JPH04125399A - Underground type storage tank structure - Google Patents

Abstract

PURPOSE:To rigidly fix the title structure within a ground by installing a plurality of anchors each having the lower end fixed within a lower ground of a bottom plate, and rigidly connecting the upper end of each anchor within the bottom plate. CONSTITUTION:A plurality of anchors 6 are buried within a lower ground of a bottom plate 3 of an underground type storage tank structure to a specified depth in such a manner that the lower ends thereof are fixed within the ground E, and the upper ends thereof are connected with the bottom plate 3. Each anchor 6 is buried within the ground E prior to application of bottom plate. This eliminates the necessity of excessively increasing the thickness of the bottom plate as a means for stably supporting the whole structure within the ground and the whole weight of the structure, and also reduces the stress generated on the bottom plate because of the action of the anchors as a spring support. Accordingly it is possible to thin the thickness of the bottom plate, to shorten the term of works and reduce the construction cost, and to further improve the safety.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an underground storage tank structure for storing low-temperature liquefied gas such as LNG and LPG, crude oil, and the like.

(Prior art) Large storage tank structures for storing low-temperature liquefied gases such as LNG and LPG are designed to prevent thermal effects on the surroundings due to the latent heat of vaporization of the liquefied gas and internal effects due to external heat. It is sometimes built underground or semi-underground.

In addition, many of these underground storage tank structures are often constructed as storage bases on reclaimed land near the sea.

There are various methods for constructing this underground storage tank structure, examples of which include the methods described below.

First, a cylindrical underground wall deep enough to reach the supporting ground is constructed using the continuous underground wall construction method, the ground at the planned construction site is enclosed with a pond wall, and internal excavation is carried out.

Next, a side wall is constructed along the inner surface of the underground wall using a reverse winding method or a forward winding method.

When the planned depth is reached, a bottom slab is constructed on the bottom ground and connected to the side walls.

Finally, the upper opening is covered with a roof and the inside is lined with cold insulation material and steel plates to complete the underground storage tank structure.

(Problems to be Solved by the Invention) The above-mentioned underground storage tank structure is easily affected by groundwater because it is constructed in ground with a high groundwater level such as a landfill, and the bottom part is pumped up by groundwater. There are many methods that use pressure.

For this reason, in the past, countermeasures have been taken in which the thickness of the bottom slab and side walls are made larger than required for the strength, and the entire weight of the storage tank structure is used to counteract the groundwater pressure.

However, with such measures, in order to secure the internal volume of the storage tank, it is necessary to excavate an extra layer of ground to compensate for the increased thickness of the structure, which requires more man-hours and increases the construction period due to the increase in materials used. It was disadvantageous in terms of cost.

This invention solves the above problems by installing a plurality of anchors at the bottom of an underground storage tank structure.
The purpose of the present invention is to provide an underground storage tank structure that firmly fixes the structure in the ground and prevents it from floating up.

(Means for Solving the Problems) In order to achieve the above object, the present invention provides an underground storage tank structure having a bottom slab and side walls constructed in the ground, in which the lower end of the bottom slab is fixed in the lower ground. The present invention is characterized in that a plurality of anchors are installed, and the upper ends of each of these anchors are tightly tied to the bottom plate.

(Function) According to the above configuration, since the bottom slab is supported by a plurality of anchors, the structure is firmly fixed inside the ground against the buoyant force due to groundwater pressure according to the pull-out resistance of the anchors, and , the anchor acts as a base support and can reduce the stress generated by the bottom slab.

(Example) Hereinafter, an example of the present invention will be described in detail using the drawings.

FIG. 1 shows an underground storage tank structure according to the present invention.

In the figure, in the ground E, a cylindrical continuous underground wall 1 is provided that reaches from the ground surface to a poorly permeable layer E1, which is the supporting ground.

In the interior surrounded by the underground wall 1, a side wall 2 is constructed along the pond wall 1, and a bottom slab 3 is constructed at the deepest part. are connected to each other via a PC steel rod or the like.

The upper opening surrounded by the side walls 2 and the bottom plate 3 is sealed by a roof 4 to form an underground storage tank structure.

The inside of this structure is lined with a cold insulating material 5 whose surface material is a membrane, and the outside of the structure is provided with a heater for controlling frozen ground, piping equipment, and other accessories (not shown). ing.

The construction procedure for this structure is almost the same as the conventional one, but in addition to the above structure, the present invention has a plurality of anchors 6 whose lower ends are anchored in the ground E at a predetermined depth in the lower ground of the bottom plate 3.
is buried, and the upper end of each anchor 6 is connected to the bottom plate 3.

Each anchor 6 is buried in the ground E before the bottom slab 3 is constructed.

Figures 2 (a) to (C) show an example of the construction procedure, in which a casing 8 is inserted into the bottom of a hole that has been excavated to the planned depth to a predetermined depth in the lower ground, and a PC steel wire etc. A tensioning member 6a consisting of the above is inserted, and then grout G is injected into the inside of the casing 8.

After that, when the casing 8 is pulled up, the size of the grout G expands according to the injection pressure at the lower end and the withdrawal, and as the grout G hardens, the fixing part 6b is integrated with the lower outer periphery of the tension member 6a. As a result, the anchor 6 is left in the ground E.

Then, by constructing the bottom plate 3 and burying the upper end of the tension member 6a projecting above the bottom plate 3 in the bottom plate 3 or burying it under tension, a plurality of anchors 6 can be integrated in the lower part of the bottom plate 3.

In the above configuration, if the groundwater level WL of the ground E is close to the ground surface, water pressure corresponding to the difference between this water level WL and the depth D of the deepest part of the structure is applied to the structure, and as a result, Although a lifting force will be applied to the entire structure, the structure will be firmly fixed in an appropriate position by the resistance of each of the anchors 6 to be removed.

Note that, of course, the number of anchors 6 to be driven, the arrangement, and the depth of the anchoring portion 6b at the lowest end are set according to the design of the structure and the soil quality of the ground E.

(Effects of the Invention) As described above in detail through the embodiments, in the underground storage tank structure according to the present invention, the bottom plate is supported by a plurality of anchors, and the weight of the internal ground due to the effect of the plurality of anchors is Depending on the pull-out resistance of each anchor, the structure is firmly fixed inside the ground against the buoyancy caused by groundwater pressure.

Therefore, as a means of stably supporting the entire structure in the ground, there is no need to excessively increase the thickness of the bottom slab or the total weight of the structure, and the anchors act as spring supports to reduce the stress generated by the bottom slab. It is now possible to reduce the thickness of the bottom plate, reducing construction time.

This is advantageous in terms of construction costs and further improves safety.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing the overall configuration of an underground storage tank structure according to the present invention, and FIGS. 2(a) to 2(c) are explanatory diagrams showing the procedure for constructing an anchor. 1... Continuous underground wall 2... Side wall 3... Bottom plate 6... Anchor 6a... Tension member 6b... Anchoring part E... Ground

Claims (1)

[Claims] In an underground storage tank structure equipped with a bottom slab and side walls constructed in the ground, a plurality of anchors each having a lower end anchored in the lower ground of the bottom slab are installed, and the upper end of each of these anchors is tightly tied to the bottom slab. An underground storage tank structure characterized by: