JP5555820B1 - Sheath conduit structure - Google Patents

Abstract

PC steel material that is caused by bleeding water in the sheath pipe line in which the PC steel material is inserted and filled with grout to escape or isolate bleeding water generated in the pipe line when the grout is hardened. Reduces corrosion.
The sheath conduit 1 includes a connection portion 12 in which ends of the sheath 10 are connected and fixed via a joint member 11. At the connection portion 12, the protrusion 15 and the protrusion 25 are screwed together while the outer peripheral surface 16 of the protrusion 15 of the sheath 10 and the inner peripheral surface 26 of the protrusion 25 of the joint member 11 are in partial contact. As a result, the connecting tube portion 21 of the joint member 11 is fitted and fixed to the end portion of the sheath 10, and the grout 4 is cured between the end portion of the sheath 10 and the connecting tube portion 21 of the joint member 11. A drainage channel 30 is formed for guiding bleeding water generated in the pipeline to the outside of the pipeline.

Description

  The present invention relates to a structure of a sheath pipe that is embedded in a concrete structure such as a PC girder bridge, a PC steel material for introducing prestress into the concrete structure is inserted, and a grout is filled therein. .

  In general, when constructing prestressed concrete structures such as PC girders by post-tension method, sheath pipe is embedded in the concrete structure, and the PC steel material inserted through this pipe is tensioned, and the reaction force The compressive force (prestress) is introduced into the concrete structure. And it fills with the grout which is a mixture of Portland cement, water, an admixture, etc. in the pipe line which let PC steel material penetrate, and is trying to protect PC steel material from corrosion.

  When filling the grout, it is necessary to fill the pipe line tightly without a gap. For example, if a grout unfilled part occurs in the pipe and air remains, condensation occurs in this part, which causes the corrosion of the PC steel material, resulting in a problem that the strength of the concrete structure is reduced. Become.

  Therefore, the end portions of the sheath are connected and fixed via a joint member with an exhaust tube, and the air in the pipeline is discharged outside the pipeline through the exhaust hose connected to the exhaust tube of the joint member. It has been proposed (see, for example, Patent Document 1). Further, there has also been proposed one in which the ends of the sheath are connected and fixed via a joint member with a sensor, and the grout filling state (presence of residual air) in the pipe line is confirmed by the sensor of the joint member. (For example, refer to Patent Document 2).

JP 2003-321900 A JP-A-2005-188101

  As described above, various measures have been taken against the air remaining in the pipe line when the grout is filled, but in addition to this, as a factor causing corrosion of the PC steel material, There is bleeding water generated in the road. That is, the bleeding water remaining in the pipe line is in direct contact with the PC steel material, or the condensation generated in the voids after evaporation of the bleeding water is in contact with the PC steel material. This causes a problem that the strength of the object is reduced. However, the present situation is that no countermeasure is taken against bleeding water generated in the pipe line when the grout is cured.

  In view of the above, the present invention has a sheath pipe structure in which bleeding water generated in the pipe line during the hardening of the grout is escaped or isolated from the pipe line to suppress corrosion of the PC steel material caused by the bleeding water. For the purpose of provision.

  The sheath pipe structure of the present invention is a sheath pipe that is embedded in a concrete structure 2, is inserted with a PC steel material 3 for introducing prestress into the concrete structure 2, and is filled with a grout 4. In the path 1, a connection portion 12 is provided in which the ends of the sheath 10 are connected and fixed via a joint member 11, and the sheath 10 has convex ridges 15 bulging outward in the axial direction at an equal pitch in the axial direction. A spiral corrugated pipe formed in a spiral shape is provided, and the joint member 11 is provided with a connecting cylinder portion 21 at both ends thereof, and a protrusion 25 bulging radially outward is axially provided in the connecting cylinder portion 21. And the cross-sectional shape in the axial direction on the outer peripheral surface 16 of the ridge 15 and the cross-sectional shape in the axial direction on the inner peripheral surface 26 of the ridge 25 are different from each other, and the connection In the region 12, the ridge 5 and the inner peripheral surface 26 of the protrusion 25 are in partial contact with each other, and the protrusion 15 and the protrusion 25 are screwed together, so that the end of the sheath 10 is The connecting tube portion 21 of the joint member 11 is fitted and fixed, and bleeding water generated in the pipe line when the grout 4 is cured is piped between the end portion of the sheath 10 and the connecting tube portion 21 of the joint member 11. A drainage channel 30 is formed to guide the outside of the road.

  Further, the sheath pipe structure of the invention different from the present invention is embedded in the concrete structure 2, inserted with a PC steel material 3 for introducing prestress into the concrete structure 2, and grouted inside. 4 is provided with a connecting portion 12 in which the ends of the sheath 10 are connected and fixed via a joint member 11, and the sheath 10 is a ridge 15 bulging in the radially outward direction. Is a spiral corrugated tube formed in a spiral shape at an equal pitch in the axial direction, and the joint member 11 is provided with connecting tube portions 21 at both ends thereof, and the connecting tube portion 21 bulges radially outward. The projected ridges 25 are formed in a spiral shape at an equal pitch in the axial direction, and the axial sectional shape of the outer peripheral surface 16 of the ridge 15 and the axial sectional shape of the inner peripheral surface 26 of the ridge 25 are irregular. And said connecting part 12 In this case, the outer surface 16 of the protrusion 15 and the inner surface 26 of the protrusion 25 are in partial contact with each other, and the protrusion 15 and the protrusion 25 are screwed together, so that the sheath The connecting tube portion 21 of the joint member 11 is fitted and fixed to the end portion of the joint member 10, and the inside of the pipe line is set between the end portion of the sheath 10 and the connecting tube portion 21 of the joint member 11 when the grout 4 is cured. An isolation space 31 for isolating bleeding water generated in the above is formed.

  Further, a corner 16 c along the spiral direction is formed on the outer peripheral surface 16 of the ridge 15, and the corner 16 c of the ridge 15 is an inner periphery of the ridge 25 in the connection portion 12. The protrusion 15 and the protrusion 25 are screwed together while making line contact with the surface 26.

  Further, the sheath pipe line 1 is embedded in the concrete structure 2 in a state of meandering in the vertical direction, and the connecting portion 12 is provided at least near the top 1a. Furthermore, as confirmation means for confirming the state of filling of the grout 4 in the intermediate portion 20 of the joint member 11, exhaust pipes 40 and 41 for discharging the air in the pipe line to the outside of the pipe line, the residual in the pipe line Either a sensor 50 for detecting the presence or absence of air, an insertion cylinder 60 for inserting a camera for photographing a state in the pipe line, or a functional part made of a combination thereof is provided.

  According to the sheath conduit structure of the present invention, since the drainage channel is formed at the connection portion formed by connecting and fixing the end portions of the sheath via the joint member, bleeding water generated in the conduit when the grout is hardened is formed. It is possible to escape to the outside of the pipe through the drainage channel, to suppress the corrosion of the PC steel material due to bleeding water, and to maintain the strength of the concrete structure well over a long period of time.

  Further, according to the sheath conduit structure of another invention of the present invention, the isolation space is formed at the connection portion formed by connecting and fixing the end portions of the sheath via the joint member. The bleeding water generated inside is pushed out of the pipe line by the pressure of the grout before hardening, and is located in the isolated space (flows in), so that the bleeding water is prevented from coming into direct contact with the PC steel material, As a result, the corrosion of the PC steel caused by bleeding water can be suppressed, and the strength of the concrete structure can be maintained well over a long period of time.

  In addition, when forming the drainage channel or the isolation space, only a clearance to be a drainage channel or an isolation space is ensured between the end portion of the sheath and the connecting tube portion of the joint member that is externally fitted and fixed thereto. Further, the structure can be simplified without requiring a special mechanism or a dedicated member.

  Furthermore, while the outer peripheral surface of the ridge at the end portion of the sheath and the inner peripheral surface of the ridge at the connecting tube portion of the joint member are in partial contact, the convex ridge and the ridge are screwed together, so that the sheath The clearance which becomes a drainage channel or isolation space is ensured between the edge part of this and the connection cylinder part of the coupling member externally fixed to this. For this reason, a drainage channel and an isolation space can be formed while externally fixing and fixing the connecting tube portion of the joint member to the end of the sheath in a stable manner (so as not to hinder the external fitting fixation) Moreover, since the frictional resistance at the time of screwing between the ridges and the ridges becomes small, the workability at the time of external fitting and fixing is improved, and the coupling and fixing of the end portions of the sheath via the joint member is easily performed. be able to.

  In addition, when screwing between the ridges and the ridges, the corners of the ridges are brought into line contact with the inner peripheral surface of the ridges, so that a drainage channel and an isolation space can be reliably formed, and frictional resistance The workability at the time of fixing the outer fitting can be improved by further reducing the size of the lens.

  Furthermore, by providing a connection part that forms a drainage channel or an isolation space at least near the top of the sheath pipeline meandering in the vertical direction, bleeding water that tends to collect near the top of the sheath pipeline can be efficiently captured, and the outside of the pipeline. Can be escaped or placed in an isolated space.

  Furthermore, by providing various functional members in the middle part of the joint member and taking measures against the air remaining in the pipe line, corrosion of the PC steel material is surely prevented and reliability is improved. Can be planned.

It is a longitudinal section showing a sheath channel structure concerning one embodiment of this invention. It is a longitudinal cross-sectional view of a connection part. It is a longitudinal cross-sectional view of the principal part of a connection site | part. It is a front view which shows a sheath and a coupling member. It is a front view of the joint member provided with the exhaust pipe. It is a front view of the joint member provided with the exhaust pipe. It is a front view of the joint member provided with the sensor. It is a front view of the joint member provided with the insertion cylinder. It is a longitudinal cross-sectional view of the principal part of the connection site | part in the sheath pipe line structure which concerns on another embodiment. It is a longitudinal cross-sectional view of the principal part of the connection site | part in the sheath pipe line structure which concerns on another embodiment.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The sheath pipe line structure according to an embodiment of the present invention is applied when a prestressed concrete structure such as a PC girder bridge by a post-tension method is constructed.

  As shown in FIGS. 1 and 2, the sheath conduit 1 is embedded in a concrete structure 2, inserted with a PC steel material 3 for introducing prestress into the concrete structure 2, and grouted inside. 4 is filled. In addition, as grout 4, the general thing which consists of mixtures, such as Portland cement, water, an admixture, is used.

  The sheath conduit 1 is embedded in a concrete structure 2 in a meandering manner in the vertical direction, and a connection portion 12 in which the ends of the sheath 10 are connected and fixed via a joint member 11 is provided in the vicinity of the top 1a. It has been. And in this connection part 12, the countermeasure for making bleeding water which arises in a pipe line in the case of hardening of grout 4 out of a pipe line is taken. The connecting portion 12 may be provided not only in the vicinity of the top 1a of the sheath conduit 1, but also in the vicinity of the inclined portion 1b between the vicinity of the top 1a and the vicinity of the bottom 1c, or in the vicinity of the bottom 1c.

  As shown in FIGS. 2 and 4, the sheath 10 is a polyethylene resin spiral corrugated tube in which ridges 15 bulging in the radially outward direction are spirally formed in the axial direction at an equal pitch. The material of the sheath 10 is not necessarily limited to polyethylene resin, but may be other synthetic resin.

  As shown in FIG. 3, the outer peripheral surface 16 of the ridge 15 in the sheath 10 extends along the longitudinal direction (spiral direction) of the outer top surface 16 a that is flat along the axial direction and has a narrow width. And a pair of outer side surfaces 16b extending in the radially inward direction from both end portions. The outer peripheral surfaces 16 of the ridges 15 adjacent to each other in the axial direction are continuous with each other via a flat outer bottom surface 17 along the axial direction. In addition, as for the protruding item | line 15, the cross-sectional shape of the axial direction is made uniform over a longitudinal direction (spiral direction) full length.

  The joint member 11 is made of polyethylene resin, and as shown in FIGS. 2 and 4, the intermediate portion 20 is formed in a substantially cylindrical shape, and both end portions are helically fitted and fixed to the end portions of the sheath 10. The connecting tube portion 21 has a shape, and the intermediate portion 20 and the connecting tube portion 21 are continuous via a tapered portion 22. Note that the material of the joint member 11 is not necessarily limited to polyethylene resin, but may be other synthetic resin.

  On the connecting cylinder portion 21 of the joint member 11, ridges 25 bulging outward are formed in a spiral shape at an equal pitch in the axial direction. The protrusions 25 of the connecting cylinder portion 21 are formed at a size that allows the protrusions 15 to enter the inside thereof at substantially the same pitch as the protrusions 15 of the sheath 10. As shown in FIG. 3, the inner peripheral surface 26 of the ridge 25 is formed from an inner top surface 26a that is flat along the axial direction and both end portions along the longitudinal direction (spiral direction) of the inner top surface 26a. It is comprised by a pair of inner surface 26b extended in the radial direction toward the radial direction. The inner peripheral surfaces 26 of the protrusions 25 adjacent in the axial direction are in a continuous state via an inner bottom surface 27 that is curved so as to protrude in the radial inner direction. In addition, as for the protrusion 25, the cross-sectional shape of the axial direction is made uniform over a longitudinal direction (spiral direction) full length.

  When the ridge 15 of the sheath 10 and the ridge 25 of the joint member 11 are compared, the axial sectional shape of the outer peripheral surface 16 of the ridge 15 and the axial sectional shape of the inner peripheral surface 26 of the ridge 25 are mutually different. It is considered a variant. Specifically, the outer top surface 16a of the protrusion 15 is narrower than the inner top surface 26a of the protrusion 25, and the angle (about 45 degrees) with respect to the axial direction of the outer surface 16b of the protrusion 15 is the protrusion. The angle of the inner side surface 26b of 25 with respect to the axial direction (about 60 degrees) is smaller.

  Then, in the connecting portion 12, as shown in FIG. 2, the protruding strip 15 of the sheath 10 and the protruding strip 25 of the joint member 11 are screwed together, so that the distal end portion of the sheath 10 is a tapered portion 22 of the joint member 11. The connecting tube portion 21 of the joint member 11 is externally fitted and fixed to the end portion of the sheath 10.

  In this case, the outer peripheral surface 16 of the ridge 15 and the inner peripheral surface 26 of the ridge 25 are partially in contact with each other without being entirely overlapped because their axial cross-sectional shapes are different from each other. It has become. Therefore, the end portions of the sheath 10 are connected and fixed in a stable state via the joint member 11, but the end portion of the sheath 10 and the connecting tube portion 21 of the joint member 11 are continuously connected in the spiral direction. Clearance is ensured. The clearance that is continuous in the spiral direction serves as a drainage channel 30 for guiding bleeding that occurs in the pipeline when the grout 4 is cured to the outside of the pipeline.

  In general, when the grout 4 is filled in the sheath conduit 1, the grout 4 is injected into the conduit while being pressurized by a pump or the like. After injection of the grout 4, pressurization by a pump or the like is released, but the inside of the pipe line is filled with the pressurized grout 4 and maintained at a high pressure (1 atm or more). When bleeding water is generated in the pipeline when the grout 4 is cured, the bleeding water is guided from the inside of the pipeline maintained at a high pressure to the outside of the pipeline through the drainage passage 30. Thereby, corrosion of the PC steel material 3 resulting from bleeding water can be suppressed, and the intensity | strength of the concrete structure 2 can be maintained favorable over a long period of time.

  5 to 8 show modified examples of the joint member 11. These joint members 11 are provided with various functional parts as means for confirming the filling state of the grout 4 at the intermediate portion 20 thereof. These are merely examples, and for example, a joint member 11 having various functional parts in combination may be used.

  The joint member 11 shown in FIG. 5 and FIG. 6 is provided with exhaust pipes 40 and 41 projecting from the intermediate part 20 as functional parts, and filling the grout 4 through an exhaust hose connected to the exhaust pipes 40 and 41. At this time, the air remaining in the pipe can be discharged out of the pipe.

  In the joint member 11 shown in FIG. 5, a protrusion 42 projecting in the radially inward direction is formed between the intermediate portion 20 and the connecting tube portion 21, and the joint member 11 is formed at the end of the sheath 10. In a state where the connecting tube portion 21 is externally fitted and fixed, the distal end portion of the sheath 10 is pressed against the protruding portion 42 of the joint member 11.

  Further, in the joint member 11 shown in FIG. 6, the diameters of the left and right connecting cylinder parts 21 are different, the intermediate part 20 that connects them is formed in a tapered shape, and the connecting cylinder of the joint member 11 is formed at the end of the sheath 10. In the state where the portion 21 is fitted and fixed, the distal end portion of the sheath 10 is pressed against the intermediate portion 20 of the joint member 11.

  The joint member 11 shown in FIG. 7 has a sensor 50 mounted as a functional part at the intermediate portion 20, and the sensor 50 can detect the presence or absence of residual air in the pipeline.

  The joint member 11 shown in FIG. 8 has an insertion tube 60 protruding as a functional part at the intermediate portion 20, and a small camera such as a CCD camera is inserted into the insertion tube 60 to photograph the state in the pipeline. Can be done. In the joint member 11, a protruding portion 61 projecting in the radially inward direction is formed between the intermediate portion 20 and the connecting tube portion 21, and the connecting tube portion of the joint member 11 is formed at the end of the sheath 10. In a state where 21 is fitted and fixed, the distal end portion of the sheath 10 is pressed against the protruding portion 61 of the joint member 11.

  FIG. 9 shows a main part of the connection portion 12 of the sheath conduit structure according to another embodiment. In this sheath conduit structure, the shape of the inner peripheral surface 26 of the protrusion 25 on the joint member 11 side is different from that of the embodiment shown in FIG. That is, the inner peripheral surface 26 of the protrusion 25 on the joint member 11 side has an overall cross-sectional shape in the axial direction that is substantially arcuate. Then, in a state where the connecting tube portion 21 of the joint member 11 is fitted and fixed to the end portion of the sheath 10, the corner portion 16 c of the ridge 15 (the boundary between the outer top surface 16 a and the outer surface 16 b on the outer peripheral surface 16). The portion 15) is in line contact with the inner peripheral surface 26 of the ridge 25, and the ridge 15 and the ridge 25 are screwed together, and between the end portion of the sheath 10 and the connecting tube portion 21 of the joint member 11, A drainage channel 30 continuous in the spiral direction is formed. Other configurations are the same as those of the embodiment shown in FIG.

  FIG. 10 shows a main part of the connection portion 12 of the sheath conduit structure according to still another embodiment. In this sheath conduit structure, the opening portion of the clearance (drainage channel 30) between the end of the sheath 10 and the connecting tube portion 21 of the joint member 11 is made of vinyl at the end of the connecting tube portion 21 of the connecting member 11. It is different from the sheath line structure of the above embodiment in that it is closed by a closing member 70 such as a tape and the clearance is used as an isolation space 31 for moving and isolating bleeding water.

  The isolation space 31 is a spiral space that opens to the inside of the pipe and closes the end on the outside of the pipe. Therefore, the isolation space 31 is not filled with the grout 4 having a high viscosity, and bleeding water having a low viscosity is used. Only in the isolated space 31 (flowed in) is pushed out from the inside of the pipe line maintained at a high pressure by injecting the grout in a pressurized state. Therefore, similarly to the above-described embodiment, the corrosion of the PC steel material 3 due to bleeding water can be suppressed, and the strength of the concrete structure 2 can be well maintained over a long period of time. Other configurations are the same as those of the embodiment shown in FIG. Moreover, the said structure is applicable also to the thing shown in FIG. 4, and there exists the same effect.

  The present invention is not limited to the above embodiment, and it is needless to say that many modifications and changes can be made to the above embodiment within the scope of the present invention.

  For example, the outer peripheral surface 16 of the ridge 15 on the sheath 10 side and / or the inner peripheral surface 26 of the ridge 25 on the joint member 11 side include the outer peripheral surface 16 of the ridge 15 and the inner peripheral surface 26 of the ridge 25. When the ridges 15 and the ridges 25 are screwed together, the outer peripheral surface 16 of the ridges 15 and the inner peripheral surface 26 of the ridges 25 are partially in contact with each other, so that the sheath 10 As long as the drainage channel 30 and the isolation space 31 that are continuous in the spiral direction are formed between the end portion of the joint member 11 and the connecting tube portion 21 of the joint member 11, the shape may be other than the above embodiment. In addition, the tapered portion 22 of the above embodiment allows the joint member 11 to rotate (idle) until the outer peripheral surface 16 of the ridge 15 and the inner peripheral surface 26 of the protrusion 25 come into contact with each other. Although it plays a role of suppressing excessive screwing of the tip portion of the joint 10 into the joint member 11, it does not necessarily have to be tapered, and a projection or the like may be substituted.

  1 ·· Sheath pipeline, 1a ·· Near the top of the sheath pipeline, 2 ·· Concrete structure, 3 · PC steel, 4 ·· Grout, 10 ·· Sheath, 11 ·· Joint member, 12 ·· Connection Part, 15 ··· ridge, 16 ·· · Outer peripheral surface of the ridge, 16c · · Corner corner, 20 · · Intermediate portion of the joint member, 21 · · Connection cylinder, 25 · · · ridge, 26 · · · Inner surface of the strip, 30 ... drainage, 31 ... isolation space, 40, 41 ... exhaust pipe, 50 ... sensor, 60 ... insertion cylinder

Claims (6)

A sheath pipe that is embedded in a concrete structure (2), is inserted with a PC steel material (3) for introducing prestress into the concrete structure (2), and is filled with grout (4). In (1), a connection part (12) in which the ends of the sheath (10) are connected and fixed via a joint member (11) is provided, and the sheath (10) is a convex bulging outward in the radial direction. The strip (15) is a spiral corrugated tube formed in a spiral shape at an equal pitch in the axial direction, and the joint member (11) includes a connecting tube portion (21) at both ends thereof, and the connecting tube portion (21 ), The protrusions (25) bulging in the radially outward direction are formed in a spiral shape at an equal pitch in the axial direction, and the axial cross-sectional shape of the outer peripheral surface (16) of the protrusions (15) and the protrusions. The cross-sectional shape in the axial direction on the inner peripheral surface (26) of the strip (25) is irregular. In the connecting part (12), the outer circumferential surface (16) of the projecting strip (15) and the inner circumferential surface (26) of the projecting strip (25) are partially in contact with each other, 15) and the protrusion (25) are screwed together, and the connecting tube portion (21) of the joint member (11) is fitted and fixed to the end portion of the sheath (10). 10) between the end portion of the joint member (11) and the connecting cylinder portion (21), a drainage passage (30) for guiding bleeding water generated in the pipe line when the grout (4) is hardened. ) Is formed. A sheath pipe that is embedded in a concrete structure (2), is inserted with a PC steel material (3) for introducing prestress into the concrete structure (2), and is filled with grout (4). In (1), a connection part (12) in which the ends of the sheath (10) are connected and fixed via a joint member (11) is provided, and the sheath (10) is a convex bulging outward in the radial direction. The strip (15) is a spiral corrugated tube formed in a spiral shape at an equal pitch in the axial direction, and the joint member (11) includes a connecting tube portion (21) at both ends thereof, and the connecting tube portion (21 ), The protrusions (25) bulging in the radially outward direction are formed in a spiral shape at an equal pitch in the axial direction, and the axial cross-sectional shape of the outer peripheral surface (16) of the protrusions (15) and the protrusions. The cross-sectional shape in the axial direction on the inner peripheral surface (26) of the strip (25) is irregular. In the connecting part (12), the outer circumferential surface (16) of the projecting strip (15) and the inner circumferential surface (26) of the projecting strip (25) are partially in contact with each other, 15) and the protrusion (25) are screwed together, and the connecting tube portion (21) of the joint member (11) is fitted and fixed to the end portion of the sheath (10). An isolation space (31) is formed between the end of 10) and the connecting cylinder (21) of the joint member (11) to isolate bleeding water generated in the pipe line when the grout (4) is hardened. A sheath conduit structure characterized by comprising: A corner (16c) along the spiral direction is formed on the outer peripheral surface (16) of the ridge (15), and the corner of the ridge (15) ( The sheath according to claim 1 or 2, wherein the protrusion (15) and the protrusion (25) are screwed together while the line 16c) is in line contact with the inner peripheral surface (26) of the protrusion (25). Pipe structure. The sheath pipe (1) is embedded in a concrete structure (2) in a state of meandering in the vertical direction, and the connection site (12) is provided at least near the top (1a). The sheath conduit structure according to any one of the above. The sheath conduit structure according to any one of claims 1 to 4, wherein a confirmation means for confirming a filling state of the grout (4) is provided at an intermediate portion (20) of the joint member (11). An exhaust pipe (40) (41) for discharging the air in the pipe line to the outside of the pipe line, a sensor (50) for detecting the presence or absence of residual air in the pipe line, The sheath conduit structure according to claim 5, comprising any one of an insertion tube (60) for inserting a camera for photographing a state, or a combination thereof.

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