JPH05156635A - Open shield construction method and concrete caisson used therefor - Google Patents

Abstract

PURPOSE:To increase rigidity so as to prevent the occurrence of defect and cracks in the outer peripheral corner portion and to improve water cut-off capability by covering the outer peripheral corner portions of the front and rear end surfaces of a concrete caisson and their vicinity with steel plates having an L-shaped section to protect the portions. CONSTITUTION:Steel plates 14 having an L-shaped section are installed on the outer peripheral corner portions of the front end portion and the rear end portion of a concrete caisson 4 and their vicinity in such a manner as to wrap the portions from the outside, and the concrete caisson 4 is hung down to be installed. The concrete caissons 4 are joined to each other in such a manner that the vertical plates 14a of the steel plates 14 are pressed to each other and the outer peripheral corner portions are joined by welding 15 the outer periphery. Thus, the concrete caissons 4 are duplicately watertight sealed, internally and externally so as to improve the sealing performance, and the occurrence of breakage and cracks in the corner portions can be prevented.

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. 5 to 8. In FIG. 5, reference numeral 1 is an open shield machine, which is a shield having front and rear surfaces and an upper surface 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. 5, the open shield machine 1 is installed in the starting 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 starting 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 portion 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 portion of the shield machine 1 and, as the open shield machine 1 moves forward, exits from the tail portion and remains in the ground. The concrete box is made of reinforced concrete and receives the reaction force when the propulsion jack 3 is extended to move the shield machine 1 forward.
Even though the pushing angle 7 is arranged at the front portion, a considerable load is applied to the front end thereof, and this portion is likely to undergo split fracture and cracks. Further, many cracks are generated from the corners of the concrete box 4, and the outer peripheral corners are cracked.

In particular, when performing a curve construction, the stroke of the propulsion jacks 3 arranged on the left and right inside the shield machine 1 is made different, and the shield machine 1 is bent and moved forward. Since the load is unevenly distributed, cracks and corners are more likely to occur.

Further, the concrete box 4 is connected to the rear concrete box 4 by a steel rod or the like, but a sealing material is arranged on the joint surface for stopping water. But the propulsion jack 3
If an unbalanced load is applied to the sealing material, the sealing material may be broken. Also, as the diameter of the underground structure to be constructed becomes larger, the diameter of the concrete box 4 also becomes larger and the sealing material is Stopping water is also difficult.

Further, although a steel collar may be arranged at the joint between the concrete boxes 4, it is very troublesome to install the steel collar in the limited space in the shield machine 1. Therefore, workability is poor. Further, the use of such a steel collar is limited to the case of the concrete box 4 having a relatively small diameter.

The object of the present invention is to eliminate the disadvantages of the above-mentioned conventional example, to prevent the occurrence of cracks and the application of corners even when receiving the load for pushing out by the propulsion jack, and to prevent the concrete boxes from interlocking with each other. Since it is possible to easily and completely carry out water with a large cross section, an object of the present invention is to provide an open shield construction method capable of constructing a highly reliable underground structure and a concrete box used therefor.

[0011]

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 the open shield construction method in which the concrete boxes are sequentially buried in a vertical line by repeating the above steps, the concrete box is covered with the steel plate having an L-shaped cross section at the outer peripheral corners of the front and rear end faces and in the vicinity thereof, and is mainly propelled at the steel plate installation portion. The gist of the present invention is to receive a jack load and to weld watertightly the outer peripheral corners of the joint surface between the steel plates between the front end face and the rear end face of the concrete case to be connected to each other.

[0012]

According to the first and third aspects of the present invention, since the concrete box is protected by the steel plate at the outer peripheral corners of the front and rear end faces and in the vicinity thereof, the steel plate enhances the rigidity and the opening. Even if a load for pushing out by the propulsion jack is applied to the side of the face, it is possible to prevent cracks and corners from being applied.

According to the fourth aspect of the present invention, in addition to the above action, the steel plate covers the entire front and rear end faces of the concrete box, so that it is possible to prevent the inner peripheral corners of the front and rear end faces from hanging.

According to the second aspect of the present invention, in addition to the above action, the steel plates are joined to each other when connecting the concrete boxes. Therefore, the outer circumference of the joining surface of the steel sheets is joined from the outside of the concrete box. The corners can be welded to be watertightly sealed, and a connection box with high water shutoff can be obtained.

[0015]

Embodiments of the present invention will now be described in detail with reference to the drawings. First, the concrete box of the present invention will be described. The concrete box 4 is made of reinforced concrete, and as shown in FIG.
It is composed of b, an upper floor plate 4c and a lower floor plate 4d, and the front and rear surfaces form an opening 17.

According to the present invention, the concrete box 4 is
A steel plate 14 having an L-shaped cross section, which is composed of a vertical plate 14a and a flange plate 14b orthogonal to the end, covers the outer peripheral corners of the front and rear end faces and the vicinity thereof.

In the example of FIG. 1, the vertical plate 14a of the steel plate 14 covers the entire front and rear end surfaces of the concrete box 4, and the shape is substantially the same as the shape of the front and rear end surfaces of the concrete box 4. As shown in FIG. 3, the vertical plate 14a may cover the front and rear end surfaces of the concrete box 4 only in the vicinity of the outer peripheral corners.

As described above, the steel plate 14 having an L-shaped cross section is attached so as to wrap the front end portion and the rear end portion of the concrete box 4 from the outside. After the concrete box 4 is manufactured, it is attached so as to cover it. Alternatively, when the concrete box 4 is manufactured, the concrete box 4 can be placed in a concrete form and attached by simultaneous molding during concrete pouring. In case of retrofitting, flat body is welded to each other and cross section L
It may be attached while molding into a letter shape.

The overall outline of the open shield construction method using the concrete box 4 of the present invention is as shown in FIGS. 5 to 8 and the detailed description thereof will be omitted. However, excavation by the open shield machine 1 and concrete By repeating the setting process of the box 4, the concrete box 4 is left in the ground in a row in line with the forward movement of the open shield machine 1, and the back surface 5 of the concrete box 4 is backfilled.

In this case, the concrete box 4 receives a reaction force when the propulsion jack 3 is extended for advancing the shield machine 1, but the outer peripheral corners of the front and rear end faces of the concrete box 4 and the vicinity thereof are cross-sections. Since it is covered with an L-shaped steel plate 14 and the rigidity is increased by the steel plate 14 to form a high-strength portion, even if a considerable load is applied to the front end of the concrete case 4, the outer peripheral corners are broken or split. It does not break and crack. This is also the case when making a curve construction, and the strokes of the propulsion jacks 3 arranged on the left and right inside the shield machine 1 are made different and the shield machine 1 is bent and moved forward. It is possible to prevent the occurrence of cracks and cracks even though the load is uneven.

The concrete box 4 to be hung inside the shield machine 1 is connected to the concrete box 4 previously installed in the shield machine 1 by means of steel rods or long bolts, as shown in FIGS. As described above, when the concrete boxes 4 are connected to each other, the vertical plates 14a of the steel plates 14 come into contact with each other as joint surfaces, so that the outer peripheral corners of the joint surfaces are joined by welding 15 from the outside of the concrete box 4. Watertightly seal.

In the case of the concrete box 4 of the first embodiment shown in FIG. 1, the vertical plate 14a of the steel plate 14 is the concrete box 4
Since it covers the entire front and rear end faces, it is possible to prevent the inner peripheral corners of the front and rear end faces from hanging.

Also, as shown in FIG. 2, a vertical plate of the steel plate 14
14a is welded not only on the outer peripheral corners of the joint surface but also on the inner peripheral side
If they are joined with 16 and sealed inside and outside with double water-tightness, the sealing property becomes higher. Weld the inner peripheral edges of this vertical plate 14a to each other.
When joining at 16, the worker performs welding work from inside the concrete box 4.

[0024]

As described above, the open shield construction method of the present invention and the concrete box used for the same can prevent the outer peripheral corners from being cracked and the occurrence of cracks even when the load for pushing out by the propulsion jack is received. It is possible to construct a highly reliable underground structure.

Further, the water blocking between the concrete boxes can be easily and completely performed even with a large cross section.

[Brief description of drawings]

FIG. 1 is a perspective view showing a first embodiment of a concrete box of the present invention.

FIG. 2 is a vertical cross-sectional side view showing a connected state of the concrete box of the first embodiment of the present invention.

FIG. 3 is a perspective view showing a second embodiment of the concrete box of the present invention.

FIG. 4 is a vertical sectional side view showing a connected state of the concrete box of the second embodiment of the present invention.

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

FIG. 6 is a vertical sectional side view of a second step showing an outline of the open shield construction method.

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

FIG. 8 is a vertical sectional side view of a fourth step showing an outline of the open shield construction method.

[Explanation of symbols]

1 ... Open shield machine 1a ... Side wall plate 1b ... Bottom plate 2 ... Blade 2a ... Sliding cleat plate 3 ... Propulsion jack 4 ... Concrete box 4a ... Left side plate 4b ... Right side plate 4c ... Upper floor plate 4d ... Lower floor plate 5 ... Backfilling 6 ... Excavator 7 ... Push angle 8 ... Start pit 9 ... Reaction wall 10 ... Strut 11 ... Ground improvement 12 ... Pavement 13 ... Reaching pit 14 ... L-shaped cross-section steel plate 14a ... Vertical plate 14b ... Flange plate 15, 16 ... Welding 17 ... Opening

Claims (4)

[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 construction method of sequentially burying concrete boxes in a vertical line, the concrete box is covered with the steel plate having an L-shaped cross section at the outer peripheral corners of the front and rear end faces and in the vicinity thereof, and the propulsion jack load is mainly received at this steel plate installation portion. An open shield construction method characterized by that. 2. A step of digging and discharging earth and sand in front of the front or upper surface opening of an open shield machine having front, rear and upper surfaces provided with propulsion jacks inside the left and right 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 construction method of sequentially burying concrete boxes in a vertical column, the concrete boxes are covered with steel plates having an L-shaped cross section at the outer peripheral corners of the front and rear end faces and in the vicinity thereof, and the front end faces of the concrete boxes to be connected to each other. The rear end surfaces are watertightly sealed by welding the outer peripheral corners of the joint surface of the steel plates to each other. 3. A concrete box for an underground structure, which has front and rear end faces opened as opening faces and is composed of left and right side plates, an upper floor plate and a lower floor plate, and an outer peripheral corner portion of the front and rear end faces and the vicinity thereof with a steel plate having an L-shaped cross section. A concrete box characterized by being covered. 4. The concrete box according to claim 3, wherein the steel sheet having an L-shaped cross section covers the entire front and rear end surfaces of the concrete box.