JP6971165B2 - Wall construction method and wall - Google Patents

Description

The present invention relates to a method for constructing a wall body having an opening and the wall body.

Ground tanks are sometimes used as equipment for storing low-temperature liquids such as LNG (liquefied natural gas) and LPG (liquefied petroleum gas).

FIG. 9 shows an example of an LNG tank 100 that stores LNG as a ground tank. The LNG tank 100 has a liquid barrier 2 fixed on a bottom slab 5 supported by a pile 4 in the ground 7 to form a tank skeleton, and an inner tank 3a and an outer tank 3b made of steel plates or the like are provided inside the tank skeleton. .. The roof portion of the outer tank 3b is made of steel or concrete, and the steel plate on the side portion is integrally formed with the liquid barrier 2. LNG is stored in the inner tank 3a, and a heat insulating material is arranged between the inner tank 3a and the outer tank 3b to keep it cool.

The liquid barrier 2 is a concrete tubular wall body provided to prevent liquid leakage from the LNG to the outside when the inner tank 3a is damaged, and is usually cylindrical. The liquid barrier 2 needs to have a structure that can withstand the hydraulic pressure of LNG, and is therefore rigidly coupled to the bottom slab 5, and is not shown in the tank circumferential direction (hereinafter, may be simply referred to as the circumferential direction) tension material or vertical direction. Prestress due to the tension of the tension material is introduced to generate a predetermined compressive stress in the concrete.

When constructing the LNG tank 100, the liquid barrier 2 is constructed with an opening for construction provided at the bottom. The opening is used for carrying in materials for building an inner tank (bottom heat insulating material, bottom steel plate, side steel plate, roof steel plate, etc.), carrying in construction materials and equipment, and entering and exiting workers. As a result, the construction of the inner tank 3a can be efficiently performed in parallel with the construction of the liquid barrier 2. This opening is closed when the construction of the inner tank 3a is almost completed.

As a conventional example of such a method for constructing the liquid barrier 2, for example, as shown in FIG. 10, the lower portion of the liquid barrier 2 is constructed while leaving the opening 20, and the circumferential PC under the opening 20 is constructed. Tension the steel material 17a and the left and right vertical PC steel materials 17c of the opening 20. The circumferential PC steel material 17a is a circumferential tension material of the liquid barrier 2, and the vertical PC steel material 17c is a vertical tension material provided in the lower part of the liquid barrier 2.

When the liquid barrier 2 is constructed up to the top and the construction of the inner tank 3a is almost completed, the opening 20 is closed to form the closed portion 21, and the remaining circumferential PC steel 17a and the opening 20 are closed as shown in FIG. The vertical PC steel material 17c and the vertical PC steel material 17b in the width range are strained. The vertical PC steel material 17b is a vertical tension material provided over the entire height of the liquid barrier 2.

In another conventional example, for example, as shown in FIG. 12A, the lower portion of the liquid barrier 2 is constructed while leaving the opening 20, and the left and right vertical PC steel materials 17c of the opening 20 are strained.

When the liquid barrier 2 is constructed up to the top, as shown in FIG. 12B, the vertical PC steel materials 17a above and below the opening 20 and the vertical PC steel materials 17b on the left and right sides of the opening 20 are tensioned.

After that, when the construction of the inner tank 3a is almost completed, the opening 20 is closed to form the closed portion 21 as shown in FIG. 11, and the width of the circumferential PC steel material 17a and the closed portion 21 in the height range of the closed portion 21. Tension the vertical PC steel 17c and the vertical PC 17b in the range.

In addition, in Patent Document 1, as a method of introducing prestress to the liquid barrier at an early stage with the opening left, it is located in the circumferential PC steel material located in the height range of the opening or in the width range of the opening. It is described that the vertical PC steel material to be fixed is fixed at the edge of the opening.

Japanese Unexamined Patent Publication No. 2016-69851

In the former procedure (FIG. 10 → 11) of the conventional example, there is no vertical PC steel material on the lower side of the opening 20, and the circumferential PC steel material 17a is also arranged only on the lower side of the opening 20. The liquid barrier 2 must be constructed up to the top, and the structural instability will continue for a long time until the opening 20 is closed and the PC steel material is tense. Further, since a large amount of tension work is performed on the PC steel material after the opening 20 is closed, the entire construction period is likely to be extended.

Of the conventional examples, the latter procedure (FIG. 12 → 11) has the same problem, and the liquid barrier 2 is constructed up to the top, and the vertical PC steel material 17a in the vertical direction of the opening 20 and the left and right vertical of the opening 20. Direction The PC steel 17b is in an unstable state for a long time until it is tense.

Further, the PC steel material is arranged in a state of being passed through the sheath, and grout is performed in the sheath after the PC steel material is tense. However, the liquid barrier 2 moves due to the tension of the PC steel material after the opening 20 is closed. Grouting of the sheaths of the vertical PC steel 17a above and below the opening 20 and the left and right vertical PC steel 17b of the opening 20 cannot be performed until the tension of the PC steel after the opening 20 is closed is completed. Therefore, it may be necessary to take anti-corrosion measures for the circumferential PC steel material 17a and the vertical PC steel material 17b.

Further, when the vertical PC steel material 17a in the vertical direction of the opening 20 and the vertical PC steel material 17b in the left and right directions of the opening 20 are tensioned, the vertical and horizontal sides of the opening 20 are deformed by the compressive force. Therefore, after the opening 20 is closed, sufficient prestress is applied to the concrete of the closing portion 21 when the circumferential PC steel material 17a in the height range of the closing portion 21 and the vertical PC steel material 17b in the width range of the closing portion 21 are tensioned. It may not fit in.

For example, as shown in FIG. 13, in a flat plate P having an opening O, consider a case where vertical prestress (see arrow) is introduced into the flat plates P on the left and right of the opening O. The chain wire shows the flat plate P after deformation due to the prestress on the left and right of the opening O. In this example, the vertical prestress is introduced into the flat plates P on the left and right of the opening O, while the prestress in the vertical direction is introduced into the flat plate P of the opening O. Since no vertical prestress is introduced into the flat plate P in the width range, the flat plate P is distorted at the upper and lower edges of the opening O. As a result, it becomes difficult to introduce a predetermined vertical prestress into the closed portion that closes the opening O. FIG. 13 shows an example of introducing vertical prestress, but the same applies to the case of introducing horizontal prestress.

Further, in Patent Document 1, prestress by an additional tension material is introduced into the closed portion that closes the closed portion, and this tension material connects one end to the tension material at the edge of the closed portion and the other end of the closed portion. It is fixed on a nearby liquid barrier, and since the liquid barrier near the closed portion serves as a fixed end, it may be difficult to efficiently introduce prestress.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a wall body construction method and the like, which can proceed with construction in a stable state of the wall body and can shorten the construction period.

The first invention for solving the above-mentioned problems is a wall body construction method for constructing a tubular wall body having an opening, and when constructing the wall body with the opening left, the first invention is performed. The step (a) of introducing prestress into the wall body by tensioning the tension material arranged at a position not straddling the opening of the wall body and the temporary tension material having one end in the opening. wherein the step of releasing the tension by the temporary tendons (b), have a, the temporary tendon includes a height direction of the tendons of the wall body, tension in the step (a) of the height direction after tensioning timber, the wall body is constructed to the top, then, in the step (b) is tensioned by the height direction of the tension member is a wall construction wherein the Rukoto is canceled.

In the present invention, when constructing a tubular wall body, prestress is introduced into the wall body by a tension material that does not straddle the opening and a temporary tension material having one end in the opening. Then, the tension due to the temporary tension material is released, and the wall body having the above-mentioned opening is first constructed. This wall has a tension material that does not directly affect the opening, which greatly simplifies the work after the opening is closed, saves labor and shortens the construction period, and uses the above-mentioned temporary tension material to pre-tension the wall. By introducing stress at an early stage, it is possible to proceed with construction in a stable state against earthquakes, strong winds, etc.

Further, in the present invention, the tension material and the temporary tension material can uniformly introduce the prestress to the wall body excluding the opening, and the deformation can be the same as the case where the prestress is introduced to the wall body having no opening. can. This facilitates the introduction of predetermined prestress into the obstruction that obstructs the opening. Further, by releasing the tension caused by the temporary tension material, the prestress caused by the tension of the tension material straddling the obstruction portion can be reintroduced into the wall body. When the tension material is tense, the wall body undergoes the same deformation as when the prestress is introduced into the wall body having no opening, so that the prestress can be efficiently introduced into the closed portion.

A step of releasing the tension due to the temporary tension material, closing the opening to form a closed portion, and tensioning the tension material arranged at a position straddling the closed portion to introduce prestress into the wall body. It is desirable to have (c) further.
In the present invention, it is possible to construct a wall body without an opening by closing the opening and introducing prestress by a tension material straddling the closed portion into the wall body having the opening.

The tension material arranged at a position straddling the closed portion is configured by, for example, connecting the temporary tension materials on both sides of the closed portion with the tension material arranged in the closed portion. Alternatively, it may be a tension material newly arranged after removing the temporary tension material.
In the former case, the amount of tension material used can be reduced, and in the latter case, there is an advantage that a new tension material without scratches can be used for introducing prestress.

In the step (a), it is desirable that after the tensioning material is strained, the sheath through which the tensioning material is passed is filled with the filler.
In the present invention, the tension material at a position not straddling the opening and the temporary tension material having one end at the opening can bring the wall body before closing of the opening into a substantially final deformed state. It is possible to grout the tension material at an early stage without waiting for the blockage, and no rust prevention measures are required.

The second invention is a tubular wall body having an opening, a tension material arranged at a position not straddling the opening of the wall body, and a tension material having one end in the opening. Prestress is introduced by the tension of the tension material arranged at a position not straddling the opening of the wall body, and the tension material having one end in the opening is in the state of releasing the tension. It is a characteristic wall body.
In the present invention, the wall body having the above-mentioned opening is constructed before the opening is closed. This wall is stable by introducing tension material that does not directly affect the opening, which greatly simplifies the work after closure, and by introducing prestress by a temporary tension material that has one end in the opening. It is built in the state of being. Further, by releasing the tension due to the temporary tension material, the prestress due to the tension of the tension material straddling the obstruction portion can be reintroduced into the wall body.

A third invention is a tubular wall body having a closed portion that closes the opening, and a tension material arranged at a position that does not straddle the closed portion of the wall body, and a position that straddles the closed portion. Prestress is caused by the tension of the tension material arranged in the position not straddling the obstruction portion of the wall body and the tension material arranged in the position straddling the obstruction portion. The tension material introduced and arranged at a position straddling the closed portion is a tension material on both sides of the closed portion, and the tension materials having one end in the closed portion are connected to each other by the tension material arranged in the closed portion. It is a wall body characterized by being composed of.
In the present invention, it is possible to construct a wall body without an opening by closing the opening and introducing prestress by a tension material straddling the closed portion into the wall body having the opening. Further, by connecting the temporary tension materials on both sides of the closed portion with the tension material of the closed portion to form a tension material straddling the closed portion, the amount of the tension material used can be reduced.

INDUSTRIAL APPLICABILITY According to the present invention, it is possible to provide a wall body construction method or the like in which construction can be carried out in a stable state and the construction period can be shortened.

The figure which shows the liquid barrier 2a. The figure which shows the wall body construction method. The figure which shows the wall body construction method. The figure which shows the wall body construction method. The figure which shows the wall body construction method. The figure which shows the introduction of the prestress into the flat plate P which has an opening O. The figure which shows the re-installation of a circumferential PC steel material 17a. An example in which the vertical PC steel materials 17b and 17c are arranged in a U shape. The figure which shows the LNG tank 100. The figure which shows the wall body construction method of the conventional example. The figure which shows the wall body construction method of the conventional example. The figure which shows the wall body construction method of the conventional example. The figure which shows the introduction of the prestress into the flat plate P which has an opening O.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings.

(1. Liquid barrier 2a)
FIG. 1A is a diagram showing a liquid barrier 2a constructed by the wall body construction method according to the embodiment of the present invention.

The liquid barrier 2a is the liquid barrier of the LNG tank 100 described in FIG. 9 and the like, and is a concrete tubular wall body that is rigidly coupled and integrated with the bottom slab 5. In this embodiment, the liquid barrier 2a has a cylindrical shape. The description of the configuration of the LNG tank 100 already described with reference to FIG. 9 and the like will be omitted. Similarly, with respect to the liquid barrier 2a, the configuration described with reference to FIGS. 10 to 12 and the like may be omitted by giving the same reference numerals in the drawings and the like.

Similar to the above, the liquid barrier 2a has an opening 20 for construction at the lower part. The opening 20 is provided slightly above the bottom plate 5. The opening 20 is closed by placing concrete at the stage when the construction of the inner tank 3a is almost completed, and becomes the closed portion 21.

Circumferential PC steel materials 17a, vertical PC steel materials 17b, and 17c are arranged on the liquid barrier 2a, and prestress (compressive force) due to tension of these PC steel materials (tension materials) is introduced. PC steel wires and PC steel rods are used for each PC steel material, and these are arranged in a sheath (not shown) embedded in a liquid barrier 2a or the like. After the tension of the PC steel material, the sheath is filled (grout) with a filler made of a solidifying material such as mortar. Reinforcing bars (not shown) are also buried in the liquid barrier 2a, but the description thereof will be omitted here.

The circumferential PC steel material 17a is a tension material in the circumferential direction (corresponding to the left-right direction in FIG. 1A) of the liquid barrier 2a, and is arranged over the entire circumference of the liquid barrier 2a. The circumferential PC steel material 17a is provided in a plurality of stages in the height direction of the liquid barrier 2a, and both ends of each circumferential PC steel material 17a are provided outward protrusions (pilasters) at predetermined positions in the circumferential direction of the liquid barrier 2a. Is fixed at.

The vertical PC steel material 17b is a tension material in the height direction of the liquid barrier 2a, and is arranged over the entire height of the liquid barrier 2a. A plurality of rows of vertical PC steel materials 17b are provided in the circumferential direction of the liquid barrier 2a. The lower end of each vertical PC steel material 17b is fixed in the bottom slab 5, and the upper end is fixed at the top of the liquid barrier 2a.

The vertical PC steel material 17c is a tension material in the height direction of the liquid barrier 2a, and is arranged below the liquid barrier 2a. A plurality of rows of vertical PC steel materials 17c are provided in the circumferential direction of the liquid barrier 2a. The lower end of each vertical PC steel material 17c is fixed in the bottom slab 5, and the upper end is fixed to the liquid barrier 2a within the height range of the closing portion 21 (opening 20). However, depending on the position and height of the opening 20, the upper end may be fixed on the upper side or the lower side of the closing portion 21.

Here, the circumferential PC steel material 17a in the height range of the closed portion 21 is arranged so as to straddle the closed portion 21 on the left and right, and the PC steel materials 171 on the left and right sides of the closed portion 21 are arranged on the closed portion 21. It is configured by connecting with 171.

Similarly, the vertical PC steel material 17b within the width range of the closed portion 21 is arranged so as to straddle the closed portion 21 vertically, and the PC steel materials 172 on both the upper and lower sides of the closed portion 21 are arranged in the closed portion 21. It is configured by connecting with 172. The width direction of the closed portion 21 (opening 20) corresponds to the circumferential direction of the liquid barrier 2a.

The other circumferential PC steel materials 17a and vertical PC steel materials 17b (positions that do not straddle the closed portion 21) are basically one continuous PC steel material. However, it is possible to connect and use multiple PC steel materials.

Further, the vertical PC steel material 17c within the width range of the closed portion 21 is arranged so that the upper end thereof protrudes to the closed portion 21, and is arranged in the PC steel material 173 and the closed portion 21 below the closed portion 21. It is configured by connecting PC steel materials 173. The other vertical PC steel materials 17c (on the left and right of the closed portion 21) are basically one continuous PC steel material as described above, but a plurality of PC steel materials can be connected and used. Is.

FIG. 1B is a view of a cross section of the liquid barrier 2a in the height direction. A right-angled triangular haunch 22 is provided at the lower part of the liquid barrier 2a, and the vertical PC steel material 17c is arranged along the slope of the hypotenuse of the haunch 22. The upper end of the vertical PC steel material 17c is fixed by a notch 23 provided on the inner surface of the liquid barrier 2a. FIG. 1B is a cross section at a position without the closing portion 21, but the basic configuration is the same at the position of the closing portion 21. However, the upper end of the vertical PC steel material 17c is fixed on the inner surface of the closed portion 21.

As shown in the liquid barrier 2a'in FIG. 1 (c), the haunch 22 may not be provided. In this case, the upper end of the vertical PC steel material 17c is, for example, a box removed provided on the outer surface of the liquid barrier 2a'. It can be fixed by a part (not shown).

(2. Construction method of liquid barrier 2a)
FIGS. 2 to 5 are views showing a step of constructing a liquid barrier 2a by the wall body construction method according to the embodiment of the present invention.

The liquid barrier 2a is first constructed at a predetermined height (for example, about 5 to 10 m) with an opening 20 provided at the bottom as shown in FIG.

Then, the tension of the circumferential PC steel material 17a on the lower side of the opening 20, the left and right PC steel materials 171 of the opening 20, the vertical PC steel materials 17c on the left and right of the opening 20, and the PC steel material 173 on the lower side of the opening 20 is applied. Prestress is introduced into the liquid barrier 2a in order. For the above-mentioned circumferential PC steel material 17a and vertical PC steel material 17c, the sheath is filled with the filler at this stage. The tension order of each PC steel material is not limited to the above. This also applies to the subsequent steps.

The left and right PC steel materials 171 (temporary tension material) of the opening 20 are a part of the circumferential PC steel material 17a (see FIG. 1 (a)) straddling the opening 20 on the left and right, and one end thereof is the opening 20. The other end is fixed by the pilaster of the liquid barrier 2a.

The PC steel material 173 (temporary tension material) below the opening 20 is a part of the vertical PC steel material 17c (see FIG. 1A) within the width range of the opening 20, and the lower end is inside the bottom plate 5. The upper end is located at the opening 20 and is fixed at the edge thereof.

These PC steel materials 171 and 173 are also arranged in the sheath, but the filler is not filled in the sheath at this stage.

In the present embodiment, as shown in FIG. 3, a liquid barrier 2a is subsequently constructed up to the top, and the circumferential PC steel material 17a on the upper side of the opening 20, the left and right vertical PC steel materials 17b of the opening 20, and the opening 20. Prestress is introduced into the liquid barrier 2a by tensioning the PC steel materials 172 above and below in this order. For the above-mentioned circumferential PC steel material 17a and vertical PC steel material 17b, a filler is filled in the sheath at this stage.

The PC steel material 172 (temporary tension material) above and below the opening 20 is a part of the vertical PC steel material 17b (see FIG. 1A) straddling the opening 20 up and down, and is below the opening 20. The lower end of the PC steel material 172 is fixed in the bottom slab 5, and the upper end is located at the opening 20 and fixed at the edge thereof. The lower end of the PC steel material 172 on the upper side of the opening 20 is located at the opening 20 and is fixed at the edge thereof, and the upper end is fixed at the top of the liquid barrier 2a. These PC steel materials 172 are also arranged in the sheath, but the filler is not filled in the sheath at this stage.

In the present embodiment, the construction of the inner tank 3a is carried out in parallel with the construction of the liquid barrier 2a, and when the construction of the inner tank 3a is almost completed, the tensions of the PC steel materials 171, 172 and 173 are released, and these are released. The PC steel materials 171, 172, and 173 of the above are put into a state of releasing tension.

Then, as shown in FIG. 4, the PC steel materials 171 on the left and right sides of the opening 20 are connected to each other by the PC steel materials 171 arranged in the opening 20, and the circumferential PC steel materials straddling the opening 20 on the left and right by these PC steel materials 171. It constitutes 17a.

Similarly, the PC steel materials 172 on both the upper and lower sides of the opening 20 are connected to each other by the PC steel materials 172 arranged in the opening 20, and these PC steel materials 172 form a vertical PC steel material 17b that straddles the opening 20 vertically.

Further, a PC steel material 173 arranged in the opening 20 is connected to the upper end of the PC steel material 173, and the PC steel material 173 constitutes a vertical PC steel material 17c protruding into the opening 20.

The PC steel materials 171, 172, 173 of the opening 20 are arranged in a sheath (not shown), and this sheath is connected to the sheath through which the PC steel materials 171, 172, 173 in the liquid barrier 2a are passed.

Subsequently, as shown in FIG. 5, concrete is placed to close the opening 20 to form the closed portion 21, and the circumferential PC steel material 17a straddling the closed portion 21 on the left and right and projecting to the closed portion 21 in the vertical direction. The PC steel 17c and the vertical PC steel 17b straddling the closed portion 21 are tensioned in this order, and the sheath through which these PC steels are passed is filled with the filler.

Both ends of the circumferential PC steel material 17a are fixed by pilasters of the liquid barrier 2a. Further, the lower end of the vertical PC steel material 17b is fixed in the bottom slab 5, and the upper end is fixed at the top of the liquid barrier 2a. The lower end of the vertical PC steel material 17c is fixed in the bottom slab 5, and the upper end is fixed in the closed portion 21 of the liquid barrier 2a.

In the present embodiment, the PC steel materials are arranged in the range of the closed portion 21 with the same specifications and intervals as the left and right ranges of the closed portion 21, and the amount of the PC steel material is the same over the entire circumference of the liquid barrier 2a. Equal prestress is introduced. Therefore, the stress at each height of the liquid barrier 2a is the same over the entire circumference of the liquid barrier 2a.

As described above, in the present embodiment, when constructing the tubular liquid barrier 2a, the circumferential PC steel material 17a, the vertical PC steel material 17b, etc. that do not straddle the opening 20 and one end of the opening 20 are provided. Prestress is introduced into the liquid barrier 2a by the PC steel materials 171 and 172 having the above. After that, the tension caused by the PC steel materials 171 and 172 is released, and the liquid barrier 2a (see FIG. 3) having the opening 20 is first constructed.

This liquid barrier 2a greatly simplifies the work after closing by tensioning the circumferential PC steel 17a, the vertical PC steel 17b, etc., which do not directly affect the opening 20, before closing the opening 20. In addition to labor saving and shortening of construction period, the liquid barrier 2a can be constructed in a stable state against earthquakes, strong winds, etc. by introducing prestress by PC steel material 171 etc. at an early stage.

Further, as shown in FIG. 3, when the liquid barrier 2a is constructed up to the top, PC steel materials as designed can be arranged on the cross sections of all the liquid barrier 2a except the opening 20, and the prestress of these PC steel materials can be used. The liquid barrier 2a before the opening 20 is closed can be in a substantially final deformed state in which further deformation hardly occurs. Therefore, the circumferential PC steel materials 17a, the vertical PC steel materials 17b, and 17c that are not straddling the opening 20 can be grouted at an early stage without waiting for the opening 20 to be closed, and there is no concern about corrosion. Rust countermeasures (for example, dehumidification inside the sheath and adoption of PC steel coated with resin etc.) become unnecessary.

Further, in the present embodiment, by releasing the tension caused by the PC steel materials 171, 172, the prestress due to the tension of the circumferential PC steel material 17a and the vertical PC steel material 17b located straddling the closing portion 21 is introduced into the liquid barrier 2a. Can be redone. The liquid barrier 2a can move inward when the circumferential PC steel 17a and the vertical PC steel 17b are tense, and the same deformation as when prestress is introduced into the liquid barrier 2a having no opening occurs. Therefore, prestress can be efficiently introduced into the closed portion 21. Further, it is easy to introduce the prestress as designed into the concrete of the closed portion 21 due to the tension of the circumferential PC steel material 17a and the vertical PC steel material 17b, and the necessary prestress does not enter the closed portion 21. Can be avoided.

For example, in comparison with FIG. 13, in the present embodiment, at the stage shown in FIG. 3, the flat plates P on the left and right of the opening O and the flat plates P in the width range of the opening O, as shown in FIG. In addition, vertical prestress (see arrow) will be introduced, and by uniformly introducing prestress, the same deformation as when prestress is introduced into the flat plate P having no opening O will occur, and the chain line will be deformed. As shown, the upper and lower edges of the opening O are uniformly deformed. As a result, when introducing the vertical prestress into the closed portion that has closed the opening O, it is not difficult to introduce the predetermined prestress as described above. FIG. 6 shows an example of introducing the prestress in the vertical direction, but the same applies to the case of introducing the prestress in the left-right direction.

In this way, the opening 20 of the liquid barrier 2a in FIG. 3 is closed, and the circumferential PC steel 17a and the vertical PC steel 17b arranged at positions straddling the closed portion 21 are strained to introduce prestress into the liquid barrier 2a. By doing so, it is possible to finally construct a liquid barrier 2a in which the opening 20 is closed.

However, the present invention is not limited to this. For example, in the present embodiment, as shown in FIG. 4, the PC steel materials 171 on the left and right sides of the opening 20 are connected to form the circumferential PC steel material 17a straddling the opening 20 on the left and right, but the left and right sides of the opening 20 are formed. The tension of the PC steel material 171 was released, and the PC steel material 171 arranged in the sheath 18 as shown in FIG. 7 (a) was removed from the sheath 18 as shown in FIG. 7 (b), and FIG. 7 (c) was taken. ), A new circumferential PC steel material 17a may be re-installed in the sheath 18 arranged in the opening 20 and the sheath 18 in the liquid barrier 2a. Alternatively, it is also possible to install a new circumferential PC steel material 17a in the sheath separately arranged on the liquid barrier 2a or the like without removing the PC steel material 171 from the sheath 18.

When connecting the PC steel material 171 as described above, there is a possibility that the fixing part etc. may be scratched during the temporary tension of the PC steel material, but when the PC steel material is newly installed as described above, there is no scratch or the like. There is an advantage that various PC steel materials can be used for the introduction of prestress. On the other hand, when the PC steel material 171 is connected as described above, the amount of the PC steel material used can be reduced.

Further, in the present embodiment, the vertical PC steel materials 17b and 17c are arranged in a straight line, but as shown in FIG. 8, a U-shaped arrangement in which the bent portion is embedded in the bottom slab 5 may be used. In this case, as shown in FIG. 8, the PC steel materials 172 and 173 may be connected to form the vertical PC steel materials 17b and 17c in the width range of the closed portion 21, but the PC steel materials may be formed as in the example of FIG. It is also possible to replace 172 and 173 with new vertical PC steel materials 17b and 17c.

Further, in the present embodiment, the opening 20 is provided above the lower end of the liquid barrier 2a, but the opening 20 may be located at the lower end of the liquid barrier 2a. In this case, the circumferential PC steel material 17a below the opening 20 is omitted.

Further, in the present embodiment, the liquid barrier 2a and the bottom slab 5 are rigidly coupled from the beginning of construction of the liquid barrier 2a, but the circumferential PC steel material 17a or the PC steel material in the liquid barrier 2a is provided by a mechanism such as a pin slide. When the liquid barrier 2a is tense, the liquid barrier 2a can move with respect to the bottom slab 5, and after the liquid barrier 2a and the bottom slab 5 are rigidly coupled, the vertical PC steel materials 17b, 17c or PC steel material 172 in the liquid barrier 2a, You may be nervous about 173.

In some cases, it is possible to leave the openings 20 without closing them. A plurality of openings 20 are provided, some of which are closed as described above, and the rest are not closed and are not distorted. It is also possible to leave it as a quality opening 20. With respect to the opening 20 left without being closed, the tension caused by the PC steel materials 171, 172, 173 and the like is not released and is left as it is, and the filler is filled into the sheath.

Further, the liquid barrier 2a may be constructed with holes or small openings such as pipe insertion holes for electrical wiring and small windows for inspection between the PC steel materials. It is possible to leave these holes and small openings as they are without closing them. Further, a slit-shaped opening for inserting a steel plate or the like may be further provided by thinning out a part of the circumferential PC steel material 17a or the vertical PC steel material 17b. This opening is closed by, for example, reinforced concrete, and tension due to a tension material straddling the opening can be omitted.

Further, in the present embodiment, an example of the liquid barrier 2a of the LNG tank 100 has been described, but the present invention is applicable as long as an opening is provided when constructing a tubular wall body into which prestress is introduced. It can also be applied to the liquid barrier of LPG tanks, the walls of water tanks, or general wall structures.

Further, the present invention can be applied not only to the case of constructing the liquid barrier 2a from cast-in-place concrete, but also to the case of constructing the liquid barrier 2a by stacking precast blocks vertically and horizontally, which is different from the conventional example. By introducing prestress as shown in FIGS. 2 and 3, the upper, lower, left and right blocks are integrated at an early stage and stabilized during construction.

Although the preferred embodiments of the present invention have been described above with reference to the accompanying drawings, 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 modified examples within the scope of the technical idea disclosed in the present application, and these also naturally belong to the technical scope of the present invention. Understood.

2, 2a, 2a': Liquid barrier 3a: Inner tank 3b: Outer tank 4: Pile 5: Bottom slab 7: Ground 17a: Circumferential PC steel 17b, 17c: Vertical PC steel 18: Sheath 20: Opening 21: Closure 22: Haunch 23: Notch 100: LNG tank 171, 172, 173: PC steel

Claims (7)

It is a wall body construction method for constructing a cylindrical wall body having an opening.
When constructing the wall body with the opening left, the tension material arranged at a position not straddling the opening of the wall body and the temporary tension material having one end in the opening are tensioned. In the step (a) of introducing prestress into the wall body,
The step (b) of releasing the tension due to the temporary tension material and
Have a,
The temporary tension material includes a tension material in the height direction of the wall body, and after tensioning the tension material in the height direction in the step (a), the wall body is constructed to the top, and then the step. (b) tension by the height direction of the tension member is released in wall construction method comprising Rukoto. A step of releasing the tension due to the temporary tension material, closing the opening to form a closed portion, and tensioning the tension material arranged at a position straddling the closed portion to introduce prestress into the wall body. The wall body construction method according to claim 1, further comprising (c). The second aspect of the present invention, wherein the tensioning material arranged at a position straddling the closing portion is configured by connecting the temporary tensioning materials on both sides of the closing portion with the tensioning material arranged in the closing portion. How to build a wall. The wall body construction method according to claim 2, wherein the tension material arranged at a position straddling the closed portion is a tension material newly arranged after the temporary tension material is removed. The wall body according to any one of claims 1 to 4, wherein in the step (a), after the tension material is strained, the filler is filled in the sheath through which the tension material is passed. How to build. A cylindrical wall with an opening
A tension material arranged at a position not straddling the opening of the wall body, and
A tension material having one end in the opening,
Have,
Prestress is introduced by the tension of the tension material arranged at a position not straddling the opening of the wall body.
The tension material having one end in the opening is a wall body characterized in that the tension is released. A cylindrical wall body having a closed portion that closes the opening.
A tension material arranged at a position not straddling the closed portion of the wall body, and
A tension material placed at a position straddling the closed portion and
Have,
Prestress is introduced by the tension of the tension material arranged at a position not straddling the obstruction portion of the wall body and the tension material arranged at a position straddling the obstruction portion.
The tension material arranged at a position straddling the closed portion is configured by connecting the tension materials having one end of the closed portion, which are the tension materials on both sides of the closed portion, with the tension material arranged in the closed portion. A wall body characterized by being made.

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