EP2050879B1 - Stabilisation strip designed to be used in structures with reinforced floor - Google Patents

Abstract

The strip (10) has laterally open notches (16) and laterally open pre-notches for imposing a finite radius of curvature in a main plane of the strip, where the strip is constituted of a polymer based matrix e.g. polyethylene based matrix. The notches and the pre-notches are arranged at regular intervals on lateral parts (14), in the form of wings, of a central part (12), where the central part extends along a longitudinal axis (A) of the strip. The central part includes longitudinal reinforcements e.g. polymeric fibers or threads. An independent claim is also included for a method for constructing a reinforced soil structure.

Description

The present invention relates to a stabilization strip for use in structures reinforced soil or armed land, and the use of such a strip for the construction of structures reinforced soil or ground.

A reinforced soil structure combines a compacted embankment, a siding and reinforcements connected or not to the facing.

Various types of reinforcements may be used: metal reinforcements, for example galvanized steel rods, or flexible stabilizing strips, for example based on polyester fibers. They are placed in the soil with a density depending on the constraints that can be exerted on the structure. For example, the thrust forces of the ground that are taken up by the friction soil-reinforcements.

The facing is most often made from prefabricated concrete elements in the form of slabs or blocks, juxtaposed to cover the front face of the structure.

In some cases, the reinforcements are provided in the form of substantially parallelepipedal flexible strips, for example, all of whose faces are rectangles. Commonly such strips have a width greater than their thickness, for example ten times larger, or even 100 times larger.

Such flexible strips may have a length of about 3 to 10 meters, although shorter or longer strips may be employed. The width of such strips is generally between 4 and 6 centimeters although it is possible to use strips width of up to 10 or 25 centimeters, or even more. Their thickness varies, for example, from about 1 millimeter to a few centimeters and is generally between 1 to 6 millimeters.

There are stabilization bands unreinforced or reinforced by means of, for example, fibers or parallel threads.

The purpose of the stabilization strips is to transmit the forces into the ground or earth and thus distribute the forces.

In particular, it is necessary to transmit forces between a strip and the embankment in which it is placed. The strip must therefore have a sufficient area to develop by friction the required shear strength per unit length.

In addition, the band is preferably capable of transmitting the forces along its entire length, allowing a high tensile strength.

A solution known to those skilled in the art consists in using parallelepiped strips of polyethylene reinforced with polyester fibers arranged parallel to each other in the volume of said strip.

Another solution, described in WO 95/11351 is to use strips having a longitudinal portion in the form of a central portion to withstand a tensile force. The central part has two lateral parts which protrude laterally on either side of the central part to rub against the earth. The central portion also includes a set of fibers arranged to enhance the tensile strength.

Another example of stabilization band is described in WO 2007/086634 .

The use of such stabilizing bands in structures with reinforced soil may present difficulties especially when there are obstacles in the structure. For example, the presence of vertical support columns or pipes may interfere with the disposition of the stabilization strips.

Indeed, such a stabilizing strip structurally has a high rigidity in their laying plane. It is therefore very difficult to impose a deviation on such bands so as to circumvent any obstacles.

Such a stabilizing strip is generally arranged flat, its width and length being substantially in a horizontal plane, thus defining the main plane of such a stabilizing strip

An object of the present invention is to provide a stabilizing strip to which it is possible to impose a deflection.

The invention thus proposes a stabilization strip intended to be used in reinforced soil structures comprising notches and / or laterally emergent pre-cuts enabling a finite radius of curvature to be imposed on said strip.

According to the invention, the term laterally opens a notch or pre-notch whose one end is in the volume of the strip and another end opens on the surface of the strip on its side side.

Advantageously, the notches or pre-cuts allow to impose a deviation to the stabilization band while maintaining sufficient rigidity of the band and a sufficient life to ensure the stabilization of the structure in reinforced soil.

• ladite bande comprend au moins une paire d'entailles

ou de pré-entailles, chaque entailles ou pré-entailles de ladite au moins une paire étant disposée symétriquement de part et d'autre de l'axe longitudinal de ladite bande,

• ladite bande est fournie sous forme d'une bande sensiblement parallélépipédique, par exemple, dont toutes les faces sont des rectangles,
• les entailles ou pré-entailles s'étendent sensiblement dans le plan principal de ladite bande et selon la largeur de ladite bande,
• ladite bande comprend une matrice à base de polymères, par exemple à base de polyéthylène ;
• les entailles et/ou pré-entailles sont aptes à permettre d'imposer un rayon de courbure sensiblement dans le plan principal de ladite bande de stabilisation ;
• ladite bande comprend une partie centrale s'étendant sensiblement le long de l'axe longitudinal de ladite bande, ladite partie centrale ayant des parties qui font saillie latéralement, où lesdites parties latérales comprennent des entailles et/ou pré-entailles;
• les entailles et/ou pré-entailles latéralement débouchantes sont disposées à des intervalles réguliers sur la partie latérale de ladite bande;
• les entailles et/ou pré-entailles latéralement débouchantes sont disposées à des intervalles irrégulièrs sur la partie latérale de ladite bande;
• lesdites parties latérales présentent une épaisseur plus faible que ladite partie centrale sur laquelle elles font saillie ;
• ladite partie centrale comprend un renfort longitudinal apte à résister en traction ;
• ledit renfort longitudinal est une corde et/ou des fibres ou fils polymérique(s) ;
• la partie latérale s'étend longitudinalement.

A stabilizing strip according to the invention may further comprise one or more of the features optional below, considered individually or in any combination:

• said band comprises at least one pair of notches

or pre-cuts, each notches or pre-cuts of said at least one pair being arranged symmetrically on either side of the longitudinal axis of said strip,

• said band is provided in the form of a substantially parallelepipedal band, for example, all of whose faces are rectangles,
• the notches or pre-cuts extend substantially in the main plane of said band and according to the width of said band,
• said band comprises a matrix based on polymers, for example based on polyethylene;
• the notches and / or pre-cuts are able to allow to impose a radius of curvature substantially in the main plane of said stabilizing strip;
• said strip comprises a central portion extending substantially along the longitudinal axis of said strip, said central portion having laterally projecting portions, wherein said side portions comprise notches and / or pre-cuts;
• the notches and / or pre-cuts laterally open are arranged at regular intervals on the lateral portion of said strip;
• the notches and / or pre-notches laterally open are arranged at irregular intervals on the lateral portion of said strip;
• said side portions have a thickness smaller than said central portion on which they project;
• said central portion comprises a longitudinal reinforcement capable of withstanding traction;
• said longitudinal reinforcement is a rope and / or fibers or polymeric threads;
• the lateral part extends longitudinally.

The invention also relates to the use of a stabilizing strip according to the invention for the construction of a structure in reinforced soil.

The invention also relates to a reinforced soil structure comprising at least one stabilizing strip according to the invention.

The subject of the invention is also a method for constructing a structure in reinforced soil, in which a facing is placed along a front face of the structure delimiting a volume to be filled, reinforcements are provided in an area of said volume, brings backfill material into said volume and compacts the backfill material, characterized in that said reinforcements comprise at least one stabilizing strip according to the invention.

The method of constructing a structure in reinforced soil according to the invention may comprise a step where a radius of curvature of between 1 and 10 meters is imposed on said stabilizing strip, as well as a step in which it is notch said at least one stabilizing strip at the time of laying.

It is possible to impose on the band a plurality of radius of curvature and thus to obtain all possible forms of path.

The method of construction of a reinforced soil structure according to the invention may further include the provision of the stabilization strips on the same plane and the opening of any pre-notches laterally open at the time of disposition of the stabilization strips .

• la figure 1 est une vue schématique en perspective d'un premier mode de réalisation avec des entailles latérales;
• la figure 2 est une vue schématique en perspective d'un deuxième mode de réalisation avec des entailles latéralement débouchantes;
• la figure 3 est une vue schématique en perspective d'un troisième mode de réalisation avec des pré-entailles latéralement débouchantes;
• la figure 4 une vue schématique en coupe latérale d'un ouvrage en sol renforcé selon l'invention en cours de réalisation.

The invention will be better understood on reading the description which follows, given solely by way of example and with reference to the appended drawings in which:

• the figure 1 is a schematic perspective view of a first embodiment with lateral notches;
• the figure 2 is a schematic perspective view of a second embodiment with laterally open notches;
• the figure 3 is a schematic perspective view of a third embodiment with laterally open pre-notches;
• the figure 4 a schematic side sectional view of a reinforced soil structure according to the invention in progress.

For the sake of clarity, the different elements shown in the figures are not necessarily to scale.

The term "longitudinal" means the direction along the longitudinal axis of the strip, the "lateral" direction being a direction substantially perpendicular to the longitudinal direction.

"Rope" means an assembly obtained by twisting or braiding at least three fibers composed of a plurality of threads, for example of at least three threads, of textile, synthetic, plastic, metal or a combination of these different fibers or threads.

The chosen cords may for example be thin, with a diameter of the order of one millimeter or more thick with a diameter of about one centimeter.

For the purposes of the invention, "pre-cut" designates a portion of the stabilizing strip prepared to be cut in such a manner as to form a laterally open notch. The pre-notch can be opened to obtain the notch laterally open by a small effort, for example by bending the stabilization band or by breaking junction points between the pre-notch and the stabilizing band.

The pre-notch may, for example, consist of discontinuous cutting or thinning of material according to the desired notch, or a weak zone capable of tearing or degrading to form a notch.

We have shown on the figure 1 a perspective view of a first embodiment of a stabilizing strip according to the invention.

In this first embodiment, the stabilizing strip 10 comprises a central portion 12 which extends substantially along the longitudinal axis A of the stabilizing strip 10. In lateral projection on each side of the central portion 12, the stabilizing strip 10 comprises two lateral parts 14. Each lateral part comprises laterally open slots 16 regularly disposed on the lateral part 14 substantially laterally to the central part 12.

The central portion 12 may be of a plastic material such as polyethylene, polypropylene, PVC.

In this embodiment, the lateral portions 14 comprise a plurality of laterally emergent notches 16 arranged regularly so as to make it possible to impose a radius of curvature over the entire length of the strip 10.

The notches in this embodiment have a substantially triangular shape, but they could equally well have a rectangular, curved or irregular shape or a combination of these different shapes.

In the case of triangular notches, the choice of the angle at the apex α of said triangle is to be considered.

Indeed, the greater the angle α, the greater the curvature that can be given to the stabilization band is important.

The angle at the apex α of the triangular notch should not, however, be increased excessively as this may cause a reduction of the material constituting the lateral parts such that a harmful reduction of the friction surface with the ground would result.

A compromise can therefore be determined. Thus, for example, the angle α is less than or equal to 90 °, for example less than or equal to 50 °, for example greater than or equal to 20 °, for example greater than or equal to 40 °.

In another embodiment, shown in FIG. figure 2 said stabilizing strip 10 according to the invention comprises a central portion 12 extending substantially along the longitudinal axis of said strip.

Said central portion 12 comprises a longitudinal reinforcement 18 capable of withstanding traction and being able to admit a radius of curvature in the main plane of the strip.

In the embodiment shown on the figure 2 the longitudinal reinforcement is in the form of one or more braided cords 18, but it could also be in the form of one or more twisted cords or polymeric fibers.

The longitudinal reinforcement can be included both in the entire volume of the band and not only in the central part. The lateral parts may also include longitudinal reinforcements.

The central portion 12 extends laterally on two sides by two lateral portions 14 which project on said central portion 12, in the form of fins.

The two lateral parts 14 have a smaller thickness than the central part 12.

One or both lateral portions 14 may or may be provided with ribs and / or corrugation and / or perforation or any other means known to those skilled in the art for improving the frictional interaction with the earth. Said lateral portions 14 comprise laterally open slots 16.

As in the embodiment of the figure 2 the notches have a substantially triangular shape, but may also have a rectangular, curved or irregular shape or a combination of these different shapes.

According to another embodiment shown in figure 3 , the band according to the invention may comprise pre-cuts 17.

The stabilizing strip 10 shown on the figure 3 comprises a central portion 12 extending substantially along the longitudinal axis of said strip.

Said central portion 12 comprises a polyethylene matrix reinforced with polyester fibers 19 arranged parallel to each other in the volume of said central portion 12.

In this embodiment, the lateral portions 14 comprise a plurality of laterally open pre-notches 17 arranged regularly so as to make it possible to impose a radius of curvature along the entire length of the strip 10 once these pre-cuts 17 have been opened.

The laterally open pre-notches 17 in this embodiment have a substantially triangular shape, but may also have a rectangular, curved or irregular shape or a combination of these different shapes.

In the case of triangular pre-cuts, the choice of the angle at the apex α of said triangle is to be considered.

For the same reasons as explained in detail in the description of the embodiment of the figure 1 , the apex angle α of said triangle may be chosen less than or equal to 90 °, for example less than or equal to 50 °, for example greater than or equal to 20 °, for example greater than or equal to 40 °.

The use of laterally open pre-notches allows to reduce the surface of the fins only when desired. In fact, it is preferable to have a large contact area between the lateral edges and the earth or the ground in order to increase the friction between the stabilizing strip and the ground and thus strengthen the soil.

A strip according to the invention can be produced, for example, by extrusion, coextrusion, rolling or any other technique known to those skilled in the art to produce metal or polymer strips.

Notches and / or pre-notches laterally emerging strips of the invention can be obtained by means of manufacturing method as described in WO 95/11351 . Such a method may comprise the passage of the stabilizing strip between two rotary rollers having on their periphery a suitable profile for cutting notches and / or pre-notches laterally open on the strips.

The invention also relates to a method of constructing a structure in reinforced soil.

The figure 4 illustrates such a method. A compacted backfill 21, in which stabilizing strips 10 according to the invention are distributed, is delimited on the front side of the structure by a facing 23 constituted by juxtaposing prefabricated elements 24, and on the rear side by the ground 25. against which is erected the retaining wall.

The compacted embankment 21 shown on the figure 4 comprises a foundation stack 22 of concrete. The stabilizing strips according to the invention can bypass the stack 22 thanks to their notches and / or pre-cuts.

To ensure the cohesion of the retaining wall, the stabilizing strips 10 can be connected to the facing elements 24, and extend for a distance within the embankment 21. These stabilizing strips 10 contribute to reinforce the soil located in a reinforced zone Z on the back of the siding 23.

In this reinforced zone Z, the material of the embankment 21 has a great cohesion thanks to the stabilizing strips 10. It is thus able to withstand the shear stresses which are exerted due to the tensile forces experienced by the stabilizing strips 10 .

The connection of stabilizing strips on the back of the facing elements 24 ensures the maintenance of the facing applied against embankments that can be of large volume.

In one possible embodiment, the stabilizing strips 10 are integrated during the manufacture of the facing elements 24. In the frequent case where the elements 24 are prefabricated in concrete, a portion of the stabilizing strips 10 may be embedded in the molded concrete. 24. In the example of book configuration illustrated by the figure 4 the stabilizing strips 10 are arranged in horizontal planes substantially parallel to one another over the height of the structure.

1. a) mettre en place une partie des éléments de parement 24 et de la pile de fondation 22 afin d'être en mesure d'apporter ensuite du matériau de remblai sur une certaine hauteur. De façon connue, le montage et le positionnement des éléments de parement peuvent être facilités par des organes d'assemblage placés entre eux;
2. b) installer les bandes de stabilisation 10 sur le remblai déjà présent en leur imposant un rayon de courbure de manière à contourner un obstacle, notamment la pile de fondation 22;
3. c) apporter du matériau de remblai par-dessus la couche de bandes de stabilisation 10 qui vient d'être installée, jusqu'au prochain niveau de bandes de stabilisation 10. Ce matériau de remblai est compacté au fur et à mesure de son apport;
4. d) répéter les étapes a) à c) jusqu'à atteindre le niveau supérieur du remblai.

To build the book presented on the figure 4 we can proceed as follows:

1. a) set up a portion of the facing elements 24 and the foundation pile 22 so as to be able to then bring backfill material to a certain height. In known manner, the mounting and positioning of the facing elements can be facilitated by connecting members placed between them;
2. b) install the stabilization strips 10 on the embankment already present by imposing a radius of curvature so as to bypass an obstacle, including the foundation pile 22;
3. c) providing backfill material over the newly installed layer of stabilizing strips 10 to the next level of stabilizing strips 10. This backfill material is compacted as it is added;
4. d) Repeat steps a) to c) until the top level of the embankment is reached.

The stabilizing strips may already include notches and / or pre-bowels laterally open, the pre-cuts can be opened, for example hollowed out, by the operator on the site, just before the establishment of bands. In addition, the notches can be cut by the operator on the site of the book, or even at the time of installation according to obstacles to bypass.

A tool can then make it possible to proceed with the notches in situ, for example cutting pliers or a cutting plier with two series of blades facing one another, each series being arranged according to the desired notch, for example V-shaped .

It should be noted that many variations can be made to the previously described structure and its method of production.

The invention is not limited to these types of embodiments and must be interpreted in a nonlimiting manner, and encompassing any equivalent embodiment.

Claims (14)

1. Stabilizing strip (10) intended to be used in reinforced earth structures characterized in that said strip comprises laterally-opening notches (16) and/or pre-notches (17) making it possible to impose a finite radius of curvature on said strip (10).
2. Stabilizing strip (10) according to claim 1, characterized in that said strip comprises a polymer-based matrix, for example polyethylene-based.
3. Stabilizing strip (10) according to any one of claims 1 or 2, characterized in that the notches (16) and/or pre-notches (17) are capable of allowing a radius of curvature to be imposed, approximately in the principal plane of said stabilizing strip.
4. Stabilizing strip (10) according to any of the preceding claims, comprising a central part (12) extending approximately along the longitudinal axis (A) of said strip, said central part (12) having laterally-protruding parts (14) characterized in that said lateral parts (14) comprise notches (16) and/or pre-notches (17).
5. Stabilizing strip (10) according to claim 4, characterized in that the laterally-opening notches (16) and/or pre-notches (17) are arranged at regular intervals on the lateral part (14).
6. Stabilizing strip (10) according to one of claims 4 or 5, characterized in that said lateral parts (14) are less thick than said central part (12) from which they protrude.
7. Stabilizing strip (10) according to any of claims 4 to 6, characterized in that said central part (12) comprises a longitudinal reinforcement (18, 19) having a high tensile strength.
8. Stabilizing strip (10) according to claim 7, characterized in that said longitudinal reinforcement (18, 19) is a cord and/or polymer fibres or yarn.
9. Stabilizing strip (10) according to any one of claims 4 to 8, characterized in that the lateral part (14) extends longitudinally.
10. Use of a stabilizing strip (10) according to any one of the previous claims for the construction of a reinforced earth structure.
11. Reinforced earth structure comprising at least one stabilizing strip (10), according to any of claims 1 to 9.
12. Construction method for a reinforced earth structure, in which a facing (24) is arranged over a front surface of the structure delimiting a volume to be backfilled, reinforcements (10) are arranged in one zone of said volume, backfill material (21) is placed in said volume and the backfill material (21) is compacted, characterized in that said reinforcements (10) comprise at least one stabilizing strip (10) according to any of claims 1 to 9.
13. Construction method for a reinforced earth structure according to claim 12, characterized in that a radius of curvature of between 1 and 10 metres is imposed on said stabilizing strip (10).
14. Construction method for a reinforced earth structure according to claim 12 or 13, characterized in that said at least one stabilizing strip (10) is notched during installation.

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