GB2301848A

GB2301848A - Modular manhole assembly

Info

Publication number: GB2301848A
Application number: GB9511632A
Authority: GB
Inventors: Alan Brook
Original assignee: Hepworth Building Products Ltd
Current assignee: Hepworth Building Products Ltd
Priority date: 1995-06-08
Filing date: 1995-06-08
Publication date: 1996-12-18
Also published as: GB9511632D0

Abstract

A modular manhole assembly comprises modular plastics sections 7,9,10,13 of double-walled construction optionally having a lightweight filling between the walls 1,2. The filling is suitably a plastics foam. Preferably at least one of the sections is provided with a radial rib or flange 16. The structure enables the provision of a manhole which is deep, with adequate strength and rigidity, yet also light enough for handling and installation by one man without machinery.

Description

DRAINAGE COMPONENTS This invention relates to inspection chambers, also known as manholes.

Smaller inspection chambers (up to one meter deep) are commonly prefabricated from plastics or clayware, and are relatively easy to handle and install.

Because regulations specify a relationship between depth and diameter of inspection chambers, pre-fabricated chambers have not hitherto been produced for depths greater than one meter; it has not been practical to provide the requisite internal dimensions.

Deep inspection chambers have therefore been built on site using brickwork, or concrete sections. A brick manhole is very expensive. Concrete manhole sections are heavy and difficult to handle, usually requrring cranage which is not normally available at least on small building sites, and concrete sectional manholes are usually of poor quality as well as expensive.

There is a great need for a deep inspection chamber which is light and which is simple and fast to install.

According to the present invention there is provided a modular manhole assembly comprising modular plastics sections of double-walled construction.

The use of a double wall for the manhole sections makes it possible to provide the internal dimensions required by building regulations for a deep manhole, with adequate strength and rigidity. The plastics sections can however be made light enough to be handled by one man without machinery.

The double-walled sections may have a lightweight filling between the walls, for improved strength, for example a plastics foam filling.

A modular manhole embodying the invention is shown by way of example, in perspective and in vertical section, in the accompanying drawing.

The illustrated manhole is assembled from rotation-moulded plastics modular sections. These are double-walled comprising an inner wall 1 and an outer wall 2 with a closed hollow space between them, which may be filled with plastics foam.

The manhole assembly comprises a base 4 with integral sockets 5 for connection to drainpipes and on its upper side a circular coupling flange 6.

Above this is a bottom riser or pan 7 with a horizontal lower wall and a funnellike upper wall meeting at a downwardly projecting circular coupling stub 8 in which is a circular groove or seat mating with the flange 6 of the base. This provides a mechanically strong connection between the base 4 and the bottom riser 7. A seal may be provided between components 4 and 7.

Because the joint between components 4 and 7 is circular these two components can be oriented independently of one another.

Above the bottom riser is a cylindrical wall consisting of one or more riser sections 9 stacked vertically on the bottom riser. The riser sections 9 can be of different standard heights (e.g. 150mm, 500mm) to enable the construction of manhole assemblies of different desired heights by the use of appropriate numbers of riser sections of appropriate individual heights.

Seated on the uppermost riser section 9 is a top riser 10 which tapers upwardly to a circular neck 11 which is connected to a manhole cover frame 12 in which, in use, a manhole cover is seated. The frame 12 is coupled to the neck 11 by one or more height adjusters. In the illustrated example these comprise shallow modular sections 13 stacked on the neck 11 to the required number and height.

Alternatively, a slidable cylindrical height adjuster sleeve may be provided which caries the frame 12 and can slide vertically within the neck 11, suitable seals being provided between the height adjuster and the frame and neck.

Because there is a circular joint between the frame 12 and the inspection chamber proper there can be oriented independently of one another, so that the frame can be oriented parallel to surrounding paving.

As already mentioned, each of the modular sections 7, 9, 10, 13 is doublewalled to provide adequate strength and rigidity with a relatively large diameter, typically 1050mm ID. The neck diameter is enough to admit a person, typically 600mm ID.

For interconnecting the modular sections, these are provided at their upper and/or lower edges with complementary mating profiles to provide positive mechanical location between the modular sections. In the illustrated embodiments each upper edge has an upwardly projecting inner flange 14 spaced inwardly from the periphery of the section and flush with the inner surface, and each section lower edge has a downwardly projecting outer flange 15 flush with the outer surface of the section. Thus, each of the flanged edges is of a stepped profile, providing an abutment surface on which the mating flange of the adjacent section can abut. Seals may be provided between adjacent modular sections, between these and the top and bottom risers, and between the top components 10-12, as appropriate.

The riser sections 9, at least in the case of those with greater height (for example 500mm) have circumferential external ribs 16 for enhanced strength.

The top riser may have radial ribs or flanges 17 for enhanced strength and to provide protection against overlying material and vertical loads.

The bottom riser 7 may have a peripheral rib similar to the ribs 16 of the modular riser sections.

The various sections can be made in any convenient way, but we have found that rotational moulding is a particularly suitable manufacturing process.

The sections of the described manhole are light but durable, can be carried by one man, and are able to withstand rough handling on site. The manhole is able to withstand at least light vehicular traffic.

The illustrated manhole is of circular cross section but the invention is not limited to circular manholes and is also applicable for example to square and rectangular manholes. Regulations restrict 1050mm circular manholes to 1.5mm deep, deeper manholes must be of greater diameter, or be rectangular.

For improved access a double-size opening may be provided instead of the 600mm opening described. Access steps may be incorporated in the sections, or the sections may be provided with means for fitting step irons, ladders or the like.

The described manhole is for access to drainpipes, and accordingly it has a base comprising a stepped drainage channel or invert. However, the invention is also applicable to other access uses for example silt pits, anti flood valves, and so on. In all applications the present manhole is significantly cheaper and easier to install than conventional brick and concrete manholes.

Claims

CLAIMS:

1. A modular manhole assembly comprising modular plastics sections of doublewalled construction.

2. A modular manhole assembly according to Claim 1, comprising a lightweight filling between the double walls.

3. A modular manhole assembly according to Claim 2, wherein the filling is a plastics foam filling.

4. A modular manhole assembly according to any preceding Claim, wherein at least one of the sections is provided with a radial rib or flange.

5. A modular manhole assembly according to any preceding claim, wherein a bottom one of the said sections defines a pan.

6. A modular manhole assembly according to Claim 5, wherein the pan is configured such that, in use, it has a generally horizontal lower wall and a funnelshaped upper wall.

7. A modular manhole assembly according to any preceding claim, wherein an upper one of the said sections comprises an upper wall which tapers upwardly to a neck, which neck defines an access opening.

8. A modular manhole assembly according to Claim 7, wherein the said neck is formed from modular plastics sections of double-walled construction.

9. A modular manhole assembly according to Claim 8, wherein at least one of the said plastic sections forming the said neck is axially slidable relative to another one of the said sections forming the said neck.

10. A modular manhole assembly according to any preceding claim wherein interconnection between adjacent ones of the said sections is achieved by inserting an axial flange provided on one of the sections into an axial mouth provided on the other.

11. A modular manhole assembly according to Claim 10, wherein the said flange extends flush with a radially inner wall of the section on which it is provided and the other section comprises a corresponding radially inner wall, the configuration of the mouth being such as to accommodate the flange and maintain it in a substantially flush relationship with the said radially inner wall of the section in which the mouth is provided.

12. A modular manhole assembly according to any preceding claim, wherein at least some of the modular sections have a circular cross-section.

13. A modular manhole assembly according to any one of Claims 1 to 11, wherein at least some of the modular sections have a rectangular cross-section.

14. A modular manhole substantially as hereinbefore described with reference to the accompanying drawing.

15. A modular section for a manhole assembly according.to any preceding claim.