JPS6318080B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a storage device for storing cryogenic liquids such as LNG and LPG underground.

In underground storage tanks for low-temperature liquids, the ground around the underground storage tank freezes due to the cooling that accompanies storage of low-temperature liquids, causing various problems. It is known that one way to prevent the ground from freezing is to install a heat fence around an underground storage tank to warm the surrounding ground. Tests have shown that it is not possible to completely prevent frost heaving, and even in sandy soil with little frost heaving, when water moves to a frozen surface, a phenomenon occurs in which only ice precipitates, and the freezing expansion displacement of the ground cannot be stopped. It turns out there isn't.

The present invention has been made in view of the above, and an object of the present invention is to provide a cryogenic liquid storage device that can suppress as much as possible the freeze-expansion displacement of the surrounding ground accompanying the storage of the cryogenic liquid. The present invention provides an impermeable wall that extends an impermeable membrane between partition members and injects backfill material into the front and back surfaces of the ground on which an underground storage tank for low-temperature liquid is installed, surrounding the underground storage tank and reaching the impermeable layer. This is a low temperature liquid storage device in which a heat fence is provided on the water-shielding wall. The present invention will be described in detail below with reference to the drawings.

Figures 1 to 3 show an embodiment of the present invention, and an underground storage tank 2 for storing a low-temperature liquid 1 is a well-known type, and the inner surface of a peripheral wall 3 and a bottom plate 4 formed of concrete are A heat insulating material 5 is applied, and a roof 6 is provided on the top. On the ground A on which the underground storage tank 2 is constructed, an impermeable wall 7, which will be described later, is provided to surround the underground storage tank 2 and reach the impermeable layer B.

The above-mentioned water-blocking wall 7 is constructed by digging a trench 8 in the ground A and installing a water-impermeable film 9 inside the trench using a partition member 10.
Enter 1 and 12. As the water-impermeable membrane 9, a sheet made of nylon, polyethylene, etc. is used, and as the backfilling materials 11, 12, sand,
Mud mortar, concrete, asphalt, etc. may be used alone or in combination or in combination.

Here, an example of a method of constructing the water-shielding wall 7 will be explained with reference to FIG. 4.

First, a trench 8 is excavated in the ground A using an appropriate excavator until it reaches the impermeable layer B as shown in Fig. The guide tubes 14, 14 are set vertically apart from each other at an appropriate interval. After completing the above work, pipe 15 (3rd
The partition member 10, which has side plates 16, 16 on the front and rear, and engaging parts 17, 17 on the left and right sides, which are integrally attached by welding or the like, is inserted into the slit 18 of the engaging part 17 (see Fig. 3). Insert the locking part 13 of the guide tube 14 into the groove 8 as shown in C and C'.
Furthermore, the water-impermeable membrane 9 with the locking plates 19 (FIG. 3) attached to the side edges is attached to the locking plates 19,1.
9 is inserted into the engaging portion 17 through the slit 18 and stretched between the partition members 10 and 10 like D and D'. When the water-impermeable film 9 is finished in this way in the groove 8, backfilling materials 11 and 1 are placed on the front and back sides of the water-impermeable film 9.
Enter 2. If it is necessary to increase the liquid density between the engaging part 17 of the partition member 10 and the locking plate 19 of the water-impermeable membrane 9 inserted therein, mortar or the like is grouted into that part.

After constructing the water-shielding wall 7 between the two guide tubes 14, 14 as described above, pull out one guide tube 14 from the groove 8 as shown in E and E' and insert it again into the next section. Dig a groove 8 as shown in ', and construct a water-shielding wall 7 in the same manner as above. When constructing the impermeable wall 7 for the second time and thereafter, one guide pipe 14 is placed in the groove 8 apart from the partition member 10 at the end as shown by the two-dot chain line in F and F'. Build a water wall.

By the way, the pipe 15 constituting the partition member 10 of the water-shielding wall 7 is used as a well-known heat fence H. A deep well 20 is provided between the water-shielding wall 7 and the underground storage tank 2 as required. This deep well 20 is well-known, and the water-blocking wall 7
Pump up the groundwater existing between the and underground storage tank 2,
Freeze expansion displacement is suppressed by reducing the water content in that area.

When installing Heat Fence H on the impermeable wall as in the present invention, the rate of freezing progress slows down to approximately
10 ^-7 to 10 ^-8 cm/sec, and the water absorption capacity on the frozen surface increases several times.
Assuming that it is 10Kg/cm ² , in order to enhance the water-shielding effect of the water-shielding wall 7, it is necessary to increase its permeability coefficient to about 10 ^-8 cm/sec, and furthermore, the water-shielding wall 7 has a high resistance to water even if displacement occurs. It is required to follow the surrounding ground without causing cracks. Therefore, as described above, the materials, thicknesses, etc. of the water-impermeable membrane 9 and the backfilling materials 11 and 12 are determined in consideration of the above-mentioned requirements and the like. g is frozen soil.

As explained above, in the cryogenic liquid storage device of the present invention, the impermeable wall 7 provided around the underground storage tank 2 up to the impermeable layer B prevents the movement of groundwater to the frozen surface, and the heat fence H Since the progress of freezing is stopped, the freeze expansion displacement is suppressed as much as possible, and various troubles caused by this are effectively prevented. In addition, the water-blocking wall 7 has good water-blocking properties because it uses the water-impermeable membrane 9, and by selecting the backfilling materials 11 and 12, it can follow displacement and prevent the occurrence of cracks. Therefore, even if the ground is partially or completely deformed due to freezing or other causes, groundwater movement can be prevented regardless of this. Furthermore, the partition member 10 of the water-shielding wall 7 is replaced by a heat fence H.
If used as a heat fence, there is no need to go to the trouble of installing a heat fence, which has the effect of being economical.

In particular, according to the present invention, by adopting a structure in which a water-impermeable membrane is stretched between partition members, when constructing a water-shielding wall, after excavating a groove in which this water-shielding wall is to be installed, Since it is possible to adopt a construction method in which the partition members are erected, an impermeable membrane is stretched between the partition members, and a backing material is then placed, the impermeable membrane can be stretched only until the backing material is placed. There is no need to separately prepare supporting members, etc. to support the construction, and construction work can be carried out efficiently.In addition, because of the presence of partition members, it is possible to excavate a trench that forms part of the water-shielding wall. It is possible to use a construction method that sequentially builds water-blocking walls, such as pouring backing material into a section and, once that is completed, excavating the next trench. This has the effect of making construction easier by eliminating the need to excavate continuous trenches all at once. In addition, since you only need to prepare an impermeable membrane that is large enough to be stretched between partition members, it is possible to prepare an impermeable membrane that is large enough to cover the entire impermeable wall, or to join it at the construction site. You can eliminate what you have to do. Furthermore, since the partition member also acts as an aggregate to reinforce the impermeable wall, the amount of aggregate can be reduced. When using a heat fence, the entire impermeable wall is easily heated by the heat fence, resulting in a more effective antifreeze effect.

[Brief explanation of the drawing]

The drawings show one embodiment of the present invention, and FIG. 1 is a cross-sectional view of a cryogenic liquid storage device according to the present invention, FIG. 2 is a plan view of the same, and FIG. 3 is an enlarged detailed view of the portion shown in FIG. 2. , FIGS. 4A and 4A' to 4F and 4F are explanatory diagrams showing an example of a method of constructing a water-blocking wall. DESCRIPTION OF SYMBOLS 1... Low temperature liquid, 2... Underground storage tank, 7... Impermeable wall, 9... Impermeable membrane, 10... Partition member, 1
1, 12... Backfill material, A... Ground, B... Impermeable layer, H... Heat fence.

Claims (1)

[Claims] 1. An impermeable wall that surrounds the underground storage tank and whose lower part reaches an impermeable layer of the ground is provided on the ground where an underground storage tank for storing low-temperature liquid is provided, and this impermeable wall constitutes a heat fence. A water-impermeable membrane is stretched between a plurality of cylindrical partition members, and a backing material is placed on the front and back surfaces of the water-impermeable membrane to embed the partition members and the water-impermeable membrane. A storage device for low-temperature liquids.