Secondary closure device for an underground chamber

Abstract

The invention relates to a secondary closure device for an underground chamber, installed below a primary closure device, in order to at least partially block access to the bottom of said underground chamber. It comprises a grid having a transverse axis, supports (6A) adapted to support the grid in a closed position, including a first support (7A) hinged with the transverse axis so that the grid can be pivoted to an open position, and a second support (8A). The first support (7A) and the second support (8A) are positioned on opposite walls of the underground chamber.The first support (7A) comprises two parallel wings (18) perpendicular to the transverse axis. Each wing (18) has a slot (19) with a complex trajectory and a width slightly greater than the diameter of the axis, allowing the axis to slide from an opening in the slot to a terminal portion that enables the grid to rotate around the axis. The terminal portion is straight and allows longitudinal translation of the transverse axis. See Figure 3 for abbreviations.

Description

Title of the invention: Secondary closure device for an underground chamber TECHNICAL FIELD OF THE INVENTION

[0001] The present invention relates to the field of access chambers for underground infrastructure. More particularly, it relates to underground chambers providing access to networks such as telecommunications networks or distribution networks (water, electricity, gas, etc.). It specifically relates to means for closing and securing such chambers. STATE OF THE ART

[0002] Communication networks, as well as water, electricity, and gas distribution systems, are often buried underground. Access chambers are installed at various locations within these underground infrastructures to allow for inspections, connections, and / or maintenance work on these networks.

[0003] These access chambers are closed when not in use to access the corresponding underground infrastructure. This closure is achieved by means of a cover, also called a plug, which forms a main closing device.

[0004] Such a lid can be metallic, for example cast iron or steel, but it can also be made of plastic material, for example composite. The lid protects the contents of the chamber and allows passage over it for people and / or vehicles.

[0005] The cover forming the main closing device of a chamber can have various configurations. It is generally positioned in a frame that is sealed in the ground.

[0006] The cover can be removed from the frame or tilted to allow access to the chamber located under the frame and the network it contains.

[0007] However, when the main locking device is removed or tilted to allow access to the chamber—in other words, when the chamber is open—certain problems can arise. For example, there is a risk of an operator falling while the chamber is open but the operator is not working in the chamber, or during the opening of the chamber. Furthermore, improper handling can cause the cover or a tool to fall into the chamber, particularly during the opening of the chamber, which can damage the underground infrastructure within the chamber.

[0008] To solve these problems, a known solution is to install a secondary closing device below the main device. This second device is generally in the form of a grid. This grid does not offer the same sealing capacity or the same resistance as the main cover, but it nevertheless prevents a person or an object (for example, from the cover) from falling into the chamber.

[0009] In a known manner, this grid can be held in position in two alternative ways.

[0010] According to a first configuration, the grid can be inserted into supports which are fixed to opposite walls of the chamber, towards the top of these walls. This can then be referred to as a grid with pegged or "spun" supports.

[0011] According to a second configuration, the grid is placed on supports welded to the frame of the access chamber.

[0012] In order to access the chamber, and depending on the type of grille, the grille can be removed or opened by pivoting (this is then referred to as a hinged grille). The latter solution is preferable, because a removable grille could itself fall into the chamber.

[0013] Thus, whether the grid supports are fixed to the frame or to the chamber, advantageously, these supports and the grid can be configured to allow on the one hand the grid to pivot and on the other hand the grid to be locked, for example with a padlock.

[0014] The grid is conventionally articulated by aligning holes formed respectively in the supports and in the grid and inserting a so-called transverse axis into them. Alternatively, an axis can be rigidly attached to the grid and inserted into a hinge formed by the support.

[0015] Document FR3062860 thus discloses an example of a fall arrest grid, as described above, with a bolted axle.

[0016] Another example of a grid as described above is known from document FR2792662A1. The grid described in this document is further configured so that it can be opened by pivoting 180° relative to the frame of the chamber it equips.

[0017] Nevertheless, secondary sealing solutions for access chambers to underground infrastructure can still be improved. One particular problem is that installing such grates requires precise positioning of the grate supports, whereas the chambers are often manufactured with significant dimensional tolerances. This is especially true when the supports are fixed, or bolted, to the chamber walls. It is also true when the supports are attached to the frame, since any precision is compromised. The manufacturing load-bearing capacity results in a higher cost. Generally speaking, the cost required to achieve the function of the secondary grid, whether it be the cost of the supports or the cost related to the required low tolerance, can be improved. Description of the invention

[0018] The present invention aims to remedy all or part of the disadvantages of the prior art mentioned above.

[0019] To this end, the invention relates to a secondary closure device for an underground chamber, intended to be installed in said underground chamber under a main closure device, in order to block, when said secondary closure device is in a closed position, at least partially the access to a bottom of said underground chamber, the secondary closure device comprising a grid having a transverse axis of circular section, and supports adapted to support the grid in said underground chamber in said closed position.

[0020] The supports comprise a first hinged support allowing the grid to pivot around the transverse axis, so that the grid can be pivoted into an open position in which access to the underground chamber is unobstructed, and a second support. The first and second supports are positioned near opposite walls, in a so-called longitudinal direction, of the underground chamber.

[0021] The first support comprises two wings parallel to each other and perpendicular to the transverse axis of the grid, each wing comprising a slot of complex trajectory, said slot having a width slightly greater than the diameter of the axis, thus allowing the sliding of the axis in the slot from an entrance to a terminal portion and allowing the rotation of the grid around the axis, said terminal portion being straight and allowing a longitudinal translation of the transverse axis.

[0022] The configuration of the first support, which can be implemented very simply and economically, allows for very easy installation and removal of the grid without tools. It also allows for some freedom in the longitudinal position of the grid. This makes it possible to use the proposed secondary closure without complex adaptation, even when the manufacturing dimensional tolerances of the underground chamber or frame are relatively high (for example, 10 mm, 20 mm, or even more). Furthermore, to adapt the device to larger chambers, or to chambers whose dimensions exceed the maximum tolerance, shims can be very easily added to adjust the position of the supports.

[0023] The slot of each wing of the first support may have, for example, a trajectory substantially in “C” or a trajectory substantially in “S”.

[0024] The second support may include at least one vertical leg, adapted to pass through a notch formed in the grid.

[0025] The notch may have a length greater than the width of the leg, allowing longitudinal movement of the grid.

[0026] At least one vertical leg of the second support may have a hole located above the grid, when the latter is in the closed position, so as to be able to fix on said vertical leg a locking device, for example a padlock.

[0027] The first support or the second support may be formed of two angle brackets, each angle bracket having a fixing flange intended to be fixed, for example pegged, to a wall of the underground chamber.

[0028] The secondary closure device may further include an installation template for determining the position of the holes to be drilled on a wall of the underground chamber to fix the first or second support, the template being made up of a plate, said plate having a first surface intended to be in contact with an upper rim of the chamber, a second surface intended to be in contact with said wall of the underground chamber to which the first or second support is to be fixed, and an edge intended to be in contact with a side wall of the underground chamber which is perpendicular to said wall of the underground chamber to which the first or second support is to be fixed, the second surface of the template having openings whose position corresponds to the position of the holes to be drilled.

[0029] The first support can be formed of a piece comprising a central plate and two wings parallel to each other and perpendicular to the central plate, said central plate comprising a folded end part adapted to be welded to a frame.

[0030] The second support may be formed of a piece comprising a central plate and two vertical legs, said central plate having a folded end part adapted to be welded to a frame.

[0031] The secondary closing device may further comprise a frame forming a seating surface for a primary closing device of an underground chamber, for example for a cover, in which the first support and the second support are welded to opposite edges of the frame.

[0032] The first support and / or the second support can be made solely by folding and cutting a flat sheet. BRIEF DESCRIPTION OF THE FIGURES

[0033] Other advantages, purposes and particular features of the present invention will become apparent from the following non-limiting description of at least one particular embodiment of the devices and methods of the present invention, with reference to the accompanying drawings, in which: Fig. 1 is a schematic view of an underground chamber with a secondary closure conforming to the state of the art; [Fig.2] represents the supports used for the secondary closure of [Fig.1], in accordance with the state of the art; Figure 3 represents, in a schematic three-dimensional view, an example of a support for a secondary closure of an underground chamber, according to one embodiment of the invention. [Fig.4] is another view of one of the supports of [Fig.3]; [Fig.5] is a detail view of one side of a secondary underground chamber closure mounted on the supports of [Fig.3]; [Fig.6] is a detail view of the other side of a secondary underground chamber closure mounted on the supports of [Fig.3]; [Fig.7] is a schematic three-dimensional view of an underground chamber with a secondary closure device including the supports of [Fig.3]; [Fig.8] represents a template allowing the installation of the supports of [Fig.3]; [Fig.9] represents a template similar to that of [Fig. 10], when used in an underground chamber; [Fig. 10] represents an example of support for the secondary closure of an underground chamber, according to an embodiment of the prior art in which the supports are linked to one side of the frame of the underground chamber; [Fig. 11] represents an example of support for the secondary closure of an underground chamber, according to an embodiment of the prior art in which the supports are linked to the other side of the frame of the underground chamber; [Fig. 12] represents an example of a support for the secondary closure of an underground chamber, according to an embodiment of the invention in which the supports are linked to one side of the frame of the underground chamber; [Fig. 13] represents an example of a support for the secondary closure of an underground chamber, according to an embodiment of the invention in which the supports are linked to the other side of the frame of the underground chamber; [Fig. 14] is a schematic three-dimensional view of a frame and a grid forming a secondary closure according to another example of an embodiment of the invention; [Fig. 15] represents a grid adapted to form a secondary closure of an underground chamber as illustrated in [Fig. 14]. DETAILED DESCRIPTION OF THE INVENTION

[0034] The present description is given by way of non-limiting example. [Fig. 1] is a schematic view of an underground chamber with a secondary closure in accordance with the prior art. The underground chamber 1 is in the form of a rectangular shaft formed in the ground. The underground chamber has walls 2, here made of concrete. The upper edge of the underground chamber 1 is reinforced by a frame 3. The frame 3 is generally metallic and forms a bearing surface 4 on which a cover can be placed to seal the underground chamber 1.

[0035] A secondary closure of the chamber is provided, in the form of a grid 5. The grid 5, in the closed position, extends horizontally under the frame, and therefore under the cover (not shown) which forms a primary closure device for the underground chamber 1.

[0036] The purpose of the grid 5 is to secure the underground chamber 1, primarily during the opening of the cover (or other primary closing device), or when said cover is opened or removed. Indeed, when opening the chamber cover, which is generally heavy, there is a risk that the cover or a tool may fall into the underground chamber 1. There is also a risk of falling into the underground chamber for the operator opening the cover.

[0037] The secondary closing device thus prevents the cover, a tool, or a person from falling to the bottom of the underground chamber 1. This avoids a risk of injury to the person concerned, and / or damage to the equipment contained in the underground chamber 1.

[0038] The grid 5, which is not subjected to such significant and repeated stresses (for example, the passage of vehicles) as the primary closure, must nevertheless be securely fixed to the underground chamber 1.

[0039] To this end, supports 6 are, in the example shown here, securely fixed, preferably pegged, to opposite walls 2 of the underground chamber.

[0040] The chamber is arbitrarily oriented by considering that the walls where the supports 6 are fixed are longitudinally opposed, that is to say here along a longitudinal direction L. The longitudinal direction corresponds in the example shown to the largest side of the underground chamber, which is rectangular in this example.

[0041] The transverse direction T is defined as the horizontal direction perpendicular to the longitudinal direction L, and here it is parallel to the short side of the rectangular chamber.

[0042] The supports 6 thus comprise: a first support 7, allowing the extraction or articulation of the grid 5 (to bring it into the open position), and a second support 8.

[0043] Various types of supports 6 are known in the prior art. An example of a known, functionally evolved support is shown in [Fig.2].

[0044] Fig. 2 thus represents the first support 7 and the second support 8.

[0045] The first support 7 is in the form of two solid and rigid brackets. Each bracket has a first portion 9 which has holes 10, each allowing the insertion of an anchor bolt. A second portion 11 of the bracket has a hook 12 which is attached, for example welded, to the first support.

[0046] The hook 12 allows a transverse axis 13 of the grid 5 to be locked in order to allow it to tilt.

[0047] The second support 8 also includes two solid, rigid brackets. A first portion 9 of each bracket has holes 10, each allowing the insertion of an anchor bolt. At least one of the two brackets of the second support 8 has a ring 14 fixed, for example welded, to its second portion 11. When the grid 5 is in the closed position, it rests on the second portion 11 of each of the brackets of the second support 8. The ring 14 then protrudes above an upper surface 15 of the grid. A padlock can be fitted into the ring 14 to lock the grid 5 in the closed position.

[0048] These supports can nevertheless be improved: they are complex parts to manufacture (they require the assembly of the hooks 12 and the ring 14, in particular), they are laminated parts assembled by welding, which are relatively expensive, and they require high precision during assembly. In particular, if the longitudinal spacing between the supports is not correctly maintained and is too large, there is a risk that the grid 5 could be extracted from the first support 7 despite the presence of a padlock in the ring 14. Conversely, if the spacing is too small, mounting the grid 5 may be impossible, or the grid may rest incorrectly on the support 6.

[0049] According to known embodiments, an accuracy of the order of 2 mm is required to ensure the correct positioning and proper functioning of the grid 5. However, such accuracy is rarely achieved with certainty with regard to the spacing between the opposite walls of an underground chamber, which requires adapting the position of the supports during their assembly, for example by means of shims.

[0050] Fig. 3 illustrates 6A supports conforming to a first embodiment of the invention.

[0051] Just as in the known embodiment shown in [Fig.2], the supports 6A comprise a first support 7A and a second support 8A.

[0052] The first support 7A comprises two parts, namely two angle brackets 16. The two angle brackets 16 may be identical. Each angle bracket 16 has a fixing flange 17 intended to be fixed, for example by means of anchors, to a wall of the underground chamber. The fixing flange 17 may thus have holes 10, each allowing the insertion of an anchor bolt. In the example shown here, the holes 10 are oblong, allowing some adjustment of the transverse position of the angle brackets 16. Each angle bracket 16 also has a flange 18, perpendicular to the fixing flange 17.

[0053] Wing 18 has a slot 19.

[0054] As can be seen in [Fig. 4], the slot 19 has a substantially constant width 1. This width 1 is such that it allows the passage, with minimal play, of the axis 13 of the grid 5, which has a diameter D. The slot 19 can have a complex trajectory, for example, essentially a curvilinear one. In the example shown here, the slot 19 has a substantially C-shaped trajectory. The slot 19 has a terminal portion 20, which is closed and straight. This terminal portion is substantially horizontal when the first support 7A is fixed in an underground chamber.

[0055] As shown in [Fig. 5], when the first support 7A is fixed to the wall 2 of the underground chamber 1 using dowels, the two angle brackets 16 are fixed so that their flanges 18 are parallel to each other and aligned. The axis 13 of the grid 5 is inserted into the slot 19 of each of the angle brackets 16 through its opening 21 (the beginning of the upper arm of the "C" formed by the slot). The axis 13 is then advanced through each slot 19 of the angle brackets until the axis 13 is in the terminal portion 20 (formed by the lower arm of the "C"). The axis 13 can then no longer escape from the first support 7A from above. It nevertheless remains free to rotate, and its longitudinal position can also be adjusted to a certain extent. For example, the length of the terminal portion of the slot 19 can be on the order of 20 mm to 30 mm, allowing a corresponding adaptation of the longitudinal position of the axis 13.

[0056] In [Fig. 5], the axis 13 is positioned near the closed end of the portion terminal 20, which corresponds to the position of axis 13 when the grid 5 is tilted towards its open position. In particular, the "C" configuration of slot 19 allows axis 13 to be moved away from the wall 2 of the chamber, which improves the stability of grid 5 in the open position.

[0057] It is also noteworthy that the grid 5, assuming that it is free at its opposite longitudinal end, can be very easily removed from the first support 7A, by making the axis 13 follow the trajectory of the slot 19 to its entrance 21.

[0058] Each of the two angle brackets 16 forming the first support 7A can be obtained by cutting and folding (in a single 90° fold) a metal plate. A steel plate (For example, stainless or galvanized steel) approximately 3 mm thick can be used for this purpose. Given the small dimensions of the 16 mm angle brackets, a scrap piece of metal sheet can usually be used to form each 16 mm angle bracket.

[0059] Regarding the second support 8A of the embodiment of [Fig. 3], it also comprises two parts, namely two angle brackets 16A. The two angle brackets 16A may be identical. Each angle bracket 16A has a fixing flange 17A intended to be fixed, for example by anchoring, to a wall of the underground chamber (opposite the wall where the first support 7A is fixed). The fixing flange 17A of each angle bracket may thus have holes 10, each allowing the insertion of an anchor bolt. In the example shown here, the holes 10 are oblong, allowing some adjustment of the transverse position of the angle brackets 16A.

[0060] Each angle bracket 16A forms a leg 22, which extends perpendicularly to the fixing wing 17A.

[0061] The leg 22 further extends vertically, so that it passes through a notch 23 formed in the grid 5 when the latter is placed against the second support 8A, as shown in [Fig.6].

[0062] The notch 23 preferably has an elongated shape in the longitudinal direction. The length w of the notch 23 is advantageously greater than the width e of the tab 22.

[0063] This offers some freedom in the longitudinal positioning of the angle brackets 16A forming the second support 8A, between the two extreme positions shown in [Fig.6], offering a deflection d.

[0064] At least one of the legs 22 of the second support 8A has a hole 24. When the grid 5 is in the closed position, resting on the second support 8A, the hole 24 is located above the grid 5, more precisely above the upper surface 15 of the grid 5.

[0065] Hole 24 allows a padlock or other suitable locking device to be passed through it, in order to lock the grid 5 in its closed position.

[0066] Figure 7 is a schematic three-dimensional view of an underground chamber 1 including a secondary closing device comprising the supports of [Fig.3].

[0067] Compared to the underground chamber of [Fig. 1], the underground chamber 1 of [Fig. 7] differs in the secondary closure device used. In particular, the first support 7A, comprising the two angle brackets 16 having a slot 19 into which the axis 13 of the grid 5 is inserted, is fixed to a first wall of a longitudinal end of the underground chamber 1.

[0068] The second support 8A comprising two angle brackets 16A comprising tabs 22 allowing the locking of the grid 5 is fixed on the wall of the underground chamber 1 opposite longitudinally.

[0069] Figure 8 shows a template allowing the correct positioning of the angle brackets forming the first support 7A and the second support 8A respectively in an underground chamber. This template 25 is formed from a plate such that it has a first surface 26 and a second perpendicular surface 27.

[0070] As shown in [Fig.9], the first surface 26 of the template 25 is intended to be brought into contact with an upper edge of the underground chamber 1, in this case on the bearing surface 4 of the frame 3 of the chamber.

[0071] The first surface 27 may include a handle 28 which is foldable in order to facilitate the handling of the template 25.

[0072] The second surface 27 is pressed against the wall 2 of the underground chamber 1 on which one of the first support 7A or second support 8A is to be fixed. An edge 29 of the template 25 is pressed against the wall of the chamber which is perpendicular to the wall of the chamber to which the first support 7A or the second support 8A is to be fixed.

[0073] The second surface 27 of the template has openings 30 whose position corresponds to the position of the holes to be drilled. In particular, as in the example shown in Figures 8 and 9, openings 30 of various shapes may be present in the second surface 27. The openings have the correct spacing between them in the transverse direction for mounting a suitable grid 5, and two openings 30 of the same shape have the correct vertical spacing, corresponding to the vertical spacing of the holes 10 in the supports.

[0074] The selection of the openings used to make the drillings in the wall 2 of the underground chamber 1 allows the installation depth of the grid 5 to be chosen in relation to the bearing surface 4 of the frame 3.

[0075] Figure 10 shows an example of a support for the secondary closure of an underground chamber, in this case the first support 7B, according to a prior art embodiment in which the supports are connected to one side of the underground chamber frame. Figure 10 illustrates that the support for a secondary closure device can be directly connected to the frame 3. This simplifies the installation of the secondary closure, but, obviously, this is only feasible for underground chambers that are designed from the outset to be equipped with such a secondary closure. In the known embodiment of Figure 10, the first support 7B has two tabs 31 welded to the frame 3. Each tab 31 has a perforated plate 32 for mounting a pin 33 (for example, in the form of a bolt) for hinged to a grid 5.

[0076] Regarding the second corresponding support 8B, shown in [Fig. 1 1], it also includes two tabs 31A each forming a support to receive the grid 5. At least one of the two tabs 31 can be equipped with a ring 14A for locking the grid 5, for example with a padlock.

[0077] The support of figures 10 and 11 is complex, requires many welded parts, and does not allow tool-free disassembly of the grid in relation to frame 3.

[0078] On the same principle as detailed above with reference to figures 3 to 7, it is proposed within the framework of the present invention to have supports 6C, comprising a first support 7C represented in [Fig.12] and a second support 8C represented in [Fig.13].

[0079] The first support 7C is formed of a piece comprising a central plate 34 and two wings 18A parallel to each other and perpendicular to the central plate 34.

[0080] The central plate 34 further comprises an end part 35 which is welded to the frame 3.

[0081] Each wing 18A has a slot 19A.

[0082] The slot 19A, just like the slot in the embodiment of figures 3 to 7, has a substantially constant width such that it allows the passage, with little play, of the axis 13 of the grid 5.

[0083] The slot 19A has, in the example shown here, a substantially "S" shaped trajectory. The slot 19A has a terminal portion 20A, which is closed, straight and substantially horizontal when the frame 3 is in place on an underground chamber.

[0084] The grid's axis 13 can easily be inserted into slot 19A and positioned in portion 20A, where it can no longer escape from the first support 7C from above. The grid 5 can nevertheless be tilted, around its axis 13, to an open position. The grid can be removed from the first support 7C without tools.

[0085] The second support 8C, shown in [Fig. 13], has a general structure similar to that of the first support 7C. Thus, the second support 8C comprises a central plate 34A having an end portion 35A which is welded to the frame 3. The second support further comprises two tabs 22A, which extend perpendicularly to the central plate 34A. The tabs 22A also extend vertically, so that they pass through the notches 23 formed in the grid 5 when the latter is supported by the second support 8C.

[0086] Just as in the embodiment shown in figures 3 to 7, the legs 22A advantageously have a width less than the length of the notches 23.

[0087] At least one of the legs 22A has a hole 24 located above the grid 5, more precisely above the upper surface 15 of the grid 5 when it is supported on the second support 8C.

[0088] Hole 24 allows a padlock or other suitable locking device to be passed through it, in order to lock the grid 5 in its closed position.

[0089] Compared to the known embodiment shown in Figures 10 and 11, the The first support (7C) and the second support (8C) can be made by folding and cutting a sheet of metal, without any added parts. They also allow for very easy and tool-free installation and removal of the grid.

[0090] Furthermore, the frames incorporating the support for the secondary closing grille according to Figures 12 and 13 are stackable for storage and transport, without requiring any interposed piece (wooden block or other) between the frames. This is not the case with frames known in the prior art, such as those in Figures 11 and 12, because elements of the first support 7B and / or the second support 8B (in particular the perforated plates 32 or the rings 14A) would interfere.

[0091] All the embodiments described above assume that the support is installed on the opposite walls furthest from each other in an underground chamber. However, whether the support is brought into the chamber or directly welded to the frame, it can be positioned on the opposite walls of the chamber that are closest to each other. This is illustrated in [Fig. 14], which shows a frame 3 with a secondary closure support. The support in [Fig. 14] can correspond to the one shown in Figures 12 and 13. Thus, by convention, the longitudinal direction L in [Fig. 14] is considered to correspond to the direction of the shorter side of the frame 3. The transverse direction T is that of the longer side of the frame 3.

[0092] Figure 15 illustrates a grid 5 that can thus be used to form a secondary closing device according to one embodiment of the invention. The grid 5 has the particularity of comprising, on either side (along the longitudinal direction L), structures which each form a portion of axis 13 and a notch 23. The grid is thus symmetrical and can be mounted in either direction. It should be noted that the axis 13 is here formed of several coaxial portions.

[0093] It is thus proposed within the framework of the present invention, a secondary closing device for an underground chamber allowing easy installation and removal of a grid, and tolerating significant dispersions in the dimensions of the underground chamber or frame, for example up to 20 mm to 30 mm.

[0094] The support for the secondary closing grid can also be obtained by simple bending and cutting of metal plates, and is therefore simple and inexpensive to obtain.

Claims

Demands

1. A secondary closure device for an underground chamber, intended to be installed in said underground chamber (1) beneath a primary closure device, in order to seal, when said secondary closure device is in a closed position, at least partially, access to a bottom of said underground chamber (1), the secondary closure device comprising: - a grid (5) comprising a transverse axis (13) of circular section, - supports (6A, 6C) adapted to support the grid (5) in said underground chamber (1) in said closed position, the supports (6A, 6C) comprising: - a first support (7 A, 7C) forming a hinge and allowing a pivoting of the grid (5) around the transverse axis (13), so that the grid (5) can be pivoted into an open position in which access to the underground chamber (1) is freed, - a second support (8A, 8C), The first support (7A, 7C) and the second support (8A, 8C) are positioned near opposite walls, along a longitudinal direction (L), of the underground chamber (1). The first support (7A, 7C) comprises two wings (18, 18A) parallel to each other and perpendicular to the transverse axis (13) of the grid (5). Each wing (18, 18A) comprises a slot (19, 19A) with a substantially C-shaped or S-shaped trajectory. The slot (19, 19A) has a width (1) greater than the diameter (D) of the axis (13), thus allowing the axis (13) to slide within the slot from an inlet (21) to a terminal portion (20, 20A) and enabling the grid to rotate around the axis (13). The terminal portion (20, 20A) is straight and allows translation. longitudinal of the transverse axis (13).

2. A secondary closure device for an underground chamber according to claim 1, wherein the second support (8A, 8C) has at least one vertical tab (22, 22A) adapted to pass through a notch (23) formed in the grid (15).

3. Secondary closing device for an underground chamber according to claim 2, wherein the notch (23) has a length (w) greater than a width (e) of the tab (22, 22A), allowing longitudinal movement of the grid (5).

4. Secondary closing device for an underground chamber according to claim 2 or claim 3, wherein at least one vertical tab (22, 22A) of the second support (8A, 8C) has a hole (24) located above the grid (5), when the latter is in the closed position, so as to be able to fix on said vertical tab (22, 22A) a locking device, for example a padlock.

5. Secondary closure device for an underground chamber according to any one of the preceding claims, wherein the first support (7A, 7C) or the second support (8A, 8C) is formed of two angle brackets (16, 16A), each angle bracket (16, 16A) having a fixing wing (17, 17A) intended to be fixed, for example by doweling, to a wall (2) of the underground chamber (1).

6. Secondary closure device according to claim 5 further comprising an installation template (25) for determining the position of the holes to be made on a wall (2) of the underground chamber (1) for fixing the first support (7A) or the second support (8A), the template being made of a plate, said plate having a first surface (26) intended to be made in contact with an upper edge of the chamber, a second surface (27) intended to be made in contact with said wall (2) of the underground chamber (1) to which the first support (7A) or the second support (8A) is to be fixed, and an edge (29) intended to be made in contact with a side wall of the underground chamber which is perpendicular to said wall (2) of the underground chamber (1) to which the first support (7A) or the second support (8A) is to be fixed,the second surface (27) of the template (25) having openings (30) whose position corresponds to the position of the holes to be drilled.

7. Secondary closure device for an underground chamber according to any one of claims 1 to 4, wherein the first support (7C) is formed of a piece comprising a central plate (34) and two parallel wings (18A) to each other and perpendicular to the central plate (34), said central plate (34) comprising a folded end portion (35) adapted to be welded to a frame (3).

8. Secondary closure device for an underground chamber according to claim 7, wherein the second support (8C) is formed of a piece comprising a central plate (34A) and two vertical tabs (22A), said central plate (34A) comprising a folded end portion (35A) adapted to be welded to a frame (3).

9. A secondary closure device for an underground chamber according to claim 8, further comprising a frame (3) forming a seating surface (4) for a primary closure device for an underground chamber (1), for example for a cover, in which the first support (7C) and the second support (8C) are welded to opposite edges of the frame (3).

10. Secondary closure device for an underground chamber (1) according to any one of the preceding claims, wherein the first support (7A, 7C) and / or the second support (8A, 8C) is made solely by bending and cutting a flat sheet.

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