JPH092572A - Structure of underground tank - Google Patents

Abstract

PURPOSE: To avoid entrance of groundwater into an underground tank by a simple structure. CONSTITUTION: This underground tank includes a tubelike continuous underground wall 2 constructed in the ground Y, an inner container constructed therein at a distance, and an intermediate layer 4 with an inner cushioning material applied between them. A water leading layer 5 for leading downward groundwater W entering inside along an inner face is provided on the inner face of the wall 2, and a drainage means 6 for collecting and draining the led groundwater W outside is connected to a lower part of the layer 5. Thus instead of shielding the groundwater in a sealed state, a flow path for drainage is secured, thereby preventing the groundwater from reaching the inner container 3.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the structure of an underground tank, and more particularly to a technique for preventing the infiltration of groundwater into an underground tank constructed below the groundwater level.

[0002]

Conventionally, for example, cryogenic liquefied gas such as LNG and LPG is stored in an underground tank built in the ground. This underground tank is generally a recess formed by constructing a cylindrical concrete underground continuous wall in the ground and then excavating the inside of the underground continuous wall as a mountain retaining wall to prevent the ground from collapsing. Built in.
Therefore, an underground tank constructed in this way
The liquefied gas stored inside can be effectively insulated from the outside by the ground, and since it is an underground structure, it has the advantage of excellent seismic performance.

By the way, depending on the underground tank, it may be necessary to construct it in a recess excavated deeper than the water level of the groundwater. In such a case, it is appropriate to avoid leakage of groundwater into the underground tank. It is necessary to take measures to stop water. Conventionally, a method of providing a continuous impermeable water blocking wall in the ground has been considered as such a water blocking measure. This stop wall is made of concrete, asphalt,
It is constructed using steel sheet pile or impermeable clay sheet.

[0004]

However, the water blocking wall composed of these members basically has a structure in which the ground water is blocked by the impermeability of the water blocking wall to block the ground water to a sealed state. It is necessary to maintain a perfect sealability over the entire wall surface because it is configured to store in a storage state, but for a large-scale structure such as an underground tank, such a complete sealability is required. It is difficult to realize the sealed state, and there is a problem that a large-scale construction work is required.

For example, in the case of constructing a water blocking wall using sheets, a plurality of sheets are inserted into a groove formed by excavation from the ground so that their ends overlap each other, and overlapping portions of each sheet and each sheet are overlapped. It is necessary to perform a water-stop treatment by placing a filler on each of the lower ends. However, when the water blocking wall must be deeply constructed, it is difficult to insert the sheet so that it does not curl, and it is difficult to reliably place the filler at the lower end of the sheet. .

[0006] Such inconvenience also applies to the water blocking wall made of other constituent members. In other words, as the size of the underground tank increases, the area to be subjected to water stopping treatment increases, so groundwater is completely sealed and stored outside the water blocking wall over this vast area. In order to maintain the state, it is necessary to take a large-scale water stop measure.

The present invention has been made in view of the above-mentioned circumstances, and an object thereof is to provide a structure of an underground tank capable of avoiding inundation of ground water with a simple structure.

[0008]

To achieve the above object, the present invention provides a cylindrical underground continuous wall constructed in the ground,
An inner container formed with a space inward of the inner container; and an intermediate layer formed by placing a filling material between the inner container and the underground continuous wall. An inner surface is provided with a water guiding layer that guides the groundwater penetrating through the underground continuous wall to the inside along the inner surface of the underground continuous wall, and collecting the guided groundwater at the bottom of the water guiding layer. We propose a structure of an underground tank to which a drainage means for discharging to the outside is connected.

[0009]

According to the structure of the underground tank according to the present invention, the earth pressure and the water pressure from the outside ground are received by the underground continuous wall which is the outermost shell of the underground tank. Then, when the groundwater penetrates the underground continuous wall and infiltrates into the underground continuous wall, the groundwater reaches the water guiding layer provided on the inner surface of the underground continuous wall, and along the water guiding layer, The inner surface of the middle continuous wall is guided downward. Since the drainage means is connected to the lower part of the water guide layer, the groundwater guided in the water guide layer is collected by the drainage means and then discharged to the outside. Therefore, the groundwater that has penetrated the underground continuous wall is guided downward by the water guiding layer before it is submerged in the intermediate layer, so that it is prevented from reaching the internal container inside the intermediate layer, and the infiltration of water into the internal container is prevented. To be prevented. Moreover, since the intermediate layer is formed by filling the filling material between the inner container and the underground continuous wall, the restraining effect of the ground is transmitted to the inner container,
The inner container will be reliably supported.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the structure of an underground tank according to the present invention will be described below with reference to FIGS. The underground tank of this embodiment is for storing liquefied gas, and is assumed to be constructed when the existing underground tank is rebuilt. As shown in FIG. 1, an underground tank 1 according to the present embodiment includes a cylindrical underground continuous wall 2, an inner container 3 arranged at an interval inward in a radial direction thereof, the inner container 3 and the inner container 3. And an intermediate layer 4 disposed between the underground continuous wall 1 and an inner surface 2a of the underground continuous wall 2, and a water guiding layer 5
The drainage means 6 is connected to the water guide layer 5.

The underground continuous wall 2 is a cylindrical wall constructed outside the frozen soil portion X formed around the existing underground tank 7, and is filled with a stabilizing solution such as bentonite muddy water. The ground Y is excavated in a groove shape while ensuring stability of the inner wall surface, a reinforcing bar cage or the like is built in the groove, and the concrete is poured into the groove while substituting the stabilizing liquid with the tremie pipe. The underground continuous wall 2 constructed in this way becomes a mountain retaining wall that receives earth pressure, water pressure, etc. of the ground Y that comes into contact therewith, and can prevent the ground Y from collapsing. Therefore, after the underground continuous wall 2 is constructed, the inside of the underground continuous wall 2 is excavated to remove the existing underground tank 7 and the frozen soil portion 2 around it, thereby forming a recess having the underground continuous wall 2 as an inner wall. Is able to.

As shown in FIG. 2, the water guiding layer 5 has, for example, a porous draining filter member 8 disposed on the entire inner surface 2a of the underground continuous wall 2 constructed as described above. And a flow passage 9 provided in the up-down direction along the inner surface 2a of the underground continuous wall 2 is formed. The drainage filter member 8 is arranged in an intermediate state between the intermediate layer 4 and the underground continuous wall 2 which will be described later, and allows the intermediate layer 4 to be in close contact with the underground continuous wall 2 and allows the vertical water to flow therethrough. The road 9 can be secured.

The inner container 3 is a side wall 3 which is constructed in a concentric shape with a space inwardly in the radial direction of the underground continuous wall 2.
It has a bottomed cylindrical shape including a and a bottom plate 3b constructed so as to close the bottom of the side wall 3a.

The intermediate layer 4 is cast between the continuous underground wall 2 thus constructed and the inner container 3 by filling a filling material such as a poorly mixed mortar.
Therefore, the intermediate layer 4 brings the water guiding layer 5 into close contact with the inner surface 2a of the underground continuous wall 2 by the pressure of the filling material, and the restraining effect of the ground Y through the underground continuous wall 2 is exerted on the side wall of the inner container 3. Three
It can be effectively transmitted to a.

The drainage means 6 is, for example, a water storage pit 10 provided below the inner container 3 and the water storage pit 10.
A pump 11 arranged inside, and a flow path 12 for guiding the groundwater W flowing downward through the water guiding layer 5 to the water storage pit 10.
And a water conduit 13 for pumping the groundwater W discharged by the pump 11 to the ground. The flow path 12 is formed, for example, from the lower part of the water transfer layer 5 to the intermediate layer 4
It is formed so as to penetrate through the lower part and the lower part of the side wall 3a of the inner container 3 to reach the gravel layer 14 provided on the lower part of the bottom plate 3b of the inner container 3, and the groundwater W guided to the lower part of the water guiding layer 5 It can be guided to the water storage pit 10 through the gravel layer 14.

With such a structure of the underground tank 1,
Most of the earth pressure and water pressure of the outer ground Y are resisted by the underground continuous wall 2 arranged in the outermost shell, and the side wall 3a of the inner container 3 is made of poorly mixed mortar having higher rigidity than the ground Y. The intermediate layer 4 is constrained by the intermediate layer 4 and
Is formed in close contact with the underground continuous wall 2, the restraining effect of the ground Y can be reliably transmitted to the side wall 3a of the inner container 3, and the specifications of the side wall 3a can be reduced.

Even when the groundwater W permeates the underground continuous wall 2, the groundwater W is moved down by the water guiding layer 5 along the inner surface 2a of the underground continuous wall 2, and the flow path 12 and the gravel. After being temporarily stored in the water storage pit 10 through the layer 14, the water is actively drained by the pump 11, so that it does not reach the inner container 3. Since the water guide layer 5 is provided on the inner surface 2a of the underground continuous wall 2 exposed by excavation, its construction is easy. Therefore, according to the structure of the underground tank 1 of the present embodiment, a relatively simple measure is taken without implementing a large-scale waterproofing measure that completely seals the entire sidewall of the underground tank 1 which is a large-scale underground structure. Thus, it is possible to reliably prevent water from entering the inner container 3 inside the underground continuous wall 2. Furthermore, since the intermediate layer 4 is formed of a filler such as a poorly mixed mortar, improvement in water impermeability and heat insulation can be expected also by the intermediate layer 4.

In this embodiment, the water guiding layer 5 is composed of the filter member 8 for draining water, but the intermediate layer 4 and the underground continuous wall 2 are secured while ensuring the flow passage 9 for the groundwater W. However, the structure is not limited to this as long as it can be closely contacted. For example, as shown in FIG.
The corrugated plate 15 may be provided on the inner surface 2a of the underground continuous wall 2. Further, the underground tank 1 is assumed to be for storing liquefied gas, but instead of this, it can be applied as an arbitrary underground tank structure. Also, the underground wall 2,
Although the side wall 3a of the inner container 3 has a cylindrical shape, instead of this, the side wall 3a may have a cylindrical shape of another arbitrary shape.

[0019]

As described in detail above, the structure of the underground tank according to the present invention comprises a cylindrical underground continuous wall constructed in the ground, and an internal container constructed with a space inside thereof. , And an intermediate layer formed by placing a filling material between them, and an inner layer of the underground continuous wall is provided with a water-conducting layer that guides underground water that infiltrates into the interior downward along the inner surface, and below that. Since the drainage means for collecting the guided groundwater and discharging it to the outside is connected, the following effects are obtained. When groundwater permeates through the underground wall, the groundwater is lowered by the water guiding layer along the inner surface of the underground wall, and is actively discharged by the drainage means. Can be prevented. Therefore, it is possible to reliably prevent water from entering the inner container by a simple method without taking a large-scale water-stopping measure such as complete sealing over the entire wall surface. Most of the earth pressure or water pressure of the outer ground is resisted by the underground continuous wall arranged in the outermost shell, and the inner container is securely restrained by the ground through the intermediate layer and the underground continuous wall. , The integrity of the inner container can be maintained for a long time. Further, it is possible to reduce the specifications of the inner container.

[Brief description of drawings]

FIG. 1 is a vertical sectional view showing an embodiment of the structure of an underground tank according to the present invention.

FIG. 2 is an enlarged cross-sectional view showing a structure of a sidewall of the underground tank of FIG.

FIG. 3 is a vertical sectional view showing another embodiment of the structure of the underground tank according to the present invention.

[Explanation of symbols]

 W Groundwater Y Ground 1 Underground tank 2 Underground continuous wall 2a Inner surface 3 Inner container 4 Intermediate layer 5 Water transfer layer 6 Drainage means

 ─────────────────────────────────────────────────── --- Continuation of the front page (72) Inventor Mitsuo Nemoto 1-5-20 Kaigan, Minato-ku, Tokyo Tokyo Gas Co., Ltd. (72) Inventor Miya ▲ Shinichi Shinichi 1-5-5 Kaigan, Minato-ku, Tokyo 20 Tokyo Gas Co., Ltd. (72) Inventor Yoji Nishikawa 1-3-2 Shibaura, Minato-ku, Tokyo Shimizu Construction Co., Ltd. (72) Inventor Sadaji Honjima 1-3-2 Shibaura, Minato-ku, Tokyo Shimizu Construction (72) Inventor Hideetsu Waga 1-3-2 Shibaura, Minato-ku, Tokyo Shimizu Construction Co., Ltd. (72) Inventor Yoshihiko Shimizu 1-3-2 Shibaura, Minato-ku, Tokyo Shimizu Construction Co., Ltd. ( 72) Inventor Takuro Odawara 1-3-2 Shibaura, Minato-ku, Tokyo Shimizu Corporation

Claims (1)

[Claims] 1. A cylindrical continuous underground wall constructed on the ground,
An inner container constructed with a space inward of the inner container; and an intermediate layer formed by placing a filling material between the inner container and the underground continuous wall, An inner surface is provided with a water guiding layer that guides the groundwater that permeates the underground continuous wall into the interior downwardly along the inner surface of the underground continuous wall, and collects the guided groundwater at the bottom of the water guiding layer. The structure of the underground tank, which is connected to the drainage means for discharging to the outside.