JP7689367B2 - Precast member joint structure - Google Patents

Description

This invention relates to a joint structure for precast members. Note that precast concrete is simply called precast.

A joint structure is known in which a first precast member and a second precast member are joined by a grout-filled joint that fixes the end of a first rebar inside the first precast member and the end of a second rebar protruding from the second precast member inside a sleeve embedded in the first precast member via grout filled inside the sleeve, and by grout filled in a joint space formed between the first precast member and the second precast member (Patent Documents 1 to 3).

In Patent Document 1, as shown in FIG. 10, a edging convex portion 52 that goes around the edge of the first precast member 50 is left on the lower end surface 51 during precasting, forming a joint space 53 between the inner recess and the second precast member 60. Then, grout 54 is injected from an injection port 56 on the lower side of the sleeve 55, fills the inside of the sleeve 55, overflows from an outlet 57 on the upper side of the sleeve 55, and also flows out from the lower end of the sleeve 55, filling the joint space 53.

In Patent Document 2, a spacer is interposed between the first precast member and the second precast member to form a joint space, and a grout stopper is applied to the outer periphery. Then, grout is injected from a grout injection hole drilled from the side to the bottom end face of the first precast member, and fills the joint space, then fills the inside of the sleeve from the bottom end opening of the sleeve, and overflows from the outlets on the upper and lower sides of the sleeve.

In Patent Document 3, a receiving member (bolt) is attached to the second precast member to form a joint space between the first precast member and the second precast member. Then, with the bottom opening of the sleeve covered, grout is injected from an injection port on the bottom side of the sleeve, filling the inside of the sleeve and overflowing from an outlet on the top side of the sleeve. Also, grout is injected from a joint injection hole that runs from the side of the first precast member to the bottom end face, filling the joint space.

Japanese Patent Application Publication No. 5-230877 JP 2003-301526 A JP 2012-77547 A JP 2020-94391 A

The applicant has implemented the above-mentioned grout-filled joint for the upper and lower joints of a split-type box culvert (Patent Document 4). In this split-type box culvert, multiple precast bodies are connected in the length direction of the box culvert to construct the box culvert, and each precast body includes a first precast member and a second precast member that are divided into upper and lower parts, and the first precast member and the second precast member are joined by a grout-filled joint.

This joint can be joined by grout filled in the joint space formed between the first and second precast members. In order to form this joint space, it is also possible to form a edging protrusion 52 around the edge of the lower end surface 51 of the first precast member 50 by precasting it to act as a spacer, as in Patent Document 1 (Figure 10). However, this edging protrusion 52 comes into direct contact with the upper end surface of the second precast member 60, and as there is no grout between them, this creates a missing portion that does not bond to the grout, resulting in a problem of a reduced grout bonding area.

The object of the present invention is to rationally reduce the edging portions for forming joint spaces between precast members, so as to minimize the reduction in the grout joint area between the precast members.

[1] A precast body that is connected in the longitudinal direction of a civil engineering structure (hereinafter simply referred to as the "longitudinal direction") to construct the civil engineering structure includes a divided first precast member and a second precast member,
A structure in which a first precast member and a second precast member are joined by grout filled in a joint space between a rectangular end surface of the first precast member and a rectangular end surface of the second precast member,
A joining structure for precast members, characterized in that one or both of the end faces have a pair of precast edging protrusions that abut the end faces of the opposing precast member formed by precast on the opposite sides of the peripheral portion of the end face that face the longitudinal direction, and there are no edging protrusions abutting the end faces of the opposing precast member over more than half the length of the opposite sides of the peripheral portion that face the transverse direction perpendicular to the longitudinal direction (hereinafter simply referred to as the "transverse direction").

[2] In the above [1], it is preferable that there is no edging protrusion that abuts against the end face of the opposing precast member on at least 3/4 (more preferably at least 4/5) of the length of the opposing side of the peripheral portion that faces in the transverse direction. This is because the edging can be significantly reduced.

[3] In the above [1] or [2], it is preferable that the length (width) in the longitudinal direction of the convex end face of the edging convex portion is 1.5 to 5% of the length in the longitudinal direction of the end face on which the edging convex portion is formed. If it is less than 1.5%, the strength tends to decrease, and if it exceeds 5%, the reduction rate of the edging portion tends to decrease.

[Effect]
Of the peripheral portions of the end faces of the first and second precast members, it is reasonable to form the edge projections by precasting the opposite sides that face each other in the longitudinal direction, since it is difficult to place a joint form between them when multiple precast bodies are connected in the longitudinal direction. On the other hand, it is possible to eliminate the edge projections for the opposite sides that face each other in the transverse direction, since a joint form can be applied from the outside. In this way, the edge projections can be rationally reduced, and the grout joint area between the precast members can be minimized.

According to the present invention, it is possible to rationally reduce the edging portions for forming joint spaces between precast members, thereby minimizing the reduction in the grout joint area between the precast members.

FIG. 1 is an exploded perspective view of a first precast member and a second precast member in an embodiment. FIG. 2 is an exploded perspective view of the main parts of both precast members. Fig. 3 is a perspective view of the main parts when both precast members are joined together. Note that only a part of the sleeve etc. is shown (the same is true for Figs. 4, 5 and 8). FIG. 4 is a perspective view of the essential parts when the openings of the joint spaces between the two precast members are sealed with joint masking tape. FIG. 5 is a perspective view of the essential parts when a joint formwork is placed against and fixed to the opening of the joint space between both precast members. FIG. 6 is a cross-sectional view showing the joint spaces and sleeves of both precast members after they have been filled with grout. FIG. 7 is a cross-sectional view showing the length of both precast members with the joint spaces and sleeves filled with grout. FIG. 8 is a perspective view of the main parts of both precast members after grout filling. FIG. 9 is a perspective view of a box culvert constructed with both precast members. FIG. 10 shows a conventional example (Patent Document 1), where (a) is a cross-sectional view, (b) is a bottom view of the first precast member, and (c) is a right side view.

1. Civil Engineering Structures Civil engineering structures are not particularly limited, but examples thereof include box culverts, sheds, waterways, retaining walls, and the like.

2. Precast body The first precast member and the second precast member may be, for example, a precast body divided into upper and lower parts or left and right parts (in the transverse direction), but the present invention is particularly suitable for a precast body divided into upper and lower parts.

2. Sleeves When a port other than the grout flow port is formed in the cylindrical wall of each sleeve, it is preferable that the port is closed by a cap other than that of the first precast member.

3. Grout The grout is not particularly limited, but mortar is preferred because of its adhesion to concrete and ease of handling, and non-shrink mortar is particularly preferred.

Next, an embodiment in which the present invention is embodied in a joint structure of precast members of a precast body 1 that constructs a box culvert will be described with reference to Figures 1 to 9. Note that the structure, materials, shapes, and dimensions of each part in the embodiment are examples and can be modified as appropriate without departing from the spirit of the invention.

As shown in Figure 9, a number of precast bodies 1 are connected in the longitudinal direction of the box culvert to construct the box culvert. Each precast body 1 is formed into a rectangular ring of a given length, consisting of a bottom plate, a top plate, and two ends.
As shown in Figure 1, the precast body 1 is composed of an upper first precast member 10 and a lower second precast member 20, which are divided into two parts, upper and lower, at the midpoint between the two side wall portions.

As shown in FIG. 6 and FIG. 7, the first precast member 10 and the second precast member 20 are
(1) grout 3 filled in a joint space 2 between a rectangular end surface of a first precast member 10 and a rectangular end surface of a second precast member 20;
(2) A plurality of grout-filled joints in which an end of a first reinforcing bar 11 in a first precast member 10 and an end of a second reinforcing bar 21 protruding from an end face 22 of a second precast member 20 are fixed inside a sleeve 4 embedded in the lower part of the first precast member 10 via grout 3 filled inside the sleeve 4;
The electrodes are joined by

The grout 3 is made of a commercially available non-shrink mortar, for example, "SS Mortar" manufactured by Japan Splice Sleeve Co., Ltd.
The sleeve 4 is a commercially available sleeve, for example, "NMB Splice Sleeve" manufactured by the same company.

As shown in Figures 2, 6 and 7, the end face 12 of the first precast member 10 has a pair of precast edging protrusions 13 that abut against the end face 22 of the second precast member 20 formed by precasting on opposite sides facing each other in the longitudinal direction of the peripheral portion of the end face 12, and there are no edging protrusions abutting the end face 22 of the second precast member 20 along the entire length of the opposite sides facing each other in the transverse direction of the peripheral portion (the both ends of the edging protrusions 13 that extend over both ends of the opposite sides are not included).
Similarly, the end face 22 of the second precast member 20 has a pair of edging protrusions 23 precast on opposite sides facing each other in the longitudinal direction of the peripheral portion of the end face 22, and no edging protrusions are present along the entire length of the opposite sides facing each other in the transverse direction of the peripheral portion.

The end face 12 of the first precast member 10 and the end face 22 of the second precast member 20 each have a longitudinal length of 1000 mm and a transverse length (width) of 500 mm. The longitudinal length (width) of the convex end face of each edging protrusion 13, 23 is 25 mm (2.5% of the longitudinal length of the end face), a transverse length of 500 mm (the same as the longitudinal length of the end face), and a height of 10 mm.

A pair of edging protrusions 13 of the first precast member 10 and a pair of edging protrusions 23 of the second precast member 20 come into contact with each other, forming a joint space 2 between the end face 12 of the first precast member 10 and the end face 22 of the second precast member 20. The height of the joint space 2 is therefore 20 mm. The joint space 2 is closed in the longitudinal direction by the raised surfaces of these edging protrusions 13, 23, and is open in the transverse direction.

Of the peripheral portions of the end faces 12, 22, the opposite sides that face each other in the longitudinal direction are adjacent when multiple precast bodies 1 are connected in the longitudinal direction, and it is difficult to place a joint formwork 32 between them, so it is reasonable to form the edging protrusions 13, 23 by precast. On the other hand, the opposite sides that face each other in the transverse direction can be fitted with a joint formwork 32 from the outside, so the edging protrusions can be eliminated. In this way, the edging parts can be rationally reduced, and the grout joint area between the precast members 10, 20 can be kept from decreasing as much as possible.

It is preferable to apply a caulking material such as an epoxy adhesive between the edging protrusion 13 of the first precast member 10 and the edging protrusion 23 of the second precast member 20 to prevent grout leakage and to stop water.

At the center of each edging protrusion 13, 23, an alignment protrusion 14, 24 that protrudes inward is precast to be continuous with the edging protrusion 13, 23. The convex end face of the alignment protrusion 14, 24 has a length of 85 mm in the longitudinal direction, a length of 70 mm in the transverse direction, and a height of 10 mm. An alignment recess is formed in a part of the alignment protrusion 14, 24, and an alignment pin 30 is fitted into the alignment recess.

As shown in Figures 2, 6, 9, etc., a grout injection path (hose 25) leading from the outside to the joint space 2 is provided in the second precast member 20,
Each sleeve 4 has one end surface that opens into the joint space 2, and a grout flow port 5 is formed in the cylindrical wall near the other end.
In the first precast member 10, grout flow holes 15 are formed for each sleeve 4, the grout flow holes 15 opening from the grout flow ports 5 of the sleeves 4 to the outside,
The grout 3 is continuously filled into the hose 25, the joint space 2, the inside of the sleeve 4, the grout flow port 5 and the grout flow hole 15.

Grout flow holes 15 that open to the outside from the grout flow ports 5 of each sleeve 4 are formed in the first precast member 10, one for each sleeve 4, so the number of grout flow holes formed in the first precast member 10 can be halved compared to the conventional method, and the effort required for their formation can be reduced. Also, as shown in Figure 9, the grout flow holes 15 only appear in a single row on the surface of the first precast member 10, improving the poor appearance compared to the conventional method.

The grout injection path is formed by a hose 25 made of a polymeric material, and the injection side end of the hose 25 protrudes 500 mm outward from the second precast member 20. For example, a resin hose with an inner diameter of about 19 mm is used for the hose 25. The hose 25 is embedded in the second precast member 20 when the second precast member 20 is precast, the outlet side end opens into the joint space 2, and the injection side end protrudes from the side of the second precast member 20. The protruding length is set to 500 mm, taking into consideration the operability of connecting the hose 25 during injection and the folding process after injection is completed, which will be described later. In the illustrated example, two grout injection paths (hoses 25 in this example) are provided, but the number can be changed depending on the dimensions of the precast members.

As shown only in Figures 2 and 8 for convenience, the second precast member 20 is provided with a spare hose 26 that leads from the outside to the joint space 2. The spare hose 26 also protrudes to the outside from the second precast member 20, and its protruding end is raised above the height of the joint space 2 during grout injection.

The sleeve 4 used had a grout flow port 5 and another grout flow port 6 formed in the cylindrical wall near one end, so the grout flow port 6 was closed with a cap 7 before embedding in the first precast member 10.

The joint structure of the precast members in the embodiment configured as described above is assembled by transporting the precast members 10 and 20 to the construction site and joining them at the construction site as follows.

(1) First, as shown in the change from Figure 1 and Figure 2 to Figure 3, the first precast member 10 is placed on the second precast member 20 and set up. Prior to this setting, a caulking material is applied to the edging protrusion 23. In addition, accurate positioning can be achieved by fitting the centering pin 30 into the centering recess.
Then, the edging protrusions 13 and 23 abut against each other via the caulking material, forming a joint space 2 between the end face 12 of the first precast component 10 and the end face 22 of the second precast component 20. The joint space 2 is closed in the longitudinal direction by the rising surfaces of these edging protrusions 13, 23 and is open in the transverse direction.
The precast body 1, consisting of the first precast member 10 and the second precast member 20, is joined in a row along the length of the box culvert, but as the joining structure and sealing structure can be applied to conventional structures, a description of them will be omitted.

(2) Next, as shown in FIG. 4, joint masking tape 31 is applied to the boundary between the first precast member 10 and the second precast member 20 so as to close the transverse opening of the joint space 2. The joint masking tape 31 is intended to stop grout leakage that may occur if only the next joint formwork 32 is used.

(3) Next, as shown in FIG. 5, a joint formwork 32 is placed on the boundary between the first precast member 10 and the second precast member 20 so as to close the transverse opening of the joint space 2 (even beyond the joint masking tape 31). Furthermore, a fixing bracket 33 is placed on the joint formwork 32, and the fixing bracket 33 is fastened to the embedded nut 17 of the first precast member 10 and the embedded nut 27 of the second precast member 20 by a bolt 34, thereby pressing the joint formwork 32 against the boundary. For example, a wooden board can be used for the joint formwork 32.

(4) Next, as shown in Figures 6 and 7, a grout pump (not shown) is connected to the hose 25, and the grout 3 is injected. The grout 3 flows through the hose 25, the joint space 2, the inside of the sleeve 4, the grout flow port 5, and the grout flow hole 15 in that order, and continuously fills them. Note that the grout flow hole 15 is plugged with a plug 16 before the grout is injected.
The grout 3 is discharged from the protruding end of the spare hose 26 (FIGS. 3 and 8), and the grout injection is completed after the plug 16 has confirmed that the grout has been completely filled up to the grout flow hole 15. It is also preferable to complete the injection after bending the hose 25 to prevent backflow.

(5) After the grout 3 has hardened and cured, remove the joint formwork 32, peel off the joint masking tape 31, and cut and remove the protruding portions of the hose 25 and spare hose 26 protruding from the surface of the second precast member 20 as shown in Figures 8 and 9, to complete the box culvert.

The present invention is not limited to the above-described embodiment, and can be embodied by making appropriate modifications without departing from the spirit of the invention.
(a) Providing a grout injection passage (hose 25) in the first precast member 10.
(i) The edging convex portion 13 is formed by precasting on only one of the end face 12 of the first precast member 10 or the end face 22 of the second precast member 20.

REFERENCE SIGNS LIST 1 Precast body 2 Joint space 3 Grout 4 Sleeve 5 Grout flow port 6 Another grout flow port 7 Cap 10 First precast member 11 First reinforcing bar 12 End face 13 Edge projection 15 Grout flow hole 16 Plug 20 Second precast member 21 Second reinforcing bar 22 End face 23 Edge projection 25 Hose 26 Spare hose 31 Joint masking tape 32 Joint formwork 33 Fixing metal fitting

Claims (5)

The precast body (1) which is connected in the longitudinal direction of the civil engineering structure to construct the civil engineering structure includes a first precast member (10) and a second precast member (20) which are separated from each other;
A structure in which a first precast member (10) and a second precast member (20) are joined by grout (3) filled in a joint space (2) between a rectangular end surface (12) of the first precast member (10) and a rectangular end surface (22) of the second precast member (20),
Either or both of the end faces (12, 22) have a pair of edging protrusions (13, 23) formed by precast on the opposite sides of the peripheral portion of the end face (12, 22) that face each other in the longitudinal direction, and there is no edging protrusion that abuts on the end face of the counterpart precast member over more than half the length of the opposite sides of the peripheral portion that face each other in a direction perpendicular to the longitudinal direction ,
A joint structure for precast members, characterized in that an alignment convex portion (14, 24) that protrudes inward from the edging convex portion (13, 23) is formed by precasting continuous with the edging convex portion (13, 23), an alignment recess is formed in a part of the alignment convex portion (14, 24), and an alignment pin (30) is fitted into the alignment recess. The precast body (1) which is connected in the longitudinal direction of the civil engineering structure to construct the civil engineering structure includes a first precast member (10) and a second precast member (20) which are separated from each other,
A structure in which a first precast member (10) and a second precast member (20) are joined by grout (3) filled in a joint space (2) between a rectangular end surface (12) of the first precast member (10) and a rectangular end surface (22) of the second precast member (20),
The two end faces (12, 22) are formed by precasting a pair of edging protrusions (13, 23) that abut against the end faces of the opposing precast member on the opposite sides of the peripheral portion of each end face (12, 22) that face each other in the longitudinal direction, and there is no edging protrusion that abuts against the end face of the opposing precast member over more than half the length of the opposite sides that face each other in a direction perpendicular to the longitudinal direction of the peripheral portion.
A joint structure for precast members, characterized in that a pair of edging protrusions (13) of the first precast member (10) and a pair of edging protrusions (23) of the second precast member (20) abut against each other. A joint structure of precast members as described in claim 2, wherein an alignment convex portion (14, 24) that protrudes inward is formed by precasting continuous with the edging convex portion (13, 23), an alignment recess is formed in a part of the alignment convex portion (14, 24), and an alignment pin (30) is fitted into the alignment recess. A joint structure for precast members as described in claim 1 , 2 or 3, in which there is no edging protrusion that abuts against the end face of the opposing precast member over more than 3/4 of the length of the opposing sides of the peripheral portion facing each other in the perpendicular direction. A joint structure for precast members as described in claims 1, 2, 3 or 4, wherein the longitudinal width of the convex end face of the edging convex portion (13, 23) is 1.5 to 5% of the longitudinal length of the end face (12 , 22) on which the edging convex portion (13, 23 ) is formed.

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