GB2621152A

GB2621152A - Stub bypass apparatus

Info

Publication number: GB2621152A
Application number: GB2211316.1A
Authority: GB
Inventors: Garbutt Justine; Davies Barton Christopher; Patel Bhavesh
Original assignee: Francis and Lewis International Ltd
Current assignee: Francis and Lewis International Ltd
Priority date: 2022-08-03
Filing date: 2022-08-03
Publication date: 2024-02-07
Also published as: GB202211316D0

Abstract

A stub bypass apparatus 10 for reinforcing a tower base 12 having a damaged stub, the stub bypass apparatus comprising: a bypass plate 30 having a flange-abutment surface 30 for abuttably engaging with a flange of the tower base, a receiving aperture 34 for receiving the bypass plate about the tower base, at least one flange connection point 42 for connecting the bypass plate to the flange of the tower base, and at least one foundation connection point 44, 44’, wherein the at least one flange connection point and the at least one foundation connection point are co-planar with one another; and at least one foundation anchor 46 engagable with the at least one foundation connection point of the bypass plate and an existing foundation of the tower base to in-use provide a clamping force from the flange-abutment surface of the bypass plate onto the flange of the tower base.

Description

Stub Bypass Apparatus The present invention relates to a stub bypass apparatus for reinforcing a tower base where a stub has become degraded or corroded. The invention further relates to a method of reinforcing the tower using such a stub bypass apparatus, and also to a 5 bypass plate suitable for use with a stub bypass apparatus.

Towers for telecoms purposes, as well as other mast-type structures, are typically mounted onto metal stubs installed in a concrete foundation. The foundation can be prepared easily, and then the tower installed thereon. This is well-established practice within the art. Only a small portion of the stub is exposed above ground.

The exposed portion of the stub, however, can become degraded, corroded, or damaged over time, and if any stub becomes sufficiently defective, then the structural integrity of the whole tower becomes untenable, and repairs or replacement must be performed. Failure of the stub can lead to collapse of the tower. Typically, repairs are performed by constructing a duplicate tower base around a leg of the tower, buttressing around the stub, thereby bypassing the stub, and routing the load through the buttress. This is a disproportionate repair solution however, having a large footprint as well as requiring large material input.

It is an object of the present invention to provide a simple, reproducible. and lightweight stub bypass solution.

According to a first aspect of the invention, there is provided a stub bypass apparatus for reinforcing a tower base having a damaged stub, the stub bypass apparatus comprising: a bypass plate having a flange-abutment surface for abuttably engaging with a flange of the tower base, a receiving aperture for receiving the bypass plate about the tower base, at least one flange connection point for connecting the bypass plate to the flange of the tower base, and at least one foundation connection point, wherein the at least one flange connection point and the at least one foundation connection point are co-planar with one another; and at least one foundation anchor engagable with the at least one foundation connection point of the bypass plate and an existing foundation of the tower base to in-use provide a clamping force from the flange-abutment surface of the bypass plate onto the flange of the tower base.

The present invention has been designed to provide a means of repairing or reinforcing a tower base where the stub has become damaged, which can be installed without the need for significant machinery investment, or the need to bring heavy mechanical plant to site. The bypass plate is designed to withstand severe stresses which may be applied when the stub is bypassed, as well as being sufficiently lightweight to be carried by one or two workers. The planarity of the plate also provides a suitable lid, underneath which a grout column can be formed to provide ongoing compression resistance and weatherproofing.

Optionally, the receiving aperture may comprise a slotted receiver extending from an 10 edge of the bypass plate The presence of a slotted receiver allows for the bypass plate to be engaged with the tower base without needing to dismantle the tower base at all.

The slotted receiver may have a tapered throat portion.

The tapered throat portion allows for simpler access of the bypass plate towards the 15 tower base, whilst also potentially accommodating some of the load-bearing structures of the tower which couple to the tower base at low-level.

Preferably, the bypass plate may comprise at least one grip void.

The presence of a grip void provides a region for a user to be able to lift the bypass plate, whilst also simultaneously reducing the weight of the bypass plate for no discernible loss 20 of strength.

In one embodiment, the bypass plate may have a trapezoidal or substantially trapezoidal shape.

A trapezoidal structure provides good stability around the flange of the tower base, whilst also keeping the foundation connection points nicely spread, thereby limiting the 25 likelihood of stress fractures within the concrete foundation.

In an alternative embodiment, the bypass plate may be or may substantially be X-shaped.

An X-shaped bypass plate has significantly less material required to form the plate body, which further adds to the weight reduction, making the bypass plate more suitable for manual transport.

Optionally, a plurality of foundation connection points may be provided, each foundation 5 connection point being positioned at a corner of the bypass plate. Said plurality of foundation connection points may comprise at least one tower-proximal foundation connection point, and at least one tower-distal foundation connection point.

The closer the foundation anchors are to one another, the greater the risk of damage to the underlying foundation. Spreading the foundation connection points of the bypass plate reduces this risk. Additionally, since the bypass plate is installed above the level of the foundation, the bypass plate defines a volume around the damaged stub, and the corners may define suitable delimiters for a grout column to be installed, preventing further corrosion.

The at least one tower-proximal foundation connection point may be laterally offset with 15 respect to the at least one tower-distal foundation connection point.

The lateral offset provides sufficient space for the worker to access the tower base during works, which may make the installation procedure less cramped.

It is preferred that the bypass plate may be pre-stressed. Additionally, or alternatively, the at least one foundation anchor may be pre-stressed.

Pre-stressing of the components of the apparatus can limit the risk of stress damage to the apparatus once installed.

In one embodiment, the bypass plate may be a multi-part bypass plate.

With a multi-part bypass plate, the weight of the apparatus can be further reduced, though installation may be more complicated for a single worker.

The bypass plate may have a weight of less than 30kg.

30kg is a target weight beyond which it becomes likely that mechanical assistance will be required in the installation process. Weight of the bypass plate can be influenced by the provision of voids or similar to reduce the material content of the bypass plate without reducing strength.

The stub bypass apparatus may further comprise a supplementary bypass plate in-use receivably engagable with the said bypass plate at an upper surface thereof.

For larger towers having wider legs, the foundation anchors must be spaced further apart to avoid stress fracture damage to the foundation itself. In doing so, the foundation anchors apply force further from the flange itself. There is therefore a greater risk of lifting forces from the flange causing a separation between the bypass plate and the flange, resulting in failure. A supplementary bypass plate, spreading the load in a lateral direction across the upper surface of the said bypass plate, can substantially obviate this issue.

Optionally, the supplementary bypass plate may be shape-matched to a tower-distal side of the bypass plate.

If the supplementary bypass plate is shape-matched to the said bypass plate, then this will ensure a good degree of contact therebetween to limit stress damage.

Preferably, the bypass plate and supplementary bypass plate may have complementary additional connection points for interconnection with one another.

Additional connection points allow for the discrete plates to be interconnected without necessarily needing to fully anchor the supplementary bypass plate, which serves as a brace.

According to a second aspect of the invention, there is provided a method of reinforcing a tower base having a damaged stub, the method comprising the steps of: a] providing a stub bypass apparatus in accordance with the first aspect of the invention; b] engaging the at least one foundation anchor with a foundation of the tower base; c] connecting the bypass plate to a flange of the tower base via the at least one flange connection point, such that the at least one foundation connection point corresponds with the at least one foundation anchor; and d] securing the at least one foundation anchor to the at least one foundation connection point.

The present method of repairing a tower base improves the working life of the tower, without needing large or cumbersome repair solutions. The reduced weight of the bypass plate also means it can be performed by one or two workers without mechanical assistance.

The method may further comprise a step e] subsequent to step d] of forming a grout column between the bypass plate and the foundation around the damaged stub.

A grout column protects the components below the bypass plate from becoming further damaged following installation, reducing the risk of further repairs being required. This contrasts significantly with bulkier repair solutions, where no such weather-proofing is feasible.

Optionally, during step c], the bypass plate may be connected to the flange of the tower 10 without removing all of the existing fasteners for the flange to the stub.

The ability to install a bypass plate without needing to dismantle the tower in the process significantly reduces the installation time, which in turn reduces outage times from the tower being out of operation.

Preferably, during step c], the bypass plate is introduced towards the tower base laterally.

Lateral introduction of the bypass plate towards the tower base is a simple installation process, which can be performed entirely by an individual worker.

According to a third aspect of the invention, there is provided a bypass plate for a stub bypass apparatus, the bypass plate comprising: a flange-abutment surface for abuttably engaging with a flange of a tower base; a receiving aperture for receiving the bypass plate about the tower base; at least one flange connection point for connecting the bypass plate to the flange of the tower base; and at least one foundation connection point, wherein the at least one flange connection point and the at least one foundation connection point are co-planar with one another.

The invention will now be more particularly described, by way of example only, with 25 reference to the accompanying drawings, in which: Figure 1 shows a pictorial representation of an indicative telecoms tower base having a foundation with a damaged stub, shown in detail in the inset; Figure 2 shows an isometric representation of a first embodiment of a stub bypass apparatus in accordance with the first aspect of the invention, when seated on a flange of a tower base; Figure 3 shows a plan view of the sub bypass apparatus of Figure 2, inclusive of 5 fasteners; Figure 4 shows a perspective representation of a drill guide used in the installation of the stub bypass apparatus of Figure 2; Figure 5 shows a perspective representation of the stub bypass apparatus of Figure 2 in a partially installed condition; Figure 6 shows a perspective representation of the stub bypass apparatus of Figure 2 in a fully installed condition; Figure 7 shows a plan view of a second embodiment of a stub bypass apparatus in accordance with the first aspect of the invention, when seated on a flange of a tower base; Figure 8 shows a perspective representation of a third embodiment of a stub bypass apparatus in accordance with the first aspect of the invention, when seated on a flange of a tower base; Figure 9 shows a perspective representation of a fourth embodiment of a stub bypass apparatus in accordance with the first aspect of the invention, when seated on a 20 flange of a tower base; Figure 10 shows a plan view of the stub bypass apparatus of Figure 9; Figure 11 shows a perspective representation of a fifth embodiment of a stub bypass apparatus in accordance with the first aspect of the invention; Figure 12 shows a perspective representation of a sixth embodiment of a stub 25 bypass apparatus in accordance with the first aspect of the invention; and Figure 13 shows a perspective representation of a seventh embodiment of a stub bypass apparatus in accordance with the first aspect of the invention.

Referring to Figure 1, there is indicated an exemplary telecoms tower, referenced at 10, having a tower base 12 which is connected to a foundation 14 for structural support. The foundation 14 comprises a concrete slab 16 having a plurality of stubs 18 embedded therein, a number of stubs 18 being equal to a number of feet 20 of the tower base 12.

Each foot 20 has a flange 22 which is complementarily engagable with a corresponding flange 24 of the stub 18, and secured in place via fasteners 26, typically bolts.

A stub bypass apparatus, such as that shown in Figures 2 and 3, and referenced at 28, can be used to take the load from a foot 20 connected to a damaged or degraded stub 18, completely bypassing the stub 18 by anchoring directly into the concrete slab 16.

The stub bypass apparatus 28 comprises a bypass plate 30 having a flange-abutment surface 32 for abuttably engaging with a flange 22 of the tower base 12. The bypass plate 30 also includes a receiving aperture 34 for receiving the bypass plate 30 about the tower base 12. The receiving aperture 34 here has a slotted receiver 36 extending from one edge 38 thereof, so that the bypass plate 30 can be introduced towards the tower base 12 from a lateral direction. The slotted receiver 36 may have a tapered throat portion 40 to accommodate the shape of the tower base 12.

At least one flange connection point 42 is provided for connecting the bypass plate 30 to the flange 22. In the depicted embodiment each flange connection point 42 is provided as an aperture through the bypass plate 30 for receivably engaging with a fastener 26, such as the nut and bolt shown in Figure 3. There is also at least one foundation connection point 44, 44', again formed as an aperture through the bypass plate 30 for receivably engaging with a foundation anchor 46, such as the nut and bolt shown in Figure 3. The flange connection points 42 and the foundation connection points 44, 44' are co-planar with one another.

By co-planar, it is intended to define that the flange connection points 42 and the foundation connection points 44, 44' at least in part overlap in a horizontal plane through the bypass plate 30, and more preferably, that the bypass plate 30 is itself planar, the flange connection points 42 and the foundation connection points 44, 44' extending through the bypass plate 30.

The bypass plate 30 may include one or more, preferably elongate, grip voids 45, at or towards the edges of the bypass plate 30. This reduces the weight of the bypass plate without negatively impacting on its structural integrity, whilst also providing a place for a user to grip the bypass plate 30 during transit.

The bypass plate 30 preferably has a trapezoidal or substantially trapezoidal shape. The wider edge 38a of the trapezium here forms the tower-proximal side of the bypass plate 5 30, with an opposite edge 38b forming a tower-distal side of the bypass plate 30. This results in the presence of tower-proximal and tower-distal foundation connection point 44, 44', and the tower-proximal and tower-distal foundation connection points 44, 44' are laterally offset to one another; an indicative angle of rotation of the tower-proximal foundation connection points 44 with respect to the tower-distal foundation connection 10 points 44' is 20°. The foundation connection points 44, 44' are positioned in the corners of the bypass plate 30.

The dimensions of the bypass plate for specific contexts can be calculated using finite element analysis, which has been performed for the illustrated design. For a standard 76.1mm diameter tower base 12, spacings between adjacent foundation connection points 44, 44' was provided as 220mm, with a plate thickness of 35mm, though a minimum plate thickness of 32mm was deemed feasible. An anchor embedment depth of 400mm was required. In any event, a plate thickness of at least 25mm is likely to be used in all serious engineering contexts.

Using the finite element analysis, it was found that the stress maxima were concentrated 20 around the edge of the flange 22, that is, at the receiving aperture 34, and at the foundation connection points 44, 44'. Improved strength of the bypass plate 30 at these locations can be achieved by pre-stressing of the material.

The foundation anchors 46 are engagable with the at least one foundation connection point 44, 44' of the bypass plate 30 and the concrete slab 16 to in-use provide a clamping 25 force from the flange-abutment surface 32 of the bypass plate 30 onto the flange 22 of the tower base 12.

The bypass plate 30 is preferably fixed to the flange 22 itself. The existing fasteners 26 between the tower base 12 and the stub 18 can be used for this, and the positions of the flange connection points 42 are provided with this in mind.

To install the stub bypass apparatus 28, the tower 10 and foundation 14 must first be inspected; if either of these are too damaged, then the stub bypass apparatus 28 will not be effective. Typically, this is done via a site survey.

The stub 18 itself would then be inspected, typically by drilling a hole into the stub 18, 5 and introducing a borescope to examine the status. Other techniques can be used, for example, by using a rebound hammer or similar metal scanner. If the stub 18 is deemed defective, then remedial work can begin using the stub bypass apparatus 28.

All loose and visible rust should be removed from the stub 18, and holes drilled into the stub 18 to permit the escape of air and water therefrom. A corrosion protection layer is 10 then applied to the holes and any damage, such as a zinc-rich paint.

The anchor holes must then be prepared in the concrete slab 16. A drill guide 48 can be used for this purpose, as shown in Figure 4, which is a plate 50 dimensioned to the bypass plate 30 which has a plurality of drill-alignment receivers 52 positioned to correspond with the locations of the foundation connection points 44, 44'. The drill-guide 48 can be constructed to be engaged with the flange 22 of the tower base 12 to be repaired, without removing all of the existing fasteners 26. Given that this process does, however, require some of the structural bolts be removed, it is recommended that this process only occur in low-wind speed conditions, preferably not exceeding 12.1m/s measured at 10m above ground level. Drilling into the concrete slab 16 can then occur to the minimum embedment depth.

At this point, the foundation anchors 46 can be inserted into the holes, and would typically be adhesively engaged in position. The foundation anchors 46 would generally be left with sufficient overhang above ground, to ensure that there is sufficient height to engage with the bypass plate 30 once installed. The adhesive is then left to cure.

To install the bypass plate 30, alignment with the foundation anchors 46 is first confirmed, before the outer three flange bolts 26 of the flange 22 of the tower base 12 are removed. The flange bolt 26 which would be positioned in the slotted receiver 36 in-use need not be removed.

The bypass plate 30 is then positioned onto the flange 22, with the flange-abutment 30 surface 32 abuttably engaging with the flange 22. The bypass plate is connected to the flange 22 using the fasteners 26, or replacement fasteners as required. The fastener 26 which was not removed can then be replaced if necessary.

The foundation anchors 46 can then be tested by application of a test load, commonly 113kN. If any foundation anchor 46 fails, then further remedial action is required. If there are no deficiencies, however, the nuts of the foundation anchors 46 can be engaged therewith, securing the bypass plate 30 in position, as is shown in Figure 5. Any earthing lugs 54 may also be installed at this point. The foundation anchors 46 are securely torqued in an even manner across the foundation anchors 46, preferably to 160Nm torque.

At this point, the stub 18 should be grouted internally, preferably with a high-strength, non-shrink, cementitious grout of minimum 40MPa strength, mixed to a flowable consistency. This can be pumped into the stub 18 via one of the previously drilled holes, displacing any air or water present.

The outer surface of the bypass plate 30 and stub 18 can then be cleaned, and a grout box put in place, so that a grout column can be prepared between the concrete slab 16 and the overhanging portion of the flange-abutment surface 32 of the bypass plate 30. Again, the grout used should be a high-strength, non-shrink, cementitious grout of minimum 40MPa strength, mixed to a flowable consistency. The grout box can be struck off once cured, and any rough edges worked out. The completed stub bypass apparatus 28 is shown in Figure 6.

A second embodiment of stub bypass apparatus is shown in Figure 7, which has been designed to accommodate a larger tower base 112 having 88.9mm diameter. However, since the tower bases of these dimensions have identical flange sizes and configurations, this stub bypass apparatus supersedes that shown in Figure 2. The stub bypass apparatus is referenced globally at 128, and identical or similar reference numerals will be used to refer to identical or similar features, and further detailed description is omitted for brevity.

Compared with the embodiment of Figure 2, the bypass plate 130 has been increased in thickness, to 45mm thickness, but the positions of the flange connection points 142 30 remains identical. The foundation connection points 144, 144' are slightly further spaced apart from one another by an additional 20mm, with an increased anchor embedment depth of 600mm.

To compensate for the increased size of the bypass plate 130, the tapered throat portion 140 of the slotted receiver 136 leading to the receiving aperture 134 is increased in size, also providing additional clearance for receiving the tower base 112. The weight of this bypass plate 30 is expected to be around 29kg, which means that it remains carriable by hand without the need for mechanical assistance.

A third embodiment of stub bypass apparatus is shown in Figure 8, referenced globally at 228 and connected to a tower base 212, and identical or similar reference numerals will be used to refer to identical or similar features, and further detailed description is omitted for brevity. Weight reduction of the bypass plate 230 is achieved by providing cut-out portions 256 of the more square-profiled bypass plate 230. A reinforcement bar 258 is also provided across the slotted receiver 236, which may improve the strength thereof.

There is a larger class of towers, which have leg diameters of 114.3mm. The aforementioned designs can be enlarged to work with such towers; however, the weight of the stub bypass apparatuses then becomes greater than can be safely manually handled. Alternative designs of stub bypass apparatus are discussed hereafter which resolve this issue.

A fourth embodiment of stub bypass apparatus is thus shown in Figures 9 and 10, which has been designed to accommodate a 114.3mm diameter tower bases 312. The stub bypass apparatus is referenced globally at 328, and identical or similar reference numerals will be used to refer to identical or similar features, and further detailed description is omitted for brevity.

The bypass plate 330 of this arrangement has a plurality of flange connection points 342; there are five shown, as there are six fasteners for this size of tower base 312. As with the previous embodiments, the final fastener is positioned within the slotted receiver 336 of the receiving aperture 334 in use.

The bypass plate 330 itself has a substantially X-shaped body, which has the 30 appearance of butterfly wings, with the tower-proximal side 360 tapering more than the tower-distal side 362, producing the distinctive shape. Grip voids 345 are provided in the tower-distal side 362. Again, the foundation connection points (n316, n316') are provided in the corners of the bypass plate 330.

Finite element analysis illustrates that, at higher loads, the greatest stress to the foundation is provided at the tower-distal side 362, and can result in damage to the concrete slab 16 of the foundation 14. Lateral bracing is thus provided by adding a supplementary bypass plate 364 in-use receivably engagable with the said bypass plate 330 at an upper surface 366 thereof.

In this embodiment, the supplementary bypass plate 364 is shape-matched to the tower-10 distal side 362 of the bypass plate 330, inclusive of the tower-distal foundation connection points 344', and any overlapping flange connection points 342.

Both the bypass plate 330 and supplementary bypass plate 364 also include additional connection points 368, here positioned co-axially with the tower base 312. Dedicated fasteners 370 are shown in Figure 10, interconnecting the bypass plate and 15 supplementary bypass plate 364.

It may be feasible to provide additional foundation anchors which engage with the additional connection points 368, though it may be difficult to avoid damage to the concrete slab 16 in this scenario, as the foundation anchors would then be less well spread relative to one another.

The supplementary bypass plate 364 thus provides reinforcement to the said bypass plate 330, inhibiting separation of the flange 322 and the bypass plate 330 under stress. In essence, the supplementary bypass plate 364 binds the flange 322 and the bypass plate 330 together more effectively.

A fifth embodiment of stub bypass apparatus is shown in Figure 11. The stub bypass 25 apparatus is referenced globally at 428, and identical or similar reference numerals will be used to refer to identical or similar features, and further detailed description is omitted for brevity.

This version of the stub bypass apparatus 428 utilises a multi-part bypass plate 430, having first and second plate portions 430a, 430b. In this arrangement, the 30 supplementary bypass plate 464 serves as a tie plate between the first and second plate portions 430a, 430b, and which may abuttably engage with the tower base 412. Notably, this illustrates that the supplementary bypass plate 464 need not be shape-matched to any part of the bypass plate 430.

A sixth embodiment of stub bypass apparatus is shown in Figure 12. The stub bypass 5 apparatus is referenced globally at 528, and identical or similar reference numerals will be used to refer to identical or similar features, and further detailed description is omitted for brevity.

This version of the stub bypass apparatus 528 utilises a circular bypass plate 530, with the supplementary bypass plate 564 having a horseshoe shape which is received around the tower base 512. In the depicted embodiment, the supplementary bypass plate 564 has been introduced from an opposite direction to that of the bypass plate 530. This could provide an improved reinforcing effect, without necessarily a significant weight increase to the overall apparatus 528.

A seventh embodiment of stub bypass apparatus is shown in Figure 13. The stub bypass 15 apparatus is referenced globally at 628, and identical or similar reference numerals will be used to refer to identical or similar features, and further detailed description is omitted for brevity.

The depicted bypass plate 630 is a multi-part bypass plate having first and second bypass plate portions 630a, 630b which do not contact one another at all. This 20 configuration of bypass plate 630 may help with weight mitigation, since each bypass plate portion 630a, 630b can be easily carried by a single worker.

The various embodiments shown are non-limiting, and any appropriate shape of bypass plate or supplementary bypass plate can be considered.

Whilst the bypass plate is defined as being planar here, it will be appreciated that the 25 grout column could be installed below, even where the bypass plate were not completely planar, provided that suitable anchoring was provided.

The lower surface of the bypass plate is referred to as a flange-abutment surface. It will be apparent that its purpose is to bear against the flange which it is reinforcing, and therefore this function is fulfilled even if an intermediate member, such as a washer or 30 seal, were provided.

It is therefore possible to provide a bypass plate, as part of a stub bypass apparatus, which enables quick repair of the base of a tower such as a telecoms tower, without needing to perform any dismantling. The solution is simple, but also provides a means for adequate weatherproofing of the remaining stub to limit further damage. The bypass plate has been created with simplicity in mind, so that the repair process can be performed by one or two workers only, without the need for mechanical intervention.

The words 'comprises/comprising' and the words 'having/including' when used herein with reference to the present invention are used to specify the presence of stated features, integers, steps, or components, but do not preclude the presence or addition 10 of one or more other features, integers, steps, components, or groups thereof.

It is appreciated that certain features of the invention, which are, for clarity, described in the context of separate embodiments, may also be provided in combination in a single embodiment. Conversely, various features of the invention which are, for brevity, described in the context of a single embodiment, may also be provided separately or in any suitable sub-combination.

The embodiments described above are provided by way of examples only, and various other modifications will be apparent to persons skilled in the field without departing from the scope of the invention as defined herein.

Claims

Claims 1. A stub bypass apparatus for reinforcing a tower base having a damaged stub, the stub bypass apparatus comprising: a bypass plate having a flange-abutment surface for abuttably engaging with a flange of the tower base, a receiving aperture for receiving the bypass plate about the tower base, at least one flange connection point for connecting the bypass plate to the flange of the tower base, and at least one foundation connection point, wherein the at least one flange connection point and the at least one foundation connection point are co-planar with one another; and at least one foundation anchor engagable with the at least one foundation connection point of the bypass plate and an existing foundation of the tower base to in-use provide a clamping force from the flange-abutment surface of the bypass plate onto the flange of the tower base.
2. A stub bypass apparatus as claimed in claim 1, wherein the receiving aperture comprises a slotted receiver extending from an edge of the bypass plate.
3. A stub bypass apparatus as claimed in claim 2, wherein the slotted receiver has a tapered throat portion.
4. A stub bypass apparatus as claimed in any one of the preceding claims, wherein the bypass plate comprises at least one grip void.
5. A stub bypass apparatus as claimed in any one of the preceding claims, wherein the bypass plate has a trapezoidal or substantially trapezoidal shape.
6. A stub bypass apparatus as claimed in any one of claims 1 to 4, wherein the bypass plate is or is substantially X-shaped.
7 A stub bypass apparatus as claimed in any one of the preceding claims, wherein a plurality of foundation connection points is provided, each foundation connection point being positioned at a corner of the bypass plate.
8 A stub bypass apparatus as claimed in claim 6, wherein the plurality of foundation connection points comprises at least one tower-proximal foundation connection point, and at least one tower-distal foundation connection point.
9 A stub bypass apparatus as claimed in claim 7, wherein the at least one tower-proximal foundation connection point is laterally offset with respect to the at least one tower-distal foundation connection point.
10. A stub bypass apparatus as claimed in any one of the preceding claims, wherein the bypass plate is pre-stressed.
11. A stub bypass apparatus as claimed in any one of the preceding claims, wherein the at least one foundation anchor is pre-stressed.
12. A stub bypass apparatus as claimed in any one of the preceding claims, wherein the bypass plate is a multi-part bypass plate.
13. A stub bypass apparatus as claimed in any one of the preceding claims, wherein the bypass plate has a weight of less than 30kg.
14. A stub bypass apparatus as claimed in any one of the preceding claims, further comprising a supplementary bypass plate in-use receivably engagable with the said bypass plate at an upper surface thereof.
15. A stub bypass apparatus as claimed in claim 14, wherein the supplementary bypass plate is shape-matched to a tower-distal side of the bypass plate.
16. A stub bypass apparatus as claimed in claim 14 or claim 15, wherein the bypass plate and supplementary bypass plate have complementary additional connection points for interconnection with one another.
17. A method of reinforcing a tower base having a damaged stub, the method comprising the steps of: a] providing a stub bypass apparatus as claimed in any one of the preceding claims, b] engaging the at least one foundation anchor with a foundation of the tower base, c] connecting the bypass plate to a flange of the tower base via the at least one flange connection point, such that the at least one foundation connection point corresponds with the at least one foundation anchor; and d] securing the at least one foundation anchor to the at least one foundation connection point.
18. A method as claimed in claim 17, further comprising a step e] subsequent to step d] of forming a grout column between the bypass plate and the foundation around the damaged stub.
19. A method as claimed in claim 17 or claim 18, wherein during step c], the bypass plate is connected to the flange of the tower without removing all of the existing fasteners for the flange to the stub.
20. A method as claimed in any one of claims 17 to 19, wherein during step c], the bypass plate is introduced towards the tower base laterally.
21. A bypass plate for a stub bypass apparatus, the bypass plate comprising: a flange-abutment surface for abuttably engaging with a flange of a tower base, a receiving aperture for receiving the bypass plate about the tower base; at least one flange connection point for connecting the bypass plate to the flange of the tower base; and at least one foundation connection point, wherein the at least one flange connection point and the at least one foundation connection point are co-planar with one another.