JP2005124348A - Installation method for cable and fire resistant bell block - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an installation method for cables for installing power/communication cables underground using a protection duct for wiring, and a fire resistant bell block for use in this method. <P>SOLUTION: The fire resistant bell block 2 is formed mainly of cement containing substantially no organic substances and is provided with a joint made of uninflammable, flame-retardant, or self-extinguishing resin on the side of its face where the outer face of a manhole is formed. The protection duct 4 for wiring is fit into the joint 10 of this bell block. A cable 5 installed in the protection duct 4 for wiring is inserted into the through hole 3 in the bell block 2, and passed through the internal vacancy in a cylindrical fire resistant plug 6. The plug is installed on the side face of the bell block 2 where the inner face of the manhole is formed, is formed of an uninflammable, flame-retardant, or self-extinguishing material, and has a flange at its end. Thus, the cable is guided into the manhole. Further, the internal vacancy in the fire resistant plug 6 is filled with an uninflammable, flame-retardant, or self-extinguishing material 11. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

The present invention relates to a cable laying method for laying power and communication cables such as electric wires and telephone lines in the ground using a protective duct for wiring, and a fireproof bell block used in this method. It is related to cable construction technology for power and communication.

  Electricity and telephone power / communication cables are usually protected by synthetic resin wiring protective ducts (hereinafter simply referred to as “ducts”), and tunnels, general roads, and even highways and other sideways. In order to improve the efficiency of the installation and to maintain and inspect the cable, it is usually necessary to install manholes and handholes where one cable is directly exposed at an interval of 25 meters (hereinafter also referred to as “the manhole” or “handhole”). Called manholes).

  In the construction of this manhole, a bell block having a plurality of through holes for inserting cables is normally used, but the through hole for inserting a cable provided in the bell block has a relatively large diameter, Since the cable wired in the duct is restricted within a certain range by the diameter of the duct to be used, the space area inside the duct is very wide.

  Therefore, when a fire occurs in or near a manhole, flame, smoke, or high-temperature gas enters the duct from the opening of the bell block through-hole, and a duct with a large diameter and a large space is formed. There is a risk of expanding the fire as a passage, and the damage in the event of a fire may be immeasurable if it includes direct and indirect items.

  In particular, when a traffic accident occurs in a highway tunnel, fuel such as leaked gasoline or loaded flammable liquid accumulates in a manhole, resulting in a fire in a closed tunnel. In some cases, the damage can be even more serious.

  For this reason, various methods have been proposed to prevent the fire from expanding when a fire occurs in or near the manhole.

  For example, as a method for laying a cable, Japanese Patent Application Laid-Open No. Hei 4-21307 (Patent Document 1) has an opening at one end of a cable insertion hole formed in a bell block at an opening on a cable drawing side or a cable feeding side. A plug member in which a cable holding hole is formed is mounted, and the cable is concentrated and held in the cable holding hole of the plug member to close most of the opening portion of the cable insertion hole. A method has been proposed in which the cable exposed in the cable insertion hole is covered with a fire spread prevention material carrying a foamable material on the outer periphery.

In addition, in Utility Model Registration No. 2528553 (Patent Document 2) and Utility Model Registration No. 2605960, a cylindrical body having the same diameter as the inner diameter of one end opening of the cable insertion hole is formed of a non-combustible material. A lid body having a cable holding hole at the center or a lid body having no cable holding hole is integrally formed at the base end portion of the cylindrical body, and foamed by heat on the inner peripheral portion of the cylindrical body A method is also disclosed in which a plug member carrying a fire spread prevention material covered with a foaming substance with a protective film impermeable to gas or moisture is attached to a cable insertion hole formed in a bell block.
JP-A-4-21307 (Claims and FIG. 3) Utility Model Registration No. 2528553 (Utility Model Registration Claim 1) Utility Model Registration Gazette No. 2605960 (Utility Model Registration Claim 1)

  In the invention described in each of the above documents, the opening of the cable insertion hole of the bell block is closed by a lid member having a cable holding hole at the center or a plug member having a lid member having no cable holding hole. Is a foam material supported on the inside or outside of the plug member, the outside of the cable, etc. In the unlikely event that a fire breaks out, the inside of the manhole burns, or the flame or smoke in the manhole Even if high-temperature gas enters, the opening is closed by the plug member, so that the cable insertion hole formed in the bell block and the duct fitted and held in this cable insertion hole have flame, smoke, Has an excellent effect that there is almost no risk of expanding the damage as a passage of high-temperature gas.

  However, under worse conditions, for example, in a car accident in a highway tunnel as described above, fuel such as leaked gasoline and flammable liquid that had been loaded accumulated in the manhole, resulting in a fire. In some cases, a higher level of fire resistance and fire resistance has been demanded. Under such severe conditions, it is difficult to say that satisfactory results are always obtained with the conventionally proposed methods. is there.

Therefore, the inventors have studied to propose a method for laying a cable excellent in fire resistance and fire resistance that can be satisfied even under severe conditions, and as a result, conventionally, flame retardant synthetic resin and resin concrete have been studied. The bell block formed in step 1 is made mainly of cement containing substantially no organic substance, and the opening on the manhole side of the through hole for inserting the cable formed in the bell block is nonflammable. It is made of a flame-retardant or self-extinguishing material and has a cylindrical fire hydrant with an enlarged diameter at the tip, and the opposite opening is for fitting a non-flammable, flame-retardant or self-extinguishing resin duct As the present invention was completed, it was found that the above object can be achieved by wiring the cable with the joint of the above and filling the fire hydrant with a material having non-flammability, flame retardancy or self-extinguishing properties. is there.

The cable laying method according to claim 1 of the present invention includes:
When laying power / communication cables in the ground via manholes using protective ducts for wiring,
As a bell block that constitutes a part of the manhole and has a through hole for inserting a cable, the main material is cement that does not substantially contain an organic substance, and the surface that forms the outer surface of the manhole is nonflammable, flame retardant, or Use the one with a self-extinguishing resin joint,
Fit the protective duct for wiring into the joint,
The cable wired in the protective duct for wiring is formed of a non-flammable, flame-retardant or self-extinguishing material provided on the surface side forming the inner surface of the bell block manhole via the through hole of the bell block. Introducing into the manhole through the internal hole of the cylindrical fire hydrant having an enlarged diameter portion at the tip,
The interior pore space of the fire hydrant is filled with a material having nonflammability, flame retardancy, or self-extinguishing properties.

Moreover, the fireproof bell block according to claim 9 of the present invention,
The main material is cement that has a through hole for cable insertion and does not substantially contain organic substances.
When used as part of a manhole, it is made of non-flammable, flame-retardant or self-extinguishing resin for connecting a protective duct for cable wiring for power / communication at the opening of the through hole on the side that forms the outer surface of the manhole The joint is provided.

  According to the cable laying method of the present invention using the fire-proof bell block having the above-described configuration, fuel such as gasoline leaked in a car accident in a highway tunnel and flammable liquid loaded in the manhole Even under harsh conditions such as accumulation and fire, the opening is completely sealed with a non-flammable, flame retardant or self-extinguishing material filled in the plug member and the inside. Since the duct fitted and held in the cable insertion hole formed in the block is protected by a non-flammable, flame retardant or self-extinguishing resin joint, the cable insertion hole or duct is protected from flame, smoke, high-temperature gas, etc. Enlarging the damage as a passage also has an excellent effect that the duct itself does not burn due to the heat of the fire.

Furthermore, since each component used in the cable laying method of the present invention has a simple structure, it is easy and easy to lay the cable, and a special period is required to provide fire resistance and fire resistance. However, in the conventional laying method and the construction period, there is no difference, and if a plug member composed of a plurality of divided bodies is used as the plug member, it can be constructed in a shorter period of time. .

  Hereinafter, a fireproof bell block of the present invention and a cable laying method using the fireproof bell block will be described in detail with reference to the accompanying drawings.

  FIG. 1 is a schematic explanatory view for explaining a main part of a fire proof bell block and cable laying method according to the present invention, FIG. 2 is a front view of a fire hydrant used in the present invention, and FIG. It is a figure which shows the relationship of a bell block, and the laying state of a cable.

  As shown in FIG. 3, the power and communication cable 25 embedded in the ground (not shown) using the wiring protection duct 24 is exposed to the ground surface for maintenance and inspection. The manholes 21 that are opposed to each other in the laying direction of the cable 25 are formed by bell blocks 22, 22, and each bell block 22 is provided with a through hole 23 for inserting a cable.

  The bell block 22 in the figure is simplified, and the wall surface is formed by the single bell block 22 of the through hole 23. Usually, the shape and the size and number of the through holes are different for the wall surface formation. It is formed by a plurality of bell blocks.

  In the cable laying method shown in FIG. 3, the duct 24 protecting the cable 25 buried in the ground extends from the outer wall surface of the bell block 22 (the manhole side is the inner wall surface) to the through hole 3. It is inserted and held.

  The cable 25 drawn out from the duct 24 passes through the through hole 23 and is drawn out to the manhole 21 for maintenance and inspection, and is kept exposed in the space of the manhole 21.

  The cable 25 kept in an exposed state in the space of the manhole 21 is further extended and fitted into the bell block 22 through the through hole 23 of another bell block 22 in the same manner as described above. It is housed in a duct inserted and held and wired (not shown). The duct 24 to which the cable 25 is wired is buried in the ground, and the cable construction is completed.

  In FIG. 3, the plug member 26 is provided for fire spreading by the through hole 23 of the bell block 22, and the plug member 26 has an inner diameter of the cable insertion hole formed of a nonflammable material. A cylindrical body 28 having substantially the same diameter and a lid body 27 having a cable holding hole 29 at the center at the base end of the cylindrical body 28 are configured.

  Then, by closing the opening of the cable insertion hole 23 of the bell block 22, a fire may occur and the inside of the manhole 1 may be burned, or flame, smoke, or even high temperature gas may enter the manhole 1. In addition, the cable insertion hole 23 formed in the bell block 22 and the duct 24 fitted and held in the cable insertion hole 23 prevent passage of flames, smoke, and further high-temperature gas from expanding the damage. It plays the role of

  FIG. 1 illustrates the main part of the fireproof bell block and cable laying method of the present invention. In this invention, the duct 4 is inserted and held in the bell block 2 unlike the conventional one. A fire hydrant 6 is detachably provided on the inner side of the manhole of the fire-proof bell block 2.

  The fire hydrant 6 is filled with a non-flammable, flame retardant or self-extinguishing material 11 so as to wrap the wired cable 5, and has a fire retardant 6 and non-flammable, flame retardant or self-extinguishing property. The opening portion of the cable insertion hole 3 is completely sealed by the material 11.

The fireproof bell block 2 of the present invention has its shape, the number and size of the cable insertion holes 3 (
The hole diameter is the same as that of the conventional one, but the material is different from the conventional one made of flame retardant synthetic resin or resin concrete. It is made of a cement-free material, ie, concrete.

  Note that “substantially free of organic substances” means that synthetic resins are not included as components such as resin concrete, and a small amount of organic substances as water reducing agents and fluidizing agents are also included. It does not mean that there is no.

  The joint 10 is formed by reducing the diameter of the tip of the holding portion 10a that engages and holds the duct 4 to form the insertion portion 10b into the through hole 3, and is integrally molded with non-combustible, flame-retardant or self-extinguishing resin. The length of the through hole 3 for inserting the cable formed in the bell block 2 is less than half of the total length, and serves to separate the duct 4 engaged and held by the joint 10 from the manhole. The duct 4 is prevented from being melted, damaged, or spread by the heat generated by the fire in the manhole.

  As the non-flammable, flame-retardant or self-extinguishing resin used for the joint 10, a thermoplastic resin to which an inorganic or organic flame retardant such as antimony trioxide or chlorinated paraffin is added from the viewpoint of moldability, particularly polypropylene, etc. Polyolefin is preferred.

  Further, the joint 10 and the duct 4 are preferably made of a thermoplastic resin that naturally digests within 30 seconds according to a standardized combustion test according to JISC3653. Further, when the joint 10 is molded, as shown in FIG. 1, it is preferable to provide a protrusion 13 for ensuring the fitting on the surface of the fitting portion with the bell block 2.

  As described above, the fire hydrant 6 is provided on the inner surface of the bell block 2 on the manhole, and the fire hydrant 6 has non-flammability, flame retardant, or self-extinguishing properties so as to wrap the wired cable 5. Since the material 11 is filled without any gaps, the opening of the cable insertion hole 3 is completely sealed, and the inside of the manhole 1 is burned, or flame, smoke, or even high temperature gas enters the manhole 1. However, damage expansion to the cable insertion hole 3 and the duct 4 communicating with the cable insertion hole 3 can be prevented.

  Since the surface of the fire hydrant 6 is exposed to the manhole, it is made of a nonflammable, flame retardant, or self-extinguishing material because it is in direct contact with flames and smoke generated in the manhole 1 and also with high-temperature gas. These materials include cement, metal, ceramics, diatomaceous earth and the like, and preferred for this invention is cement, that is, made of concrete.

  The fire hydrant 6 is formed of a cylindrical body 8 having an outer diameter substantially the same as the inner diameter of the cable insertion hole 3 and having an enlarged diameter portion 7 at one end, and is integrally formed. Alternatively, it may be composed of a plurality of divided bodies.

  That is, as shown in FIG. 2, a cylindrical body 8 having an enlarged diameter portion 7 is composed of two divided bodies 6a and 6b obtained by cutting the central portion along the axial direction. When fitting into the cable insertion hole 3, the joined surfaces of the respective divided bodies 6 a and 6 b are combined by an appropriate means so as to be integrated, or finally fitted into the cable insertion hole 3 so that one fire plug 6 is finally obtained. There are no particular limitations on the number and shape of the divided members constituting one fire hydrant 6, but two or three divided members are preferable in terms of efficiency in production and use.

  Moreover, it is preferable that the fitting part to the cable insertion hole 3 of the cylindrical fire hydrant 6 is diameter-reduced in order to make the insertion into the cable insertion hole 3 easy, and also the diameter expansion part 7 is the surface. However, it is preferable that the surface of the bell block 2 be flush with the surface of the bell block 2 and that the surface be provided with a hole 12 for attachment to and removal from the cable insertion hole 3.

  In addition, as the material 11 having non-flammability, flame retardancy, or self-extinguishing properties, which is filled and filled without gaps so as to wrap the wired cable 5 inside the fire hydrant 6, inorganic fibers such as glass fiber and rock wool, Fireproof putty etc. are used.

  The fire-resistant putty is made by blending a large amount of the above-mentioned flame retardants and inorganic fillers such as aluminum hydroxide and calcium carbonate into a synthetic resin emulsion or liquid resin, and has a high viscosity. Materials such as clay-like putty MPP-45 (manufactured by Sumitomo 3M), liquid putty CP-25WB (manufactured by Sumitomo 3M) and the like are preferable for the present invention from the viewpoint of workability and fire resistance.

The fire plug 6 and the inside thereof are filled with a non-flammable, flame retardant or self-extinguishing material 11 to block flame, smoke, and high-temperature gas. It is desirable to apply to all of the holes 3, that is, all of the cable insertion holes 3 where the current cable 5 is not wired, including the cable insertion holes 3 provided for future expansion.

The fireproof bell block according to the present invention, and the cable laying method using the bell block, fire resistance such as power and communication cables such as electric wires and telephone lines laid underground using a protective duct for wiring, In particular, it improves the fire resistance around the manhole and is widely used in various industries that use power and communication cables.

It is a schematic explanatory drawing explaining the principal part of the laying method of the fireproof bell block and cable of this invention. It is a front view of the fire hydrant used by this invention. It is a figure which shows the relationship between the manhole and bell block by a prior art, and the laying state of a cable.

Explanation of symbols

1 Manhole 2 Bell block 3 Cable insertion hole 4 Protective duct for wiring (duct)
DESCRIPTION OF SYMBOLS 5 Cable 6 Fire hydrant 7 Expanded diameter part 8 Cylindrical body 9 Holding hole 10 Joint 11 Material which has incombustibility, a flame retardance, or self-extinguishing property 12 Hole 13 Protrusion

Claims (11)

When laying power / communication cables in the ground via manholes using protective ducts for wiring,
As a bell block that constitutes a part of the manhole and has a through hole for inserting a cable, the main material is cement that does not substantially contain an organic substance, and the surface that forms the outer surface of the manhole is nonflammable, flame retardant, or Use the one with a self-extinguishing resin joint,
Fit the protective duct for wiring into the joint,
The cable wired in the protective duct for wiring is formed of a non-flammable, flame-retardant or self-extinguishing material provided on the surface side forming the inner surface of the bell block manhole via the through hole of the bell block. Introducing into the manhole through the internal hole of the cylindrical fire hydrant having an enlarged diameter portion at the tip,
A method for laying a cable, characterized in that an internal hole space of a fire hydrant is filled with a material that is incombustible, incombustible, or self-extinguishing. The bell block is
Of the through hole for inserting the cable, the through hole through which the cable does not pass is also provided on the surface side forming the inner surface of the manhole of the bell block.
The cable laying method according to claim 1, wherein the internal hole of the fire hydrant is filled with a material having noncombustibility, flame retardance, or self-extinguishing property to close the through hole. The fire hydrant is
A material having a non-flammable, flame-retardant or self-extinguishing material comprising a cylindrical body having an outer diameter substantially the same as the inner diameter of the opening on the inner surface forming surface side of the insertion hole and having an enlarged diameter portion formed on one end surface The cable laying method according to claim 1, wherein the cable is laid integrally with each other. The fire hydrant is
A material having a non-flammable, flame-retardant or self-extinguishing material comprising a cylindrical body having an outer diameter substantially the same as the inner diameter of the opening on the inner surface forming surface side of the insertion hole and having an enlarged diameter portion formed on one end surface The cable laying method according to claim 1, wherein the cable laying method is constituted by a plurality of divided bodies formed so as to be integrated at the time of use. The joint provided on the bell block is
The cable laying according to claim 1 or 2, wherein the bell block is fitted and inserted into a through hole for inserting a cable, and the insertion depth is not more than half of the length of the through hole. Method. The joint is
The cable laying method according to claim 1 or 2, wherein the cable is laid with a thermoplastic synthetic resin to which a flame retardant is added. The fire hydrant is
The cable laying method according to claim 1 or 2, wherein the main material is cement that does not substantially contain an organic substance. Non-flammable, flame retardant or self-extinguishing material that fills the inside of the fire hydrant,
The cable laying method according to claim 1 or 2, wherein the cable is a putty-like material having high viscosity and viscosity. The main material is cement that has a through hole for cable insertion and does not substantially contain organic substances.
When used as part of a manhole, it is made of non-flammable, flame-retardant or self-extinguishing resin for connecting a protective duct for cable wiring for power / communication at the opening of the through hole on the side that forms the outer surface of the manhole A fireproof bell block characterized by being provided with a joint. The joint is
The fireproof bell block according to claim 8, wherein the bell block is fitted and inserted into a through hole for inserting a cable of the bell block to a position not more than half of its length. The incombustible, flame retardant or self-extinguishing resin is
The fireproof bell block according to claim 8, which is a thermoplastic synthetic resin to which a flame retardant is added.

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