a hollow interior of the pile.

[00107] The first pile assembly 502 and second pile assembly 503 each comprise a bottom portion 507, 508. Bottom portions 507, 508 are pre-cast concrete disks.

[00108] Each pile section 502A, 502B, 502C, 502D, 503A, 503B, 503C, 503D is a pre-cast concrete tube, having a hollow interior. Pile sections 502A, 502B, 502C, 502D form first pile 700 and pile sections 503A, 503B, 503C, 503D form second pile 800. [00109] Pre-cast pile sections are advantageous in that they dispense with the need to transport liquid concrete and to form a pile fully from liquid concrete on site. Furthermore, pre-cast pile sections may be readily inspected for defects. Piles made from pre-cast pile sections are also typically easier to dismantle or break-down than traditional cast in situ piles. Furthermore, given that it is possible to make pre-cast piles sections using fibre-reinforced concrete, there may be no need for reinforcement cages that would usually be used with cast in situ piles. Examples of such pre-case pile sections are described in GB2580041.

[00110] As mentioned above, the first 700 and second 800 piles are hollow piles. Flollow piles use less material than non-hollow piles, and the pile sections are relatively light and easy to handle, depending on size, of course. Furthermore, hollow piles may be less stiff than non-hollow piles, and the stiffness of hollow piles tends to better match the stiffness of the surrounding ground, providing better load transfer from pile to ground, thereby improving overall load bearing capacity and settlement performance as against traditional non-hollow cast in situ piles.

[00111] A cementitious grout 519, 520 is provided between the external surfaces of pile sections 502A, 502B, 502C, 502D, 503A, 503B, 503C, 503D and the internal surface of the respective first bore 505 or second bore 506. The grout 519, 520 is also in contact with the tensioning members 509, 510, 511, 512. The grout 519, 520 provides increased friction between the pile and the bore.

[00112] Those skilled in the art will realise that repeat grouting operations may be adopted in order to increase end bearing resistance through the use of grout carrying channels (for example, tubes-a-manchette) incorporated in the base.

[00113] Those skilled in the art will realise that repeat grouting operations may be adopted in order to increase shaft friction resistance through the use of channels (such as those provided by tubes-a-manchette) incorporated in the hollow pre-cast pile sections.

[00114] Those skilled in the art will realise that other sorts of grout (such as a resin) may be used. [00115] Caps 513, 514 may be provided with a reservoir R for the storage of grout. The grout may be conveyed to the grout-carrying channels of the pile via grout- conveying channels (not shown) in the cap 513, 514.

[00116] Figures 7 A and 7B show pile assemblies comprising a spacer 601. Once again, components relating to heat transfer have been omitted for the purpose of clarity. The spacer 601 comprises a disk or annulus of pre-cast concrete. In Figure 8A, the spacer 601 is located between pile section 502D and cap 513. In Figure 8B, the spacer 601 is located on top of cap 13, which is itself located on top of pile section 502D. Spacer 601 adjusts the length of the pile assembly so that the top of the pile assembly is in the desired position, in this case, substantially level with the surrounding ground G. Spacer 601 is provided with channels (not shown) for the location of tensioning members. Such channels may be located in the external (circumferential) surface of the spacer 601. Spacer 601 may also be located in between two pre-formed pile sections, if the pile comprises such pre-formed pile sections.

[00117] Figure 8 shows a schematic side-on view of another embodiment of a pile assembly in accordance with the present invention. The pile assembly comprises a cap 513 atop a pile comprising pre-formed pile section 502D. The cap 513 is located several metres below the ground level GL of ground G. During the construction of the pile, a temporary sleeve (not shown) is placed in the mouth of the bore B and is used to help guide pre-formed pile sections (such as 502D) into position and help retain the pre-formed pile sections in position. Once cap 513 has been fixed into place, the sleeve is removed.

[00118] An embodiment of a method of assembling a hollow pile assembly will now be described in relation to Figure 9. The method is denoted by reference numeral 900, and comprises the steps of: connecting 901 a cap to a hollow pile, the cap comprising a top portion, a base portion, a fluid inlet, and a fluid outlet; passing 902 heat exchanging fluid into the cap through the fluid inlet; exchanging 903 heat between the heat exchanging fluid and a thermal medium located within the hollow pile; and passing 904 fluid out of the cap through the fluid outlet. The hollow pile may, for example, comprise pre-formed pile sections. The method may comprise assembling the pre-formed pile sections to form a pile wall.

[00119] Whilst the present invention has been described and illustrated with reference to particular embodiments, it will be appreciated by those of ordinary skill in the art that the invention lends itself to many different variations not specifically illustrated herein.