JP2745083B2 - Tunnel construction method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tunnel construction method for digging and building a tunnel.

[0002]

2. Description of the Related Art A conventional tunnel open-cut construction method is shown in FIG.
And FIG. FIG. 3 is a sectional view of the tunnel, and FIG. 4 is a plan view thereof. First, on both sides of the tunnel structure line, the earth retaining wall 2 with the continuous underground wall is installed, and at the same time, the intermediate steel pile 4 is provided substantially in the center of the pit. Next, a road surface girder 6 such as an H-section steel or an I-section steel is supported by the soil retaining member 2 and the intermediate steel pile 4 as supports, and a lining plate 8 is laid thereon. After that, while erection (cutting beam) 10 is erected, groundwater 12
Is pumped by the pumping machines 14, 16, 18 and excavation is advanced by the excavating machine 20. When excavation of the specified depth is completed,
The foundation concrete is cast, the construction of the tunnel structure 60 is advanced from the bottom of the tunnel, and the support 10 is sequentially removed as the tunnel structure 60 rises. When the tunnel structure 60 is completed, the tunnel structure 60 is backfilled with earth and sand. When the backfill approaches the road surface, the lining plate 8 and the road surface receiving girder 6 are removed, and the road surface is restored.

[0003]

However, according to the above-mentioned conventional construction method, since the groundwater 12 in the tunnel is pumped, the groundwater level line 22 around the tunnel in FIG. Such a drop in groundwater level occurs. Due to the decrease in the groundwater level, land subsidence occurs in the ground behind the soil retention. Further, as schematically shown in FIG. 5, before the shoring 10 is erected, the earth retaining part 2 is slightly displaced in accordance with the depth of the tunnel, and the ground subsidence area 28 is enlarged as the displacement area 26 is increased. It will be. Due to these problems,
When the conventional method is used in a place where important structures are close to each other and the groundwater level is high, it is necessary to improve the ground at the backside of the retaining soil by injecting a chemical solution or special cement as an auxiliary method. In addition, when the embankment was sandy, it was necessary to extend the embankment length and improve the soil in the embankment by injecting chemicals and special cement to prevent boiling.
Accordingly, there is a problem that construction costs are high and the construction period is long in order to perform these ground improvement works.

[0004]

The tunnel construction method according to the present invention focuses on the fact that the above-mentioned change in the ground behind the lands is mainly caused by the displacement of the lands and a decrease in the groundwater level, and the preceding underground beam (transverse continuous underground wall) is used. The purpose of the present invention is to eliminate the displacement of earth retaining by the construction of the tunnel, and to construct the tunnel without causing the groundwater level to be lowered by the construction of the underwater excavation. That is, the present invention
On both sides of the tunnel structure line, the earth retaining consisting underground diaphragm walls
In the open-cut tunnel construction method of installing and constructing a tunnel, the counter pressure strength for preventing the displacement of the soil during the soil is described.
The continuous continuous underground wall with a proper spacing in the length direction of the tunnel
The step of installing a continuous underground wall,
After installing the extension wall, excavation above the groundwater level is carried out by a standard method.
Excavation below the groundwater level
A digging step to be performed with filling, and after the digging, filling with the water.
Pile foundation concrete on the bottom of the tunnel
Concrete casting process and the foundation concrete
After the hardening of the water, a water discharging process to discharge the water between
After exiting, remove the tunnel structure from the foundation concrete side
Tunnel that builds and tears down continuous underground wall after completion
And a structure building process .

[0005]

[Action] having a pair pressure strength of the displacement of the earth retaining prior to drilling <br/> cutting between earth retaining provided on both sides of the tunnel structure is prevented
By cross-cutting underground diaphragm walls have been installed, reliably preventing the displacement of the earth retaining by soil pressure regardless depth whether drilling in cross underground diaphragm walls. Drilling below groundwater level
Is a result of the construction of underwater excavation performed by filling the mine with water , so that the groundwater level at the back of the soil does not decrease and the ground deformation such as land subsidence is prevented.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the tunnel construction method according to the present invention will be described below in detail with reference to the drawings. FIG. 1 is a cross-sectional view of a tunnel for explaining one embodiment of the tunnel construction method of the present invention, and FIG. 2 is a plan view thereof.

First, in the same manner as in the conventional construction method, soil retaining members 2 (continuous underground walls) are installed on both sides of the tunnel structure line.

Next, the transverse continuous underground wall 40 (preceding underground beam)
Is installed inside the soil retaining 2. At this time, the H-section steel 4 is buried in a substantially central part of the continuous underground wall 40 as a support for mounting the road surface girder 6 and the lining plate 8. With the H-section steel 4 as a support, a road surface girder 6 is hung, and a lining plate 8 is laid thereon. As shown in FIG.
It is installed so as to be almost orthogonal to. The continuous underground wall 40 is provided in order to prevent the displacement of the earth retaining member 2 and has a predetermined strength enough to withstand the earth pressure of the ground where the tunnel is provided. In addition, the erection distance d is selected to be sufficient to prevent the displacement of the earth retaining member 2.

Next, the excavation work of the tunnel proceeds. Here, earth and sand having a groundwater level of 22 or higher is excavated using the same ground excavation machine as before, and excavation with a groundwater level of 22 or lower is filled with water in a tunnel pit, and excavation is performed underwater using an underwater excavation machine 46. At this time, the water level 12 in the tunnel pit is the same as the ground water level 22 of the ground around the outside of the tunnel pit, and does not change as in the conventional construction method. .

Next, when the excavation is completed, the foundation concrete 50 is poured in water, and after the concrete has hardened, water is drained. The construction of the structure 60 is advanced from, and after the construction is completed, the crossing continuous underground wall 40 is demolished.
Tunnel demolished transverse continuous underground wall substructures 60
To build. Finally, when the tunnel structure 60 is completed,
The top of the tunnel structure 60 is buried with earth and sand, and when the backfill approaches the road surface, the lining plate 8 and the road receiving girder 6 are removed, the road surface is restored, and the work is completed.

[0011]

Effect of the Invention] As described above, according to the tunnel construction method of the present invention, between earth retaining provided on both sides of the tunnel structure, pair pressure strength of the displacement of the earth retaining is prevented prior to drilling Crossing continuous underground wall with
By disposing them at appropriate intervals, the displacement of the earth retaining due to earth pressure can be surely prevented at the transverse continuous ground wall regardless of the excavation depth. Also, groundwater
By position to perform the following drilling underwater excavation filled with water in downhole, it is possible to prevent a drawdown of groundwater, soil improvement and Boiling of prevention such as auxiliary method of subsidence and Boiling like without straining facilities Prevents ground deformation, shortens the construction period of tunnel construction, and enables low-cost construction of tunnels, making it ideal as a construction method when building tunnel structures close to important structures. .

[Brief description of the drawings]

FIG. 1 is a cross-sectional view for explaining one embodiment of a tunnel construction method of the present invention.

FIG. 2 is a plan view for explaining one embodiment of the tunnel construction method of the present invention.

FIG. 3 is a cross-sectional view for explaining a conventional tunnel construction method.

FIG. 4 is a plan view for explaining a conventional tunnel construction method.

FIG. 5 is a cross-sectional view for explaining a state of soil displacement and land subsidence.

[Explanation of symbols]

2 Soil 22 Groundwater level 4 Intermediate steel pile 40 Crossing continuous underground wall 6 Road girder 46 Underwater excavating machine 8 Lining plate 48 Crane truck 12 Tunnel water level 50 Foundation concrete

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Tadashi Sukekawa 807-3, Funaishikawa, Tokai-mura, Naka-gun, Ibaraki Pref. JP-A-51-42328 (JP, A) JP-A-1-121414 (JP, A) JP-A-60-226917 (JP, A)

Claims (1)

(57) [Claims] In an open-cut tunnel construction method in which a tunnel is constructed by installing a soil retaining wall consisting of a continuous underground wall on both sides of a tunnel structure body line, a change of the retaining soil between the soil retaining parts is performed.
The continuous underground wall 40 having the counter pressure strength to prevent
Crossing continuous ground installed at appropriate intervals along the length of the channel
After the middle wall installation step and the installation of the transverse continuous underground wall 40,
Excavation above the sewage level is carried out by conventional methods, and
Excavation below the water level is performed by filling the mine with water.
After the excavation, the tunnel is filled with the water.
Concrete to put foundation concrete 50 on the bottom
After the casting step and the hardening of the foundation concrete 50,
A water discharging step for discharging water between the dome 2 and the water, and after discharging the water,
A tunnel structure 60 is constructed from the concrete foundation side.
After the completion, the transversal continuous underground wall 40 was demolished,
A tunnel structure 60 is provided on the demolished section of the continuous underground wall.
And a tunnel structure building process for building a tunnel .