JPH0551929A - Open shield construction and concrete caisson for its construction - Google Patents

Abstract

PURPOSE:To increase the bearing force of ground under a caisson and prevent them from settling by penetrating the caisson vertically with a ground improving rod via penetration holes formed on the upper and lower floor boards of the concrete caisson, and by improving the ground under the caisson. CONSTITUTION:On open shield construction, on the upper floor board 4c and the lower floor board 4d of a concrete caisson 4, a singularity or a plurality of penetration hole or holes 14 are formed, and the caisson 4 is set, and after that, on it, a base machine 16 is set, and the caisson 4 is vertically penetrated with a ground improving rod 17 through the upper and lower floors 4c, 4d via the penetration holes 14. Then, through a constructing procedure for boring start, boring completion, discharge injection start, and the rotational lifting-up of the rod 17, circular column solidifying bodies 15 are created under the caisson 4, and plugs 23 are applied to the penetration holes 14 with mortar or the like. As a result, under construction on the open shield construction, ground under the caisson 4 is improved, and poor subsoil or the underground structure of a large cross-sectional area can be also-prevented from settling after the caisson 4 is set on.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an open shield construction method for constructing an underground structure such as a water supply / sewerage system, a public ditch, a telegraph, a telephone, etc. for laying underground passages, and a concrete box used therefor.

[0002]

2. Description of the Related Art The open shield method is a highly rational method that takes advantage of the open cutting method (open cut method) and the shield method. The outline is shown in FIGS. 4 to 7. In FIG. 1, reference numeral 1 denotes an open shield machine, which is a shield having front, rear, and upper surfaces formed of left and right side wall plates 1a and a bottom plate 1b connected to these side wall plates 1a. It is a machine. In the open shield machine 1, the tip ends of the side wall plate 1a and the bottom plate 1b are formed as blade openings 2, and the propulsion jacks 3 are arranged vertically rearward near the center or the rear end of the side wall plate 1a.

As shown in FIG. 4, the open shield machine 1 is installed in the start pit 8 and the propulsion jack 3 of the shield machine 1 is extended to apply a reaction force to the reaction force wall 9 in the start pit to shield the shield. The machine 1 is moved forward, the first concrete box 4 forming the underground structure is suspended from above, and is set behind the propulsion jack 3 compressed in the tail part of the shield machine 1. Reference numeral 10 in the figure denotes a strut, which is arranged between the propulsion jack 3 and the reaction force wall 9 for adjusting the gap as appropriate. Further, the start pit 8 is composed of a retaining wall, and a part of the retaining wall is cut off with a mirror to start the open shield machine 1. May be given.

Then, the excavator 6 such as a shovel excavates earth and sand from the front surface or the top surface of the open shield machine 1 and discharges it. Simultaneously with or after this soil discharging step, the propulsion jack 3 is extended to advance the shield machine 1. In the case of this advancing process, a pushing angle 7 made of a frame body made of box steel or shaped steel is arranged in front of the concrete box 4. Then, the second concrete box 4 is suspended in front of the first concrete box 4 in the tail portion of the shield machine 1. Hereinafter, the same soil discharging step, advancing step, and setting step of the concrete box 4 are appropriately repeated to sequentially leave the concrete box 4 in the ground in a row along with the forward movement of the open shield machine 1, and further to this concrete box. Backfill 5 is applied to the upper surface of 4, and pavement 12 is applied to the surface.

In this way, when the open shield machine 1 reaches the reaching pit 13, it is removed and the construction is completed.

[0006]

In such an open shield construction method, as described above, the concrete box 4 is
It is suspended in the tail part of the shield machine 1 and goes out of the tail part with the forward movement of the open shield machine 1 and remains in the ground. It is connected to the concrete box 4 at the rear with a steel rod or a collar. However, if the ground is soft, it may sink. As such a measure, the ground where the concrete box 4 is to be installed by using the chemical solution injection method together with the surrounding ground is improved in advance before the construction, and the shield machine 1 is dug on the improved ground. Concrete box 4
However, the construction cost will rise and the construction period will become longer.

Further, it is technically extremely difficult to improve the ground by the chemical solution injection method even if the bottom plate of the open shield machine 1 is about the height. As a result, the ground improvement portion may hit the open shield machine 1 and may hinder the excavation of the open shield machine 1.

On the other hand, in recent years, underground structures such as underground passages are also required to have a large cross section. However, the ground is weak to embed a concrete box for such large cross section underground structures. At least measures to prevent subsidence of underground structures were required, and there was no suitable open shield construction method other than the full improvement of the surrounding ground.

The object of the present invention is to eliminate the disadvantages of the conventional example, and as a part of it during the process of the open shield construction method, it is possible to increase the bearing capacity of the ground under the concrete box, and to prevent the settlement easily. It is to provide a construction method and a concrete box used for the method.

[0010]

In order to achieve the above-mentioned object, the present invention provides a propulsion jack inside the left and right side wall plates,
A step of excavating and discharging earth and sand in front of the front or upper surface opening of the open shield machine having the front, rear surface and upper surface opened,
The process of extending the propulsion jack and making the concrete box a reaction force to advance the shield machine, and the step of suspending and setting a new concrete box from above behind the propulsion jack contracted in the tail part of the shield machine. In an open shield method of sequentially burying concrete boxes in a column by repeating the steps as appropriate, the concrete box has through holes formed in the upper floor plate and the lower floor plate, and the rod for ground improvement is formed through the through holes. The gist is to penetrate the concrete box up and down and make ground improvement under the concrete box.

[0011]

According to the present invention, as part of the process of the open shield construction method, the ground can be improved under the concrete box as an underground structure during the construction period, and even if the ground is weak or has a large cross section. Even subterranean structures can be prevented from sinking after laying a box.

[0012]

Embodiments of the present invention will now be described in detail with reference to the drawings. FIG. 1 is an explanatory view showing an embodiment of the open shield construction method of the present invention. First, the concrete box 4 used in the method of the present invention will be described. As shown in FIG. 2, the concrete box 4 has left and right side plates 4 similar to the conventional one.
Although the front and rear surfaces of a, 4b, the upper floor plate 4c, and the lower floor plate 4d are opened, the present invention uses them as the upper floor plate 4c.
The vertical through holes 14 are vertically symmetrically provided in the central portion of the lower floor plate 4d, and the concrete box 4 can be vertically penetrated through the through holes 14.

As shown in FIG. 3, a plurality of the through holes 14 may be provided side by side in the left-right direction or the front-rear direction. Further, although not shown, the through hole 14 may be filled with mortar or the like so as to be closed so that it can be opened easily.

An overall outline of the open shield method is shown in FIGS. 4 to 7 and detailed description thereof will be omitted. However, the present invention is an excavation process, a forward process (excavation process), and concrete in the open shield machine 1. By repeating the setting process of the box 4, the concrete boxes 4 are sequentially left in the ground in a row along with the forward movement of the open shield machine 1, and before the backfilling 5 is performed on the upper surface of the concrete box 4, the high pressure is applied. A cylindrical solidified body 15 is formed on the ground below the concrete box 4 by the jet injection mixing treatment method.

In this high-pressure jet injection mixing treatment method, after excavating to a target depth by a boring machine, an improved material (grout) is injected from the lower end of the rod at an ultrahigh pressure to cut the ground and simultaneously mix and stir the soil particles with the grout. Or
Alternatively, it is a construction method of forming the cylindrical solidified body 15 by replacement, but a grout injection method in which only the high-pressure injection of grout is applied, a grout-air injection method of cutting the soil by injecting the grout at high pressure with an air jet, further,
Water / air injection that injects grout while cutting the ground with high-pressure water jet and air jet to create voids,
There are three types of grout injection methods.

Of these, FIG. 1 shows the case of the JST method of the grout / air injection method. In the figure, 16 is a JST base machine, 17 is its rod, 18 is a submersible pump, 19 is a material mixer, 20 is a hydraulic unit, 21 is a super high pressure pump, 22 is a flow cell, and the base machine 16 is installed on the concrete box 4. Then, the rod 17 is passed through the through hole 14 to pass the upper floor plate 4c and the lower floor plate 4d, and the entire concrete box 4 is vertically penetrated.

In this way, the ground is improved by forming the column-shaped consolidated body 15 under the concrete box 4, and the construction procedure is boring start, boring end,
Injection injection started, rod rotation pulled up, and solidified columnar structure was created. Further, after the formation of the cylindrical solid body 15, the through hole
14 is a mortar or the like to form the stopper 23.

Then, as in the conventional case, backfilling 5 is applied to the upper surface of the concrete box 4, and pavement 12 is applied to the surface thereof.

As described above, the high-pressure jet injection mixing treatment method includes a grout injection method, a water / air injection method, a grout injection method, etc. in addition to the grout / air injection method. In either case, the base machine is a concrete box. The cylindrical solidified body 15 can be formed under the concrete box 4 by installing it on the body 4 and vertically penetrating the entire concrete box 4 through the through hole.

Further, as shown in FIG. 3, if a plurality of through holes 14 are arranged side by side or left and right or side by side, a plurality of columnar consolidated bodies 15 can be formed, and in the case where the concrete box 4 has a large cross section. Is effective in.

[0021]

As described above, the open shield construction method of the present invention is capable of performing ground improvement under a concrete box as an underground structure during a construction period as a part of the process of the open shield construction method, and is soft. It is possible to prevent the subsidence of an underground structure at low cost even if the ground is large or an underground structure having a large cross section.

[Brief description of drawings]

FIG. 1 is an explanatory view showing an embodiment of an open shield construction method of the present invention.

FIG. 2 is a perspective view showing an example of a concrete box used in the open shield method of the present invention.

FIG. 3 is a perspective view showing another example of a concrete box used in the open shield method of the present invention.

FIG. 4 is a vertical sectional side view of a first step showing an outline of an open shield construction method.

FIG. 5 is a vertical sectional side view of a second step showing an outline of the open shield construction method.

FIG. 6 is a vertical cross-sectional side view of a third step showing the outline of the open shield construction method.

FIG. 7 is a vertical sectional side view of a fourth step showing the outline of the open shield construction method.

[Explanation of symbols]

 1 ... Open shield machine 1a ... Side wall plate 1b ... Bottom plate 2 ... Blade 3 ... Propulsion jack 4 ... Concrete box 4a ... Left side plate 4b ... Right side plate 4c ... Upper floor plate 4d ... Lower floor plate 5 ... Backfill 6 ... Excavator 7 … Pushing angle 8… Starting pit 9… Reaction wall 10… Struts 11… Ground improvement 12… Pavement 13… Reaching pit 14… Through hole 15… Cylindrical consolidation 16… Base machine 17… Rod 18… Submersible pump 19… Material mixer 20 ... hydraulic unit 21 ... super high pressure pump 22 ... flow cell 23 ... plugging

Claims (2)

[Claims] 1. A step of digging and discharging earth and sand in front of an opening or a front surface of an open shield machine having front, rear and upper surfaces provided with propulsion jacks inside right and left side wall plates, and extending the propulsion jack. Repeat the process of moving the shield machine forward by using the concrete box as a reaction force and the step of suspending and setting a new concrete box from above behind the propulsion jack that has been compressed in the tail part of the shield machine. In the open shield method of sequentially burying concrete boxes in vertical columns, the concrete box has through holes formed in the upper floor plate and the lower floor plate, and the ground improvement rods of the concrete box are formed through the through holes. An open shield construction method that is characterized in that it penetrates vertically and the ground is improved under the concrete box. 2. A concrete box body having front and rear surfaces opened and comprising left and right side plates, an upper floor plate and a lower floor plate, wherein through holes are provided in the upper floor plate and the lower floor plate so as to vertically penetrate the entire box body. Concrete box for open shield method.