GB2368604A

GB2368604A - Frame assemblies for manhole covers

Info

Publication number: GB2368604A
Application number: GB0026970A
Authority: GB
Inventors: Barry Turner
Original assignee: C I S
Current assignee: C I S
Priority date: 2000-11-04
Filing date: 2000-11-04
Publication date: 2002-05-08
Anticipated expiration: 2020-11-04
Also published as: GB2368604B; GB0026970D0

Abstract

A frame assembly for a manhole cover 14 comprises a support member or members 12 on which the cover 14 is supported and a foundation member 40, e.g. of polymer concrete, in which the support member 12 is at least partially embedded, the assembly of support and foundation members 12,40 forming a discrete unit which is installed at the site location and subsequently embedded in place. The foundation member 40 may have (a) reinforcement(s) 60. The support member 12 may be a continuous frame or may comprise separate corner pieces. It may include hinge mounts. It has a flange 30 embedded in the foundation member and the flange may be U-shaped in vertical section. The lower face of the foundation member may have protruding nodules 58.

Description

Ground Surface Access Assemblies The invention relates to ground surface access assemblies such as manhole assemblies and gully gratings. Such assemblies allow access to sewers, water hydrants and other below surface installations, via openings in the roads, pavements, etc. above.

A manhole assembly typically includes a generally rectangular frame and a cover member mountable on the frame. The cover member can be lifted from the frame or pivoted relative to the frame in order to allow access to the below surface installation.

Manhole assemblies are generally made of strong materials and are designed to be stiff in order to function correctly. The assemblies are generally made from cast or ductile iron or materials of similar strength and stiffness. In order to reduce the likelihood of the cover member rocking on the frame, the assemblies are usually made up of a number of triangular cover member units supported by and within a frame.

European standards for ground surface access assemblies define a general level of stress that any assembly is allowed to impose on the substructure beneath it. The stress levels are defined in terms of the total maximum design load divided by the base area of the assembly. However, research by the Applicants has shown that the load applied by a ground surface access assembly to the substructure is not evenly distributed, but is concentrated around the support points. Various designs of frame have been proposed which attempt to reduce the stresses imposed by the loads, by increasing the base area of the frame in the region of the support points.

The Applicants have discovered that the above proposed designs have two important weaknesses. Firstly, the designs are reliant on the quality of the site installation of the assemblies, which the Applicants have found to be inconsistent and frequently inadequate. For example, it is common for insufficient foundation material to be used or for the foundation material not to be mixed or compacted properly. In addition, the person installing the frame may not level it properly within the foundation material Further, the road in which the ground surface access assembly is installed may be opened before the structure has properly cured. Efforts to overcome these problems by means of education and training have proved unsuccessful as it is difficult to control conditions on site and the skill levels of those involved may be low.

The second problem is that the materials used to construct ground surface access assembly frames are essentially elastic and can deform to accommodate imposed loads. The Applicants have discovered that such frames deform to a surprising extent even under the application of relatively low, uneven loads. Therefore, even when the frame is designed to distribute loads over large areas, it is still possible for the frame to impose a very high local level of stress which the foundation material cannot tolerate.

According to the invention there is provided a frame assembly for a ground surface access assembly, the frame assembly including one or more support members for supporting a cover member of the access assembly and a foundation member, the or each support member being at least partially embedded in the foundation member and the frame assembly being formed as a discrete unit for subsequent embedding on a substrate.

Preferably the or each support member is made of a metallic material which is preferably a cast ferrous material such as cast iron or ductile iron.

The or each support member may include an upstanding wall portion and one or more seats protruding inwardly in use therefrom. A cover member supported on the support member may be supported on the or each seat, inwardly of the upstanding wall.

The or each support member may further include a flange portion extending generally outwardly in use from a base region of the upstanding wall portion.

The flange portion may be generally planar and substantially horizontal in use. However, preferably the flange portion has a curved profile. The flange portion may be shaped so as to form a smooth channel extending around the upstanding wall portion. In vertical section, the flange portion may be generally U-shaped.

An edge of the flange portion remote from the upstanding wall portion is preferably smooth and curved. An elongate bead may extend around at least a part of the edge. The bead may have a substantially circular section, and may have a radius of about 10 mm. The bead preferably extends around the whole of the edge of the flange.

The frame assembly may include a single unitary support member. The support member may be generally rectangular in plan view, including substantially straight side portions and curved corner portions. The seats may be provided in the corner portions of the support member.

Alternatively the frame assembly may include a plurality of discrete support members. The frame assembly may include four support members for supporting respective corners of a cover member. Each support member is preferably shaped to form a corner part of a rectangle in plan view, including an upstanding wall portion with a right-angled corner therein. Preferably the support member includes a seat extending generally inwardly in use from the corner portion.

Two or more of the discrete support members may include means for mounting a hinge for attaching a cover member thereto. These means may include a recess for receiving a hinge, the recess extending outwardly in use from the upstanding wall portion. Preferably the recess is defined by base, side and end walls, the respective side walls including aligned openings therein, for mounting the hinge.

Preferably the flange portion of the or each of the support members is fully embedded in the foundation member. Preferably the wall portion extends upwardly out of the foundation member such that the or each seat is exposed.

Preferably the foundation member forms a closed loop of material for extending around a top edge of a manhole chamber. The foundation member may be bounded by an inner surface defining an edge of a central opening in the foundation member and a lower surface extending outwardly in use from a base part of the inner surface or a part of the support member. An outer surface may extend generally between an outer part of the lower surface and an upper part of the inner surface. In use, the inner surface may be aligned generally with walls of the manhole chamber.

The lower surface may be substantially planar. The lower surface may be provided with a plurality of projections extending downwardly in use therefrom. Preferably the projections result in the profile of the lower surface having alternating peaks and troughs in each of any two mutually perpendicular directions. The projections on the lower surface preferably provide a smoothly undulating profile in each of the two mutually perpendicular directions. The undulations may be regular or periodic. The lower surface of the foundation member may be provided with a plurality of protruding nodules. The nodules preferably protrude in a direction substantially perpendicular to the general plan of the lower surface of the foundation member. The nodules may be substantially conical in shape, with blunt or curved peaks. The nodules may be provided over substantially the whole of the lower surface of the foundation member. Preferably the nodules terminate smoothly near an outer edge of the lower surface.

The overall size of the foundation member may be such that it spans at least 800 mm across in plan view.

The foundation member is preferably inflexible on the application of vertically directed forces. Preferably the foundation member applies primarily compressive forces to a substrate in which it is embedded. The Young's Modulus of the Foundation member is preferably at least 150 GPa and most preferably at least 210 GPa.

The foundation member may include a bedding mortar. The foundation member may be made substantially of a concrete material, which may be a polymer concrete. Alternatively the foundation member might be made of a resinous material. Preferably the compression strength of the foundation

member is at least 70N/mm2. Preferably the tensile strength of the foundation member is at least 9N/mm2. Preferably the flexural strength of the foundation member is at least 20N/mm2.

One or more reinforcement members may be embedded in the foundation member. The reinforcement members may include corrosion resistant steel members, which may be elongate and which may be curved.

The frame assembly preferably forms a discrete component, for subsequent embedding on mortar to form a site installation.

According to the invention, there is further provided a ground surface access assembly including a frame assembly as previously defined, and a cover member.

According to the invention there is further provided a method of manufacturing a frame assembly according to any of the preceding definitions, the method including the steps of supporting the or each support member, pouring a liquid material over and around the or each support member and allowing the liquid material to set around the or each support member to form the foundation member and to at least partially embed the support member within the foundation member.

The or each support member may be supported upside down in relation to its in-use position According to the invention there is further provided a method of manufacturing a ground surface access assembly including a plurality of discrete support members, as previously defined, the method including the steps of: supporting a cover member upside down in relation to its in-use position; locating each support member on the cover member such that the position of the support member in relation to the cover member is as it will be in use; pouring a liquid material over and around the support members; and allowing the liquid material to set around the support members to form the foundation member, thereby setting the support members in relative positions which enable each support member to contact and support the cover member in use.

Preferably the support members are located over corners of the cover member, with respective seats of the support members in contact with the cover member.

The method may include the step of connecting two of the support members to the cover member by hinge means, thereby correctly defining the positions of the hinged support members in relation to the position of the cover member in use.

Embodiments of the invention will be described for the purpose of illustration only with reference to the accompanying drawings in which: Fig. 1 is a diagrammatic plan view of a prior art manhole assembly frame; Fig. 2 is a diagrammatic plan view of a prior art manhole assembly including a frame and a cover member; Fig. 3 is a diagrammatic partial cross-section through a prior art manhole assembly after exposure to traffic; Fig. 4 is a diagrammatic partial cross-section through a manhole assembly according to the invention; Fig. 5 is a diagrammatic partial cross-section through a frame assembly according to an alternative embodiment of the invention; Fig. 6 is a diagrammatic plan view of a manhole assembly according to the invention; Fig. 7 is a diagrammatic perspective view of a corner support according to an alternative embodiment of the invention; Fig. 8 is a diagrammatic plan view of a corner support similar to that of Fig. 7, but provided with a hinge; and Fig. 9 is a diagrammatic perspective view illustrating the use of the corner supports of Figs. 7 and 8.

Referring to the drawings, a conventional manhole assembly 10 includes a frame 12 and a cover member 14. Referring to Fig. 2, the cover member 14 is formed of cast metal such as cast iron and comprises two substantially planar triangular parts 16 provided with triangular projections 18 on their upper surfaces. The triangular projections 18 provide for a high friction upper surface of the cover member 14, to allow traffic to pass over the manhole assembly 10 without skidding.

The cover member 14 is supported at its edges 20 by the frame 12. The frame 12 is generally square in plan view, including straight sides 22 and curved corner regions 24. Referring to Fig. 3, the frame 12 includes an upstanding wall 26, provided with seats 28 projecting therefrom in an inward direction. The edges 20 of the cover member 14 are supported on the seats 28.

Extending outwardly from a base region of the upstanding wall 26 is a generally planar flange 30 which includes relatively narrow side portions 32 and splayed corner portions 34. Each corner position 34 includes three openings 36 passing therethrough (see Fig. 1).

Conventionally, the above manhole assembly is installed at a site location by site operatives mixing and applying an encapsulating foundation mortar 40 in which the frame is embedded (see Fig. 3). The mortar 40 then retains the manhole assembly in place in the road, etc. Traditional installation of such a manhole assembly therefore relies heavily on the skill of the site operatives mixing and applying the encapsulating foundation mortar. Such mortar must be applied in a controlled and consistent manner in order to provide a high quality installation. Unfortunately, it is common for insufficient mortar to be used, for the mixing to be heterogeneous, for insufficient compaction to be applied and for the manhole assembly to be levelled incorrectly. Further, the road or other site may be opened before sufficient mechanical properties have been developed in the mortar.

If any of the above occurs, weak areas may develop in the foundation mortar bed. If the mortar bed fails in a region under the flange 30, this region of the flange becomes unsupported. It has been discovered by the Applicants that conventional manhole frames 12 are relatively flexible and particularly if unsupported in any region, they will tend to flex quite dramatically as vehicles travel over the manhole assembly. Such flexing causes initial damage to the mortar bed or, if the mortar bed is already damaged, the flexing increases that damage. The damage eventually results in failure. Fig. 3 illustrates a situation where cracks have formed around an edge of the flange 30 of the frame 12.

Referring to Fig. 4, a frame assembly 44 according to the invention includes a support member in the form of a frame 12 embedded in a foundation member 46. The frame 12 is embedded in the foundation member 46 at the factory under controlled and consistent conditions. It can be seen that the foundation member encapsulates the flange 30 of the frame 12. The upstanding wall 26 protrudes from the foundation member, leaving the seats 28 exposed, to support the cover member 14. The frame assembly 44 is provided to site operatives in this state.

The shape of the frame 12 is generally as described above in relation to the prior art.

The foundation member 46 includes an inner surface 48 which in use is generally aligned with an inner wall 50 of a manhole chamber 52. A bottom of the foundation member 46 is defined by a lower surface 54 which extends outwardly from a base of the inner surface 48. An outer surface 56 extends generally between an outer edge of the lower surface 54 and a mid part of the upstanding wall 26 of the frame 12.

The lower surface 54 of the foundation member 46 is provided with protruding nodules 58 which are generally conical in shape but which have curved peaks. The nodules 58 result in the lower surface 54 of the foundation member 46 having an undulating profile in each of any two mutually perpendicular directions.

The foundation member 46 is made of a material such as a polymer concrete which has medium compression strength, high tensile and shear strength, high fatigue resistance and high surface adhesion to freshly laid contemporary foundation mortars. The cementitious material should also have a good resistance to chemical attack from common manhole chamber condensates and normal road and subterranean contaminants.

Embedded within the foundation member 46, spaced from the flange 30, is a reinforcement member 60. The reinforcement member 60 is made of a material having high rigidity, such as steel, and helps to improve the rigidity of the overall frame assembly 44.

Referring to Fig. 5, there is illustrated an alternative embodiment of the invention. In this embodiment, the flange 30 of the frame 12 is smoothly curved, in order to reduce the stresses that it applies to the foundation member 46 and is generally U-shaped in vertical section. An underside 62 of the flange 30 has a textured contact surface, in order to increase friction with the foundation member 46. The lower surface 54 of the foundation member 46 also has a textured contact surface for engagement with mortar in which it is embedded on site. The frame assembly further includes reinforcement members 60, which in this case are made from 30 mm angled steel elements.

Fig. 6 is a plan view of the frame assembly of Fig. 5, illustrating the overall shape of the foundation member 46. It may be seen that the foundation member includes foot portions 64 which extend outwardly away from its corners. The foot portions 64 are joined by narrower wall portions 66. The width of the wall portions is about 50 mm, whilst the width of the foot portions is about 150 mm.

The composite frame assembly 44, including the frame 12 and the foundation member 46, is provided to the site operative as a single, discrete unit. The frame assembly 44 is manufactured under controlled conditions in a suppliers factory. The frame 12 is thus embedded correctly in the foundation member 46 and does not apply any localised stresses thereto.

The site operative is required to embed the frame assembly 44 on mortar. However, the accuracy of this embedding operation is far less important than in the prior art case. This is because the foundation member 46, being made of concrete, is very stiff. It thus cannot flex in the way that the frame 12 can. Because the frame 12 is fully embedded within the foundation member 46, the foundation member prevents movement of the frame 12 when vehicles travel over the manhole assembly 10. The foundation member 46 also has a large lower surface 54 which distributes loads over the encapsulating mortar material. Any voids in this encapsulating mortar material, under the frame assembly 44, do not have the detrimental effect of voids provided directly under a metallic frame member 12. This is because the inability of the foundation member to flex prevents it from applying a repetitive load to these areas.

In view of the above, the main stresses transmitted to the encapsulating mortar are compressive stresses which the mortar is well able to withstand. There are some shear forces provided when vehicles accelerate or slow down across the manhole cover but these are addressed by the provision of the textured underside 58.

Figs. 7 to 9 illustrate an alternative embodiment of the invention. In this embodiment, instead of a unitary frame 12, four support members 70 are provided for locating independently within the foundation member 46. Each support member 70 includes an upstanding wall 26 including a curved corner 72. A seat 28 projects inwardly from the corner 72, to support the cover member 14. A flange 30 extends outwardly from a base region of the upstanding wall 26. The flange is U-shaped in profile, as in the Fig. 5 embodiment.

The support member 70 illustrated in Fig. 8 includes a hinge recess 74 defined by side, end and base walls 76,78 and 80 respectively. Each side wall 76 is provided with an opening 82, the respective openings being aligned. The hinge recess 74 allows a cover member to be pivotally attached to the support member 70. The frame assembly 44 would generally include two support members provided with hinge recesses 74 and two support members without hinge recesses, so that the cover member may be attached at one of its sides to the hinged support members.

The support members 70 may be embedded in the foundation member 46, in order to provide all the advantages discussed above in relation to the previous embodiments. However, this embodiment of the invention provides further advantages in relation to the mounting of the cover member on the frame.

As illustrated in Fig. 2, cover members 14 are conventionally formed in two triangular halves, in order that each may be supported stably at three corner points. The use of triangular units has disadvantages in that the cover member is supported only at three corners, whilst loads tend to be applied to the centre. It is thus necessary to provide a long, reinforced beam diagonally across the centre of the cover member. This can result in a relatively heavy and expensive product.

Any alternative support system which uses more than three supports tends to suffer from rocking problems if the supports are not precisely complementary to the shape of the frame. These problems may be overcome by the embodiment of Figs. 7 to 9.

Referring to Fig. 9, a frame assembly may be formed using the support members 70, as follows. A cover member 14 may be supported in an inverted state relative to its in use position. The support members 70 may then be placed on corners of the cover member 14 such that the relative positions of the cover member 14 and the support members are as they would be in use. The corners of the cover member will be in contact with the respective seats of the support members 70. If the cover member in use is hinged to the frame, the hinges may be also put into place in the hinge recess 74.

With the cover member and the support members so positioned, liquid mortar material may be poured around the assembly, using a suitable mould.

The mortar material sets around the support members 70, thus holding them in place such that in use the hinges will be correctly aligned and the cover member will be in close contact with all four seats 28 on the support members 70. The composite frame assembly 44 may then be removed from the cover member for subsequent site installation. When the cover member is eventually fitted to the frame assembly 44, the cover member should be correctly mounted on the seats 28 of all four support members 70.

The above method therefore provides a frame assembly 44 which may be used with a rectangular cover member. The cover member may be supported on four seats 28. The cover member will not rock on the seats because their positions have been dictated specifically by the precise shape of the cover member. This method therefore overcomes the problems conventionally associated with supporting a cover member on more than three seats.

Whilst endeavouring in the foregoing specification to draw attention to those features of the invention believed to be of particular importance it should be understood that the Applicant claims protection in respect of any patentable feature or combination of features hereinbefore referred to and/or shown in the drawings whether or not particular emphasis has been placed thereon.

Claims

Claims 1. A frame assembly for a ground surface access assembly, the frame assembly including one or more support members for supporting a cover member of the access assembly and a foundation member, the or each support member being at least partially embedded in the foundation member and the frame assembly being formed as a discrete unit for subsequent embedding on a substrate.
2. A frame assembly according to claim 1, in which the or each support member is made of a metallic material.
3. A frame assembly according to claim 2, in which the metallic material is a cast ferrous material such as cast iron or ductile iron.
4. A frame assembly according to any of the preceding claims, in which the or each support member includes an upstanding wall portion and one or more seats protruding inwardly in use therefrom.
5. A frame assembly according to claim 4, in which a cover member supported on the support member is supported on the or each seat, inwardly of the upstanding wall.
6. A frame assembly according to claim 4 or claim 5, in which the or each support member includes a flange portion extending generally outwardly in use from a base region of the upstanding wall portion.
7. A frame assembly according to claim 6, in which the flange portion is generally planar and substantially horizontal in use.
8. A frame assembly according to claim 6, in which the flange portion has a curved profile.
9. A frame assembly according to claim 8, in which the flange portion is shaped so as to form a smooth channel extending around the upstanding wall portion.
10. A frame assembly according to claim 8 or claim 9, in which in vertical section, the flange portion is generally U-shaped.
11. A frame assembly according to any of claims 6 to 10, in which an edge of the flange portion remote from the upstanding wall portion is smooth and curved.
12. A frame assembly according to claim 11, in which an elongate bead extends around at least a part of the edge.
13. A frame assembly according to claim 12, in which the bead has a substantially circular section.
14. A frame assembly according to claim 13, in which the radius of the bead is about 10 mm.
15. A frame assembly according to any of claims 12 to 14, in which the bead extends around the whole of the edge of the flange.
16. A frame assembly according to any of claims 6 to 15, in which the frame assembly includes a single unitary support member.
17. A frame assembly according to claim 16, in which the support member is generally rectangular in plan view, including substantially straight side portions and curved corner portions.
18. A frame assembly according to claim 17, in which the seats are provided in the corner portions of the support member.
19. A frame assembly according to any of claims 6 to 15, in which the frame assembly includes a plurality of discrete support members.
20. A frame assembly according to claim 19, in which the frame assembly includes four support members for supporting respective corners of a cover member.
21. A frame assembly according to claim 20, in which each support member is shaped to form a corner part of a rectangle in plan view, including an upstanding wall portion with a right-angled corner therein.
22. A frame assembly according to claim 19 or claim 20, in which the support member includes a seat extending generally inwardly in use from the corner.
23. A frame assembly according to any of claims 19 to 22, in which two or more of the discrete support members include means for mounting a hinge for attaching a cover member thereto.
24. A frame assembly according to claim 23, in which these means include a recess for receiving a hinge, the recess extending outwardly in use from the upstanding wall portion.
25. A frame assembly according to claim 24, in which the recess is defined by base, side and end walls, the respective side walls including aligned openings therein, for mounting the hinge.
26. A frame assembly according to any of claims 6 to 25, in which the flange portion of the or each of the support members is fully embedded in the foundation member.
27. A frame assembly according to claim 26, in which the wall portion extends upwardly out of the foundation member such that the or each seat is exposed.
28. A frame assembly according to any of the preceding claims, in which the foundation member forms a closed loop of material for extending around a top edge of a manhole chamber.
29. A frame assembly according to claim 28, in which the foundation member is bounded by an inner surface defining an edge of a central opening in the foundation member and a lower surface extending outwardly in use from a base part of the inner surface or a part of the support member.
30. A frame assembly according to claim 29, in which an outer surface extends generally between an outer part of the lower surface and an upper part of the inner surface.
31. A frame assembly according to claim 29 or claim 30, in which in use, the inner surface is aligned generally with walls of the manhole chamber.
32. A frame assembly according to any of claims 29 to 31, in which the lower surface is substantially planar.
33. A frame assembly according to any of claims 29 to 32, in which the lower surface is provided with a plurality of projections extending downwardly in use therefrom.
34. A frame assembly according to claim 33, in which the projections result in the profile of the lower surface having alternating peaks and troughs in each of any two mutually perpendicular directions.
35. A frame assembly according to claim 34, in which the projections on the lower surface provide a smoothly undulating profile in each of the two mutually perpendicular directions.
36. A frame assembly according to claim 35, in which the undulations are regular or periodic.
37. A frame assembly according to any of claims 29 to 36, in which the lower surface of the foundation member is provided with a plurality of protruding nodules.
38. A frame assembly according to claim 37, in which the nodules protrude in a direction substantially perpendicular to the general plane of the lower surface of the foundation member.
39. A frame assembly according to claim 37 or claim 38, in which the nodules are substantially conical in shape, with blunt or curved peaks.
40. A frame assembly according to any of claims 37 to 39, in which the nodules are provided over substantially the whole of the lower surface of the foundation member.
41. A frame assembly according to claim 40, in which the nodules terminate smoothly near an outer edge of the lower surface.
42. A frame assembly according to any of the preceding claims, in which the overall size of the foundation member is such that it spans at least 800 mm across in plan view.
43. A frame assembly according to any of the preceding claims, in which the foundation member is inflexible on the application of vertically directed forces.
44. A frame assembly according to any of the preceding claims, in which the foundation member applies primarily compressive forces to a substrate in which it is embedded.
45. A frame assembly according to any of the preceding claims, in which the Young's Modulus of the foundation member is at least 150 Gpa.
46. A frame assembly according to claim 45, in which the Young's Modulus of the foundation member is at least 210 GPa.
47. A frame assembly according to any of the preceding claims, in which the foundation member includes a bedding mortar.
48. A frame assembly according to claim 47, in which the foundation member is made substantially of a concrete material.
49. A frame assembly according to claim 48, in which the concrete material is a polymer concrete.
50. A frame assembly according to any of claims 1 to 46, in which the foundation member is made of a resinous material.
51. A frame assembly according to any of the preceding claims, in which the compression strength of the foundation member is at least 70N/mm2.
52. A frame assembly according to any of the preceding claims, in which the

tensile strength of the foundation member is at least 9N/mm2.
53. A frame assembly according to any of the preceding claims, in which the flexural strength of the foundation member is at least 20N/mm2.
54. A frame assembly according to any of the preceding claims, in which one or more reinforcement members is embedded in the foundation member.
55. A frame assembly according to claim 54, in which the or each reinforcement member includes a corrosion resistant steel member.
56. A frame assembly according to claim 55, in which the or each steel member is elongate.
57. A frame assembly according to claim 55 or claim 56, in which the or each steel member is curved.
58. A frame assembly according to any of the preceding claims, in which the frame assembly forms a discrete component, for subsequent embedding on mortar to form a site installation.
59. A ground surface access assembly including a frame assembly as previously defined in claims 1 to 58, and a cover member.
60. A method of manufacturing a frame assembly according to any of the preceding claims, the method including the steps of supporting the or each support member, pouring a liquid material over and around the or each support member and allowing the liquid material to set around the or each support member to form the foundation member and to at least partially embed the support member within the foundation member.
61. A method of manufacturing a frame assembly according to claim 60, in which the or each support member is supported upside down in relation to its in-use position.
62. A method of manufacturing a ground surface access assembly including a plurality of discrete support members, as previously defined in claims 1 to 15 and claims 19 to 59, the method including the steps of: supporting a cover member upside down in relation to its in-use position; locating each support member on the cover member such that the position of the support member in relation to the cover member is as it will be in use; pouring a liquid material over and around the support members; and allowing the liquid material to set around the support members to form the foundation member, thereby setting the support members in relative positions which enable each support member to contact and support the cover member in use.
63. A method of manufacturing a ground surface access assembly according to claim 62, in which the support members are located over corners of the cover member, with respective seats of the support members in contact with the cover member.
64. A method of manufacturing a ground surface access assembly according to claim 62 or claim 63, in which the method includes the step of connecting two of the support members to the cover member by hinge means, thereby correctly defining the positions of the hinged support members in relation to the position of the cover member in use.
65. A manhole assembly substantially as hereinbefore described with reference to any of Figs. 4 to 9 of the accompanying drawings.
66. Any novel subject matter or combination including novel subject matter disclosed herein, whether or not within the scope of or relating to the same invention as any of the preceding claims.