Patent Grant
8011859
This application is a National Stage Entry of International Application No. PCT/FR2008/050347, filed Feb. 29, 2008, and claims priority to French Patent Application No. 0701579, filed in France on Mar. 5, 2007, each of which is hereby incorporated by reference in its entirety as if fully set forth herein.
This invention relates to the construction of reinforced earth or soil reinforced structures. This construction technique is commonly used to realize structures such as retaining walls, bridge abutments, etc.
A soil reinforced structure combines a compacted fill, a facing and reinforcements normally connected to the facing. The reinforcements are set in place in the soil with a density that depends on the constraints that can be exerted on the structure, the soil pressure efforts being taken up by the soil-reinforcement friction.
The invention is particularly interesting in the case where the reinforcements are in the form of a strip made of synthetic material, for example of a polyester fiber base.
The facing is most often realized using prefabricated concrete members, in the form of slabs or blocks, juxtaposed in order to cover the front face of the structure. There can be transverse thrusts on this front face between different levels of facing, when the structure comprises one or several terraces.
The reinforcements placed in the fill are usually attached to the facing using mechanical connecting members that can have various forms. Once the structure is completed, the reinforcements distributed in the fill transmit high loads, which can attain several tons. Their connection to the facing must be robust in order to retain overall cohesion.
The connecting members have risks of degradation. They are often sensitive to corrosion due to humidity or to chemical agents present or infiltrated into the fill. The connecting members are sometimes of a base of resins or of composite materials in order to be less easily corrodible. But their cost is then increased, and it is difficult to provide them with good mechanical properties. It is as such desirable to be able to avoid the use of connecting members between the facing member and the reinforcements of the structure.
In certain systems, the facing members are conformed in such a way as to have at least one passage intended to receive a reinforcement strip.
In FR 2878268, a soil reinforced structure is proposed, comprising a fill, reinforcement strips extending in a reinforced area of the fill located at 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 the respective anchoring regions. In at least one anchoring region, the facing incorporates a path formed for a reinforcement strip between two protruding points located on a rear face of the facing adjacent to the fill. This path comprises two rectilinear portions respectively adjacent to the two protruding points and each one arranged in order to position the strip in the same protruding plane perpendicular to said rear face, two curved portions respectively defining an extension of the two rectilinear portions and arranged to divert the strip outside from the protruding plane, and a connecting portion connecting together the two curved portions and having at least one loop located outside of the protruding plane.
This arrangement allows for a good positioning and effective anchoring of the reinforcement strip while preventing it from having to follow curvatures that are too sharp or from having to apply substantial baulk efforts (tightening) to it.
In general, the distribution of the reinforcement strips is calculated according to the soil pressure efforts and the number of reinforcement strips required for a given configuration is determined according to the soil-reinforcement friction.
In light of responding to the constant concern of increasing the resistance of the structures and/or reducing costs—by decreasing the number of reinforcement strips required for the same configuration—it is advantageous to be able to increase the soil-reinforcement friction coefficient.
The purpose of this invention is to propose a configuration of reinforcement strips that makes possible an advantageous anchoring to a facing of a soil reinforced structure and to respond to the aforementioned concerns.
The invention as such proposes a soil reinforced structure, comprising a fill, reinforcement strips comprising reinforcement sections which extend in a reinforced area of the fill located at 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 the respective anchoring regions, wherein the facing incorporates, in at least one anchoring region, a path formed for a reinforcement strip between two protruding points located on a rear face of the facing adjacent to the fill, and where the path comprises two rectilinear portions respectively adjacent to the two protruding points and each arranged to position the strip in the same protruding plane (P) perpendicular to said rear face, two curved portions respectively defining an extension of the two rectilinear portions and arranged to divert the strip outside from the protruding plane (P), and a connecting portion connecting together the two curved portions and having at least one loop located outside of the protruding plane, where at least two reinforcement sections each prolong a rectilinear portion of a path beyond a protruding point and are connected together by at least one linking member and where each one of said reinforcement sections is part of a reinforcement strip arranged according to said path.
Connecting together at least two reinforcement sections that are part of a reinforcement strip arranged according to said path by at least one linking member makes it possible to significantly increase the soil-reinforcement friction coefficient.
The number of reinforcement strips required to reinforce a structure can advantageously be reduced, with a given configuration or increase the margin of safety for the same distribution of reinforcement strips.
According to an embodiment, the linking members are strips. These linking strips can be fastened to the reinforcement strips by stapling, gluing or any other appropriate technique. This fastening can be carried out before or after positioning reinforcement strips according to said path.
According to an embodiment, the linking members are arranged according to an angle α, between 30° and 150° more preferably between 60° and 120°, even substantially equal to 90°, where the angle α measures the angular separation in the plane P between the axis of one of the reinforcement sections and the axis of the linking member. According to the invention, the reinforcement sections can be arranged so that the latter are substantially parallel together.
According to different embodiments, which can be combined:
According to an embodiment, two reinforcement sections connected together by at least one linking member are part of the same reinforcement strip arranged according to said path. In this configuration, the reinforcement sections of the same strip are connected together by a portion of this strip which follows said path and by at least one linking member as well.
It can be considered that several reinforcement sections of several strips also be connected together by the same reinforcement member.
According to the preceding embodiment, the structure can include a plurality of reinforcement strips that are independent of one another and arranged according to said path where each reinforcement strip comprises two reinforcement sections connected together by a plurality of linking members.
According to another embodiment, at least two reinforcement sections connected together by at least one linking member are part of two separate reinforcement strips, each one being arranged according to said path. In this configuration reinforcement sections of several separate linking strips are connected together by the same reinforcement member.
According to the preceding embodiment, said separate reinforcement strips each include first and second reinforcement sections wherein the first and/or second reinforcement sections are connected together by linking members.
The invention also relates to a reinforcement member intended to reinforce a structure comprising a fill, comprising at least two reinforcement strips with reinforcement sections substantially parallel together, where the reinforcement sections of two different reinforcement strips are connected together by at least one linking member and the reinforcement strips are twisted a half-turn between two linking members. Such a reinforcement member is able to be arranged in the facing in order to realize a structure where the reinforcement sections of several separate linking strips are connected together by the same reinforcement member.
According to the invention, said reinforcement member can have the following characteristics, alone or in combination:
The invention also relates to a method of manufacturing of a reinforcement member intended to reinforce a structure comprising a fill comprising the following successive steps:
The aforementioned reinforcement member can thus be realized. According to an embodiment of said method, the reinforcement strips are twisted a half-turn before arranging at least one linking member on each side of the twisted portion.
The invention also relates to a method of manufacturing a soil reinforced structure comprising a fill, reinforcement strips comprising reinforcement sections which extend in a reinforced area of the fill located at 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 comprising the following steps:
The strip can be put into place according to the path as soon as the casting of the prefabricated members with or without protective shaft. The use of such a shaft insulates the strip from the casted material in order to protect the reinforcement from premature damage. In particular, if the reinforcement is procured by polyester fibers, it is known that the latter poorly admit basic environments such as those found in concrete. The aforementioned shaft thus supplements the protection conferred by the plastic sheath which coats the polyester fibers of the strip.
If a protective shaft is used, the reinforcement strips are introduced after the casting and the link of the reinforcement sections with a linking member is carried out after the introduction of the reinforcement strips into the prefabricated members. In the case where the use of a protective shaft is not desired, the introduction of the reinforcement strips can be carried out either after or before the casting. It is generally advantageous to carry it out before the casting and it is possible to cast the prefabricated members with the reinforcement strips which can be connected by a linking member either before, or after the casting. The incorporation at the time of casting of reinforcement strips connected together beforehand by linking members can be advantageous as it makes it possible to separate the steps of implementing the method and to prepare the reinforcement strips connected together independently of the step of casting. This can result in significant gains in productivity.
Several arrangements are possible for the path defined for the strip within the facing member. In certain embodiments, the two curved portions of the path direct the strip towards the same side of the protruding plane. In this case, a first possibility is that the path is formed in such a way that the strip is received in the two rectilinear portions with the same face of the strip directed towards this side of the protruding plane. The path is then formed in such a way that said face of the strip is placed either on the exterior side or on the interior side of the loop located outside of the protruding plane. A second possibility is that the path is formed in such a way that the strip is received in one of the two rectilinear portions with a face of the strip directed towards said side of the protruding plane and in the other of the two rectilinear portions with said face of the strip directed opposite of said side of the protruding plane.
In another embodiment, the two curved portions of the path direct respectively the strip towards two sides opposite the protruding plane, and the connecting portion of the path has two loops respectively prolonging the two curved portions of the path and a portion crossing the protruding plane and connecting together the two loops.
Other particularities and advantages of this invention shall appear in the description hereinafter of examples of embodiments that are not limiting, in reference to the annexed drawings, wherein:
For reasons of clarity, the dimensions of the different members shown in these figures are not in proportion with their actual dimensions. In all of the figures, identical references correspond to identical members.
According to the invention, “reinforcement strip” 2 means a continuous strip. Such a strip can include one or several reinforcement sections 82, 83, 84 extending in a reinforced area of the fill 1. Generally, but in a non-limited way, a reinforcement strip comprises two reinforcement sections.
The reinforcements 2 consist of synthetic reinforcements in the form of flexible strips extending in horizontal planes at the rear of the facing 3. It can in particular entail polyester fiber-base reinforcement strips sheathed with polyethylene.
The reinforcement strips 2 are attached to the prefabricated members 4 assembled to form the facing 3. These members 4 are typically made of reinforced concrete. In the example shown, they are in the form of panels. They could also have other forms, in particular a block. When the concrete of such a member 4 is cast, one or several reinforcement strips 2 are installed in the cast according to a path described further on in order to realize the strip-member anchoring. After the concrete has set, each strip has two sections which exit the member in order to be installed in the packed pad.
In order to edify the structure, it is possible to proceed as follows:
a) set in place a portion of the facing members 4 in order to be able to then add fill material over a certain height. In a known manner, the assembling and the positioning of the facing members can be facilitated by assembling members placed between them. The strips 2 are positioned on the facing members 4 in such a way that some of them are placed at the same horizontal level during the assembling of the facing;
b) add fill material and compact it progressively until the next level is reached provided for the setting in place of the reinforcement strips 2;
c) spread the reinforcement strips 2 on the fill to this level;
d) add fill material on top of the reinforcement strips 2 which have just been installed. This fill material is compacted as it is added;
e) repeat steps b) to d) if several levels of strips are provided per row of facing members 4;
f) repeat steps a) to e) until the upper level of the fill is reached.
During the adding and the compacting of the fill material, the reinforcement strips 2 already set into place in the lower levels become taught. This becoming taught is the result of the friction between the strips and the packed material and assures the reinforcing of the structure. So that the tension can establish itself in good conditions, it is suitable for the strips of a level exit their facing members as all being well aligned on this level. It is further suitable that they be directed horizontally as soon as they exit from the facing, in order to avoid them from twisting in the packed pad.
On their protruding points 6 outside from a facing member, the two sections of a strip 2 are in the same protruding plane P (perpendicular to the plane in
A path 20 corresponding to a case wherein a plurality of linking strips connect together reinforcement sections of the same reinforcement strip, is shown in
Each rectilinear portion 81 of the path of the strip is prolonged by a respective curved portion 9 wherein the strip is diverted outside from the protruding plane P. Beyond this curved portion 9, the strip 2 extends along the forward face of the member, slightly withdrawn in relation to forward this in order to not be apparent on the surface of the structure.
The two curved portions 9 are connected together by a connecting portion which has a loop 10 located outside of the protruding plane P.
In this example, the strip is directed towards the same side P1 of the protruding plane P in the two curved portions 9 of its path within the facing member 4. This path is formed in such a way (i) that in the two rectilinear portions 8, the strip has the same face directed towards the side P1 of the protruding plane, and (ii) that this face of the strip is placed on the exterior side of the loop 10. Consequently, in the middle of the loop 10, the strip is placed practically perpendicularly to the rear face 7 of the member.
Two reinforcement sections 82 each prolong a rectilinear portion 81 of said path, beyond a protruding point 6. A rectilinear portion 81 extended by a reinforcement section 82 constitutes a rectilinear portion 8 of a reinforcement strip 2. In the case shown, two rectilinear portions 8 of the same reinforcement strip are arranged substantially in parallel. The two reinforcement sections 82 are connected together by a plurality of linking members 11, constituted in the example shown of strips of likewise nature as the reinforcement strip 2. These linking strips 11 can be stapled, glued or connected by any other means to the reinforcement sections 82 in a zone 111.
In the example shown, the linking members 11 are arranged according to an angle α substantially equal to 90°, where the angle α measures the angular separation in the plane P between the axis 80 of a reinforcement section 82 and the axis 110 of a linking member 11.
The linking members 12 and 13 are arranged according to an angle α substantially equal to 90°, where the angle α measures the angular separation in the plane P between the axis 80 of a reinforcement section, for example 84 and the axis, for example 120 of a linking member 12.
In the embodiments shown, the linking members 13 that connect together the second reinforcement sections 83 are arranged below the first reinforcement sections 84. These linking members 13 are connected, in particular via stapling or gluing, by the top to the second reinforcement sections 83 in the zones 131 and pass under the first reinforcement sections 84 in zones 132.
The linking members 12 that connect together the first reinforcement sections 84 are connected, in particular via stapling or gluing, to the lower face of the first reinforcement sections 84 in zones 121. These linking members 12 are arranged above the second reinforcement sections 83 in zones 122.
In the alternative shown in
In the alternative shown in
In the alternative shown in
Other arrangements are still possible for the path of the reinforcement strip inside a facing member.
Note that the loops 101, 102, 103, 104 shown respectively in
In order to easily follow a path such as those shown in
The reinforcement member can then be arranged in a cast and a prefabricated member can be realized after casting, in particular with concrete. After arrangement in a fill to be reinforced, the configuration shown in
By folding back, according to the direction of the arrow shown, the portion comprising the reinforcement sections 84a and the linking members 12a above the portion comprising the reinforcement sections 83a and the linking members 13a, a loop is obtained in the central area of the reinforcement member, between each pair of reinforcement sections 83a, 84a.
The loops which are formed as such are of the type of loops 103 shown in
Generally, the method of reinforcing proposed, using a facing of a soil reinforced structure and reinforcement strips, is compatible with a large number of configurations of structure, strip lengths, densities for setting up strips, etc.
| Number | Date | Country | Kind |
|---|---|---|---|
| 07 01579 | Mar 2007 | FR | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/FR2008/050347 | 2/29/2008 | WO | 00 | 9/4/2009 |
| Publishing Document | Publishing Date | Country | Kind |
|---|---|---|---|
| WO2008/122733 | 10/16/2008 | WO | A |
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| Number | Date | Country |
|---|---|---|
| 1 662 050 | May 2006 | EP |
| WO 9935343 | Jul 1999 | WO |
| Number | Date | Country | |
|---|---|---|---|
| 20100092249 A1 | Apr 2010 | US |
