JPS581679A - Underground tank and its building method - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] The present invention relates to a huge underground tank for storing petroleum etc. and a method of constructing the same, particularly when the underground water level is high and there is no reliable impermeable layer underground. This article relates to a huge underground tank that can be easily and inexpensively constructed and its construction method.

As is well known, Japan relies on imports from foreign countries for most of its energy resources, and in particular, imports almost 100 tons of oil. Therefore, the supply and demand situation is sensitively affected by the international situation and the national situation of oil-producing countries, and it cannot be said that there is no risk of causing major turmoil in the Japanese economy in some cases. It goes without saying that sufficient reserves of petroleum are necessary to prevent such effects.

Possible ways to store oil include using abandoned tankers or solid rock, but the most common method is to use tanks for storage. Of these types of storage using tanks, storage in above-ground tanks has problems in dealing with fire outbreaks and environmental pollution due to oil leaks, and is also difficult to effectively utilize land due to restrictions on safety distances such as the distance between tanks. Problems remain.

For this reason, underground tanks are increasingly being used as large-capacity oil storage facilities these days. However, considering the location conditions, these underground tanks often have to be installed on soft ground with a high groundwater level, such as in a coastal area. In such ground, even if a continuous underground wall is constructed around the tank construction site, there will be a large amount of spring water, and if there is no reliable impermeable layer at an appropriate depth, a large amount of spring water may occur. However, in order to prevent this, continuous underground walls had to be built very deeply, which required a huge amount of construction costs.

The present invention aims to overcome the above-mentioned problems when constructing a huge underground tank for storing petroleum, etc., and to provide a highly reliable and low-cost underground tank and its construction method.C The present invention Focusing on the fact that the problem with conventional tank construction is that it occurs because the groundwater in the excavated ground surface is removed, the tank is constructed above the groundwater surface without removing the groundwater, and the tank is constructed in a sequential manner. This objective is achieved by allowing the tank to sink against the buoyancy of the groundwater.

Embodiments of the present invention will be described below based on the drawings. 1 to 5 illustrate the method of constructing an underground tank according to the present invention according to the process order. That is, in FIG. 1, consider the case where an underground tank of a size as shown by the broken line 2 is constructed on soft ground 1 with a high groundwater level. The groundwater level is indicated by 3. In this case, first, a continuous underground wall 4 is constructed around the tank construction site. In this case, it is sufficient that the distance between the lowest end 5 of the continuous underground wall 4 and the tank bottom ground surface 6 is a minimum value that does not cause heaving when the tank bottom ground surface 6 is excavated by underwater excavation. It is.

Next, as shown in FIG.
Excavate the ground 8 inside. As the excavation progresses, underground water will gush out, but without eliminating this, the underground excavation will continue. Therefore, the water level 3A within the continuous underground wall 4 is maintained at approximately the same level as the groundwater level 3 outside. Since the water level 3A and the underground water level 3 are maintained at the same level in this way, there is no fear that the bottom of the excavation will cause boiling due to spring water even after the excavation progresses.

After the excavation reaches 6t of tank bottom ground level, level it on top; 9t of concrete is poured underwater. The leveled concrete 9 uses concrete that is easily permeable to water. Instead of leveling concrete 9, a method of leveling crushed stone may be used.

Next, Fig. 3 (Fig. 3 and subsequent figures are enlarged illustrations.

), the bottom plate 22 of the tank 21 is manufactured above the pool 10 in the continuous underground wall 4 completed by the above process.The bottom plate 22 of the tank 21 is made of steel plate and is subjected to external pressure as shown by the arrow 11. , it is desirable to have a shape that forms part of a downwardly concave spherical surface.

After manufacturing the bottom plate 22, a side plate 23 is attached to the upper outer periphery of the bottom plate 22.
Manufacture.

After the manufacturing of the side plates 23 is completed, the bottom plate 2 is assembled as shown in FIG.
A bottom wall 24 of concrete is cast on the upper part of the wall 2, and a side wall 25 made of reinforced concrete is cast inside the side plate 23. The side wall 25 has 25-1, 25-
2. Continue with... By connecting in this way, the dead weight of the tank 21 gradually increases, so that the tank 21 gradually sinks against the buoyancy of the groundwater.

When pouring the bottom wall 24 and side walls 2 and 5, the tank 2
In order to prevent damage caused by colliding with the continuous underground wall 4 when the underground wall 1 sinks, a side wall 25 is placed on the upper part of the continuous underground wall 4, as shown in FIG. 5, and a roof 26 is then constructed.
When the construction is completed, the tank's own weight exceeds the buoyancy of the groundwater and it lands on the leveled concrete 9 of the excavated bottom plate 22Ifi of the tank 21. Thereafter, the fender 12 is removed, 13 tons of gravel, mortar, etc. are filled between the continuous underground wall 4 and the side plate 23, and both are fixed to complete the construction.

The underground tank construction method exemplified above and the tank constructed by this method have the following excellent advantages: (1) The water level within the continuous underground wall is kept at the same level as the outside groundwater table. Since there is no water pressure applied from outside, there is no need to worry about the bottom of the excavation boiling.
Continuous underground wall construction depth: The depth of the excavated bottom surface should be 1 degree before heaving occurs. Therefore, construction costs for continuous underground walls are low, and excavation can be performed extremely efficiently.

(2) Underground tanks can be easily and inexpensively constructed even on soft ground with high groundwater levels.

(3) The bottom plate of the tank has a shape of a part of a spherical surface with a concave downward.The bottom plate can be thin because it is a tube.(4) The side plate of the tank is thin because it has a reinforced concrete side wall on the inside. That's fine.

(5) Safety during the construction process is high, and all of the excavation, assembly of steel parts, and internal reinforced concrete placement can be performed rapidly, reducing overall construction time and construction costs.

Based on the above, the present invention 4 makes the construction of huge underground tanks in high ground water levels and soft ground different, greatly contributes to disaster prevention and environmental conservation in oil storage facilities, and also greatly contributes to resolving the energy crisis in Japan. It is clear that it is 0

[Brief explanation of drawings]

Figures WJ1 to Figure 5 illustrate the method of constructing an underground tank according to the present invention in the order of its steps. l...O ground 3@...Fist underground water level 4...
Continuous underground wall 6...tank bottom ground surface 7...excavation machine 9...leveled concrete 10...police/pool 12..."proof tkT113 fist/fist O gravel, mortar, etc. 21 ... Tank 22 ... Bottom analysis 23 ...
Side plate 24...Bottom wall 25.25-1.25-2
・・・・・・・・・・Side wall 26・・・・Roof Patent applicant Nishimatsu Construction Co., Ltd. Agent Patent attorney Tsuka Moto Daisanbe

Claims (1)

[Claims] (1) An underground tank constructed according to the following steps (a) to (b). (a) Construct a continuous underground wall to a depth that does not cause heaving of the ground at the bottom of the tank. (b) Construct a continuous underground wall while keeping the groundwater level inside the continuous underground wall at the same height as the groundwater level outside. The enclosed interior is excavated by underwater excavation (Q) After the excavated bottom is leveled, crushed stone is laid down or underwater concrete is cast to make it easier for water to pass through (d) Made by the steps of (,) to (C) Fabricate a tank bottom plate made of metal with a part of a spherical surface concave downward above the pool in a continuous underground wall, and then fabricate the side plates (-) Concrete is placed on the top of the tank bottom plate □
(f) The side walls are successively poured and the tank roof is constructed, and the tank is allowed to sink against the buoyancy, allowing the tank bottom plate to reach the bottom of the excavation (f). g) Filling the cylindrical space formed by the continuous underground wall, the side plate, and K with one mortar of gravel and fixing both (2) Construction of an underground tank according to the steps (,) to (g) below. Method. (-) Construct a continuous underground wall to a depth that does not cause heaving of the ground at the bottom of the tank (1)) Build a continuous underground wall while keeping the groundwater level inside the continuous underground wall at the same height as the groundwater level outside. (0) After leveling the bottom of the excavation, lay crushed stone or cast underwater concrete that is easily permeable to water (d) Steps from (a) to ((+) A tank bottom plate in the shape of a part of a downwardly concave spherical surface was manufactured above the pool in a nine-continuous underground wall, and then side plates were manufactured (・) Concrete was poured on the top of the tank bottom plate. A side wall made of reinforced concrete is placed on the upper part of the periphery of the tank bottom plate (f) The side walls are successively poured and a tank roof is constructed, and the tank is made to sink by resisting the buoyant force to allow the tank bottom plate to reach the bottom of the excavation (port). A nine cylindrical space formed by the continuous underground wall and the side wall is filled with gravel or the like to fix both.