JPS6334275B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of constructing an underground tank and a water collector used in the implementation.

Generally, the construction of an underground tank involves digging a hole in the ground.
This is generally done by forming the tank side wall with concrete cast on site or with precast concrete, and then forming the tank bottom plate with concrete cast on site.

At this time, when forming the tank bottom slab, groundwater is likely to seep out, and if there is a large amount of spring water, it will hinder construction work. For this reason, conventionally, the area where the tank bottom slab was formed was surrounded by earthen retaining sheet piles, a part of which was widened to create a recess for collecting water, and spring water was pumped out from within this recess to lower the groundwater level. The situation was maintained and enforced.

However, this method has the disadvantage that the water collection recess projects outward from the side wall of the tank, which increases the construction area of the retaining sheet pile, and requires digging a hole much larger than the side wall of the tank.
Also, when pouring concrete for the tank bottom,
The problem was that the concrete flowed into the water collection recess and filled it up.

The purpose of the present invention is to provide a method for constructing an underground tank that can effectively pump out spring water without digging an extra-sized hole and to allow concrete to be placed without any problems, and a water collector used to carry out the method. is to provide.

The structure of the present invention which achieves such an object includes the method for constructing an underground tank in which a hole is dug in the ground, a tank side wall is formed in the hole, and then a tank bottom plate is formed by placing cast-in-place concrete on the bottom of the hole. Before forming the tank bottom plate, a water collector consisting of a cylindrical body having a water collection port at the lower end and a water stop plate that can freely close the water collection port of the cylinder is installed at the lowest part of the hole. The tank bottom plate is formed by burying the board in a state away from the water collection port, and draining the spring water flowing from the water collection port from within the water collection device to lower the water level of the spring water, and forming the tank bottom plate. After carrying out water-stop treatment on the inner surface of the tank except for the water-stopping plate, the water collection port is closed using the water-stop plate, and then cast-in-place concrete is placed at the inner bottom of the water collector to form a water-tight water collector bottom plate. A method for constructing an underground tank, a cylindrical body having an open upper end and a water collection port at the lower end, a water stop plate that faces the water collection port and can freely come into contact with and separate from the water collection port, and a guide hole formed in the peripheral wall of the cylindrical body. a water stop plate support shaft that is slidably inserted in the axial direction and has the water stop plate fixed to its lower end; and a stop that is interposed between the water stop plate and the edge of the water collection port when the water collection port is closed by the water stop plate. Equipped with a water pack,
The present invention relates to a water collector used in constructing an underground tank, which is buried in the bottom of the tank to collect spring water, and after the tank is constructed, to collect the remaining water when the tank is drained.

Next, embodiments of the present invention will be described in detail with reference to the drawings. First, an embodiment of the water collector of the present invention will be described with reference to FIGS. 1 and 2.

This water collector 1 uses a water collection cylinder 2 made of precast concrete. This water collection cylinder 2 has a cylindrical shape with an open top and bottom, and in the circumferential wall thereof, in some embodiments, four guide holes 3 penetrating vertically are formed at equal intervals. The lower opening of this cylindrical body 2 is a water collection port 5, and a water stop plate 4 made of an iron plate is provided opposite to the water collection port 5 so as to be able to come into contact with and separate from it. The water stop plate 4 opens the water collection port 5 when separated from the water collection cylinder 2, and closes the water collection port 5 when in contact with the water collection cylinder 2. This water stop plate 4 has a nut 7 attached to the lower end of the water stop plate support shaft 6 passing through each guide hole 3.
and is supported by the welded portion 7a. Nuts 8 are also screwed onto the upper ends of these water stop plate support shafts 6 to prevent the water stop plate support shafts 6 from coming out downward.
The length of each water stop plate support shaft 6 is longer than the length of the water collection cylinder 2 so as to form a sufficient interval for groundwater to flow into the water collection port 5. A ring-shaped water stopper 9 made of neoprene rubber or the like is fixed to the outer periphery of the upper surface of the water stop plate 4 by adhesive.

Next, an example of a method for constructing an underground tank according to the present invention using such a water collector 1 will be explained with reference to FIGS. 3 to 6.

First, a hole is dug in the ground, and a concrete tank side wall 10 is formed inside the hole. The tank side wall 10 may be formed using cast-in-place concrete by building a formwork in a hole excavated inside by driving sheet piles as in the past, or by forming segments made of precast concrete on the ground surface. Various methods can be used, such as a method in which the side wall 10 of the tank is formed in advance by assembling it into a cylindrical shape, and the tank side wall 10 is sequentially dropped into the tank while forming a hole by digging out the earth and sand inside the tank.

After forming the tank side wall 10 in this way,
The water collector 1 described above is installed at the bottom of the tank. At this time, the water collector 1 moves the water stop plate 4 away from the periphery of the water collection port 5 and maintains the water stop plate 4 in an open state. For this reason, as shown in FIG.
A separator 1 such as a square lumber is placed between the periphery of the water stop plate 4 and the water stop plate 4.
The nut 8 at the upper end of the water stop plate support shaft 6 is tightened with the water stop plate support shaft 6 interposed therebetween. Also, the installation of water collector 1 is done in the third place.
As shown in the figure, the bottom of the hole is further dug in the area where the water collector 1 is located so that its upper end is at a height slightly lower than the height of the surface of the tank bottom plate, which will be described later. Note that one or more water collectors 1 are installed depending on the amount of spring water, and a drainage pump is installed inside the tank side wall to collect the spring water during the installation work of the water collector 1 and the formation of the tank side wall 10 described above. Insert and drain.

After installing the water collector 1 as described above, the drain pump 13 is inserted into the water collector 1 and the water collection port 5 is opened.
The inflowing spring water is drained to lower the groundwater level to the water collection port 5. In this state, the tank bottom plate will be constructed. As an example of the construction of the tank bottom plate, as shown in Fig. 3, chestnut stone 11 is first laid as a foundation over the entire lower part of the tank side wall 10 except for the water collector 1 part, and waste concrete 14 is poured on top of it. and assemble reinforcing bars (not shown). After reinforcing reinforcement inspection, tank bottom slab concrete 15 is placed. About 10 hours after pouring, the submersible pump 13 is stopped and the tank bottom slab concrete 15 is cured underwater.

After curing of the tank bottom concrete 15 is completed, the submersible pump 13 is operated again to drain the spring water. Once the groundwater level has been stabilized, the work inside the water collector 1 is carried out in the following manner.

(1) A worker enters the water collector 1, loosens the nuts 8 of each water stop plate support shaft 6 from the upper end, and taps each water stop plate support shaft 6 downward with a hammer to tighten the water stop plate 4 by about 1 cm. Lower it.

(2) Remove the separator 12 in this state.

(3) Remove sand, small gravel, etc. from the water stop plate 4.

(4) Tighten each water stop plate support shaft 6, raise the water stop plate 4, and bring it into contact with the lower surface of the water collection cylinder 2 via the water stop gasket 9 to close the water collection port 5.

(5) Tighten nut 8 sufficiently to stop the water from leaking out.

(6) If multiple water collectors 1 are used, perform the same operation for the other water collectors 1.

(7) Stop the submersible pump 13.

(8) Water seeping into the water collector 1 is stopped by filling the space between the water collection cylinder 2 and the water stop plate 4 using a rapidly hardening cement 16.

(9) A predetermined connecting bar 17 is inserted into the water collection cylinder 2, and rapidly hardening concrete is poured to form the water collection bottom plate 18.

(10) Loosen the nuts 8 one by one, inject the quick-hardening mortar 19 into the guide holes 3 to stop the water in the guide holes 3, and tighten the nuts 8. This operation is performed for all the water stop plate support shafts 6.

(11) After the paste or mortar hardens, the tip of each waterstop support shaft 6 is cut and removed using gas.

(12) Place waterproof mortar 20 on the tank bottom concrete 15 and water collector bottom 18.

Note that the water stop gasket 9 may be attached to the lower surface of the water collection cylinder 2.

Moreover, drainage in the water collector 1 can also be carried out by inserting a drainage hose into the water collector 1 and operating a drainage pump on the ground.

As explained above, in the method for constructing an underground tank according to the present invention, a water collector with a special structure is set at the formation point of the tank bottom plate, and water flows into the water collector from the openable/closable water collection port at the bottom. While draining the water, pouring concrete for the bottom of the tank, etc.
It is possible to form the tank bottom plate without being disturbed by spring water. By setting a water collector in the area where the tank bottom plate is formed in this way, it becomes unnecessary to use earth retaining sheet piles, etc. to drain spring water, and it is not necessary to dig a hole larger than the capacity of the tank, which reduces costs. Therefore, the construction period can be shortened. In particular, since the water collector of the present invention has a water collection port at the bottom, concrete will not flow through the opening of the water collector during pouring of tank bottom slab concrete, and drainage work can be carried out without being obstructed by the concrete. Can be done. In addition, in this water collector, the water stop plate is supported by a water stop plate support shaft that penetrates inside the peripheral wall of the water collection cylinder, and the water stop plate can be lowered by lowering or raising the water stop plate support shaft. Since the water collection port is opened and closed by raising the water collection device, the water collection port can be opened and closed from the top of the water collection device, which has the advantage of good workability.

[Brief explanation of the drawing]

Fig. 1 is a plan view showing the water collector of the present invention, Fig. 2 is a vertical sectional view thereof, and Fig. 3 shows the process of forming the bottom plate of an underground tank while opening the water collection port and discharging water by the method of the present invention. FIG. 4 is a vertical cross-sectional view of the main part of the underground tank in the completed state, and FIGS. 5 and 6 are views of the water collector according to the present invention when the water collection port is open FIG. 3 is a vertical cross-sectional view of each main part when closed. 1...Water collector, 2...Water collection cylinder, 3...Guide hole, 4
...Water stop plate, 5...Water collection port, 6...Water stop plate support shaft, 7,
8... Nut, 9... Water stop packing, 10... Tank side wall, 11... Chestnut stone, 12... Separator, 13... Submersible pump, 14... Waste concrete, 15... Tank bottom plate concrete, 18... Water collector bottom plate.

Claims (1)

[Scope of Claims] 1. In a method for constructing an underground tank, which involves digging a hole in the ground, forming a tank side wall in the hole, and then forming a tank bottom plate with cast-in-place concrete on the bottom of the hole, before forming the tank bottom plate. At the bottom of the hole, a water collector consisting of a cylinder having a cylindrical shape and a water collection port at the lower end, and a water stop plate that can freely close the water collection port of the cylinder,
The water stop plate is buried in a state where it is separated from the water collection port, and the spring water flowing from the water collection port is discharged from the water collection device to lower the water level of the spring water while forming the tank bottom plate. After applying a water stop treatment to the inner surface of the tank except for the water collector, the water collection port is closed using the water stop plate, and then cast-in-place concrete is placed at the inner bottom of the water collector to form a water-tight water collector bottom plate. How to build an underground tank featuring: 2. A cylindrical body whose upper end is open and has a water collection port at its lower end, a water stop plate that faces the water collection port and can come into contact with and separate from the water stop plate, and a water stop plate that slides in the axial direction of the cylinder through a guide hole formed in the peripheral wall of the cylindrical body. A water stop plate support shaft that is freely inserted through the shaft and has the water stop plate fixed to its lower end, and a water stop gasket that is interposed between the water stop plate and the edge of the water collection port when the water collection port is closed by the water stop plate, When constructing the tank,
A water collector used to construct an underground tank that is buried at the bottom of the underground tank to collect spring water and, after the tank is constructed, to collect the remaining water when the tank is drained.