EP1325541A1

EP1325541A1 - Method for embedding in a road surface optical fibre claddings, and resulting pavement

Info

Publication number: EP1325541A1
Application number: EP01969891A
Authority: EP
Inventors: Florence Richard; Jean-Pierre Ronseaux
Original assignee: SANEF; Sanef SA
Current assignee: SANEF; Sanef SA
Priority date: 2000-10-02
Filing date: 2001-09-14
Publication date: 2003-07-09
Also published as: WO2002029947A1; FR2814793A1; FR2814793B1; AU2001290024A1

Abstract

The invention concerns a method for embedding in a road pavement claddings designed to house optical fibre cables, characterised in that it consists in: a) levelling at least part of the running surface (7) of the road and optionally part of the base layer (8) of said road, to produce a continuous slot (4); b) laying flat the claddings (5) at the base (6) of said groove (4), at least some of the claddings being non-contiguous to create a space (e) between the claddings (5); refilling at least partly the groove (4) with concrete (14) to cover the claddings (5); d) providing above said concrete (14) a running surface layer (11, 12).

Description

METHOD OF LAYING FIBER SLEEVES FOR OPTICAL FIBERS ON A ROAD PAVEMENT, AND PAVEMENT THUS OBTAINED.

The present invention has for ob and a method of laying in a roadway, sheaths intended to receive fiber optic cables.

Currently, the sheaths for fiber optic cables are, in the case of motorways, placed either on the emergency stop strip (BAU), or on the left flared strip (BDG) of a motorway, or even on the ber e.

A first known method for laying on the emergency stop band or the left flared band, consists in making a trench, using a trencher, over a width of about ten centimeters and a depth of around 30 cm. Then, we evacuate the rubble, we vacuum it to clean the trench, we put the sheaths in clusters at the bottom of the trench, and we fill the trench with concrete and we perform a repair of the tread.

This technique, which ensures good positioning of the sleeves, is however expensive, in particular because of the large depth of the trench produced. Another known technique consists in placing the sheaths in the ground in the berm by digging down to 70 or 80 cm deep with a mechanical shovel or manually, and by implementing a bed of sand at the bottom of the excavation on which the sheaths are deposited in several layers. It is then filled up to a height of -30 cm with the extracted earth, after which a warning grid is put in place and the backfilling is finished with the extracted earth.

This technique is also expensive, because it requires deep earthwork (70 to 80 cm) in order to protect the sleeves. On the other hand, the installation on road or on highway is, for one and the other of the above processes, dependent on singular works: lower and upper points, crossing of ramps, and service access.

These techniques are in fact not suitable for these particular crossings, hence an additional cost for the passage of the sleeves.

The present invention relates to a laying process which is more economical than the aforementioned processes, and which allows easy crossing of at least a major part of single structures.

The invention thus relates to a method of laying sheaths intended for receiving optical fiber cables in a road pavement, characterized in that it implements: a) planing of at least part of the thickness of the wearing course of the roadway and possibly of a part of the base layer of said roadway, to make a continuous groove or groove, b) placing the sleeves flat at the bottom of said groove, at least some of these sleeves being non-contiguous to create at least one space between the sleeves, c) at least partially filling the groove with a concrete to cover the sleeves, d) producing above said concrete a surface surface layer. The depth of the groove obtained by planing can be between 6 cm and 12 cm and preferably between 8 cm and 10 cm.

The thickness of the concrete filling layer, taken above the upper generatrix of the sleeves, is advantageously at least equal to 3 cm. The surface surface layer can be produced by a cold-cast mix or by depositing an emulsion and graveling, or even using bituminous concrete. The method can implement the installation of jumpers to maintain the space or spaces between the sleeves, and to keep the sleeves at the bottom of the groove.

According to a preferred embodiment, the method implements, before c, the passage of a sheath for placing the sleeves with a desired space e between the sleeves.

The installation of arches and / or the passage of a rake makes it possible to ensure a good return to the ground and a good distribution of the vertical forces, but also to avoid that the sleeves do not make horizontal undulations, in order to be able, then , easily equip them with optical fibers.

It is particularly advantageous for said space e between the sleeves to have a value of between 0.5 and 2 times the diameter D of the sleeves.

The invention also relates to a roadway comprising sheaths intended to receive optical fiber cables, which are housed in at least one groove filled with cement and covered with a surface surface layer, characterized in that the sheaths are arranged in a single layer at the bottom of a said groove which is situated in a wearing course of the roadway or else in a surface region of a base layer of said roadway, and in that at least some of said sleeves are non-contiguous to create at least one space between the sleeves, the filling cement also filling the inter-sleeve space (s) to form one or more bearing regions on the bottom of the groove. The groove has a depth of, for example, between 6 cm and 12 cm and preferably between 8 cm and 10 cm.

The thickness h ′ of the concrete filling layer, taken above the upper generatrix of the sleeves is advantageously at least equal to 3 cm.

Said space e between the sleeves advantageously has a value between 0.5 times and 2 times the diameter D of the sleeves. Riders for maintaining the spaces between the sleeves are advantageously arranged at regular intervals along the groove.

The roadway can be characterized in that at least one said groove is formed in a region of the roadway located outside the area where the traffic takes place, in particular the emergency stop lane, or else the leveled strip d 'a highway.

Other characteristics and advantages of the invention will appear better on reading the description which follows, given by way of nonlimiting example, in conjunction with the drawings in which:

- Figures 1 and 2 illustrate the techniques of the prior art;

- Figure 3 is a diagram of a roadway in which is formed a groove according to the invention;

- Figures 4 and 5 show in section a floor made by the method according to the invention and according to two different embodiments; Figure 6 illustrates a hoop for maintaining the spaces between the sleeves.

FIG. 1 illustrates the first method of the prior art mentioned above, in which a slitting with a width of about ten centimeters and a depth of the order is carried out using a slicer about thirty centimeters on the emergency stop band (BAU) or on the left flared band (BDG) of a highway. This trench crosses the wearing course 7 of the roadway (whose thickness is of the order of 8 cm) and almost all or even all of the base layer 8 based on asphalt in general bituminous whose height is generally of the order of 25 to 30 cm and below which is the foundation layer 9 which consists of treated gravel. In this trench, which is therefore pierced at the limit of the foundation layer 9, and after evacuating the rubble and passing a vacuum cleaner in order to clean the trench, the sleeves 5 are placed in a cluster at the bottom of the trench and the trench is then filled in with concrete, either completely with subsequent laying of an emulsion and gravel or a cold-cast mix 11 as shown on the left side of FIG. 1, or else by a concrete filling up to '' at a height of approximately -2.5 cm with implementation over bituminous concrete 12 as shown on the right side of Figure 1. If this technique ensures good positioning of the sleeves, the depth of the trench made and its subsequent filling with concrete makes it expensive. In particular, the concrete layer must have a sufficient thickness to avoid degradation by rolling vehicles of the integrity of the sheath clusters 5, which are intended to receive fiber optic cables.

Figure 2 illustrates an installation in the open ground with earthworks up to 70-80 cm deep with a mechanical shovel or manually, the implementation of a sand bed 22 at the bottom of the excavation, sand bed 22 on which the sleeves are placed in several superimposed layers, after which, the trench is filled up to a height of -30 cm with the earth extracted to allow the implementation of a warning grid 21 and after which the backfilling is finished with the extracted land.

It can be seen that this method of laying in open ground is costly because of the depth of earthwork and the double filling operation required by the warning wire mesh 21.

This known technique can be improved by carrying out a mechanized installation with the plow with simultaneous placement of the sleeves and the warning mesh. The plow used then makes a trench of a depth such that the generator of the sleeves placed above is located approximately 70 cm from the surface of the ground.

The fact remains that the technique remains expensive and does not allow the crossing of particular works.

FIG. 3 diagrammatically represents a motorway lane 1 of which the emergency stop strip 3 is delimited by a continuous line 2. In this emergency stop strip 3, a trench 4 of width L and depth h at the bottom 6 of which there are flat and on a single layer sleeves 5 of diameter D, which are spaced by a distance e. The process involves planing at a shallow depth (6 to 12 cm, preferably 8 to 10 cm) over a width L, for example of 60 cm, removal of the cuttings, cleaning of the bottom and of the edge of the groove 4 , placing the sleeves 5 flat in the groove. Jumpers 30, for example made of polyvinyl chloride, arranged regularly along the groove, make it possible to maintain the spacing e between the sleeves.

The groove 4 is then at least partially filled with concrete 14. Alternatively, the spacing between the sleeves can be obtained by raking the bottom of the groove immediately before depositing the filling concrete. Two types of filling can be implemented, namely a total filling with concrete 14 and an implementation of an emulsion and a gravel, or else a cold-cast mix 11 (FIG. 4); an alternative solution is filling in concrete 14 up to a height of, for example, 2.5 cm and using bituminous concrete 12 (Figure 5).

One can in particular deposit ten sheaths of outside diameter 33 mm in a trench of width 60 cm and depth h of 8 cm, or else for example 8 sheaths of diameter 40 mm in a trench 4 of depth 9 cm, the trench always having a width L of 60 cm. These dimensions make it possible to retain, above the upper generatrices 15 of the sleeves 5, a thickness h ′ of concrete capable of withstanding the stresses. In particular, maintaining a spacing e between the sleeves, which is advantageously comprised, between 0.5 times and 2 times the diameter D of the sleeves makes it possible to strengthen the protection of the sleeves since, when filling with cement 14 , these intervals of width e are filled with cement, which forms arches in the manner of a bridge to transmit the mechanical stresses due to rolling from the surface to the bottom 6 of the grooves 4. The sleeves 5 could be grouped in groups 2 contiguous sleeves (or more), separated by intervals e calculated accordingly, to maintain an arch structure of appropriate strength.

In this way, the filling with concrete 14 allows good resistance to traffic. AFNOR rutting tests have shown the validity of the process, these tests only leading to deformation of the mix without deterioration of the concrete 14 and the sleeves 5.

An advantage of the method according to the invention is that it can be implemented with machines currently used for asphalt planing sites. As a result, the development of specific tools is not useful. In addition, in order to achieve high implementation yields, it is also possible to automate the site by continuously planing the groove 4, laying the sleeves 5, filling with concrete 14 and repairing (11, 12) of the roadway.

Because the process is implemented in areas not intended mainly for traffic

(emergency stop strips, left flared strips) suggests a long service life due to the positive result of the above test, which corresponds to a very high number of passages on a roadway. In addition, since the method only requires a groove to be made in a surface area of the roadway, it is possible to cross a certain number of works such as bridges, etc. for which the groove 4 could be formed in the thickness of the wearing course without adversely affecting the tightness of the structure.

During installation, at least some of the sleeves 5 can be pre-equipped with a fiber optic cable 16

Claims

1) Method for laying sheaths intended for receiving optical fiber cables in a road pavement, characterized in that it implements: a) planing of at least part of the thickness of the wearing course ( 7) of the roadway and possibly of a part of the base layer (8) of said roadway, to produce a continuous groove (4), b) flat positioning of the sleeves (5) at the bottom (6) of said groove (4), at least some of these sleeves (5) being non-contiguous to create at least one space (e) between the sleeves (5), c) at least partially filling the groove (4) with a concrete (14) for covering the sleeves (5), d) producing above said concrete (14) a surface surface layer (11, 12).

2) Method according to claim 1, characterized in that the depth of the groove (4) obtained by planing is between 6 cm and 12 cm and preferably between 8 cm and 10 cm.

3) Method according to one of claims 1 or 2, characterized in that the thickness h 'of the concrete filling layer (14), taken above the upper generator (15) of the sleeves (5), is at least equal to 3 cm.

4) Method according to one of claims 1 to 3, characterized in that the ^' surface bearing layer (11) is produced by a cold-cast mix or by depositing an emulsion and graveling.

5) Method according to one of claims 1 to 3, characterized in that the surface surface layer (12) is produced using a bituminous concrete. 6) Method according to one of the preceding claims, characterized in that it implements the installation of jumpers (30) to maintain the space or spaces between the sleeves. 7) Method according to one of claims 1 to 5, characterized in that it implements, before c, the passage of a rake for placing the sleeves (5) with a desired space e between the sleeves.

8) Method according to one of the preceding claims, characterized in that said space e between the sleeves (5) has a value between 0.5 and 2 times the diameter D of the sleeves (5).

9) Road pavement comprising sheaths intended to receive optical fiber cables, which are housed in at least one groove filled with cement and covered with a surface surface layer, characterized in that the sheaths (5) are arranged in a single layer at the bottom (6) of a said groove (4) which is located in a wearing course (7) of the roadway or else in a surface region of a base layer (8) of said roadway, and that at least some of said sleeves (5) are non-contiguous to create at least one space e between the sleeves, the filling cement (14) also filling the space (s) inter-sleeves to form one or more regions bearing on the bottom (6) of the groove (4).

10) Roadway according to ^• claim 9, characterized in that the groove (4). has a depth between 6 cm and 12 cm and preferably between 8 cm and 10 cm.

11) Pavement according to one of claims 9 or 10, characterized in that the thickness h 'of the concrete filling layer, taken above the upper generatrix (15) of the sleeves (5) is at least equal to 3 cm. 12) Pavement according to one of claims 9 to

11, characterized in that said space e between the sleeves (5) has a value between 0.5 times and 2 times the diameter D of the sleeves (5). 13) Pavement according to one of claims 9 to

12, characterized in that it has jumpers (30) for maintaining spaces between the sleeves (5), which are arranged at regular intervals along the groove (4). 14) Pavement according to one of claims 9 to

13, characterized in that at least one said groove (4) is formed in a region of the roadway located outside the area where traffic takes place, in particular the emergency stop lane (BAU), or else the highway strip (BDG).