JP6902189B2 - PC liquid barrier - Google Patents

Description

The present invention relates to a PC liquid barrier provided in a PC tank.

In recent years, when storing liquefied natural gas (hereinafter referred to as LNG), it is arranged in and around a metal double-shell LNG tank consisting of an outer tank and an inner tank from the viewpoint of effective use of the site and increase in capacity. A PCLNG tank (hereinafter simply referred to as a PC tank), which is a facility that ensures liquidtightness by integrating the liquid barrier with the liquid barrier and making the liquid barrier made of PC (prestressed concrete), is adopted. ..

The PC-made liquid barrier (hereinafter referred to as PC liquid barrier) is along the circumferential direction with respect to the concrete cylindrical peripheral wall erected on the outer peripheral edge of the foundation slab on which the LNG tank is placed. The PC steel material inserted through the structure and the PC steel material arranged along the vertical direction and having the lower end portion bent in a straight line or a U shape are arranged.

Then, by tensioning and fixing these PC steel materials in the circumferential direction and the vertical direction, prestress forces in the circumferential direction and the vertical direction are introduced into the cylindrical peripheral wall, so that cracks in the PC liquid barrier are suppressed. However, even if the stored LNG leaks from the inner tank, the liquidtightness is ensured so that it can be kept in the facility.

Here, the PC liquid barrier is rigidly joined to the foundation plate on the lower end side and the roof on the upper end (top) side in order to improve the resistance during an earthquake. When the tension force of is introduced, the deformation is restrained by the foundation slab and the roof in the vicinity of the lower end portion and the upper end portion of these PC liquid barriers. As a result, a bending moment is generated along the vertical direction, and cracks occur accordingly. Therefore, it is necessary to introduce not only the above-mentioned tension force in the circumferential direction but also the tension force along the vertical direction.

However, the above bending moments are concentrated in the vicinity of the upper end portion and the lower end portion of the PC liquid barrier. Therefore, if the PC steel material along the vertical direction is arranged from the upper end to the lower end of the PC liquid barrier to apply tension, the vertical prestress force is also applied to the middle portion in the height direction of the PC liquid barrier. Was introduced, resulting in waste.

Therefore, as described in Patent Document 1, PC steel materials in the vertical direction are aggregated and arranged at the lower end and the upper end of the PC liquid barrier, and cracks occur at the lower end and the upper end of these PC liquid barriers. A PC tank has been developed that effectively suppresses the problem.

Japanese Patent No. 5516963

In the PC tank of Patent Document 1, although the introduction of unnecessary prestress force can be omitted and the occurrence of cracks in the PC liquid barrier can be efficiently suppressed, a large amount of vertical force is formed at the upper end and the lower end of the PC liquid barrier. The PC steel materials along the direction are densely arranged. For this reason, the structure of the PC liquid barrier becomes complicated, and the work of applying tension to a large amount of PC steel materials along the vertical direction becomes complicated, the work efficiency decreases, and the construction period tends to be prolonged.

The present invention has been made in view of such a problem, and a main object thereof is to provide a PC liquid barrier capable of efficiently suppressing the occurrence of cracks while having a simple structure. Is.

In order to achieve such an object, the PC liquid barrier of the present invention is a PC liquid barrier constructed so as to surround the tank body installed on the foundation slab, and at least the legs are restrained by the foundation slab. A cast- in-place PC-made cylindrical peripheral wall in a state where the circumferential prestress is introduced, and a lateral peripheral surface of the cylindrical peripheral wall on the tension side in a range in which a bending moment is generated by the action of the circumferential prestress. The PC panel is provided with a PC panel installed in a state where vertical prestress is introduced, and the PC panel is provided with a shear connector on a surface facing the cylindrical peripheral wall and is installed integrally with the cylindrical peripheral wall. It is characterized by being done. Further, the top of the cylindrical peripheral wall is restrained by the roof, and the PC panel generates a bending moment due to the action of the circumferential prestress in the vicinity of the top and the leg of the cylindrical peripheral wall. It is characterized in that it is installed on the side peripheral surface on the tension side in the range.

According to the PC liquid barrier of the present invention described above, it is possible to suppress the occurrence of cracks by installing the PC panel into which the vertical prestress is introduced.

As a result, the sheath and tension material that have been conventionally installed on the cylindrical peripheral wall can be omitted, the structure of the cylindrical peripheral wall can be simplified, and the PC liquid barrier provided with the cylindrical peripheral wall has a highly rational and economical structure. It becomes possible to.

In addition, the work process is greatly reduced because the process of applying tension to the tension material and the grout filling process for fixing the tension material, which were carried out to introduce vertical prestress to the cylindrical peripheral wall, are no longer necessary. Not only is it easy to install, but it also makes it possible to significantly shorten the construction period.

In addition, if a vertical prestress is directly introduced into the height range in which the desired PC panel is installed on the cylindrical peripheral wall and a compressive force is applied , a large bending moment may be generated, for example. It is possible to more reliably suppress the occurrence of cracks due to the bending moment in the vicinity of the legs of the cylindrical peripheral wall or in the PC liquid barrier of a large-capacity PC tank on which a large hydraulic pressure acts at the time of liquid leakage.

Further, by using the PC panel and the configuration in which the vertical prestress is directly introduced into the cylindrical peripheral wall, the vertical prestress introduced directly into the cylindrical peripheral wall can be reduced, so that the vertical tension inside the cylindrical peripheral wall can be reduced. The quantity of the material can be reduced, or the tension applied to the vertical tension material can be reduced, and the workability can be greatly improved.

The PC liquid barrier of the present invention is a PC liquid barrier constructed so as to surround the tank body installed on the foundation slab, and at least the legs are restrained by the foundation slab, and the prestress in the circumferential direction is applied. Vertical prestress is introduced into the cylindrical peripheral wall made of PC in the introduced state and the lateral peripheral surface of the cylindrical peripheral wall on the tension side in the range where the bending moment is generated by the action of the circumferential prestress. It is a PC liquid barrier provided with a PC panel installed in a vertical state, and is characterized in that a reinforcing bar forming a vertical bar of the cylindrical peripheral wall is installed on the PC panel.

According to the PC liquid barrier of the present invention, when the PC panel is installed so as to be embedded in the cylindrical peripheral wall, the cylindrical peripheral wall is provided in order to prevent interference between the vertical streaks constituting the cylindrical peripheral wall and the PC panel. It is possible to fit the PC panel within the wall thickness of the cylindrical peripheral wall without performing complicated work such as increasing the wall thickness or changing the arrangement position of the vertical streaks.

According to the present invention, a PC panel in a state in which vertical prestress is introduced is integrally formed on the lateral peripheral surface of the cylindrical peripheral wall on the tension side in a range in which a bending moment is generated by the action of the circumferential prestress. By installing it, it is possible to efficiently suppress the occurrence of cracks in the cylindrical peripheral wall while having a simple structure.

It is a figure which shows the outline of the PC tank in embodiment of this invention. It is a figure which shows the cross section of the cylindrical peripheral wall which constitutes the PC liquid barrier in embodiment of this invention. It is a figure which shows the PC panel in embodiment of this invention. It is a figure which shows the detail of the vicinity of the top of the cylindrical peripheral wall in embodiment of this invention. It is a figure which shows the other example of the PC panel in embodiment of this invention. It is a figure which shows the detail of the vicinity of the leg part of the cylindrical peripheral wall in embodiment of this invention (the 1). It is a figure which shows the detail of the vicinity of the leg part of the cylindrical peripheral wall in embodiment of this invention (the 2). It is a figure which shows the detail of the vicinity of the leg part of the cylindrical peripheral wall in embodiment of this invention (the 3). It is a figure which shows the vertical tension material arranged on the cylindrical peripheral wall in embodiment of this invention.

The PC liquid barrier of the present invention has a cylindrical shape by integrally installing a PC panel with vertical prestress on the side peripheral surface of a cylindrical peripheral wall made of PC into which circumferential prestress has been introduced. While omitting the equipment such as sheaths and tensioning materials for introducing vertical prestress on the peripheral wall, it suppresses the occurrence of cracks due to the bending moment generated by the action of circumferential prestress on the cylindrical peripheral wall. Is what you do.

The PC liquid barrier can be applied to a PC tank that stores either liquefied natural gas (LNG), liquefied petroleum gas (LPG), etc., but in the present embodiment, it is used as a PC tank that stores LNG. Taking the PC liquid barrier provided as an example, the details will be described below with reference to FIGS. 1 to 7.

As shown in FIG. 1A, the PC tank 1 is integrated on the tank body 4, the foundation plate 5 on which the tank body 4 is installed, a plurality of piles K supporting the foundation plate 5, and the foundation plate 5. It is equipped with a PC liquid barrier 6 constructed in.

The tank body 4 includes an inner tank 3 for storing LNG and an outer tank 2 for protecting the inner tank 3, and between the outer tank 2 and the inner tank 3, as shown in FIG. 2, from granular pearlite or the like. A side cold insulation material Q is interposed. Then, glass wool 31 is provided on the side surface of the inner tank 3 on the side of the cold insulation material Q, and a cold resistance relaxation portion (PUF) 21 is provided on the surface of the outer tank 2 on the side of the cold insulation material Q.

Then, as shown in FIG. 1 (b), the PC liquid barrier 6 is integrally constructed along the outer peripheral edge of the foundation plate 5 so as to surround the tank body 4, and is shown in the side view of FIG. As described above, a cylindrical peripheral wall 7 and a plurality of PC panels 8 installed on its side peripheral surface are provided.

The cylindrical peripheral wall 7 is a wall body made of cast-in-place PC, and as shown in FIG. 2, includes a plurality of circumferential tension members 9 extending in the circumferential direction. In the present embodiment, since the tension force is applied to the circumferential tension member 9 by the post-tension method, a plurality of sheaths (not shown) are provided in the section from the top to the leg of the cylindrical peripheral wall 7. Are buried in layers with intervals.

The plurality of circumferential tension members 9 are subjected to tension force in a state of being inserted into each of the plurality of sheaths embedded in the cylindrical peripheral wall 7, and are fixed to the grout filled in the sheath to form a cylinder. Circumferential prestress is introduced into the circumferential wall 7.

The PC panel 8 is a precast concrete member manufactured by a factory or the like, and is formed by a plate piece having an arcuate cross section in which a tubular body along the outer peripheral surface or the inner peripheral surface of the cylindrical peripheral wall 7 is divided into a plurality of parts in the axial direction thereof. It is formed. In the present embodiment, as shown in FIG. 2, the PC panel 8 is installed on the outer peripheral surface of the cylindrical peripheral wall 7, and a plurality of PC panels 8 are arranged adjacent to each other so as to form a ring.

Further, as shown in FIG. 3A, a plurality of panel tensioning members 81 are arranged inside the PC panel 8 in a direction orthogonal to the arc-shaped end face, and tensioning force is applied by a prestressed method. Has been done. Since the arc-shaped end faces of the PC panel 8 installed on the cylindrical peripheral wall 7 form the upper end surface and the lower end surface, the vertical prestress is introduced.

In the present embodiment, the tension force for the panel 81 is applied by the pretension method, but the tension force may be applied by the post tension method. In this case, when the PC panel 8 is manufactured, for example, as shown in FIG. 3B, a plurality of U-shaped sheaths 82 are embedded in a direction orthogonal to the arc-shaped cross section.

Then, the tension member 81 for the panel may be inserted into each of the plurality of U-shaped sheaths 82 in the manufactured PC panel 8 to apply tension, and the sheath may be filled with grout to fix the sheath. The sheath tube 82 does not necessarily have to be U-shaped, and may be a linear tube material penetrating the PC panel 8.

In the PC liquid barrier 6 having such a configuration, since the circumferential prestress is introduced into the cylindrical peripheral wall 7, if a liquid leak occurs from the tank body 4, it is generated by the leak pressure. It is possible to resist the tensile force. However, the top of the cylindrical peripheral wall 7 is rigidly connected to the roof (not shown) and restrained, and the legs are integrally constructed and restrained with the foundation plate 5. Therefore, in a normal state where no liquid leakage pressure is applied to the cylindrical peripheral wall 7, vertical bending moments are generated in the vicinity of the top and the legs of the cylindrical peripheral wall 7. Then, the side peripheral surface of the cylindrical peripheral wall 7 in the range where the bending moment is generated and the portion on the tension side is in a state where cracks are likely to occur.

Therefore, the PC panel 8 into which the above-mentioned vertical prestress is introduced is installed on the side peripheral surface of the cylindrical peripheral wall 7 that is in the range where the bending moment is generated and is on the tension side.

For example, as shown in FIG. 4A, when it is specified that the lateral peripheral surface on the pulling side is only the outer peripheral surface in the vicinity of the top of the cylindrical peripheral wall 7, a bending moment of the cylindrical peripheral wall 7 is generated. The PC panel 8 is installed on the outer peripheral surface side in the range to be used. At this time, the PC panel 8 may be installed so as to be adjacent to the outside of the wall thickness secured on the cylindrical peripheral wall 7, or as shown in FIG. 4 (b), within the wall thickness of the cylindrical peripheral wall 7. It may be installed so as to be buried.

Further, when it is specified that the lateral peripheral surface on the pulling side is dispersed in the outer peripheral surface and the inner peripheral surface in the range where the bending moment of the cylindrical peripheral wall 7 is generated, it is shown in FIG. 4 (c). As described above, the PC panel 8 is installed on each of the outer peripheral surface and the inner peripheral surface on the tension side. In this case as well, the PC panel 8 may be installed so as to be adjacent to the outside of the wall thickness secured in the cylindrical peripheral wall 7, or may be installed so as to be embedded in the wall thickness of the cylindrical peripheral wall 7. Good.

As described above, the outer peripheral surface of the cylindrical peripheral wall 7 on which the PC panel 8 in the state where the vertical prestress is introduced can suppress the occurrence of cracks due to the bending moment. As a result, the sheath and tension material for introducing vertical prestress, which have been conventionally equipped on the cylindrical peripheral wall 7, can be omitted, the structure of the cylindrical peripheral wall 7 can be simplified, and a PC provided with the cylindrical peripheral wall 7 can be simplified. It is possible to make the liquid barrier 6 a structure rich in rationality and economy.

Further, since the step of applying the tension force to the tension material and the grout filling process for fixing the tension material, which were carried out to introduce the vertical prestress to the cylindrical peripheral wall 7, are not required, the work process is completed. Not only is it significantly omitted and workability is good, but it is also possible to significantly shorten the construction period.

Here, if the PC panel 8 is installed so as to be integrated with the cylindrical peripheral wall 7, the occurrence of cracks due to the bending moment can be more reliably suppressed. Therefore, as shown in FIGS. 3 and 4, the PC A shear connector 83 such as a stud gibber may be provided on the surface of the panel 8 facing the cylindrical peripheral wall 7.

By the way, when the vertical prestress is introduced into the PC panel 8, the magnitude of the tension applied to the panel tension member 81 differs depending on the bending moment generated in the cylindrical peripheral wall 7. Then, when it is desired to introduce a larger vertical prestress to the PC panel 8, the tension applied to the panel tension material 81 also increases, so that it is necessary to secure a sufficient member thickness for the PC panel 8.

In such a case, if the PC panel 8 is installed so as to be embedded in the wall thickness of the cylindrical peripheral wall 7, a sufficient cover thickness cannot be secured for the vertical bars 71 arranged on the cylindrical peripheral wall 7, or these A situation such as interference between the vertical stripe 71 and the PC panel 8 occurs.

Therefore, in the present embodiment, as shown in FIG. 5, a reinforcing bar 84 similar to the vertical bar 71 arranged on the cylindrical peripheral wall 7 is embedded in advance in the PC panel 8'that has secured the required member thickness. doing. By making the reinforcing bar 84 function as a vertical bar 71 to be arranged on the cylindrical peripheral wall 7, complicated work such as increasing the wall thickness of the cylindrical peripheral wall 7 and changing the bar arrangement position of the vertical bar 71 can be performed. It is possible to fit the PC panel 8 within the wall thickness of the cylindrical peripheral wall 7 without doing so.

Therefore, the upper and lower ends of the reinforcing bar 84 are from the upper end surface and the lower end surface of the PC panel 8'so that the reinforcing bar 84 can form a lap joint together with the vertical bar 71 when the PC panel 8'is installed on the cylindrical peripheral wall 7. It is good to expose it. The reinforcing bar 84 may be arranged in parallel with the PC panel 8'without being embedded in the PC panel 8', and a lap joint may be formed together with the vertical bar 71 arranged on the cylindrical peripheral wall 7.

On the other hand, as shown in FIG. 6A, even in the vicinity of the legs of the cylindrical peripheral wall 7, when it is specified that the lateral peripheral surface on the pulling side is only the outer peripheral surface within the range where the bending moment is generated, the cylindrical peripheral surface is formed. The PC panel 8 is installed on the outer peripheral surface of the peripheral wall 7. At this time, the lower end of the PC panel 8 may be rooted in the basic plate 5.

Further, as shown in FIG. 6B, the PC panel 8 may be installed so as to be embedded in the wall thickness of the cylindrical peripheral wall 7. Further, in the range where the bending moment is generated, when the lateral peripheral surface on the tension side is dispersed in the outer peripheral surface and the inner peripheral surface, as shown in FIG. 6C, the outer peripheral surface on the tension side and the outer peripheral surface on the tension side and the outer peripheral surface are dispersed. A PC panel 8 is installed on each of the inner peripheral surfaces.

By the way, in the vicinity of the legs of the cylindrical peripheral wall 7, a tensile force that cannot suppress the occurrence of cracks often acts on the side peripheral surface only by installing the PC panel 8 in which the vertical prestress is introduced. Therefore, in the present embodiment, the vertical tension member 11 is installed in the range where the bending moment is generated in the vicinity of the legs of the cylindrical peripheral wall 7, and the compressive force is applied.

As shown in FIG. 7, the vertical tension member 11 straddles the base plate 7 with a constant interval in the circumferential direction in a vertically erected state in a range where a bending moment is generated in the vicinity of the legs. , It is inserted into each of the plurality of U-shaped sheaths 10 embedded. Then, the vertical tension member 11 is fixed to the grout filled in the U-shaped sheath 10 in a state where the tension force is applied, and the legs of the cylindrical peripheral wall 7 as shown in FIGS. 6A to 6C. Vertical prestress is introduced in the range where the bending moment occurs in the vicinity.

With the above configuration, in the vicinity of the legs of the cylindrical peripheral wall 7, a compressive force acts on the range where the bending moment is generated via the vertical tension member 11. As a result, the PC panel 8 and the vertical tensioning material 11 are used in combination with respect to the vicinity of the legs of the cylindrical peripheral wall where a large bending moment is generated as compared with the top, so that cracks due to the bending moment are surely generated. It can be suppressed. Further, it is possible to adopt the PC liquid barrier 6 using the PC panel 8 for the large-capacity PC tank 1 in which a large liquid pressure acts at the time of liquid leakage.

In this way, when the PC panel 8 and the vertical tensioning material 11 are used in combination, the vertical prestress introduced directly into the cylindrical peripheral wall can be reduced. Therefore, the vertical tensioning material to be installed straddling the cylindrical peripheral wall 7 and the base plate 7 is installed. The quantity of 11 can be reduced, or the tension applied to the vertical tension material 11 can be reduced, and the workability can be significantly improved.

As the circumferential tension material 9, the vertical tension material 11, and the panel tension material 81, any PC steel material generally used for prestressed concrete such as PC steel wire or PC steel stranded wire is used. You may.

Further, a sheath through which the circumferential tension material 9 is inserted (not shown), a U-shaped sheath 10 through which the vertical tension material 11 is inserted, and a U-shaped sheath 82 through which the panel tension material 81 is inserted are In either case, any pipe material may be used as long as it is generally used when applying tension to the PC steel material by the post-tension method.

Further, the PC panel 8 may function as a formwork for placing cast-in-place concrete in order to construct the cylindrical peripheral wall 7. In this case, the adjacent PC panels 8 may be assembled while being connected to each other via a connecting jig. Then, the height of the PC panel 8 may be manufactured to be equal to the casting height of concrete at one time, or may be manufactured to a size that facilitates the transport work and the installation work.

It goes without saying that the PC liquid barrier 6 of the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the gist of the present invention.

In the present embodiment, the PC panel 8 is installed near the top of the cylindrical peripheral wall 7, and the vertical tension member 11 and the PC panel 8 are installed near the legs of the cylindrical peripheral wall 7. However, it is not necessarily limited to this.

For example, the vertical tension member 11 and the PC panel 8 may be installed in both the vicinity of the top of the cylindrical peripheral wall 7 and the vicinity of the legs of the cylindrical peripheral wall 7, or the PC panel 8 may not be installed in the vicinity of the top. If the occurrence of cracks can be suppressed by its own weight, the PC panel 8 or the vertical tension member 11 and the PC panel 8 may be installed only in the vicinity of the legs. As described above, depending on the structural conditions of the PC liquid barrier, any combination of the PC panel 8 and the vertical tensioning material 11 may be adopted to suppress the occurrence of cracks in the cylindrical peripheral wall 7.

Further, in the present embodiment, the PC panel 8 is manufactured at the factory, but the present invention is not necessarily limited to this, and the PC panel 8 may be manufactured at a yard or the like installed at the construction site.

1 PC tank 2 Outer tank 21 Cold resistance relaxation unit (PUF)
3 Inner tank 31 Glass wool 4 Tank body 5 Basic version 6 PC liquid barrier 7 Cylindrical peripheral wall 71 Vertical bar 8 PC panel 81 Panel tension material 82 U-shaped sheath 83 Shear connector 84 Reinforcing bar 8'PC panel 9 Circumferential tension Material 10 U-shaped sheath 11 Vertical tension material K Pile Q Side cold insulation material

Claims (3)

It is a PC liquid barrier that is constructed so as to surround the tank body installed on the foundation plate, and at least the legs are restrained by the foundation plate.
Cylindrical peripheral wall made of cast- in-place PC with circumferential prestress introduced,
A PC panel installed with vertical prestress introduced on the lateral peripheral surface of the cylindrical peripheral wall on the tension side in a range in which a bending moment is generated by the action of the circumferential prestress is provided.
The PC panel is provided with a shear connector on a surface facing the cylindrical peripheral wall, and is integrally installed with the cylindrical peripheral wall . In the PC liquid barrier according to claim 1.
The top of the cylindrical peripheral wall is constrained to the roof
The PC panel is installed on the lateral peripheral surface on the tension side in the vicinity of the top of the cylindrical peripheral wall and the vicinity of the legs in a range in which a bending moment is generated by the action of the circumferential prestress. Characterized PC liquid barrier. It is a PC liquid barrier that is constructed so as to surround the tank body installed on the foundation plate, and at least the legs are restrained by the foundation plate.
A PC-made cylindrical peripheral wall with circumferential prestress introduced,
A PC including a PC panel installed on the lateral peripheral surface of the cylindrical peripheral wall on the tension side in a range where a bending moment is generated by the action of the circumferential prestress, with the vertical prestress introduced. It ’s a liquid barrier,
A PC liquid barrier characterized in that reinforcing bars forming vertical bars of the cylindrical peripheral wall are installed on the PC panel.

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