JP4603852B2 - Structure to prevent floating of buried objects - Google Patents

Description

  TECHNICAL FIELD The present invention relates to a buried object floating prevention structure in which underground buried objects such as sewer manholes and common grooves prevent levitation of manholes and common grooves due to ground liquefaction during an earthquake.

  In the event of an earthquake, ground liquefaction may occur, and underground objects such as manholes may surface due to liquefaction. The reason for the levitation is that the apparent specific gravity of the manhole is small, so that it rises according to the degree of liquefaction. When the manhole rises, there is a problem that not only the flow gradient of the sewage pipe line is damaged, but also the function of the pipe line is lost when the levitation is severe.

Conventionally, in order to prevent the manhole or the like from rising, there are a method of surrounding the bottom and sides of the manhole with a material such as crushed stone, and a method of applying a drain to the ground to suppress an increase in excess pore water pressure.
In the technique disclosed in Japanese Patent Application Laid-Open No. 8-170349 (hereinafter referred to as Patent Document 1), a water passage hole for allowing outside water to flow into the manhole is provided on the peripheral wall of the manhole, and the backfilling soil around the manhole is filled. A geotextile is buried around the manhole and surrounding the manhole and backfill soil. And the backfill earth and sand is fully compacted between the geotextile and the manhole.
In this technology, the water in the ground contained in the backfilling soil flows into the manhole through the water passage hole, so the ground is compacted, but even if the pore water pressure in the ground increases due to vibration during an earthquake, the manhole Liquefaction hardly occurs around the earth, and even if liquefaction occurs, the earth and sand surrounded by the geotextile is prevented from flowing, and these interactions prevent the manhole from rising.
JP-A-8-170349

However, the conventional construction method requires a large-scale construction and is expensive, and cannot be applied to an existing manhole. In addition, the method of providing a hole in the wall portion of the manhole has a problem that sand from the outside flows into the manhole when a liquefaction phenomenon occurs.
This invention is made | formed in view of such a situation, Comprising: It can attach to the bottom wall part or side surface of underground buried objects, such as a manhole, by the small-scale construction from the inside (or the exterior) of a buried object. It is a structure that can be incorporated into the product when it is manufactured, and prevents the increase of excess pore water pressure in the ground during the liquefaction phenomenon, and allows the earth and sand outside the underground object to flow into the underground object An object of the present invention is to provide a structure for preventing the floating of buried objects.

The present invention, in order to achieve the above object, buried in the ground, or manhole before being buried in the ground (hereinafter, simply referred to manhole) and within said manhole and underground side wall portion of the the forming a through hole communicating, to permit the flow of water from the ground side to the through hole into said manhole, blocking all times the flow of water into the ground side from the manhole check valve in buried object floating preventing structure were provided with the elastic member provided in the valve body of the check valve, so that the elastic member is opened the check valve against the constant pressure greater than that generated in the ground The check valve case includes an outer cylinder fixed to the through-hole, and an inner cylinder that is detachably attached to the outer cylinder and in which the valve body is provided. When replacing the check valve, remove only the inner cylinder from the manhole. It was configured to.
Further, the present invention forms a through hole communicating with the ground side and the manhole in the bottom wall of the manhole, allowing the flow of water from the ground side to the through hole into said manhole, said in buried object floating preventing structure in which the check valve is disposed to block at all times the flow of water into the ground side from the manhole, the valve body of the check valve is a heavy object placed on the flow path , together configured to open the check valve against above a certain pressure the valve member is generated in the ground, the casing of the check valve, an outer cylinder fixed to the through hole The inner cylinder is detachably attached to the outer cylinder and the valve body is provided therein, and only the inner cylinder can be removed from the manhole when the check valve is replaced .
Furthermore, the present invention forms a through hole communicating with the ground side and the manhole in the bottom wall of the manhole, allowing the flow of water from the ground side to the through hole into said manhole, said in buried object floating preventing structure of the check valve is disposed to block at all times the flow of water into the ground side from the manhole, the valve body of the check valve is a plug-like material that blocks the flow passage, together configured to open said check valve and said check valve and said valve body against a certain over pressure generated in the ground, the casing of the check valve, fixed to the through hole And an inner cylinder that is detachably mounted in the outer cylinder and in which the valve body is provided, and only the inner cylinder can be removed from the manhole when the check valve is replaced. It was configured as follows.
The said invention can provide the filter which interrupts | blocks the inflow of earth and sand on the said underground side of the said check valve, and can provide the holding | maintenance member which made the said check valve attachable / detachable in the said wall part.

According to the present invention, which is buried in the ground, or manhole to be buried, the a ground side and said manhole to form a through hole communicating with the walls of the joint groove such buried object, the through hole permits a flow of water into the manhole from the ground side, the buried object floating preventing structure of the check valve is disposed to block at all times the flow of water into the ground side from the manhole, said reverse an elastic member provided in the valve body of the stop valve, the elastic members against the constant pressure greater than that occurring in the ground and arranged to open the check valve, or the valve body of the check valve Is a heavy object placed in the flow passage, and the valve element is configured to open the check valve against a pressure exceeding a certain level generated in the ground, or the check valve The valve body is a plug-like material that closes the flow passage, and the check valve and the valve body are formed in the ground. The check valve is configured to open against the pressure described above, and the check valve case is detachably attached to the outer cylinder fixed to the through-hole and the outer cylinder. And, with the inner cylinder provided with the valve body inside, when replacing the check valve, so that only the inner cylinder can be removed from the manhole , even if a liquefaction phenomenon occurs due to an earthquake, The check valve is actuated to reduce manhole buoyancy and suppress manhole lift. Further, by disposing the filter check valve, Ru can be prevented from flowing a large sediment particles in the manhole.

Hereinafter, a first embodiment of a buried object floating prevention structure of the present invention will be described with reference to the drawings.
FIG. 1 shows a manhole 1 buried in the ground.
The manhole body 2 that is a concrete portion of the manhole 1 is configured by stacking, for example, cylindrical precast concrete blocks. The manhole body 2 is provided with a bottom slab 3 at the bottom, an invert block 4 is provided on the bottom slab 3, and a sewer pipe 5 (see FIG. 10) is connected to both ends of the invert 4a to circulate drainage.

  In the manhole body 2, a plurality of cylindrical body blocks 6 (one in the drawing) are stacked, and a cylindrical upper block 7 having one side inclined in a tapered shape is stacked thereon. A ring-shaped opening block 8 is placed on top of the upper block 7, and an upper lid 9 is fitted into the upper end opening of the opening block 8. The manhole body 2 has a side (circumferential) wall 2 a formed by the body block 6, the upper block 7 and the opening block 8, and the upper surface of the upper lid 9 is placed in the ground 11 so that the upper surface is at the same height as the ground surface 10. Buried.

The body block 6 is formed with a plurality of lateral holes 12 that allow the inside of the manhole body 2 and the underground 11 to communicate with each other. A plurality of vertical holes 13 penetrating the bottom plate 3 and the invert block 4 of the manhole body 2 and communicating the manhole body 2 and the underground 11 are formed. These holes 12 and 13 are provided in an arbitrary number at arbitrary positions according to the ground conditions. The shape is a circular cross section, but the shape such as a square is not particular.
In these horizontal holes 12 and vertical holes 13, a check valve 14 that allows water to flow from the underground 11 into the manhole body 2 and blocks the flow of water from the manhole body 2 to the underground 11 (see FIG. 2-9) is installed. The positions of the holes 12, 13, that is, the place where the check valve 14 is arranged, may be arranged at equal angular intervals in the side wall 2 a, for example, on the lower side. May be arranged, and the upper side may be arranged few. Further, at the bottom of the manhole body 2, it may be arranged in one row or two or more rows along both sides of the invert 4 a.

2 to 4 show the check valve 14 disposed in the manhole body 2. 2 is a plan view of the side of the check valve 14 disposed toward the manhole body 2, FIG. 3 is a cross-sectional view, and FIG. 4 is a side of the check valve 14 disposed toward the ground 11. 3 is a bottom view of the check valve 14. FIG.
The check valve 14 is provided with a cylindrical case 16 having an outer diameter substantially equal to the inner diameter of the horizontal hole 12 and the vertical hole 13, and a filter 17 having a large number of openings 17 a is provided on one end side of the case 16. . The size of the opening 17a and the size and shape of allowing the water to pass through without passing through the earth and sand having a particle size of a certain size or more. The valve structure of the check valve 14 includes a base 19 disposed on the other end side of the case 16, a valve body 20, a valve seat 21, and a spring 22. The valve body 20 is disposed so as to face the filter 17, and the periphery of the tip of the valve body 20 and the valve seat 21 can be brought into close contact with each other. The base 19 and the case 16 are fixed, and a drain port 19 a is formed in the base 19.

A spring 22 is provided between the base 19 and the valve body 20, and the valve body 20 is seated on the valve seat 21 by the urging force of the spring 22 in a no-load state in a normal state. When water enters from the filter 17 side and a large water pressure is applied to the valve seat 21, the check valve 14 is pressed toward the base 19 against the biasing force of the spring 22, and the valve body 20. And the valve seat 21 are separated and the valve is opened. When the check valve 14 is opened, water flows into the manhole body 2 from the underground 11. The spring constant of the spring 22 is set by the height of the manhole body 2, the hydrostatic pressure of pore water in the earth and sand of the land, the ground environment, and the like.
Specifically, with the manhole body 2 embedded, the check valve 14 does not open at the hydrostatic pressure that the manhole body 2 normally receives, and the check valve 14 is liquefied in the ground 11 due to an earthquake. Set the spring constant to the pressure at which. Further, in the body block 6 of the manhole body 2, the check valve 14 disposed below the check valve 14 disposed on the upper side has different pressures received at the respective positions due to the difference in height. It is preferable to set a large spring constant of the check valve 14 arranged.

  The check valve 14 can be incorporated into the manhole body 2 when the bottom plate 3 and the blocks 6 to 8 of the manhole body 2 are manufactured. For the existing manhole body 2 embedded in the ground 11, a horizontal hole 12 is made in the side wall 2 a of the manhole body 2 with a concrete cutter, and a check valve 14 is disposed in the side hole 12, and then mortar, etc. Thus, the check valve 14 and the lateral hole 12 are sealed and prevented from coming off. The same applies to the vertical hole 13.

Next, the operation of the present embodiment will be described.
Normally, the check valve 14 is loaded with a hydrostatic pressure or the like on the valve body 20, but the biasing force of the spring 22 of the check valve 14 is large, and the check valve 14 does not open.
When a liquefaction phenomenon occurs due to an earthquake or the like, a buoyancy force that lifts the manhole body 2 is applied to the manhole body 2, and liquefaction water pressure due to sediment flow is applied to the bottom plate 3 and the side wall 2 a of the manhole body 2. At this time, the water pressure applied to the valve body 20 is pressed against the urging force of the spring 22, so that the valve body 20 and the valve seat 21 are separated from each other, and the check valve 14 is opened. Then, the horizontal hole 12 and the vertical hole 13 communicate with the manhole body 2 and the underground 11 side, and water flows into the manhole body 2 from the underground 11 side. At this time, the opening 17a of the filter 17 serves as a sieve, and prevents inflow of large particles of earth and sand into the manhole body 2.
When the check valve 14 is opened, the buoyancy applied to the manhole body 2 is reduced. In addition, the water flowing into the manhole body 2 increases the apparent weight of the manhole body 2 and generates a force for suppressing the buoyancy. Therefore, the manhole body 2 is prevented from rising.

5 to 8 show modified examples of the check valve. In addition, the same code | symbol is attached | subjected about the thing of the same name as the said embodiment.
For the spring 22 of the check valve 14, both “pull type” and “compression type” can be applied.
The structure of the “pull type” is as follows.
As shown in FIG. 5, the case 16 of the check valve 14 is composed of an outer cylinder 16a and an inner cylinder 16b, a filter 17 is fixed to one end side of the inner cylinder 16b, and an opening on the other end side of the inner cylinder 16b. A valve seat 21 is formed, and the valve body 20 is seated on the valve seat 21. The spring 22 is attached in a tensioned state between the filter 17 and the valve body 20, and the valve body 20 is pulled in the direction in which the valve body 20 is seated on the valve seat 21. When liquefied water enters from the filter 17 side and a water pressure higher than a predetermined level is applied, the spring 22 is pulled and the check valve 14 is opened.

The structure of “compression format” is as follows.
As shown in FIG. 6, the case 16 of the check valve 14 is composed of an outer cylinder 16a and an inner cylinder 16b, the filter 17 is fixed to one end side of the inner cylinder 16b, and the inner cylinder 16b is closer to one end opening side. A tapered portion that is tapered is formed, a valve seat 21 is formed at the tip of the tapered portion, and the valve body 20 is configured to be seated on the valve seat 21. On the other end side of the inner cylinder 16b, a lid 28 is fixed to the outer cylinder 16a and the inner cylinder 16b. One end of a shaft 27 extending in the axial direction of the case 16 is fixed to the valve body 20, and the other end of the shaft 27 passes through an insertion hole 29 formed in the lid 28, and a stopper material is provided at the end of the shaft 27. The nut 30 is screwed. A spring 22 is attached in a compressed state between the valve body 20 and the lid 28, and the spring 22 biases the valve body 20 toward the valve seat 21. When a predetermined or higher water pressure is applied from the filter 17 side, the spring 22 is compressed and the check valve 14 is opened so that the shaft 27 penetrates the insertion hole 29 of the lid 28 to the left.

Next, the “gravity type” and the “friction type” of the check valve 14 that does not use a spring will be described.
The structure of “gravity type” is as follows.
The check valve 14 shown in FIG. 7 is used at the bottom of the manhole body 2 (the bottom plate 3 and the invert block 4). The case 16 of the check valve 14 includes an outer cylinder 16a and an inner cylinder 16b. The filter 17 is fixed to one end side of the inner cylinder 16b, and a valve body 20 (lid) is provided at the other end side opening of the inner cylinder 16b. Is disposed. The filter 17 is disposed on the lower side and the valve body 20 is disposed on the upper side. Although the valve body 20 is mounted on the step part formed in the inner cylinder 16b, a heavy thing is used. The adjustment of the weight is the same as that of the above-described spring, and the valve body 20 is not detached at the time of normal embedding, and is formed so that the valve body 20 is detached by the water pressure at the time of liquefaction. When liquefied water pressure exceeding a predetermined value is applied from the filter 17 side, the valve body 20 is lifted and the check valve 14 is opened. In this way, the heavy object that closes the vertical hole 13 becomes the valve body 20 to form the check valve 14.

The structure of the “friction type” is as follows.
The friction check valve 14 shown in FIG. 8 can be used for both the bottom and the side wall of the manhole body 2. The case 16 of the check valve 14 includes an outer cylinder 16a and an inner cylinder 16b. The filter 17 is fixed to one end side of the inner cylinder 16b, and a valve body (plug) 20 is provided at the other end side opening of the inner cylinder 16b. Is disposed. Friction is generated at the contact portion 21a between the periphery of the valve body 20 and the enlarged diameter portion of the inner cylinder 16b. The adjustment of the frictional force is the same as that of the spring 22 described above, and the valve body 20 is not detached at the time of normal embedding, and is formed so that the valve body 20 is detached by water pressure at the time of liquefaction. When a predetermined or higher water pressure is applied from the filter 17 side, the valve body 20 is pressed and the check valve 14 is opened. That is, the plug-like material becomes the valve body 20 that closes the horizontal hole 12 or the vertical hole 13 to form the check valve 14.

Since the manhole body 2 is used for a long period of time, the check valve 14 needs to be replaced after a certain period of time. Therefore, it is preferable that the check valve 14 be detachable from the manhole body 2 as follows. As for the attachment / detachment method, there are a “bolt connection type” and a “screw-in type”.
The structure of the “bolt connection type” is as follows.
As shown in FIG. 5, the case 16 of the check valve 14 is divided into an outer cylinder 16 a and an inner cylinder 16 b, and all functional parts as check valves such as the filter 17 and the valve body 20 are on the inner cylinder 16 b side. Install. The outer cylinder 16a and the inner cylinder 16b are formed so as to be closely attached and detached. Then, a screw hole (not shown) is formed in the end of the outer cylinder 16a and the inner cylinder 16b on the side where the valve body 20 is present, and the outer cylinder 16a and the inner cylinder 16b are connected by the fixing plate 33 and the bolt 34. . Only the outer cylinder 16a is fixed to the manhole body 2, and the inner cylinder 16b is removed from the manhole body 2 for replacement by removing the bolt 34 at the time of replacement. Note that the check valve 14 shown in FIGS. 2 to 4 and 6 to 8 can also be bolted to remove the inner cylinder 16b.

The “screw-in” structure is as follows.
As shown in FIG. 9, the case 16 of the check valve 14 is divided into an outer cylinder 16a and an inner cylinder 16b, an internal thread 31 is formed on the inner peripheral surface of the outer cylinder 16a, and the outer peripheral surface of the inner cylinder 16b is formed. Forms a male thread 32. Functional parts as check valves such as the filter 17 and the valve body 20 are attached to the inner cylinder 16b side. Only the outer cylinder 16a is fixed to the manhole body 2, and the inner cylinder 16b is removed by removing the inner cylinder 16b at the time of replacement. The check valve 14 shown in FIGS. 2 to 4 and FIGS. 5 to 8 can also be screwed to remove the inner cylinder 16b from the manhole body 2.

While the embodiments of the present invention have been described above, various modifications can be made to the present invention based on the technical idea of the present invention.
For example, in the first embodiment, the check valve 14 is used, and in the second embodiment, the piping 42 is used to prevent the manhole body from floating, but both may be used together.
Although the first embodiment has been described using the coil spring, other elastic members such as a leaf spring may be used instead of the coil spring.

It is sectional drawing of the manhole main body which employ | adopted the non-return valve system in the 1st Embodiment of this invention. It is a top view of the non-return valve integrated in the manhole main body of FIG. It is sectional drawing of the XX direction of FIG. It is a bottom view of the non-return valve integrated in the manhole main body of FIG. It is a modification (spring tension type and bolt connection type) of a check valve of Drawing 2-Drawing 4, A is a top view of a check valve, B is a sectional view, and C is a bottom view. It is a modification (spring compression type) of the check valve of FIG. 2, A is a top view of a check valve, B is sectional drawing, C is a bottom view. It is a modification (gravity type) of the check valve of FIG. 2, A is a top view of a check valve, B is sectional drawing, C is a bottom plan view. It is a modification (friction type) of the check valve of FIG. 2, A is a top view of a check valve, B is sectional drawing, C is a bottom plan view. It is a modification (screw-in type) of the check valve of FIG. 2, A is a top view of a check valve, B is sectional drawing, C is a bottom plan view.

Explanation of symbols

1 Manhole 2 Manhole body 3 Bottom plate 4 Invert block 6 Body block 7 Upper block 8 Opening block 11 Underground 12 Horizontal hole 13 Vertical hole 14 Check valve 16a Outer cylinder 16b Inner cylinder 17 Filter 21 Valve seat 26 Inner cylinder

Claims (5)

Manhole, allowing the flow of water into the buried object in the ground side wall portion of buried objects such as joint groove and in said buried object to form a through hole communicating from the ground side to the through hole and, in the buried object floating preventing structure of the check valve is disposed to block at all times the flow of water into the ground side from the buried object within
Wherein an elastic member provided in the valve body of the check valve, together with the elastic member is configured to open the check valve against the constant pressure greater than that occurring in the ground, the case of the check valve Is formed of an outer cylinder fixed to the through-hole, and an inner cylinder that is detachably mounted in the outer cylinder and in which the valve body is provided, and when the check valve is replaced, the inner cylinder A structure for preventing floating of an embedded object , wherein only the cylinder is configured to be removable from the embedded object. Manhole, the a ground side and in the buried object to form a through-hole communicating with the bottom wall portion of buried objects such as joint groove, the flow of water from the ground side to the through hole to the buried object in acceptable, in a buried object floating preventing structure which is disposed a check valve that shuts off at all times the flow of water into the ground side from the buried object within
The valve body of the check valve is a heavy object placed on the flow path and configured such that the valve body is opened the check valve against the constant pressure greater than that generated in the ground In addition, the check valve case includes an outer cylinder fixed to the through-hole, and an inner cylinder that is detachably attached to the outer cylinder and includes the valve body therein. An embedded object floating prevention structure , wherein only the inner cylinder can be removed from the embedded object when the stop valve is replaced . Manhole, allowing the flow of water into the buried object in the ground side wall portion of buried objects such as joint groove and in said buried object to form a through hole communicating from the ground side to the through hole and, in the buried object floating preventing structure of the check valve is disposed to block at all times the flow of water into the ground side from the buried object within
A plug-like product valve body of the check valve closes the flow passage, opening the check valve and the check valve and the valve body against a certain over pressure generated in the ground The check valve case includes an outer cylinder fixed to the through-hole, and an inner cylinder that is detachably attached to the outer cylinder and in which the valve body is provided. An embedded structure floating prevention structure characterized in that, when replacing the check valve, only the inner cylinder can be removed from the embedded object. The buried object floating prevention structure according to any one of claims 1 to 3, wherein a filter that blocks inflow of earth and sand is provided on the underground side of the check valve.   The embedded object floating prevention structure according to any one of claims 1 to 4, wherein a holding member that allows the check valve to be attached and detached is provided on the wall portion.

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