JP5813569B2 - Rainwater penetration dredging method - Google Patents

Description

  The present invention relates to a novel construction method for embedding rainwater seepage pits in the ground.

  In recent years, flood damage due to localized heavy rain (so-called guerrilla heavy rain) has frequently occurred. The guerrilla heavy rain has a feature that the amount of rainfall per unit time is extremely large. In the suburbs, for example, fields, forests, ponds, and the like play a role in storing water, so that a large amount of rainwater can be stored. On the other hand, in the urban areas, although sewerage has been established, a large amount of rainwater due to heavy guerrilla rain flows into the sewer in a short time, so that it immediately overflows and causes a lot of inundation damage. For this reason, measures have been taken to install underground water tanks, especially in urban areas, but if the water passage from the ground to the underground water tank exceeds the allowable amount, it will eventually lead to inundation damage. In fact, the installation of underground water storage tanks is by no means a sufficient countermeasure.

  On the other hand, the installation of a rainwater infiltration tank that can immediately store a large amount of rainwater is attracting attention. Since the opening of the rainwater infiltration trough is buried toward the ground, it is possible to directly store rainwater and to infiltrate into the ground thereafter. As a result, it is possible to avoid or alleviate the situation where a large amount of rainwater flows into the sewer in a short time. Such rainwater permeation pits are buried by, for example, a method of digging a hole on the ground, laying chestnut stone, gravel or the like on the bottom, and installing the rainwater permeation pits thereon (Patent Document 1, Patent Document 2, etc.).

JP 10-168983 A JP 9-4034 A

  However, since the shape of the rainwater penetrating ridge is vertically long as in these prior arts, it is necessary to provide such a vertically long hole (excavation mine), but the construction period is relatively long in the normal excavation method, There is room for improvement in this regard.

  Moreover, particularly in urban areas, there is a high demand for space saving in places where rainwater seepage dredgers are installed, so the openings are smaller, and it is necessary to provide deeper holes to maintain higher water storage capacity. However, it is not easy to form such a drilling pit by a normal construction method.

  Therefore, the main object of the present invention is to provide a construction method that can be installed efficiently even with deeper rainwater infiltration troughs with smaller openings.

  As a result of intensive studies in view of the problems of the prior art, the present inventor has found that the above object can be achieved by employing a construction method including a specific process, and has completed the present invention.

That is, the present invention relates to the following rainwater seepage dredging method.
1. A method for burying a rainwater infiltrating basin having a rainwater discharge hole at least at the bottom,
(1) A step of arranging the tubular casing for excavation at the excavation position;
(2) a step of providing an excavation pit by excavating the ground in the casing while press-fitting the casing into the ground;
(3) forming a water permeation layer at least at the bottom of the excavation mine;
(4) A step of disposing a rainwater seepage rod in the excavated space in the casing,
(5) A method for embedding a rainwater infiltration basin, including a step of filling a concrete , which is a slurry-like composition, into a gap between the rainwater infiltration basin and the ground while pulling up the casing.
2. Item 5. The embedding method according to Item 1, wherein in the step (5), the step is performed while filling a space corresponding to the amount of the casing pulled up with concrete which is a slurry-like composition .
3. Item 3. The embedding method according to Item 1 or 2, wherein in the step (5), the step is carried out while supporting a rainwater infiltration tub with the casing.
4). Item 4. The embedding method according to any one of Items 1 to 3, wherein a rainwater discharge hole is further provided on a side surface of the rainwater infiltration tub.
5. Item 5. The embedding method according to any one of Items 1 to 4, wherein the rainwater seepage trough has a cylindrical shape.
6). Item 6. The embedding method according to any one of Items 1 to 5, wherein the rainwater seepage trough is arranged so that a longitudinal direction thereof is perpendicular to the ground.

  According to the embedding method of the present invention, the opening can be made smaller, and even deeper rainwater infiltration can be efficiently installed. Thereby, it is possible to install a rainwater infiltration tank having a larger water storage capacity in a narrow space. In particular, it is also possible to relatively easily install an elongated rainwater infiltration tub that is difficult to install by conventional methods. For this reason, a large amount of rainwater due to guerrilla heavy rain can be immediately stored and can be infiltrated into the ground. As a result, it is possible to reduce the amount of rainwater flowing into the sewer and contribute to the prevention of inundation and flooding on the ground.

  Moreover, in the construction method of the present invention, since the removal of the excavation casing and the filling of the filler are performed in parallel, the construction period can be completed in a relatively short period. For example, in the case of placing using a water kneaded material such as concrete as the filler, the water kneaded material is filled in the gap between the rainwater penetrating gutter and the ground while pulling the tubular casing for excavation upward. Can be fixed at the same time as curing the walls and bottom of the excavation mine. This can also contribute to shortening the construction period.

  Furthermore, by preparing a plurality of excavation casings with different inner diameters, it is possible to cope with installation according to the space at the installation location, etc. It can also be installed.

It is the schematic which shows the process of this invention construction method. It is the schematic which shows the process of this invention construction method. It is the schematic which shows the process of this invention construction method. It is the schematic which shows the process of this invention construction method. It is the schematic which shows the process of this invention construction method. It is the schematic which shows the process of this invention construction method. It is the schematic which shows the process of this invention construction method. FIG. 8A is a perspective view of a tubular casing for excavation used in the method of the present invention. FIG. 8B is a schematic view of the excavating tubular casing used in the method of the present invention as seen from the side.

The method for burying rainwater infiltration basin in the present invention is a method for burying rainwater infiltration basin having at least a rainwater discharge hole in the ground,
(1) A step of arranging the tubular casing for excavation at the excavation position (casing arrangement step),
(2) A step of digging the ground in the casing while press-fitting the casing into the ground (press-fitting / digging step),
(3) forming a water-permeable layer at least at the bottom of the excavation mine (water-permeable layer forming step);
(4) A step of arranging a rainwater infiltration tub in the excavated space in the casing (rainwater infiltration basin arrangement step),
(5) A step of filling the gap between the rainwater infiltration trough and the ground while pulling up the casing upward (filling step)
It is characterized by including. Each step will be described below.

Casing Arrangement Step In the casing arrangement step, the excavating tubular casing is arranged at the excavation position. As the tubular excavation casing (hereinafter also simply referred to as “casing”), a known or commercially available one can be used. As the shape of the tubular excavation casing, for example, as shown in FIG. 8A, a cylindrical casing 1 having an upper opening 2 and a lower opening 3 can be suitably used. Moreover, as shown in FIG.8 (b), the edge part of the downward opening part 3 of the casing 1 is processed into the tooth shape so that it may be easy to press-fit in the ground.

  The size of the tubular excavation casing can be appropriately set according to the size of the tanks to be embedded. Further, only one casing may be used, or two or more casings may be used in succession. When two or more are used, they may be joined together by welding or the like.

In the press- fitting / digging step, the ground in the casing is excavated while the casing is press-fitted into the ground. The press-fitting and excavation process itself can be performed by using a rocking press-fit type shaft construction machine (rocking press-fitting machine) according to a known method (so-called PIT method). For example, the tubular casing for excavation may be pressed into the ground while swinging, and the ground in the casing where the earth is retained is excavated to construct a shaft. In this case, the excavator can reach the inside from the outside of the excavating tubular casing, excavate the ground in the region surrounded by the casing, and excavate the earth and sand out of the casing.

  If the tubular excavation casing is pressed into the basement to some extent, it may be difficult to press the tubular excavation casing directly with a rocking press-fitting vertical shaft construction machine. By adding the temporary casing onto the excavating casing and press-fitting the temporary casing with the swing press-fit type shaft construction machine, the tubular excavating casing can be completely pressed into the ground. After the tubular excavation casing is press-fitted into the ground, the temporary casing may be removed.

  The excavation mine formed by excavation uses a casing and thus has a substantially cylindrical shape corresponding to the casing. In the present invention, it is particularly preferable to have a vertically long shape. In other words, it is desirable to make the excavation shaft deeper than the diameter of the excavation shaft. For example, it is preferable to form a drilling pit having a depth of 1.5 times or more (particularly twice or more) the diameter of the digging mine. Thereby, since the rainwater permeation gutter can be installed vertically long, space saving etc. can be achieved.

Water-permeable layer forming step In the water-permeable layer forming step, a water-permeable layer is formed at least at the bottom of the excavation mine.

  The water permeation layer can be the same as that used in the installation of a normal rainwater permeation dredger. For example, it can be formed by spreading gravel, chestnut, river stone, crushed stone, concrete aggregate, river sand, etc. at the bottom of the excavation mine. The size of gravel and the like used here is not limited, but usually within a range of about 0.5 to 10 cm in diameter, for example, depending on the size of the rainwater infiltration basin to be installed, the speed at which rainwater permeates, etc. It can be set appropriately.

  In addition, the thickness (height) of the water infiltration layer is not particularly limited, but generally can be appropriately set within a range of about 1 to 100 cm according to, for example, the size of the rainwater infiltration tank to be installed.

  In the present invention, the rainwater infiltration trough has at least a rainwater discharge hole at the bottom, but a rainwater discharge hole can also be provided on the side of the rainwater infiltration trough as necessary. In this case, a water permeation layer can also be formed on the side surface of the excavation mine. In this case, it is only necessary to fill the gap between the rainwater infiltration basin and the excavation mine with the filler as described above after the rainwater infiltration basin is arranged.

Rainwater seepage trough placement step In the rainwater seepage trough placement step, a rainwater seepage trough is placed in the excavated space in the casing. In this case, the rainwater seepage trough is loaded from the upper opening of the tubular casing and lowered to the excavated bottom (ground). Raising and lowering the rainwater seepage rod at this time may be performed using a general crane or the like.

  In the rainwater seepage trough arrangement step, it is preferable to arrange the rainwater seepage trough so that the longitudinal direction of the rainwater seepage trough is perpendicular to the ground. For example, as shown in FIG. 4, in the case of a cylindrical rainwater seepage rod, it may be arranged so that its bottom surface lands on the bottom.

  The rainwater permeation tank itself used in the present invention is not particularly limited, and known or commercially available ones can be used. Accordingly, for example, a rainwater infiltration trough having a plurality of rainwater discharge holes only on the bottom surface, a rainwater infiltration trough having a plurality of rainwater discharge holes on the bottom and side surfaces, a rainwater infiltration trough having a plurality of rainwater discharge holes having a connection pipe attached, etc. Any of these can be employed.

  Further, the material constituting the rainwater permeating trough is not limited, and may be any of synthetic resin (polypropylene resin, polyvinyl chloride resin, etc.), metal, concrete (including secondary concrete products), and the like. good. In addition, when using a rainwater-impregnated basin made of synthetic resin with a specific gravity lighter than that of water and using an aqueous slurry such as concrete or mortar as a filler in the filling step described later, the rainwater-permeable basin is an aqueous slurry (before curing). For example, it is possible to omit the step of previously forming the concrete foundation floor on the floor surface of the region where the rainwater infiltration tub is disposed. Examples of the synthetic rainwater penetrating basin include a rainwater penetrating basin composed of a thermoplastic resin or a thermosetting resin, and a rainwater penetrating basin composed of fiber reinforced plastic (FRP) reinforced with these synthetic resins. A cocoon can be used suitably. For these, a known or commercially available rainwater permeation can be adopted.

  The shape of the rainwater infiltration tub is not particularly limited, and may be any of a rectangular parallelepiped, a cube, a cylinder, and the like, but in general, a cylindrical rainwater infiltration basin can be suitably used. That is, it is possible to use a rainwater permeation rod having a circular horizontal cross section. More specifically, a rainwater infiltration rod having a shape whose length L is larger than the outer diameter d of the rainwater infiltration rod (that is, a relationship of d <L) can be suitably used. More preferably, a rainwater infiltration tub having a length L of 1.5 times or more (particularly 2 times or more) of the outer diameter d is used.

  Further, the outer diameter d of the cylindrical rainwater seepage rod is not particularly limited as long as it is smaller than the inner diameter D of the casing, but is preferably within a range of about 85 to 98% of the inner diameter D of the casing. Thereby, since the rainwater permeation basket can be effectively supported by the casing, it is possible to efficiently install the rainwater penetration tank.

Filling step In the filling step, the filler is filled in the gap between the rainwater infiltration trough and the ground while pulling up the casing upward. As a means for pulling up the casing, a known crane or the like (hydraulic rocker) may be used. Further, the pulling method may be any of a method of pulling up intermittently in addition to a method of pulling up at a constant speed.

  Any filler can be used as long as it can substantially fix the rainwater seepage by filling the gap. For example, concrete, mortar, gravel, aggregate, sand and the like can be used.

  It is preferable that the filling with the filler is basically performed while filling the space corresponding to the amount of the casing pulled up with the filler. That is, a space is formed when the casing is pulled up, but a sufficient amount of filler is filled in order to fill the space. Thereby, the filling of the filler and the lifting of the casing can be performed in parallel, which can contribute to shortening the construction period.

  After the casing is pulled up and the filler is filled in order, and all the casing is pulled up, the entire area other than the top surface of the rainwater infiltration tub is filled with the filler. When a water kneaded material such as concrete or mortar is used as the filler, the rainwater permeation cage is fixed in the ground with a hardened body by curing after curing.

  The features of the present invention will be described more specifically with reference to examples. However, the scope of the present invention is not limited to the examples.

Example 1
An example of a method for burying rainwater seepage dredging according to the construction method of the present invention will be described with reference to the drawings. First, as shown in FIG. 1, the excavating tubular casing 1 is disposed at the excavation position of the ground 21. The casing 1 is a steel tubular casing as shown in FIG. 8, and two casings having an outer diameter of about 2.5 m × a length of about 2.5 m are joined together by welding.

  Next, as shown in FIG. 2, the excavating tubular casing 1 is press-fitted into the ground in the vertical direction using a commercially available rocking press-fitting machine (not shown). The verticality of the casing 1 may be measured by an inclinometer or the like. Then, the ground in the excavating tubular casing 1 is excavated by an excavator. In this case, the press-fitting depth and the excavation depth are monitored so that the press-fitting of the casing always precedes the excavation. The excavated earth and sand are discharged out of the excavating tubular casing 1 and transported to another place by a dump truck or the like. In this way, the excavating tubular casing 1 descends into the ground by the amount that has been press-fitted and excavated. By proceeding with such work, the excavated tubular casing 1 is finally embedded in the ground 21 as shown in FIG. Thereby, an excavation mine is formed.

  Next, as shown in FIG. 3, the water permeation layer 31 is formed by spreading gravel on the bottom of the excavation mine. The gravel used here was about 5 to 10 cm in size, and the thickness of the water-permeable layer was about 50 cm.

  Thereafter, as shown in FIG. 4 (a), a concrete rainwater infiltration rod 41 is disposed in the space of the excavating tubular casing 1 embedded in the ground. The rainwater infiltration trough 41 is provided with a concrete slab material 42 at the bottom, and a plurality of rainwater discharge holes (diameter about 50 mm) are formed in the concrete slab material 42 as shown in FIG. . The size of the rainwater infiltration tub is about 2.5 m in outer diameter and about 5 m in length. For the excavation, the rainwater penetration rod 41 is lifted with a crane machine so that the opening (rainwater inflow port) of the rainwater penetration rod 41 is upward and the longitudinal direction of the rainwater penetration rod 41 is substantially perpendicular to the ground. Insert inside the tubular casing 1. In this case, depending on the weight of the rainwater infiltrating rod to be installed, prior to the arrangement of the rainwater infiltrating rod 41, concrete may be placed on the bottom (ground) of the excavated excavation mine to form a bottom slab in advance. good.

  Next, as shown in FIG. 5, the rainwater infiltration basin 41 is lowered to the bottom of the excavated ground and settled down. In this case, if necessary, a water-permeable layer can also be formed on a part or all of the side surface by filling gravel also on the side surface (the gap between the excavating tubular casing and the rainwater-permeable rod).

  After the rainwater seepage trough is settled on the bottom of the excavation pit, concrete (mortar) is placed while the excavation tubular casing 1 is pulled up (removed). In FIG. 6, the state which pulled up the tubular casing 1 for excavation a little is shown. The excavation tubular casing is pulled up using a crane or the like. Then, as shown in FIG. 6, concrete 22 is placed in a portion corresponding to the portion where the tubular casing for excavation 1 is pulled up. While repeating these series of steps, the periphery of the rainwater infiltration basin is filled with concrete (slurry composition). Finally, after the tubular casing 1 for excavation is completely pulled up, as shown in FIG. 7, the entire surrounding area of the rainwater infiltration basin 41 is filled with concrete and cured to be fixed with a hardened concrete. At the same time, the wall surface and bottom of the excavation mine are protected by the hardened concrete. In this way, the rainwater seepage rod 41 can be buried in the ground. Moreover, as shown in FIG. 7, you may form the water penetration layer 31b by spreading gravel also in the bottom part in the rainwater penetration tank 41 as needed.

Claims (6)

A method for burying a rainwater infiltrating basin having a rainwater discharge hole at least at the bottom,
(1) A step of arranging the tubular casing for excavation at the excavation position;
(2) a step of providing an excavation pit by excavating the ground in the casing while press-fitting the casing into the ground;
(3) forming a water permeation layer at least at the bottom of the excavation mine;
(4) A step of disposing a rainwater seepage rod in the excavated space in the casing,
(5) A method for embedding a rainwater infiltration basin, including a step of filling a concrete , which is a slurry-like composition, into a gap between the rainwater infiltration basin and the ground while pulling up the casing. The embedding method according to claim 1, wherein in the step (5), the step is performed while filling a space corresponding to a portion where the casing is pulled up with concrete which is a slurry-like composition . The embedding method according to claim 1 or 2, wherein, in the step (5), the step is carried out while supporting a rainwater infiltration tub with the casing. The embedding method according to any one of claims 1 to 3, further comprising a rainwater discharge hole on a side surface of the rainwater permeation trough. The embedding method according to any one of claims 1 to 4, wherein the rainwater seepage trough has a cylindrical shape. The embedding method according to any one of claims 1 to 5, wherein the rainwater seepage trough is arranged so that a longitudinal direction thereof is perpendicular to the ground.