JPH09322375A - Concrete box for branch and connection of underground wiring - Google Patents

Abstract

PROBLEM TO BE SOLVED: To maintain the strength of the wall of a concrete box for the branches and connections of underground wirings even when disposing in the wall with a high density wire-pipe connecting portions having such shapes as bell-mouths, by forming at least one portion of the end walls of both the ends of the concrete box out of wall plates, and by so attaching in that time each wall plate to a box main body that the recessed sides of its connecting regions face the inside of the box main body. SOLUTION: As a box 10, forming a wire-pipe connecting portion 17a or 17b in a wall plate 31a or 31b, the wall plates 31a, 31b are combined with a main body 30 to provide such knockout type wire-pipe connecting portions 17a, 17b in the box 10 that they are respectively tapered from the side of an inner surface 11a of the box 10 to the side of its outer surface 11b and they are respectively recessed from the side of its inner surface 11a, leaving respective thin wall portions on the side of its outer surface 11b. Further, by molding the wall plates 31a, 31b independently of the main body 30, without improving or creating newly the molding flask for molding the main body 30, a concrete box for the branches and connections of underground wirings can be supplied cheaply in a short time to the adapted positions to the field requiring the different sizes and dispositions of embedded wire pipes from each other.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a branching / connecting concrete for underground wiring, which is buried along an underground wiring route when performing underground wiring work such as an electric wire common groove so that a cable can be branched or connected inside. It is about the box made.

[0002]

2. Description of the Related Art A large number of electric wire joint grooves are being constructed along roads to lay a large number of cables such as power cables, communication cables, and optical fiber cables. Conventionally, the electric wire common groove is entirely formed by a U-shaped concrete groove. In recent years, an underground wiring route 2 has been constructed along a road 1 as shown in Fig. 8 so that an electric wire common groove capable of laying a larger amount of cables can be constructed at a low cost, and concrete can be laid at locations where cable branching or connection is required. A policy to secure a work space by providing a box 10 made of steel has been proposed. Since various kinds of cables such as electric power and communication for homes, offices, factories, etc. are installed in the electric wire common groove, the box 10 to be buried in the branch or the connection part also needs to be of a very large size. Become.
Therefore, unlike the conventional handhole having a substantially square bottom surface, adoption of a box having a substantially rectangular bottom surface extending along the underground wiring route 2 is being considered.

[0003]

FIG. 9 is a cross-sectional view showing how a plurality of embedded conduits 3 forming an underground wiring route 2 are connected to a concrete box 10 forming a branch or a connecting portion. is there. The concrete box 10 is buried in the ground 9, and the buried conduit 3 is connected to the end wall 11 of the box 10 so that the space 7 inside the box 10 can be used for branching and connecting cables. It has become. For this reason, the upper part of the box 10 is constituted by the lid 8 which can be opened and closed, and is put inside the box 10. In the underground wiring route 2, a plurality of buried conduits 3 for power cables or communication cables are stacked in the horizontal direction and the vertical direction, and the cable is pulled out to the underground wiring route 2 in order to construct a common electric wire groove. Therefore, it is necessary to connect a plurality of buried conduit tubes 3 to the end wall 11 of the concrete box 10. For this reason, it is necessary to provide many through holes in the end wall 11 made of concrete. Further, at a place where the end wall 11 and the buried electric conduit 3 are connected, a protection tube 4 in which the inner surface 11a side of the end wall 11 is widened in a bell mouth shape is embedded. Therefore, it is necessary to prepare a through hole having a diameter larger than the outer diameter of the buried conduit 3 in the end wall 11, and after the buried conduit 3 is attached, a caulking material may be injected into the through hole. There is a need to do. Therefore, it takes a lot of time and labor to connect the buried conduit tube 3 to the end wall 11 of the box 10 on site.

Therefore, it is considered that when the concrete box 10 is precast in a factory, a through hole for inserting the buried conduit tube 3 is previously formed in the end wall 11. The through hole of the end wall 11 can be provided, for example, by the method shown in FIGS. 10 and 11. The concrete box 10 with a bottom can be molded by pouring concrete into the space between the outer mold 22 and the inner mold 23 installed on the base 21. At this time, a sleeve 29 having a truncated cone shape reaching the inner mold 23 is attached to the detachable outer mold 22 so that the end wall 1
The through hole 19 can be formed in the first. Then, after the concrete poured between the inner mold 23 and the outer mold 22 is solidified, the sleeve 29 is disassembled outward together with the outer mold 22, and the inner mold 23 is vertically moved from the concrete box 10. The box 10 can be demolded by removing it. Since the sleeve 29 is detached to the outer side of the end wall 11 together with the outer mold 22, a sleeve 29 having a tapered shape that narrows toward the inner mold 23 is used. Therefore, the through hole 19 formed by the above method has a larger hole diameter opened on the outer surface 11b as compared with the hole diameter opened on the inner surface 11a.

As described above, by providing the outer sleeve 22 with the tapered sleeve 29, the through hole 19 is formed in the end wall 11.
The open concrete box 10 can be molded. And such a concrete box 1
By using 0, the electric wire common groove can be constructed in a short period of time. However, some problems will be pointed out in consideration of the situation in which many buried conduits will be connected to the end wall 11 of the box 10 in the future, corresponding to the common groove of the wires for processing a larger amount of cables. One is that it becomes difficult to maintain the strength of the end wall 11 when the pitch of the through holes 19 becomes narrow. As shown in FIG. 12 (a), since the bell mouth 4 a portion of the protective tube 4 is installed on the inner surface 11 a side of the end wall 11, the inner surface 11 of the through hole 19 is
The diameter on the side of a needs to be formed to be large according to the diameter of the bell mouth 4a. In the above manufacturing method, the through hole 1
9 has a larger diameter on the outer surface 11b. Therefore, if the spacing between the bell mouths 4a is narrowed, even though the pitch of the bell mouths 4a appearing on the inner surface 11a is sufficient, the through holes 19
It is conceivable that the openings 19b of the outer surface 11b are overlapped with each other. When the openings 19b are arranged so as to overlap with each other, the wall thickness of the portion where the through holes 19 are adjacent to each other becomes thin and the strength is reduced. For this reason, there is a possibility that the strength during manufacturing, especially against the load during demolding, may be insufficient, or the strength during burying may be insufficient.

On the other hand, if the openings 19b on the outside of the through holes 19 are arranged so as not to overlap with each other, the arrangement density of the bell mouths 4a is lowered, so that a large number of embedded conduits cannot be connected in a small box and the size of the box is reduced. Need to be bigger. Therefore, the box becomes heavy and expensive, and the on-site construction becomes difficult. Furthermore, it may be difficult to prefab the factory if the box becomes large.

Further, as shown in FIG. 12 (b), instead of providing the through hole 19, the wall thickness of that portion is made thin so that the knock-out type conduit tube connecting portion 18 can be easily penetrated on site. It is considered to be provided. The knock-out type conduit tube connecting portion 18 has a thinned portion 18 of the end wall 11 only at the site where the conduit tube is actually connected.
The wall 18a can be left at a place where a is demolished and penetrated and the conduit is not connected. Therefore, a plurality of knock-out type connecting portions 18 are formed at the prefabricated stage of the factory at a place where the buried conduit is to be laid, and it is decided at the site whether or not to actually connect the buried conduit. It becomes possible to do. Therefore, by adopting the knockout method, the concrete box 10 can be prospectively produced, and the concrete box 10 can be supplied at low cost in a short period of time.

The concrete box 10 having the knock-out type conduit tube connecting portion 18 can be manufactured by a manufacturing method similar to the above-described manufacturing method, and the outer mold is provided with a sleeve that does not reach the inner mold. You can leave it. By using this method, as shown in FIG. 12B, it is possible to form a knock-out type conduit tube connecting portion 18 in which the end wall 11 is thin on the inner surface 11a side. Then, in the field, by breaking the thin wall portion 18a of the connecting portion 18 on site, a through hole for connecting the conduit can be easily provided. However, since the knock-out type connecting portion 18 forms a through hole with a hammer or the like in the field, the circumference of the through hole is not aligned and a large hole is often opened. The side of the inner surface 11a of the box 10 is
Since the surface will be used for cables to be taken in and out, it is necessary to finish the wall surface so as to have a smooth surface with few irregularities so as not to damage the cables and workers. Therefore,
When the knock-out type connecting portion 18 is adopted, the inner surface 11
It is necessary to carefully perform the work between the through hole on the side of a and the bell mouth 4a at the work site, which reduces the time and effort required at the work site.

Therefore, in view of these problems, the present invention provides a concrete box for branching / connecting that can maintain the strength of the wall even if the connecting portions of the conduits having the shape of a bell mouth are densely arranged. It is intended to be provided. Further, even when a knockout type connection portion is provided, the work required for repair at the site is small, and it is an object of the present invention to provide a concrete box for branching and connecting which can construct a common wire groove in a short period of time. I am trying.

[0010]

Therefore, in the present invention, the connection area of the conduit is provided with a knock-out type connection area which is recessed from the inside to the outside of the box. Further, in the connection area of the conduit, a tapered connection hole is provided which becomes thinner from the inside of the box to the outside thereof. By providing such a connecting region, the opening appearing on the outer surface of the box becomes smaller than the opening appearing on the inner surface, so that a through-hole having a shape fitting the protective tube whose end is widened like a bell mouth can be formed.
Furthermore, since the space between the openings is wider on the outer surface than on the inner surface, the arrangement density of the through holes can be increased without lowering the strength of the outer wall of the box. Also in the knockout type connection area, the wall is left on the outer surface side and the inside of the box is already processed and finished in the shape of a through hole, so the work of finishing after installing the protection tube is omitted. be able to.

However, a knock-out type connection region in which the inner side is recessed and a wall is left on the outer side, and a tapered through hole narrowed from the inner side to the outer side cannot be manufactured by attaching a sleeve to the outer form. On the other hand, if the sleeve is attached to the inner mold, the sleeve interferes with the box at the time of demolding, so that it cannot be demolded. It is possible to employ a method of rotating the box for each inner mold or lifting the box together with the inner mold and then disassembling the inner mold to remove the mold, but it takes a lot of labor and time. Furthermore, since it requires a dangerous process of turning heavy objects including the formwork or lifting them up, it is difficult to use in practice. It is also possible to adopt a disposable type sleeve made of an inexpensive material such as Styrofoam, but since it is necessary to fix the sleeve to the inner formwork, there is a risk that the fixed part will interfere during demolding, and It is difficult to firmly fix the sleeve against the load when pouring concrete. In particular, when a knockout type connection area is provided, a sleeve of styrofoam or the like cannot be sandwiched and fixed between the inner mold and the outer mold, so a disposable sleeve cannot be adopted. Further, when the sleeve is repeatedly attached to and detached from the inner mold to provide connection regions of different sizes and arrangements, the iron plate forming the inner mold is damaged and distorted, which makes it difficult to remove the mold. Since the formwork is very expensive, it is difficult to create a new formwork each time the placement or size of the connection area changes.

Therefore, in the present invention, a concrete box for branching and connection for underground wiring, which is buried along the underground wiring route and secures a space for wiring work inside, is extended substantially along the underground wiring route. At least a part of the end walls of both ends of the box, using a concrete main body having a U-shaped cross section and a concrete wall plate having at least one knock-out type connection region in which at least one side is recessed Is constituted by a wall plate, and at that time, the wall plate is attached to the main body so that the concave side of the connection region faces the inside of the main body. In this way, by molding the knockout connection area separately from the main body, it is possible to provide a knockout connection area in which the inside of the box is recessed. Also, using a concrete wall plate having a connection region in which at least one through hole is narrowed from one surface toward the other surface, the thin side of the through hole faces the outside of the main body. By attaching to the main body, it becomes possible to provide a through hole formed in a thin taper shape from the inside to the outside.

When the end walls are integrally formed on both sides of the main body, a hole for fitting the wall plate may be formed in a part of the end walls, or the wall plates are attached to both sides of the main body. You may comprise an end wall.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows an outline of a concrete box 10 for branching and connecting underground wiring (underground wiring or buried wiring) according to the present invention. The concrete box 10 of this example is a box for constructing the branching portion and the connecting portion of the electric wire common groove as described above, and the installation location and the burying method therefor are common to the above-mentioned box, and therefore will be described below. Is omitted. In the concrete box 10 of this example, two connection regions 12a and 12b capable of connecting to the buried conduit are provided on the end walls 11 at both ends. Respective connection areas 12a and 12
A plurality of knockout type conduit connection parts 17 are formed in b, and the conduit connection parts 17a of the connection region 12a are formed.
Has a large-diameter frusto-conical shape and can be connected to a buried conduit for laying a power cable. The conduit connection portion 17b of the connection region 12b has a truncated cone shape with a small diameter so that a buried conduit for laying a communication cable including an optical fiber cable can be connected. The conduit connection portions 17a and 17b provided in the box 10 of the present example have a large diameter on the side facing the inner surface 11a of the end wall 11 and a small diameter on the outer surface 11b side. It is formed in a thin taper shape toward. Furthermore, the conduit connection part 1 of this example
7 is a knockout method, and the thinned wall portion 17
c is formed on the outer surface 11b side of the end wall 11. Further, the side wall 13 of the concrete box 10 of this example is provided with a plurality of knock-out type branch connection holes 15 so that a conduit for laying a branched cable can be connected.

FIG. 2 shows a concrete box 1 of this example.
0 is assembled in the factory. Also, FIG.
The structure of the concrete box 10 of this example is shown in FIG. As shown in FIG. 2, the concrete box 10 of this example includes a main body 30 and an end wall 1 of the main body 30.
It is mainly assembled by two sets of wall plates 31a and 31b which are fitted into the plurality of opening spaces 32 provided in 1. The main body 30 is formed in the shape of a concrete box 10 for branch connection, and includes a set of end walls 11
The two sets of the side wall 13 and the bottom wall 14 are integrally formed. Then, substantially rectangular opening spaces 32a and 32b are formed at locations corresponding to the connection regions 12a and 12b of the respective end walls 11. The four surfaces 32c of the opening spaces 32a and 32b are formed in a tapered shape from the outer surface 11b toward the inner surface 11a, as shown in FIG. Therefore, this opening space 3
2a and 32b can be easily formed by the manufacturing method described above with reference to FIGS.

On the other hand, each of the wall plates 31a and 31b is a concrete wall plate prefabricated to a size corresponding to the opening spaces 32a and 32b.
One surface 31c is formed in a tapered shape so as to match the four surfaces 32c of the through hole. Furthermore, a plurality of conduit tube connection portions 17a and 17b are formed on the respective wall plates 31a and 31b, and the surface 31d on the side where the surface 31c is tapered becomes an opening, and the surface 3 on the opposite side thereof is formed.
1e is a portion 17c where the wall remains thin. Therefore, the wall plates 31a and 31b are connected to the opening space 32a.
And 32b, respectively, the connecting areas 12a and 12b of the conduit are tapered toward the outer surface 11b from the inner surface 11a side of the end wall.
Knockout type conduit tube connection portions 17a and 17b having thin walls are formed on the side of b.

FIG. 4 shows how the wall plates 31a and 31b of this example are molded. Wall plates 31a and 3 of this example
1b can be prefabricated using a formwork. The outer form 41 having a tapered shape is assembled on the base 40 to determine the outer shape of the wall plate 31. Then, a conical trapezoidal sleeve 29 having a narrow tip is fixed to a predetermined position of the pedestal 40 by a bolt or the like, and concrete 45 is poured into the inside of the outer formwork 41 so that the wall plates 31 a and 31.
b is molded. After the concrete 45 has solidified, the outer mold 41 is disassembled to the outside, and the wall plate 31a or 31b and the base 40 are divided into upper and lower parts, so that the mold can be removed. The method of molding the wall plate 31 is not limited to this.
For example, it is possible to turn the outer mold 41 upside down to provide a mold that faces the base 40 and defines the inner surface of the wall plate, and attach the sleeve 29 to the mold that defines the inner surface.

As in the box 10 of this example, the conduit connection portion 17a or 17b is formed on the wall plate 31a or 31b, and by combining the wall plate 31a and 31b with the main body 30, from the inner surface 11a side of the box 10. The knock-out type conduit tube connecting portions 17a and 1 which are tapered toward the outer surface 11b side and are further recessed from the inner surface 11a side to leave a thin wall portion on the outer surface 11b side.
7b can be provided in the box 10. Therefore, by destroying the thin wall portion 17c on the outer surface 11b side, a thin tapered through hole can be easily formed on the site from the inner surface 11a side to the outer surface 11b side.
Of course, by using the sleeve 29 that penetrates the wall plate when molding the wall plate 31a or 31b,
Box 10 having a thin tapered through hole from the inner surface 11a to the outer surface 11b when shipped from the factory
It is also possible to provide

The wall plates 31a and 31b can be molded using the molds 40 and 41 that are inexpensive and can be easily manufactured as described above, and can be easily demolded. Therefore, even if the size or position of the conduit connecting portion 17 is changed, it can be easily dealt with. It is inexpensive to manufacture the mold 40 in which the size and the position of the conduit connection portion 17 are different, and even if the mold is processed to cause some distortion, the influence on the demolding work is small. Further, by molding the wall plates 31a and 31b separately from the main body 30 as in the present example, the size and arrangement of the buried conduits are different without modifying the mold for molding the main body 30 or newly creating it. It becomes possible to supply a box for branching / connection with a knockout type conduit connection part at a position suitable for the site at low cost in a short period of time.

FIG. 5 shows the inner surface 11a to the outer surface 11b of this embodiment.
On the side of the outer wall 11b, and the thin wall 1 on the side of the outer surface 11b.
In the knockout type conduit connection part 17 leaving 7c,
A state in which a bellmouth-shaped protection tube 4 is installed is shown.
When installing the protection tube 4 in the field, the conduit tube connection part 1
The wall portion 17c of No. 7 is broken by a hammer or the like to form a through hole. Then, the bellmouth-shaped protection tube 4 is installed in this through hole so that the widened side 4a faces the inner surface 11a. In the conduit tube connection portion 17 of this example, the diameter of the inner surface 11a side is larger than the diameter of the outer surface 11b side along the shape of the bellmouth-shaped protection tube 4. Therefore, even if the widened portions 4a are arranged at a narrow pitch on the inner surface 11a, the conduit connecting portion 1 is provided on the outer surface 11b side.
Since the interval of 7 can be secured, sufficient strength can be provided. That is, on the outer surface 11b side, the distance between the conduit connection portions 17 becomes wider than that on the inner surface 11a, and the concrete in that portion becomes thicker, so that it is less likely to break. Therefore, even if the conduit tube connecting portions 17 are densely arranged, the strength at the time of releasing from the mold and the burying strength will not be an obstacle in manufacturing the box 10. Therefore, it is possible to provide a large number of conduit connection portions on the end wall, and it is possible to provide a small-sized concrete box for branching / connecting that can process a large amount of cables.

Further, as shown in FIG. 5, the conduit connection portion 17 of the present embodiment has the thin wall 17c on the outer surface 11b side, and therefore the outer surface 11b is processed and repaired on site. Therefore, the inner surface 11a side can be factory processed according to the outer diameter of the widened portion 4a of the protection tube. Therefore, the inner surface of the box 10, which needs to be finished in consideration of interference with the cable, requires almost no repair on site. On the other hand, the conduit connection portion 17 of the present example needs to be caulked by using the mortar 16 or the like because the outer surface 11b side is open, but since this outer surface 11b is a surface to be buried in the soil, it does not take much trouble. Work can be done in a short time without hanging up.

In FIG. 6, the water stop ring 2 is attached to the conduit connecting portion 17.
4b shows how to set up the bell mouth 4 using 4b. The bell mouth 4 is inserted from the inner surface 11a into the penetrating conduit connecting portion 17, and a water blocking ring 24b made of an elastic band such as rubber having a V-shaped cross section is formed between the bell mouth 4 and the conduit connecting portion 17. insert. Further, a cap 2 having a cylindrical flange 26a formed on the bell mouth 4 or the embedded conduit tube 3 mounted on the bell mouth 4 from the outer surface 11b.
6 is attached with an adhesive or the like. The water stop ring 24b having a substantially V-shaped cross section is used to connect the bell mouth 4 and the conduit tube connecting portion 1
By inserting it into the gap of No. 7, it is possible to surely stop the water even if the width of the gap is slightly changed, so that it is suitable for the conduit tube connecting portion 17 in which the opening area changes in a tapered shape like this example. There is. Further, by attaching the cap 26 to the bell mouth 4 or the buried conduit tube 3, the water stop ring 24b
Can be prevented from coming off. The method of stopping water using such an elastic band has a high water-stopping effect and is also excellent in earthquake resistance, and can improve the reliability of underground wiring laying work. It is also possible to insert the water stop ring 24b into the gap between the bell mouth 4 and the conduit tube connecting portion 17 and further fill the mortar to further enhance the water stop effect. By adopting the method using such a ring or packing,
It is possible to carry out water stoppage work on site in a shorter period of time. Therefore, it is possible to shorten the period in which passage is blocked by the underground wiring work, and it is possible to proceed with the underground wiring work with confidence even in an area with a lot of traffic and passersby such as a shopping district.

In FIG. 7, as a different example of the present invention, the conduit connection area 1 is provided at both ends of the main body 30 having a U-shaped cross section.
It shows an example in which the wall box 31 on which 2a and 12b are molded is attached to manufacture the branch / connecting concrete box 10.

In the main body 30 constituting the concrete box 10 of this example, the side wall 13 and the bottom wall 14 are integrally formed in a U shape, and a plurality of inserts 50 are embedded in the surfaces 13a at both ends of the side wall 13. There is. Further, the wall plate 31 is a concrete plate formed in a plate shape having a size that covers the side surface of the main body 30, and the conduit tube connection regions 12a and 12b thereof are recessed from one wall surface to the other wall surface side. A plurality of knock-out type conduit tube connection portions 17a and 17b leaving a thin wall portion 17c are formed in respective regions. Further, the bolts 3 are attached to the periphery 33 of the wall plate 31.
Holes 34 are provided for installing 5 and the wall plate 31 can be attached to the end surface of the U-shaped main body 30 using these bolts 35. Therefore, the wall plate 31
Is the concave portion of the conduit connection portions 17a and 17b
Box 10 by mounting towards the inside of 0
Conduit portions 17a and 17b recessed from the inner side of the
A concrete box for branching and connecting can be formed.

The wall plate 31 as in this example can be molded using the same simple mold as that described above. Further, since the conduit connection portions 17a and 17b can be formed in a taper shape from their open side toward the thin wall portion 17c, a sufficient distance can be obtained even when the bellmouth-shaped protection tubes are arranged at a narrow pitch. With this, it becomes possible to form the conduit tube connection portions 17a and 17b. Therefore, as in this example, by assembling the wall plate 31 to the U-shaped main body 30, as in the above case, a large number of conduits can be connected and processed, and furthermore, for branching / connection for easy on-site construction. Of concrete boxes can be provided. Further, one side wall 13 of this example has an elliptical knock hole 15 for branch connection.
And a knock hole 25 for installing a transformer is provided on the other side. As described above, the present invention can be applied regardless of the configuration of the main body 30.

In the above example, the description is based on the box in which two types of conduit connecting portions having different diameters are formed, but it goes without saying that even a box in which one type of conduit connecting portion is provided is used. It is also possible to provide good or three or more types of conduit connecting portions having different diameters. Furthermore, although the shape of the conduit connection portion has been described as an example of a truncated cone in the above, the shape is not limited to this, and the cross-sectional shape may be a quadrangular shape or another polygonal shape, and further various cross-sections such as an ellipse. Of course, the provided conduit connection portion may be used.

Further, in this example, the description is made based on the box in which a plurality of conduit connection portions corresponding to the installed conduit are formed in a substantially one-to-one relationship. However, a plurality of conduits are combined into one conduit. It is of course possible to form an elliptical, elliptical or almost rectangular conduit connection so that it can be laid using the connection. A concrete box provided with such a collective conduit connection part is also included in the scope of the present invention. By applying the present invention, one or a plurality of collective conduit connection parts or a collective box Concrete conduit connections and individual conduit connections can be densely arranged, making it possible to effectively utilize the limited area of the end wall of a concrete box to connect multiple conduits. Can provide boxes. Further, the present invention can be applied not only to a concrete box that requires densely arranging the conduit connections, but also to a concrete box where densely arranging the conduit connections is not so required. When applied to various types of conduits or sites where the placement of the concrete box changes depending on the situation at the site, etc., a knockout type wire is used to accommodate such changes in the penetration point. It is possible to flexibly arrange the pipe connection portion. Furthermore, by applying the present invention, the knockout type conduit connection part can be clearly seen from the inside of the box and the through hole can be easily opened. There is also the merit that opening work is easy and can be done in a short time.

Further, the conduit connection portion described above is not limited to a conduit for accommodating an electric wire, an optical fiber cable or the like, and a directly buried cable or another pipe can be connected. Even when such a cable or other piping is installed, the above effects can be obtained. Further, in the above example, the unit formed in a box shape is described as an example, but a unit in which an end wall is provided only at one end may be combined to form a box shape. Of course, it is also possible to combine the letter-shaped units in a box shape on site.

[0029]

As described above, according to the present invention, a concrete box for branching and connecting underground wiring, which is buried along the underground wiring route and secures a space for wiring work inside, is provided in the main body and the box. A wall plate to be attached is used for the construction, and at least one side of the wall plate is a knock-out type conduit tube connection portion that is recessed, or at least one portion is tapered from one surface to the other surface. Two through holes are formed to form a connection area. Then, this wall plate is attached to the body so that the recessed side of the knockout type conduit connection part or the one with the larger diameter of the through hole is inside the box, and the connection part recessed from the inside of the box, or the box A through hole for connection is formed that is tapered from the inside to the outside. Therefore, the strength of the end wall of the box can be sufficiently secured even if the conduit connection portions are arranged densely, and further, a concrete box for branching / connection can be provided with little rework on site. In particular, when using a protective tube in which the widened bellmouth-shaped part is exposed in the box, it is possible to prepare a connection part with a shape substantially along the protection tube, so it is possible to improve the arrangement density of conduit connection parts, We can provide a concrete box for branching and connecting that can finish the inner surface in a short time. Therefore, the concrete box for branching and connection of the present invention is small and can take in and process a large amount of cables, and it is possible to construct an electric wire common groove capable of laying a large number of various types of cables at low cost in a short period of time. Become.

[Brief description of drawings]

FIG. 1 is a perspective view of a concrete box for branching and connecting according to an embodiment of the present invention.

FIG. 2 is a developed perspective view showing a state where the concrete box shown in FIG. 1 is assembled with a main body and a wall plate.

FIG. 3 is a cross-sectional view showing the configuration of the concrete box shown in FIG.

FIG. 4 is a cross-sectional view showing how the wall plate shown in FIG. 2 is molded.

5 is a cross-sectional view showing a state where a bellmouth-shaped protection tube is installed using a knockout type conduit tube connection portion provided in the concrete box shown in FIG. 1. FIG.

FIG. 6 is a cross-sectional view showing a state in which a bell mouth-shaped protection tube is installed by a different method using the knockout type conduit connection portion provided in the concrete box shown in FIG.

FIG. 7 is a perspective view showing an example of a different concrete box according to the embodiment of the present invention.

FIG. 8 is a plan view showing an electric wire common groove constructed by using a buried conduit and a branch / connection box.

FIG. 9 is an example showing how a conduit is connected to a branch / connection box.

FIG. 10 is a view showing how the branching / connecting box shown in FIG. 9 is integrally molded with concrete.

FIG. 11 is a diagram showing how the box shown in FIG. 10 is removed from the mold.

FIG. 12 is a diagram showing a state in which a bellmouth-shaped protective tube is installed in a through hole for connecting a conduit tube and a connection portion of a knockout system of the concrete box shown in FIG.

[Explanation of symbols]

 10 ・ ・ Concrete box for branching / connecting 11 ・ ・ End wall of box 12 ・ ・ Conduit connection area 13 ・ ・ Sidewall 14 ・ ・ Bottom wall 15 ・ ・ Connecting area of branched conduit 17 ・ ・ Conduit connection Part 30 ··· Box main body 31 ·· Wall plate 32 ·· Opening for fitting the wall plate

Claims (4)

[Claims] 1. A branch for underground wiring that is buried along an underground wiring route and can secure a space for wiring work inside.
A concrete box for connection, which comprises a concrete body extending along the underground wiring path and having a substantially U-shaped cross section, and at least one knockout type connection area in which at least one side is recessed. At least a part of the end walls of both ends of the branching / connecting concrete box for underground wiring is constituted by the wall plate, and the wall plate is a recess of the connection region. A branch / connecting concrete box for underground wiring, characterized in that the other side is attached to the main body so as to face the inside of the main body. 2. A branch for underground wiring that is buried along an underground wiring route and can secure a space for wiring work inside.
A concrete box for connection, which is made of concrete and has a substantially U-shaped cross section that extends along the underground wiring path, and at least one through hole that is tapered from one surface to the other surface. And a wallboard made of concrete having a connection area formed, wherein at least a part of both end walls of the concrete box for branching and connecting the underground wiring is constituted by the wallboard, The wall board is attached to the main body so that the side of the through hole that is narrowed faces the outside of the main body. A concrete box for branching and connecting underground wiring. 3. The end wall according to claim 1 or 2, wherein the end walls are integrally formed on both sides of the main body, and a hole for fitting the wall plate is formed in a part of the end walls. A characteristic concrete box for branching and connecting underground wiring. 4. The concrete for branching / connecting for underground wiring according to claim 1 or 2, wherein the end wall is constituted by the wall plate, and the wall plates are attached to both sides of the main body. Made box.