Increased fuse

Abstract

Fuse riser (1) for hydraulic structure comprising: a trough (2) having a front surface including a lower edge (12), the trough (2) being able to be disposed on the sill (30) of a spillway of the hydraulic structure in a nominal position such that the lower edge (12) is in contact with the sill (30), the trough (2) being able to pivot under the action of external forces (F, G) around an axis (Z) defined by at least one stop (32) disposed on the sill (30), up to an angle (α) less than a critical tilting angle, angle (α) causing the lower edge (12) of the front surface to rise away from the sill (30);and a sealing gasket (16) mounted on the front surface, the sealing gasket (16) being movable in translation relative to the front surface to ensure a seal between the lower edge (12) and the sill (30) of the spillway of the hydraulic structure not only when the trough (2) is in the nominal position but also when the trough is pivoted by an angle (α) less than the critical tilting angle. Figure of the abstract: Figure 4B;

Description

Title of the invention: Fuse riser technical field

[0001] This disclosure relates to the field of hydraulic structures, such as dams, dikes, or river weirs. In particular, this disclosure relates to fusible weirs, devices that retract in the event of an exceptional flood. Prior art

[0002] Document FR 2 656 354 B1 introduces the concept of a fusible weir. This passive device comprises a module placed on the sill of a spillway in a hydraulic structure, forming a barrier that raises the dam's spillway crest. During most floods, water flows over the fusible weirs, which act as a free-spilling sill. Each module consists of three parts: the trough, the pressure chamber, and the feed shaft. A seal ensures the system is watertight, and drains clear the chamber in case of accidental filling. Stops located downstream of the module keep the fusible weir in place on the spillway. In the event of an exceptional flood, i.e., when the water level exceeds a predetermined critical height, the chamber of a weir is filled with water. Pressure builds up under the weir, creating a destabilizing moment that causes it to tip over downstream.As the water rises, the fusible risers switch over one after the other, each configured to switch at a different critical height.

[0003] The reliability of such a device depends in part on the supply of water to the chamber when the water level reaches the wellhead. To prevent obstruction of the supply to the chamber, document EP 2 215 308 B1 describes the concept of a protected well. This particular design proposes supplying the pressurization chamber via a baffle that is invisible from the outside.

[0004] As long as the water level remains below the wellhead, the fusible risers are susceptible to reversible rotation around the axis formed by the stops, a rotation caused by an additional force. Such rotation generates water leaks downstream of the fusible risers, and the partial pressurization of the chamber reduces the module's stability margin. Although this apparent unreliability of the safety system is temporary—since the riser returns to its position when the additional force exerted by external elements ceases—it is undesirable. When the additional force disappears, the fusible riser returns to its nominal position. Since the water leakage rate can be significant, it is generally unacceptable.

[0005] There is therefore a need to eliminate this leakage flow and the partial pressurization of the chamber caused by the rotation of the fusible riser for the loading case described above. Summary

[0006] The present disclosure remedies this situation.

[0007] A fusible riser for a hydraulic structure is thus proposed, comprising a trough having a front surface including a lower edge, the trough being able to be disposed on the sill of a spillway of the hydraulic structure in a nominal position such that the lower edge is in contact with the sill, the trough being able to pivot under the action of external forces around an axis defined by at least one stop disposed on the sill, up to an angle strictly less than a critical tilting angle, an angle causing the lower edge of the front surface to rise away from the sill;and a sealing gasket mounted on the front surface, the sealing gasket being movable in translation relative to the front surface to ensure a seal between the lower edge and the sill of the hydraulic structure's spillway not only when the trough is in the nominal position but also when the trough is pivoted from the lower angle to the critical tipping angle.

[0008] The inventors of this document have established that the expansion of ice that can form on the surface of the water in a hydraulic structure can create an additional force ('additional' because it is added to the water pressure) on the fusible link, an additional force that can be sufficient to cause the link to pivot by a few degrees, thus causing water leaks downstream and / or from the reservoir to the pressure chamber. The movable seal ensures the watertightness of the fusible link even in the case of an inclined position. To a lesser extent, other forces such as seismic forces can cause the fusible link to rotate. The movable seal also ensures watertightness in this load case.

[0009] The term "spreader" refers to an element that can have various shapes or dimensions and that constitutes an obstacle to the flow of water. The spreader is designed to be placed without fixing on the sill of a hydraulic structure's spillway. Once installed, the spreader assumes a position, referred to in this document as the nominal position. This is a stable equilibrium position as long as the water level is below a critical height. The presence of the spreader raises the permissible water level (and therefore the capacity) of the hydraulic structure. The spreader is called a fusible spreader because it constitutes a safety element in the event of a flood. To this end, a device allows the spreader to be tilted if the water level exceeds the critical height, a critical height that may correspond to a 100-year or 1,000-year flood. At such a water level, the fusible spreader moves away from its position. nominal and tipping out of the spillway threshold. The rise disappears in the floodwater flow downstream of the spillway.

[0010] The term "trough" refers to the solid element, the main constituent of the weir. The trough comprises a so-called frontal surface, which faces upstream and is in contact with the water. The frontal surface has a lower edge, generally straight, which rests on the weir crest in the nominal position of the weir.

[0011] One or more stops are generally provided downstream of the trough. These stops are fixed to the sill and extend beyond the sill to prevent the trough from sliding on the sill.

[0012] Under nominal conditions, the trough is subjected to three forces: its own weight, water pressure, and the resistance of the sill and the stop. As mentioned above, additional forces (ice, earthquake, etc.) can disrupt this equilibrium. The trough can then pivot and find another equilibrium position. In this intermediate inclined position, the trough is in contact with the stop(s), but the lower edge of the front surface is raised. In this temporary equilibrium position, four forces act on the trough: its own weight, water pressure, the resistance of the sill and the stop, and the additional force. Due to the continued contact between the trough and the stops, the trough moves from the nominal position to the intermediate inclined position by rotating around an axis defined by the stops (for example, by an upper edge of the stops).

[0013] This intermediate inclined position is reversible: when the additional force ceases, the riser returns to its nominal position.

[0014] The angle of rotation of the riser in the intermediate inclined position is less than the critical angle, which is the angle triggering the tilting and obliteration of the riser in the event of an exceptional flood.

[0015] The features described in the following paragraphs may optionally be implemented independently of each other or in combination with each other.

[0016] A rail which can extend parallel to the lower edge is fixed to the trough, and the joint is movable under the action of an elastic element interposed between the rail and the joint.

[0017] The joint can be fixed to a slide, itself movable in translation in the rail under the action of the elastic element.

[0018] At least one sealing lip may be disposed between the slide and the rail.

[0019] The seal may be movable in translation under its own weight.

[0020] The trough may include a lateral surface provided with a lower edge, the riser including a second seal movable in translation or rotation relative to the lateral surface.

[0021] The joint may have a length between 50 cm and 30 m and / or a translational stroke between 5 cm and 5 m.

[0022] The critical angle ac can be between 10° and 20°. The design of the riser (dimensions, mass distribution, geometry of the pressure chamber, etc.) determines the critical tilting angle. The lower angle a varies continuously according to the forces acting on the riser, while remaining strictly below the critical angle ac. The translational stroke of the seal is consistent with these angular variations. In other words, the seal stroke is such that sealing is guaranteed for any inclination strictly less than the critical tilting angle of the riser.

[0023] The rise may further include hydraulic communication means configured to supply a pressure chamber of the trough with water when the water level of the hydraulic structure exceeds a critical water height, the pressure chamber being configured to, once filled with water, exert sufficient negative pressure to trigger the tilting and / or lifting of the trough, thereby removing the trough from the weir sill of the hydraulic structure.

[0024] This disclosure also relates to a method of using a fusible riser as described above, the method comprising a step of rotating the fusible riser and a subsequent step of translating the sealing gasket.

[0025] By "subsequent," it should be understood that the rotation step of the trough triggers, potentially with a small phase shift, the translation of the seal. The two steps may be simultaneous or may at least occur with temporal overlap. The seal may translate as soon as the trough rotation begins, and / or the translation of the seal may cease when the trough reaches its intermediate equilibrium position. Brief description of the drawings

[0026] Other features, details and advantages will become apparent upon reading the detailed description below, and upon analysis of the accompanying drawings, on which:

[0027] [Fig.1] shows an isometric view of a fusible riser.

[0028] [Fig.2] illustrates the process of reversing the rise in the event of an exceptional flood.

[0029] [Fig.3] represents a rotation of a known rise under the action of an external force.

[0030] [Fig.4] represents a rotation of a rise according to the present disclosure under the action of an external force.

[0031] [Fig.5] shows a detailed view of a design of a movable joint. Description of the implementation methods

[0032] The figures schematically depict the invention. Some dimensions may be exaggerated to facilitate reading. Upstream and downstream refer to the direction of water flow.

[0033] Figure 1 shows an isometric view of a fusible riser 1. The riser 1 comprises a trough 2. The trough 2 is a solid element, for example made of concrete, possibly reinforced. In the illustrated example, the trough 2 has a base 2.1, a downstream wall 2.2 and two side walls 2.3, 2.4.

[0034] The side walls 2.3, 2.4 can stand vertically and perpendicular to the base 2.1. The downstream wall 2.2 can be inclined, rising as it moves downstream, and can form an angle of approximately 120° with the base. The trough 2 can naturally take other forms.

[0035] A front surface 4 is formed by the base 2.1 and the side walls 2.3, 2.4. The water that accumulates in the hydraulic structure comes into contact with this surface 4 and enters a space 6 delimited by the side walls 2.3, 2.4 and by the downstream wall 2.2. If the water level increases, the water can overflow above the top surface 8 of the trough 2.

[0036] The trough 2 is placed on the sill 30 of a spillway in a hydraulic structure. The sill 30 may be substantially flat and horizontal. Several troughs 2 are arranged contiguously to cover the entire width of the spillway. The lateral surface 10 of the side wall 2.4 may thus come into contact with a neighboring trough (not shown). In addition to the fusible weirs, which are passive devices, the spillway may be equipped with mechanized gates.

[0037] The front surface 4 has a lower edge 12 which is in contact with the weir 30. The lateral surface 10 has a lower edge 14 also in contact with the weir 30.

[0038] A seal 16 is fixed to the front surface 4 in a lower part, i.e. in the vicinity of the lower edge 12. A second seal (not shown) can be disposed at the lower edge 14 of the lateral surface 10.

[0039] The length of the lower edge 12, and therefore that of the joint 16, can be between 50 centimeters and 30 meters. The trough 2 can be several meters high.

[0040] Figures 2A to 2C illustrate the general operating principle of a fusible riser 1 using a cross-sectional view.

[0041] In [Fig. 2] A, the riser 1 is in its nominal position, that is, the position it initially adopts and maintains stably under normal conditions (no additional force or exceptional flooding). The trough 2 includes a pressurization chamber 18. The chamber 18 is connected to a well 20 via fluidic communication means 22. The assembly is represented simply with a parallelepiped chamber and straight conduits acting as of a fluidic means of communication, but in reality it can be more complex. Well 20 is open at its top to allow water to enter when the water level corresponds to a critical height Hc above threshold 30.

[0042] Under normal conditions, the water is retained at least in part by the downstream wall 2.2 of the trough 2. The water can flow downstream without unbalancing the trough 2, when the water level is greater than the height of the downstream wall 2.2, without however exceeding the critical height Hc.

[0043] To prevent the trough 2 from sliding on the threshold 30 under the action of the water, one or more stops 32 may be provided in contact with the base of the trough 2.

[0044] Figure 2 B shows an exceptional situation, namely a flood that causes the water level to rise above the critical height Hc. Under these conditions, water enters the well 20 and feeds the pressure chamber 18. A drain can prevent the unintentional accumulation of water in the chamber 18. However, when the flow rate of water entering the chamber 18 is significant (in the case of a flood, it is much greater than the evacuation capacity of the drain), the chamber 18 fills and exerts pressure (also called negative pressure by hydraulic engineers) on the trough 2.

[0045] As shown in [Fig. 2] C, the shape of the trough 2 is such that the pressure exerted by the chamber 18 initiates the tilting of the trough 2. The trough 2 is shown in an inclined position at a critical angle ac in [Fig. 2] C, an angle beyond which the trough 2 tilts and lifts off the sill to allow the water to drain. The critical angle ac can, depending on the geometry and mass distribution of the trough 2, be between 10° and 20°.

[0046] The spillway can be equipped with several troughs 2 which have respective critical heights Hc, which leads the troughs to tip successively, thus smoothing the effects of the flood downstream of the hydraulic structure.

[0047] Figure 3 A illustrates a trough 2 of the prior art in the nominal position. Figure 3 B shows that external elements, here ice G which can form on the surface of the water, can apply a force F on the trough 2. The expansion of the ice tends to rotate the trough 2 around an axis Z perpendicular to the figure and supported by the stop 32, by an angle denoted α. This angle is less than the critical angle αc of Figure 2 C which would cause the trough 2 to tip. The trough 2 therefore does not tip under the action of the ice G but adopts a (temporary) equilibrium position, inclined relative to the nominal position. In this position, downstream water leaks are possible, with water rushing under the lower edge of the front surface and in particular under the joint 20 which is fixed to the trough in existing trough geometries.

[0048] Fig. 4 A illustrates a trough 2 of the present disclosure in the nominal position. Fig. 4 B shows this trough under ice stress and illustrates that the seal 20 is movable in translation parallel to the front surface, downwards. The movement of the The seal 20 compensates for the rotation of the trough 2 to ensure a watertight seal and prevent water leaks downstream. The stroke of the seal, that is to say the distance between the extreme highest and extreme lowest positions of the seal, can be between 5 centimeters and 5 meters.

[0049] Fig. 5 shows an example of the design of the mechanism allowing the mobility of the sealing joint 16 in a cross-section.

[0050] The seal 16 may be made of an elastomer of the EPDM (ethylene-propylene-diene monomer) type. Its profile may generally be rectangular. It may have a lower lip oriented upstream, that is to say away from the front surface 4.

[0051] The seal 16 can be a single piece or can consist of several seal sections carefully positioned in contact with each other.

[0052] A rail 24 can be fixed to the front surface 4 of the trough 2. The rail 24 extends parallel to the lower edge 12. The rail 24 may have a U-shaped cross-section, open at the bottom. Elastic means 26 can be interposed between the rail 24 and the seal 16 to force the seal downwards as soon as the trough 2 pivots out of its nominal position. When the trough 2 returns to its nominal position, the contact between the seal 16 and the threshold 30 pushes the seal 16 upwards.

[0053] In the illustrated example, a metal slide 17 encloses an upper part of the joint 16. The slide 17 extends parallel to the rail 24. The presence of the slide 17 allows the elastic means 26 not to apply force directly to the joint 16.

[0054] The elastic means 26 may be of a suitable nature and stiffness to ensure the downward vertical translation of the seal 16 during rotation of the trough (see Figures 4A and 4B). The elastic means 26 may, for example, consist of helical springs, Belleville washers, spring steel strips, or elastomeric materials.

[0055] Water can enter the gap 19 between the rail 24 and the slide 17. It is therefore advantageous to provide a sealing lip 28 to prevent water leaks downstream.

[0056] The rail may optionally be pierced with holes to facilitate the circulation of water in and out of the gap 19 (or at least to balance the water pressures), so as not to impede the movement of the joint.

[0057] This mechanism thus allows the seal to be deployed downwards passively and reliably during the rotation of the trough.

[0058] In an alternative not illustrated, the joint is mobile under its own weight. To this end, the joint can be appropriately ballasted, depending on the water height (and therefore the Archimedes' pressure) of the hydraulic structure.

[0059] In an unillustrated variant, the deployment of the joint is obtained by mechanized means, upon detection of a rotation of the trough 2 by a geometric sensor such as an inclinometer.

[0060] The kinematics of the joint deployment can be more or less complex. In the illustrated example, the joint undergoes a simple translation. Other kinematics are possible, such as a rotation around the lower edge 12.

[0061] An identical type of seal can be arranged at the lower edge 14 of the lateral surface 6. This second seal can be movable in translation or possibly in rotation, for example around the Z axis. It can thus deploy in rotation in the opposite direction to the rotation of the trough 2. The second seal can have a length between 50 cm and 30 m and / or a translational stroke between 5 cm and 5 m and / or a rotational stroke between 1° and 15°.

Claims

Demands

1. Fuse riser (1) for hydraulic structure comprising: a trough (2) having a front surface (4) including a lower edge (12), the trough (2) being able to be disposed on the sill (30) of a spillway of the hydraulic structure in a nominal position such that the lower edge (12) is in contact with the sill (30), the trough (2) being able to pivot under the action of external forces (F) around an axis (Z) defined by at least one stop (32) disposed on the sill (30), up to an angle (a) strictly less than a critical angle (ac) of tipping, angle (a) causing the lower edge (12) of the front surface (4) to rise away from the sill (30);and a sealing gasket (16) mounted on the front surface (4), the sealing gasket (16) being movable in translation relative to the front surface (4) to ensure a seal between the lower edge (12) and the sill (30) of the spillway of the hydraulic structure not only when the trough (2) is in the nominal position but also when the trough is pivoted by an angle (a) less than the critical angle (ac) of tipping.;

2. Fuse riser (1) according to claim 1, wherein a rail (24) extending parallel to the lower edge (12) is fixed to the trough (2), and wherein the joint (16) is movable under the action of an elastic element (26) interposed between the rail (24) and the joint (16).

3. Fuse riser (1) according to the preceding claim, wherein the seal (16) is fixed to a slide (17), itself movable in translation in the rail (24) under the action of the elastic element (26).

4. Fuse riser (1) according to the preceding claim, wherein at least one sealing lip (28) is disposed between the slide (17) and the rail (24).

5. Fuse riser (1) according to claim 1, wherein the joint (16) is movable in translation under its own weight.

6. Fusible riser (1) according to any one of claims 1 to 5, wherein the trough (2) comprises a lateral surface (10) provided with a lower edge (14), the riser (1) comprising a second sealing joint movable in translation or rotation relative to the lateral surface.

7. Fuse riser (1) according to any one of claims 1 to 6, wherein the joint has a length between 50 cm and 30 m and / or a translational stroke between 5 cm and 5 m.

8. Fuse riser (1) according to any one of claims 1 to 7, wherein the critical tilt angle (ac) is between 10° and 20°.

9. Fuse riser (1) according to any one of claims 1 to 8, further comprising hydraulic communication means (20, 22) configured to supply a pressure chamber (18) of the trough (2) with water when the water level of the hydraulic structure exceeds a critical water height (Hc), the pressure chamber (18) being configured to, once filled with water, exert sufficient negative pressure to trigger the tipping and / or lifting of the trough (2), thereby causing the removal of the trough (2) from the sill (30) of the spillway of the hydraulic structure.

10. Method of using a fusible riser according to any one of claims 1 to 9, the method comprising a step of rotating the fusible riser and a subsequent step of translating the sealing gasket.