The present invention relates to the construction of stabilized soil, or reinforced earth, structures. This construction technique is normally used for producing structures such as retaining walls, bridge abutments, etc.
A stabilized soil structure combines a compacted fill, a facing and reinforcements usually connected to the facing. The reinforcements are put in place in the soil with a density depending on the stresses that may be exerted on the structure, the thrust forces of the terrain being absorbed by the soil-reinforcement friction.
The invention concerns more particularly the case where the reinforcements are in the form of a strip of synthetic material, for example based on polyester fibres.
The facing is most often produced from prefabricated concrete elements, in the form of slabs or blocks, juxtaposed so as to cover the front face of the structure. There may be horizontal steps on this front face between different levels of the facing, when the structure comprises one or more terraces.
The reinforcements placed in the fill are usually secured to the facing by means of mechanical connection members that may take various forms. Once the structure is finished, the reinforcements distributed in the fill transmit high loads, which may range up to several tons. The connection thereof to the facing must be robust in order to preserve the cohesion of the whole.
In some systems, the facing elements are configured so as to have at least one passage intended to receive a reinforcement strip.
The document EP 1 662 050 discloses a reinforced soil structure comprising a fill, reinforcement strips extending in a reinforced area of the fill situated to the rear of a front face of the structure, and a facing placed along said front face, the reinforcement strips being anchored to the facing in respective anchoring regions. In at least one anchoring region, the facing incorporates a path formed for a reinforcement strip between two emergence points situated on a rear face of the facing adjacent to the fill. This path comprises two rectilinear portions respectively adjacent to the two emergence points and each disposed so as to position the strip in the same emergence plane perpendicular to said rear face, two curved portions provided as respective extensions of the two rectilinear portions and disposed so as to deviate the strip out of the emergence plane, and a connecting portion connecting together the two curved portions and having at least one loop situated outside the emergence plane. It also describes a facing element adapted to such a structure.
This solution, although highly advantageous, may nevertheless have a drawback during the construction of such a structure.
This is because such a structure is generally constructed by disposing at least one facing fitted along a front face of the structure delimiting a volume to be filled and by performing the following successive steps:
The excavation step for digging a trench extends the duration of the work and requires the use of labour.
The object of the present invention is to propose a new method of anchoring reinforcement strips to a facing of a stabilized soil structure that reduces the effect of the above problems.
The invention proposes a stabilized soil structure comprising a fill, reinforcement strips extending in a reinforced area of the fill situated to the rear of a front face of the structure, and a facing placed along said front face, the reinforcement strips being anchored to the facing in respective anchoring regions, wherein the facing incorporates, in at least one anchoring region, a path formed for a reinforcement strip between two emergence points situated on a rear face of the facing adjacent to the fill, wherein the path comprises two adjacent portions respectively adjacent to the two emergence points and each disposed so as to position the strip in an emergence plane substantially perpendicular to said rear face, two curved portions provided as respective extensions of the two adjacent portions and disposed so as to deviate the strip out of the emergence planes, and a connecting portion connecting together the two curved portions, characterized in that the two emergence planes are distinct, separated by a physical separator and substantially parallel to each other in order to form top and bottom emergence planes, and in that the connecting portion comprises at least one loop situated outside the emergence planes and outside the space between these emergence planes.
The invention also proposes a stabilized soil structure comprising a fill, reinforcement strips extending in a reinforced area of the fill situated to the rear of a front face of the structure, and a facing placed along said front face, the reinforcement strips being anchored to the facing in respective anchoring regions, wherein the facing incorporates, in at least one anchoring region, a path formed for a reinforcement strip between two emergence points situated on a rear face of the facing adjacent to the fill, wherein the path comprises two adjacent portions respectively adjacent to the two emergence points and each disposed so as to position the strip in a respective emergence plane substantially perpendicular to said rear face, two curved portions provided as respective extensions of the two adjacent portions and disposed so as to deviate the strip out of the emergence planes, and a connecting portion connecting together the two curved portions, wherein the two emergence planes are distinct and substantially parallel to each other in order to form top and bottom emergence planes, and wherein the connection portion comprises at least one loop situated outside the emergence planes and outside the space between these emergence planes.
Allowing emergence in the reinforced area of the fill of portions of reinforcement strip in two distinct emergence planes while connecting these two strip portions by a path in the facing comprising at least one loop situated outside the emergence planes and outside the space between these emergence planes makes it possible both to stress the facing, consisting in general of cast material, such as concrete, in a satisfactory manner, and to simply put the portions of the strip under tension. Because of the offset between the emergence planes, it is possible to tension the portions of the strip after they have been disposed on a laying surface, situated at the bottom emergence plane, by simple addition of filling material.
The fill thus pushes the portion of the strip emerging from the top plane towards the one emerging from the bottom plane, effectively ensuring tensioning of the portions of the strip.
In the context of the invention, “an emergence plane substantially perpendicular” to a face means a plane the angle of which with respect to a plane perpendicular to the tangent plane of the said face in the emergence area is less than or equal to 25°, for example less than or equal 10°, in particular equal to 0°.
In the context of the invention, “two distinct emergence planes substantially parallel to each other” means two planes defined above, which may form between them an angle of less than or equal to 30° for example less than or equal to 15°, and are thus able to intersect each other at a distance from the anchoring means. The angle between these two emergence planes may be an angle measured with respect to the plane perpendicular to the tangent plane of the base of the facing in the emergence zone in a direction perpendicular and/or parallel to said tangent plane.
In the context of the invention, “physical separator” means a part of the material disposed in the anchoring region and adapted to separate the two emergence planes. The physical separator may be in continuity of material in the anchoring region of the facing. It may also consist of a piece attached in the anchoring region of the facing.
In one embodiment of the structure, the adjacent portions are rectilinear portions.
According to an embodiment, the two substantially parallel emergence planes are separated in the anchoring region by a distance greater than or equal to 2 cm and less than or equal to 20 cm, for example greater than or equal to 5 cm and/or less than or equal 15 cm.
According to an embodiment, the adjacent portions emerge at the rear face of the facing in the form of slots, comprising the emergence point, and two slots connected by the same path are offset so as not to cross a common vertical plane.
According to another embodiment, the adjacent portions emerge at the rear face of the facing in the form of slots, comprising the emergence points, and where two slots connected by the same path cross a common vertical plane.
Preferably, the adjacent portions of said path are rectilinear and each extend in the emergence plane over at least half of the thickness of the facing. The reinforcement strip typically has a width of no more than half the thickness of the facing.
In an embodiment of the structure, the facing has, in the anchoring region, a protective sheath receiving the reinforcement strip along said path. This sheath isolates the strip from the moulded material in order to protect the reinforcement against premature damage. In particular, if the reinforcement is procured by polyester fibres, it is known that these do not well accept basic environments such as those that are encountered in concrete. The aforementioned sheath therefore supplements the protection conferred by the plastic sheath that coats the polyester fibres of the strip.
Another aspect of the invention relates to a facing element for a stabilized soil structure comprising a body made from cast material inside which a path is formed for a reinforcement strip between two emergence points situated on a rear face of the body, wherein the path comprises two adjacent portions respectively adjacent to the two emergence points and each disposed so as to position the strip in a respective emergence plane perpendicular to said rear face, two curved portions provided as respective extensions of the two adjacent portions and disposed so as to deviate the strip out of the emergence planes, and a connecting portion connecting together the two curved portions, wherein the two emergence planes are distinct, separated by a physical separator and substantially parallel to each other, and wherein the connecting portion comprises at least one loop situated outside the emergence planes and outside the space between these emergence planes.
The invention also relates to a facing element for a stabilized soil structure comprising a body made from cast material inside which a path is formed for a reinforcement strip between two emergence points situated on a rear face of the body, wherein the path comprises two adjacent portions respectively adjacent to the two emergence points and each disposed so as to position the strip in a respective emergence plane perpendicular to said rear face, two curved portions provided as respective extensions of the two adjacent portions and disposed so as to deviate the strip out of the emergence planes, and a connecting portion connecting together the two curved portions, wherein the two emergence planes are distinct and substantially parallel to each other, and wherein the connecting portion comprises at least one loop situated outside the emergence planes and outside the space between these emergence planes.
The features described above in relation to the stabilized soil structure according to the invention are also directly usable for the purpose of different embodiments of a facing element according to the invention.
According to an embodiment, the adjacent portions emerge at the rear face of the facing in the form of slots, comprising the emergence point, and two slots connected by the same path are offset so as not to cross a common vertical plane when said facing element is disposed in a position similar to the one that it would occupy in an erected structure.
According to another embodiment the adjacent portions emerge at the rear face of the facing in the form of slots, comprising the emergence points, and two slots connected by the same path cross a common vertical plane when said facing element is disposed in a position similar to the one that it would occupy in an erected structure.
Similar position means a position where the facing element will have the same inclinations with respect to the vertical and horizontal planes as if it were disposed in the erected structure, in particular assembled with other facing elements.
The strip may be put in place on the path as soon as the material of the body is cast, with or without the aforementioned protective sheath.
Several arrangements are possible for the path defined for the strip within the facing element. In some embodiments, the two curved portions of the path direct the strip towards the same side of the emergence planes. It is considered that the curved portions of the path direct the strip towards the top side, or respectively the bottom side, if these portions are each oriented above or respectively below each of the emergence planes. In this case, a first possibility is that the path is formed so that the strip is received in the two adjacent portions with the same face of the strip oriented towards this side of the emergence planes. The path is then formed so that said face of the strip is placed either on the external side or on the internal side of the loop situated outside the emergence planes. A second possibility is that the path is formed so that the strip is received in one of the two adjacent portions with a face of the strip oriented towards said side of the emergence planes and in the other one of the two rectilinear portions with said face of the strip oriented opposite to said side of the emergence planes.
In another embodiment, the two curved portions of the path respectively direct the strip towards two opposite sides, one above and the other below the emergence planes, and the connecting portion of the path has two loops respectively extending the two curved portions of the path and a part passing through the emergence planes and connecting together the two loops.
The present invention also relates to a method of constructing a stabilized soil structure according to the invention, wherein at least one facing element according to the invention is disposed on a front face of the structure delimiting a volume to be filled, comprising the following successive steps:
Other features and advantages of the present invention will emerge in the following description of non-limitative example embodiments, with reference to the accompanying drawings, in which:
a and b illustrate the placing of a known reinforcement of the prior art;
The reinforcements 2 consist of synthetic reinforcements in the form of flexible strips extending in horizontal planes at the rear of the facing 3. These may in particular be reinforcement strips based on polyester fibres sheathed with polyethylene.
The reinforcement strips 2 are attached to the prefabricated elements 4 assembled so as to form the facing 3. These elements 4 are typically made from reinforced concrete. In the example shown, they are in the form of panels, they could also have other forms, such as blocks. When the concrete of such an element 4 is cast, one or more reinforcement strips 2 are installed in the mould according to a path described below in order to produce the strip/element anchoring. After the concrete has set, each strip has two portions that emerge from the element in order to be installed in the filled block.
In order to erect the structure, it is possible to proceed as follows:
a) position some of the facing elements 4 in order to be in a position then to add filling material over a certain height. In a known manner, the mounting and positioning of the facing elements can be facilitated by assembly members placed between them. The strips 2 are positioned on the facing elements 4 so that some of them are placed at the same horizontal level during mounting of the facing;
b) add filling material and compact it progressively until the next level provided for the positioning of the reinforcement strips 2 is reached;
c) spread the reinforcement strips 2 over the fill at this level;
d) add filling material over the reinforcement strips 2 that have just been installed. This filling material is compacted as it is added;
e) repeat steps b) to d) if several levels of strips are provided per row of facing elements 4;
f) repeat steps a) to e) until the top level of the fill is reached.
According to a traditional embodiment illustrated in
In the method according to the invention, as illustrated in
There are two adjacent portions, here rectilinear 21 and 22, extending perpendicular to the rear face 7 of the element from the emergence points PE1 and PE2. In each adjacent portion 21, 22, the strip remains in each of the distinct emergence planes Pl, P2. The rectilinear portions 21, 22 extend over at least half of the thickness of the body of the element 4, measured perpendicular to the rear face 7 thereof. This avoids bad stressing of the concrete in the vicinity of the rear face 7.
Each rectilinear portion 21, 22 of the path of the strip is extended by a respective curved portion 23, 24 where the strip is deviated out of each of the emergence planes P1, P2. Beyond the curved portions 23, 24, the strip 2 extends along the front face of the element, a little recessed with respect to this front face so as not to be visible on the surface of the structure. According to another embodiment the adjacent portions may not be rectilinear but for example slightly curved and make it possible to join the emergence points to curved portions 23, 24 as shown.
The two curved portions 23, 24 are connected together by a connecting point that has a loop 25 situated outside the emergence planes P1, P2.
In the example in
In the variant illustrated by
In the variant illustrated by
Other arrangements are also possible for the path of the reinforcement strip within a facing element.
In the embodiments illustrated in
According to another embodiment illustrated in
In order easily to follow a path such as the one illustrated by
When the reinforcement strip has components (for example polyester fibres) sensitive to basic environments, it may advantageous to place a protective sheath made from plastics material between this strip and the concrete facing. This sheath prevents the alkalinity of the concrete propagating as far as the sensitive component. The flexible sheath receives the strip before being put in place with it in the mould. It is thus surrounded by the moulded concrete and receives the reinforcement along its path in order to isolate it from the concrete.
It can be envisaged that the reinforcing strip not yet be installed in its sheath 15 at the time of manufacture of the element. It is then convenient to use a rigid sheath previously shaped along the required path.
In the example shown in
In the example shown in
An embodiment according to
In general terms, the proposed connection method, between the facing of a stabilized soil structure and at least some of the reinforcement strips thereof, is compatible with a large number of structure configurations, strip lengths, strip fitting densities, etc.
Number | Date | Country | Kind |
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08 58196 | Dec 2008 | FR | national |
Filing Document | Filing Date | Country | Kind | 371c Date |
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PCT/FR2009/052353 | 12/1/2009 | WO | 00 | 6/1/2011 |