JP7120897B2 - Joining method of precast members - Google Patents

Description

The present invention relates to precast component technology.

Precast members may be used for the purpose of shortening the construction period. For example, in the construction work to update the aged floor slabs of a road bridge in service, it is necessary to complete the work in a short period of time, such as late at night when there is little traffic and open the next morning. The use of precast members may shorten the construction period. On the other hand, precast members are subject to deformation due to shrinkage during production and introduction of prestress. In particular, precast members made of ultra-high-strength fiber-reinforced concrete can be made stronger and lighter, but shrinkage is greater than that of ordinary concrete, so if a large member is manufactured, it will deform greatly. . If such a precast member is used and a dry joint is adopted in which the end surfaces are butted and connected in the finished shape, the errors of each precast member are added, resulting in a large error in the final finished shape. Concerned. Therefore, when connecting a plurality of precast members such as a bridge floor slab, there is a risk that the accuracy of the finished shape of the final structure cannot be ensured. Such problems are not limited to bridge floor slabs, but may also occur in other structures that connect a plurality of precast members, such as box girders.

Therefore, by adopting a so-called wet joint in which cast-in-place concrete or the like is placed between precast members, errors in the precast members may be absorbed (see, for example, Patent Document 1).
Wet joints require curing by pouring concrete or the like into the joints at the construction site. Therefore, it could not be adopted when there was a time constraint.

JP 2018-059357 A

An object of the present invention is to develop a technique for joining precast members without using a wet joint.

The present invention realized a joining technique that does not use wet joints in the renovation work of floor slabs using precast floor slabs.
A method for joining precast members, which is the first invention for solving the above-mentioned problems, temporarily places a plurality of precast members constituting a predetermined length range at a place other than the construction location, and The method includes a step of casting a cement-based material to form an adjustment member, and a step of connecting the adjustment member and the precast member used for temporary placement at the construction site.
Further, the method for joining precast members according to the second invention comprises a temporary placement step of temporarily placing a plurality of precast members at a location other than the construction location, and a main assembling step of main assembly of the plurality of precast members at the construction location. Be prepared. In the temporary placement step, the member temporary placement work of placing the pair of precast members with a gap between the end faces, the formwork assembly work of installing the formwork on the lower surface and the side surface of the gap, and the A member forming operation of filling a gap with a cement-based material to form an adjusting member and a demolding operation of demolding the formwork are performed. Further, in the main assembling step, a member carrying-in operation of carrying the precast member and the adjusting member to the construction site, and a member connecting operation of connecting the pair of precast members via the adjusting member are performed.
According to the method for joining the precast members, since the precast members are connected by using the precast adjustment member molded by the match casting method using the end faces of the precast members as the formwork, the precast member shrinks during the manufacturing process. It is possible to build a structure in a state in which errors caused by warping or the like during the introduction of prestress are absorbed. Moreover, since the adjusting member is a precast member, there is no need to use a wet joint on site, and work can be simplified. In addition, it is possible to perform high-quality construction in a short time.

In the member temporary arrangement work, if another precast member is connected to the end surface of the precast member opposite to the gap side, an adjustment member is formed for each predetermined number of precast members in the main assembling process. Even in this case, it is possible to form an adjustment member capable of absorbing errors caused by connecting a plurality of precast members.
Further, it is desirable that in the member provisional placement work, the angle of the end face of the precast member is adjusted so that the end face of the precast member is inclined at an angle that is expected to occur in the end face of the precast member in the main assembling process. In this way, for example, an adjusting member that absorbs errors caused by connecting a plurality of precast members can be formed by arranging one precast member in the temporary placement step.
In the demolding operation, one of the pair of precast members is removed from the adjusting member, and in the member carrying operation, the adjusting member is attached to the end face of the other precast member and carried in. You may By doing so, it is possible to further shorten the construction period by reducing the number of work steps in the main assembly process.

According to the method for joining precast members of the present invention, it is possible to construct a high-quality structure by absorbing errors that occur when manufacturing precast members and errors that occur when introducing prestress, and wet joints. It is possible to simplify the work and shorten the construction period compared to the case of adopting .

BRIEF DESCRIPTION OF THE DRAWINGS It is a figure which shows the precast floor slab of embodiment of this invention, Comprising: (a) is a top view seen from the lower side, (b) is sectional drawing. It is a figure which shows the state which precast floor slabs were temporarily placed, (a) is a side view, (b) is a top view. It is a figure which shows a formwork, Comprising: (a) is a side view, (b) is a top view. It is a sectional view showing a demolding jig. It is a cross-sectional view showing a temporary fixing jig. It is a side view which shows an inclination adjusting member.

<First Embodiment>
In the first embodiment, a case will be described in which a precast floor slab (precast member) 1 is used to shorten the construction period in a project to renew an aged floor slab of a bridge in service. The precast floor slab 1 is made of a concrete member to which prestress has been introduced. In the floor slab renewal project, a plurality of precast floor slabs 1 are connected in the direction of the bridge axis. As shown in FIG. 1, the precast floor slab 1 has grid-like ribs 11 formed on its lower surface. A joint portion 12 is formed at the end portion of the lower surface of the precast floor slab 1 . A bolt insertion hole 13 is formed in the joint portion 12 . Note that the location where the joint 12 is formed is not limited to the lower surface of the precast floor slab 1 . The precast floor slabs 1 are connected to each other by bolts B inserted through the bolt insertion holes 13 of both precast floor slabs 1 while abutting the ends of the other adjacent precast floor slabs 1 .
The precast floor slab 1 undergoes deformation such as warping due to shrinkage (manufacturing error) during manufacturing and introduction of prestress. Therefore, when a plurality of precast floor slabs 1 are connected by dry joints, errors (warping) of the precast floor slabs 1 accumulate, resulting in large errors at the ends of the bridge. In this embodiment, a method of joining precast members and an adjusting member 3 capable of absorbing deformation occurring in the precast floor slab 1 are adopted.

The method of joining precast members according to the present embodiment includes a temporary placing step of temporarily placing a number of precast floor slabs 1 corresponding to a predetermined length range, and a main assembly step of assembling the precast floor slabs 1 temporarily placed in the temporary placing step. and
In the temporary placement process, a member temporary placement work, a form assembly work, a member formation work, and a demolding work are performed at a place other than the construction site.
In the member temporary placement work, as shown in FIGS. 2(a) and 2(b), a pair of precast floor slabs 1 (first joint floor slab 14 and second joint floor slab 15) are placed together at their end faces. are arranged with a gap S between them. At this time, the other end face of the first joint floor slab 14 (the end face opposite to the second joint floor slab 15) and the other end face of the second joint floor slab 15 (the first joint floor slab 15) Other precast floor slabs 1 (general floor slabs 16) are connected to the end face opposite to the slab 14). The number of floor slabs 16 for common parts to be joined to the first joint floor slab 14 and the second joint floor slab 15 is not limited. Also, the floor slabs 16 for the general section may be installed as required.

In the formwork assembling work, as shown in FIGS. ), the formwork 2 is installed on the bottom surface and the side surface of the gap S (shortage within the predetermined length range).
The bottom formwork 21 installed on the lower surface of the gap S is made of a steel plate. In addition, the material constituting the bottom mold 21 is not limited. The ends of the first joint floor slab 14 and the second joint floor slab 15 are placed on the upper surface of the end of the bottom mold 21 in the bridge axis direction. Between the upper surface of the bottom mold 21 and the lower surface of each precast floor slab 1, waterproof rubber or grease is interposed to ensure watertightness. The bottom formwork 21 and the precast floor slab 1 are fixed with jigs such as bolts as necessary.

The side formwork 22 installed on the side surface of the gap S consists of a structural member having an L-shaped cross section. The side mold frame 22 is arranged so that one piece (bottom plate 23) faces the lower side and the other piece (side plate 24) faces the side surface of the gap S. The end of the side plate 24 in the bridge axis direction is in contact with the end of the precast floor slab 1 on the gap S side. The side plate 24 is formed with insertion holes 25 each having a long hole corresponding to the contact portion with the precast floor slab 1 . That is, the side plate 24 is formed with through-holes 25 (a total of two through-holes 25) at the front end and the rear end in the bridge axis direction. The side frame 22 is fixed to the precast floor slab 1 by screwing bolts B inserted through the insertion holes 25 into the precast floor slab 1 . At this time, waterproof rubber or grease is interposed between the side molds 22 and the precast floor slab 1 to ensure watertightness. The insertion hole 25 does not necessarily have to be an elongated hole, and may have a circular shape larger than the outer diameter of the shaft portion of the bolt B, for example.

In addition, in the gap S, a cylindrical body 31 is arranged corresponding to the position of the bolt insertion hole 13 of the adjacent precast floor slab 1 . The cylindrical body 31 has an inner diameter equivalent to that of the bolt insertion hole 13 and has a strength such that it is not deformed by the pressure of the concrete placed in the member forming work. In addition, the material forming the cylindrical body 31 is not limited, and for example, a steel pipe, a vinyl chloride pipe, or the like may be used.
Further, in this embodiment, the end face of the floor slab 14 for the first joint and the inner face of the mold 2 are coated with a release agent (not shown). The release agent may also be applied to the end face of the floor slab 15 for the second joint.

In the member forming work, the area surrounded by the formwork 2 (the gap S between the first joint floor slab 14 and the second joint floor slab 15) is filled with concrete and cured until a predetermined strength is achieved. do. When the concrete hardens, the adjusting member 3 is formed by match-casting the abutment surface with the precast floor slab 1 (the first joint floor slab 14 or the second joint floor slab 15). The material constituting the adjusting member 3 is not limited to concrete as long as it is a cement-based material, and may be, for example, mortar or non-shrinkage mortar. Further, reinforcing bars may be arranged in the adjusting member 3 as necessary.

In the demolding work, the formwork 2 is demolded after the concrete filled in the gap S develops a predetermined strength. In this embodiment, along with demoulding of the formwork 2, the floor slab 14 for the first joint (one of the pair of precast floor slabs 1) is removed from the adjusting member 3, and the second joint is removed. The adjusting member 3 is left on the end face of the partial floor slab 15 (the other precast floor slab 1). The adjusting member 3 does not necessarily have to be left on the end face of the floor slab 15 for the second joint portion, and may be removed from both precast floor slabs 1 .
In the demolding work, a demolding jig 4 is used. The demolding jig 4 is fixed to the adjusting member 3 and the floor slab 14 for the first joint portion, as shown in FIG. Inserts 32 and 17 are previously embedded in the adjustment member 3 and the floor slab 14 for the first joint portion, respectively, and a jig body 41 is fixed to the inserts 32 and 17 via bolts 42 that are screwed together. The jig main body 41 is composed of an L-shaped structural member when viewed in cross section. The jig main body 41 fixed to the adjusting member 3 and the jig main body 41 fixed to the first joint portion floor slab 14 face each other. A jig body 41 fixed to the adjusting member 3 is provided with a long bolt 43 protruding toward the first joint floor slab 14 side so as to be able to move back and forth. When the long bolt 43 is extended toward the first joint floor slab 14 , a pressing force is applied to the jig main body 41 fixed to the first joint floor slab 14 . The plate 14 separates from the adjusting member 3 . When the adjusting member 3 is removed from both precast floor slabs 1 , the stripping jig 4 may be fixed to the first joint floor slab 14 and the second joint floor slab 15 .

In the main assembling process, a member carrying-in operation and a member connecting operation are performed.
In the member carrying-in work, the plurality of precast floor slabs 1 used in the temporary placement process and the adjustment members 3 formed in the temporary placement process are carried into the construction site. At this time, the adjusting member 3 is carried in while attached to the end surface of the floor slab 15 for the second joint portion.
At the time of carrying in the members, as shown in FIG. The temporary fixing jig 5 is fixed to the inserts 32 and 17 previously embedded in the adjustment member 3 and the floor slab 15 for the second joint portion. That is, the temporary fixing jig 5 is disposed across the adjusting member 3 and the second joint floor slab 15 , thereby connecting the adjusting member 3 and the second joint floor slab 15 . .

In the member connecting work, as shown in FIGS. 1A and 1B, the first joint floor slab 14 and the second joint floor slab 15 are connected via the adjusting member 3 . With the adjustment member 3 interposed between the first joint floor slab 14 and the second joint floor slab 15, the bolt insertion hole 13 of the first joint floor slab 14 and the bolt of the adjustment member 3 are inserted. By inserting the bolt B through the insertion hole (cylindrical body 31) and the bolt insertion hole 13 of the second joint floor slab 15 and screwing the bolt B onto the nut N, the first joint floor slab 14 and the second joint floor slab 14 are connected to each other. The floor slabs 15 for two joints are connected.
Further, the general floor slab 16 used in the temporary placement process is connected to the first joint floor slab 14 and the second joint floor slab 15 .

According to the precast member joining method and adjustment member 3 of the present embodiment, the precast floor slab 1 is assembled using the precast adjustment member 3 formed by the match casting method using the end face of the precast floor slab 1 as a formwork. Since the precast floor slabs 1 are connected, the precast floor slabs 1 can be connected in a state in which an error or the like caused by shrinkage during manufacture of the precast floor slabs 1 or warping or the like when prestress is introduced is absorbed.
In addition, since the adjustment member 3 is a precast member molded outside the construction site, there is no need to use a wet joint on site, which simplifies the work and enables high-quality construction to be performed in a short time. It becomes possible.
Since the adjustment member 3 is attached to the end surface of the second floor slab 15 and is transported, the risk of damage to the thin adjustment member 3 during transportation can be reduced. Also, there is no need to secure a space for transporting the adjusting member 3 individually.

<Second embodiment>
In the second embodiment, as in the first embodiment, in a project to renew an aged floor slab of a bridge in service, a joint of precast members capable of absorbing deformation occurring in the precast floor slab 1. The use of the method and adjustment member 3 will be described.
The method of joining precast members includes a temporary placement step of temporarily placing a number of precast floor slabs 1 corresponding to a predetermined length range, and a main assembly step of permanently assembling the precast floor slabs 1 temporarily placed in the temporary placement step. there is
In the temporary placement process, a member temporary placement work, a form assembly work, a member formation work, and a demolding work are performed at a place other than the construction site.

In the member temporary placement work, a pair of precast floor slabs 1 (first joint floor slab 14 and second joint floor slab 15) are arranged with a gap S between their end surfaces.
At this time, as shown in FIG. The inclination adjustment member 6 is arranged to adjust the precast floor slabs 1 to the height of the warp of the precast floor slabs 1 that is expected to occur at the joint when connecting the precast floor slabs 1 in a number corresponding to a predetermined length range. It is a member that lifts the end of the That is, the ends of the floor slabs 14 for the first joint and the floor slabs 15 for the second joint on the gap S side (butting surface side) are lifted by the inclination adjusting member 6, and the angles of the end faces are adjusted. ing. The tilt adjusting member 6 may be configured to be extendable so that height adjustment is possible. At this time, a water stop plate 61 is arranged on the lower surface of the gap S.
In addition, the details of the temporary placement process (contents of the formwork assembly work, member forming work, and demolding work) are the same as in the first embodiment, and thus detailed descriptions are omitted.
Further, since the contents of the assembly process are the same as those of the first embodiment, detailed description thereof will be omitted.

According to the precast member joining method and the adjusting member 3 of the present embodiment, since the adjusting member 3 is formed by the match casting method in a state where the angle of the end face of the precast floor slab 1 is adjusted, the first It is not necessary to connect the floor slabs 16 for common parts to the floor slabs 14 for joints and the floor slabs 15 for second joints. Therefore, in the temporary placement process, it is possible to omit the labor required to join the required number of general floor slabs 16 . Moreover, even if it is not possible to secure a work space corresponding to the predetermined length range at the work location of the temporary placement process, the adjustment member 3 can be molded.
Since other effects of the second embodiment are the same as those of the first embodiment, detailed description thereof will be omitted.

Although the embodiments according to the present invention have been described above, the present invention is not limited to the above-described embodiments, and each constituent element can be appropriately modified within the scope of the present invention.
In the above embodiment, a case has been described in which a plurality of precast floor slabs 1 to which prestress has been introduced in advance are connected in the bridge axis direction at the site, but prestress may be introduced at the site. For example, after installing a plurality of precast floor slabs 1 at predetermined positions, tendons (PC steel wires, PC steel bars, PC The prestress may be introduced on site by inserting a steel strand, etc., or the prestress may be introduced on site by an out cable. Since the adjustment member 3 is interposed at the joint between the precast floor slabs 1, the adjustment member 3 absorbs the displacement (error) during the manufacture of the precast floor slabs 1, and the prestress is effectively applied within the cross section. can be done.
In the above-described embodiment, the method for joining precast members and the adjustment member 3 of the present invention are employed in a floor slab renewal project using the precast floor slab 1. However, the method for joining precast members and the adjustment member Members to which 3 is applicable are not limited to floor slabs. For example, the method for joining precast members and the adjusting member of the present invention may be employed at joints between precast box girders.

1 Precast floor slab (precast member)
14 Floor slab for first joint 15 Floor slab for second joint 16 Floor slab for general part 2 Formwork 3 Adjustment member 4 Stripping jig 5 Temporary fixing jig 6 Tilt adjustment member

Claims (5)

A step of temporarily placing a plurality of precast members constituting a predetermined length range at a location other than the construction location, and casting a cement-based material in the insufficient portion within the predetermined length range to form an adjustment member;
A method for joining precast members, comprising: performing a connecting operation using the precast member used for temporary placement at a construction site and an adjustment member. A temporary placement step of temporarily placing a plurality of precast members at a location other than the construction location;
A method for joining precast members, comprising a main assembling step of assembling a plurality of the precast members at the construction location,
In the temporary placement step,
A member temporary arrangement work of arranging the pair of precast members with a gap between the end faces;
Formwork assembling work for installing formwork on the lower surface and side surfaces of the gap;
a member forming operation of filling the gap with a cementitious material to form an adjustment member;
Performing a demolding work of demolding the formwork,
In the main assembly process,
A member carrying-in operation of carrying the precast member and the adjusting member to the construction site;
and a member connecting operation of connecting the pair of precast members via the adjusting member. 3. The method of joining precast members according to claim 2, wherein, in said member temporary placement work, another precast member is connected to an end surface of said precast member opposite to said gap side. 4. The method of joining precast members according to claim 2, wherein the angle of the end face of the precast member is adjusted in the temporary arrangement of the members. In the demolding operation, one precast member of the pair of precast members is removed from the adjustment member;
5. The method for joining precast members according to any one of claims 2 to 4, wherein in the member carrying-in operation, the adjustment member is carried in with the end surface of the other precast member attached. .

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