JP4070091B2 - manhole - Google Patents

Description

[0001]
[Industrial application fields]
The present invention relates to the structure of a manhole (including a handhole).
[0002]
[Prior art]
In general, a manhole is often composed of a manhole body having a pipe buried in the lower wall surface and a single iron manhole cover attached to the upper surface opening of the manhole body. The iron manhole cover is mainly required to withstand load, and although it has fire resistance, it does not have the ability to insulate. For this reason, when a fire breaks out around the manhole, the heat of the fire is transmitted to the inside of the manhole through the manhole cover, and the transmitted fire heat is stored in the cable, the cable connecting member and the pipe line. The problem of damaging etc. arises.
[0003]
Conventionally, as described in Utility Model Registration No. 3032908 and Utility Model Registration No. 3043060, manholes are known which are configured to provide a heat insulating inner lid under the manhole cover to block heat exchange by the manhole cover. Yes. However, in the conventional manhole structure described above, there is a gap between the wall of the manhole body and the heat insulating inner lid, so when a fire occurs around the outside of the manhole, There is a problem in that the cable is transmitted to the whole manhole through the gap and damages the cables stored in the manhole.
[0004]
[Means for solving problems]
In order to solve the above problems, the manhole (7) according to the present invention includes a manhole body (3) in which a pipe (6) is buried in the ground of the lower wall surface, and a manhole attached to the upper surface opening of the manhole body. In a conventional manhole consisting of a lid (4), a heat insulating inner lid (8) is installed below the manhole lid (4) and above the pipe (6) buried in the ground near the manhole lid (4). The heat insulating inner lid (8) comprises a receiving plate (1) made of a metal plate that is nonflammable and hardly deformed by heat, and a thermally expandable heat insulating material (2) installed on the upper surface of the receiving plate (1) . When a fire occurs around the outside of the manhole, the heat-expandable heat insulating material (2) is thermally expanded by the fire heat transmitted to the inside through the manhole cover (4), and the manhole body (3) and the receiving plate (1) der which is characterized in that close the gap between the . As a result, when a fire occurs around the outside of the manhole, the heat-expandable heat insulating material (2) expands due to the fire heat transmitted to the inside through the manhole cover (4), and the heat-expandable heat insulating material (2) expanded. Holds the shape by the backing plate (1), and exerts further heat insulating effect by closing the gap between the backing plate (1) and the manhole wall surface, and heat is generated inside the manhole below the heat insulating inner lid (8). Can be prevented for a long time, and the cable, the cable connecting member, the pipe line and the like housed inside can be protected.
[0005]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to FIGS.
FIG. 1 shows the structure of a manhole according to the present invention. As shown in this figure, the manhole (7) according to the present invention is attached to the manhole body (3) in which the pipe (6) is buried in the ground of the lower wall surface, and the upper opening of the manhole body (3). The manhole cover (4) is the same as the conventional one, but the frame (5) is placed on the wall below the manhole cover (4) and above the pipe line (6) closest to the manhole cover (4). It is characterized by the fact that a heat insulating inner lid (8) is installed on the stand (5).
[0006]
The manhole body (3) is formed into a concrete circular or square shape, and the manhole cover (4) installed at the top opening of the manhole body (3) has the same shape as the manhole body (3) It is formed by. The pipe (6) buried in the lower wall of the manhole in the basement uses fume pipes, metal pipes, and resin pipes.
[0007]
The position of the gantry (5) is not specified as long as it is between the manhole cover (4) and the pipe line (6) closest to the manhole cover (4), but the closer to the manhole cover (4), the maintenance inspection It is preferable because it can be opened and closed easily and the expansion reaction of the thermally expandable heat insulating material (2) is fast.
[0008]
As shown in the front view of Fig. 2 and the side view of Fig. 3, the heat insulating inner lid (8) is installed on the upper surface of the receiving plate (1) made of nonflammable and high temperature resistant material. And a thermally expandable heat insulating material (2). The front shape of the heat insulating inner lid (8) shown in Fig. 2 is a square shape, but the shape may be formed in a circular shape or the like according to the shape of the manhole, and it can be accommodated from the top opening of the manhole. There is no particular limitation. The heat insulating inner lid (8) is preferably a little smaller than the inner circumference of the manhole by about 10mm to 25mm so as not to hinder the opening and closing of maintenance inspections. Further, it is preferable that the backing plate (1) and the thermally expandable heat insulating material (2) have the same shape and size.
[0009]
The receiving plate (1) uses a fire-resistant non-combustible material, and is preferably a metal plate that is not easily deformed by heat, and is preferably a lightweight plate such as an aluminum plate. Thermally expandable heat insulating material (2) is a sheet-like flame-resistant material composed of flame retardant rubber, inorganic filler, inorganic expandable material, organic expandable material, etc. However, it should be changed to carbide with heat insulation. As such a heat-expandable heat-resistant material, for example, a product commercially available from Furukawa Techno Material Co., Ltd. under the trade name “Dunseal FB Sheet” can be used. In addition, as for the thickness of commercially available heat-expandable heat insulating materials, there are many products of about 3mm to 20mm, but as described above, when the heat insulating inner lid (8) is installed in a predetermined place, the gap with the manhole wall is 10mm In the case of about ~ 25 mm, it is preferable to use a thermal expansion insulating material (2) having a thickness of 5 mm or more in order to close the gap from the beginning of the fire.
[0010]
【Example】
In this example, as shown in Fig. 1, the manhole body (3) is made of concrete with a square depth of 800mm and a cross section of 600mm x 600mm, and the manhole cover (4) is made of iron. The same shape as the manhole body (3) was used. In this manhole (7), pipes (6) are buried in three places, 400mm, 600mm and 700mm below the manhole cover (4) on the lower wall of the manhole body (3). A metal stand (5) that receives the insulated inner lid (8) is installed on the wall of the manhole body (3), 120mm below the manhole cover (4), and the insulated inner lid is placed on the stand (5). (8) was placed.
As shown in Fig. 2, the heat insulating inner lid (8) has a square shape similar to that of the manhole body (3), and its dimensions are about 20mm smaller than the inner periphery of the manhole body (3). As shown in FIG. 3, the heat insulating inner lid (8) is composed of a receiving plate (1) and a thermally expandable heat insulating material (2) disposed on the upper surface of the receiving plate (1). The plate (1) uses an aluminum plate with a thickness of 3 mm, and the thermally expandable insulation (2) is a sheet-like thermally expandable insulation with a expansion rate of 6 times that begins to expand at 200 ° C (15 mm thick) (Furukawa Techno Material Co., Ltd.) The product name is Dunseal FB sheet). This thermally expandable heat insulating material (2) was fixed on the aluminum receiving plate (1) with a commercially available double-sided tape.
[0011]
The heat insulation effect was confirmed as follows with respect to the manhole described in the above example.
In other words, assuming a fire of about 2 hours, charcoal was uniformly spread over the manhole cover (4) and heated. As shown in Fig. 4, the thermocouple is located between the manhole cover (4) 50mm below the manhole cover (4) and the heat insulating inner cover (8) (9), and the receiving plate 120mm below the manhole cover (4) ( Installed at three locations (11), (12), (13) at a total of five locations (10) on the bottom of 1), 400mm, 600mm, and 700mm below the manhole cover (4). The temperature was measured. The thermocouple used was capable of withstanding 1200 ° C.
[0012]
FIG. 5 shows a graph of the measurement results. In FIG. 5, curves (14) to (18) represent temperature changes with time measured at the thermocouple positions (9) to (13) shown in FIG. As shown in Fig. 5, even if the space temperature (14) between the manhole cover (4) and the heat insulating inner cover (8) is heated to about 1000 ° C, the temperature (15) at the bottom of the receiving plate is about 400 The temperature (16) to (18) near the estimated pipeline position was about 16 ° C. As a result, the temperature in the vicinity of the pipe line did not rise so as to damage the cable, the cable connecting member, the pipe line, etc., and the excellent heat insulation effect of the present embodiment could be confirmed.
[0013]
【The invention's effect】
The manhole (7) according to the present invention includes a manhole body (3) in which a pipe line (6) is buried in the ground of the lower wall surface, and a manhole cover (4) attached to the upper surface opening of the manhole body (3). In the conventional manhole constructed, a heat insulating inner lid (8) is installed below the manhole cover (4) and above the pipe line (6) close to the manhole cover (4), and the heat insulating inner cover (8). Is composed of a receiving plate (1) made of a metal plate that is nonflammable and hardly deformed by heat, and a thermally expandable heat insulating material (2) installed on the upper surface of the receiving plate (1). When a fire breaks out, the heat transmitted from the manhole cover (4) to the inside expands and expands the thermally expandable heat insulating material (2) installed on the backing plate (1) of the heat insulating inner cover (8). The heat-expandable heat insulating material (2) retains its shape by the backing plate (1). By blocking the gap between the receiving plate (1) and the manhole wall, heat is prevented from being transmitted downward from the heat insulating inner lid (8), and the cables, cable connecting members, and pipes stored in the manhole are protected. can do.
[Brief description of the drawings]
FIG. 1 is an explanatory view showing a manhole according to the present invention.
FIG. 2 is a front view of a heat insulating inner lid used in the present invention.
FIG. 3 is a side view of a heat insulating inner lid used in the present invention.
FIG. 4 is an explanatory diagram of a state where a thermocouple is installed in a manhole according to the present invention.
FIG. 5 is a graph showing a temperature measurement result for confirming the effect of the example.
[Explanation of symbols]
1. Backing plate 2. 2. Thermally expandable heat insulating material 3. Manhole body 4. Manhole cover Base 6 Pipe line 7. Manhole 8. Insulated inner lid 9. Thermocouple installation position10. 10. Thermocouple installation position Thermocouple installation position 12. Thermocouple installation position13. Thermocouple installation position14. 15. Temperature measured at thermocouple installation position 9. Temperature measured at thermocouple installation position 10 16. 18. Temperature measured at thermocouple installation position 11 Temperature measured at thermocouple installation position 12 18. Temperature measured at thermocouple installation position 13

Claims (3)

  In a manhole comprising a manhole body (3) in which a pipe line (6) is embedded in the lower wall surface and a manhole cover (4) attached to the upper surface opening of the manhole body (3), a manhole cover ( 4) A heat insulating inner cover (8) is installed below the pipe line (6) close to the manhole cover (4) below the heat insulating inner cover (8), and the heat insulating inner cover (8) is nonflammable and hardly deformed by heat. And a thermally expandable heat insulating material (2) installed on the upper surface of the receiving plate (1). When a fire occurs around the outside of the manhole, the manhole cover (4) A manhole characterized in that the thermally expandable heat insulating material (2) is thermally expanded by fire heat transmitted to the inside to close a gap between the manhole body (3) and the receiving plate (1).   The manhole according to claim 1, wherein the heat-expandable heat insulating material (2) is composed of a flame-retardant rubber, an inorganic filler, an inorganic expandable material, and an organic expandable material that start to expand at 200 ° C.   The manhole according to claim 1, wherein the thermally expandable heat insulating material (2) is a sheet-like heat expandable heat insulating material.

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