JP4730622B2 - Levitation restraint manhole. - Google Patents

Description

  The present invention relates to a levitation suppression 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 base, and 8 is an invert. They are generally joined and integrated by an adhesive or the like.

  As is well known, in the Hanshin-Awaji and Chuetsu earthquake areas, the liquefaction (fluidization) of the ground raises many of the assembly manholes, resulting in obstacles to road traffic and greatly affecting recovery and support assistance. It is a new memory to stop the function of, and to have hindered residents' lives.

  According to the January 2005 issue of the Sewerage Society Vol. 42 No. 507, page 68, Table-2, it was reported that there were 1,365 manhole lifts and sinkings in the Niigata Chuetsu Earthquake. Currently, various solutions are being studied in the technical field of sewerage, including the Ministry of Land, Infrastructure, Transport and Tourism's sewerage department.

  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 dense body changes its shape due to the shearing force, but does not change its volume. 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. As a result, the assembly manhole rises due to the mud of the ground due to the earthquake, and the sand particles floating below sink into it. As a result, the assembly manhole will remain floating when returning to normal.

  As a method of preventing the assembly manhole from rising due to fluidization of the ground, there were technologies such as selecting a backfill material proposed by the Ministry of Land, Infrastructure, Transport and Tourism to increase the pressure density, and performing backfilling with solidified improved soil.

  However, these methods have problems such as being impractical because they are difficult to apply to existing assembly manholes, increase the cost of backfill materials, and it is difficult to manage variations in construction. .

Today, it is screamed that a major earthquake is imminent. In addition to the newly installed ones, especially the prevention of the rise of existing manholes is a realistic and useful method, that is, construction is easy, efficient and continuous. The emergence of an ascent prevention method that can be performed and that can provide an effective effect is desired.
Utility Model Registration No. 3120761 January 2005 Sewage Society Vol.42 No.507

  Accordingly, the present invention is intended to provide a levitating suppression manhole that is easy to apply to existing manholes as well as newly installed manholes and that is excellent in workability.

  The present invention has been made in order to solve the above-mentioned problems, and is provided with an overhang receiving portion formed in a ring shape or intermittently in the circumferential direction at an arbitrary position on the outer surface of the manhole housing, and a through hole is formed on the upper portion thereof. Attach the provided enclosure frame to form a cage-like part, and store the weighted padding material such as gravel material, metal lump, metal ball, and metal plate with through holes in it or in a bag. It is a maneuvering manhole characterized by

  When applied to an assembly manhole, the overhang receiving part is formed in a ring shape, temporarily fixed with a set screw at an arbitrary place on the manhole housing, and then lifted with a synthetic resin adhesive such as an epoxy adhesive. By adopting a strong fixing method that can be withstood, it is possible to easily form an overhang receiving portion on an existing manhole as well as on a new manhole.

  It is preferable to use a net-like material for the bag for storing the weighted filling material. By selecting a mesh of a net-like material, it is possible to use even a small weighted filling material that passes through a through hole provided in the enclosure frame. The weighted filling material may be put in a sachet, but for construction, an appropriate mesh sheet-like material is laid on the inner surface of the surrounding frame, and the weighted filling material is put into it. A construction method in which the inner and outer edges of the sheet are tied to the manhole housing with a tightening band has good workability and is practical.

  The levitation suppression manhole according to the present invention considers the weight balance between the manhole and soil during soil liquefaction and adds a weighted block body having an excessive pore water pressure increase suppression function (floating suppression function) to the manhole housing. Therefore, it is necessary to have a gap between the filling materials to absorb the water flow and suppress the absorption of the pore pressure, and the apparent specific gravity of the manhole. It is necessary to add a weighted filling material that is at least 1.0 to 2.0 or more, and a weighted filling material that is easy to manage is required.

  As the weighted filling material that meets this requirement, a metal ball having a substantially constant shape for weight calculation, a filling material made of a cast hole with through holes or irregularities, or a metal plate with through holes, etc. are useful. Compared to gravel materials, these filling materials can be expected to have a floating suppression effect without variation, and construction management becomes easy.

  According to the present invention, the apparent specific gravity of the manhole at the time of soil liquefaction is 1.0 to 2.0 or more, and the construction of adding a weighted block body having a function of suppressing excessive increase in pore water pressure is performed in a procedure. Can be provided.

  FIG. 2 is a perspective view of an embodiment of the present invention, FIG. 3 is a longitudinal sectional view, FIG. 4 is a plan view of the overhang receiving portion attached to the manhole housing, and a plan view before attaching the enclosure frame, 10 is the manhole housing, and 11 is cement concrete. A ring-shaped overhang receiving portion 12 made of a casting, a frame frame made of a casting provided with a through hole, a sheet 13 of a mesh smaller than the filling material, and a filling material 14. The overhang receiving portion 11 is not limited to cement concrete, but may be made of metal or the outside as a metal frame, and concrete may be put therein.

  The overhang receiving portion 11 is provided with an appropriate number of anchor bolts 15 for fixing an enclosure frame plate 12 provided with a casting through-hole on the upper surface, and a set screw for temporary fixing is screwed to the lower portion. Anchor female screws 16, 16 are provided, and the manhole housing 10 is attached to the anchor bolts 15, 15 by screwing hanging eyenuts 17, 17 as shown in FIG. The hooks attached to the crane wires 18, 18 are hooked on the hanging eye nuts 17, 17, are suspended to a predetermined position, and the overhang receiving portions are set by set screws 19, 19 screwed to the anchor female screws 16, 16. 11 is temporarily fixed to the manhole housing 10, and an epoxy adhesive 20 is injected between the manhole housing 10 and the overhang receiving portion 11 is fixed to the manhole housing 10.

  Next, after removing the hanging eye nuts 17 and 17 from the anchor bolts 15 and 15, the enclosure frame plate 12 (eight in the embodiment) is used as shown in FIGS. 3, 4, and 5 (b). The anchor bolts 15, 15 are fastened with nuts, and the adjacent surrounding frame plate 12 is connected with bolts 22 and nuts 23 via a hem-like connecting plate 21.

  Next, as shown in FIG. 3 and FIG. 5 (b), a mesh sheet having a size that prevents the small filling material 14 from spilling out from the through holes of the enclosure frame plate 12 in the enclosure frame plate 12 in the shape of a cage. 13, insert the filling material 14 as shown in FIG. 3, FIG. 4 and FIG. 5C, close the sheet 13 so as to wrap the filling material 14, and tighten the inner and outer edges. The band 24 is fixed to the manhole housing 10.

  As described above, mounting of the overhang receiving portion 11 → mounting of the surrounding frame plate 12 → laying of the sheet 13 → inserting of the filling material 14 → fixing of the sheet 13 with the tightening band 23 is carried out in order, and it has a function to suppress the rise. A manhole having a weighted block body can be quickly assembled and constructed, and is excellent in workability.

  In the case of a newly installed manhole, the manhole housing can be integrally provided with an overhang receiving portion provided intermittently in the ring shape or in the circumferential direction. However, as shown in the embodiment, the ring-shaped overhang receiving portion 11 is externally attached. Is more practical and better.

  The floating suppression manhole according to the present invention configured as described above and having an apparent specific gravity of 1.0 to 2.0 or more is a weighted block body including an overhang receiving portion, a surrounding frame provided on the overhang receiving portion, and a filling medium. However, when the soil is liquefied, the water flow is diverted to suppress an excessive increase in pore water pressure and prevent the manhole from rising, and good experimental results have been obtained.

The longitudinal cross-sectional view of a standard assembly manhole. The perspective view of the Example of this invention. The longitudinal cross-sectional view of the Example of this invention. The top view before attaching an overhang | projection receiving part in the Example of this invention to a manhole housing, and attaching an enclosure frame. Explanatory drawing which shows the assembly procedure of this invention.

Explanation of symbols

10 Manhole housing 11 Overhang receiving portion 12 Enclosure frame plate 13 Sheet 14 Filling material

Claims (4)

At the arbitrary position on the outer surface of the manhole's housing, a ring-shaped or intermittently formed projecting receiving portion is formed in the circumferential direction, and a cage frame with a through hole is attached to the upper portion to form a cage-shaped portion, A levitation suppression manhole characterized in that a gravel material, a metal lump, a metal sphere, a weighted filling material such as a metal plate having a through hole is stored as it is or in a bag. The levitation suppression manhole according to claim 1, wherein the ring-shaped overhang receiving portion is externally attached. The levitation suppression manhole according to claim 1 or 2, wherein a net-like material is used for the bag for storing the weighted filling material. An overhang receiving portion for a levitation suppression manhole, which is formed in a ring shape and has an appropriate number of surrounding frame mounting anchor bolts planted on the upper surface, and a temporary set screw provided on the side.

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