JP6968728B2 - How to join precast concrete members - Google Patents

Description

The present invention relates to a method for joining precast concrete members, and more particularly to a method for joining precast concrete members connected by a tension material such as a PC cable.

In concrete structures, various precast concrete members (hereinafter referred to as PCa members) manufactured in advance at the factory are often used for rationalization of construction and shortening of construction period. When the PCa members of prestressed concrete are connected to each other by the post-tension method, the joint portion between the PCa members is joined by a dry joint or a wet joint. When joining by a wet joint, grout material such as non-shrink mortar is filled between the joint surfaces of the PCa member, but it is necessary to prevent the grout material from entering the sheath pipe of the PCa member from the edge of the PCa member at the time of filling. be.

In order to deal with this problem, in Patent Document 1, the tube (expansion type 20) inserted into the sheath tube is expanded to close the sheath tube, the joint portion is filled with a filler, and then the expansion type 20 is pulled out. , A joining method for preventing the filler from entering the sheath tube is disclosed.

Japanese Unexamined Patent Publication No. 2017-71996

However, in the joining method described in the first embodiment of FIGS. 1 to 3 of Patent Document 1, the rubber inflatable type 20 (tube) is inserted into the sheath tube as it is, so that the inflatable type 20 is inside the sheath tube. It is not easy to get caught in the unevenness and insert the inflatable type 20 over the entire length of the sheath tube. In addition, the expansion type 20 may be damaged by being caught by the unevenness inside the sheath tube at the time of insertion, and the expansion type 20 cannot be expanded, so that the filling material may not be prevented from entering the sheath tube.

Therefore, an object of the present invention is to improve the efficiency of construction by improving the insertability of a tube which is a protective material for preventing the filler from entering the sheath tube when joining joints between PCa members. It is an object of the present invention to provide a method of joining precast concrete members, which improves and reduces the possibility of tube breakage.

In order to achieve the above object, the present invention is a joining method for joining a plurality of precast concrete members by a tension material wired inside the through hole, and can be expanded to a diameter larger than the diameter of the through hole. A tube formed by reducing the diameter of a plurality of expansion portions arranged at predetermined intervals in the extension direction and a restraint portion located between the plurality of expansion portions by reducing the diameter of the restraint portion is described. The expansion portion straddles the predetermined gap in the through hole of each precast concrete member adjacent to each other with a predetermined gap so that the through hole communicates with each other, and both ends of the through hole have a predetermined length. The step of inserting the tube so that it is located inside, and injecting fluid into the tube to inflate the inflated portion so as to be in close contact with the inner wall of the through hole to close the open end of each through hole and to close the open end of the through hole. It is characterized by including a step of forming an insertion space for the tension material in a predetermined gap and a step of filling the gap with a filler.

The restraining portion may be reduced in diameter by folding a part of the tube.

The tube may further have an inflatable portion in the through hole, and the inflatable portion in the through hole may be closely fixed to the inner peripheral surface of the through hole by injecting a fluid into the tube.

It is preferable that the tube has a guide member attached to the tip thereof.

The restraint portion is preferably formed by winding a tape around the tube.

According to the present invention, when joining joints between PCa members, it is possible to improve the efficiency of construction by improving the insertability of the tube for preventing the filler from entering the sheath tube. In addition, the possibility of the tube being damaged can be reduced.

(A) is a perspective view of a structure of a PCa member according to an embodiment of the present invention, (b) is a side view of (a), and (c) is a side cross section of a tube used in the embodiment of the present invention. figure. (A) is an enlarged sectional perspective view of a structure of a PCa member according to an embodiment of the present invention, and (b) is an enlarged side sectional view of (a). (A) is a side sectional view of a tube insertion step of the structure joining method according to the embodiment of the present invention, and (b) is a side sectional view of the tube expansion step. (A) is an enlarged side sectional view of a tube insertion step of the method of joining a PCa member according to an embodiment of the present invention, (b) is an enlarged side sectional view of the tube expansion step, and (c) is the joint portion. Enlarged side sectional view of the grout material filling process. (A) is a side sectional view of the tube used in the modified example when compressed air is injected, and (b) is a side sectional view of the tube used in another modified example when compressed air is not injected.

A method of joining a structure 1 such as a box culvert formed by a PCa member connected by a tension material (PC steel material) of the present invention by a wet joint will be described below with reference to the attached drawings.

FIG. 1A shows a formwork in which a reinforcing bar assembly assembled with a required cover thickness secured in a precast concrete member manufacturing factory constructed in one embodiment of the joining method according to the present invention is arranged. The PCa members 10-1, 10-2, ..., 10-n manufactured by placing concrete in the building are shown. In the present embodiment, FIG. 1A shows a prestressed concrete box culvert to be constructed as the PCa member 10 in the longitudinal direction at the site by a post-tension method. In the PCa member main body 11 shown in FIG. 1B, a sheath tube 12 forming a through hole through which a PC cable, which is a tension material, is inserted into the PCa member 10 is arranged (FIG. 1A).

As shown in FIGS. 3 (a) and 3 (b), the joint portion J of the structure 1 having a full length Lc formed by the PCa members 10-1, 10-2, 10-3, ..., 10-n has a joint portion J. By using the tube 20 shown in FIG. 1 (c), each open end of the sheath tube 12 is closed, and the filler 30 is filled while maintaining a state in which the tension material can be inserted through the joint portion J in the longitudinal direction. .. As shown in FIGS. 2A and 2B, for example, the joint portion J has a predetermined distance (gap) between the joint surface A of the PCa member 10-1 and the joint surface B of the PCa member 10-2. It is formed to have and face each other. Before filling the joint portion J with the filler 30, the expansion portion 22 of the tube 20 is inserted into the opening 13 on the joint surface A side of the joint portion J and the sheath pipe 12 of the PCa member 10-1 and the sheath pipe of the PCa member 10-2. The expansion portion 22 is expanded by injecting a fluid such as compressed air into the tube 20 by arranging it in the opening 14 on the joint surface B side of the 12. By expanding the expansion portion 22, the opening 13 and the opening 14 are closed, the inflow of the filler 30 into the sheath pipe 12 is prevented, and a space for inserting the tension material is secured in the joint portion J.

The joint portion J between the PCa member 10-2 and the PCa member 10-3, the joint portion J between the PCa member 10-3 and the PCa member 10-4, and so on are the same as those of the PCa member 10-1 and the PCa member 10-2. Since the configuration is as follows, the description thereof will be omitted.

[Construction method of joint part J]
Hereinafter, a method of joining the joining portion J of the PCa member will be described with reference to each figure. This joining method includes a PCa member placement step, a tube insertion step, a tube expansion step, a joint grout material filling step, and a tensioning step.

As shown in FIG. 1 (c), the tube 20 used in this embodiment has a total length L (L> Lc) except for the wire P described later. As shown in FIG. 2B, the tube 20 has a cylindrical shape having an outer diameter D2 smaller than the inner diameter DS of the sheath tube 12. As the tube 20, in the present embodiment, a synthetic rubber product such as styrene-butadiene rubber or chloroprene having elasticity is used. In order to improve the durability of the tube 20, a product with fiber reinforcement may be used. A ready-made product such as an air formwork such as a gap guard (registered trademark) for closing the joint can be diverted to the tube 20. As shown in FIGS. 3 (a) and 3 (b), the tube 20 has an in-hole expansion portion 21, an expansion portion 22, a restraint portion 23, and a tip expansion portion 24 in the extension direction in consideration of the function performed during expansion. , The rear end expansion portion 25, and so on. As shown in FIG. 2B, the tube 20 usually has an outer diameter D2 smaller than the inner diameter DS of the sheath tube 12, but expands beyond the inner diameter DS of the sheath tube 12 when a fluid such as compressed air is injected. can do. Further, the wire P is connected to the tip expansion portion 24 of the tube 20 and is closed.

Here, the arrangement state of the tube 20 in the PCa member 10 will be described.
As shown in FIGS. 2 (a), 2 (b) and 3 (a), the expansion portion 21 in the through hole of the tube 20 is arranged inside the sheath tube 12 of the PCa member 10-1 and the PCa member 10-2. NS. When compressed air is injected into the tube 20, as shown in FIG. 3B, the expansion portion 21 in the through hole expands, the tube 20 comes into close contact with the inner peripheral surface of the sheath tube 12, and the tube 20 is sheathed. It is fixed in the tube 12. As described above, the expansion portion 22 is arranged so as to straddle the joint portion J (space E (E1)), the opening 13, and the opening 14. When compressed air is injected into the tube 20, the expansion portion 22 expands and the openings 13 and 14 are closed. As a result, when the filler 30 is filled in the joint portion J, as shown in FIG. 2B, the filler 30 is prevented from flowing into the sheath pipe 12, and the tension material 30 is prevented from flowing into the joint portion J. Placement space is secured. The restraint portion 23 is arranged so as to communicate the expansion portion 21 in the through hole and the expansion portion 22 (including the tip expansion portion 24 and the rear end expansion portion 25). In the present embodiment, the restraint portion 23 is formed by winding an adhesive tape around a tube 20 folded in the radial direction including the expansion portion 21 in the through hole and the expansion portion 22, and the diameter thereof is D3. As a result, the outer diameter D2 of the maximum diameter (expanded portion 22) of the tube 20 in the normal state (when compressed air is not filled) is smaller than the outer diameter D1 of the original tube 20, but when the tube 20 expands, the sheath The inner diameter DS of the tube 12 or more.

As shown in FIG. 3A, a wire P is connected to the tip of the tip expansion portion 24. The tip of the tip expansion portion 24 protrudes from the sheath tube 12. The wire P is a guide (guide member) for passing the tube 20 through the sheath tube 12. The rear end of the tip expansion portion 24 is arranged in the sheath tube 12 of the PCa member 10 in the same manner as the expansion portion 22. A marker M for positioning the tube 20 is attached to the tip expansion portion 24. The rear end of the rear end expansion portion 25 protrudes from the sheath tube 12, and an air compressor or the like (not shown) for injecting compressed air into the tube 20 is connected via a check valve.

(PCa member placement process)
In the PCa member arranging step, the joint surface A in the longitudinal direction of the PCa member 10-1 and the junction surface B in the longitudinal direction of the PCa member 10-2 are shown in FIGS. 2 and 3A. The sheath tubes 12 and 12 are arranged so as to face each other with a predetermined gap W2. In the present embodiment, the predetermined gap W2 is set to about 20 mm. W2 is appropriately set according to the scale of the structure, workability, and the like.

(Tube insertion process)
When the tube 20 is inserted into the PCa member 10, as shown in FIG. 4A, the expansion portion 22 of the tube 20 has a joint portion J (gap E) and the joint surface A of the sheath tube 12 of the PCa member 10-1. It is arranged so as to straddle the opening 13 on the side and the opening 14 on the joint surface B side of the sheath tube 12 of the PCa member 10-2. As shown in FIG. 2B, a sufficient predetermined length F is secured from the openings 13 and 14 to prevent the filler 30 from infiltrating. In the present embodiment, the tube 20 has a width W1 of the PCa member 10 shown in FIG. 2A, a width W2 of the joint portion J, and a tube 20 so that the center of the joint portion J is arranged at the center of the expansion portion 22. The length L1 of the expansion portion 21 in the through hole, the length L2 of the expansion portion 22, and the length L3 of the restraint portion 23 are arranged so as to be W1 + W2 = L1 + L2 + 2L3. At this time, assuming that the portion of the expansion portion 22 that does not contact the sheath tube 12 even during expansion is S, L2 = 2S + 2F + W2 as shown in FIG. 2B. Further, the length L4 of the tip expansion portion 24 shown in FIG. 2A, which is the tip of the tube 20, up to the marker M is determined. When the position of the marker M is arranged on the end surface C on the opposite side of the joint surface A of the PCa member 10-1, the position of the marker M is determined so that the position of the tube 20 has the above-mentioned positional relationship. Since the tube 20 is slightly shortened in the length direction when the compressed air is exhausted from the tube 20, it is preferable to consider the shortened amount of the tube 20 in advance when determining the position of the marker M.

(Tube expansion process)
As shown in FIGS. 2 (b) and 3 (b), in the tube expansion step, compressed air is supplied to the tube 20 from an air compressor or the like (not shown) connected to the rear end expansion portion 25 of the tube 20, and a through hole is formed. The inner expansion portion 21, the expansion portion 22, the tip expansion portion 24, and the rear end expansion portion 25 are expanded until the diameter DS of the sheath tube 12 or more is reached. As shown in FIG. 4B, when the expansion portion 22 expands, the opening 13 and the opening 14 are closed, and the opening 13 and the opening 14 and the joint portion J (the gap E (E1)) are partitioned. At this time, as shown in FIGS. 2A and 3A, it is confirmed that the position of the marker M of the expanded tip expansion portion 24 is not deviated from the end face C.

(Joint grout material filling process)
As shown in FIG. 4C, in the joint portion grout material filling step, the gap E is surrounded by using known joint retainers 40 and 40, and the joint portion J is filled with the grout material 30. After the grout material 30 is sufficiently dried, the air in the tube 20 is exhausted, and the tube 20 having a reduced diameter is removed from the sheath tube 12.

(Tension process)
In the tensioning step, a PC cable (not shown) as a tensioning material is inserted into the sheath tubes 12 and 12 and the hole 50 formed in the joint portion J by the expansion portion 22 shown in FIG. 4 (c). Then, one end of the PC cable is fixed to the end face C shown in FIG. 3 (b) using a known fixing tool (not shown). Subsequently, the other end of the PC cable is fixed to the end face D by applying a predetermined tension to the PC cable using a known tension fixing tool (not shown) using a hydraulic pump and a jack (not shown). .. After fixing the PC cable, the sheath tubes 12 and 12 are filled with grout material to form the structure 1 shown in FIG. 1 (a).

[Transformation example of tube]
As a modification of the tube 20, a tube 20A as shown in FIG. 5A will be described. In the tube 20A, the restraint portion 23A corresponding to the restraint portion 23 of the tube 20 is long in the long axis direction of the tube 20A, and there is no portion corresponding to the expansion portion 21 in the through hole. In the tube 20A, only the expansion portion 22 exposed to the joint portion J (FIG. 2) expands, so that the time for injecting compressed air into the tube 20A can be shortened. Further, by forming the outside of the restraint portion 23A with a material having a low coefficient of friction, the insertability of the restraint portion 23A is enhanced, the time for inserting the tube 20A into the sheath tube 12 can be shortened, and the tube 20A is the sheath tube 12. It is possible to reduce the possibility of being caught and damaged inside, and it is expected that the construction time will be shortened.

Further, as a modification of the tube 20, the tube 20B as shown in FIG. 5B will be described. In the tube 20B, the restraint portion 23B corresponding to the restraint portion 23 of the tube 20 is long in the long axis direction of the tube 20B, there is no portion corresponding to the expansion portion 21 in the through hole, and the expansion portion 22B corresponding to the expansion portion 22. Has a larger diameter than the restraint portion 23 even when air is not injected. Even in the tube 20B, only the expansion portion 22B exposed to the joint portion J (FIG. 2) expands. Further, since the expansion portion 22B has a large diameter, the time for injecting air into the tube 20B can be shortened. Further, since the expansion portion 22B has a large diameter, it can be confirmed by visually observing the joint portion J that the expansion portion 22B is arranged in the joint portion J.

In the present embodiment, the restraint portion 23 is formed by winding an adhesive tape around a tube 20 folded in the radial direction, but instead of the adhesive tape, a thin metal plate or a synthetic resin that can be easily bent is wound. By turning to form the restraint portion 23, the strength and insertability of the restraint portion 23 can be increased. Further, the restraint portion 23 may be formed by attaching a rubber ring or the like having the same diameter as the restraint portion 23 to the tube 20. Further, by changing the weaving method of the reinforcing fibers of the tube 20, a portion where the reinforcing fibers hardly expand and contract may be formed and used as the restraining portion 23.

In the present embodiment, the restraint portion 23 is formed by folding the tube 20 in the radial direction, but the tube 20 may be wound in a spiral shape to reduce the diameter of the tube 20.

In the present embodiment, this joining method is used in the longitudinal direction, but when the PCa member 10 is divided in the transverse direction, it can also be applied in the transverse direction.

The present invention is not limited to the above-described embodiments, and various modifications can be made within the scope of each claim. That is, an embodiment obtained by combining technical means appropriately modified within the scope of the claims is also included in the technical scope of the present invention.

1 Structure 10 PCa member 11 PCa member body 12 Sheath pipe (through hole)
13,14 Opening 20,20A, 20B Tube 21 Through-hole expansion part 22,22B Expansion part 23,23A, 23B Restraint part (constraint member)
24 Tip expansion part 25 Rear end expansion part 30 Grout material J Joint part A, B Joint surface C, D End surface E, E1, E2 Void (gap)
P wire (guidance member)

Claims (5)

It is a joining method that joins multiple precast concrete members with a tension material wired inside the through hole.
A plurality of expansion portions arranged at predetermined intervals in the extension direction, which can be expanded to a diameter larger than the diameter of the through hole, and a restraint portion located between the plurality of expansion portions are provided with the restraint portion. A tube formed by reducing the diameter,
The expansion portion straddles the predetermined gap in the through hole of each precast concrete member adjacent to each other with a predetermined gap so that the through hole communicates with each other, and both ends penetrate the penetration by a predetermined length. The process of inserting so that it is located in the hole,
A fluid is injected into the tube to inflate the inflated portion so as to be in close contact with the inner wall of the through hole, the open end of each through hole is closed, and the insertion space of the tension material is provided in the predetermined gap. The process of forming and
The process of filling the gap with the filler and
A method of joining precast concrete members, which comprises. The method for joining a precast concrete member according to claim 1, wherein the restraining portion has a diameter reduced by folding a part of the tube. The tube further has an inflatable portion in the through hole.
The method for joining a precast concrete member according to claim 1, wherein a fluid is injected into the tube to closely fix the expansion portion in the through hole to the inner peripheral surface of the through hole. The method for joining a precast concrete member according to claim 1, wherein the tube has a guide member attached to the tip thereof. The method for joining a precast concrete member according to claim 1 or 2, wherein the restraining portion is formed by winding a tape around the tube.

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