JP5064347B2 - Manhole rise prevention method and its manhole - Google Patents

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 an ascent 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 has proposed a method for preventing the ascent and increasing the apparent specific gravity of the assembly manhole by attaching a flange-like weight body to the straight wall of the assembly manhole as shown in Patent Document 2, and this assembling manhole has been devised. Although it can be applied to existing assembly manholes, when constructing flanges that are heavy bodies to increase the apparent specific gravity, it is necessary to excavate the asphalt and the stratum around the assembly manholes. There was a problem that it took cost and construction period.
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 assembling prevention method that is realistic, useful, and easy to implement without preventing the surrounding manholes from being cut off, and the manhole.

  The present invention has been made to solve the above-mentioned problems, and the invention according to claim 1 is characterized in that a weight body for preventing levitating is provided inside the assembly manhole so that the overall apparent specific gravity is 1.0 or more. This is a method for preventing the manhole from rising.

  The invention according to claim 2 is the manhole floating prevention method according to claim 1, wherein the weight body is provided along an 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 inner wall surface of the assembly manhole are coupled by a coupling material.

  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 method according to any one of the second to fourth aspects, the weight body includes a plurality of segment-shaped weight bodies. is there.

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

  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 7 is a manhole characterized in that a weight body for preventing floating is provided inside the assembly manhole, and the apparent specific gravity is 1.0 or more.

  According to an eighth aspect of the present invention, a plurality of segmented weight-preventing weight bodies are annularly arranged along the shape on the inner wall surface of the assembly manhole, and a support body having a height adjusting means is provided below the weight body. In addition, the manhole is characterized by an overall apparent specific gravity of 1.0 or more.

  A ninth aspect of the present invention is the manhole according to the eighth aspect of the present invention, wherein the levitation-preventing weight body and the inner wall surface of the assembly manhole are coupled with a binder.

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

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

  The invention according to claim 12 is the invention according to any one of claims 7 to 11, wherein the weight body is made of metal, concrete, synthetic resin alone or a combination thereof. It is a manhole.

  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.

  It is desirable to install the weight body at the bottom of the assembly manhole due to the problem of the center of gravity, but in general, the invert at the bottom of the assembly manhole varies in shape depending on the use of the manhole, etc. Is difficult. However, the weight body can be installed horizontally at the bottom of the assembly manhole even if the shape of the invert is not horizontal by providing the support body provided with the height adjusting means at the lower part of the weight body as in the invention of claim 7. it can.

  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.

  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, wherein 9 is a housing at the bottom of the assembly manhole, 10 is a straight wall, 11 is an invert, and 12 is an invert. The outflow pipes 13a, 13b, 13c and 13d connected to the straight wall 10 are provided with segmented casting weight bodies which are provided with a slope 14 at the upper part and are connected in an annular shape with connecting fittings 15, 15, 15 and 15. is there.

  In this embodiment, the straight wall 10 has an inner diameter of 90 cm, the weight bodies 13a, 13b, 13c, and 13d have a thickness of 5 cm and a height of about 1 m. The inner diameter of the housing 9 including the weight bodies 13a, 13b, 13c, and 13d is 80 cm. However, the function of the manhole itself is not hindered, and the weight bodies 13a, 13b, 13c, and 13d are 1 t or more. Although the apparent specific gravity of the entire assembly manhole necessary for preventing ascent depends on the depth of the assembly manhole and the nature of the surrounding soil, the soil is made liquid by installing the weight bodies 13a, 13b, 13c, and 13d inside the assembly manhole. The apparent specific gravity of the entire assembly manhole in which the assembly manhole does not rise even if it is made can be easily increased to 1.0 or more without cutting the periphery of the assembly manhole.

  Further, since the weight bodies 13a, 13b, 13c, and 13d are formed so that the lower portions thereof are matched with the surface shape of the invert 11 or the outflow pipe 12, even if an earthquake occurs, the weight bodies 13a, 13b, 13c, and 13d are stable. And even if the inflow from the assembly manhole falls due to the inclined surface 14 at the top of the weight bodies 13a, 13b, 13c, 13d, it is difficult to adhere to the top of the weight bodies 13a, 13b, 13c, 13d, thus preventing corrosion and odor. I can do it.

  FIG. 4 is a cross-sectional view showing a second embodiment of the present invention. Weight bodies 16a, 16b, 17a, and 17b are made of segmented castings that are connected in a ring shape with a connection fitting 15 in the same manner as in the first embodiment. , 18 is a support body for supporting the weight bodies 17a and 17b.

  The weight bodies 16a and 16b are configured to be fitted vertically by a connection hole 19 provided in the lower portion and a connection fitting 20 provided in the upper portion of the weight bodies 17a and 17b. The support 18 is provided with a screw portion 21 at the top, and the screw portion 21 is inserted into a hole 22 provided in the bottom surface of the weight bodies 17a and 17b, and the weight bodies 17a and 17b are screwed into the nut 23 screwed into the screw portion 21. The height is adjusted. The substrate 24 of the support 18 is pivotally attached to the support body so as to be grounded along the surface shape of the invert 11.

  According to this embodiment, the weight body can be stably placed horizontally on the bottom of the assembly manhole without forming the shape of the bottom of the weight body in accordance with the shape of the upper surface of the invert. Further, when the weight body is installed, first, the base of the heavy weight bodies 16a and 16b is formed by the light weight bodies 17a and 17b and the support body 18, thereby reducing the work burden when installing the weight body inside the assembly manhole. be able to.

    FIG. 5 is a cross-sectional view showing a third embodiment of the present invention, which corresponds to a case where an inflow pipe 12 ′ is provided on the upper part of the straight wall 10.

In the first and second embodiments, four segmented weight bodies are annularly provided on the inner wall of the straight wall 10 of the assembly manhole. In this embodiment, the weight bodies 25a to 25d are adapted to the conditions of the assembly manhole. This is achieved by changing the configuration of the width and height.

  6 and 7 are a plan view and a cross-sectional view taken along the line BB of the fourth embodiment, 26 is a casing at the bottom of the assembly manhole, 27 is a straight wall, 28 is an outflow pipe provided on the straight wall 27, 29 is an invert provided on the bottom of the straight wall 27, 30 is a lifting footrest provided on the inner wall of the straight wall 27, 31 a to 31 f are annularly connected circular casting weight bodies, and 32 a to 32 f are It is composed of a support body of weight bodies 31a to 31f in which a plurality of arc-shaped metal flat plates are connected in an annular shape.

  In the present embodiment, the weight body 31 a is provided with an insertion hole 33 through which the footrest 30 is inserted. Even if the footrest 30 is present, the weight body 31 a can be installed, and the function of the footrest 30 is inhibited. There is nothing to do. In order to install the weight bodies 31a to 31f, first, the footrest 30 is passed through the insertion hole 33 of the weight body 31a and is brought into close contact with the inner wall of the straight wall 27 and positioned. Then, as shown in FIG. 8, the support bolts 34 provided at one end of each support are passed through a connection hole 35 provided at the other end of the other support so that the support 32 a to 32 f are annular and have a height adjusting function. The support leg main body 36 provided with is attached with a nut 37 and installed so that the support bodies 32a to 32f are horizontal with reference to the position of the bottom surface of the weight body 31a.

  Here, as shown in FIG. 8, the support leg main body 36 is provided with a base plate 39 rotatably by a ball joint constituted by a ball 38 provided at the lower end and a ball joint bearing portion 40 provided on the base plate 39, and a grounding surface. A height adjusting bolt 43 is inserted into the height adjusting hole 42 of the height adjusting plate 41 which can always be kept vertical regardless of the inclination angle, and is fixed by the nut 44 to fix the supports 32a to 32f. The height can be adjusted freely and the level can be maintained.

  Next, after the support bodies 32a to 32f are installed, the weight bodies 31b to 31f are sequentially installed in an annular shape on the support bodies 32b to 32f, and bolts provided on one side surface of the weight bodies 31a to 31f as shown in FIG. The tightening bolt 46 is screwed into the mounting portion 45, the tightening bolt 46 is rotated, the adjacent weight body 31c is pressed, and the weight bodies 31a to 31f are fixed to each of the weight bodies 31a to 31f by tension. And close contact with the inner wall surface of the straight wall 27.

  Therefore, according to the present embodiment, the weight body can be installed even if there is a footrest on the inner wall of the straight wall, and the function of the footrest is not hindered. It does not interfere with the lifting or lowering of people during work. In addition, since a light arc-shaped metal plate is used as the support, the support can be easily and quickly installed. In addition, the apparent specific gravity of the assembly manhole by the weight body can be increased without cutting the periphery of the assembly manhole, and the manhole of the manhole against the earthquake can be increased by bringing the weight body into close contact with the inner wall of the straight wall by the tension generated by the tightening bolt. Stiffness can be reinforced.

  FIG. 10 shows a cross-sectional view of the fifth embodiment. The fourth embodiment is equipped with a weight body of an assembly manhole, whereas the fourth embodiment is equipped with a weight body while leaving the footrest of the existing assembly manhole as it is. The footrest of the part is cut off and a weight body with a footrest is equipped.

  That is, the footrest 30 provided on the straight wall 47 in the place where the weight body is equipped is cut off, and the weight body 48 provided with the footrest 30 'as shown in FIG. It is intended to be equipped with.

  In the structure of the fourth embodiment, since the protruding length of the footrest is reduced only in the thickness portion of the weight body 31a, it is difficult to get on and slippery when ascending / descending, but the structure of the fifth embodiment is In addition to solving the problem and improving the workability of attaching the weight body as compared with the fourth embodiment, various weight bodies with different sizes of the leg through holes as in the fourth embodiment are prepared. There is an advantage that there is no hassle of having to.

  FIG. 12 is a cross-sectional view of a sixth embodiment of the present invention considering rehabilitation of a deteriorated manhole. 50 is a manhole cover receiving frame of an assembly manhole, 51 is a height adjusting ring, 52 is a slanted wall, 53 and 54 are straight. Walls, 55 are inverts, 56 are bottom plates, 60a to c, 61a to c, and 62a to c are stacked on a support 63, and mortar 64 is used as a binder on the inner wall surfaces of the slant wall 52 and the straight walls 53 and 54, respectively. The combined weight body, 65 is a sealing material made of butyl rubber, and 66 is a connection portion of the weight bodies 60a to 60c, 61a to 60c, and 62a to 62c.

  In this embodiment, the support 63 has the same structure as that of the fourth embodiment, and the straight wall 54 is sealed with a sealing material 65, and the weight bodies 60a to 60c, 61a to 62c, and 62a to 62c are formed on the support 63. As shown in FIG. 13, the connecting portion 66 provided on the side surface of the weight body and the screw hole 67 are overlapped with the sealing material 65 interposed therebetween, and connected by a bolt 68 provided with a bolt head having a hexagonal hole. After sandwiching and placing, the mortar 64 is poured between the straight wall 54 and the weight bodies 62 a to 62 c to join the weight bodies 62 a to 62 c to the inner wall surface of the straight wall 54.

  Next, the weight bodies 61a to 61c are stacked on the weight bodies 62a to 62c with the sealing material 65 sandwiched therebetween, and the mortar 64 is poured between the straight wall 53 and the weight bodies 61a to 61c in the same manner as described above to place the weight bodies 61a to 61c on the straight wall. It is combined with the inner wall surface of 53.

  The weight bodies 60a to 60c are similarly placed on the weight bodies 61a to 61c, and are joined to the inner wall surface of the inclined wall 52 by the mortar 64.

  Since the present embodiment is configured to cover the inner wall surface of the assembly manhole with the weight bodies 60a-c, 61a-c, 62a-c, the deteriorated assembly manhole can be reinforced and rehabilitated, and the soil can be liquefied. In addition, the apparent specific gravity of the entire assembly manhole where the assembly manhole does not rise can be easily increased to 1.0 or more without cutting the periphery of the assembly manhole, and the assembly manhole can be rehabilitated and an ascent prevention effect can be imparted. .

  In this example, the weight body may be all made of metal (in the example, made of tag tile cast iron), but when the apparent specific gravity can be 1.0 or more with the metal weight body provided in the lower part, The upper part may be a thin concrete or synthetic resin weight body.

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. Sectional drawing of the 2nd Example of this invention. Sectional drawing of the 3rd Example of this invention. The top view of the 4th Example of this invention. BB sectional drawing shown in FIG. The assembly schematic explanatory drawing of a support body. FIG. 7 is an enlarged partial cross-sectional view shown in C of FIG. 6. Sectional drawing of the 5th Example of this invention. The perspective view of the weight body with a step in a 5th Example. Sectional drawing of the 6th Example of this invention. FIG. 13 is an enlarged partial cross-sectional view shown in D of FIG. 12.

Explanation of symbols

9 Housing 10 Straight wall 11 Invert 12 Outflow pipes 13a to 13d Weight body 14 Slope 15 Connecting bracket

Claims (12)

A method for preventing a manhole from rising, wherein a weight body for preventing floating is provided inside the assembly manhole so that 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 manhole rising prevention method according to claim 2, wherein the weight body and the inner wall surface of the assembly manhole are joined 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. The method for preventing the manhole from rising according to any one of claims 2 to 4, wherein the weight body includes a plurality of segment-like weight bodies. 6. The method for preventing a manhole from rising according to any one of claims 1 to 5, wherein the weight body is made of metal, concrete, synthetic resin, or a combination thereof. An assembly manhole characterized in that a weight body for preventing levitation is provided inside the assembly manhole and the overall apparent specific gravity is 1.0 or more. A plurality of segmented weight-preventing weight bodies are annularly arranged along the inner wall surface of the assembly manhole, and a support body having a height adjusting means is provided at the lower part of the weight body, and the overall apparent specific gravity is 1.0 or more. A manhole characterized by that. 9. The manhole according to claim 8, wherein the levitation-preventing weight body and the inner wall surface of the assembly manhole are coupled with a binder. 10. The manhole according to claim 8, wherein a through-hole through which a footrest provided inside the assembly manhole is inserted is provided in the segment-like weight for preventing levitation. 10. 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 7 to 11, wherein the weight body is made of metal, concrete, synthetic resin, or a combination thereof.

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