Modular access chamber and stackable ring

Abstract

The present invention relates to a stackable ring for a modular access chamber. The stackable ring comprises a plurality of elongate side portions and a corresponding plurality of corner portions connected between adjacent side portions. An angle formed between each side portion and an adjacent corner portion is less than 90 degrees. The invention also relates to modular access chamber, comprising a plurality of such stackable rings, stacked vertically such that a lower end of a first stackable ring of the plurality of stackable rings engages an upper end of a second stackable ring of the plurality of stackable rings. A side portion for a stackable ring for a modular access chamber is also provided.

Description

Field of the Invention

[0001] The present invention relates to a modular access chamber and to stackable rings that may be stacked together to form such an access chamber.Background to the Invention

[0002] Utility services such as electricity, gas and water are typically laid underground. Valves, electrical junctions and meters are provided in underground access chambers (or manhole chambers) which can be accessed at designated points via access covers (or manhole covers). Rapid and economical construction of these access chambers is a key requirement of utility providers. Many construction companies also wish to minimise the carbon footprint associated with the materials used in the construction of these chambers while also improving safety.

[0003] Traditionally, underground infrastructure access chambers have been manufactured from precast concrete, brick or other traditional materials. These materials are heavy, carbon intensive and require specialised lifting equipment to handle and install. Concrete is one of the largest contributors to the carbon footprint of the construction industry.

[0004] More recently, glass fibre reinforced composite plastics materials have been used as a way to create lightweight chamber products. One example is proposed in British Patent Application Publication No. 2 404 409, which describes a modular chamber having a base and side wall, the sidewall comprising a plurality of side wall units stacked one on top of another. Each side wall unit comprises a plurality of elongate, hollow, wall members and a plurality of connector members.

[0005] A disadvantage of existing composite access chambers is that, due to their modular nature, water may enter the chamber between the modular elements, which increases the risk of damage to the equipment located in the chamber. Another disadvantage is that composite chambers may have reduced strength as compared with traditional concrete chambers.Summary of the Invention

[0006] The present invention relates to a stackable ring for a modular access chamber, comprising: a plurality of elongate side portions; and a corresponding plurality of corner portions connected between adjacent side portions, and wherein an angle formed between each side portion and an adjacent corner portion is less than 90 degrees.

[0007] The stackable ring may be formed from a plastics material and, preferably, a composite plastics material.

[0008] Connection means may be provided on or engaged with each corner portion for connection to adjacent side portions.

[0009] The angle formed between each side portion and the adjacent corner portion is preferably between about 45 degrees and about 85 degrees. Preferably, the angle is between about 55 degrees and about 75 degrees. More preferably, the angle is approximately 65 degrees.

[0010] In an embodiment, the stackable ring defines a perimeter that is substantially rectangular in shape. In this embodiment, the stackable ring may comprise four side portions and four corner portions. In other embodiments, the perimeter of the ring may be a different shape. Preferably, the side portions are substantially straight. The corner portions may be curved or angled.

[0011] Each side portion may be formed such that an inner edge thereof is shorter (in a longitudinal direction of the side portion) in length than an outer edge thereof. As such, an end of the side portion may be angled inwards from the outer edge to the inner edge. Each side portion may be trapezoidal in shape. The corner portions may be formed such that their ends are angled outwards at an angle complementary to the angle at which the side portions are angled inwards.

[0012] Each side portion and / or each corner portion may comprise: an inner wall; an outer wall; and an upper plate extending substantially horizontally between an upper end or edge of the inner wall and an upper end or edge of the outer wall.

[0013] The upper plate may extend from one end of each side portion to the other. The upper plate may extend from one end of each corner portion to the other.

[0014] For each side portion, the inner wall may be shorter (in a longitudinal direction of the side portion) in length than the outer wall such that an end of the side portion is angled inwards from the outer wall to the inner wall.

[0015] Each end of the side portion may be formed with an acute angle such that the side portion is trapezoidal in shape, that is, the upper plate of the side portion may be in the form of a trapezoid or trapezium, whereby the inner edge of the upper plate is shorter (in a longitudinal direction of the side portion) that the outer edge of the upper plate. For example, the upper plate of the side portion may take the form of an isosceles trapezoid in which the base angles at each end have the same value.

[0016] For each corner portion, an end of the upper plate may be angled outwards from the outer wall to the inner wall, wherein the angle is complementary to the angle formed by the adjacent side portion.

[0017] The elongate side portions may be formed, for example, by pultrusion or other suitable method of manufacture. A single elongate profile may be formed by pultrusion and cut to form multiple individual side portions of the stackable ring. Each end of the side portion may be cut at an angle to form the trapezoidal shape described above. Each side portion may be hollow.

[0018] An advantage of the proposed arrangement in which the angle formed between each side portion and the adjacent corner portion is less than 90 degrees is that it maximises the strength of the stackable ring by transferring stress from the elongate side portions to the corner portions. This in turn provides improved resistance to side wall loading pressure as a result of the soil surrounding the chamber.

[0019] The stackable ring may further comprise a gasket disposed between each side portion and the adjacent corner portion. Preferably the gasket is flat and has an outer profile corresponding to that of the adjacent corner portion. The gasket may be formed from an elastomeric or other deformable material. An example of a suitable material is Ethylene Propylene Diene Monomer (EPDM) sponge rubber.

[0020] When the stackable ring is assembled, the gasket is compressed between the side portions and the adjacent corner portions to form a mechanical seal therebetween, thereby preventing water ingress at the connection points between the side and corner portions of the ring. The acute angle formed between the side portion and the adjacent corner portions provides improved compression of the gasket, as compared with a 90 degree joint, to further improve watertightness of the ring and thus an access chamber formed therefrom.

[0021] The stackable ring may further comprise an O-ring disposed in an upper surface thereof. Preferably, the O-ring is disposed centrally of the upper surface of the stackable ring. The O-ring is preferably continuous around the upper surface of the stackable ring.

[0022] For example, a channel may be formed in an upper surface of the upper plate of each side portion and each corner portion, to form a continuous channel in the upper surface of the stackable ring. Preferably, the channel has a dove-tail profile. The channel may be located centrally of the upper plate of each side portion and each corner portion. The O-ring may be disposed in the continuous channel.

[0023] An advantage of this arrangement is that, when the stackable rings are stacked to form a modular access chamber, the O-ring provides a seal between consecutive rings which prevents water ingress to the chamber. The dove-tail profile grips the O-ring to retain it in the stackable ring.

[0024] The upper plate of a stackable ring suitable for use as an uppermost stackable ring of a modular access chamber may extend horizontally beyond the outer wall. This uppermost stackable ring may be referred to as a crowning profile. By extending horizontally beyond the outer wall of the stackable ring, the crowning profile provides an extra wide surface at a top end of the modular access chamber which allows bearing pressure from a manhole cover frame to be more evenly distributed and transferred to the access chamber structure, thereby increasing the performance and lifespan of the chamber. The upper plate of the stackable ring suitable for use as an uppermost stackable ring may also have a castellated upper profile to aid bedding mortar adhesion.

[0025] Each side portion may further comprise a lower plate extending substantially horizontally between the inner wall and the outer wall along at least a portion of the length of the side portion. The lower plate may be parallel to and spaced apart from an upper plate of the side portion. The lower plate may be offset from lower ends or edges of the inner and outer walls such that the inner and outer walls extend vertically below the lower plate. The lower plate and the lower ends of the inner and outer walls of the side portions may form a recess dimensioned to receive an upper plate of a corresponding stackable ring, when stacked to form a modular access chamber.

[0026] According to another aspect of the invention, there is provided a modular access chamber, comprising: a plurality of stackable rings, each stackable ring comprising: a plurality of elongate side portions; and a corresponding plurality of corner portions connected between adjacent side portions, and wherein an angle formed between each side portion and an adjacent corner portion is less than 90 degrees; wherein the stackable rings are stacked vertically such that a lower end of a first stackable ring of the plurality of stackable rings engages an upper end of a second stackable ring of the plurality of stackable rings.

[0027] Each side portion and each corner portion of each stackable ring may comprise: an inner wall; an outer wall; and an upper plate extending substantially horizontally between an upper end of the inner wall and an upper end of the outer wall.

[0028] The upper plate of the first stackable ring may extend horizontally beyond the outer wall. The upper plate of the first stackable ring may have a castellated upper profile.

[0029] Each side portion of at least the first stackable ring may further comprise a lower plate extending horizontally between the inner wall and the outer wall along the length of the side portion. The lower plate of the first stackable ring may engage the upper plate of the second stackable ring. The lower plate of the first stackable ring may be offset from lower ends or edges of the inner and outer walls such that the inner and outer walls extend vertically below the lower plate. The lower plate and the lower ends of the inner and outer walls of the side portions may form a recess dimensioned to receive an upper plate of the second stackable ring. The upper plate of the second stackable ring may be received in the recess in the first stackable ring according to an interference fit.

[0030] The second stackable ring may comprise an O-ring disposed in an upper surface thereof. Preferably, the O-ring is disposed centrally of the upper surface of the second stackable ring. The O-ring is preferably continuous around the upper surface of the second stackable ring. A channel may be formed in an upper surface of the upper plate of each side portion and each corner portion of the second stackable ring, to form a continuous channel in an upper surface of the second stackable ring. The O-ring may be disposed in the channel. The O-ring may provide a seal between the upper plate of the second stackable ring and the lower plate of the first stackable ring.

[0031] The modular access chamber may further comprise a clip mechanism for securing the first stackable ring to the second stackable ring. The clip mechanism engages each of the first and second stackable rings to cause a vertical compressive force therebetween. The clip mechanism may provide vertical compression of the O-ring between the stackable rings so as to maintain watertightness, while also allowing the assembled chamber to be easily handled on site and during transportation as a single unit.

[0032] The terms "upper", "lower", "inner", "outer", "inwards", outwards", "horizontally", "vertical", etc. are used herein to refer to the stackable ring and modular access chamber as per the intended orientation and are not intended to be otherwise limiting.

[0033] According to another aspect of the invention, there is provided an elongate side portion for a stackable ring for a modular access chamber, the elongate side portion comprising: an inner wall; an outer wall; and an upper plate extending substantially horizontally between an upper end or edge of the inner wall and an upper end or edge of the outer wall, wherein the inner wall is shorter (in a longitudinal direction of the side portion) than the outer wall such that an end of the side portion is angled inwards from the outer wall to the inner wall.

[0034] Each end of the elongate side portion may be connectable to a corresponding corner portion of a stackable ring for a modular access chamber.Brief Description of the Drawings

[0035] Figure 1 is a perspective view of a first embodiment of a stackable ring for a modular access chamber; Figure 2 is a rear perspective view of the stackable ring of Figure 1; Figure 3 is a top plan view of the stackable ring of Figure 1; Figure 4 is a perspective view of a side portion of the stackable ring of Figure 1; Figure 5 is a top plan view of the side portion of Figure 4; Figure 6 is a cross-sectional view of the side portion of Figure 4; Figure 7 is a perspective view of a corner portion of the stackable ring of Figure 1; Figure 8 is a perspective view, from underneath, of the corner portion of Figure 7 Figure 9 is a perspective view of a second embodiment of a stackable ring for a modular access chamber; Figure 10 is a top plan view of the stackable ring of Figure 9; Figure 11 is a perspective view of a side portion of the stackable ring of Figure 9; Figure 12 top plan view of the side portion of Figure 11; Figure 13 is a cross-sectional view of the side portion of Figure 11; Figure 14 is a top-plan view of a portion of the stackable ring of Figure 9, showing a corner portion and two adjacent side portions; Figure 15 is a perspective view of a modular access chamber according to an aspect of the present invention; Figure 16 is a cutaway perspective view of the modular access chamber of Figure 15; Figure 17 is a perspective view of a portion of the modular access chamber of Figure 15; Figure 18 is a cross-sectional view through the side portions of two stackable rings of the modular access chamber of Figure 15; Figure 19 is a perspective view of corner portions of two stackable rings of the modular access chamber of Figure 15; Figure 20 is a perspective view of a clip member for connecting adjacent stackable rings of the modular access chamber of Figure 15; Figure 21 is a perspective view of a clip member for connecting adjacent stackable rings of the modular access chamber of Figure 15; Figure 22 is a perspective view of a clip member in situ in adjacent stackable rings of the modular access chamber of Figure 15; and Figure 23 is a perspective view of a portion of the modular access chamber of Figure 15, with an accessory mounted thereon. Detailed Description of the Drawings

[0036] A stackable ring 101 for a modular access chamber according to a first embodiment of the present invention is shown in Figures 1 to 3. The stackable ring 101 comprises a plurality of elongate side portions 102 and a corresponding plurality of corner portions 103 connected between adjacent side portions.

[0037] In the embodiment shown in Figures 1 to 3, the stackable ring 101 defines a substantially rectangular perimeter. As shown, the stackable ring 101 comprises four side portions 102 and four corner portions 103. Each of the side portions is substantially straight and each of the corner portions is curved, to provide a 90 degree angle at the corners of the stackable ring. In other embodiments, the perimeter of the ring may be a different shape and the corner portions may be formed with the appropriate degree of curvature to provide the required shape.

[0038] As shown in Figures 1 to 3 and in more detail in Figures 4 to 6, each side portion 102 comprises an inner wall or skin 104 and an outer wall or skin 105. Each side portion further comprises an upper plate 106 extending substantially horizontally between an upper end 107 or edge of the inner wall 104 and an upper end or edge 108 of the outer wall 105. The upper plate 106 extends longitudinally from one end 114 of each side portion to the other end 115.

[0039] As shown in more detail in Figures 4 and 5, for each side portion 102, the inner wall 104 is shorter (in a longitudinal direction of the side portion) in length than the outer wall 105 such that an end of the side portion is angled inwards from the outer wall to the inner wall. That is, each side portion is formed such that an inner edge thereof is shorter (in a longitudinal direction of the side portion) in length than an outer edge thereof. As such, an end 114, 115 of the side portion may be angled inwards at an angle α from the outer edge to the inner edge. That is, each end 114, 115 of the side portion is formed with an acute angle such that the side portion is trapezoidal in shape, as shown most clearly in Figure 5. The upper plate 106 of the side portion is in the form of a trapezoid or trapezium, whereby the inner edge of the upper plate is shorter (in a longitudinal direction of the side portion) that the outer edge of the upper plate. In the embodiment shown, the upper plate 106 of the side portion is in the form of an isosceles trapezoid in which the base angles α at each end have the same value.

[0040] The elongate side portions 102 may be formed from a composite plastics material, for example, by pultrusion or other suitable method of manufacture. For example, the material may be a thermoset resin reinforced with continuous lengths of glass fibre. The fibres may be fully wetted out by pulling through a resin bath and then through a steel die so as to form the desired shape. A single elongate profile may be formed by pultrusion and cut to form multiple individual side portions 102 of the stackable ring 101. Each end of the side portion may be cut at an angle to form the trapezoidal shape described above.

[0041] Each side portion 102 further comprises a lower plate 120 extending substantially horizontally between the inner wall 104 and the outer wall 105. In the embodiment shown in Figures 1 to 7, the lower plate extends along the entire length of the side portion. In other embodiments, the lower plate may extend along at least a portion of the length of the side portion. The lower plate 120 is parallel to and spaced apart from the upper plate 106 of the side portion, to define a hollow chamber 123 within the side portion. The lower plate is offset from the lower ends 121 or edges of the inner and outer walls such that the inner and outer walls extend vertically below the lower plate. The lower plate and the lower ends of the inner and outer walls of the side portions may form a recess 122 dimensioned to receive an upper plate 106 of a corresponding stackable ring, when stacked to form a modular access chamber.

[0042] A corner portion 103 of the stackable ring 101 is shown in more detail in Figures 7 and 8. The corner portions may be formed from a composite plastics material, such as a thermoset resin reinforced with glass fibre. The corner portions may typically be manufactured using a compression moulding process using heated steel tooling. Each corner portion 103 also comprises an inner wall or skin 109 and an outer wall or skin 110. Each corner portion further comprises an upper plate 111 extending substantially horizontally between an upper end 112 or edge of the inner wall 109 and an upper end or edge 113 of the outer wall 110. The upper plate 111 extends from one end 116 of each corner portion to the other end 117. The corner portions 103 are formed such that their ends 116, 117 are angled outwards at an angle that is complementary to the angle at which the side portions are angled inwards. In the embodiment shown, the ends of the upper plate of the corner portion are angled outwards at an angle complementary to the angle at which the upper plate of the side portion is angled inwards.

[0043] As shown in Figure 8, a downwardly depending central rib 127, intermediate the inner 109 and outer 110 walls and generally parallel thereto, is provided on the corner portion 103. Perpendicular ribs or webs 128 are provided between the inner wall 109 and the central rib 127, and between the central rib 127 and the outer wall 110. Mounting eyes 129 are provided at the internal corners of the corner portions 103 to allow cable trays or other internal chamber fittings to be mounted internally of the modular access chamber without the need to drill into the chamber walls, as discussed in more detail in relation to Figure 23.

[0044] The corner portions 103 further comprise loops 132 formed at a lower end of the outer wall 110 and corresponding detents or recesses 133 at an upper end of the outer wall 110. The loops and detents are configured to engage with a clip member to allow consecutive stackable rings to be clipped together, as described in more detail below with reference to Figures 19 to 22.

[0045] Connection means in the form of a projection 124 is formed at each end 116 and 117 of the corner portion 103. Each projection 124 is configured to be received in the hollow chamber 123 of an adjacent side portion 102, when the side portions and corner portions are assembled into a stackable ring. The projections are shaped and dimensioned such that a tight push or transition fit is provided between the corner portions and the side portions. The projections 124 are open at their bottom ends and a cutout 125 is provided in the top of each projection to allow compression of the projections so that they can be inserted into the chambers in the adjacent side portions.

[0046] The stackable ring 102 further includes a gasket 126 disposed between each side portion and the adjacent corner portion. As shown in Figure 7, the gasket is flat and has an outer profile corresponding generally to that of the adjacent corner profile. The gasket is formed from an elastomeric or other deformable material, such as EPDM sponge.

[0047] When the side portions and corner portions are assembled into a stackable ring as shown in Figures 1 to 3, an angle α, formed between each side portion 102 and an adjacent corner portion 103, is less than 90 degrees. In the embodiment shown, the angle α is approximately 65 degrees. However, in other embodiments, the angle may be between about 45 degrees and about 85 degrees, and preferably, between about 55 degrees and about 75 degrees. The projections 124 on the corner portions are inserted into the chambers 123 in the side portions and the gaskets 126 are compressed between the side portions and the adjacent corner portions to form a mechanical seal therebetween, thereby preventing water ingress at the connection points between the side and corner portions of the ring. The acute angle formed between the side portion and the adjacent corner portions provides improved compression of the gasket, as compared with a 90 degree joint to further improve watertightness of the ring and thus an access chamber formed therefrom.

[0048] A channel 118 is formed in an upper surface of the upper plate of each side portion and each corner portion, to form a continuous channel in the upper surface of the stackable ring. As shown most clearly in Figure 6, the channel has a dove-tail profile. The channel is located centrally of the upper plate 106, 111 of each side portion and each corner portion. An O-ring 119, which is continuous around the upper surface of the stackable ring 101, is disposed in the continuous channel 118. The dove-tail profile grips the O-ring to retain it in the stackable ring. When the stackable ring 101 is stacked with other rings to form a modular access chamber, the O-ring provides a seal between consecutive rings which prevents water ingress to the chamber.

[0049] A stackable ring 201 for a modular access chamber according to a second embodiment of the present invention is shown in Figures 9 and 10. The stackable ring 201 comprises a plurality of elongate side portions 202 and a corresponding plurality of corner portions 203 connected between adjacent side portions, as described above with reference to the previous embodiment. The stackable ring 201 is suitable for stacking on top of the stackable ring 101, to form a modular access chamber, or part thereof, and may be referred to as a crowning profile.

[0050] As before, the stackable ring 201 defines a substantially rectangular perimeter. As shown, the stackable ring 201 comprises four side portions 102 and four corner portions 203. Each of the side portions is substantially straight and each of the corner portions is curved, to provide a 90 degree angle at the corners of the stackable ring.

[0051] As shown in Figures 9 and 10 and in more detail in Figures 11 to 13, each side portion 202 comprises an inner wall or skin 204 and an outer wall or skin 205. Each side portion further comprises an upper plate 206 extending substantially horizontally between an upper end 207 or edge of the inner wall 204 and an upper end or edge 208 of the outer wall 205. The upper plate 206 extends longitudinally from one end 214 of each side portion to the other end 215. In this embodiment, the upper plate 206 is extended as compared with that of the first embodiment described above so that it extends horizontally beyond the outer wall 205 of the side portion. That is, an extension portion or lip 230 of the upper plate 206 extends beyond the outer wall of the side portion. When the stackable rings are stacked vertically to form a modular access chamber, the extended upper plate provides an extra wide surface at a top end of the modular access chamber which allows bearing pressure from a manhole cover frame to be more evenly distributed and transferred to the access chamber structure, thereby increasing the performance and lifespan of the chamber.

[0052] The upper plate 206 of the stackable ring 202 also has a castellated upper profile, as shown most clearly in Figures 11 and 13, to aid bedding mortar adhesion.

[0053] As shown in more detail in Figures 11 and 12, for each side portion 202, the inner wall 204 is shorter (in a longitudinal direction of the side portion) in length than the outer wall 205 such that an end of the side portion is angled inwards from the outer wall to the inner wall. That is, each side portion is formed such that an inner edge thereof is shorter (in a longitudinal direction of the side portion) in length than an outer edge thereof. As such, an end 214, 215 of the side portion 202 is angled inwards at an angle α from the outer edge to the inner edge. That is, each end 214, 215 of the side portion is formed with an acute angle such that the side portion is trapezoidal in shape, as shown most clearly in Figure 12. The upper plate 206 of the side portion is in the form of a trapezoid or trapezium, whereby the inner edge of the upper plate is shorter (in a longitudinal direction of the side portion) that the outer edge of the upper plate. In the embodiment shown in Figures 9 to 14, the upper plate 206 of the side portion 202 is in the form of an isosceles trapezoid in which the base angles α at each end have the same value.

[0054] The elongate side portions 202 may be formed, for example, by pultrusion or other suitable method of manufacture, as described above.

[0055] Each side portion 202 further comprises a lower plate 220 extending substantially horizontally between the inner wall 204 and the outer wall 205. In the embodiment shown in Figures 9 to 13, the lower plate extends along the entire length of the side portion. In other embodiments, the lower plate may extend along at least a portion of the length of the side portion. The lower plate 220 is parallel to and spaced apart from the upper plate 206 of the side portion, to define a hollow chamber 223 within the side portion. The lower plate is offset from the lower ends 221 or edges of the inner and outer walls such that the inner and outer walls extend vertically below the lower plate. The lower plate and the lower ends of the inner and outer walls of the side portions may form a recess 122 dimensioned to receive an upper plate 206 of a corresponding stackable ring, such as that shown in Figures 1 to 8, when stacked to form a modular access chamber.

[0056] A corner portion 203 of the stackable ring 201 is shown in more detail in Figure 14. Each corner portion 203 also comprises an inner wall or skin 209 and an outer wall or skin 210. Each corner portion further comprises an upper plate 211 extending substantially horizontally between an upper end 212 or edge of the inner wall 209 and an upper end or edge 213 of the outer wall 210. In this embodiment, the upper plate 211 is extended as compared with that of the first embodiment described above so that it extends horizontally beyond the outer wall 210 of the corner portion. That is, an extension portion or lip 231 of the upper plate 211 extends beyond the outer wall of the corner portion.

[0057] The upper plate 211 extends from one end 216 of each corner portion to the other end 217. The corner portions 203 are formed such that their ends 216, 217 are angled outwards at an angle that is complementary to the angle at which the side portions are angled inwards. In the embodiment shown, the ends of the upper plate of the corner portion are angled outwards at a complementary to the angle at which the upper plate of the side portion is angled inwards.

[0058] Although not specifically shown in Figures 9 to 14, the corner portion 203 may also comprise a downwardly depending central rib corresponding to that shown in Figure 8, intermediate the inner 209 and outer 210 walls and generally parallel thereto. As in the first embodiment, perpendicular ribs or webs may be provided between the inner wall 209 and the central rib, and between the central rib and the outer wall 210.

[0059] The corner portions 203 further comprise loops 232 formed at a lower end of the outer wall 210. The loops are configured to engage with a clip member to allow consecutive stackable rings to be clipped together, as described in more detail below with reference to Figures 19 to 22.

[0060] As shown in Figure 19, connection means in the form of a projection 224 is formed at each end 216 and 217 of the corner portion 203. Each projection 224 is configured to be received in the hollow chamber 223 of an adjacent side portion 202, when the side portions and corner portions are assembled into a stackable ring. The projections are shaped and dimensioned such that a tight push or transition fit is provided between the corner portions and the side portions. The projections 224 are open at their bottom ends and a cutout 225 is provided in the top of each projection to allow compression of the projections so that they can be inserted into the chambers in the adjacent side portions.

[0061] As shown in Figure 14, the stackable ring 202 further includes a gasket 226 disposed between each side portion and the adjacent corner portion. The gasket is flat and has an outer profile corresponding generally to that of the adjacent corner profile. The gasket is formed from an elastomeric or other deformable material.

[0062] In the embodiment shown, a nut 234, such as an M12 nut, is glued into the upper plate 211 of the corner portions 203. This may be used to assist with levelling of a manhole or access chamber frame that may be placed on top of the modular access chamber when installed, using corresponding M12 bolts attached to a flange of the frame.

[0063] As discussed above in relation to the first embodiment, when the side portions and corner portions are assembled into a stackable ring as shown in Figures 9, 10 and 14, an angle α, formed between each side portion 102 and an adjacent corner portion 103, is less than 90 degrees. In the embodiment shown, the angle α is approximately 65 degrees. However, in other embodiments, the angle may be between about 45 degrees and about 85 degrees, and preferably, between about 55 degrees and about 75 degrees. The projections 224 on the corner portions are inserted into the chambers 223 in the side portions and the gaskets 226 are compressed between the side portions and the adjacent corner portions as shown in Figure 14, to form a mechanical seal therebetween, thereby preventing water ingress at the connection points between the side and corner portions of the ring. The acute angle formed between the side portion and the adjacent corner portions provides improved compression of the gasket, as compared with a 90 degree joint to further improve watertightness of the ring and thus an access chamber formed therefrom.

[0064] The stackable rings 101, 201 described above may be stacked vertically, one on top of the other, such that a lower end of a first stackable ring engages an upper end of a second stackable ring to form a modular access chamber 300, as shown in Figures 15 to 22. Preferably, one or more stackable rings 101 as described above with reference to Figures 1 to 8 are stacked vertically, and then a crowning profile, such as that described above with reference to Figures 9 to 14, is placed on top to provide a modular access chamber of the required height.

[0065] As shown most clearly in Figure 18, when the first stackable ring 201 is stacked on top of stackable ring 101, the lower plate 220 of each side portion of the first stackable ring 201 engages the upper plate 106 of the second stackable ring. As described above, the lower plate 220 of the first stackable ring is offset from lower ends 221 of the inner and outer walls such that the inner and outer walls extend vertically below the lower plate, to form a recess 222 dimensioned to receive the upper plate 106 of the second stackable ring. The edges of the upper plate 106 are rebated so that it is received in the recess 222 in the first stackable ring. When the rings are stacked as shown in Figure 18, the O-ring 119 provides a seal between the upper plate 106 of the second stackable ring and the lower plate 220 of the first stackable ring.

[0066] As shown in Figures 17 and 19, the corner portions 103, 203 of the stackable rings also engage with one another. As with the side portions, the edges of the upper plate 111 of each corner portion of the second stackable ring 101 are rebated so that they are received between the lower ends of the inner 209 and outer 210 walls of the first stackable ring, to provide a tight push fit connection. The central rib of the stackable section 201 engages the O-ring in the stackable section below. The push fit between the corner portions resists the opening pressure exerted by the O-ring.

[0067] As illustrated in Figures 19 to 22, a clip mechanism is also provided to maintain the vertical compression of the O-ring between the stackable rings so as to maintain watertightness, while also allowing the assembled chamber to be easily handled on site and during transportation as a single unit. As described above, each of the corner portions comprises a pair of loops 132, 232 at a lower end of the outer wall 110, 210 thereof. The corner portions of the lower stackable rings 101 also include a corresponding pair of detents or recesses 133 at an upper end of the outer wall 110. When the rings have been stacked together, a clip member 335 is inserted into each loop on each of the upper stackable rings. A shoulder 336 on the outside of clip member engages the loop 232 and a shoulder 337 on the inside of the clip member is received in the corresponding detent 133 on the lower corner portion. The clip member acts to exert a compressive force on the upper and lower stackable rings, which compresses the O-ring, thereby improving watertightness. In an alternative embodiment, an interference fit may be provided between adjacent stackable rings.

[0068] Figure 23 shows a cable tray 338 mounted to steel bracketry which is connected to one of the mounting eyes 129 provided on the corner portion 103. In other embodiments, other internal chamber fittings may be mounted to the interior of the modular access chamber in a similar manner, without the need to drill into the chamber walls

[0069] The words "comprises / comprising" and the words "having / including" when used herein with reference to the present invention are used to specify the presence of stated features, integers, steps or components but does not preclude the presence or addition of one or more other features, integers, steps, components or groups thereof.

[0070] It is appreciated that certain features of the invention, which are, for clarity, described in the context of separate embodiments, may also be provided in combination in a single embodiment. Conversely, various features of the invention which are, for brevity, described in the context of a single embodiment, may also be provided separately or in any suitable sub-combination.

Examples

first embodiment

[0036]A stackable ring 101 for a modular access chamber according to the present invention is shown in Figures 1 to 3. The stackable ring 101 comprises a plurality of elongate side portions 102 and a corresponding plurality of corner portions 103 connected between adjacent side portions.

[0037]In the embodiment shown in Figures 1 to 3, the stackable ring 101 defines a substantially rectangular perimeter. As shown, the stackable ring 101 comprises four side portions 102 and four corner portions 103. Each of the side portions is substantially straight and each of the corner portions is curved, to provide a 90 degree angle at the corners of the stackable ring. In other embodiments, the perimeter of the ring may be a different shape and the corner portions may be formed with the appropriate degree of curvature to provide the required shape.

[0038]As shown in Figures 1 to 3 and in more detail in Figures 4 to 6, each side portion 102 comprises an inner wall or skin 104 and an outer wall or ...

second embodiment

[0049]A stackable ring 201 for a modular access chamber according to the present invention is shown in Figures 9 and 10. The stackable ring 201 comprises a plurality of elongate side portions 202 and a corresponding plurality of corner portions 203 connected between adjacent side portions, as described above with reference to the previous embodiment. The stackable ring 201 is suitable for stacking on top of the stackable ring 101, to form a modular access chamber, or part thereof, and may be referred to as a crowning profile.

[0050]As before, the stackable ring 201 defines a substantially rectangular perimeter. As shown, the stackable ring 201 comprises four side portions 102 and four corner portions 203. Each of the side portions is substantially straight and each of the corner portions is curved, to provide a 90 degree angle at the corners of the stackable ring.

[0051]As shown in Figures 9 and 10 and in more detail in Figures 11 to 13, each side portion 202 comprises an inner wall o...

Field of the Invention

[0001] The present invention relates to a modular access chamber and to stackable rings that may be stacked together to form such an access chamber.Background to the Invention

[0002] Utility services such as electricity, gas and water are typically laid underground. Valves, electrical junctions and meters are provided in underground access chambers (or manhole chambers) which can be accessed at designated points via access covers (or manhole covers). Rapid and economical construction of these access chambers is a key requirement of utility providers. Many construction companies also wish to minimise the carbon footprint associated with the materials used in the construction of these chambers while also improving safety.

[0003] Traditionally, underground infrastructure access chambers have been manufactured from precast concrete, brick or other traditional materials. These materials are heavy, carbon intensive and require specialised lifting equipment to handle and install. Concrete is one of the largest contributors to the carbon footprint of the construction industry.

[0004] More recently, glass fibre reinforced composite plastics materials have been used as a way to create lightweight chamber products. One example is proposed in British Patent Application Publication No. 2 404 409, which describes a modular chamber having a base and side wall, the sidewall comprising a plurality of side wall units stacked one on top of another. Each side wall unit comprises a plurality of elongate, hollow, wall members and a plurality of connector members.

[0005] A disadvantage of existing composite access chambers is that, due to their modular nature, water may enter the chamber between the modular elements, which increases the risk of damage to the equipment located in the chamber. Another disadvantage is that composite chambers may have reduced strength as compared with traditional concrete chambers.Summary of the Invention

[0006] The present invention relates to a stackable ring for a modular access chamber, comprising: a plurality of elongate side portions; and a corresponding plurality of corner portions connected between adjacent side portions, and wherein an angle formed between each side portion and an adjacent corner portion is less than 90 degrees.

[0007] The stackable ring may be formed from a plastics material and, preferably, a composite plastics material.

[0008] Connection means may be provided on or engaged with each corner portion for connection to adjacent side portions.

[0009] The angle formed between each side portion and the adjacent corner portion is preferably between about 45 degrees and about 85 degrees. Preferably, the angle is between about 55 degrees and about 75 degrees. More preferably, the angle is approximately 65 degrees.

[0010] In an embodiment, the stackable ring defines a perimeter that is substantially rectangular in shape. In this embodiment, the stackable ring may comprise four side portions and four corner portions. In other embodiments, the perimeter of the ring may be a different shape. Preferably, the side portions are substantially straight. The corner portions may be curved or angled.

[0011] Each side portion may be formed such that an inner edge thereof is shorter (in a longitudinal direction of the side portion) in length than an outer edge thereof. As such, an end of the side portion may be angled inwards from the outer edge to the inner edge. Each side portion may be trapezoidal in shape. The corner portions may be formed such that their ends are angled outwards at an angle complementary to the angle at which the side portions are angled inwards.

[0012] Each side portion and / or each corner portion may comprise: an inner wall; an outer wall; and an upper plate extending substantially horizontally between an upper end or edge of the inner wall and an upper end or edge of the outer wall.

[0013] The upper plate may extend from one end of each side portion to the other. The upper plate may extend from one end of each corner portion to the other.

[0014] For each side portion, the inner wall may be shorter (in a longitudinal direction of the side portion) in length than the outer wall such that an end of the side portion is angled inwards from the outer wall to the inner wall.

[0015] Each end of the side portion may be formed with an acute angle such that the side portion is trapezoidal in shape, that is, the upper plate of the side portion may be in the form of a trapezoid or trapezium, whereby the inner edge of the upper plate is shorter (in a longitudinal direction of the side portion) that the outer edge of the upper plate. For example, the upper plate of the side portion may take the form of an isosceles trapezoid in which the base angles at each end have the same value.

[0016] For each corner portion, an end of the upper plate may be angled outwards from the outer wall to the inner wall, wherein the angle is complementary to the angle formed by the adjacent side portion.

[0017] The elongate side portions may be formed, for example, by pultrusion or other suitable method of manufacture. A single elongate profile may be formed by pultrusion and cut to form multiple individual side portions of the stackable ring. Each end of the side portion may be cut at an angle to form the trapezoidal shape described above. Each side portion may be hollow.

[0018] An advantage of the proposed arrangement in which the angle formed between each side portion and the adjacent corner portion is less than 90 degrees is that it maximises the strength of the stackable ring by transferring stress from the elongate side portions to the corner portions. This in turn provides improved resistance to side wall loading pressure as a result of the soil surrounding the chamber.

[0019] The stackable ring may further comprise a gasket disposed between each side portion and the adjacent corner portion. Preferably the gasket is flat and has an outer profile corresponding to that of the adjacent corner portion. The gasket may be formed from an elastomeric or other deformable material. An example of a suitable material is Ethylene Propylene Diene Monomer (EPDM) sponge rubber.

[0020] When the stackable ring is assembled, the gasket is compressed between the side portions and the adjacent corner portions to form a mechanical seal therebetween, thereby preventing water ingress at the connection points between the side and corner portions of the ring. The acute angle formed between the side portion and the adjacent corner portions provides improved compression of the gasket, as compared with a 90 degree joint, to further improve watertightness of the ring and thus an access chamber formed therefrom.

[0021] The stackable ring may further comprise an O-ring disposed in an upper surface thereof. Preferably, the O-ring is disposed centrally of the upper surface of the stackable ring. The O-ring is preferably continuous around the upper surface of the stackable ring.

[0022] For example, a channel may be formed in an upper surface of the upper plate of each side portion and each corner portion, to form a continuous channel in the upper surface of the stackable ring. Preferably, the channel has a dove-tail profile. The channel may be located centrally of the upper plate of each side portion and each corner portion. The O-ring may be disposed in the continuous channel.

[0023] An advantage of this arrangement is that, when the stackable rings are stacked to form a modular access chamber, the O-ring provides a seal between consecutive rings which prevents water ingress to the chamber. The dove-tail profile grips the O-ring to retain it in the stackable ring.

[0024] The upper plate of a stackable ring suitable for use as an uppermost stackable ring of a modular access chamber may extend horizontally beyond the outer wall. This uppermost stackable ring may be referred to as a crowning profile. By extending horizontally beyond the outer wall of the stackable ring, the crowning profile provides an extra wide surface at a top end of the modular access chamber which allows bearing pressure from a manhole cover frame to be more evenly distributed and transferred to the access chamber structure, thereby increasing the performance and lifespan of the chamber. The upper plate of the stackable ring suitable for use as an uppermost stackable ring may also have a castellated upper profile to aid bedding mortar adhesion.

[0025] Each side portion may further comprise a lower plate extending substantially horizontally between the inner wall and the outer wall along at least a portion of the length of the side portion. The lower plate may be parallel to and spaced apart from an upper plate of the side portion. The lower plate may be offset from lower ends or edges of the inner and outer walls such that the inner and outer walls extend vertically below the lower plate. The lower plate and the lower ends of the inner and outer walls of the side portions may form a recess dimensioned to receive an upper plate of a corresponding stackable ring, when stacked to form a modular access chamber.

[0026] According to another aspect of the invention, there is provided a modular access chamber, comprising: a plurality of stackable rings, each stackable ring comprising: a plurality of elongate side portions; and a corresponding plurality of corner portions connected between adjacent side portions, and wherein an angle formed between each side portion and an adjacent corner portion is less than 90 degrees; wherein the stackable rings are stacked vertically such that a lower end of a first stackable ring of the plurality of stackable rings engages an upper end of a second stackable ring of the plurality of stackable rings.

[0027] Each side portion and each corner portion of each stackable ring may comprise: an inner wall; an outer wall; and an upper plate extending substantially horizontally between an upper end of the inner wall and an upper end of the outer wall.

[0028] The upper plate of the first stackable ring may extend horizontally beyond the outer wall. The upper plate of the first stackable ring may have a castellated upper profile.

[0029] Each side portion of at least the first stackable ring may further comprise a lower plate extending horizontally between the inner wall and the outer wall along the length of the side portion. The lower plate of the first stackable ring may engage the upper plate of the second stackable ring. The lower plate of the first stackable ring may be offset from lower ends or edges of the inner and outer walls such that the inner and outer walls extend vertically below the lower plate. The lower plate and the lower ends of the inner and outer walls of the side portions may form a recess dimensioned to receive an upper plate of the second stackable ring. The upper plate of the second stackable ring may be received in the recess in the first stackable ring according to an interference fit.

[0030] The second stackable ring may comprise an O-ring disposed in an upper surface thereof. Preferably, the O-ring is disposed centrally of the upper surface of the second stackable ring. The O-ring is preferably continuous around the upper surface of the second stackable ring. A channel may be formed in an upper surface of the upper plate of each side portion and each corner portion of the second stackable ring, to form a continuous channel in an upper surface of the second stackable ring. The O-ring may be disposed in the channel. The O-ring may provide a seal between the upper plate of the second stackable ring and the lower plate of the first stackable ring.

[0031] The modular access chamber may further comprise a clip mechanism for securing the first stackable ring to the second stackable ring. The clip mechanism engages each of the first and second stackable rings to cause a vertical compressive force therebetween. The clip mechanism may provide vertical compression of the O-ring between the stackable rings so as to maintain watertightness, while also allowing the assembled chamber to be easily handled on site and during transportation as a single unit.

[0032] The terms "upper", "lower", "inner", "outer", "inwards", outwards", "horizontally", "vertical", etc. are used herein to refer to the stackable ring and modular access chamber as per the intended orientation and are not intended to be otherwise limiting.

[0033] According to another aspect of the invention, there is provided an elongate side portion for a stackable ring for a modular access chamber, the elongate side portion comprising: an inner wall; an outer wall; and an upper plate extending substantially horizontally between an upper end or edge of the inner wall and an upper end or edge of the outer wall, wherein the inner wall is shorter (in a longitudinal direction of the side portion) than the outer wall such that an end of the side portion is angled inwards from the outer wall to the inner wall.

[0034] Each end of the elongate side portion may be connectable to a corresponding corner portion of a stackable ring for a modular access chamber.Brief Description of the Drawings

[0035] Figure 1 is a perspective view of a first embodiment of a stackable ring for a modular access chamber; Figure 2 is a rear perspective view of the stackable ring of Figure 1; Figure 3 is a top plan view of the stackable ring of Figure 1; Figure 4 is a perspective view of a side portion of the stackable ring of Figure 1; Figure 5 is a top plan view of the side portion of Figure 4; Figure 6 is a cross-sectional view of the side portion of Figure 4; Figure 7 is a perspective view of a corner portion of the stackable ring of Figure 1; Figure 8 is a perspective view, from underneath, of the corner portion of Figure 7 Figure 9 is a perspective view of a second embodiment of a stackable ring for a modular access chamber; Figure 10 is a top plan view of the stackable ring of Figure 9; Figure 11 is a perspective view of a side portion of the stackable ring of Figure 9; Figure 12 top plan view of the side portion of Figure 11; Figure 13 is a cross-sectional view of the side portion of Figure 11; Figure 14 is a top-plan view of a portion of the stackable ring of Figure 9, showing a corner portion and two adjacent side portions; Figure 15 is a perspective view of a modular access chamber according to an aspect of the present invention; Figure 16 is a cutaway perspective view of the modular access chamber of Figure 15; Figure 17 is a perspective view of a portion of the modular access chamber of Figure 15; Figure 18 is a cross-sectional view through the side portions of two stackable rings of the modular access chamber of Figure 15; Figure 19 is a perspective view of corner portions of two stackable rings of the modular access chamber of Figure 15; Figure 20 is a perspective view of a clip member for connecting adjacent stackable rings of the modular access chamber of Figure 15; Figure 21 is a perspective view of a clip member for connecting adjacent stackable rings of the modular access chamber of Figure 15; Figure 22 is a perspective view of a clip member in situ in adjacent stackable rings of the modular access chamber of Figure 15; and Figure 23 is a perspective view of a portion of the modular access chamber of Figure 15, with an accessory mounted thereon. Detailed Description of the Drawings

[0036] A stackable ring 101 for a modular access chamber according to a first embodiment of the present invention is shown in Figures 1 to 3. The stackable ring 101 comprises a plurality of elongate side portions 102 and a corresponding plurality of corner portions 103 connected between adjacent side portions.

[0037] In the embodiment shown in Figures 1 to 3, the stackable ring 101 defines a substantially rectangular perimeter. As shown, the stackable ring 101 comprises four side portions 102 and four corner portions 103. Each of the side portions is substantially straight and each of the corner portions is curved, to provide a 90 degree angle at the corners of the stackable ring. In other embodiments, the perimeter of the ring may be a different shape and the corner portions may be formed with the appropriate degree of curvature to provide the required shape.

[0038] As shown in Figures 1 to 3 and in more detail in Figures 4 to 6, each side portion 102 comprises an inner wall or skin 104 and an outer wall or skin 105. Each side portion further comprises an upper plate 106 extending substantially horizontally between an upper end 107 or edge of the inner wall 104 and an upper end or edge 108 of the outer wall 105. The upper plate 106 extends longitudinally from one end 114 of each side portion to the other end 115.

[0039] As shown in more detail in Figures 4 and 5, for each side portion 102, the inner wall 104 is shorter (in a longitudinal direction of the side portion) in length than the outer wall 105 such that an end of the side portion is angled inwards from the outer wall to the inner wall. That is, each side portion is formed such that an inner edge thereof is shorter (in a longitudinal direction of the side portion) in length than an outer edge thereof. As such, an end 114, 115 of the side portion may be angled inwards at an angle α from the outer edge to the inner edge. That is, each end 114, 115 of the side portion is formed with an acute angle such that the side portion is trapezoidal in shape, as shown most clearly in Figure 5. The upper plate 106 of the side portion is in the form of a trapezoid or trapezium, whereby the inner edge of the upper plate is shorter (in a longitudinal direction of the side portion) that the outer edge of the upper plate. In the embodiment shown, the upper plate 106 of the side portion is in the form of an isosceles trapezoid in which the base angles α at each end have the same value.

[0040] The elongate side portions 102 may be formed from a composite plastics material, for example, by pultrusion or other suitable method of manufacture. For example, the material may be a thermoset resin reinforced with continuous lengths of glass fibre. The fibres may be fully wetted out by pulling through a resin bath and then through a steel die so as to form the desired shape. A single elongate profile may be formed by pultrusion and cut to form multiple individual side portions 102 of the stackable ring 101. Each end of the side portion may be cut at an angle to form the trapezoidal shape described above.

[0041] Each side portion 102 further comprises a lower plate 120 extending substantially horizontally between the inner wall 104 and the outer wall 105. In the embodiment shown in Figures 1 to 7, the lower plate extends along the entire length of the side portion. In other embodiments, the lower plate may extend along at least a portion of the length of the side portion. The lower plate 120 is parallel to and spaced apart from the upper plate 106 of the side portion, to define a hollow chamber 123 within the side portion. The lower plate is offset from the lower ends 121 or edges of the inner and outer walls such that the inner and outer walls extend vertically below the lower plate. The lower plate and the lower ends of the inner and outer walls of the side portions may form a recess 122 dimensioned to receive an upper plate 106 of a corresponding stackable ring, when stacked to form a modular access chamber.

[0042] A corner portion 103 of the stackable ring 101 is shown in more detail in Figures 7 and 8. The corner portions may be formed from a composite plastics material, such as a thermoset resin reinforced with glass fibre. The corner portions may typically be manufactured using a compression moulding process using heated steel tooling. Each corner portion 103 also comprises an inner wall or skin 109 and an outer wall or skin 110. Each corner portion further comprises an upper plate 111 extending substantially horizontally between an upper end 112 or edge of the inner wall 109 and an upper end or edge 113 of the outer wall 110. The upper plate 111 extends from one end 116 of each corner portion to the other end 117. The corner portions 103 are formed such that their ends 116, 117 are angled outwards at an angle that is complementary to the angle at which the side portions are angled inwards. In the embodiment shown, the ends of the upper plate of the corner portion are angled outwards at an angle complementary to the angle at which the upper plate of the side portion is angled inwards.

[0043] As shown in Figure 8, a downwardly depending central rib 127, intermediate the inner 109 and outer 110 walls and generally parallel thereto, is provided on the corner portion 103. Perpendicular ribs or webs 128 are provided between the inner wall 109 and the central rib 127, and between the central rib 127 and the outer wall 110. Mounting eyes 129 are provided at the internal corners of the corner portions 103 to allow cable trays or other internal chamber fittings to be mounted internally of the modular access chamber without the need to drill into the chamber walls, as discussed in more detail in relation to Figure 23.

[0044] The corner portions 103 further comprise loops 132 formed at a lower end of the outer wall 110 and corresponding detents or recesses 133 at an upper end of the outer wall 110. The loops and detents are configured to engage with a clip member to allow consecutive stackable rings to be clipped together, as described in more detail below with reference to Figures 19 to 22.

[0045] Connection means in the form of a projection 124 is formed at each end 116 and 117 of the corner portion 103. Each projection 124 is configured to be received in the hollow chamber 123 of an adjacent side portion 102, when the side portions and corner portions are assembled into a stackable ring. The projections are shaped and dimensioned such that a tight push or transition fit is provided between the corner portions and the side portions. The projections 124 are open at their bottom ends and a cutout 125 is provided in the top of each projection to allow compression of the projections so that they can be inserted into the chambers in the adjacent side portions.

[0046] The stackable ring 102 further includes a gasket 126 disposed between each side portion and the adjacent corner portion. As shown in Figure 7, the gasket is flat and has an outer profile corresponding generally to that of the adjacent corner profile. The gasket is formed from an elastomeric or other deformable material, such as EPDM sponge.

[0047] When the side portions and corner portions are assembled into a stackable ring as shown in Figures 1 to 3, an angle α, formed between each side portion 102 and an adjacent corner portion 103, is less than 90 degrees. In the embodiment shown, the angle α is approximately 65 degrees. However, in other embodiments, the angle may be between about 45 degrees and about 85 degrees, and preferably, between about 55 degrees and about 75 degrees. The projections 124 on the corner portions are inserted into the chambers 123 in the side portions and the gaskets 126 are compressed between the side portions and the adjacent corner portions to form a mechanical seal therebetween, thereby preventing water ingress at the connection points between the side and corner portions of the ring. The acute angle formed between the side portion and the adjacent corner portions provides improved compression of the gasket, as compared with a 90 degree joint to further improve watertightness of the ring and thus an access chamber formed therefrom.

[0048] A channel 118 is formed in an upper surface of the upper plate of each side portion and each corner portion, to form a continuous channel in the upper surface of the stackable ring. As shown most clearly in Figure 6, the channel has a dove-tail profile. The channel is located centrally of the upper plate 106, 111 of each side portion and each corner portion. An O-ring 119, which is continuous around the upper surface of the stackable ring 101, is disposed in the continuous channel 118. The dove-tail profile grips the O-ring to retain it in the stackable ring. When the stackable ring 101 is stacked with other rings to form a modular access chamber, the O-ring provides a seal between consecutive rings which prevents water ingress to the chamber.

[0049] A stackable ring 201 for a modular access chamber according to a second embodiment of the present invention is shown in Figures 9 and 10. The stackable ring 201 comprises a plurality of elongate side portions 202 and a corresponding plurality of corner portions 203 connected between adjacent side portions, as described above with reference to the previous embodiment. The stackable ring 201 is suitable for stacking on top of the stackable ring 101, to form a modular access chamber, or part thereof, and may be referred to as a crowning profile.

[0050] As before, the stackable ring 201 defines a substantially rectangular perimeter. As shown, the stackable ring 201 comprises four side portions 102 and four corner portions 203. Each of the side portions is substantially straight and each of the corner portions is curved, to provide a 90 degree angle at the corners of the stackable ring.

[0051] As shown in Figures 9 and 10 and in more detail in Figures 11 to 13, each side portion 202 comprises an inner wall or skin 204 and an outer wall or skin 205. Each side portion further comprises an upper plate 206 extending substantially horizontally between an upper end 207 or edge of the inner wall 204 and an upper end or edge 208 of the outer wall 205. The upper plate 206 extends longitudinally from one end 214 of each side portion to the other end 215. In this embodiment, the upper plate 206 is extended as compared with that of the first embodiment described above so that it extends horizontally beyond the outer wall 205 of the side portion. That is, an extension portion or lip 230 of the upper plate 206 extends beyond the outer wall of the side portion. When the stackable rings are stacked vertically to form a modular access chamber, the extended upper plate provides an extra wide surface at a top end of the modular access chamber which allows bearing pressure from a manhole cover frame to be more evenly distributed and transferred to the access chamber structure, thereby increasing the performance and lifespan of the chamber.

[0052] The upper plate 206 of the stackable ring 202 also has a castellated upper profile, as shown most clearly in Figures 11 and 13, to aid bedding mortar adhesion.

[0053] As shown in more detail in Figures 11 and 12, for each side portion 202, the inner wall 204 is shorter (in a longitudinal direction of the side portion) in length than the outer wall 205 such that an end of the side portion is angled inwards from the outer wall to the inner wall. That is, each side portion is formed such that an inner edge thereof is shorter (in a longitudinal direction of the side portion) in length than an outer edge thereof. As such, an end 214, 215 of the side portion 202 is angled inwards at an angle α from the outer edge to the inner edge. That is, each end 214, 215 of the side portion is formed with an acute angle such that the side portion is trapezoidal in shape, as shown most clearly in Figure 12. The upper plate 206 of the side portion is in the form of a trapezoid or trapezium, whereby the inner edge of the upper plate is shorter (in a longitudinal direction of the side portion) that the outer edge of the upper plate. In the embodiment shown in Figures 9 to 14, the upper plate 206 of the side portion 202 is in the form of an isosceles trapezoid in which the base angles α at each end have the same value.

[0054] The elongate side portions 202 may be formed, for example, by pultrusion or other suitable method of manufacture, as described above.

[0055] Each side portion 202 further comprises a lower plate 220 extending substantially horizontally between the inner wall 204 and the outer wall 205. In the embodiment shown in Figures 9 to 13, the lower plate extends along the entire length of the side portion. In other embodiments, the lower plate may extend along at least a portion of the length of the side portion. The lower plate 220 is parallel to and spaced apart from the upper plate 206 of the side portion, to define a hollow chamber 223 within the side portion. The lower plate is offset from the lower ends 221 or edges of the inner and outer walls such that the inner and outer walls extend vertically below the lower plate. The lower plate and the lower ends of the inner and outer walls of the side portions may form a recess 122 dimensioned to receive an upper plate 206 of a corresponding stackable ring, such as that shown in Figures 1 to 8, when stacked to form a modular access chamber.

[0056] A corner portion 203 of the stackable ring 201 is shown in more detail in Figure 14. Each corner portion 203 also comprises an inner wall or skin 209 and an outer wall or skin 210. Each corner portion further comprises an upper plate 211 extending substantially horizontally between an upper end 212 or edge of the inner wall 209 and an upper end or edge 213 of the outer wall 210. In this embodiment, the upper plate 211 is extended as compared with that of the first embodiment described above so that it extends horizontally beyond the outer wall 210 of the corner portion. That is, an extension portion or lip 231 of the upper plate 211 extends beyond the outer wall of the corner portion.

[0057] The upper plate 211 extends from one end 216 of each corner portion to the other end 217. The corner portions 203 are formed such that their ends 216, 217 are angled outwards at an angle that is complementary to the angle at which the side portions are angled inwards. In the embodiment shown, the ends of the upper plate of the corner portion are angled outwards at a complementary to the angle at which the upper plate of the side portion is angled inwards.

[0058] Although not specifically shown in Figures 9 to 14, the corner portion 203 may also comprise a downwardly depending central rib corresponding to that shown in Figure 8, intermediate the inner 209 and outer 210 walls and generally parallel thereto. As in the first embodiment, perpendicular ribs or webs may be provided between the inner wall 209 and the central rib, and between the central rib and the outer wall 210.

[0059] The corner portions 203 further comprise loops 232 formed at a lower end of the outer wall 210. The loops are configured to engage with a clip member to allow consecutive stackable rings to be clipped together, as described in more detail below with reference to Figures 19 to 22.

[0060] As shown in Figure 19, connection means in the form of a projection 224 is formed at each end 216 and 217 of the corner portion 203. Each projection 224 is configured to be received in the hollow chamber 223 of an adjacent side portion 202, when the side portions and corner portions are assembled into a stackable ring. The projections are shaped and dimensioned such that a tight push or transition fit is provided between the corner portions and the side portions. The projections 224 are open at their bottom ends and a cutout 225 is provided in the top of each projection to allow compression of the projections so that they can be inserted into the chambers in the adjacent side portions.

[0061] As shown in Figure 14, the stackable ring 202 further includes a gasket 226 disposed between each side portion and the adjacent corner portion. The gasket is flat and has an outer profile corresponding generally to that of the adjacent corner profile. The gasket is formed from an elastomeric or other deformable material.

[0062] In the embodiment shown, a nut 234, such as an M12 nut, is glued into the upper plate 211 of the corner portions 203. This may be used to assist with levelling of a manhole or access chamber frame that may be placed on top of the modular access chamber when installed, using corresponding M12 bolts attached to a flange of the frame.

[0063] As discussed above in relation to the first embodiment, when the side portions and corner portions are assembled into a stackable ring as shown in Figures 9, 10 and 14, an angle α, formed between each side portion 102 and an adjacent corner portion 103, is less than 90 degrees. In the embodiment shown, the angle α is approximately 65 degrees. However, in other embodiments, the angle may be between about 45 degrees and about 85 degrees, and preferably, between about 55 degrees and about 75 degrees. The projections 224 on the corner portions are inserted into the chambers 223 in the side portions and the gaskets 226 are compressed between the side portions and the adjacent corner portions as shown in Figure 14, to form a mechanical seal therebetween, thereby preventing water ingress at the connection points between the side and corner portions of the ring. The acute angle formed between the side portion and the adjacent corner portions provides improved compression of the gasket, as compared with a 90 degree joint to further improve watertightness of the ring and thus an access chamber formed therefrom.

[0064] The stackable rings 101, 201 described above may be stacked vertically, one on top of the other, such that a lower end of a first stackable ring engages an upper end of a second stackable ring to form a modular access chamber 300, as shown in Figures 15 to 22. Preferably, one or more stackable rings 101 as described above with reference to Figures 1 to 8 are stacked vertically, and then a crowning profile, such as that described above with reference to Figures 9 to 14, is placed on top to provide a modular access chamber of the required height.

[0065] As shown most clearly in Figure 18, when the first stackable ring 201 is stacked on top of stackable ring 101, the lower plate 220 of each side portion of the first stackable ring 201 engages the upper plate 106 of the second stackable ring. As described above, the lower plate 220 of the first stackable ring is offset from lower ends 221 of the inner and outer walls such that the inner and outer walls extend vertically below the lower plate, to form a recess 222 dimensioned to receive the upper plate 106 of the second stackable ring. The edges of the upper plate 106 are rebated so that it is received in the recess 222 in the first stackable ring. When the rings are stacked as shown in Figure 18, the O-ring 119 provides a seal between the upper plate 106 of the second stackable ring and the lower plate 220 of the first stackable ring.

[0066] As shown in Figures 17 and 19, the corner portions 103, 203 of the stackable rings also engage with one another. As with the side portions, the edges of the upper plate 111 of each corner portion of the second stackable ring 101 are rebated so that they are received between the lower ends of the inner 209 and outer 210 walls of the first stackable ring, to provide a tight push fit connection. The central rib of the stackable section 201 engages the O-ring in the stackable section below. The push fit between the corner portions resists the opening pressure exerted by the O-ring.

[0067] As illustrated in Figures 19 to 22, a clip mechanism is also provided to maintain the vertical compression of the O-ring between the stackable rings so as to maintain watertightness, while also allowing the assembled chamber to be easily handled on site and during transportation as a single unit. As described above, each of the corner portions comprises a pair of loops 132, 232 at a lower end of the outer wall 110, 210 thereof. The corner portions of the lower stackable rings 101 also include a corresponding pair of detents or recesses 133 at an upper end of the outer wall 110. When the rings have been stacked together, a clip member 335 is inserted into each loop on each of the upper stackable rings. A shoulder 336 on the outside of clip member engages the loop 232 and a shoulder 337 on the inside of the clip member is received in the corresponding detent 133 on the lower corner portion. The clip member acts to exert a compressive force on the upper and lower stackable rings, which compresses the O-ring, thereby improving watertightness. In an alternative embodiment, an interference fit may be provided between adjacent stackable rings.

[0068] Figure 23 shows a cable tray 338 mounted to steel bracketry which is connected to one of the mounting eyes 129 provided on the corner portion 103. In other embodiments, other internal chamber fittings may be mounted to the interior of the modular access chamber in a similar manner, without the need to drill into the chamber walls

[0069] The words "comprises / comprising" and the words "having / including" when used herein with reference to the present invention are used to specify the presence of stated features, integers, steps or components but does not preclude the presence or addition of one or more other features, integers, steps, components or groups thereof.

[0070] It is appreciated that certain features of the invention, which are, for clarity, described in the context of separate embodiments, may also be provided in combination in a single embodiment. Conversely, various features of the invention which are, for brevity, described in the context of a single embodiment, may also be provided separately or in any suitable sub-combination.

Examples

first embodiment

[0036]A stackable ring 101 for a modular access chamber according to the present invention is shown in Figures 1 to 3. The stackable ring 101 comprises a plurality of elongate side portions 102 and a corresponding plurality of corner portions 103 connected between adjacent side portions.

[0037]In the embodiment shown in Figures 1 to 3, the stackable ring 101 defines a substantially rectangular perimeter. As shown, the stackable ring 101 comprises four side portions 102 and four corner portions 103. Each of the side portions is substantially straight and each of the corner portions is curved, to provide a 90 degree angle at the corners of the stackable ring. In other embodiments, the perimeter of the ring may be a different shape and the corner portions may be formed with the appropriate degree of curvature to provide the required shape.

[0038]As shown in Figures 1 to 3 and in more detail in Figures 4 to 6, each side portion 102 comprises an inner wall or skin 104 and an outer wall or ...

second embodiment

[0049]A stackable ring 201 for a modular access chamber according to the present invention is shown in Figures 9 and 10. The stackable ring 201 comprises a plurality of elongate side portions 202 and a corresponding plurality of corner portions 203 connected between adjacent side portions, as described above with reference to the previous embodiment. The stackable ring 201 is suitable for stacking on top of the stackable ring 101, to form a modular access chamber, or part thereof, and may be referred to as a crowning profile.

[0050]As before, the stackable ring 201 defines a substantially rectangular perimeter. As shown, the stackable ring 201 comprises four side portions 102 and four corner portions 203. Each of the side portions is substantially straight and each of the corner portions is curved, to provide a 90 degree angle at the corners of the stackable ring.

[0051]As shown in Figures 9 and 10 and in more detail in Figures 11 to 13, each side portion 202 comprises an inner wall o...

Claims

1. A stackable ring for a modular access chamber, comprising: a plurality of elongate side portions; and a corresponding plurality of corner portions connected between adjacent side portions, and wherein an angle formed between each side portion and an adjacent corner portion is less than 90 degrees.

2. A stackable ring as claimed in claim wherein the angle formed between each side portion and the adjacent corner portion is between about 45 degrees and about 85 degrees.

3. A stackable ring as claimed in claim 1 or claim 2, wherein each side portion and each corner portion comprises: an inner wall; an outer wall; and an upper plate extending substantially horizontally between an upper end of the inner wall and an upper end of the outer wall.

4. A stackable ring as claimed in claim 3, wherein, for each side portion, the inner wall is shorter in length than the outer wall such that an end of the side portion is angled inwards from the outer wall to the inner wall.

5. A stackable ring as claimed in claim 3 or claim 4, wherein, for each corner portion, an end of the upper plate is angled outwards from the outer wall to the inner wall, wherein the angle is complementary to the angle formed by the adjacent side portion.

6. A stackable ring as claimed in any preceding claim, further comprising a gasket disposed between each side portion and the adjacent corner portion.

7. A stackable ring as claimed in any of claims 3 to 6, further comprising a channel formed in an upper surface of the upper plate of each side portion and each corner portion, to form a continuous channel in an upper surface of the stackable ring.

8. A stackable ring as claimed in claim 7, further comprising an O-ring disposed in the continuous channel.

9. A stackable ring as claimed in any of claims 1 to 5, wherein the upper plate extends horizontally beyond the outer wall.

10. A stackable ring as claimed in any of claims 3 to 9, wherein each side portion further comprises a lower plate extending substantially horizontally between the inner wall and the outer wall along at least a portion of the length of the side portion.

11. A modular access chamber, comprising: a plurality of stackable rings as claimed in any preceding claim, stacked vertically such that a lower end of a first stackable ring of the plurality of stackable rings engages an upper end of a second stackable ring of the plurality of stackable rings.

12. A modular access chamber as claimed in claim 11, wherein each side portion and each corner portion of each stackable ring comprises: an inner wall; an outer wall; and an upper plate extending substantially horizontally between an upper end of the inner wall and an upper end of the outer wall.

13. A modular access chamber as claimed in claim 12, wherein the upper plate of the first stackable ring extends horizontally beyond the outer wall.

14. A modular access chamber as claimed in claim 12 or claim 13, wherein each side portion of at least the first stackable ring further comprises a lower plate extending horizontally between the inner wall and the outer wall along the length of the side portion, wherein the lower plate of the first stackable ring engages the upper plate of the second stackable ring.

15. A modular access chamber as claimed in claim 14, wherein the second stackable ring comprises a channel formed in an upper surface of the upper plate of each side portion and each corner portion thereof, to form a continuous channel in an upper surface of the stackable ring, and an O-ring disposed in the channel, wherein the O-ring provides a seal between the upper plate of the second stackable ring and the lower plate of the first stackable ring.

16. A modular access chamber as claimed in any of claims 11 to 15, further comprising a clip mechanism for securing the first stackable ring to the second stackable ring, wherein the clip mechanism engages each of the first and second stackable rings to cause a vertical compressive force therebetween.

17. A side portion of a stackable ring for a modular access chamber, comprising: an inner wall; an outer wall; and an upper plate extending substantially horizontally between an upper end of the inner wall and an upper end of the outer wall, wherein the inner wall is shorter in length than the outer wall such that an end of the side portion is angled inwards from the outer wall to the inner wall.

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