AU2327301A - Improvements in precast pit members - Google Patents

Description

r P/00/011 Regulation 3.2

AUSTRALIA

Patents Act 1990

ORIGINAL

COMPLETE SPECIFICATION STANDARD PATENT Invention Title: "IMPROVEMENTS IN PRECAST DRAINAGE CHANNELS" The following statement is a full description of this invention, including the best method of performing it known to me/us: 2 This invention is concerned with improvements or modifications to precast drainage channels, the subject of our co-pending patent application 71802/00.

The invention is concerned particularly with the application of the underlying structural concept of our co-pending patent application 71802/00 to other drainage or like products utilised in storm water systems sewerage systems including drainage sumps and pits, access pits and the like.

In the in-situ construction of drainage channels, drainage pits or access pits having a manhole cover or the like, it is known to form a grate or cover locating recess by casting a prefabricated steel locating member into the upper surface of a concrete pit body or channel body while the concrete is still fluid. Typically, the retaining member will have a lip or small retaining lugs to prevent withdrawal of the retaining member from the pit or channel body after is has cured.

While generally effective for their intended purpose, such ingillie situ formed pits an channels are very expensive to construct due to high labour content in erection and dismantling of formwork and the need for heavy lifting equipment for formwork, concrete mixers and transport equipment for on-site usage.

In an endeavour to reduce the costs of drainage pits and channels and access pits in commercial or industrial environments, of recent times it is becoming increasingly prevalent to use domestic 3 grade precast pits or channels, often with disastrous results.

Typically these precast members have only recessed support ledges in the walls to support a grate or cover.

In heavy traffic or high load traffic environments, these domestic pits or channels are prone to two main modes of failure.

One failure mode occurs as a result of vertically directed load forces through the steel grate being transferred to the concrete support ledges via relatively thin peripheral grate frame members and load bearing cross members. This causes wear and/or cracking in the support ledges with a risk of collapse of the grate under load.

Another failure mode arises from the transverse movement of the grate across the support ledges as a result of horizontally directed forces imposed by the friction of vehicle tyres, particularly under acceleration or deceleration. This quite violent transverse movement °o results in an impact between the upper portions of the side wall and the grate member with resultant cracking in the floor of the drainage •channel.

The present invention aims to overcome the disadvantages Selassociated with prior art commercial or industrial drainage channel or pit construction and/or otherwise provide consumers with an effective S. alternative.

As used hereinafter, the expression "pit member" includes within its scope drainage channels which may or may not be used in 4 conjunction with a drainage pit or sump.

According to one aspect of the invention there is provided a pit member comprising:a body portion adapted to support a cover 8in an upper aperture thereof, said body portion being formed of a flowable, curable cementitious composition; spaced upright metal reinforcing members extending into at least opposite side walls of said body portion; and, angular cross section cover support members extending along respective upper regions of said opposed side walls, said reinforcing members being secured to undersurfaces of respective cover support :..members.

The body portion may be selected from a drainage channel, a 15 drainage pit, an access pit or like structural member, with or without .i a floor therein.

!tllt: "If required angular cross section cover support members may extend about the periphery of said cover.

The cover support members may comprise discrete support elements or an integrally formed member.

Suitably, the cover is a grate member or a full closure member.

Suitably said metal reinforcing members extend at least partially across a floor, when present, of said body portion.

If required, said body portion may include one or more steel reinforcing members extending transversely of said upright reinforcing members.

The steel reinforcing members may comprise steel rod-like members and/or steel mesh.

Suitably the angular cross section cover support members each comprise an inwardly directed base web and an upright flange.

If required, the cover support members may be recessed into respective upper regions of said side walls.

Preferably the cover support members are mounted on respective upper surfaces of said side walls.

The cover support members may be adapted to include lifting means.

Suitably the lifting means comprises at least one aperture in each upright flange.

.i If required the pit member may be adapted in use to resist transverse movement of the cover in said cover support members.

Preferably said cover support members include cover locking ~means.

According to another aspect of the invention there is provided a method of forming a pit member, said method comprising the steps of:locating, within a mould having a hollow cavity, steel reinforcing members secured to respective cover support members; and introducing into said mould a flowable, curable cementitious composition to encapsulate said steel reinforcing members and whereby said cover support members form cover support ledges adjacent respective upper edges of side walls of said pit member.

Suitably said cover support members are removably secured in said mould cavity by fastening means extending through apertures in respective base webs.

Preferably said apertures are screw threaded.

In order that the invention may be more fully understood and put into practical effect, preferred embodiments of the invention will now be described with reference to the accompanying drawings in which:- 15 FIG 1 shows a phantom view of the drainage channel of FIG 1.

FIG 2 shows a perspective view of a drainage channel according to the invention.

FIG 3 is an enlarged part cross sectional view of a drainage ~channel according to the invention.

FIG 4 shows installation of drainage channels according to the o. invention.

FIG 5 shows part exposed view of the installation of a drainage 7 FIG 6 shows a cross sectional view of the pit of FIG In FIG 1 the pit member 1 comprises a cast concrete drainage channel body 2 having a base 3 and opposed upright side walls 4.

Angle iron grate support members 5 extend along the upper edges 6 of side walls 4 to receivably locate a steel grate (not shown).

Steel reinforcing rods 7 are secured to the undersurface of the horizontal webs 8 of members 5 by welding or the like and extend within the side walls 4 and at least partially across the width of the base 3. A further reinforcing rod 9 extends longitudinally within base 3.

Adjacent opposite ends of support members 5 are threaded apertures 10, the purpose of which will be described later.

Located in the upright flanges 11 of support members 5 are diagonally opposed apertures 12 to assist in lifting and manipulation of the drainage channels during transportation and installation.

If required, support members 5 may be fabricated as an oo.o.i •integrally formed rectangular channel, the transverse end members (not shown) providing additional transverse reinforcing between o•opposed walls 4. Still further, the integrally formed rectangular grate support member may include additional reinforcing members (not shown) extending transversely between opposed side members FIG 2 shows a perspective view of the pit member 1 of FIG 1 wherein the lower regions 13 of side walls 4 are recessed to enable 8 the channels to be stacked with the recessed lower region of a channel being securely nested within the support members In the manufacture of the drainage channels according to the invention, a mould having an inverted U-shaped cavity is employed.

The mould includes detachable or hinged side walls for ease of removal of the finished channels and also to locate the support members 5 with attached reinforcing rods 7 therewithin.

The base of the mould includes apertures which align with apertures 10 in the support members whereby the support members can be removably fastened into the mould base by threaded bolts which engage with threaded apertures After securing reinforcing rods 7 to longitudinal rod 11 by wire twitches or the like, the mould is filled with a concrete composition of required strength and the mass is allowed to cure.

15 Before removal of the cured channel from the mould, the bolts securing support members 5 are removed and the side walls of the mould removed or opened to facilitate removal of the channel.

loll FIG 3 shows an enlarged partial cross sectional view of an installed drainage channel.

The side wall 4 of channel 1 abuts against a cast concrete :paving slab 14 with the upper edge of flange 11 flush with the surface 15 of slab 14.

A conventional fabricated steel grate with a peripheral frame 9 16, transverse load bearing members 17 and longitudinal stabilizers 18 has an apertured mounting flange 19 secured at the base of each inner corner. A bolt 20 locks the grate at its corners into the support members 5 via the threaded apertures 10 therein and the free end of the bolt is locked in a cavity 21 formed by the bolts which located the support members 5 in the base of the mould.

As can be seen from FIG 3, the grate is firmly supported on the webs 8 of support members 5 and is restrained by bolts 20 against vertical movement, the bolts also acting as a deterrent against theft.

Any vertically directed force vectors from traffic loads are distributed over the face of webs 8 and thereafter are distributed within the steel reinforced channel body via reinforcing rods 7 and compression in the side walls 4.

Horizontally directed force vectors from traffic loads are borne on the opposed side walls 4 simultaneously via bolts 20 under shear and these vectors are also borne by an edge face of an abutting •pavement slab 15 under compression. The side walls 4 are thus not exposed individually to horizontal force vectors which might *I I otherwise cause cracking or fracture in the base 3 of the channel.

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FIG 4 shows the installation of drainage channels according to el the invention.

Utilising the lifting apertures 12 on opposite flanges of support members 5, workers 22 using hooked tools 23 can easily lift and manipulate the channels 1 into position against the edge of a pavement slab 15. The narrow upstanding flanges of support members 5 abut neatly with the surrounding pavement slab.

Ideally, the channels 1 are placed on a concrete footing 24 to avoid subsidence. Thereafter when the required number of channels have been positioned end to end to form a continuous channel of desired length, a further concrete paving slab can be poured against the exposed side walls of the channels.

FIG 5 shows a drainage pit member 30 installed in a concrete paved driveway traffic apron or roadway.

Drainage pit 30 is formed as a generally rectangular box 31 with a floor 32 and an open top 33. Located about the periphery of box 31 is a rectangular cover support member 34 fabricated from 0000 channel section steel. Support member 34 is secured into the side *0 0 15 walls 31a of box 31 by upright reinforcing members (not shown) in a 0 0• manner similar to the drainage channels previously described.

000000 The prefabricated pit member 30 is simple located in an 0000 0 *ooo excavated hole in the earth 35 with portion of the pit extending *0ooabove the surface 36 of the earth. A layer of concrete 37 is then 0000 poured over the earth surface 36 and, using the upper edge 38 of cover support member 34 as a datum, the concrete pavement is 0o finished by trowelling or the like to a desired level so that water accumulating on the surface of concrete layer 37 is constrained to 11 drain into pit 30 via grate 39. Pit 30 is coupled to a drainage conduit (not shown) via access aperture It will be readily apparent to a skilled addressee that many modifications and variations may be made to the invention without departing from the spirit and scope thereof.

For example pit members according to the invention may be formed with the angle iron support members located on longitudinally extending recessed shoulders on the inner faces of walls 4. Similarly, pit members may be of circular section in plan view.

FIG 6 shows a cross sectional view of the pit 30 of FIG 5 and for the sake of simplicity, like reference numerals are employed for like features.

FIG 6 clearly shows the location of reinforcing rods 41 in the side walls 31a of pit member 30. If required, the reinforcing rods oo 15 could extend over the entire height of side walls 31a, and, as shown in FIG 1, they could also extend into the floor 32, with or without .oeoo •longitudinally extending rods (not shown) as in FIG 1.

Another feature of the pits according to the invention is the o.

ooprovision of "knock-out" apertures 42 of differing sizes for coupling to drainage on other conduits of a predetermined size. As the pit :members according to the invention may be used for "dry" applications such as junction boxes for electrical and communications conduits, each side wall of pit member 30 or opposed pairs of side 12 walls may include "knock-out" apertures 42 to suit conduit sizes for a variety of applications.

In yet another adaption, the pit members 30 shown generally in FIGS 5 and 6 may be formed without a floor. Such floorless pits may be used as drainage pits in conjunction with a rubble drain or, for say, sewerage installations, a floorless pit may be located on top of a floored pit as a riser with the lower peripheral edge (not shown) of the floorless pit located in the support member 34 of the lower pit.

Throughout this specification, unless the context requires otherwise, the word "comprise" and variations such as "comprises" or "comprising", will be understood to imply the inclusion of a stated integer or group or group of integers or steps but not the exclusion of any other integer or group of integers.

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Claims (25)

1. A pit member comprising:- a body member adapted to support a cover in an upper aperture thereof, said body portion being formed of a flowable, curable cementitious composition; spaced upright metal reinforcing members extending into at least opposite side walls of said body portion; and, angular cross section cover support members extending along respective upper regions of said opposed side walls, said reinforcing members being secured to undersurfaces of respective cover support members.

2. A pit member as claimed in claim 1 wherein the body portion is formed as a drainage channel, a drainage pit or an access pit. S:

3. A pit member as claimed in claim 2 wherein said body portion 0. is formed with an open base.

A pit as claimed in any one of claims 1 to 3 wherein said cover support members extend about the periphery of said cover.

5. A pit as claimed in any preceding claim wherein said cover support members comprise discrete support elements. 20

6. A pit as claimed in any one of claims 1 to 4 wherein said cover support members are fabricated as an integrally formed member.

7. A pit as claimed in any preceding claim wherein said cover member is a grate or a full closure member.

8. A pit member as claimed in any preceding claim wherein said metal reinforcing members extend at least partially across a floor, when present, of said body portion.

9. A pit member as claimed in any preceding claim wherein said pit member includes one or more steel reinforcing members extending transversely of said upright reinforcing members.

A pit member as claimed in claim 9 wherein the steel reinforcing members comprise steel rod-like members.

11. A pit member as claimed in claim 9 wherein said metal reinforcing members and/or said steel reinforcing members comprise a steel mesh.

12. A pit member as claimed in any preceding claim wherein the angular cross section cover support members each comprise an inwardly directed base web and an upright flange. .i

13. A pit member as claimed in any preceding claim wherein the .OleOi cover support members are recessed into respective upper regions of said side walls. i

14. A pit member as claimed in any one of claims 1 to 12 wherein the cover support members are mounted on respective upper surfaces g 20 of said side walls.

1 5. A pit member as claimed in any preceding claim wherein the grate support members include lifting means.

16. A pit member as claimed in claim 15 wherein the lifting means 16 comprises at least one aperture in each upright flange.

17. A pit member as claimed in any preceding claim adapted, in use, to resist transverse movement of the cover in said cover support members.

18. A pit member as claimed in any preceding claim including a cover locking means.

19. A pit member as claimed in claim 18 wherein said cover locking means comprises at least one threaded aperture in at least one cover support member to receivably locate a screw threaded fastener.

20. A method of forming a pit member, said method comprising the steps of:- locating, within a mould having a hollow cavity, steel reinforcing members secured to respective cover support members; "and introducing into said mould a flowable, curable cementitious o 0*0 composition to encapsulate said steel reinforcing members and whereby said cover support members form cover support ledges S. .adjacent respective upper edges of side walls of said pit member.

21. A method as claimed in claim 20 wherein said cover support .0 *0 20 members are removably secured in said mould cavity by fastening means extending through apertures in respective base webs.

22. A method as claimed in claim 21 wherein said apertures are screw threaded. 17

23. In combination, a pit member according to any one of claims 1 to 19 and a cover member.

24. A pit member substantially as herebefore described with reference to the accompanying drawings.

25. A method of forming a pit member substantially as hereinbefore described with reference to the accompanying drawings. PATENT PRODUCTS AUSTRALIA PTY LTD By their Patent Attorneys FISHER ADAMS KELLY ee So