JP4904593B2 - Underground tank structure - Google Patents

Description

  The present invention relates to an underground tank structure, and more particularly to an underground tank structure suitable for an underground structure such as an LNG underground storage tank.

  Conventionally, as an underground tank structure, a continuous underground wall constructed continuously in the ground, a cylindrical side wall that defines an internal space, and a roof that is disposed in a manner that closes the upper end opening of the side wall And a bottom plate disposed at the lower end of the side wall is known.

  These continuous underground walls, side walls, and bottom slabs are made of reinforced concrete, and each is sufficient to prevent buoyancy of groundwater acting from the bottom to the top of the bottom slab, that is, floating due to lifting pressure. The sum of the weights of the continuous underground wall, side wall, roof and bottom plate is sufficiently larger than the lifting pressure.

  However, when the thickness of the continuous underground wall, the side wall, and the bottom plate is sufficiently increased in this way, and the total sum of the weights of the continuous underground wall, the side wall, the roof, and the bottom plate is sufficiently larger than the lifting pressure, the continuous underground wall, The formation of the side wall and the bottom plate requires more material than necessary, and it is necessary to secure a sufficiently large installation space, resulting in an increase in manufacturing cost.

  Therefore, a shelf board is attached to the outer peripheral portion of the upper end of the continuous underground wall, and a bank is placed on the shelf board, and the total weight of the continuous underground wall, side wall, roof, bottom slab, shelf board, and bank fill An underground tank structure has been proposed in which the thickness of the continuous underground wall, side wall, and bottom slab is reduced so as to be equal to or larger than the lifting pressure (for example, Patent Document 1). reference).

Japanese Patent No. 3886275

  However, in the underground tank structure as proposed in Patent Document 1 as described above, it is possible to reduce the thickness of the continuous underground wall, side wall, and bottom plate, but the weight of each of the shelf board and the embankment As a result, it has been difficult to reduce the manufacturing cost.

  In view of the above circumstances, an object of the present invention is to provide an underground tank structure capable of reducing the manufacturing cost.

In order to achieve the above object, an underground tank structure according to claim 1 of the present invention includes a continuous underground wall, and a cylindrical side wall formed such that an outer peripheral surface is in contact with an inner peripheral surface of the continuous underground wall. A roof disposed at the upper end of the side wall, a bottom slab disposed at the lower end of the side wall, an interior disposed within the side wall or the bottom slab, and an outer top of the continuous underground wall An underground tank comprising an overhanging portion integrally projecting on the side, and an embankment placed in a predetermined area above the underground tank, and defining an internal space with a side wall, a roof, and a bottom plate It is a tank structure, and the sum of the weight of the continuous underground wall, side wall, roof , bottom plate, interior, overhanging portion and embankment is defined as an underground tank weight, and the underground tank weight and the bottom plate on the continuous underground wall The sum of the peripheral frictional force acting on the inner peripheral surface on the lower side is the same as the lifting pressure acting on the bottom plate. , Or it larger than Ri Na, and the underground tank weight is characterized by being configured with smaller further aspect than the uplift.

Also, underground tank structure according to claim 2 of the present invention, Oite in claim 1 described above, skin friction of the continuous underground wall is attached to the continuous underground wall of the lower side of the bottom plate It is obtained from the shear strength of the mud film.

  According to the underground tank structure of the present invention, the sum of the weight of the continuous underground wall, the side wall, the roof and the bottom plate is defined as the underground tank weight, and this underground tank weight and the inner peripheral surface below the bottom plate in the continuous underground wall Since the sum of the frictional force acting on the peripheral surface is equal to or greater than the lifting pressure acting on the bottom plate, the gravity of the continuous underground wall, side wall, and bottom plate is made relatively small. As a result, it is possible to reduce the weight of the continuous underground wall, side wall, and bottom plate, and as a result, the thickness of the continuous underground wall, side wall, and bottom plate can be reduced. Therefore, the manufacturing cost can be reduced.

  Exemplary embodiments of an underground tank structure according to the present invention will be described below with reference to the accompanying drawings. In the following, an LNG storage underground tank structure will be described as an example.

  FIG. 1 shows an underground tank structure according to an embodiment of the present invention. The underground tank illustrated here includes a continuous underground wall 2, a side wall 3, a roof 4, and a bottom plate 5. Further, an interior 10 made of a membrane, a cold insulating material, or the like for maintaining the liquid-tightness of the stored liquid is provided inside the side wall 3 and the bottom plate 5.

  The continuous underground wall 2 is a cylindrical thing continuously constructed in the ground, and will be described in detail later. An outer guide wall (overhanging portion) 6 is joined and integrated with the outer peripheral portion of the upper portion of the continuous underground wall 2, and the outer guide wall 6, the continuous underground wall 2, the side wall 3, and the roof 4 are integrated. An embankment 9 is placed on the upper part (the area of the embankment 9 is placed directly on each structure of the outer guide wall 6, the continuous underground wall 2, the side wall 3, and the roof 4, as shown in FIG. However, depending on the soil quality of the embankment, it is directed upward from the outermost peripheral edge of the structure as the embankment portion of the structure located in the outermost periphery (in this embodiment, the outer guide wall 6). As a result, the inner part of the sloped line (the alternate long and short dash line shown in FIG. 1) that gradually slopes outward can be seen as the embankment part. The outer guide wall 6 is constructed above the groundwater level, and is connected to the upper part of the continuous underground wall 2 by a dowel 7. The gibber 7 is formed of, for example, a stud bolt, an anchor bolt or the like, and is disposed across the continuous underground wall 2 and the outer guide wall 6, and a plurality thereof are arranged in parallel along the vertical direction and the circumferential direction. . With the dowel 7, the weight of the outer guide wall 6 can be transmitted to the continuous underground wall 2 through the dowel 7.

  The side wall 3 has a cylindrical shape, and is provided in such a manner that the outer peripheral surface is in contact with the inner peripheral surface of the continuous underground wall 2. This side wall 3 is for defining an internal space in the ground. Moreover, the side wall 3 is united and integrated with the continuous underground wall 2 by a not-shown gibber 7 or the like. The roof 4 is disposed at the upper end of the side wall 3 in a manner that closes the upper end opening of the side wall 3.

  The bottom plate 5 is disposed at the lower end of the side wall 3 and defines the internal space as a bottom. That is, the bottom plate 5 is constructed in the ground together with the side wall 3.

  The continuous underground wall 2, the side wall 3, the bottom plate 5 and the outer guide wall 6 are each formed from reinforced concrete as will be described later. In the internal space defined by the side wall 3, the roof 4 and the bottom plate 5, for example, Filled with liquid such as liquefied natural gas.

  A method for constructing the above underground tank will be described. First, the outer guide wall 6 and the inner guide wall (not shown) are temporarily installed in such a manner that an annular groove portion is formed between them. The space between the outer guide wall 6 and the inner guide wall is excavated, that is, an annular groove portion is excavated and a continuous underground wall reinforcing bar is inserted. After that, concrete is laid. At this time, in a state where the upper outer side of the continuous underground wall 2 and the outer guide wall 6 are integrally coupled by attaching the dowel 7 in a manner protruding inward to the inner surface of the outer guide wall 6, The continuous underground wall 2 will be completed. After the continuous underground wall 2 is completed, the inner guide wall is removed.

  Next, by excavating the ground inside the continuous underground wall 2 to the flooring position (internal excavation), assembling bottom bar reinforcement at the bottom of the excavated ground, and placing concrete at the bottom of the underground The bottom plate 5 is completed. Inside the continuous underground wall 2, the side wall 3 is completed by assembling the side bars and placing concrete. In order to integrate with the continuous underground wall 2 when the side wall 3 is constructed, a part of the concrete on the continuous underground wall surface is shaved to expose the reinforcing bar, and a gibber is attached to the reinforcing bar. Integrate. Then, an interior 10 made of a membrane, a cold insulating material, or the like for liquid-tight holding of a stored liquid such as liquefied natural gas is provided inside the side wall 3 and the bottom plate 5. Thereafter, the roof 4 is attached to the upper end portion of the side wall 3, and the embankment 9 is placed on the outer guide wall 6, the continuous underground wall 2, the side wall 3, and the roof 4, whereby the underground tank structure 1 is constructed. Is done. The interior may be incorporated in the roof 4.

  In the underground tank structure 1 according to the embodiment of the present invention, the continuous underground wall 2, the side wall 3, the outer guide wall 6, the roof 4, the embankment 9 placed on top of these, the bottom slab 5, The sum of the respective weights of the interior 10 is defined as the underground tank weight (b), and the underground tank weight (b) and the bottom plate 5 below the bottom plate 5 on the continuous underground wall 2 below the bottom plate 5. The sum (b + c) of the peripheral frictional force (c) generated as a force resisting the lifting pressure (a) due to the groundwater acting from the groundwater is equal to or greater than the lifting pressure, while the underground tank weight (b) is Each of the thicknesses and weights is adjusted in a manner that is smaller than the lifting pressure (a).

  That is, the inventors of the present invention have a peripheral frictional force (c) as a force resisting the lifting pressure (a) acting on the bottom plate 5 from below on the inner peripheral surface of the continuous underground wall 2 below the bottom plate 5. In consideration of the peripheral frictional force (c), the continuous underground wall 2, the side wall 3, the outer guide wall 6, the roof 4, the embankment 9, the bottom plate 5 and the interior 10 are designed. .

  Such peripheral frictional force is caused by the shear strength of mud water slime (hereinafter referred to as mud film 8) called mud cake that adheres to the inner peripheral surface of the continuous underground wall 2 when the continuous underground wall is constructed. It is proportional. The shear strength of the mud film 8 is determined from the mud film collected from the continuous underground wall at the time of construction of other structures, or from the continuous underground wall at the time of construction of the underground tank if a similar underground tank is constructed adjacently. It is obtained by conducting a one-sided shear test using the collected mud film. The value obtained by dividing the shear strength of the mud film obtained by this test by the safety factor (for example, 1.5) is used as the peripheral frictional force. In addition, as a method for obtaining the shear strength of the mud film, it can also be obtained by conducting a loading test on the continuous underground wall.

  As described above, in the underground tank structure 1 in the embodiment of the present invention, the continuous underground wall 2, the side wall 3, the outer guide wall 6, the roof 4, and the embankment 9 placed on the upper part thereof. The sum of the respective weights of the bottom plate 5 and the interior 10 is defined as the underground tank weight (b), and the sum (b + c) of the underground tank weight (b) and the peripheral frictional force (c) is the lift pressure ( Since it is configured in a manner equivalent to or larger than a), the gravity of the continuous underground wall 2, the side wall 3, and the bottom slab 5 can be relatively reduced, whereby the continuous underground wall 2 and the side wall can be reduced. 3 and the bottom plate 5 can be reduced in weight, so that the thickness of the continuous underground wall 2, the side wall 3, and the bottom plate 5 can be reduced. Therefore, the manufacturing cost can be reduced.

  The preferred embodiment of the present invention has been described above, but the present invention is not limited to this, and various modifications can be made. For example, in the above embodiment, in addition to the continuous underground wall 2, the side wall 3, the roof 4, and the bottom slab 5, the outer guide wall 6 is left, the embankment 9 is placed, the interior 10 is provided, and all of these are combined. However, the outer guide wall 6 may be removed without leaving it, the embankment 9 may not be provided, and the interior 10 can be used for storage only by the side wall 3. It is not necessary to provide it. These configurations may be appropriately selected depending on the conditions such as the installation location and stored items. Therefore, even if some or all of the outer guide wall 6, the embankment 9, and the interior 10 are not provided, the underground tank weight is satisfied and the effects of the present invention are exhibited. According to this, it is possible to relatively reduce the weight of the continuous underground wall 2, the side wall 3, and the bottom plate 5, and it is possible to reduce the manufacturing cost by reducing these thicknesses and the like. Become.

  In particular, the thickness (b) of the underground tank is smaller than the lifting pressure (a), and the thickness and weight of each are adjusted. According to this, it becomes possible to make thickness of the continuous underground wall 2, the side wall 3, and the bottom plate 5 smaller, and can aim at reduction of manufacturing cost more.

It is sectional drawing which shows typically the structure of the underground tank structure in embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Underground tank structure 2 Continuous underground wall 3 Side wall 4 Roof 5 Bottom plate 6 Outer guide wall 7 Giber 8 Mud film 9 Filling 10 Interior

Claims (2)

A continuous underground wall, a cylindrical side wall whose outer peripheral surface is formed in contact with the inner peripheral surface of the continuous underground wall, a roof disposed at the upper end of the side wall, and a lower end of the side wall. An underground tank composed of a bottom plate provided, an interior disposed inside the side wall and the bottom plate, and an overhanging portion integrally projecting outward from the upper part of the continuous underground wall,
A structure of an underground tank comprising an embankment placed in a predetermined area above the underground tank, and defining an internal space with a side wall, a roof, and a bottom plate,
The sum of the weight of the continuous underground wall, side wall, roof , bottom plate, interior, overhang and embankment is defined as the weight of the underground tank, and the weight of the underground tank and the inner periphery below the bottom plate of the continuous underground wall and wherein the sum of the circumferential surface frictional force acting surfaces, said bottom plate equal to the uplift acting on, or greater than Ri Na, and the underground tank weight is constituted by less other modes than the uplift Underground tank structure. The underground tank according to claim 1 , wherein the peripheral frictional force of the continuous underground wall is obtained from the shear strength of a mud film adhering to the continuous underground wall below the bottom plate. Construction.

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