Patent Description:
Conventionally, ground surface access assemblies comprise a frame defining an opening and one or more covers which locate onto the frame in or above the opening. The or one or each cover is openable or removable to permit access to underground services via the opening. Traditionally, during installation, the frame is laid on a bed of bedding material such as mortar on top of a chamber structure formed of concrete or brick. Surround material (which could comprise underlying foundation material, bedding material, haunching material, sub base material, road base material and surfacing material) is then installed up to ground surface level, substantially to the top of the frame, so that the sides of the frame are fully covered.

Investigations have shown that nowadays, for a variety of reasons (primarily the increased use of ductile iron), it is more often installation failure which occurs rather than failure of the covers and frame. In installation failure, the access assembly remains intact and functional, but the surround material degrades and breaks up. This in itself can present a hazard to road users. Furthermore this can result in the access assembly becoming loose and dislodged, presenting a further hazard to road users.

In this specification, the terms inner, outer, inwardly and outwardly, when used in relation to the frame, are used with respect to the opening, which is inward of the frame, and the terms upward and downward are used in relation to the in use orientation of a ground surface access assembly, in which downward means down into the ground.

In this specification, the term cover has been used to mean solid and/or gridded covers (gratings).

The invention is a ground surface access assembly with the features of claim <NUM>, The additional features of claims <NUM>-<NUM> describe further embodiments of said assembly.

Embodiments of the present invention will now be described, by way of example only, and with reference to the accompanying drawings, in which:-.

In the drawings, where multiple instances of the same or similar features exist, only a representative one or some of the instances of the features have been provided with numeric references for clarity.

<FIG> show a prior art ground surface access assembly <NUM>. The assembly <NUM> includes a frame <NUM> defining an opening <NUM>. The frame <NUM> includes a mounting <NUM> for a cover <NUM>, which is arranged so that, in use, the cover <NUM> locates in the opening <NUM>.

In the example shown, the frame <NUM> includes four side members <NUM>. Each side member <NUM> includes an upstanding side wall <NUM>. Each side wall <NUM> includes an outer side wall surface <NUM> and an inner side wall surface <NUM>.

Each side member <NUM> includes a base wall <NUM>. Each base wall <NUM> includes a flange part <NUM>, which projects outwardly from a lowermost part of one or more of the side walls <NUM>.

In the example shown, the ground surface access assembly <NUM> includes a pair of covers <NUM>.

The mounting <NUM> includes mounting projections <NUM>, which project inwardly from the side walls <NUM>, for mounting the cover <NUM>. The mounting projections <NUM> are spaced upwardly from the base walls <NUM>.

In the example shown, each cover <NUM> is mounted so that it contacts the frame <NUM> at three points, to provide non-rock mounting.

Typically, the frame <NUM> and the covers <NUM> are formed by casting of cast iron, which could be ductile iron.

<FIG> shows the prior art ground surface access assembly <NUM> in an installed condition. The frame <NUM> is laid on a layer <NUM> of bedding material <NUM> (such as mortar) on top of an upper part <NUM> of a chamber structure <NUM>, which defines a passage <NUM> which communicates with the opening <NUM>. The chamber structure <NUM> could be formed of concrete or brick. The upper chamber part <NUM> includes outer side wall surfaces <NUM>. Surround material <NUM> (which could comprise underlying foundation material, bedding material, haunching material, sub base material, road base material and surfacing material) is then installed up to ground surface level <NUM>, substantially to the top of the frame <NUM>.

The outwardly extending base walls <NUM> extend laterally outwardly beyond the outer side wall surfaces <NUM> of the upper chamber part <NUM>. This provides the advantage that the span distances between the mounting projections <NUM> for the covers <NUM> are minimised, which assists in reducing product weight. However, the Applicant has realised that, in practice, this arrangement causes a number of disadvantages.

In one failure mode, in use, under traffic loads, vertical loads (arrows Fv, <FIG>) are applied to the covers <NUM> which cause flexing of the frame <NUM>. This in turn results in a relatively high load concentration on the inward edge of the bedding material layer <NUM>, which over time can degrade and fall into the passage <NUM>. The loss of the bedding material layer <NUM> can result in the frame <NUM> dropping (arrow D), leading to a void forming above the flange part <NUM>. Further trafficking can then cause failure of the surround material <NUM> above the flange part <NUM>. Flexing of the frame <NUM> under traffic loading also causes movement of the base walls <NUM> projecting beyond the upper chamber part <NUM> which causes degradation of the surround material <NUM>.

In another failure mode, in use, braking forces apply horizontal lateral loads (arrow FH, <FIG>) to the covers <NUM> and the frame <NUM>, resulting in horizontally extending shear stress planes being formed in the bedding layer <NUM>, between the bedding layer <NUM> and the frame <NUM> and between the bedding layer <NUM> and the upper chamber part <NUM>. The stress planes can cause failure planes resulting in lateral movement of the frame <NUM> relative to the upper chamber part <NUM> (arrow L).

In another failure mode, loading on the surround material <NUM> (for example, by road surfacing machinery) can be transmitted through the surround material <NUM> to dislodge or distort the chamber upper part <NUM> of the chamber structure (arrows FR).

<FIG> show a first embodiment of a ground surface access assembly <NUM> according to the invention, many features of which are similar to those already described in relation to the prior art arrangement of <FIG>. Therefore, for the sake of brevity, the following embodiment will only be described in so far as it differs from the arrangement already described. Where features are the same or similar, the same reference numerals have been used and the features will not be described again.

The assembly <NUM> includes a frame <NUM> defining an opening <NUM>. The frame <NUM> includes a mounting <NUM> for a cover <NUM>, which is arranged so that, in use, the cover <NUM> locates in the opening <NUM>. The assembly <NUM> includes an upper chamber part <NUM> of a chamber structure <NUM>, wherein, in an assembled condition, the frame <NUM> locates on and is supported by the upper chamber part <NUM>.

The frame <NUM> and the covers <NUM> could be formed by casting of cast iron, which could be ductile iron.

The upper chamber part <NUM> could be formed of concrete and/or resin.

The frame <NUM> includes a seating surface <NUM>. The upper chamber part <NUM> includes a mounting surface <NUM>.

The upper chamber part <NUM> defines a passage <NUM> which communicates with the opening <NUM>.

The frame <NUM> and the upper chamber part <NUM> each include a mutually cooperating interlock feature <NUM>, <NUM> respectively, which, in use and in the assembled condition, interlock to resist lateral (side to side) relative movement between the frame and the upper chamber part.

One of the interlock features <NUM>, <NUM> includes a projection <NUM> and one of the interlock features <NUM>, <NUM> defines a recess <NUM> in which, in the assembled condition, the projection <NUM> locates.

In the example shown, the frame interlock feature <NUM> comprises the projection <NUM> and the upper chamber part interlock feature <NUM> defines the recess <NUM>.

As seen most clearly in <FIG>, in one example, the projection <NUM> is tapered in cross section profile and the recess is correspondingly shaped. In one example, the projection <NUM> could be a sliding fit in the recess <NUM>. In another example, the projection could be an interference fit in the recess <NUM>.

The upper chamber part <NUM> includes outer side wall surfaces <NUM>. The frame <NUM> includes outer side wall surfaces <NUM>. In the assembled condition, the upper chamber part outer side wall surfaces <NUM> and the frame outer side wall surfaces <NUM> are substantially vertically aligned.

The frame <NUM> includes one or more side members <NUM>. In the example shown, the frame <NUM> includes four side members <NUM>. Each side member <NUM> includes an upstanding side wall <NUM>. Each frame side wall <NUM> includes one of the outer side wall surfaces <NUM> and an inner side wall surface <NUM>.

Each side member <NUM> includes a base wall <NUM>, which comprises a flange part <NUM>. Each flange part <NUM> projects inwardly from a lowermost part of one of the side walls <NUM>.

No part of the base walls <NUM> or the flange parts <NUM> projects outwardly (ie away from the opening) from any of the side walls <NUM>.

The frame seating surface <NUM> comprises in-use a downwardly directed surface of the base wall <NUM>.

The frame interlock projection <NUM> projects downwardly from the base wall <NUM> and from the frame seating surface <NUM>.

The mounting <NUM> includes mounting projections <NUM>, which project inwardly from the side walls <NUM>, for mounting the cover <NUM>. The mounting projections <NUM> are spaced upwardly from, and on the same inward side of the side walls <NUM> as, the base walls <NUM>. Each mounting projection <NUM> is in the form of a projecting ledge <NUM>.

In the example shown, the frame seating surface <NUM> includes both an outer portion <NUM>, which is located adjacent to an outer side of the frame interlock projection <NUM>, and an inner portion <NUM> which is located adjacent to an inner side of the frame interlock projection <NUM>.

Each portion <NUM>, <NUM> is in the form of a strip. In one example, each portion <NUM>, <NUM> extends continuously around the opening <NUM>.

In the example shown in <FIG>, the frame interlock projections <NUM> extend longitudinally along the base wall <NUM>. Each frame interlock projection <NUM> could be in the form of a fin, rib or blade.

In one example, each base wall <NUM> has one frame interlock projection <NUM> projecting therefrom.

The upper chamber part <NUM> includes four chamber side walls <NUM>. Each side wall <NUM> includes an upwardly directed chamber side wall upper surface <NUM>. The chamber side wall upper surfaces <NUM> comprise the mounting surface <NUM>.

In the example shown in <FIG>, each chamber side wall upper surface <NUM> defines one of the interlock recesses <NUM>. Each interlock recess <NUM> extends longitudinally along the respective chamber side wall upper surface <NUM>. Each interlock recess <NUM> is in the form of a slot or channel.

In the assembled condition, the assembly <NUM> includes fixing material <NUM> which is located between the frame interlock projection <NUM> and the upper chamber part <NUM>. The fixing material <NUM> is a settable material which is movable between a relatively fluid condition, in which the fixing material <NUM> can flow between the frame interlock projection <NUM> and the upper chamber part <NUM>, and a relatively solid condition, in which the fixing material <NUM> substantially does not flow but is substantially solid.

In use, the frame <NUM> is located on to the upper chamber part <NUM> so that the frame <NUM> directly contacts the upper chamber part <NUM>. In the assembled condition, the frame seating surface <NUM> locates directly on the mounting surface <NUM> of the upper chamber part <NUM> with no intermediate material therebetween. The frame <NUM> does not extend outwardly beyond an outward extremity of the upper chamber part <NUM>. No part of the frame <NUM> projects laterally outwardly beyond the outer side wall surfaces <NUM> of the upper chamber part <NUM>.

In the assembled condition, the frame interlock projections <NUM> locate in the chamber interlock recesses <NUM>. The fixing material <NUM>, which could be a cementitious material, a polymer modified cementitious material, an epoxy grout or the like, is located between the frame interlock projection <NUM> and the upper chamber part <NUM> so that it substantially fills spaces <NUM> defined in the recess <NUM> between the frame interlock projection <NUM> and the upper chamber part <NUM>. The fixing material <NUM> could be located before and/or after location of the frame <NUM> on to the upper chamber part <NUM>.

With the frame <NUM> in the assembled condition on the upper chamber part <NUM>, the surround material <NUM> is located against the side walls <NUM> of the upper chamber part <NUM> and the frame side walls <NUM> up to the ground surface level <NUM>.

It is a feature of the invention that, in the assembled condition, the frame <NUM> is in direct contact with the upper chamber part <NUM>, with no intermediate layer of relatively weak bedding material <NUM> therebetween. Advantageously, flexing of the frame <NUM> under traffic loading does not transmit movement to layer <NUM> of the intermediate bedding material <NUM>, which in conventional arrangements can result in the formation of horizontal planes of weakness in the relatively weak intermediate material, which can in turn result in lateral movement between the frame <NUM> and the upper chamber part <NUM>, loss of the bedding material <NUM>, dropping of the frame and degradation of the surround material <NUM>.

It is a feature of the invention that, in the assembled condition, the frame <NUM> is only vertically supported by the upper chamber part <NUM>, which permits the frame <NUM> to move separately relative to the surround material <NUM>. Advantageously, flexing of the frame <NUM> under traffic loading does not transmit movement to the surround material <NUM> via a projecting flange which, in conventional arrangements, can result in degradation of the surround material <NUM>.

The mutually cooperating interlock features <NUM>, <NUM> of the frame <NUM> and the upper chamber part <NUM> interlock to resist lateral (side to side) relative movement between the frame <NUM> and the upper chamber part <NUM>, reducing the risk of installation failure due to the transmission of lateral forces to and from the surround material <NUM>.

The mutually cooperating interlock features <NUM>, <NUM> are shown in cross section in <FIG> and could take a number of differing forms in longitudinal shape. As mentioned above, one example has been shown and described in <FIG>. In this example, the interlock features <NUM>, <NUM> could extend the whole length or the majority of the whole length of each side wall <NUM> of the upper chamber part <NUM> and each frame side member <NUM>, so that each frame side member <NUM> has one frame interlock projection <NUM> projecting downwardly therefrom and each chamber side wall <NUM> defines one chamber interlock recess <NUM>.

In a second embodiment of the invention, an assembly <NUM>, shown in <FIG>, a plurality of interlock features <NUM>, <NUM> are intermittent along the length of each side wall <NUM> of the upper chamber part <NUM> and each frame side member <NUM>. Each frame side member <NUM> includes a plurality of frame interlock projections <NUM> projecting downwardly therefrom, which are aligned in a row. The frame interlock projections <NUM> are intermittent and spaced apart and could be in the in the form of studs, pegs, nodules or the like.

Each chamber side wall <NUM> defines a plurality of interlock recesses <NUM>, which correspond in number to the number of the frame interlock projections <NUM>, and correspond in shape.

Advantageously, the interlock features <NUM>, <NUM> of <FIG> provide lateral interlock in two mutually horizontal orthogonal directions (eg X-Y).

The Applicant has further realised that the interlocking features <NUM>, <NUM> could be provided on one, some or all of the sides of the frame <NUM> and the upper chamber part <NUM>. For example, in the case of gully gratings which are commonly located against a kerb at the side of a road, the interlocking features <NUM>, <NUM> might only be provided on the three sides subjected to traffic in the roadway.

In another example (not shown), one or the or each interlock recess <NUM> could receive, in the assembled condition, a plurality of the frame interlock projections <NUM>.

<FIG> show other embodiments of the invention, many features of which are similar to those already described in relation to the embodiments of <FIG>. Therefore, for the sake of brevity, the following embodiments will only be described in so far as they differ from the embodiments already described. Where features are the same or similar, the same reference numerals have been used and the features will not be described again.

<FIG> shows a third embodiment, a ground surface access assembly <NUM>. The assembly <NUM> includes an adjustor <NUM>, for adjusting the height of the frame <NUM> relative to a fixed chamber structure <NUM>. The fixed chamber structure <NUM> is that part of the chamber structure on which the ground surface access assembly <NUM> is installed in use.

The assembly <NUM> is movable from an adjustment condition, in which the adjustor <NUM> is operable to adjust the height of the frame <NUM>, to a fixed condition, in which the height of the frame <NUM> is fixed.

The adjustor <NUM> comprises part of the frame <NUM> and comprises at least one adjustor member <NUM>. In the example shown, the adjustor member <NUM> is threaded, and extends through a threaded adjuster hole <NUM> (shown in dashed lines in <FIG>) defined by the frame base wall <NUM>. The adjustor member <NUM> extends downwardly, substantially vertically in use, and alongside the frame interlock projection <NUM> to a chamber recess base wall <NUM>, which comprises part of the upper chamber part <NUM> and defines the chamber interlock recess <NUM>.

The frame base walls <NUM> could define a plurality of the adjustor holes <NUM> and the adjustor <NUM> could comprise a plurality of the adjuster members <NUM>. The adjustor holes <NUM> could be arranged in one or more pairs, with one pair being defined by one, some or each frame base wall <NUM>. Each of the adjuster holes <NUM> could be located in the vicinity of or towards one of the corners of the frame <NUM>.

In use, the frame <NUM> is located on to the upper chamber part <NUM> so that the frame <NUM> directly contacts the upper chamber part <NUM> with no intermediate material therebetween. The frame interlock projections <NUM> locate in the chamber interlock recesses <NUM>.

The adjustor members <NUM> are then located through the adjustor holes <NUM> and, in the adjustment condition, are adjusted by rotation until the adjustor members <NUM> contact the chamber recess base wall <NUM> and the frame <NUM> is at the required height relative to the finished ground surface level <NUM>.

The adjustor members <NUM> could be fixed at this position by the use of, for example, thread locking adhesive, locknuts etc. which prevent rotation of the adjustor members <NUM>.

At the required height, the frame <NUM> could contact the upper chamber part <NUM> via the frame seating surfaces <NUM>, one or some of the adjustor members <NUM>, or a combination thereof.

The fixing material <NUM> is then located in the space <NUM> and allowed to set, fixing the frame <NUM> in the fixed condition at the required height above the fixed chamber structure <NUM>.

The surround material <NUM> is then located against the side walls <NUM> of the upper chamber part <NUM> and the frame side walls <NUM> up to the ground surface level <NUM>. In this embodiment, it is an advantage for the frame interlock projections <NUM> to extend substantially continuously along the side members <NUM>, to act as a barrier or shuttering for the surround material <NUM>.

<FIG> shows a fourth embodiment, a ground surface access assembly <NUM>. In this embodiment, the adjustor <NUM> includes first and second adjustor chamber members <NUM>, <NUM> respectively, which together comprise the upper chamber part <NUM>.

In the adjustment condition, the first adjustor chamber member <NUM> and the second adjustor chamber member <NUM> movably inter-engage to permit adjustment of the height of the frame <NUM> relative to the fixed chamber structure <NUM>. In the adjustment condition, the first adjustor chamber member <NUM> is movable relative to the second adjustor chamber member <NUM>.

The first and second adjustor chamber members <NUM>, <NUM> each include a mutually cooperating adjustment feature <NUM>, <NUM> respectively, which, in the assembled condition, permits adjustment of the height of the frame <NUM>.

One of the adjustment features <NUM>, <NUM> includes a projection <NUM> and one of the adjustment features <NUM>, <NUM> defines an adjustment recess <NUM> in which, in the assembled condition, the projection <NUM> locates.

The first adjustor chamber member <NUM> includes the interlock feature <NUM> of the upper chamber part <NUM>. In the example shown, the first adjustor chamber member <NUM> defines, at an upper end, the interlock recess(es) <NUM>.

In the example shown, the first adjustor chamber member <NUM> includes the adjustment projection <NUM> which extends downwardly and, in the assembled condition, is received in the adjustment recess <NUM> which is defined by the second adjustor chamber member <NUM>.

The adjustor <NUM> includes a locking device <NUM> for locking the assembly <NUM> in the fixed condition.

In the example shown, the locking device <NUM> includes a plurality of locking members <NUM> which extend, in use substantially horizontally, through locking holes <NUM> defined in the first and second adjustor chamber members <NUM>, <NUM>. The locking holes <NUM> could be pre-formed or formed in situ, or some combination thereof.

Some of the holes <NUM> could be elongate, in the form of slots, with a longitudinal axis which is aligned substantially vertically.

In one example, in use, the first adjustor chamber member <NUM> is located at a required height relative to the second adjustor chamber member <NUM>, with the adjustment projection <NUM> located in the adjustment recess <NUM>. The locking holes <NUM> are then formed by drilling through the second adjustor chamber member <NUM> and the adjustment projection <NUM> and the locking members <NUM> located through the locking holes <NUM>.

The adjustor <NUM> includes adjustor fixing material <NUM> which is located in the adjustment recess <NUM> between the adjustment projection <NUM> of the first adjustor chamber member <NUM> and the second adjustor chamber member <NUM>. The adjustor fixing material <NUM> is a settable material which is movable between a relatively fluid condition, in which the adjustor fixing material <NUM> can flow, and a relatively solid condition, in which the fixing material <NUM> substantially does not flow but is substantially solid. The adjustor fixing material <NUM> could be a cementitious material, a polymer modified cementitious material, an epoxy grout or the like.

In the assembled condition, the adjustor fixing material <NUM> substantially fills adjustment spaces <NUM> defined in the adjustment recess <NUM> between the adjustment projection <NUM> of the first adjustor chamber member <NUM> and the second adjustor chamber member <NUM>.

<FIG> shows a fifth embodiment, a ground surface access assembly <NUM>. This embodiment is similar to the embodiment shown in <FIG>, except that, rather than the adjustment member <NUM>, the adjustor <NUM> comprises one or more packing members <NUM>, which, in use, are located vertically between the frame interlock projection <NUM> and the chamber recess base wall <NUM>.

<FIG> shows a sixth embodiment, a ground surface access assembly <NUM>. This embodiment is similar to the embodiment shown in <FIG>, except that, rather than the locking members <NUM>, the adjustor <NUM> comprises one or more packing members <NUM>, which, in use, are located vertically between the adjustment projection <NUM> of the first adjustor chamber member <NUM> and the second adjustor chamber member <NUM>.

<FIG> shows a frame <NUM> only of a seventh embodiment, a ground surface access assembly <NUM>. In this embodiment, the frame interlock projection <NUM> defines a plurality of interlock apertures <NUM>, which in this example are through apertures.

In use, the fixing material <NUM> locates in the apertures <NUM>. Advantageously, this increases interlock between the frame <NUM> and the fixing material <NUM> and in particular, vertical interlock between the frame <NUM> and the fixing material. Also, the apertures <NUM> reduce the weight of the frame <NUM> which reduces the frame cost and reduces manual handling risk.

The apertures <NUM> could be of any suitable number, spacing, size and shape, and could be in the form of recesses rather than through holes, or a combination thereof.

<FIG> shows a frame <NUM> only of an eighth embodiment, a ground surface access assembly <NUM>. In this embodiment, the frame interlock projection <NUM> reduces in cross-sectional width. In the example shown, the frame interlock projection <NUM> is stepped in cross-section. The frame interlock projection <NUM> comprises an upper part 34A, a middle part 34B and a lower part 34C, with a step <NUM> between each part. The middle part 34B is narrower in cross-section width than the upper part 34A and the lower part 34C is narrower in cross-section width than the middle part 34B, so that the projection <NUM> progressively reduces in cross-sectional width.

The reduced width parts 34B, 34C reduce the weight of the frame <NUM>, which reduces the frame cost and reduces manual handling risk.

The frame interlock projection <NUM> could reduce in cross sectional width in other ways. For example, the frame interlock projection <NUM> could be tapered, or both tapered and stepped.

The steps <NUM> and the reduced width parts 34A, 34B, 34C could be of any suitable number, spacing, size and shape.

Various other modifications could be made without departing from the scope of the invention. The ground surface access assembly and the various components thereof could be of any suitable size and shape, and could be formed of any suitable material (within the scope of the specific definitions herein).

For example, the upper chamber part could be formed of a metallic material, such as mild steel, or of a cast material, or of a combination of materials, such as mild steel, concrete, glass fibre and/or resin, polycarbonate, resin composite and/or glass reinforced materials. In some embodiments the upper chamber part could comprise a metal upper part and a lower part formed of plastics materials such as polycarbonate, resin composite and/or glass reinforced materials.

The frame could be circular, triangular, square or rectangular in plan shape. The ground surface access assembly could comprise one, two or more covers. The ground surface access assembly could comprise a manhole frame and cover(s), or a gully and grating(s).

The interlock feature of the frame could define a recess and the interlock feature of the upper chamber part could comprise a projection. The interlock features of both the frame and the upper chamber part could include both recesses and projections.

The adjustment feature of the first adjustor chamber member could define a recess and the adjustment feature of the second adjustor chamber member could comprise a projection.

Any of the features or steps of any of the embodiments shown or described could be combined in any suitable way, within the scope of the overall disclosure of this document.

Claim 1:
A ground surface access assembly (<NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>), the assembly including a frame (<NUM>) defining an opening (<NUM>), the frame including a mounting (<NUM>) for a cover (<NUM>) which is arranged so that, in use, the cover locates in the opening, the assembly including an upper part (<NUM>) of a chamber structure (<NUM>), wherein, in an assembled condition, the frame locates on and is supported by the upper chamber part;
the frame and the upper chamber part each include a mutually cooperating interlock feature (<NUM>, <NUM>), which, in use and in the assembled condition, interlock to resist lateral (side to side) relative movement between the frame and the upper chamber part;
characterised in that:
one of the interlock features includes a projection (<NUM>) and one of the features defines a recess (<NUM>) in which, in the assembled condition, the projection locates to provide the interlock;
the upper chamber part interlock feature (<NUM>) defines the recess (<NUM>) and the frame interlock feature (<NUM>) includes the projection (<NUM>);
wherein the recess is in the form of a slot or channel.