OA11909A - Tubular work. - Google Patents

Abstract

The invention concerns a tubular structure comprising, in cross-section transverse to its axis (O), at least three prefabricated elements, respectively two side wall elements (32, 32') resting on the setting surface and at least one upper element (31) with a curved profile resting, along two longitudinal joints (36), on the upper edges of the two side wall elements (32, 32') and tangentially connected thereto to form a continuous vault for transmitting loads on the bases (33) of said side walls (32, 32'). The invention is characterised in that at least some of the side wall elements (32, 32') are shaped so as to possess sufficient rigidity for carrying the applied loads without lateral support on an embankment covering the structure.

Description

1 119 09

The invention belongs to the field of construction and public works. Its purpose is an underground passage structure, especially for the circulation of vehicles. The invention also covers previously prefabricated elements, specially adapted for the realization of such a work.

A lane of traffic and, more forte reason, railway, must have a fairly regular enlong profile, avoiding too important slopes. It is therefore not possible to follow the terrain profile constantly, as the platform in some sections is either above or below the natural terrain level. On the other hand, it is desirable, at crossings, to pass one path below the other by means of an underground pass.

When the difference in level between the installation surface of an underground passage and the natural terrain is not too great, it is advantageous to make an open trench whose bottom is placed at the desired level to allow the open construction of the structure which is then covered with an embankment to restore the level of the natural terrain. For a few years, the inventor has developed a particularly advantageous technique for constructing works of this type, which is described in particular in EP-A-0.081.402 or US-A-4,836,714.

In this technique, the structure consists of prefabricated wall elements arranged one against the other on a platform formed in the bottom of the trench. In an embodiment described in particular in document EP-A-0.081.402, the structure comprises, in cross-section to the axis, an upper element forming a vault resting on twopieces placed on either side of a raft. Preferably, the upper longitudinal joints between the vault element and the upper edges of the two walls are constituted by articulations that provide a relative flexibility for the structure, especially during the construction of the backfill. In addition, the pedestal elements advantageously have a curved upper portion that is tangentially tangential to the upper element so as to form a continuous vault.

Between the bases of the two piers may be placed an element of slab, prefabricated or cast in place, which connects to the inner sides of the bases of the piers by concrete joints forming a rigid longitudinal connection, thus forming a flat base for distributing the load on a large area.

In some cases, however, particularly when the span of the structure is very important, the deck may be removed, each deck resting on the ground by an enlarged base, the dimensions of which are calculated according to the loads to be borne and the bearing capacity of the ground. Such an arrangementis described in particular in US-A-4,836,714.

In a particular embodiment, it is possible to construct structures of very large dimensions, consisting of several adjacent passage sections, for example for the realization of an underground highway with several traffic lanes. In the case of a work having two sections of passage, these are separated by a central right, on which two devout elements rest, which, on the external side, are supported on a side-wall.

This technique has experienced significant development because it makes it possible to achieve particularly fast and economic works of great section.

Indeed, the whole of the supporting structure is made up of prefabricated elements which can be realized economically and in the best conditions of safety, in a specially equipped factory of manufacture or in a fairground workshop installed close to the opening when this one is important. It is thus possible to rigorously control the manufacturing conditions and, in particular, the composition of the concrete and its water content, the positioning of the reinforcement and the surface quality after stripping. In some cases, it is even possible to use high performance concretes.

As a result, the use of prefabricated elements, compared to a construction and concreting on site, makes it possible to reduce their thickness in relation to their range and, consequently, to lighten them. Even for large ships, the prefabricated elements can be handled and set up by the lifting gear that is usually available on a construction site.

To build such a work, after having dug a trench whose bottom is applied to the level wanted, one poses successively, first of all the elements that are designed to stand up straight by themselves, then the upper elements which rest, at 4 119 09 their ends, on two side elements, the assembly is then covered with a backfill. According to one of the characteristics of this technique, lembly participates in the resistance of the whole. Due to the fact that the elements can be particularly thin and that the tooling can be carried out with great precision, the elements have a certain flexibility and can yield slightly when the structure supports the embankment and the overloads, which reduces the forces applied to the key, the structure bearing laterally on the front.

It is particularly interesting to use such a technique for the circumvention of agglomerations or the passage of a road or railroad in a protected area, because the work can be made in open trench over a great length, even close to homes, then be covered by an embankment so as to restore the level and the natural aspect of the ground by ensuring, in addition, a near perfect sound insulation.

However, it is not always easy to carry out, on both sides of the structure, an embankment that can accommodate side forces. This is the case, especially in an urbanized area when the project passes close to existing buildings, for example, the foundations or basements of a building, or a sewer. In addition, in a narrow space, it may be necessary to pass pipes near the work and it can therefore be brought, for maintenance location, to reopen the embankment. The object of the invention is to remedy such disadvantages by means of a new embodiment of such a structure that makes it possible to avoid the creation of a lateral embankment capable of withstanding lateral stresses, particularly in urban areas and in urban areas. lescas where the taxiway is, in all or part, above the level of the natural terrain. The invention thus relates to the realization of tubular constructions made ofprefabricated wall elements arranged one after the other on a platform so as to form a structureuseesistant having at least a passagetubulaire section centered on a longitudinal axis and resting on the platform by a flattened base, the structure comprising, in cross-sectional area, at least three elements, respectively two side membersforming piers each having a wall vertically having an upper edge and a base with a flat lower face resting on the platform, and at least one upper profile-profiled member resting on the upper edges, respectively, of the two right-hand elements, along two longitudinal joints and tangentially connecting to the upper parts of saidpieces so as to form a continuous arch for the transmission of loads on the bases of said rights.

According to the invention, at least some elements of piédroit, placed on the outer side of the structure, are shaped so as to have aerigidité sufficient to cash and transmitcharges applied, without lateral support on a backfillcouvrant the book.

In a preferred embodiment, each side member is provided with at least one stiffening rib extending over at least one face of its side wall and capable of opposing a deformation thereof under the effect of the charges applied by the upper element.

Furthermore, each upper element may advantageously be provided, along at least one side edge placed on the outside of the structure, with a rigid sail extending upwardly for the maintenance of a minimum thickness of backfill above the upper element. The invention also covers the prefabricated wall elements thus produced. The invention therefore constitutes an extension of the known technique for producing tubular structures which has numerous advantages and makes it possible to adapt them to particular situations.

Indeed, until now, it was accepted that the construction of underground passages was necessary only in the case where, precisely, the circulation platform is below the level of the natural terrain. When, on the contrary, the ground falls below the level of the platform, it must be built on an embankment or viaduct to restore the desired level. In urban areas, there is the problem of noise caused by vehicular traffic and environmental disturbance, and costly, unattractive and sometimes ineffective noise barriers are often required. The invention also remedies such inconveniences by making it possible to ensure, under the best conditions, the protection of the environment along the entire length of the traffic path. 7 119 09

In fact, thanks to the provisions according to the invention, the structure can be made at least partly above the level of the natural terrain. It is first covered with a first embankment havinga platform-shaped upper part to form the laying surface and, after the elements have been laid, the whole structure and the first frame which supports it are covered with a second connection which connects to the natural terrain on either side of the structure so as to form a collineartificielle, the flattened base of the structure havinga width determined according to the capacitanteanteante of the first embankment so as to transmit to the latter the applied loads excessive settlement. Other advantageous features of the invention will be described in the description of certain particular embodiments, given as non-limiting examples and shown in the appended drawings, in which:

Figure 1 is a schematic view, in longitudinal section, of the assembly of a workpieceaccording to the invention.

FIG. 2 is a cross-sectional view along the line II - II of FIG.

FIG. 3 is a cross-sectional view along the line III-III of FIG.

Figure 4 is a schematic set view, in perspective.

Figure 5 is a detail view of the base of a podium.

Figure 6 shows, in cross section laréalisation of a work with two contiguous sections. without risk of claims and claims that will follow 8 1 7 9 0 9

Figure 7 shows a particular embodiment of such a work.

Figures 8 and 9 show, respectively envue from side and in plan view, the output of a traversing work obliquely an embankment.

FIG. 1 shows, in longitudinal section, a part of a traffic lane made according to the invention on a relatively uneven ground whose long profile is indicated by the line 10 corresponding to the section of the natural terrain 1 by a Vertical plane P passing through the longitudinal axis of the traffic channel. This is provided on a platform A which comprises a portion 11 below the level of the natural terrain and a portion 12se above it.

Therefore, the portion 11 of the platform A is cut into the bottom of a trench Balors that the portion 12 is formed on the top of a unite C.

In the section 11 excavated, the platform constituting the taxiway is covered, classically, a tubular structure D constituting an underground passage that is first made to cielouvert, then buried under a embankment E to restore level 14 natural terrain.

Such an arrangement is particularly advantageous for the circumvention of urbanized areas because it allows to ensure perfect isolation and restore the environment, embankment To be planted.

In one embodiment described in patent EP-0,081,402, the tubular wall D is formed of successive sections placed end to end 9119 and 9 each comprising, in cross section, at least three elements, respectively a curved upper element 21 resting on two side piers 22, 22 'each provided with a flat base allowing them to be placed standing upright on the ground. The inner sides of the bases of the two piers may be connected, by longitudinal skewed joints, to a fourth element forming a raft. Thus, all of the load applied to the tubular wall is transmitted to a very large base.

However, it is also possible to remove the base. As shown in FIG. 2, each lateral sidewall 22, 22 'then comprises an enlarged base 23 having two wings, respectively internal and external, which give the element a sufficient seating surface, and a sidewall 24 having a portion upper 25, inwardly curved, which is connectedangentially to the upper element 21 so that the whole forms, in cross section, a substantially semicircular vaults centered on an axelongitudinal 0.

In addition, the longitudinal joints 26 between the upper element 21 and the upper edges of the two lateral crosspieces 22, 22 'consist of articulations centered on planes PI, P'1, in which are placed the centers of curvature of the upper element 21 and upper parts 25 of the pans 22, 22 '. Preferably, these joint planes are inclined at 45 ° with respect to the vertical.

In this known arrangement, the loads applied to the upper member 21 are transmitted substantially to the two side legs 22, 22 '. 10 119 0 9

The latter are supported on the ground by their base 23, but because of the flexibility of the structure and the use of the articulated joints 26, the upper element 21 has a tendency to bend slightly away from the side walls 22, 22 'which also flex and take Lateral support is applied to the embankment E. This must therefore be carried out in a particular manner to participate in the resistance of the whole structure by accommodating the lateral thrusts applied by the two piers 22, 22 '.

As indicated, it is not possible, in some cases, to bear laterally on the surrounding grounds.

According to the invention, the lateral piers which are then able to withstand the loads applied by the upper element themselves are formed so as to be rigid enough not to bend under load. For this purpose, as shown in Figure 3, each side member 32 is provided with a stiffening rib 37 placed on the outer side of the wall 34 and extending between the base 33 and the seals 36. The wall 32 thus stiffened can therefore transfer the loads in a substantially vertical direction, without lateral support on the assembly 5.

Such an embodiment of the side walls is particularly advantageous in the caserepresented in FIG. 1, of a naturally relatively uneven ground.

Usually, in fact, when the level of the platform 11 reaches the natural level of the ground 1, at the point 13 of the longitudinal profile 10, the stepped structure 2 covered with an embankment is stopped and after the driving lane A is made to 11 119 0 9 open on the upper part of a slope C or even on a viaduct. This results in environmental discomfort and, in urbanized areas, it is often necessary to build noise barriers along both sides of the A platform. Such a realization is expensive and unattractive.

According to the invention, instead of being stopped at the outlet of the trench B, the tubular structure 2 is extended by a similar structure 3 which is shown in FIG. 3, the latter being a cross-section, along the line III-III of FIG. 1. For this purpose, a first embankment 4 is built in the extension of the part 11 of the platform A, the upper portion 41 of which is stowed so as to form a platform 12 on which the tubular structure 3 is placed. .

In FIG. 4, which is a perspective view of the assembly, there is shown, for simplification, a single section of the tubular structure 3 which comprises, in cross-section with the axis O, at least three elements, respectively a curved upper element 31 resting on two side walls 32, 32 'along longitudinal joints 36. These prefabricated wall elements preferably have exactly the same profile as the elements 21, 22, 22' of the structure 2 and are thus placed in the extension thereof. The longitudinal joints 36 are thus placed in alignment with the longitudinal joints 26 of the structure 2 and constitute, in the same way, joints giving the structure unerelative flexibility.

In addition, each pedestal 32 is provided with a base 33 bearing on the platform 12. 12 119 0 9

After the installation of the elements constituting the structure 3, in the extension of the structure 2, the assembly is covered with a second embankment 5 whose surface 50 is progressively connected to the natural terrain 1 and the surface 14 of the embankment E, so as to realize a artificial hill that can be advantageously planted to restore an aesthetic environment.

It is clear that, in this way, a near-perfect acoustic isolation is achieved, even in areas where the A platform is at a higher level than the natural terrain.

In addition, the traffic on the covered Aainsi platform is no longer visible from neighboring buildings F.

These essential advantages can offset, in urbanized areas, the additional price due to the realization of structure 3 and the second embankment 5.

As for the structure 2, each sidewall 32, 32 'preferably comprises an enlarged base 33 and a curved sidewall 34 which will be tangentially tangential to the upper element 31. The upper elements 31 and the sidewalls 32 have the same profile as the elements. analogs 21, 22 of. structure 2 and can thus be cast on the same molds, these being slightly modified to realize the stiffening ribs 37.

The width of the base 33 of each wall 32 must be determined by taking into account the large capacity of the first backfill 4 which may be lower than that of the platform 11 formed in the bottom of the trench B, ie on the natural land. 13,119 0 9

However, as indicated above, prefabricated elements of this type, even for a large distance, can be made at a remote site duchantier and transported by road, each element may be placed lengthwise on a trailer.

For large dimensions, it is therefore interesting to calculate the elements so as to lighten them to the maximum and, insofar as a stiffening rib is added to a sidewall, it may be better to reduce the width of the soleplate by providing a possibility of widening of it, after the pose, to give him the necessary sitting surface. For this purpose, as shown in FIG. 5, it is possible to provide, during the manufacture of the half-pipe elements, to leave on the two sides, respectively external 33a and inner 33b, of the base 33, waiting frames 42a, 42b. Thus, the weight of the side element can be reduced so as to be compatible with the transport capacities. After the elements are installed, it is possible, by means of appropriate formwork, to pour extensions 44a, 44b on each side of the section. base 33 so as to widen the latter to reduce the loads applied to the embankment 4. Thus reducing the width of. In step 33, it is possible to compensate for the increase in weight on the rib 37. Furthermore, longitudinal reinforcement 45 covering several successive right-hand elements can be threaded into the waiting armatures 42 so as to make a longitudinal length of connection between the elements, allowing them to be better resist differential settlements. 14 1 19 0 9 "*

To further increase the seating surface 30, it is also possible to flow, between the inner sides of base 33, 33 'of the two wall elements 32, 32', unradier 43 provided with the necessary reinforcement and in which are drowned the waiting frames 42b.

To simplify FIG. 3, there is shown a structure made on a natural terrain 1 substantially horizontal in cross section. In practice, however, the slope line of the terrain, in a direction orthogonal to the longitudinal axis of the structure, may be more or less inclined relative to the horizontal, between an upstream slope 16 and a downstream slope 15. As it is 6, it follows that, in the zone where the platform 11 passes above the natural ground level 1, the side of the work turned from the naval side must be placed on an embankment 61, while the side facing upstream rests on the bottom of unetranchée 62 made in cut.

The structure according to the invention is particularly adapted to such a situation. As mentioned above, the use of prefabricated brackets, supported on a wide web and on which the upper element is supported by means of a longitudinal joint, makes it possible to withstand particularly well the differential settlements which may result from such asymmetrical support.

FIG. 6 shows, for example, a two-arch structure of the type described in EP-A-0202.256, which is particularly suitable for the realization of motorways and comprises at least two SI traffic lanes, S2 on either side of a central wall 63 on which 119 119 09 rest two upper elements, respectively 64,64 ', which bear outwardly, each on a lateral side, respectively 65 on the upstream side and 65' on the side downstream.

The embankment 5 which covers the whole of the work and connects to the natural terrain in the manner shown in Figure 6, is asymmetrical, but this does not affect the stability of the structure, thecharges being transmitted vertically by the rights 65, 65 ', made rigid by the ribs 37.

Figures 3 and 6 show another improvement of the invention. Indeed, the secondremblai 5 which is formed over the first embankment4, can be subject to slippage and that is why it is advantageous, as shown in Figure 3, to provide on the lateral side of eachelément upper 31, a concrete veil 38 extends upwardly so as to retain the upper portion 51 of the embankment covering the structure. Thus, it is always covered with a kind of cap in terredont the weight increases the stability of all and that will not collapse if the downstream portion 52f embankment 5 tends to slip.

Preferably, the retaining web 38 isperpendicular to the lateral side of the wall element 31 and, therefore, parallel to the joint plane PI.

In the case of a single-section work shown in Figure 3, the upper element 31 may be provided with two webs 38, 38 'formed on each side. On the other hand, in the case of a two-section structure, each upper element 64, 64 'is provided with a retaining veil 38 only on its external side resting on a lateral side wall 16 119 65 65', the inner sides of the two elements 64, 64'reposant symmetrically on the central wall 63.

It should be noted that the prefabricated elements that have just been described have many advantages that justify their application to various situations.

For example, through the use of reinforced substrates as described above, the assembly must no longer be performed in a particular way and can therefore be reopened in case of need. As a result, it is possible to pass therethroughs 67 which can be laid even after completion of the work.

This advantage is particularly interesting urban site because it frees space on each side of the book. Such piers may therefore advantageously be used, even for a structure made, conventionally, on the bottom of a trench.

However, in the case shown in FIG. 6 of a structure made on a terraindissymmetric, the part of the backfill between the right-hand side upstream 65 and the slope 16 can be made in order to accommodate lateral thrusts. Lepiédroit 65 could thus have been realized without rib, like a podium 22 of structure 2.

FIG. 7 shows another example of embodiment of a two-lane structure in the case of a skewed exit in an inclined natural terrain. It may then be of interest to first stop the section S'2 of the setrouvant on the downstream side and to prolong for some time the section S'1 located on the upstream side and which is alone covered with a slope 51 '. The latter 17 119 0 9 is advantageously stopped by an inclined web 38 arranged on the side facing the slope of the upper element 66 which rests on the central 63''republique.Ce may be constituted by a solid wall or unerangée pillars surmounted by a sill andcomportant, on the upstream side, a single support member 36for the upper element 66 covering the section S'1.Du downstream side, the upper part of thecentral element 63 'advantageously comprises a tapered face 39a support of the retaining web 38a.

Similarly, the rib 37 of each element 65 'perpendicular to the outwardly closing section S'2 may be provided at its upper end with an inclined surface 39 having the same orientation as the star 38' associated with the upper member 64 'so as to constitute a bearing surface of said web 38'.

It should be noted that the slope 51 can be closed at the level of the sail 38 ', the lower portion 52 being removed 5 being removed. The work is then covered with a simplecalotte of earth and the ribbed piers 65 'remainvisible from the outside while assuring by themselves the phonic protection. This gives an interesting aesthetic effect.

Moreover, even in the case of a trenched and fully covered with an unfinished work, it may be interesting to foresee forged works at the outlet of the work, especially when it is arranged at an angle to the embankment that covers it . By way of example, FIGS. 8 and 9 show the exit of such a structure through an embankment E on which is formed a traffic lane 14 whose longitudinal direction makes a non-right angle with the axis 70 of the book 7.

In current section, the structure is constituted, as the structure 2 of Figure 2, succesive sections each comprising an upper element 21reposant on two side walls 22, 22 'quipeuvent take a lateral support on the emboundment Erecouvrant the book. However, the embankment E, which has been removed in FIG. 9, is limited by an inclined slope E 'whose edge along the structure is indicated in dashed line. Usually, at the exit 7de the structure, the lateral piers 72, 72 'of the last section 71 are extended by prefabricated walls 73, 74 having the same inclination as letalus, for the maintenance of land.

It can be seen that, in particular on the most remote side of the bottom of the embankment, the wall 72a can not rest on the embankment whose height is insufficient. In this case, to accommodate lateral thrusts applied by the upper element 71, the two side elements must sometimes be connected to their base by a connecting beam extending between the two flanges 73, 73 '. This may have disadvantages, for example for the realization of a road passing inside the structure and these disadvantages can be avoided by using, at the two ends where the height of earth is inadequate, ribbed piers of the type described above and which encash by they themselves are applied without having to take a lateral support on the embankment.

As shown in FIG. 9, the adjacent pieces 72a, 72b of the two last sections are then provided with ribs 37 whereas, on the other side, only the extreme piece 72'a is pointed, the right side 72'b of the penultimate sectionprenant support on a slope of sufficient height to encase the thrust and being, therefore, identical to the current pawl 22 '.

It therefore appears that the prefabricated elements which have just been described can be used in various ways. In addition, the invention is obviously not limited to the details of the embodiments which have just been described by way of example, other variants, other improvements and other uses that can be imagined without departing from the protective frame defined by the claims.

In particular, it is advantageous to use, for the construction of the structure, wall elements with an enlarged soleplate, but it may be preferable to connect the bases of the two piers, by means of a radon pad for distributing the load on a base plate having a very large surface area. large seating area. On the other hand, as mentioned above, in the embodiments described in the prior patents, the piers were dimensioned and ironed so as to have a certain flexibility by relying laterally on the backfill.In the invention, on the other hand, the totality of the applied load is transmitted by the sideboard on sasemelle and it results, for the same cross section, an increase of the compression stresses applied on the concrete. Therefore, in order not to be forced to increase the thickness of the paroilateral and, therefore, the weight of the piers, it may be advantageous to make the elements into a high performance concrete having substantially increased compressive strength.

The reference signs inserted after the technical features mentioned in the claims, are intended only to facilitate understanding of the latter and do not limit the scope thereof.

Claims (12)

21 119 0 9 BEZEHDISàiSHâ 1. Underpass structure / intended to be at least partially covered by embankment (E) and consisting of wall elements. prefabricated 5 arranged one after the other on a platform (A) so as to form a tubulairérésistante structure (£) having an axis. . longitudinal (0) andcomprising, in cross-section with the axis (0), at least three elements / respectively at least one curved upper element (31) resting, along two longitudinal joints (36, 36 ') on the upper edges of two side members (32, 32 ') forming piers each having a base (33) resting on the platform (A) and a substantially vertical side wall (34) having an axially curved top portion (35) ( O) of the structure and seraccordant tangentially to the corresponding side of the upper element (31) so as to form a continuous vault for the transmission of charges on the 20 bases. (33, 33 ') of said pane members (32, 32'), the latter being each provided with at least one stiffening line (37) provided on the outer side of the sidewall (34) and extending from the base (33) substantially to the level of the longitudinal seam (36), so that each leg member (32, 32 ') has sufficient rigidity to cascade the applied loads without sagging and transmit them onto the base (33) without lateral support on the embankment (E) covering the structure. 2. A tubular structure according to claim 1, characterized in that it is provided with each longitudinal joint (36, 36 ') between a pedestal element (32) and the upper element. (31) is a longitudinally-oriented hinge 22 119 0 9 3 "tubular structure according to claim 2, characterized in that each longitudinal joint (36) is centered on a joint plane (PI) inclined relative to the vertical. 4. Underground tubular structure for the production of a traffic lane on an accident site, constituted by assembly on the site of prefabricated wall elements and comprising a first tubular structure (2) firstly made open at a first portion (11). ) of a platform (A) formed on the bottom (11) of a trench (B) below the level of the natural ground (1), then covered with an embankment (E), said tubular structure (2) having a longitudinal axis (0) and 15 comprising, in cross-section at the axis (0), at least three elements, respectively at least one curved upper element (21) resting, along two longitudinal joints (26, 26 ') on the upper edges of two side members (22, 22 ') forming piers each having a base (23) resting on the platform (A) and a substantially vertical side wall (24) having an axially curved top portion (25). (O) of the book and seraccordant tangentially to the corresponding side of the upper member (21) so as to form a. Continuous vault, characterized in that, from the outlet of the trench (B), the first tubular structure (2) is extended by a second structure (3) of the same type, placed on a second part (12) 30 of the platform (A), arranged above the natural ground level (l), at. the upper part (41) of a first embankment (4), and extending in the extension of the first part (11) of the platform (A), that, after the laying of the elements (31, 23 1 19 09 31 ', 32) of the second structure (3) all thereof and the first embankment (4) which supports it istrésouvecouvert a second embankment (5) which is connected to the naturalterterrain (1) on both sides of the the work of forming an artificial hill, and that the elements of piers (31, 31 ') of this second structure (3) are each provided with au. at least one stiffening rib (37) formed on the outer side of the sidewall (34) and extending from their base (33) substantially to the longitudinal joint (36) so that each sidewall (32/32 ') ) has a sufficient rigidity to cash in without sagging the applied loads andtransmitting them on the base (33) of the structure (3) without lateral support on the embankment (E) covering the work. 5. An underground structure according to claim 4, characterized in that the second structure (3) rests on a seat surface (30) having a width determined according to the bearing capacity of the first embankment (4) so as to transmit & this one the charges applied without risk of excessive settlement. 6. An underground structure according to claim 5, characterized in that the natural ground (1) on which the structure is constructed is inclined in a direction transverse to the longitudinal axis (0) of the structure (3) between an upstream upstream (16). ) and a downstream slope (15), the platform (A) is made asymmetrically and comprises a part (18) made of cuttings in the bottom of a trench (62), and on which are laid the piers (65) of the work turned on the upstream side (16), and a portion (17) made embankment (61) to 24 119 09 above the natural terrain (1) and on which are placed the pans (65 ') of the work turned sideaval (15), at least said downstream piers (65 ') being provided with a reinforcing rib (37). 7. Tubular structure according to one of claims 5 and 6, characterized in that the base (33) of at least some of the side elements (32) of the second structure (3) is provided on at least one lateral side (33a, 33b), waiting reinforcements (42) capable of being embedded in a concreting after installation of the element to achieve widening (44) of the seating surface (30). 8. Tubular structure according to larevendication 7, characterized in that it comprises a raft (43) extending between the bases (33, 33 ') of the side elements (32, 32') and secured. sides, internally (33b) saidbases (33, 33 ') so as to form a seating surface (30) of the structure (3). 9. Tubular structure according to one of the preceding claims, characterized by the fact that each upper element (31) is provided, along at least one side facing outward, a voilerigide (38) extending towards the from said side for holding an earth cap (51) having a minimum thickness of backfill at least partially covering the structure. 10. Tubular structure according to larevendication 9, characterized in that the rigid web 30 (38) formed on one side of an upper element (31) rests on a bearing surface (39) oforientation arranged at an upper end of each stiffening rib (37) of the corresponding right-hand element. 25 119 0 9 11. Tubular work according to one of the claims 9 and 10, characterized in that the lemblai partially covering the structure is stopped at the level of the retaining veil (38), the elements dïèdroit right nervurôs (65 ') remaining visible from outside. Tubular structure according to one of claims 9 to 11, comprising at least two sections (S1, S2) contiguous on either side of at least one central wall (63), each section comprising an upper element (64) resting, one side on the central wall (63) and the other on a lateral right (65), characterized in that, at the exit of a ground whose surface is at an angle to the longitudinal direction of the structure, the one of the sections (S'1) on the upstream side is extended relative to the other (S'2j and is covered by an upper element (66) provided on the supporting side on the central wall (63); *), a rigid sail (38a) extending upwardly for the maintenance of a fill (51 ') up to the level of the right center (63'), the upper part of which provides, on the upstream side, a support (36) for the upper element (66) and, on the downstream side, an inclined face (39a) for supporting the durability web (38a) (51 ').