JP5064351B2 - Manhole rise prevention method and its manhole - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for preventing the floatation of a built-up manhole, which is effective for preventing the floatation of an existing manhole and damage to a bottom slab without excavating the circumference and which is easy to be constructed, and to provide a manhole to which the method is applied. <P>SOLUTION: In accordance with the shape of segment-like weight bodies 15a-15f, an invert 12 provided at the bottom of the skeleton 9 of a built-up manhole and an outflow pipe 13 provided on a vertical wall 10 of the skeleton 9, damage preventing bodies 17a-17f of the bottom slabs, having weight bodies which bottoms are segment-like molded and having vertical sections which are L-shaped, are disposed annularly along the shape of the inner wall surface of the vertical wall 10. The weight bodies 15a-15f and the damage preventing bodies of the bottom slabs 17a-17f are respectively connected with connecting parts 16, 16, 16, 16, the weight bodies 15a-15f and the damage preventing bodies 17a-17f of the bottom slabs are connected with a mortar 18 on the top face of the inner wall surface of the vertical wall 10 and on the top face of the invert 12, the apparent specific gravity of the built-up manhole as a whole is set to 1.0 or larger. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to a method for preventing a manhole from rising and its manhole.

  FIG. 1 shows a standard configuration of an assembly manhole approved by the Japan Sewerage Association, which is generally used at present. 1 is a manhole cover, 2 is a manhole cover receiving frame, 3 is a height adjustment ring, and 4 is a slanted wall. , 5 and 6 are straight walls, 7 is a bottom plate, and 8 is an invert, which are generally joined and integrated by an adhesive or the like.

  As is well known, in the Hanshin-Awaji and Chuetsu earthquake areas, liquefaction (fluidization) of the ground has lifted many of the assembly manholes, creating obstacles to relief.

  According to the January 2005 issue of Sewerage Association Vol. 42 No. 507, page 68, Table-2, it was reported that 1,365 assembly manholes were lifted and subsided in the Niigata Chuetsu Earthquake. Currently, various studies have been made on solutions in the technical field of sewerage, including the Ministry of Land, Infrastructure, Transport and Tourism's sewerage department, and various anti-floating measures have been proposed.

  A material that is an aggregate of particles such as sand is called a granular body, and this granular body has a characteristic called dilatancy as a unique property, that is, a phenomenon in which the volume changes due to shearing. For example, the shape of the granular material changes due to the shearing force, but the volume does not change. However, when a shearing force is applied to a granular material in a loosely packed state, it changes into a honey-packed state and the volume shrinks.

  In dry sand, such a volume change occurs instantaneously, but in sand saturated with water, it takes time for the pore water to be discharged to the outside. When sudden shear deformation occurs, the drainage is not in time and volume shrinkage will occur, and the effective stress decreases accordingly, so the sand loses its strength and eventually becomes like a liquid It will take on an aspect. This is the liquefaction mechanism.

  And when soil liquefies in this way, the specific gravity of the earth and sand containing a lot of moisture will be 1.0 or more and 2.0.

  On the other hand, the assembly manhole (underground structure) is hollow and has a cup shape, so the apparent specific gravity is smaller than the liquefied ground, so when the ground in the event of an earthquake becomes muddy, it begins to surface, Sand particles floating under the assembly manhole will sink, and with the end of the earthquake, the sand particles will recombine as they are and the assembly manhole will remain floating.

  As a method of preventing the assembly manhole from rising due to fluidization of the ground, conventionally, the mass of the assembly manhole in which the bottom plate, the straight wall and the inclined wall are integrated is increased, and a backfill material is selected to increase the pressure density. There was technology such as backfilling with solidified improved soil.

  However, these methods must change the design of the assembly manhole approved by the Japan Sewerage Association, and cannot be applied to existing assembly manholes, increase the cost of backfill materials, and are not practical. There was a problem that it was difficult to recover the original same day.

  Today, it is screamed that a major earthquake is imminent. In addition to the new ones, it is a practical and useful method to prevent the assembling of manholes from rising, especially for easy and efficient construction. Therefore, the emergence of a levitating prevention method that can be performed at the same time and that can provide an effective effect is desired.

  Therefore, the inventor of the present application previously proposed a method of preventing the assembling and the assembling manhole by attaching a flange-like weight body to the straight wall of the assembling manhole and increasing the apparent specific gravity of the assembling manhole as shown in Patent Document 2. Although the method can be applied to existing assembly manholes, when assembling a flange that is a heavy body to increase the apparent specific gravity on existing assembly manholes, it is necessary to excavate the asphalt and the stratum around the assembly manhole. There was a problem that construction cost and construction period were required.

In general, the bottom plate 7 of the assembly manhole is subjected to the weight of the assembly manhole and the repeated load of an automobile or the like passing over it. In this case, since the straight wall 6 in contact with the bottom plate is cylindrical, a pressing force acts downward on the periphery of the bottom plate 7, and an upward repulsive force acts on the center portion of the bottom plate 7. When it was insufficient, the bottom plate 7 might be damaged by those repeated stresses.
Utility Model Registration No. 3120761 JP 2007-262747 A January 2005 Sewage Society Vol.42 No.507

  Therefore, the present invention is intended to provide an assembling manhole floating prevention method and its manhole that are effective in preventing floating and bottom plate damage without cutting the surroundings of existing manholes and are easy to construct.

  SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems. The invention according to claim 1 is characterized in that a floating weight preventing body and a bottom plate damage preventing body are provided inside the assembly manhole, and the overall apparent specific gravity is 1.0. This is a method for preventing the manhole from rising above.

  According to a second aspect of the present invention, in the first aspect, the weight body is provided along the inner wall surface of the assembly manhole.

  A third aspect of the present invention is the manhole floating prevention method according to the second aspect of the present invention, wherein the weight body and the bottom plate damage prevention body are coupled to the inner wall surface and invert of the assembly manhole with a binder. .

  According to a fourth aspect of the invention, there is provided the manhole floating prevention method according to the second or third aspect, wherein the weight body is provided in an annular shape along the inner wall surface of the assembly manhole.

  According to a fifth aspect of the present invention, in the invention according to any one of the second to fourth aspects, the weight body and the bottom plate damage prevention body are configured in a plurality of segments. It is a prevention method.

  The invention according to claim 6 is the invention according to any one of claims 1 to 5, wherein the weight body and the bottom plate damage prevention body are made of metal, concrete, synthetic resin alone or a combination thereof. This is a method for preventing the manhole from rising.

  According to a seventh aspect of the present invention, in the method according to any one of the first to sixth aspects, the vertical cross section of the bottom plate breakage prevention band is formed in an L shape. It is.

  The shape, size, thickness, and the like of the weight body provided on the inner wall surface of the assembly manhole are selected and determined by design, and the arrangement thereof is arranged in a balanced manner according to the structure of the assembly manhole.

  The invention according to claim 8 is a manhole characterized in that a weight body for preventing levitating and a bottom plate damage preventing body are provided inside the assembly manhole so that the apparent specific gravity is 1.0 or more.

  According to the ninth aspect of the present invention, a plurality of segment-like lifting prevention weight bodies are annularly arranged along the shape on the inner wall surface of the assembly manhole, and a bottom plate damage prevention body is provided. It is a manhole characterized by being 0 or more.

  A tenth aspect of the invention is the manhole according to the ninth aspect of the invention, wherein the weight body for preventing levitation, the bottom plate damage prevention body, and an inner wall surface of the assembly manhole are coupled with a bonding material.

  According to an eleventh aspect of the present invention, in the invention according to the ninth or tenth aspect, the segment-like weight for preventing levitation is provided with a through-hole through which a footrest provided inside the manhole is inserted. It is a manhole.

  A twelfth aspect of the present invention is the manhole according to the ninth aspect or the tenth aspect of the present invention, wherein a footrest is provided on the segmented anti-lifting weight body.

  The invention according to claim 13 is the invention according to any one of claims 8 to 12, wherein the weight body and the bottom plate damage prevention body are made of metal, concrete, synthetic resin alone or a combination thereof. It is a manhole characterized by that.

  A fourteenth aspect of the present invention is the manhole according to any one of the eighth to thirteenth aspects, wherein a longitudinal section of the bottom plate damage prevention band is formed in an L shape.

  As described above, the manhole floating prevention method according to the present invention is a conventionally known method in which the apparent specific gravity of the entire assembly manhole is set to be higher than the specific gravity of the liquefied soil by providing a weight body inside the assembly manhole. This is a new construction method that is different from the weighting method. According to this construction method, it is not necessary to perform the excavation work around the existing assembly manhole as in the conventional construction method. It is possible to take measures to prevent the rise of the existing manhole in And this floating prevention method has a manhole floating prevention effect without obstructing the function of the manhole, although the inner diameter of the assembly manhole is reduced to some extent by arranging the weight body along the inner wall surface of the manhole housing. be able to.

  In addition, when a segment-shaped anti-lifting weight body is provided inside an asymmetrical assembly manhole, a combination of segment-shaped weight bodies with different lengths is used to balance the weight, so that Assembling manhole runout can be reduced.

  On the other hand, concrete manholes have a service life of about 50 years, but existing manholes that have been in use for more than 20 years will deteriorate sooner than their actual service life due to corrosion caused by hydrogen sulfide gas generated from sewage. However, there are many manholes that need to be reinforced or replaced.

  However, in the present invention, the weight body is made of metal, concrete, synthetic resin alone or a combination thereof, and is assembled by bonding to the inner wall surface of a deteriorated assembly manhole with a binder such as mortar. Since the manhole can be reinforced and rehabilitated, and replacement work for a deteriorated manhole is not necessary in addition to the anti-lifting effect, the economic effect is great.

  When the weight body is provided on the inner wall surface of the existing assembly manhole, the load applied to the bottom plate increases, so that the bottom plate may be damaged beyond the strength of the bottom plate. By providing the body, it is possible to prevent the bottom plate from being damaged.

  2 and 3 are a plan view and a cross-sectional view taken along the line AA of the first embodiment of the present invention. Reference numeral 9 is a bottom frame of an assembly manhole, 10 is a straight wall, 11 is a bottom plate, and 12 is a bottom plate. Inverters 13 are outflow pipes connected to the straight wall 10, 14 are foot brackets provided on the inner wall surface of the straight wall 10, and 15 a, 15 b, 15 c, 15 d, 15 e, 15 f are connection parts 16, 16, 16, 16. 18a, 17b, 17c, 17d, 17e, and 17f are bottom plate damage prevention bodies having a L-shaped longitudinal cross section that also serves as a weight body, and 18 is weight bodies 15a and 15b. , 15 c, 15 d, 15 e, 15 f and bottom plate damage prevention bodies 17 a, 17 b, 17 c, 17 d, 17 e, 17 f and the straight wall 10 are joined together.

  As shown in FIG. 4, the weight bodies 15a, 15b, 15c, 15d, 15e, 15f and the bottom plate damage prevention bodies 17a, 17b, 17c, 17d are connected to the connection portions 16 and screw holes provided on the side surfaces of the weight body and the bottom plate damage prevention body. 19 are overlapped with a sealing material 20 made of butyl rubber and connected by a bolt 21 provided with a bolt head having a hexagonal hole.

  In the present embodiment, a horizontally long insertion hole 22 is provided in the weight body 15c, and the footrest fitting 14 can be inserted into the insertion hole so that it can be easily installed in an existing assembly manhole. In addition, when there is no existing footrest metal fitting, it can also be provided in the weight body 15c.

  The bottom plate damage prevention bodies 17a, 17b, 17c, 17d, 17e, and 17f are joined to the straight wall 10 and the weight bodies 15a, 15b, 15c, 15d, 15e, and 15f, and the straight wall 10 and the invert 12 by the mortar 18, and the weight body 15a. , 15b, 15c, 15d, 15e, 15f and bottom plate damage prevention bodies 17a, 17b, 17c, 17d, 17e, 17f are overlapped with a sealing material made of butyl rubber.

  In this embodiment, the straight wall 10 has an inner diameter of 1.5 m, the weight bodies 17a, 17b, 17c, 17d, 17e, and 17f have a thickness of 5 cm and a height of about 2 m. The inner diameter of the housing 9 including the weight bodies 15a, 15b, 15c, 15d, 15e, and 15f is 1.4 m, but there is no hindrance to the function of the manhole itself, and the weight bodies 15a, 15b, 15c, 15d, 15e, It becomes 1t or more with 6 pieces of 15f. Although the apparent specific gravity of the entire assembly manhole necessary for preventing the ascent is changed depending on the depth of the assembly manhole and the surrounding soil properties, the weight bodies 15a, 15b, 15c, 15d, 15e, and 15f should be installed inside the assembly manhole. As a result, the apparent specific gravity of the assembly manhole where the assembly manhole does not rise even if the soil liquefies can be easily increased to 1.0 or more without cutting the periphery of the assembly manhole, and the weight bodies 15a, 15b, 15c, 15d. , 15e, 15f cover the inner wall surface of the assembly manhole, so that the deteriorated assembly manhole can be reinforced and rehabilitated.

  Further, since the bottom plate damage prevention bodies 17a, 17b, 17c, 17d, 17e, and 17f are formed so that the lower part thereof is matched to the surface shape of the invert 12 or the outflow pipe 13, the bottom plate damage prevention bodies 17a, 17b, 17c, 17d, 17e, 17f Does not interfere with function. The bottom plate damage prevention bodies 17a, 17b, 17c, 17d, 17e, and 17f serve as weight bodies and cover the top surface of the bottom plate, thereby preventing the bottom plate 11 from being damaged against the repulsive force upward of the bottom plate. be able to.

  In this embodiment, the weight body and the bottom plate damage prevention body may be all made of metal (in the embodiment, made of tag tile cast iron), but the apparent specific gravity may be 1.0 or more with a metal weight body provided in the lower part. If possible, the upper part may be a thin concrete or synthetic resin weight body. In this embodiment, the weight body and the bottom plate damage prevention body are coupled to the straight wall using the mortar 18, but it is needless to say that they may be coupled using an anchor bolt or the like.

The longitudinal cross-sectional view of a standard assembly manhole. The top view which shows the 1st Example of this invention. AA line sectional view shown in FIG. FIG. 4 is an enlarged partial cross-sectional view shown in B of FIG. 3.

Explanation of symbols

9 Housing 10 Straight wall 11 Bottom plate 12 Invert 13 Outflow pipe 14 Foot brackets 15a to 15f Weight body 16 Connection portions 17a to 17f Bottom plate damage prevention body 18 Mortar

Claims (14)

A manhole rising prevention method characterized in that a floating weight preventing body and a bottom plate breakage preventing body are provided inside an assembly manhole, and the overall apparent specific gravity is 1.0 or more. 2. The method according to claim 1, wherein the weight body is provided along an inner wall surface of the assembly manhole. 3. The method for preventing a manhole from rising according to claim 2, wherein the weight body and the bottom plate damage prevention body are joined to the inner wall surface and invert of the assembly manhole by a binder. 4. The method according to claim 2, wherein the weight body is provided in an annular shape along an inner wall surface of the assembly manhole. 5. The manhole floating prevention method according to any one of claims 2 to 4, wherein the weight body and the bottom plate damage prevention body are configured in a plurality of segments. 6. The method for preventing a manhole from rising according to any one of claims 1 to 5, wherein the weight body and the bottom plate damage prevention body are made of metal, concrete, synthetic resin, or a combination thereof. . The method for preventing manholes according to any one of claims 1 to 6, wherein a longitudinal section of the bottom plate damage prevention band is formed in an L shape. A manhole characterized in that an assembling manhole is provided with an anti-lifting weight body and a bottom plate damage prevention body so that the apparent specific gravity is 1.0 or more. A plurality of segmented anti-lifting weight bodies are annularly arranged along the shape on the inner wall surface of the assembly manhole, and a bottom plate breakage prevention body is provided to make the overall apparent specific gravity 1.0 or more. Manhole to do. The manhole according to claim 9, wherein the floating weight preventing body, the bottom plate breakage preventing body, and an inner wall surface of the assembly manhole are coupled by a bonding material. 10. The manhole according to claim 8, wherein a through hole through which a footrest provided inside the manhole is inserted is provided in the segment-like weight for preventing levitation. 11. The manhole according to claim 8 or 9, wherein a footrest is provided on the segment-like weight for preventing levitation. The manhole according to any one of claims 8 to 12, wherein the weight body and the bottom plate damage prevention body are made of metal, concrete, synthetic resin, or a combination thereof. The manhole according to any one of claims 8 to 13, wherein a longitudinal section of the bottom plate damage prevention band is formed in an L shape.

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