ALTERNATIVE ANCHOR

Abstract

Method and device for installing a replacement anchorage, replacing an existing anchorage connecting a cable to a construction structure, the cable comprising a plurality of reinforcing bars, the method comprising: preparing anchor block segments; placing the anchor block segments at a distance from the existing anchorage and in such a way that each reinforcing bar is held between two adjacent anchor block segments; joining the anchor block segments together, thus forming a replacement anchor block; joining each reinforcing bar to the two adjacent anchor block segments; and transferring the load carried by the cable from the existing anchorage to the replacement anchor block. Abstract figure: Figure 5

Description

Title of the invention: SUBSTITUTION ANCHOR Technical field

[0001] The present disclosure relates to the field of civil engineering works and their maintenance or repair. In particular, the present disclosure relates to a method for manufacturing and installing a temporary or permanent replacement anchor, in particular for connecting a stay cable to the deck, in place of an existing anchor. Prior art

[0002] Civil engineering structures may include cables (stay cables, suspension cables, hangers, etc.) which are tensioned between two anchors, thus connecting two structural elements of the bridge, for example a pylon and the deck. The cables may be damaged by corrosion at their anchors. If this occurs, it is common to replace the entire cable, or at least the reinforcements of the cable which are affected by corrosion. This procedure requires the use of significant resources, deployed on a large-scale construction site, thus leading to significant disruptions to the operation of the bridge: in addition to the cost of repairs, traffic may be reduced or even interrupted, generating traffic difficulties and / or a loss of earnings for the operator. Summary

[0003] The present disclosure improves the situation.

[0004] A method of installing a substitute anchor, replacing an existing anchor connecting a cable to a construction structure, the cable comprising a plurality of reinforcements, the method comprising: preparing anchor block segments; placing the anchor block segments at a distance from the existing anchor and in such a way that each reinforcement is held between two adjacent anchor block segments; joining the anchor block segments together, thereby forming a substitute anchor block; joining each reinforcement to the two adjacent anchor block segments; and transferring the load carried by the cable from the existing anchor to the substitute anchor block.

[0005] Unlike conventional techniques, this process makes it possible to avoid replacing the entire cable. In fact, the initial cable is retained over substantially its entire length, which represents an economic and logistical gain: the footprint of the construction site is limited, thus reducing disruptions to the operation of the structure. The consequences are also environmental, because less raw material and less energy are used with the method of the present disclosure.

[0006] The building structure to which the cable is connected may be the deck of a bridge, a pylon of a bridge, or other structural elements.

[0007] The cable may be composed, for example, of a bundle of 19 strands of 7 wires, each strand having a diameter of 15.7 mm, sheathed in HDPE and with a strength class Frg of 1860 MPa. It is understood that the disclosed method can be used for any type of cable, regardless of the number of strands or their mechanical strength. Depending on the nature of the cable envisaged, the term reinforcement used in this document will designate a strand or a wire.

[0008] The installation of the segments at a distance from the existing anchorage can be carried out for example less than 2 meters, or less than 1 meter from the existing anchorage and / or at a distance less than 2% or less than 1% of the total length of the cable.

[0009] According to another aspect, the preparation of anchoring segments comprises the manufacture of adjacent segments in pairs, two adjacent segments comprising respective concavities each describing a respective half of the same truncated cone. As explained in detail below, the pairing of the segments in pairs makes it possible to guarantee the dimensional quality of the cone (or conical pot) in which each reinforcement will be anchored.

[0010] According to another aspect, the securing of each reinforcement to the adjacent segments is achieved by sliding anchoring jaws / keys between the reinforcement and the respective halves of the truncated cone, at least one of the keys being positioned in overlapping position on the two halves of the truncated cone. It is indeed possible to use conventional keys in cooperation with the half-cones of each segment. Optionally, exactly two keys are overlapped on the interfaces between the two half-cones.

[0011] According to another aspect, the anchoring block segments are secured to each other by placing a yoke and / or a collar on the periphery of the segments. The yoke and / or the collar is thus arranged around the segments and tightened, for example by threaded rods, to immobilize the segments relative to each other.

[0012] According to another aspect, the transfer of the load comprises the installation of a load-recovering header encircling the cable in support of a rear surface of the segments or of a load-recovering flange itself in support of the segments, opposite a front surface of the segments which is opposite the existing anchorage. The header can be connected, by relay bars arranged parallel to the cable, to a header made integral with the anchorage point of the construction structure. A parallel bridging is thus produced of the portion of cable located between the existing anchorage and the replacement anchorage.

[0013] According to another aspect, the yoke is formed of two half-yokes separated from each other at a first joint plane and the flange is formed of two half-rings separated from each other at a second joint plane, angularly offset from the first joint plane by an angle of between 60° and 120°. This angular offset makes it possible to limit stress concentrations and optimizes the mechanical strength of the substitute anchor. It is understood that the yoke and / or the flange may be made up of more than two parts and thus each form more than one joint plane. In this case, none of the joint planes of the yoke coincide with one of the joint planes of the flange.

[0014] According to another aspect, the segments are placed in place by a movement of the segments in a translation substantially transverse to the reinforcements of the cable. It is in particular possible to place the segments with limited access to the cable, on only one side of the cable.

[0015] According to another aspect, when placing the segments, two adjacent segments are positioned in such a way as to hold together a beam line of reinforcements. Alternatively, several segments may be positioned along a beam line.

[0016] According to another aspect, before the anchor block segments are put in place, the following steps are taken: to strip the cable and / or the reinforcements; and / or to insert shim boards between the reinforcements, in particular between two lines of reinforcement bundles, in two zones axially distant from each other. The insertion of wooden wedges facilitates the insertion of the segments. The wooden wedges can be removed after the segments have been inserted, or later, for example after the reinforcements have been secured to the replacement block.

[0017] According to another aspect, after the load transfer, the following operations are carried out: finishing, treatment or dressing of the area affected by the installation of the replacement anchor; and / or removal of the existing anchor.

[0018] According to another aspect, after the load transfer, the existing anchor is treated, replaced or repaired, thus obtaining a restored anchor, then the following steps are taken: to secure the reinforcements to the restored anchor; to transfer the load from the replacement anchor to the restored anchor; to detach the reinforcements from the segments of the replacement anchor; to detach the anchor block segments from each other; and to remove the segments. Thus, the method of installing a replacement anchor is reversible and can allow a temporary substitution of the existing anchor.

[0019] The present disclosure also relates to a device for implementing the method according to one of the embodiments set out above, the device comprising a plurality of substitute anchor block segments; means for securing the segments together; means for securing the cable reinforcements to the substitute anchor segments; and load transfer means. The device may comprise the various elements (shell, half-cones, etc.) discussed above in connection with the method used.

[0020] The present disclosure also relates to a method for preparing anchor block segments for carrying out the method set out above, the preparation method comprising: providing a block; cutting segments forming block slices; positioning two segments plane on plane and drilling cones centered on the interface between the two segments; positioning all the segments of the block and machining a preferably cylindrical contour. Brief description of the drawings

[0021] Other characteristics, details and advantages will appear on reading the detailed description below, and on analyzing the attached drawings, in which:

[0022] [Fig-1] shows an anchoring area before the anchor block is substituted.

[0023] [Fig.2] shows the anchoring area of ​​[Fig.l] after removal of the sheath or envelope and installation of wooden wedges.

[0024] [Fig.3] shows the anchoring area of ​​[Fig.2] after laying segments of a block of substitution.

[0025] [Fig.4A] shows the installation of a yoke and a flange associated with the substitution block.

[0026] [Fig.4B] shows a variant for the installation of a yoke and a flange associated with the substitution block.

[0027] [Fig.5] shows the anchoring area of ​​[Fig.3] after load transfer.

[0028] [Fig.6] shows the substitution block during its manufacture.

[0029] [Fig.7] shows the segments of the substitute block manufactured.

[0030] [Fig.8] shows a diagram. Description of the embodiments

[0031] Figures 1 to 4 are schematic illustrations and Figures 5 to 9 show certain details. [Fig.l] shows an anchoring zone 1 between a cable 2 and an anchoring point 4 linked to a structural element of a work of art, which may be a pylon or the deck of a bridge for example.

[0032] In the present disclosure, the cylindrical reference (axial, radial or transverse, tangential or circumferential) will be used in reference to the cable or in reference to an armature (strand, wire), the axial direction being designated by the reference X in [Fig.l]. Figures 1 to 4 and 6 show a view A in the plane (X, Z) and a view B representing a section in a plane (Y, Z) perpendicular to X.

[0033] The cable 2 is composed of a bundle of several reinforcements (or strands) 6 arranged in parallel, for example 19 in number. Each strand 6 can be composed of 7 wires, consisting of six peripheral wires 8 wound in a helix around a central wire 10. A sheath 12 made of high-density polyethylene can enclose the wires 8, 10.

[0034] The set of reinforcements 6 can also be protected by an envelope sheath 14.

[0035] The reinforcements 6 are individually secured to an anchoring block 16, which will be referred to as “existing” in this document.

[0036] The anchor block 16 may be the site of mechanical or physicochemical damage such as corrosion. This damage may weaken the anchor and it may be necessary to repair, treat, or replace the anchor 16. One option is to unanchor the cable and replace it, after having treated or replaced the anchor 16. The present disclosure presents another solution in the following figures.

[0037] [Fig.2] shows the anchoring of [Fig.l] following a step of the installation process consisting of removing the sheath 14. Also, wedging boards (made of wood or equivalent material) 18 can be inserted between bundles 20 of reinforcements 6 in two zones a and b distant from each other. The reinforcements 6 can be stripped in a zone c between a zone a and a zone b. The stripping can be done over a length of between 15 and 40 cm, more particularly between 20 and 30 cm. The wedging boards can have a thickness of between 20 and 50 mm, and in particular a thickness of approximately 30 mm.

[0038] [Fig.3] shows the cable and anchor 16 following the insertion of segments 22, 24, 26, 28, 30, 32 between two adjacent beam lines 20. The segments 22-32 can be inserted between the lines transversely (radially) to the reinforcements 6, i.e. in the Y direction. The wooden wedges 18 can help to separate the beam lines 20 from each other to facilitate the insertion of the segments 22-32. Each wedge board can be inserted and then removed successively between 2 adjacent reinforcement lines for the successive insertion of each segment.

[0039] Each reinforcement 6 is anchored with a conical jaw housed and clamped in a conical pot constituted by two adjacent segments. For example, the reinforcement denoted 6A is anchored in a conical pot constituted with the segments 24 and 26. It is thus separated from the other reinforcements, and surrounded by the material of the segments 24 and 26, locally in a plane (Y,Z) crossing the segments 24, 26. To this end, each segment 22-32 comprises half-cone and / or half-cylinder concavities (see also [Fig.6]). The adjacent segments are paired two by two during their manufacture to form conical pots and cylinders of good dimensional quality. These conical pots and / or cylinders allow the anchoring of the reinforcements 6 to the segments by means of anchoring jaws constituted by truncated cone keys (see [Fig.4A]). Each anchor jaw is typically made up of 3 truncated cone keys, each covering a sector close to 120° angle.

[0040] The number and design of the segments depends on the number of reinforcements 6. In the example illustrated, the 19 reinforcements are distributed in a regular hexagonal pattern in lines of three, four or five reinforcements 6. It is understood that other segment geometries are possible, more or less complex to manufacture and / or install.

[0041] The segments 22-32 are composed of two end segments 22, 32 which comprise half-cones and / or half-cylinders on only one of their faces. The intermediate segments 24, 26, 28, 30 comprise half-cones and / or half-cylinders on two of their opposite faces. On these intermediate segments, the half-cones and / or half-cylinders may be arranged in a staggered pattern between their two opposite faces, in accordance with a regular hexagonal pattern of the reinforcements of the bundle.

[0042] The end segments 22, 32 may be thicker (for example 40 mm) than the intermediate segments 24, 26, 28, 30 (for example 25 mm).

[0043] The segments can be held together by any means. The segments form, with the means holding them together, an anchoring block 34 for the reinforcements 6, which will be referred to in the present disclosure as a “substitution” block. The set of segments is denoted 33.

[0044] The segments may be substantially parallelepipedal. However, in the example illustrated, the periphery (or outer surface of the assembly) of the segments is cylindrical in order to allow more freedom in the choice of the means of securing (for example yoke or collar). In an alternative solution, the outer surface is machined into a truncated cone (as shown in [Fig.4B]) which offers the possibility of better radial clamping by circular wedge effect.

[0045] [Fig.4A] shows an example of securing the segments together and transferring the load from the existing block 16 to the replacement block 34. A yoke 35 formed of two half-yokes 36, and held by screw elements 37 (threaded rod, nut, bushing, washer, etc.), surrounds the assembly 33 of the segments. The interface between the two half-yokes 36 is materialized by the joint plane PL. The two half-yokes 36 can be separated from each other by at least one millimeter at this location.

[0046] Anchoring jaws consisting of truncated cone keys (truncated cones) 38 are assembled and slid along the axial direction X until they are wedged in the conical pots of the segments and the reinforcements 6. The jaws / keys 38, once wedged, secure (or anchor) the reinforcements 6 in the block 34. The jaws / keys 38 may be pre-positioned along the reinforcements 6 before the segments are secured together, since this securing may reduce the space available between the reinforcements 6 and make the insertion of the key jaws more difficult. The keys may be made of hardened and tempered steel suitable for anchoring steel reinforcements.

[0047] As visible in [Fig.4A], part B, at least one key (per frame) overlaps the joint plane between two adjacent segments.

[0048] The shimming boards can preferably be removed after the segments have been inserted, or after they have been secured if their thickness allows it.

[0049] A force-recovery flange 39 may be arranged in contact with the assembly 33 of segments and / or the yoke 35, on the face remote from the existing anchor 16. The force-recovery flange 39 may be formed of two half-rings 40 whose interface is materialized by the joint plane P2. The two half-rings 40 may be separated from each other by at least one millimeter at this location. The joint planes P1 and P2 may form between them an angle of between 60 and 120°, an angle which may preferably be approximately 90°. The half-rings 40 of the flange 39 may be provided with a circular counterbore and / or pins or cleats (not shown) to promote their good centering with the reconstituted block.

[0050] [Fig.4B] shows substantially the same aspects as [Fig.4A] except that the perimeter of the assembly 33 is truncated (and the shell 35 or the half-shells 36 have a complementary shape).

[0051] [Fig. 5] shows a load-recovery header 45 connected to a header 42 secured to the anchoring point 4 by means of load-recovery bars 44 called relay bars. The relay bars 44 can be threaded and supported on the headers 42 and 45 by means of adjustable nuts (not shown).

[0052] Thus, a parallel bridging of the existing anchor block 16 is put in place. The existing anchor block 16 can thus be relieved of the tension of the reinforcements 6.

[0053] The substitution of the existing anchor block 16 by the substitution block 34 may be permanent or temporary. In the case of temporary substitution, the reinforcements 6 may be detached from the existing block 16 in order to treat and repair the reinforcements on the one hand, or to treat, repair or replace the block on the other hand. Following the treatment, repair or replacement of the block, the reverse steps may be carried out, to remove the substitution block 34.

[0054] [Fig.6] shows the manufacture of the set 33 of segments. A parallelepiped blank has been sliced ​​into parallelepiped segments 122, 124, 126, 128, 130, 132. The flat faces of the parallelepiped segments can be dressed after cutting if this is necessary to ensure flatness and good quality contact at the interfaces between segments. The blank can be made of high-strength mechanical steel. For an anchorage of 19 T15 reinforcements (150 mm2), the blank can be a parallelepiped with dimensions 75 mm x 190 mm x 190 mm. Each slice can have a height of 25 to 45 mm. After cutting and dressing, the segments 122, 124, 126, 128, 130, 132 are paired, positioned against each other and held to carry out the drilling of the cones and cylinders. The cylinder may have a slightly larger DI diameter than that of the reinforcements, such as 18 mm. The cone can have a maximum diameter D2 of 26 mm. The length of the cone L can be between 40 and 50 mm, and for example be 44 mm.

[0055] [Fig.7] shows the segments ready for use. The periphery of the segments is contoured, for example by turning or milling, while the segments are held securely in position. For example, the periphery or outer surface may be cylindrical with a diameter between 150 mm and 200 mm, in particular about 175 mm.

[0056] Here we will note the concavities 23, 25, 27, 29 and 31 in the shape of a half-cone and half-cylinder.

[0057] The collar or yoke shown in Figures 4A and 4B is machined or turned with an internal shape complementary to the external surface of the assembly 33 of segments 22-32. In the case of a circular cylindrical surface, the yoke 35 formed by two half-yokes 36 has a substantially annular shape matching the external shape of the assembled block (of segments). The internal diameter of the yoke will be adjusted to be slightly greater (0.5 to 1 mm for example) than that of the reconstituted anchoring block. Furthermore, the 2 joints between half-yokes 36 will be machined to maintain an opening (minimum value 1 mm for example) at the interface so that this joint is never closed after tensioning the clamping screws 37. These arrangements make it possible to ensure suitable tightening of the yoke on the block, producing radial pressure on its periphery. In the case of an assembly 33 whose external surface is frustoconical (as in [Fig.4B]), the yoke 35 has an annular shape whose inner surface is truncated, matching the outer shape of the assembly 33 (of segments), so that the radial clamping exerted on the block can be improved by a circular wedge effect.

[0058] [Fig.8] shows the steps of the method of installing the replacement block. Steps 100 to 103 concern the preparation of the segments.

[0059] As discussed in connection with Figures 6 and 7, the segments are obtained by providing a raw block 100, cutting and dressing 101 of segments / block slices, drilling 102 of cones / cylinders centered on the interface between two respective segments, and contouring 103 of the cylindrical periphery.

[0060] In relation to [Fig.2], the method continues by removing 104 the cable sheaths and the reinforcements. The wedging boards are inserted 105 between two beam lines, laterally, in particular by a transverse translation movement.

[0061] The segments are then inserted 106, in particular by a transverse translation movement.

[0062] The anchoring jaws (keys) can be arranged 107 around each frame before securing 108 the segments together, with tightening of the yoke or collar 35 (by means of the screws 37) and possible installation of the flange 39.

[0063] The anchoring jaws are then slid (see arrows in [Fig.4A], part A) until they are wedged between the reinforcement and the conical pots of the segments, thus anchoring the reinforcements in the substitution block.

[0064] The load is finally transferred 110 from the existing block to the replacement block.

[0065] Finishing operations 111 may be performed to protect the new anchor. The existing anchor may be removed 112.

[0066] If the substitution is temporary, the preceding steps can be performed in reverse, to remove the substitution block and restore the load to the original anchor level. List of reference signs

[0067] 1: Anchoring zone 2: cable 4: anchor point 6: reinforcements (strands) 8, 10: son 12, 14: sheath 16: existing anchor block 18: wooden wedges 20: reinforcement beam lines 22, 24, 26, 28, 30, 32: substitute anchor block segments 23, 25, 27, 29, 31: half-cone and half-cylinder concavities

[0068] 33: set of anchor block segments 34: substitution block 35: straitjacket 36: half-straitjacket 37: screw element 38: key 39: force absorption flange 40: half-ring bridle 42: headstock at anchor point 44: load transfer bar 45: header supporting the substitution anchor 100-111: steps of the process 1000 122, 124, 126, 128, 130, 132: segments after cutting and drilling, and before contouring

Claims

Claims

1. A method (1000) of installing a substitute anchor, replacing an existing anchor (16) connecting a cable (2) to a construction work structure (4), the cable (2) comprising a plurality of reinforcements (6), the method comprising: has. preparing (100, 101, 102, 103) anchor block segments (22, 24, 26, 28, 30, 32); b. placing (106) the anchor block segments (22, 24, 26, 28, 30, 32) at a distance from the existing anchor (16) and in such a manner that each reinforcement (6) is held between two adjacent anchor block segments (22, 24, 26, 28, 30, 32); c. securing (108) the anchor block segments (22, 24, 26, 28, 30, 32) together, thereby forming a substitute anchor block (34); d. the securing (109) of each reinforcement (6) to the two adjacent anchor block segments (22, 24, 26, 28, 30, 32); and e. the transfer (110) of the load supported by the cable (2), from the existing anchor (16) to the replacement anchor block (34).

2. Method according to claim 1, wherein the preparation (100, 101, 102, 103) of anchoring segments (22, 24, 26, 28, 30, 32) comprises the manufacture of segments (22, 24, 26, 28, 30, 32) adjacent in pairs, two adjacent segments comprising a respective concavity (23, 25, 27, 29, 31) each describing a respective half of the same truncated cone.

3. Method according to the preceding claim, in which the securing (109) of each frame (6) to the adjacent segments (22, 24, 26, 28, 30, 32) is carried out by sliding anchoring jaws / keys (38) between the frame (6) and the respective halves of the truncated cone (31), at least one of the keys (38) being positioned overlapping on the two halves of the truncated cone (31).

4. Method according to one of the preceding claims, in which the securing (108) of the segments (22, 24, 26, 28, 30, 32) of anchoring block to each other is carried out by the installation of a yoke (35) and / or a collar on the periphery of the segments (22, 24, 26, 28, 30, 32).

5. Method according to one of the preceding claims, in which the transfer of the load (110) comprises the installation of a load-recovery header (45) which encircles the cable (2) in support of a rear surface of the segments (22, 24, 26, 28, 30, 32) or of a load-recovery flange (39) itself in support of the segments (22, 24, 26, 28, 30, 32), opposite a front surface of the segments which is opposite the existing anchoring (16).

6. Method according to the combination of claims 4 and 5, in which the yoke (35) is formed of two half-yokes (36) separated from each other by a first joint plane (PI) and the flange (39) is formed of two half-rings (40) separated from each other by a second joint plane (P2), angularly offset from the first joint plane (PI) by an angle of between 60° and 120°.

7. Method according to one of the preceding claims, in which the positioning of the segments (22, 24, 26, 28, 30, 32) is carried out by a movement of the segments (22, 24, 26, 28, 30, 32) in a translation substantially transverse to the reinforcements (6) of the cable (2).

8. Method according to one of the preceding claims, wherein when placing the segments (22, 24, 26, 28, 30, 32), two adjacent segments (22, 24, 26, 28, 30, 32) are positioned in such a way as to hold together a beam line (20) of reinforcements (6).

9. Method according to one of the preceding claims, in which before the installation (106) of the anchor block segments, the following is carried out: - stripping (104) of the cable (2) and / or of the reinforcements (6); and / or - insertion (105) of wedging boards (18) between the reinforcements (6), in particular between two lines of reinforcement bundles (20), in two zones (A, B) axially distant from one another.

10. Method according to one of the preceding claims, in which after the load transfer (110), the following are carried out: - operations (111) of finishing, treating or dressing the area affected by the installation of the replacement anchor (34); and / or - removal (112) of the existing anchor (16).

11. Method according to one of the preceding claims, wherein after the load transfer, the existing anchor (16) is treated, replaced or repaired, thus obtaining a restored anchor, then the following steps are taken: a. to secure the reinforcements (6) to the restored anchor; b. to transfer the load from the replacement anchor (34) to the restored anchor; c. to detach the reinforcements (6) from the segments (22, 24, 26, 28, 30, 32) of the replacement anchor (34); d. to detach the segments (22, 24, 26, 28, 30, 32) of anchor block from each other; and e. to remove the segments (22, 24, 26, 28, 30, 32).

12. Device for implementing the method according to any one of claims 1 to 11, the device comprising a plurality of segments (22, 24, 26, 28, 30, 32) of substitute anchor block; means (35, 36, 37) for securing the segments together; means (38) for securing the reinforcements (6) of cable (2) to the segments (22, 24, 26, 28, 30, 32) of substitute anchor; and load transfer means (39, 40, 42, 44, 45).

13. A method of preparing anchor block segments for carrying out the method according to one of claims 1 to 11, the preparation method comprising: - providing a block (100); - cutting (101) segments forming block slices (122, 124, 126, 128, 130, 132); - positioning two segments plane on plane and drilling (102) cones centered on the interface between the two segments; - positioning all the segments of the block and machining (103) a preferably cylindrical contour.