Duct burial method and the duct panels and end protectors used therein

Abstract

To enable burying a duct through a beam without providing an opening larger than the duct's outer diameter in the beam, eliminating supporting work to facilitate performing work independently and easily, and easily removing a formwork without damaging the duct's interior and exterior surfaces.SOLUTION: In panel preparation step S1, a duct panel 10 with a duct hole 11 and an outer periphery 10a is prepared. In opening setting step S2, formwork openings 6 are provided on the sides of a formwork 3. In duct positioning step S3, an outer end face of a duct 7 is positioned outside the formwork 3. In opening sealing step S4, the duct 7 is passed through the duct hole 11 and the outer periphery of the duct panel 10 is fixed to the formwork opening 6 in a liquid-tight manner. In panel fixing step S5, the duct panel 10 is fixed to the formwork 3. In concrete placing step S6, concrete is placed inside the formwork 3.SELECTED DRAWING: Figure 7

Description

Technical Field

[0001] The present invention relates to a duct embedding method for installing a duct through a reinforced concrete beam, a duct panel used therefor, and an end protector.

Background Art

[0002] In a building having a reinforced concrete beam, for example, a duct (exhaust duct or air supply duct) may be installed by passing through a large beam (a beam connecting columns). Such a construction method is disclosed in, for example, Patent Documents 1 and 2.

[0003] "Penetrating pipe for reinforced concrete beam and its construction method" in Patent Document 1 forms a through-hole by incorporating a reinforcing bar assembly (hereinafter "beam bars") into a formwork, then embedding a penetrating pipe in the beam bars and placing concrete. The penetrating pipe is composed of a cylindrical body formed by rounding a rectangular elastic flat plate material into a partial arc shape and provided with an opening slit, a fixture disposed in the circumferential direction at both ends of the cylindrical body and fixed to the formwork by nailing, and an engaging means for connecting the engaging sides of each other constituting the opening slit of the cylindrical body. The cylindrical body is inserted and reversed by expanding the opening slit from the reinforcement gap on the upper surface of the beam bars, and is installed and fixed at a predetermined position inside the formwork.

[0004] "Driving formwork for forming a fire compartment through-hole and this construction method" in Patent Document 2 sets a formwork for forming a through-hole (hereinafter, "sleeve") at a predetermined position of a formwork for forming a fire compartment (hereinafter, "section formwork"), and places concrete in the section formwork. Then, the section formwork is removed, a pipe (duct) is passed through the sleeve, and a filler such as mortar is packed into the gap between the duct and the sleeve.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document Ⅱ

[0006] The duct construction method described in Patent Document 1 above had the following problems. (1) When using sliding pipes, after assembling the reinforcing bars that make up the beam ("beam reinforcement") in the rebar work, and before dropping them into the formwork, it is necessary to carry out the work of installing the sliding pipes in the piping work, which results in a joint work (or coordinated work). Joint work refers to a work in which a craftsman of a different trade than the craftsman performing the work is present when a particular work is being carried out. In the simultaneous construction of rebar work and piping work, there are many beams, and it becomes necessary to work on them sequentially while paying attention to the timing of each other's work. Because different tasks intersect, care must be taken, and interruptions occur, resulting in low work efficiency. (2) When using a slide tube or the cylindrical body described in Patent Document 1, the work of fixing both ends to the inner surface of the formwork must be done through the gaps in the beam reinforcement, which results in poor workability. In particular, after the slab reinforcement (reinforcement that makes up the floor) has been assembled on top of the beam reinforcement, the work becomes practically impossible. (3) Because the entire cylindrical body is embedded in concrete, there is a risk of a large amount of slurry leaking into the interior of the cylindrical body through the gaps. Slurry refers to water containing cement components. In addition, in order to connect the duct to the indoor (or outdoor) side, it will be necessary to remove the concrete around the end of the cylindrical body embedded in the concrete.

[0007] Furthermore, the duct construction method described in Patent Document 2 above had the following problems. (4) Because an opening larger than the outer diameter of the duct is formed in the beam, the beam strength is greatly reduced. (5) After the concrete is poured, the gap between the sleeve and the duct needs to be filled with mortar.

[0008] This invention was devised to solve the problems described above. Specifically, the first objective of this invention is to eliminate the need for sequential construction work and to enable independent and easy implementation without interfering with rebar work, thereby increasing work efficiency. The second objective is to enable the insertion and embedding of a hollow cylindrical duct into a reinforced concrete beam without creating an opening in the beam larger than the outer diameter of the duct, thereby suppressing a decrease in the strength of the reinforced concrete beam. Furthermore, the third objective is to enable easy removal of the formwork without damaging the inner and outer surfaces of the duct, and to significantly reduce slag leakage into the duct. [Means for solving the problem]

[0009] According to the present invention, a duct burying method is provided in which a hollow cylindrical duct is embedded by penetrating it into a reinforced concrete beam, A panel preparation step involves preparing a duct panel having a duct hole through which the duct passes and an outer peripheral portion located at a distance from the inner surface of the duct hole. An opening setting step is to provide a formwork opening on the side of the formwork surrounding the outer surface of the beam, excluding the upper surface of the beam reinforcement that constitutes the beam, in which the outer surface of the duct panel can be liquid-tightly fixed. A duct positioning step involves positioning the outer end face of the duct outside the formwork, The opening closing step involves passing the duct through the duct hole and fixing the outer periphery of the duct panel to the formwork opening in a liquid-tight manner to close the formwork opening. A panel fixing step for fixing the duct panel to the formwork, A duct embedding method is provided, which includes a concrete pouring step for pouring concrete inside the formwork.

[0010] Furthermore, according to the present invention, a duct panel used in the above-mentioned duct burial method is provided, It is made of an elastic material that is not easily adhered to concrete and is flexible. When fixed to the formwork opening, it has a formwork-side inner surface that is flush with the inner surface of the formwork, A duct panel is provided, characterized in that the duct hole has an inner diameter that contacts or is close to the outer surface of the duct. [Effects of the Invention]

[0011] According to the duct embedding method of the present invention, the steps of opening setting, duct positioning, opening sealing, panel fixing, and concrete pouring described above are carried out at a different time than the rebar work in which beam reinforcement is assembled and dropped into formwork. Therefore, it is possible to eliminate the need for concurrent work and carry out the work independently and easily without interfering with the rebar work, thereby increasing work efficiency.

[0012] Furthermore, in the duct positioning step, the outer end face of the duct is positioned outside the formwork, and in the concrete pouring step, concrete is poured inside the formwork. This construction method allows a hollow cylindrical duct to be embedded through a reinforced concrete beam without creating an opening in the beam larger than the outer diameter of the duct, thereby suppressing a decrease in the strength of the reinforced concrete beam.

[0013] Furthermore, in the opening-closing step, the duct is passed through the duct hole, and the outer periphery of the duct panel is liquid-tightly fixed to the formwork opening to seal it, thereby significantly reducing slag leakage from the formwork opening.

[0014] Furthermore, since the outer perimeter of the duct panel is positioned at a distance from the inner surface of the duct hole through which the duct passes, the formwork can be easily removed after the concrete has hardened without damaging the inner or outer surfaces of the duct.

[0015] Furthermore, in the duct positioning step, the outer end face of the duct is positioned outside the formwork, which significantly reduces slag leakage into the duct. [Brief explanation of the drawing]

[0016] [Figure 1] This is a cross-sectional view of a beam after concrete pouring using the duct embedding method according to the present invention. [Figure 2]It is a view taken along the line A-A of FIG. 1. [Figure 3] It is an explanatory view of a duct panel. [Figure 4] It is a schematic view of the formwork removal work in the formwork removal step. [Figure 5] It is an explanatory view of a duct support member. [Figure 6] It is a connection structure diagram of the duct of the completed beam and the indoor duct. [Figure 7] It is an overall flow chart of the duct embedding method of the present invention. [Figure 8] It is an explanatory view showing an example of an end protector. [Figure 9] It is a cross-sectional view taken along the line A-A of FIG. 8(B) showing the same state as FIG. 4.

Embodiments for Carrying out the Invention

[0017] Hereinafter, preferred embodiments of the present invention will be described in detail based on the accompanying drawings. In each figure, the same reference numerals are assigned to common parts, and duplicate descriptions are omitted.

[0018] FIG. 1 is a cross-sectional view of a beam after concrete placement by the duct embedding method according to the present invention. In this figure, the beam bars 2 constituting the beam 1 (main beam in this example) are assembled in steel reinforcement work and dropped into the formwork 3. The formwork 3 is composed of a plate material (for example, plywood), is provided along the outer surface of the beam 1, and is located surrounding the outer peripheral surface excluding the upper surface of the beam bars 2. In this example, the formwork 3 has a beam bottom weir plate 3a, a slab bottom weir plate 3b, an inner weir plate 3c, and an outer weir plate 3d. A reinforcing plate 4 is fixed to the connecting portion of the formwork 3 with nails or the like to reinforce so that mortar does not leak out from the gap of the formwork 3. Further, slab bars (steel bars constituting the floor) not shown are embedded above the beam bars 2. Concrete 5 is placed from above inside the formwork 3, and after the concrete 5 has hardened, the formwork 3 is removed, whereby the beam 1 is completed.

[0019] In Figure 1, the duct panel 10 of the present invention is used by fixing its outer periphery 10a to a formwork opening 6 provided in the formwork 3 in a liquid-tight manner. In this example, the formwork opening 6 is provided only on the indoor side (inner weir plate 3c in this example), but it may also be provided on the outer side (outer weir plate 3d in this example).

[0020] In this example, the outer end 7a of the duct 7 is supported on the outer inner surface of the formwork 3 (the inner surface of the outer weir plate 3d in this example) via the duct support member 12. If a formwork opening 6 is also provided on the outer side (the outer weir plate 3d in this example), the duct support member 12 is not required.

[0021] Duct 7 is, for example, a hollow cylindrical spiral duct. The spiral duct has spiral projections on the outer surface of a hollow cylindrical straight pipe. The outer diameter of the hollow cylindrical straight pipe is, for example, 101 mm or 151 mm, and the outer diameter of the projections is, for example, 105 mm or 155 mm. Note that duct 7 is not limited to a spiral duct, and may be a hollow cylindrical straight pipe without projections.

[0022] In this diagram, the axis of duct 7 is set with a slope such that the outside side is lower than the inside side, allowing condensation inside the duct to be discharged to the outside. This slope is, for example, 1 / 200.

[0023] Figure 2 is a view taken along arrow AA in Figure 1. In Figures 1 and 2, the duct retaining plate 14 is made of plywood, for example, and is positioned in contact with the outer edge front surface 10c, which is the indoor side front surface of the duct panel 10. Furthermore, multiple single pipes 16 (hollow circular pipes) are positioned in contact with the front surface of the duct holding plate 14, and the formwork 3 is tightened via the single pipes 16, the duct holding plate 14, and the duct panel 10 by the pipe holding member 18.

[0024] Concrete 5 is poured from above into the inside of the formwork 3 described above. After the concrete 5 hardens, the formwork 3, single pipe 16, duct holding plate 14, duct panel 10, and duct support material 12 are removed, completing the beam 1 in which the duct 7 is embedded by passing it through the reinforced concrete beam 1.

[0025] Figure 3 is an explanatory diagram of the duct panel 10. In this figure, (A) is a front view showing the indoor side of the duct panel 10, and (B) is a cross-sectional view of (A) BB.

[0026] In Figure 3, the duct panel 10 is made of an elastic material that is flexible and does not easily adhere to the concrete 5. The material of the duct panel 10 is, for example, synthetic rubber (ethylene propylene rubber), but it may also be made of other materials (for example, plastic).

[0027] The fitting portion 10e of the duct panel 10 into the formwork opening 6 is preferably a polygon composed of straight lines. In this example, the outer perimeter 10a and the fitting portion 10e are quadrilaterals (squares). This configuration allows the shape of the formwork opening 6 provided in the formwork 3 to be a polygon composed of straight lines, which can be easily installed in the formwork using a circular saw or similar tool commonly available for formwork construction. The polygon is not limited to a quadrilateral (square), but may be a rectangle or any other polygon. Furthermore, in this invention, the fitting portion 10e is not limited to a polygon, but may be of other shapes (for example, a circle).

[0028] The duct panel 10, while fixed to the formwork opening 6, has a formwork-side inner surface 10b that is flush with the inner surface of the formwork (the inner surface of the inner weir plate 3c or the outer weir plate 3d). This configuration allows the area around the duct 7 of the completed beam 1 to be flush with the outer beam 1. Furthermore, the duct panel 10 has a sealing surface 10f that is flush with the outer surface of the formwork when fixed to the formwork opening 6. The sealing surface 10f is provided along the entire circumference of the fitting portion 10e and has a width that reduces slag leakage. This width should preferably be at least 10 mm.

[0029] In Figure 3(B), the fitting portion 10e and the sealing surface 10f are set to be in close contact with the inner surface and front surface of the formwork opening 6. This configuration makes it possible to suppress slag leakage from between the formwork opening 6 and the outer periphery 10a. Furthermore, a tapered surface 10g is provided between the outer edge of the outer peripheral portion 10a and the sealing surface 10f, which is inclined away from the sealing surface 10f. With this configuration, when removing the duct panel 10 from the formwork 3 in the formwork removal step S7 described later, a crowbar (metal rod) can be inserted between the tapered surface 10g and the outer surface of the formwork 3 to pull out the outer circumference 10a from the formwork 3.

[0030] The duct panel 10 has a duct hole 11 through which the duct 7 passes. The duct hole 11 has an inner diameter that contacts or is close to the outer surface of the duct 7. This configuration makes it possible to reduce the leakage of slurry from the gap between the duct 7 and the duct hole 11 when concrete 5 is poured inside the formwork 3. In this example, the inner surface 11a of the duct hole 11 has a tapered surface that is wider on the formwork side inner surface 10b. This configuration allows the duct 7 to be smoothly passed through the duct hole 11 of the duct panel in the duct positioning step S3 described later. It also makes it easier to remove the duct panel 10 in the formwork removal step S7 described later. There are cases where masking tape is wrapped around the outer circumference of the end face of duct 7, and cases where it is not. The minimum diameter of the duct hole 11 should be set accordingly for both cases, depending on whether or not masking tape is used.

[0031] The center O2 of the duct hole 11 is located eccentrically above the centroid O1 of the fitting portion 10e of the duct panel 10. This eccentricity e is, for example, 10 mm. Furthermore, the front of the duct panel 10 has markings to indicate the top and bottom of the duct panel 10 (for example, the words "up" and "down"). Other methods may be used to indicate the top and bottom. With this configuration, by setting the center height of the centroid O1 of the duct panel 10 to be the same as the center height of the duct support member 12 described above, the center O2 of the duct hole 11 can be set higher by an eccentricity amount e, and the duct 7 can be easily set to have a slope (for example, 1 / 200) where the outside side is lower than the inside side.

[0032] The outer edge front surface 10c of the outer peripheral portion 10a of the duct panel 10 preferably has a constant thickness from the inner surface 10b on the formwork side. This thickness is set to add the desired rigidity to the duct panel 10. This thickness is, for example, about 50 mm. Furthermore, the duct panel 10 has a recessed surface 10d on the inside of its outer periphery 10a that surrounds the duct hole 11. The recessed surface 10d is recessed from the front surface 10c toward the formwork. The depth of this recess is, for example, about 20 mm. In other words, with the duct panel 10 shown in Figure 1 fixed to the formwork opening 6 and the duct 7 positioned, the recessed surface 10d is set to be smaller than the distance from the inner surface of the formwork to the outer end surface of the duct 7. With this configuration, when concrete 5 is poured inside the formwork 3, any slurry leaking from the gap between the duct 7 and the duct hole 11 falls inward (towards the formwork) from the outer end face of the duct 7, thus preventing the slurry from entering the duct.

[0033] Figure 4 is a schematic diagram of the removal of formwork 3 in the formwork removal step S7, which will be described later. After removing the duct panel 10, when removing the formwork 3 (in this example, the inner weir board 3c), a crowbar (metal rod) is inserted from underneath the inner weir board 3c and the bottom is pulled out to remove the nails from the slab's plywood. In this case, if there is no gap between the inner surface of the formwork opening 6 and the outer surface of the duct 7, the duct 7 and the formwork 3 will interfere with each other at the part indicated by B in the figure, potentially causing scratches or dents on the inner and outer surfaces of the duct. Therefore, the outer periphery 10a of the duct panel 10 is set to be positioned at a sufficient distance from the inner surface of the duct hole 11. For example, in Figure 3(B), the distance (dimension L) from the inner surface of the duct hole 11 to the inner surface of the formwork opening 6 should be set to 20 mm or more.

[0034] During the removal of formwork 3 in Figure 4, if duct 7 and formwork 3 interfere with each other at the point indicated by B in the figure, the load from the formwork opening 6 of formwork 3 may deform the end of duct 7 that protrudes from the structural surface. If the amount of deformation is large, the effort required to correct the deformation will be considerable. Furthermore, if scratches or dents occur at the end of duct 7, it becomes difficult to create a liquid-tight seal at the connection point between duct 7 and indoor duct 8 in the connection structure between duct 7 and indoor duct 8 shown in Figure 6, which will be described later. Therefore, in the panel fixing step S5 described later, it is preferable to insert the end protector 24 inside the end of the duct 7 (in this case, the indoor end 7b).

[0035] The end protector 24 is inserted inside the end of the duct 7 (indoor end 7b), and its outer surface 24a extends circumferentially along the inner surface of the end, and has the function of applying radially outward pressure to the end (indoor end 7b) by elastic force.

[0036] Figure 8 is an explanatory diagram showing an example of an end protector 24. Figure 8(A) shows the end protector 24 in a state where it is not subjected to external force. In this state, the end protector 24 has a body portion 25 at both ends 25a and 25b, with its outer circumferential surface 24a extending circumferentially along an outer diameter D2 that is larger than the inner diameter D1 of the duct 7. In this example, the end protector 24 has a form in which a portion of a hollow cylindrical elastic material having an outer diameter D2 that is larger than the inner diameter D1 of the end of the duct 7 is cut and separated in the axial direction of the duct 7. The cross-sectional shape of the body portion 25 is preferably rectangular, but other shapes are also acceptable.

[0037] Figure 8(B) shows the state in which the body portion 25 of the end protector 24 is inserted along the inner surface of the end of the duct 7. In this state, one end 25a and the other end 25b of the body portion 25 are close together or overlap radially, and the restoring force of the body portion 25 applies radially outward pressure to the end of the duct 7. In this example, the end protector 24 has a configuration in which one end 25a, which is separated and faces the other in the circumferential direction, is superimposed on the inside of the other end 25b. Alternatively, there may be no overlap, and one end 25a and the other end 25b may face each other and be in close proximity.

[0038] For example, for a spiral duct with an inner diameter D1 = 100 mm (or 150 mm) and a pipe thickness of 0.5 mm, a rigid polyvinyl chloride pipe with an outer diameter D2 = 114 mm (or 165 mm) is used as the "hollow cylindrical elastic material". The type of rigid polyvinyl chloride pipe can be either VP or VU.

[0039] A portion of the rigid polyvinyl chloride pipe is cut axially, and as shown in Figure 8(B), one end 25a, which is separated and faces the other in the circumferential direction, is placed inside the other end 25b, and inserted into the inside of the end of the duct 7. This configuration allows the end protector 24 to resist the load from the formwork opening 6 of the formwork 3, thereby suppressing the amount of deformation of the spiral duct.

[0040] Figure 9 is a cross-sectional view taken along line AA of Figure 8(B), showing a similar condition to that in Figure 4. As shown in this figure, taking into consideration the ease of insertion and removal of the end protector 24 into the inside of the end of the duct 7, the axial length of the end protector 24 is preferably about 10 to 20 mm longer than the length that protrudes from the structural surface of the duct 7.

[0041] In this example, the body portion 25 has a through hole 25c that penetrates radially or axially. The end protector 24 also has a removal tool 26 fixed through the through hole 25c. A through-hole 25c is provided in a part of the body 25 of the end protector 24, penetrating radially or axially, and a ring-shaped removal tool 26 through which tape or string is passed is provided in the hole. This configuration allows the end protector 24 to be removed by hooking a crowbar onto the ring-shaped removal tool 26 during formwork dismantling, eliminating the need for ladders or other equipment. Furthermore, the removed end protector 24 can be reused in other locations (for example, on an upper floor).

[0042] Figure 5 is an explanatory diagram of the duct support member 12. In this figure, (A) is a front view of the duct support member 12, and (B) is a side view of (A). The duct support member 12 has a cylindrical portion 12a that fits with the inner diameter of the outer end 7a of the duct 7, and a flange portion 12b that has a larger outer diameter than the cylindrical portion 12a and abuts against the outer end 7a. The cylindrical portion 12a is provided with multiple through holes (nail holes 12c) for passing nails or the like. Using these nail holes 12c, the duct support material 12 can be fixed to the outer inner surface of the formwork 3 (the inner surface of the outer weir plate 3d in the example of Figure 1) with nails or the like. The outer diameter d1 of the cylindrical portion 12a is slightly smaller than the inner diameter of the duct 7, so that it fits snugly and prevents slag from entering. The outer diameter d2 of the flange portion 12b is larger than the inner and outer diameters of the duct 7, so that slag does not enter from the end face of the duct 7.

[0043] Figure 6 is a diagram showing the connection structure between the completed beam 1's duct 7 and the indoor duct 8. In this example, the duct 7 in beam 1 (hereinafter referred to as "embedded duct 7") and the indoor duct 8 have the same inner and outer diameters. Nipple 9 is a standard nipple that fits the buried duct 7 and the indoor duct 8. Nipple 9 is a single-piece component and has a hollow cylindrical fitting portion 9a that fits into the same inner diameter and a protruding portion 9b located in the center in its longitudinal direction and projecting outward from the inner diameter of the ducts 7 and 8. Ducts 7 and 8 are to be fixed to the fitting portion 9a with self-drilling screws 20, respectively. This configuration allows the ducts 7 and 8 to be firmly connected via the nipple 9.

[0044] In Figure 6, flame-retardant tape (e.g., non-combustible butyl tape 21a) is wrapped around the protruding portion 9b of the nipple 9, and the ends of the ducts 7 and 8 are fitted onto it. Non-combustible butyl tape 21b is also wrapped around the outside of the ends of the ducts 7 and 8, and aluminum tapes 22a and 22b are wrapped twice on top of that. This configuration allows for a liquid-tight seal and protection of the connection between ducts 7 and 8.

[0045] Figure 7 is an overall flow diagram of the duct burial method of the present invention. In this figure, the duct burial method of the present invention has steps (processes) S1 to S7.

[0046] In panel preparation step S1, the duct panel 10 described above is prepared, which has a duct hole 11 through which the duct 7 passes, and an outer peripheral portion 10a located at a distance from the inner surface of the duct hole 11. This step S1 is carried out in advance to accommodate the duct 7 to be used.

[0047] In the formwork construction T1, the formwork 3 described above is manufactured and fixed in place. The opening setting step S2 is also performed during this construction. In the opening setting step S2, a formwork opening 6 is provided on the side of the formwork 3 that surrounds the outer surface of the beam reinforcement 2 constituting the beam 1, excluding the upper surface, allowing the outer periphery 10a of the duct panel 10 to be fixed in a liquid-tight manner.

[0048] As shown in Figure 1, when the duct 7 protrudes only to the interior side, a formwork opening 6 is provided on the interior side of the formwork 3, and a duct support member 12 that supports the exterior end 7a of the duct 7 is fixed to the exterior inner surface of the formwork 3.

[0049] Unlike Figure 1, when the duct 7 protrudes to both the indoor and outdoor sides, formwork openings 6 are provided on both the indoor and outdoor sides of the formwork 3.

[0050] In step S2, if the shape of the formwork opening 6 is a polygon (for example, a quadrilateral) composed of straight lines, it is best to process the formwork opening 6 (cut the plywood) using a circular saw or similar tool that is readily available in the formwork construction T1. The processing of the formwork opening 6 (cutting of plywood) in opening setting step S2 is carried out by craftsmen of the same trade as those performing the formwork construction T1. Therefore, opening setting step S2 does not fall under the category of sequential construction work as described above.

[0051] In the reinforcement work T2, the beam reinforcement 2 described above is assembled and placed into the formwork 3. In the rebar work T2, the slab reinforcement (reinforcement that makes up the floor) may be assembled on top of the beam reinforcement 2 prior to the duct positioning step S3.

[0052] In duct positioning step S3, the outer end face of the duct 7 is positioned outside the formwork 3.

[0053] As shown in Figure 1, when the duct 7 is to protrude only to the interior side, the exterior end 7a of the duct 7 is fixed to the duct support material 12, and the interior end 7b of the duct 7 is positioned on the exterior of the interior side of the formwork 3. The outer end 7a of the duct 7 is preferably fitted into the cylindrical portion 12a of the duct support material 12, which is fixed to the inner surface of the outer weir plate 3d during formwork construction T1, and secured by making the end face tightly contact with the flange portion 12b.

[0054] Unlike Figure 1, when the duct 7 protrudes both to the indoor and outdoor sides, the indoor end 7b of the duct 7 is positioned on the indoor exterior side of the formwork 3, and the outdoor end 7a of the duct 7 is positioned on the outdoor exterior side of the formwork 3.

[0055] In the opening-closing step S4, the duct 7 is passed through the duct hole 11, and the outer periphery 10a of the duct panel 10 is liquid-tightly fixed to the formwork opening 6 to close the formwork opening 6.

[0056] As shown in Figure 1, when the duct 7 is to protrude only to the interior side, the interior side of the duct 7 is passed through the duct hole 11 of the duct panel 10, and the outer periphery 10a of the duct panel 10 is liquid-tightly fixed to the formwork opening 6 to close the formwork opening 6. At this time, pay attention to the top and bottom of the duct panel 10, ensuring that the center of the duct hole 11 is positioned above the center of the duct panel 10. Also, ensure that the fitting portion 10e of the duct panel 10 fits into the formwork opening 6, the sealing surface 10f is in close contact with the outer surface of the formwork, and the back surface 10b is flush with the inner surface of the formwork. Furthermore, ensure that the recessed surface 10d of the duct panel 10 (around the duct hole 11) is positioned closer to the formwork than the end face of the duct 7.

[0057] Unlike Figure 1, when the duct 7 is to protrude on both the indoor and outdoor sides, the duct 7 is passed through the duct holes 11 of a pair of duct panels 10 on the indoor and outdoor sides, and the outer periphery 10a of the duct panel 10 (i.e., the fitting portion 10e and the sealing surface 10f) is liquid-tightly fixed to the formwork openings 6 on the indoor and outdoor sides to close the formwork openings 6.

[0058] In panel fixing step S5, the duct panel 10 is fixed to the formwork 3. In this case, as shown in Figures 1 and 2, multiple single pipes 16 are positioned in contact with the front surface of the duct holding plate 14, and the formwork 3 is tightened by the pipe holding member 18 via the single pipes 16, the duct holding plate 14, and the duct panel 10. Furthermore, if the duct panel 10 can be firmly fixed to the formwork opening 6 in the opening closing step S4, the panel fixing step S5 can be substantially omitted.

[0059] In concrete pouring step S6, concrete 5 is poured inside the formwork 3. Step S6 can be carried out as a normal concrete pouring operation after the formwork construction T1 and the rebar work T2.

[0060] In the formwork removal step S7, after the concrete 5 has hardened, the formwork 3, single pipe 16, duct holding plate 14, duct panel 10, and duct support material 12 are removed, completing the beam 1 in which the duct 7 is embedded by passing it through the reinforced concrete beam 1.

[0061] According to the duct embedding method of the present invention described above, steps S2 to S6 of opening setting, duct positioning, opening sealing, panel fixing, and concrete pouring are performed at a different time than the rebar work in which the beam reinforcement 2 is assembled and dropped into the formwork 3. Therefore, it is possible to eliminate the need for concurrent work and to easily carry out the work independently without interfering with the rebar work, thereby increasing work efficiency.

[0062] Furthermore, in the duct positioning step S3, the outer end face of the duct 7 is positioned outside the formwork 3, and in the concrete pouring step S6, concrete 5 is poured inside the formwork 3. This construction method allows a hollow cylindrical duct 7 to be embedded through a reinforced concrete beam 1 without creating an opening in the beam 1 larger than the outer diameter of the duct 7, thereby suppressing a decrease in the strength of the reinforced concrete beam.

[0063] Furthermore, in the opening-closing step S4, the indoor side of the duct 7 is passed through the duct hole 11, and the outer periphery 10a of the duct panel 10 is liquid-tightly fixed to the formwork opening 6 to close the formwork opening 6, thereby reliably reducing slag leakage from the formwork opening 6.

[0064] Furthermore, since the outer periphery 10a of the duct panel 10 is spaced apart from the duct hole 11 through which the duct 7 passes, the formwork 3 can be easily removed after the concrete 5 has hardened without damaging the inner or outer surfaces of the duct.

[0065] Furthermore, in the duct positioning step S3, the outer end face of the duct 7 is positioned outside the formwork 3, which significantly reduces slag leakage into the duct.

[0066] The scope of the present invention is not limited to the embodiments described above, but is indicated by the claims, and includes all modifications within the meaning and scope of equivalence to the claims. [Explanation of Symbols]

[0067] e Eccentricity, O1 centroid, O2 center, 1 beam, 2 beam reinforcement, 3 formwork, 3a beam bottom weir plate, 3b slab bottom weir plate, 3c inner weir plate, 3d outer weir plate, 4. Reinforcement plate, 5. Concrete, 6. Formwork opening, 7. Duct (buried duct), 7a External end, 7b Indoor end, 8 Indoor duct, 9 Nipple, 9a Fitting part, 9b Protruding part, 10 Duct panel, 10a Outer periphery, 10b Inner surface of the formwork, 10c Front surface of the outer edge, 10d Recessed surface, 10e Fitting part, 10f sealing surface, 10g tapered surface, 11 duct hole, 11a inner surface, 12 Duct support material, 12a Cylindrical part, 12b Flange part, 12c Nail hole, 14 Duct holding plate, 16 Single pipe, 18 Pipe holding member, 20 Drill screws, 21a, 21b Non-flammable butyl tape, 22a, 22b Aluminum tape, 24 End protector, 24a Outer surface, 25 Body, 25a, 25b End, 25c Through hole, 26 Removal tool

Claims

1. This duct burial method involves embedding a hollow cylindrical duct by passing it through a reinforced concrete beam. A panel preparation step involves preparing a duct panel having a duct hole through which the duct passes and an outer peripheral portion located at a distance from the inner surface of the duct hole. An opening setting step is to provide a formwork opening on the side of the formwork surrounding the outer surface of the beam, excluding the upper surface of the beam reinforcement that constitutes the beam, in which the outer surface of the duct panel can be liquid-tightly fixed. A duct positioning step involves positioning the outer end face of the duct outside the formwork, The opening closing step involves passing the duct through the duct hole and fixing the outer periphery of the duct panel to the formwork opening in a liquid-tight manner to close the formwork opening. A panel fixing step for fixing the duct panel to the formwork, A duct embedding method comprising a concrete pouring step for pouring concrete inside the formwork.

2. In the opening setting step, the formwork opening is provided on the indoor side surface of the formwork, and a duct support member that supports the outer end of the duct is fixed to the outer inner surface of the formwork. In the duct positioning step, the outer end of the duct is fixed to the duct support material, and the indoor end of the duct is positioned on the indoor outside of the formwork. The duct burying method according to claim 1, wherein in the opening sealing step, the indoor side of the duct is passed through the duct hole of the duct panel, and the outer periphery of the duct panel is liquid-tightly fixed to the formwork opening to seal the formwork opening.

3. In the opening setting step, the formwork opening is provided on the indoor side and the outdoor side of the formwork. In the duct positioning step, the indoor end of the duct is positioned on the indoor outside of the formwork, and the outer end of the duct is positioned on the outer outside of the formwork. The duct burying method according to claim 1, wherein in the opening sealing step, the duct is passed through the duct holes of a pair of duct panels on the indoor and outdoor sides, and the outer periphery of the duct panels is liquid-tightly fixed to the formwork openings on the indoor and outdoor sides to seal the formwork openings.

4. The duct embedding method according to claim 1, wherein the shape of the formwork opening is a polygon composed of straight lines.

5. A duct panel used in the duct burial method of claim 1, It is made of an elastic material that is not easily adhered to concrete and is flexible. When fixed to the formwork opening, it has a formwork-side inner surface that is flush with the inner surface of the formwork, The duct panel is characterized in that the duct hole has an inner diameter that contacts or is close to the outer surface of the duct.

6. The duct panel according to claim 5, wherein the fitting portion of the outer periphery to the formwork opening is a polygon composed of straight lines.

7. A sealing surface is provided along the entire circumference of the fitting portion and, when fixed to the formwork opening, is flush with the outer surface of the formwork, The duct panel according to claim 6, further comprising a tapered surface provided between the outer edge of the outer periphery and the sealing surface, and inclined in a direction away from the sealing surface.

8. The duct panel according to claim 6, wherein the center of the duct hole is located eccentrically above the centroid of the fitting portion.

9. The front surface of the outer periphery has a certain thickness from the inner surface of the formwork, The duct panel according to claim 5, wherein the inner side of the outer periphery has a recessed surface that is recessed from the outer periphery toward the formwork side and surrounds the duct hole.

10. An end protector for use in the duct burial method of claim 1, It is inserted inside the end of the duct, its outer surface extends circumferentially along the inner surface of the end, and applies radially outward pressure to the end by elastic force, In a state where no external force is applied, the outer surface extends circumferentially along an outer diameter larger than the inner diameter of the duct, and the body has both ends that are positioned opposite each other in the circumferential direction. An end protector in which, when the body is inserted along the inner surface of the end of the duct, one end and the other end of the body are close together or overlap radially, and the restoring force of the body applies radially outward pressure to the end.

11. The end protector according to claim 10, wherein a portion of a hollow cylindrical elastic material having an outer diameter larger than the inner diameter of the end is cut and separated in the axial direction of the duct.

12. The body portion has through holes that penetrate radially or axially, Furthermore, the end protector according to claim 11, further comprising a removal tool fixed through the through hole.

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