EP0774027B1 - Underground passage - Google Patents

Description

The present invention relates to a conduit underground to create a passage for a track traffic or for a watercourse, for example.

It is well known to make such a conduit underground by assembling prefabricated elements, these elements for constituting tubular sections of ducts which are arranged side by side along an axis longitudinal.

In particular, it is known from the document entitled "Vaulted lower passages" of 1978, edited by the general direction of inland transport of French Ministry of Transport, to carry out a work having either a raft or two support flanges parallel, on which shaped elements rest arch.

For small cross-sections, the elements forming the vault of the work can be of section substantially hemi-tubular. However, as soon as the width at the base of the structure exceeds approximately five meters or that its height exceeds about three meters, it becomes impossible to manufacture and transport to the site of such items. We then realize the vault by assembling many elements. In general, a section of pipe is consisting, in addition to the raft or the soles, by two elements forming a vault, called "half-shells", the lower longitudinal edges are engaged in grooves in the raft and whose edges upper longitudinal sections have reinforcement outgoing and are assembled by keying and pouring a sill.

This document shows a possibility of assembling two half-shells, consisting of mounting a scaffolding on the raft or between the soles, in front of the wrench vaulted.

This solution is not used in practice, because it would be extremely tedious to position the scaffolding over the entire length of the structure, carefully put the two half-shells in press simultaneously on this scaffolding, to operate the keying and sinking the sill and then removing the entire scaffolding.

The commonly used technique is to place the half-shells pressing against each other with interlocking at their longitudinal edges superiors, to key outgoing armatures, making protruding upwards, by means of longitudinal reinforcements, to build a formwork around these reinforcements, and to pour a concrete sill in this formwork.

This technique has the disadvantage of being relatively complex and time consuming to implement. Of plus, the reinforcement and the assembly beams half shells are located outside the curvature median of the half-shells, at which are mainly exerted the constraints undergone by these. As a result, significant efforts generated by the weight of the embankments are cantilevered on these stringers, which can affect the assembly prefabricated elements and therefore the resistance in the time of the work.

In addition, it appears that transverse efforts particularly important are exerted on the sill when backfilling the sides of the structure. These constraints can lead to the creation of cracks in the sill, affecting its long-term resistance term.

British patent application GB 2 254 350 describes a work with half shells assembled as a key vault by transverse tie rods and concrete pouring. Each half-shell includes a projecting spoiler, the two spoilers coming to bear against each other after assembly, to allow the clamping of the tie rods. The residual gap between the spoilers is plugged, before pouring of the concrete, by a sealing putty.

The installation of the tie rods is relatively long and complex to achieve. In addition and above all, the above problem of cracking the sill and transverse forces exerted on it are not resolved.

Patent application No. FR 2 682 141 describes a process for making a construction joint between two prefabricated elements, consisting in providing at least one elements of a spoiler protruding beyond its surface end, this spoiler being made of concrete molded in one piece with this element and delimiting one side of the joint area; to have shims made of material elastic between the end surface of an element and looped reinforcement of the other element; to place the end of the spoiler of an element against the part correspondent of the other element, with interposition of sealing means; and to use concrete to bond to low shrinkage.

The purpose of the holds is to obtain a "monolithism" flawless joints, allowing, before setting concrete, a certain freedom of compaction of the elements to assemble, thanks to elastic shims. After taking concrete, the forces are transmitted via the concrete, which is in homogeneous contact with the surface end of the elements.

Therefore, the elements are directly in contact with each other, and this "monolithism" of joints does not solve the above problem transverse stresses exerted on a sill keystone assembly. Such a sill is not, moreover, in no way described by this document. At on the contrary, the elastic support of the elements is not conceivable only for joints made on the sides of the structure.

The present invention aims to solve the aforementioned specific problem of transversal efforts particularly important exerted on a sill of keystone, when installing embankments on the sides of the work. The invention aims, in a way general, to provide an underground conduit perfectly resistant over time to the forces exerted on it by embankments, while being simple and quick to build.

The conduit that the invention relates to includes, in known manner, a raft or support soles on which are based prefabricated elements, called half-shells, making it possible to constitute a vault, these elements being assembled to each other longitudinally and transversely, at the key vault, by a concrete sill cast in situ, and comprising outgoing reinforcement as well as walls protruding, called spoilers, protruding from the elements interior side, these spoilers extending beyond the ends of the outgoing reinforcement, facing each other others when these elements are placed in position assembly and delimiting, with the longitudinal edges elements, a groove in which concrete can be poured to form the sill assembly.

According to the invention, the length of the spoilers is such that the ends of these spoilers are located, after assembly, at a distance from each other sufficient to never come into contact with each other the others when the half-shells are deformed by the installation of embankments.

The Applicant has in fact found that the half-shells more or less deform upwards when placing backfill on the sides of the book. As a result, the half-shells act on the sill like levers around the bearing surfaces of the half-shells against each other others, located below the sill.

Thanks to the invention, the spoilers do not come in contact with each other, so that the elements are not directly in contact with one another the other. No leverage occurs during the deformation of the elements, and no effort in overhang is not passed on to the sill by the elements.

Outgoing frames and frames longitudinal keying are advantageously located in the extension of the wall of the elements, that is to say in places where efforts are mainly exerted resulting from the stresses suffered by the elements, which ensures a particularly solid and resistant assembly in time.

Preferably, the outgoing reinforcements form loops through which the longitudinal reinforcement can be implemented by engagement.

Advantageously, studs forming spacers are inserted between the end faces of the spoilers. These studs allow to maintain a minimum space between these end faces, the time of the installation of the reinforcement and sill reinforcement. These items are then removed.

According to a preferred embodiment of the invention, the elements are kept in their assembly position, before reinforcement keying and sinking the sill, using one or more rigid longitudinal plates, which are fixed, with possibility of play, spoilers and which connect them one to the other. Preferably, the elements include threaded bushings embedded in their thickness substantially at the base of the spoilers, allowing the setting place of screws ensuring the fixing of said one or more plates.

By the way, the lower longitudinal edges elements coming to bear on the raft or on the soles include support pads between which outgoing reinforcements protrude, in continuation of the wall of these elements, these studs and reinforcements being intended to be embedded in concrete poured on site, after possible installation of additional reinforcements, in order to constitute the raft or the soles.

Thus, a perfect connection with embedding is obtained between the arch elements and the raft or the support soles.

Preferably, the studs comprise nipples, protruding from their underside, intended to be engaged in positioning holes arranged in the slab cast in place, intended to support the conduit. The engagement of these nipples in these holes allows a precise provisional positioning of the ends of the elements, the time to pour the concrete coming to drown the studs and outgoing frames.

For its understanding, the invention is to new described below, with reference to the drawing schematic annexed representing, by way of example not limiting, a preferred embodiment of the conduit underground it concerns.

Figure 1 is a perspective view, with partial removal; and

Figures 2 and 3 are sectional views, enlarged scale, assemblies between these elements constitutive.

Figure 1 shows an underground pipe 2 allowing the construction of a passage for a traffic or for a stream, for example.

The conduit 2 comprises two support flanges 3 resting on a slab 4 and two elements 5, or "half-shells", constituting, when assembled, a arch supporting the embankments 6.

The half-shells 5 are assembled one to the other at the keystone, and are assembled soles 3.

Figure 2 shows the connection of the half-shells 5 to each other at the keystone.

With reference to this figure, it appears that the assembly edge 5a of each half-shell 5 comprises outgoing frames 10 forming loops, arranged in the extension of the wall of the half-shell 5, and includes a wall, or "spoiler", 11 projecting from the inner shell 5 extending beyond the end of the outgoing reinforcement 10.

In addition, each half-shell 5 comprises threaded inserts 12 embedded in their thickness substantially at the base of the spoilers 11.

It appears in Figure 2 that the ends of these spoilers 11 are located, after assembly, at a certain distance from each other, explained more far.

Figure 3 shows the connection of the half-shells 5 at the level of the support plates 3.

As it appears with reference to this figure and in figure 1 the longitudinal edges lower half-shells 5 include studs support 15 between which outgoing reinforcements 16 are projection, in line with the wall of the half-shells 5.

In addition, the underside of each pad 15 includes a stud 17, projecting perpendicularly relative to it, while slab 4 includes positioning holes 18, in which the pins 17 can be hired.

In practice, slab 4, made of lean concrete, is pouring on site, after completion of the earthworks adequate. The holes 18 are arranged during this pouring or drilled after the concrete has dried.

The half-shells 5 are then positioned above of slab 4, so as to engage the pins 17 in holes 18 and bring the ends of the spoilers 11 close to each other, as shown in the figure 2.

Hard polystyrene pads 20 are inserted between the end faces of the spoilers 11, then of the plates longitudinal metal 21 are fixed to the spoilers 11, with possibility of play, using screws 22 engaged in the threaded sockets 12.

After placing the plate 21, the spoilers 11 are held opposite each other and the half-shells 5 are placed in the assembly position. The spoilers 11 and the upper longitudinal edges 5a of half-shells 5 then define a groove longitudinal.

A sealing strip 25 is placed at the bottom of this groove so as to cover the existing space between the two ends of the spoilers 11. Reinforcement intermediate 26 and longitudinal reinforcement 27 are so put in place by engagement in the loops that form the outgoing reinforcements 10, in order to achieve a bonding of these, then concrete 28 is poured into the groove to constitute an assembly sill.

The pads 15 and frames 16 are then embedded in concrete poured on site to form the footings 3, after fitting any reinforcements additional.

Thus, once the half-shells 5 have been placed in their assembly position by fitting pads 20 and of the plate 21, it suffices to seal the groove thanks to the band 25, to connect longitudinally outgoing reinforcement 10 and pour concrete 28 into this groove to achieve the assembly of half-shells 5.

The distance between the ends of the spoilers 11 is sufficient so that these spoilers never come in contact with each other when the half shells are deformed by the placement of embankments on the sides of the book.

Thus, the half-shells 5 are not in abutment one against the other. No leverage occurs during the deformation undergone by the half-shells 5 under the weight of the embankments 6, and no effort in overhang is not transmitted to sill 28 by them.

Outgoing reinforcements 10 and reinforcements 26,27 in addition are found in the extension of the wall of the half-shells 5, that is to say where the efforts resulting from constraints undergone by them.

No scaffolding and no construction no special formwork is required to pour the sill 28, so the construction of duct 2 is performed quickly and easily.

The studs 20 form spacers allowing maintain a minimum space between the end faces spoilers 11 during the installation of the reinforcements 26,27 and the sinking of the sill. They are normally removed, as well as plate 21, after drying concrete. It is however possible to leave them in place without hard spots being created between the half-shells 5, due to their weak material resistant to compression.

The studs 15 and outgoing frames 16, once embedded in the concrete poured on site intended to constitute the soles 3, ensure a perfect connection with installation of the half-shells 5 and the support flanges 3.

The engagement of the nipples 17 in the holes 18 allows precise provisional positioning of the ends lower half-shells 5, the time that their assembly to one another and to the soles 3 is achieved.

Claims (8)

1. Underground conduit into which can be fitted a passage for a traffic lane, of the type including a foundation raft or sole plates (3) on which rest prefabricated elements (5), called half-shells, which allow the formation of an arch, these elements (5) being assembled on one another longitudinally and cross-wise, at the keystone level, by a concrete longitudinal beam cast on site, and having protruding reinforcements (10) as well as projecting walls, called spoilers (11), which project from the elements (5) on the inside, these spoilers (11) extending further than the protruding reinforcements (10) facing each other when these elements (5) are placed in their assembly position and delimiting, with the upper longitudinal edges of the elements (5), a groove into which concrete can be cast to make the assembly longitudinal beam, conduit characterised in that the length of the spoilers (11) is such that the ends of these spoilers (11) are located, after assembly, at a distance from each other which is sufficient for them never to be in contact with one another when the half-shells (5) are distorted by the laying of the embankments.
2. Underground conduit according to claim 1, characterised in that the protruding reinforcements (10) and the longitudinal keying reinforcements (256, 27) are located in the extension of the walls of the elements.
3. Underground conduit according to claim 1 or claim 2, characterised in that protruding reinforcements (10) form loops through which the longitudinal keying reinforcements (26, 27) can be engaged into position.
4. Underground conduit according to one of claims 1 to 3, characterised in that the blocks (20) which form cross struts are inserted between the end surfaces of the spoilers (11).
5. Underground conduit according to one of claims 1 to 4, characterised in that the elements (5) are kept in the assembly position, before the keying of the reinforcements (10) and casting of the longitudinal beam, by means of one or several rigid longitudinal plates (21) which are fixed, with an allowance for play, to the spoilers (11) and which link them one to the other.
6. Underground conduit according to claim 5, characterised in that the elements (5) include tapped bushings (12), sunk in their thickness approximately at the level of the base of the spoilers (11), which allows the fitting of screws (22) which ensure the holding of this or these plate(s) (21).
7. Underground conduit according to one of claims 1 to 6, characterised in that the lower longitudinal edges of the elements (5) which rest on the foundation raft or the sole plates (3) include support blocks (15) between which protruding reinforcements (16) stand proud, in the prolongation of these elements (5), these blocks (15) and reinforcements (16) being meant to be sunk in concrete cast on site, after the possible positioning of additional reinforcements, in order to make the foundation raft or the sole plates (3).
8. Underground conduit according to claim 7, characterised in that the blocks (15) have studs (17) protruding from their lower surface, which are meant to be slotted into locating holes (18) made in the slab (4) cast on site and intended to support the conduit (2).

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