JP7651488B2 - Wall - Google Patents

Description

The present invention relates to walls of tanks and the like.

Prestressed concrete (PC) tanks are used as equipment for storing liquids such as LNG (liquefied natural gas) and LPG (liquefied petroleum gas) (see, for example, Patent Document 1).

Figure 6 shows an example of a PC tank 100. The PC tank 100 has a cylindrical liquid retaining dike 200 on a base slab 5 supported by piles 4 in the ground, with an inner tank 6 and an outer tank 3 made of steel plates or the like installed inside. The inner tank 6 is provided for storing liquid.

The liquid barrier 200 is a tubular concrete wall, usually cylindrical, that is installed to prevent liquid from leaking to the outside if the inner tank 6 is damaged. The liquid barrier 200 must be constructed to withstand the liquid pressure that would be exerted if the inner tank 6 were to be damaged, and for this reason prestress is introduced by tensioning the circumferential and vertical tension members.

Figure 7 is an example of a vertical cross section of the liquid barrier 200. The above-mentioned liquid pressure can be resisted by introducing prestress into the liquid barrier 2 through the circumferential tension members 11 of the liquid barrier 2, but the liquid barrier 2 is not normally subjected to liquid pressure from inside the tank. For this reason, a bending moment in the vertical plane is applied to the liquid barrier 2 due to the circumferential prestress. The vertical tension members 13 are provided primarily to reinforce against this bending moment.

JP 2011-219140 A

In Patent Document 1, taking into consideration that the bending moment is large at the top and bottom of the dike, vertical tension members are provided only at the top and bottom of the dike. However, at the top of the dike, a large number of vertical tension members are placed in addition to the circumferential tension members of the dike, which raises concerns that construction will become more complicated due to an increase in the number of tensions.

The present invention was made in consideration of the above problems, and aims to provide walls and other structures that are easy to construct.

The present invention, which aims to solve the above-mentioned problems, is a cylindrical wall made of concrete, in which prestress is introduced by circumferential and vertical tension members of the wall, the vertical tension members are arranged only at the bottom of the wall, and at the top of the wall, the circumferential tension members of the wall are arranged so as to be inclined with respect to the horizontal direction.

In this invention, at the top of a cylindrical wall such as a flood barrier, the circumferential tension member of the wall is inclined with respect to the horizontal, so that prestress in both the circumferential and vertical directions of the wall can be introduced with a single tension member. This makes it possible to introduce the necessary prestress into the wall with a small number of tension members, which makes construction easier by reducing the number of times tension is required.

It is desirable for the angled portion of the tendon at the top of the wall to have a curve.
This allows both ends of the tendon to be smoothly connected when both ends are arranged horizontally from the standpoint of ease of tensioning work, etc.

The tendons at the top of the wall are preferably arranged in a wavy pattern in the circumferential direction of the wall, and are preferably arranged in a sine curve pattern in the circumferential direction of the wall.
This allows prestress to be introduced over a long range in the circumferential direction of the wall. Also, by making the tendons sine-curve shaped, the curvature of the tendons does not become too large, making the installation of the tendons easier.

It is desirable that a notch or a projection for fixing the end of the tendon at the top of the wall is provided on the outer surface of the wall.
This allows tensioning work to be carried out from outside the wall, making construction easier.

It is desirable that a plurality of the tendons are provided on the inside and outside of the top of the wall body.
This makes it possible to introduce a large prestress by the tendons and to make the prestress introduced by the tendons uniform in the circumferential direction of the wall body.

This invention makes it possible to provide walls and other structures that are easy to construct.

A diagram showing PC tank 1. A diagram showing the liquid barrier 2. A diagram showing the arrangement of tendons 15. A diagram showing the arrangement of tendons 15. A diagram showing the arrangement of tendons 15. A diagram showing a PC tank 100. A diagram showing a liquid barrier 200.

The following describes in detail a preferred embodiment of the present invention with reference to the drawings.

(1. Liquid barrier 2)
FIG. 1 is a diagram showing a PC (prestressed concrete) tank 1 having a liquid retaining dike 2 according to an embodiment of the present invention.

The liquid barrier 2 is a tubular wall, and in this embodiment, it is cylindrical. The liquid barrier 2 is formed by arranging concrete precast blocks 10 (hereinafter sometimes referred to as "blocks") in the circumferential direction of the liquid barrier 2 and stacking them vertically. Between adjacent blocks 10 in the circumferential and vertical directions of the liquid barrier 2, joints 7 made of a filler material such as concrete are provided. The configuration of the PC tank 1 other than the liquid barrier 2 is the same as that described in Figure 6.

Figure 2(a) is a diagram showing a vertical cross section of the liquid barrier 2. Tendons 11, 13, and 15 are embedded in the liquid barrier 2. The tendons 11, 13, and 15 are passed through a sheath (not shown) in the block 10, for example. PC steel materials such as PC steel bars and PC steel wires can be used as the tendons 11, 13, and 15.

The tension member 11 is a tension member in the circumferential direction of the dike 2 and is provided in the part of the dike 2 excluding the top 21.

The tension member 13 is a vertical tension member and is installed only at the bottom of the dike 2.

The tension member 15 is a circumferential tension member of the liquid barrier 2 provided at the top 21 of the liquid barrier 2, and is arranged so as to be inclined with respect to the horizontal direction. The tension member 15 is provided over the entire circumferential length of the liquid barrier 2. Note that in addition to the top 21 of the liquid barrier 2, it is also possible to provide the tension member 15 at the middle part of the height of the liquid barrier 2.

Figure 3(a) shows the top 21 of the liquid barrier 2 expanded in the circumferential direction. The circumferential direction of the liquid barrier 2 corresponds to the left-right direction in Figure 3(a), and Figure 3(a) shows a portion (1/3 of the circumference) of the liquid barrier 2 in the circumferential direction.

In this embodiment, the tension members 15 are arranged in a wavy pattern around the circumferential direction of the dike 2, and when viewed in a specific direction (e.g., from left to right in Figure 3(a)), they have an inclined portion that slopes from top to bottom and an inclined portion that slopes from bottom to top.

In this embodiment, this inclined portion has a curve, and when both ends of the tensioning material 15 are arranged horizontally from the viewpoint of ease of tensioning work described below, the both ends can be smoothly connected.

The waveform of the tendon 15 is a sine curve, and the tendon 15 continues smoothly (without corners). Two tendons 15 are placed on top of each other inside and outside the dike 2, which allows the prestress introduced into the dike 2 to be increased.

Notches 16 are provided on the outer surface of the top 21 of the dike 2 to secure the ends of these tension members 15. The tension members 15 are secured in place by fasteners 17 placed in the notches 16 after their ends are tensioned. The notches 16 are provided at a position corresponding to the apex of a sine curve where the tension members 15 are oriented horizontally, making it possible to secure the ends of the tension members 15 by tensioning them horizontally, making tensioning work easier. Note that instead of the notches 16, protrusions protruding outward from the dike 2 may be provided to secure the ends of the tension members 15.

In this embodiment, as shown in FIG. 3(b), the components Px and Py of the prestress force (compressive force) P due to tensioning of the tensioning material 15 can simultaneously introduce circumferential prestress and vertical prestress into the liquid retaining wall 2. As a result, vertical tensioning material is no longer necessary, and the number of times tensioning is reduced, making the construction of the liquid retaining wall 2 easier.

The tendons 15 are placed inside a sheath (not shown) embedded in the block 10, and the block 10 is manufactured with a sheath embedded that is shaped to match the arrangement of the tendons 15.

In this embodiment, the division positions of the blocks 10 in the circumferential direction of the liquid barrier 2 are regularly determined according to the waveform of the tension member 15, so that the top 21 of the liquid barrier 2 can be formed by blocks 10 with a common sheath arrangement, and the manufacturing of the blocks 10 can be reduced. For example, in the example of Figure 3(a), the division positions of the blocks 10 are determined so that the length of one period of the waveform of the tension member 15 is divided into six, so that the sheath arrangement is common for the multiple blocks 10 illustrated by the symbol A.

As described above, in this embodiment, by inclining the circumferential tension members 15 of the dike 2 at the top 21 of the dike 2 with respect to the horizontal direction, prestress in the circumferential and vertical directions of the dike 2 can be introduced with a single tension member 15. As a result, the necessary prestress can be introduced into the dike 2 with a small number of tension members 15, which makes construction easier by reducing the number of times tension is required.

In addition, in this embodiment, the inclined portion of the tension member 15 has a curve, and when both ends of the tension member 15 are arranged horizontally from the standpoint of ease of tensioning work, etc., the both ends can be smoothly connected.

In addition, in this embodiment, the tension members 15 are arranged in a wave pattern, which allows prestress to be introduced over a long range in the circumferential direction of the dike 2. In particular, in this embodiment, the tension members 15 are arranged in a sine curve pattern, which prevents the curvature of the tension members 15 from becoming too large, making installation of the tension members 15 easier.

In this embodiment, two tension members 15 are provided, one on the inside and one on the outside, so that a large prestress can be introduced by the tension member 15. However, only one tension member 15 may be provided without being stacked on the inside and the outside.

The outer surface of the dike 2 is provided with notches 16 or protrusions for fixing the ends of the tension members 15, which allows tensioning work to be performed from outside the dike 2, making construction easier. The ends of the tension members 15 can also be fixed to the pilasters 22 (see Figure 1) of the dike 2.

However, the present invention is not limited to the above embodiment. For example, in this embodiment, the length of one tension member 15 is set to be equal to or longer than one period of the waveform of the tension member 15, but as shown in FIG. 4(a), multiple tension members 15 may be arranged in the circumferential direction of the dike 2 in a continuous wavy manner, and the length of one tension member 15 may be set to be less than one period of the waveform.

In this example, as shown in FIG. 4(b), the length of each tension member 15 is set to half the length of the waveform, and the ends of adjacent tension members 15 in the circumferential direction of the liquid barrier 2 are arranged to overlap each other.

In this embodiment, as shown in FIG. 3(a), two tension members 15 with the same corrugation, one inside and one outside, are arranged circumferentially offset by a length equivalent to half the period of the corrugation, but the number of tension members 15 overlapped on the inside and outside of the liquid barrier 2 is not limited to this, and may be three or more. The amount of offset of the tension members 15 is also not limited to the above.

For example, in the example of Figure 5 (a), three inner and outer tendons 15 of the same corrugation are arranged circumferentially around the liquid barrier 2, shifted by a length equal to 1/3 of the period of the corrugation. In this way, by appropriately aligning the tendons 15 within a range of less than half a period, the magnitude of the circumferential prestress and vertical prestress of the liquid barrier 2 can be made uniform around the circumferential direction of the liquid barrier 2, and vertical prestress can be introduced at any position around the circumferential direction of the liquid barrier 2.

In this embodiment, the waveform of the tension member 15 is a sine curve, but the waveform of the tension member 15 is not limited to this, and may be arranged in a triangular wave shape, for example. As shown in FIG. 5(b), multiple tension members 15 can be arranged at intervals around the circumferential direction of the liquid barrier 2, and multiple tension members 15 with the same inclination can be arranged around the circumferential direction of the liquid barrier 2. In the example of FIG. 5(b), one tension member 15 is arranged across multiple blocks 10, but one tension member 15 may be arranged diagonally within one block 10. Although the inclined portion of the tension member 15 is linear, it may be curved.

In this embodiment, the flood barrier 2 is constructed using precast blocks 10, but the present invention can also be applied when constructing the flood barrier 2 using cast-in-place concrete, and the concrete can be poured with a sheath in place for passing the tension member 15 through.

This embodiment is described by giving an example of the arrangement of the tension members 15 of the dike 2 of the PC tank 1, which makes it easy to construct the PC tank 1, but the present invention is not limited to this and can be applied to various types of cylindrical wall bodies.

The above describes preferred embodiments of the present invention with reference to the attached drawings, but the present invention is not limited to these examples. It is clear that a person skilled in the art can come up with various modified or revised examples within the scope of the technical ideas disclosed in this application, and it is understood that these also naturally fall within the technical scope of the present invention.

1, 100: PC tank 2, 200: Liquid barrier 10: Precast block 11, 13, 15: Tendon 16: Notch 17: Anchorage 21: Top

Claims (6)

A cylindrical wall made of concrete,
Prestressing is introduced by circumferential and longitudinal tendons in the wall;
the longitudinal tendons are disposed only at the bottom of the wall;
A wall body, characterized in that at the top of the wall body, a circumferential tension member of the wall body is arranged so as to be inclined with respect to the horizontal direction. The wall according to claim 1, characterized in that the inclined portion of the tension member at the top of the wall has a curve. The wall body according to claim 2, characterized in that the tension members at the top of the wall body are arranged in a wavy pattern in the circumferential direction of the wall body. The wall body according to claim 3, characterized in that the tension members at the top of the wall body are arranged in a sine curve shape in the circumferential direction of the wall body. A wall according to any one of claims 1 to 4, characterized in that a notch or a protrusion for fixing the end of the tension member at the top of the wall is provided on the outer surface of the wall. A wall according to any one of claims 1 to 5, characterized in that the tension members at the top of the wall are provided in multiple numbers on the inside and outside.

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