JP5038975B2 - Anti-levitation manhole structure - Google Patents

Description

  The present invention relates to a levitating manhole structure.

When the ground liquefies due to an earthquake, the manhole will rise and the manhole will rise from the ground and rise.
In the technique of Patent Document 1, the lower end of the pipe is penetrated to the invert and the base portion to reach the natural ground, and a plurality of hollow pipes having the upper end of the pipe above the groundwater level are provided, and moisture is increased by the hollow pipe. It diffuses into the manhole from the top opening.
JP 2007-23603 A

  The technique of patent document 1 requires a lot of work to make the lower end of the pipe penetrate the invert and the foundation and reach the natural ground.

A first object of the present invention is to provide a manhole structure that prevents the manhole from rising and rising.
The second object of the present invention is to provide a manhole structure that prevents the manhole from rising and rising even if liquefaction occurs due to an earthquake.

(About claim 1)
A bottom plate with drain holes is installed at the bottom of the shaft. A large number of crushed stones are placed on the bottom plate to form a crushed stone foundation.
The bottom plate is installed on the crushed stone foundation and becomes the bottom of the manhole.
A straight wall cylinder serving as a side wall of the manhole is fixed on the bottom plate, and a latch is attached to a plurality of locations on the outer periphery of the lower part.
The top plate has a hole that can be loosely fitted into the straight wall cylinder, and is fitted into the straight wall cylinder. This top plate is fixed to the latch or placed on the latch.
The top plate is connected and fixed to the bottom plate by the fixing means.

  The anti-levitation manhole structure is equipped with hooks at multiple locations on the outer periphery of the lower part, and the top plate is fixed to the hook, or the top plate is placed on the hook, and the top plate is connected to the bottom plate by fixing means. And fixed. And in addition to the weight increase (anchor effect) due to the formation of a crushed stone foundation by placing a lot of crushed stones on the bottom plate, resistance due to earth pressure is applied to the top plate. it can.

  Since it has a structure in which hanging brackets are attached to the lower outer periphery of the straight wall cylinder fixed on the bottom plate and the top plate is fixed to the hanging bracket, or the top plate is placed on the hanging bracket, The outer diameter of the wall cylinder can be made the same as the outer diameter of the bottom plate.

(About claim 2)
A bottom plate with drain holes is installed at the bottom of the shaft. A large number of crushed stones are placed on the bottom plate to form a crushed stone foundation.
The bottom plate is installed on the crushed stone foundation and becomes the bottom of the manhole.
The straight wall cylinder serving as the side wall of the manhole is fixed on the bottom plate so that the bottom surface of the cylinder faces the inside of the bottom plate edge.
The top plate has a hole that can be freely fitted into the straight wall cylinder, is fitted into the straight wall cylinder, and is placed on the bottom plate.
The top plate is connected and fixed to the bottom plate by the fixing means.

In the levitation prevention manhole structure, a top plate that is fitted into a straight wall cylinder and placed on the bottom plate is connected and fixed to the bottom plate by a fixing means.
And in addition to the weight increase (anchor effect) due to the formation of a crushed stone foundation by placing a lot of crushed stones on the bottom plate, resistance due to earth pressure is applied to the top plate. it can.

The levitation prevention manhole structure is a structure in which the top plate is fitted into a straight wall cylinder and placed on the bottom plate, and the top plate is connected and fixed to the bottom plate by fixing means.
And since the resistance by earth pressure is applied to a top plate in addition to the weight increase by mounting many crushed stones on the bottom plate and forming the crushed stone foundation, the levitation preventing manhole structure can prevent the levitation and rising.
In addition, the straight wall cylinder is fixed on the bottom plate so that the bottom surface of the cylinder faces the inner side of the bottom plate edge, and the top plate is hooked with the bottom plate edge instead of the latch, so the straight wall fixed on the bottom plate There is no need to attach a latch to the outer periphery of the lower part of the tube.

(Claim 3)
If the outer diameter of the top plate is made larger than the outer diameter of the bottom plate, the earth pressure applied to the top plate can be increased, and the manhole can be further prevented from rising and rising.

(About claim 4)
The levitation prevention manhole structure has a communicating hole in the plate edge of the bottom plate, a short pipe is attached to the communicating hole in a watertight manner, the lower end of the pipe is fitted into the short pipe, and the opening at the upper end of the pipe faces the upper part of the manhole. A drain pipe is attached in the same way.

The above-mentioned anchor effect (the bottom is heavy due to the weight increase due to the crushed stone foundation), the lower end of the pipe is fitted into a short pipe, and the opening of the upper end of the pipe faces the upper part of the manhole. Even if it is liquefied, it is difficult to lift, and it is possible to prevent push-up.
In addition, since the short pipes are watertightly attached to the communication holes of the bottom plate and the drain pipes are watertightly attached to the respective short pipes, the water level in the drain pipe is normally located below the upper opening. No groundwater is discharged from the upper opening into the manhole.

(Claim 5)
The watertight attachment of the short pipe to the communication hole is performed as follows.
A cylindrical rubber joint having a small-diameter cylindrical portion, a large-diameter portion, a large-diameter cylindrical portion, and a flange portion is fitted into the short tube, and the small-diameter cylindrical portion is tightened to the short tube end portion with a fastener.
The fastening body (plurality) is fitted into the communication hole (plurality) of the bottom plate from the upper side of the bottom plate.
When the wedge tube is driven from above the bottom plate into the gap between the large-diameter cylindrical portion of the cylindrical rubber joint and the outer peripheral surface of the short tube, the cylindrical rubber joint expands in the communication hole, and the cylindrical rubber joint can be fixed to the communication hole in a watertight manner.
Fit the lower end of the drain pipe into the wedge pipe.

Manhole straight wall cylinders and bottom plates can be manufactured, and short pipes can be installed in communication holes, not at the construction site but at the factory. Further, at the construction site, it is only necessary to connect the tip of the drain pipe to the short pipe attached to the communication hole, so that the drain pipe can be easily set up from the bottom plate at the construction site.
For this reason, on-site work can be simplified (construction is easy), and construction costs can be reduced. In addition, since the number of members to be assembled on site can be reduced, the number of construction steps for work performed on site can be reduced.

(About claim 6)
The levitation prevention manhole structure of claim 6 is the levitation prevention manhole structure of claims 4 and 5, in which a drain material is arranged directly below the communication hole instead of crushed stone.
The anti-lifting manhole structure in which the drain material is arranged prevents ground water from being filtered by the drain material and entering the drain pipe, thereby preventing problems such as the drain pipe being clogged with foreign material and the foreign material flowing into the manhole.

(About claim 7)
The bottom plate has a plurality of drain holes penetrating vertically, and is installed at the bottom of the shaft.
In a drain container in which a filtering material is sealed in a container, the lower end surface of the container is fixed to the upper surface of the bottom plate inward from the plate end of the bottom plate. In addition, a drain container exhibits the shape which reversed the bottomed cylindrical body with the short length of a cylindrical part.
The crushed stone foundation is formed by placing a large number of crushed stones on a bottom plate structure in which a drain container is fixed to the bottom plate.
The bottom plate is installed on the crushed stone foundation.

The straight wall cylinder is fixed on the bottom plate so that the bottom surface of the cylinder faces the inside of the bottom plate edge.
The top plate with a hole has a hole that can be loosely fitted into the straight wall cylinder, and is fitted into the straight wall cylinder and placed on the bottom plate.
The fixing means connects and fixes the top plate to the bottom plate.
The drain pipe is fixed at the lower end of the pipe to the drain container so that the lower end opening communicates with the drain container, passes through the top plate and faces upward, and the upper end of the pipe is directly adjusted so that the upper end opening communicates with the straight wall cylinder. It is fixed to the wall tube.

  In addition to the anchor effect that the bottom is heavy due to the weight increase due to the crushed stone foundation, the levitation prevention manhole structure adheres the container lower end surface of the drain container in which the filter material is enclosed in the container to the upper surface of the bottom plate inward from the plate end of the bottom plate, Fix the lower end of the pipe to the drain container so that the lower end opening of the drain pipe communicates with the drain container, pass through the top plate and face upward, and connect the upper end of the pipe to the straight wall so that the upper end opening communicates with the straight wall cylinder It has a structure that is fixed to a cylinder.

For this reason, when the ground is liquefied by an earthquake, groundwater enters the drain vessel through the drain hole in the bottom plate, is filtered by the filter medium, and enters the manhole through the drain pipe. In addition, since the groundwater filtered with the filter material enters the manhole, sludge and the like are not allowed to flow into the downstream sewage facility.
Thereby, even if the ground is liquefied, it is difficult for the manhole to be lifted, and the manhole can be prevented from being lifted and lifted. Normally, the water level in the drain pipe is located below the upper end opening, and groundwater is not discharged from the upper end opening of the drain pipe into the manhole.
In addition, since the drain container which enclosed the filtering material in the container is employ | adopted, while being able to increase the quantity of a filtering material, the loss of the filtering material can be prevented.

(About claim 8)
The levitation prevention manhole structure covers the pipe outer wall with a plurality of water collection holes with a filter medium, and connects the base end of the sub drain pipe with the closed end connected to the drain pipe at a position below the upper end opening. ing.
When the ground is liquefied by an earthquake, pore water (groundwater) around the straight wall tube can be drained into the manhole straight wall tube through the water collecting hole through the filter medium and into the sub drain pipe. Therefore, it is difficult for the manhole to rise, and the manhole can be prevented from rising and rising.
In normal times, the water level in the sub-drain pipe is located below the upper end opening, so that groundwater is not discharged into the manhole via the sub-drain pipe.
In addition, since the outer wall of the pipe is covered with the filtering material, it is possible to prevent problems such as the sub-drain pipe being clogged with foreign matter and the foreign matter flowing into the manhole.

(About claim 9)
The anti-levitation manhole structure has no top plate and no fixing means, so that the structure is simple and the material cost can be saved.
Although there is no anchor effect due to the top plate, when the ground is liquefied by an earthquake, the pore water (ground water) around the straight wall cylinder and the ground water below the bottom plate can be drained into the straight wall cylinder of the manhole. Can prevent the manhole from rising and rising.

  The levitation prevention manhole structure forms a crushed stone foundation by placing a large number of crushed stones on the plate, the bottom plate installed at the bottom of the shaft, the bottom plate installed on the crushed stone foundation, and the cylinder lower surface inside the bottom plate edge A straight wall cylinder fixed on the bottom plate so as to face, a top plate with a hole fitted into the straight wall cylinder and placed on the bottom plate, and a fixing means for connecting and fixing the top plate to the bottom plate, And a drain pipe attached to the bottom plate in a watertight manner so that the opening at the upper end of the pipe faces the upper part of the manhole.

  This levitation-preventing manhole structure is difficult to lift due to the anchor effect (the bottom of the manhole is heavy), and when the ground liquefies due to an earthquake, groundwater enters the manhole through the drain pipe and can prevent levitation.

Manufacture of straight wall cylinders and bottom plates of manholes and installation of short pipes in communication holes can be performed at the factory. Further, at the construction site, it is only necessary to connect the tip of the pipe to a short pipe disposed in the communication hole, so that the drain pipe can be easily set up.
For this reason, on-site work can be simplified (construction is easy), and construction costs can be reduced. In addition, since the number of members to be assembled on site can be reduced, the number of construction steps for work performed on site can be reduced.

A first embodiment (corresponding to claims 2 to 6) of the present invention will be described with reference to FIGS.
The levitation prevention manhole structure A includes a bottom plate 2 installed at the bottom of the shaft 10, a large number of crushed stones 21 which are placed on the plate and constitute the crushed stone foundation 20, a bottom plate 3 placed on the crushed stone foundation 20, and a bottom plate. 3, a straight wall cylinder 31 fixed to 3, a top plate 4 fitted into the straight wall cylinder 31 and placed on the bottom plate 3, a drain pipe 5 standing from the bottom plate 3, and the top plate 4 to the bottom plate 3. And a rod-like fixture 40 (fixing means) to be connected and fixed.

  The bottom plate 2 installed at the bottom of the shaft 10 is made of a metal such as iron and has a number of small holes (drain holes) smaller than bolt holes (four pieces) and the crushed stone 21. The bottom plate 2 forms a crushed stone foundation 20 by placing a large number of crushed stones 21 on the plate.

The bottom plate 3 (made of concrete) placed on the crushed stone foundation 20 has a disc shape, and three communication holes 32 are separated by 120 ° and opened at the bottom plate edge near the inner wall of the straight wall cylinder 31. Yes.
A cylindrical rubber joint 53 is fitted into each communication hole 32, a wedge tube 54 is press-fitted into the cylindrical rubber joint 53, and short tubes 51 (three in total) are fitted into the wedge tube 54.

The straight wall cylinder 31 is impregnated and bonded to the bottom plate 3 in a watertight manner using a metal fitting, an adhesive, or the like.
The top plate 4 (made of metal such as iron) has a bolt hole (four pieces) and a hole 41 that can be loosely fitted into the straight wall cylinder 31. Placed on.
If the outer diameter of the top plate is made larger than the outer diameter of the bottom plate, the earth pressure applied to the top plate can be increased, and the manhole can be further prevented from rising and rising.

  The rod-shaped fixture 40 includes anchor bolts 43 and nuts 44 that are fitted into the respective bolt holes. By tightening the nuts 44, the top plate 4 and the bottom plate 2 are connected and fixed.

  Three drain pipes 5 (made of resin) standing from the bottom plate 3 have lower ends fitted into the short pipe 51, and an opening 52 (upper end opening) facing inward is disposed above the groundwater level.

Next, a construction method of the levitating prevention manhole structure A will be described.
<Factory work>
The bottom plate 3 is manufactured at a factory as shown in FIGS.
As shown in FIG. 3A, three communication holes 32 are opened in the bottom plate edge portion of the bottom plate 3 with an interval of 120 °. When the straight wall cylinder 31 is lowered at the site, the communication hole 32 is opened at a position close to the inner wall of the straight wall cylinder 31.

  The cylindrical rubber joint 53 includes a small-diameter cylindrical portion 53a having an inner diameter substantially equal to the outer diameter of the short tube 51, a large-diameter portion 53b in which the inner and outer diameters expand, a large-diameter cylindrical portion 53c, and a rod for hooking into the hole rod. Part 53d. The cylindrical rubber joint 53 is fitted into the short pipe 51, and the small-diameter cylindrical part 53a is fastened to the short pipe end part 51a with a stainless steel band 53e (fastening tool). This fastening body is fitted into the communication hole 32 from the upper side of the bottom plate {see (b) of FIG. 3}.

  The wedge tube 54 is hit with a hammer or the like, and the wedge tube 54 is press-fitted into the cylindrical portion of the cylindrical rubber joint 53 {see (c) of FIG. 3}. Thereby, the cylindrical rubber joint 53 is water-tightly joined to the communication hole 32 of the bottom plate 3.

<Work on site>
The bottom plate 2 in which the anchor bolts 43 are fitted in the bolt holes is transported to the site together with the straight wall cylinder 31 and the drain pipe 5 by a truck or the like.
The bottom plate 2 is hung with a rope and lowered into the shaft 10 from the shaft opening, and is installed on the bottom of the shaft 10 as shown in FIG.

  As shown in FIG. 2B, a large number of crushed stones 21 are placed in the bottom plate 2 from the shaft opening to make a flat crushed stone foundation 20. In addition, the drain material 22 for filtering groundwater is previously arrange | positioned to the position where each communicating hole 32 faces, when the baseplate 3 is mounted instead of the crushed stone 21. FIG.

  At the factory, the bottom plate 3 in which the wedge tube 54 is press-fitted into the cylindrical portion of the cylindrical rubber joint 53 is transported to the construction site, lowered from the shaft opening into the shaft 10, and the bottom plate 3 is placed on the crushed stone base 20 {FIG. → (c) in FIG.

  As shown in FIG. 2 (d), the straight wall cylinder 31 is inserted into the shaft 10 from the shaft opening and placed on the bottom plate 3, and the straight wall tube 31 is fixed to the bottom plate 3 {(d) of FIG. reference}.

The top plate 4 having the hole 41 that can be loosely fitted into the straight wall cylinder 31 is fitted into the straight wall cylinder 31 and placed on the bottom plate 3 {see FIG. 2 (e)}.
The nut 44 is tightened, and the top plate 4 and the bottom plate 2 are connected and fixed {see (f) of FIG. 2}.
The drain pipe 5 is lowered into the straight wall cylinder 31 from the shaft opening, and the drain pipe 5 is inserted into the pipe of the short pipe 51 (see FIG. 3E).

The levitating prevention manhole structure A of the present embodiment has the following advantages.
[A] The ascent prevention manhole structure A uses a large number of crushed stones 21 in the bottom plate 2 installed at the bottom of the shaft 10 to form a crushed stone foundation 20, and a short pipe 51 is watertightly attached to a communication hole 32 opened in the bottom plate edge. The bottom plate 3 is placed on the crushed stone foundation 20, the straight wall cylinder 31 is fixed to the bottom plate 3, and the top plate 4 and the bottom plate 2 are connected and fixed by tightening the nut 44 of the rod-shaped fixture 40. The bottom of the manhole can be made heavy and an anchor effect can be obtained.
Furthermore, since the lower end of the drain pipe 5 is connected to the short pipe 51 and the opening 52 faces the upper part of the manhole, groundwater enters the manhole through the drain pipe 5 when the ground is liquefied by an earthquake. Therefore, even if the ground is liquefied, it is difficult for the manhole to lift, and the manhole can be prevented from being lifted and lifted.

  In addition, since the short pipe 51 is watertightly attached to each communication hole 32 of the bottom plate 3 and the drain pipe 5 is watertightly attached to each short pipe 51, the water level in the drain pipe 5 is normally upward. Located below the opening, groundwater is not discharged from the upper opening of the drain pipe 5 into the manhole.

[I] The anti-floating manhole structure A performs the manufacture of the straight wall cylinder 31 and the bottom plate 3 and the attachment of the short pipe 51 to the communication hole 32 at the factory. At the site, the bottom plate 3 with the short pipe 51 attached to the communication hole 32 is placed on the crushed stone foundation 20, the straight wall cylinder 31 is placed on the bottom plate 3 and fixed, and the nut 44 of the rod-shaped fixture 40 is attached. By tightening, the top plate 4 and the bottom plate 2 are connected and fixed, and the drain pipe 5 is inserted into the short tube 51.

  Since preparations such as the formation of the communication hole 32 and the attachment of the short pipe 51 are performed at the factory, on-site construction is simplified and the on-site construction can be performed with a small number of processes. In addition, the number of members assembled on site can be reduced. Therefore, the construction period is short and the construction cost is low.

[U] In the levitating manhole structure A, the outer diameter of the top plate 4 is larger than the outer diameter of the bottom plate 2, so that the earth pressure applied to the top plate 4 can be increased. For this reason, compared with the case where the outer diameter of the top plate 4 is the same as the outer diameter of the bottom plate 2, the anti-lifting manhole structure A can further prevent the manhole from being lifted and levitated.

[E] In the manhole structure A for preventing levitation, a drain material 22 is disposed immediately below the communication hole 32 in place of the crushed stone 21. For this reason, when the ground is liquefied, the ground water is filtered by the drain material 22 and enters the drain pipe 5, so that it is possible to prevent the drain pipe 5 from being clogged with foreign substances or flowing into the manhole.

  Next, a second embodiment (corresponding to claim 2) of the present invention will be described with reference to FIGS. The levitation preventing manhole structure B includes a bottom plate 6 installed at the bottom of the vertical shaft 10, a bottom plate 7 serving as a manhole bottom, a straight wall cylinder 31 fixed on the bottom plate 7, and a top plate placed on the bottom plate 7. 8 and a rod-shaped fixture 9 (fixing means) for fixing the top plate 8 to the bottom plate 6.

The bottom plate 6 (made of iron) includes a disc portion (outer diameter φ130 cm) larger than the bottom plate 7 and a cylindrical portion rising from the edge of the disc portion. A large number of drain holes 60 and bolt holes 61 (four) for passing the rod-shaped fixture 9 are formed in the disc portion of the bottom plate 6.
A large number of crushed stones 21 larger than the drain holes 60 are placed in the cylindrical portion of the bottom plate 6 to form a crushed stone foundation 20 (20 cm thick) having a flat upper surface.

The bottom plate 7 (made of concrete; outer diameter φ110 cm) has a disk shape with a wall thickness (13 cm) and is horizontally installed on the crushed stone foundation 20.
The top plate 8 (made of iron; outer diameter φ150 cm) has an annular shape having a fitting hole 81 (hole; φ106 cm) that is smaller than the outer diameter of the bottom plate 7 and larger than the outer diameter of the straight wall cylinder 31. The top plate 8 is lowered from the upper side of the shaft 10 while being loosely fitted to the straight wall cylinder 31 and placed on the bottom plate 7. In addition, the bolt hole 82 (four pieces) for letting the anchor bolt 90 pass is formed in the plate surface.

  The rod-shaped fixture 9 has a bolt head 91 welded to the lower surface of the bottom plate 6 around the bolt hole 61, an anchor bolt 90 (4-M32) through which the male screw portion 92 penetrates the bolt hole 82 of the top plate 8, and a male screw. The nut 92 is screwed into the portion 92.

Next, a construction method of the levitating prevention manhole structure B will be described.
(1) Excavate the shaft 10 for burying the manhole structure B that is not levitated.
(2) The bottom plate 6 with the drain hole 60 welded to the anchor bolt 90 is lowered into the shaft 10 from the shaft opening and placed on the shaft bottom {see (a) of FIG. 5}. The bolt head 91 of the anchor bolt 90 is previously welded to the bottom surface of the bottom plate 6 around the bolt hole 61 at the factory.

(3) A large number of crushed stones 21 are introduced into the cylindrical portion of the bottom plate 6 to form a crushed stone foundation 20 having a flat upper surface {see FIG. 5 (b)}.
(4) Install the bottom plate 7 on the crushed stone foundation 20 {see (c) of FIG. 5}.

(5) The straight wall cylinder 31 is lowered from the shaft opening into the shaft 10 and placed on the bottom plate 7 and fixed. The straight wall cylinder 31 is fixed by using an adhesive or a plurality of mounting brackets and water-tightly impregnating and bonding to the bottom plate 7 so that the lower cylinder surface faces the inner side of the bottom plate edge {see FIG. 5 (d)} . The straight wall cylinder 31 is manufactured in advance at a factory.

(6) The top plate 8 having a fitting hole 81 that is smaller than the outer diameter of the bottom plate 7 and larger than the outer diameter of the straight wall cylinder 31 is lowered from the upper side of the shaft 10 to the straight wall cylinder 31 in a loose fitting state. 7 (see (e) of FIG. 5).
(7) A nut 93 is screwed into the male screw portion 92 protruding from the bolt hole 82 of the top plate 8, and the top plate 8 is fixed to the bottom plate 7 (see FIG. 5 (f)).

[O] Lifting prevention manhole structure B is lifted and lifted because resistance due to earth pressure is applied to the top plate 8 in addition to an increase in weight due to the formation of the crushed stone foundation 20 by placing a large number of crushed stones 21 on the bottom plate 6. Can be prevented.
The amount of the crushed stone 21 (height of the crushed stone foundation 20) and the size of the top plate 8 are adjusted according to the kind of soil in which the ascent prevention manhole structure B is embedded. For example, in the case of soil that is likely to be pushed up and lifted, the amount of crushed stone 21 is increased and the top plate 8 is enlarged.

[Ka] In the manhole structure B for preventing levitation, the top plate 8 with the fitting hole 81 is lowered from above the shaft 10 into a loosely fitted state and placed on the bottom plate 7, and the top plate 8 is attached by the anchor bolt 90 and the nut 93. Since the structure is fixed to the bottom plate 6, a hook for fixing the top plate 8 to the straight wall cylinder 31 is unnecessary.

Next, a third embodiment (corresponding to claim 7) of the present invention will be described with reference to FIG.
As shown in FIG. 8, the ascent prevention manhole structure C includes a bottom plate 2 installed at the bottom of the shaft 10, a drain vessel 23 in which a filtering material 23 a is sealed in the vessel, and a bottom plate structure in which the drain vessel 23 is welded to the bottom plate 2. A crushed stone foundation 20 in which a large number of crushed stones 21 are placed on a body 24 to form a concave shape, a bottom plate 3 embedded in the crushed stone foundation 20, a straight wall cylinder 31 fixed on the bottom plate 3, and a straight wall A top plate 4 that is fitted into the cylinder 31 and placed on the bottom plate 3, a drain pipe 5 (four pieces) having a pipe lower end 55 fixed to the drain container 23, and a pipe upper end 56 fixed to the straight wall cylinder 31. And a bar-like fixture 40 (fixing means) for connecting and fixing the top plate 4 to the bottom plate 2.

The bottom plate 2 (disc shape) is formed of a metal such as iron and has bolt holes 25 (four pieces) and a large number of small holes 26 (drain holes) smaller than the crushed stone 21.
A drain container 23 (bottomed cylindrical shape) having a diameter smaller than that of the bottom plate 2 is formed of metal such as iron, and the lower end surface 27 of the container is welded to the upper surface of the bottom plate inward from the plate end of the bottom plate 2. In the drain container 23, a filtering material 23a is enclosed.

The bottom slab 3 (made of concrete) having a smaller diameter than the drain container 23 is a thick disk, and is embedded in the recess of the crushed stone foundation 20 so that the bottom slab surface is exposed.
The cylindrical straight wall cylinder 31 is impregnated and bonded to the bottom plate 3 at a position where the bottom surface of the cylinder is on the inner side of the bottom plate edge using a metal fitting, an adhesive, or the like.

The top plate 4 (made of metal such as iron) has bolt holes h (four pieces) and a hole 41 that can be loosely fitted into the straight wall cylinder 31, and the bottom plate 3 is fitted into the straight wall cylinder 31. Placed on top.
The rod-shaped fixture 40 includes anchor bolts 43 and nuts 44 that are fitted into the bolt holes 25 and h, and the top plate 4 and the bottom plate 2 are connected and fixed by tightening the nuts 44.

  The drain pipe 5 (four pipes; made of resin) has an opening 57 (lower end opening) communicating with the inside of the drain container 23, standing up through the top plate 4, and opening 52 (upper end opening) at a position above the groundwater level. Is communicated with the direct wall 31.

The floating prevention manhole structure C of the present embodiment has the following advantages.
[G] The levitation prevention manhole structure C has an anchor effect that the bottom is heavy due to the weight increase due to the crushed stone foundation 20, and the container lower end surface 27 of the drain container 23 in which the filter medium 23 a is enclosed in the container from the plate end of the bottom plate 2. The pipe bottom end 55 is fixed to the drain container 23 so that the lower end opening of the drain pipe 5 communicates with the inside of the drain container, and passes through the top plate 4 so as to face upward. The pipe upper end 56 is fixed to the straight wall cylinder 31 so as to communicate with the wall cylinder 31.
For this reason, when the ground is liquefied by the earthquake, the groundwater enters the drain vessel 23 through the drain hole 26 of the bottom plate 2, is filtered by the filtering material 23 a, passes through the drain pipe 5 and enters the manhole. In addition, since the groundwater filtered with the filter medium 23a enters the manhole, sludge and the like are not allowed to flow into the downstream sewage facility.
Thereby, even if the ground is liquefied, it is difficult for the manhole to be lifted, and the manhole can be prevented from being lifted and lifted. In normal times, the water level in the drain pipe 5 is located below the upper opening, and groundwater is not discharged from the opening 52 of the drain pipe 5 into the manhole.
In addition, since the drain container 23 in which the filter medium 23a is sealed in the container is employed, the amount of the filter medium 23a can be increased, and the loss of the filter medium 23a can be prevented.

Next, a fourth embodiment (corresponding to claim 8) of the present invention will be described with reference to FIG.
As shown in FIG. 9, the levitation prevention manhole structure D includes a bottom plate 2 installed at the bottom of the shaft 10, a drain container 23 in which a filtering material 23 a is sealed in the container, and a bottom plate structure in which the drain container 23 is welded to the bottom plate 2. A crushed stone foundation 20 in which a large number of crushed stones 21 are placed on a body 24 to form a concave shape, a bottom plate 3 embedded in the crushed stone foundation 20, a straight wall cylinder 31 fixed on the bottom plate 3, and a straight wall A top plate 4 that is fitted into the cylinder 31 and placed on the bottom plate 3, a drain pipe 5 (three pieces) having a pipe lower end 55 fixed to the drain container 23, and a pipe upper end 56 fixed to the straight wall cylinder 31. , A rod-shaped fixture 40 (fixing means) for connecting and fixing the top plate 4 to the bottom plate 2 and a sub-drain pipe in which the base end 72 is connected to and connected to the drain pipe 5 at a position below the opening 52 (upper end opening). 71, 71.

  The auxiliary drain pipes 71 (six pipes in total) face the drain pipes 5 and cover the outer walls of the pipes arranged in parallel two by two with a plurality of water collecting holes 73 covered with the filter material 74 to block the tips. ing.

The levitating prevention manhole structure D of the present embodiment has the following advantages.
[6] The levitation prevention manhole structure D is configured such that the outer wall of the pipe having a plurality of water collecting holes 73 is covered with a filtering material 74, and the base ends 72 of the sub-drain pipes 71 and 71 whose ends are blocked are formed at the upper end opening 52. It is connected to and connected to the drain pipe 5 at a lower position.
When the ground liquefies due to the earthquake, pore water (groundwater) around the straight wall cylinder 31 enters the sub-drain pipes 71 and 71 from the water collecting hole 73 through the filter medium 74, and directly into the manhole. Since the water can be drained into the wall cylinder 320, it is difficult for the manhole to be lifted, and the manhole can be further prevented from being lifted and lifted.
In normal times, the water level 70 in the sub-drain pipes 71 and 71 is located below the opening 52, so that groundwater is not discharged into the manhole via the sub-drain pipes 71 and 71.
In addition, since the outer wall of the pipe is covered with the filtering material 74, it is possible to prevent problems such as the auxiliary drain pipes 71 and 71 being clogged with foreign matter and the foreign matter flowing into the manhole.

Next, a fifth embodiment (corresponding to claim 9) of the present invention will be described with reference to FIG.
As shown in FIG. 10, the ascent prevention manhole structure E includes the top plate 4 and the rod-like fixture 40 (fixing means) omitted from the ascent prevention manhole structure D, and has two drain pipes 5 facing each other. Two sub-drain pipes 71 are arranged in parallel.

The levitation prevention manhole structure E has no top plate 4 and no rod-like fixture 40, so that the structure is simple and the material cost can be saved.
Although there is no anchor effect by the top plate 4, when the ground is liquefied by an earthquake, pore water (ground water) around the straight wall tube 31 and ground water below the bottom plate can be drained into the straight wall tube 320 of the manhole. Therefore, it is difficult for the manhole to lift up, and the manhole can be prevented from being lifted and lifted up.

(Modification 1; corresponding to claim 1)
A plurality of L-shaped metal fittings 37 (holding fixtures) are attached with bolts 36 to the lower outer periphery of the straight wall cylinder 31 fixed on the bottom plate 7 with the attachment metal fittings 35 and the like, and a fitting hole 81 (hole) larger than the straight wall cylinder 31 is provided. The top plate 8 may be fitted and placed on the L-shaped bracket 37, and the top plate 8 may be fixed to the bottom plate 6 with anchor bolts 90 and nuts 93 (see FIG. 6).

(Modification 2; corresponding to claim 2)
In the second embodiment shown in FIG. 4, the bottom plate 6 and the top plate 8 may be fixed by welding the iron plate 94 without using the rod-shaped fixture 9 (see FIG. 7).

(Modifications 3 and 4)
The number of rod-shaped fixtures 9 and 40 (fixing means) is not limited to four and is arbitrary.
Further, the number of communication holes 32 is not limited to three and is arbitrary.

The manhole that is used to prevent ascent may be an on-site manhole.
The bottom plate and the straight wall cylinder are not limited to a circular cross section, and may be a square cross section.
A crushed stone or a filter medium may be laid under the bottom plate. In this case, it is not necessary to arrange the filter medium in the drain container.

The number of drain pipes in claims 4, 5, 7, 8, and 9 and the number of sub-drain pipes connected to the drain pipes in claims 8 and 9 are arbitrary.
A water collecting hole may be formed at the end of the closed sub drain pipe.

It is sectional drawing which shows the levitation prevention manhole structure which concerns on Example 1. FIG. It is process drawing which shows the construction on the spot of the anti-levitation manhole structure which concerns on Example 1. FIG. It is process drawing which shows the assembly in the factory of the floating prevention manhole structure which concerns on Example 1. FIG. It is sectional drawing which shows the levitation prevention manhole structure which concerns on Example 2. FIG. It is process drawing which shows the construction on the spot of the anti-levitation manhole structure which concerns on Example 2. FIG. It is sectional drawing which shows the levitation prevention manhole structure which concerns on the modification 1. FIG. It is sectional drawing which shows the levitation prevention manhole structure which concerns on the modification 2. FIG. It is sectional drawing which shows the levitation prevention manhole structure which concerns on Example 3. FIG. It is sectional drawing which shows the levitation prevention manhole structure which concerns on Example 4. FIG. It is sectional drawing which shows the levitation prevention manhole structure which concerns on Example 5. FIG.

Explanation of symbols

A, B, C, D, E Lifting prevention manhole structure 2, 6 Bottom plate 3, 7 Bottom plate 4, 8 Top plate 5 Drain pipe 10 Shaft 20 Crushed stone foundation 21 Crushed stone 22 Drain material 23 Drain container 31 Straight wall cylinder 32 Communication hole 37 L-shaped bracket (Hook)
9, 40 Bar-shaped fixture (fixing means)
41 hole 51 short tube 52 opening (top opening)
53 Cylindrical rubber joint 53a Small-diameter cylindrical portion 53b Large-diameter portion 53c Large-diameter cylindrical portion 53d Gutter portion 53e Stainless steel band 54 Wedge tube 57 Opening (lower end opening)
60 Water drain hole 70 Water level 71 Sub drain pipe 72 Base end 73 Water collecting hole 74 Filter material 81 Insertion hole (hole)

Claims (9)

A bottom plate with a drain hole that is installed at the bottom of the shaft and has a crushed stone foundation by placing a large number of crushed stones on the plate,
A bottom plate installed on a crushed stone foundation;
A straight-walled cylinder fixed on the bottom plate and attached to multiple places on the outer periphery of the lower part,
A top plate with a hole that has a hole that can be loosely fitted to the straight wall cylinder, is fitted to the straight wall cylinder, and is fixed to the latch or placed on the latch;
An anti-levitation manhole structure comprising fixing means for connecting and fixing the top plate to the bottom plate. A bottom plate with a drain hole that is installed at the bottom of the shaft and has a crushed stone foundation by placing a large number of crushed stones on the plate,
A bottom plate installed on the crushed stone foundation, a straight wall tube fixed on the bottom plate so that the bottom surface of the cylinder faces the inside of the bottom plate edge,
A top plate with a hole that has a hole that can be loosely fitted into the straight wall cylinder, is fitted into the straight wall cylinder, and is placed on the bottom plate;
An anti-levitation manhole structure comprising fixing means for connecting and fixing the top plate to the bottom plate.   The floating prevention manhole structure according to claim 1 or 2, wherein an outer diameter of the top plate is made larger than an outer diameter of the bottom plate. Drilling a communication hole in the plate edge of the bottom plate,
A short pipe is attached to the communication hole in a watertight manner,
4. A floating prevention manhole according to any one of claims 1 to 3, wherein a drain pipe is attached so that a lower end of the pipe is fitted into the short pipe and an opening of the upper end of the pipe faces an upper portion of the manhole. Construction. A cylindrical rubber joint having a small-diameter cylindrical portion, a large-diameter portion, a large-diameter cylindrical portion, and a flange portion is fitted into the short tube, and the small-diameter cylindrical portion is tightened to the short tube end with a fastener,
The fastening body is fitted into the communication hole from the upper side of the bottom plate,
Driving the wedge tube from the upper side of the bottom plate into the gap between the large cylindrical portion and the outer peripheral surface of the short tube,
5. The anti-levitation manhole structure according to claim 4, wherein a lower end of the drain pipe is fitted into a wedge pipe.   6. The anti-levitation manhole structure according to claim 4 or 5, wherein a drain material is disposed directly below the communication hole instead of the crushed stone. A plurality of drain holes penetrating vertically, a bottom plate installed at the bottom of the shaft,
A drain container in which a container lower end surface is fixed to an inner bottom plate upper surface from an end of the bottom plate, and a filtering material is sealed in the container;
A crushed stone foundation formed by placing a large number of crushed stones on a bottom plate structure in which the drain vessel is fixed to the bottom plate;
A bottom plate embedded in a crushed stone foundation so that the bottom plate surface is exposed;
A straight wall cylinder fixed on the bottom plate such that the bottom surface of the cylinder faces the inside of the bottom plate edge;
A top plate with a hole that has a hole that can be loosely fitted into the straight wall cylinder, is fitted into the straight wall cylinder, and is placed on the bottom plate;
Fixing means for connecting and fixing the top plate to the bottom plate;
The lower end of the pipe is fixed to the drain container so that the lower end opening communicates with the drain container, passes through the top plate, faces upward, and the upper end of the pipe communicates with the straight wall cylinder. An anti-levitation manhole structure comprising a drain pipe fixed to a wall cylinder.   The outer wall of the pipe having a plurality of water collecting holes is covered with a filter medium, and the base end of the sub-drain pipe whose tip is closed is connected to and communicated with the drain pipe at a position below the upper end opening. The levitating prevention manhole structure according to claim 7. A plurality of drain holes penetrating vertically, a bottom plate installed at the bottom of the shaft,
A drain container in which a container lower end surface is fixed to an inner bottom plate upper surface from an end of the bottom plate, and a filtering material is sealed in the container;
A crushed stone foundation formed by placing a large number of crushed stones on a bottom plate structure in which the drain vessel is fixed to the bottom plate;
A bottom plate embedded in a crushed stone foundation so that the bottom plate surface is exposed;
A straight wall cylinder fixed on the bottom plate such that the bottom surface of the cylinder faces the inside of the bottom plate edge;
A drain pipe having a pipe lower end fixed to the drain container such that a lower end opening communicates with the drain container, and a pipe upper end fixed to the straight wall cylinder such that an upper end opening communicates with the straight wall cylinder. ,
The outer wall of the pipe having a plurality of water collecting holes is covered with a filter medium, and the base end of the sub-drain pipe whose tip is closed is connected to and communicated with the drain pipe at a position below the upper end opening. Anti-levitation manhole structure.

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