JP5865637B2 - Manhole bottom plate and assembly manhole - Google Patents

Description

  The present invention relates to a technique for preventing a manhole from rising due to a ground liquefaction phenomenon.

  In recent years, development of technology for preventing the manhole from rising due to the liquefaction phenomenon of the ground has been underway. For example, the assembly-type manhole disclosed in Patent Document 1 includes a manhole housing main body and a bottom plate on which the main body is placed, and the height of the peripheral portion of the bottom plate decreases toward the connecting portion with the main body. A tapered surface is formed. A pipe is connected to the side surface near the manhole bottom plate of the manhole body.

  When the liquefaction phenomenon occurs, the bottom plate of the assembly manhole receives a lifting pressure from the ground, while the bottom plate receives a soil pressure in a direction resisting the lifting pressure from the ground on the periphery. As a result, the lifting pressure acting on the bottom plate is canceled or reduced, and the assembling manhole is prevented from rising.

JP 2008-291563 A

  However, the conventional manhole rising prevention technology does not consider the protection of the piping around the manhole housing main body, and there is a possibility that the piping may be damaged if the ground liquefaction occurs.

Therefore, the manhole bottom plate of the present invention includes a bottom plate body on which the manhole housing main body is installed , and an inflow pipe which is provided integrally with the bottom plate body so as to protrude from the side surface of the bottom plate body and is connected to the side surface of the manhole housing body. And an auxiliary bottom plate having a rectangular plate shape, which is disposed directly under the outflow pipe and whose width is longer than the maximum outer diameter of the inflow pipe and outflow pipe .

The assembly manhole includes a manhole housing body and a manhole bottom plate on which the housing body is installed. The manhole bottom plate projects from the bottom plate body on which the housing body is installed, and a side surface of the bottom plate body. A rectangular plate having a width longer than the maximum outer diameter of the inflow pipe and the outflow pipe, which is provided integrally with the main body and is respectively disposed directly under the inflow pipe and the outflow pipe connected to the side surface of the manhole housing main body. The inflow pipe and the outflow pipe are made of deformable pipes having ribs, and the casing main body, the manhole bottom plate, the inflow pipe and the outflow pipe on the bottom plate are buried with crushed stone.

  According to the above invention, since the surface area of the lower surface of the manhole bottom plate is increased by the amount of the auxiliary bottom plate, the resistance to the ground lifting pressure due to the liquefaction phenomenon is increased. Further, since the auxiliary bottom plate is positioned directly below the inflow pipe and the outflow pipe and the lift pressure is subjected to the resistance of the auxiliary bottom plate, the load of the lift pressure on the pipe is greatly reduced. In particular, the assembly manhole of the present invention can absorb the impact of the lifting pressure because the inflow pipe and the outflow pipe can be deformed. In addition, since the manhole body and the manhole bottom plate are buried by crushed stone, the weight of the assembly manhole is increased, the resistance to the lifting pressure is further increased, and the ground sediment around the manhole body is dissipated to dissipate the surroundings of the body. Liquefaction of the ground is suppressed.

  Therefore, according to the above invention, the manhole housing body can be prevented from rising and the piping around the housing body can be protected.

Sectional drawing of the assembly manhole which concerns on embodiment of this invention. The top view of the assembly manhole which concerns on embodiment of this invention. The side view (a) of the manhole bottom plate which concerns on embodiment of this invention, the top view (b) of the said manhole bottom plate.

  An assembly manhole 1 according to the embodiment of the present invention illustrated in FIG. 1 includes a manhole housing body 2 and a manhole bottom plate 3 on which the housing body 2 is installed.

  As shown in the figure, the manhole housing body 2 is of a one-sided oblique wall type. That is, the manhole housing body 2 includes a manhole cover 21, a cover receiving frame 22, an adjustment wall 23, a swash wall 24, a straight wall 25, and a bottomed housing 26. Both the straight wall 25 and the bottomed casing 26 are formed in a cylindrical shape, and the inner diameter is also set to the same diameter. The manhole housing main body according to the present invention is not limited to the illustrated single inclined wall type, but may be a double inclined wall type.

  An inlet 261 and an outlet 262 are formed in the bottomed casing 26. The illustrated inlet 261 and outlet 262 are provided so as to face each other, and the bottom of the inlet 261 is set to be at least higher than the bottom of the outlet 262. The installation angle of the outlet 262 with respect to the inlet 261 centering on the bottomed casing 26 is not limited to 180 ° as shown in FIG. 2, and is set to a predetermined angle according to the site where the assembly manhole 1 is installed. Is done.

  The inflow piping 4 and the outflow piping 5 are connected to the inflow port 261 and the outflow port 262 of the bottomed casing 26 through flexible joints 6 and 7, respectively. As the flexible joints 6 and 7, a known flexible joint adopted in a conventional assembly manhole may be applied. The inflow piping 4 and the outflow piping 5 are made of deformable piping having ribs. As this deformable pipe, for example, a well-known rigid vinyl chloride pipe with a rib is applied.

  The bottom portion 263 of the bottomed casing 26 is formed integrally with the casing 26 main body. An inclined groove 264 and an inclined surface 265 are formed on the bottom portion 263. The inclined groove 264 communicates with the inflow port 261 and the outflow port 262 of the bottomed casing 26, and the curvature of the bottom thereof is formed substantially equal to the curvature of the inflow port 261 and the outflow port 262, and the introduced fluid flows from the inflow port 261. It is formed so as to ensure a gradient that shifts to the outlet 262. The inclined surface 265 is formed so that the height of the surface gradually decreases from the inner wall surface side of the bottomed casing 26 toward the inclined groove 264 side. The bottom portion 263 may be formed by placing mortar in the bottomed casing 26 after the manhole casing body 2 is installed on the manhole bottom plate 3.

  As shown in FIGS. 3A and 3B, the manhole bottom plate 3 includes a bottom plate body 31 and auxiliary bottom plates 32a and 32b.

  As shown in FIG. 1, the manhole housing body 2 is installed on the bottom plate body 31. The bottom plate body 31 is formed in a disc shape according to the shape of the bottomed casing 26, and the outer diameter thereof is set larger than the outer diameter of the bottomed casing 26. As shown in FIGS. 3A and 3B, the bottom plate main body 31 is formed with a recess 33 in which the bottomed casing 26 is installed. As shown in FIG. 1, the concave portion 33 is formed so that the peripheral edge portion 34 engages with the lower end edge portion 266 of the bottomed casing 26.

  The auxiliary bottom slabs 32a and 32b are formed on the side surfaces of the bottom slab body 31 so that they can be arranged directly below the inflow piping 4 and the outflow piping 5 connected to the side surface of the bottomed casing 31 as shown in FIGS. Yes. The auxiliary bottom plates 32a and 32b are formed in a rectangular plate shape as shown in FIG. 3 (b), and correspond to the positions of the inlet 261 and outlet 262 of the bottomed casing 26 shown in FIGS. In this way, it is integrally formed with the bottom plate body 31 so as to protrude from the side surface of the bottom plate body 31.

  As shown in FIG. 2, the widths D1 of the auxiliary bottom plates 32a and 32b are set to be longer than at least the maximum outer diameter D2 of the inflow pipe 4 and the outflow pipe 5, respectively. Further, the total length La of the auxiliary bottom plate 32a and the total length Lb of the auxiliary bottom plate 32b are set to be substantially equal, and the length from one end side of the auxiliary bottom plate 32a to one end side of the auxiliary bottom plate 32b that separates the bottom plate body 31 is the assembly manhole 2. It is set to be approximately equal to a general excavation width D at the time of construction.

  The manhole housing body 2, the manhole bottom plate 3, the inflow piping 4 and the outflow piping 5 on the bottom plate 3 are evenly buried by the crushed stone 8 as shown in FIGS.

  The assembly manhole 1 may be constructed by a conventional construction method. An example of the construction procedure of the assembly manhole 1 will be described with reference to FIG.

  First, after the foundation surface is formed by uniformly and smoothly laying ground stone or crushed stone as a base material on the bottom of the excavation pit of the ground 11 on which the assembly manhole 1 is installed, the manhole bottom slab 3 is placed on the surface through the mortar. Laid. Next, the bottomed casing 26 is installed in the recess 33 of the manhole bottom plate 3 so that the inflow port 261 and the outflow port 262 are respectively disposed directly above the auxiliary bottom plate 32a and the auxiliary bottom plate 32b. The outer joints between the manhole bottom plate 3 and the bottomed casing 26 are filled with mortar 9. Next, the straight wall 25, the swash wall 24, the adjustment wall 23, the lid receiving frame 22, and the manhole cover 21 are sequentially installed on the bottomed casing 26. The joints between the members 23 to 26 are appropriately filled with mortar. The gap between the adjustment wall 23 and the lid receiving frame 22 is filled with the adjustment mortar 10. The inflow piping 4 and the outflow piping 5 are connected to the inflow port 261 and the outflow port 262 of the bottomed casing 26 through flexible joints 6 and 7, respectively. When the assembly of the assembly manhole 1 is completed as described above, the excavation pit is uniformly backfilled up to the roadbed 12 by the crushed stone 8 and the assembly manhole 1 is embedded. The gap between the inflow pipe 4 and the outflow pipe 5 and the auxiliary bottom plates 32a and 32b is equally filled with the crushed stone 8.

  The function and effect of the assembly manhole 1 will be described with reference to FIG.

  When the liquefaction phenomenon of the ground 11 occurs due to an earthquake or the like, the manhole bottom plate 3 of the assembly manhole 1 receives the lifting pressure of the ground 11 from below. Since the manhole bottom plate 3 has a lower surface area that is increased by the amount of the auxiliary bottom plates 32a and 32b, resistance to the lifting pressure is increased. In particular, the auxiliary bottom slabs 32a and 32b are located directly below the inflow pipes 4 and the outflow pipes 5, and the lifting pressure is received by the resistance of the auxiliary bottom slabs 32a and 32b. The pressure load is greatly reduced. Thereby, damage to the inflow piping 4 and the outflow piping 5 around the manhole housing body 2 is avoided. In addition, since the inflow pipe 4 and the outflow pipe 5 can be deformed, the impact of the lifting pressure is absorbed, and damage to the pipes 4 and 5 can be further prevented. Furthermore, since the manhole body 2 and the manhole bottom plate 3 are embedded with the crushed stone 8, the weight of the assembly manhole 1 is increased, and the resistance to the lifting pressure is further increased. Moreover, since the sediment water around the manhole body 2 is dissipated by burying with the crushed stone 8, liquefaction of the ground 11 around the body 2 can be suppressed. As described above, according to the assembly manhole 1, the manhole housing main body 2 can be prevented from floating due to the liquefaction phenomenon of the ground 11, and the inflow piping 4 and the outflow piping 5 around the main body 2 can be protected.

  The present invention is not limited to the above-described embodiment, and various modifications are possible within the scope of the invention described in the claims, and these modifications are also included in the technical scope of the present invention. It goes without saying that it is what is done.

DESCRIPTION OF SYMBOLS 1 ... Assembly manhole 2 ... Manhole housing main body 3 ... Manhole bottom plate, 31 ... Bottom plate main body, 32a, 32b ... Auxiliary bottom plate 4 ... Inflow piping 5 ... Outflow piping 8 ... Crushed stone

Claims (2)

A bottom plate body on which the manhole body is installed,
The width of the inflow pipe and the outflow pipe is extended from the side surface of the bottom plate body and is provided integrally with the bottom plate body, and is disposed directly below the inflow pipe and the outflow pipe connected to the side surface of the manhole housing main body. A manhole bottom plate characterized by comprising a rectangular plate-like auxiliary bottom plate having a longer diameter than the maximum outer diameter . The manhole housing body,
With a manhole bottom plate where this chassis body is installed,
The manhole bottom plate is
A bottom plate body on which the housing body is installed;
The width of the inflow pipe and the outflow pipe is extended from the side surface of the bottom plate body and is provided integrally with the bottom plate body, and is disposed directly below the inflow pipe and the outflow pipe connected to the side surface of the manhole housing main body. It consists of a rectangular plate-shaped auxiliary bottom plate that is longer than the maximum outer diameter ,
The inflow pipe and the outflow pipe are made of deformable pipes having ribs,
An assembly manhole characterized in that the main body, manhole bottom plate, inflow piping and outflow piping on the bottom plate are buried by crushed stone.

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