JP2010053891A - Underground tank structure - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent rise of light weight coating material when an upper part of a storage tank is coated by light weight coating material. <P>SOLUTION: An underground tank structure 10 includes a reinforced concrete tank body 20 formed in a vessel shape, a retaining wall 26 erectly provided in a cylindrical shape along an outer circumference of an upper surface of a side wall 21 of the tank body 20, and a mud layer 50 having the light weight coating material 51 filled in an inside surrounded by the retaining wall 26. Inclination descending toward a pump pit 35 is provided on the upper surface of the tank body 20, and the pump pit 35 is provided with a pump 34 and a drain pipe 33 for draining water to an outside. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an underground tank structure in which a lower part for storing liquefied gas is buried in the ground.

  Conventionally, as a storage tank for liquefied gas such as LPG, LNG, etc., it consists of a bottom part, a side wall constructed along the periphery of the bottom part, and a roof part covering the upper part of the side wall, at least the lower part being buried in the ground. A tank constructed in such a way is used. Since such a storage tank is intimidating when the upper portion of the tank is exposed to the ground surface, a method of embedding and covering soil so that the upper portion of the tank is buried is widely used.

However, in such a method of covering the upper part of the tank, the weight of the earth and sand used for the covering soil is large, and the roof portion must be firmly constructed so that the load can be supported. Therefore, for example, Patent Document 1 describes a method in which a lightweight coating material such as foamed polystyrene or foamed urethane foam is disposed immediately above the tank in order to reduce the load acting on the roof of the tank. In this method, the outer edge of the tank is surrounded by a retaining wall for the purpose of preventing the lightweight coating material from floating due to the intrusion of rainwater from the surrounding embankment.
JP-A-4-236899

  However, the method described in Patent Document 1 has a problem that if rainwater accumulates in the retaining wall, the lightweight coating material provided in the retaining wall is lifted.

  The present invention has been made in view of the above problems, and an object of the present invention is to prevent the lightweight coating material from floating when the upper portion of the storage tank is coated with the lightweight coating material.

  The underground tank structure of the present invention is an underground tank structure constructed in a state where at least the lower part is buried underground, and a reinforced concrete tank main body formed in a container shape, along the outer periphery of the upper surface of the tank main body A retaining wall erected in a cylindrical shape, and a coating layer filled with a coating material on the inner side of the retaining wall, and the upper surface of the tank body descends toward a predetermined position on the upper surface. A gradient is provided, and a drainage mechanism for discharging water to the outside is provided at the predetermined position.

  In the above underground tank structure, a pump pit is formed at the predetermined position, and the drainage mechanism is connected to the pump disposed in the pump pit and the pump, and extends to the outside of the retaining wall. It may consist of a drain pipe.

  Further, a water collecting groove is formed on the upper surface of the tank body along the retaining wall, the pump pit is formed in the middle of the water collecting groove, and the water collecting groove is directed toward the pump pit. A downward gradient may be formed. Moreover, the water shielding sheet may be laid so that the upper part of the said coating layer may be covered.

  According to the present invention, even if rainwater penetrates into the cover layer, the rainwater that has reached the upper surface of the tank body flows along the gradient formed on the upper surface of the tank body and is discharged to the outside by the pump. . For this reason, it is possible to prevent the soil covering layer from being lifted.

Hereinafter, an embodiment of the storage tank structure of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a vertical sectional view showing a storage tank structure 10 of the present embodiment. As shown in the figure, the storage tank structure 10 of the present embodiment is for storing a liquefied gas such as LPG or LNG, and has an underground continuous wall 11 formed into a cylindrical shape in the ground, The underground tank body 20 constructed so as to be integrated with the underground continuous wall 11 inside the underground continuous wall 11, the retaining wall 26 constructed at the upper part of the side wall 21 of the underground tank body 20, and the underground tank body 20 The cover layer 50 is formed by covering the upper portion of the roof portion 25 with a lightweight covering material 51 and the drainage mechanism 30 for discharging rainwater and the like accumulated on the upper portion of the underground tank body 20.

  The underground tank body 20 is constructed integrally with the bottom plate 24 made of concrete on the bottom of the ground via a drained crushed stone layer 22 and a bottom heater 23, and integrally with the underground continuous wall 11 around the bottom plate 24. The side wall 21 and a concrete roof portion 25 constructed in a dome shape integrally with the top of the side wall 21. The top part of the roof part 25 is constructed so as to be located above the ground surface height (indicated by a broken line in the figure) before being raised by the embankment 12.

  A cold insulating material such as a membrane is attached to the inner peripheral surface of the underground tank main body 20 so as to maintain the heat insulating property of the underground tank main body 20. In addition, a side heater 40 is embedded in the outer peripheral portion of the underground continuous wall 11 to prevent freezing of the surrounding ground together with the bottom heater 23 embedded under the bottom plate 24.

  The underground continuous wall 11 is constructed from the surface height before raising in the vertical direction to the vicinity of the bottom plate 24 of the underground tank body 20. This underground continuous wall 11 is used as a retaining wall when the underground tank body 20 is constructed.

  The retaining wall 26 is formed of a cylindrical reinforced concrete wall constructed along the outer periphery of the upper portion of the side wall 21 of the underground tank body 20. The retaining wall 26 is constructed such that the lower end is integrated with the upper part of the side wall 21 and the upper end protrudes from the upper surface of the cover soil layer 50 provided on the upper part of the underground tank body 20. Partitioning the space above the top. The embankment 12 is applied to the outside of the retaining wall 26 to a height near the top of the retaining wall 26.

  Inside the retaining wall 26, for example, a covering layer 50 is formed by laminating a lightweight covering material 51 such as polystyrene foam formed in a rectangular parallelepiped shape. The upper surface of the covering layer 50 has a height near the top of the retaining wall 26, and the height of the upper surface is substantially the same inside and outside the retaining wall 26.

  2A is an enlarged sectional view showing the drainage mechanism 30, and FIG. 2B is a sectional view taken along line BB in FIG. Further, a water collecting groove 36 is formed in an annular shape along the outer periphery of the upper portion of the side wall 21 of the underground tank body 20, and pump pits 35 are formed at substantially four intervals in plan view. The upper surface of the side wall 21 is provided with an inclination such that water flows toward the water collecting groove 36 (that is, descending toward the outer periphery as indicated by an arrow in the figure). Is provided with an inclination so that water flows toward the pump pit 35 (that is, as it is lowered toward the pump pit 35 as indicated by an arrow in the figure).

  The drainage mechanism 30 is inserted above the pump pit 35 formed in the upper part of the underground tank main body 20, and a protection tube 31 fixed by a fixture 32 along the retaining wall 26 and the inside of the protection tube 31. The drain pipe 33 is provided and a pump 34 connected to the tip of the drain pipe 33 and disposed in the pump pit 35. By providing the protective pipe 31, the drain pipe 33 and the pump 34 can be pulled up to the ground, so that the drain pipe 33 and the pump 34 can be easily maintained even when the tank is in operation.

  When rain falls on the upper part of the storage tank structure 10, the rainwater penetrates into the covering soil layer 50 through the light-weight covering material 51 filled in the retaining wall 26. Thus, the rainwater that has penetrated into the cover soil layer 50 flows along the upper surface of the underground tank body 20 to the water collecting groove 36. Further, the rainwater that has flowed into the water collecting groove 36 flows into the pump pit 35 due to the gradient. The rainwater flowing into the pump pit 35 in this way is discharged to the outside through the drain pipe 33 by the pump 34.

  As described above, according to the present embodiment, rainwater that has entered the cover soil layer 50 flows into the pump pit 35 via the water collecting groove 36, and the rainwater that has flowed into the pump pit 35 passes through the drain pipe 33 by the pump 34. It will be discharged to the outside. For this reason, it can prevent that the lightweight coating | covering material 51 which comprises the soil covering layer 50 raises.

  In the present embodiment, the water collecting grooves 36 are provided along the inside of the retaining wall 26 at the upper part of the side wall 21 of the underground tank body 20, and the pump pits 35 are provided in the water collecting grooves 36 at substantially four intervals. However, the present invention is not limited to this, and the water collecting groove 36 may be provided at two substantially equal intervals, and the position and location where the pump pit 35 is provided can be appropriately selected.

  In the present embodiment, the water collecting groove 36 is formed along the retaining wall 26 on the upper surface of the side wall 21 of the underground tank body 20, but the water collecting groove 36 is not necessarily formed, and the side wall 21 is not necessarily formed. It suffices if the upper surface of the plate is provided with an inclination so as to descend toward the pump pit 35.

  Further, a waterproof sheet may be laid on the top of the soil covering layer 50. By laying a waterproof sheet on top of the soil covering layer 50, it is possible to prevent rainwater from entering the soil covering layer 50. Further, even if the waterproof sheet has a hole due to aging, and rainwater penetrates into the soil covering layer 50 from this hole, the rainwater can be discharged to the outside by providing the drainage mechanism 30. .

In the present embodiment, the soil covering layer 50 is constituted by the lightweight covering material 51. However, the present invention is not limited to this, and the soil covering layer 50 may be covered with earth or sand.
In the present embodiment, the upper surface of the side wall 21 is inclined. However, the present invention is not limited to this, and the upper surface of the tank including the roof portion 25 may be inclined.

It is a vertical sectional view showing the storage tank structure of this embodiment. (A) is an expanded sectional view which shows a drainage mechanism, (B) is BB sectional drawing in (A).

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Underground tank structure 11 Underground continuous wall 12 Filling 20 Underground tank main body 21 Side wall 22 Drainage crushed stone layer 23 Bottom heater 24 Bottom plate 25 Roof part 26 Retaining wall 30 Drainage mechanism 31 Protective pipe 32 Fixing tool 33 Drain pipe 34 Pump 35 Pump pit 36 Water collecting groove 40 Heater 50 Soil covering layer 51 Lightweight covering material

Claims (4)

An underground tank structure constructed with at least the lower part buried underground,
A tank body of reinforced concrete formed in a container shape;
A retaining wall erected in a cylindrical shape along the outer periphery of the upper surface of the tank body;
A coating layer filled with a coating material inside the retaining wall;
The upper surface of the tank body is provided with a gradient so as to descend toward a predetermined position on the upper surface,
An underground tank structure characterized in that a drainage mechanism for discharging water to the outside is provided at the predetermined position. The underground tank structure according to claim 1,
A pump pit is formed at the predetermined position,
The drainage mechanism is composed of a pump disposed in the pump pit and a drainage pipe connected to the pump and extending to the outside of the retaining wall. The underground tank structure according to claim 2,
A water collecting groove is formed along the retaining wall on the upper surface of the tank body,
The pump pit is formed in the middle of the water collecting groove,
The underground water tank structure is characterized in that the water collecting groove is formed with a gradient downward toward the pump pit. The underground tank structure according to any one of claims 1 to 3,
An underground tank structure, wherein a water shielding sheet is laid so as to cover an upper portion of the covering layer.

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