GB2543597A

GB2543597A - Covers for voids

Info

Publication number: GB2543597A
Application number: GB1608635.7A
Authority: GB
Inventors: Merfyn Phillips Andrew; Hywel Mason Thomas
Original assignee: CARREG CONSTRUCTION Ltd
Current assignee: CARREG CONSTRUCTION Ltd
Priority date: 2015-05-27
Filing date: 2016-05-17
Publication date: 2017-04-26
Anticipated expiration: 2036-05-17
Also published as: GB201608635D0; GB2543597B; GB201509054D0

Abstract

A cover assembly is for a void having a cover slab 4 that defines an opening 6 into the void. The cover assembly includes a cover plate 14 and a frame 8. The frame is for locating the cover plate so as to close the opening and is configured to be attached to a surface of the cover slab not facing the void. The frame may be dimensioned and configured to provide a guide to the setting out of brickwork to be constructed on the surface of the cover slab that is vertically uppermost. The cover plate or frame may comprise at least one locking means adapted to reversibly lock the cover plate within the frame. A manhole comprises a void having a cover slab which defines an opening in the void, said cover assembly, brickwork on the cover slab, a manhole ring on the top of the brickwork, and a manhole cover. The manhole may comprise a second frame having one or more elements which define a space within which the cover plate may loosely fit, the second frame being attached to the brickwork.

Description

COVERS FOR VOIDS

This invention relates to covers for voids and, in particular, methods of construction and use of the covers.

Voids in the ground such as manholes and access pits are commonly used so as to gain access to services that are located underground. Such services include water pipes, sewerage systems, underground cables and the like. Manholes are generally comprised of a manhole chamber located below ground level with a top comprised of a cover slab. The cover slab defines an access aperture or void opening which allows human access into the chamber. On top of the cover slab and around the access aperture one or more courses of bricks (or similar) are laid creating a brick shaft. On top of the brick shaft is set a cover frame suitable for the insertion and retention of a manhole cover. The uppermost surface of the cover frame is generally required to be at the same level as the local surface in which the man hole is located. This requirement will determine the number of courses of bricks to be used.

Access pits are similar in nature to manholes but may simply be comprised of a void defined by one or more brick walls on top of which a cover frame suitable for the insertion and retention of a cover is set. Again the uppermost surface of the cover frame is generally required to be at the same level as the local surface in which the access pit is located.

The covers for manholes and access pits are generally heavy and intended to withstand whatever loading from traffic (whether pedestrian or vehicular) is expected in the area in which the manhole or access pit is located. Furthermore, the covers are required to be sufficiently heavy that they will not easily be displaced from the cover frame by accident. Typically the covers are made of cast metal and held in place by gravity. The covers are not locked or keyed into the cover frames because the exposure of the covers to the elements and dirt would be expected to block any locking means and / or because the weight of the covers would render fine manipulation of the covers in order to insert them or extract them from the cover frame difficult.

According to the present invention there is provided a cover assembly for a void having a cover slab which defines an opening in the void comprising a cover plate suitable for closing the opening in the void and a means for locating the cover plate so as to close the opening of the void characterised in that the means for locating the cover plate is a frame attached to a surface of the cover slab not facing the void.

The use of a cover assembly for closing the opening in the void is known per se, see for example GB2410283A. As is discussed in GB2410283A the advantages of having a cover assembly for the void opening during the construction of a manhole are that it increases the safety of the worker(s) constructing the brick shaft on top of the cover slab because there is no longer an opening through which they could fall, and the cover prevents construction materials such as excess mortar falling into the manhole chamber. Furthermore, the presence of the cover plate means that if the manhole is left unattended there is a minimal safety risk to others. A significant disadvantage of the cover assembly disclosed in GB2410283A is it's complexity and the number of parts of which it is constructed. In particular, once a worker starts to fit the apparatus of GB2410283A they have to hold the two brackets mentioned therein in place whilst the trench struts mentioned therein are put in position and extended so as to hold the brackets in place. There is considerable risk that during this process one or more of these parts will be dropped down the manhole. Furthermore, when these parts have been removed and finished with, there is a risk that at least one of these parts will get lost before the apparatus is next required for use.

The apparatus of the present invention has significant advantages over the apparatus disclosed in GB2410283A because once the frame has been attached to the surface of the cover slab all that is required is that the cover plate is located within the frame and the void opening is closed. The frame may be attached to the cover slab by suitable means such as adhesive, nails, bolts or other similar attachment means. A further advantage of the apparatus of the present invention relative to the apparatus disclosed in GB 2410283A is that because of the simplicity of the apparatus, essentially a frame and a cover plate, the cost of the apparatus may be low and it will be economically possible to leave the apparatus in place once the manhole has been completed. This is particularly advantageous because it means that if, for some reason such as theft or routine maintenance, the manhole cover is removed at a later date then the hole in the ground created by removal of that manhole cover is relatively shallow because it will extend down only to the cover plate. Furthermore, because the cover plate does not have to bear the same expected loading as the manhole cover, for example the cover plate may, once the manhole is completed, be expected to support only one or two men, the cover plate can be made from lightweight materials. In a particularly preferred embodiment the cover plate can be made of non-metallic lightweight materials so rendering it less likely to be stolen. A further advantage of the ability to leave the apparatus of the present invention in the manhole without economic detriment is that, because the cover plate is not exposed to the elements and to the weather and dirt that the manhole cover is exposed to, it is possible to incorporate into the cover plate one or means to lock the cover plate to the frame. Locking the cover plate to the frame renders the manhole chamber more secure than currently known manholes. This security is advantageous for two reasons. Firstly, it protects the contents of the manhole chamber and secondly, because it means that unwanted items cannot be put into the manhole chamber. In areas of high security, where there is a risk of terrorism and the planting of bombs, the ability to prevent access to manhole chambers is particularly advantageous.

It is particularly preferred that the frame is attached to the uppermost surface of the cover plate. This is preferred because it means that the frame does not overlie the void opening at all, so preventing the frame impeding passage through the void opening should someone wish to go into the manhole chamber. Furthermore, because the frame is on the uppermost surface, all it is required to do is to prevent lateral movement of the cover plate. This means that the frame may be relatively lightweight and thus inexpensive.

The frame of the present invention may preferably be such that it is continuous and surrounds the edge of the cover plate when the cover plate is loosely located within the frame. In alternative embodiments, the frame may be comprised of two or more elements which, in combination, are located so that the cover plate may be loosely fitted between those elements and retained in position by those elements. For example, if the cover plate is rectangular, then the frame may be comprised of four substantially "L" shaped elements which are so located on the cover slab that the corners of the cover plate each loosely fit into the corner created by one of the "L" elements of the frame.

The brick shaft that is formed on top of the cover slab and extends between the cover slab and cover frame is generally required to be of certain dimensions. These dimensions are standardised and relate to the size of the manhole cover itself. In a particularly preferred embodiment of the present invention the frame of the cover assembly is so dimensioned and configured that a part of the frame will act as a guide to the dimensions that that brickwork has to have. In a particularly preferred embodiment the frame includes an edge or face against which the bricks or brocks may be abutted. For example, the frame may be comprised of a section which is an inverted " T shape, in which case the face of the upright portion of that section that is facing the rest of the frame will be in loose fit with the cover plate and the face of the upright facing away from the rest of the frame may act as a guide to where the face of the brickwork should be. This dimensioning of the frame is particularly advantageous because it will allow very accurate setting out of the brickwork by unskilled workers because all they need to do is follow the edge of the frame. Whilst the workers are doing the brickwork the cover plate is in place and may be stood upon without danger to the worker.

In a particularly preferred embodiment of the present invention the frame is so configured that a mounting portion of the frame will be between the cover slab and the brickwork once the brickwork is in place. This will ensure that the frame is securely fixed in place and have the result that removing the frame will be very difficult without wholly destroying at least part of the brickwork. It will be appreciated that the larger the portion of the frame between the cover slab and the brickwork the greater the difficulty of removing the frame.

It is particularly preferred that the cover plate and/or frame is further comprised of at least one locking means adapted to reversibly lock the cover plate within the frame. This is particularly advantageous because it means that the cover plate, once locked in to the frame, cannot be removed by an unauthorised person. This particularly increases the security and safety associated with the apparatus of the present invention because it means that during the period in which the manhole is being constructed once the cover plate has been locked in position the manhole under construction can be left unattended without the danger of parties accidently or intentionally removing the cover plate and falling through the void opening. During the construction process the cover plate and any locking means can be protected from falling debris, and in particular, from excess mortar or sand and mud, by placing a thin plastic sheet over the cover plate. This protection is entirely sufficient because all that is required is that dirt and building materials do not fall onto the cover plate.

After the construction of the manhole is complete, the ability to lock the cover plate to the frame means that access to the manhole chamber can be restricted to those who have keys to unlock the locking means so increasing the security of the manhole chamber. The locking means may be of a complexity of security level appropriate to the perceived security risk of unauthorised individuals accessing a manhole chamber. Because of the protected position of the cover plate it will be appreciated that the locking means can be complex and they are unlikely to be affected by the ingress of dirt, mud or the like. Furthermore, because the cover plate will not have pedestrian or vehicular traffic passing across it the locking means or a portion of the locking means can be upstanding from the surface of the cover plate without risk of damage.

The frame and/or cover plate may further be provided with means for attachment of tamper evident seals so that, should it be so desired, tamper evident seals can be applied once the cover plate is in position and, thereafter, a quick visual inspection will allow the inspector to confirm that no unauthorised access has been made to the manhole chamber.

It has been found that although the cover plate can be a single item, it is advantageous to form the cover plate from at least two sub-plates. In the case of a rectangular cover plate, those sub-plates are preferably triangular. The benefit of forming the cover plate from at least two sub-plates is that it renders insertion and removal of the cover plate from the frame easier and less likely to be prone to jamming. Where the cover plate is comprised of at least two sub-plates, it is preferred that at least one sub-plate further comprises one or more locking means adapted to lock the or each sub-plate to at least one other sub-plate and/or the frame.

The present invention further includes a manhole comprising a void having a cover slab which defines an opening in the void, a cover assembly as herein described, a brick shaft on the cover slab, a cover frame on the top of the brickwork and a manhole cover. A particularly preferred manhole according to the present invention includes a second frame attached to the brick shaft above the first frame which is located on the cover slab. Most preferably, the second frame is closer to the cover frame than it is to the cover slab. In a particularly preferred embodiment, the second frame is one or no courses of bricks below the cover frame for the manhole. This arrangement is particularly advantageous because once the manhole is built a cover plate can be placed within the second frame minimising the amount of free space between the cover plate and the manhole cover. If the cover plate is locked to the second frame then there is very little space within which anything can be hidden between the cover plate and the manhole cover. In a particularly preferred embodiment of the present invention the cover plate which is to be attached to the second frame can be configured so as to follow the contours of the underside of the manhole cover still further reducing the space between the manhole cover and the cover plate.

Alternatively, appropriately configured space filling blocks can be attached to the cover plate prior to the cover plate's attachment to the second frame. The present invention further comprises the method of construction of a manhole comprising the steps of constructing a void having a cover slab which defines an opening in the void, attaching a cover assembly as discussed above to the cover slab, constructing a brick shaft on the top of the cover slab, setting a cover frame on the top of the brick shaft, and placing a manhole cover in the cover frame.

The attachment of the frame of the cover assembly to the cover slab may be via an appropriate adhesive, nails, bolts or other fixing means.

Preferably at least a portion of the frame is located between the cover slab and the brick work.

The construction of the manhole according to the present invention may further include attachment of a second frame to the brickwork of the brick shaft closer to the cover frame than the first frame which is attached to the cover slab.

The benefits of the present invention may also be gained in situations where there is a preexisting man hole or access pit. In such instances, assuming that the access pit has been made to an appropriate size and/or the brick shaft of the manhole is the proper size then configuring the frame of the present invention so as to have a mounting plate substantially perpendicular to the plane of the cover plate will allow the frame to be fitted to the inside face of the brick shaft or access pit. Most preferably, the portion of the frame adapted to be fitted to the brick extends in a direction that, in use, will be away from the manhole cover and away from the portion of the frame which holds the cover plate in position.

The present invention will be further described and explained with reference to the accompanying drawings in which

Figure 1 shows a cross section of a manhole according to one embodiment of the present invention;

Figure 2 shows an enlarged portion of figure 1;

Figure 3 shows a cover assembly according to the present invention;

Figure 4 shows a cross section of a second embodiment of the frame of the cover assembly of the present invention; and

Figure 5 shows a cross section of part of a second embodiment of a manhole 5 according to the present invention.

With reference to Figures 1 and 2, a manhole is comprised of a void or manhole chamber (2) the top of which is closed by a cover slab (4). The cover slab (4) defines a void opening (6) which is of sufficient size to allow human access to the inside of the void (2).

Attached to the upper surface of the cover slab (4) is a frame (8). The frame (8) is attached to the cover slab (4) by a suitable adhesive (not shown). The frame (8) has, as may be better seen in Figure 3, an "L" shaped cross section, with the longer leg (10) of the " L being positioned to be in contact with the cover slab (4) and adhesive (not shown) and the shorter leg (1 2) which is approximately perpendicular to the longer leg (10). In other embodiments of the present invention, the frame (8) may have different cross sections such as the " T section illustrated in Figure 4.

The void opening (6) of the cover slab (4) is reversibly closed by a cover plate (14). The cover plate (14) is held in position over the void opening (6) by the frame (8) and gravity. The cover plate (14) is constructed of a lightweight material such as thin sheet steel, or a composite material. The precise material used will depend on the required maximum loading that the cover plate (14) has to be capable of bearing and, possibly, any relevant environmental factors.

The face of the shorter leg (12) of the frame (8) that faces away from the cover plate (14) when it is closing the void opening (6) is dimensioned so as to provide a setting out guide for the construction of a brick shaft (16) which is constructed on the upper surface of the cover slab (4). On the upper end of the brick shaft (16) is set a cover frame (18) which is adapted to receive a manhole cover (20). The height of the brick shaft (16), that is how many courses of bricks are used and how much mortar is placed between the bricks, is determined by the need to ensure that the uppermost face of the cover frame (18) is at the same level as the local surface level (22). Other suitable materials, such as concrete blocks can be used in the place of bricks if appropriate.

The frame (8) is configured so that when the brick shaft (16) is constructed using the shorter leg (12) as a setting out guide for the brick shaft (16), the long leg (10) is between the brick shaft (16) and the cover slab (4). This ensures that the frame (8) is held securely in position and that it cannot be removed without substantial effort.

The long leg (10) is illustrated as a continuous sheet of material, in other embodiments of the present invention. The long leg (10) may define one or more apertures. This will result in a saving in materials for the construction of the frame (8) and allow the mortar below the brick shaft (16) to better key onto the cover slab (4).

With reference to Figure 3, the cover plate (14) is substantially rectangular and comprised of two triangular sub-plates (24, 26). Each of the sub-plates (24, 26) is provided with a lifting hole (28) which allows a user to insert a finger or other lifting means through the lifting hole (28) when they want to lift the or one of the sub-plates (24, 26) out of the frame (8). The sub-plates (24, 26) are further provided with at least one lock means (30) adapted to allow a user to reversibly engage a locking mechanism (not shown) which is part of the lock means (30) with an aperture (32) in the shorter leg (12) of the frame (8).

The sub-plate (26) is further provided with a second lock means (34) which is adapted to reversibly engage a locking mechanism (not shown) which is part of the lock means (34) with the sub-plate (24).

The nature of the lock means (30) and (34) may be determined by the level of security that needs to be associated with the locking of the cover frame (18) into the frame (8). In other embodiments, more than one lock means (30) can be associated with each of sub-plates (24, 26) and an appropriate number of apertures (32) provided in the frame (8).

With reference to Figure 5, the manhole is as that shown in Figures 1 and 2 with the addition of a second frame (8) which has a cross section as illustrated in Figure 4. The second frame (8) is fixed in the brick shaft (16) with the long leg (10) of the frame (8) being located between adjacent courses of bricks and the leg (36) of the frame (8) extending into the space defined by the brick shaft (16). A cover plate (14) can be reversibly attached to the second frame (8) to minimise the volume of the space accessible if the manhole cover (20) is removed from the cover frame (18).

Claims

CLAIMS 1 A cover assembly for a void having a cover slab which defines an opening in the void comprising a cover plate suitable for closing the opening in the void and a means for locating the cover plate so as to close the opening in the void characterised in that the means for locating the cover plate is a frame attached to a surface of the cover slab not facing the void. 2 A cover assembly according to claim 1 in which the frame is attached to the surface of the cover slab that is vertically uppermost. 3 A cover assembly according to claim 1 or 2 in which the frame comprises one or more elements which define a space within which the cover plate may loosely fit. 4 A cover assembly according to any of claims 1 to 3 in which the frame is continuous and surrounds the edge of the cover plate when it is located so as to close the opening in the void. 5 A cover assembly according to any of claims 1 to 4 in which the frame is 20 dimensioned and configured so as to provide a guide to the setting out of brickwork to be constructed on the surface of the cover slab that is vertically uppermost. 6 A cover assembly according to claim 5 in which the frame is comprised of a cover plate abutment portion and a mounting portion, and the mounting portion is configured so that a portion of the frame will be between the cover slab and the brickwork when the brickwork is constructed. 7 A cover assembly according to any of claims 1 to 6 in which the cover plate or frame is further comprised of at least one locking means adapted to reversibly lock the cover plate within the frame. 8 A cover assembly according to any of claims 1 to 7 in which the cover plate is comprised of two or more sub-plates. 9 A cover assembly according to claim 8 in which at least one sub-plate further comprises means for reversibly locking the sub-plates to each other. 10 A cover assembly according to claim 8 or 9 in which the cover plate is rectangular and the sub-plates triangular. 11 A cover assembly according to any of claims 7 to 10 further comprising attachment means for at least one tamper evident seal. 12 A manhole comprising a void having a cover slab which defines an opening in the void, a cover assembly according to any of claims 1 to 11, brickwork on the cover slab; a manhole ring on the top of the brickwork, and a manhole cover. 13 A manhole according to claim 12 further comprising a second frame according to any of claims 3 to 6 in which the second frame is attached to the brickwork. 14 A manhole according to claim 13 in which the first and second frames are dimensionally the same and a cover plate may be loosely fitted in either frame. 15 A method of construction of a manhole comprising the steps of: a) constructing a void having a cover slab which defines an opening in the void; b) attaching a cover assembly according to any of claims 1 to 11 to the cover slab; c) constructing the required brickwork on the cover slab; and d) setting a cover frame on the top of the brickwork. 16 A method of construction of a manhole according to claim 15 which further comprises the step of attaching a second frame according to any of claims 3 to 6 to the brickwork. 17 A method of construction of a manhole according to claim 16 in which the second frame is attached to the brickwork closer to the cover frame than to the cover plate. 18 A cover plate suitable for use in a cover assembly according to any of claims 1 to 11. 19 A frame for locating a cover plate suitable for use in a cover assembly according to any of claims 1 to 11.