JP2007063895A - Construction method for side wall of underground tank - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To efficiently place sidewall concrete in the construction of a large-scale underground tank. <P>SOLUTION: The whole of a one-lot (#3-lot) concrete placing area is divided into a lower placing area (#3-1) and an upper placing area (#3-2), and a working space 4 is presecured by post-constructing a part of a bar arranged in a boundary between the placing areas (#3-1) and (#3-2). Lower and upper placing pipelines 11A and 11B for independently placing the concrete in the respective placing areas are preinstalled in the placing areas, respectively; the concrete is placed in the lower placing area through the lower placing pipeline while an ascending-type frame device 20 is elevated; after that, the bar arranged in the working space is post-constructed by removing the lower placing pipeline; and consecutively, the concrete is placed in the upper placing area through the upper placing pipeline. An anchoring bar in which an anchoring head or a hook is integrally formed at an end is used as the reinforcing bar that is post-constructed in the working space. An embedded scaffold embedded within the wall thickness of the side wall is employed, and placing piping is installed in the state of being supported on the embedded scaffold. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method for efficiently constructing a side wall of a large-scale reinforced concrete underground tank such as an LNG underground storage tank.

When constructing this type of underground tank, it is necessary to cast a large amount of concrete once over a wide area. Conventionally, a placement pipe for pumping concrete from a pump car placed on the ground to a placement site is generally used. It is common to place a road in advance, and pull concrete up in layers by pulling up sequentially while routing a vertical hose connected to the placement pipe. As such a construction method, in addition to the conventional method of rearranging the formwork sequentially and upward, the so-called slip form method of placing concrete continuously while raising the formwork continuously Is also known. Furthermore, for example, Patent Document 1 proposes a method of performing various operations related to side wall construction by sequentially raising a working scaffold, a concrete placing pipe, and a truss beam to which an inner mold is attached.
JP 2003-119806 A

  In any case, when constructing concrete from the ground to the underground when constructing the side walls of a large underground tank, it is generally better to increase the placement height of one lot as much as possible. It is considered efficient not only for installation work, but also for bar arrangement work, formwork work, and joint processing, but in practice, if the setting height is set too high, material separation in the vertical hose and Since there is a possibility of causing clogging, the construction quality and construction efficiency may be lowered, so in the past, any construction method could not set the concrete placement height per lot too large, Normally, the limit is 8.5 m to 10 m at the maximum.

  FIG. 9 shows a specific example of the conventional method. This is a large scale in which, for example, the total height of the underground continuous wall 1 reaches 42 m after excavating the inside of the underground continuous wall 1 previously constructed as a mountain retaining and water blocking wall and constructing the bottom plate 2. As shown in the figure, first, two lots (# 1 lot and # 2 lot) in which the placement height is set to about 3 m with respect to the lower portion of the side wall 3 are shown. After the placement, the placement height is set to about 8-9m, which is close to the limit, and 4 lots (# 3 lot to # 6 lot) are placed sequentially, and finally the top (# 7 lot) is placed. I try to cast it. In other words, in this case, it is unavoidable to perform concrete placement independently on the bottom and top special portions of the side wall 3, but the construction of the mere intermediate portion is also limited to 4 from the limit of the placement height. It required lots of concrete to be cast, and therefore the joints were in total 6 locations.

  Thus, since the number of concrete placement lots in the conventional construction of the large-scale side wall 3 has to be increased, not only the placement work but also the placement work, the formwork work, and the joint part. All the work related to the side wall construction including the processing requires a lot of labor and cost, which is one of the factors hindering the improvement of workability when constructing this kind of underground tank.

  In view of the above circumstances, the present invention provides an effective and appropriate construction method that can set the placement height of one lot large without hindrance when placing side wall concrete in the construction of an underground tank, thereby improving workability. It is aimed.

  The present invention is a method for constructing a side wall of an underground tank for forming a side wall by placing concrete from the ground part in constructing an underground tank of reinforced concrete structure, and performs a bar arrangement work for a concrete placing region of one lot. In this case, the entire placement area is divided into a lower placement area and an upper placement area, and a part of the bar arrangement is post-installed at the boundary between the lower placement area and the upper placement area. As a result, a working space for placing concrete is secured there, and when placing concrete in the entire placement area, the ascending formwork device is raised at the bottom of the placement area. On the other hand, the lower placement pipeline for placing concrete in the lower placement area is installed from the surface to the lower placement area through the work space, and the upper placement area. Then, an upper placement pipe for placing concrete is installed in advance from the ground surface to the upper placement area, and the concrete is placed against the lower placement area by the lower placement pipe while raising the ascending formwork device. After the installation, the lower placement pipe is removed and the work space is post-installed, and then the ascending formwork device is further raised while the upper placement pipe is used for concrete placement in the upper placement area. It is characterized by setting.

  As a reinforcing bar to be laid after work on the work space, it is only necessary to use a fixing bar that is integrally formed with a fixing head or a hook part at the end, and the fixing bar is arranged as a shear reinforcement bar in the work space. .

  Adopting steel embedded scaffolds embedded in the side walls to be constructed, and using the embedded scaffolds to perform the reinforcement work, and supporting the lower and upper placement conduits on the embedded scaffolds Good.

  According to the present invention, a lower placement pipe for dividing a placement area of one lot into upper and lower portions, securing a working space between them, and placing concrete independently for both placement areas. Since the road and the upper placement pipe are installed in advance, it is necessary to temporarily suspend the work in the middle of the placement work and remove the placement pipe from the work space and perform the reinforcement work there. Although there is concrete, it is possible to perform concrete placement substantially continuously over the entire placement area, thereby making it possible to set the placement height per lot sufficiently larger than before. Therefore, it is possible to perform construction much more efficiently, and it is possible to reduce the construction period and the construction cost.

  In particular, by using a fixing bar having a fixing head or a hook portion as a bar arrangement to be post-installed in the work space, the bar arrangement work in the work space can be quickly performed. Further, by using a steel embedded scaffold that is embedded as it is in the side wall, the bar arrangement work can be performed efficiently, and the placement piping can be stably supported by the embedded scaffold and easily installed.

  1 to 8 show an embodiment of the construction method of the present invention. In the present embodiment, when the side wall 3 in the underground tank of the same scale as that shown in FIG. 9 is constructed, concrete placement is performed in all 5 lots (# 1 lot to # 5 lot). Placing the intermediate portion excluding the bottom and top of the side wall 3 is performed in only 3 lots (# 2 lot to # 4 lot). That is, in the case of the conventional general construction method shown in FIG. 9, it is necessary to divide the intermediate portion into four lots by limiting the placement height per lot to about 8 to 9 m. On the other hand, in the present embodiment, the number of lots in the intermediate portion is reduced as compared with the prior art by setting the placement height per lot to about 10 m to 14 m.

  However, simply increasing the placement height per lot as described above may cause material separation or blockage in the vertical hose during placement as described above. In the embodiment, the following steps are employed.

  That is, also in this embodiment, basically, the bar arrangement work is performed in units of lots corresponding to each lot of concrete placement as in the prior art. Therefore, for example, # 2 prior to concrete placement for the # 2 lot. In the present embodiment, the entire lot # 2 is further divided into a lower placement area (# 2-1) and an upper placement area (# 2-2). Then, as will be described later, as a part of the bar arrangement for the boundary portion is post-constructed, a work space 4 for concrete placement work is temporarily secured there. Similarly, at the time of the bar arrangement work for the entire # 3 lot, the entire # 3 lot is further divided into a lower placement area (# 3-1) and an upper placement area (# 3-2), and # 4 lots. In the arrangement work for the whole, the entire # 4 lot is further divided into a lower placement area (# 4-1) and an upper placement area (# 4-2). The work space is temporarily secured there by post-constructing the part.

  Further, in the present embodiment, the slip form method is adopted when placing the concrete of # 2 lot to # 4 lot, and for this purpose, the ascending mold apparatus 20 shown in FIGS. 2 to 3 is used. The ascending mold apparatus 20 is mainly composed of an annular truss frame 22 having a mold 21 and also serving as a work scaffold. The truss frame 22 is installed so that it can be lifted. By operating the hydraulic jack 24 while the guide rods 23 are successively extended upwards, the truss frame 22 can be lifted by itself by taking the reaction force from the guide rods 23. Accordingly, the concrete can be placed substantially continuously by sequentially raising the mold 21. In addition, since it is necessary to fix the guide rod 23 to the side wall 3 that has already been constructed via the support member 25, when the side wall 3 is constructed, is the support member 25 connected to the bar arrangement in the side wall? Or it is good to connect with the underground scaffolding wall 10 (after-mentioned) which is installed in the underground continuous wall 1 or a side wall, and is embedded as it is.

  The specific work process of the construction method of this embodiment is demonstrated with reference to FIGS. In the present embodiment, basically, as in the case of the conventional method shown in FIG. 9, the inside of the underground continuous wall 1 that has been previously constructed is excavated, the bottom plate 2 is preceded, and the bottommost portion of the side wall 3 is constructed. Is constructed in # 1 lot so as to be integrated with the bottom plate 2, and then the concrete is placed by using the above-described ascending mold apparatus 20 with the intermediate portion of the side wall 3 as # 2 to # 4 lot as described above. It will be constructed sequentially. Further, when the side wall 3 is constructed, a steel embedded scaffold 10 (not shown in FIG. 4) is installed in the wall thickness of the side wall 3, and this is used as a working scaffold to connect the inner and outer distribution bars and the main bars 6 to each other. The reinforcing bars 7 are arranged with the shear reinforcement bars 7 as a main component, and the placement scaffolds 11 (11A, 11B), which will be described later, are supported and installed on the embedded scaffolds 10.

  FIG. 4 shows a state immediately before placing concrete for # 3 lot, that is, the arrangement work for the entire # 3 lot is completed, and the ascending formwork apparatus 20 is installed at the lowermost part to place concrete. The installation pipe line 11 (11A, 11B) is shown. In this state, as described above, the entire # 3 lot is divided into the lower placement area (# 3-1) and the upper placement area (# 3-2), and the upper placement area which is the boundary portion thereof. At the bottom of (# 3-2), the two-stage shear reinforcement bars 7 are left without being arranged, so that at this point, a work space 4 is secured to allow workers to pass therethrough. .

  Further, as the placement line 11 for the entire # 3 lot, the lower placement line 11A for the lower placement area (# 3-1) and the upper placement line for the upper placement area (# 3-2). 11B is installed independently in advance. Each of the placement pipes 11 (11A, 11B) is arranged horizontally in the placement area connected to the main pipe 13 connected to the pump car 12 arranged on the surface and the main pipe 13. The horizontal conduit 14 and the vertical hose 15 connected to the horizontal conduit 14 and routed are connected to each of the embedded scaffolds 10 (11A, 11B). Supported and installed. The horizontal pipeline 14 in the upper placement pipeline 11B is arranged at the top of the entire # 3 lot (that is, the top of the # 3-2 lot) as usual, but in the lower placement pipeline 11A. The horizontal pipe 14 is disposed in the work space 4 secured at the boundary portion (the bottom of the # 3-2 lot), and by using the work space 4, a lower placement area ( The concrete placing work for # 3-1) can be performed without any trouble.

  In order to place concrete for the entire # 3 lot by the construction method of the present embodiment, as shown in FIG. First, both the path 11A and the upper stage placement pipe 11B are installed in advance, and the ascending mold apparatus 20 is installed at the lowermost part of the # 3 lot. Concrete placement for the lower placement area (# 2-1) is performed. That is, the concrete is pumped from the pump car 12 through the lower casting line 11A to the lower casting area (# 2-1), and the worker sequentially pulls up the vertical hose 15 and synchronizes with it. The ascending mold apparatus 20 is raised, and concrete is cast and filled in layers.

  Thus, when the concrete placement for the lower placement area (# 3-1) as shown in FIG. 5 is completed, all of the lower placement pipeline 11A is quickly removed as shown in FIG. As shown in FIG. 7, the post-installation of the work space 4 is quickly performed. In other words, in order to secure the work space 4, the two-stage shear reinforcement bars 7 left without being arranged are arranged. In this case, a normal reinforcing bar may be used as the shear reinforcing bar 7, but two fixing bars 16 each having a fixing head 16a integrally formed at the end portion are used as a set, and the main reinforcing bars 6 are used as inner and outer main bars 6. If the bars are arranged between the two, the arrangement work can be performed easily and quickly.

  When the concrete placement for the lower placement area (# 3-1) of the entire # 3 lot, the removal of the lower placement conduit 11A, and the reinforcement work for the work space 4 are performed as described above, the ascending type is continued. While raising the frame device 20, concrete placement is performed as usual in the upper placement area (# 3-2) through the upper placement pipeline 11 </ b> B. When the concrete placement for the entire # 3 lot is completed, the operation moves to the # 4 lot and the same procedure is repeated.

  Note that the reinforcing bars for the work space 4 are instead of using the above two fixing bars 16 as a set, for example, as shown in FIG. 8A, a fixing bar having a hook portion 17a formed at the end. 17 may be used as one set, or as shown in FIG. 5B, the fixing muscle 16 having the fixing head 16a and the fixing muscle 17 having the hook portion 17a may be used in combination.

  According to the construction method of the present embodiment, it is necessary to temporarily suspend the placing operation in the course of one lot of concrete placing process, to remove the lower placing pipe line 11A, and to carry out the post-construction of some bars. Although it is possible, it is possible to perform concrete placement substantially continuously over the entire placement area of one lot at a stretch, so that the placement height per lot can be set larger than the conventional limit. Efficient construction, shortening the construction period and reducing construction costs. Of course, although the placement height is set to be large, the placement height in the lower placement area (# 3-1) and the upper placement area (# 3-2) is in the same range as in the prior art. In this case, there is no material separation or blockage in the vertical hose 15, and there is no concern about deterioration in construction efficiency and construction quality as in the case of simply increasing the placement height.

  Although the embodiment of the present invention has been described above, the above embodiment is merely a preferred example, and the present invention is not limited to the above embodiment. For example, the setting of the number of lots for placing concrete The details of the process, the configuration of the rising form apparatus and the operation procedure thereof, the specific configuration of the reinforcement and the embedded scaffolding on the side wall, the necessity of the underground continuous wall, etc. are within the scope not departing from the gist of the present invention. Appropriate design changes can be made according to the scale, form and application of the underground tank to be constructed.

The embodiment of the present invention is shown, and is a diagram showing lot setting of a concrete placing process on a tank side wall. It is a top view which shows the outline | summary of a raise mold apparatus same as the above. It is an elevation view which shows the outline | summary of a raise mold apparatus same as the above. It is a figure which shows the condition just before concrete placement with respect to # 3 lot. It is a figure which shows the state which concrete placement with respect to the lower stage placement area in # 3 lot was completed. It is a figure which shows the state which removed the lower stage installation piping. It is a figure which shows an example of the state which carried out the post-installation in the working space. It is a figure which shows the other example of the state which carried out the post-installation in the work space. It is a figure which shows the lot setting of the concrete placement process with respect to the conventional general tank side wall.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Underground continuous wall 2 Bottom plate 3 Side wall 4 Work space 6 Main reinforcement 7 Shear reinforcement 10 Embedded scaffold 11 Placing pipeline 11A Lower placement pipeline 11B Upper placement pipeline 12 Pump car 13 Main pipeline 14 Horizontal pipeline 15 Vertical Hose 16 anchoring muscle 16a anchoring head 17 anchoring muscle 17a hook part 20 ascending mold device 21 mold 22 truss frame 23 guide rod 24 hydraulic jack 25 support member

Claims (3)

In constructing a reinforced concrete underground tank, a side wall construction method for an underground tank for placing concrete from the ground to form a sidewall,
When performing the bar arrangement work for one lot of concrete placement area, the entire placement area is divided into a lower placement area and an upper placement area, and the boundary between the lower placement area and the upper placement area. As for the part, as a part of the bar arrangement is post-constructed, a work space for concrete placement work is secured there,
When placing concrete in the entire placement area, the ascending formwork device is installed at the lowermost part of the placement area so that it can be raised, while the concrete is placed in the lower placement area. Install the lower placement pipe from the surface to the lower placement area through the work space, and the upper placement pipe from the ground to the upper placement area for placing concrete in the upper placement area. Set up in advance,
After raising the ascending formwork device, placing the concrete in the lower casting area using the lower casting pipe, then removing the lower casting pipe and post-laying the work space, and then raising A method for constructing a side wall of an underground tank, wherein concrete casting is performed on an upper casting area by an upper casting pipe while further raising a formwork device. A side wall construction method for an underground tank according to claim 1,
As a reinforcing bar to be laid after work on the work space, a fixing bar with a fixed head or hook part formed integrally at the end is used, and the fixing bar is placed in the work space as a shear reinforcement bar. The underground tank side wall construction method. It is the side wall construction method of the underground tank of Claim 1 or 2,
Adopting steel embedded scaffolds embedded in the side walls to be constructed, and using the embedded scaffolds to perform the reinforcement work, and supporting the lower and upper placement conduits on the embedded scaffolds A method for constructing a side wall of an underground tank.

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