JP5088466B2 - Concrete roof construction method - Google Patents

Description

  The present invention mainly relates to a method for constructing a concrete roof in an LNG storage tank.

  LNG (liquefied natural gas) is shifting its position from an energy source that complements oil to a major energy source that replaces oil, and along with that, tanks that store LNG have become larger every year, with an inner diameter exceeding 50 m. It has become.

  Therefore, how to construct a dome-shaped roof having a huge diameter as well as the construction of a tank bottom plate and a cylindrical side wall becomes important in order to make the construction of the LNG storage tank more efficient.

  Under such circumstances, as a method for constructing the roof of the LNG tank, a so-called air raising method for raising the roof frame with air pressure is widely adopted.

  To construct a roof using the air-raising method, first lay a roof frame with a steel liner plate affixed to the frame on the bottom slab concrete, and then raise the ground frame by air pressure Then, the peripheral edge of the roof frame is fixed to the top of the side wall and reinforcement is provided on the roof, and then concrete is placed on the liner plate while keeping the air pressure inside the tank high.

  When placing concrete, the liner plate serves as a dam plate for placing concrete on the outside, and the air pressure inside the tank supports vertical loads due to the weight of concrete that has not yet solidified (fresh concrete). Play a role of supporting work.

JP-A 64-10840 JP-A-5-33523

  Here, in the above-described construction method, it takes several weeks until the strength of the concrete is developed, so it is necessary to maintain the air pressure in the tank supporting the vertical load of the fresh concrete.

  Therefore, until several weeks have passed since the concrete was placed, it became difficult for workers to go in and out of the tank and to carry materials in and out, which caused the air pressure inside the tank to drop, and it was necessary to interrupt the construction inside the tank. Is done.

  In order to solve such a problem, an airtight bag body composed of an upper film and a lower film is attached to the top of the side wall, and air is pressed into the airtight bag body, and concrete is placed on the upper film in such a state. (Patent Documents 1 and 2), and according to such a construction method, it is not necessary to make the entire space in the tank high in pressure, and the construction inside the tank is performed in parallel during the curing period of roof concrete. Can proceed.

  However, in this construction method, the lower film hangs down due to the air pressure and the trouble of lifting the material using a crane, etc. There has been a problem that the airtightness of the bag cannot be maintained due to excessive sag. Such a problem becomes more prominent in an LNG tank having an inner diameter of more than 50 m.

  Incidentally, in Patent Document 2, it is disclosed that the hanging rope 2b is stretched under the lower membrane 4 to prevent the lower membrane from drooping. However, after the roof concrete work is completed, the lower membrane is removed and Both of the ropes must be removed.

  Moreover, even if the attachment part of the lower film periphery and the side wall top part is comprised so that attachment or detachment is possible (refer to the chuck | zipper part 9 of FIG. 9 of patent document 2, paragraph number 9 and FIG. 3), the circular sheet-like lower film exceeding 50 m in diameter is formed. The removal is expected to be quite difficult, and construction inside the tank must be temporarily suspended.

  The present invention has been made in consideration of the above-described circumstances, and in the construction method for supporting the load at the time of placing the concrete constituting the roof by air pressure, the work in the tank is performed while ensuring a wide internal work space in the tank. It aims at providing the construction method of the concrete roof which can be performed continuously.

In order to achieve the above object, a concrete roof construction method according to the present invention includes a dome-like shape at the top of a cylindrical side wall erected on the bottom plate so as to surround the upper space of the bottom plate. In the construction method of the concrete roof where the roof frame of the building
The roof frame is assembled so that the roof frame is composed of a frame and a roof base material affixed to the frame, and a suspension rod is suspended from the frame, and a membrane material is provided at the lower end of the suspension rod. Attaching, spanning the roof frame to the top of the side wall, closing the gap between the peripheral edge of the membrane material and the inner peripheral surface of the side wall with an airtight plate and making the roof base material and the top of the side wall airtight, Air is pressed into an airtight space surrounded by the roof base material, the side wall, the membrane material and the airtight plate, and then concrete is placed on the barrier plate using the roof base material as a barrier plate.

  In the concrete roof construction method according to the present invention, the roof frame, the suspension rod and the membrane material are pre-assembled on the bottom plate, and the roof frame is raised together with the suspension rod and the membrane material. Then, the roof frame is fixed to the top of the side wall at the periphery thereof, and then the airtight plate is installed and the air pressure is pressed.

Moreover, the construction method of the concrete roof which concerns on this invention performs the said raise process by an air pressure.
In the concrete roof construction method according to the present invention, the bottom plate, the side wall, the roof frame, the suspension rod, and the membrane material are respectively provided on the bottom plate of the LNG tank, and the side wall provided in the vicinity of the periphery of the bottom plate. A roof frame composed of a frame and a roof base material spanned on the top of the side wall, a suspension rod suspended from the frame, and a deck suspended by the suspension rod and provided with a heat insulating material. .

  In the method for constructing a concrete roof according to the present invention, as in the past, a dome-shaped roof frame is bridged on the top of a cylindrical side wall erected on the bottom slab so as to surround the upper space of the bottom slab. Although concrete work is performed, in the present invention, the roof frame is assembled so that the roof frame is composed of a frame and a roof base material affixed to the frame, and a suspension rod is suspended from the frame. A membrane material is attached to the lower end of the suspension rod.

  And after spanning this roof frame over the top part of a side wall, while sealing between the periphery of a film | membrane material and the inner peripheral surface of a side wall with an airtight board, a roof base material and the top part of the said side wall are made airtight.

  Next, air is pressed into an airtight space surrounded by the roof base material, the side wall, the membrane material, and the airtight plate.

  In this way, the pressed-in air tries to push the roof base material upward and the membrane material downward, but the membrane material is suspended from the framework via the suspension rod. The hanging rod is prevented from drooping in such a way that the suspension rod bears the tensile force.

  When the air pressure is injected, concrete is placed on the dam plate using the roof base material as the dam plate.

  Here, the vertical load of the placed fresh concrete is supported by the air pressure in the airtight space described above. Therefore, the membrane material does not hang down between the membrane material and the bottom plate, and a state in which a large internal work space is secured is maintained, and even during the concrete curing period, the tank in the internal work space is maintained. Internal work can be advanced.

  The roof frame consisting of the frame and the roof base material affixed to the frame shall be assembled together with the suspension rod and membrane material before it is transferred to the top of the side wall, but where it is assembled is arbitrary. A roof frame may be assembled adjacent to a construction planned area of a building to which the present invention is applied, for example, an LNG tank, and the roof frame may be lifted by a large crane and suspended on the top of the side wall.

  Here, the roof frame, the suspension rod and the membrane material are pre-assembled on the bottom plate, the roof frame is raised together with the suspension rod and the membrane material, and then the roof frame is fixed to the top of the side wall at the periphery. After that, if an airtight plate is installed and air pressure is pressed, it is not necessary to secure a separate assembly yard for the roof frame.

  The method of raising the roof frame is arbitrary. For example, a number of PC steel bars are erected along the periphery of the roof frame, and the same number of center hole jacks are fixed along the top of the side wall. Although the method of lifting the roof frame can be adopted by inserting the PC steel rods respectively in this way, it is not necessary to install a lifting mechanism if the lifting process is performed pneumatically.

  Embodiments of a concrete roof construction method according to the present invention will be described below with reference to the accompanying drawings. Note that components that are substantially the same as those of the prior art are assigned the same reference numerals, and descriptions thereof are omitted.

  FIG. 1 is a view showing an LNG tank including a concrete roof to be constructed in the concrete roof construction method according to the present embodiment.

  As shown in the figure, the LNG tank 1 is a so-called PCLNG ground storage tank. The LNG tank 1 has a substantially circular bottom plate 3 made of reinforced concrete supported by a pile 2 and an internal space 4 extending above the bottom plate. A cylindrical side wall 5 serving as a PC liquid barrier made of prestressed concrete (hereinafter referred to as PC) standing in the vicinity of the periphery of the bottom plate 3 so as to surround the circular dome-shaped concrete roof spanning the top of the side wall 6, and a tank body (not shown) is installed inside the bottom plate 3, the side wall 5, and the concrete roof 6 via a predetermined cold insulation member.

  Here, a deck 8 as a membrane material is suspended from the concrete roof 6 via a suspension rod 7, and glass wool 9, which is one of the cold insulation members, is laid on the deck.

  Prior to the construction of the concrete roof 6 according to the present embodiment, the pile 2 is first constructed as shown in FIG. 2, and then the bottom plate 3 is constructed of reinforced concrete on the head of the pile, and the upper side of the bottom plate 3 A side wall 5 is erected as a PC structure in the vicinity of the periphery of the bottom plate 3 so as to surround the internal space 4 that extends to the bottom.

  Next, as shown in FIG. 3, the roof frame 11 is assembled on the bottom plate 3, the suspension rod 7 is suspended from the roof frame, and the deck 8 is attached to the lower end of the suspension rod.

  The roof frame 11 is composed of a steel frame assembled in a circular dome shape and a roof base material consisting of a steel plate affixed to the upper surface of the frame, and the suspension rod 7 described above is suspended from the frame. You should just make it.

  The deck 8 is a circular deck having an outer diameter that is smaller than the inner diameter of the side wall 5 by a predetermined length so that there is no interference with the side wall 5 when performing the air lathing method described later, and a plurality of steel plates are joined in an airtight manner. You can assemble it into a floor.

  When the roof frame 11 is grounded and the suspension rod 7 is suspended from the roof frame and the deck 8 is attached to the lower end thereof, the periphery of the roof base material 63 constituting the roof frame 11 as shown in FIG. At the same time, the base end of the airtight seal 61 is attached, and the front edge of the airtight seal is brought into contact with the inner peripheral surface of the side wall 5 in a tongue shape.

  Next, the airtight seal 61 maintains the airtightness between the roof base material 63 and the side wall 5, and sends air into the internal space 4 to increase the air pressure in the internal space, as shown in FIG. 5. The frame 11 is raised together with the suspension rod 7 and the deck 8. In order to send air into the internal space 4, for example, a temporary sleeve may be provided on the side wall 5 and a blower may be connected to the outside of the sleeve, but from FIG. It is omitted.

  When the roof frame 11 is raised to a predetermined height, as shown in FIGS. 4 and 6, the end of the frame 62 constituting the roof frame 11 is embedded in a ring beam 5 a formed on the top of the side wall 5 in advance. The attached body 64 is joined.

  In order to join the frame 62 and the mounting body 64 to each other, the long hole 67 drilled in the frame 62 and the long hole 65 bonded to the mounting body 64 are aligned, and then the bolts are fixed to the long holes 65 and 67. May be inserted and fastened with a nut 68.

  Further, in order to ensure the airtightness between the roof base material 63 and the side wall 5, welding 69 is applied between the edge of the annular mounting angle 66 embedded in the ring beam 5 a in advance and the roof base material 63. The airtight seal 61 is removed as appropriate at an appropriate time.

  Next, the airtight plate 82 is bridged between the annular locking groove 81 embedded in advance on the inner peripheral surface of the side wall 5 and the peripheral edge of the deck 8.

  The airtight plate 82 is formed between the peripheral edge of the deck 8 and the inner peripheral surface of the side wall 5 and closes the gap having a planar shape in a donut shape. For example, a plurality of fan-shaped plate members divided into 10 degrees each. It is only necessary that the gap is closed 360 degrees along the circumferential direction while wrapping the film by a predetermined width.

  Here, as shown in FIG. 8 (a), the side wall side of the airtight plate 82 is bent at its edge to form a locking portion 83, and as shown in FIG. The edge portion is bent into a leaf spring shape to form an elastic locking portion 84.

  Therefore, when the airtight plate 82 is bridged between the peripheral edge of the deck 8 and the inner peripheral surface of the side wall 5, the elastic airtight material 85 sandwiches the locking portion 83 provided on the side wall side edge of the airtight plate. In this state, it is hooked into the annular locking groove 81, and while the airtight plate 82 is pulled horizontally to the deck side in this state, the locking portion 84 is sandwiched with the stretchable airtight material 86 and the peripheral rib of the deck 8 Drop into.

  By doing so, the airtight plate 82 is easily and easily spanned between the peripheral edge of the deck 8 and the inner peripheral surface of the side wall 5 by the expansion and contraction action of the elastic airtight members 84 and 85. Can do.

  After the installation of the airtight plate 82, air is pressed into the airtight space 91 surrounded by the roof base material 63, the side wall 5, the deck 8, and the airtight plate 82.

  As shown in FIG. 9, the press-fitted air attempts to push the roof base material 63 upward and expand the deck 8 downward. As shown in FIG. 9, the deck 8 passes through the suspension rod 7. Since the suspension rod 7 is suspended from the frame 62, the suspension of the deck 8 is prevented while the suspension rod 7 bears the tensile force.

  When the air pressure is press-fitted into the airtight space 91, as shown in FIGS. 9 and 10, the concrete material 92 is placed on the dam plate using the roof base material 63 as a dam plate.

  Here, the vertical load of the fresh concrete placed is supported by the air pressure in the airtight space 91. Therefore, the state where the wide internal work space 4a is secured between the deck 8 and the bottom plate 3 is maintained without the deck 8 hanging down.

  Next, when the strength of the concrete is developed, the air in the airtight space 91 is evacuated as necessary, and then the airtight plate 82 is removed, while the deck 8 is suspended by laying glass wool as a cold insulating material. Use as a floor.

  As described above, according to the concrete roof construction method according to the present embodiment, the concrete load of the placed concrete roof is supported by the pressure of the air press-fitted into the airtight space 91, and the deck 8 is moved downward. Since the suspension rod 7 supports the air pressure to be pushed down by the tensile resistance, the deck 8 is prevented from drooping, and thus a large internal work space 4a is secured between the deck 8 and the bottom plate 3. Can do.

  Therefore, even during the concrete curing period, in the internal work space 4a, on the inner side of the side wall 5, installation of tank body side parts such as a steel outer tank side liner, side refrigeration made of pearlite, and an inner tank side plate. On the upper side of the bottom plate 3, it is possible to proceed with the installation work of the tank body bottom such as the outer tank bottom liner, the bottom cooler, and the inner tank bottom plate.

  In this embodiment, the roof frame 11 is bridged by a so-called air lasing method in which it is increased by air pressure. In addition, air is pressed into an airtight space surrounded by the roof base material, side walls, membrane material and airtight plate, and in this state, concrete is placed using the roof base material as a dam plate, and the tensile resistance of the suspension rod In terms of preventing the film material from drooping, the construction of the roof frame is arbitrary, and the roof frame may be bridged by a known method other than the air-raising method.

  Moreover, in this embodiment, although the structure used as construction object of a concrete roof was used as the PCLNG ground type storage tank, while being able to apply this invention also to an underground type LNG storage tank, it is also applied to buildings other than an LNG tank. It goes without saying that it can be applied.

1 is an overall view of an LNG tank 1 to which a construction method according to the present embodiment is applied. The figure which showed a mode that the construction method of the concrete roof which concerns on this embodiment was implemented. The figure which showed a mode that the construction method concerning this embodiment was implemented continuously. The detailed drawing of the side wall top part at the time of raising the roof frame 11 by air pressure. The figure which showed a mode that the construction method concerning this embodiment was implemented continuously. FIG. 3 is a detailed view of the top of the side wall when the roof frame 11 is bridged to the top of the side wall 5. The figure which showed a mode that the clearance gap produced between the deck 8 and the side wall 5 was plugged up with the airtight board 8. FIG. FIG. 3 is a detailed view showing an installation state at both edges of the airtight plate 8. The figure which showed a mode that the construction method concerning this embodiment was implemented continuously. The figure which showed a mode that the concrete placement of a concrete roof was performed, supporting with the air pressure of the airtight space 91. FIG.

Explanation of symbols

1 LNG tank 3 Bottom plate 4 Internal space 4a Internal work space 5 Side wall 6 Concrete roof 7 Suspension rod 8 Deck (membrane material)
11 Roof frame 61 Airtight seal 62 Frame 63 Roof base material 82 Airtight plate 92 Concrete

Claims (4)

In a concrete roof construction method in which a dome-like roof frame is built around the top of a cylindrical side wall erected on the bottom plate so as to surround the upper space of the bottom plate, and then roof concrete work is performed,
The roof frame is assembled so that the roof frame is composed of a frame and a roof base material affixed to the frame, and a suspension rod is suspended from the frame, and a membrane material is provided at the lower end of the suspension rod. Attaching, spanning the roof frame to the top of the side wall, closing the gap between the peripheral edge of the membrane material and the inner peripheral surface of the side wall with an airtight plate and making the roof base material and the top of the side wall airtight, Air is pressed into an airtight space surrounded by a roof base material, the side wall, the membrane material and the airtight plate, and then concrete is placed on the barrier plate using the roof base material as a barrier plate. How to construct a concrete roof. The roof frame, the suspension rod and the membrane material are pre-assembled on the bottom plate, and after the roof frame is raised together with the suspension rod and the membrane material, the roof frame is The concrete roof construction method according to claim 1, wherein the concrete roof is fixed to the top of the side wall, and then the airtight plate is installed and the air pressure is pressed. The construction method of the concrete roof of Claim 2 which performs the said raising process with an air pressure. The bottom plate, the side wall, the roof frame, the suspension rod, and the membrane material, respectively, a bottom plate of an LNG tank, a side wall that stands near the periphery of the bottom plate, a framework that spans the top of the side wall, and a roof base The concrete roof according to any one of claims 1 to 3, wherein the roof is made of a material, the suspension rod is suspended from the frame, and the deck is suspended by the suspension rod and laid with a heat insulating material. Construction method.

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