JPH08120969A - Underground tank - Google Patents

Abstract

PURPOSE: To provide an underground tank that is excellent in water stoppability. CONSTITUTION: This tank is composed of a reinforced concrete construction skeletal body 11 consisting of a side wall 3 and a bottom block, an adiabator 6 installed in an inner part of the skeletal body, a water stop plate 16 installed in space between the skeletal body 11 and this water stop plate 16 as covering an outer surface of the adiabator 6, and a drainage layer 17 installed in space between the skeletal body 11 and the water stop plate 16. In this constitution, this drainage layer 17 is interconnected to a pumping pit 8 via a drainpipe 18.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an underground tank which is built underground and stores liquefied gas such as liquefied natural gas and liquefied petroleum gas.

[0002]

2. Description of the Related Art As a tank for storing liquefied gas such as liquefied natural gas or liquefied petroleum gas, an underground tank having a structure shown in FIGS. 2 to 4 has been put into practical use. This is one in which the ground 1 is excavated, a bottom plate 2 and side walls 3 made of reinforced concrete are provided, and the upper part thereof is covered with a dome roof 4 made of steel. The underground tank 5 having such a structure can secure the strength capable of resisting external force such as earth pressure, groundwater pressure, seismic force, internal hydraulic pressure, gas pressure, etc. by the strong bottom plate 2 and side wall 3 made of reinforced concrete. Not to mention
As shown in FIG. 4, a heat insulating material 6 and a membrane 7 made of a stainless steel thin plate are attached to the inside thereof, whereby excellent heat insulating properties, liquid tightness, and air tightness can be secured.

Further, in the above-mentioned conventional underground tank 5, a pumping pit 8 is provided outside the side wall 3 in order to lower the water level of the ground water in the ground 1 below the bottom slab 2, and is formed below the bottom slab 2. Groundwater is collected from the crushed stone layer 9 through the water collection pipe 10 to the pumping pits 8 and pumped up to be drained.

[0004]

In the underground tank having the above-mentioned structure, the reliability of strength against external force such as earth pressure, groundwater pressure, seismic force, internal liquid pressure, gas pressure, etc. is further improved, and For the purpose of surely preventing the infiltration of groundwater into the tank 5, as shown in FIGS. 5 and 6, it is conceivable to attach the iron plate 12 to the outer surface of the skeleton 11 composed of the reinforced concrete bottom plate 2 and the side wall 3. There is. However, even with such a structure, there has been a problem that sufficient water-stopping property is not always obtained.

That is, if a crack 14 extending from the iron plate 12 to the skeleton 11 as shown in FIG. 6 occurs, the groundwater in the ground 1 passes from the defective portion of the iron plate 12 through the defective portion of the skeleton 11 to the heat insulating material 6. It was considered that the performance of the heat insulating material 6 would be deteriorated because the heat infiltrating into the above portion. Therefore, in the underground tank 13, even if there is a case where the tank 13 receives a large external force such as an earthquake force or a sudden temperature change occurs in the tank 13 for some reason, it is possible to cope with these external factors. With such a structure, it has been desired to sufficiently enhance the reliability of the strength of both the iron plate 12 and the skeleton 11.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an underground tank having a structure capable of further improving water shutoff.

[0007]

In order to achieve the above-mentioned object, an underground tank of the present invention comprises a reinforced concrete structure body comprising a side wall and a bottom slab, a heat insulating material provided inside the body, and A water blocking plate provided between the body and the heat insulating material to cover the outer surface of the heat insulating material, a drainage layer provided between the body and the water blocking plate, and the drainage layer and the drain pipe. It is characterized in that it is composed of a pumping pit which is communicated via the.

[0008]

In the underground tank of the present invention, the drainage layer and the water stop plate are sequentially provided from the outside between the body of the tank and the heat insulating material, so that the drainage layer interposed between the body and the water stop plate is the body. The transfer of external force and thermal stress between the water and the water stop plate is relaxed. Also, since the drainage layer is connected to the pumping pit, the drainage layer functions as a drainage route for discharging the infiltrated groundwater to the outside of the tank again, and the water blocking plate prevents the groundwater from reaching the heat insulating material. To do. That is, even if a defect occurs in the structure, the groundwater that has penetrated into the structure of the structure through the defect is stopped by the water stop plate, and does not further enter the inside of the tank. Drained to the outside of the body.

[0009]

EXAMPLE An underground tank which is an example of the present invention will be described below with reference to FIG. Since the entire structure of the underground tank 15 is basically the same as that described above, the illustration of the entire underground tank 15 is omitted, and a sectional view of the body 11 is shown in FIG. The same parts as those in FIG.

The structure of the underground tank 15 of this embodiment is such that the outer surface of the heat insulating material 6 is covered with a water stop plate 16, and a drainage layer 17 is provided between the reinforced concrete frame 11 and the water stop plate 16. . That is, as shown in FIG. 1, in the underground tank 15, a drainage layer 17, a water stop plate 16, a heat insulating material 6, and a membrane 7 are sequentially provided inside a body 11 composed of a bottom plate 2 and side walls 3 made of reinforced concrete. It has a laminated structure.

The heat insulating material 6 is for holding cold heat of the liquefied gas stored therein, and is made of, for example, rigid polyurethane foam as a material. The membrane 7 is intended to maintain liquid-tightness and air-tightness, and is made of, for example, stainless steel sheet. The water stop plate 16 is for preventing the infiltrating groundwater from reaching the heat insulating material 6 and is formed of, for example, an iron plate so as to be kept watertight.

A drainage layer 1 is provided between the frame 11 and the water blocking plate 16.
7 are formed. The drainage layer 17 is formed by being filled with a water-permeable material such as sand, or by being charged with a filter material. On the other hand, outside the frame 11, a pumping pit 8 is provided for collecting groundwater and pumping it from there for drainage, and a drainage layer 17 is provided between the bottom plate 2 and the side wall 3 below the frame 11. A drainage pipe 18 is provided to connect the pumping pit 8 to each other.

The underground tank 15 having the above structure is different from the conventional underground tank in which the water-stopping iron plate and the body are in direct contact with each other, and a water-permeable material is provided between the body 11 and the water-stop plate 16. The drainage layer 17 consisting of is interposed. Therefore, even if a large external force such as seismic force is applied to the tank 15, when the external force is transmitted from the frame 11 to the water blocking plate 16, the drainage layer 17 interposed therebetween acts as a cushion. By satisfying the above condition, the external force is absorbed and dispersed, so that the water blocking plate 16 has a structure in which such a large external force is not concentratedly applied. Therefore, the water blocking plate 16 can be made less likely to be damaged, and even if the water blocking plate 16 is damaged, it is less likely to occur at the same position as the damaged part of the skeleton 11.

Even if the temperature of the tank 15 suddenly changes, the drainage layer 17 is provided between the skeleton 11 and the water stop plate 16, so that the skeleton 11 and the water stop plate 16 are provided.
And have a structure in which thermal deformation is not restricted to each other. That is, since the drainage layer 17 interposed between the skeleton 11 and the water stop plate 16 serves as a cushioning material in both mechanical and thermal aspects, the reliability of the strength of both the skeleton 11 and the water stop plate 16 is high. Can be improved more than ever before.

Even if a crack 14 is generated on the side of the skeleton 11 and groundwater enters through the crack 14, the groundwater pressure applied to the cracked portion of the skeleton 11 is dissipated by the drainage layer, and when it reaches the water stop plate 16, the water pressure is reduced. Is in a sufficiently lowered state. Therefore, the groundwater is surely stopped by the water stop plate 16 and flows through the drainage layer 17 without further entering the inside of the tank. Then, the groundwater is collected in the pumping pit 8 via the drain pipe 18, and the groundwater can be quickly discharged to the outside of the tank 15 by any means such as inserting an underwater pump into the pumping pit 8. That is, since it is possible to reliably prevent the groundwater from reaching the heat insulating material 6, the performance of the heat insulating material 6 is not deteriorated.

Further, even if a crack occurs in the water blocking plate 16, the water pressure applied to the cracked portion of the water blocking plate 16 is sufficiently lower than the water pressure applied to the skeleton 11.
It is difficult for groundwater to infiltrate from the water stop plate 16 to the heat insulating material 6 side.

In the present embodiment, the water stop plate 16 is made of an iron plate and the drainage layer 17 is made of a water permeable material such as sand or a filter material.
As long as each function of the drainage layer 17 can be performed, it can be appropriately changed.

[0018]

As described above in detail, in the underground tank of the present invention, a water blocking plate is provided between the reinforced concrete frame and the heat insulating material so as to cover the outer surface of the heat insulating material. A drainage layer is provided between the plate and this drainage layer, and this drainage layer is connected to the pumping pit. The drainage layer interposed between the frame and the water blocking plate absorbs and relaxes the transfer of external force and thermal stress. Therefore, the reliability of the strength of both the frame and the water blocking plate can be improved more than ever before. And, even if a defect occurs on the side of the structure and groundwater infiltrates through this defect, the groundwater is reliably stopped by the water stop plate, and is drained from the drainage layer to the outside of the structure through the pumping pit. Can be improved. Furthermore, groundwater is prevented from reaching the insulation, and the performance of the insulation is not degraded.

[Brief description of drawings]

FIG. 1 is an enlarged cross-sectional view of a main part of an underground tank that is an embodiment of the present invention.

FIG. 2 is a side sectional view showing an example of an underground tank.

FIG. 3 is a plan view of the same.

FIG. 4 is an enlarged cross-sectional view of the main part of the same.

FIG. 5 is a side sectional view showing an example of an underground tank equipped with a water blocking iron plate.

FIG. 6 is a diagram showing a state in which a crack has occurred in the underground tank.

[Explanation of symbols]

 2 Bottom plate 3 Side wall 6 Insulation material 8 Pumping pit 11 Body 15 Underground tank 16 Water stop plate 17 Drainage layer 18 Drain pipe

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yasunao Kono 1-3-2 Shibaura, Minato-ku, Tokyo Shimizu Construction Co., Ltd.

Claims (1)

[Claims] 1. A reinforced concrete structure body comprising a side wall and a bottom slab, a heat insulating material provided inside the body, and an outer surface of the heat insulating material provided between the body and the heat insulating material. An underground tank comprising a water stop plate, a drainage layer provided between the skeleton and the water stop plate, and a pumping pit communicating with the drainage layer via a drain pipe. .