EP0585959A1 - Method for realising an entrenched conduit - Google Patents

Abstract

The subject of the invention is a buried pipe consisting of a series of segments placed one after the other, and each including a lower part resting on a laying surface (A) and an upper part consisting of at least one element (2) forming a roof and resting on the lower part via longitudinal bearing members (7) (7') parallel to the longitudinal axis (0). According to the invention, the lower part of each section of the pipe (1) consists of two prefabricated bearing elements (30), each forming an isolated base (32), the said bearing elements (30) being placed one after another so as to form two longitudinal bearing members (7, 7') on which the lower side edges (71) of the upper elements (2) come to bear. The invention applies especially to the production of underground pipes of large cross-section. <IMAGE>

Description

The subject of the invention is a method of producing a buried conduit by assembling, on the site, along a longitudinal axis, a plurality of prefabricated elements and also covers the prefabricated elements and the manner in which they are presented.

There are different types of buried conduits produced by assembling prefabricated elements and made up in particular of tubular sections aligned end to end along a longitudinal axis. Each tubular section may consist, for example, of a single element of tubular section. In this case, the tubular sections are generally provided at their ends with parts, respectively, projecting and recessed, which fit into one another when the elements are installed and allow the latter to be joined.

For a large passage section, the circular section sections have very high weights and are difficult to handle, transport and set up.

This is why it has also been proposed to divide the wall of the duct into prefabricated elements, each tubular section being made up of a certain number of elements resting on each other so as to constitute a closed section. Often, elements of a single type are used, each covering an arc of a given length and therefore making it possible to produce sections of circular section. However, it has also been proposed to use prefabricated elements of different shapes making it possible to produce sections of non-circular cross section and, for example, having a flat bottom allowing better distribution of the applied load on the ground.

In particular, the applicant has already described such structures, for example in European patent EP 081.402 which shows different embodiments and, in particular, a duct comprising, in cross section, four elements, respectively a planar element forming a raft, two side elements placed on either side the raft and each provided with a base allowing them to stand straight on the ground and a curved arch element resting on the upper edges of the side elements.

In another embodiment which is the subject of patent EP 0188.487 by the same applicant, a duct has been described comprising, in cross section, only two elements, respectively a lower element forming a raft and an upper element in the form of a curved arch in an arc of a circle and resting, via its two parallel longitudinal edges, on support members formed along the two sides of the raft.

According to one of the characteristics described in patent EP 0188.487, the longitudinal support members formed on both sides of the raft consist of grooves with a curved hollow bottom in which engage the longitudinal edges of the arch element which each have a convex rounded profile of curvature slightly more marked than that of the groove so as to leave a slight clearance. Each longitudinal support thus presents a certain possibility of articulation around an axis parallel to the longitudinal axis of the duct, each element of arch can be deformed very slightly under the load transmitted by the terrain that surmounts it. This is transmitted to the two lateral sides of the raft, which is made up of a solid rectangular panel resting on the ground by means of a rigid bottom allowing good distribution. all the charges applied.

It appeared that such structures resist the loads applied in an active way by mobilizing, moreover, the surrounding grounds to which a part of the applied load is transmitted by lateral deformation of the upper element, the latter being thus unloaded with the key .

These features have led to extending the possibilities of applying such conduits.

The invention therefore relates, in general, to a buried conduit, for the passage of a roadway or a river, produced by assembly on the site, along a longitudinal axis, of a plurality of prefabricated elements forming adjacent sections, each comprising, in cross section with the axis, a lower part resting on a laying surface and an upper part made up of at least one arch element and resting on the lower part via 'longitudinal support members parallel to the longitudinal axis.

In accordance with the invention, the lower part of each section of the duct consists of two support elements produced in advance, each forming an insulated sole having, on a lower face, a seating surface and, on one side upper, a longitudinal support part for an upper element, said support elements being placed one after the other so that the aligned support parts form the two longitudinal support members on which the edges rest lower side of the upper elements, said support elements having dimensional and structural characteristics determined so as to be able to withstand the loads applied in service by the upper elements and to ensure a seating surface of sufficient width, taking into account said loads and the bearing capacity of the ground at this location.

In addition, the invention covers numerous variants which are the subject of the sub-claims and which will be described in detail in the description which follows, with reference to the accompanying drawings.

Figure 1 shows an embodiment of a known type of conduit.

Figure 2 shows, in cross section, a conduit according to the invention, buried under an embankment.

Figure 3 is a longitudinal section of the conduit of Figure 2 at its end opening into an embankment.

Figure 4 is a partial side view showing a particular embodiment of the longitudinal support between an upper element and a base element.

Figure 5 is a partial top view showing, in a particular embodiment, a transverse joint interlocking between two consecutive base elements.

Figure 6 and Figure 7 are detail views showing two embodiments of the connection between two consecutive support elements.

Figure 8 shows, by way of example, two series III, III ', of support elements.

Figure 9 is a cross-sectional view of another embodiment.

Figure 10 is a schematic perspective view of the conduit of Figure 9.

In Figure 1, there is shown, in cross section to the axis, an example of pipe section of the type described in patent EP 0188.487 and consisting of two types of elements, respectively an element of base 10 forming a raft placed on the ground and an upper element 2 in the form of a curved arch resting on the raft element 10. The elements 10 and 2 are produced by molding, normally in reinforced or prestressed concrete, or in concrete of fibers, but other moldable materials can be used.

The conduit 1 is placed in the bottom of a trench B which is open up to a leveled and compacted laying surface A placed at the desired level, the conduit being, after installation, covered with an embankment C. The conduit thus buried is therefore subject, on the one hand, to the load of the embankment which essentially depends on the height of the latter and, on the other hand, to operating charges applied, for example, on a carriageway D fitted on the embankment .

The basic element comprises a bottom 10 consisting of a solid reinforced concrete panel of rectangular shape provided, along its two lateral sides 11, with two longitudinal supports which, in the example shown, are constituted by grooves with curved bottom 72 placed substantially at the level of the upper face of the bottom 10.

The arch element 2 has a semicircular cylindrical shape, centered on a longitudinal axis O which can be placed either in the horizontal plane of the grooves 72, or at a height h above the upper face 13 of the raft 10. For example, in the embodiment of Figure 1, the arch element 2 is provided with two planar sides 21 tangent to the circular part 20 which make it possible to raise the axis O by the same height.

By retaining the semicircular shape of the arch, it is thus possible to vary the total height H of the duct by modifying the height of the flat parts 21 of the arch element 2.

Each end 22 of the upper arch element 2 is provided with a convex rounded edge 71 which engages in the corresponding concave groove 72 at the level of the upper face 12 of the base element 1. The rounded edge 71 a a slightly greater curvature than that of the groove 72 so as to provide a slight clearance allowing the lower parts 25 of the arch element to pivot very slightly on either side of the vertical plane P passing through the bottom of each groove 72. thus constitutes, on each lateral side, a support member 7 articulated around an axis parallel to the axis O of the conduit.

As a result, as described in patent EP 0188.487, the arch element 2 can deform very slightly thanks to its articulated supports 7, 7 ′, under the action of the loads applied and this results in a certain reduction of the constraints to the key, part of the load being taken up laterally by the embankment C.

Each articulated support 7 must however be held laterally. For this purpose, each groove 72 is limited by raised edges 14 which, in the case shown in FIG. 1, where the grooves are placed at the level of the upper face 13 of the raft, have a height not exceeding 5 cm, this which allows the raised edges 14 to be poured from the concrete without using a particular mold. The raft elements 13 can therefore be molded quickly and economically.

It is also possible, as described in patent EP 0188.487, to apply the edges 22 of the arch in the grooves 72 by means of tie rods 25 tensioned by bearing on parts 24 of the arch, a gasket being interposed between the edges 71 and the bottom of the grooves 72.

By varying the height h of the flat lower parts 21 of the arch element, it is possible to modify the total height H of the structure as well as the passage section S inside the duct.

But for the same width between supports, it is also possible to reduce the height H of the duct by giving the vault a lowered shape like a basket handle. Of course, in this case, the passage section S is also reduced. If a maximum height has to be respected, the width of the raft can be increased and, consequently, the distance between supports L so as to ensure a determined passage section.

In the embodiments described so far, the lower part consisted of prefabricated monoblock elements forming a continuous raft. It is possible, however, to replace each base element 10 with two spaced support elements 30 so as to constitute two support lines 3 separated by a free space.

Such an arrangement, which has been shown in FIGS. 2 and 3, could be useful, for example, for very large sections for which one-piece basic elements would become untransportable. Indeed, the support elements 30 form insulated soles whose width can be provided to provide a sufficient support surface. In particular, in the case of soils having good resistance, the width of the sole 32 could be reduced.

Such elements, which are identical and can be stacked easily, are lighter and less bulky than one-piece elements covering the entire width of the duct.

In the embodiment shown in the Figures 2 and 3, each upper element 20 has the shape of a curved arch resting on the support elements 30 by its lower lateral edges, the latter having a rounded convex profile and each fitting into a groove 31 in the form of concave trough formed on the upper face of each support element 30. Two longitudinal support members are thus produced with a certain possibility of articulation of the upper element 20 relative to the two support elements 30.

The replacement of a monobloc lower element by two separate support elements does not significantly change the maximum admissible load because it depends essentially on the resistance of the arch, the role of the raft being essentially to transmit to the ground the load applied to the arch and provide a downward seal.

The space existing between the two separate support elements 30 may, as the case may be, be left free or else closed in any suitable manner corresponding to the use of the conduit.

In FIG. 2, for example, the lower part 4 of the duct consists of a base layer 41 of compacted aggregates, placed between the internal lateral sides 33 of the support elements 30 and covered with a slab 42 which can be consisting of prefabricated elements or else cast in place by covering the upper faces 34 of the support elements 30.

We can thus, as shown in Figure 3, pass between the two support lines 3 a roadway 43 and we see that one of the advantages of this arrangement lies in the fact that the roadway 43 can be performed continuously and conventionally inside and outside the duct, while lower concrete elements would require a connection with the outside pavement, with the risks of offset due to differential settlement and expansion.

Furthermore, the planes of the transverse joints 23 between two consecutive arch elements 20 can be offset longitudinally relative to the plane of the transverse joints 35 between the support elements 30. In this way, the load applied by each upper element 20 is distributed on two consecutive support elements, on either side of the joint plane.

Advantageously, it is also possible, as shown diagrammatically in FIG. 5, to provide along the two transverse edges 8 of each base element protruding parts 81 which engage in recessed parts 82 formed on the transverse edge opposite the adjacent element.

In this way, it ensures relative centering of the consecutive elements to avoid the risk of misalignment when the structure is subjected to a lateral shifting effect, for example in curves.

A longitudinal shifting effect can also appear, for example, when the structure is produced on a surface inclined relative to the horizontal.

In this case, as shown in side view in Figure 4, each longitudinal support member 7 has a slot profile. The convex profiled part 71 formed on each lower edge 22 of the upper element 2 in fact extends alternately on two different levels so as to include, for example, a projecting central part 71 framed by two recessed parts 73 which s '' engage in inverted parts recessed 74 and projecting 75 on the upper edge of the basic element and which are provided with a longitudinal groove.

Such a niche profile ensures the longitudinal maintenance of each upper element 2 relative to the corresponding base element.

Of course, other similar arrangements, including hollow and projecting parts offset longitudinally could be used.

The transverse joints between two consecutive elements 30 can be made in different ways.

In Figure 6, for example, there is shown a sealed joint 5 between two consecutive elements 30, 30 '. The latter are provided, on their front faces facing waiting frames 51 which intersect in a space 50 left between the two elements 30 and 30 'and which are associated with transverse irons 52, l' together being embedded in a sealing mortar 53. The sealing joint 5 thus produced between the two consecutive elements 30 and 30 'constitutes a real keying in the longitudinal direction. By thus joining a certain number of consecutives elements, a monobloc sill is made, over a determined length, which makes it possible to distribute the load on the ground and to avoid differential settlement.

However, it is also possible, as shown in FIG. 7, to place at the opposite ends of two consecutive elements 30 and 30 ′, connecting members 54, 54 ′, which fit together 'one inside the other and can be connected by a pin 55. The two consecutive elements 30 and 30' are thus connected to each other by an articulated connection giving each element a slight possibility of deviation from the elements that surround it.

The dimensions of the support elements 30, and in particular the width L 'of their seating surface and their height H', will be chosen according to the circumstances of use, and in particular the loads supported and the bearing capacity of the ground .

Different profiles may also be provided. For example, for the production of underground pavements, at least one of the support lines 3 could consist of elements 30 shaped so as to have a substantially horizontal upper face 34 ′ and placed above the level of the pavement 4 so as to create a pedestrian traffic sidewalk.

According to another variant shown in Figures 9 and 10, the conduit is provided for the passage of liquid, for example from a river. In this case, the bottom 6 of the duct can advantageously consist of a series of plates 61 of cast iron, sheet metal or plastic, having a width equal to that of the duct and covering the space between the two elements 30, going up on the upper faces 34 of these up to the joints 31. As indicated in the Figure, the plates 61 can limit a hollow profile, for example for the passage of a channel and the height H 'of support elements 30 can be increased so as to raise the average water level, the bottom 6 thus limiting a sufficient section for average flow rates. Seals can be placed between the upper parts 31 of the support elements 30 and the upper edges 62 of each plate 6 so as to allow the water level to rise above the level of the edges 62 while filling more or less the conduit, in case of flood. The duct can even be pressurized if the lower edges 21 of the arch 2 are applied in the bottom of the grooves 31 by tensioned tie rods.

In addition, as shown in the perspective view of FIG. 10, the plates 61 can advantageously overlap each other in the manner of a covering, the transverse end 63 of a plate facing downstream, in the direction of circulation of the liquid, covering the front end 64 of the next plate 61 ', with the interposition of a sealing bead.

Other methods of coating the bottom could obviously be used. It is possible, in certain cases, that the longitudinal axis (O) of the duct is inclined relative to the horizontal and the support elements 30 may then have a tendency to slip. To avoid this, it will be advantageous to provide, on the lower faces 32 of the elements 30, hooking notches 37 which can be made during concreting or else, as shown in FIG. 10, be arranged on a cast iron plate 38 sealed on the underside of each support element 30.

As indicated in FIG. 10, in the event of a steep slope, the seat faces 32 of the support elements 30 could form steps, the laying surface A constituting steps A2 of corresponding width.

To avoid any danger of skidding, the elements 30 can be anchored in the ground by transverse beams forming keys. It is the same for the upper elements 2 which can be keyed relative to the basic elements.

According to another advantageous arrangement shown in Figures 3 and 10, are added to the upper elements 2 of the head pieces 9 placed at each end of the conduit.

Indeed, the conduit is buried under an embankment C and opens at each end into a slope C 'which must be maintained by the two lateral sides. To avoid unnecessarily prolonging the conduit outside the embankment C, head pieces are advantageously used, each comprising a vertical wall 9 of triangular or trapezoidal shape, associated with a flange 90.

In Figures 3 and 10, for example, the sole 90 consists of one or more support elements 39 identical to those 30 which support the arch elements 20. Each head piece then consists of a plate 9 comprising a horizontal side 91 which rests on the upper part 31 of the corresponding support element 39, a vertical side 92 placed in the extension of the side 24 of the last upper element 25 of the duct, and an inclined side 93 whose inclination corresponds at the natural angle of slope C '.

The wall 9 can be held in place by sealing between the vertical sides 92 and 24 facing each other or by fitting suitable parts sealed in the facing faces of said sides 91, 24.

In addition, the wall 9 is supported, in the longitudinal direction, on a stop 94 closing the chute 31 in which the horizontal side 91 engages.

But one could also make head pieces each provided with a sole 90 integral with the vertical wall 9, so as to produce a freestanding element.

The dimensions and the profile of the prefabricated elements can be chosen to vary the passage section and the space requirement, in particular the width L and the height H of the duct, depending on the circumstances, in particular the conditions of use. and the construction site.

In particular, the dimensional and structural characteristics of the elements such as the thickness of the roof, the nature of the concrete and the constitution of the reinforcement must be determined according to the constraints applied by the embankment and by the operating costs.

In addition, without modifying the profile of the vault, it is also possible to raise the level of the longitudinal supports 7, for example when the conduit is used for the passage of a height of water not exceeding, in normal service, the height of the supports 7 Such an arrangement makes it possible to keep the longitudinal supports out of the water as long as the flow rate transported by the conduit is normal.

However, other characteristics could also be modified or added, as required, and certain accessories can also be added to the basic elements or to the upper elements.

The roof elements 2 can also be subject to variants, some of which have already been described.

We can thus determine in advance different forms of upper elements and basic elements that can be combined in any possible way.

Furthermore, for each profile, it is also possible to vary the parameters determining the strength of the concrete, such as the thickness of the vault, the nature of the concrete used and the construction of the reinforcement, the reinforcements possibly being prestressed.

In this regard, it may also be advantageous as shown in Figure 1, to provide, in the thickness of the basic elements, recesses tubular which are placed in alignment with each other when laying the elements so as to form longitudinal channels in which it is possible to pass prestressing reinforcements then joined together, in a conventional manner, by pouring a mortar.

Such channels can also be used, for example, for the passage of pipes or electrical or telephone cables.

The parallel European patent application N ° 90,400,144.3 of which the present application is a Division, describes a system for producing buried conduits according to which the characteristics of a certain number of profiles of upper elements and d are defined in advance. 'basic elements which can be classified in series each corresponding to a width between supports.

We can thus define the characteristics of a certain number (a) of series I, I ', ... of basic elements and II, II', ... of superior elements, each series corresponding to a width between supports, so as to cover as continuously as possible, but under economically profitable conditions, a wide range of passage sections to meet the needs of customers. In practice, it will be possible, for example, to define four series of basic elements and of upper elements whose widths range between 1 meter and 2.50 meters, which allows, depending on the profile adopted, to produce surfaces passing from 0.35 m² to around 6 m².

In the same way, it is possible to produce at least a series III of support elements inside which a certain number of dimensional and structural characteristics are varied such as, for example, the width of the surface of seated, the height of the element, the shape of the support members 31, the nature of the concrete used and the constitution of the reinforcement, etc.

For example, in Figure 8, there is shown schematically two series III, III ', of support elements each corresponding to a width L'1 and L'2 of the seat surface and in which varied the shapes of the elements.

In addition to the series I, I '... of basic elements 1 and II, II' ... of upper elements 2, there is thus at least one series III of basic elements and, according to the needs, it will therefore be possible to combine the arch elements 20 chosen from the corresponding series with isolated support elements chosen from a series III, III ′, having a seating surface compatible with the bearing capacity of the ground.

The upper and base elements thus defined can be combined in all possible and desirable ways, by forming a certain number of standard sections of the same width and whose profiles and passage section are substantially different.

Of course, the associated elements must be compatible and, for example, we will combine together arch elements and basic elements having thicknesses and reinforcements allowing them to withstand forces of the same order.

We can have in stock a number of elements of several widths having significantly different characteristics with regard to the profile, thicknesses and reinforcement and corresponding to the most common needs. If the necessary elements are in stock, they can immediately be delivered to the site.

If the necessary elements are not in stock, they can however be made very quickly because all their dimensional and structural characteristics are already defined and we normally have the molds which were used to produce the elements subjected to the preliminary tests. When the customer orders elements having other accessory characteristics, such as internal pipes or anchoring members, or even slight variations in dimensions due to installation requirements, the mold is simply adapted to obtain, a the casting, of these additional characteristics, all the other characteristics remaining well fixed.

The prefabricated elements are then produced in a desired number either in a factory or on the site, and they are assembled to build the conduit.

Other prefabricated accessories could moreover be advantageously added to the series of support elements 30.

For example, the internal side of the elements 30 could be provided with parts arranged to constitute or receive circulation rails of a carriage or gantry facilitating the assembly and / or maintenance of the structure.

It is also possible to add to the series of upper and lower elements, a series of head pieces having thicknesses, heights and, possibly, different inclinations so as to be able to adapt to the different cases in the best way.

Generally speaking, moreover, one could imagine other variants and other accessory arrangements, for example for making the bottom or the upper part of the duct differently.

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

Claims (17)

Buried conduit for the passage of a roadway or a river, consisting of a series of contiguous sections placed one after the other, along a longitudinal axis (O), on the bottom (A) d '' a trench (B) and covered with an embankment C, said sections being formed by assembling on the site of prefabricated elements and each comprising, in cross section to the axis (O), a lower part resting on a surface of installation (A) and an upper part consisting of at least one element (2) forming a vault and resting on the lower part by means of longitudinal support members (7) (7 ') parallel to the longitudinal axis (O),
characterized in that the lower part of each section of the duct (1) consists of two support elements (30) produced in advance, each forming an insulated sole having, on a lower face, a seating surface (32) and, on an upper face (34), a longitudinal support part (72) for an upper element (2), said support elements (30) being placed one after the other so that the aligned support parts (72) form the two longitudinal support members (7, 7 ′) on which the lateral lower edges (71) of the upper elements come to rest (2), said support elements having dimensional characteristics and structural determined so as to be able to withstand the loads applied in service by the upper elements (2) and to ensure a seating surface (32) of sufficient width (L '), taking into account said loads and the lift from the ground (A) at this location. Buried conduit according to claim 1, characterized in that each upper element is produced so as to be able to deform under the action of the loads applied by pivoting slightly around the longitudinal supports (7, 7 '). Buried pipe according to one of claims 1 and 2, characterized in that each support element (30) has a substantially trapezoidal section comprising a wide lower face (32) providing a sufficient seating surface and an upper face forming an articulated support (72). Buried conduit according to one of the preceding claims, characterized in that it comprises, between the two lines (3) of support elements (30), a series of intermediate elements (61) resting on the internal parts (34) support elements (30) of the two lines (3) so as to form the bottom (6) of the duct (1). Buried pipe according to claim 4, characterized in that the intermediate elements (61) are made of moldable, injectable or laminated material, such as metal, concrete or plastic. Buried pipe according to one of claims 4 and 5, characterized in that the bottom (6) of the pipe (1) forms a channel for the circulation of a liquid and that the intermediate elements consist of plates (61) covering substantially the entire internal width of the conduit and overlapping each other in the manner of a stabilizer, the downstream end (63) of a plate (61) covering the upstream end (66) of the next plate (61 '). Buried conduit according to one of claims 1 to 3, characterized in that, in the case where the conduit (1) is used for the passage of a traffic pavement (43), this the latter is carried out without discontinuity passing between the two lines (3, 3 ') of support elements (30). Buried conduit according to one of the preceding claims, characterized in that the support elements (30) are each provided, on its underside (32), with projecting parts (37) for anchoring the element on the laying surface (A). Buried conduit according to one of the preceding claims, characterized in that the seating surface (32) of the support elements (30) forms stepped steps capable of being placed on steps (A₂) formed on the surface installation (A) in case of inclination of the longitudinal axis (O) of the duct (1). Buried conduit according to one of the preceding claims, characterized in that at least certain basic elements (30) are provided with at least one tubular recess formed in the thickness of the element and parallel to the axis ( O), so that the aligned tubular recesses of several consecutive base elements (30) form an internal channel extending over the entire length of the structure. Buried conduit according to one of the preceding claims, characterized in that each longitudinal support member (7) (7 ') comprises two rounded parts, respectively convex (71) and concave (72) formed respectively in projection and in hollow along the lateral sides (21) (31) facing the upper element (2) and the two base elements (30) of each section so as to form a joint. Buried pipe according to claim 11, characterized in that the profiled parts, respectively convex (71) and concave (72) extend alternately on two different levels so as to achieve along each base element (30) and each upper element (2), profits in inverted slots comprising, on the base element (30) recessed portions (74 ) and projecting (75) in which engage reverse portions formed respectively projecting (71) and recessed (73) on the lateral sides (21) of the upper element (2). Buried pipe according to one of the preceding claims, characterized in that at least some of the support elements (30) are provided with waiting reinforcements (51, 52) capable of being associated with transverse reinforcements (52 ) and to be embedded, after installation, in a sealing binder (53) so as to form a keyed joint, the assembly of several consecutive elements (30, 30 ') thus constituting a monobloc sill. Buried conduit according to one of the preceding claims, characterized in that the adjacent ends of the support elements (30, 30 ') of the same line are provided with connecting members (54, 54') interconnected so as to form a link articulated around an axis (55). Buried conduit according to one of the preceding claims, characterized in that, the conduit being covered with an embankment (C) limited by an embankment (C '), each end (25) of the conduit opening into the embankment (C' ) is equipped with two head pieces (9) placed respectively in the extension of the two sides of the duct, and each comprising a side wall element (9) of bias shape resting on a support sole (90) and capable of be placed respectively in the extension of the two lateral sides (24) of the upper element (25) placed at the end of the duct, each side wall element (9) having a substantially trapezoidal or triangular shape comprising a horizontal side (91) resting on the support base (90), a vertical side (92) placed along the corresponding side (24) of the upper element (25) and an inclined side (93) whose inclination corresponds to the natural slope angle (C ′) of the embankment covering the duct. Buried conduit according to claim 15, characterized in that there is a series of head pieces (9) in which at least one of the parameters has been varied such as the thickness of the wall (9 ), the height of the vertical side (92), the inclination of the inclined side (93) and the width of the support base (90). Precast concrete elements for producing a conduit according to one of the preceding claims.

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