GB2145444A

GB2145444A - Manhole chambers

Info

Publication number: GB2145444A
Application number: GB08419674A
Authority: GB
Inventors: John Patrick Telford
Original assignee: Individual
Current assignee: Individual
Priority date: 1983-08-05
Filing date: 1984-08-02
Publication date: 1985-03-27
Also published as: AU3162684A; GB2145444B; GB8419674D0; AU572539B2

Abstract

Manhole components moulded from a plastics material include a chamber (10) having a side wall (14), step formations (18) which are integral with the side wall (14) and an integral base (20) which carries inlet (22) and outlet (24) pipe locating sockets; a cover slab such as (28) having an entrance aperture for location on and over the chamber (10) with at least the surface (40) of the cover slab which is exposed to the inside of the chamber (10) being composed of a plastics material; and a lid such as (36) for closing the cover aperture. Superposed spacer rings 30-32-34 may be provided and concrete filling may be used in or around all plastics components. Blanked-off pipe sockets (22) have saw guides (26) the inner of which can subsequently serve to locate a pipe seal. <IMAGE>

Description

SPECIFICATION Manhole This invention relates to a manhole or inspection access to underground sewers or drains and to a method of constructing the manhole.

Manholes and the like are conventionally made from precast concrete components with perhaps a benched base having branch outlets being cast from concrete in situ. Two principal difficulties arise with the conventional concrete manhole components. Firstly, transport, storage and handling of the components is made difficult and expensive because of their mass and secondly, where the manhole is into a sewer, the concrete is in time degraded by sewer gas and chemicals.

It is the object of this invention to provide a manhole, inspection chamber or the like and components for constructing the manhole which will minimise the above difficulties with conventional manholes and to a method of constructing the manholes.

A manhole according to the invention includes a chamber which is made from a platics material and has an integral base which carries inlet and outlet pipe locating sockets, a cover have an entrance aperture for location on and over the chamber with at least the surface of the cover which is exposed to the inside of the chamber being composed of a plastics material and a lid for closing the cover aperture.

Further according to the invention the manhole includes step formations which are integral with the wide wall of the chamber.

In one form of the invention the chamber cover is moulded from a plastics material.

In another form of the invention the chamber cover is made from concrete with at least the surface of the cover which is exposed to the inside of the chanmber being clad with a plastics material. The cover preferably includes a cover slab, an adaptor ring and a frame ring which carries a seat for the cover lid. Conveniently the cover includes at least one spacer ring which is located between the adaptor and frame rings.

Still further according to the invention the cover components each consists of a plastics moulding which is filled with concrete.

The cover lid could be made entirely of plastic or could, like the cover slab and its extension rings, consist of a concrete filled plastic mould.

A component for use in the manufacture of a manhole according to the invention consists of a mould which is made from a plastics material and is filled with concrete.

A manhole chamber according to the invention is moulded from a plastics material and includes a substantially cylindrical side wall into which step formations are integrally moulded and an integral base which carries inlet and outlet pipe locating sockets. Conveniently the pipe sockets project outwardly from the chamber side wall and are closed ended with each socket on the outside of the chamber including saw guide formations for guiding a saw in removing the closed socket ends.

A method of constructing a manhole according to the invention includes the steps of burying a chamber as described above, locating inlet and outlet pipes in the sockets in the chamber base, backfilling the chamber, casting a concrete restraining member on the backfill about the upper end of the chamber and locating a cover which conists of at least one concrete filled plastics mould over the chamber on the restraining member with the plastic of the or each mould exposed to the inside of the chamber.

In this specification the term plastics material is intended to means any suitable mouldable plastic which is unreactive with gases and chemicals which are likely to be encountered in sewers and the like. Additionally the term manhole is intended to include like access or inspection chambers into underground drains or sewers.

The invention is now described by way of example only with reference to the drawings in which: Figure 1 is an exploded sectioned side elevation of one embodiment of the manhole of the invention; Figure 2 is a sectioned side elevation of an alternative closure for the manhole; and Figure 3 is a half-sectioned side elevation of a coupling between a sewer inlet pipe and the benched base of the manhole chamber.

The manhole of Fig. 1 is shown to include basically a chamber 10 and a cover arrangement 12.

The chamber 10 is made from a plastics material such as high density polyethelyne which is non-reactive with destructing sewer gases and chemicals.

The chamber includes a cylindrical side wall 14 which is reinforced by circumferential ribs 16. Inwardly projecting steps 18 which are suitably spaced below each other and are moulded integrally with the side wall 14. If the chamber is to have a greater depth than is provided for by the single moulding of Fig. 1 one or more extension tubes which have an idential cross-section to the wall 14, including the steps 18, are suitably bonded to the mouth of the chamber to extend its length.

The base 20 of the chamber is integrally moulded with the side wall 1 4 and is benched in any suitable configuration. The inlets 22 and outlet 24 of the base are moulded closed as shown in the drawing with each carrying a pair of raised annular ribs 26 adjacent its closed end. This arrangement dispenses with blanking-off caps for those inlets and outlets which are not used in a specific application.

The cover arrangement 12 consists of a cover slab 28, an adaptor ring 30, one or more spacer rings 32, a frame ring 34 and a lid 36.

Each of the cover arrangement 1 2 components consists of a mould 40 which is made from a suitable plastics material, which may be the same as that from which the chamber is made, and a concrete infill 42. Where required each concrete filled mould 40 carries, in addition to the concrete, suitable metal reinforcing material. The reinforcing material will almost always be required in the relatively large dimension cover slab 28.

The simplicity of constructing a manhole from the components of the invention is that all that a contactor needs to transport and store is the light plastic mouldings. The cover assembly moulds are concrete filled and allowed to cure on site so significantly reducing transport costs and the high percentage of breakages which are common with the conventional concrete components.

The manhole of the invention is constructed by first cutting the end closures from selected inlets and outlets to the base of the chamber.

The spaced ribs 26 act as saw guides with the inner of the two ribs serving as a seal locator as illustrated in Fig. 3. Seals 44 are located over the opened base inlet and outlets and conventional UPVC or clay pipes are sealingly located in the openings as illustrated in Fig. 3 when the chamber is palced in a trench including the pipes. The trench or hole in which the chamber is located is backfilled and compacted with care being taken to fill the cavities of the steps as tightly as possible.

A restraining concrete ring 46 is then cast on the backfill around the mouth of the chamber as illustrated in Fig. 1.

The cover assembly 12 is assembled in the order shown in the drawing with a suitable adhesive between all of the components with the exception of the lid 36 and frame 34.

From the drawing it is evident that when the manhole is assembled no portion of the concrete infili 42 is exposed to the inisde of the chamber. This is addition to the fact that the manhole includes no metal components, such as step irons, significantly increases the useful life of the manhole, particularly in situations where highly destructive and corrosive liquids are passed through it in use. Cleaning of the manhole is additionally simplified by its smooth internal surfaces.

As an alternative to the cover 12 in Fig. 1 the Fig. 2 cover 47 which is moulded entirely from plastic could be employed as a closure for the manhole. In this event both the upper edge of the chamber 10 and the lower edge of the cover 46 could include inwardly directed flanges 48 and 50 which could be bonded, as illustrated, or bolted together to locate the cover on the chamber.

As mentioned above the invention is not limited to the components for and method of making only sewer manholes and extends to similar structures such as relatively smaller inspection chambers and the like which may include only the chamber and a lidded cover slab in place of the illustrated cover assembly components. The invention is also not limited to components having only the cross-sectional configurations which are illustrated in Fig. 1 and any of the components could have any shape suitable to its purpose.

Claims

1. A manhole including a chamber which is made from a plastics material and has a side wall, a base which is integral with the side wall and carries inlet and outlet pipe locting sockets, a cover having an entrance aperture for location on and over the chamber with at least the surface of the cover which is exposed to the inside of the chamber being composed of a platics material and a lid for closing the cover aperture.

2. A mahole as claimed in Claim 1 including step formations which are integral with the side wall of the chamber.

3. A manhole as claimed in either one of Claims 1 or 2 in which the chamber cover is moulded from a plastic material.

4. A manhole as claimed in either one of Claims 1 or 2 in which the chamber cover is made from concrete with at least the surface of the cover which is exposed to the inside of the chamber being clad wth a plastics material.

5. A manhole as claimed in Claim 4 in which the cover includes a cover slab, an adaptor ring and frame ring which carries a seat for the cover lid.

6. A manhole as claimed in Claim 5 including at least one spacer ring which is located between the adaptor and frame rings of the cover.

7. A manhole as claimed in Claim 6 in which each of the cover components each consiss of a plastics moulding which is filled with concrete.

8. A manhole as claimed in any one of the above claims in which the cover lid consists of a plastics mould which is filled with concrete.

9. A component for use in the manufacture of a manhole including a plastic moulding which is filled with concrete.

10. A manhole chamber which is moulded from a plastics material and includes a substantially cylindrical side wall into which step formations are integrally moulded and an integral base which carries inlet and outlet pipe locating sockets.

11. A manhole chamber as claimed in Claim 10 in which the pipe sockets project outwardly from the chamber side wall and are closed ended with each socket on the outside of the chamber including saw guide formations for guiding a saw in removing the closed socket ends.

1 2. A method of constructing a manhole including the steps of burying a chamber as claimed in Claim 10, locating inlet and outlet pipes in the sockets in the chamber base, backfilling the chamber, casting a concrete restraining member on the backfill about the upper end of the chamber and locating a cover which consists of at least one concrete filled plastics mould over the chamber on the restraining member with the plastic of the or each concrete filled mould exposed to the inside of the chamber.

1 3. A manhole substantially as herein described with reference to any one of the embodiments shown in the accompaying drawings.

14. Components for use in the construction of a manhole substantially as herein described with reference to any one of the embodiments shown in the accompanying drawings.

1 5. A method of constructing components such as cover dabs, adaptor, frame and spacer rings for use in the construction of manholes substantially as herein described with reference to any one of the embodiments shown in the accompanying drawings.

1 6. A method of constructing a manhole substantially as herein described with reference to any one of the embodiments shown in the accompanying drawings.