Process for producing hollow structures such as ducts, silos, or shelters, and structures obtained by this process

The present invention relates to a method for making hollow structures, having the shape of a cylinder resting on the ground by one of its generatrices or a similar curved shape.

Such structures are typically ducts of large cross section, for example beyond the traditional industrial production of the order of 2 m²Buried or not, for the supply of water or other fluid under pressure or without pressure, or to passages of cables and / or other conduits or the movement and parking of vehicles people.

The invention is also applicable to the obtaining of similar forms of structures but relatively short, usable commes cellars, anti-atomic shelters or silos or other.

Various techniques are used for the establishment of conduits for the water supply, petroleum transport, cable glands, or other conduits, etc ...

The most common technique involves the use of pipe sections with circular section, which are put together and assembled by various methods. This technique has drawbacks which increase with the diameter of the pipe, even if they reduce the length of the sections: manufacturing, transportation, handling and installation. Anyway, in addition to manufacturing problems, congestion problems arise as soon as you approach an outside diameter of 2.50 m, which corresponds to the normal limit of road templates. For flow rates, it is necessary to provide several lines in parallel, which is an expensive solution, or to contruire the pipe on site, according to the techniques of masonry constructions or works also expensive galleries and long delays manufacturing or achievement.

It is also known from FR 733 098 or US Patent 2,400,071, techniques of assembling a large number of small elements each provided with transverse flanges for assembly with adjacent components. The large number of elements to give them requires an identical shape, resulting in the adoption of a circular section, and in this case, the resistance to stress requires that the junctions are alternated in the longitudinal direction. It was well planned in US Patent 2,400,071 to consider some of the stresses acting on the wall, and use for the upper section of a tunnel elements to lower resistance for the lower part, but on the one hand an alternate assembly joints of different characteristics elements has an uncertain strength, and secondly it introduces an additional complication in the assembly by mounting a large number of small elements, so that such an arrangement is difficult to enforce so perfect by unskilled personnel.

On the other hand, if the circular duct is best suited to the case of high internal pressures and easier to obtain when manufactures sections corresponding to the entire section of the duct, it may, however, have drawbacks . Indeed, creates a circular duct in the floor which supports its weight, the stresses which have a high peak in its central region. It follows that if the soil is loose, significant differential settlements may occur after installation.

In addition, the circular form is poorly suited for use when space is crowded, as is often the case in urban areas. Finally, the weight of the conduit is too high compared; indeed, material is, in the case of unit sections each covering the entire section, evenly distributed over the entire periphery so that the constraints are not.

To solve these various problems, it has been proposed to construct tubular conduits having a cross section flattened at the base by on-site assembly of longitudinal elements prepared in advance and each corresponding to a portion of the cross section of the conduit.

DE-A-2157191 describes, for example, a cylindrical pipe and may have a flattened base made from assembled longitudinal elements. Such elements which are made of corrugated iron and are, in fact, a simple formwork, do not, for large sections, a trèsfai- ble resistance to external constraints, which makes uncertain the shape retention of the section and sealing. Furthermore, the corrugations increase the strength of the conduit to fluid flow.

To improve the flow, document FR-A-1027788, which concerns the implementation of a flattened base to underground gallery proposes making the inner wall by assembling prefabricated reinforced concrete comprising, in cross section, a raft element forming a flat bottom, two side jambs and an arch element.

Such a process is intended only to build the coating of a gallery built in tunnels in the ground up and is not applicable to the realization of a structure simply buried under an embankment.

Indeed, in the case of tunnel described in document FR-A-1027788, the coating elements are placed at progressively excavation of the excavation by pressing the veneer already laid and they are then sealed by injecting cement between the elements and the rock wall. For this, the laterally elements fit into each other and therefore must be laid with great accuracy. Is used, however, for this purpose, a special machine circulating in the gallery.

It is this machine that keeps upright each sidewall of a new section to its insertion in the corresponding sidewall of the last section already asked and if there is a widening at the base is to allow connection round with the raft element. Such an extension, which engages itself in a groove of the floor, would not be sufficient to ensure, with the necessary security, maintenance of the vertical sidewall.

We can not therefore consider using such a method for producing a pipe buried under fill, the wall must stand alone to requests from the field and applied loads. In addition, we must also consider, in this case, differential settlements that may occur resulting in a shift of the adjacent elements. Such a risk is negligible in the case of a tunnel made underground in a necessarily stable ground and nothing is specifically intended to remedy in FR-A-1027788.

It was also proposed, in FR 1,008,441, to realize the wall of an underground gallery with four elements, respectively a base, two piers and a canopy. To realize, with the same base, several sections are used vault elements across different widths and the sidewalls engage with clearance in grooves provided on the base so as to take various inclinations to adapt to the width of the vault. The sidewalls must be calibrated to the desired orientation during the construction to allow the construction of the vault, and the assembly is blocked by casting a mortar into the grooves.

Such a construction method therefore requires that the piers are wedged, before sealing, or on the rock wall or on scaffolding. In addition, it is not suitable for producing pipes of very large section allowing, for example, the vehicle traffic.

True, the document FR 2223513 provides to make small tunnels including, in cross section, two piers shaped boxes, provided at their lower part of a broader basis for their rights and to stand on their upper part, each of a console on which a planar slab, a concrete slab being simply poured between the bases of the sidewalls which serve as formwork.

Such a method is intended only for making galleries rectangular section and, in particular, one could consider replacing by circular arch-shaped elements the upper elements in form of planar slab resting on the upper brackets.

However, unless overly increase the reinforcement and the thickness of the planar sheet, the scope thereof, and therefore the width of the tunnel, thus remain limited.

In addition, adjacent elements are simply placed on top of each other and there is provided no attachment to resist differential settlements.

Thus, it appears that there is an unsolved need for a method that allows the obtaining of hollow structures, cylindrical, resting on the ground, to form flattened section at the base, in particular of large section ducts, or similar structures, this method to achieve structures with high mechanical strength and can withstand differential settlement, with the cost of production, transportation and implementation significantly reduced compared to current techniques.

The present invention therefore applies, in general, to the production of a tubular hollow structure of large cross-section, buried under an embankment, and formed by assembling on site prefabricated elements prepared in advance and being connected to one another along longitudinal joints and transverse joints parallel and perpendicular respectively to the axis of the structure, the latter including, in cross section, two side elements positioned on either side of a raft and on which rests an upper element, each side element having a substantially vertical side wall and resting on the ground via a planar underside stabilizer member allowing said member to stand upright by itself .

According to the invention, the top elements each have the shape of a curved arch resting on the upper edges of the lateral side walls of the elements and connecting tangentially to the latter so as to give the structure a substantially cylindrically shaped section flattened base, said structure consisting of tubular sections placed end to end with the prefabricated elements are positioned so that the longitudinal joints between elements of a same section are in the extension of each other on either side of each transverse joint between two successive sections and the stabilizing elements are provided for enabling the side elements to stand upright by themselves supporting the roof elements such that, for the realization of the structure, the prefabricated elements may of first be placed in a manner permitting limited relative displacement of the adjacent elements and, when the surrounding terrains and the whole structure have stabilized, a definitive and rigid assembly of the elements is formed at least along two longitudinal joints, thus constituting the said structure, in its final form, a homogeneous piece assembly.

The invention also covers a particularly rapid and economic method of making such a structure.

Indeed, according to the invention to realize each tubular section of the structure:<ul><li>- First we put on the floor a raft element or is realized raft of reinforced concrete cast in place,</li><li>- It poses both sides of the raft of side elements each being placed directly on the floor and standing straight without scaffolding with its stabilizing element,</li><li>- An upper element is placed on the side elements,</li><li>- Is connected elements to each other in a manner permitting limited relative movements between adjacent elements is allowed to surrounding land and the entire structure is stabilized and it then carries out the final assembly and rigid elements at least along two longitudinal joints so that, in its final form, the structure constitutes a homogeneous and integral whole.</li></ul>

In a preferred embodiment, at least the side elements and the raft are made of concrete and are left between the lateral sides of the raft and the base of the side elements an interval in which extend the armatures having the end portions of reinforcement elements which was allowed to exceed during molding and said reinforcements are embedded in a cast sealing mortar in said interval, using suitable shuttering elements to realize the definitive and rigid assembly of the elements along the longitudinal joints lower.

The invention presents a first advantage over the prior art, namely that transport is easy. If one assumes indeed that the maximum allowable dimension of 2.5 meters, current technology only allows the unit transport outer diameter sections at most equal to 2.5 m. If the elements of the invention each correspond to a quarter of the channel section, the latter may have, once completed a diameter of about 3.5 m, a dual surface section, and if the elements correspond to a sixth section, it may have once finished diameter of 4.4 m is about a triple-sectional area. Moreover, for the same height of 2.5 m we will have, in the same volume, a considerable number of unit elements, stacked on top of each other so well. the same transport vehicle will be used to its maximum payload. In contrast, the total length of joints to be made, by welding or other means, is of course increased. It must be observed that it is normally rectilinear joints that are much easier to obtain or perform as circular joints, and the number of these can be reduced to the contrary due to the greater length of unit elements, allowed by their unit weight more reduced.

Another advantage of the invention results from the non-circular shape of the structure, it was reported above disadvantages of a circular shape.

In addition, thanks to the shape of flattened section at the base, we get a considerable improvement in the distribution of stresses generated in the underlying soil, and the movements of the latter can be reduced dramatically. Another advantage of such forms is equal to a lower section height, hence reducing the search costs (earthworks, shields, drawdown of water table, etc ...). On the other hand, when the consistency of the soil required bearer (aquifer particular) can be incorporated within a conduit ballast obtained by means of masses of metal or concrete mistletoe are hooked by an appropriate bolting, you raft said conduit. Of course, the mass of les- taqe is calculated based on data specific to the site concerned and each of the weight members can also be prefabricated. Can also anchor the leads to the ground by the same method of bolting which is made easier from the inside by the flattened shape of the raft.

On the other hand, the preliminary computation of the stresses to which are subject the pipe elements, and using the result of this calculation to determine the thickness of each element, the variation of this thickness from one point to the other of the section, the material of which is made each item and location of longitudinal joints, offer important advantages:<ul><li>It is common, in fact, that the upper part of a conduit has a protective function and is subject to limited stresses. On the other hand, the weight of the transported fluid, when it is water or another liquid in free flow, obviously more at the bottom than at the top. In addition the seal obtained with assembly joints allows the conduit to withstand internal pressures and, therefore, to be used penstock. Note also that, in its final form, the duct forming a homogeneous and unitary whole, it will not be necessary to make stops to change direction, driven generators longitudinales.La possibility of adapting the thickness and material of element allows significant savings on the cost and transportation.</li></ul>

As mentioned above, the various elements can be of different thicknesses according to the calculation result of contraintes.lls can also be made with different materials, provided however that, if appropriate, the necessary precautions have been taken to prevent corrosion effect of electrochemical couples.

Preferred materials include, for their low price and their facilities for obtaining and assembly by welding and / or other means, ductile iron, although other materials can be envisaged alone or in combination, such as steel, aluminum alloys, other metals, reinforced plastics or non fiber-reinforced concrete or non-prestressed or non.Dans these last two cases, it is obvious that the welds which have been spoke up more be replaced by appropriate links.

In the case where duct elements are produced by monoblock molding or by continuous profiling section, including parfilage, materials such as ductile iron, steel, reinforced concrete, these resins, etc ...., it advantageously uses a mold or tool whose cross section is shaped to reproduce by acting on the inner surface of the conduit element, the aforementioned variations of optimum profile and likewise the transverse variation in thickness.

The directional changes are achieved by prefabricated curved or canted, especially calculated and adapted to the geometry imposed.

The making of a conduit according to the invention, that is to say by elements that correspond to only a part of the section but can yes, by compensation, be of considerable length, raises specific problems when assembly; these problems could be solved by the next assembly process, which is therefore in close contact with the main object of the invention. According to this method, one proceeds to the initial assembly of the elements connecting them both longitudinally and transversely by means allowing limited relative movement of adjacent elements and by interposing between them a flexible material seal, and one proceeds then the final and rigid connection between the elements when the surrounding land and the entire duct is stabilized. Preferably, the initial assembly of the elements to each other is made by means of bolts passing through at least one of a hole extended accordingly.

However, other joining methods may be more advantageous, particularly in joints where strong constraints impose significant wall thickness. In these cases, it is preferred to operate according to one or more of the following modalities.<ul><li>- To make the longitudinal joint and optionally the transverse junction of the conduit elements, forming recessed portions or projecting placed in the zones of corresponding edges and engageable by conjugation of shapes and / or forces to create longitudinal joints and necessary cross;</li><li>- For creating longitudinal joints, forming a rib on each of the edges of two elements to be joined and are distributed along the two ribs thus formed locking means;</li><li>- The locking means are rigid or spring clips;</li><li>- The brackets are attached using rigid or elastic parts-fitted between the inner surface of the stirrup and the flank of the corresponding rib or by elastic deformation of the stirrups themselves;</li><li>- Gaskets, a profile section corresponding to the edges of longitudinal and transverse joints, are interposed between said edges and tight clamp is provided with said stirrups or with necklaces, hoops, prestressing cables or other means;</li><li>- In cases where the elements are formed from weldable or sealable materials, the longitudinal and transverse joints are made by adding material welding or corresponding sealing.</li></ul>

According to the invention, to facilitate the establishment and stabilization of the pipe, there are provided stabilizing elements having a triangular longitudinal section, on the sides of the bottom face of the pipe. These elements have a horizontal flat face which is approximately at the bottom of the pipe, a planar face approximately vertical or inclined, and a face that matches that of the pipe. These stabilizing elements are preferably discontinuous and implanted from place to place along the pipe to prevent the lower member to tilt about its longitudinal axis after its establishment.

These stabilizing members may be attached by bolting, welding or the structural element of the pipe. In the case where it is obtained by molding (concrete) can also be integral with it.

Further interest in the stabilization of the whole pipe, the stabilizing elements are advantageous in the case where the pipe is formed of elements some of which constitute the bottom and other side walls with a generally vertical orientation: by providing that the elements stabilizers are set in advance on the side wall elements, or are integral with these elements, they become able to stand upright resting on the ground, which facilitates the obtaining of their junction with the background elements placed first. Then, the establishment of the elements forming the above can be performed by placing them on the side wall elements.

In the case where the section of the hollow structure, is relatively small, for example a conduit 1 4 m² about, one can provide that the section of the conduit estformée by two components only one of which corresponds to the lower part and sides of the conduit and the other forms a cover. These elements, or at least part of them can be made of concrete or other cast material.

According to another method of obtaining usable seals, in the case where the elements are made of concrete or other cast material, is provided on the edges of the longitudinal elements, angle weldable or bondable material on which is fixed, after establishment and, preferably after stabilization, flat parts for sealing a material compatible with the angle profiles.

In some cases, particularly when it comes to transport or store hazardous fluids, or for the construction of fallout shelters, should get a perfect seal even in case of landslides or explosion nearby, and if the elements are constructed of concrete or other material that may crack or lose its tightness in another way, it is advantageously provided a waterproof coating or inner liner, integral or not the structural elements.

In some cases, this coating may be a lost formwork section for the elements of the structure.Si the coating is tin or other metal or non-metallic weldable or bondable material, of the flat parts ty pe indicated above may be welded or glued joints of this coating, or can be welded directly or paste coating portions together at points.

If the structure, duct or shelter, is formed of concrete elements, it provides the crushing strength, while a lining metal sheet or not or plastic welded, adhered or applied by any coating provides absolute tightness contamination or seepage, radioactive or other, even if the movements of the land or explosion due to the distorted structure.

The following examples are mostly related to conduits of large cross section, but estfacile to realize that what is said is true for silos, shelters or similar structures.

In the case of a prefabricated bomb shelter, is placed longitulinale wall elements, which may be constituted in the same way as the large section ducts, and the cover is closed at its ends by walls flat or curved cross. Preferably, gives away a substantially flat bottom, and the base or side members are provided with lateral stabilization elements are integrated during manufacture or subsequently added so as to prevent tilting of the shelter about its longitudinal axis.

Advantageously, there is provided a leakproof lining, particularly if the cover is constructed of concrete.

The shelter can be set up very quickly, because it is formed of separate elements that can be easily transported for assembly on site. It can be placed in an excavation, which is then recapped, or even, in some cases simply be placed on the floor. Note that the base flattened shape provides improved resistance to blast effects, compared to a brick shelter cylindrical or parallelepipedal.

The invention will now be described in more detail using exemplary embodiments, non-limiting, illustrated by the drawings in which:<ul><li>FIGS. 1 to 3 are schematic cross-sections of ducts according to the invention.</li><li>Fig. 4 is a partial section illustrating a method of assembly.</li><li>Fig. 5 is a schematic perspective view of a conduit in which the various sections are formed of longitudinal elements whose longitudinal and transverse seams joining are highlighted.</li><li>Fig. 6 shows an example of pipe elements with a gradual reduction of radial thickness toward the center.</li><li>Fig. 7 shows an example of pipe members having a gradual increase of cross-sectional thickness from left to right.</li><li>Fig. 8 is a cross section of a longitudinal joint showing a mode of joining rib and stirrups.</li><li>Fig. 9 shows an example of profile interlocking the corresponding edge of two pipe members to form a longitudinal or transverse seal.</li><li>Fig. 10 shows another example of the edge profiling of elements to form a longitudinal or transverse seal.</li><li>Fig. 11 shows yet another example edge profiling of elements to form a longitudinal or transverse seal.</li><li>Fig. 12 shows an embodiment of a transverse spigot joint which is sealed by a special profile annular seal which is compressed using a suitable strapping.</li><li>Fig. 13 is a cross section of the conduit of Figure 12, showing the strap of the seal.</li><li>Fig. 14 shows the establishment of a joint in the case of reinforced concrete elements.</li><li>Fig. 15 is a diagram illustrating the results of stress calculations.</li><li>Fig. 16 is a sectional view of a hollow structure section reinforced concrete corresponding to the calculation of Figure 16.</li><li>Fig. 17 shows another embodiment, especially suitable for conduits of small cross section.</li><li>Fig. 18 shows a method of obtaining the seal.</li><li>Fig. 19 shows a fastening of the joint.</li><li>Fig. 20 shows another method of production of the seal.</li></ul>

1 shows, in solid lines, the section of a pipe 1 obtained by the process of the invention, and for comparison by dashes, the section of a circular section 2 same duct. The conduit according to the invention is obtained by assembling five elements of same length.

Two basic elements 3 are substantially planar; two side 4 elements have a higher variable downward curvature than upwards; the profile is completed by an upper member 5, in section in a circular arc. The example shown is for guidance to a section of 10 m². The total height H is 2.40 m wide and 5.00 m L, compared with the corresponding diameter D of the circular duct, which is 3.57 m. The excavation necessary for the duct according to the invention is wider at the base than to the circular pipe, but it is shallowest; and in total, the volume to be excavated may be less and work more easy.

2 shows another form of conduit according to the invention, wherein the bottom elements 3a are slightly curved, and which comprises two upper elements 5aau instead of one.

Figure 3 shows yet another embodiment, mistletoe has the feature that the bottom part 3b forms a central cunette 6. It was expected that the culvert is in the middle of the element 3b and is slightly flared so that the elements are identical and stackable for transport, but of course other arrangements are possible. According to the conventional art, the addition of a culvert poses a virtually insoluble problem.

4 illustrates an example of the connection mode between two elements 4, 5 placed as elements 4a and 5a of FIG 2.

The element 4 is in a first stage provided with a connecting plate 7, fixed by a weld 8, which can be run in the factory or on site. This plate 7 has widened holes 9 which, during assembly, are in correspondence with enlarged holes 10 of the element 5. When mounting is interposed between the element 5 and the plate 7 a flexible seal 11 of elastomeric or the like, and then one proceeds to the junction with the aid of a screw 12 and a nut 13.

when the set of elements corresponding to the following section of the duct is mounted, slight relative movements of the elements 4 and 5 can occur, such as the level changes effect the bottom of the excavation. Slight movements can also be a consequence of the settlement of the underlying land. All these movements are made possible by the expansion of the holes 9 and 10. When these movements have stopped happening, we can proceed to the final junction elements by welding 14. The screw 12 and the nut 13 can further be deleted, and the holes 9 and 10 or only one of the two, can be closed by welding.

In Figure 5, there is shown in schematic perspective view a duct obtained by implementing the process according to the invention. This duct comprises longitudinal elements such as A1, B1, C1, etc ... for the first portion A'1, B'1, C'1, etc ... for the second segment, and so on; these elements are interconnected by longitudinal seams, JL1, JL2, JL3, JL4, etc ... and by transverse seals JT1, JT2, JT3, JT4, etc ...

It is interesting to give to the cross section of at least some of said elements of varying thickness to suit the stresses exerted at different points of the section of the element considered. Thus, it was demonstrated in Figures 6 and 7 cross sections of duct elements showing how to vary the thickness of matière.Cette feature is extremely important, both for the manufacture and for the transport and assembly of element since the amount of material and thus the weight and cost are defined in the most accurate manner possible, depending on the settings reacting the realization of the final pipe. If we consider the application of the invention to the construction of oil pipelines, aqueducts, etc ...., long lengths, it becomes easy for the influence of weight gain on the profitability finate execution of the work.

The duct elements according to the present invention can be made of different materials and be manufactured, in correspondence, by various methods. Thus it is possible to envisage the manufacture of elements such as A1, B1, C1, etc ... in a metal such as ductile iron, thy spheroidal graphite cast iron, steel, aluminum alloys etc ... for such materials, it is possible to apply various processes, for example the cast piece by piece, continuous casting, spinning, forging, differential rolling, etc ... All these methods allow to achieve a homogeneous from the recesses or projections to be used later, when assembling the elements, the establishment of longitudinal and transverse joints, as will be explained below.

It is also possible to achieve duct elements in other materials as metals, including reinforced concrete, plastics or resins reinforced or not with fibers, ect ..... In such conditions, the elements are made by molding to the flange of molds or forms, which also allow to obtain the projecting portions and the aforementioned hollow.

All implementation processes of materials defined above for achieving the duct elements according to the invention involve tooling, molds, molds, etc ..., which must consider the characteristics of the process of obtaining ducts according to the invention under the following conditions:<ul><li>- The inner surface of the manufactured pipe section must match the ideal profile section of the pipe, determined by calculation based on known parameters concertante installation type, the conditions of use of leads and intrinsic caractéristigues. By "ideal profile" means, in the heap of a conduit where the external conditions vary little, an average profile applicable to the conduct of a certain length,</li><li>- Each item must have the over-all dimensions for assembling with the other elements of the pipe and the different thicknesses of the elements must be calculated to allow them to withstand the stresses to which they are subject.</li></ul>

The final sealing is obtained by various means appropriate to each material used, it is created from within the conduitaprès definitive stabilization (compaction, compensating expansion, compacting, etc ...).

will now be described how to perform the assembly of the various elements to form a conduit, with reference to Figures 8 to 12 which show some embodiments of longitudinal joints and transverse joints. Ansi in cross section is shown in Figure 4 a longitudinal seal established between the two conduit elements A1 and B1. In this case there is provided, on either side of the points defined by the two surfaces 71,72 of the elements A1. B1. respective outer longitudinal ribs 73,74 extending along the entire length of the corresponding duct elements. These ribs may be formed during casting, spinning, rolling, or molding or corresponding elements they can also be reported by welding, in which case they can be discontinuous. These two ribs provide as shown in Figure 8, the simple and efficient attachment of a locking stirrup 79, with corners 76,77 which are fitted in position between the bracket and the corresponding rib by operating e.g. by hammering or other similar process.

For absorbing the reactions acting in a direction perpendicular to the sectional profile of the duct, it is appropriate to leave lateral boundary surfaces of the duct elements A1, B1, ... etc, shapes enabling them to absorb the stresses in the best way possible, taking into account all the parameters relating to the conditions of manufacturing and use of the duct, and also the material of which it consists. Thus, by way of non-limiting examples, given in Figures 8, 9 and 10 several profile templates of said side boundary surfaces of the duct elements. In Figure 8, the boundary surfaces 71 and 72 are inclined relative to the plane perpendicular to the profile of the section of the conduit. Such a profiling of the seal surfaces for example suitable when the static loads on the pipe are predominant.

In Figure 9, the two lateral boundary surfaces of the duct elements A1, B1, which are designated by 79 and 80, have corresponding rounded shapes so as to absorb the reactions acting in both directions in said plane perpendicular to the profile section.

In Figure 10, we represented boundary surfaces 82 and 83 which form steps for achieving a embottement.

Figures 11, there is shown the profiles 33 and 34 defining a recess 35 yes may be filled by a sealing material for example a casting resin.

It should be noted that all these forms of side surfaces of delimitation of conduit elements can be perfectly made by any of the above manufacturing processes. To establish a good seal, is provided in each case between the corresponding surfaces of the abovementioned longitudinal seals, coatings, sealants, gaskets or other sealing establishment of agents, including rubber, natural or synthetic, as shown in respectively 8 in Figure 8, in 81 in Figure 9 and 84 in Figure 10.

It should be noted in this regard that these seals provide a pressure seal.

In FIG 14, a longitudinal seal is shown which is established between two elements of conduitA1, B1 made of reinforced concrete. It has designated 20 and 21, the respective frames of the elements A1, B1. To realize the junction is allowed to exceed the armatures 20, 21 during molding of the elements and, once they have been set up in the positions provided on the place of installation of the duct, it interconnects the end portions projecting respective frames, as indicated at 22, then, using appropriate formwork elements such as 26, is cast a sealing mortar into the gap 21 to achieve the intended longitudinal seam.

In FIG 14, it was revealed in 24 and 25 of angular profiles and recessed elements A1 connecting edges B1. These profiles are intended firstly to facilitate sealing mortar hanging 23 and the other to complete the sealing of the joint, creating gaps for suppressing leakage paths located. Has been designated by 27 and 28 of the formwork of the holding members 26 which is fixed in position by nuts 29, 30.

In Figure 12, an embodiment is shown of a transverse joint between two duct sections respectively constituted by elements such as A1, ..., and elements such as A'1.,. etc ... It was designated by 15 and 16 the mitation deli surfaces of the transverse seal. In the example, there is provided a peripheral seal indicated generally by 17 and comprising firstly a mistletoe radial bead fits into the gap between the surfaces 15, 16 and secondly by a peripheral ring whose inner surfaces are applied against the outer surfaces of the respective pipe members, said ring having on its outer périphérigue surface of the raised portions 19, intended to be flattened by compression using a strap or necklace 18A, 18B, as shown in Figure 13 which is a cross section of the duct of Figure 12. in the example considered, given as non-limiting, the raised portions 19 may have a dovetail profile and comprise divisions in their slots to create a labyrinth type seal. Flattening the strapping is made in two parts 18A, 18B interconnected by turnbuckles 31, 32 are actuated mistletoe for final tightening.

It should be noted that although all the embodiments of joints between duct elements do not form involves bolting, such a process is not at all excluded and that it is possible to form or fixed on the elements of like portions of the rims and flanges mistletoe would then be assembled using bolts or similar bodies.

In some applications it is possible, within the scope of the invention, to adopt for the conduit a mixed structure, that is to say, use of a quarter of the elements formed of a first material, example of reinforced concrete, in a first portion of the conduit, for example in the lower part between the longitudinal seams and JL1 JL4 in Figure 5, and the other elements formed of a second material, for example a metal or a reinforced plastic or not fibers in the remaining part of the conduit. Such a composite structure may be recommended in a waterworks in open trench, that is to say without high loads on top of the duct, in a remote area where it pays to make the bottom in cast reinforced concrete and the upper part by thin elements, prefabricated in a factory and transported on site.

15 shows, in solid lines in the form of the neutral fiber of a duct section according to the invention (curve I) in indents (curve 11) the distribution of the bending moment corresponding to the vertical thrust of the ground and features altemés (curve 111) the distribution of the bending moment corresponding to the lateral earth pressure. The complete calculation also includes determining a number of similar curves, corresponding, for example, the internal pressure in the true weight of the pipe, etc .... The calculation then includes combining results each corresponding to a type constraint.

It is observed that the full profile section has four areas of "nodes", one located in the lower part of the pipe, the other towards its upper section.

Figure 16 shows the half-section of a duct formed of four elements made of reinforced concrete.

It is observed that the thickness (h_i, h₂) In areas that correspond to the strongest constraints of Figure 15, that is to say at the center of the base and on the sides is approximately 50% larger than the thickness h₃ the junctions sommet.Les JL1, JL2 between elements have been made in the areas of constraint nodes. In this figure the benchmark f_i refers to reinforcing bars embedded in the concrete of the elements prepared in advance and f₂ denotes the anchoring irons, which have been folded over each other before being embedded in the concrete during the construction of the structure.

17 shows an embodiment suitable for pipes of relatively small cross section: 1.5 to 4 m² about. In a simplification, the section of the pipe is divided into two elements that can be carried separately without special difficulties because of their small size. The lower member 40 is made of concrete, and produced by molding, comprising the base with a flat bottom and sides. in addition it is observed includes stabilizing elements 41, which form part of it, and allow its easy installation in a flat-bottom search. These stabilizing elements are volumes to generally triangular cross section, with a horizontal lower face, these stabilizing elements not extending over the entire length of the element 40 for the purpose of briskly. The top 42 of the driving element is simplest because it has the form of an upturned eaves, low curvature. It can be achieved either by molding or by extrusion. Where the lower member 40 is formed by extrusion, it is clear that the stabilizing members 41 are fixed subsequently, but before the establishment of the pipe, by screwing, welding or any suitable means.

Figure 16 shows in phantom a stabilizing element 41. This figure highlights another advantage of the stabilizing element in the case of a structure whose cross section is formed of more than two elements. One sees in effect that the A2-side member provided with the stabilizer 41 outer member can remain only in the final position. There is therefore no need to provide temporary support for the realization of JL2 junction with the base member A3.

Note also that in the case of a structure resting on the floor, the stabilizing element increases the resistance to lateral forces tending to overturn the structure, which is advantageous in the case of an anti-atomic shelter or otherwise, would be placed on the ground and exposed to blast effects.

18 shows an embodiment of seals in the case where the elements are on or weldable or bondable, for example of concrete:<ul><li>Each element A1, A2 relates to the edges of ledges 43 of weldable material or bondable, such as ferrous metal, in place during molding if the element is obtained in this manner. Flat elements 44 or other flat connecting elements weldable or bondable material on the brackets 42 are welded or glued thereon, optionally after soil stabilization.</li></ul>

19 shows another assembly of the structures according to the invention.

One of A1, elements comprises a threaded hole 45, which may be provided in an insert 46. The threaded bore is directed approximately perpendicular to the plane of the gasket. The other element A2 has a shoulder 47 with a hole 48 in which is inserted a screw 49 which screws into the hole 45 in passing with clearance through the hole 48.

Figure 20 shows another embodiment of joint sealing embodiment, in which the elements A1, A2 in concrete, are provided internally with a sealing coating 50 of sheet metal shuttering perdu.Un inner flat element 44 is then welded directly to the coating 50. a bracket, similar to that of Figure 18 may be provided on the other edge of the elements A1, A2.

It is observed that a number of provisions of assemblabe described above are used for setting up the conduit and did not intervene to contain alone in an essential way, the hydrostatic pressure in the case of use penstock, these hydrostatic pressures were partly offset by the surge in embankments.

To better secure the elements of a pipe, or other shelter and facilitate the achievement by points, one can possibly predict more prestressed cables forming strapping, cables or bars prestressed interconnecting adjacent longitudinal members in the direction the length of each other. Such cables or rods can interconnect each of at least two consecutive elements, for example, an element may be connected to the element which follows by a set of cables or rods, and to the element which precedes by a similar game , which allows to operate the prestressing progressively as the progress of the installation. One can also provide that each cable or prestressing bar connects three consecutive items or more.