EP2505714B1 - Method for draining a system for anchoring a structural cable to a construction element - Google Patents

Description

The present invention relates to a method of emptying an anchoring system of a structural cable to a construction element.

The structural cable in question may be in particular a guy, a hanger or a prestressing cable.

It is common that the structural cables usually encountered comprise a plurality of strands which each comprise metal wires themselves wrapped together in a protective sheath. Each of these protective sheaths is interrupted at an end wafer so that the strands each have a stripped end section.

• un bloc d'ancrage perforé sur lequel sont ancrés individuellement le ou les tronçons d'extrémité dénudés du câble,
• une portée qui est solidaire de l'élément de construction et contre laquelle est en appui axial le pourtour du bloc perforé,
• une ou plusieurs chambres contenant des parties dénudées du câble de structure (éventuellement divisé en brins), ainsi qu'une matière de remplissage. Il existe notamment, en général, une chambre première située du côté du bloc d'ancrage par lequel arrive le câble de structure et dans laquelle les gaines de protection s'interrompent.

The anchoring systems usually encountered, as presented in the documents US 5173982 A1 and GB 2148351 A , include:

• a perforated anchor block on which are anchored individually or bare end sections of the cable,
• a bearing which is integral with the construction element and against which is axially supported the periphery of the perforated block,
• one or more chambers containing stripped portions of the structural cable (optionally divided into strands), and a filler. In particular, there is generally a first chamber located on the side of the anchor block through which the structural cable arrives and in which the protective sheaths are interrupted.

The filler is usually a petroleum wax, or a fat. It is injected hot into the anchoring chamber or chambers after the cable is put in place and anchored. It forms after cooling a solid or a thick paste that adheres to the stripped cable and provides the desired seal.

However it may be useful to change the filling material, either during construction because it would have been poorly injected or during the life of the construction work, during maintenance operations of the system anchor. For some rooms of the anchoring system, this is not a problem. For example, for a chamber located under a hood and containing the end portion of the structural cable that protrudes from the anchor block, the filler may be removed with a trowel and / or a current hot air.

At present, there is no method for draining some rooms of the anchoring system difficult to access, for example a chamber located behind the anchor block, in a part of the anchoring system embedded in the construction work.

The present invention aims to remedy all or some of the disadvantages mentioned above, that is to say in particular to provide a method for draining an anchoring system of a structural cable having a filled chamber filling material difficult to access.

• insertion d'au moins un élément chauffant au sein de la première matière de remplissage par une ouverture de l'enveloppe de la première chambre ;
• chauffage de la première matière de remplissage à l'aide de l'élément chauffant pour fluidifier tout ou partie de la première matière de remplissage; et
• extraction de la première matière de remplissage fluidifiée par une ouverture de l'enveloppe de la première chambre.

The solution of the invention relates to a method of emptying an anchoring system of a structural cable to a construction element, the anchoring system comprising a first chamber defined by an envelope, the first chamber containing a first portion of the structural cable and a first filling material, the method comprising the following steps:

• inserting at least one heating element into the first filling material through an opening of the casing of the first chamber;
• heating the first filler with the heater to fluidify all or part of the first filler; and
• extracting the first fluidized filling material through an opening of the envelope of the first chamber.

The filler, although solid at room temperature, is quite soft and it is possible to enter a heating element. It usually occupies the entire first chamber, so as to wrap the bare part of the cable. The filling material may have a protective role of the cables that it surrounds.

In the insertion step, at least one heating element is passed through an opening in the envelope delimiting the first chamber. He can be It is advantageous to use several heating elements passing through several openings, or by the same opening, so as to accelerate the heating.

The opening or openings may be pre-existing, for example, it may be holes in the anchor block and used to fill the chamber. Alternatively, the openings can be made especially for the emptying operation.

By "fluidify" is meant to "make fluid enough to flow through an opening of the type used to introduce the heating element. For a wax, it is liquefaction. For a fat, it is a matter of lowering the viscosity sufficiently.

The heating element may be of any kind appropriate to the filling material that it is a question of fluidizing, without it catching fire. If the structure cable is partly sheathed in the chamber, care must be taken not to damage this sheath, which generally melts at around 180 ° C.

It is therefore possible to circulate a coolant in the heating element, the fluid having been previously heated. The heat can also be produced directly in the heating element, within the filler material to be heated.

The purpose of the heating is normally to fluidify all the filler, or at least a large part. At a minimum, the filler is fluidized in an area where it contacts the stripped wire.

The heat is communicated from the heating element to the filling material being fluidized. The hot filling material moves by convection and helps to melt the remaining material.

The extraction of the fluidized filling material is done by opening the envelope of the first chamber. This opening may be the same as that used for the introduction of the heating element (s). Several openings can be used for extraction, so that all the liquid can be removed more easily.

The method is relatively simple to implement. It makes it possible to empty the filling material in a non-intrusive manner, without any notable alteration of the structure of the anchor. It remains functional and can be refilled with filling material.

• l'élément chauffant comprend une partie sensiblement cylindrique ayant une extrémité par laquelle, durant l'étape d'insertion, on le fait pénétrer dans la première matière de remplissage. Une telle forme, par exemple en tube, facilite la pénétration de l'élément chauffant dans la matière de remplissage, qui est un solide plus ou moins mou. L'extrémité peut être de forme pointue de manière à faciliter encore plus la pénétration.
• l'élément chauffant comprend une résistance électrique, le procédé comprenant en outre une étape de connexion de la résistance électrique à une source de courant. Un élément chauffant contenant une résistance électrique est en effet aisé à manipuler et à installer dans le système d'ancrage. Il ne nécessite qu'un branchement à une source de courant.
• l'élément chauffant comprend un thermocouple pour mesurer une température au voisinage de l'élément chauffant. Par « au voisinage », on veut dire « dans ou à proximité de ». La mesure peut se faire notamment à l'extrémité de l'élément chauffant qui pénètre dans la matière de remplissage. Cette mesure permet de suivre l'évolution en température dans la chambre, notamment au voisinage de l'élément chauffant.
• durant l'étape de chauffage, l'élément chauffant délivre une puissance thermique régulée en fonction de la température mesurée par le thermocouple. Ceci permet de réduire le temps de chauffe et d'éviter une surchauffe qui pourrait altérer les gaines protectrices éventuellement présentes sur une partie du câble de structure ou causer une inflammation de la matière de remplissage.
• durant l'étape de chauffage, on rend l'ouverture de l'enveloppe de la première chambre par laquelle est introduit l'élément chauffant étanche vis-à-vis d'un écoulement de la première matière de remplissage fluidifiée. Ceci permet d'éviter que la chambre se vide progressivement de sa matière de remplissage fluidifiée. En effet, pour une bonne conduction de la chaleur et une fluidification optimale de la matière de remplissage, il est préférable que toute la matière fluidifiée reste dans la chambre pendant l'étape de chauffage. L'étanchéité peut être obtenue grâce des moyens d'étanchéité (par exemple un joint) disposés sur l'élément chauffant.
• l'extraction de la première matière de remplissage fluidifiée se fait au moins en partie par aspiration à l'aide d'une canule. Ceci permet l'évacuation de la matière de remplissage fluidifiée, même quand l'ouverture par laquelle elle se fait est située au-dessus de la matière liquide. Ce cas peut par exemple se produire dans un système d'ancrage de la partie haute d'un hauban de pont.
• l'extraction de la première matière de remplissage fluidifiée se fait au moins en partie par un écoulement. Si l'ouverture servant à l'extraction de la matière de remplissage fluidifiée est située en partie basse de la chambre, ce mode d'évacuation est simple et efficace.
• l'écoulement de la première matière de remplissage fluidifiée se fait à travers l'ouverture ayant servie à l'introduction de l'élément chauffant au sein de la première matière de remplissage. On peut par exemple, après l'étape de chauffage, retirer l'élément chauffant et libérer le passage pour un écoulement de la matière de remplissage fluidifiée. Ainsi une ouverture supplémentaire n'est pas utile pour l'évacuation.
• l'enveloppe de la première chambre comprend un bloc d'ancrage sur lequel est ancré le câble de structure, un tube et un presse-étoupe, l'ouverture par laquelle l'élément chauffant est introduit au sein de la première matière de remplissage durant l'étape d'insertion se situant dans le bloc d'ancrage. Selon ce mode de réalisation, on utilise pour l'insertion de l'élément chauffant une ouverture, en général préexistante, dans le bloc d'ancrage. L'ouverture n'a donc pas à être créée spécialement.
• le système d'ancrage comprend une seconde chambre située de l'autre côté du bloc d'ancrage par rapport à la première chambre et délimitée par une seconde enveloppe comprenant le bloc d'ancrage et un capot, la seconde chambre contenant une seconde partie du câble de structure et une seconde matière de remplissage et dans lequel, préalablement à l'insertion de l'élément chauffant au sein de la première matière de remplissage, on fait pénétrer l'élément chauffant dans la seconde chambre par une ouverture du capot alignée avec l'ouverture de l'enveloppe de la première chambre par laquelle l'élément chauffant est inséré pour permettre une pénétration successive de l'élément chauffant dans la seconde chambre puis la première chambre sans déplacement du capot. Certains systèmes d'ancrage possèdent une seconde chambre, où se situent par exemple la ou les parties terminales du câble de structure qui dépassent du bloc d'ancrage. Cette seconde chambre est délimitée par le bloc d'ancrage et par un capot. Elle contient une seconde matière de remplissage. Elle a la même fonction que la première matière de remplissage et peut être constituée du même matériau. Dans ce mode de réalisation, l'élément chauffant pénètre d'abord dans la seconde chambre, puis dans la première, par deux ouvertures configurées pour ne pas avoir à déplacer le capot.
• le procédé comprend en outre une étape de chauffage de la seconde matière de remplissage par une ceinture chauffante placée sur une surface externe du capot. La seconde matière de remplissage peut être fluidifiée par un chauffage externe à l'aide d'une ceinture chauffante placée à l'extérieur de la chambre, contre le capot, puis enlevée.

According to particular embodiments, the invention may implement one or more of the following features:

• the heating element comprises a substantially cylindrical portion having an end through which, during the insertion step, it is penetrated into the first filling material. Such a shape, for example in tube, facilitates the penetration of the heating element in the filling material, which is a more or less soft solid. The end can be pointed in order to facilitate further penetration.
• the heating element comprises an electrical resistance, the method further comprising a step of connecting the electrical resistance to a power source. A heating element containing an electrical resistance is indeed easy to handle and install in the anchoring system. It only requires a connection to a power source.
• the heating element comprises a thermocouple for measuring a temperature in the vicinity of the heating element. By "neighborhood", we mean "in or near". The measurement can be done in particular at the end of the heating element which penetrates into the filling material. This measurement makes it possible to follow the evolution in temperature in the chamber, in particular in the vicinity of the heating element.
• during the heating step, the heating element delivers a regulated thermal power as a function of the temperature measured by the thermocouple. This reduces the heating time and avoids overheating which could alter the protective sheaths that may be present on a part of the structural cable or cause ignition of the filling material.
• during the heating step, the opening of the casing of the first chamber through which the sealed heating element is introduced is made vis-à-vis a flow of the first fluidized filling material. This makes it possible to prevent the chamber from progressively emptying its fluidized filling material. Indeed, for good heat conduction and optimal fluidification of the filling material, it is preferable that all the fluidized material remains in the chamber during the heating step. The seal can be achieved by means of sealing (for example a seal) disposed on the heating element.
• the extraction of the first fluidized filling material is at least partly by suction using a cannula. This allows evacuation of the fluidized filling material, even when the opening through which it is made is located above the liquid material. This case can for example occur in an anchoring system of the upper part of a bridge stay.
• the extraction of the first fluidized filling material is at least partly by a flow. If the opening for extracting the fluidized filling material is located in the lower part of the chamber, this mode of discharge is simple and effective.
• the flow of the first fluidized filling material is through the opening used for the introduction of the heating element into the first filling material. For example, after the heating step, the heating element may be removed and the passageway may be released for flow of the fluidized filling material. Thus an additional opening is not useful for evacuation.
• the envelope of the first chamber comprises an anchor block on which is anchored the structural cable, a tube and a gland, the opening through which the heating element is introduced into the first filling material during the insertion step lying in the anchor block. According to this embodiment, for the insertion of the heating element is used an opening, generally pre-existing, in the anchor block. The opening does not have to be specially created.
• the anchoring system comprises a second chamber located on the other side of the anchor block relative to the first chamber and delimited by a second envelope comprising the anchor block and a cover, the second chamber containing a second part of the anchor block; structure cable and a second filling material and in which, prior to the insertion of the heating element into the first filling material, the heating element is introduced into the second chamber through an opening of the hood aligned with opening the envelope of the first chamber through which the heating element is inserted to allow successive penetration of the heating element in the second chamber and the first chamber without moving the cover. Some anchoring systems have a second chamber, where are for example the terminal or the end portions of the structural cable protruding from the anchor block. This second chamber is defined by the anchor block and a hood. It contains a second filling material. It has the same function as the first filling material and can be made of the same material. In this embodiment, the heating element first enters the second chamber, then into the first, by two openings configured to not have to move the hood.
• the method further comprises a step of heating the second filler material with a heating belt placed on an outer surface of the hood. The second filler may be fluidized by external heating using a heating belt placed outside the chamber, against the hood, and removed.

• la figure 1a représente schématiquement une coupe longitudinale d'un système d'ancrage d'un câble de structure à un élément de construction;
• la figure 1b illustre une méthode de vidange de ce système d'ancrage conforme à l'invention ;
• la figure 2 est une coupe transversale du système d'ancrage représenté en figure 1b ;
• la figure 3 représente un élément chauffant mis en oeuvre par la méthode illustrée à la figure 1b.

Other features and advantages of the present invention will become apparent in the following description of nonlimiting exemplary embodiments, with reference to the appended drawings, in which:

• the figure 1a schematically represents a longitudinal section of a system for anchoring a structural cable to a construction element;
• the figure 1b illustrates a method of emptying this anchoring system according to the invention;
• the figure 2 is a cross-section of the anchoring system represented in figure 1b ;
• the figure 3 represents a heating element implemented by the method illustrated in FIG. figure 1b .

For the sake of clarity, the dimensions of the various elements shown in these figures are not necessarily in proportion to their actual dimensions. In the figures, identical references correspond to identical elements, but not necessarily implemented identically.

On the figure 1a , the considered structural cable is for example the lower part of a bridge stay oriented in a direction X. The cable is composed of a plurality of strands. Three of them have been represented: 2a, 2b, 2c. The structural cable (that is to say its strands 2a, 2b, 2c) is anchored by means of an anchoring system 1 in axial support on a construction element 7 (for example a span of the bridge). The anchoring system has for example a length of about 600 to 1000 mm in the X direction and a diameter of about 200 to 600 mm in a plane orthogonal to this direction.

Each strand is itself formed of a plurality of elementary wires. These son may be parallel or twisted and are for example made of galvanized steel or galfanized. The strands 2a, 2b, 2c are each surrounded by a protective sheath which is able to protect them during their lifetime against corrosion due to weather or other external aggression, including moisture and handling. This sheath is for example made of a plastic material, such as high density polyethylene (HDPE) or a polyamide.

The structural cable is anchored to a perforated block 4, or anchor block, for example by clamping the ends of the strands in split jaws (not shown). For this, each of the protective sheaths of the strands is interrupted at an end wafer so that the cable has a first denuded portion 2aa, 2bb, 2cc.

• à une première extrémité axiale, d'une face du bloc perforé 4,
• transversalement, d'un tube rigide 6 qui est par exemple de forme cylindrique à base circulaire,
• et à l'extrémité axiale opposée au bloc 4, d'un presse-étoupe 5 traversé de façon étanche par les brins gainés 2a, 2b, 2c et pressé de façon étanche contre la face intérieure du tube 6 sous l'effet d'une compression axiale.

In order to protect this first stripped portion 2aa, 2bb, 2cc against corrosion, it is located inside a first chamber 3 filled with wax and delimited by an envelope constituted by:

• at a first axial end, of a face of the perforated block 4,
• transversely, a rigid tube 6 which is for example cylindrical in shape with a circular base,
• and at the opposite axial end to the block 4, a gland 5 sealed through the sheathed strands 2a, 2b, 2c and sealingly pressed against the inner face of the tube 6 under the effect of a axial compression.

The strands emerge from the anchoring block 4 and form a second portion 2aaa, 2bbb, 2ccc of the structure cable, also stripped. For the same reasons of protection against corrosion, this second part of the structural cable is contained in a second chamber 3a filled with a filling material which, in the example under consideration, is a wax. The chamber 3a is delimited on the one hand by the anchoring block 4 and on the other by a cover 9 pierced with two openings 9a and 9b closed by plugs.

The anchoring block 4 comprises two openings 4a and 4b, for example circular holes, for filling the first chamber 3 with hot wax.

The chamber 3 is located in an area of the anchoring system 1 which is generally surrounded by the construction element. Because of this, it is not very accessible.

The figure 1b represents the same anchoring system, during the implementation of a method of emptying according to the invention.

According to a variant of the invention not shown, the filling material present in the chamber 3a can be drained by removing the cover 9 to access it directly. This can be removed manually, if necessary by blowing hot air. In this case, it ensures the sealing of the openings 4a and 4b, and possibly that openings corresponding to the passage of the strands 2a, 2b, 2c in the block 4.

In a first step, two heating elements 10a and 10b are inserted into the filling material which fills the first chamber 3. These were inserted via the openings 9a and 9b. The heaters 10a and 10b have a seal (not shown) so that, when in place, the openings 9a and 9b are sealed against flow of the fluidized filler into the first chamber 3.

The heating elements 10a and 10b comprise a cylindrical portion with an end 10e through which they are embedded in the solid filler.

To bring the heating elements 10a and 10b into the anchoring system, they are then passed through the openings 4a and 4b of the anchor block 4. These are aligned with the openings 9a and 9b of the hood block 9 .

Once the heating elements have been installed, a heating step of the filling material contained in the first chamber 3 begins. This material is brought to a temperature greater than its melting temperature, but less than about 300 ° C., in order not to cause its heating. ignition and even less than about 160 ° C to not damage the sheaths of the strands 2a, 2b, 2c.

To facilitate this control of the temperature in the first chamber, the heating elements 10a and 10b (see figure 3 ) may comprise a thermocouple 10d located to measure the temperature at the end 10e of the heating elements. The thermal power dissipated by the heating elements is then regulated as a function of the temperature measured by these thermocouples. Other thermocouples may be inserted into the first or second chamber to better control the fluidization of the filler, or to replace the thermocouples 10d.

When the filler is melted (preferably completely), the heating elements 10a and 10b are removed and the fluidized filler may flow into the passages created by the insertion of the heating elements. Alternatively or additionally, the fluidized filling material can be sucked by a cannula inserted either by the same path as the heating elements 10a and 10b, either by an ad hoc opening of the envelope of the first chamber 3.

In general, the filling material contained in the second chamber can be easily removed by removing the cover 9. This material can also be heated without removing the cover. The heating can be done using a heating belt 12 placed on the outer face of the cover 9. The heating elements 10a and 10b can also be configured to be able to heat the filling material contained in the second chamber 3a.

On the figure 2 the strands 2a, 2b, 2c which cross the anchoring block 4 are shown. The fastening elements (jaws) are not shown. We also see the openings 4a and 4b through which are inserted the heating elements 10a and 10b.

The figure 3 illustrates an embodiment of the heating element 10a. Element 10b is identical to element 10a. The heating element 10a has an envelope whose outer surface is cylindrical with a circular base. The section is a little less than 10 mm. The element 10a has two opposite ends 10e and 10f, one of which, 10e, is intended to penetrate into the solid filler of the chambers 3a and 3. It comprises an electrical resistance 10c arranged along the entire length of the envelope, and a thermocouple 10d placed so as to measure the temperature of the end 10e. Supply wires of the resistor 10c and the thermocouple 10d exit through the end 10f.

During the heating step, each resistor 10c is connected to a current source 11 comprising a PID regulator controlling the electrical intensity delivered to the resistor 10c (that is, controlling the thermal power dissipated by the Joule effect). temperature function measured by the thermocouple 10d. If there are several resistors, each is independently powered and controlled. The control reduces the heating time under maximum temperature stress.

Claims (12)

1. Method of draining a system for anchoring a structural cable (2a, 2b, 2c) to a construction element (7), the anchor system comprising a first chamber delimited by an envelope (4, 5, 6), the first chamber (3) containing a first part (2aa, 2bb, 2cc) of the structural cable and a first filling material, the method comprising the following steps:

   - inserting at least one heating element (10a, 10b) into the first filling material via an opening (4a, 4b) in the envelope of the first chamber;

   - heating the first filling material using the heating element to fluidize at least some of the first filling material; and

   - extracting the fluidized first filling material via an opening (4a, 4b) in the envelope of the first chamber.
2. Method according to Claim 1, wherein the heating element (10a, 10b) comprises a substantially cylindrical part having an end (10e by which it is caused to penetrate into the first filling material during insertion.
3. Method according to Claim 1 or 2, wherein the heating element (10a, 10b) comprises a thermocouple (10d) for measuring a temperature in the vicinity of the heating element.
4. Method according to Claim 3, wherein, during heating, the heating element (10a, 10b) delivers a thermal power regulated as a function of the temperature measured by the thermocouple (10d).
5. Method according to any one of Claims 1 to 4, wherein the heating element (10a, 10b) comprises an electrical resistor, the method further comprising connecting the electrical resistor to a current source (11).
6. Method according to any one of Claims 1 to 5, wherein, during heating, the opening of the envelope (4a, 4b) of the first chamber through which the heating element (10a, 10b) is introduced is sealed against flow of the fluidized first filling material.
7. Method according to any one of Claims 1 to 6, wherein the fluidized first filling material is extracted at least in part by aspiration using a cannula.
8. Method according to any one of Claims 1 to 6, wherein the fluidized first filling material is extracted at least in part by flow.
9. Method according to Claim 8, wherein the fluidized first filling material flows through the opening (4a, 4b) that was used to introduce the heating element (10a, 10b) into the first filling material.
10. Method according to any one of Claims 1 to 9, wherein the envelope (4, 5, 6) of the first chamber (3) comprises an anchor block (4) to which the structural cable (2a, 2b, 2c) is anchored, a tube (6) and a gland (5), the opening (4a, 4b) through which the heating element (10a, 10b) is introduced into the first filling material during the insertion being situated in the anchor block (4).
11. Method according to Claim 10, wherein the anchor system (1) comprises a second chamber (3a) situated on the other side of the anchor block (4) relative to the first chamber (3) and delimited by a second envelope comprising the anchor block (4) and a cap (8), the second chamber containing a second part (2aaa, 2bbb, 2ccc) of the structural cable (2a, 2b) and a second filling material and wherein, prior to the insertion of the heating element into the first filling material, the heating element is caused to penetrate into the second chamber (3a) via an opening (9a, 9b) in the cap (8) aligned with the opening (4a, 4b) in the envelope of the first chamber through which the heating element is inserted to enable successive penetration of the heating element (10a, 10b) into the second chamber (3a) and then the first chamber (3) without moving the cap.
12. Method according to Claim 11, further comprising a step of heating the second filling material by a heating belt (12) placed on an external surface of the cap (8).

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