JP4524755B2 - Side wall construction method for underground tank - Google Patents

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 the road in advance, and pull up the concrete in layers by sequentially pulling up the vertical hose connected to the placement pipe. As an example of such a construction method, for example, in Patent Document 1, a large number of vertical hoses are connected in advance to a horizontally placed installation line through automatic open / close valves, and these automatic open / close valves are appropriately used. An automatic placement control method has been proposed in which concrete is placed while being controlled to open and close at an appropriate timing.
JP-A-7-189487

  By the way, when constructing the side wall of a large underground tank, when placing concrete from the ground to the basement using the method described above, in general, the placement height of one lot should be as large as possible. However, it is considered efficient not only for placement work but also for bar arrangement work, formwork work, and processing of joints, but in practice, if the placement height is set too high, Since there is a possibility that material separation or blockage may occur and the construction quality and construction efficiency may be lowered, the concrete placement height per lot cannot be set so large conventionally. The limit is about 5 m to 10 m at the maximum.

  FIG. 7 shows a specific example of such a conventional general construction 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. when performing the frame work, the entire droplet formation regions by dividing the lower punch installation zone and the upper punch installation zone, the bottom-most of the upper punch installation zone at their lower punch installation zone and the upper hitting region where the boundary For this, a part of the bar arrangement will be post-installed, and a working space for concrete placement work will be secured there. When placing concrete in the entire placement area, we established a lower punch設管passage for pouring concrete from the surface portion to the lower punch installation zone through the horizontal line of the lower punch設管path disposed in the working space for installation zone, the upper Previously established the upper punch設管passage for pouring the concrete against installation zone from the surface portion to the upper punch installation zone through the horizontal line of the upper punch設管path disposed on top of the upper punch installation zone First, after placing concrete in the lower casting area using the lower casting pipe, the lower casting pipe is removed and post-installation of the work space is performed, followed by the upper casting pipe. The concrete is placed in the upper placement area by a road.

  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 formwork, and the lower and upper placement pipes as the embedded scaffolds It should be installed in support.

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. Road and upper placement pipes are installed in advance , and horizontal pipes are provided in the middle of the lower and upper placement pipes, so work temporarily during the placement work. Although it is necessary to remove the placement pipe line from the work space and perform the reinforcement work there, it is possible to perform concrete placement almost continuously over the entire placement area at a stretch. In this way, the placement height per lot can be set sufficiently larger than that of the prior art, so that the construction can be performed much more efficiently, and the construction period can be shortened and the construction cost can be reduced.

  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. In addition, by using steel embedded scaffolds that are embedded as they are in the side walls, reinforcement and formwork work can be performed more efficiently, and the installation piping can be installed with stable support by the embedded scaffolds. Can do.

  1 to 6 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. 7 is constructed, concrete placement is performed in all four lots (# 1 lot to # 4 lot). Placing the intermediate portion excluding the bottom and top of the side wall 3 is performed in only two lots (# 2 lot to # 3 lot). That is, in the case of the conventional general construction method shown in FIG. 7, it was 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 this embodiment, the placement height per lot is set to 17 m or more, which is about twice that of the conventional one, so that the number of lots in the intermediate portion is halved from the conventional one and only two lots are performed. It is said.

  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, in this embodiment as well, basically, in the same manner as in the prior art, the placement work and the formwork work are performed in units of lots corresponding to each lot of concrete placement, and therefore, for example, concrete placement for # 2 lot Prior to this, the arrangement work and the formwork for the entire # 2 lot are performed. In this embodiment, the entire # 2 lot is further divided into a lower placement area (# 2-1) and an upper placement area ( # 2-2), and a part of the bar arrangement for the boundary portion is post-installed, and a work space 4 for concrete placement work is temporarily secured there. Similarly, in the case of bar arrangement work and formwork 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). Then, as a part of the bar arrangement for the boundary portion is post-constructed, a work space for concrete placement work is temporarily secured there.

  The concrete 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 construction method shown in FIG. Is constructed in # 1 lot so as to be integrated with the bottom plate 2, and then the middle portion of the side wall 3 is constructed sequentially as # 2 lot to # 3 lot as described above. In the construction of the side wall 3, a frame scaffold 5 is installed in the tank, and the reinforcement is mainly composed of the inner and outer strength bars, the main bars 6, and the shear reinforcement bars 7 connecting them, and the working scaffold. The mold 8 is supported by the framework scaffold 5 via the support frame 9 and the tip of a separator (not shown) for supporting the mold 8 is fixed to the underground continuous wall 1. In this embodiment, in addition to the framework scaffold 5 described above, a steel embedded scaffold 10 (not shown in FIG. 2) that is embedded as it is in the side wall 3 to be constructed is installed, and the embedded scaffold 10 is also used. In addition, the placement work and the formwork work are performed, and the placement pipeline 11 (11A, 11B), which will be described later, is supported and installed by the embedded scaffolding 10.

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

  Further, as the placement line 11 for the entire # 2 lot, the lower placement line 11A for the lower placement area (# 2-1) and the upper placement line for the upper placement area (# 2-2). 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 are routed, and each of the placement conduits 11 (11A, 11B) is supported by the embedded scaffold 10 described above. Has been installed. The horizontal pipeline 14 in the upper placement pipeline 11B is arranged at the top of the entire # 2 lot (that is, the top of the # 2-2 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 # 2-2 lot), so that the lower placement area ( The concrete placing work for # 2-1) can be performed without any trouble. In addition, when placing concrete in each placement pipeline 11, placement control as shown in Patent Document 1 may be performed. For that purpose, an automatic opening / closing valve and a control device are provided in each placement pipeline 11. You should prepare.

  In order to place concrete on the entire # 2 lot by the method of the present embodiment, as shown in FIG. 2, bar arrangement is performed on the entire # 2 lot leaving the work space 4 portion, and # 2 After assembling the mold for the entire lot and installing both the lower casting line 11A and the upper casting line 11B in advance, the concrete is first placed in the lower casting area (# 2-1) through the lower casting line 11A. Then, concrete placement is performed on the upper placement area (# 2-2) through the upper placement pipeline 11B.

  That is, first, concrete is pumped from the pump car 12 through the lower casting pipe 11A to the lower casting area (# 2-1), and the worker sequentially pulls up the vertical hose 15 and pulls the concrete in layers. I will continue to fill.

  Thus, when the concrete placement for the lower placement area (# 2-1) as shown in FIG. 3 is completed, all of the lower placement pipeline 11A is quickly removed as shown in FIG. As shown in FIG. 5, the post-arrangement 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.

  If the concrete placement for the lower placement area (# 2-1) of the entire # 2 lot, the removal of the lower placement pipeline 11A, and the bar placement work for the work space 4 are performed as described above, this time, Concrete pouring is performed as usual in the upper placing area (# 2-2) through the upper placing conduit 11B. When the concrete placement for the entire # 2 lot is completed, the operation is shifted to the # 3 lot and the same procedure is repeated.

  In the arrangement of the working space 4, instead of using the above two fixing bars 16 as one set, for example, as shown in FIG. 6A, a fixing bar having a hook portion 17 a 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 as large as double the conventional placement. Therefore, the construction is much more efficient, and the construction period can be shortened and the construction cost can be reduced. Of course, although the casting height is set to about double , the horizontal pipeline 14 is arranged in the lowermost working space 4 of the upper casting area (# 2-2) in the lower casting pipe 11A. At the same time, a horizontal pipe 14 is arranged at the uppermost part of the upper casting area (# 2-2) in the upper casting pipe 11B, and concrete casting is performed through these horizontal pipes 14, thereby lowering the lower casting pipe 11B. In each of the placement area (# 2-1) and the upper placement area (# 2-2), it is possible to perform the placement height within the same range as in the prior art. There is no separation or blockage, 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 Concerning the details of the process, the concrete arrangement of reinforcement and formwork in the side walls, the necessity of underground continuous walls, the presence or absence of framework scaffolds and embedded scaffolds, etc., construction is performed within the scope of the present invention. Appropriate design changes can be made according to the scale, form and use of the underground tank.

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 figure which shows the condition immediately before concrete placement with respect to # 2 lot. It is a figure which shows the state which concrete placement with respect to the lower stage placement area in # 2 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 5 Framework scaffold 6 Main reinforcement 7 Shear reinforcement 8 Formwork 9 Support frame 10 Embedded scaffold 11 Placing pipeline 11A Lower placement pipeline 11B Upper placement pipeline 12 Pump car 13 Main Line 14 Horizontal Line 15 Vertical Hose 16 Anchor Muscle 16a Anchor Head 17 Anchor Muscle 17a Hook

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 bar arrangement work and formwork for a single lot of concrete placement area, the entire placement area is divided into a lower placement area and an upper placement area, and the lower placement area and the upper placement area are divided. As the bottom of the upper placement area at the boundary of the installation area, a work space for concrete placement work is secured there as a post-installation of part of the bar arrangement,
When placing concrete in the entire placing area, a lower placing pipe in which a lower placing pipe for placing concrete in the lower placing area is disposed in the work space from the surface portion. Is installed up to the lower placement area through the horizontal pipe as the upper placement pipe where the upper placement pipe for placing concrete in the upper placement area is placed from the surface to the top of the upper placement area. Pre-installed up to the upper placement area through the horizontal pipeline as the installation pipeline ,
First, after placing the concrete in the lower placement area using the lower placement pipe, remove the lower placement pipe and perform post-laying of the work space, and then continue the upper placement using the upper placement pipe. A method for constructing a side wall of an underground tank, wherein the concrete is placed in an installation area. It is the side wall construction method of the underground tank of 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. 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 formwork, and the lower and upper placement pipes as the embedded scaffolds Side wall construction method for underground tanks, characterized by supporting and installing.

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