Secondary closing device for an underground chamber

Abstract

The invention relates to a secondary closure device for an underground chamber, installed under a main closure device, in order to at least partially close access to a bottom of said underground chamber. It comprises a grid having a transverse axis, supports (6A) adapted to support the grid in a closed position comprising a first support (7A) forming a hinge 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 wings (18) parallel to each other and perpendicular to the transverse axis, each wing (18) comprising a slot (19) of complex trajectory and having a width slightly greater than the diameter of the axis, allowing the sliding of the axis from an entrance of the slot to a terminal portion allowing the rotation of the grid around the axis. The terminal portion is straight and allows a longitudinal translation of the transverse axis.

Description

TECHNICAL FIELD OF THE INVENTION

[0001] The present invention relates to the field of access manholes for underground infrastructure. It relates more particularly to underground chambers providing access to networks such as telecommunications networks or distribution networks (water, electricity, gas, etc.). It relates in particular to the 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 located at various points in 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 cover, which forms a main closing device.

[0004] Such a cover can be metallic, for example cast iron or steel, but it can also be made of plastic material, for example composite. The cover protects the contents of the chamber, and allows movement 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 which is sealed in the ground.

[0006] The cover can be removed from the frame or tilted to allow access to the chamber below the frame and the network within.

[0007] However, when the main closure device is removed or tilted so as to allow access to the chamber, i.e. the chamber is open, certain problems may 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 when the chamber is being opened. Furthermore, incorrect handling may result in the lid or a tool falling into the chamber, particularly when the chamber is being opened, which may cause damage to the underground infrastructure present in the chamber.

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

[0009] As is known, this grid can be held in position in two alternative ways.

[0010] In a first configuration, the grid can be inserted into supports which are fixed on opposite walls of the chamber, towards the top of these walls. We can then speak of a grid with pegged or "spiked" supports.

[0011] In 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 grid in question, the grid can be removed or opened by pivoting (this is called a hinged grid). The latter solution is preferable, because a grid that can be removed could itself fall into the chamber.

[0013] Thus, whether the grid supports are attached to the frame or to the chamber, advantageously, these supports and the grid can be configured to allow on the one hand the pivoting of the grid and on the other hand to lock the grid, for example using a padlock.

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

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

[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] However, there is still room for improvement in secondary sealing solutions for access chambers in underground infrastructure. One particular issue is that installing such grids requires high precision in the positioning of the grid supports, while the chambers are often manufactured with significant dimensional tolerances. This is particularly the case when the supports are fixed, pegged, to the chamber walls. This is also the case when the supports are connected to the frame, since any significant manufacturing precision translates into higher costs. Generally speaking, the cost required to achieve the function of the secondary grid, whether it is the cost of the supports or the cost related to the required low tolerance, can be improved. STATEMENT OF THE INVENTION

[0018] The present invention aims to remedy all or part of the drawbacks of the state of the art cited above.

[0019] To this end, the invention relates to a secondary closing device for an underground chamber, intended to be installed in said underground chamber under a main closing device, in order to close, when said secondary closing device is in a closed position, at least in part the access to a bottom of said underground chamber, the secondary closing device comprising a grid comprising 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 support forming a hinge and allowing the grid to pivot about the transverse axis, so that the grid can be pivoted to an open position in which access to the underground chamber is free and a second support. The first support and the second support 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 inlet to an end portion and allowing the rotation of the grid around the axis, said end portion being straight and allowing a longitudinal translation of the transverse axis. The slot of each wing of the first support has a substantially "C" shaped trajectory or a substantially "S" shaped trajectory.

[0022] The configuration of the first support, which can be carried out in a very simple and economical way, allows the grid to be installed and removed very easily without tools. It also allows a certain freedom in the longitudinal position of the grid. This allows the proposed secondary closure to be used without complex adaptation even when the dimensional manufacturing tolerances of the underground chamber or the frame are relatively high (e.g. 10 mm, 20 mm, or even more). In addition, to adapt the device to larger chambers, or to chambers whose dimensions exceed the maximum of the planned tolerance, shims can be very easily added to adjust the position of the supports.

[0023] The second support may comprise at least one vertical leg, adapted to pass through a notch formed in the grid.

[0024] The notch can have a length greater than the width of the leg, allowing longitudinal movement of the grid.

[0025] The at least one vertical leg of the second support may comprise a hole located above the grid, when the latter is in the closed position, so as to be able to fix a locking device, for example a padlock, to said vertical leg.

[0026] The first support or the second support may be formed from two angles, each angle comprising a fixing wing intended to be fixed, for example pegged, to a wall of the underground chamber.

[0027] The secondary closure device may further comprise an installation template for determining the position of the holes to be made on a wall of the underground chamber to fix the first support or the second support thereto, the template consisting of a plate, said plate comprising a first surface intended to be placed in contact with an upper edge of the chamber, a second surface intended to be placed in contact with said wall of the underground chamber to which the first support or the second support must be fixed, and an edge intended to be placed in contact with a side wall of the underground chamber which is perpendicular to said wall of the underground chamber to which the first support or the second support must be fixed, the second surface of the template comprising openings whose position corresponds to the position of the holes to be made.

[0028] The first support may be formed from a part 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.

[0029] The second support may be formed from a part comprising a central plate and two vertical legs, said central plate comprising a folded end portion adapted to be welded to a frame.

[0030] The secondary closure device may further comprise a frame forming a seating surface for a primary closure device of an underground chamber, for example for a cover, wherein the first support and the second support are welded to opposite edges of the frame.

[0031] The first support and / or the second support can be made solely by folding and cutting a flat sheet. BRIEF DESCRIPTION OF THE FIGURES

[0032] Other advantages, aims and particular characteristics of the present invention will emerge from the following non-limiting description of at least one particular embodiment of the devices and methods which are the subject of the present invention, with reference to the appended drawings, in which: there Figure 1 is a schematic view of an underground chamber comprising a secondary closure in accordance with the state of the art; Figure 2 represents the supports used for the secondary closure of the Figure 1 , in accordance with the state of the art; the Figure 3 represents, according to a three-dimensional schematic view, an example of support for a secondary closure of an underground chamber, according to an embodiment of the invention, the Figure 4 is another view of one of the supports of the Figure 3 ; there Figure 5 is a detail view of one side of a secondary underground chamber closure mounted on the supports of the Figure 3; there Figure 6 is a detail view of the other side of a secondary underground chamber closure mounted on the supports of the Figure 3 ; there Figure 7 is a three-dimensional schematic view of an underground chamber having a secondary closure device comprising the supports of the Figure 3 ; there figure 8 represents a template allowing the installation of the supports of the Figure 3 ; there figure 9 represents a template similar to that of the Figure 10 , when used in an underground chamber; the Figure 10 represents an example of a 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; Figure 11represents an example of a 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; Figure 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; the Figure 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; the figure 14 is a three-dimensional schematic view of a frame and a grid forming a secondary closure according to another exemplary embodiment of the invention; Figure 15represents a grid adapted to form a secondary closure of an underground chamber as illustrated in figure 14 . DETAILED DESCRIPTION OF THE INVENTION

[0033] This description is given as a non-limiting example of an embodiment. Figure 1 is a schematic view of an underground chamber having a secondary closure in accordance with the state of the 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 in order to close the underground chamber 1.

[0034] 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.

[0035] The purpose of the grid 5 is to secure the underground chamber 1, essentially when opening the cover (or other primary closure device), or when said cover is opened or removed. Indeed, when opening the chamber cover, which is generally heavy, there is a risk that this 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 who opens the cover.

[0036] 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.

[0037] Grid 5, which is not subjected to such significant and repeated forces (for example the passage of vehicles) as the primary closure, must nevertheless be securely fixed to underground chamber 1.

[0038] For this purpose, supports 6 are, in the example shown here, securely fixed, preferably pegged, to opposite walls 2 of the underground chamber.

[0039] The chamber is arbitrarily oriented by considering that the walls where the supports 6 are fixed are longitudinally opposed, that is to say here in 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.

[0040] 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.

[0041] 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.

[0042] Different types of supports 6 are known in the state of the art. An example of a known, functionally advanced support is shown in Figure 2 .

[0043] There Figure 2thus represents the first support 7 and the second support 8.

[0044] 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 installation of an anchor pin. A second portion 11 of the bracket has a hook 12 which is attached, for example welded, to the first support.

[0045] The hook 12 makes it possible to block a transverse axis 13 of the grid 5 in order to allow it to tilt.

[0046] The second support 8 also comprises two solid and rigid brackets. A first portion 9 of each bracket comprises orifices 10 each allowing the installation of an anchor pin. At least one of the two brackets of the second support 8 comprises a ring 14 fixed, for example welded, on 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 placed in the ring 14, in order to lock the grid 5 in the closed position.

[0047] These supports can nevertheless be improved: they are complex parts to produce (they require the assembly of the hooks 12 and the ring 14, in particular), they are rolled parts assembled by mechanical welding which are relatively expensive, and they require great assembly precision. In particular, if the longitudinal spacing between the supports is not correctly respected and is too large, there is a risk that the grid 5 can be extracted from the first support 7 despite the presence of a padlock in the ring 14. Conversely, if the spacing is too small, the assembly of the grid 5 may be impossible, or the grid may rest incorrectly on the support 6.

[0048] According to known embodiments, a precision of the order of 2 mm is necessary to guarantee the correct positioning and correct operation of the grid 5. However, such precision 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.

[0049] There Figure 3 illustrates supports 6A in accordance with a first embodiment of the invention.

[0050] Just as in the known embodiment shown in the Figure 2 , the supports 6A comprise a first support 7A and a second support 8A.

[0051] The first support 7A comprises two parts, namely two angle irons 16. The two angle irons 16 may be identical. Each angle iron 16 comprises a fixing wing 17 intended to be fixed, for example pegged, to a wall of the underground chamber. The fixing wing 17 may thus comprise orifices 10 each allowing the installation of an anchoring pin. In the example shown here, the orifices 10 are oblong, allowing a certain adaptation of the transverse position of the angle irons 16. Each angle iron 16 also comprises a wing 18, perpendicular to the fixing wing 17.

[0052] Wing 18 has a slot 19.

[0053] As can be seen in the Figure 4, the slot 19 has a substantially constant width l. This width l is such that it allows the passage, with a small clearance, of the axis 13 of the grid 5, which has a diameter D. The slot 19 can have a complex trajectory, for example essentially curvilinear. In the example shown here, the slot 19 has a substantially “C” shaped trajectory. The slot 19 has an end portion 20, which is closed and straight. This end portion is substantially horizontal when the first support 7A is fixed in an underground chamber.

[0054] As represented in the Figure 5, when the first support 7A is fixed to the wall 2 of the underground chamber 1 using bolts, the two brackets 16 are fixed such that their wings 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 brackets 16 through its inlet 21 (beginning of the upper branch of the "C" formed by the slot). Then, the axis 13 is advanced in each slot 19 of the brackets until the axis 13 is in the terminal portion 20 (formed by the lower branch of the "C"). The axis 13 can then no longer escape from the first support 7A from above. It remains freely rotatable, 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 adjustment of the longitudinal position of the axis 13.

[0055] On the Figure 5, the axis 13 is positioned near the closed end of the terminal portion 20, which corresponds to the position of the axis 13 when the grid 5 is tilted towards its open position. In particular, the “C” configuration of the slot 19 allows the axis 13 to be spaced from the wall 2 of the chamber, which improves the stability in the open position of the grid 5.

[0056] It is also notable 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 path of the slot 19 to its entrance 21.

[0057] Each of the two angles 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 steel or galvanized) with a thickness of approximately 3 mm can for example be used for this. Given the small dimensions of the angles 16, a scrap of metal plate can generally be used to form each angle 16.

[0058] Regarding the second support 8A of the embodiment of the Figure 3, it also comprises two parts, namely also two angles 16A. The two angles 16A may be identical. Each angle 16A comprises a fixing wing 17A intended to be fixed, for example pegged, to a wall of the underground chamber (opposite the wall where the first support 7A is fixed). The fixing wing 17A of each angle may thus comprise orifices 10 each allowing the installation of an anchoring peg. In the example shown here, the orifices 10 are oblong, allowing a certain adaptation of the transverse position of the angles 16A.

[0059] Each angle iron 16A forms a tab 22, which extends perpendicular to the fixing wing 17A.

[0060] The tab 22 further extends vertically, so that it passes through a notch 23 formed in the grid 5 when the latter is placed in abutment on the second support 8A, as shown in Figure 6 .

[0061] 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.

[0062] This provides a certain freedom in the longitudinal positioning of the angles 16A forming the second support 8A, between the two extreme positions shown in the Figure 6 , offering a travel of d.

[0063] 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.

[0064] Hole 24 allows a padlock or any other suitable locking device to be passed through it, in order to lock the grid 5 in its closed position.

[0065] There Figure 7is a three-dimensional schematic view of an underground chamber 1 comprising a secondary closure device comprising the supports of the Figure 3 .

[0066] Compared to the underground chamber of the Figure 1 , underground chamber 1 of the Figure 7 differs from it by the secondary closing device used. In particular, the first support 7A, comprising the two angles 16 having a slot 19 into which the axis 13 of the grid 5 is introduced, is fixed to a first wall of a longitudinal end of the underground chamber 1.

[0067] The second support 8A comprising two angles 16A comprising tabs 22 allowing the locking of the grid 5 is fixed on the wall of the underground chamber 1 opposite longitudinally.

[0068] There figure 8represents a template allowing correct positioning of the angles forming respectively the first support 7A and the second support 8A in an underground chamber. This template 25 is formed from a plate so that it comprises a first surface 26 and a second perpendicular surface 27.

[0069] As shown in the figure 9 , the first surface 26 of the template 25 is intended to be placed in contact with an upper edge of the underground chamber 1, in this case on the support surface 4 of the frame 3 of the chamber.

[0070] The first surface 27 may comprise a handle 28 which is foldable in order to facilitate the handling of the template 25.

[0071] The second surface 27 is pressed into contact with 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 placed in contact with 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.

[0072] The second surface 27 of the template comprises openings 30 whose position corresponds to the position of the holes to be made. In particular, as in the example shown in figures 8 And 9 , openings 30 having 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 orifices 10 of the supports.

[0073] The selection of the openings used to make the holes in the wall 2 of the underground chamber 1 makes it possible to choose the installation depth of the grid 5 with respect to the support surface 4 of the frame 3.

[0074] There Figure 10 represents an example of a support for the secondary closure of an underground chamber, in this case the first support 7B, according to an embodiment of the prior art in which the supports are linked to one side of the frame of the underground chamber. Figure 10 illustrates the fact that the support of a secondary closure device can be connected directly to the frame 3. This simplifies the installation of the secondary closure, but, of course, this is only possible for underground chambers which must be equipped with such a secondary closure from the outset. In the known embodiment of the Figure 10, the first support 7B comprises two tabs 31 welded to the frame 3. Each tab 31 comprises a perforated plate 32 allowing an axis 33 to be mounted there (for example in the form of a bolt) for the articulation of a grid 5.

[0075] Concerning the second corresponding support 8B, represented in the Figure 11 , it also comprises two tabs 31A each forming a support for receiving 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 using a padlock.

[0076] The support of the figures 10 And 11 is complex, requires many welded parts, and does not allow tool-free disassembly of the grid from the frame 3.

[0077] On the same principle as that detailed above with reference to the figures 3 to 7, within the framework of the present invention there are provided supports 6C, comprising a first support 7C shown in Figure 12 and a second 8C support shown in the Figure 13 .

[0078] The first support 7C is formed from a part comprising a central plate 34 and two wings 18A parallel to each other and perpendicular to the central plate 34.

[0079] The central plate 34 further comprises an end portion 35 which is welded to the frame 3.

[0080] Each wing 18A has a slot 19A.

[0081] Slot 19A, just like the slot of the embodiment of the 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.

[0082] The slot 19A has, in the example shown here, a substantially “S” shaped trajectory. The slot 19A has an end portion 20A, which is closed, straight and substantially horizontal when the frame 3 is in place on an underground chamber.

[0083] The axis 13 of the grid can easily be inserted into the slot 19A and placed in the portion 20A, from where it can then 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 removal of the grid from the first support 7C can be carried out without tools.

[0084] The second 8C support, shown in the Figure 13, has a general constitution 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 legs 22A, which extend perpendicular to the central plate 34A. The legs 22A also extend vertically, so that they pass through the notches 23 formed in the grid 5 when the latter is placed in abutment on the second support 8C.

[0085] 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.

[0086] At least one of the legs 22A comprises a hole 24 located above the grid 5, more precisely above the upper surface 15 of the grid 5 when the latter is resting on the second support 8C.

[0087] Hole 24 allows a padlock or any other suitable locking device to be passed through it, in order to lock the grid 5 in its closed position.

[0088] Compared to the known embodiment shown in figures 10 And 11 , the first support 7C and the second support 8C can be made by folding and cutting a metal sheet, without any additional parts. They also allow the installation and removal of the grid very easily and without tools.

[0089] In addition, the frames comprising the support for the secondary closing grid according to the figures 12 And 13 are stackable for storage and transport, without requiring any part (wooden block or other) interposed between the frames. This is not the case for frames known in the prior art such as that of Figures 11 and 12, because elements of the first support 7B and / or of the second support 8B (in particular the perforated plates 32 or the rings 14A) would interfere.

[0090] All of the embodiments described above assume that the support is installed on the farthest opposite walls of an underground chamber. However, whether the support is attached to the chamber or directly welded to the frame, it can be positioned on the nearest opposite walls of the chamber. This is illustrated in figure 14 , which shows a frame 3 having a secondary closing support. The support of the figure 14 may correspond to the one illustrated in figures 12 And 13 . Thus, we then consider by convention that the longitudinal direction L corresponds, on the figure 14 , to the direction of the smallest side of frame 3. The transverse direction T is that of the largest side of frame 3.

[0091] There Figure 15illustrates a grid 5 which can thus be used to form a secondary closure device in accordance with an embodiment of the invention. The grid 5 has the particularity of comprising on either side (in 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 indifferently in one direction or the other. It will be noted that the axis 13 is here formed of several coaxial portions.

[0092] 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 the frame, for example up to 20 mm to 30 mm.

[0093] 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

1. A secondary closure device for an underground chamber, intended to be installed in said underground chamber (1) under a main closure device, in order to close, when said secondary closure device is in a closed position, at least in part, the 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 (7A, 7C) forming a hinge and allowing the grid (5) to pivot about the transverse axis (13), so that the grid (5) can be pivoted to an open position in which access to the underground chamber (1) is released, - a second support (8A, 8C), the first support (7A, 7C) and the second support (8A,8C) being positioned near opposite walls, in a so-called longitudinal direction (L), of the underground chamber (1), , characterized in that 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) comprising a slot (19, 19A) which has a substantially “C” shaped trajectory or a substantially “S” shaped trajectory, said slot (19, 19A) having a width (I) greater than the diameter (D) of the axis (13), thus allowing the axis (13) to slide in the slot from an inlet (21) to an end portion (20, 20A) and allowing the grid to rotate around the axis (13), said end portion (20, 20A) being straight and allowing a longitudinal translation of the transverse axis (13).

2. Secondary closing device for an underground chamber according to claim 1, in which the second support (8A, 8C) comprises 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, in which 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, in which the at least one vertical leg (22, 22A) of the second support (8A, 8C) comprises 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 leg (22, 22A) a locking device, for example a padlock.

5. Secondary closing device for an underground chamber according to one of the preceding claims, in which the first support (7A, 7C) or the second support (8A, 8C) is formed of two angles (16, 16A), each angle (16, 16A) comprising a fixing wing (17, 17A) intended to be fixed, for example pegged, 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) to fix the first support (7A) or the second support (8A) thereto, the template consisting of a plate, said plate comprising a first surface (26) intended to be brought into contact with an upper edge of the chamber, a second surface (27) intended to be brought into 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 brought into 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) comprising openings (30) whose position corresponds to the position of the holes to be made., 7. Secondary closure device for an underground chamber according to one of claims 1 to 4, in which the first support (7C) is formed from a part comprising a central plate (34) and two parallel wings (18A) perpendicular to the central plate (34), said central plate (34) comprising a folded end part (35) adapted to be welded to a frame (3).

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

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

10. Secondary closing device for an underground chamber (1) according to one of the preceding claims, in which the first support (7A, 7C) and / or the second support (8A, 8C) is produced solely by folding and cutting a flat sheet.

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