JPH0441731Y2 - - Google Patents

Description

[Detailed description of the invention] [Field of industrial application] The present invention relates to manholes or handholes (herein referred to collectively as manholes) used when laying cable conduit lines for communications, electric power, etc., and is particularly applicable to conduit connections. The present invention relates to a precast manhole having a blind hole-like preliminary hole prepared in advance for the purpose of use.

[Conventional technology]

Traditionally, when installing underground conduits, the common method was to first construct the manhole section on site, then perform underground conduit construction to connect the manhole and conduit. In order to deal with traffic congestion caused by such civil engineering works, factory-produced precast manholes are being used to shorten the construction period. The structure of the conduit connection part of such a precast manhole can be roughly divided into two types.

One method is to install a duct with an opening corresponding to the number of connection pipes on the side wall of the manhole, and after positioning the pipe inside the duct at the construction site.
One method is to build formwork inside and outside the manhole and pour concrete to connect it.The other method is to make a blind hole-shaped preliminary hole for connecting the pipe in the manhole wall for each pipe line. This is a method of connecting pipes by opening preliminary holes at necessary connection points at the construction site.

The former requires a lot of man-hours for formwork, etc., and if it is necessary to expand the duct, it is difficult to open the duct by partially destroying the manhole side wall and waterproof concrete layer using a drill or breaker. Compared to this, the latter method is simpler and requires only a chisel-like tool to break the thin wall of the manhole side wall when adding pipes. Yes, no formwork is required, and the spacing between the pipes is determined by the spacing between the preliminary holes.
Recently, it has been widely adopted due to its good appearance.

FIG. 3 is a partial cross-sectional view of a conventional manhole having a preliminary hole for connecting pipes. The thin wall portion 3
By tearing the hole, you can easily make one hole.

FIG. 4 is a partially sectional perspective view showing the conduit connection state, and in the figure, 2 is an unused spare hole, and 2' is an open hole to which the conduit 4 is connected.

[Problem that the invention attempts to solve]

The above-mentioned conventional manhole with a spare hole for connecting pipes has the advantage of allowing you to freely select the number and position of the pipes to be connected, but on the other hand, the extra blind hole-like spare hole 2 is not used. Remaining, unused spare hole 2
and the opening hole 2' to which the conduit 4 is connected have the same shape, so when you look inside the manhole to confirm the conduit connection position, you may find that there is an unused spare hole or the conduit in the dark manhole. This has the disadvantage that it is difficult to identify which opening hole is connected, and it is easy to misidentify it.

Closing unused holes to prevent misidentification makes the work when expanding the pipeline difficult, and covering unused holes with some kind of removable cap increases costs.

This invention was developed in consideration of the above points.
To provide a manhole with a spare hole for conduit connection that allows unused spare holes to be visually recognized simply and inexpensively.

[Means for solving problems]

The above object is achieved by providing a manhole having a blind hole-shaped preliminary hole for conduit connection with a protrusion projecting from the center of the bottom of the preliminary hole to the hole entrance side.

[Action]

Since the protrusion mentioned above is integrated with the thin wall that forms the bottom of the reserve hole, it exists only when the reserve hole is unused, and when the thin wall is broken to connect the pipe, the protrusion will be removed along with it. . Therefore, depending on the presence or absence of the above-mentioned protrusion, it is possible to easily identify from the surface whether it is an unused reserve hole or an open hole to which a conduit is connected just by looking inside the manhole, and there is no possibility of misidentification even in a dark place inside the manhole. There is no.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS. 1 and 2.

FIG. 1 is a partial cross-sectional view of an embodiment of a manhole with preliminary holes for conduit connection according to the present invention, in which a plurality of blind hole-like holes are provided in the side wall of the manhole 1, leaving a thin wall portion 3 on the outside surface. One of the preliminary holes 2 for conduit connection is shown. 5 is a protrusion that protrudes from the center of the bottom of the preliminary hole 2 to the hole entrance side and is formed so that its tip is almost flush with the manhole wall surface; when the preliminary hole 2 is not in use, the tip of this protrusion is appearing on the surface.

FIG. 2 is a perspective view partially showing the conduit connection state, and the unused preliminary hole 2 and the open hole 2' to which the conduit 4 is connected by breaking the thin wall part 3 are different depending on the presence or absence of the protrusion 5. It can be clearly identified.

[Effect of idea]

According to the present invention, it is possible to easily distinguish between an unused reserve hole and an open hole to which a conduit is connected by simply looking into the manhole, thereby preventing troubles due to misidentification when designing conduit extensions, etc. Furthermore, since the identification protrusion is formed by precasting, there is an advantage that the cost is extremely low and the work will not be difficult when adding pipes.

[Brief explanation of the drawing]

Fig. 1 is a partial cross-sectional view of a manhole with a preliminary hole for conduit connection according to the present invention, Fig. 2 is a perspective view showing the state of conduit connection in partial cross section, and Fig. 3 is a conventional preliminary hole for conduit connection. Partial sectional view of a manhole with a 4th
The figure is a perspective view showing a state in which the pipes are connected, partially in cross section. 1... Manhole, 2... Spare hole for conduit connection,
2'...Open hole, 3...Thin wall part, 4...Pipe line, 5
……protrusion.

Claims (1)

[Scope of utility model registration request] In a manhole in which a plurality of blind hole-like preliminary holes are provided on the side wall of the manhole with a thin wall portion left on the outside surface for connecting underground pipes, a portion of the preliminary hole protrudes from the center of the bottom surface to the hole entrance side. What is claimed is: 1. A manhole having a preliminary hole for conduit connection, characterized in that it is provided with a protrusion for connecting the conduit.