JP2012002053A - Construction method for burying tank and the like - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a construction method capable of effectively burying a tank and the like with a less work range.SOLUTION: A construction method to bury tank and the like in the ground includes the processes: (1) to install a tubular casing 1 for excavation at a position to be excavated; (2) to excavate the ground 20 inside the casing while pressing the same into the ground; (3) to install a tank and the like 21 in an excavated space in the casing; and (4) to cast concrete 22 in a gap between the tank and the like and the ground while pulling the casing upward.

Description

  The present invention relates to a novel construction method for embedding tanks in the ground.

  Tanks used as septic tanks, water storage tanks, etc. are often buried in the ground from the viewpoint of effective use of land. Various methods for burying these tanks have been proposed. For example, a step of providing a base floor for installing the underground storage tank in an underground space in which the underground storage tank is buried, and a tank fixing auxiliary tool is attached to the underground storage tank, and the base floor is placed at an appropriate position on the foundation floor. In the underground storage tank embedding method, comprising the step of installing an underground storage tank and the step of filling the underground space with a filling material together with the installed underground storage tank, the underground space is installed in the underground A method for burying an underground storage tank, further comprising a step of removing the tank fixing auxiliary tool from the underground storage tank by crushing the tank fixing auxiliary tool together with the storage tank before the step of filling with a filling material. It has been proposed (Patent Document 1). In addition, a method of burying tanks in the ground improvement body is known (Patent Document 2).

  By the way, although tanks made of FRP (fiber reinforced plastic) are widely used as tanks, horizontally long tanks have been used more than ever. For example, as shown in FIG. 10, a conventional FRP tank 31 is provided with a water intake port 33 on a side surface 32 in the longitudinal direction, and the water intake portion 33 comes out on the ground. It is buried in.

JP-A-10-297692 JP 2006-138091 A

  However, when embedding a horizontally long tank as described above, a large space for digging up the ground into a horizontally long shape is required, so that the work range may straddle a public road or another person's site. For this reason, it is difficult to secure a range in which work can be performed effectively for a long period of time. It can be said that this problem tends to become more serious especially in the city center.

  In addition, although the conventional burying method can be carried out with a small work range, in the present situation where a shorter work period is required, further improvement is required in terms of work efficiency and the like.

  Accordingly, a main object of the present invention is to provide a construction method capable of efficiently burying tanks with a smaller work range.

  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 tank embedding method.
1. A method for burying tanks in the ground,
(1) A step of arranging the tubular casing for excavation at the excavation position;
(2) a step of excavating the ground in the casing while press-fitting the casing into the ground;
(3) a step of arranging tanks in the excavated space in the casing;
(4) A method for embedding tanks, including a step of placing concrete in a gap between the tanks and the ground while pulling up the casing.
2. The embedding method according to Item 1, wherein in the step (4), the step is performed while filling a space corresponding to the amount of the casing pulled up with concrete.
3. Item 3. The embedding method according to Item 1 or 2, wherein in the step (4), the step is performed while supporting the tanks with the casing.
4). Item 4. The embedding method according to any one of Items 1 to 3, wherein the tanks are made of synthetic resin.
5). Item 5. The embedding method according to any one of Items 1 to 4, wherein the tank has a cylindrical shape.
6). Item 6. The embedding method according to any one of Items 1 to 5, wherein the tanks are arranged so that a longitudinal direction thereof is perpendicular to the ground.

  According to the embedding method of the present invention, tanks can be efficiently embedded with a smaller work range. That is, since the area to be excavated can be reduced, preparation for excavation (securing of a work place, etc.) can be easily performed as compared with the case of embedding a conventional horizontal tank.

  Moreover, in the construction method of the present invention, since the removal of the excavation casing and the concrete placement are performed in parallel, the construction period can be completed in a relatively short period.

  Furthermore, in concrete placement, concrete is placed in the gap between the tanks and the ground while pulling up the tubular casing for excavation, so the tanks should be fixed and the walls and bottom of the excavation mine should be cured at the same time. Can do. This can also contribute to shortening the construction period.

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. It is the schematic which shows the process of this invention construction method. FIG. 9A is a perspective view of a tubular casing for excavation used in the method of the present invention. FIG.9 (b) is the schematic diagram which looked at the tubular casing for excavation used with this invention construction method from the side. It is the schematic of the conventional horizontal tank. It is the schematic which shows the state which attaches a bottom slab to tanks and is made to wear down. It is a schematic diagram of a bottom board slab. Fig.13 (a) is a side view of the structure which has arrange | positioned the reinforcement in the bottom slab. FIG.13 (b) is the figure which looked at the said structure from upper direction.

The method of burying tanks in the present invention is a method for burying tanks in the ground,
(1) A step of arranging the tubular casing for excavation at the excavation position (casing arrangement step),
(2) A step of excavating the ground in the casing while press-fitting the casing into the ground (press-in / excavation step),
(3) A step of arranging tanks in the excavated space in the casing (tank arrangement step),
(4) A step of placing concrete in the gap between the tanks and the ground while pulling up the casing (concrete placing 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. 9A, a cylindrical casing 1 having an upper opening 2 and a lower opening 3 can be suitably used. Moreover, as shown in FIG.9 (b), the edge part of the lower 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-fit 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 tanks can be installed vertically long, space saving etc. can be achieved.

Tank Arrangement Step In the tank arrangement step, tanks are arranged in the excavated space in the casing. In this case, the tanks are loaded from the upper opening of the tubular casing and lowered to the excavated bottom (ground). The raising and lowering of the tanks at this time may be performed using a general crane or the like.

  In the tank arrangement step, the tanks are preferably arranged so that the longitudinal direction of the tanks is perpendicular to the ground. For example, as shown in FIG. 4, in the case of a cylindrical tank, it may be arranged so that the bottom surface of the tank lands on the bottom.

  The application of the tanks used in the present invention is not particularly limited, and may be either a liquid tank or a gas tank. More specifically, for example, various tanks such as a fuel tank and a gas tank can be used in addition to a water storage tank, a fire prevention water tank, a sewage tank, a septic tank, a sedimentation tank, and a treatment tank. Moreover, the material which comprises tanks is not limited, either, for example, synthetic resin, metal, concrete (including concrete secondary products), etc. may be used. In particular, in the present invention, synthetic resin tanks can be preferably used. In particular, when using synthetic resin tanks that have a lighter specific gravity than water, the tanks can be placed on concrete (slurry before curing) in the concrete placing process described later. The step of forming the concrete foundation floor in advance on the floor surface of the area to be removed can be omitted. As the synthetic resin tanks, for example, tanks made of thermoplastic resin or thermosetting resin, and tanks made of fiber reinforced plastic (FRP) in which these synthetic resins are reinforced with fibers are suitably used. Can be used. For these, known or commercially available tanks (containers) can be employed.

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

  Further, the outer diameter d of the cylindrical tanks 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 tanks can be effectively supported by a casing, installation of tanks can be performed efficiently.

Concrete placing process In the concrete placing process, concrete is placed in the gap between the tanks and the ground while the casing is pulled 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.

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

  After the concrete is poured in order while pulling up the casing, and all the casings are pulled up, everything around the tanks other than the upper surface is filled with concrete. Then, by curing, the tanks are fixed in the ground with a hardened concrete.

  Depending on the soil and geology, groundwater may spring out. In such a case, after filling the embedding tank with water, concrete and concrete can be placed in the water using a graft pump, a tremy tube, etc., so that boiling, healing and the like can be more effectively prevented.

  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 embedding tanks according to the 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 20. This casing 1 is a steel tubular casing as shown in FIG. 9, and two casings having an outer diameter of about 2.6 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 using 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 as shown in FIG.

  Then, as shown in FIG. 4, the FRP water storage tank 21 is disposed in the space of the excavating tubular casing 1 buried in the ground. The size of this tank is about 2.5 m in outer diameter and about 5 m in length. This water storage tank 21 is lifted with a crane machine, and the excavation tube so that the water injection port (not shown) of the water storage tank 21 is upward and the longitudinal direction of the tank 21 is substantially perpendicular to the ground. Insert inside casing 1. In this case, in accordance with the weight of the tanks to be installed, the bottom slab may be formed in advance by placing concrete on the bottom (ground) of the excavated excavation mine prior to the arrangement of the water storage tank 21. . In this case, as shown in FIG. 13, reinforcing bars surrounding the tank side surface can be provided on the bottom slab as required. This reinforcing bar is covered with concrete in the subsequent concrete placing process. Installation of the reinforcing bars on the bottom slab is not particularly limited, and for example, a known method such as a method of hardening together with the reinforcing bars when forming a concrete hardened body that becomes the bottom slab, a method of fixing with a connecting tool such as an anchor bolt, etc. can be adopted. . By arranging the reinforcing bars, the strength of the hardened concrete (wall surface) formed on the side surface of the tank, the earthquake resistance, the effect of preventing water leakage, and the like can be further strengthened to protect the tank more effectively.

  After the water storage tank 1 is lowered to the bottom of the excavated ground, the excavating tubular casing 1 is pulled up (removed). In FIG. 5, 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.

  Next, as shown in FIG. 6, concrete 22 is placed in a portion corresponding to the portion where the tubular casing 1 for excavation is pulled up. While repeating these series of steps, the periphery of the tanks is filled with concrete (slurry composition) as shown in FIG. Finally, after the tubular casing for excavation 1 is completely pulled up, as shown in FIG. 8, the entire basement of the tanks 21 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 tanks 21 can be buried in the ground.

  In particular, when there is a lot of water, flowing water, etc., due to soft ground, for example, underwater excavation while storing water in the shaft being excavated, and after flooring, as shown in FIG. The bottom slab 41 is attached, and these are suspended by a crane truck and installed on the bottom of the shaft. At this time, if water is poured into the tanks and the weight is used, it can be made more stable. Thus, in the present invention, it is one of the features that a bottom slab for stabilizing tanks is attached in the tank arranging step. This prevents or suppresses the floating, tilting, etc. of the tanks, and can be used as the bottom slab concrete of the shaft bottom as it is after the tanks are placed, so that the tanks can be buried more reliably and efficiently. Is possible.

  The bottom slab 41 is not particularly limited as long as it can exert the above-mentioned role. For example, as shown in FIG. 12, the bottom plate slab 41 has a hollow portion 42 and has an anchor bolt 43 for fixing on the top surface. A circular donut-shaped concrete molded body (about 4200 kg) provided in the section can be used. The outer diameter of the bottom of the bottom slab 41 is preferably 5 to 10% larger than the outer diameter of the bottom of the tanks. The hollow portion 42 can be used for air venting and mortar injection at the bottom of the vertical pile.

Claims (6)

A method for burying tanks in the ground,
(1) A step of arranging the tubular casing for excavation at the excavation position;
(2) a step of excavating the ground in the casing while press-fitting the casing into the ground;
(3) a step of arranging tanks in the excavated space in the casing;
(4) A method for embedding tanks, including a step of placing concrete in a gap between the tanks and the ground while pulling up the casing. 2. The embedding method according to claim 1, wherein in the step (4), the step is performed while filling a space corresponding to a portion where the casing is pulled up with concrete. The embedding method according to claim 1 or 2, wherein in the step (4), the step is performed while supporting the tanks with the casing. The embedding method according to any one of claims 1 to 3, wherein the tanks are made of synthetic resin. The embedding method according to any one of claims 1 to 4, wherein the tank has a cylindrical shape. The embedding method according to any one of claims 1 to 5, wherein the tanks are arranged so that a longitudinal direction thereof is perpendicular to the ground.