JPH0238740B2 - - Google Patents

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a construction method for a spherical PC structure.

[Conventional technology]

Conventionally, in a spherical PC structure A such as an egg-shaped digester as shown in FIG. It has been adopted to introduce prestress by arranging

The spherical PC structure A is constructed by arranging reinforcing bars in the concrete 2, along with the prestressing steel 1, and introducing prestress.
PC steel material 1 installed in the lower bottom slab of PC structure A
As shown in Figure 9, the lower end is fixed and the spiral is arranged in a spiral shape that gradually slopes horizontally toward the top.When viewed from above, it forms an arc in the clockwise direction. One is drawn and the other is arranged in an arc counterclockwise, so that the two intersect. Then, the upper end of the PC steel material 1 placed at the bottom is made to protrude inside the spherical PC structure A, and after concrete 2 is poured and hardened, a jack is placed inside the spherical PC structure A. PC
Steel material 1 is tensed to introduce prestress.

Since the prestressed steel material 1 is arranged in a spiral, prestress can be simultaneously introduced in both the horizontal and vertical directions by tensioning, and by changing the inclination of the prestressed steel material 1, prestress can be applied in both the horizontal and vertical directions. It is possible to adjust the ratio of the magnitude of the prestress.

In this way, the PC steel material 1 placed at the bottom is shaped into a spherical shape.
The reason why the inside of PC Structure A can be tensioned is that it can be constructed even in cases where the jack cannot be set in the part to be buried underground.

[Problem to be solved by the invention]

However, with only the above PC steel material 1, the spherical shape
The PC steel material 1 cannot pass through the deepest part of the bottom of the PC structure A, and if the hydraulic load is concentrated on this part, there is a risk that the bottom will fall out. The purpose of the present invention is to eliminate such inconveniences, and as a construction method, it is possible to construct a PC structure that eliminates the need to perform work underground where members such as reinforcing bars are concentrated, and that can streamline construction. It is about providing law.

[Means to solve the problem]

In order to achieve the above-mentioned object, the present invention has an egg-shaped spherical PC structure whose lower part is buried underground, and a part of the PC steel material disposed in the lower bottom slab part is continuous vertically centering on the deepest part. shall be installed and applicable.
The PC steel material or its sheath is used when assembling on the ground the bottom reinforcing bars, in which the bottom reinforcing bars and the top reinforcing bars are arranged radially with a vertical interval, and hoop-shaped horizontal bars are orthogonally intersected with each other to form a basket shape. The gist of this is to set them together in advance between the reinforcing bars.

[Effect]

According to the present invention, the PC steel material also penetrates the deepest part of the bottom plate of the spherical PC structure and lifts this part, so there is no need to worry about the bottom plate falling out.

In addition, when the penetrating prestressing steel material is installed between intricate reinforcing bars, at least the sheath part of the reinforcing bars itself is preset between them when the reinforcing bars are assembled on the ground, so it is difficult for people to fit into a narrow space. There is no need to crawl in and do the work.

〔Example〕

Embodiments of the present invention will be described in detail below with reference to the drawings.

First, to briefly explain the method of construction of the egg-shaped spherical PC structure shown in Fig. 10, as the foundation work shown in Fig. 3, piles 3 are constructed using the hollow construction method, and as shown in Fig. 4. As shown in Figure 2, after constructing earth retaining (four steel sheet piles, tie rods) as earthworks, ground improvement will be carried out and excavation will be carried out in primary and secondary sections (bottom slab section).

Next, as shown in Figure 5, 2
After the next excavation, concrete is sprayed 5, and the bottom slab concrete 6, which will become the frame, is constructed using a formwork 7 using a ring beam type steel girder.

Then, as shown in FIG. 6, climbing scaffolding 8 is used for the inside and framework scaffolding 9 is used for the outside. First, the ring foundation 10 is constructed using ordinary formwork, and then the side walls are constructed in stages 1 to 4. Figure 7 shows the sidewall work, which is carried out using climbing scaffolds 8 on both the inside and outside, and is carried out continuously in a ring shape divided into ten or more stages. Finally, as shown in FIG. 8, the gas dome 13 and sludge pocket 14 are constructed using the bracket scaffolding 11 and the center frame 12 as part of the top construction, and the construction is completed.

Among these, in the bottom slab construction shown in FIGS. 3 and 4, many reinforcing bars and prestressing steel materials will be placed inside the bottom slab concrete 6.

Figure 1 shows the situation, and the reinforcing bar is the lower end bar 15a.
and upper end reinforcements 15b are arranged radially with vertical spacing, and hoop-shaped horizontal reinforcements 15c are orthogonal to each of them to form a basket shape. All of these are assembled on the ground, but at that time there are no spaces between the reinforcing bars. The sheath 16 for the prestressed steel material and the prestressed steel material 1 (in this case, the prestressed steel rod) explained in the conventional example are assembled together.

The sheath 16 is continuous in the vertical direction centering on the deepest part, and the sheath 16 may be used alone, but a prestressed steel stranded wire 17 may be inserted in advance into the sheath 16. In addition, in the case of only the sheath 16,
After it is built underground, the PC steel stranded wire 17 will be passed through it.

In the figure, 18 indicates a holding frame for ground assembly. The reinforcing bars etc. assembled on the ground are placed on top of the sprayed concrete shown in FIG. 5, and concrete is poured from above to form the bottom slab concrete 6. In this case, the sheath 16 is placed as shown in FIG. And the PC steel stranded wire 17 (PC steel material 1 is omitted in Fig. 2) penetrates the deepest part of the bottom, and in this way, the center of the bottom of the spherical PC structure A is It will be lifted upwards.

〔Effect of the invention〕

As described above, the method for constructing a PC structure of the present invention improves the load-bearing performance of the bottom part of an egg-shaped spherical PC structure whose bottom part is buried underground. Even if this involves penetrating and installing prestressing steel, pre-assembling it on the ground eliminates the troublesome underground work and improves safety and workability. .

[Brief explanation of drawings]

Fig. 1 is a side view showing an embodiment of the construction method of the present invention, Fig. 2 is a plan view of the same, and Figs. 3 to 8 are oval-shaped spheres.
FIG. 9 is a cross-sectional plan view of the bottom plate of the oval-shaped PC structure, and FIG. 10 is a partially omitted vertical cross-sectional side view of the same. 1...PC steel material, 2...concrete, 3...
Piles, 4...Steel sheet piles, 5...Concrete spraying, 6
...Bottom slab concrete, 7...Ring beam formwork, 8...Climbing scaffolding, 9...Frame scaffolding,
10...Ring foundation, 11...Bracket scaffolding, 12...Center pedestal, 13...Gas dome, 14...Sludge pocket, 15a...Lower end reinforcement, 15b...Upper end reinforcement, 15c...Transverse reinforcement, 16...
...Sheath, 17...PC steel stranded wire, 18...Holding frame for ground assembly.

Claims (1)

[Claims] 1. In an egg-shaped spherical PC structure whose lower part is buried underground, some of the PC steel materials installed in the bottom slab of the lower part are placed continuously up and down centering on the deepest part, and the PC Steel materials or their sheaths are used when assembling bottom slab reinforcement on the ground, in which lower end reinforcement and upper end reinforcement are arranged radially with a vertical interval, and hoop-shaped horizontal reinforcement is orthogonally intersected with each other to form a basket shape. A method of constructing a spherical PC structure characterized by pre-setting the PC structures together.