JP2001193382A - Constructing method for shaft having wall with varied thickness - Google Patents

Abstract

PROBLEM TO BE SOLVED: To vary the wall thickness in the vertical direction and to allow construction of a floor in a stepped part by means of a slide form construction method. SOLUTION: When a stage 4 reaches the predetermined height, an auxiliary frame 9 is installed to its outer circumference, and a mold 8 and a hydraulic jack 6 are removed and installed to the auxiliary frame 9, so that the thickness of a concrete wall C is reduced in the part constructed afterward, and a floor part D is formed when a floor plate 11 of a half PC plate is placed to the stepped part and concrete is placed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for constructing a shaft, and more particularly to a method for constructing a shaft having a change in the thickness of a concrete wall depending on the depth.

[0002]

2. Description of the Related Art For example, silos, chimneys, shafts, etc.
In order to construct a concrete wall structure having a circular cross-sectional shape, a sliding foam method of sequentially moving a form in a height direction is known. An example will be briefly described with reference to FIGS. FIG. 9 is a cross-sectional view showing a situation in which a shaft having a circular section and a constant wall thickness is constructed in a vertical hole excavated in the ground, and FIG.
Is a ground wall, C is a concrete wall formed on the inner surface of a vertical hole of the ground ground G that has been excavated, 1 is a receiving hopper for receiving concrete on a ground portion, 2 is a rotary hopper provided at a lower portion thereof through a vertical pipe, 3 Is a rotary chute connected to the rotary hopper 2 for supplying concrete in a circumferential shape, 4 is a stage suspended and held at a concrete pouring height, and the outer shape is inside a ring-shaped frame slightly smaller than a vertical hole cross section. 5 is a steel rod vertically arranged at a predetermined pitch in the circumferential direction on a concrete wall, 6 is a hydraulic jack locked to this, 7 is a hydraulic jack 6 and a stage 4 The yoke 8 is a frame that connects the stage 4 with a concrete formwork attached to the outer periphery of the stage 4.
A gap corresponding to the wall thickness to be formed is formed between the mold 8 and the ground.

First, the stage 4 is suspended from the bottom of the vertical hole, concrete is supplied to the rotary chute 3 from the ground, and concrete is poured between the form 8 and the ground to form the bottom of the concrete wall C. Inside the concrete wall C, steel rods 5 are vertically arranged at a predetermined pitch, and a hydraulic jack 6 attached to the stage 4 is engaged with the rods 5. When the poured concrete hardens, the hydraulic jack 6 is operated to raise the stage 4 by a predetermined stroke h, and concrete is newly poured into the upper part of the existing concrete wall. After curing, raise stage 4 again,
Hereinafter, the concrete wall C is constructed from the lower side to the upper side by this repetition.

[0004] Since such a conventional pit formed by the sliding form method can construct only a concrete wall body having the same inner surface shape in the depth direction, it is limited to a ventilation opening of a tunnel or a pressure regulating water tank of a dam, and is located at an intermediate height. In the case of water and sewage pits that have horizontal floors as beams to counter the earth pressure, even if the walls are constructed by the sliding form method, the floor will be a conventional method combining scaffolding and formwork. Therefore, there is a problem that the omission of the scaffolding, which is a feature of the sliding form method, cannot be achieved.

[0005]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and it has been made possible to change the wall thickness in the height direction only by using the slide form method, and to construct the floor. The purpose is to do.

[0006]

SUMMARY OF THE INVENTION According to the present invention, a stage having a profile slightly smaller than the vertical hole cross section is suspended in a vertical hole excavated from the ground, and concrete is filled in a gap between the formwork attached to the outer periphery thereof and the ground. Injecting, raising the stage after the concrete is hardened, raising the stage, and thereafter repeating this, in a method of constructing a shaft which forms a concrete wall on the inner surface of the vertical hole, when the stage reaches a predetermined height, the outer periphery of the stage A method of constructing a shaft with a change in wall thickness, characterized in that the inner wall of the concrete wall is made larger for the portion to be built thereafter by attaching an auxiliary frame to the shaft, and further, the inner wall of the concrete wall changes. It is preferable to place a floor slab on the stepped portion, cast concrete on the upper surface and integrate it with the surrounding concrete wall to form a floor portion The deck is desirably half PC version obtained by dividing the cross-section of the intake shaft in a plurality.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described with reference to the drawings. In this embodiment, the inner thickness of the concrete wall C is gradually increased from the deep portion to the shallow portion, that is, assuming that the vertical hole excavated from the ground is cylindrical, the wall thickness of the concrete wall C is changed according to the depth. It shall be changed step by step, and a stepped shaft shall be constructed in which a horizontal floor is provided at the stepped portion where the wall thickness changes.

The operation from the bottom of the shaft to the first wall thickness change position is the same as in the conventional case described with reference to FIG. FIG.
Shows the situation where the stage 4 reaches the first wall thickness change position in this way. Each code is the same as before. Subsequently, as shown in the left half of FIG. 2, the stage 4 is raised by the hydraulic jack 6 by one stroke. Here holds the stage 4 is attached to bracket 10 hypotheses on the upper end internal surface of the existing concrete wall C _0, the difference between the wall thickness and the new wall thickness so far to remove the mold 8 in its outer peripheral surface The auxiliary frame 9 having a width corresponding to the above is attached, and the mold 8 is attached to the outer periphery again. The rod 5
Rearranged slightly outside, and hydraulic jack 6
Is also replaced with the auxiliary frame 9. The left half of FIG. 2 shows a state before the auxiliary frame 9 is attached, and the right half shows a state after the auxiliary frame 9 is attached.

After the auxiliary frame 9 is attached, the ground G and the mold 8
If injected concrete between which larger clear width than before, it is possible to form a thin concrete wall C ₁ of the wall thickness. Once the concrete wall C ₁ has risen to some extent after the wall thickness change, to form a floor to the stepped portion T. As shown in FIG. 3, the floor slab 11 is hung on the stepped portion T. If the floor to be formed is merely a lid, the floor slab 11 may be obtained by dividing a pre-fabricated PC plate or the like as necessary, but the floor is used as a beam, that is, against the surrounding earth pressure. When designing as a structural member to be used, it is preferable to use a half-PC version, which is a semi-finished product, as the floor slab 11. As shown in FIG. 4, the half PC plate is a plate-shaped concrete plate 111 in which a wavy reinforcing bar 112 is partially buried, and is commercially available under the name of Omnia plate or Kaiser plate. The half-PC version does not require a separate formwork because the concrete plate 111 is discarded. If it is attempted to use a conventional wooden formwork without using the half-PC version, if the diameter of the shaft is large, the deflection due to its own weight is large, so it has to be supported in the middle, and the scaffold is not required. The benefits disappear. It is not preferable to use a metal discarded formwork such as a deck plate because it may be corroded by moisture or the like in a pit.

[0010] The floor slab 11 is placed on the stepped portion T, the upper reinforcing bar is arranged on the reinforcing bar 112, and the reinforcing bar 112 is moved to a height that gives a predetermined cover thickness.
Concrete is cast on the floor slab 11 and its surroundings.
Until the concrete hardens, the floor slab 11 may be dropped or lifted up. Therefore, it is desirable to suspend the slab 11 from the stage 4 by the hanging rod 13 as shown in FIG.

FIG. 5 is a sectional view showing a state in which a floor D is formed at a stepped portion between concrete walls C ₀ and C ₁ having different wall thicknesses. By the way, taking the case where the cross section of the shaft is circular as an example, the floor slab 11 to be taken in cannot be suspended through the stage 4 if it is a single slab having the entire cross section. And the like are used. FIG. 6 shows an example of the division. With respect to the circular opening of the stepped portion T, a lunar shape 11a surrounded by a portion less than half of the circumference and a chord corresponding to the portion,
11b, and the other two ends are circular arcs, and the center part of a substantially strip shape is divided into two in the length direction. It is composed of two sheets, 11c and 11d, for a total of four sheets. Engage or add steps and drop. FIG. 6 shows a stepped portion T
(A) is a state before the floor slab 11 is placed, (b) is a state where two sheets 11a and 11b are first placed, and (c) is a state where the remaining two sheets are placed and opened. The whole is in the closed state.

FIG. 7 shows an example in which the diameter of the shaft is large and the floor slab 11 is divided more finely. Moon-shaped on both sides
11a and 11b are further opened on both sides, and the inner one is divided into four sheets 11e, 11f, 11g and 11h. FIG. 7A shows a state in which two sheets 11a and 11b are placed on both sides, and FIG. 7B shows a state in which the remaining four sheets are placed and the entire opening is closed. FIG. 8 shows a vertical sectional view taken along the line AA in FIG.

When the number of divisions is increased, the floor slabs are unstable until the concrete is hardened by placing the entire slab. Therefore, the hanging bar 13 is lowered from the stage and the floor slabs are held. It is even more important to keep Although an example of a shaft with a circular cross section has been described above, the present invention is not limited to this, and by changing the shape of the stage, an ellipse, an ellipse, and a cross section such as a quadrilateral can be implemented. Needless to explain again. It is optional to install machinery on the floor or to provide manholes for traffic.

In addition, the wall thickness can be changed in three or more steps,
It is easy to provide floors in two or more places by repeating the above procedure.

[0015]

According to the present invention, the wall thickness can be changed in the slide form method, and the floor can be formed at an intermediate height of the shaft by using the stage. There is an excellent effect that the construction of a shaft with a floor is made more efficient and the construction period and construction costs can be greatly reduced.

[Brief description of the drawings]

FIG. 1 is a vertical sectional view of a shaft showing an intermediate stage in an embodiment of the present invention.

FIG. 2 is a vertical sectional view of a shaft showing a next stage in the embodiment of the present invention.

FIG. 3 is a longitudinal sectional view of a shaft showing a further next stage in the embodiment of the present invention.

FIG. 4 is a cross-sectional view showing a half PC plate used in the present invention.

FIG. 5 is a vertical sectional view of a shaft showing a further next stage in the embodiment of the present invention.

FIG. 6 is a horizontal sectional view of a shaft showing a floor portion in the embodiment of the present invention.

FIG. 7 is a horizontal sectional view of a shaft showing a floor portion in the embodiment of the present invention.

FIG. 8 is a longitudinal sectional view taken along the line AA in FIG. 7;

FIG. 9 is a vertical sectional view of a shaft under construction showing a conventional technique.

FIG. 10 is a partial cross-sectional view showing a portion B of FIG. 9 in an enlarged manner.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Receiving hopper 2 Rotating hopper 3 Rotating chute 4 Stage 5 Rod 6 Hydraulic jack 7 Yoke 8 Form frame 9 Auxiliary frame 10 Bracket 11 Floor plate 13 Hanging bar 111 PC plate 112 Reinforcing bar C Concrete wall D Floor G Ground mountain T Stepped part

Claims (3)

[Claims] 1. A stage having an outer shape slightly smaller than the vertical hole cross section is suspended in a vertical hole excavated from the ground, concrete is poured into a gap between a formwork attached to the outer periphery of the stage and the ground, and the concrete is hardened. In the method of constructing a shaft where the concrete wall is formed on the inner surface of the vertical hole by repeating the above, the auxiliary frame is attached to the outer periphery of the stage when the stage reaches a predetermined height. A method of constructing a shaft having a change in wall thickness, characterized in that the inside of a concrete wall is increased in a part to be constructed. 2. A floor slab is placed on a stepped portion of a concrete wall where an inner method changes, and concrete is poured on the upper surface thereof to be integrated with a surrounding concrete wall to form a floor portion. The method for constructing a shaft having a change in wall thickness according to claim 1. 3. The method according to claim 2, wherein the floor slab is a half-PC slab in which a section of the shaft is divided into a plurality of sections.