EP1362152A1

EP1362152A1 - Sealed and resistant tank

Info

Publication number: EP1362152A1
Application number: EP02706864A
Authority: EP
Inventors: Marcel Matiere
Original assignee: Societe Civile de Brevets Matiere
Current assignee: Societe Civile de Brevets Matiere
Priority date: 2001-02-16
Filing date: 2002-02-15
Publication date: 2003-11-19
Also published as: US6874651B2; US20040112901A1; FR2821105A1; FR2821105B1; JP2004522879A; JP4086145B2; WO2002066770A1

Abstract

The invention concerns a tank for a fluid product, having a bottom (4) and a resistant side wall (10) consisting of juxtaposed prefabricated panels (1) each comprising a wall element (2) covered, on its inner surface (22), with a continuous sealing sheet (3) extended by three parts (33, 33", 34) which cover respectively the lateral sides (23, 23") and the lower side (24) of the wall element (2) and overlap on the outside of the wall (10). Said wall is set on a slab (4) covered with sealing sheets (42) and the adjacent overlapping parts of the sealing sheets (3, 42) covering the assembly of panels (1) and the bottom (4) are tightly linked together. Such a tank which is easy to construct and maintain, can contain drinking water or a polluting product.

Description

Waterproof and resistant tank The invention relates to a waterproof and resistant tank, having a bottom and a side wall made from prefabricated elements and also covers a method of constructing such a tank.

It is often necessary to build reservoirs of greater or lesser capacity, for example for the distribution of drinking water, or else for the storage of any fluid product, in industry or in agriculture. Such tanks are generally limited by a side wall which must withstand the service pressure of the product contained inside the tank and which is generally connected to a sealed bottom in order to avoid losses. water or seepage in the case of a polluting product.

To obtain the necessary resistance economically, the side wall and the bottom are often made of reinforced or prestressed concrete.

However, such a tank must also be sufficiently sparse, to avoid leaks, in particular, if the product it contains is corrosive or harmful.

Generally, it is considered that the concrete is not sufficiently waterproof by itself and that it is therefore necessary to cover the internal face of the wall with a layer of a product ensuring sealing.

When the tank must contain drinking water, it is obviously essential that the sealant is suitable for this use. In addition, the tank must be cleaned periodically and the sealing layer may be damaged. On the other hand, certain corrosive products can, in the long run, attack the waterproofing coating and the concrete.

The maintenance costs of such tanks can therefore be significant and it is often necessary to replace the sealing layer and even, sometimes, the entire tank, after only a few years of use.

The invention makes it possible to remedy such drawbacks thanks to a new embodiment of reservoirs having a low maintenance cost and a longer service life than that of reservoirs produced by the methods known up to now. The invention applies especially to the storage of drinking water but can have other interesting applications. According to the invention, the side wall of the tank consists of a set of juxtaposed prefabricated panels, each comprising a wall element of sufficient thickness to withstand the pressure of the fluid, with two lateral sides, an upper side and a lower side and covered, on an internal face, with a continuous sealing sheet extended by three parts respectively covering the lateral sides and the lower side and each having a length greater than the thickness of the element so as to exceed the outside of the wall by an overhanging part. Said panels are applied against one another by their lateral sides and rest, by their lower side on a slab constituting the bottom of the tank and covered with a sealing sheet having a peripheral projecting part extending to the outside of the wall placed on the slab, and the adjacent projecting parts of the sealing sheets covering all of the panels and the bottom are connected together so as to limit a sealed tank. For this purpose, the lateral projecting parts of the sealing sheet of each panel are tightly connected with the lateral projecting parts of the adjacent panels and the lower projecting part is connected with the peripheral part of the covering sheet covering, tank bottom. In a preferred embodiment, the sealing sheet covering each panel is made of a metal adapted to the fluid contained and the projecting parts of the sheets of the two adjacent panels are interconnected by welding their outer edges.

However, the sealed connection can also be produced by crimping or bonding.

Particularly advantageously, the sealing sheet is made of stainless steel, in particular for tanks containing drinking water. Of course, stainless steel is relatively expensive, but because the pressure resistance is provided by the concrete wall, the sealing sheet can have a very thin thickness and, as a result, the cost increases of construction is offset by the reduction in maintenance costs and the increase in the service life of the tank.

Moreover, stainless steel can even be profitable for tanks containing other products, for example hydrocarbons or for manure pits in the agricultural field, because it is much better resistant to corrosion and cleaning is facilitated.

To build such a tank having a bottom and a side wall, the bottom is first made, consisting of a concrete slab on which a continuous sealing sheet is applied having a peripheral edge and it is placed on this slab , along said peripheral edge, a set of juxtaposed panels forming the side wall, and each covered with a sealing sheet having three projecting parts, folded along the two lateral sides, and on the lower side, said panels being placed l 'one next to the other, so that the folded overhanging parts are applied one on the other and a tight connection is made, on the one hand, at the bottom, between the peripheral edge of the sheet covering the slab and the edge outer of the sheet folded over the lower side of each panel and, on the other hand, in each joint plane between two panels, between the outer edges, parts of the sheets folded over the adjacent lateral sides of said panels.

Particularly advantageously, the external parts of the sealing sheets protruding outside the wall are electrically connected to a ground, so as to provide cathodic protection. Generally, such a tank is produced in the bottom of a pit which is backfilled around the side wall, after the latter has been laid.

The embankment can therefore secure the juxtaposed panels. On the other hand, insofar as the external parts of the sealing sheets are buried in the embankment, this can constitute the mass ensuring cathodic protection.

However, after the welds have been made, it is also possible to cast a concrete blocking belt around the base of the panels.

Such a belt can also be produced at an intermediate level, or else at the upper part of the panels, above the maximum level of the product contained in the tank. In particular, such a fastening belt may consist of beam-shaped elements, arranged one after the other, along the upper part of the wall. Preferably, each element extends on either side of a joint plane between two adjacent panels, and is secured to said panels to produce a continuous belt.

Advantageously, this joining belt can consist of at least one elongated piece having, in cross section, a U-shaped profile covering the upper part of the wall.

The invention, as claimed, also covers other advantageous features which will appear in the following description of certain particular embodiments, given by way of example and shown in the accompanying drawings.

Figure 1 is a front view of a prefabricated panel according to the invention. Figure 2 and Figure 3 are, respectively, a top view and a side view of the panel.

Figure 4 is a horizontal sectional view, on an enlarged scale, of the junction between two adjacent panels.

Figure 5 is a vertical sectional view, on an enlarged scale, of the junction between a panel and the bottom of the tank.

Figure 6 is a partial perspective view of the wall.

Figure 7 shows schematically, in vertical section, a tank according to the invention.

Figure 8 is a perspective view of another embodiment of the reservoir.

Figure 9 is a detail view of the base of a panel. Figure 10 is a partial top view.

Figure 1 1 is a vertical sectional view of the wall.

Figure 12 shows, in top view, a curved wall variant.

In general, as shown schematically in FIG. 7, a tank according to the invention comprises a side wall 10, made up of prefabricated panels 1 placed on a bottom 4 and limiting a capacity (E) capable of containing a fluid product, for example water. As shown in FIGS. 1, 2 and 3, each prefabricated panel 1 comprises a resistant wall element 2, for example of reinforced concrete, having an external face 21 and an internal face 22 on which a sealing sheet 3 is applied , for example, thin metal strips forming strips welded edge to edge.

The structural characteristics of the wall element 2, in particular its thickness (e), as well as its reinforcement, are determined as a function of the forces to be supported in service, in particular to resist the pressure of the fluid product (E) contained in The reservoir.

On the other hand, the metal sheet 3 applied to the panel 2 does not support any effort and only provides sealing. Its thickness therefore depends only on the operating conditions and can range, for example, from a few tenths to 1 or 2 millimeters.

Each panel 1 preferably has a rectangular shape comprising two lateral sides 23, 23 ′, a lower side 24 and an upper side 25. The sealing sheet 3 covers the whole of the internal face 22 of the resistant element 2, at least over a height (h) greater than the maximum height (H) of the product (E) contained in the reservoir.

Preferably, the sealing sheet 3 covers a surface greater than that of the internal face 22 of the resistant element 2, and is extended by three parts 33, 33 ', 34 which extend beyond the corresponding sides 23 , 23 ', 24 of element 2, each over a distance (I) greater than the thickness (e) of element 2. These extensions 33, 33', 34 of sheet 3 are folded and applied to the lateral sides 23, 23 ′ and the lower side 24 of the element 2, as indicated by arrows in FIG. 2, and therefore extend to an edge outer 35 ', 37' which is spaced from the outer face 21 of the element 2 by a distance a = I - e Thus, each panel 1 is surrounded, on three sides 23, 23 ', 24, by parts protruding, respectively lateral 35 and lower 37, each having a rectilinear outer edge 35 ', 37'.

To facilitate the folding of the waterproof sheet 3, it is preferable that the edges of the panel 2 are rounded. At each corner of the panel 1, the lateral edges 330,

340 of the extensions 33, 34 folded over the sides 23, 24 come into contact and are connected by a weld bead 360, so that, on the height (h) of the sheet 3, the resistant element 2 of concrete is housed inside a watertight box formed by the sealing sheet 3 and having three projecting parts 33, 33 ', 34, extending beyond the external face 21 of the element 2.

This box can advantageously be made in advance and placed in the bottom of a mold in order to serve as lost formwork for molding the prefabricated panel 1.

Such prefabricated panels make it possible to easily and quickly produce a sealed tank as shown diagrammatically in FIG. 7, which illustrates the case of a semi-buried tank. On the bottom of an excavation (A), carried out in the ground, a concrete slab 4 is first poured on a surface slightly greater than the cross section to be given to the reservoir and which is limited by a lateral lateral side 41.

The slab 4 is then covered with a continuous sealing sheet 42 which can optionally be laid before setting the concrete, so as to be integral with it.

As shown in the detail view of FIG. 5, the sealing sheet 42 covers an area greater than that of the slab 4 and therefore extends to a peripheral edge 43 ′ placed beyond the lateral side 41 of the slab 4.

We can then place on the slab 4, a set of prefabricated panels 1 which are produced in the manner indicated above and are juxtaposed so as to form the side wall 10 of the tank.

As shown in FIG. 4, which is a detail view, in horizontal section, of the joint between two adjacent panels 1a, 1b, the protruding parts 33a, 33b of the sealing sheets 3a, 3b are applied one on the other in the joint plane (P), between the corresponding lateral sides 23a, 23b of the two panels 1a, 1b and the straight external edges 35'a, 35'b of the two sealing sheets extend l 'next to each other. If the sealing sheets 3a, 3b are made of metal, in particular stainless steel, it is therefore possible to produce a weld bead 36 along the junction between the outer edges 35'a, 35'b of the two sheets sealing 3a, 3b and thus, sealing the wall against the pressure applied to the internal faces 22a, 22b of the two panels by the fluid contained in the reservoir.

A sealed connection between the edges 33, 33 ′ of the panels can also be produced by crimping.

On the other hand, each prefabricated panel 1 rests, by its lower side 24, along the side of the slab 4. The folded extension 34 of the sealing sheet 3 is applied to the sealing sheet 42 covering the bottom 4 and protrudes beyond the lateral side 41 thereof by an overhanging part 37 bounded by a rectilinear external edge 37 'which extends along the peripheral edge 43 of the sealing sheet 42 and can be welded thereto by a weld bead 38.

With this arrangement, as shown in the perspective view of Figure 6, the sealing sheets 3 of each panel 1 are tightly connected, respectively to each other by the weld beads 36 and with the sealing sheet 42 of the bottom 4 by the peripheral weld bead 38. These weld beads are capable of withstanding the pressure of the fluid contained in the capacity limited by the side wall 10 and which can infiltrate between the parts 33a, 33b of the sealing sheets which are applied one on the other. This infiltration can, moreover, be limited by placing a sealant, for example with silicone, between the facing faces 33a, 33b of the two panels 1a, 1b.

In a preferred embodiment, the lateral sides 33, 33 ′ of the box 3 and, optionally the lower side 34 are reinforced by an excess thickness of metal or by a strip 39 interposed between the outer sheet 33 and the side 23 of the element made of concrete 2, as shown in FIG. 4. This strip 39 can moreover be bent so as to cover the rounded edge of connection with the internal face 21. This increases the rigidity of the panel 1 while avoiding the risk of buckling during demolding and transport, which guarantees the application one on the other of the edges to be welded 35'a, 35'b and the maintenance in the time of the weld bead 36, 38. After the assembly of all the panels forming the side wall 10, the excavation (A) is filled, around the tank, by an embankment (B) which opposes the separation panels under water pressure, after filling the tank. If the prefabricated panels are flat, the tank has a square or rectangular section. But it is also possible, as shown in FIG. 12, to make curved panels which allow a continuous curved wall to be produced. If the water level is not too high, a properly embankment can be sufficient to ensure resistance to the push of water by avoiding the spacing of the panels. However, it is preferable to make a reinforced concrete chaining 52 at the lower part of the tank to secure the bases of the panels together and with the slab 42. Such chaining 52 can be poured in place after the production of the weld beads 38 and 36.

On the other hand, it is possible, for safety, to join together the panels at their upper part, above the maximum water level.

Indeed, as shown in Figure 6, the resistant element 2 of each panel 1 can be extended by an upper part 5 forming a beam, in which can be formed, for example, ducts for the passage of one or more bars prestressing 51.

After the assembly of all of the panels, the bars 51 can be passed through the aligned sheaths and tensioned to ensure the assembly of the assembly, at least at the top of the panels.

This produces a chaining 5 which can form a base for a cover 1 1 for closing the tank.

It is also possible to produce a joining belt, at an intermediate level, for example as shown diagrammatically in FIG. 5.

Each wall element 2 is then provided, on its external face 21, with a projecting part in the form of a beam 53 which extends outwards, beyond the external edges 35 of the folded parts of the sealing sheet. The projecting parts 53, which are placed at the same level, are in the extension of one another when the panels 1 are put in place on the slab 4 and are connected together so as to form a belt surrounding the whole of the wall. One or more prestressing bars 54 passing in aligned sheaths, formed in the projecting parts 53 and passing outside the weld beads 36, make it possible to ensure the joining of the panels and to avoid their separation under the thrust of the water in the tank.

The invention thus makes it possible to produce, in a simple and rapid manner, a reservoir whose shape, height and capacity can be determined as required. In fact, it is possible to have molds readily adaptable to the desired dimensions in the factory and quickly produce the number of panels required, these having a width corresponding to the road gauge, which makes it possible to transport them stacked on a simple trailer. We can, however, vary the width of some panels to give the tank the desired dimensions.

However, it is also possible to produce in advance a sufficient number of prefabricated panels having different heights.

Depending on the dimensions of the tank to be made, we can then choose from stock the number of panels necessary to make the wall and deliver them quickly to the site. Certain panels may have a particular shape and, during molding, provision may be made therein or incorporation of accessory members, for example for the connection of supply and discharge pipes. After digging the excavation to make the seat surface, pour the concrete slab 4 and cover it with the sealing sheet 42, which can advantageously be made up of metal strips unrolled side by side on slab 4 and welded or crimped edge to edge.

By means of a simple crane, all the juxtaposed panels are then placed on the slab and the welds are made between the outer edges of the sealing sheets, as well as the fixing of the securing belts. The excavation can then be backfilled.

Due to the fact that all the welds are made outside the tank, it is possible to avoid interventions inside the tank and consequently the risks of deterioration of the sealing sheets.

On the other hand, the overflow outside of the overflowing parts 35, 37, 43 of the sealing sheets makes it possible to ensure permanent contact with the earth backfilled around the tank and, thus, the grounding of the latter. ci for cathodic protection.

In addition, it is possible to electrically connect all the welds to an earth connection.

Furthermore, the fact that the prefabricated panels 1 are only interconnected by the welds 35 and the securing belts 5, 53, the wall retains a relative flexibility and easily collects thermal variations, the folded parts 33a, 33b of the sheets sealing welded by their outer edges 35 forming bellows serving as expansion joints.

Of course, the invention is not limited to the single embodiment which has just been described by way of example and which can be the subject of variants using equivalent means to fulfill the same functions, without departing from the scope of protection defined by the claims.

For example, to secure the panels at their base, they could be embedded in the slab 4, as shown in Figure 9. The slab 4 is then provided, around its entire periphery, with a groove device in which engage the base of each panel 1 or a simple rib forming a tenon. In this case, it is not necessary to make a lower belt, the thrust of the fluid being collected by the groove. The waterproof sheet 42 which covers the slab 4 can be shaped so as to cover the bottom of the groove 44, as well as the folded part 34 of the sheet 3 covering each panel, the outer edges 37 and 43 being welded together as before . It is advantageous to weld together the projecting parts 33, 33 'and 34 of the sealing sheet covering each panel 1 to produce a sort of sealed box, but one could also use a continuous sheet simply folded in the corners. Indeed, since the resistance to the stresses applied is provided by the wall element 2, the sealing sheet 3 can be very thin and can therefore be folded easily.

Furthermore, it is advantageous to reduce the weld length, to use a sheet 3 folded over the sides of the wall element 2. But one could also use a sheet 3 of the same dimensions as the inner face of the panel and welded edge to edge with metal strips covering each side 23, 24 of the element 2. On the other hand, in the embodiment which has just been described, the panels 1 have the shape of a rectangular slab, particularly simple to achieve. However, this form can be modified while retaining the advantages of the invention. In Figures 8, 9 and 1 0 for example, there is shown a reservoir in which each prefabricated panel 1 has an enlarged base 6 which allows the panel to stand straight by itself, and can advantageously engage in a groove 44 of corresponding width, formed around the periphery of the slab 4. The latter is covered with a sealing sheet 42 which, because of its thinness, can be shaped so as to cover the bottom of the groove 44, emerging from the latter by a raised part 45 Likewise, the sealing sheet 3 which covers the internal face of the panel is folded over the underside of the base 6 and can come out on the outside so as to be welded with the part 45 of the sealing sheet 42. covering the slab 4. If necessary, the prefabricated panels 1 could also be provided on their lateral sides, of conjugate parts, respectively in hollow and projecting, making it possible to fit one into the other two adjacent panels, the sealing sheet 3 being shaped so as to follow the profile of the socket.

Some panels may also have a particular shape. For example, the side wall preferably includes, at each angle, a square panel 12 which improves the rigidity of the assembly and facilitates the installation of the flat panels.

The upper belt can also consist of elongated pieces 55 with a U-section, which cover the upper part of the panels 1.

Advantageously, each U-shaped piece 55 has a length equal to the width of a panel 1, but is offset by half a step so as to cover two adjacent panels, as shown in FIG. 8.

On the other hand, the U-shaped pieces 55 can be secured to the panels 1 by sealed studs 56. In the corners, it is also possible to use square pieces 55 ′ which cover the corner panels 12 of the wall.

Preferably, at each angle, the internal face 22 ′ of the square part 12 is rounded so as to ensure a perfect application of the sealing sheet 3 which covers the part 12.

Furthermore, each panel 1 can be provided with a rib 13 which increases the rigidity of the panel and makes it possible to avoid the installation of an intermediate belt, the panels being held simply at their upper part by the U-shaped pieces 55 and at their lower part by the groove 44 of the slab 4.

It is easier to produce flat panels and, therefore, rectangular section tanks, but one could also, as shown in Figure 12, use curved panels to achieve a curved wall.

On the other hand, if the sides 23, 23 'of each panel 1 must be straight to allow the folding of the sealing sheet 3, they are not necessarily parallel.

In fact, in the case of FIG. 12 where a curved wall is produced, each panel could have a general trapezoidal shape, with converging lateral sides so as to produce a conical wall.

As indicated, the fact that the sealing sheet covering each panel can be very thin, it is possible to produce it in stainless steel, the increase in the price of the material being largely offset by the advantages provided. , in particular the reduction of maintenance costs and better resistance over time.

For this reason, a reservoir according to the invention will be particularly suitable for containing drinking water or other food products, for example milk.

However, since stainless steel has excellent corrosion resistance and is easy to clean, the invention may find multiple applications, for example, for the production of tanks containing a hydrocarbon or a harmful or corrosive product such as slurry or industrial waste, in order to avoid pollution of the water table.

Of course, the quality of the steel will then have to be adapted to the chemical composition of the product to be stored.

However, it is also possible to produce the sealing sheet for each panel from an ordinary metal provided with an adequate coating or from another material, for example a composite or synthetic product. Similarly, if it is advantageous to connect the outer edges of the sealing sheets 3 to each other by welding or crimping, a sealed connection could also be obtained by simple bonding of the folded parts 33, 33 ′ applied one to the other.

The reference signs, inserted after the technical characteristics mentioned in the claims, have the sole purpose of facilitating the understanding of the latter and in no way limit their scope.

Claims

1. Tank for a fluid product, having a bottom (4) and a resistant side wall (10) consisting of prefabricated panels juxtaposed (1) and covered, on an internal face, by a sealing sheet (3), characterized by the fact that each prefabricated panel (1) comprises a wall element (2) having a thickness sufficient to withstand the pressure of the fluid, with two lateral sides (23, 23 '), an upper side (25) and a lower side (24 ) and covered, on an internal face (22), with a continuous sealing sheet (3) extended by three parts (33, 33 ', 34) respectively covering the lateral sides (23, 23') and the lower side (24) of the wall element (2) and each extending over a length greater than the thickness of the element (2) so as to protrude outside the wall (10) by an overhanging part (35, 37), that said panels (1) are applied one against the other by their lateral sides ow. (23, 23 ') and rest, by their lower side (24) on a slab (4) constituting the bottom of the tank and covered with a sealing sheet (42) having a peripheral projecting part (43) extending outside the wall (1) placed on the slab (4), and that the adjacent projecting parts of the sealing sheets (3, 42) covering all of the panels (1) and the bottom (4) are interconnected so as to limit a sealed reservoir, the lateral projecting parts (35a) of the sealing sheet (3a) of each panel (1a) being sealingly connected with the lateral projecting parts (35b) of the adjacent panels (1 b) and the lower projecting part (37) being connected with the peripheral part (43) of the sealing sheet (42) covering the bottom (4) of the tank.

2. Tank according to claim 1 characterized in that the sealing sheet (3, 42) covering each panel (1) and the bottom (4) is made of a metal suitable for the fluid (E) and that the projecting parts (35, 37, 43) of the sheets (3, 42) of the panels (1) of the wall (10) and of the bottom (4) are interconnected by welding or crimping their edges external (35 ', 37', 43 ').

3. Tank according to claim 2, characterized in that the sealing sheet (3, 42) covering each panel (1) and the bottom (4) is made of stainless steel.

4. Tank according to one of claims 1, 2, 3, characterized in that the parts (33, 34) of the sealing sheets (3) covering the panels (1) are interconnected and with the sheet (42 ) covering the bottom, by gluing.

5. Tank according to one of the preceding claims, characterized in that the projecting parts (35, 37, 43) of the sealing sheets (3, 42) projecting outside the wall (10) are electrically connected to a mass so as to provide cathodic protection.

6. Tank according to one of the preceding claims, characterized in that it comprises means (5) for connection between the adjacent panels (1) making it possible to resist the pressure of the fluid (E) contained in the tank.

7. Tank according to claim 6, the wall (10) of which extends in height up to a higher level, characterized in that the means (5) of connection between adjacent panels are placed below the upper level of the wall (10) and comprise at least one connecting member (53, 54) forming a belt externally surrounding all of the panels (1) at a distance from the internal face (22) thereof greater than the distance (a ) between said inner face (22) and the outer edges (35 ') of the sealing sheets (3).

8. Tank according to claim 7, characterized in that each resistant element (2) of a panel (1) is provided with a part (53) projecting outwardly from the external face ( 21) of said element (2), and that the parties projecting (53) adjacent panels (1a, 1b) are placed in the extension of one another and are interconnected by at least one elongated connecting member (54) opposing, in service, efforts tending to separate one from the other two adjacent panels (1 a, 1 b).

9. Tank according to claim 8 characterized in that the connecting member (54) between the adjacent panels (1) comprises at least one cable or a prestressing bar bearing on the projecting parts (53) of the panels (1 ) and subjected to a tensile force for clamping said panels (1) therebetween.

10. Tank according to claim 6, consisting of panels extending in height at least up to a maximum level of the reserve capacity, characterized in that the means (5) of connection between the panels form a belt (55) extending above said maximum level and provided with means (56) for securing with each of the panels (1).

1 1. Tank according to claim 10, characterized in that the fastening belt (5) consists of beam elements (55) arranged one after the other, along the upper part of the wall (10 ), each element (55) extending on either side of at least one joint plane between two adjacent panels (1) and being secured to said panels (1).

12. Tank according to one of claims 10 and 1 1, characterized in that the joining belt consists of at least one elongated part (55) having, in cross section, a U-shaped profile and covering the upper part of the panels (1).

13. Tank according to one of the preceding claims, characterized in that the slab (4) is provided, over its entire periphery, with a groove (44) in which fits at least one projecting part (27) on the lower side (24) of each panel (1).

14. Tank according to claim 13, characterized in that the lower side (24) of each panel (1) is widened so as to form a stabilizing foot (6) which fits into a groove (44) of corresponding width , formed on the periphery of the slab (4) constituting the bottom of the tank.

15. Tank according to one of claims 13, 14, characterized in that the sealing sheet (42) covering the slab (4) is shaped according to the hollow profile of the groove (44) so as to emerge from that -this extending to an external edge (43 ') placed substantially at the level of the upper face of the slab (4) and that the lower side (34) of the sheet (3) covering each wall element ( 2) goes up along the external face (21) thereof and extends to an external edge (37 ') which, after fitting the panel (1), is located substantially at the level of the upper face of the slab (4), so as to be connected to the outer edge (43 ') of the sheet (42) covering the latter.

16. Tank according to one of the preceding claims, characterized in that, the side wall (10) of the tank having a polygonal shape comprising several planar faces which are angularly connected, the wall (10) comprises, at each angle, a panel bent (12) having two branches which are each connected to a flat panel 1 constituting at least part of the flat face of the wall.

17. Method of constructing a tank having a bottom (4) and a side wall (10), characterized in that the bottom is first produced by pouring a concrete slab (4) on which one applies a continuous sealing sheet (42) having a peripheral projecting part (43), which is placed on the periphery of this slab, a set of juxtaposed prefabricated panels (1), forming a wall (10) and each comprising a resistant element (2) covered a sealing sheet (3) extended by three parts (33, 34) respectively covering the two lateral sides (23) and the lower side (24) of the element (2) and each extending over a length greater than the thickness of said side so as to protrude outside the wall (10) by an overhanging part (35, 37) and a tight connection is made, on the one hand, at the bottom, between the peripheral projecting part (43) of the sheet (42) covering the slab (4) and the lower projecting part (37) of the sheet (3) folded over the lower side (24) of each panel (1) and, on the other hand, in each joint plane between two panels (1a, 1b), between the projecting parts (35a, 35b) of the sheets (3a, 3b) folded over the adjacent lateral sides (23a, 23b) of said panels (1 a, 1 b).

18. The method of claim 17, characterized in that the tank is buried, at least in part in a pit (A) and that, after the completion of the bottom (4) and the wall (10) and the welding of outer edges (35 ', 37', 43 ') of the sealing sheets (3), an embankment (B) is placed around the side wall (10) which secures the juxtaposed panels (1) .

19. The method of claim 18, characterized in that the projecting parts (35, 37) of the sealing sheets (3, 42) covering the panels (1) of the wall (10) and the bottom (4) are buried, at least at their lower part, in the embankment (B) produced around the wall (10) and which constitutes an electrical mass ensuring cathodic protection of the sealing sheet.

20. Method according to one of claims 17 to 19, characterized in that there is provided a securing belt (5), at least at the upper part of the panels (1), above the maximum level of the product (E) contained in the tank.