EP0295175B1 - Hollow structure with flat base plate - Google Patents

Abstract

The invention relates to a tubular structure consisting of sections placed end to end and resting on a flattened and compacted laying surface (61). Each section is formed from juxtaposed wall elements comprising two side elements (2, 2') with an inwardly curved lateral wall, each bearing on the laying surface (61) by means of a stabilising member with a flat bottom, allowing the side element to stand up without scaffolding, characterised in that each side element (2, 2') is equipped at its base with a widened sole (7) comprising two wings (71, 72) extending horizontally in a projecting manner on either side of the lateral wall (20) of the element (2, 2'), the latter comprising a substantial vertical lower part (26) perpendicular to said sole (7) and extended upwards by an inwardly curved upper part (21). The present invention is used for conduits of very large cross-section which can be employed for the construction of underground passages for various uses. <IMAGE>

Description

a. _U nE

The invention relates to a hollow structure with a flat bottom resting on a flattened laying surface such as the bottom of a trench and made up of juxtaposed wall elements.

Structures of this type are already known, used in particular for the production of liquid circulation conduits such as sewers and of which, consequently, the cross section does not exceed 1 to 2 square meters.

However, the applicant has already proposed a new system for constructing conduits made of prefabricated elements described in European patent application 00 81 402. Such a system makes it possible to produce structures of much larger sections, which can even exceed 100 m ² and which can therefore be used for the construction of tunnels for vehicle traffic, the diversion of a river, etc.

According to one of the embodiments of the invention described in the aforementioned European application, the hollow structure is formed of tubular sections placed end to end and each consisting of a certain number of juxtaposed elements respectively a substantially planar radiating element placed on the ground or else cast in place, two side elements placed on either side of the slab and a vault element resting on the upper ends of the side elements so as to close the duct. Each side element has a curved wall of generally vertical orientation which connects tangentially upwards with the arch element and downwards, horizontally, with the radiant element so as to constitute a smooth wall whose the curvature varies continuously.

According to another characteristic, the longitudinal joints between the arch elements and the side elements on which they rest constitute articulations which make it possible in particular to leave the elements a possibility of slight displacements during the setting up and during the backfilling of the trench, the joints are then sealed. On the other hand, at their base, the side elements are secured to the floor by longitudinal joints constituting a real keying. In this way, all of the loads applied to the roof are transmitted to the side elements and taken up by the slab, the flat shape of which allows the load to be distributed over a large area. A considerable improvement is thus obtained in the distribution of the stresses generated in the soil.

To achieve this keying of the raft with the base of the side elements, during the installation of the latter, they are moved slightly apart from the raft so as to provide between the longitudinal edges vis-à-vis a space in which intersect reinforcements left waiting and which are then embedded in concrete. When molding the elements, the longitudinal edges must therefore be set back from the theoretical plane of the joint, which complicates production. In practice, it is necessary to cast the side elements in a horizontal position so that their base stands vertically upwards. In addition, the presence of these reinforcements which can be subjected to shocks during transport and the installation of the elements weakens the longitudinal edges and can be the source of cracks.

Furthermore, the concreting of the joints after laying lengthens the construction time, all the more since it is necessary to wait for the complete setting of the concrete before laying the vault elements so that the side elements, secured to the write off, better resist the risk of overturning. Moreover, after the commissioning of the conduit, variations in the applied stresses can still occur, in particular differential settlement, with the risk of formation, in the joints, of cracks which can cause leaks and corrosion of the reinforcements.

The present invention overcomes these drawbacks with improvements to facilitate and simplify the production and installation of elements for the construction of such hollow structures.

According to the invention, the two side elements and the raft element are provided respectively, along their longitudinal edges opposite, thinned ends in the form of short consoles having, respectively, inverted profiles providing longitudinal bearing faces inclined at the same angle, not zero, with respect to the vertical and, for the construction of a structural section, the side elements are positioned so that the distance between their internal edges is less than the width of the raft element and that the short consoles facing each other overlap each other, their inclined bearing faces applying in pairs one on the other, said consoles having a profile and mechanical characteristics determined to be capable of transmitting to the element to radiate at least part of the forces supported by the side elements or vice versa.

Preferably, the short brackets formed along the internal edges of the side elements pass over the short brackets formed along the longitudinal edges of the raft element. However, in certain particular applications, this arrangement can be reversed, the short brackets of the radiating elements passing over the short brackets formed along the internal edges of the side elements which surround it.

Generally, a seal is interposed between the inclined bearing faces applied one on the other of said short brackets.

In a more sophisticated embodiment, each side element is connected to the corresponding raft element by a plurality of spaced tie rods distributed along the longitudinal edges of the elements and crossing the short consoles vis-à-vis, said tie rods being subjected to a tension and bearing on the faces of said consoles opposite the inclined bearing faces so that the latter are applied under pressure to each other .

According to another advantageous characteristic, the stabilization members formed at the base of each side element are extended towards the outside of the structure by parts extending in console over a sufficient distance to oppose the risks of overturning the side element under the effect of the applied forces.

The base of each side element can moreover be constituted by a support sole extending over its entire length and comprising two wings extending transversely inwards and outwards.

• Fig.1 est une vue en coupe transversale d'un conduit fermé muni des perfectionnements selon l'invention ;
• Fig.2 est une vue de détail, en coupe transversale, d'un joint longitudinal entre un élément de côté et un élément de radier ;
• Fig.3 est une vue de détail, en coupe transversale, d'un autre mode de réalisation d'un élément de côté ;
• Fig.4 représente, en vue de côté, un mode de réalisation particulier d'un tronçon de la structure creuse ;
• Fig.5 est une vue de détail du joint entre un élément de côté et l'élément de voûte, en coupe selon la ligne A-A de la figure 4 ;
• Fig.6 représente schématiquement, en perspective, une application particulière de l'invention.

However, the invention will be better understood from the detailed description of certain particular embodiments, given by way of example and shown in the accompanying drawings.

• Fig.1 is a cross-sectional view of a closed conduit provided with the improvements according to the invention;
• Fig.2 is a detail view, in cross section, of a longitudinal joint between a side element and a raft element;
• Fig.3 is a detail view, in cross section, of another embodiment of a side element;
• Fig.4 shows, in side view, a particular embodiment of a section of the hollow structure;
• Fig.5 is a detailed view of the joint between a side element and the arch element, in section along the line AA in Figure 4;
• Fig.6 shows schematically, in perspective, a particular application of the invention.

In Figure 1, there is shown, in cross section, a closed conduit of the type described in European application 00 81 402. Such a conduit, which can be for example an underground passage for the circulation of vehicles or a circulation channel of liquid, is produced by combining tubular sections placed end to end and each consisting, in cross section of four prefabricated elements, respectively, a raft element 1, two side elements 2 and 2 ', placed on either side of the radiate 1 and an arch element 3 resting, along its longitudinal edges 31, on the upper ends 21 of the side elements. The side elements 2, 2 ′ and arch 3 are curved so as to give the duct the desired section. For example, in the embodiment shown, the upper parts 21 of the side elements 2 and the arch element 3 have the same center of curvature 0. But other shapes are possible provided that the centers of curvature of the arch element 3 and upper parts 21 of the side elements are centered in the joint planes PP ′ so as to maintain the continuity of the curvature.

Likewise, the lower parts 22 of the two side elements 2 are oriented so as to connect tangentially, in a substantially horizontal direction, to the longitudinal edges 12 of the raft element 1.

A closed conduit is thus defined having a smooth internal wall of ovoid shape with a flattened base which can be laid on the flattened and packed bottom 61 of a trench 6.

According to one of the essential characteristics of European patent 00 81 402, to facilitate construction, the side elements 2 are provided at their base with stabilizing members 23 defining horizontal planar bearing faces 24 allowing them to stand upright only without scaffolding on the laying surface 61. The advantages of such an arrangement are described in detail in the aforementioned European application.

The structure according to the present invention differs essentially from the previous embodiment by the fact that, when the elements are installed, the distance L between the internal longitudinal edges 40 of the two side elements 2 is less than the width L 'of the slab element 1, that is to say the distance between the longitudinal edges 50 of the latter, so that the ends 4 of the side elements 2 partially cover the ends 5 of the slab 1.

To this end, each end 4 of a side element 2 is tapered at an angle to form a short console of substantially triangular section providing a longitudinal face 41 inclined at an angle A not zero with respect to the vertical, as is shown in detail in Figure 2.

Each end 5 of the raft 1 is thinned in the same way but in the opposite direction and therefore has a longitudinal face 51 inclined at the same angle A relative to the vertical. The consoles 4 and 5 therefore have inverted profiles and can overlap each other when the elements are installed.

Preferably, the inclined faces 41 of the brackets 4 are turned downwards and the inclined faces 51 of the brackets 5 are turned upwards. Thus, when the two side elements 2, 2 ′ are placed on either side of the raft element 1, the two consoles 4 of the side elements cover the two consoles 5 of the raft 1, the faces d 'support 41 and 51 applying to each other. As a result, the two side elements bear along their internal edge on the raft element 1. The load applied to the upper part of the structure and taken up by the side elements is thus transmitted to the element of write off 1 and spread over the entire surface of the latter, a smaller part being transmitted directly to the ground by the stabilization members 23.

Of course, the profile of consoles 4 and 5 as well that the characteristics of the reinforcements 42, 52 with which they are provided must be determined so as to give the consoles 4, 5 the resistance necessary to withstand without risk of cracking the significant stresses resulting from the transmission of the load to the raft 1.

It will be noted that the reinforcements 42, 52 incorporated in the concrete are well protected and can be tighter than reinforcements simply protruding on hold.

In the embodiment which has just been described, the raft elements consisted of prefabricated panels, but it is possible to use a similar arrangement on a raft cast in place by simply providing faces along the longitudinal edges of the latter. tilt support corresponding to that of the side elements.

When the raft is cast in place, it is possible to give it a monolithic structure by providing overlapping reinforcements between the parts cast successively. This produces continuous support on the ground to maintain the alignment of the different sections of the upper part and to resist variations in the applied forces or differential settlement. In the case where the raft elements 1 consist of prefabricated panels laid flat on the ground, it is possible to offset the elements axially so that each transverse joint plane between the upper parts of two successive sections passes substantially to the center of a write-off element. In this way, the successive side elements are supported on the ground by means of the same raft element which thus opposes the possible effects of misalignment

Note also that the side elements 2 can also be used to maintain the raft 1 against an upward push under the effect of the water table in the case where the conduit is more or less submerged therein.

In certain applications, the side elements will thus simply be placed on the elements to be removed. However, it may be necessary to keep a certain connection between the elements, for example to resist misalignments caused by differential settlements or when the direction of application of the forces can vary. This is why, it can be advantageous, to avoid misalignments and guarantee sealing by maintaining the pressure of application of the consoles one on the other, to connect the side elements to the elements to be rafted by spaced tie rods 43 distributed along the longitudinal edges of the elements and passing through aligned orifices 44, 54, arranged vertically through the brackets 4 and 5 as shown in FIG. 2.

Each tie rod 43 is provided at its two ends with heads 47 bearing on the faces 46, 56 of the brackets 4, 5 opposite the inclined faces 41, 51 and is subjected to a prestressing tension determining the application under pressure one on the other of said inclined faces with crushing of the seal 45.

This avoids shifts of the side elements with respect to the raft during construction or under the effect of the applied forces.

However, in the previous embodiment, the keying of the lower joints made it possible to oppose the spacing outwards of the side elements 2, 2 ′ during the installation of the arch element 3 and of the embankment and the tie rods 43 may be insufficient, in certain cases, to fulfill this function. This is why, in a more improved embodiment, it may be advantageous to improve the resistance to the outward overturning of the side elements 2 by widening the seating surface of the stabilizing members 23. For this purpose, these will be extended outwards by parts 25 extending in consoles over a distance a sufficient.

However, it is also possible to modify the cross-sectional profile of the duct, for example in the case where the latter is not used for the circulation of liquid and where there is therefore no particular effort made to produce a rounded profile. In such an embodiment shown by way of example in FIG. 3, the side wall 20 of each side element 2 comprises a curved upper part 21 and a substantially vertical lower part 26 which rests on an enlarged base in the form of sole 7 comprising two wings 71, 72 extending respectively on each side and perpendicular to the vertical wall 26. The latter can also be widened at the base to increase the rigidity of the element 2. The wing internal 71 ends, as before, by a thinned end in the form of a console 4 which rests on the corresponding console 5 of the raft element 1. The external wing 72 makes it possible on the one hand to increase the resistance to overturning and on the other hand to increase the overall bearing surface of the conduit on the bottom 61 of the trench.

In addition, when installing the elements, it is possible, without waiting for the final backfilling, to cover the outer soles 72 with a certain amount of soil which, by spade effect, increases the stability of the side elements 2.2 '.

According to another characteristic making it easier to construct and install the elements, the longitudinal joints 8 between the arch element 3 and the side elements 2 can also be the subject of a variant shown in detail in FIGS. 4 and 5.

In fact, in patent application 00 81 402, two embodiments of these seals were described, one by articulated support, the other by keying.

However, it is advantageous to simultaneously use these two types of seals. Indeed, as can be seen in FIG. 4, the joint 8 between the upper part of the side element 2 and the arch element 3 is produced in a mixed manner and comprises two articulated supports 81 spaced apart from one other and preferably placed at the two ends of the elements 2 and 3. These articulated supports 81 are produced in the manner described in the previous patent application and therefore comprise rounded protruding parts 82, preferably formed at the lower ends of the arch element 3 and which rest on hollow parts 83 formed at the upper ends of the side element 2 axially. A seal is interposed between said support parts 82 and 83.

The articulated joints 81 extend over lengths (e) provided simply so that, overall, the load applied by the arch element (3) on each side element (2) is temporarily collected by said supports 81 without risk of 'crushing or cracking.

Between the articulated supports 81, that is to say over the remaining length e ′ of the section, the concrete walls of the side element 2 and of the arch element 3 end in end faces 28, 33 spaced from each other by a certain distance on either side of the joint plane P (FIG. 5) so as to provide a free space 84 in which the waiting reinforcements extend transversely 27, 34 , protruding from the ends of the two elements 2 and 3.

In this way, during the construction of a section of the structure, the vault elements 3 are first placed on the side elements 2 and 2 ′, providing the necessary seals between the bearing faces 82 , 83 and, according to one of the characteristics of patent 00 81402, the elements are allowed to position, the articulated supports allowing them to move relatively slightly. We then proceed to keying the joint by passing through the waiting frames 27, 34, longitudinal anchoring irons 35 and pouring a sealing concrete in the space 84 closed, on the opposite side, by a temporary formwork. The end faces 28 and 33 are advantageously inclined symmetrically with respect to the plane P so as to open in V towards the outside to facilitate concreting.

We thus combine the advantage of the articulated support which facilitates the installation of the elements and the sealed joint which ensures the final joining of the structure.

FIG. 6 shows a particular application of the invention to the production of liquid circulation channels and in particular of irrigation channels which may have a very large cross section.

As before, such a channel can be made up of sections placed end to end and each comprising a raft element 1 with a flat bottom interposed between two side elements 2 which can advantageously be produced according to the embodiment described above, each element side 2 being provided at its base with an enlarged sole 7 comprising two wings 71, 72 extending on either side of the vertical side wall 26. The channel thus formed, which can be used for the circulation of water or other liquid 14 can either be open upwards or be covered with a curved element 36 which, not having to support backfill, can be made in a light manner, for example in a corrugated plastic material giving it a certain stiffness. Such a cover 36 protects the transported water against pollution and reduces the risk of evaporation, in particular if the plastic material used is opaque.

Moreover, these risks are also reduced by the inwardly curved shape of the side elements 2 which, for an equal transported volume, reduces the free surface of the liquid 14.

It will be noted that, in this case, the side elements 2 exert on the ground a push corresponding simply to their own weight and which is distributed over the entire lower surface of the sole 7. On the other hand, the conduit is normally not placed in a trench but in a simple recess to reach the right soil. The risk of vertical thrust on the raft 1 under the effect of the water table is therefore reduced and the raft is subjected essentially to the load of the water 14 transported.

Furthermore, the thrust of the water 14 on the side walls 2 which are no longer interconnected by the arch element, tends to overturn them towards the outside. It may therefore be advantageous, in this case, as shown in FIG. 6, to reverse the arrangement of the brackets 4 and 5 so that the brackets 5 formed along the longitudinal edges of the raft 1 cover the brackets 4 constituting the internal edges of the sole 7 of the side elements 2. The latter therefore resist the effects of overturning outwards under the pressure of water 14, on the one hand thanks to the parts 72 of the sole 7 projecting towards the 'exterior and covered by the embankment R, and secondly through the blocking effect of the raft 1 itself subjected to the weight of the water transported.

Note, moreover, that the inwardly curved shape of the side elements 2 also promotes stability by reducing the value of the horizontal force of thrust of the liquids.

It can be seen that the invention can be the subject of numerous variants and that it is therefore not limited to only the embodiments which have just been described by way of example, other variants and other improvements which may be imagined without departing from the protective framework defined by the claims.

Claims (14)

1. Hollow structure with flat bottom resting on a flattened and compacted laying surface (61) and consisting of juxtaposed wall elements comprising at least one substantially plane raft element (1) and two lateral side elements (2, 2') equipped respectively with stabilising members (23, 7) allowing them to stand upright on the laying surface (61) and arranged on either side of the raft element (1), each side element (2) defining a lateral wall (20) connected horizontally to the raft element (1) along an inner longitudinal edge (40) confronting a corresponding longitudinal edge (50) of the raft element (1), characterised in that the two side elements (2, 2') and the raft element (1) are respectively equipped, along their mutually confronting longitudinal edges (40) (50), with thinned ends in the form of short brackets (4) (5) possessing respectively inverted profiles forming longitudinal bearing faces (41) (51) inclined at the same non-zero angle (A) relative to the vertical, and in that, at the laying of the elements (1, 2), the distance (L) between the inner edges (40) of the two side elements (2, 2') is smaller than the width (L') of the raft element (1), in such a way that the mutually confronting short brackets (4) (5) overlap one another and that their inclined bearing faces (41) (51) are laid two by two onto one another, the said brackets (4) (5) having a profile and mechanical characteristics so determined as to allow them to transmit to the raft element (1) at least some of the forces borne by the side elements (2, 2'), or vice versa.

2. Hollow structure according to Claim 1, characterised in that the short brackets (4) formed along the inner edges (40) of the side elements (2) pass over the short brackets (5) formed along the longitudinal edges (50) of the raft element (1).

3. Hollow structure according to Claim 1, characterised in that the short brackets (5) formed along the longitudinal edge (50) of each raft element (1) pass over the short brackets (4) formed along the inner edges (40) of the side elements (2, 2') which frame it.

4. Hollow structure according to one of the preceding claims, characterised in that a gasket (45) is interposed between the bearing faces (41) (51), laid onto one another, of the said short brackets (4) (5).

5. Hollow structure according to one of the preceding claims, characterised in that each side element (2, 2') is connected to the raft element (1) by means of a plurality of spaced ties (43) distributed along the longitudinal edges of the elements (1) (2) and passing through the mutually confronting short brackets (4) (5), the said ties (43) being subjected to a tension, whilst at the same time bearing on the faces (46) (56) of the said brackets (4) (5) opposite the inclined faces (41) (51), in such a way that the latter are laid under pressure onto one another.

6. Hollow structure according to one of the preceding claims, characterised in that the stabilising parts (23, 7) of each side element are extended towards the outside of the structure (10) by parts (25, 72) extending by projection over a distance (a) sufficient for preventing the risks that the side element (2) will overturn under the effect of the forces exerted.

7. Hollow structure according to Claim 6, charao- terised in that the lateral wall (20) of each side element (2) comprises a substantially vertical lower part (26) and rests on a widened sole (7) comprising two wings (71, 72) respectively extending horizontally inwards and outwards on either side of the lateral wall (20).

8. Hollow structure according to one of the preceding claims, characterised in that it consists of a series of successive sections juxtaposed in a longitudinal direction so as to form an elongate conduit.

9. Hollow structure according to Claim 8, characterised in that each section comprises at least one arch element (3) resting on the two side elements (2, 2') so as to form a closed tubular conduit

10. Hollow structure according to Claim 8, characterised in that each section comprises a raft element (1) and two side elements (2, 2') made of concrete, so as to form an upwardly open channel for the circulation of liquid.

11. Hollow structure according to Claim 10, characterised in that the channel is covered by a curved element (36) made of light material and resting on the upper ends (21) of the side elements (2) (2').

12. Hollow structure according to Claim 9, characterised in that each longitudinal joint (8) between a lower edge (31) of the arch element (3) and the upper edge (21) of the corresponding side element (2) (2') comprises at least two articulated stays (81) which are located at an axial distance from one another and between which the end faces (28) (33) of the side element (2) and of the arch element (3) are formed set back relative to the mid-plane (P) of the joint (8), so as to provide a free space (84), in which there extend transversely stand-by reinforcements (27) (34) associated with anchoring bars (35) arranged longitudinally, the assembly as a whole being fixed together by means of a sealing mortar poured into the said free space (84).

13. Hollow structure according to Claim 12, characterised in that the articulated stays (81) extend respectively over distances (e) substantially sufficient for transmitting the load exerted by the arch element (3).

14. Hollow structure according to Claim 12, characterised in that each articulated stay (81) consists of rounded projecting parts (82) formed on the lower ends (31) of the arch element (3) and bearing on recessed parts (83) formed on the upper ends (81) of the side elements (2), a gasket being interposed between the said bearing parts (82, 83).

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