JPH0343520A - Method of setting bottom die frame in reverse winding process - Google Patents

Abstract

PURPOSE:To enhance the efficiency of a reverse winding process by successively and stepwise forming an involute wall in which a plurality of sheath pipes and suspended anchors are embedded, at the inner periphery of a retaining wall, depthwise from the ground surface with the use of wires made to pierce through the sheath pipes. CONSTITUTION:Hollow sheath pipes 14, suspended anchors 16 and inner and outer wall-like reinforcements 80, 20 are embedded in an upper stage involute wall 12 which have been already formed at the inner periphery of a retaining wall 10, and wires 24 are made to pierce through the sheath pipes 14 so as to suspend the wall 12 by a crane on the ground. With the use of these wires 24, a die frame for forming a lower stage involute wall 12a is set. Further, a bottom die frame 26 is parted from the upper stage involute wall 12, and an outer wall-like reinforcement 20a, a suspended anchor 16a and an inner wall reinforcement 18a are extended downward, successively and are secured. Further, the bottom die frame 26 is locked and secured to the lower end of the suspended anchor 16a. With this arrangement, the suspended anchor 16a and the like may be simply pulled into, thereby it is possible to enhance the efficiency of the construction.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Field of Application) The present invention relates to a method for installing a bottom formwork in a reverse winding method.

(Prior art) As is well known, the reverse winding method is a construction method that is used when constructing underground tanks and starting shafts for shield excavators, etc. are constructed sequentially from the ground side in the depth direction.

When constructing an inner wall using this type of construction method, the inner wall is usually divided into steps in the depth direction, and multiple formworks are used in which the inner wall is divided into steps in the circumferential direction. used.

Then, when the -stage inner wall is formed, the formwork is removed from the mold and set under the existing inner wall while being supported by shoring, and concrete is poured again.

At this time, the method of installing the support for the bottom formwork was
There is a technique disclosed in Japanese Patent No. 9,1015.

The installation method shown in this bulletin is to bury a sheath pipe and hanging anchors with a length equivalent to the height of one concrete pouring of the inner wall concrete, and remove the bottom formwork. First, extend the sheath pipe downward, insert a suspension rod into it from the ground, suspend and support the bottom formwork with the suspension rod, and extend the suspension anchor under the support of this suspension rod. , the lower end of the extended hanging anchor is fixed to the bottom formwork.

However, the installation method disclosed in the above publication has the following technical problems.

(Problem to be Solved by the Invention) In other words, in the installation method disclosed in the above publication, the bottom formwork is suspended and supported by a hanging rod, and the hanging anchor is extended under the support of this hanging rod. Although it will be lifted by a means other than the hanging rod, in the reverse winding method where the height of the casting is high, the length of this hanging anchor will be long and the weight will also be heavy. The work of hoisting this becomes troublesome.

To solve this problem, using the installation method described in the above publication, it is possible to extend the suspension anchor by lifting it with a suspension rod before extending the sheath pipe, but since the suspension rod is not flexible, it is difficult to There is a problem in that a long hanging anchor cannot be pulled to the bottom side of the inner wall.

This invention was made in view of these conventional problems, and its purpose is to provide a bottom form in the reverse winding method that allows easy retraction and extension of the hanging anchors that fixedly support the bottom form. The purpose is to provide a method for installing the frame.

(Means for Solving the Problems) In order to achieve the above object, the present invention provides an inner winding wall in which a plurality of sheath pipes and hanging anchors are buried in the inner periphery of the earth retaining wall, which are successively staged from ground level in the depth direction. In the reverse winding method, in which one stage of the inner wall is formed, the bottom formwork is demolded, and the hanging anchor is extended and the reinforcing bars are arranged under the support of the wire pushed through the sheath pipe. The method is characterized in that the bottom formwork is then lifted up by the wire, and is supported by being locked and fixed to the lower end of the extended hanging anchor.

(Operations and Effects of the Invention) According to the bottom form installation method in the reverse winding method with the above configuration, the wire inserted into the sheath pipe is flexible, so the long hanging anchor is placed on the lower surface of the inner winding wall. In addition to being retractable, extension work can be performed with the hanging anchor supported by wire.

(Embodiments) Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 shows an embodiment of a method for installing a bottom form in the reverse winding method according to the present invention.

This figure shows the process from the time when the upper inner winding 912 has already been formed on the inner periphery of the retaining wall 10 to the setting of a formwork to form the lower inner winding wall 12a below it.

Inside the upper inner winding wall 12, a plurality of hollow sheath pipes 14 are arranged in the vertical direction. A plurality of hanging anchors with threads cut into the outer periphery 16. Inner and outer wall reinforcing bars 18 and 20, which are a combination of vertical and horizontal bars in a lattice pattern, are buried, and tie rod anchors 22 are buried in the horizontal direction. It protrudes slightly outward from the lower and inner surfaces, respectively.

Inside each sheath tube 14, a wire 24 is provided.
is inserted, and the wire 24 is supported by a crane installed on the ground (not shown).

The formwork is composed of a separable bottom formwork 26 and side formworks 28, and the side formworks 28 are fixedly supported by tie rod anchors 22.

In setting the formwork, first, as shown in Figure 1 (A),
The bottom formwork 26 is demolded, suspended by wires 24, and installed on the root cutting excavation surface.

Next, the wire 24 is removed from the bottom formwork 26, and as shown in FIG. 1(B), the wire 24 is connected to the outer wall reinforcing bars 20a that have been assembled in advance into a wall shape, and is retracted and lifted by a crane operation on the ground. It is connected and fixed to the lower end of the outer wall reinforcing bar 20 of the inner wall 12 by welding or the like.

When the fixing of the outer wall reinforcing bars 20a is completed, as shown in FIG. The anchor 16 is fixed to the lower end using a joint sleeve 30, and then the inner wall reinforcing bar 8a is lifted up with the wire 24 and fixed to the lower end of the inner wall reinforcing bar 18 of the upper inner winding wall 12.

After this, as shown in FIG. 1(D), the wire 24 is attached to the bottom formwork 26 again, and the bottom formwork 26 is lifted up by crane operation, and fixed to the lower end of the extended hanging anchor 16a. support.

When the bottom formwork 26 is supported by the hanging anchors 16a, the wire 24 is removed from the bottom formwork 26 and inserted into the sheath pipe 14a buried in the lower inner winding wall 12a.

The insertion work at this time is performed by pushing the sheath pipe 14a while it is installed on the root cutting excavation surface.

When the wire 24 has been inserted, its lower end is locked to the lower end of the sheath tube 14a, and the wire 24 is pulled up.
If the upper end of the sheath tube 14a pulled up together with the wire 24 is connected to the lower end of the sheath tube 14 of the upper inner winding wall 12, as shown in FIG. The set is complete.

In the above work process, before supporting and fixing the bottom formwork 26 to the lower end of the suspending anchor 16a, the wire 24 is inserted into the sheath pipe 14a, and the sheath pipe 14a and the bottom form 26 are simultaneously lifted by the wire 24. The sheath pipe 14a may be extended by supporting and fixing the bottom formwork 26 to the lower end of the hanging anchor 16a.

Then, the connection between the side formwork 28 and the tie rod anchor 22 is released, the side formwork 28 is lowered, and the side formwork 28 is combined with the bottom formwork 26, and a new tie rod anchor is installed, thereby completing the setting of the formwork. , concrete pouring is completed.

Now, in the reverse winding method of the present invention, which is performed through the steps described above, the wire 24 inserted into the sheath pipes 14, 14a is flexible, so the long hanging anchor 16a to be extended can be easily attached. It can be drawn to the lower surface side of the inner wall 12, and it can be easily lifted even if the wall reinforcing bars 18.18a and 20.20a arranged on the inner and outer peripheral edges of the inner wall 12 are assembled in advance. This greatly improves construction efficiency.

In addition, a wire 2 used for lifting the bottom formwork 26, etc.
The insertion work No. 4 can be performed by pushing the sheath pipe 14a with the sheath pipe 14a installed on the root cutting excavation surface, not with the sheath pipe 14a extended, so it can be easily done and the sheath pipe 14a can be pulled up with the wire 24. The sheath tube 14, 14a and the wire 24 can be used for a wide variety of operations.

In addition, in the above embodiment, the reinforcing bars 1, 8, and 20 were used that were assembled in advance into a wall shape, but the implementation of the present invention is not limited to this, and they may be assembled one by one. .

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing an embodiment of the reverse winding method according to the present invention in the order of steps. 10・・・・・・・・・・・・Earth retaining wall 12.12
a... Inner wall 14.14a... Sheath pipe 16.16a... Hanging anchor 18.18a... Inner wall reinforcing bar 20.20a... Outer wall reinforcing bar

Claims (1)

[Claims] In the reverse winding method, in which an inner wall in which a plurality of sheath pipes and hanging anchors are buried in the inner circumference of the earth retaining wall is formed in steps from the ground level in the depth direction, a bottom mold is formed after one stage of the inner wall is formed. The frame is removed from the mold, the hanging anchor is extended and reinforcing bars are placed under the support of the wire inserted into the sheath pipe, and then the bottom form is lifted by the wire and the extended hanging anchor is extended. A method for installing a bottom formwork in the reverse winding method, which is characterized by securing and supporting the bottom formwork at the lower end.