WO2024073790A1

WO2024073790A1 - Permanent tanks

Info

Publication number: WO2024073790A1
Application number: PCT/AU2022/051180
Authority: WO
Inventors: Kieron Michael Jeffries; Shaun Edward Barry
Original assignee: Entacon Pty Ltd
Priority date: 2022-10-04
Filing date: 2022-10-04
Publication date: 2024-04-11

Abstract

A permanent tank, and method of constructing same, having a plurality of precast wall panels retained by a cable tensioning system to form a continuous, preferably circular, wall and a roof to fluidly seal a cavity formed between the roof and the wall panels. The roof can be rigid and mounted on the continuous wall of the tank. Alternatively, the roof can be flexible, and in some embodiments, the flexible roof can float on the surface of a liquid in the tank. The tank can be easily assembled at a site with prefabricated parts. The shape of the precast wall panels in conjunction with the cable tensioning system means no additional frame or supports are required.

Description

PERMANENT TANKS

FIELD OF THE INVENTION

[0001 ] The invention relates to permanent tanks. In particular, the invention relates, but is not limited, to a modular, liquid storage tank formed on a site by a plurality of panels which is intended to remain in place.

BACKGROUND TO THE INVENTION

[0002] Reference to background art herein is not to be construed as an admission that such art constitutes common general knowledge.

[0003] Tanks of various shapes and sizes are known for storing fluids, in particular liquids, such as water. Such tanks vary in size tremendously from, for example, a personal/domestic water storage tank for drinking or irrigation purposes to industrial or commercial storage tanks. Small tanks are relatively easy to assemble and can often be moulded as a single piece (e.g., 1 -5KL water storage tanks). However, as tank sizes increase it becomes increasingly more difficult to construct a sealed tank for storing fluid.

[0004] One of the issues with constructing large tanks is in transporting and building the tank, particularly for remote locations. For example, in utilities applications, water is a resource which may be stored in tanks, or reservoirs, or the like. The storage of these liquids in the tanks may be long term or temporary. In any event, often the storage site is in a constrained location with limited land space and may also be in a remote location with limited infrastructure and building a tank requires significant preparation and logistics. Furthermore, traditional construction methods either involve significant earthworks (specifically for an earthen bund storage) or significant construction time onsite. Both methods add significant costs for materials and time.

[0005] Large tanks often suffer from hoop stress and, when empty, wind loading. Furthermore, the walls of the tank may need to be reinforced with an external structure. For example, the walls of the tank may be reinforced with a frame. Such a frame typically has support members which extend radially outwards from the tank walls. In one tank design, the support members are steel ‘A’ -frame members. Disadvantageously, such supporting framework requires additional space around the tank walls. As the support members need to be provided with suitable support, the concrete pad or footing also needs to be large enough to extend to at least the outer edge of the framework, further increasing costs and environmental impact of the tank. Furthermore, the base of the tank may need to be reinforced concrete further increasing costs and environmental impact of the tank.

OBJECT OF THE INVENTION

[0006] It is an aim of this invention to provide a permanent tank which overcomes or at least ameliorates one or more of the disadvantages or problems described above, and/or which at least provides a useful alternative.

[0007] Other preferred objects of the present invention will become apparent from the following description.

SUMMARY OF INVENTION

[0008] In one form, although it need not be the only or indeed the broadest form, there is provided a permanent tank comprising: a plurality of precast wall panels arrangeable on a floor to form a continuous wall; a roof mounted on the continuous wall to seal a cavity formed between the roof, the wall panels, and the floor; and a tensioning system comprising one or more cables configured to extend around the continuous wall; wherein the wall panels and cable tensioning system are configured to retain abutting wall panels in an interference fit.

[0009] Suitably, the floor can be earthen, or can comprise reinforced concrete. Suitably, the floor can be in the form of a ring beam foundation. [0010] The roof may be flexible or rigid. The roof may comprise a roof of flexible or rigid material. The roof may comprise a flexible plastic or polymer material such as, polypropylene. The roof may comprise a rigid material such as, steel or aluminium or concrete panels. In some embodiments, the flexible roof can float on the surface of a liquid in the tank.

[001 1 ] The tank may comprise a roof support structure to support the roof spanning across the tank from wall to wall.

[0012] The tank may comprise a roof support member to support at least a portion of the roof or support structure. The support member may be in the form of a support column. The support column may comprise a central support column or a plurality of columns. The support column(s) may extend from the floor to the roof.

[0013] The wall panels may be made of a cementitious material. The wall panels may comprise precast concrete panels. The wall panels may be substantially planar. The wall panels may be rectangular. The wall panels may have side walls at a transverse angle to the plane of the panel. The side walls may be angled from 0° to 22.5° relative to the orthogonal axis of the plane of the panel. The angled side walls may be angled in opposite directions, preferably forming an isosceles trapezoid in a cross-section of the wall panel.

[0014] The wall panels may have at least one channel that receives at least part of the tensioning system. The channel may be in the form of an internal conduit through the panel. Each wall panel may comprise a plurality of channels. The channels may be spaced apart.

[0015] The continuous wall is preferably circular or, at least, substantially circular. One or more single cables may extend within the internal conduit around the continuous wall. Alternatively, a plurality of cables may collectively extend within the internal conduit around the continuous wall. The cable may be internal to the wall panels, or partially external and partially internal to the wall panels.

[0016] At least one of the wall panels may comprise a cable retainer at one or more specific panels called buttresses or buttress panels. The cable tensioning system may comprise a cable anchor at at least one end of the cable. The cable tensioning system may comprise a cable anchor at each end of the cable. The cable retainer of the wall panel may be configured to receive and retain the cable anchor. The tensioning system may comprise a single cable tensioning system extending the perimeter of the continuous wall. The cable tensioning system may comprise a plurality of cables each extending around a portion of the perimeter of the continuous wall. The cables are tensioned after wall erection to support the hoop stress. The continuous wall preferably has no support structures, such as buttresses, extending radially or perpendicularly to the wall panels.

[0017] The permanent tank may comprise a liner configured to fluidly seal the wall panels and a floor of the permanent tank. The liner preferably lines an inner surface of the tank defined by the inner surface of the wall and the floor. The floor preferably includes a surface upon which the wall panels are placed. The surface under the wall panels may be reinforced concrete. The remaining surface of the tank floor may be earthen, preferably graded. The liner preferably comprises a leak detection system. The leak detection system preferably comprises a leak detection layer fluidly connected to an outlet. The outlet is preferably a sump. A communications device may be provided to transmit a signal if a leak is detected. A pump may be configured to return fluid in the sump back into the permanent tank.

[0018] In a preferred embodiment there are between 15 and 500 wall panels, more preferably between 20 and 400 wall panels, and even more preferably between approximately 25 and 300 wall panels. However, it will be appreciated that the number of wall panels will depend on the size of tank required, the application and the site parameters.

[0019] In another form, there is provided a method of assembling a tank on a site, the method comprising the steps of: erecting a plurality of precast wall panels on a floor at the site to form a continuous wall; configuring one or more cables to extend around the continuous wall; tightening the one or more cables to retain the plurality of wall panels in an interference fit; and constructing a roof over the continuous wall to fluidly seal a cavity formed between the roof, the wall panels, and the floor.

[0020] The method may comprise levelling a ground surface to form the floor. The floor may be earthen. The method may comprise creating a pad to form the floor. The method may comprise creating a concrete pad. The method may comprise forming a floor in the form of a ring beam made of a cementitious material.

[0021 ] The method may comprise supporting the plurality of precast wall panels with temporary supports until the tensioning system is tightened to hold the wall panels in the interference fit. The method may comprise anchoring one or more cables in one or more recesses of at least one wall panel. The method may further comprise passing one or more cables through channels in the wall panels, in particular, channels in the form of internal conduits within the panels.

[0022] The method may comprise applying a liner to fluidly seal the wall panels and floor.

[0023] The method of constructing a permanent tank preferably comprises constructing the permanent tank as hereinbefore described.

[0024] Further features and advantages of the present invention will become apparent from the following detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

[0025] By way of example only, preferred embodiments of the invention will be described more fully hereinafter with reference to the accompanying figures, wherein:

Figure 1 illustrates a perspective view of a permanent tank;

Figure 2 is a cross sectional view of adjacent wall panels of the permanent tank; Figure 3 is a cross sectional view of adjacent wall panels and a buttress panel of the permanent tank showing a tensioning anchor system;

Figure 4 illustrates a diagrammatic cross-sectional view of the tank comprising a leak detection system;

Figure 5 and Figure 6 illustrates the tank of Figure 4 comprising a roof; and

Figure 7 illustrates an example of how layers of the tank and a flexible roof are mounted to walls panels of the tank.

DETAILED DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 illustrates a permanent tank 10 in accordance with embodiments of the present invention. Temporary supports 102, which may be used during construction, are also shown. A plurality of precast wall panels 1 10 are arranged adjacent one another to form a substantially circular continuous wall 100. The panels 1 10 are planar such that each forms a circle segment. In the illustrated wall 100 there are approximately 200 wall panels 1 10. Once the wall 100 has been erected and retained by a tensioning system the temporary supports 102 can be removed and the wall 100 is self-standing.

[0027] As shown in Figure 2, the wall panels 1 10 have side walls 1 12 that are at a transverse angle, preferably between 0° and 22.5° to an orthogonal axis of the plane of the panels 1 10. In cross-section the wall panels have an isosceles trapezoid shape. The wall panels 1 10 also have a channel 1 14 in the form of an internal conduit configured to receive a cable from a cable tensioning system. The tensioning cable is passed through the channels 1 14 of adjacent wall panels 1 10 and tensioned at cable anchors 120 in selected wall panels 1 10 (see Figure 3).

[0028] In some embodiments, a plurality of tensioning cables, anchored by a plurality of cable anchors 120, as shown in Figure 3, can be provided to extend around the continuous wall 100 through the channel 1 14. [0029] In some embodiments, the wall panels 1 10 can comprise a plurality of channels 1 14 wherein the channels are spaced apart.

[0030] One or more single cables can extend within the internal conduit of each channel 1 14 around the continuous wall 100. Alternatively, a plurality of cables may collectively extend within the internal conduit of each channel 1 14 around the continuous wall 100. Each cable can be internal to the wall panels 1 10, or partially external and partially internal to the wall panels.

[0031 ] The angled side walls 1 12 allow the wall panels 1 10 to abut each other and provide support in a ‘keystone’ manner such that they cannot fall inward. The cable tensioning system retains the wall panels 110 in such an arrangement and provides support such that the wall panels cannot fall outward. In use, liquid 20 contained in the tank provides radial forces against the wall panels 1 10. The tensioning system must therefore be of sufficient strength to not just hold the wall panels 1 10 in place in a freestanding manner, but also to be able to withstand the radial forces caused by the liquid 20 contained in the tank.

[0032] To construct the permanent tank 10, a suitable site is first determined. The site may be prepared first, such as by levelling a ground surface and, in some embodiments, creating a footing for a foundation of the wall panels and/or creating a pad to form a floor of the tank 10. In some embodiments, the floor is earthen, or the floor can comprise reinforced concrete. In some embodiments, the floor is in the form of a ring beam foundation. Once a suitable ground surface has been determined, a plurality of precast wall panels 1 10 can be erected to form a continuous wall 100. Temporary supports 102 may be utilised to support the wall panels 1 10 during construction. A tensioning system is then applied to cables running through channels in the wall panels 1 10 to tighten the cables to hold the wall panels 1 10 in an interference fit.

[0033] A roof 200 can then be constructed over the continuous wall 100 to fluidly seal a cavity formed between the roof 200, wall 100, and floor 140. The roof 200 is preferably flexible or can be rigid. In preferred forms the roof comprises a flexible plastics material, such as polypropylene. Alternatively, a rigid material, such as steel or aluminium or concrete panels can be used.

[0034] Figure 4 illustrates a liner and leak detection system comprising a first liner 150, a geotextile and/or geonet layer 152, a leak detection liner 154, and a cushioning layer which may be in the form of a geotextile 156. An internal sump 158 is fluidly connected to the leak detection liner 154 which is in turn fluidly connected to an external sump 160 having a communication system 162 to transmit a signal indicating detection of a leak. The sumps 158, 160 may also have a pump (not shown) to return leaked fluid back into tank 100 or discharged to drain. In the event of a leak in the first liner 150, fluid enters a geotextile/geonet cavity formed by the geotextile/geonet layer 152 and is caught by the leak detection layer. Water from the internal sump 158 is preferably gravity fed to the external sump 160 which can activate a pump, preferably a solar pump, to return water to the tank 100 or to drain. The tank shown in Figure 4 comprises the flexible roof 200 mounted on the continuous wall 100 formed from the plurality of wall panels 1 10 to fluidly seal a cavity formed between the roof 200, the wall panels 1 10, and the floor 140. In some embodiments, the flexible roof 200 can float on the surface of a liquid in the tank. In these embodiments, no roof support structure is required. The flexible roof can comprise one or more folds and one or more ballast tubes, such as sand ballast tubes, to assist the flexible roof adapt to different levels of fluid in the tank.

[0035] With reference to Figure 7, the flexible roof 200 can be mounted on and secured to the continuous wall by any suitable fastening elements, such as anchor studs 170 passing through respective batten bars 172 and rubber gaskets 174 and into the wall panels 1 10. Such fastening arrangements can also pass through the first liner 150, the geotextile/geonet layer 152, the leak detection liner 154, and the cushioning geotextile layer 156 to secure these layers to the wall panels 1 10 of the continuous wall 100.

[0036] Figure 5 and 6 illustrates the tank, liner and leak detection system as shown in Figure 4 with the tank comprising other embodiments of the roof 200 mounted on the continuous wall 100 formed from the plurality of wall panels 1 10 to fluidly seal a cavity formed between the roof 200, the wall panels 1 10, and the floor 140. In the embodiment shown in Figure 5, the tank 10 comprises a roof support structure 202 to support the roof 200 spanning across the diameter of tank (for a circular tank) from wall to wall. The roof support structure 202 can comprise one or more substantially horizontal members 204 spanning from one side of the tank to the other side, or part thereof, depending on the size of the tank and the type of roof. The roof support structure 202 can also comprise one or more substantially vertical support members 205 extending between the one or more substantially horizontal members 204 of the roof structure and the outer portion of the roof 200. The tank 10 can comprise one or more roof support members 206 to support at least a portion of the roof 200 or the roof support structure 202. The support member 206 can be in the form of a support column. The support column can comprise a single central support column or a plurality of columns spaced apart within the cavity of the tank 10. The support column(s) may extend from the floor 140 to the roof 200 and/or to the roof support structure 202. In the embodiment shown in Figure 6, the roof 200 is in the form of a concrete roof formed from a plurality of concrete roof panels 208 supported by a plurality of support members 206 and the wall panels 1 10.

[0037] Advantageously, the permanent tank 10 can be constructed quickly and relatively cost effectively at a site in a modular and adaptable manner. It can be a permanent installation with casting of the panels 1 10 performed offsite. Potable water or waste liquids, such as effluent or industrial wastes, can then be stored in the permanent tank 10. The shape of the precast wall panels in conjunction with the cable tensioning system means that, in some embodiments, no additional frame or supports are required, reducing parts and footprint.

[0038] The tensioning system and abutting wall panels of the present invention eliminate the need for a wet joint of concrete poured onsite, which would require formwork, access to concrete and longer construction time lines, thus providing significant benefits over prior art permanent tanks. [0039] The roof covering the tank, be it fixed or flexible, addresses issues with evaporation and contamination. A flexible roof, for example, specifically a floating cover, provides an enhanced seal for the tank contents, thus reducing evaporation and contamination, improving water quality and reducing or eliminating the need for chemical treatment.

[0040] In this specification, adjectives such as first and second, left and right, top and bottom, and the like may be used solely to distinguish one element or action from another element or action without necessarily requiring or implying any actual such relationship or order. Where the context permits, reference to an integer or a component or step (or the like) is not to be interpreted as being limited to only one of that integer, component, or step, but rather could be one or more of that integer, component, or step etc.

[0041 ] The above description of various embodiments of the present invention is provided for purposes of description to one of ordinary skill in the related art. It is not intended to be exhaustive or to limit the invention to a single disclosed embodiment. As mentioned above, numerous alternatives and variations to the present invention will be apparent to those skilled in the art of the above teaching. Accordingly, while some alternative embodiments have been discussed specifically, other embodiments will be apparent or relatively easily developed by those of ordinary skill in the art. The invention is intended to embrace all alternatives, modifications, and variations of the present invention that have been discussed herein, and other embodiments that fall within the spirit and scope of the above described invention.

[0042] As used herein, an element or operation recited in the singular and proceeded with the word “a” or “an” should be understood as not excluding plural elements or operations, unless such exclusion is explicitly recited. Furthermore, references to “one embodiment” of the present disclosure are not intended to be interpreted as excluding the existence of additional embodiments that also incorporate the recited features.

[0043] In this specification, the terms ‘comprises’, ‘comprising’, ‘includes’, ‘including’, or similar terms are intended to mean a non-exclusive inclusion, such that a method, system or apparatus that comprises a list of elements does not include those elements solely, but may well include other elements not listed.

Claims

The claims defining the invention are as follows:

1. A permanent tank comprising: a plurality of precast wall panels arrangeable on a floor to form a continuous wall; a roof mounted on the continuous wall to fluidly seal a cavity formed between the roof, the wall panels, and the floor; and a tensioning system comprising one or more cables configured to extend around the continuous wall; wherein the wall panels and cable tensioning system are configured to retain abutting wall panels in an interference fit.

2. The permanent tank of claim 1 , wherein the roof is flexible or rigid.

3. The permanent tank of claim 1 or 2, further comprising a roof support structure to support at least a portion of the roof.

4. The permanent tank of any one of claims

to 3, wherein the wall panels are precast concrete panels.

5. The permanent tank of any one of claims

to 4, wherein the wall panels are substantially planar.

The permanent tank of any one of claims

to 5, wherein the wall panels have side walls at a transverse angle to the plane of the panel.

7. The permanent tank of claim 6, wherein the side walls are angled in opposite directions to form an isosceles trapezoid in a cross-section of the wall panel.

8. The permanent tank of any one of claims 1 to 7, wherein the wall panels comprise at least one channel that receives the one or more cables of the tensioning system.

9. The permanent tank of any one of claims 1 to 8, wherein each wall panel comprises a plurality of spaced apart channels.

10. The permanent tank of any one of claims 1 to 9, wherein a plurality of cables collectively extend around the continuous wall.

1 1 . The permanent tank of any one of claims 1 to 10, wherein at least one of the wall panels comprises a cable retainer configured to receive and retain a cable anchor at an end of the cable.

12. The permanent tank of any one of claims 1 to 1 1 , wherein each cable comprises a cable anchor at each end.

13. The permanent tank of any one of claims 1 to 12, further comprising a liner configured to fluidly seal the wall panels and a floor of the permanent tank.

14. The permanent tank of claim 13, wherein the liner comprises a leak detection system.

15. The permanent tank of claim 14, wherein the leak detection system comprises a leak detection layer fluidly connected to an outlet.

16. The permanent tank of claim 15, wherein the outlet is a sump with a pump configured to return fluid from the sump back into the permanent tank or to drain.

17. The permanent tank of any preceding claim, wherein the floor is selected from one of the following: an earthen floor; a reinforced concrete floor; a ring beam foundation.

18. A method of assembling a tank on a site, the method comprising the steps of: erecting a plurality of precast wall panels on a floor at the site to form a continuous wall; configuring one or more cables to extend around the continuous wall with; tightening the one or more cables to retain the plurality of wall panels in an interference fit; and constructing a roof over the continuous wall to fluidly seal a cavity formed between the roof, wall panels, and the floor.

19. The method of claim 18, further comprising the step of supporting the plurality of precast wall panels with temporary supports until the tensioning system is tightened to hold the wall panels in the interference fit.

20. The method of claim 18 or 19, further comprising the step of anchoring one or more cables in one or more recesses of at least one wall panel.

21 . The method of any one of claims 18 to 20, further comprising the step of passing one or more cables through channels in the wall panels.

22. The permanent tank of claim 3, wherein the roof support structure comprises one or more of the following: at least one substantially horizontal member spanning from one side of the tank to the other side, or part thereof; one or more support columns.

23. The permanent tank of any of claims 1 to 17 or 22, wherein each cable is internal to the wall panels, or partially external and partially internal to the wall panels.

24. The permanent tank of any of claims 1 to 17, 22 or 23, wherein the roof is flexible and can float on a surface of a liquid in the tank.