JP2019085759A - Concrete structure - Google Patents

Abstract

To provide a concrete structure capable of reducing cost.SOLUTION: A haunch 6a is provided at a corner portion between a bottom slab 5 and a side wall 7 of a tank skeleton of an underground tank. The haunch 6a is provided so as to extend along a circumferential direction of the tank. Vertical slits 60 are provided in the haunch 6a with a predetermined interval in the circumferential direction of the tank, and the haunch is divided in the circumferential direction of the tank by the slits 60. Plate-shaped slit materials 61 are inserted into the slits 60, and the slit materials 61 are attached to plate-shaped embedded forms 62 in installation.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a concrete structure having a haunch.

  There is an underground tank as a facility for storing low temperature liquefied gas such as LNG (liquefied natural gas) and LPG (liquefied petroleum gas). In recent years, the underground tank excavates the inside of the underground continuous wall which is a mountain ridge, and then, as shown in FIG. 9, constructs a tank body consisting of a reinforced concrete bottom plate 5 and a side wall 7 inside the underground continuous wall 9 It is common to provide a steel roof 8 thereon. Although illustration is omitted, a membrane is provided on the inner surface of the tank housing via a heat insulating material. Further, below the bottom plate 5, a water collecting layer 4 made of crushed stone or the like is provided.

  Although the bottom plate 5 and the side wall 7 may perform pin connection or slide connection, recently, the bottom plate 5 and the side wall 7 are often connected integrally to form a rigid connection. This is due to the advantages of a water stop and the elimination of the bearing structure between the bottom plate 5 and the side wall 7. In the case of such a construction type, it is general to provide a hunting 6 at the corner portion of the bottom plate 5 and the side wall 7.

  The concrete of the hunt 6 is cast integrally with the lower portion of the side wall 7 after the concrete placing of the bottom plate 5. The hunt 6 is extended along the inner surface of the side wall 7 so as to be continuous in the circumferential direction of the tank. In the hunt 6, reinforcing bars (not shown) in the circumferential direction of the tank are also embedded.

  The purpose of providing the hunches 6 is to reduce the bending moment and shear force of the bottom plate 5 by reducing the span of the bottom plate 5 and minimize the thickness of the bottom plate 5 to reduce the amount of reinforcement of the bottom plate 5. In addition, when the thickness of the lower portion of the side wall is increased by the hunting 6, it is possible to resist the bending moment and the shear force in the vertical plane generated in the lower portion of the side wall.

  The size of the hunt 6 is determined by the thickness of the bottom plate 5 and the side wall 7 but in the case of a rigid connection type underground tank with a capacity of 200,000 KL, the height and the tank radial direction (left and right direction of FIG. Length of about 3 m is relatively large.

JP 2001-073396 A

  Concrete in the lower side wall of the side wall (the connection portion between the side wall and the bottom plate) including the haunch has a problem that a crack is generated due to a temperature decrease, and it requires a large cost to prevent this.

  For example, although the concrete at the time of placing is set to a high temperature due to the heat of hardening (heat of hydration), the temperature is then lowered to a normal temperature. Since the concrete at the lower portion of the side wall is integrated with the bottom plate, a tensile force is generated along with the temperature contraction in the tank circumferential direction when the temperature of the concrete decreases, and a crack in the vertical direction is generated. The concrete in the lower part of the side wall is a mass concrete with a thickness of 5 m or more including a hunt, and such a crack is likely to occur. For this reason, it is necessary to take cost-intensive measures such as devising concrete materials, reducing the temperature of concrete at the time of placing, and reinforcing bars for suppressing the crack width.

  In addition, when the tank is in operation, the temperature of the inner surface of the tank body is greatly reduced from normal temperature by the low temperature liquefied gas. Even when the temperature decreases in this manner, as in the above, cracks tend to occur in the concrete at the lower portion of the side wall including the hanch. Therefore, by arranging a large number of reinforcing bars in the tank circumferential direction, it is necessary to take measures such as setting the maximum value of the crack width to the allowable value or less. Further, if a large hunt is provided, the total thickness of the side wall and the hunt will be increased, and the tensile force in the circumferential direction of the tank will increase, so a large amount of reinforcing bars will be required.

  This invention is made in view of the said problem, and it aims at providing the concrete structure which can reduce cost.

  The present invention for solving the above-mentioned problems is a concrete structure including a cylindrical structure, and a hanch is extended so as to extend along the inner surface of the cylindrical structure, and the hanch is formed by a slit. It is a concrete structure characterized by being divided in the extension direction of the above-mentioned hunt.

  In the present invention, in the hunt provided so as to extend along the inner surface of the tubular structure, by providing the slit for dividing the hunt in the extending direction, the tubular structure including the hunt with the temperature decrease. The tensile force generated on the wall is reduced. Therefore, the cost can be reduced, for example, the amount of reinforcing bars can be reduced.

For example, the concrete structure includes the cylindrical structure and a lid-like structure closing the inside of the cylindrical structure, and the hunt is at a corner portion of the cylindrical structure and the lid-like structure. And extending so as to extend in the circumferential direction of the cylindrical structure, and the slits divide the hunt in the circumferential direction of the cylindrical structure.
As described above, in the hanch provided in the circumferential direction of the cylindrical structure at the corner portion of the cylindrical structure and the lid structure, the slits for dividing the hanch in the circumferential direction are provided, thereby reducing the temperature. The tensile force generated at the connecting portion of the tubular structure including the haunch with the lid structure is reduced, and the cost can be reduced.

The cylindrical structure is, for example, a side wall of a housing of an underground tank, and the lid-like structure is a bottom plate rigidly connected to the side wall.
INDUSTRIAL APPLICABILITY The present invention can be suitably applied to an underground tank of a rigid connection type in which a crack caused by a decrease in temperature is particularly a problem by providing the above-mentioned slitted hunting at the corner portion of the bottom plate and the side wall.

Alternatively, the cylindrical structure has a substantially polygonal inner surface, and the hunt is extended at the corner portion of the inner surface so as to extend in the axial direction of the cylindrical structure, and the slit is the hunt Are divided in the axial direction of the tubular structure.
As described above, in the hunt provided in the axial direction of the tubular structure at the corner portion of the inner surface of the polygonal tubular structure such as the box culvert, the temperature can also be provided by providing the slit for dividing the hunt in the axial direction. The reduction in tension reduces the tensile force generated at the member connection portion including the hunting, which can reduce the cost.

Preferably, a slit material is disposed in the slit.
In the present invention, the slit can be suitably formed by the slit material at the time of concrete placement, and the slit can be secured by the slit material after the concrete placement.

It is desirable that the slit material be attached to the embedded mold and disposed. Alternatively, the slit material may be attached to a rebar in the surface direction of the slit material embedded in the hunt.
By attaching the slit material to reinforcing bars in the surface direction of the embedded mold or the slit material, it is possible to prevent the slit material from being deformed during concrete placement.

  The present invention can provide a concrete structure whose cost can be reduced.

The figure which shows the underground tank 1. FIG. The figure which shows the inside of a tank housing. FIG. The figure which shows the construction method of hunches 6a. The figure which shows temperature distribution A of the lower part of a side wall. The figure which shows the inside of a tank housing. FIG. Figure showing box culvert 10; Figure showing the underground tank.

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

First Embodiment
FIG. 1 is a view showing an underground tank 1 which is a concrete structure according to a first embodiment of the present invention. The underground tank 1 is provided on the ground, and stores (extremely) low temperature liquefied gas (low temperature liquid) such as LNG or LPG as a reservoir in the tank.

  The underground tank 1 excavates the inside of the underground continuous wall 9 which is a mountain stay as in the example of FIG. 9, and then constructs a tank body by the reinforced concrete bottom plate 5 and the side wall 7 inside the underground continuous wall 9 , A steel roof 8 is provided on it. Although not particularly illustrated, the inner surface of the tank housing is provided with a heat insulating material, and a membrane is also provided inside thereof. The term "inside" refers to the side closer to the center of the tank housing, and the term "outside" refers to the opposite side.

  The side wall 7 is a cylindrical structure formed on the bottom plate 5 and is provided in a cylindrical shape so as to surround the inside of the tank. The bottom plate 5 is a lid-like structure provided to close the inside. The bottom plate 5 and the side wall 7 are formed of cast-in-place concrete and integrated (rigidly bonded). The underground continuous wall 9 is cylindrically provided in the ground outside the side wall 7. Below the bottom plate 5, a water collecting layer 4 of crushed stone or the like is also provided.

  Inside the side wall 7, a hunting 6 a is provided at the corner portion of the side wall 7 and the bottom plate 5. The hunting 6a is a widening portion at the lower part of the side wall 7, and is formed to be inclined so as to expand inward as it goes down. The hunting 6 a is provided integrally with the side wall 7 and the bottom plate 5. The dimensions of the hunting 6a are the same as those of the conventional underground tank, and for example, the length and the length of the tank radial direction (corresponding to the left and right direction in FIG. 1) are 3 m. The length is about the same as the thickness of the side wall 7.

  As shown in FIG. 2, the hunt 6a is extended on the inner surface of the side wall 7 so as to extend along the tank circumferential direction, but the hunt 6a is provided with slits 60 at predetermined intervals in the tank circumferential direction. It is divided by the slit 60 in the tank circumferential direction (the extending direction of the hunting 6a). The above-mentioned interval is, for example, an interval of 2 to 3 m, which is equal to or less than the dimension of the above-mentioned height and length of the hunt 6a. The slits 60 are provided in the vertical direction, and are orthogonal to the inner surface of the side wall 7 and the upper surface of the bottom plate 5. The width of the slits 60 is smaller than the above interval, for example, about 10 to 20 mm.

  A plate-like slit member 61 is disposed in the slit 60, and the slit 60 is filled with the slit member 61. The material of the slit member 61 is not particularly limited, but in addition to a wood board such as plywood, an elastic body such as a hard rubber board or polyurethane foam can be used.

  The slit member 61 is attached to and installed in a plate-like embedded mold 62. The buried formwork 62 is a buried formwork at the time of putting concrete of the hunt 6a, and is disposed in the vertical direction. The material of the buried form 62 is not particularly limited, and, for example, a concrete plate or the like can be used.

  Fig.3 (a) is a figure which shows the cross section of the tank radial direction of the slit material 61 (slit 60), and FIG.3 (b) is a cross section along line aa of FIG. 3 (a). As shown in the figure, reinforcing bars 63 in the circumferential direction of the tank (corresponding to the left and right direction in FIG. 3B) are embedded in the hunting 6a, and the reinforcing bars 63 penetrate the slit material 61 and the embedding form 62 ing.

  At the time of formation of the hunches 6a, as shown in FIG. 4A, the slit material 61 is attached to the embedded mold 62 by attaching or the like, and the reinforcing members 63 in the tank circumferential direction are holes of the slit material 61 and the embedded mold 62 After penetrating and arranging the reinforcement, concrete as shown in FIG. 4 (b) is punched with concrete of the hunt 6a (and the lower part of the side wall 7).

  As described above, in the present embodiment, in the hunches 6a provided in the circumferential direction of the tank at the corner portions of the side wall 7 and the bottom plate 5, the concrete is cut by providing the slits 60 for dividing the hunches 6a in the circumferential direction. The thermal contraction due to the temperature drop after installation is absorbed by the opening of the slit 60, and the tensile force generated in the lower side wall (the connecting portion between the side wall 7 and the bottom plate 5) including the hunt 6a is reduced.

  Providing the slits 60 is also effective against temperature drop during tank operation. Fig. 5 shows an example of the temperature distribution at the bottom of the side wall including the hunt at the time of tank operation. In Figs. 5 (a) and 5 (b), the horizontal axis represents the distance from the tank inner surface (inner surface of the membrane), and the vertical axis The temperature distribution A of concrete on the lower side wall at the time of tank operation is shown as temperature.

  When the hunt 6 is continuous as shown in FIG. 9, the width of the lower part of the side wall including the decrease width from the initial temperature B (16 ° C. in the example of the figure) of the tank housing at the construction time 5A, a tensile force proportional to the area shown in the shaded portion D1 of FIG. 5A is applied to the lower portion of the side wall, but in the present embodiment, the tensile force of the lower portion of the side wall at the slit 60 is equal to that of FIG. The value is proportional to the area shown in the shaded portion D2, and the tensile force is greatly reduced. Also, as described above, temperature contraction can be absorbed by the opening of the slit 60.

  Since the reinforcing bars of the hanch 6a should be width retaining bars considering only the prevention of cracking of concrete between the slits 60, the diameter of the reinforcing bars can be reduced and the number of reinforcing bars can be reduced. As a result, the entire lower side wall As a result, the amount of rebars can be reduced to reduce costs.

  On the other hand, since the huntings 6a are provided in the vertical direction at the corner portions of the bottom plate 5 and the side wall 7 at locations other than the slits 60, it is possible to secure the merit that the span of the bottom plate 5 can be reduced by the huntings 6a. In addition, the hunches 6a effectively act on the bending moment and the shear force in the vertical plane at the lower portion of the side wall, so that the degree of stress of the reinforcing bar and the concrete can be relaxed as in the conventional case.

  Further, in the present embodiment, the slit 60 can be suitably formed by the slit member 61 at the time of concrete placement, and the slit 60 can be secured by the slit member 61 after the concrete placement. By attaching the slit member 61 to the embedding form 62, it is possible to prevent the slit member 61 from being deformed during concrete placement.

  However, the present invention is not limited to this. For example, the present embodiment is an example of a rigid connection type underground tank, which makes it possible to reduce the amount of reinforcement in the lower portion of the side wall including the hunches 6a of the tank body and to reduce the cost. If it is a lid-like structure which closes a cylindrical structure and its inner part, it is applicable to the corner part similarly. The dimensions of the hunting 6a and the width of the slit 60 are not particularly limited. In the present embodiment, the height and the length of the hunting 6a have the same dimensions, but the invention is not limited thereto, and similar effects can be obtained even if they have different dimensions. The same applies to the embodiments described later.

  In addition, the reinforcing bars 63 in the tank circumferential direction may not penetrate through the slits 60, and are somewhat more effective than the case of penetration in terms of reducing the tensile force at the lower portion of the side wall. In the case where the reinforcing bar 63 penetrates the slit 60 as in the present embodiment, the tension accompanying the opening of the slit 60 acts on the reinforcing bar 63 at the position of the slit 60 but the opening is not so large (1 There is no worry about breakage of the rebar 63 because it is about 2 mm).

  Hereinafter, another example of the present invention will be described as second and third embodiments. In the second and third embodiments, configurations different from the first embodiment will be mainly described, and the same configurations will be denoted by the same reference numerals in the drawings and the like, and the description will be omitted.

Second Embodiment
FIG. 6 is a view showing a tank body of an underground tank which is a concrete structure according to a second embodiment, similarly to FIG. As shown in FIG. 6, the present embodiment is different from the first embodiment in that the embedded mold 62 is not disposed in the hunting 6b.

  Fig.7 (a) is a figure which shows the cross section of the tank radial direction of the slit material 61 (slit 60), FIG.7 (b) is a cross section along line b-b of Fig.7 (a). As shown in the figure, a buttocks reinforcing bar 64 is disposed on one side of the slit member 61, and the slit member 61 is attached to the buttocks reinforcing bar 64 and installed. The buttocks reinforcing bars 64 are embedded in the concrete of the hanch 6 b along the surface direction of the slit member 61. The buttocks reinforcing bars 64 protrude inside the side walls 7 and the bottom plate 5, and a part is continuous with the reinforcing bars (not shown) in the side walls 7 and the bottom plate 5. In addition, such a buttocks rebar 64 is also embedded in the concrete between the slits 60 in the hunting 6a of the first embodiment.

  Reinforcing bars 65 in the circumferential direction of the tank (corresponding to the left and right direction in FIG. 7B) are embedded in the hunting 6b, but the reinforcing bars 65 are cut on both sides of the slit material 61 and the slit material 61 (slit 60) It is discontinuous without penetrating. However, the reinforcing bars 65 may penetrate the slit material 61. The method of forming the hunting 6b is substantially the same as that of the first embodiment except that the slit member 61 is attached to the buttocks rebar 64.

  Also in the present embodiment, as in the first embodiment, by providing the slit 60 for dividing the hunt 6a in the circumferential direction of the tank, the tensile force applied to the lower portion of the side wall decreases as the temperature decreases, thereby reducing the rebar amount. The cost can be reduced. By attaching the slit member 61 to the buttocks reinforcing bar 64, it is possible to prevent the slit member 61 from being deformed during concrete placement.

Third Embodiment
FIG. 8 is a view showing a box culvert 10 which is a concrete structure according to a third embodiment of the present invention. The box culvert 10 is a reinforced concrete cylindrical structure having a bottom plate 15, side walls 17 and a top plate 18, and the inner surface is substantially square. Bottom plate 15, side wall 17 and top plate 18 are formed of cast-in-place concrete and integrated (rigidly bonded).

  In the present embodiment, on the inner surface of the box culvert 10, the huntings 16 are provided at the corners of the bottom plate 15 and both side walls 17 and at the corners of the both side walls 17 and top plate 18. The hunting 16 is integrally formed with the bottom plate 15, the side wall 17 and the top plate 18. The dimensions of the hunches 16 are smaller than that of the above-mentioned underground tank, the height is 1 m, and the horizontal length orthogonal to the axial direction of the box culvert 10 is about 1 m.

  The hunches 16 extend on the inner surface of the box culvert 10 so as to extend along the axial direction of the box culvert 10, but are axially divided by the slits 60 similar to the first and second embodiments. The distance between the slits 60 is, for example, 1 m or less, and the height and the length described above. The slit member 61 is disposed in the slit 60.

  Also in this embodiment, by providing the slit 60 for dividing the hunt 6b in the axial direction of the box culvert 10, the connecting portion of the bottom plate 15 and the side wall 17 including the hunt 6b with the temperature decrease after casting concrete, and the side wall The tensile force in the axial direction of the box culvert 10 generated at the connection portion between the top plate 17 and the top plate 18 is reduced, and the amount of reinforcing bars can be reduced, thereby reducing the cost.

  In the present embodiment, the slit member 61 is attached to the embedded mold 62, but the embedded mold 62 is omitted and the slit member 61 is attached to the reinforcing bar 64 in the hutch 16 as in the second embodiment. It may be arranged. In addition, the cut-off hutch 16 according to the present embodiment is not limited to the box culvert 10 whose inner surface is substantially square, but may be provided at the corner portion as long as the inner surface is a substantially polygonal tubular structure.

  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.

1: underground tank 4: water collecting layer 5, 15: bottom plate 6, 6a, 6b, 16: hunt 7, 17: side wall 8: steel roof 9: underground continuous wall 10: box culvert 18: top plate 60: slit 61: Slit material 62: Buried formwork 63, 65: Rebar 64: Rebar part rebar

Claims (7)

A concrete structure including a tubular structure,
A hunting is extended to extend along the inner surface of the tubular structure,
The concrete structure characterized in that the hunt is divided in the extending direction of the hunt by a slit. The concrete structure includes the cylindrical structure and a lid-like structure that closes the inside of the cylindrical structure.
The hunting is extended so as to extend in the circumferential direction of the cylindrical structure at a corner portion of the cylindrical structure and the lid structure.
The concrete structure according to claim 1, wherein the slit divides the hunt in the circumferential direction of the cylindrical structure. The cylindrical structure is a side wall of the underground tank housing,
The concrete structure according to claim 2, wherein the lid-like structure is a bottom plate rigidly connected to the side wall. The cylindrical structure has a substantially polygonal inner surface,
The hunting is extended so as to extend in the axial direction of the cylindrical structure at a corner portion of the inner surface,
The concrete structure according to claim 1, wherein the slit divides the hunt in the axial direction of the cylindrical structure.   The concrete structure according to any one of claims 1 to 4, wherein a slit material is disposed in the slit.   The concrete structure according to claim 5, wherein the slit material is attached to and disposed in a buried form.   The concrete structure according to claim 5, characterized in that the slit material is attached to a reinforcing bar in a surface direction of the slit material embedded in the hunt.

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