JPS6055385B2 - liquid storage tank - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a large liquid storage tank for storing petroleum and other liquids.

This type of liquid storage tank, as schematically shown in a vertical cross-sectional view in FIG. 1, has a cylindrical side plate 2 standing on an annular plate 1, and a bottom plate 3 fixed on the inner edge of the annular plate. While forming a tank body A, a roof B is attached to the tank body A to store liquid inside.

Although the roof B may be a fixed roof as shown in the figure, it may be a floating roof that can move up and down in response to an increase or decrease in the amount of stored liquid. In the liquid storage tank,
The side plate 2 and the annual plate 1 are generally joined together by double-sided fillet welding.

However, in the case of the Miyagi Prefecture-Oki Earthquake, in many large liquid storage tanks of this type, the annual plate 1 broke near the joint with the side plate 2, and the liquid stored inside flowed out.

Therefore, as a reinforcement measure for this type of large liquid storage tank, as shown in a partially enlarged vertical sectional view in Fig. 2, an annular plate
An oil leak prevention plate 5 is formed by concavely curving the inner lower corner of the tank body A, which is formed by joining the side plate 2 on top by double-sided fillet welding 4 and further attaching the bottom plate (see Fig. 1). Alternatively, as shown in a partially enlarged vertical cross-sectional view in FIG. Measures such as reinforcing the joint between the annular plate 1 and the side plate 2 with residual dust 6 on the inside of A are being considered.

However, as a result of investigating the cause of the rupture in this type of large liquid storage tank, it was found that the overturning moment caused by the horizontal force caused by the earthquake force causes a floating phenomenon in the annular plate part of the tank body, which causes deformation and rupture. It was found that large residual bending deformation occurred near the joint between the side plate and the annual plate as a result of the mount sinking directly under the side plate. Furthermore, it was found that the deformation acts as cyclic deformation and induces fracture as extremely low-cycle fatigue. Since the breakage occurred due to the reasons mentioned above, it was found that the reinforcing measures shown in FIGS. 2 and 3 had little effect and were only gas-based.

Based on the above-mentioned viewpoints, this invention provides a liquid storage tank that is unlikely to break in the vicinity of the joint between the side plate and the annular plate in the event of a major earthquake. A large number of dowels are protruded over the required width of the upper surface of the member, and a ring-shaped reinforced concrete layer connected to these dowels connects the tank wall side member and the tank bottom side member. It is characterized by a ring-shaped metal plate whose edges are welded to the wall and bottom of the tank. DESCRIPTION OF THE PREFERRED EMBODIMENTS The liquid storage tank of the present invention will be explained by way of embodiments with reference to the drawings. FIG. 4 shows a main part of an embodiment of the liquid storage tank of the present invention in a longitudinal sectional view.

As shown in the drawings, an annular plate 1 which is a tank bottom side member and a side plate 2 which is a tank wall side member are joined to the saw body by double-sided fillet welding 4. The upper surface of the above-mentioned annual plate 1 and the side plate 2
A large number of dowels 7 are protruded from the inner surface of the lower part.

The dowel 7 is also provided on the bottom plate (see FIG. 1), which is not shown in FIG. 4, if necessary.

The vicinity of the joint between the annular plate 1 and the side plate 2 is connected by a reinforced concrete layer 8 which is connected to the dowel 7, and furthermore, an annular metal plate 9 is closely attached to the surface of this reinforced concrete layer 8.

The metal plate 9 consists of a horizontal part 9A that covers the upper surface 8a of the reinforced concrete layer 8, and a vertical part 9B that covers the inner circumferential surface 8b. The lower edges of each are welded to the upper surface of the annual plate 1. Next, the mechanism of resistance of the side plate 2 to the floating force will be explained with reference to FIG.

In FIG. 5, the symbol p is the hydraulic pressure of the stored liquid acting on the annular plate 1 and the side plate 2, and q is the floating force of the side plate due to the overturning moment.

FIGS. 6A, b, c, and d are diagrams showing moments, etc. showing balance in floating of the side plate 2 shown in FIG.
Figure a shows the radial width S of the floating annular plate 1 and side plate 2, Figure b shows the moment due to the hydraulic pressure p, Figure c shows the moment due to the floating force q, and , Figure d shows the total moment.

Note that in FIG. 6, the transmission of bending between the side plate 2 and the annular plate 1 is ignored for the sake of simplicity. Now, on the side plate 2,
Assuming that the uplift shown in Fig. 5 occurs, the uplift width S from the balance of moment and shear force is determined as an elastic problem.
It is expressed as If the annular plate 1 is reinforced so as to satisfy this formula 1, it can be kept within the elastic range, and the maximum moment m at this time can be obtained as follows.

Therefore, if we were to reinforce the conventional liquid storage tank shown in Figure 1, for example, with the same structure so as to keep Type 2 within the elastic range, the thickness of the annual plate 1 would have to be extremely thick. Although it is necessarily extremely uneconomical, the liquid storage tank of the present invention has the above-mentioned structure, that is, the annular plate 1 which is the bottom side member of the tank, and the bottom plate (reference numeral in FIG. 1) if necessary. A dovetail 7 is attached to the annular plate 1 and the side plate 2 from the required width portion (shown as 3) to the lower part of the side plate 2, which is the tank wall side member.
Since the reinforced concrete layer 8 is provided by connecting the annular plate 1 and the side plate 2, this reinforced concrete layer provides resistance and can reliably prevent breakage near the joint between the annular plate 1 and the side plate 2.

If the size of the liquid storage tank is a normal size, the reinforced concrete layer 8 only needs to have a radial width of several meters and a thickness of several tens of centimeters.

Furthermore, the metal plate 9 that is in close contact with the reinforced concrete layer 8 does not deform, and oil leakage is reliably prevented.

In addition, the side plate 2
Since the reinforced concrete layer 8 diffuses the compressive force from
There is no risk of large compressive force acting locally on the foundation.

As is clear from the above explanation, the liquid storage tank of the present invention is
Excellent effects such as reducing floating deformation and sinking phenomena near the joint between the side plate, which is the tank wall side member, and the annular plate, which is the tank bottom side member, preventing breakage and reliably preventing oil leakage. It is something that plays.

[Brief explanation of the drawing]

Figure 1 is a schematic vertical sectional view of a conventional liquid storage tank, Figures 2 and 3 are
The figure is an enlarged vertical cross-sectional view showing a part of each example of a conventional tank body reinforcement structure, FIG. 4 is a vertical cross-sectional view of a main part showing an embodiment of the liquid storage tank of the present invention, and FIG. FIGS. 6A, b, c, and d are longitudinal cross-sectional views showing the action of force at time, and are explanatory diagrams of moments, etc. In the drawings, A...tank body, 1... annual plate, 2
...Side plate, 4...Double-sided fillet weld, 7...Dovetail,
8... Reinforced concrete layer, 8a... Upper surface, 8b.
...Inner peripheral surface, 9...Metal plate, 9A...Horizontal part, 9B
...Vertical part.

Claims (1)

[Claims] 1. A large number of dowels are provided protruding from the lower inner surface of the tank wall side member to the required width of the upper surface of the tank bottom side member, and the tank wall side member and the tank bottom side member are connected by a ring-shaped reinforced concrete layer that is connected to these dowels. Furthermore, an annular metal plate whose edges are welded to the tank wall side and the tank bottom side is closely attached to the surface of the reinforced concrete to resist the floating force and to keep the sinking deformation within the elastic range. A liquid storage tank characterized by: