WO1998031898A1

WO1998031898A1 - Construction of liquid retaining structures

Info

Publication number: WO1998031898A1
Application number: PCT/AU1998/000012
Authority: WO
Inventors: Sharne Anthony Andree
Original assignee: Sharne Anthony Andree
Priority date: 1997-01-21
Filing date: 1998-01-13
Publication date: 1998-07-23
Also published as: AUPO468897A0

Abstract

A roofed storage structure such as a silo or water tank is constructed by forming a concrete base (1) on a ground surface and then forming on the base a reinforced concrete roof structure (6). A liquid retaining perimetral wall structure (8), surrounding and spaced from said roof structure (6), is then constructed on the base (1). A body of liquid is then introduced into the storage structure whereby flotation means associated with the roof structure (6) causes the roof structure (6) to be elevated to a desired height within the perimetral wall structure (8), the roof structure (6) then being secured in position by attachment to the perimetral wall (8) and/or upright roof support members (4) positioned within the storage structure.

Description

TITLE

CONSTRUCTION OF LIQUID RETAINING STRUCTURES

FIELD OF THE INVENTION

This invention is concerned with the construction of roofed storage

structures such as silos, liquid retaining structures such as water

reservoirs or the like.

Although the following description is illustrated by reference to

water reservoirs, it should be understood that the invention is not so

limited.

BACKGROUND OF THE INVENTION

In small towns or in rapidly growing urban areas it is common place

to use concrete water reservoirs of from 2 to 50 megalitres or even

greater as "header" or "surge" tanks to store water pumped from a remote

source. The stored water is then distributed to a specific community at a

generally constant head.

The economics of constructing such water reservoirs usually

favours on site construction of the reservoir base and side wall from

concrete with steel or aluminium roof structures being prefabricated at a

remote manufacturing facility and then transported to the reservoir site as

required.

Generally speaking very high construction costs mitigate against in-

situ construction of a concrete roof for such structures as erection and subsequent dismantling of formwork is highly labour intensive.

Although generally effective for their intended purpose, metal roof

structures for water reservoirs have a relatively short life span and high

maintenance costs due to corrosion in the metal sheeting and framework

comprised in the roof structure.

SUMMARY OF THE INVENTION

It is an aim of the present invention to overcome or alleviate at

least some of the disadvantages associated with prior art roofing systems

for concrete water reservoirs and to permit on site installation of a

concrete roof structure.

According to one aspect of the invention there is provided a

method for construction of a roofed storage structure, said method

comprising the steps of

forming a concrete base on a ground surface;

forming on said base a reinforced concrete roof structure;

erecting on said base a perimetral wall structure surrounding said

roof structure; and,

introducing a body of liquid into the storage structure whereby

buoyancy means associated with said roof structure elevates said roof

structure to a desired level for attachment to said wall structure.

Suitably the base comprises steel reinforced concrete.

If required the base may be pre-stressed and/or post-tensioned. The base may include liquid inlet and/or outlet ports.

Suitably a release agent is located between said base and said

roof structure.

If required, the base may include spaced locating means for upright

roof support members.

The reinforced concrete roof structure may be pre-stressed and/or

post-tensioned.

If required the roof structure may include one or more apertures.

Suitably the roof structure includes a plurality of spaced column

apertures aligned with said locating means.

The roof structure may comprise an integrally formed roof member

or it may comprise two or more separate roof members.

The perimetral wall structure may comprise an integral wall or a

plurality of interconnecting wall panels.

If required the perimetral wall structure may include a liquid

impervious membrane over an inner surface thereof.

If required the inner wall surface may be spaced from the radially

outer edge of said roof structure.

Suitably upright roof support members are located in said spaced

locating members via respective column apertures in said roof structure.

The buoyancy means associated with said roof structure may be

located above and/or below said roof structure.

If required said buoyancy means may comprise a body of low density material, one or more expandable chambers, one or more closed

chambers or any combination thereof.

Preferably the buoyancy means comprises a liquid resistant upright

barrier extending from an upper surface of the roof structure adjacent the

outer edge of said roof structure.

Where apertures are formed in said roof structure the buoyancy

means also comprises a liquid resistant upright barrier extending from the

upper surface of the roof structure about each said aperture.

If required one or more of said liquid resistant barriers may be

integrally formed with said roof structure.

Preferably said one or more liquid resistant barriers are detachably

securable to said roof structure.

Suitably, said roof structure is supported in an elevated position by

connecting members extending between said perimetral wall structure

and said roof structure.

Preferably said roof structure is supported by upright roof support

members extending between said roof structure and said base.

Most preferably said roof structure is supported by both connecting

members with said wall structure and said upright members.

According to another aspect of the invention there is provided a

roofed storage structure whenever made in accordance with the aforesaid

method.

According to yet another aspect of the invention there is provided a method of roofing a storage structure.

BRIEF DESCRIPTION OF THE DRAWINGS

In order that the invention may be more fully understood and put

into practical effect, a preferred embodiment will now be described with

reference to the accompanying drawings in which:-

FIG 1 illustrates schematically a plan view of a partially completed

water reservoir.

FIG 2 illustrates a cross sectional view through A-A in FIG 1.

FIG 3 illustrates a partially elevated roof structure.

FIG 4 illustrates a completed water reservoir.

DETAILED DESCRIPTION OF THE DRAWINGS

In FIG 1 a water reservoir is constructed by first pouring a

reinforced concrete base slab 1 on a prepared ground surface.

A water inlet/outlet duct 2 is located beneath the level of the base

slab 1 with an inlet/outlet port 3 in the slab communicating with the duct 2.

In preparing the base slab 1 , locating sockets (not shown) are

formed in the surface of the slab to receivably locate upright roof support

columns 4.

A layer of polyethylene sheeting or some other release agent is

then applied to the upper surface of base slab 1 before placing formwork

(not shown) to define the outer perimeter 5 of roof structure 6 and the perimeter of column apertures 7. After placement of steel reinforcing

mesh within the area defined by the formwork, together with any post

tensioning conduits, the roof structure 6 is then poured.

When the roof structure is cured, the formwork is removed and any

post-tensioning cable system are tensioned.

A wall structure 8 is then formed on the base 1 leaving a small gap

9 between the edge 5 of roof structure 6 and the inner surface of wall 8.

The wall structure may be formed by any conventional means suitable for

water reservoirs.

Typically the wall structure comprises upright panels with

interlocking edge joints and a waterstop located within the joint. The wall

structure is reinforced with post tensioned cables located within the panel

bodies or exteriorally of the wail surface to provide structural integrity.

Before erecting the outer wall however, it is convenient although

not essential to erect the support columns 4 for the roof structure 6. The

support columns are located into the locating sockets (not shown) formed

in the base slab 1 and grouted for permanent retention. At this juncture

the water reservoir structure is as shown schematically in FIG 2.

After erection of the outer wall 8 is completed, a waterproof steel

sheet barrier 10 is erected about the periphery of the roof structure and

secured thereto in a watertight manner by brackets and a waterproofing

gasket if necessary. Similar barriers 11 surround the column apertures 7

to form a "boat-like" structure. Water is then introduced into the tank interior via conduit 2 to iniet

port 3 which opens between the upper surface of base 1 and the lower

surface of roof slab 6.

As the water enters it "cracks" the (usually) airtight seal between

the base and roof slabs and flows around the outside of barrier 10 and the

inside of barriers 11 until the mass of the volume of fluid displaced equals

the mass of the roof structure and associated waterproof barriers. At this

juncture the roof slab begins to float and is elevated as the water level

rises within the tank. If difficulty is encountered in breaking adhesion

between the base and roof slabs, high pressure compressed air may be

introduced into inlet port 3 to assist initial separation.

When the roof reaches a desired height above the base 1 it is

secured to outer wall 8 by pins (not shown) brackets or the like. Similarly,

the roof structure 6 is supportively connected to columns 4 and for this

purpose ties, brackets or exposed reinforcing steel 12 as shown in FIG 1

may be employed.

After mechanical fixing of the roof structure 6 to the wall structure 8

and columns 4, the aperture between the roof structure and the wall is

filled with cement mortar or the like as are the apertures surrounding the

columns 4.

A manhole (not shown) can be formed in the roof slab 6 during its

initial construction for access to the interior of the reservoir after

completion. It will be readily apparent to persons skilled in the art that many

modifications and variations may be made to the invention without

departing from the spirit and scope thereof.

For example, when the roof is elevated to a position where the

lower surface thereof is above the tops of columns 4, the roof structure

may be rotated to misalign apertures 7 with columns 4.

After releasing the water in the reservoir the roof structures settles

onto and is supported by the columns. The peripheral gap and apertures

7 may then be sealed in any convenient manner.

Claims

1. A method for construction of a roofed storage structure, said

method comprising the steps of

forming a concrete base on a ground surface;

forming on said base a reinforced concrete roof structure;

erecting on said base a liquid retaining perimetral wall structure

surrounding said roof structure; and,

introducing a body of liquid into the storage structure whereby

buoyancy means associated with said roof structure elevates said roof

structure to a desired level for attachment to said wall structure.

2. A method as claimed in claim 1 wherein the base comprises steel

reinforced concrete.

3. A method as claimed in claim 2 wherein the base is pre-stressed

and/or post-tensioned.

4. A method as claimed in any preceding claim wherein the base

includes liquid inlet and/or outlet ports.

5. A method as claimed in any preceding claim wherein a release

agent is located between said base and said roof structure.

6. A method as claimed in any preceding claim wherein the base

includes spaced locating means for upright roof support members.

7. A method as claimed in any preceding claim wherein the reinforced

concrete roof structure is pre-stressed and/or post-tensioned.

8. A method as claimed in any preceding claim wherein the roof structure includes one or more apertures.

9. A method as claimed in claim 8 wherein the roof structure includes

a plurality of spaced column apertures aligned with said locating means.

10. A method as claimed in any preceding claim wherein the roof

structure comprises an integrally formed roof member or two or more

separate roof members.

11. A method as claimed in any preceding claim wherein the perimetral

wall structure comprises an integral wall or a plurality of interconnecting

wall panels.

12. A method as claimed in any preceding claim wherein an inner wall

surface is spaced from the radially outer edge of said roof structure.

13. A method as claimed in any preceding claim wherein upright roof

support members are located in said spaced locating members via

respective column apertures in said roof structure.

14. A method as claimed in any preceding claim wherein the buoyancy

means associated with said roof structure is located above and/or below

said roof structure.

15. A method as claimed in any preceding claim wherein said

buoyancy means comprises a body of low density material, one or more

expandable chambers, one or more closed chambers or any combination

thereof.

16. A method as claimed in claim 15 wherein the buoyancy means

comprises a liquid resistant upright barrier extending from an upper surface of the roof structure adjacent the outer edge of said roof structure.

17. A method as claimed in any one of claims 8 to 16 wherein the

buoyancy means also comprises a liquid resistant upright barrier

extending from the upper surface of the roof structure about each said

aperture.

18. A method as claimed in claim 17 wherein one or more of said liquid

resistant barriers is integrally formed with said roof structure.

19. A method as claimed in claim 17 or claim 18 wherein said one or

more liquid resistant barriers are detachably securable to said roof

structure.

20. A method as claimed in any preceding claim wherein said roof

structure is supported in an elevated position by connecting members

extending between said perimetral wall structure and said roof structure.

21. A method as claimed in any preceding claim wherein said roof

structure is supported by upright roof support members extending

between said roof structure and said base.

22. A method as claimed in any one of claims 13 to 19 wherein said

roof structure is supported by both connecting members with said wall

structure and said upright roof support members.

23. A method as claimed in any preceding claim wherein said

perimetral wall structure includes a liquid impervious membrane over an

inner surface thereof.

24. A roofed storage structure whenever made in accordance with the method of any one of claims 1 to 23.

25. A method for construction of a roofed storage structure

substantially as hereinbefore described with reference to the

accompanying drawings.

26. A roofed storage structure substantially as hereinbefore described

with reference to the accompanying drawings.