FR2783540A1 - Tubular structure for underground passage has sidewalls with cover cap formed of prefabricated sections - Google Patents

Abstract

The tubular tunnel comprises three prefabricated components, two sidewalls (22,22') which rest on the ground and an upper component (21) with a curved profile resting along two longitudinal joints (26) on the upper edges of the sidewalls. This upper component is connected tangentially to the side walls to form a continuous vault for the transmission of loads onto the bases (23) of the sidewalls.

Description

The invention belongs to the field of construction and works

  public. Its purpose is an underground passage structure, more particularly intended for the

vehicle traffic.

  The invention also covers prefabricated pedestal elements, specially adapted for making

of such a work.

  A road and, a fortiori, a rail traffic lane must have a fairly regular longitudinal profile, avoiding too steep slopes. It is therefore not possible to constantly monitor the profile of the terrain, the

  platform located, in certain sections, either

  above, or below the level of the natural terrain.

  On the other hand, it is desirable, at crossings, to pass one lane below the other by means of an underground passage. When the difference in level between the platform of an underground passage and the natural ground is not too great, it is advantageous to make an open trench, the bottom of which is placed at the desired level to allow the construction in the open air of the structure which is then covered with an embankment to restore the level of the

natural land.

  The inventor has developed, in recent years, a particularly advantageous technique for constructing works of this type, which is described in particular in

  document EP-A-0.081.402 or document US-A-4.836.714.

  In this technique, the structure consists of prefabricated wall elements arranged one after the other on a platform provided 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 with the axis, an upper element forming a vault resting on two pedestals placed on either side of a slab . Preferably, the upper longitudinal joints between the arch element and the upper edges of the two pedestals are formed by articulations which give the structure relative flexibility, in particular when the embankment is being made. In addition, the wall elements advantageously have a curved upper part which tangentially connects to the element.

  upper, so as to form a continuous arch.

  Between the bases of the two pedestals can be disposed a radiant element, prefabricated or cast in place, which is connected to the internal sides of the bases of the pedestals by concrete joints forming a rigid longitudinal connection, the assembly thus forming a flat base allowing

  distribute the load over a large area.

  In certain cases, however, in particular when the span of the structure is very large, the raft can be removed, each pedestal resting on the ground by an enlarged base whose dimensions are calculated according to

  loads to bear and the bearing capacity of the soil.

  Such an arrangement is described in particular in the document

US-A-4,836,714.

  In a particular embodiment, it is possible to build very large structures, consisting of several adjacent passage sections, for example for the construction of an underground highway with several traffic lanes. In the case of a structure with two passage sections, these are separated by a central pedestal on which rest two arch elements which, on the exterior side, bear

each on a side pedestal.

  Such a technique makes it possible to produce structures of very large cross section in a particularly rapid and economical manner and it has therefore experienced significant development. In particular, this technique has been used for the bypassing of built-up areas or the passage of a road or rail track in a protected area, because it allows the work to be carried out in a trench, even over a long length, and then to cover it by an embankment so as to restore the level and the natural aspect of the ground in

  ensuring, in addition, almost perfect sound insulation.

  However, it was accepted, until now, that the construction of underground passages was necessary only in the case where, precisely, the circulation platform is below the ground level

  natural. When, on the contrary, the ground descends

  below the level of the platform, it must be built on an embankment or viaduct to restore the desired level. This raises the problem, in urban areas, of the noise caused by vehicle traffic and the discomfort caused to the environment, and it is often necessary to produce noise barriers which are costly, inexpensive

  aesthetic and sometimes ineffective.

  The object of the invention is to remedy such drawbacks by means of a new embodiment of such a structure making it possible to protect the environment over the entire length of the track.

circulation.

  The invention therefore constitutes an extension of the usual techniques for producing tubular structures made up of prefabricated wall elements arranged one after the other on a laying surface so as to form a resistant structure having at least one tubular passage section centered on a longitudinal axis and resting on the laying surface by a flattened base, the structure comprising, in cross section with the axis, an upper element resting on its lateral sides in two

wall elements.

  According to the invention, at least one of the pedestal elements, placed on the outside of the structure, is provided with at least one stiffening rib extending on one face of its side wall and capable of opposing to a deformation of it under the effect of

  loads applied by the upper element.

  Furthermore, according to another particularly advantageous arrangement, each upper element is provided, along at least one lateral side placed on the outside of the structure, with a rigid veil extending upward for the stable maintenance of 'thickness

  minimum of backfill above the top element.

  The invention also covers the prefabricated wall elements specially adapted for such a structure, which

  may have advantages in other situations.

  Other advantageous provisions of the invention

  are the subject of the claims and will emerge from the

  description which follows of certain embodiments

  particulars, given by way of nonlimiting examples and represented in the appended drawings, in which: FIG. 1 is a schematic view, in longitudinal section, of the whole of a structure produced according to the invention. Figure 2 is a cross-sectional view along

line II-II of Figure 1.

  Figure 3 is a cross-sectional view along

line III-III of Figure 1.

  Figure 4 is a schematic overview, in perspective. Figure 5 is a detail view of the base of a

pedestal.

  Figure 6 shows, in cross section the

  creation of a structure with two adjoining sections.

  Figure 7 shows an embodiment

particular of such a work.

  Figures 8 and 9 show, respectively in side view and in top view, the exit of a structure

crossing an embankment at an angle.

  In Figure 1, there is shown schematically, in longitudinal section, part of a traffic lane produced according to the invention on relatively uneven terrain whose longitudinal profile is indicated by line 10 which therefore corresponds to the section of the natural terrain 1 by a vertical plane P passing through the longitudinal axis of taxiway A. This is provided on a platform which includes a portion 11 lying below the level of the natural terrain and a portion 12 lying on top of it. Consequently, the platform 11 is formed in cut on the bottom of a trench B while the part 12 is formed on the top of an embankment C. In the cut 11 in part, the traffic lane A is covered , in a conventional manner, of a tubular work D constituting an underground passage which is first made in the open air, then buried under an embankment E to restore

level 14 of the natural terrain.

  Such an arrangement is particularly advantageous for bypassing urban areas because it ensures perfect sound insulation and

  restore the environment, the embankment E can be planted.

  In an embodiment described in patent EP-0,081,402, the tubular wall D consists of successive sections placed end to end and each comprising, in cross section, at least three elements, respectively a curved upper element 21 resting on two side pedestals 22, 22 ′ each provided with a flat base allowing them to be installed while standing straight on the ground. The internal sides of the bases of the two pedestals can be connected, by concrete longitudinal joints, to a fourth element forming a raft. In this way, the entire load applied to the tubular wall is

  transmitted to a very large area base.

  However, it is also possible to delete the deletion. As shown in FIG. 2, each lateral pedestal 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 side wall 24 having an upper part 25, curved inwards, which tangentially connects to the upper element 21 so that the assembly forms, in cross section, a substantially semicircular arch

centered on a longitudinal axis 0.

  In addition, the longitudinal joints 26 between the upper element 21 and the upper edges of the two lateral pedestals 22, 22 'are constituted by articulations centered on planes P1, P'l, in which are placed the centers of curvature of the 'upper element 21 and upper parts 25 of the sides 22, 22'. Preferably, these joint planes are inclined at 45 relative to the vertical. In this known arrangement, the loads applied to the upper element 21 are transmitted tangentially to the two lateral pedestals 22, 22 '. The latter are supported on the ground by their base 23 but, due to the flexibility of the structure and the use of the articulated joints 26, the upper element 21 tends to bend slightly by spreading the side pedestals 22, 22 ' which also flex and bear laterally on the embankment E. This must therefore be carried out in a particular way to participate in the resistance of the entire structure by taking the lateral thrusts

  applied by the two legs 22, 22 '.

  Usually, when the level of the platform 11 joins the natural level of the terrain 1, at point 13 of the longitudinal profile 10, the vaulted structure is stopped, the traffic lane A being made in the open air on the upper part of an embankment C or, even, on a viaduct. This results in discomfort for the environment and, in urban areas, it may be necessary to build noise barriers along both sides of the traffic lane

  A. Such an achievement is expensive and unattractive.

  According to the invention, instead of being stopped at the exit from trench B, the tubular structure 2 is extended by a structure of the same nature 3 which is shown in FIG. 3, this being a section

  transverse, along line III-III of Figure 1.

  To this end, a first embankment 4 is constructed, in the extension of taxiway A, the upper part 41 of which is leveled so as to form the platform.

  form 12 on which the tubular structure 3 is placed.

  In Figure 4, which is a perspective view of the assembly, there is shown, for simplicity, 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 lateral pedestals 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 placed therefore as an extension of these. The longitudinal joints 36 are therefore placed in alignment with the longitudinal joints 26 of the structure 2 and constitute, likewise, joints

  giving the structure a relative flexibility.

  In addition, each pedestal 32 is provided with a base 33

  bearing on the platform 12.

  In this way, sound insulation is achieved, even in the parts where the traffic lane A is at a level

higher than natural terrain.

  In addition, the traffic on track A thus covered is no longer visible from neighboring constructions F. These essential advantages can compensate, in urbanized areas, the additional cost due to the realization

of structure 3.

  As for structure 2, each lateral pedestal 32, 32 ′ preferably comprises an enlarged base 33 and a curved lateral wall 34 which tangentially connects to the upper element 31. The upper elements 31 and the pedestals 32 have the same profile as the similar elements 21, 22 of the buried structure 2 and can therefore be produced on the same molds. However, it is preferable to make some modifications to them to take into account the fact that the structure 3 is placed on the top of an embankment. First of all, it appears that the side walls 32, 32 ′ must resist by themselves the loads applied by the upper element 3. This is why it is advantageous to conform them so as to be rigid enough not to flex under load. To this end, each pedestal element 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 upper seal 36. The pedestal 32 thus stiffened can therefore transmit the loads in a vertical direction without lateral support

on the embankment 5.

  On the other hand, the base 33 of each pedestal 32 can be widened inwards and outwards to take account of the bearing capacity of the first embankment 4 which risks being less than that of the platform 11 provided in the bottom of trench B, i.e. on the

natural land.

  It should be noted, in fact, that prefabricated elements of this type, even for a large span, can be produced at a site remote from the site and transported by road, each element being able to be placed lengthwise on a trailer. For large dimensions, it is therefore advantageous to calculate the elements so as to lighten them as much as possible and, insofar as a stiffening rib is added to a pedestal, it may be preferable to reduce the width of the sole by providing for a possibility of widening it, after installation,

  to give it the necessary seating surface.

  To this end, as shown in FIG. 5, provision can be made, during the manufacture of the wall elements, to allow protruding reinforcements 42a on the two sides, respectively external 33a and internal 33b, of the base 33 , 42b. Thus, the weight of the pedestal element can be reduced so as to remain compatible with the transport capacities. After the elements have been laid, it is possible, using appropriate formwork, to pour extensions 44a, 44b on each side of the base 33 so as to widen the latter to reduce the loads applied to the embankment 4. By thus reducing the width of the sole 33, it is possible to compensate for the increase in weight due to the rib 37. Furthermore, longitudinal reinforcements 45 covering several successive pedestal elements can be threaded into the waiting reinforcements 42 so as to produce a longitudinal beam connecting the elements, allowing them to better

  resist differential settlement.

  To further increase the seating surface, it is also possible to pour, between the internal sides of the two pedestal elements 32, 32 ′, a raft 43 provided with the necessary reinforcement

  and in which the waiting reinforcements 42b are embedded.

  To simplify Figure 3, there is shown a work carried out on natural terrain 1 substantially horizontal. In practice, however, the slope line of the ground, in a direction orthogonal to the longitudinal axis of the structure, can be more or less inclined relative to the horizontal, between an upstream slope 16 and a downstream slope 15. As shown, by way of example, in FIG. 6, it follows that, in the zone or platform 11 passes above the level of the natural terrain 1, the side of the structure turned towards the downstream side must be laid on an embankment 61, while the side facing upstream

  rests on the bottom of a trench 62 made of cuttings.

  The structure according to the invention is particularly suitable for such a situation. In fact, as indicated above, the use of prefabricated pedestals 32 resting on a very wide sole and on which the upper element 31 rests by means of a longitudinal articulation 36 makes it possible to resist differential settlement particularly well. who

  may result from such asymmetrical support.

  In Figure 6, there is shown, by way of example, a structure with two arches of the type described in document EP-A-0.202.256, which is particularly suitable for the construction of motorways and comprises at least two lanes of traffic Sl, S2 on either side of a central pedestal 63 on which two upper elements, respectively 64, 64 'rest, which bear outwards, each on a lateral pedestal, respectively 65 on the side

upstream and 65 'on the downstream side.

  The embankment 5 which covers the entire structure and connects to the natural terrain as shown in Figure 6, is asymmetrical, but this does not affect the stability of the structure, the loads being transmitted vertically by the 65, 65 'legs made rigid by

the ribs 37.

  Figures 3 and 6 show another improvement of the invention. Indeed, it is advantageous, as indicated in FIG. 3, to provide on the lateral side of each upper element 31, a concrete veil 38 which extends upwards so as to retain the upper part 51 of the embankment covering the 'work. So, this one is always covered with a sort of cap in

  earth whose weight increases the stability of the whole.

  Preferably, the retaining veil 38 is perpendicular to the lateral side of the wall element 31 and,

  therefore, parallel to the joint plane P1.

  In the case of a single-section structure shown in FIG. 3, the upper element 31 can be provided with two webs 38, 38 ′ formed on each of its sides. On the other hand, in the case of a structure with two sections, each upper element 64, 64 'is provided with a retaining veil 38 only on its external side resting on a lateral pedestal 65, 65', the internal sides of the two elements 64, 64 'resting symmetrically on the pedestal

central 63.

  It should be noted that the prefabricated elements which have just been described have numerous advantages which justify their application to other situations. For example, in the usual case of a work carried out in the bottom of a trench, the lateral support of the piers on the embankment requires the creation of an embankment capable of withstanding these lateral thrusts. Thanks to the invention, on the other hand, if one uses the reinforced type of sidewalls described above, the backfill must no longer be made in a particular way and can be reopened if necessary. It is therefore possible to pass there conduits 67 which can be laid even after the completion of

the book.

  This advantage is particularly interesting in urban sites because it frees up space on each side of the structure. Such sidewalls can therefore advantageously be used, even for a structure 2

  carried out, in a conventional manner, on the bottom of a trench.

  However, in the case shown in FIG. 6 of a structure produced on an asymmetric terrain, the part of the embankment between the upstream pedestal 65 and the slope 16 can be produced so as to collect the lateral thrusts. Pedestal 65 could therefore have been made without

  rib, like a pedestal 22 of structure 2.

  Figure 7 shows another embodiment of a structure with two lanes of traffic in the case of an oblique exit in inclined natural terrain. It may then be advantageous to first stop the section S'2 of the structure located on the downstream side and to extend for a certain time the section S'l located on the upstream side and which is alone covered with a slope 51 '. The latter is advantageously stopped by an inclined veil 38 'formed on the side facing the slope of the upper element 66 which rests on the central pedestal 63'. The latter may consist of a solid wall or a row of pillars surmounted by a sill and comprises, on the upstream side, a single support member 36 for the upper element 66 covering the section S'l. On the downstream side, the upper part of the central element 63 ′ advantageously constitutes an inclined face 68

support of the retaining veil 38 '.

  Furthermore, even in the case of a work carried out in a trench and entirely covered with an embankment, it may be advantageous to provide ribbed pedestals at the outlet of the work, in particular when the latter is

  formed at an angle to the embankment covering it.

  For example, there is shown in Figures 8 and 9 the output of such a structure 7 passing, for example, below a traffic lane 14 formed on an embankment E and whose longitudinal axis forms a non-right angle with

axis 70 of the structure 7.

  In current section, the structure consists, like the structure 2 of FIG. 2, of successive sections each comprising an upper element 21 resting on two lateral pedestals 22, 22 ′ which can take lateral support on the embankment E covering the work. However, the embankment E is limited by an inclined slope E 'which has been removed in FIG. 9 and the edge of which is indicated in phantom. Usually, at the outlet 7 of the structure, the side walls 72, 72 'of the last section 71 are extended by prefabricated walls 73 having the same

  tilt as the slope, for the maintenance of land.

  We see that, in particular on the side closest to the bottom of the slope, the pedestal 72a cannot rest on an embankment whose height is insufficient. In this case, to collect the lateral thrusts applied by the upper element 71, the two side elements 72, 72 'must sometimes be connected to their base by a connecting beam extending between the two flanges 73, 73'. This can have drawbacks, for example for the realization of a road passing inside the structure 7 which can be avoided by using, at the two ends where the height thereof is insufficient, ribbed pedestals of the type described above and which collect by themselves the loads applied without having to take lateral support on

the embankment.

  As shown in FIG. 9, the adjacent pedestals 72a, 72b of the last two sections can be provided with ribs 37 while, on the other side, only the extreme pedestal 72'a is ribbed, the pedestal 72 ' b the penultimate section resting on an embankment

  of sufficient height to absorb the thrust.

  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 which can be imagined without departing. of the protection framework defined by

the revendications.

  In particular, it is advantageous to use, for the construction of the structure, wall elements with an enlarged sole, but it may be preferable to connect the bases of the two piers, by a concrete slab allowing the load to be distributed on a base. unique with a very large seating area. On the other hand, as indicated above, in the embodiments described in the previous patents, the sidewalls were dimensioned and reinforced so as to present a certain flexibility by leaning laterally on the embankment. In the invention, on the other hand, the entire applied load is transmitted by the pedestal on its sole and this results, for the same passage section, an increase in the compressive stresses applied to the concrete. Therefore, in order not to be obliged to increase the thickness of the side wall and, consequently, the weight of the sidewalls, it may be advantageous to produce the elements in high performance concrete having a compressive strength.

significantly increased.

  It should also be noted that for low spans, for example, the passage section could be rectangular, the structure consisting of flat slabs

  resting on vertical legs.

  The reference signs inserted after the technical characteristics mentioned in the

  claims are intended only to facilitate the

  understanding of them and in no way limit them

the scope.

Claims (10)

  1. Tubular work consisting of prefabricated wall elements arranged one after the other on a laying surface (A) so as to form a resistant tubular structure (D) having a longitudinal axis (O) and comprising , in cross section with the axis (O), at least three elements, respectively two side elements (32, 32 ') forming piers each having a substantially vertical wall (34) having an upper edge and a base (33) with flat lower face resting on the laying surface (A), and at least one upper element (31) with curved profile resting on the upper edges respectively, of the two pedestal elements (32, 32 ') along two longitudinal joints (36, 36 ') and tangentially connecting to the upper parts (35, 35') of said legs (32, 32 ') so as to form a continuous arch for the transmission of loads on the bases (33, 33') of said legs (32, 32 '), characterized in that at least ins some of the pedestal elements (32, 32 ') are shaped so as to have sufficient rigidity to collect and transmit the loads applied without lateral support on a embankment covering the structure.   2. Tubular structure according to claim 1, characterized in that at least some of the pedestal elements (32, 32 ') are each provided with at least one stiffening rib (37) extending over at least one face. of their side wall (34) and capable of opposing a deformation thereof under the effect of the applied loads by the upper element (31).   3. Tubular structure according to one of claims   1 and 2, characterized in that each longitudinal joint (36, 36 ') between a pedestal element (32) and the upper element (31) constitutes an articulation with an axis longitudinal.   4. Tubular structure according to claim 3, characterized in that each longitudinal articulation (36) is centered on a joint plane (Pl)   inclined to the vertical.   5. Tubular structure according to one of claims   previous, characterized in that each pedestal element (32) has an enlarged base (33) extending on either side of a substantially vertical side wall (34) having an upper part (35) curved on the side of the axis (O) of the structure, so as to connect tangentially to the corresponding side of the element upper (31).   6. Tubular structure according to one of claims   above, characterized in that each pedestal element (32) is provided with at least one stiffening rib (37) formed on the outside of the side wall (34) and extending from the base (33 )   substantially to the level of the longitudinal joint (36).   7. Tubular structure according to one of claims   above, characterized in that the base (33) of at least some of the pedestal elements (32) is provided, on at least one lateral side (33a), with waiting frames (42) capable of being embedded in poured concrete after the element has been laid to widen (44) the seat surface.   8. Tubular structure according to one of claims   above, characterized in that it is at least partially covered with an earth cap (51) consisting of a minimum thickness of fill maintained on at least one side of the upper element (31), by a rigid veil (38) extending upward from said side   9. Tubular structure according to one of claims   previous, comprising at least two sections (S1, S2) joined on either side of at least one central pedestal (63), each section comprising an upper element (64) resting, on one side on the central pedestal ( 63) and on the other on a lateral pedestal (65), characterized in that, the upper elements (64, 64 ') respectively covering the two sections (Sl, S2) are each provided with a rigid veil (38 , 38 ') extending upwards from the external side of the upper element (64, 64'), the internal side resting on a lateral pedestal (65), to maintain a thickness of fill (51 ) above the book. 10. Tubular structure according to claim 9, characterized in that, at the exit from a ground whose surface is oblique with respect to the longitudinal direction of the structure, one of the sections (If) is extended relative to the other (S'2) and is covered by an upper element (66) provided, on the side bearing on the central pedestal (63 '), with a rigid veil (38') extending towards the top for maintaining an embankment (51 ') up to the level of the central pedestal (63'), the upper part of the latter forming, on the upstream side, a support (36) for the upper element (66) and, on the downstream side, an inclined face (68)   support of the veil (38 ') for maintaining the embankment (51').