JPH0291314A - Forming method for opening portion of underground continuous wall - Google Patents

Abstract

PURPOSE:To form an opening portion simply and quickly and intend better efficiency and lower cost of construction by inserting into a drilled cavity for a continuous wall a reinforced cage previously incorporated with a steel-made case, which is large enough to match a destroyed and removed portion, at a preset position. CONSTITUTION:A steel-made case 2, with a scale equivalent to a destroyed and removed portion and the same thickness as an underground continuous wall, is made up in such a manner that a reinforcement 1a is projected from a hollow structure comprising respective face plates 2a-2f provided with reinforced ribs 3 inside, and openings 5, 6 are provided in an upper and lower face plates 2e, 2f and covered with a network structure 7 etc. Then, the case 2 is built at a preset position into a reinforced cage 1 which is suspended down in a cavity 9 for the continuous wall, where concrete is placed while putting sand or broken stones into the case 2 to construct the continuous wall. Then an opening is formed, with the inside of the continuous wall drilled, the exposed case 2 cut and withdrawn, and the broken stones etc. removed.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is directed to a starting shaft in tunnel construction using an underground continuous wall.
The present invention relates to a method for forming an opening in an underground continuous wall for providing an opening through which a shield excavator or the like passes when used to form an access shaft.

[Conventional technology]

When a vertical shaft such as a starting shaft or a destination shaft is formed using an underground continuous wall, an opening through which a shield tunneling machine, etc. passes must be provided in the underground continuous wall immediately before the shield tunneling machine starts or reaches the shaft.

This opening largely penetrates the underground continuous wall in the thickness direction, and in the past, the underground continuous wall was constructed using the normal method, and the reinforced concrete of the continuous wall was removed by a concrete crusher in the part that would be an obstacle for the shield excavator to advance. The method of demolition and removal using a steel reinforcing bar cutting machine was adopted.

[Problem to be solved by the invention]

However, the method of forming openings by crushing reinforced concrete as described above requires a great deal of time and effort, and may have an adverse effect on the diaphragm wall itself.

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for forming an opening in an underground continuous wall, which eliminates the disadvantages of the conventional example, allows the opening to be formed efficiently and quickly, and is inexpensive.

[Means to solve the problem]

In order to achieve the above object, the present invention excavates a groove for a continuous wall, inserts into the groove a reinforcing bar cage in which a steel box of a size corresponding to the part to be demolished and removed is installed in a predetermined position, and then The main idea is to pour concrete inside to form an underground continuous wall, excavate the inner part of the completed underground continuous wall, and then hollow out the steel box to form an opening. .

[Effect]

According to the present invention, when forming an underground continuous wall, the poured concrete does not go inside the steel box, and a reinforced concrete wall is formed outside that part. After the underground continuous wall is completed and the inner part of the underground continuous wall is excavated to form a shaft, this steel box can be used to punch out the underground wall in the thickness direction. It is possible to easily form an opening that penetrates the

〔Example〕

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

First, the reinforcing bar cage used in the construction method of the present invention will be explained.

FIG. 1 is a perspective view showing the main parts of a reinforcing bar cage 1, and 2 in the figure is a steel box. The steel case 2 has a front plate 2a, a rear plate 2b,
A rectangular hollow body consisting of left and right side plates 2c, 2d, a lower plate 2e, and a lower plate 2f, between the front plate 2a and the rear plate 2b, that is, the left and right side plates 2c.

The width of 2d is approximately the same as the thickness of the underground continuous wall to be constructed.

Furthermore, reinforcing ribs 3 are integrally provided on the inside of the front plate 2a, rear plate 2b, etc. so that the box 2 can withstand concrete pressure, earth pressure, water pressure, etc.
, reinforcing bars 1a of the reinforcing bar cage l are placed on the outside of the left and right side plates 2c and 2d.
A flange 4 for connection with is provided protrudingly.

Further, an upper opening 5 is provided at the center position of the upper surface plate 2e and the lower surface plate 2f.
and a lower opening 6, of which the lower opening 6 is covered with a net 7, a sheet, etc. to allow liquid to pass through but not concrete.

By welding the reinforcing bar 1a to the flange 4,
As shown in the figure, such a steel box 2 is installed in advance in a predetermined position of the reinforcing bar cage 1 (a position corresponding to the part of the underground continuous wall to be demolished and removed).

Figures 4 to 11 show each step of the construction method of the present invention.
First, as shown in FIG. 4, a groove 9 for a continuous wall is drilled using an excavator 8, and a stabilizing liquid 10 is filled therein.

Next, as shown in FIG. 5, the reinforcing bar cage 1 incorporating the steel box 2 as described above is suspended and fixed at the cape within the groove 9.
Since the box 2 has an upper opening 5 and a lower opening 6, the stabilizing liquid 10 also enters the box 2 and no buoyant force acts on it.

As shown in FIGS. 6 and 7, the tremie pipe 11 is lowered and concrete 12 is poured into the groove 9.
3, and insert its tip into the upper opening 5 of the steel box 2. When the top of the poured concrete 12 reaches the bottom end of the box 2, pour sand into the box 2 using the crushed stone input pipe 13. Or start adding crushed stone 14.

Thereafter, the concrete 12 is placed while maintaining the top of the sand or crushed stone 14 and the top of the concrete 12 at the same level.

As shown in FIG. 8, when the top of the concrete 12 reaches the upper opening 5 of the box 2 (at this point, the inside of the box 2 is filled with sand or crushed stone 14), the sand or crushed stone 1
4 is stopped, and the crushed stone input pipe 13 is pulled out and removed.

After the crushed stone input pipe 13 is removed, concrete concretion 2 is continued to be placed using the tremie pipe 11 to complete the underground continuous wall 15 (see Fig. 9). In Fig. 9, 16 indicates the underground continuous wall 1
The adjacent element connected to 5 is shown.

When the construction of the continuous wall is completed in this way, the earth and sand in the inner part is excavated to form the shaft 17, but the outer part where the box 2 is located is reinforced by chemical injection etc. 18 as in the conventional construction method. (See Figure 1θ).

When the vertical shaft 17 is formed, the inner surface of the box 2 (front plate 2
a) is exposed, the front plate 2a and reinforcing ribs 3 are cut and removed using a gas cutter or the like to remove internal sand or crushed stones 14, and the rear plate 2b and reinforcing ribs 3 are also cut and removed in the same manner. An opening 19 is formed that penetrates the underground continuous wall 15 in the width direction, and is used as a passage port for a shield excavator or the like.

The steel case 2 may be completely cut and removed to form the opening 19, but if the frame made of the left and right side plates 2c, 2d, the top plate 2es, and the bottom plate 2f are left, this can be used as the reinforcing bar 1a. It can also be used as an integral strength member.

Furthermore, if the required opening 19 spans more than one element of a continuous wall, the steel box 2 is manufactured by dividing it into each element, and the steel box 2 is manufactured in a predetermined position of the reinforcing bar cage 1 of the element (element mutually). (Move it to the joint side) and perform construction using the same method.

In addition, if the length of the steel box 2 is the same as or longer than the length of the element, and there is a concern that it may hinder the wrapping of the concrete 12, a through-hole for inserting a tremie pipe for concrete pouring may be used. A hole is formed in the box 2 using, for example, a steel pipe with an inner diameter larger than the outer diameter of the tremie tube, and the tremie tube 11 is passed through the through hole to form the concrete 12.
All you have to do is pour the concrete.

By the way, if the steel case 2 can resist buoyancy by filling only the stabilizing liquid 1O without putting sand or crushed stone 14 inside, the upper opening 5 of the steel case 2 also has a lower part. It is also possible to block the opening 6 with a rope, sheet, etc. to prevent the concrete 12 from flowing in, and to omit the step of introducing sand or crushed stone 14 using the crushed stone input pipe 13 shown in FIGS. 6 to 8. It is.

〔Effect of the invention〕

As described above, the method for forming an opening in an underground continuous wall of the present invention uses, for example, the underground continuous wall as a starting hole and a reaching hole in tunnel construction, and a shield tunneling machine or the like is installed in this underground continuous wall. When it is necessary to create an opening to pass through, it is possible to easily and quickly form an opening that penetrates through the thickness, there is no risk of reducing the reliability of the underground continuous wall, and the construction cost for tunnel construction is also reduced. It is inexpensive.

[Brief explanation of the drawing]

Fig. 1 is a perspective view showing an example of a reinforcing bar basket used in the construction method of the present invention, Fig. 2 is a longitudinal sectional front view of the reinforcing bars set in a groove, Fig. 3 is a longitudinal sectional side view of the same, and Fig. 4. - Fig. 11 show each step of the construction method of the present invention, Fig. 4 - Fig. 9 are longitudinal sectional front views, and Fig. 10 and Fig. 11 are longitudinal sectional side views. 1... Rebar cage 2... Steel case 2b... Rear plate 2e... Top plate 3... Reinforcement rib 5... Upper opening a... Net body 9... Groove 11 ... Tremy pipe 13 ... Frame plate input pipe 15 ... Underground continuous wall 17 ... Vertical shaft 19 ... Opening 1a ... Reinforcing bars 2a ... Front plate 2c, 2d ... Left and right sides Face plate 2r... Bottom plate 4... Connection flange 6... Lower opening 8... Excavator lO... Stabilizing liquid 12... Concrete 14... Sand or crushed stone 16... Adjacent element 1st...Reinforcement Figure 1

Claims (1)

[Claims] A trench for the continuous wall is excavated, a reinforcing bar cage with a steel box of a size equivalent to the part to be demolished and removed is inserted into the trench, and then concrete is poured into the trench and the construction is carried out underground. A construction method for forming an opening in an underground continuous wall, which is characterized by forming a continuous wall, excavating the inner part of the completed underground continuous wall, and then hollowing out a steel box part to form an opening.