JP2017036597A - Wall body construction method and wall body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a wall body construction method, which can rapidly construct a prestressed wall body with less problems in design or construction.SOLUTION: In constructing a concrete dike 2a vertically prestressed with a tendon 13a in a lower part 21, the dike 2a having a hole part 20 formed on its outer side face and sheath pipes 30 formed above the hole part 20 is formed, and an upper end of the tendon 13a protrudes into the hole part 20. The tendon 13a is tensed by pulling the upper end with a pulling material 60 passing through the sheath pipe 30, and the upper end is fixed in the hole part 20. The hole part 20 is filled with a filler 201.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a wall body construction method and a wall body for constructing a cylindrical wall body.

  A PC (prestressed concrete) tank is a facility for storing liquids such as LNG (liquefied natural gas) and LPG (liquefied petroleum gas). FIG. 8 shows an example of an LNG tank 100 that stores LNG as a PC tank. The LNG tank 100 of FIG. 8 is provided with a liquid breakwater 2 on a bottom slab 5 supported by a pile 4 in the ground 7 and an inner tank 3a and an outer tank 3b made of a steel plate or the like inside. The roof portion of the outer tub 3b is made of steel or a composite structure of steel plate and reinforced concrete, and the side portion of the outer tub 3b is formed by attaching a steel liner plate to the liquid barrier 2. The bottom of the outer tub 3b has a shape in which a liner plate is pasted on the bottom plate. LNG is stored in the inner tank 3a, and a heat insulating material is disposed between the inner tank 3a and the outer tank 3b to perform cold insulation.

  The breakwater 2 is a concrete cylindrical wall provided to prevent leakage of LNG to the outside when the inner tank 3a is damaged, and is usually cylindrical. The breakwater 2 needs to have a structure capable of withstanding the hydraulic pressure of LNG, so that prestress is introduced by the tension of the circumferential and longitudinal tension members.

  FIG. 9 is a diagram illustrating an example of a cross section of the liquid breakwater 2. Although the hydraulic pressure can be resisted by introducing a prestress by the circumferential tension material 11 to the liquid breakwater 2, the liquid breakwater 2 is always in a state where no liquid pressure is applied from the inside of the tank. For this reason, a bending moment in the vertical plane due to circumferential prestress is applied to the breakwater 2. A longitudinal tension member is provided mainly to resist this bending moment, and a long tension member (not shown) extending from the lower portion 21 of the breakwater 2 to the top through the upper portion 22 and below the breakwater 2. In many cases, a short tension member 13 provided in the portion 21 is used in combination. By introducing eccentric prestress in the breakwater 2 with these tendons, the bending moment in the opposite direction to the bending moment in the vertical plane is generated, and the bending moment in the vertical plane is canceled out. be able to.

  Since the hydraulic pressure applied to the breakwater 2 generally increases at the lower portion 21, the circumferential tension material 11 is more disposed at the lower portion 21 and less disposed at the upper portion 22. As a result, the bending moment in the vertical plane is large in the lower part 21 of the liquid barrier 2 and is small in the upper part 22 thereof. Therefore, in the lower portion 21 of the breakwater 2, the short tension members 13 are added and the longitudinal tension members are densely arranged. In the upper portion 22 of the breakwater 2, the above-described long tendon exists, but the arrangement of the tendon is relatively rough due to the absence of the short tendon 13. In some cases, the above-described long tendon may not be arranged. is there.

  The lower end portion of the longitudinal tension member 13 in the lower portion 21 of the breakwater 2 is fixed by a fixing portion 131 embedded in the bottom plate 5. The upper end portion of the tension member 13 is fixed by the fixing portion 131 in the middle of the liquid breakwater 2, and this fixing portion 131 is often provided in a range of 3 to 10 m from the bottom end of the liquid breakwater 2. Conventionally, after the concrete in this range is placed and the strength is developed, the tension member 13 is tensioned and the upper end portion is fixed by the fixing portion 131, and then the liquid breakwater 2 above the fixing portion 131 is fixed. Concrete was cast.

  As another method, Patent Document 1 discloses that the upper end portion of the longitudinal tension material in the lower part of the breakwater is obliquely drawn out to the cutout portion on the outer side surface of the breakwater, and the tension material is removed at the cutout portion. After tension and fixing of the upper end, the notch is filled with concrete.

JP 2007-303101 A

  In the conventional method, since the concrete of the liquid bank cannot be placed only after the tension work of the longitudinal tension material is performed in the lower part of the liquid bank, the entire construction period is extended by the tension work, The period is 1.5 to 2.0 months for a 200,000 KL class tank.

  In addition, the breakwater will be constructed with a construction opening in the lower part used to carry in materials and equipment, etc., but this opening has been completed after the construction of the interior of the breakwater such as the construction of the inner tank. Otherwise it cannot be closed. As a result, it is often the case that the breakwater is built to the top, then the concrete is cast and the opening is closed, and then the tensioning work is performed. In this case, the tension material must be extended to the top of the breakwater. There is a lot of waste.

  If it is the method of patent document 1, it is not necessary to interrupt construction of a breakwater by tension | tensile_strength work, the whole construction period can be shortened, and a tension | tensile_strength material can also be arrange | positioned short also in the position of the opening part for construction. However, in the method of Patent Document 1, the upper end portion of the tension member is pulled out obliquely to the notch portion on the outer side surface of the liquid barrier and is tensioned from the outside, so that the upper end portion of the tension member needs to be bent outward.

  PC steel used for the tension material can be bent and arranged only with a minimum curvature of about R = 3 m, and the PC steel material is arranged in a straight line near the anchoring part. It is necessary to avoid interference with other reinforcing bars and the design becomes difficult. In addition, in order to avoid such interference, the reinforcing reinforcing bars in the circumferential direction of the interference range may be cut once, and reinforcement of the range may be performed afterwards, but the range becomes large and construction is troublesome. In addition, if the tendon is bent and disposed, the frictional resistance force during tension is large and the introduction force is small, and as a result, an additional tendon must be disposed.

  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 that can quickly construct a wall body into which prestress has been introduced and have few problems in design and construction.

  1st invention for solving the subject mentioned above is the wall body construction method which constructs the cylindrical wall body made from concrete in which the prestress by the longitudinal direction tension material was introduced into the lower part, Forming a wall having a hole and having a through-hole extending upward from the hole, and projecting at least one end of the tendon into the hole, and the end A step (b) of tensioning the tension material by tensioning the tension material passed through the through hole and fixing the end portion in the hole portion; and a step (c) of filling the hole portion with a filler. And (d) filling the through hole with a filler.

  In the present invention, even after the wall body is formed, the tension material in the lower part of the wall body in which the end portion protrudes from the hole portion on the side surface of the wall body is tensioned by the tension material passed through the through hole above the hole section. Therefore, it is not necessary to interrupt the construction of the wall body by the tension work of the tendon material, and the entire construction period can be shortened. In addition, as described above, there is no need to bend the tension material and pull it to the outer side surface from the outside, so that interference with the circumferential tension material inside the wall body or reinforcing reinforcing bars hardly occurs, and the design is easy. . Further, when the reinforcing reinforcing bars in the circumferential direction of the interference range are once cut, the range can be reduced.

The through hole is provided in the vertical direction from the hole to the top of the wall body, and in the step (b), it is desirable to pull the tensile material with a tension device provided at the top of the wall body.
The tension member can be pulled by, for example, a tension device provided on the top of the wall body, which facilitates the tensioning operation.

In the step (a), the hole is preferably provided on the outer side surface of the wall body.
Thereby, various work can be performed from the outside of the wall body when the tension material is tensioned, and it does not interfere with the work performed on the inside of the wall body such as an internal facility worker.

Further, the tendon is arranged in a substantially U shape, and both end portions project into the hole on the side surface of the wall body, and one end of the tendon is fixed to the hole in the step (b). It is desirable to tension the other end in the state.
The tension work can be made efficient by arranging the tension material in a substantially U shape and performing the tension as described above.

  A second invention is a concrete cylindrical wall body in which prestress due to a longitudinal tension material is introduced into a lower portion, and has a hole portion filled with a filler on a side surface, and the hole portion The wall body is characterized in that a through-hole is provided extending from the top to the bottom and filled with a filler, and at least one end of the tendon is fixed in the hole.

  According to the present invention, it is possible to provide a wall construction method or the like that can quickly construct a wall body into which pre-stress is introduced and has few problems in design and construction.

Diagram showing breakwater 2a The figure which shows the construction method of the breakwater 2a The figure which shows the hole part 20. The figure which shows the construction method of the breakwater 2a in the opening part 23 for construction The figure which shows the construction method of the breakwater 2a in the opening part 23 for construction Diagram showing breakwater 2b The figure which shows another example of a hole Diagram showing LNG tank 100 Diagram showing breakwater 2

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

(1. Breakwater 2a)
Fig.1 (a) is a figure which shows the breakwater 2a which concerns on the 1st Embodiment of this invention. The breakwater 2a is a breakwater for the LNG tank described with reference to FIG. 8 and is a concrete cylindrical wall body fixedly provided on the bottom plate 5. The breakwater 2a has a substantially cylindrical shape, for example. The configuration of the LNG tank other than the breakwater 2a is the same as that described with reference to FIG.

  In addition to the circumferential tension member 11 and the reinforcing steel bars (not shown), the breakwater 2a resists bending moment in the vertical plane caused by the prestress by the circumferential tension member 11, so As the tension material, a long tension material (not shown) reaching the top from the lower portion 21 of the breakwater 2a through the upper portion 22 and a short tension material 13a provided on the lower portion 21 of the breakwater 2a are arranged. The tendon members 11, 13a are disposed through the corresponding sheath tube 30. A gap between the tendon members 11 and 13a and the sheath tube 30 is filled with a filler such as cement milk.

  The lower part 21 (bottom part) of the breakwater 2a is widened outward with respect to the upper part 22, and in this embodiment, the outer side surface of the lower part 21 is substantially linear so that it goes outward as it goes downward. It has an inclined tapered shape. The outside means the outside of the tank, and the center side of the tank is the inside.

  A vertical tension member 13a is disposed in the lower portion 21 of the breakwater 2a. The upper end of the tension member 13a is fixed by a fixing portion 131 at a hole 20 provided on the outer side surface of the breakwater 2a. It is fixed.

  The cross section of the hole 20 in the vertical direction is substantially U-shaped, and the position of the fixing unit 131 in the hole 20 corresponds to the planar position of the longitudinal sheath tube 30 disposed in the upper portion 22. The sheath tube 30 is used for inserting a tensile material, which will be described later, and then filled with a filler 301.

  In the lower part 21 of the breakwater 2a, the tendon 13a is inclined along the inclination of the outer side surface of the lower part 21 so as to go outward as it goes downward. In the lower part 21 of the breakwater 2a, the tendon 13a is arranged eccentrically outside the center line (see the dotted line in the figure) in the thickness direction of the lower part 21, and the cover on the outer side surface is about 20 to 25 cm. ing. The lower end portion of the tension material 13 a is fixed by the fixing portion 131 in the bottom plate 5.

  As the tension material 13a, PC steel materials such as PC steel rod, PC steel wire (single strand), PC steel stranded wire, unbonded PC steel stranded wire can be applied. When an unbonded PC steel stranded wire is used, the sheath tube 30 can be omitted.

  FIG. 1B shows the vicinity of the lower part of the liquid barrier 2a as seen from the outside. In this embodiment, the hole 20 is formed for every tendon 13a. Each hole 20 is filled with a filler 201 such as concrete or mortar.

(2. Construction method of the breakwater 2a)
When constructing the breakwater 2a, for example, as shown in FIG. 2A, after the bottom plate 5 is constructed, the concrete of the breakwater 2a is placed in order from the bottom to the top.

  A fixing portion 131 for fixing the lower end portion of the tension material 13a is embedded in the bottom plate 5, and a sheath tube for allowing the tension materials 11, 13a and a tension material described later to pass through the concrete of the bottom plate 5 and the breakwater 2a. 30 is buried. The sheath tube 30 is provided with a filler inlet and a hose (not shown) for air removal and filling confirmation as required.

  A hole 20 for fixing the upper end of the tension member 13a is formed at a predetermined location on the outer side surface of the liquid barrier 2a by boxing or the like. A sheath tube 30 (through hole) for passing a tensile material, which will be described later, of the upper portion 22 is arranged in the vertical direction so as to extend upward from the hole portion 20 and reach the top of the liquid barrier 2a.

  In the present embodiment, the tension member 13a is disposed in advance in the corresponding sheath tube 30 and the lower end portion is attached to the fixing portion 131 in the bottom plate 5 before placing the concrete on the breakwater 2a. The upper end portion of the tension member 13a is projected into the hole portion 20.

  The concrete of the breakwater 2a is placed in several lots, but it is continuously launched up to the top without interruption. About the tension material 13a, it becomes possible to perform the tension work when the concrete strength in the range up to the height of the hole 20 is developed and reaches a predetermined value. high. In this embodiment, in order to perform tension from the top of the liquid breakwater 2a via a tensile material described later, the tension work is performed after the concrete from the top of the liquid breakwater 2a reaches a predetermined strength.

  At the time of the tension work, as shown in FIG. 2B, the tension member 60 is inserted into the sheath tube 30 from the top of the liquid barrier 2a, and the lower end portion thereof is connected to the upper end portion of the tension member 13a within the hole portion 20. Connect at 70. As the tension member 60, a rod such as a tension rod or a PC steel material for tension work can be used.

  A tension device 50 for tensioning the tension member 60 is disposed on the top of the liquid barrier 2a. As the tensioning device 50, a center hole jack as shown in JP 2008-115575 A can be used.

  FIG. 3A is a diagram showing the hole 20 at this time, and in this embodiment, the fixing unit 131 includes a support plate 131a and a nut 131b. The upper end portion of the tension member 13a is disposed so as to protrude into the hole portion 20 through a hole (not shown) of the bearing plate 131a. A male screw is provided at the upper end of the tension member 13a, and a nut 131b is attached by screwing with the male screw.

  A male screw is also provided at the lower end portion of the tension member 60, and the lower end portion of the tension member 60 and the upper end portion of the tension member 13a are connected by a cylindrical connector 70 having an inner peripheral surface provided with a female screw. .

  When the tension member 60 is pulled by the tension device 50 as shown by the arrow A in FIG. 2B to tension the tension material 13a, the nut 131b is lifted as shown in FIG. 3B. Therefore, by rotating and tightening the nut 131b as shown by the arrow B, the nut 131b is brought into close contact with the bearing plate 131a as shown in FIG.

  When the tensile force by the tension device 50 is released, the upper end portion of the tension member 13a is fixed by the fixing unit 131. Therefore, the tension device 50, the tension material 60, and the connection tool 70 are removed, and the tension material 13a and the sheath tube 30 are removed. Fill the gaps between them with a filler.

  In addition, it is possible to perform fixing using a wedge (wedge) instead of the nut 131b as the fixing unit 131, but the fixing unit 131 may be slightly enlarged. Further, in this embodiment, after the tensioning work with the tension material 60 is finished and the tension material 60 is removed, the tension material 60 is diverted to tension another tension material 13a in the same manner as described above, and the tension material 13a is sequentially tensioned. Alternatively, a large number of tension members 60 may be used and a number of tension members 13a may be tensioned simultaneously. In any case, the tension work is no longer a critical work type and does not greatly affect the overall work schedule.

  After that, as shown in FIG. 2C, the tension material 11 is disposed in the corresponding sheath tube 30, the hole 20 is filled with the filler 201, and the sheath tube 30 that has passed through the tensile material 60 is also filled with the filler 301. And prestress is introduced into the breakwater 2a by tensioning the tension member 11. The gap between the tendon 11 and the sheath tube 30 is filled with a filler. The tensile material 60 may be left in the sheath tube 30 as it is without being removed, and the sheath tube 30 may be filled. It is also possible to use a tension material as the tension material 60 and thereby introduce a tension force to the upper portion 22 of the breakwater 2a.

  FIG. 3D shows the hole 20 at this time. Reference numeral 301 in FIG. 3D denotes a filler in the sheath tube 30. About the tension material 11 of the circumferential direction, the tension | tensile_strength and fixation of both ends are performed, for example by the pilaster (not shown) provided in the outer side surface of the liquid-breakwater 2a. In addition, about the above-mentioned long longitudinal tension material (not shown), since arrangement | positioning and tension | tensile_strength in a sheath pipe | tube (not shown) can be performed during construction of the breakwater 2a as usual, description is abbreviate | omitted here. did.

(3. Construction method of the breakwater 2a in the opening for construction)
The method of this embodiment is applicable also in the position corresponding to the construction opening part of the lower part 21 of the breakwater 2a.

  Also in this case, as shown in FIG. 4A, the breakwater 2a is formed up to the top with the construction opening 23 provided. Since the opening 23 for construction is used for carrying in materials and equipment, the sheath tube 30 and the like cannot be disposed during the construction of the internal equipment. Therefore, the sheath tube 30a is embedded in the bottom plate 5 and the concrete above the opening, avoiding the construction opening 23.

  In this embodiment, when closing the construction opening 23, the sheath tube 30b corresponding to the construction opening 23 is connected to the upper and lower sheath tubes 30a as shown in FIG. 4B. The tension member 13 a is disposed through the sheath tubes 30 a and 30 b, the lower end portion is attached to the fixing portion 131 in the bottom plate 5, and the upper end portion protrudes into the hole portion 20. A similar splicing process is also performed on the sheath tube through which the circumferential tendon 11 is passed.

  As shown in FIG. 5A, after the construction opening 23 is filled with a filler 202 such as concrete and strength is developed, the tension material 13a is tensioned and fixed in the same procedure as described above. Subsequent procedures are the same as described above. By performing tensioning, fixing, and the like of the tension member 11, the liquid breakwater 2a at the position corresponding to the construction opening 23 is constructed as shown in FIG. 5B. . In this case, even if it is the construction opening 23, the longitudinal tension member 13a does not need to be arranged up to the top as in the prior art, and its length is the same as that of the portion other than the construction opening 23, thus increasing the cost. Must not.

  As described above, according to the present embodiment, the tension member 13a having the upper end protruding from the hole 20 on the outer side surface of the liquid barrier 2a is provided above the hole 20 even after the liquid barrier 2a is formed. Since the tension can be tensioned by the tension member 60 passed through the sheath tube 30, it is not necessary to interrupt the construction of the liquid barrier 2a by the tensioning operation of the tension member 13a, and the entire construction period can be shortened. For example, in the case of a breakwater for a 200,000 KL class LNG tank, the construction of the breakwater is interrupted by tension work as in the conventional case, but it takes about 10.5 to 11 months to build the breakwater. Then, this can be shortened to about 1.5 to 2.0 months and to about 9 months.

  Further, in the present embodiment, as described above, it is not necessary to bend the tension member 13a and pull it out to the outer side surface and tension it from the outside, so that interference with the circumferential tension member 11 inside the breakwater 2a, reinforcing reinforcing bars, etc. It is hard to get up and is easy to design. Further, when the reinforcing reinforcing bars in the circumferential direction of the interference range are once cut, the range can be reduced.

  Moreover, in this embodiment, since the sheath pipe | tube 30 is utilized for letting the tension material 60 pass, the liquid-proof embankment 2a can be constructed | assembled efficiently. The sheath tube 30 extends upward from the hole portion 20 and is provided in the vertical direction up to the top of the liquid barrier 2a. By pulling the tension member 60 with the tension device 50 provided on the top, the tension work can be easily performed.

  Moreover, since the hole part 20 is provided in the outer side surface of the breakwater 2a, when tension | tensile_strength 13a is tension | tensile_strength, the tension | tensile_strength 60 and the tension | tensile_strength 13a connection and other operations can be performed from the outer side of the breakwater 2a. There is no interference with the internal facilities of the bank 2a. However, in some cases, it is possible to provide a similar hole on the inner side surface of the liquid breakwater 2a.

  In the present embodiment, the outer side surface of the lower portion 21 of the breakwater 2a is tapered outward with respect to the upper portion 22, and the tension material 13a is inclined substantially linearly along this inclination, The lower portion 21 of the liquid bank 2a is eccentric to the outside of the center in the thickness direction. Although this is effective as arrangement | positioning of the tension material 13a for making it resist the bending moment in an above described vertical surface, the shape of the lower part 21 and arrangement | positioning of the tension material 13a are not restricted to this. For example, the lower part 21 may be widened stepwise outward with respect to the upper part 22, or the lower part 21 may not be widened with respect to the upper part 22. Further, the tension material 13a is not limited to the one arranged eccentrically on the outside as described above.

  In addition, in this embodiment, although the lower end part of the tension material 13a was fixed in the bottom plate 5, for example, as shown in the liquid barrier 2b of FIG. 6A, the tension material 13a ′ is arranged in a substantially U shape, An example in which fixing in the bottom plate 5 is not performed is also conceivable. FIG. 6B is a view of the breakwater 2b from the inside, and the tension members 13a 'and the like are illustrated by dotted lines.

  In this case, both end portions of the tension member 13 a ′ protrude into the hole portion 20 and are fixed by the fixing portion 131, and the U-shaped folded portion 132 is embedded in the bottom plate 5. The tension material 13a 'may be simultaneously tensioned from both ends, but one end may be fixed to the fixing portion 131 of the hole 20 and only the other end may be tensioned to introduce prestress. Thereby, the tension work can be made efficient.

  In the present embodiment, as shown in FIG. 1B, the holes 20 are provided for each of the tension members 13a, and the holes 20 are arranged in a line in the circumferential direction of the liquid barrier 2a. It is not limited to. For example, when the tension members 13a are densely arranged and adjacent tension members 13a are close to each other, as shown in FIG. 7A, slits that are continuous in the circumferential direction of the breakwater (corresponding to the horizontal direction in the figure). A shaped hole 20a may be provided. Furthermore, when the fixing position of the upper end portion of the tension member 13a is a plurality of upper and lower stages, fixing holes 20 may be provided on the upper and lower stages as shown in FIG.

  In the present embodiment, an example of constructing the LNG tank breakwater 2a has been described. However, the present invention is not limited to this, and can be applied to a liquid breakwater of other tanks such as an LPG tank, In addition, a cylindrical wall body can be used other than the tank. Further, in this embodiment, the breakwater 2a is constructed by placing concrete on site, but the present invention can also be applied to the construction of a breakwater using precast blocks. In this case, necessary things such as a through hole and a hole 20 for passing the tension material 13a and the like are previously formed in the precast block.

  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 will be apparent to those skilled in the art that various changes or modifications can be conceived within the scope of the technical idea disclosed in the present application, and these are naturally within the technical scope of the present invention. Understood.

2, 2a, 2b; Breakwater 3a; Inner tub 3b; Outer tub 4; Pile 5; Bottom slab 7; Ground 11, 13, 13a, 13a ′; Tensile material 20, 20a; Portion 23; construction openings 30, 30a, 30b; sheath tube 50; tension device 60; tension member 70; connector 131; fixing portion 131a; bearing plate 131b; nut 201, 202, 301;

Claims (5)

A wall construction method for constructing a concrete cylindrical wall body in which prestress due to a longitudinal tension material is introduced in a lower part,
Forming a wall having a hole on a side surface and having a through hole extending upward from the hole, and projecting at least one end of the tendon into the hole (a);
(B) a step of tensioning the tension material by pulling the end portion with a tensile material passed through the through hole, and fixing the end portion in the hole portion;
Filling the hole with a filler (c);
Filling the through hole with a filler (d);
A wall construction method characterized by comprising: The through hole is provided in the vertical direction from the hole to the top of the wall,
2. The wall construction method according to claim 1, wherein in the step (b), the tension member is pulled by a tension device provided on a top of the wall.   3. The wall construction method according to claim 1, wherein, in the step (a), the hole is provided on an outer side surface of the wall. The tendon is arranged in a substantially U shape, and both end portions protrude into the hole on the side surface of the wall body,
The wall according to any one of claims 1 to 3, wherein, in the step (b), the other end is tensioned in a state where one end of the tendon is fixed to the hole. Body construction method. A concrete cylindrical wall body in which prestress due to a longitudinal tension material is introduced in the lower part,
Has a hole filled with filler on the side,
A through hole extending upward from the hole and filled with a filler is provided,
A wall body, wherein at least one end of the tendon is fixed in the hole.

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