JPH0296062A - Construction of underground tank - Google Patents

Abstract

PURPOSE:To increase the effect of cut-off by piping a coolant circulation pipe to the inside of a continuous underground wall, taking advantage of the heat of coolant circulating the inside of the pipe to freeze the soil around the continuous underground wall and forming a frozen earth layer. CONSTITUTION:A coolant circulation pipe 2 is distributed to the inside of an excavated trench hole and, at the same time, required reinforcements are erected to place concrete, and a continuous underground wall 1 is constructed. The coolant is circulated in the coolant circulation pipe 2 to form a frozen earth layer 3 around the continuous underground wall 1. After that, the skeleton of a tank is constructed in the inside of the underground wall 1. According to the constitution, the infiltration of water can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method of constructing an underground LNG tank, etc., and particularly relates to a method of constructing an LNG underground tank in a place where there is a lot of spring water.

[Prior art] For large underground tanks such as LNG, a continuous underground wall 01 is first constructed as shown in Fig. 4.
The tank body is constructed without excavating the inside of the wall 01 and draining the spring water inside the wall 01 using a pump 02.

[Problem to be solved] As a result, the following problems arise.

a. In places near the coast, the groundwater level is high and the water pressure is high, so a lot of spring water flows through the lower end of the continuous underground wall 01, so it is necessary to increase the capacity and number of pumps in operation. Operating costs will increase.

b. The amount of spring water sometimes exceeds the drainage capacity, and in such cases, we deal with it by pouring chemicals or placing inner concrete, but the water does not stop completely, or it takes time to construct the stopper. .

The present invention has been proposed in view of these points, and an object of the present invention is to propose a method for constructing an underground tank while completely stopping spring water flowing into a continuous underground wall.

[Means for Solving the Problems] The present invention proposes the following construction method as a technical means for achieving the above object.

a. First, dig a circular slot to surround the tank to be constructed. The depth of this groove should be determined to reach the impermeable layer.

58 Next, a refrigerant circulation pipe is installed in the slot and necessary reinforcing bars are installed.

The density or position of the refrigerant circulation pipe may be set in consideration of heat conductivity, and heat transfer fins may be welded to the refrigerant circulation pipe, or the refrigerant circulation pipe may be brought into contact with a reinforcing bar and the reinforcing bar may be used as a heat transfer body.

Next, concrete is poured into the groove.

60 Next, a refrigerant is circulated within the refrigerant circulation pipe to form a frozen layer around the continuous underground wall.

00 Next, construct the tank frame inside the continuous underground wall.

[Example] Figures 1 to 3 show examples of the above-mentioned present invention, and reference numeral 1 indicates a continuous underground wall.

This continuous underground wall 1 is constructed by excavating a groove with an excavator or the like until reaching the impermeable layer, erecting reinforcing bars, and pouring concrete.

2 is a refrigerant circulation pipe which is installed in the groove before the concrete is placed in a meandering manner as shown in Fig. 2;
A refrigerant is supplied into the refrigerant circulation pipe 2 from a refrigerant supply device (not shown). When the refrigerant is supplied, this cold heat passes through the continuous underground wall 1 and freezes the surrounding soil, forming a frozen layer 3 as shown in FIG.

The frozen soil layer 3 should be concentrated at the lower end of the continuous underground wall 1 so as to have a water-stopping effect, especially between the lower end of the continuous underground wall 1 and the impermeable layer. For this reason, although the piping of the refrigerant circulation pipe 2 needs to be constructed densely in the lower part of the continuous underground wall 1, it is not necessarily necessary to pipe the entire continuous underground wall 1.

In the case of an underground LNG tank, the refrigerant is circulated through the refrigerant circulation pipe 2 during construction of the tank, or when construction of the tank is completed and LNG is stored in the tank, the circulation of the refrigerant is stopped. This is because the frozen ground is maintained by the cold heat of the LNG in the storage tank.

[Effects of the present invention] As described above, the present invention installs a refrigerant circulation pipe within a continuous underground wall, and utilizes the heat of the cold colander circulating within the refrigerant circulation pipe to cool the surrounding soil of the continuous underground wall. By freezing and forming a layer of frozen soil, and building a tank using this layer of frozen soil to enhance its water-stopping effect, we can expect the following effects.

a. The frozen soil layer is concentrated between the continuous underground wall and the impermeable layer, which is the weak point of stopping water, and completely prevents water from penetrating between these areas.

As a result, there is no need to use a lift pump to drain a large amount of spring water as in the past, and the drainage equipment can be reduced. In addition, there are no spring water accidents, which is an effective safety measure.

b. Constructing a continuous underground wall, immediately forming a frozen soil layer, and then excavating the inside of this continuous underground wall, which eliminates the hassle of draining spring water while excavating at the same time as in the past. It doesn't grow.

[Brief explanation of the drawing]

Figure 1 is an explanatory diagram of the state in which a frozen layer is formed on a continuous underground wall.
FIG. 2 is an explanatory diagram of an example of a refrigerant circulation pipe, FIG. 3 is a partial sectional view of a continuous underground wall, and FIG. 4 is an explanatory diagram of an example of conventional spring water drainage. 1...Continuous underground wall 2...Refrigerant circulation pipe 3...Frozen layer Fig. 4

Claims (1)

[Claims] A process of excavating a groove for constructing a continuous underground wall, a process of setting a refrigerant circulation pipe in the groove, a process of pouring concrete into the groove, and a process of placing a refrigerant in the refrigerant circulation pipe. Construction of an underground tank consists of the steps of: circulating the soil to freeze the soil around a continuous underground wall to form a frozen soil layer; and excavating the area surrounded by the continuous underground wall and constructing the tank frame here. Law.