WO2002101159A1

WO2002101159A1 - Lined manhole base section

Info

Publication number: WO2002101159A1
Application number: PCT/AU2002/000750
Authority: WO
Inventors: Shane Wormall
Original assignee: Blueport Nominees Pty Ltd
Priority date: 2001-06-11
Filing date: 2002-06-11
Publication date: 2002-12-19
Also published as: AUPR556201A0

Abstract

A manhole base section (10) includes a pre-formed corrosion resistant liner (50) and a concrete body (12). The body (12) has a top (14), a base (16) and a side wall (18). The top (14) is provided with an opening (20) leading into a cavity (22) that extends into the body (12). The cavity (22) is divided into a recess portion (24) and a bowl portion (26). The bowl portion (26) is preferably an inverted dome shape. The pre-formed liner (50) is formed of polyvinyl chloride plastics (PVC) material. It is received through the opening (20) of the concrete body and married with the internal surfaces of the concrete body (12). A first pipe (42) extends from the side wall (18) to the bowl portion (26) of the concrete body. The first pipe (42) opens into the bowl portion (26) at opening (44). The opening (44) is higher relative to the drainage point (34). A second pipe (46) also extends from the side wall (18) into the bowl portion (26) of the concrete body. The second pipe (46) opens into the bowl portion at opening (48), which is positioned at or adjacent to the drainage point 34 so that fluid or slurry flows from the drainage point (34) into the second pipe (46). The opening (48) of the second pipe is lower than the opening (44) of the first pipe. The position of the pipes relative to one another may be provided at any desired angle. A simplified manufacturing process is also described.

Description

LINED MANHOLE BASE SECTION

FIELD OF THE INVENTION

The present invention relates to a manhole base section for connection of underground pipes.

BACKGROUND TO THE INVENTION

Underground pipes, particularly those that carry sewerage often require inspection or maintenance. Access to the pipes is provided by a manhole base section that interconnects the underground pipes. The base section supports a riser that is covered by a manhole cover. This allows access to the base section for inspection or maintenance of the base section or the pipes.

Currently, manhole base sections are provided with a generally cylindrical wall surrounding a cavity into which the pipes connect. So as to enhance the flow of fluid or slurry from an inlet pipe to an outlet pipe a channel is fabricated into the base section. The channel accommodates directional flow of fluid or slurry from the incoming to the outgoing pipe. This fabrication method is labour intensive arid thus expensive. Furthermore, it provides difficult working conditions for the person fabricating the channel due to the cramped space. ^"Where the diameter of the inlet and outlet pipes exceed 300mm, the construction of the manhole base sections have been previously limited by the corrosive property of sewage passing through the pipes.

SUMMARY OF THE INVENTION The present invention was developed with a view to providing an improved manhole base section that increases resistance to the corrosive properties of sewage, and allows for easier access to outlet and inlet pipes for inspection and maintenance.

According to one aspect of the present invention there is provided a process for manufacturing a manhole base section, the process including the steps of: providing a pre-cast corrosion resistant liner, the liner including a bowl shaped portion; providing a mold shaped to cast the base section so that the base section includes a base, at least one side, a top, and a bottom, the top including an opening leading to a cavity having a bowl portion; placing the liner into the mold so that the bowl shaped portion of the liner lines the bowl portion of the cast base section; filling the mold with concrete and allowing the concrete to cure.

Preferably, the process further includes a step of coupling a pipe to the bowl shaped portion of the liner, prior to filling the mold with concrete, whereby when the concrete is cured the base section is provided with a pipe extending from the bowl shaped portion. Preferably a hole is cut in the liner to allow fluid communication between the inside of the bowl shaped portion and the pipe.

According to a further aspect of the present invention there is provided a manhole base section, the base section manufactured by a process described above.

Preferably the body of the manhole base section includes a first pipe that extends from the side into the bowl portion and a second pipe that extends from the side of the base into the bowl portion, whereby in use a fluid or slurry may pass from the first pipe to the second pipe via the bowl portion.

According to another aspect of the present invention there is provided a manhole base section for connection to underground pipes, the base section including: a body, the body including a base, at least one side and a top; the top including an opening leading to a cavity extending into the base from the opening, the cavity having a bowl portion extending into the body, the bowl portion having a sloped wall so as to provide a sump, and the bowl portion being lined with a corrosion resistant liner; wherein a first pipe extends from the side into the bowl portion and a second pipe extends from the bowl portion to the side or the base, whereby, in use, fluid or slurry passes from the first pipe to the second pipe via the bowl portion. Preferably the corrosion resistant liner is manufactured from pre-cast PVC. Preferably the liner is provided with projections to facilitate mechanical bonding to the concrete base.

Preferably, the second pipe opens into the bowl portion at or adjacent to a drainage point of the sump. Further pipes may extend from the side into the bowl portion, whereby fluid or slurry from the further pipes may pass through the bowl portion to the second pipe.

Preferably, the body is shaped to provide a ledge recessed inwardly from the top by a ledge recess portion, whereby the opening provides access to the ledge and the cavity for inspection or maintenance of the base section. Preferably, the bowl portion extends from the ledge further into the body.

Preferably, the bowl portion is an inverted dome shape.

In one embodiment the pipes are bonded to the pre-cast liner then cast into the concrete body. In a second embodiment, holes to receive the pipes are cored into the concrete body after curing.

Preferably, the holes are formed in the body at an angle so that the pipes passing through the holes may be disposed at a desired angle relative to one another. Alternatively, the pipes are cast in the body at a desired angle relative to one another.

Preferably, the top includes a riser recess for recessing a riser that extends upwardly from the base section to allow access to the base section for inspection or maintenance. Preferably, the ledge slopes inwardly toward the bowl section. Preferably, the ledge recess portion includes a wall that is sloped inwardly towards the bowl section.

Preferably, the first pipe opens into the bowl portion at a relatively higher height to where the second pipe opens into the bowl portion. Preferably, the body is generally cylindrical in shape. Alternatively, the body is generally frustoconical in shape. Preferably, the curved surface of the cylinder or frustocone forms the side.

BRIEF DESCRIPTION OF THE DRAWINGS

In order to provide a better understanding of the nature of the present invention, a preferred embodiment of the manhole base section will now be described in detail, by way of example only, with reference to the accompanying drawings, in which: Figure 1 is a schematic side view representation of the base section of a preferred embodiment of the manhole base section in accordance with the present invention; Figure 2 is a top view of the base section of Figure 1 ;

Figure 3 is a side view of a base section of another preferred embodiment of the manhole base section in accordance with the present invention; and

Figure 4 is a top view of the base section of Figure 3.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Referring to Figure 1, there is shown a manhole base section 10 that includes a pre- formed corrosion resistant liner 50, and concrete body 12. The body 12 has a top 14, a base 16 and a sidewall 18. The concrete body 12 has a generally frustoconical external shape with the curved surface forming the sidewall 18. The base 16 of the body 12 is larger in area than the top 14. The top 14 of the body 12 is provided with an opening 20 leading into a cavity 22 that extends into the body 12. The cavity 22 is divided into a recess portion 24 and a bowl portion 26. A lower part of the bowl portion 26 forms a sump.

A sidewall 28 and ledge 30 boarder the recess portion 24. The sidewall 28 is directed substantially downwardly from the top 14 and slopes slightly inwardly until it meets the ledge 30. The ledge 30 is substantially horizontal, although it slopes slightly downwardly towards the bowl portion 26. The bowl-portion 26 is preferably an inverted dome shape. The bowl portion 26 is defined by a bowl wall 32. The bowl wall 32 is sloped so that the bowl portion 26 is provided with a single drainage or collection point 34.

The periphery of the top 14 forms a lip 36 within which there is provided a riser recess 38. The riser recess 38 extends inwardly from the lip 36 to a riser ledge 40. The riser ledge 40 is provided so that a riser (not shown) may sit on the ledge 40 within the riser recess 38, so as to provide passage to the manhole to allow access to the base section for inspection or maintenance.

The pre-formed liner 50 of this embodiment is formed of polyvinyl chloride plastics (PVC). It is received through the opening 20 of the concrete body and marries with the internal surfaces of the concrete body 12. The liner therefore has a cavity 22' divided into a recess portion 24' and a bowl portion 26'. A lower part of the bowl portion 26' forms a sump. A sidewall 28' and ledge 30' of the liner 50 boarder the recess portion 24'. The ledge 30' is substantially horizontal, although it slopes slightly downwardly towards the bowl portion 26'. The bowl portion 26' is preferably an inverted dome shape. The bowl portion 26' is defined by a bowl wall 32'. The bowl wall 32' is sloped so that the bowl portion 26' is provided with a single drainage or collection point 34'. Liquid within the bowl moves, under the force of gravity, down the sloping bowl walls 32' to a drainage point 34*.

A first pipe 42 is shown extending from the sidewall 18 to the bowl portion 26 of the concrete body and 26' of the PVC liner. The pipe is PVC welded to the liner. The pipe is also in fluid communication with the inside of the bowl portion 26'. The first pipe 42 is slightly downwardly sloping so as to encourage, under the influence of gravity, the flow of fluid or slurry within the pipe into the bowl section 26' of the PVC liner. The first pipe 42 opens into the bowl portion 26' at opening 44. The opening 44 is higher relative to the drainage point 34, so that fluid or slurry from the first pipe 42 flows down the bowl wall 32' of the PVC liner to the drainage point 34'. A second pipe 46 also extends from the sidewall 18 into the bowl portion 26 of the concrete body and 26' of the PVC liner. The second pipe 46 has a downward slope leading from the bowl portion of the PVC liner 34' so that fluid or slurry is encouraged to flow, under the influence of gravity, from the bowl portion 26' out through the second pipe 46. The second pipe is also welded to the liner. The second pipe 46 opens into the bowl portion at opening 48.

The opening 48 is positioned at or adjacent to the drainage point 34' of the PVC liner so that fluid or slurry flowing down the bowl wall 32' of the PVC liner to the drainage point 34' will then flow on from the drainage point 34' into the second pipe 46. The opening 48 of the second pipe is thus lower than the opening 44 of the first pipe. It is envisaged that an alternative may be to provide the opening 46 at the base of the drainage point so that the second pipe 42 in beneath the bowl portion 26'. However, this embodiment is less preferred as it may require a bend in the pipe 46.

Referring to Figure 2, it can be seen that the pipes are disposed relative to one another at an angle 9 which is approximately 180°. The position of the pipes relative to one another may be provided at any desired angle. Common angles Q will be 30°, 45°, 60°, 90°, 135° and 180°. Additional pipes may be added leading from the sidewall 18 through the bowl portion 26 of the concrete body and into the bowl portion 26' of the PVC liner.

If additional pipes are added, providing inlets to the bowl portion 26' of the PVC liner, they should always be provided at a height greater than the opening 48 of the second pipe so that liquid or slurry always flows from the inlet pipe/s toward the drainage point 34' and then out through the second pipe 46.

Holes may be bored through the body to provide a passage for the pipes. If the pipes are required to be at a particular non-standard angle they may either be precast into the concrete or holes for the pipes may be precast or the holes may be cored so that the pipes may be inserted. Otherwise set angled base sections may be prefabricated and stored ready for later use.

Referring to Figures 3 and 4, this alternative form of base section has the bowl portion divided into a semi-hemispherical inlet portion 54 and a funnel shaped outlet portion 56. The inlet portion 54 is defined by the hemispherical wall 32 that is sloped to provide collection point 34. The collection point 34 is at an interface with the outlet portion 56. The outlet portion 56 is defined by opposite walls that are disposed at an acute angle to one another and a curved channel shaped bottom wall as can be seen most clearly in Figure 4. The fluid at the drain point 34 is channelled between the opposed walls 52, through the channel shaped bottom wall to outlet pipe 46. The shape of the bowl portion 46' of the liner 50 is of a corresponding shape to the bowl shaped portion 26. That is, the bowl portion 26' of the liner includes a hemispherical inlet portion 54' and a funnel shaped outlet portion 56'. The wall of the hemispherical inlet portion is defined by the hemispherical wall 34' and the shape of the outlet portion 56' is defined by opposed walls 52' that are disposed at an acute angle to one another and a curved channel shaped bottom wall. The liner may also be provided with an outlet tube section 58' for connection to the outlet pipe 46. The tube section 58' connects the outlet of the outlet portion 56' to the outlet pipe 46.

The method of manufacture of the manhole base section is as follows. A corrosion resistant liner 50 is vacuum molded from PVC. Another suitable technique made be used to manufacture the liner 50. The liner is then placed on a mold shaped to cast the base section 10. At least the bowl portion 26' of the liner will coincide with the bowl portion 26' of the cast base section. The liner is generally in an inverted orientation on the mold for ease of casting. Thus the mold will have an upwardly projecting dome shape that will form the bowl portion in the cast bowl portion. The mold is then filled with concrete and the concrete allowed to cure. The cast base section is removed from the mold, with the liner bonded to the inside of the cast base section.

To assist in bonding projections may be provided in the liner so that the liner is mechanically connected to the cast concrete.

It is sometimes desirable to have one or more pipes pre-cast into the base section. In this instance, the pipes may be coupled to the bowl shaped portion of the liner by PVC welding prior to filling the mold with concrete. Once attached, the concrete is then poured into the mold. A hole may be cut in the liner to allow fluid communication between the inside of the bowl shaped portion and the pipe either before casting, or after casting, on-site.

The method of use and operation of the present invention will now be described with reference to the accompanying drawings.

The manhole base section is positioned within the ground. The inlet pipes are connected as the first and additional pipes, and the second pipe 46 is provided as an outlet pipe. The outlet pipe may be larger in diameter than the first pipe and additional pipes so as to allow adequate flow. A riser is inserted into the riser recess and rests on the riser ledge 40. The riser is generally then covered with a manhole that allows access through the riser to the base section for inspection or maintenance of the base section or pipes leading to and from the bowl portion. Soils are back filled around the base section.

In use, fluid or slurry enters the bowl portion through the first or further pipes, the slurry then flows down the bowl wall 32 to the drainage point 34, whereupon it then flows into the second pipe opening 48 and out through the second pipe 46.

The skilled addressee will realise that the present invention provides the following advantages: pipes may be provided at any desired angle relative to one another; labour intensive channel fabrication is not required as the shape of the bowl portion results in fluid or slurry flowing from the inlet pipes to the outlet pipes.

Modifications and variations can be made to the present invention without departing from the basic inventive concept. Such modifications may include forming the body of the base section of a material other than concrete; the number of inlet or indeed outlet pipes may be more man that shown in the drawings; the angle of the inlet pipe to the outlet pipe may be other than that shown in the drawings; the outlet pipe may extend downwardly from the drainage portion as a sink and may exit the body through the base; the shape of the base section may be other than the frustoconical shape, the shape of the bowl section may be other than a dome shape, such as an elliptical shape and/or the riser recess may be replaced with a riser projection if the riser has a female receptor, rather than a male projection. Such modifications and variations are intended to be within the scope of the present invention, the nature of which is to be determined from the foregoing description and the appended claims.

Claims

THE CLAIMS

1. A manhole base section for connection to underground pipes, the base section including: a body, the body including a base, at least one side and a top; the top including an opening leading to a cavity extending into the base from the opening, the cavity having a bowl portion extending into the body, the bowl portion having a sloped wall so as to provide a sump, and the bowl portion being lined with a corrosion resistant liner; wherein a first pipe extends from the side into the bowl portion and a second pipe extends from the bowl portion to the side or the base, whereby, in use, fluid or slurry passes from the first pipe to the second pipe via the bowl portion.

2. A manhole base section as defined in claim 1, wherein the corrosion resistant liner is manufactured from pre-cast PVC.

3. A manhole base section as defined in claim 2, wherein the liner is provided with projections to facilitate mechanical bonding to the concrete base.

4. A manhole base section as defined in claim 1, wherein the second pipe opens into the bowl portion at or adjacent to a drainage point of the sump.

5. A manhole base section as defined in claim 4, wherein further pipes extend from the side into the bowl portion, whereby fluid or slurry from the further pipes can pass through the bowl portion to the second pipe.

6. A manhole base section as defined in claim 4, wherein the first pipe opens into the bowl portion at a relatively higher height to where the second pipe opens into the bowl portion.

7. A manhole base section as defined in claim 1, wherein the bowl portion is an inverted dome shape.

8. A manhole base section as defined in claim 1, wherein the pipes are bonded to the pre-cast liner then cast into the concrete body.

9. A manhole base section as defined in claim 1, wherein holes to receive the pipes are cored into the concrete body after curing.

10. A manhole base section as defined in claim 9, wherein the holes are formed in the body at an angle so that the pipes passing through the holes may be disposed at a desired angle relative to one another.

11. A manhole base section as defined in claim 1, wherein the pipes are cast in the body at a desired angle relative to one another.

12. A manhole base section as defined in claim 1, wherein the body is shaped to provide a ledge recessed inwardly from the top by a ledge recess portion, whereby the opening provides access to the ledge and the cavity for inspection or maintenance of the base section.

13. A manhole base section as defined in claim 12, wherein the bowl portion extends from the ledge further into the body.

14. A manhole base section as defined in claim 13, wherein the ledge slopes inwardly toward the bowl section.

15. A manhole base section as defined in claim 14, wherein the ledge recess portion includes a wall that is sloped inwardly towards the bowl section.

16. A manhole base section as defined in claim 1, wherein the top includes a riser recess for recessing a riser that extends upwardly from the base section to allow access to the base section for inspection or maintenance.

17. A manhole base section as defined in claim 1, wherein the body is generally cylindrical in shape.

18. A manhole base section as defined in claim 1, wherein the body is generally frustoconical in shape.

19. A process for manufacturing a manhole base section, the process including the steps of: providing a pre-cast corrosion resistant liner, the liner including a bowl shaped portion; providing a mold shaped to cast the base section so that the base section includes a base, at least one side, a top, and a bottom, the top including an opening leading to a cavity having a bowl portion; placing the liner into the mold so that the bowl shaped portion of the liner will line the bowl portion of the cast base section; and, filling the mold with concrete and allowing the concrete to cure.

20. A process for manufacturing a manhole base section as defined in claim 19, wherein the process further includes a step of coupling a pipe to the bowl shaped portion of the liner, prior to filling the mold with concrete, whereby when the concrete is cured the base section is provided with a pipe extending from the bowl shaped portion.

21. A process for manufacturing a manhole base section as defined in claim 20, wherein a hole is cut in the liner to allow fluid communication between the inside of the bowl shaped portion and the pipe.

22. A manhole base section manufactured in accordance with the process of claim 19.

23. A manhole base section as defined in claim 22, wherein the body of the manhole base section includes a first pipe that extends from the side into the bowl portion and a second pipe that extends from the side of the base into the bowl portion, whereby in use a fluid or slurry may pass from the first pipe to the second pipe via the bowl portion.