JP5239634B2 - Construction method of underground tank structure - Google Patents

Description

  The present invention relates to a construction method of an underground tank structure in which a lower part for storing liquefied gas is buried in the ground.

  Conventionally, as a storage tank for liquefied gas such as LPG, LNG, etc., it consists of a bottom plate, a side wall constructed along the periphery of the bottom plate, and a roof part covering the upper part of the side wall, and at least the lower part is buried in the ground. An underground tank constructed like this is used. Such underground tanks build a cylindrical underground continuous wall in the ground, excavate the underground continuous wall, build a bottom slab inside the underground continuous wall, and place it on the inner periphery of the underground continuous wall. A side wall can be constructed so as to be along, and a roof portion can be connected to the upper part of the side wall.

Another method for constructing the roof of the underground tank is to construct a dome-shaped temporary roof made of steel on the bottom plate of the completed underground tank, and lift the temporary roof to correspond to the roof. A method of constructing a roof part by constructing a reinforced concrete structure so as to be integrated with the temporary roof on the temporary roof is known.
Furthermore, for example, Patent Document 1 describes a method of constructing a support work up to the height of the roof part on the bottom plate and performing the construction work of the roof part on the support work.
JP-A-7-34714

However, in the method using a temporary roof made of a steel material, a lift-up device for lifting the temporary roof is required, which increases the cost and requires time and labor for the lift-up operation. In addition, when the liquefied gas is stored inside, the temporary roof is exposed to a low temperature state, and therefore, the temporary roof is made of special steel material having low temperature toughness so that it can withstand even in a low temperature state, resulting in a high material cost. End up.
Moreover, in the method of patent document 1, since it is necessary to construct | assemble and remove a very large support work, it becomes high cost and a construction period will become long.

  This invention is made | formed in view of said problem, and it aims at reducing cost while reducing an effort at the time of constructing an underground tank structure.

  The construction method of the underground tank structure of the present invention is a reinforced concrete structure comprising a cylindrical side wall part, a bottom slab part connected to the lower part of the side wall part, and a roof part constructed on the upper side of the side wall part. Is an underground tank structure in which at least a side wall portion and a bottom plate portion are embedded in the ground, and at a height above the ground, a roof central portion excluding at least a part of a peripheral edge portion of the roof portion. A central construction step for construction, a subterranean wall construction step for constructing a cylindrical underground wall at a position corresponding to the outer periphery of the side wall, and an opening between the roof central portion and the underground wall in plan view And connecting the roof central portion and the top of the underground wall with the support member so that the roof central portion is supported via a support member, and the opening. Through the inside Or, an excavation step of excavating the inside of the underground wall by the carried excavator and discharging the excavated soil to the outside through the opening, and a bottom plate portion construction step of constructing the bottom plate portion at the bottom of the excavated hole And a side wall part construction step for constructing the side wall part so as to follow the inside of the excavated underground wall while lifting the material through the opening, and a reinforced concrete constituting at least a part of the edge part of the roof part. An edge construction step for construction.

  In the construction method of the above underground tank structure, the support member is made of reinforced concrete, and in the central part construction step, the support member is integrally projected with the roof central part so as to protrude from the roof central part toward the outer periphery. By constructing, in the connecting step, by constructing a frame-shaped part made of an annular reinforced concrete member at the upper part of the underground wall so that the end part of the support member protruding from the roof center part is integrated, You may connect the said roof center part and the top part of the said underground wall.

Further, the support member is made of a steel frame, and in the center part construction step, the roof center part is constructed so that the steel frame protrudes from the roof center part toward the outer periphery, and in the connection step, the roof part is By connecting the roof and the top of the underground wall by constructing a frame-shaped part made of an annular reinforced concrete member on the upper part of the underground wall so that the end of the protruding steel frame is embedded Also good.
In addition, a tensile member to which a tensile force is applied in the circumferential direction may be embedded in at least one of the frame-shaped portion and the peripheral portion of the roof central portion.

Moreover, you may perform the said center part construction step and the said underground wall construction step in parallel.
Further, the inner peripheral surface of the underground tank is subjected to cold insulation processing, and in the center construction step, after constructing the roof center, the suspension scaffold is suspended so as to be suspended on the constructed roof center. In parallel with at least one of the excavation step, the bottom plate portion building step, the side wall portion building step, and the edge portion building step, a cooling process is performed on the inner peripheral surface of the roof portion. Also good.

  According to the present invention, since the roof portion can be constructed on the ground, a large support work, a lift-up device, a temporary roof made of a special steel, and the like, which are conventionally necessary for constructing the roof portion, are unnecessary. Therefore, the cost can be reduced. In addition, support construction, dismantling work, and lift-up work are not required, and the construction work can be reduced.

Hereinafter, an embodiment of a construction method of an underground tank structure according to the present invention will be described in detail with reference to the drawings.
FIG. 1 is a vertical sectional view showing an underground tank structure 10 constructed by the construction method of this embodiment. As shown in the figure, the underground tank structure 10 is for storing a liquefied gas such as LPG or LNG. The underground continuous wall 30 formed in a cylindrical shape on the ground, and the underground continuous wall 30 An underground tank body 20 constructed so as to be integrated with the underground continuous wall 30 inside.

The underground tank body 20 is composed of a reinforced concrete bottom slab 22 constructed through a drained crushed stone layer at the bottom, and a reinforced concrete constructed integrally with the underground continuous wall 30 along the periphery of the bottom slab 22. It is comprised by the side wall part 21 and the roof part 23 of the reinforced concrete structure built on the dome integrally with the top part of the side wall part 21. FIG.
A cold insulating material and a membrane are attached to the inner peripheral surface of the underground tank body 20 so that the cold heat of the liquefied gas stored in the underground tank body 20 does not propagate to the outside.

  The underground continuous wall 30 includes a cylindrical underground wall main body 31 extending in the vertical direction and an annular frame-shaped portion 32 connected to the outside of the top of the underground wall main body 31. The underground continuous wall 30 is made of a reinforced concrete structure, and a PC steel cable is embedded in the frame-like portion 32 in a state where a tensile force is applied along the shape.

  Hereinafter, the construction method of the underground tank structure having such a configuration will be described with reference to FIGS. In each figure, (A) is a vertical sectional view, and (B) is a plan view. Since the underground tank structure of this embodiment has symmetry in the vertical section, each figure (A) shows a vertical section on the left side of the central axis, and (B) shows only a range of a central angle of 90 degrees.

  First, as shown in FIG. 2, at the position corresponding to the outer periphery of the side wall portion 21 of the underground tank main body 20, the upper end portion is equal to the lower end height of the frame-shaped portion 32, and the vertical streak protrudes from the upper end. The underground wall body 31 is constructed. In addition, the underground wall main body 31 can be constructed by excavating the ground, building a rebar cage in the excavation hole, and then placing concrete in the excavation hole.

  Moreover, as shown in the figure, in parallel with the construction work of the underground wall main body 31, the outer peripheral portion having a width of about 1 to 2 m was removed from the inner peripheral surface of the side wall portion 21 in the roof portion 23 of the underground tank main body 20. The support work 40 is constructed at a location corresponding to a portion (hereinafter referred to as a central portion). And on the support work 40, the reinforcement which comprises a center part is arranged, and the formwork 41 for placing the concrete which comprises a center part is installed.

  Next, as shown in FIG. 3, one end is located in the central portion at a position corresponding to the outer periphery of the central portion, and the other end reaches the upper portion of the underground wall body 31 (a position corresponding to the frame-shaped portion 32). A plurality of steel frames 50 are arranged as described above. As will be described later, these steel frames 50 can be used by heavy equipment for excavation between them, and can carry out excavated soil and materials for constructing the underground tank body 20. Place at intervals. Then, concrete is placed in the mold 41 so that the end on the central portion 23A side of the steel frame 50 is buried, thereby constructing the central portion 23A.

  In parallel with this, the reinforcing bar and the PC steel cable constituting the frame-like portion 32 are arranged on the upper part of the underground wall main body 31, and the concrete is placed, so that the end of the steel frame 50 is embedded, The frame-shaped part 32 is constructed so that the reinforcing bars protruding from the upper part of the underground wall main body 31 are embedded. Then, a tensile force is applied to the PC steel cable embedded in the concrete constituting the frame portion 32. Thereby, the underground continuous wall 30 is constructed.

  Next, the formwork 41 used when placing the concrete constituting the central portion 23A is removed, and the support work 40 is dismantled. Here, the load of the central portion 23 </ b> A of the roof portion 23 is transmitted to the frame-shaped portion 32 through the steel frame 50 by disassembling the support work 40. The frame-like portion 32 of the underground continuous wall 30 is subjected to a vertical load and a horizontal load spreading on the outer periphery via the steel frame 50 due to the load of the central portion 23A. Since a tensile force is applied to the PC steel cable embedded in the shaped portion 32, the horizontal load can be resisted.

  Then, as shown in FIG. 4, excavation work for the ground is performed below the central portion 23A. In the excavation work of the ground, as shown in the figure, several excavating heavy machines 71 such as backhoes enter the excavation hole 70 through the openings between the steel frames 50 or carry them in for excavation. The ground can be excavated by the heavy machinery 71, and the excavated soil can be discharged from the opening between the steel frames 50 by the earth and sand bucket 72.

  In parallel with the excavation work of the ground, on the suspension scaffold 60 suspended by the central part 23A of the roof part 23, the work of attaching the cold insulation material and the work of lining the membrane are performed on the lower surface of the roof part 23. In addition, the work on the lower surface of the roof part 23 is the construction work of the side wall part 21 and the bottom plate 22 of the underground tank, which will be described later, the work of attaching the cold insulation material on the side wall part 21 and the bottom plate 22 of the underground tank body 20, and the membrane lining. It may be performed in parallel with the work.

  Next, as shown in FIG. 5, a reinforced concrete bottom slab 22 is constructed at the bottom in the excavation hole 70 inside the underground continuous wall 30. At this time, materials for constructing the bottom plate 22 are carried from the openings between the steel frames 50.

  Next, as shown in FIG. 6, the side wall portion 21 of the underground tank body 20 is constructed integrally with the underground continuous wall 30 so as to follow the inner periphery of the underground continuous wall 30.

  Next, as shown in FIG. 7, the mold frame is installed at a position corresponding to the connection portion between the side wall portion 21 and the roof portion 23, the reinforcing bars are arranged in the mold frame, and then concrete is placed, The side wall portion 21 and the central portion 23A are connected. Thereby, the roof part 23 and the side wall part 21 are connected, and construction of the underground tank main body 20 is completed.

Next, the work for attaching the cold insulation material and the work for lining the membrane are performed on the side wall portion 21 of the underground tank body 20 and the inner peripheral surface of the bottom plate 22.
And the construction work of the underground tank structure 10 is completed by dismantling the suspension scaffold 60 suspended by the roof part 23.

  According to the present embodiment, since the central portion 23A of the roof portion 23 of the underground tank main body 20 can be constructed on the ground, a large support work conventionally required for constructing the roof portion 23 is required. And a lift-up device, a temporary roof made of special steel, and the like are unnecessary, so that the cost can be reduced. In addition, support construction, dismantling work, and lift-up work are not required, and the construction work can be reduced.

  Moreover, since the construction work of the roof part 23 and the construction work of the underground continuous wall 30 can be performed in parallel, workability can be improved.

  In addition, by attaching the suspension scaffold 60 to the roof portion 23, excavation work for the ground inside the underground continuous wall 30, work for attaching the cold insulation material for the side wall portion 21 and the bottom plate 22 of the underground tank body 20, and the membrane can be performed. In parallel with the lining work, the work for attaching the cold insulation material and the work for lining the membrane can be performed on the suspension scaffold 60, so that the construction period can be shortened.

  In the present embodiment, the central portion 23A of the roof portion 23 is supported by providing a steel frame so as to connect the central portion 23A of the roof portion 23 and the frame-shaped portion 32 of the underground continuous wall 30. However, the present invention is not limited to this, and the central portion 23A of the roof portion 23 may be supported by a reinforced concrete member or a steel concrete member formed in a rod shape.

  In addition, when it is set as the structure which supports the center part 23A of the roof part 23 by a reinforced concrete member or a steel concrete member, the steel frame 50 demonstrated with reference to FIG. 3 is arrange | positioned, and the center so that this steel frame 50 may be embedded. Instead of the step of constructing the portion 23A, a step of constructing a rod-shaped reinforced concrete member or a steel concrete member so as to protrude from the central portion 23A toward the outer periphery integrally with the central portion 23A is performed, and the end of the steel frame 50 is embedded Instead of the step of constructing the frame-like part 32 at the upper part of the underground structure main body 31, the rod-shaped reinforced concrete member or the steel concrete member protruding toward the outer periphery from the central part 23A is integrated. What is necessary is just to perform the process of constructing the frame-shaped part 32.

  Moreover, in this embodiment, although the PC steel cable which added the tensile force to the frame-shaped part 32 is embed | buried, not only this but a tensile force is cyclically formed along the peripheral part of the center part 23A of the roof part 23. The added PC steel cable may be buried. By embedding a PC steel cable with a tensile force applied to the peripheral edge of the central portion 23A, a load that spreads toward the outer periphery acts on the central portion 23A due to its own weight, but resists this load. be able to. Moreover, it is good also as embedding PC steel cable in the peripheral part of the frame-shaped part 32 and the center part 23A.

  Further, instead of embedding the PC steel cable in the frame-shaped portion 32, the opposing positions of the frame-shaped portion may be tied by a tie rod to which a tensile force is applied. Even with such a configuration, it is possible to resist a load that spreads toward the outer periphery that acts due to the weight of the central portion 23 </ b> A of the roof portion 23. Similarly, instead of embedding the PC steel cable in the peripheral portion of the central portion 23A, it may be connected by a tie rod to which a tensile force is applied so as to connect the opposing positions of the peripheral portion of the central portion 23A.

  In addition, after the underground tank body 20 is constructed, the upper portion of the roof portion 23 of the underground tank body 20 may be covered with a lightweight material such as polystyrene foam. In this case, a waterproof sheet or the like may be laid on the covered lightweight material.

It is a vertical sectional view showing the underground tank structure It is the figure (the 1) for demonstrating the construction method of an underground tank structure, (A) is a vertical sectional view, (B) is a top view. It is a figure (the 2) for demonstrating the construction method of an underground tank structure, (A) is a vertical sectional view, (B) is a top view. It is the figure (the 3) for demonstrating the construction method of an underground tank structure, (A) is a vertical sectional view, (B) is a top view. It is a figure (the 4) for demonstrating the construction method of an underground tank structure, (A) is a vertical sectional view, (B) is a top view. It is the figure (the 5) for demonstrating the construction method of an underground tank structure, (A) is a vertical sectional view, (B) is a top view. It is the figure (the 6) for demonstrating the construction method of an underground tank structure, (A) is a vertical sectional view, (B) is a top view.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Underground tank structure 20 Underground tank main body 21 Side wall part 22 Bottom plate 23 Roof part 23A Central part 30 Underground continuous wall 31 Underground wall main body 32 Frame-like part 40 Supporting work 41 Formwork 50 Steel frame 60 Scaffolding 70 Excavation hole 71 Heavy machine for excavation 72 earth and sand bucket

Claims (6)

A reinforced concrete underground tank comprising a side wall portion formed in a cylindrical shape, a bottom plate portion connected to a lower portion of the side wall portion, and a roof portion constructed on the upper portion of the side wall portion, and including at least the side wall portion and the bottom plate Is a method of constructing an underground tank structure with a part buried underground,
In the ground height, a center part construction step for constructing a roof center part excluding at least a part of a peripheral part of the roof part, and
An underground wall construction step of constructing a cylindrical underground wall at a position corresponding to the outer periphery of the side wall part,
The roof central portion and the underground wall so that an opening is formed between the roof central portion and the underground wall in a plan view and the roof central portion is supported via a support member. A connecting step of connecting the top of the support member with the support member;
An excavation step for excavating the inside of the underground wall by an excavator that has entered or is carried through the opening and discharging the excavated soil to the outside through the opening;
A bottom plate portion building step for building the bottom plate portion at the bottom of the excavated hole;
A side wall construction step for constructing the side wall so as to follow the inside of the excavated underground wall while lifting the material through the opening;
An edge construction step of constructing reinforced concrete that constitutes at least a part of the edge of the roof, and a construction method for an underground tank structure. A construction method of an underground tank structure according to claim 1,
The support member is made of reinforced concrete,
In the center part construction step, the support member is constructed so as to protrude from the roof center part toward the outer periphery, integrally with the roof center part,
In the connecting step, the roof center is constructed by constructing a frame-shaped portion made of an annular reinforced concrete member at the upper part of the underground wall so that ends of the support members protruding from the roof central portion are integrated. The construction method of the underground tank structure characterized by connecting a part and the top part of the underground wall. A construction method of an underground tank structure according to claim 1,
The support member is made of steel,
In the central part construction step, the central part of the roof is constructed so that the steel frame protrudes toward the outer periphery from the central part of the roof,
In the connecting step, by constructing a frame-shaped portion made of an annular reinforced concrete member at the upper part of the underground wall so that an end of a steel frame protruding from the roof central portion is embedded, the roof central portion and A method for constructing an underground tank structure characterized by connecting the top of the underground wall. A construction method for an underground tank structure according to claim 2 or 3,
A construction method of an underground tank structure, wherein a tensile member to which a tensile force is applied in a circumferential direction is embedded in at least one of the frame-shaped part and the peripheral part of the roof central part. A construction method of an underground tank structure according to any one of claims 1 to 4,
The construction method of the underground tank structure characterized by performing the said center part construction step and the said underground wall construction step in parallel. A construction method of an underground tank structure according to any one of claims 1 to 4,
The inner peripheral surface of the underground tank is subjected to a cold insulation process,
In the central part construction step, after constructing the roof central part, a suspension scaffold is provided to be suspended in the constructed roof central part,
In parallel with at least any one of the excavation step, the bottom slab portion building step, the side wall portion building step, and the edge portion building step, a cooling process is performed on the inner peripheral surface of the roof portion. To build underground tank structure.

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