JP2013249655A - Storage tank subjected to buoyancy countermeasure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide buoyancy countermeasures for a simpler storage tank reliably operating and buried underground.SOLUTION: A storage tank of the first invention, which is buried underground to serve as storage facilities for rainwater and the like, includes a water collector, communicates with the water collector, and has a bottom of the water collector opened toward the ground. A storage tank of the second invention, which is buried underground to serve as the storage facilities for the rainwater and the like, includes piping which communicates in the storage tank, and has a check valve provided at the in-storage-tank end of the piping.

Description

The present invention belongs to a buoyancy countermeasure technique using groundwater applied to a storage tank such as rainwater buried underground.

In a storage tank buried underground, buoyancy occurs in the storage tank when the groundwater level reaches the side of the storage tank. As a matter of course, a concrete storage tank is recently susceptible to the influence of buoyancy because a resin tank in which resin blocks are arranged vertically and horizontally and its periphery is covered with sheets is small in weight. Such a tank responds by making the earth pressure covering the upper part larger than the buoyancy applied to the tank. However, if sufficient ground cover thickness cannot be obtained due to the location of the installation site, groundwater will rise unexpectedly due to torrential rain after designing and construction on the premise that the groundwater layer is not sufficiently low to rise to the side of the tank It is not easy.
As a countermeasure, Japanese Patent Laid-Open No. 10-72090 is provided with a floating ring at the upper end of the bellows which also serves as a pipe, and groundwater from outside the tank is introduced so that there is always a floating ring above the groundwater layer. Technology is disclosed.

JP-A-10-72090

This invention exists in the proposal of the buoyancy countermeasure with respect to the storage tank embed | buried under the base where operation | movement is more reliable and reliable.

The first aspect of the present invention is a storage tank embedded in the basement and used as a storage facility for rainwater, etc., provided with a water collector, the water collector and the storage tank are communicated, and the bottom of the water collector is opened to the ground. Storage tank.
The second aspect of the invention is a storage tank that is buried underground and used as a storage facility for rainwater, etc., provided with a pipe that communicates with the storage tank, and provided with a check valve at the inner end of the storage tank. is there.
According to the third aspect of the present invention, in the storage tank of the first aspect, the buoyancy due to the groundwater collected on the outer surface of the storage tank is greater than the earth pressure on the storage tank. It is the storage tank set to the position.
The fourth aspect of the invention is the storage tank according to the second aspect of the invention, wherein the operating pressure of the check valve is set to a pressure at which the buoyancy due to the groundwater accumulated on the outer surface of the storage tank is greater than the earth pressure on the storage tank. It is a tank.
When the groundwater level outside the storage tank rises and the buoyancy applied to the storage tank exceeds the earth cover pressure, the groundwater flows into the storage tank via the water collector or check valve, and the buoyancy applied to the storage tank is increased. It was able to be solved.

The storage tank of the first aspect of the present invention is (1) provided with a water collector that opens to the base, and when the groundwater level rises because the water collector and the storage tank are communicated, the groundwater flows from the water collector into the storage tank, Eliminates buoyancy on the storage tank.
The storage tank of the second aspect of the present invention is (2) a check valve is provided at the end of the pipe that opens to the outside of the tank and has an end inside the tank. Groundwater flows in and the buoyancy applied to the storage tank is eliminated.
In the storage tank of the third aspect of the invention, (3) the horizontal level of the pipe communicating the storage tank and the water collector is set at a position where the buoyancy due to the groundwater collected on the outer side of the storage tank is greater than the earth pressure on the storage tank. Therefore, even when the covering thickness is not sufficient, groundwater flows into the storage tank before the buoyancy reaches a dangerous level, so that the buoyancy applied to the storage tank can be eliminated.
In the storage tank of the fourth invention, (4) the check valve provided in the tank is set to operate when the buoyancy due to the groundwater accumulated on the outer surface of the storage tank is greater than the earth pressure on the storage tank. Even when the covering thickness is not sufficient, groundwater flows into the tank before the buoyancy reaches a dangerous level, so that the buoyancy applied to the storage tank can be eliminated.

It is a conceptual diagram of the storage tank which gave the buoyancy countermeasure which is this 1st invention. It is another conceptual diagram of the storage tank which gave the buoyancy countermeasure which is this 2nd invention. It is a conceptual diagram of the storage tank which gave the buoyancy countermeasure which is this 3rd invention. It is a conceptual diagram at the time of applying to the general storage tank using a unit member. It is a conceptual diagram of the general storage tank using a unit member. It is a figure which shows the example of a unit unit.

The first invention will be described below with reference to the drawings.
As shown in FIG. 1, the storage tank to which the buoyancy countermeasure according to the present invention is applied includes a storage tank and a water collector communicating therewith. The bottom of the water collector opens to the base, and when groundwater rises, it flows into the water collector preferentially. When the water level in the water collector rises above the pipe level that connects the water collector and the storage tank, groundwater flows into the storage tank and the buoyancy applied to the storage tank is eliminated.
The base portion is preferably a crushed stone foundation so that the opening facing the base of the water collector can flow into the water collector without resistance when the groundwater rises.
Although the position of the water collector is set outside the storage tank in the figure, there is no problem even if it is set inside the storage tank.

The second invention will be described below with reference to the drawings.
FIG. 2 shows a storage tank using a check valve as a countermeasure for buoyancy. The check valve has an outer end opened outside the storage tank and the other end inside the storage tank. A check valve is provided at the inner end of the storage tank. When the groundwater level rises, groundwater flows into the check valve, and when the pressure exceeds the set pressure, the check valve acts and the groundwater flows into the storage tank to eliminate buoyancy.
In the figure, the check valve opens to the bottom of the storage tank and rises vertically, but there is no problem even if it is provided in the horizontal direction. There are various types of check valves, but for storage tanks used to control spillage that temporarily accumulates rainwater, a swing type check valve consisting of a lid fixed by a hinge at the end of a simple pipe It's okay.

In the above storage tank, there may be a case where the storage tank is constructed under a condition where the covering thickness is not sufficient, or the construction is performed under a condition where the groundwater level does not rise from the bottom of the storage tank. Even in such a case, the groundwater level may rise before the rainwater flows into the storage tank due to a heavy rain. In such a case, it is necessary to cope with an increase in the groundwater level that generates buoyancy that exceeds the earth pressure.

Buoyancy can be eliminated by setting the horizontal level H of the communication pipe connecting the water collector and the storage tank to a value corresponding to the earth pressure.
The buoyancy that balances the buoyancy applied to the storage tank with the soil cover pressure generated by the thickness of the cover is obtained by calculation. That is, as shown in FIG. 3, the density of the backfill soil for the earth covering is σ1, the earth covering thickness is h1, the height of the groundwater level from the tank bottom is h2, and the water density is σ2. For example, when the earth covering pressure σ1 * h1 and the buoyancy σ2 * h2 are equal, the groundwater may flow into the storage tank from the communication pipe. In consideration of safety, H <h2 = (σ1 / σ2) * h1 is set.
In the case of a simple swing type check valve, the position of the check valve may be set to a position lower than h2.

FIG. 4 shows an example of a storage tank in which unit members are arranged vertically and horizontally to form a storage space and the periphery thereof is covered with sheets.
FIG. 4a shows an example in which the water collector is provided outside the storage tank. FIG. 4b is an example using a check valve.
A space in which the check valve is provided is provided in the arrangement of the unit units, that is, a necessary number of unit units are removed, and the check valve is provided in the space thus formed. As necessary, the periphery of the check valve is enclosed so that the arrangement of the unit members forming the storage space is not disturbed.

FIG. 5 exemplifies a general storage tank displaying a mud pool, an inflow / outlet and an orifice as an auxiliary facility of the storage tank.
Any type of storage tank whose wall surface is made of concrete, resin, or covered with a sheet is applicable to a tank constructed in a place or design condition where it may be affected by buoyancy.

FIG. 6 is a diagram illustrating an example of the unit unit. It can be applied to a unit unit made of resin or a thin metal plate and used as a storage and penetration facility for rainwater or the like.

Tanks that are buried underground such as rainwater and other storage tanks and fire prevention water tanks, and generate buoyancy in groundwater, can be used as a measure for buoyancy.

DESCRIPTION OF SYMBOLS 1 Water storage tank 2 Water collector 3 Air vent pipe 4 Water collector bottom opening 5 Reservation tank and water collector connection piping 4 Check valve 5 Check valve piping 6 Check valve tank outside opening

Claims (4)

In a storage tank buried underground and used as a storage facility for rainwater, etc., a water collector is provided, the water collector and the storage tank are communicated, and the bottom of the water collector is opened to the ground. In a storage tank buried underground and used as a storage facility for rainwater or the like, a storage tank provided with a pipe communicating with the storage tank and provided with a check valve at the inner end of the storage tank. The storage tank according to claim 1, wherein the position of a pipe communicating the storage tank and the water collector is set to a position where buoyancy due to groundwater accumulated on the outer surface of the storage tank is greater than the earth pressure on the storage tank. The storage tank according to claim 2, wherein the operating pressure of the check valve is set to a pressure at which buoyancy due to groundwater accumulated on the outer surface of the storage tank is greater than the earth pressure on the storage tank.