EP1062392B1 - Structure for passage under an embankment - Google Patents

Description

The invention relates to a passage under embankment likely to have a very large section, corresponding in particular to the road gauge, such a work being used in particular for the passage under embankment of a road or rail traffic.

Technical developments, in particular the need to build new traffic lanes, such as highways or high-speed rail lines, have led to more frequent overflights. Indeed, a railway line or a motorway must have a regular long profile, without major ramp and requires, in addition, the removal of intersections.

For some time now, it has been necessary to construct traffic lanes on an embankment that matches the profile, which requires the construction of numerous structures for the passage of secondary traffic lanes, railway lines and rivers.

To solve such problems, the inventor proposed, a few years ago, to make embankment underpass by a new technique that has many benefits and has experienced great development.

This technique which is described, in particular, in the European patents No. 0,081,402 No. 0,244,890 and No. 0 296 013 of the same inventor, consists in producing a tubular wall consisting of prefabricated concrete elements which are made of In advance, transported to the site when the prefabrication plant is remote, and assembled on the construction site, the assembly is then covered with a backfill.

In general, the tubular wall is centered on a longitudinal axis and comprises, in cross section, at least three prefabricated elements, respectively an upper element in an arc of a circle, resting on two side elements spaced apart from one of the another and each comprising a base resting on the ground and a side wall having an upper portion curved inwardly of the section so as to connect to the upper member.

The previous invention makes it possible to achieve very economically works that can have a very large section of passage corresponding to the road gauge. It has even been possible to achieve very economically works covering several roads, for example, for bypass roads in a city that can advantageously be buried in order to protect the environment.

European Patent No. 0.585.959 also describes a buried conduit comprising, in cross section, an upper element in a circular arc or possibly in a basket handle, which rests, by joints on two prefabricated bearing elements.

Of course, it is more economical to use, as much as possible, standard elements whose characteristics and performance are known and, in practice, works are usually carried out with a semi-circular section, comprising two side elements having a part upper curved in an arc and connected to an upper element of the same radius of curvature. In the most common embodiment, the upper element covers a circular sector of 90 °, such that the joint planes between the side elements and the upper element are inclined symmetrically by 45 ° with respect to the vertical.

Longitudinal joints usually consist of simple horizontal axis joints and it has been observed that such a provision to make works of very large section and able to support a heavy load, for example the circulation of a highway lane above the structure.

However, the use of a semi-circular section leads to give the structure a relatively large height relative to its width since it is equal to about half of it.

To increase the range between the side elements, the inventor has therefore proposed to use elements of different radii, the upper element, which still covers an angular sector of 90 °, having a greater radius than the curved parts of the radii. elements of sides. In this way, the same arrangement of articulated joints between the elements is maintained, but the range between these articulations can be increased. However, the deflection of the circular arc is proportional to the distance between the support and, because of the large radius required, the raising of the key relative to the lateral supports may be too important to use this technique when the difference in height between the background on which is placed the work and the way of circulation passing over it is insufficient.

In such a case, it is possible to produce passageways of rectangular section consisting of a slab resting on two vertical walls, but the technique of prefabrication can only be used for reduced cross sections, of the order of 10 to 15 m ² . In fact, for larger dimensions, prefabricated elements would no longer be manageable and it is then necessary to use conventional bridge construction techniques.

The object of the invention is therefore to extend the possibilities of application of the technique of construction of structures by prefabricated elements described in the aforementioned patents of the same inventor, by making it possible to reduce the total height of the work relative to its scope, while retaining the essential advantages of the prior art.

The solution to this problem is an embankment work as defined in claim 1. Advantageous embodiments are defined in claims 2 to 4.

The invention thus generally relates to a backfill structure comprising a tubular wall having a longitudinal axis and consisting of a plurality of concrete elements made in advance and juxtaposed along longitudinal joints and transverse, said elements being assembled on the construction site so as to form a tubular wall comprising, in cross-section at its axis, at least three prefabricated elements, respectively an upper element having two lateral sides parallel to the longitudinal axis and two elements spaced apart from each other and each comprising a base resting on the ground and a side wall having an upper portion curved inwardly of the section, with an upper edge parallel to the longitudinal axis, the element upper resting by its lateral sides along longitudinal joints, on the upper edges of the side elements.

According to the invention, each upper element comprises a cylindrical wall generatrices parallel to the longitudinal axis and having a transverse profile with double curvature comprising a flat central portion extended by two end portions each having the same radius of curvature as the upper part. curved side element corresponding, so as to connect tangentially thereto, said double curvature wall being associated with at least one stiffening rib capable of withstanding the stresses resulting from the self weight of the upper element and the load applied by the backfill covering the tubular wall.

The zero curvature of the central part of the central part of the upper element and the dimensions of the elements are such that the total height of the structure does not substantially exceed that of a rectangular section structure limiting the same height to the rib not exceeding that of a planar deck limiting the jig, the stiffening rib having a moment of inertia sufficient to give the upper element the necessary bending strength, given the distance between the lateral sides and applied loads.

Particularly advantageously, the lateral sides of the upper element and the upper edges of the side elements are provided with mating bearing parts, respectively recessed and protruding, so as to provide two articulated longitudinal joints, the tangential connection of the bearing portions of the upper member with the side members determining the transmission of the bearing forces, in each longitudinal joint, in directions inclined with respect to the horizontal, with a horizontal component directed outwards.

Preferably, the longitudinal joint plane between the upper edge of a side member and the lateral side of the upper element bearing on it, passes through a common center of curvature and is inclined substantially at 45.degree. horizontally.

• La figure 1 montre schématiquement, en coupe transversale, un ouvrage sous remblai selon l'invention.
• La figure 2 est une vue de détail d'un joint longitudinal.
• La figure 3 montre une variante.

But the invention will be better understood by the following description of a particular embodiment, given by way of example and shown in the accompanying drawings.

• Figure 1 shows schematically, in cross section, a work under embankment of the invention.
• Figure 2 is a detail view of a longitudinal joint.
• Figure 3 shows a variant.

FIG. 1 schematically shows, in cross-section, a passage structure according to the invention, comprising a tubular wall 1 disposed on the bottom 11 flattened and packed with a trench 10 and covered with an embankment 12 until at a higher level 13 at a height h above the bottom 11 of the trench 10, to allow the passage of a traffic lane above the structure.

The tubular wall 1 generally consists of prefabricated reinforced or prestressed concrete elements, which are juxtaposed so as to form successive sections centered on a longitudinal axis O.

Such an arrangement has been described in detail, in particular in the previous patents EP-0.081.402. and EP-0,244,890 of the same inventor.

In general, each section comprises, in cross section, at least three elements, respectively two side members 2, 2 'and an upper element 3, having two lateral sides 31, 31', parallel to the longitudinal axis O of the structure, which rest on the upper edges 21, 21 'of the side elements 2, 2'.

Each side member 2, 2 'comprises a sole 22 forming a flat bottom base 22 and a side wall 23 extending upwards, curving inwardly at least at its upper portion 24. The assembly is balanced in such a way that the prefabricated side element 2 can be placed on the ground and stand by itself without scaffolding, even under the weight of the upper element 3.

In the embodiments described in the previous patent EP-0,081,402, the bases of the side elements are connected by a concrete base which makes it possible to distribute the load applied over a large area. However, the raft can be removed if the lift of the bottom 11 of the trench allows it and, in particular, when the scope of the work between the bases of the side elements 2, 2 'is important.

In this case, each side element has the particular shape shown in Figure 1, the sole 22 comprising two wings 22a, 22b respectively extending outwardly and inwardly of the section, on either side the foot of the side wall 23 over a width determined according to the lift of the ground and stability conditions. Although the wall 23 is curved inwards, experience has shown that such an element can be perfectly stable, even for very large spans.

The structure described in the previous patent EP-0.081.402 has experienced a great industrial development because of the many advantages brought by this original technique of construction of structures.

In particular, the cutting of the passage section is achieved, according to patent EP-0,081,402, way that the longitudinal joints between the elements are placed in zones of stress nodes whose positions are determined by studying the influence of the loads applied. Thus, one can achieve elements as large as possible and thus reduce the number of elements to achieve the desired passage section.

Experience has shown that in the case of a semi-circular arch, these joints could be placed so that the two joint planes between the upper element and each side element are inclined by 45 ° with respect to the horizontal.

Furthermore, it is particularly advantageous to provide articulated joints between each lateral side 31 of the upper member 3 and the upper edge 21 of the associated side member 2. These articulated joints are made in the manner shown in Figure 2, the upper edge 21 of the side member 2 being provided with a concave groove 41 while the lateral side 31 of the upper member 3 is provided with a convex edge 42.

This gives a very great flexibility of the construction which facilitates, in particular, the realization of embankment in successive layers because the joints allow slight movements for the adjustment of the elements. In addition, after commissioning, the stresses applied under the load embankment and overload are transmitted tangentially by vault effect, the upper element to the side elements that bear laterally on the embankment.

Moreover, because of the great resistance provided by the judicious positioning of the joints between elements, it is possible to decrease their weight, which facilitates their handling even for very large dimensions.

In the embodiments described in EP-0,081,402, the tubular wall of the structure has a semicircular section symbolized by the dashed line S1 in FIG. 1. It can be seen that the height of the structure, at the key, is equal to half of the range between supports. The rectangular template passage in such a structure, for example for a road traffic lane, therefore has a height of the order of half the width.

As indicated, to reduce the height of the structure relative to its width, it is possible to give the upper element a radius of curvature greater than that of the side elements to which it is connected tangentially, according to the profile S2 indicated in dashed lines in FIG. 1. In this case, the passage template G shown in mixed lines in the figure has a width L greater than twice the height H. However, the overall height h1 of the key work remains quite large and may be too high when the difference in height h between the upper level of the taxiway 13 passing over the structure and the bottom 11 thereof is reduced.

To reduce the overall height of the structure, it has also been proposed in French Patent No. 2,642,109 to replace the curved upper element with a simple flat slab resting, by means of articulations, on the upper edges of the elements of the structure. side.

However, the settling effects at the edge of the deck plane determine a threshold effect which leads to a deterioration of the taxiway passing over the structure.

The invention provides a solution to this problem retaining, however, most of the advantages of the previously known arrangement.

As shown, in fact, in FIG. 1, the structure according to the invention comprises, in cross section along its axis O, an upper element 3 resting by its lateral sides 31, 31 'on the upper edges 21, 21' of two side elements 2, 2 'which can be perfectly identical to the side elements used in previously known structures.

Each side element 2 thus comprises, as in the previous arrangements, a side wall 23, at least the upper portion 24 is curved so as to form a circular sector centered at a point O1 and which extends vertically from a sole-shaped base comprising two wings, respectively external 22a and internal 22b resistant to the overturning of the element 2 inwards or outwards.

The upper element 3, on the other hand, has a particular shape. It consists, in fact, of a curved wall 30 associated with a stiffening rib 32. The wall 30 has a cylindrical shape with generatrices parallel to the longitudinal axis O and having a double curvature. It comprises, indeed, a flat central portion 33 which is connected to two end portions 34, 34 'having a radius of curvature equal to that of the curved upper part of the side wall 23, 23' of the associated side member 2, 2 '. The two parts 34 and 24 are, therefore, centered at the same point O1, O'1 and extend, respectively, on either side of the joint plane P.

The height e of the rib 32 is determined so as to give the assembly a moment of inertia sufficient to withstand the forces applied on the portion 33 of the element 3.

Preferably, the elements are dimensioned so that the longitudinal supports are spaced apart by a width L and placed at a height H above the bottom 11, these dimensions corresponding to the desired passage template G. The joints 4, 4 'are then placed at the corners of this jig.

The upper element 3 can be calculated as a variable section beam resting on two articulated supports constituted by the longitudinal joints 4, 4 'formed on the upper edges 21, 21' of the side members 2, 2 '. The height e is not therefore greater than that of a plane deck resting on two vertical abutments, to limit the same size.

On the other hand, the particular shape of the end portions 34, 34 'of the upper element 3 makes it possible to retain the previously known advantages of the structure.

For example, as shown in Figure 2, the hinged joint 4 can be made in the same way, the joint plane P is preferably inclined relative to the horizontal, an angle A equal to 45 °. It is known that, in practice, this type of joint has given the best results, even for very large spans.

In addition, the tangential connection of the elements by parts 24 and 34 of the same radius of curvature makes it possible to ensure the continuous transmission of the forces by the vault effect and to preserve a certain flexibility of the structure that is particularly useful for resisting differential settlements and, even to earthquakes, as we have been able to verify.

In particular, the forces applied to the two articulated joints 4, 4 'have a component horizontal tending to push outward side elements 2, 2 'which rest on the side embankments, the latter being made to participate in the resistance of the structure. On the other hand, the inwardly curved shape of the side elements 2, 2 'and the possibility of giving them a very small thickness relative to their length gives the assembly a certain flexibility to mobilize the embankments.

It appears that the total height h 'of the structure is not appreciably greater than that of a structure with a rectangular section and thus allows the passage of a traffic lane 13 at a relatively low height h above the bottom. 11 of the trench 10, the upper element 3 can be covered with a thin layer of embankment.

It should be noted that the particular shape of the upper element makes it possible to reduce the settling effects which normally occur at the limit of a flat deck and which lead to a deterioration of the roadway. Indeed, since the central portion 33 is extended by portions 34 of greater curvature, the thickness of the embankment gradually increases to the lateral supports 4, 4 'which are farthest from the upper surface 13 and, because continuity of the circular outer wall, this increase or gradual decrease in the height of embankment above the concrete wall ensures better absorption of the threshold effect at the passage of the structure.

Of course, the invention is not limited to the details of the embodiment which has just been described and which could be the subject of variants or improvements without departing from the scope of protection defined by the claims.

In particular, to produce the upper element 33, one can use the usual techniques of reinforced concrete, including prestressing, so as to reduce the height of the stiffening rib. We can also increase the number of ribs associated with each element.

Furthermore, in the embodiment of FIG. 1, the side elements 2, 2 'have a center of curvature O1 placed at the bottom 11, so as to increase the height of the curved portion 24 for a given ratio of the width L at the height H of the template.

However, one could give other shape to the side elements, as shown, for example, in Figure 3. In general, indeed, the height e of the rib should be just sufficient to give the upper element 3 the required flexural strength by ensuring the desired clearance pattern.

In addition, as described in patent EP-0,081,402, the inner edges of the bases 22, 22 'of the side elements can be connected by a concrete base to distribute the load over a large area.

The reference signs inserted after the technical features mentioned in the claims, are intended only to facilitate the understanding of the latter and in no way limit the scope.

Claims (4)

1. A passage structure under embankment (12) comprising a tubular wall (1) with a longitudinal axis (o) and consisting of a number of concrete elements built in advance and juxtaposed along longitudinal and transversal joints, whereby the said elements are assembled on the construction site in order to provide a tubular wall (1) comprising, as a section transversal to its axis, at least three prefabricated elements, respectively an upper element (3) with two lateral sides (31, 31') parallel to the longitudinal axis (o) and two side elements (2, 2') spaced from one another and each containing a base (22) resting on the ground (11) and a side wall (23) with an upper part (29) curved towards the inside of the section, with an upper rim (21) parallel to the longitudinal axis (o), whereas the upper element (3) rests by its lateral sides (31, 31'), along longitudinal joints (4, 4'), on the upper rims (21, 21') of the side elements (2, 2').
   characterised in that each upper element (3) comprises a wall (30) with a double curvature transversal profile comprising a flat central part (33) extended by two extreme parts (34, 34') each with the same radius of curvature as the upper curved part (24, 24') of the matching side element (2, 2'), in order to connect tangentially to the said element, whereas the said double curvature wall (30) is associated with at least one stiffening rib (32) capable of absorbing the stresses resulting from the upper element's own weight (3) and of the load applied by the embankment (12) covering the tubular wall (1) and in that the sizes of the elements are determined so that the total height (h') of the structure does not exceed substantially those of a structure with a rectangular section limiting a same passage gauge (G) and the height (e) of the rib does not exceed those of a plane roadway limiting said gauge, whereas the height of the rib (32) is determined in order to give to the upper element a moment of inertia sufficient to withstand to the stresses on the central part (33) of the upper element (3).
2. A structure under embankment according to claim 1, characterised in that the lateral sides (31, 31') of the upper element (3) and the upper rims (21, 21') of the side elements (2, 2') are provided with matching resting parts, respectively recessed and protruding parts, in order to provide two hinged longitudinal joints (4, 4'), whereas the tangential connection of the resting parts of the upper element (3) with the side elements (2, 2') determine the transmission of the resting stresses, at each longitudinal joint, along directions titled with respect to the horizontal axis, with a horizontal component directed outwards.
3. A structure under embankment according to one of the previous claims, characterised in that the longitudinal joint plane between the upper rim of a side element and the lateral side of the upper element resting on the former, passes through a common curvature centre and is tilted substantially at 45° with respect to the horizontal axis.
4. A structure under embankment according to one of the previous claims, capable of providing a rectangular passage gauge (G) of height (H) and width (L), characterised in that the sizes of the elements are determined so that, after installation, the longitudinal joints (4, 4') between the elements are located substantially at the upper angles of the passage gauge (G), whereby the stiffening ribs (32) of the upper elements (3) have a lower face placed at a level corresponding substantially to the height (H) of the gauge (G) and the longitudinal joints (4, 4') are spaced by a distance corresponding substantially to the width (L) of the gauge (G).

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