JP2000064326A - Caisson for underground structure construction - Google Patents

Abstract

PROBLEM TO BE SOLVED: To previously prevent the damage of a permeable filter at the time of caisson settling, block the interruption of underground water by caisson, secure natural flowing-down of underground water flow, and protect the permeable filter at the time of caisson settling by using a sheet housing magazine. SOLUTION: In a caisson for underground structure construction, permeable filters 8 are attached to mutually separated and opposed side walls 2, and the permeable filters 8 of both the side walls communicate with each other by a communication means as water guide can be performed. A clearance layer 9 is formed between the permeable filter 8 and the communication means. The communication means is composed of the permeable filter 8. The clearance layer 9 is filled with the permeable filter 8. A screen is arranged between the permeable filter 8 and the clearance layer 9. The outer face of the permeable filter 8 attached to the outer face of the side wall 2 is covered with a protection plate 7 or a sheet. The sheet is wound in a sheet housing magazine provided on the lower part of the side wall, pulled out from the sheet housing magazine, and the permeable filter 8 of the side wall outer face is separated from a ground 5.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a caisson for constructing an underground structure, and more particularly to a caisson having a groundwater flow interruption preventing means used to construct an underground structure such as a continuously extending tunnel.

[0002]

2. Description of the Related Art FIG. 10 shows a conventional caisson for constructing an underground structure, 1 is a caisson continuously connected in a longitudinal direction to form a wall of an underground structure, for example, a tunnel, 2 is a lateral direction. Side walls 3 separated from each other are side walls 2 of each caisson 1.
The bottom edge of 2 is a bottom slab beam and a top slab beam that connect the side walls 2 and 2 to each other. 5 is the ground, and 6 is underwater concrete cast on the ground 5 at the bottom of the caisson 1.

Each of the caisson 1 is constructed separately on the ground, submerged in the ground, and a retaining wall is built between adjacent caisson, and then excavated while preventing groundwater from spouting by ground improvement work or pressure work. After that, the caisson is connected to each other, and the backfill and the retaining wall are removed.

[0004]

However, in the conventional caisson described above, when the caisson is built in the aquifer by the submersible construction method, the caisson hinders the natural flow of groundwater in the ground and the water level at the upstream side. Rises, the water level on the downstream side drops, and there are problems that have a great impact on the surrounding environment, such as land subsidence and well water depletion.

The present invention eliminates such a problem.

[0006]

A caisson for constructing an underground structure according to the present invention is provided with side walls that are spaced apart from each other and face each other, a beam that connects the side walls, and a water-permeable material attached to the outer surfaces of the both side walls. It is characterized by comprising a filter and a communication means for communicating the water permeable filters on the both side walls so that water can be conducted.

A gap layer is formed between the water permeable filter and the communicating means.

[0008] The communication means is characterized by comprising a water permeable filter.

The gap layer is filled with a water permeable filter.

A screen is arranged between the water-permeable filter and the gap layer.

The outer surface of the water permeable filter attached to the outer surface of the side wall is covered with a protective plate or a perforated sheet.

The protection plate can be pulled up to the ground,
The outer surface of the lower end portion is covered with a cover provided on the lower portion of the side wall.

The perforated sheet is wound in a sheet storage magazine provided on the side wall, and the perforated sheet is pulled out from the sheet storage magazine and covers the water permeable filter on the outer surface of the side wall. And

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of the present invention will be described below with reference to the drawings.

In the present invention, as shown in FIGS. 1 to 3, on the outer surface of each side wall 2 of the caisson 1, from the upper part thereof to the upper part of the lower end cutting edge 3, a predetermined width is sequentially applied from the outer side to the inner side. A protective plate 7 such as a thin steel plate, a water permeable filter 8,
A gap layer 9 is formed, and a communication pipe 10 that connects the gap layer 9 of the one side wall 2 facing each other and the gap layer 9 of the other side wall 2 in a water-conducting manner is provided through the side wall 2 and the bottom slab 4a.

Since the caisson for constructing an underground structure of the present invention has the above-mentioned structure, groundwater flows from the high groundwater side to the low groundwater side through the water permeable filter 8, the interstitial layer 9 and the communication pipe 10. It will be able to flow, and even if the caisson is submerged, the natural flow of groundwater can be guaranteed.

The communicating pipe 10 is replaced by the bottom slab 4a,
Alternatively, in addition to this, it may be provided on the top plate beam 4b.
As shown in FIG. 4, the communication pipe 10 may be filled with a water permeable filter 11 made of gravel or the like so as to limit the flow rate of groundwater flowing through the communication pipe 10.

A screen 12 may be inserted between the water permeable filter 8 and the gap layer 9 as shown in FIG.

Further, as shown in FIG. 6, a water permeable filter 13 may be filled in the gap layer 9.

The protective plate 7 on the outside of the water permeable filter 8 is intended to prevent the water permeable filter 8 from being damaged by friction with the ground 5 when the caisson is submerged. It is necessary that 7 is a material having water permeability. Therefore, for example, a perforated plate may be used as the protective plate.

However, there is a possibility that the fine-grained soil of the ground 5 may block this hole during the setting. This clogging especially occurs in the clay layer during the deposition.

Therefore, it is preferable to be able to remove the protective plate 7 after the completion of the deposition.

In addition, when it is possible to remove it in this way, it is possible to use a protective plate without holes.

When the caisson is submerged, the protection plate 7 and the water permeable filter 8 on the outer side of the side wall 2 may come off due to friction with the ground 5, but as shown in FIGS. Through the through hole 14 provided at the bottom of the
This can be prevented by pulling the protective plate 7 inside the side wall 2 by the C cable 15 and fixing it by the fixing metal fitting 16 inside the side wall 2.

As shown in FIG. 7, the outer surface of the lower end portion of the protective plate 7 may be covered by a cover 17 protruding from the lower portion of the side wall 2 by a fixing rebar 16 'embedded in the side wall 2.

8 and 9 show another embodiment of the present invention. In this embodiment, a sheet storage magazine 1 in which a perforated sheet 18 for protection is wound around the lower end of the side wall 2 is stored.
9 is buried and a perforated sheet 18 for protection pulled out from the sheet storage magazine 19 is interposed between the water permeable filter 8 and the ground 5 in place of the protective plate 7, and the perforated sheet for protection is provided according to the settling of the caisson. The seat 18 is extended.
By doing this, the water permeable filter 8 is attached to the ground 5
The protective perforated sheet 18 does not rub against the ground 5 so that it can be made into a very thin plate or made of geotextile material and is not clogged.

According to this embodiment, it is possible to prevent damage to the water permeable filter 8 during caisson sedimentation.

[0028]

As described above, according to the caisson for constructing an underground structure of the present invention, it is possible to prevent the groundwater from being blocked by the caisson submersion and to ensure the natural flow of the groundwater.

If the sheet storage magazine is used, the water permeable filter can be protected when the caisson is settled.

[Brief description of drawings]

FIG. 1 is a vertical sectional front view of a caisson for constructing an underground structure according to the present invention.

FIG. 2 is a vertical sectional front view showing a main part of the caisson shown in FIG.

FIG. 3 is a cross-sectional plan view of a main part of the caisson shown in FIG.

FIG. 4 is a vertical sectional front view showing a main part of a caisson according to another embodiment of the present invention.

5 is a cross-sectional plan view of a main part of the caisson shown in FIG.

FIG. 6 is a cross-sectional plan view showing a main part of a caisson according to another embodiment of the present invention.

FIG. 7 is a vertical sectional front view showing a main part of a caisson according to another embodiment of the present invention.

FIG. 8 is a vertical sectional front view showing a main part of a caisson according to another embodiment of the present invention.

9 is a cross-sectional plan view showing a main part of the caisson shown in FIG.

FIG. 10 is a front view of a conventional caisson for constructing an underground structure.

[Explanation of symbols]

1 Underground structure (caisson) 2 side walls 3 Lower edge 4a Bottom beam 4b Top beam 5 ground 6 underwater concrete 7 Protective plate 8 water permeable filter 9 Gap layer 10 communication tubes 11 Permeable filter 12 screens 13 Permeable filter 14 through holes 15 PC cable 16 Fixing bracket 16 'anchorage rebar 17 cover 18 Perforated sheet for protection 19 sheet storage magazine

Claims (10)

[Claims] 1. A side wall facing each other at a distance from each other, a beam connecting the side walls, a water permeable filter attached to each of the outer surfaces of the both side walls, and a water permeable filter of the both side walls which communicate with each other so as to be able to conduct water. A caisson for constructing an underground structure, characterized by comprising a communication means. 2. The caisson for constructing an underground structure according to claim 1, wherein a gap layer is formed between the water permeable filter and the communicating means. 3. The caisson for constructing an underground structure according to claim 1, wherein the communicating means is a water permeable filter. 4. The caisson for constructing an underground structure according to claim 1, 2 or 3, wherein the gap layer is filled with a water permeable filter. 5. The screen according to claim 1, wherein a screen is arranged between the water permeable filter and the gap layer.
The caisson for constructing an underground structure according to 2, 3 or 4. 6. The underground structure construction according to claim 1, wherein the outer surface of the water permeable filter attached to the outer surface of the side wall is covered with a perforated protection plate. For caisson. 7. The caisson for constructing an underground structure according to claim 6, wherein the protective plate is a perforated sheet. 8. The caisson for constructing an underground structure according to claim 6, wherein the protection plate can be pulled up to the ground. 9. The perforated sheet is wound in a sheet storage magazine provided on the side wall, and the perforated sheet is pulled out from the sheet storage magazine and covers the water-permeable filter on the outer surface of the side wall. The caisson for constructing an underground structure according to claim 7. 10. The structure for constructing an underground structure according to claim 6, further comprising a lower end cover of the protective plate provided on the lower portion of the side wall to cover the outer surface of the lower end of the protective plate. caisson.