JPH0481080B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an underground tank for storing liquefied gases such as LNG and LPG.

[Prior Art] In this type of underground tank, the bottom plate and the circumferential wall are hinge-jointed through a joint in order to prevent stress concentration from being applied to the joint between the bottom plate and the circumferential side wall. .

[Problem to be solved by the invention]

However, in such an underground tank where the joint between the bottom plate and the circumferential side wall has a non-rigid structure, relative displacement may occur between the bottom plate and the circumferential side wall due to external loads, liquid loads, temperature changes, etc.

An object of the present invention is to provide an underground tank that can minimize the adverse effects on the inner tank caused by such relative displacement.

[Means to solve the problem]

In the underground tank for storing liquefied gas of the present invention, a bottom plate portion is provided at the lower end of the inner periphery of the circumferential side wall buried underground, and the tank inner tank is provided in a space partitioned by the circumferential side wall and the bottom plate portion. In the underground tank, the bottom plate portion includes a thin bottom plate having a small rigidity enough to hold the tank inner tank, and a thick bottom plate having high rigidity disposed on the lower surface side of the thin bottom plate. The thick bottom plate is connected at its peripheral edge by a hinge structure having a joint at the lower end of the peripheral side wall, and an edge cutting material is interposed between the thick bottom plate and the thin bottom plate. , a notch of a predetermined size is formed in the thick bottom plate at the peripheral edge of the upper surface facing the lower surface of the thin bottom plate, and the cutout includes:
It is characterized by being provided with an elastically deformable joint material.

[Effect]

According to the underground tank for liquefied gas storage of the present invention, since the notch portion provided with the joint material is formed in the upper surface periphery of the thick-walled bottom plate, when the thick-walled bottom plate is displaced, the thick-walled At the periphery of the top of the bottom plate,
The joint material is elastically deformed, and the upper surface peripheral edge of the thick bottom plate is prevented from pushing up near the joint with the peripheral side wall of the thin bottom plate.

〔Example〕

Hereinafter, the present invention will be explained based on illustrated examples.

FIG. 1 shows a first example of the invention. The underground tank of this example has a bottom slab section at the lower end of the inner periphery of the circumferential side wall buried underground, and the tank inner tank (membrane, etc. It has a structure in which an inner tank) 7 is provided. The bottom plate part is a thin bottom plate 1 with low rigidity that can hold the inner tank 7.
and a thick bottom plate 3 disposed on the lower surface side of the thin bottom plate 1.

Further, a slight gap is formed between the upper surface side of the thick bottom plate 3 and the bottom surface of the thin bottom plate 1, and the edge cutting material 2 is interposed between this gap. That is, by interposing the edge cutting material 2, the thin bottom plate 1 and the thick bottom plate 3 are in a state where their edges are cut (not integrated).

Further, the peripheral edge of the thick sole plate 3 and the tank circumferential side wall 4 are joined by a joining member 5a such as a stud bolt, and a joint is formed at this joining location.

That is, when a load is applied to the thick sole plate 3 from above and below, the joining member 5a is slightly elastically deformed, and the thick sole plate 3 moves in the horizontal or vertical direction using the joining point by the joining member 5a as a fulcrum. It has a hinge structure that allows it to be slightly displaced.

In addition, a notch 3a of a predetermined size is formed in the thick bottom plate 3 at the periphery of the upper surface facing the bottom surface of the thin bottom plate 1, and the notch 3a has a cutout 3a for absorbing deformation of, for example, styrene foam, etc. A joint material 6 made of a material that can be easily deformed and elastically deformed is provided.

According to the underground tank having the above structure, when a downward load such as stored items is applied to the thin bottom plate 1, the thin bottom plate 1 is supported by the thick bottom plate 3 having high rigidity. As a result, the thin bottom plate 1 and the peripheral side wall 4
The bending moment at the joint with the steel is significantly reduced.

In addition, a joint material 6 is provided on the periphery of the upper surface of the thick bottom plate 3.
Since the notch 3a is formed, even if an upward load is applied to the thick bottom plate 3 due to underground water or the like and the thick bottom plate 3 floats upward, the upper surface periphery of the thick bottom plate 3 will remain intact. In this case, the joint material 6 is only elastically deformed, and it is possible to prevent the upper surface peripheral edge of the thick sole plate 3 from pushing up the vicinity of the joint with the peripheral side wall 4 of the thin sole plate 1. Thereby, it is possible to prevent an adverse effect on the inner tank 7 due to displacement of the thin bottom plate 1 near the joint portion with the circumferential side wall 4.

Next, regarding the second embodiment of this invention, FIGS.
This will be explained with reference to FIG.

This embodiment is an example in which the present invention is applied to a pumped underground tank, and FIGS. 2 and 3 show the overall configuration thereof, and FIG. 4 shows details of the main parts. Although the bottom slab of this underground tank is located below the groundwater level H, the groundwater below the bottom slab is pumped up so that almost no upward load, such as groundwater pressure, acts on the bottom surface of the bottom slab.

As shown in FIG. 4, the tank circumferential side wall 11 has an inner flange 11a that projects inwardly at its lower end. A thin bottom plate 13 having a low rigidity enough to hold the bottom plate 12 is provided substantially integrally with the peripheral side wall 11.

In the space between the thin bottom plate 13 and the inner flange 11a, a thick bottom plate 14 having a rigidity large enough to support loads such as the weight of stored items, gas pressure, and the adverse effects of earthquakes is arranged. .

As shown in FIG. 5, this thick bottom plate 14 is arranged at a predetermined interval below the thin bottom plate 13 above it, and the space between them is filled with edge cutting material 15. By interposing the edge cutting material 15, these thin bottom plates 13 are
The thick bottom plate 14 and the thick bottom plate 14 are in a state where their edges are cut off (not integrated). Thereby, the thick bottom plate 14 can be horizontally displaced, that is, can rotate around the center of the thin bottom plate 13 or move in the radial direction.

Further, as shown in FIG. 6, the thick sole plate 14 has its peripheral edge placed on the upper surface of the inner flange 11a via a pair of shoes 16, 16 disposed above and below. These pair of shoes 16, 16 have contact surfaces that come into contact with each other in a curved manner, and the thick sole plate 14 is connected to the shoes 16, 16.
It is supported using the contact point of 6 as a fulcrum.

In addition, as shown in FIG. 4, this thick sole plate 14 has a notch of a predetermined size along the entire circumference of the upper surface periphery, and the notch 14a has elastic deformation that easily absorbs deformation of styrofoam, etc. A joint filler 17 made of a suitable material is filled. Furthermore, a gap is provided between the outer periphery of the thick bottom plate 14 and the inner peripheral surface of the peripheral side wall 11, as shown in FIG. A cushion material 18 is interposed which acts as a cushion.

Further, bolts (not shown) for fixing the inner tank 12 are implanted in the thin bottom plate 13, but the upper surface of the thin bottom plate 13 is designed to prevent cracks from occurring from the bolt-embedded portions as shown in FIG. As shown in FIG. 9, an induced joint 19 is formed. The induction joints 19 consist of a plurality of groove-shaped joints formed in advance at a predetermined depth in the circumferential direction and radial direction on the upper surface of the thin bottom plate 13, and when bolts are inserted into the thin bottom plate 13, the This absorbs the stress acting in the external direction of the bolt and prevents cracks from forming at the bolt installation location.

In addition, 20 in FIGS. 2-4 is a roof, and 21 is a crushed stone layer.

In the underground tank configured as described above, the thick bottom plate 14 supports the thin bottom plate 13, which is subject to downward loads such as stored materials and frost heaving pressure, so that the connection between the thin bottom plate 13 and the peripheral side wall 11 is The bending moment at the location can be significantly reduced. Therefore, the peripheral side wall 11 and the thin bottom plate 1
There is no need to increase the wall thickness of the joint portion with 3, and costs can be reduced.

Here, the thick sole plate 14 generates a bending moment by supporting the thin sole plate 13 on which a load is applied. Since it is supported on the upper surface of the inner jaw portion 11a using the abutment point of the abutment surface as a fulcrum, the bending moment generated in the thick bottom plate 14 does not act on the circumferential side wall 11.

In addition, since the thin bottom plate 13 has low rigidity as a whole, the circumferential side wall 11 even when a load is applied.
It is difficult to cause local relative displacement between the two. Therefore, there is no risk of harmful displacement of the inner tank 12 held by the thin bottom plate 13.

Further, when a downward load is applied to the thick sole plate 14, the thick sole plate 14 bends in a downward convex manner using the contact points of the pair of shoes 16, 16 as fulcrums. As a result, the peripheral edge of the upper surface of the thick bottom plate 14 rises upward, but in the case of this underground tank, the peripheral edge of the upper surface of the thick bottom plate 14 is cut out by a predetermined dimension, and the cutout 14a is filled with joint material 17. Therefore, there is no possibility that the rising phenomenon would cause the thin bottom plate 13 to be pushed up from below and have a harmful effect on the inner tank 12.
In this case, it goes without saying that the dimensions of the notch 14a are set at the design and construction stage to such a value that the thin bottom plate 13 will not be pushed up due to the above-mentioned rising phenomenon.

〔Effect of the invention〕

As described above, according to the underground tank for liquefied gas storage of the present invention, the thick bottom plate has a notch provided with a joint material at the upper surface periphery of the thick bottom plate. When displaced, the joint material is elastically deformed at the periphery of the upper surface of the thick-walled bottom plate, thereby reliably preventing the upper periphery of the thick-walled bottom plate from pushing up near the joint with the peripheral side wall of the thin-walled bottom plate. can. Thereby, it is possible to prevent an adverse effect on the tank inner tank due to displacement of the vicinity of the joint between the thin bottom plate and the circumferential side wall, and it is possible to ensure long-term reliability.

[Brief explanation of drawings]

FIG. 1 is a side sectional view showing an embodiment of the present invention;
2 to 8 show a second embodiment of the present invention. FIG. 2 is an overall side sectional view, FIG. 3 is a plan view of the same, and FIG. Detailed side sectional views, Figures 5, 6, and 7 are detailed views of the circular part, circular part, and circular part of Figure 4, and
This figure is a plan view taken in the direction of the arrow in FIG. 4, and FIG. 9 is a sectional view showing details of the induced joint 19 in FIG. 8. 1, 13... Thin bottom plate, 2, 15... Edge cutting material,
3, 14... Thick bottom plate, 3a, 14a... Notch, 4, 11... Circumferential wall, 5... Joint, 6, 17
...Glut material, 7,12...Inner tank.

Claims (1)

[Claims] 1. A bottom plate is provided at the lower end of the inner periphery of the circumferential side wall buried underground, and an inner tank is provided in a space partitioned by the circumferential side wall and the bottom plate. In the underground tank, the bottom plate portion is composed of a thin bottom plate having a small rigidity enough to hold the tank inner tank, and a thick bottom plate having high rigidity disposed on the lower surface side of the thin bottom plate, The thick-walled bottom plate is joined at its peripheral edge by a hinge structure having a joint at the lower end of the peripheral side wall, an edge cutting material is interposed between the thick-walled bottom plate and the thin-walled bottom plate, and the thick-walled bottom plate is A liquefied gas storage device characterized in that the bottom plate has a notch of a predetermined size formed at the peripheral edge of the upper surface facing the lower surface of the thin bottom plate, and the notch is provided with an elastically deformable joint material. underground tank.