JPS6035493B2 - Tank foundation with auxiliary bottom plate - Google Patents

Description

[Detailed Description of the Invention] <Industrial Application Field> This invention provides a foundation for a tank such as an oil tank, in which an auxiliary bottom plate is interposed on a mound on improved and strengthened ground to prevent it from tilting. The invention relates to a tank foundation, in particular, a foundation in which a liquid-resistant auxiliary bottom plate having sufficient rigidity such as metal is interposed between the upper gravel layer of the tank foundation and the base layer such as the lower oil sand layer; This invention relates to a tank foundation having an auxiliary bottom plate that allows a peripheral plate to be erected on the auxiliary bottom plate to level the tank in a floating manner and correct the inclination of the tank.

<Prior art> Conventionally, flat-bottom cylindrical liquid storage tanks (hereinafter simply referred to as tanks), such as oil tanks, which are often constructed, are used for discharging the liquid stored in the tank, removing sludge from the liquid, and discharging waste residual liquid. It is desired to be installed at a desired height above the ground due to reasons such as tank construction, and to prevent rainwater from seeping in and capillary rise of underground water from the viewpoint of corrosion prevention of the tank body. As shown in Figure 1, antibodies 1, 1,...
A layer of sand and gravel is piled up on the ground 2 which has been improved and strengthened by the above methods, compacted to form a mound 3, and after the mound 3 is smoothed, a bottom plate is laid on top of it to construct the tank 4. was.

Therefore, after the tank 4 is constructed, a water filling test is generally performed, avoiding leakage tests, strength tests, and stability tests.

After the water level test, actual operation begins, but at the time of the water level test,
Alternatively, after the start of actual operation, the bottom plate may partially cave in as shown in Figure 2 due to unimproved ground 2, insufficient compaction of the gravel layer, etc., or in addition, the bottom plate may partially cave in as shown in Figure 3. To,
If the tank is tilted, as shown in FIGS. 2 and 3, cracks may occur in the bottom plate due to strain stress caused by the collapse and tilt, and the stored liquid may leak as shown by the arrow. Then, such leakage of the stored liquid causes a so-called liquid tightening phenomenon in the mound 3,
This causes the collapse of Mound 3 below the crack to become larger and larger, which further increases the strain stress and rapidly expands the bottom plate crack, causing the leakage of stored liquid to become a spill, which creates a vicious cycle that causes the liquid to collapse vertically and collapse. The expansion, crack progression, and increase in the amount of outflow eventually caused the third end of the mound to disappear as shown in Figure 4, and the outflow also became an ejection state similar to a dam failure, resulting in a major disaster. There are people who are addicted to it.

<Problem to be solved by the invention> To deal with this problem, it is necessary to appropriately detect the leakage of the stored liquid at the initial stage and transfer the stored liquid to another tank, or to open the drain pipe and drain it in a specified manner. It is best to lower the liquid level by pouring water, etc., and take emergency measures based on this, such as reducing the liquid pressure, reducing the leakage flow rate, and reducing the load on the foundation ground. As a result, the discovery of Shade outside Mound 3 is considerably delayed, and therefore early detection is generally difficult, and the above emergency deployment measures cannot be taken immediately, and in reality, unforeseen situations cannot be avoided. There were no problems/conditions.

For example, as shown in Japanese Patent Application Laid-Open No. 11811/1984, there is a method of inserting a vinyl sheet or the like into the foundation, but due to the flexibility of the vinyl sheet, it is necessary to place a layer of gravel or the like on top of it. There were also problems in which the slab did not work as a slab and was not prevented from sinking.

The purpose of this invention is to solve the problems of foundation collapse, cracks, and leakage caused by the behavior of the tank foundation as a technical problem,
It is easy to detect leakage even in the initial leakage after tank construction, and
It is an object of the present invention to provide a tank foundation with an excellent auxiliary bottom plate for tank applications in the energy industry, which is relatively easy to repair in response to spills.

<Means/effects for solving the problems> In order to solve the above-mentioned problems, the structure of the present invention, which is based on the scope of the above-mentioned patent claims, is to solve the above-mentioned problems by using a gravel layer on a gravel layer when constructing a foundation on improved reinforced ground. A liquid-impermeable auxiliary bottom plate with sufficient rigidity, such as tear-resistant, liquid-resistant, and heavy-duty steel, is laid on top of the oil sand layer, and on top of the auxiliary bottom plate, a tank bottom plate safety retention limit thickness is placed. By building up the gravel layer and making the mound into multiple layers, it provides slab-like rigidity, and even if the bottom plate cracks and leaks due to a cave-in, it will not leak below the auxiliary bottom plate and will be within the scour outflow limit. In addition, by using the tank foundation, a liquid-resistant peripheral plate can be erected on the outer periphery of the auxiliary bottom plate. A technical measure was taken to repair cracks by filling the tank with liquid and leveling the tank using liquid flotation, and by injecting filler into the lower part of the slope of the tank bottom to correct the leveling.

Embodiment 1 Configuration> Next, an embodiment of the present invention will be described as follows based on the drawings from FIG. 5 onwards.

Note that the same reference numerals are used to describe the same parts as in FIGS. 1 to 4. In the embodiment shown in FIG.
Starting from the bottom, a prescribed sand layer 3 is first applied as a base layer on the foundation ground lower layer 2 which has been reinforced and improved by reinforcement columns 1, 1, etc. as appropriate.
' is piled up and compacted, and an oil sand layer 5 is laid on the top surface, and on top of the compacted oil sand layer 5, a weather-resistant, liquid-resistant, permeation-resistant, military-resistant rigid plate, For example, a liquid-impermeable auxiliary bottom plate 6 of a predetermined thickness such as a steel plate is laid, and then a gravel layer 7 with a predetermined grain distribution is piled up and compacted on the auxiliary bottom plate 6 to smooth it to a set slope. After constructing a multi-layered mound structure, the main bottom plate 9 of the tank 4 is laid down, and the side plate 10 is erected on the outer periphery of the main bottom plate 9 to assemble the tank 4. Therefore, the mound serving as the tank foundation 8 consists of a sand layer 3' having a thickness corresponding to the capacity of the tank 4 from the bottom, an oil sand layer 5, an auxiliary bottom plate 6, and a small gravel layer 7. In other words, the auxiliary bottom plate 6 is used as the foundation. It has a multi-layered structure built inside. <Effect of the first embodiment> In the above-mentioned foundation configuration, even if the lower layer 2 of the foundation ground were to cave in and the main bottom plate 9 of the tank 4 caused local subsidence and strain stress was applied, the main bottom plate 9 and the auxiliary bottom plate 6 would The small gravel layer 7 between the layers has sufficient rigidity to act as a kind of thick synthetic slab with the interval as the plate thickness. This prevents sudden destruction of the bottom plate 9.

As shown in FIG. 6, even if a local fracture occurs and a crack occurs, causing the stored liquid to leak, the leaked liquid will be blocked by the auxiliary bottom plate 6 and the underlying oil sand layer 5. However, because of the large porosity and uniform distribution of the small gravel layer 7, it easily penetrates the small gravel layer 7 for a considerable length and ejects to the side, and leakage can be detected early. 4. Since the gravel layer 7 has a high porosity and liquid tightening action is difficult to occur, pseudo-washing outflow hardly occurs and the deformation of the bottom plate 9 does not progress. Almost never happens.

In the unlikely event that the main bottom plate 9 sinks all at once due to an earthquake or a local collapse of the ground, cracks occur, and as shown in FIG. , auxiliary bottom plate 8
are left in place, so that the slope of the tank 4 is prevented within the range of the outflow of the small gravel layer 7, so it is safe even if considerable stress is concentrated on the tank side plate 10 and main bottom plate 9 at the area where the scour spills out. There are things that can be kept within limits.

In addition to the worst-case scenario mentioned above, in general tanks, the sinking and tilting are extremely slow and take a considerable amount of time, and as mentioned above, if the sinking does not increase due to liquid tightening shrinkage at the bottom of the foundation. In this case, the cracks do not expand and progress, so it is possible to take sufficient countermeasures.

This countermeasure is for cases where the tank inclines, the increase in the amount of local depression, etc. exceeds legal regulations, and in that case, the mound of the above-mentioned self-foundation 8 is used to issue a revised gazette.

As shown in Figure 8, a cave-in occurred in the small gravel layer 7 of the foundation 8,
If a crack occurs in the bottom plate 9 and the tank 4 tilts,
If the concave deformation is severe even if it does not lead to cracks, drain out the stored liquid, cut and remove the cracked part of the bottom plate 9 at a predetermined location, fill the cut hole with small gravel 11, and fill the filling gap described later. The main bottom plate 9 is repaired by welding and fixing the bottom plate 9', leaving .

If the cut and excavation area is wide, place concrete blocks or the like on the supplementary gravel 11 to support the main bottom plates 9, 9 and 9' after melting. If it is a concave deformation, the above-mentioned repair is not necessary.

Next, as shown in FIG. 9, the shoulders of the small gravel 7' on the peripheral side of the auxiliary bottom plate 6 are removed, and a liquid-resistant rising peripheral plate 12 made of the same material is placed on the upper circumference of the auxiliary bottom plate 6. For example, by welding or other means, the peripheral plate 1 is connected in a ring shape around the entire circumference.
Small gravel 7' is placed on the second side, and additionally reinforced embankment is applied as appropriate.

Then, as shown in FIG. 10, when a liquid, for example, water is supplied to the dish-shaped storage tank formed by the peripheral plate 12 and the auxiliary bottom plate 6 using the liquid pump 14 and the pipe 15, the liquid is The liquid 16 penetrates and diffuses into the gravel layer 7 and is stored, and as a result, the stored liquid 16 exerts hydraulic pressure on the main bottom plate 9 of the tank 4, giving buoyancy as shown by the arrow in the liquid flotation system, and finally the tank 4 is floated flat and restored.

Further, depending on the design, jacks 17 may be provided at appropriate intervals on the outer circumference of the auxiliary bottom plate 6, and may be engaged with a bracket 18 provided on the tank side plate 101 to raise the tank side plate 101 together.

After the tank 4 is leveled as described above, as shown in FIG.
and small gravel to sufficiently fill the gap, and then, as shown in FIG. 12, leveling blocks 21 are installed at predetermined intervals below the side plate 10 to remove the liquid 16. The jack 17 and the like are removed, the peripheral plate 12 is also removed, and the area around the foundation 8 is prepared to complete the modification.

It goes without saying that the embodiment of the present invention is not limited to the above-mentioned embodiment. For example, a tank on a mound with or without the auxiliary bottom plate 6 interposed therein, that is, as shown in FIG. For tanks constructed using conventional methods, the tank 4 is specially raised using an appropriate means such as a multi-mounted crane, the mound 3 is opened, and the mound is constructed with rigid, impermeable material while partially replacing the embankment. It is also possible to completely lay down the liquid auxiliary bottom plate 6, resulting in the same foundation as in FIG. 5, and therefore it is also applicable to conventional tanks.

Further, a liquid-resistant rising peripheral plate 12 may be attached to the cylindrical portion of the auxiliary bottom plate 6 at the same time as the auxiliary bottom plate is installed.

Of course, the auxiliary bottom plate 6 can also be made of two layers. Various embodiments can be adopted in which an inert liquid can be used as the liquid used for floating the tank.

<Effects of the Invention> According to the present invention, as described above, a mound is built up from the bottom as a gravel layer, an oil sand layer, and a small gravel layer on the ground where the tank foundation has been improved and strengthened to form a plurality of layers. By interposing a rigid auxiliary bottom plate between them, basically, due to the rigidity of the auxiliary bottom plate, a raised layer such as a small gravel layer on the auxiliary bottom plate can have the same effect as a slab member. However, it has an excellent effect of preventing sudden concave changes due to depression of the main bottom plate of the tank, and therefore has the effect of reducing cracks and preventing so-called tank destruction from occurring easily.

In addition, even if a crack occurs due to the slope of the tank, the leakage liquid is dispersed through the raised layer such as a small gravel layer via the auxiliary bottom plate, and easily leaks out of the small gravel layer, making it possible to detect leakage due to the crack. Emergency measures will be taken immediately when small cracks occur. Therefore, even if the leakage starts, due to the built-up layer such as 4. gravel layer, liquid tightening phenomenon does not occur, and therefore the sinking is not promoted, and to that extent, it not only has the effect of preventing the crack from expanding. Since the auxiliary bottom plate is a liquid-impermeable plate, leakage does not proceed downward, and since the auxiliary bottom plate has rigidity, the advantages of a raised layer such as the Shangkanji small gravel layer are utilized, and the initial The leakage of liquid to the outside of the built-up layer is so small that no pseudo-washing outflow can be effected, and the rate of flow loss is small, which has the effect of preventing destruction of the peripheral edge of the mound.

The basis of this invention has the advantage that it can be applied not only to newly built tanks but also to conventional tanks.

Furthermore, when using a tank foundation with the above-mentioned advantages and correcting the tank inclination, a liquid-resistant upright peripheral plate is installed on the outer circumference of the auxiliary bottom plate, or by setting it upright in advance, the auxiliary bottom plate can be fixed. The tank can be easily returned to the horizontal position by collecting the liquid in the dish-shaped tank formed by the surrounding plate, and the gap between the tank bottom plate and the top of the raised layer such as the small gravel layer can be easily returned to the horizontal position. By injecting filler into the tank, it is possible to correct and fix the tank.

At the time of correction, the liquid supply 9E does not substantially impede construction efficiency due to the large porosity of the small gravel layer, and the liquid flotation type using the liquid is a tank with a flexible structure. The tilt correction of a tank with a large capacity of 150,000K had the advantage of ease of construction, accuracy, and stability of work in terms of average lifting and restoration.

[Brief explanation of the drawing]

Figure 1 is a schematic side view of the tank on a foundation on improved reinforced ground, Figure 2 is a schematic side view of localized collapse and leakage of the tank foundation, and Figure 3 is a schematic side view of the tank with a tilted tank due to collapse and leakage. , FIG. 4 is a schematic sectional view of the foundation scour and outflow, FIG. 5 shows an embodiment of the present invention, FIG. Figure 7 is a partial cross-sectional view schematically explaining the leakage caused by cracks in the tank. Figure 7 is a partial cross-sectional view schematically explaining the leakage caused by localized collapse of the tank in Figure 5. Figure 8 and the following are diagrams explaining the modification of the tank foundation. Figure 8 is a tilted tank. Fig. 9 is a partial sectional view of the liquid-resistant peripheral plate restored, Fig. 10 is a diagram explaining the repair of the recess.
The figure is a sectional view of liquid flotation, FIG. 11 is a sectional view illustrating filling material injection after leveling the tank, and FIG. 12 is a sectional view illustrating completion of correction. 3...Improvement and reinforcement, 7...Mound, 9
,6.... ... Bottom plate, 8... Tank foundation, 3'.
... Gravel layer, 7... Small gravel layer, 5...
...Oil sand layer, 6...Liquid-impermeable auxiliary bottom plate, 12
...... Peripheral plate, 10,9... Tank outer bottom, 16... Liquid, 20... Filling material. 1st
Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 9 Figure 8 Figure 10 Figure 11 Figure 1 Mountain 2 Figure

Claims (1)

[Claims] 1. In tank foundations where a mound is raised on improved and reinforced ground and a tank bottom plate is laid on top of the mound,
The mound has a plurality of raised layers including a sand layer, an oil sand layer, and a small gravel layer from the bottom, and a liquid-impermeable auxiliary bottom plate having sufficient rigidity such as metal is interposed between the raised layers. 1. A tank foundation having an auxiliary bottom plate, characterized in that the outer peripheral part of the liquid-impermeable auxiliary bottom plate is extended and folded up to form a ring shape on the outside of the tank side plate as a liquid-resistant rising peripheral plate.