JP6510397B2 - Tank and how to build a tank - Google Patents

Description

  The present invention relates to a tank and a method of constructing a tank.

  There is a PC (prestressed concrete) tank as equipment for storing low temperature liquids such as LNG (liquefied natural gas) and LPG (liquefied petroleum gas) (see, for example, patent documents 1-3).

  FIG. 8 shows an example of an LNG tank 100 storing LNG as a PC tank. The LNG tank 100 shown in FIG. 8 is provided with the liquid barrier 2 on the bottom plate 5 supported by the pile 4 in the ground 7, and the inner tank 3a and the outer tank 3b of steel plates or the like are provided inside thereof. LNG is stored in the inner tank 3a, and a cold storage material is disposed between the inner tank 3a and the outer tank 3b to perform cold storage.

  The liquid barrier 2 is a cylindrical side wall made of concrete, which is provided to prevent liquid leakage to the outside of the LNG when the inner tank 3a is broken, and is generally substantially cylindrical. The liquid barrier 2 and the bottom plate 5 are rigidly connected to ensure liquid tightness. The liquid barrier 2 needs to have a structure that can withstand the liquid pressure of LNG, so that the prestress due to the tension of the circumferential and longitudinal tendons is introduced.

  FIG. 9 is an example of a cross section in the vertical direction of the liquid protection dike 2. Although the hydraulic pressure can be resisted by introducing prestress due to the tendon 11 in the circumferential direction to the liquid protection dike 2, the liquid dike 2 is always in a state where the liquid pressure is not applied from inside the tank. Therefore, bending moments in the vertical plane due to the prestress in the circumferential direction are applied to the liquid protection dike 2. Longitudinal tendons 13 are provided primarily for reinforcement against this bending moment.

  When constructing the liquid barrier 2 by on-site placement of concrete, the concrete is poured for each lot (a section obtained by dividing the liquid barrier 2 in the longitudinal direction). That is, after placing the concrete 21 of the lowermost lot on the bottom plate 5, the concrete 21 of the upper lot is passed over. Similarly, after placing the concrete 21 of the lower lot, the procedure for placing the concrete 21 of the upper lot is repeated, and the concrete 21 of the uppermost lot is sequentially joined.

JP, 2009-203787, A Japanese Patent Application Laid-Open No. 59-21876 Japanese Examined Patent Publication 3-20548

  As described above, although the prestress is introduced by the tension member 11 in the circumferential direction to reinforce the liquid pressure in the liquid protection embankment 2, since the rigidity in the circumferential direction and the vertical direction of the liquid protection embankment 2 is similar, the liquid immersion embankment Due to the vertical rigidity of 2, the circumferential prestress can not be effectively introduced. As a result, it is necessary to introduce extra prestress in the circumferential direction. Moreover, as shown to Fig.10 (a), the bending moment M in the perpendicular surface by the prestress of the circumferential direction is transmitted below with the rigidity of the vertical direction of the dam 2. As shown in FIG. As a result, a large amount of bending moment is generated in the vertical plane at the lower part of the dike 2, etc., it is necessary to arrange a large amount of longitudinal tendons in order to resist this, the structure becomes complicated and the construction becomes complicated Become.

  Furthermore, the reservoir in the tank is at a cryogenic temperature, and the area C of the inside of the concrete frame (the inside of the liquid dike 2 and the upper side of the bottom plate 5) shown in FIG. Although it is likely to be distorted, the liquid breakwater 2 and the bottom plate 5 are rigidly connected, and since this shrinkage strain is restrained, a large temperature stress is generated, and a large bending moment m is generated at the junction of the liquid breakout 2 and the bottom plate 5 Occurs. As a result, in order to ensure the safety of the joint, a large amount of tendon should be provided mainly in the lower part of the liquid protection dike 2 and reinforcement by prestress must be carried out. Become. In FIGS. 10 (a) and 10 (b), illustration of the tension members 11, 13 and the like is omitted.

  The present invention has been made in view of the above problems, and it is an object of the present invention to provide a tank and the like which can simplify the reinforcing structure and can be easily constructed.

  A first invention for solving the above-mentioned problems has a bottom plate and a concrete cylindrical side wall formed on the bottom plate, and between the longitudinally divided sections of the side wall, At least any one between the bottom plate and the side wall is provided with a filler having a rigidity smaller than that of the side wall and a compressive strength higher than that of the side wall concrete or comparable to that of the side wall Is a tank characterized by

The filler is, for example, a mortar.
Each section obtained by dividing the side wall in the longitudinal direction is formed of, for example, a precast block.

  A second invention is a method of constructing a tank having a bottom plate and a cylindrical side wall made of concrete formed on the bottom plate, the section between the longitudinally divided side walls, the bottom plate and the like A tank, characterized in that at least one of the side walls is provided with a filling material having a rigidity smaller than that of the side wall concrete and having a compressive strength higher than that of the side wall concrete or comparable to that of the side wall. How to build

The filler is, for example, a mortar.
Each section obtained by dividing the side wall in the longitudinal direction is formed, for example, by cast-in-place concrete. When the filler is mortar, it is desirable to form the side wall of the section above the filler after hardening of the filler.
Moreover, each section which divided the said side wall into the vertical direction can also be formed by a precast block.

  According to the present invention, the strength of the side wall is not reduced but the rigidity is reduced at the portion of the filler, so that the reinforcing structure by prestress becomes simple, and the side wall can be easily constructed.

  That is, the rigidity in the vertical direction of the side wall is smaller than that in the circumferential direction of the concrete of the side wall due to the filler. Therefore, the prestress in the circumferential direction can be efficiently introduced into the concrete of the side wall without being hindered by the rigidity in the vertical direction of the side wall, and the amount of extra prestress introduced can be reduced. In addition, since the rigidity in the vertical direction of the side wall is reduced at the portion of the filler, the bending moment in the vertical plane due to the prestress in the circumferential direction is less likely to be transmitted downward. Thus, the synergetic effect that the circumferential prestress decreases and the bending moment in the vertical plane is less likely to be transmitted reduces the bending moment in the vertical plane generated in the lower portion of the side wall, etc. It is possible to reduce the reinforcement by the reinforcement and to reduce the number of tendons and to improve the workability.

  In addition, even if the inside of the concrete body is cooled by the reservoir in the tank and shrinkage strain is to occur, the rigidity of the filler between the side wall and the bottom plate is small and the restraint of strain is small. The temperature stress generated in the part decreases. As a result, the reinforcement of the prestress in the lower part of a side wall etc. can be lessened also in this point, the number of tendons decreases, and the effect of construction efficiency improvement is acquired.

  A mortar can be used as a filler. In general, the thermal expansion coefficient of mortar is almost equal to that of concrete, and the difference in the amount of strain due to temperature decrease does not become a problem. Further, each section of the side wall may be formed of cast-in-place concrete or a precast block, and in the case of the former, it is preferable to form the side wall of the upper section after hardening of the mortar.

  According to the present invention, it is possible to provide a tank and the like which can simplify the reinforcing structure and can be easily constructed.

Figure showing the liquid barrier 2a A diagram showing bending moments M and m in the vertical plane applied to the liquid breakwater 2a Diagram showing the construction method of the liquid barrier 2a Diagram showing the construction method of the liquid barrier 2a Figure showing the liquid barrier 2b Diagram showing the construction method of the liquid barrier 2b Diagram showing the construction method of the liquid barrier 2b Diagram showing the LNG tank 100 Diagram showing the liquid break 2 A diagram showing bending moments M and m in the vertical plane applied to the liquid protection dike 2

  Hereinafter, preferred embodiments of the present invention will be described in detail based on the drawings.

First Embodiment
(1. Liquid Reservoir 2a)
FIG. 1 is a view showing a cross section in the vertical direction of a liquid protection dike 2 a according to a first embodiment of the present invention. The liquid dike 2 a is a liquid dike of the LNG tank described in FIG. 8 and is a cylindrical side wall provided on the bottom plate 5. The liquid barrier 2a is, for example, substantially cylindrical. The liquid barrier 2a and the bottom plate 5 are formed of concrete. The configuration of the LNG tank other than the liquid barrier 2a is the same as that described in FIG.

  In the present embodiment, the liquid dike 2a is constructed by on-site placement of concrete 21a. The concrete 21a is placed in order from the bottom to the top for each lot (a section obtained by dividing the liquid dike 2a in the longitudinal direction).

  A mortar (filling material) 20 is provided as a joint between the concrete 21 a of each lot of the liquid protection dike 2 a and between the liquid dike 2 a and the bottom plate 5. The layer thickness of the mortar 20 may be about 1 to 5 cm.

  Here, the compressive strength of the mortar 20 is equivalent to that of the concrete of the liquid-breaking bank 2a or larger than that of the liquid-breaking bank 2a, and the elastic modulus (rigidity) of the mortar 20 is smaller than that of the concrete of the liquid-breaking bank 2a. The compressive strength of concrete or mortar can be measured, for example, by the method specified in JIS A 1108 “Test method for compressive strength of concrete”. The modulus of elasticity of concrete or mortar can be measured, for example, by the method specified in JIS A 1149 “Test method of static modulus of concrete”.

  The modulus of elasticity of the mortar 20 is about 80% smaller than that of concrete of the same compressive strength. Therefore, in the present embodiment, the compressive strength of the mortar 20 may be set to a value that is about one time, or more than one and less than 1.25 times the compressive strength of the concrete of the liquid-repellent dike 2a. Generally, since the compressive strength and the elastic modulus are in a proportional relationship, if the compressive strength of the mortar 20 is less than 1.25 times that of the concrete of the dike 2a, the elastic modulus of the mortar 20 is smaller than the concrete of the dike 2a. .

  The tension members 11 in the circumferential direction and the tension members 13 in the longitudinal direction are disposed on the liquid-repellent dike 2a. The tendons 11, 13 are arranged through the corresponding sheath tube 30. The gap between the tendons 11, 13 and the sheath tube 30 is filled with cement milk or the like. As the tendons 11 and 13, PC steels such as PC steel rods and PC steel wires can be applied.

  Longitudinal tendons 13 are disposed through the mortar 20. The liquid revetment 2 a is also provided with reinforcing bars (not shown) for reinforcement and the like, but the reinforcing bars can also be disposed through the mortar 20.

(2. Effects of mortar 20)
In the present embodiment, the mortar 20 can form a portion with low rigidity (a portion that does not restrain deformation) of the liquid protection dike 2a, and the rigidity in the circumferential direction of the concrete 21a of each lot is large. Stiffness of Therefore, it is possible to efficiently introduce the prestress due to the circumferential tendon 11 to the concrete 21a of each lot without being impeded by the rigidity in the vertical direction of the dike 2a, and reduce the amount of extra prestress introduced. be able to.

  Also, when the concrete of the upper lot is put on top of the concrete of the lower lot as in the past to make it a liquid-proof dike (see FIG. 10 (a)), each lot is made by the rigidity in the vertical direction of the liquid-proof dike. The bending moment in the vertical plane due to the prestress in the circumferential direction added to the concrete is transmitted downward, but in the present embodiment, the rigidity in the vertical direction of the liquid dike 2a decreases at the portion of the mortar 20, as shown in FIG. As shown in (a), the bending moment M in the vertical plane due to the circumferential prestress becomes less likely to be transmitted downward from the concrete 21 a of each lot.

  Thus, the bending moment in the vertical plane generated in the lower part of the liquid-proof dike 2a is reduced by the synergetic effect that the circumferential prestress is reduced and the bending moment in the vertical plane is less likely to be transmitted. .

  Furthermore, when concrete is cast on the bottom plate 5 to form a rigid joint as in the prior art (see FIG. 10 (b)), the inside of the concrete body is cooled and shrunk by the low temperature LNG in the tank When a strain is about to occur, this contraction strain is constrained to generate a large temperature stress, resulting in a large bending moment. On the other hand, in the present embodiment, as shown in FIG. 2 (b), the rigidity is reduced at the portion of the mortar 20 between the liquid-proof dike 2 a and the bottom plate 5, so the above-described restraint of contraction strain is small. As a result, the temperature stress generated at the junction of the liquid-repellent dike 2 a and the bottom plate 5 becomes small, and the bending moment m applied to the lower part of the liquid-dinet 2 a and the like becomes small. In FIGS. 2 (a) and 2 (b), illustration of the tendencies 11, 13 and the like is omitted.

(3. Construction method of liquid protection dike 2a)
When the liquid barrier 2a is constructed, after construction of the bottom plate 5, the concrete of the liquid barrier 2a is divided into several lots in order from the bottom to the top, and is placed in the same manner as the example described above. A sheath pipe 30 for passing the tendons 11 and 13 is embedded in the concrete of the bottom plate 5 and the liquid barrier 2a.

  However, in the present embodiment, as shown in FIG. 3A, a layer of mortar 20 is formed on the bottom plate 5 after placing the bottom plate 5 and before placing concrete of the liquid-proof dike 2a. In the present embodiment, the longitudinal tendon 13 is disposed in advance in the corresponding sheath tube 30, and the lower end portion is attached to the fixing portion in the bottom plate 5.

  After the mortar 20 is hardened, concrete 21a of the lowermost lot of the liquid-repellent dike 2a is placed on the mortar 20 as shown in FIG. 3 (b).

  After the concrete 21a is hardened, a layer of mortar 20 is formed on the concrete 21a as shown in FIG. 4 (a). After the mortar 20 is hardened, the upper lot of concrete 21a is placed on the mortar 20 as shown in FIG. 4 (b).

  Thereafter, the mortar 20 is provided on the concrete 21 a after hardening of the concrete 21 a of the lower lot, and after hardening of the mortar 20, the procedure of placing the concrete 21 a of the upper lot is repeated. In this way, the concrete 21a of the lot of the uppermost part of the liquid dike 2a is constructed in order from the bottom to the top.

  After that, the circumferential tendon 11 is disposed, and the circumferential and longitudinal tendons 11 and 13 are tensioned to introduce prestress, and the cement between the tendons 11 and 13 and the sheath tube 30 is cemented. When filling with milk etc., the liquid barrier 2a is completed.

  As described above, according to the present embodiment, the strength of the liquid-proof dike 2a does not decrease at the portion of the mortar 20 but the rigidity decreases, so that the reinforcing structure by prestress becomes simple, and the liquid-proof dike 2a becomes It becomes possible to build easily.

  That is, as compared with the circumferential rigidity of the concrete 21 a of each lot, the rigidity in the vertical direction of the liquid protection dike 2 a is reduced by the mortar 20. Therefore, the prestress in the circumferential direction can be efficiently introduced into the concrete 21a of each lot without being hampered by the rigidity in the vertical direction of the liquid protection dike 2a, and the amount of extra prestress to be introduced can be reduced. In addition, since the rigidity in the vertical direction of the liquid-proof dike 2a is reduced at the portion of the mortar 20, the bending moment in the vertical plane due to the prestress in the circumferential direction is less likely to be transmitted downward. Thus, the synergetic effect of the point that the circumferential prestress decreases and the point that the bending moment in the vertical plane becomes less likely to be transmitted reduces the bending moment in the vertical plane generated in the lower part of the liquid dike 2a etc. The reinforcement by prestress can be lessened, and the effect of reducing the number of tendons and improving the workability can be obtained.

  Further, even when the concrete body is cooled by the LNG in the tank and shrinkage strain is to be generated, the rigidity of the mortar 20 between the liquid dike 2a and the bottom plate 5 is small and the restraint force of strain is small. And the thermal stress generated at the joint of the bottom plate 5 is reduced. As a result, the reinforcement of the prestress in the lower part etc. of the liquid protection dike 2a can be reduced also in this point, the number of tendons decreases, and the effect of the improvement of construction property is acquired.

  Generally, the difference between concrete and mortar 20 is the presence or absence of coarse aggregate and the material as a whole is almost the same, so the thermal expansion coefficients of mortar 20 and concrete are almost equal, and the difference in these strain amounts due to temperature decrease does not become a problem . However, as long as the conditions described above, that is, the rigidity is smaller than the concrete of the liquid dike 2a and the compressive strength is larger than that of the concrete of the liquid dike 2a or comparable to the concrete of the liquid dike 2a, are satisfied It is also possible to use a filler other than mortar instead of mortar.

  Further, in the present embodiment, after hardening of the mortar 20, the liquid barrier 2a can be suitably constructed by placing the concrete 21a of the lot above it.

  However, the present invention is not limited to this. For example, as for the compressive strength of the mortar 20, in order to support the upper weight, the compressive strength may be increased as the mortar 20 is provided below. Furthermore, depending on the design, the mortar 20 under the conditions described above may be provided only between the liquid protection dike 2a and the bottom plate 5, or conversely, may be provided only between the concrete 21a of each lot of the liquid protection dike 2a. .

  Further, the shape of the liquid protection dike 2 a and the arrangement of the tension members 11 and 13 are not limited to those described in the present embodiment. For example, the lower part of the dike 2a may be widened outward with respect to the upper side thereof, and it is also possible to add a longitudinal tendon in the widened part. Also in this case, the number of additional tendons and the like can be reduced compared to the prior art. Further, although the lower end portion of the tendon 13 in the longitudinal direction is fixed in the bottom plate 5 in this embodiment, an example in which the tendon 13 is disposed in a substantially U shape and fixing in the bottom plate 5 is not performed is also conceivable. In this case, the U-shaped folded portion is embedded in the bottom plate 5.

  Moreover, although the example which constructs the liquid barrier 2a of the LNG tank was demonstrated in this embodiment, this invention is not limited to this, It may apply to the side wall of the tank which stores other low temperature liquids etc. It is possible.

  Next, another example of the present invention will be described as a second embodiment. The second embodiment will be described in terms of differences from the first embodiment, and the description of the same points will be omitted by attaching the same reference numerals in the drawings and the like.

Second Embodiment
In the present embodiment, as shown in FIG. 5, the liquid barrier 2b is constructed by a concrete precast block 10 (hereinafter sometimes referred to as a block). A plurality of blocks 10 are arranged in the vertical direction, and these blocks 10 form sections into which the liquid protection dike 2 b is divided in the vertical direction. In the block 10, a sheath tube 30 for passing the tendons 11, 13 is embedded.

  As in the first embodiment, a mortar 20 is provided as a joint between the blocks 10 of the liquid protection dike 2 b and between the liquid protection dike 2 b and the bottom plate 5. Similarly to the above, the compressive strength of the mortar 20 is equivalent to that of the concrete of the block 10 of the dike 2b or larger than that of the block 10, and the elastic modulus (rigidity) is smaller than that of the concrete of the block 10 of the dike 2b.

  Also in this case, as in the first embodiment, the mortar 20 is provided on the bottom plate 5 or the lower block 10, and the procedure of arranging the upper block 10 on the mortar 20 is repeated, and the top of the liquid dike 2b is repeated. By placing the blocks 10 in order from the bottom to the top, the liquid barrier 2b can be constructed. In this case, the upper block 10 is placed before hardening of the mortar 20.

  When constructing the liquid barrier 2b by the block 10, the mortar 20 can be filled later. That is, as shown in FIG. 6 (a), after the construction of the bottom plate 5, the lowermost block 10 of the liquid-proof dike 2b is disposed above the bottom plate 5 with a gap, and in FIG. 6 (b) A mortar 20 is provided as shown.

  Next, as shown in FIG. 7A, the upper block 10 is disposed above the lowermost block 10 with a gap, and mortar 20 is provided in the gap as shown in FIG. 7B. .

  Thereafter, after the upper block 10 is disposed on the lower block 10 with a gap, the procedure of providing the mortar 20 in the gap is repeated. In this manner, by sequentially arranging the block 10 from the bottom to the top to the top of the liquid dike 2b, the liquid dike 2b can be constructed.

  The same effect as that of the first embodiment can be obtained also in the present embodiment described above. Further, in the present embodiment, the use of the precast block 10 has the advantage of facilitating the construction of the liquid barrier 2b.

  The preferred embodiments of the present invention have been described above with reference to the accompanying drawings, but the present invention is not limited to such examples. It is apparent that those skilled in the art can conceive of various modifications or alterations within the scope of the technical idea disclosed in the present application, and of course these also fall within the technical scope of the present invention. It is understood.

2, 2a, 2b; liquid barrier 3a; inner tank 3b; outer tank 4; pile 5; bottom plate 7; ground 10; precast block 11, 13; tendon 20; mortar 21, 21a; concrete 30;

Claims (8)

Bottom version,
A concrete cylindrical side wall formed on the bottom plate;
Have
Between the longitudinally divided sections of the side wall, and / or between the bottom plate and the side wall,
A tank having a rigidity lower than that of the concrete of the side wall, and provided with a filler having a compressive strength higher than that of the concrete of the side wall or comparable to that of the side wall.   The tank according to claim 1, wherein the filler is mortar.   The tank according to claim 1 or 2, wherein each section obtained by dividing the side wall in the longitudinal direction is formed by a precast block. A method of constructing a tank having a bottom plate and a concrete cylindrical side wall formed on the bottom plate, comprising:
Between the longitudinally divided sections of the side wall, and / or between the bottom plate and the side wall,
A method for constructing a tank, comprising: a rigidity smaller than that of the concrete of the side wall, and providing a filler having a compressive strength higher than that of the concrete of the side wall or comparable to that of the side wall.   The method for constructing a tank according to claim 4, wherein the filler is mortar.   The method for constructing a tank according to claim 4 or 5, wherein each section obtained by dividing the side wall in the longitudinal direction is formed by cast-in-place concrete. The filler is mortar,
7. A method according to claim 6, wherein the sidewall of the section above the filler is formed after curing of the filler.   The method for constructing a tank according to claim 4 or 5, wherein each section obtained by dividing the side wall in the longitudinal direction is formed by a precast block.

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