Collapsible dam and clamp therefor

Abstract

 The subject matter of the invention is a device for connecting together sheets (3) which form the outer sheath (29 or 36) of a collapsible dam, and simultaneously connecting said sheath to the bed of a waterway. Said device comprises a plurality of elementary clamps (1 or 22) alternated with hinges (2) formed by the sheets (3) of the sheath. Rubberized ropes (14, 15 or 27, 28) extending from one bank to the other of the waterway, provide continuity for the clamps and hinges.

Description

[0001] The present invention relates to a device for connecting together elements of a collapsible dam and in particular, to a device for connecting, for example, the sheets forming the flexible sheath ofthe dam with each other, or with tie-rods suited for anchoring the collapsible dam to the bottom of the waterway that the dam has to obstruct.

[0002] In the present invention, particular mention is made to the type of collapsible dams formed by a flexible and expansible sheath of a cylindrical form, which dams impede by their presence the passage of water, when the sheath becomes inflated.

[0003] However, the device according to this invention must not be considered limited to the just described type of dam, but it can also be utilized for any other type of collapsible dams which are provided with at least one flexible element, for example, for dams with a sail, i.e. for dams formed by one or several sheets which at their lower edgesand their lateral edges are connected to the bottom and to the side edges or banks of the waterway, while their upper edge is maintained in a raised position above the bottom, so as to create a dam across the waterway.

[0004] Known collapsible dams may present certain disadvantages, in particular, when they have to be inserted into a waterway the banks of which are not vertical, but are inclined (waterways having a trapeziodal section).

[0005] In such cases in fact, if there are tie-rods that have to be'connected to the dam at points lying in a line substantially parallel to the axis of the dam (i.e. substantially transversal to the axis of the waterway), or if there are several sheets of the flexible sheath of the dam to be connected together always along a line that is substantially parallel to the dam axis, there arise great problems with respect to the connecting points just defined along said line, and in particular, with respect to the connecting points lying in correspondence to the hinges of the dam.

[0006] By 'dam hinges' are defined the zones of the said connecting line at the dividing line between the central section of the dam formed generally by a partially or totally cylindrical surface, and the lateral sections corresponding to the banks, each formed by a surface that is generally partially or totally conical or inclined.

[0007] During use, the development and configuration of the line along which the sheets are connected together and/or the tie-rods are connected to the sheath, vary greatly with the variations of the upstream water basin.

[0008] In fact, if the connecting line is composed of three rectilinear tracts which are rigid and rigidly connected to one another and each of which corresponds to one of the three sections of the dam just described, a variation in the level of the dam (for example, from the collapsed position to the raised position) would not only bring about variations in the angle formed between two adjacent tracts, but it would also determine the tendency of the lateral tracts to shift themselves longitudinally to the dam towards the banks or towards the centre of the waterway, depending upon whether the level variation was positive or negative.

[0009] In fact, whereas the central tract of the connecting line corresponding to the cylindrically shaped section of the dam is maintained substantially parallel to itself, the lateral tracts of said connecting line vary both their length as well as the angle which they form with respect to the central tract.

[0010] As all the known clamps for effecting the connections (indicated hereabove) are long and relatively rigid, it results that they must be interrupted exactly in correspondence to the dam hinges, since they are not capable of following the relative rotations of the three sections of the dam, exactly because of their rigidity and length.

[0011] In spite of this, although lowering the stresses in the hinges that are derived from the reciprocal rotation of the three tracts of the connecting line, the known clamps do not solve the problem of the tendency of the lateral tracts of said line ._'to shift longitudinally to the dam itself. Rather the stresses deriving from said phenomena are amplified due to the length and rigidity of the clamps.

[0012] It follows that in these positions, i.e. in correspondence to the dam hinges, considerable stresses are concentrated, in particular in the sheets, and these stresses can cause ruptures or in any case, a shortening of the service life of the dam itself.

[0013] This concentration of stresses is also enhanced in the known rigid clamps by the fact that these latter are unable to conform by small local movements or rotations in a direction transversally to their own axis, to the small inevitable non-uniformities of the load and/or to per- centual elongations of the sheets and of the ropes of the tie-rods, owing to the following factors: Progressive deformations (creep) in the sheets and in the ropes, variable from point to point; differences between the theoretic dimensions and the actual ones of the sheets and of the ropes of the tie-rods, owing either to the difficulties arising in taking exact and precise on-site measurements during the setting-upoperation, or owing to the working and mounting tolerances that do not guarantee a length that is exactly equal to the intended length; differences in stretchability of the rubberized sheets in correspondence to the zones having a greater thickness where the connections are effected between one sheet and another; differences in the modulus of elasticity, always of the sheets due to differences in their constitution itself, caused, for example, by variable factors associated to the rubberizing process.

[0014] The nature of the tie-rods (variation in the resistence modulus from point to point, or in time) is also the cause of stress concentrations in the sheets and/or in the clamps of the dam.

[0015] The aim of the present invention is to provide a device for connecting together elements of a collapsible dam, which succeeds in obviating the previously stated inconveniences in the zones of the hinges and in the adjacent sections corresponding to the banks of the collapsible dams, and which, in particular, distributes in a uniform manner, the stresses on the sheets of the collapsible dam sheath, which can adapt itself to the rotations that the sections of the dam undergo in passing from the raised position to the collapsed position and vice versa, and which can obviate the imperfections of mounting and of the manufacture of the various component parts of the dam, so as to guarantee altogether a longer service life for the dam itself.

[0016] An object of the invention is a device for connecting together elements of a collapsible dam, comprising at least one flexible element and characterized by the fact of comprising a flexible clamp.

[0017] The present invention will be better understood from the following detailed description made just by way of nonlimiting examples with reference made to the figures of the attached drawing sheets, wherein:

Figure 1 shows a particular embodiment of a device according to the present invention, sectioned along the line I-I of figure 2,

Figure 2 shows in plan view an other embodiment of a device according to the present invention;

Figure 3 shows a section view along line III-III of figure 1j

Figure 4 shows in cross-section an alternative embodiment of a device according to the present invention;

Figure 5 shows in transversal section a dam suited for resisting thrusts from both directions, and provided with a device according to the present inventionj

Figure 6 shows a perspective view of an inflatable dam capable of resisting thrusts from both directions, set up in a waterway having a trapezoidal cross-sectionJ

Figure 7 shows in plan view,sectioned at the height of the connecting line, the dam of Fig. 6, when it is subjected to a higher upstream water level;

Figure 8 shows a top view of the dam of figure 6, when it is subjected to equal levels upstream and downstream;

Figures 9 and 10 show, respectively, sections IX-IX and X-X of the figures 7 and 8.

[0018] In the more general idea of solution of a device for connecting together elementsof collapsible dams comprising at least one flexible element, said device foresees a flexible clamp.

[0019] By a flexible clamp is meant here in the invention a clamp comprising several rigid parts that are connected together by hinges which allow each part to rotate with respect to the adjacent ones around a longitudinal axis (torsion), as well as around at least one transversal axis (flexion).

[0020] In figures 1, 2 and 3, there is shown a particular embodiment of a device for connecting together elements of a collapsible dam according to the present invention. Said device foresees, as already stated, flexible clamps.

[0021] More particularly, the device according to the present invention as shown in said figures 1, 2 and 3 foresees a plurality of elementary clamps 1 (of which only one is completely visible in figure 21 alternated with hinges 2.

[0022] Said hinges 2 can be of any whatsoever type, and in the particular embodiment shown in said figures they are constituted in particular by sheets 3 and 3' of a flexible and inextensible material (such as, for example, a rubberized fabric) that are connected together by the elementary clamps 1, to form the flexible sheath of the dam.

[0023] Said dam, which is not shown in its whole in the figures 1, 2 and 3, can be, for example, a dam similar to the one shown in the figures 5 or 6.

[0024] Each elementary clamp 1 comprises a slab 4 to which are associated means for connecting the slab 4 to a point outside the dam itself.

[0025] Said means are, in the particular embodiment shown in the figures, at least one connection formed by a fork 5 that is secured to a tie-rod such as, for example, a chain or rope 6 anchored to a fixed point outside of the dam (see, for example, point 32, figure 5), said fork 5 enclosing one end of the slab 4 and being connected to the latter by means of a bolt-nut unit 7 that traverses the fork 5 and the slab 4.

[0026] In figure 2, there is shown _'in broken lines a second connection provided on the same slab 4 and secured to a tie-rod inside the dam itself.

[0027] Said second connection is quite similar to the one just described and it is situated at the opposite end of the slab 4 with respect to the connection of the outer tie-rod 6.

[0028] The connection shown in broken lines would be the one necessary for connecting the tie-rod inside the dam (see figure 5) to the elementary clamps.

[0029] Said slabs 4 can, however, be without the end zones for connecting to tie-rods, seeing that not all the elementary clamps 1 are associated to a tie-rod, but that some of the clamps 1 are only utilized for connecting together the sheets 3 and 3' in a watertight manner.

[0030] As an alternative, several tie-rods may be connected to each end of the slab 4. On each side of the slab 4 there is a jaw 8. The two jaws 8 and the slab 4 are kept together by means for pressing said jaws 8 and the slab 4 together.

[0031] Said means comprise in the particular embodiment shown in figures 1, 2 and 3, a pair of bolts 9 that traverse the jaws 8 and the slab 4 and which are kept in position by nuts 10 screwed on their threaded ends.

[0032] Both, the nuts 10 and the bolts 9, are lodged in appropriate seats 11 and 12 provided in the body of the jaws 8.

[0033] The jaws 8 are moreover provided with at least one cavity 13 facing towards the slab 4 itself.

[0034] In said cavities 13 are lodged means for providing continuity to the plurality of clamps 1. Said means moreover provide continuity also to the plurality of hinges 2 alternated with the clamps 1.

[0035] Said means can be ropes or chains which extend along the entire length of the dam itself, and which are anchored down by their own extremities to the opposite banks of the waterway, and in particular, they are ropes 14, covered with a layer of elastomeric material 15,

[0036] Around the said covered ropes 14, there are wound the sheets 3 and 3' , so that they are lodged in the cavities 13 and connected to the elementary clamps 1.

[0037] A further cavity 16 is present on said jaws 8 and also faces the slab 4, so as to limit the contact between the jaws 8 and the slab 4 to two strips 17 and 18 (indicated with a broken line in figure 2).

[0038] Moreover, in correspondence of the strip 18, there are present two guides comprising projections 19 on the jaws 8 and slots 20 which, for example, traverse the slab 4, so as to guarantee an exact alignment between the jaws 8 and the slab 4 of each elementary clamp 1.

[0039] In correspondence of the hinges 2, there can be present sealing means for preventing the passage of water between the inside and the outside of the flexible sheath of the dam that is.formed by the said sheets 3 and 3'.

[0040] Said means can be, for example, gaskets 21 (see figure 3). Said gaskets 21 can, for example, be of elastomeric material that swells when coming or being in contact with water. As an alternative, said gaskets 21 can be the elastomeric material itself that forms said sheets 3 and 3' which is such as to swell when coming or being in contact with water.

[0041] In figure 4, there is shwon a cross-section view of an alternative embodiment of a device for connecting together elements of a collapsible dam.

[0042] Even this device foresees a flexible clamp and in particular, a plurality of clamps 22, alternated (like elementary clamps 1 and hinges 2 of figures 1, 2 and 3) with hinges (not shown) interposed between said elementary clamps 22.

[0043] Said elementary clamps 22 comprise a C-shaped profile 23 and two bars 24 of a length equal to that of the profile 23.

[0044] Said bars 24 are connected to the inner side of the wings 25 of said C-shaped profile 23 so as to result as facing and parallel to each other.

[0045] Means, such as screws 26, are foreseen for drawing said bars 24 closer. The bars 24 and the C-shaped profile 23 define a cavity inside which are lodged and blocked ropes or chains, and in particular ropes 27 provided with a covering layer 28 of elastomeric material, which ropes 27 are quite similar to and serve the same purpose as the sheathed ropes 14, 15 described in figures 1, 2 and 3.

[0046] Said ropes 27 extend along the entire length of the dam and are anchored to the opposite banks of the waterway in which the dam is placed.

[0047] Around said ropes 27 there are wound the edges of the sheets 3 and 3' (similarto those previously described in figures 1, 2 and 3),that form the sheath of the collapsible dam itself.

[0048] The elementary clamp 22 is particularly suited for connecting together the sheets forming the flexible sheath of a collapsible dam.

[0049] In the case of the device shown in figure 4, in correspondence of the hinges alternated with the elementary clamps 22, it may not be necessary to insert gaskets, since the sheets are already in contact with one another, even within the clamp 22. As a consequence, it is that the sheets 3 and 3' themselves effect the seal, since they are pressed one against the other.

[0050] In figure 5, there is shown a cross-section view of an inflatable dam anchored to the bottom of a waterway by means of a device according to the present invention.

[0051] Said dam is particularly suited for resisting the thrusts exerted on it by the positive water levels between the upstream basin and the downstream basin, or vice versa.

[0052] Said dam comprises a sheath 29 formed, for example, by two sheets 30 and 31, that are connected together by devices according to the present invention.

[0053] Said devices comprise elementary clamps 1 (indicated schematically, since they have been previously shown and described in the figures 1, 2 and 3) connected to one point not belonging to the dam itself, by means of ropes 6.

[0054] Said ropes 6 are connected to anchoring points 32 placed at the bottom and/or at the banks of the waterway.

[0055] Said elementary clamps 1 are moreover connected to each other in pairs by means of tie-rods inside the dam 'itself, formed, for example, by ropes 33 (see, for example, the solution shown in figure 2 in broken lines).

[0056] The devices according to the present invention have hence the double function of keeping together the various sheets 30, 31 which form the sheath 29 of the dam, and at the same time, to anchor said sheath 29 to the bed of the waterway itself.

[0057] In figures 6 to 10 there is shown another type of dam provided with devices according to the present invention.

[0058] Said dam is an inflatable dam inserted into a waterway having a trapezoidal cross section. Said dam is particularly suited for resisting thrusts (created by different levels) from both directions, i.e. thrusts deriving from a higher level of the upstream basin 34 with respect to the level of the downstream basin 35 (as shown in figures 7 and 9) or vice versa.

[0059] In particular, said dam comprises a tubular sheath 36 formed by one or several sheets of a flexible and inextensible material, for example, of a rubberized fabric.

[0060] The broken line (indicated with the reference numeral 37) is the connecting line, i.e. the line along which the tie-rods'(not shown in the figures 6, 7 and 8) are connected to the tubular sheath 36 by means of a device according to the present invention (not shown), i.e. by means of a plurality of flexible clamps 1 and/or 22.

[0061] The flexible clamps 1 and 22 described and shown previously can follow the movement and the rotations of the dam, in particular, during the inflating and collapsing phases of the dam itself, not only in correspondence of the hinges 38, but also along the entire length of the connecting line 37.

[0062] In fact, the dam is formed by three sections, namely two frusto-conical sections 39, which are placed in correspondence of the inclined banks of the waterway, and a third section 40 which is cylindrical and which is placed in correspondence of the flat bottom of the waterway.

[0063] Said sections 39, 40 and the dam in its whole are connected to the bottom and/or to the banks of the waterway by tie-rods placed inside the dam itself (figures 9 and 10).

[0064] In fact, said tie-rods, which are formed, for example, by chains or by ropes 6, are connected to one end of the elementary clamps 1 (shown schematically in the figures 9 and 10), while the opposite end thereof is connected to an anchorage 41. Said anchorage 41 is placed substantially in correspondence to the line along which the sheets of the sheath 36 are connected in a water-tight manner to the bottom and to the banks of the waterway.

[0065] In particular, as shown in figures 9 and 10, said anchorage 41 is coincident with the line along which the sheets forming the sheath 36, are connected to the bottom and to the banks of the waterway itself.

[0066] Preferably, as shown in figures 9 and 10, the tie-rods, and in particular the ropes 6, result in being crossed inside the dam itself.

[0067] In fact, the ropes 6 (the taut ones) connected to the anchorage 41 and placed upstream (at the left in figures 9 and 10) are connected at their other extremity to the elementary clamps 1 placed on the connecting line on the downstream side of the dam itself. Similarly the ropes 6 (the slack ones) connected to the anchorage 41 and placed downstream (at the right in figures 9 and 10) are connected at their other end to the clamps 1 placed at the connecting line on the upstream side of the dam itself.

[0068] Whenever the dam has to resist thrusts exerted in one sense only (for example, from upstream to downstream, as indicated in figure 9), the ropes 6 shown in figure 9 as being slack can be eliminated, and the clamps 1 of the upstream connecting line can be substituted by clamps 22.

[0069] The functioning of a collapsible dam that is provided with a device for connecting together elements of said dam. according to the present invention, with particular reference to the dam shown in the figures 6 to 10, is as follows: Supposing that the dam is in a collapsed position and it is desired to inflate it for creating a weir across the waterway, there is initiated the sending of a fluid, such as, for example, the water itself that is present in the waterway, into the sheath 36.

[0070] The means for effecting said inflation are already known, and hence, it is within the knowledge of any technician of the field to determine the type and the site, in order to obtain the desired results.

[0071] As the dam becomes gradually inflated, and also in function of the quantity or level of water that is contained in the upstream basin 34, the three sections 39, 40 of the dam rotate one with respect to the other, in particular and owing to the trapezoidal geometry of the cross section of the waterway itself, both in the plane of said section as well as in the plane which contains the hinges 38. In fact, the cylindrical section 40 tends to rotate, being pushed by the water present in the upstream basin 34 that is being formed.

[0072] Similar rotations of the two frusto-conical sections 39 are not allowed except to a small degree, since their cross section gradually deminishes, and hence, having a lesser development and being connected to the banks, they become less deformed.

[0073] Hence, a torsion results in the plane that contains the hinges 38 between the various sections 39, 40 of the dam itself.

[0074] To this rotation, there is added the rotation undergone by the dam in the plane of the section of the waterway, since the collapsed development of the dam is greater than its inflated development.

[0075] This situation can be seen in the figures 7 to 10. In particular, figures 8 and 10.show the dam of figure 6 in a plan view and in a cross-section view respectively, when the level of water in the upstream basin 34 is equal to that in the downstream basin 35.

[0076] As can be seen particularly in figure 7 (in which is represented a plan view of the dam sectioned in correspondence of the free water surface of the two basins), the dam is displaced more downstream with respect to the dam axis itself (indicated with the broken line a-a in figures 7 and 8).

[0077] In figure 8 instead the dam which is in the state of supporting equal and contrary thrusts is disposed symmetrically with respect to its own axis (indicated with the broken line a-a). In displacing from the position shown in figure 8 to that of figure 7 or vice versa the central section 40 of the dam displaces towards downstream direction, deforming itself and rotating with respect to its axis a-a, dragging along with it for as much as the anchorage permits, also the two lateral sections 39. The particular deformation assumed by the dam (see figure 7) is due to a greater richness and flexibility furnished to the rubberized fabric forming said dam exactly in correspondence of the hinges 38 of the dam. The term "richness" indicates that the development of the fabric in this area is greater than that strictly necessary for the inflated dam. This extra development of the fabric is necessary to permit the deflated sheath to contact the bottom of the trapezoidally sectioned waterway. In fact the development of the deflated sheath when contacting the inclined banks and the bottom of the waterway is greater than that strictly necessary to obstruct the waterway. This difference between the deflated and inflated development is the richness which is taken up by the loops which form in correspondence of hinges 38 separating the lateral conical portions of the dam from the cylindrical central portion.

[0078] In fact, said fabric forms in correspondence of the hinges 38 loops 42 and 43 respectively in the downstream and upstream sides of the dam itself, which are preferably turned towards the inside of the dam itself by means of the use of tie-rods having a lesser length (traced with a broken line in figure 9 and indicated with the reference numeral 44).

[0079] Said loops 42 and 43 are at the position where the greater richness of the fabric, necessary for consenting a correct collapsing of the dam in contact with the bottom of the waterway, is maintained when the dam is inflated, i.e. when it is in the state in which it requires a lesser development.

[0080] In correspondence of said loops 42 and 43 there are used preferably clamps 22 of the type shown in figure 4 instead of the clamps 1 of the figures 1 to 3.

[0081] Said loops 42 and 43 are gradually formed as the dam inflates and they remain so, as long as the dam remains in its position across the waterway.

[0082] When the dam has to be collapsed, the fluid present inside it is made to exit and as a consequence, the sheath 36 forming said dam is disposed adjacent to the banks and at the bottom of the waterway.

[0083] Since the development of the dam in the collapsed position is greater than when inflated, the richness of the fabric that formed said loops 42 and 43 is recovered, and the dam can sink slowly to settle at the bottom.

[0084] With a device for connecting together elements of the collapsible dam according to the present invention the pre-fixed aims are reached.

[0085] In fact, the elementary clamps 1 and 22 forming part of the device according to the present invention, act to uniformly distribute the tensions along the sheets 3 thanks to the presence of the sheathed ropes 14, 15.or 27, 28.

[0086] In fact, it is these sheathed ropes that resist the pulling force exercised by the tie-rods on the sheath, while acting to distribute said pulling force even if received only in correspondence of the clamps on the sheets 3 for the entire length of the dam.

[0087] This better distribution of the forces or stresses to the sheets 3 along the entire development of the dam is also due to the structure itself of the device according to the invention (clamps alternated with hinges), since it is capable of following the variations of the forces and the displacements of the sheets and/or of the anchoring tie-rods due to the variations in the basin levels upstream and downstream, by disposing itself according to an appropriate segmented line (line of lesser energy) rather than opposing the said variations as the known rigid clamps usually do.

[0088] The watertightness for preventing the leakage of the fluid contained in the sheath forming the dam, is further guaranteed by the sealing means placed in correspondence of the hinges in such a way as to impede the leakage of the fluid utilized for inflating the dam itself.

[0089] The adopted solution of utilizing a flexible clamp 1 or 22, realized for example by a plurality of elementary clamps alternated with hinges, that provide to the entire dam the possibility of adapting even to the most curvilinear configurations that the dam can assume, allows the anchoring tie-rods to keep the dam in position without concentrating any stresses along the sheets 3 themselves.

[0090] In particular, this is true in the case of collapsible dams anchored in waterways having a trapezoidal section, where there is no further need for interruptions between the clamps in correspondence of the hinge zone of the dam itself with the consequent concentration of the stresses in correspondence of said interruptions.

[0091] Moreover, thanks to the fact that each tie-rod remains connected to the dam sheath by means of its own elementary clamp, they can absorb and distribute throughout the entire length of the sheets any eventual stresses deriving from the non-perfect execution of the tie-rods or of the sheets, as far as working tolerances and/or mounting tolerances and such phenomena as creepage are concerned.

[0092] The presence of the loops 42, 43 in correspondence of the dam hinges 38 not only allows the three dam sections 39, 40 to rotate, one with respect to the others (torsion in a plane parallel to the axis of the waterway), so as to be disposed in the best possible way for resisting the thrusts exercised by the upstream basin 34 upon the dam itself, but also provides the dam sheath 36 with that greater length which is indispensable for allowing the sheath 36 itself to collapse, and hence, to slowly settle to the bottom of the waterway in such a way as to prevent any damages occurring by any eventual foreign bodies, which might be present in the flow that passes above the sheath 36 itself (rotation of the sheath 36 in the plane of a cross-section of the waterway in correspondence of the hinges 38.

[0093] Although several particular embodiments have been described and illustrated herein, concerning a device for connecting together elements of a collapsible dam according to the present invention, there have also to be taken as comprised within the scope of the invention, all possible alternative embodiments that are accessible to any technician of the field.

[0094] Besides, what must be understood as comprised within the scope of the present invention, is a collapsible dam comprising a flexible element provided with a device according to the present invention.

[0095] The present invention is not to be intended as limited to applications for collapsible dams installed in a waterway having a trapezoidal cross section,but it can also be utilized for any whatsoever type of collapsible dam that is installed in a waterway having any whatsoever type of section.

Claims

1. Device for connecting together elements of a collapsible dam comprising at least one flexible element, characterized by the fact of comprising a flexible clamp.

2. Device according to claim 1,
characterized by the fact that said flexible clamp comprises a plurality of elementary clamps (1 or 22) alternated with hinges (2).

3. Device according to claim 2,
characterized by the fact that said hinges (2) are formed by the flexible elements (3, 3') of the dam.

4. Device according to claims 1 , 2 and 3, characterized by the fact of comprising means (14 or 27) for providing continuity to the plurality of clamps (1 or 22).

5. Device according to claim 4,
characterized by the fact that said means are at least one rope (14 or 27).

6. Device according to claim 5,
characterized by the fact that said rope (14 or 27) is covered with a layer (15 or 28) of elastomeric material.

7. Device according to anyone of the previous claims, characterized by the fact that each elementary clamp (1) comprises a slab (4), two jaws (8) placed opposite with respect to the slab, means (5 to 7) for connecting the slab to a fixed point not belonging to the dam, and means (9, 10) for pressing together the two jaws and the slab, each jaw being provided with at least one cavity (13) facing towards the slab, wherein is lodged one of said ropes (14) and one edge of said flexible element (3) that is wound around the rope itself.

8. Device according to claim 7,
characterized by the fact that said means for connecting the slab (4) to a fixed point not belonging to the dam comprise tie-rods (6) having one of their ends connected to the slab and the other end connected to an anchorage (32 or 41) fixed to the bottom and/or to the banks of the waterway, in which the dam is installed.

9. Device according to claim 8,
characterized by the fact that said anchorage (41) fixed to the bottom and/or to the banks of the waterway is placed substantially in correspondence of the line along which the flexible element of the dam is connected in a watertight manner to the bottom and/or to the banks of a waterway.

10. Device according to claims 8 or 9,
characterized by the fact of comprising at least one tie-rod of reduced dimensions in correspondence of each hinge of the dam itself.

11. Device according to anyone of claims 2 to 6, characterized by the fact that each elementary clamp (22) comprises a C-shaped profile (23), two bars (24) facing and lying parallel to each other and connected to the wings (25) of said C-shaped profile, so as to define a cavity lodging said ropes (27, 28) and the edges of the flexible elements (3) of the dam wound around said ropes and means (26)_'for drawing the bars closer.

12. Device according to anyone of the previous claims, characterized by the fact of comprising sealing means (21) in correspondence of each hinge (2).

13. Device according to claim 12,
characterized by the fact that said sealing means are a gasket (21) of elastomeric material that swells when coming or being in contact with water.

14. Collapsible dam,
characterized by the fact of comprising a device according to any one of the previous claims.

Drawing