EP2044409A2

EP2044409A2 - Device, system and method of detecting and locating malfunctions in a hydraulic structure, and a hydraulic structure equipped with said device

Info

Publication number: EP2044409A2
Application number: EP07823567A
Authority: EP
Inventors: Olivier Artieres; Cyril Guidoux; Jean-Jacques Fry; Jean-Marie Henault; Sylvain Blairon; Gauthier Vercoutere; Marc Voet; Johan Vlekken; Yves-Henri Faure; Paul Royet; Alain Bernard; Fabrice Daly
Original assignee: Fiber Optic Sensors & Sensing Systems bvba; Electricite de France SA; Universite Joseph Fourier Grenoble 1; TenCate Geosynthetics France
Current assignee: Fiber Optic Sensors & Sensing Systems bvba; Electricite de France SA; Universite Joseph Fourier Grenoble 1; TenCate Geosynthetics France
Priority date: 2006-07-13
Filing date: 2007-07-12
Publication date: 2009-04-08
Also published as: TWI471543B; US20100175460A1; TW200829900A; CA2657712C; CA2657712A1; KR20090101432A; CN101490522B; KR101448103B1; FR2903773A1; CN101490522A; WO2008007025A3; MY152613A; AU2007274104A1; FR2903773B1; US8316694B2; WO2008007025A2

Abstract

The invention relates to a device (10) for detecting and locating a fluid leak in a hydraulic structure, characterized in that it comprises a geotextile (12) provided with at least one optical fiber (14, 141, 142) in contact with said geotextile (12) and able to transmit a modified signal when the temperature varies. Application to leak detection and location in hydraulic structures.

Description

Device, system and method for detecting and locating malfunctions in a hydraulic structure, as well as a hydraulic structure equipped with this device

The invention relates to a device, a system and a method for detecting and locating malfunctions in a hydraulic structure, as well as a hydraulic structure equipped with this device.

By dysfunction, it must be understood in particular, an abnormal fluid leak, but also in particular a deformation or a settlement of the hydraulic structure.

By structure or hydraulic structure, we mean civil engineering works such as canal, pond or river embankments or dikes or levees for protection against floods and dams, but also sealed storage structures such as ponds. , dikes and dams and landfills or other sealing devices (eg pipelines, including pipelines).

In all these works, there is a risk of leakage proven fluid, especially water, contained by the book.

These leaks can come from many different causes among which we can mention, flood overflow, runoff, which can be combined with damage to the strength and / or cohesion of the structure, following a period of drought, land movement, land heterogeneity, aging of the structure, new localized stresses, plant root holes, animal burrows, drainage ducts created by erosion or soil a defect or damage to the sealing structure.

Usually, for the detection and location of leaks in a dike, an optical cable is used longitudinally in the dike, at the foot of the dike, and which can measure the temperature. Thus, by a variation of the temperature, it detects the presence of a leak of water up to the optical fiber. This is evident, for example, from the publication of S. Johansson (1997) (see page Monitoring in Embankment Dams, Doctoral Thesis, Royal Institute of Technology, Stockholm, Sweden. 50 p) or patents DE19506180 and DE10052922. In this case, the information relating to the occurrence of a leak in the structure can arrive relatively late, especially when this leak has been initiated at a location of the dike located high and which is distant from the position of the fiber optical. In addition, the temperature measurement being modified because of the heterogeneity of the surrounding soil fiber optic, it results in greater uncertainty on the threshold of variation which must be considered significant of the presence of a leak.

It is also known from EP0978715 to use optical fibers contained in cables to monitor the condition of tubes or the like carrying gaseous or liquid fluids under pressure. In this case, the cables must be placed in the tubes to be monitored. Finally, another so-called "active" technique combines an electric wire heated with an optical fiber for measuring the temperature, that is to say that the temperature is raised in the vicinity of the optical fiber and the variation in This change is all the more rapid as the circulation of the fluid is important (see the publication of S. Perzlmaier et al (2004): Distributed Fiber Optic Temperature Measurements in Hydraulic Engineering - Prospects of the Heat-up Method , ICOLD annual meeting, Seoul 2004 or patent DE 10052922).

The present invention aims to provide a device and a method for overcoming the disadvantages of the prior art and in particular offering the possibility of detecting a leak faster in a structure, particularly a hydraulic structure.

For this purpose, according to the present invention, the leak detection and localization device is characterized in that it comprises a geotextile provided with at least one optical cable which comprises at least one optical fiber capable of detecting a temperature variation. and transmitting a modified signal when the temperature variation is detected, said optical cable being in contact with said geotextile.

In this way, it is understood that by the contact between the optical fiber (or more generally its support, the assembly being called optical cable, the optical cable may contain several optical or electrical fibers) and the geotextile, it is realized via geotextile, a transfer of information from any area of the geotextile reached by a leak to the fiber / optical cable. Indeed, by the progress of the liquid in the geotextile which is permeable, the slightest water leak that reaches the geotextile, is conducted in a uniform manner to the optical fiber, at which the detected temperature variation triggers. an alert signal.

This solution has the advantage of not limiting the zone monitored to the only zone corresponding to the position of the optical cable but it allows to cover a larger area auscultated by the geotextile, thanks to this phenomenon of drainage and collection of the leak by the geotextile towards the cable.

Thus, for all the measured characteristics, it is partly offset by the choice "a priori" of the location of the optical cable in the structure. This may make it possible to avoid the use of a large number of optical fibers or cables for the purpose of covering (by a relatively tight mesh) the entire sensitive area of the structure, thereby enabling savings to be made. .

We can also mention the protective role of the optical fiber (cable) by the geotextile with which it (he) is in contact, which avoids using the use of large sheathed cables that increase the response time of the measured.

Also, the presence of the geotextile forms a wall, certainly permeable, but which slows the progression of the leak on both sides of the geotextile. Indeed, the geotextile slows the phenomenon of regressive erosion: it clogs locally by suspended soil particles, which has the effect of limiting the flow velocities and therefore the intensity of the scouring of the walls along from the leak.

This braking of the phenomenon of leakage and erosion is very advantageous because it makes it possible, in combination with an increased speed of detection and localization, to save time to allow intervention at a sufficiently early stage so as not to jeopardize the integrity of the work.

This is particularly important in the case of dry dikes to intervene quickly and make the necessary repairs before failure. Overall, thanks to the solution according to the present invention, it is possible to provide ease of implementation during the installation and then use of the detection device and leak location, with greater speed and sensitivity of detection of the occurrence of a leak in a civil engineering work.

This contact between the optical fiber (cable) and the geotextile can be obtained in various ways from the simple laying of the optical fiber (cable) on or against the geotextile until the formation of a fixation or a link between the optical fiber (cable) and the geotextile. Indeed, preferably, said optical cable is connected to said geotextile by connecting means, in particular at least one connecting element. Among the possible connecting elements, it is possible to note the ligature, sewing thread, the warp or weft thread when weaving the geotextile, the glue, a staple, a gripping band, or fibers of each of two geotextiles needled together, each of these connecting elements can be used alone or in combination.

Thus, when such a link, especially mechanical, exists between the optical cable and the geotextile, this solution also has the additional advantage of allowing, in addition, a great ease of installation by the fact that the geotextile is in minus a layer in which the optical fiber (s) (s) is (are) already attached to the desired location (s) depending on the type and shape of the structure, as well as the location of the areas that will be estimated as sensitive to the risk of leakage. By geotextile, is meant in the present description, its broadest meaning, ie a geotextile or a geotextile related product within the meaning of ISO 10318 including a nonwoven geotextile, a composite geotextile drainage, a woven geotextile , grid or knit type. Advantageously, said geotextile is provided with at least one other fiber or optical cable capable of detecting a deformation of the geotextile in the vicinity of the preceding optical fiber (for example deformation of the geotextile if the first characteristic measured was the temperature) and of transmitting a signal modified when deformation of the geotextile is detected. In this way, by simultaneously detecting the temperature variation and deformation or movement of the geotextile, via the deformation of the optical fiber, we can better understand the phenomena that occur. In this case, the contact, and especially the connection, between the fiber

(the cable) optical and geotextile, allows to measure the deformations of the structure by transfer of the movements of the ground towards the optical fiber (the cable) by means of the geotextile.

Also, in this case, because of the good contact properties between the geotextile and its environment, in particular the soil, deformations or movements of the soil are transmitted by friction to the geotextile which in turn transmits them to the fiber (the cable) optical system whose light signal is thus modified, which makes it possible to detect any phenomenon of deformation or movement for a much larger area than when it is an optical fiber (of a cable) alone, without the geotextile.

In addition, the simultaneous detection of the temperature variation and deformations in the structure provides additional information because the measured signals can correspond to cases already observed and recorded for the same type of structure, hence the possibility of to be informed about the nature of the cause of the leak.

According to another advantageous arrangement, said geotextile is provided with an additional optical fiber (cable) capable of detecting a variation of the moisture content near the optical fiber and of transmitting a modified signal when the variation in the moisture content is detected.

Preferably, the relative humidity is measured around the optical fiber (cable) but more generally the measurement can relate to the moisture content of the soil or the environment surrounding the optical cable. In this way, by the simultaneous detection of the variation of the temperature and the humidity rate, a better diagnosis of the phenomenon of leakage can be obtained.

Preferably, the device according to the invention comprises a plurality of optical fibers (cables) arranged substantially parallel to each other (them). Thus, thanks to the presence of several optical fibers (cables) which are similar and which measure the same parameter, notably the temperature, but also the deformations and / or the humidity, one can locate the location and the extent of the leak. It is also necessary to consider the case where it concerns optical cables, among which several of them are located close to each other, forming a bundle of cables, and which measure different parameters, notably temperature and / or deformations. and / or humidity, so that several types of information are obtained on a given location of the geotextile.

According to one variant, said optical cables are grouped together in at least one bundle of optical cables, said bundle being disposed at a location of the geotextile that corresponds to a zone of the structure sensitive to leakage. In this way, by using several bundles of optical cables, each beam measuring several parameters, including temperature and deformation, one can obtain a better diagnosis of the phenomenon of leakage, as well as a more precise location.

According to another preferred arrangement, at least one of said optical cables transmitting a temperature-related signal is disposed at a location of the geotextile which is in an area located near the air.

Thus, the measurement of the air temperature is used by this appropriately placed optical cable, so that this measurement may constitute a reference measurement for monitoring temperature variations at the other locations where this measurement is made.

Advantageously, the device according to the invention further comprises at least one longitudinal heating device (electric heating wire, tube conveying a hot fluid) placed parallel to and adjacent to said optical fiber.

This arrangement makes it possible to implement another measurement technique.

According to another preferred arrangement, said optical cable is monomode or multimode. According to another advantageous arrangement, said optical cable is linked, directly or indirectly, to said geotextile. According to a preferred embodiment, said optical cable or said (other) optical fiber is bonded to the geotextile by at least one connecting element (for example ligating wire, cable, needling, gluing, stapling, gripping tape). In this way, it ensures intimate contact between the cable and the geotextile so that the first becomes a reflection of the state (including temperature, deformation and / or humidity) of the second. This intimate contact by tight mechanical connection is particularly important so that the deformations of the structure that also undergoes the geotextile, are fully retransmitted to the optical fiber (s) (s). According to another embodiment, the device according to the invention comprises a first geotextile and a second geotextile and said optical cable or said optical fiber is inserted (e) between the first geotextile and the second geotextile. In this case, according to one of the implementation possibilities, said optical fiber is linked to the first and second geotextiles or to one of the two of the first and second geotextiles.

According to another implementation possibility, there is no "intimate connection" between the optical fiber and the geotextiles: for example, the two geotextiles are assembled by two gripping strips parallel to the fibers, which can move, in a limited way, inside the space delimited by the two bands.

In this case, the intimate link between each optical fiber and the two geotextiles is ensured by different techniques for connecting each optical fiber to the first and second geotextiles, these techniques being able to be used separately or in combination. Thus, for example, this connection can be made by gluing, needling, welding, use of gripping strips, stapling or sewing between the two geotextiles.

According to another preferred arrangement, the device according to the invention comprises at least one optical fiber placed freely inside a protective tube connected to the geotextile, so that it is not subjected to external mechanical stresses.

In the case of at least two optical fibers, preferably two optical fibers formed respectively of a monomode fiber and a multimode fiber, which are advantageously placed in close proximity to one another, are used. These two optical fibers of different nature can be used for the measurement of different parameters or else to measure the same parameter, using different measurement techniques. In the latter case, this measurement can be carried out for different types of equipment, for example equipment operating according to detection techniques based on the Raman effect or on the Brillouin effect.

Thus, globally according to the invention, it is possible to choose the type, the number and the location of the optical fibers in the (or between) geotextile (s) in order to adapt the type of detection (temperature only, temperature and deformation, temperature and humidity or temperature and deformation and humidity), and location (s) monitored (s) to the type of structure, site and sensitivity of the desired detection, which allows to predict in a product easy to install, a solution of detection and localization to measure.

We can also choose the type of geotextile corresponding to the desired level of protection of the optical fiber, or to meet the conditions of soil filtration, or to adapt its permeability or its draining properties.

Conventionally, the optimal properties of geotextiles are calculated according to the characteristics of the structure. For example, for a protective function, thick non-woven geotextiles are generally used. For a filtration function, the filtration opening and the permeability of the geotextile are calculated as a function of the characteristics of the soil to be filtered: it is known, however, in the case of nonwovens, that the number of filter constrictions should preferably be between 25 and 40. For a function of erosion retarder of fine material, one will look for filtration openings small enough to retain the particles transported in suspension by the flow.

The invention also relates to a system for detecting and locating leakage of a fluid in a hydraulic structure, which comprises a leak detection and localization device of the type presented above and at least one measuring device connected to said fiber optical and to indicate a variation of the signal transmitted by the optical fiber.

In addition, the invention relates to a hydraulic structure equipped with such a device for detecting and locating leakage, in particular a hydraulic structure formed by a dike (dry or in water), and in which said leak detection and locating device is placed longitudinally in the body of the dike so as to partially cover or at least almost the entire height of the dike.

In the latter case, preferably, said leak detection and localization device is placed in the body of the dike and on the opposite side to the water (downstream side).

Also, preferably, said optical fiber which is disposed at a location of the geotextile which corresponds to an area located near the air, is placed so as to be at the top of the work. In addition, the present invention achieves the objective previously recalled by a method for detecting and locating leakage of a fluid in a hydraulic structure, which is characterized in that a temperature variation is detected by a modification of the emitted signal. by an optical fiber included in an optical cable with a geotextile, this optical cable being placed on or against the geotextile or being linked, directly or indirectly, to said geotextile.

Preferably, this method also makes it possible to detect:

a deformation of the geotextile by a modification of the signal emitted by an optical fiber linked, directly or indirectly, to said geotextile, in particular by a ligation wire, and / or

a variation of the humidity level of the geotextile by a modification of the signal emitted by an optical fiber linked, directly or indirectly, to said geotextile, in particular by a ligation wire.

Other advantages and characteristics of the invention will become apparent on reading the following description given by way of example and with reference to the appended drawings in which:

FIG. 1 is a diagrammatic perspective view of a partially transparent view of an embodiment of the leak detection and localization device according to the present invention; FIG. 2 is a cross-sectional view of another embodiment of FIG. device for detecting and locating leakage, and

- Figures 3 to 7 show a sectional view of several possible uses of the device according to the invention for a water retaining dike.

If we refer to FIG. 1, the detection and leak location 10 comprises a geotextile 12 on the lower surface of which have been placed parallel to each other several optical fibers (or cables) 14 which are intimately connected to the geotextile 12 by connecting means formed in this case by sewing threads or ligature 16.

Equivalently, it can be provided that the optical cables 14 are directly integrated in a woven geotextile, in particular by being used as warp yarns in a weave of the straight warp construction type. In the case of a woven geotextile, the weft threads are considered as connecting elements (or ligation) on the product.

According to another possibility, particularly in the case of a grid-type geotextile, the optical cables 14 are bonded to the geotextile by means of the coating coating (for example PVC) usually covering the son / strips of the grid.

In the case of a knitted grid-type geotextile made up of several warp and weft yarns or cables, the optical cables can also be connected to the other yarns of the knit by the ligation yarn itself forming a yarn of the knit. According to another embodiment visible in Figure 2, the leak detection and localization device comprises a first geotextile 12 and a second geotextile 13 between which have been inserted several optical fibers (or cables) 14 arranged parallel to each other. This assembly is secured by assembly between the two geotextiles 12 and 13 by connecting means which are, in the case shown, formed again of a sewing thread 16.

Other means of assembly between the two geotextiles 12 and 13 may be provided, in particular from the following: by gluing; by needling between the two geotextiles 12 and 13, especially if these two geotextiles 12 and 13 are formed by nonwovens,

by welding resulting in a melting of the surfaces facing the two geotextiles 12 and 13; by the use of several pairs of adhesive gripping strips, respectively provided with hooks and elements protrusion formed protuberances at their free end (type "Velcro" (registered trademark)) or several bands whose two sides are self-adhesive;

-by stapling; -by sewing.

It is also possible that the optical cable 14 is connected to only one of the two geotextiles 12 and 13, for example by means of a ligature wire or any other assembly means such as those mentioned above. In this case, the means for connecting the optical cable 14 to the geotextile 12 or 13 may be different from the assembly means between the two geotextiles 12 and 13.

In all these cases, it can be expected that the bonding technique between the two geotextiles 12 and 13 is implemented on all of the surfaces opposite the two geotextiles 12 and 13, or else in strips parallel to the geotextile fibers.

Throughout the description, the generic term optical cable is used to denote indifferently a sheathed optical fiber, several optical fibers tightly housed in a sheath, an optical fiber mounted freely in a tube or several optical fibers housed freely in a tube.

Reference will now be made to FIG. 3 illustrating a first use case of the leak detection and localization device 10 making it possible to measure the temperature by means of an optical cable 14. A dike (in water) 20 separates a first "upstream" space filled with water 22 (left in the figure), a second space 24 "downstream" (right in the figure) which must remain dry and protected from any overflow of the water 22.

The dike 20 extends vertically between a dike foot 201 and a top 202 and horizontally under the two spaces 22 and 24. At the level of the space 24, in order to keep the device 10 well pressed against the downstream slope of the body of the dike 20 and under the space 24, there is arranged a soil refill 26 composed for example of sand and / or gravel and / or rocks. A leak detection and locating device 10 has been placed to cover the slope of the dike 20 turned towards the space 24 (downstream slope) by covering almost the entire height of the dike 20 and a substantially horizontal portion extending beneath the soil recharge 26 towards the space 24, beyond the dike foot 201.

In this first case, the device 10 comprises a geotextile 12 connected to a single optical cable 14 which is located at a location considered to be the most sensitive to leakage, namely at the level of the dike foot 201, at the lowest point. from the downstream slope of the dike body 20 turned towards the space 24, namely at a location where the geotextile forms a bend. FIG. 3 furthermore shows schematically the propagation of a leak (arrow 30) along a leakage channel 28 crossing the dam 20 between the spaces 22 and 24 at an average height of the embankment slopes. 20.

This channel 28, which has been dug due to the flow of water 22 at the side wall of the dike 20 turned towards this space 22 (upstream slope), is naturally slightly inclined from the space 22 towards the space 24. In addition, this channel 28 will normally tend to widen due to the phenomenon of regressive erosion which occurs essentially on the side of the side wall of the dike 20 turned towards the dry space 24 (downstream slope).

The geotextile 12 has a soil filtration function of the dike body 20 at the interface with the soil recharge 26. However, in this case, according to the present invention, the geotextile 12 forms at the outlet of the canal on the downstream slope of the dike 20 a barrier, not for the water flowing in the escape channel 28 because the geotextile is permeable, but for the soil particles suspended in the tailrace 28 by the flow of water: thus, the geotextile 12 clogs locally in the extension of the escape channel 28, which has the effect of limiting the flow velocities inside the escape channel 28 and therefore the intensity of the flushing of the walls along the escape channel 28, which delays the expansion of the leak.

Moreover, in addition to this role of clogging and regressive erosion retarder, the geotextile 12 makes it possible to drain (arrow 32) the water flowing in the escape channel 28 to the optical cable 14, which allows accelerate the water presence information at the device 10 to the fiber 14 which is positioned at a location at a different height (in this case below) than the height at which leakage channel 28 is located.

Among the possibilities of choice for the geotextile 12, there may be noted a single or multi-layer nonwoven geotextile, a woven geotextile, a knitted geotextile, a drainage geocomposite comprising a draining geosepterous core of any kind, or any combination thereof. structures, and in particular a composite geotextile produced by the combination of a needled nonwoven and knitted reinforcement cables. The association of reinforcing cables parallel to the optical fibers is interesting to pull on the geotextile during its production or during its installation, during its winding or unwinding, without mechanically stressing the optical cables.

At the bottom of FIG. 3, the detail III corresponding to the location of the optical cable 14 according to three variant embodiments is further enlarged.

In the case of the first embodiment shown on the left (III A) and bottom of Figure 3, the optical cable 14 is a multimode type optical fiber 141 which has a sheath 14a tightly surrounding the optical fiber 141. This type of optical cable 14 is generally used to perform temperature measurements using the Raman effect.

In this case, it is understood that when the leak reaches the optical cable 14, a significant variation of the temperature is detected, which corresponds to the variation between the temperature of the dike 20 and the temperature of the water contained in the space 22. , which makes it possible to create a signal likely to give warning of the presence of a leak at the dike 20.

In this case, it is understood that this measure must have a relative accuracy to allow to give rather an indication of the presence of a leak. In particular, it is estimated that it is necessary to be able to differentiate a temperature difference of 0.1 ^° C. in the most critical cases, which makes it possible to carry out this measurement directly and without resorting to heating the zone in which the measurement is done. In the case of the second embodiment shown in the middle (III B) and at the bottom of Figure 3, the optical cable 14 is composed a monomode type optical fiber 142 which is freely surrounded by a protective tube 14b. This type of optical cable 14 is used to make temperature measurements, using the Brillouin effect.

In the case of the third embodiment shown at right (III C) and at the bottom of Figure 3, an optical cable 14 is used formed of two optical fibers 141 and 142, respectively multimode type and monomode type, which are housed freely in a protective tube 14b.

The presence of the two types of optical fibers 141 and 142 allows temperature measurements by Raman effect and / or Brillouin effect. In this case, depending on the equipment available and which is connected to one or the other or to the two optical fibers 141 and 142, it is possible, at any time and without having to install a different device 10, to realize the measure (s) considered the most adapted, technically and / or economically.

Of course, in all cases, the two ends of the optical cable 14 are respectively connected to a light emitter and a measuring device (not shown) making it possible to interpret the light ray reaching up to it in an indication of the temperature of the light. optical cable 14, that is to say the device 10 at the foot of the dike 201.

Referring now to FIG. 4, which illustrates a second use case of the leak detection and localization device 10 making it possible to perform both a temperature measurement and a deformation measurement by means of a beam 34 of FIG. optical cables 14 having two, three or more optical cables 14.

In the remainder of the description, the same reference signs as those previously used in connection with FIG. 3 designate the same elements, only the elements different from those of the first use case presented in FIG. 3 being described below.

The general arrangement of this second use case is similar to that of the first use case, the only difference being the use not of a single optical cable 14 but of a bundle 34 of optical cables 14. which is always disposed at the foot of said dike, at the bottom of the side wall of the dike turned towards the space 24 (downstream slope). For this purpose, as shown in the four enlargements of detail IV, several alternative embodiments are possible.

In the case of the first embodiment shown at the left and bottom of Figure 4, designated IV A, the beam 34 is composed of two optical cables 14 arranged side by side: a monomode type optical fiber 142 (left) disposed tightly in a sheath 14a and a multimode type optical fiber 141 tightly disposed in another sheath 14a (right). In this case, the monomode optical fiber 142 operates by the Brillouin effect and is intended to measure any deformations of the dike 20, via the deformations of the geotextile 12 and the multimode optical fiber 141 operates by Raman effect and is for measuring the temperature at this height level of the geotextile 12.

In this case, it is understood that the possibility of obtaining these two information of a different nature, namely the temperature and the deformation, makes it possible to better understand the phenomena that occur at the level of the dike 20, to carry out a more thorough monitoring.

In the case of the second embodiment shown in the second position on the left and bottom of FIG. 4, which is designated IV B, two optical cables 14 are also used for the bundle 34, which are in this case composed of a fiber singlemode-type optics 142 (left) arranged tightly in a sheath 14a and a monomode type optical fiber 142 freely disposed in a tube 14b (right).

In this case, the optical fiber 142 clamped in the sheath 14a is used to perform the Brillouin effect deformation measurement, whereas the monomode optical fiber 142 freely disposed in the tube 14b is used to perform the Brillouin effect temperature measurement. .

In the case of the third embodiment shown in the third position at the bottom of FIG. 4, which is designated IV C, a beam 34 composed of two optical cables 14 is also used. It is, on the one hand, still once of a monomode type optical fiber 142 (left) arranged tightly in a sheath 14a (measurement of deformation by Brillouin effect) and, on the other hand, a tube 14b (on the right) in which two optical fibers are housed: a multimode optical fiber 141 (on the left) and a monomode optical fiber 142 (on the other hand). right), this second optical cable 14 for performing the temperature measurement as in the case of the third variant III C of Figure 3.

In the case of the fourth variant embodiment shown in the fourth and last position, on the right and bottom of FIG. 4, and which is designated IV D, a beam 34 composed of two optical cables 14 and an additional thread 15:

- Left: a monomode type optical fiber 142 arranged tightly in a sheath 14a (Brillouin effect deformation measurement);

in the middle: an electric heating wire 15 so that the temperature measurement made by the optical cable 14 on the left is carried out by a so-called "active method" method, previously mentioned and,

on the right: a tube 14b in which two optical fibers are housed: a multimode type optical fiber 141 on the left and a monomode type optical fiber 142 on the right, this second optical cable 14 serving to carry out the temperature measurement as in FIG. case of the third variant III C of FIG.

In the case of these four variants, it is understood that the possibility of obtaining these two different types of information

(temperature and deformation) makes it possible to better understand the phenomena that occur at the level of the dike 20, to carry out a more thorough monitoring.

The nature of the optical cable used for the deformation measurement is not limited to those provided above, but it is possible to provide other types of optical cables such as those using optical fibers with Bragg gratings, particularly as in FIG. document FR 2 844874,

Reference will now be made to FIG. 5 which illustrates a third use case of the leak detection and localization device 10 making it possible to perform both a temperature measurement and a deformation measurement, and this at several locations of the geotextile 12 , by means of several beams 34 of optical cables 14 arranged in the direction longitudinally at different locations of the geotextile, these different locations corresponding to different heights along the side wall (of the downstream slope) of the dike 20 facing the space 24.

In the remainder of the description, the same reference signs as those used previously designate the same elements, only the different elements being described below.

The general arrangement of this third use case is similar to that of the second use case illustrated in FIG. 4, the only difference being the use not of a single bundle 34 of optical cables 14 but of a multiplicity (two, three or more) of beams 34 of optical cables 14, which are arranged not only at the foot of the dike 20, at the bottom of the side wall of the dike turned towards the space 24, but also along the side wall of the dike 20 turned towards the space 24. For this purpose, as shown on the four enlargements of the detail figure V, several variants are possible for each of the beams 34, these beams 34 which may be identical or different from each other.

More precisely, four variant embodiments, designated V A to V D at the bottom of FIG. 5, are provided, which are respectively identical to the four variant embodiments IV A to IV D which have been previously described in relation to FIG. 4.

In this case, the presence of a multiplicity of beams 34 makes it possible not only to measure at each of the locations of these beams 34 both the temperature and the deformation, but also for each of these measurements to be able to identify the corresponding location. of the dike 20 (and also to reduce the path length between the point of convergence between the leakage channel 28 and the geotextile 12, and the beam 34, thus reducing the detection time and location).

In relation to FIG. 6, another variant embodiment in which the leak detection and localization device 10 is arranged, not only, as in the previous cases of FIGS. 3 to 5, along the wall, is now described. lateral (of the downstream slope) of the dike 20 turned towards the space 24 and under the space 24, but also along the peak (crest) 202 of the dike 20, the soil recharge 26 also extending over the crest of the dike 20, above the device 10 and also downstream of the dike 20 (right in Figure 6).

In the fourth use case shown in FIG. 6, the geotextile 12 comprises, all along the device 10, a multitude of bundles 34 of optical cables 14, which makes it possible to give indications of measurement of temperature, of deformation, and optionally of humidity, for each of the locations of its bundles 34 along the top, the dry lateral side and also downstream of the dike 20. This variant embodiment also applies to the second and third use cases respectively represented in Figures 3 and 4.

This variant of embodiment must also be understood as encompassing another use case, namely the situation in which one disposes separately, all along the device 10 for detecting and locating leakage in its extent as represented on FIG. 6, not a multitude of bundles 34 of optical cables but a multitude of optical cables 14 separated individually and making it possible to perform each only the temperature measurement as it has been presented in relation to FIG.

It should be noted that in the case of the present invention, it should also include another case not shown which would be one in which, from the embodiment illustrated in Figure 3 there would be a single cable 14 for the measurement of temperature at different locations of the geotextile 12, along the height of the side wall (of the downstream slope) of the dike 20 turned towards the space 24, and this in order to identify the location of each of the temperature measurements .

Reference is now made to FIG. 7, which represents a fifth use case of the leak detection and localization device 10, in which, this time, it is not placed on the side of the side wall (of the downstream slope). of the dike 20 turned towards the space 24 but along the side wall (of the upstream slope) of the dike 20 turned towards the water retaining space 22.

For this purpose, between the leak detection and localization device 10 and the side wall of the dike 20 turned towards the space 22, there is provided a sealing structure of any kind, such as, for example, hydraulically or bituminous binder concrete, a clay material, a geocomposite based on clay material (geocomposite clay line) or a geomembrane 36 which protects the leak detection and localization device 10 against any ingress of water which does not would not be due to the presence of a leak.

In this case, as illustrated in FIG. 7, the leak detection and localization device 10 extends longitudinally along (the upstream slope) of the lateral wall of the dike 20 turned towards the space 22. as well as at the foot of the dike 201, slightly below the space 22, the geomembrane 36 projecting well beyond the maximum height of the device 10, along (the ridge) of the summit 202 of the dike 20, and under the space 22.

Again, several configurations are possible for the optical cable (s) 14 present in the geotextile 12 of the leak detection and localization device 10: a single optical cable 14 measuring the temperature, a plurality of separate optical cables 14 measuring the temperature at locations different, a single bundle of optical cables 14 measuring the temperature and the deformation, or, as illustrated in FIG. 7, several bundles 34 of optical cables are used in order to measure both the temperature and the deformation (as well as , possibly humidity) at different locations along the detection and location device 10.

It should be noted that in the context of these second to sixth uses respectively described in connection with FIGS. 3 to 7, it is possible (not shown) to perform in addition to the temperature measurement and the possible measurement of deformation, a moisture measurement by arranging in each beam 34 an additional wire to perform this measurement (see for example EP 1 235 089).

Also, among the other possible variants within the scope of the present invention, it is necessary to note the possibility of inserting in the leak detection and localization device 10, in particular in or on the geotextile (s) 12 (and 13), fibers / reinforcing cables (made of polymer such as polyester, polypropylene, aramid, Kevlar, etc ... or other material offering a high modulus of tensile stiffness) parallel to the optical cables 14, and this in particular to be able to , during installation on site of the leak detection and localization device 10, unwinding a roll and pulling the product without damaging the optical cables 14.

The measurement of all the previously mentioned parameters (in particular temperature, signal representative of a deformation and humidity) can be carried out continuously or discontinuously at times t0, t1, t2, independently or simultaneously.

It is also possible for the detection and localization device to consist of strips or rollers placed parallel to each other either side by side, possibly with a small overlap of the one over the other, or spaced apart from each other. one of the other. In the latter case of spaced strips, it is envisaged that they are in contact with a draining layer placed below or below them, this draining layer can be made of granular material, sand or gravel type, or geotextile or related product.

Claims

1. Device (10) for detecting and locating leakage of a fluid in a hydraulic structure, characterized in that it comprises a geotextile (12) provided with at least one optical cable (14) which comprises at least one optical fiber (141,142) adapted to detect a temperature variation and to transmit a modified signal when the temperature variation is detected, said optical cable being in contact with said geotextile.

2. Device (10) according to claim 1, characterized in that said optical cable (14) is connected to said geotextile by connecting means (16).

3. Device (10) according to any one of the preceding claims, characterized in that said geotextile is provided with at least one other optical fiber (141,142) capable of detecting a deformation of the geotextile near the optical fiber and to transmit a signal modified when the deformation of the geotextile (12) is detected.

4. Device (10) according to any one of the preceding claims, characterized in that said geotextile is provided with at least one other optical fiber (141,142) capable of detecting a variation in moisture content near the optical fiber and transmitting a modified signal when the variation of the humidity level is detected.

5. Device (10) according to claim 3 or 4, characterized in that said at least one other optical fiber (141, 142) is bonded to said geotextile by connecting means (16).

6. Device (10) according to any one of the preceding claims, characterized in that it comprises a plurality of optical fibers (141,142) disposed substantially parallel to each other.

7. Device (10) according to claim 6, characterized in that said optical fibers are grouped into at least one bundle (34) of optical fibers, said bundle (34) being disposed at a location of the geotextile (12) which corresponds to an area of the work susceptible to leaks.

8. Device (10) according to any one of the preceding claims, characterized in that at least one of said optical fibers (141,142) transmitting a temperature-related signal is disposed at a location of the geotextile (12) which is in an area near the air.

9. Device (10) according to any one of the preceding claims, characterized in that it further comprises at least one longitudinal heating element (15) placed parallel to and adjacent to said optical fiber (141,142).

10. Device (10) according to any one of the preceding claims, characterized in that said optical fiber (141,142) is monomode or multimode.

11. Device (10) according to any one of the preceding claims, characterized in that it comprises a first geotextile (12) and a second geotextile (13) and in that said optical cable (14) is inserted between the first geotextile (12) and the second geotextile (13).

12. Device (10) according to the preceding claim, characterized in that said optical cable (14) is bonded to at least one of the first and second geotextiles (12, 13) by connecting means.

13. Device (10) according to claim 2, 5 or 12 characterized in that said connecting means comprise at least one connecting element (16).

14. Device (10) according to claim 7, characterized in that it comprises at least one optical fiber (14, 141, 142) freely placed inside a protective tube (14b) connected to the geotextile (12).

15. System for detecting and locating leakage of a fluid in a hydraulic structure, characterized in that it comprises a device (10) according to any one of the preceding claims and at least one measuring device connected to said fiber optical (141,142) and for indicating a variation of the signal transmitted by the optical fiber (141,142).

Hydraulic structure equipped with a device (10) for detecting and locating leakage according to any one of claims 1 to 14.

17. Hydraulic structure according to the preceding claim, characterized in that it is formed of a dry dam or water (20) and in that said device (10) for detecting and locating leakage is placed longitudinally in the body the dike so as to cover at least part of the height of the dike.

18. Hydraulic structure according to the preceding claim, using a device (10) for detecting and locating leakage according to claim 8, characterized in that said optical fiber (141,142) which is disposed at a location of the geotextile (12) which is in an area close to the air, is placed so as to be at the top of the work.

19. A method for detecting and locating leakage of a fluid in a hydraulic structure, characterized in that a variation in temperature is detected by a modification of the signal emitted by an optical fiber (141, 142) included in an optical cable (14). ) in contact with and linked to a geotextile (12).

20. Method according to the preceding claim, characterized in that detects, in addition, a deformation of the geotextile (12) by a modification of the signal emitted by an optical fiber (141,142) included in an optical cable (14) related to said geotextile (12).

21. Method according to any one of claims 19 and

20, characterized in that, furthermore, a variation of the humidity level of the geotextile (12) is detected by a modification of the signal emitted by an optical fiber (141,142) included in an optical cable (14) connected to said geotextile ( 12).

22. Process according to any one of claims 19 to

21, characterized in that said optical cable (14) is connected to said geotextile by connecting means.

23. Method according to the preceding claim, characterized in that said connecting means comprise at least one connecting element (16).

24. Method according to any one of claims 19 to 23, characterized in that one uses several optical fibers (141,142) similar disposed substantially parallel to each other.

25. A method according to any one of claims 19 to 24, characterized in that said optical fibers (141,142) are grouped into at least one bundle (34) of optical fibers, said bundle (34) being disposed at a location of the geotextile ( 12) which corresponds to an area of the work susceptible to leaks.