EP4692459A1

EP4692459A1 - Building element and method for dealing with silting of water intakes

Info

Publication number: EP4692459A1
Application number: EP25192944.4A
Authority: EP
Inventors: Filippo POJERO; Alberto Gasparin
Original assignee: Palumbarus Di Alberto Gasparin Srl
Current assignee: Palumbarus Di Alberto Gasparin Srl
Priority date: 2024-08-05
Filing date: 2025-07-30
Publication date: 2026-02-11

Abstract

The invention concerns a building element for an intake volume in a basin comprising a bottom surface and a water intake. The building element comprises a side wall, a lower end and an upper end. The lower end is suitable for being laid down on the bottom surface of the basin, such that the side wall and the bottom surface define an intake volume comprising the water intake of the basin. From the upper end a protection permeable cage protrudes comprising a door configured for the passage of an operator. The invention also concerns a method for laying down such a building element.

Description

TECHNICAL FIELD

The present invention concerns a building element and a method which are intended for dealing with the problem of the silting of water intakes immersed in bodies of water, for example in the artificial basins.

STATE OF THE ART

The realization of dams, i.e. artificial barriers built along waterways in order to create artificial basins to collect considerable amounts of water, has been known for a long time. The water accumulated in such artificial basins can be destined for different uses, mainly for the production of hydroelectric energy, agricultural irrigation or water supply.
Usually the artificial basins comprise one or more surface drains intended to ensure that, even in the event of a flood, the level of water in the basin remains below the safety threshold defined in the project. The surface drains consist of spillways that can take different forms depending on the specific conformations of the dam and of the relative basin. In some cases the top of the dam itself comprises an overflowable portion, while in other cases the basin comprises a siphon spillway or a chalice spillway that is separate from the dam.
In addition to the surface drains, each artificial basin also needs one or more bottom drain works. These bottom drains are primarily aimed at conveying the desired amount of water from the reservoir towards the destination to which it is intended (for example, a forced pipeline, an irrigation canal or an aqueduct). The bottom drains are also aimed at allowing, if necessary, the partial or total emptying of the artificial basin, for example to be able to carry out maintenance interventions on the basin itself or on the facing upstream of the dam. The bottom drains are generally pressure tunnels, whose mouth can open with an almost vertical axis on the bottom surface of the basin or it can open with an almost horizontal axis at the foot of the facing of the dam. Usually the outflow of water from the bottom drain is regulated by a sluice gate.
As is widely known in the sector, a problem linked to the artificial basins is that of their progressive silting or burial. In every river the flow of water drags with it a large amount of material such as mud, sand, pebbles and various sediments. In the presence of a dam, the water stops inside the artificial basin, depositing all the solid material in suspension on the bottom. Inevitably, therefore, the solid material accumulates by gravity and cover the bottom design surface of the basin.
The silting of an artificial basin first of all has the effect of reducing the volume available to receive water; this reduces the functionality of the basin itself. However, some more significant problems may derive from the presence of sediments near the bottom drain. These sediments, in fact, when dragged by the water flow to the opening of the control sluice gate of the drain, can reach the plants located downstream causing damages or malfunctions.
One solution, to avoid the problems linked to the silting of the artificial basin, is that to periodically remove the sediments from the bottom.
However, the work of dredging the bottom of a basin necessarily involves raising a large amount of material passing in suspension, making the water turbid and often unsuitable for the uses for which it is intended. Alternatively, the removal of the sediments can be carried out by excavation, i.e. after emptying the basin. Of course, in this case the basin cannot supply water for the entire period during which the excavation works are carried out.
In addition, regardless of how it is carried out, the removal of the sediments is very expensive because it implies the need to dispose of their huge amount in a controlled manner. These sediments are in fact considered special waste by law and as such must be treated and disposed of.
The problems highlighted above with reference to the artificial basins can be found almost identical in other situations in which an intake work is arranged near the bottom of a basin, whether it is a lake, a river, a canal or the sea. By way of example, consider the water intakes intended for the various circuits of a thermoelectric power plant or a water desalination and/or purification plant. Even in these cases, despite a careful study of the positioning, during its operational life the water intake may run the risk of remaining covered with sediments.
Patent document JP H 09-111739 describes a connecting collector intended for draining a basin that opens laterally in the facing of a dam or of an embankment. The collector comprises a connection side duct made in such a way as to couple precisely to the drain. The realization of such a collector requires precise knowledge of the conformation of the drain and of the area surrounding it. Normally this knowledge is available for newly created basins. Conversely, with regard to the older basins, it often happens that the drawings are no longer available because they were lost or that, although available, they do not really correspond to the state of the works, for example due to wear and tear thereof. In these cases it is therefore impossible to realize the side duct of the collector such that it adapts precisely to the existing drain.
The need is therefore felt for a new solution to the problem of the silting of water intakes.

OBJECTS AND SUMMARY OF THE INVENTION

The object of the present invention is therefore to overcome the drawbacks highlighted above in relation to the prior art.
In particular, a task of the present invention is to make available a building element and a method that allow to solve in a simple and economical way the problem of the silting of the water intakes.
Furthermore, a task of the present invention is to make available a building element and a method that allow to address the problem of the silting by eliminating the need to remove and dispose of sediments.
Moreover, a task of the present invention is to make available a building element and a method that allow to obtain a temporary and easily removable solution.
Finally, a task of the present invention is to make available a building element and a method for addressing the problem of the silting, which facilitate periodic intervention.
These and other objects and tasks of the present invention are achieved by means of an element in accordance with claim 1 and a method in accordance with claim 7. Further features are identified in the dependent claims. All appended claims form an integral part of the present disclosure.
The invention first of all concerns a building element for an intake volume in a basin comprising a bottom surface and a water intake. The building element comprises a side wall, a lower end and an upper end. The lower end is suitable for being laid down on the bottom surface of the basin, such that the side wall and the bottom surface define an intake volume comprising the water intake of the basin. From the upper end a protection permeable cage protrudes comprising a door configured for the passage of an operator.
The particular structure of the building element allows the realization of an intake volume that allows the problem of the silting of the water intake of the basin to be dealt with in a simple and economical way.
In some embodiments, the side wall is closed on itself to form, in a plan view, a closed curve.
This solution is intended for use in the basins where the water intake opens directly onto the bottom surface.
In other embodiments, the side wall is open to form, in a plan view, a curve having two end portions separated from each other.
This solution is intended for use in the basins where the water intake opens laterally, for example in the facing of a dam or of an embankment.
Preferably the building element is configured for completely surrounding the water intake of the basin. Even more preferably the building element is configured for surrounding the water intake and a part of the bottom surface adjacent thereto.
This solution allows the application of the building element to any hydraulic work without the need for precise knowledge of the conformation of the water intake and/or of the area surrounding it.
Preferably the permeable cage comprises a plurality of elongated structural elements spaced from each other.
This solution makes it possible to construct a protection cage in a simple and structurally robust way that prevents dangerous debris from entering the intake volume.
Preferably the structural elements are arranged in an inclined manner with respect to the vertical direction.
This particular configuration allows dangerous debris stopped by the permeable cage to be moved away, causing it to slide laterally by gravity.
Preferably the permeable protective cage is configured for being removed from the upper end.
In this way it is possible, if necessary, to superimpose two building elements on each other, so as to expand the intake volume.
Preferably, the side wall of the building element is made of steel.
Compared to other building materials, steel allows considerable advantages in terms of handling, strength, modularity and removability.
The invention further concerns a method for obtaining an intake volume in a basin. The method comprises the steps of:

providing a basin comprising a bottom surface and a water intake, wherein the basin further comprises a layer of sediments which covers the bottom surface near the water intake;
providing a building element in accordance with what is described above;
lowering the building element down until the lower end thereof is laid on the layer of sediments near the water intake;
progressively removing the sediments under the building element until the lower end thereof is laid on the bottom surface; and
defining, with the side wall of the building element and the bottom surface of the basin, an intake volume comprising the water intake of the basin.

This method makes it possible to lay down a building element in accordance with the invention in a simple and economical way, so as to easily obtain an intake volume. In this way it is possible to manage the problem of the silting of the water intake of the basin.
Preferably, the step of progressively removing the sediments under the building element is carried out by an operator who takes position inside the intake volume.
The particular structure of the building element of the invention allows the operator to work safely, greatly simplifying the steps of the method.
Preferably, the step of progressively removing the sediments under the building element is carried out by dislodging the sediments under the building element.
This particular method is particularly simple and economical and exploits gravity to progressively lay the building element.
Preferably, the method of the invention further comprises the step of completely surrounding the water intake of the basin with the building element. Even more preferably, the method of the invention further comprises the step of completely surrounding with the building element the water intake and a part of the bottom surface adjacent thereto.
This solution allows the application of the method of the invention to any hydraulic work without the need for precise knowledge of the conformation of the water intake and/or of the area surrounding it.
In accordance with some embodiments, the method further comprises the further steps of:

removing the protection permeable cage from a first building element laid on the bottom surface;
providing a second building element in accordance with what is described above; and
lowering the second building element down until the lower end thereof is laid on the upper end of the first building element.

Further features, purposes and advantages of the present invention will become more evident from the description below.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be described hereinbelow with reference to some examples, provided for illustrative and non-limiting purposes, and illustrated in the appended drawings. These drawings illustrate different aspects and embodiments of the present invention and reference numerals illustrating structures, components, materials and/or similar elements in different drawings are indicated by similar reference numerals, where appropriate. Moreover, for clarity of illustration, certain references may not be repeated in all figures.

Figure 1 schematically represents a sectional view of an artificial basin near the dam and the water intake, in accordance with the prior art, under design conditions;
figure 2 schematically represents the basin of figure 1 in a step of complete silting of the water intake;
figure 3 schematically represents a view similar to that of figure 1, of a different artificial basin under design conditions;
figure 4 schematically represents the basin of figure 3 in an advanced phase of silting;
figure 5 schematically represents a view similar to that of figure 4, to which a step of the method in accordance with the invention is applied;
figure 6 schematically represents a view similar to that of figure 4, to which another step of the method in accordance with the invention is applied;
figure 7 schematically represents a view similar to that of figure 4, in which a building element has been installed in accordance with the invention;
figure 8 schematically represents a view similar to that of figure 7, in which two building elements have been installed in accordance with the invention;
figure 9 represents an axonometric view of a water intake comprising a building element in accordance with an embodiment of the invention;
figure 10 represents a view of the section made along trace X-X of figure 9;
figure 11 represents a side elevational view of a building element in accordance with an embodiment of the invention;
figure 12 represents a view of the section made along trace XII-XII of figure 11;
figure 13 represents an axonometric view of a different water intake comprising a building element in accordance with another embodiment of the invention; and
figure 14 represents a view of the section made along trace XIV-XIV of figure 13.

DETAILED DESCRIPTION OF THE INVENTION

While the invention is susceptible to various modifications and alternative constructions, certain preferred embodiments are shown in the drawings and are described hereinbelow in detail. It must in any case be understood that there is no intention to limit the invention to the specific embodiment illustrated, but, on the contrary, the invention intends covering all the modifications, alternative, same and equivalent constructions that fall within the scope of the invention as defined in the claims.
The description addresses in detail the peculiar technical aspects and features of the invention, while the known aspects and technical features per se can only be mentioned. In these respects, what is stated above with reference to the prior art remains valid.
The use of "for example", "etc.", "or" indicates non-exclusive alternatives without limitation, unless otherwise indicated. The use of "comprises" and "includes" means "comprises or includes, but not limited to", unless otherwise indicated.
The invention is intended to operate in the presence of gravity acceleration g. Based on the gravity acceleration g, the vertical direction and the horizontal directions are uniquely defined. Similarly, with respect to the gravity acceleration g, the terms "high", "upper", "above" and similar are defined with respect to the terms "low", "lower", "below" and similar.
In the following description, geometric terms such as "parallel", "perpendicular", "incident", and the like are used. As the skilled person can well understand, these terms must not be understood in an absolute sense, but in an intuitive sense, i.e. considering the normal tolerances of the civil engineering sector.
In the present discussion, continuous reference is made to a water intake, meaning thereby indifferently a bottom drain, a wall drain, the end of an intake duct or any other work configured for removing water from a basin.
In the present discussion, continuous reference is made to a basin, meaning thereby indifferently a natural lake, an artificial lake, a river, a canal, the sea or any body of water that hosts a water intake.
For simplicity, the following description refers, by way of non-limiting example, to an artificial basin comprising a dam, in which the water intake is a bottom drain. The skilled person will have no difficulty in applying the solution of the invention to other similar situations where a water intake is exposed to the risk of being silted.
In accordance with a first aspect, the invention concerns a building element 20 for an intake volume 22 of a basin 24 comprising a bottom surface 26 and a water intake 28. The building element 20 comprises a side wall 30, a lower end 32 and an upper end 34. The lower end 32 is suitable for being laid down on the bottom surface 26 of the basin 24 such that the side wall 30 and the bottom surface 26 define an intake volume 22 comprising the water intake 28 of the basin 24. The upper end 34 is closed by a protection permeable cage 36 comprising a door 38 configured for the passage of an operator.
In a manner known per se, the basin 24 comprises a bottom surface 26. In the case of an artificial basin 24, the bottom surface 26 can be the one defined at the design stage, sometimes defined by a masonry work (as in the attached figures), sometimes defined by a natural geological structure, such as for example a rock plane. In some cases, however, when for example the silting phenomenon already began a long time ago and has never been addressed, the bottom surface 26 can be the one defined by old sediments that have settled and compacted for a long time. In any case, the bottom surface 26 to which reference is made in the present discussion must be sufficiently compact and stable to firmly bear the building element 20.
During the operational life of the basin 24, the bottom surface 26 is usually covered by a layer of sediments 40 that are dragged by the water and that deposit by gravity. The thickness of the layer of sediments 40 superimposed on the bottom surface 26 may vary over time, in particular it may increase as a result of the supply of new sediments 40 or it may decrease as a result of removal operations.
At least one water intake 28 opens near the bottom surface 26 of the basin 24. The lower end 32 of the building element 20 is configured such that it can be firmly laid on the bottom surface 26 of the basin 24. The building element 20 is shaped such that when the lower end 32 thereof is laid on the bottom surface 26, the side wall 30 of the building element 20 and the bottom surface 26 of the basin 24 define a partially closed intake volume 22, inside which the mouth of the water intake 28 of the basin 24 opens.
In some basins 24, the water intake 28 opens directly into the bottom surface 26, locally assuming a substantially vertical course. See figures 3 to 10 in this regard. In this case it is preferable that the side wall 30 of the building element 20 is closed on itself to form, in a plan view, a closed curve, for example circular. In this way, once the lower end 32 is laid on the bottom surface 26 of the basin 24, the building element 20 encloses a portion of the bottom surface 26 of the basin 24 in which the water intake 28 opens; this situation is well represented in figure 9. In this case, the side wall 30 and the bottom surface 26 of the basin 24 define an intake volume 22 which is completely closed laterally and which, thanks to the permeable cage 36, is open upwards. In other words, the building element 20, once it has been correctly arranged, is able to completely surround the water intake 28 so as to constitute an upward lengthening thereof. In this regard, see for example figures 9 and 10.
In other basins 24, the water intake 28 opens onto the facing 42, for example of the dam or of an embankment, near the bottom surface 26, locally assuming a substantially horizontal course. See in this regard figures 1, 2, 13 and 14. In this case, it is preferable that the side wall 30 of the building element 20 is open to form, in a plan view, a curve having two end portions separated from each other, for example a C-shaped curve. As in the previous case, the lower end 32 of the building element 20 is intended to be laid on the bottom surface 26 of the basin 24. In this case, the side wall 30 of the building element 20 and the bottom surface 26 of the basin 24 define an intake volume 22 that is only partially closed laterally and open upwards. In this case, the two end portions of the side wall 30 are intended to be laid on the facing 42. In this way, the intake volume 22 is completely closed laterally, in part by the side wall 30 of the building element 20 and in part by the facing 42. Also in this case the building element 20 is able to completely surround the water intake 28 so as to constitute an upward lengthening thereof, although in this case the building element 20 imposes an angle (usually by about 90°) to the overall course of the drain flow. In this regard, see for example figures 1, 2, 13 and 14.
It should be noted that in both cases the building element 20 is advantageously configured for completely surrounding the water intake 28 of the basin 24, and not for connecting directly to it in a precise manner. Preferably, the building element 20 is configured for surrounding the water intake 28 and a part of the bottom surface 26 adjacent thereto. This solution introduces a safety margin and therefore allows it to be successfully applied to any hydraulic work in any condition. The realization of the building element 20 of the invention does not in fact require the precise knowledge of the conformation of the water intake 28 and/or of the area surrounding it.
The side wall 30 of the building element 20 preferably defines a continuous and impermeable surface, configured for preventing the passage of water. The side wall 30 of the building element 20 can be made of concrete or of other materials commonly used for building hydraulic works. However, it is preferable that the side wall 30 of the building element 20 is made of steel, since in this way the building element 20 is on the whole much lighter and stronger.
As mentioned above, the upper end of the building element 20 is closed by a protection permeable cage 36. The permeable cage 36 is configured to allow the passage of water from the basin 24 to the intake volume 22. At the same time, the permeable cage 36 is configured for preventing debris whose dimensions are larger than a certain predefined threshold from entering the intake volume 22, such as boulders or scrap dragged by the water on the bottom of the basin 24.
Advantageously, the permeable cage 36 can comprise a plurality of elongated structural elements 44, for example linear, such as bars, tubes or beams, advantageously spaced from each other. The structural elements 44 are preferably sized so as to be able to withstand the impacts deriving from the impact of the debris that must be stopped by the permeable cage 36 itself and retained outside the intake volume 22. The maximum distance between two adjacent structural elements 44 defines the predefined threshold beyond which it is preferable for the debris to be stopped outside the intake volume 22. This maximum distance can be, for example, 30 cm.
Preferably the structural elements 44 are arranged in an inclined manner with respect to the vertical direction. In this way the debris that is stopped by the permeable cage 36 slides more easily along the structural elements 44 accumulating around the building element 20, without weighing on the permeable cage 36 itself.
The permeable cage 36 further comprises a door 38 configured for the passage of an operator. Preferably the door 38 can move between an open position, in which it allows the passage of the operator, and a closed position, in which it prevents the passage of the operator and of any debris. Preferably, the dimensions of the door 38 allow the easy passage of an operator equipped with all the equipment and instruments necessary to safely carry out diving operations near the water intake 28. Typically, these operations carried out by the diving operator may concern the installation of the building element 20 itself, for example in accordance with the method that will be described below. Of course, the operator can access the intake volume 22 even after the installation of the building element 20, for example to carry out control, maintenance or cleaning operations of the building element 20 and/or of the water intake 28. By way of example, the door 38 in the open position may define a passage having a useful dimension comprised between 80 cm and 100 cm.
Preferably, therefore, in view of the above, the permeable cage 36 as a whole assumes a frustoconical (figures 9-12) or semi-frustoconical shape (figures 13-14). In this embodiment, the larger (lower) base of the frustum of cone couples to the upper end 34 of the building element 20, the side surface develops upwards and is formed by the inclined structural elements 44, and the shorter (upper) base accommodates the door 38.
In some embodiments of the invention, the building element 20 is made according to a modular logic and the protection permeable cage 36 is configured for being removed from the upper end 34. In this case, once the building element 20 is correctly positioned on the bottom of the basin 24, it is possible to remove the protection permeable cage 36 from the upper end 34 and superimpose a second building element 20 on the first building element 20 previously laid on the bottom surface 26. In particular, it is possible to lay the lower end 32 of the second building element 20 on the upper end 34 of the first building element 20, so as to obtain an upward lengthening of the side wall 30 and therefore an extension of the intake volume 22. Consider figure 8 in this regard.
This embodiment of the invention allows the intake volume 22 to be extended upwards as the thickness of the layer of sediments 40 accumulated around the water intake 28 increases. In the impossibility of removing the sediments 40, the progressive upward extension of the intake volume 22 represents a simple and economical solution to maintain the functionality of the artificial basin 24.
It is also particularly advantageous in this regard that the side wall 30 of the building element 20 is made of steel. The mechanical characteristics of steel in fact allow to superimpose numerous building elements 20 on each other, without incurring problems deriving from the compressive force. Conversely, other materials, such as for example concrete, do not allow such a solution, except through studying specific interventions to counteract the effect of the compression on the building element 20 further down.
In accordance with a second aspect, the invention concerns a method for obtaining an intake volume 22 in a basin 24, comprising the steps of:

providing a basin 24 comprising a bottom surface 26 and a water intake 28, wherein the basin 24 further comprises a layer of sediments 40 which covers the bottom surface 26 near the water intake 28;
providing a building element 20 in accordance with the invention;
lowering the building element 20 down until the lower end 32 thereof is laid on the layer of sediments 40 near the water intake 28;
progressively removing the sediments 40 under the building element 20 until the lower end 32 thereof is laid on the bottom surface 26; and
defining, with the side wall 30 of the building element 20 and the bottom surface 26 of the basin 24, an intake volume 22 comprising the water intake 28 of the basin 24.

The attached figure 4 schematically shows a basin 24 suitable for the use of the building element 20 and of the method in accordance with the invention. In particular, the basin 24 of figure 4 comprises a design bottom surface 26 and a water intake 28. The bottom surface 26 is also covered by a layer of sediments 40, at least near the water intake 28.
Preferably, in the context of the method of the invention, the step of lowering the building element 20 down is carried out thanks to the use of a crane, or of other handling system, which allows the building element 20 to be lowered down on the vertical of the water intake 28. Preferably, in a manner known per se, the crane is mounted on a pontoon or on a barge (figure 5), thereby facilitating the step of laying the lower end 32 thereof on the layer of sediments 40 near the water intake 28 (figure 6).
Preferably, the step of progressively removing the sediments 40 under the building element 20 is carried out by an operator who takes position inside the intake volume 22. This step can be carried out by dislodging the sediments 40 under the building element 20; in this way the mass of the sediments 40 becomes locally incoherent and unable to bear the weight of the building element 20 itself, which consequently sinks progressively by gravity. For example, this step can be carried out with the help of a water pump that sucks the water by dislodging the sediments 40. The water and the dislodged sediments 40 can thus be removed from the intake volume 22. Proceeding in this way, it is possible to lay the lower end 32 of the building element 20 on the bottom surface 26 of the artificial basin 24 (figure 7).
It is also particularly advantageous in this regard that the side wall 30 of the building element 20 is made of steel. The mechanical characteristics of steel in fact make it possible to obtain a relatively thin building element 20, the lower end 32 of which has a reduced rest surface. In this way, once put in position (figure 6), the building element exerts a high pressure on the sediments 40 and this helps the sinking operation of the building element 20.
It should also be noted that the volume of the sediments 40 that have to be removed from inside the intake volume 22 is extremely small compared to the overall volume of the basin 24. For this reason, the removed sediments 40 can be safely repositioned inside the basin 24 itself, for example in a calm area away from the water intake 28 or by distributing them in a thin layer over a wide surface. This avoids any problems linked to the treatment and to the disposal of the sediments.
It should be noted that the building element 20 of the invention allows the operator to work safely inside the intake volume 22, since the protection permeable cage 36 protects him/her from any debris with dangerous dimensions.
In accordance with some embodiments, the method of the invention may advantageously comprise the further steps of:

removing the protection permeable cage 36 from a first building element 20 laid on the bottom surface 26;
providing a second building element 20 in accordance with the invention; and
lowering the second building element 20 down until the lower end 32 thereof is laid on the upper end 34 of the first building element 20.

As already highlighted above, this embodiment of the invention allows the intake volume 22 to be extended upwards as the thickness of the layer of sediments 40 accumulated around the water intake 28 increases, thus maintaining the functionality of the basin 24.
The method of the invention has been described with reference to a case in which the water intake 28 opens vertically in the bottom surface 26 of the basin 24 (figures 3-10). However, the skilled person will have no difficulty in applying such teachings of the invention to the case where the water intake 28 opens laterally in the facing 42 (figures 1, 2, 13 and 14).
It should also be noted that the particular structure of the invention allows the building element 20 to be used temporarily. In some cases, in fact, it is necessary to create an intake volume 22 intended solely to allow maintenance or renovation works, at the end of which the water intake 28 must be released and returned to the initial state. In this case, the building element 20 of the invention can be positioned and removed with the same simplicity, without leaving residual structures in place.
As the person skilled can well understand, the invention overcomes the drawbacks highlighted above in relation to the prior art.
In particular, the invention makes available a building element 20 and a method that allow to solve in a simple and economical way the problem of the silting of the water intakes.
Furthermore, the invention makes available a building element 20 and a method that allow to address the problem of the silting by eliminating the need to remove and dispose of sediments.
Still, the invention makes available a building element 20 and a method that allow to obtain a temporary and easily removable solution.
Finally, the invention makes available a building element 20 and a method for addressing the problem of the silting, which facilitate periodic intervention.
The description reported above in particular delves into the innovative aspects of the invention and the differences between this and the known solutions. For all other aspects, known in themselves, that the invention shares with the prior art, what is described in the introductory part in relation to the known solutions remains valid.
In conclusion, all the details can be replaced by other technically equivalent elements; the characteristics described in relation to a specific embodiment can also be used in the other embodiments; the materials used, as well as the contingent shapes and dimensions, can be any according to the specific implementation needs without leaving the scope of protection of the following claims.

Claims

Building element (20) for an intake volume (22) in a basin (24) comprising a bottom surface (26) and a water intake (28), wherein the building element (20) comprises a side wall (30), a lower end (32) and an upper end (34), wherein the lower end (32) is suitable for being laid down on the bottom surface (26) of the basin (24), such that the side wall (30) and the bottom surface (26) define an intake volume (22) comprising the water intake (28) of the basin (24), and wherein from the upper end (34) a protection permeable cage (36) protrudes comprising a door (38) configured for the passage of an operator.
Building element (20) according to claim 1, wherein the side wall (30) is closed on itself to form, in a plan view, a closed curve.
Building element (20) according to claim 1, wherein the side wall (30) is open to form, in a plan view, a curve having two end portions separated from each other.
Building element (20) according to one or more of the preceding claims, wherein the building element (20) is configured for completely surrounding the water intake (28) of the basin (24).
Building element (20) according to one or more of the preceding claims, wherein the building element (20) is configured for surrounding the water intake (28) and a part of the bottom surface (26) adjacent to the water intake (28).
Building element (20) according to one or more of the preceding claims, wherein the permeable cage (36) comprises a plurality of elongated structural elements (44), spaced from each other and arranged in an inclined manner with respect to the vertical direction.
Building element (20) according to one or more of the preceding claims, wherein the protection permeable cage (36) is configured for being removed from the upper end (34).
Building element (20) according to one or more of the preceding claims, wherein the side wall (30) of the building element (20) is made of steel.
Method for obtaining an intake volume (22) in a basin (24), comprising the steps of:
- providing a basin (24) comprising a bottom surface (26) and a water intake (28), wherein the basin (24) further comprises a layer of sediments (40) which covers the bottom surface (26) near the water intake (28);

- providing a building element (20) according to one or more of the preceding claims;

- lowering the building element (20) down until the lower end (32) thereof is laid on the layer of sediments (40) near the water intake (28);

- progressively removing the sediments (40) under the building element (20) until the lower end (32) thereof is laid on the bottom surface (26); and

- defining, with the side wall (30) of the building element (20) and the bottom surface (26) of the basin (24), an intake volume (22) comprising the water intake (28) of the basin (24).
Method according to the preceding claim, wherein the step of progressively removing the sediments (40) under the building element (20) is carried out by an operator who takes position inside the intake volume (22).
Method according to the preceding claim, wherein the step of progressively removing the sediments (40) under the building element (20) is carried out by dislodging the sediments (40) under the building element (20).
Method according to one or more of claims 9 to 11, further comprising the step of completely surrounding with the building element (20) the water intake (28) of the basin (24).
Method according to one or more of claims 9 to 12, further comprising the step of surrounding with the building element (20) the water intake (28) and a part of the bottom surface (26) adjacent to the water intake (28).
Method according to one or more of claims 9 to 13, further comprising the steps of:
- removing the protection permeable cage (36) from a first building element (20) laid on the bottom surface (26);

- providing a second building element (20) according to one or more of claims 1 to 8; and

- lowering the second building element (20) down until the lower end (32) thereof is laid on the upper end (34) of the first building element (20).