JP2003269074A - Extension method of existing tunnel - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an extension method of the existing tunnel capable of economically making widening in the case total extension length is long or even in the case a section is small. <P>SOLUTION: The extension method includes an upper half widening section 20 and a lower half widening section 22, and a widening tunnel 12 including the whole section of the existing tunnel 10 inside thereof is constructed. When the widening tunnel 12 is constructed, a simple protector 24 having an inverted recess section for ensuring the traffic of a vehicle is installed at the inside of a lining layer 14, the excavation of the upper half widening section 20 is carried out before the lower half widening section 22, and a mobile working platform 26 is installed on a bench 28 formed by the preceding excavation in a movable manner along the direction of the axis of the existing tunnel 10. The excavation of the upper half widening section 20 and the fracture removal of side walls 18 of the lining layer 14 are carried out by work from the mobile working platform 26. The excavation of the lower half widening section 22 and the fracture removal of the side walls 18 of the lining layer 14 are carried out by work on roadbeds on the sides of the side walls 18. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for expanding an existing tunnel, and more particularly to a method for expanding the cross section of an existing tunnel while ensuring passage of vehicles.

[0002]

2. Description of the Related Art If an existing tunnel, which has been used for a long time after construction, has a problem such as not satisfying the present construction limit, its cross section may be enlarged. When enlarging the cross section of the existing tunnel, for example, as shown in FIG. 14, the widening tunnel 1 includes the entire cross section of the existing tunnel 2 and the upper half widening portion 1a located above the approximate ceiling of the existing tunnel 2.
There is a case where the width is widened in a form including the lower half widening portion 1b located on the outer side of both sides of the existing tunnel 2.

When constructing such a widening tunnel 1, as shown in FIG. 1, a fixed protector 3 having an inverted concave cross section is installed in an existing tunnel 2, and a vehicle is installed inside the protector 3. And the like, while using the protector 3 as a work scaffold, the excavation machine 4 is mounted on the protector 3 to perform work such as excavation of the upper half widened portion 1a, and the excavation machine 5 running on the roadbed lowers the work. The semi-widened part 1b was excavated.

Such an upper half or lower half widened portion 1a,
In the excavation work of 1b, usually, after excavating the upper half widened portion 1a by the whole line, the lower half widened portion 1b is excavated, or these excavations are simultaneously performed.

However, such a conventional method for expanding an existing tunnel has the following technical problems.

[0006]

That is, in the above-described conventional expansion method, since the heavy equipment such as the excavating machine 4 is mounted on the protector 3 and the protector 3 is used as a work floor, the protector 3 is a member having high rigidity. Was used over the entire line, and as a result, the ratio of steel cost to the total construction was large, which was very uneconomical.

[0007] In addition, such an increase in cost increases as the length of the tunnel increases, and if the length of the fixed protector 3 increases, it takes time to install and the time for traffic regulation increases.

Further, when the cross section of the existing tunnel 2 is small, the cross section of the protector 3 is correspondingly small, and it takes time to replace the heavy equipment on the protector 3, resulting in a significant decrease in construction efficiency. There was also a problem. The present invention has been made in view of such conventional problems, and an object of the present invention is to make it possible to economically widen the width even if the total extension is long or the cross section is small. It is to provide a tunnel expansion method.

[0009]

In order to achieve the above-mentioned object, an upper half widening portion located substantially above a ceiling portion of an existing tunnel and a lower half widening portion located substantially outside both side portions of the existing tunnel. In the expansion method of the existing tunnel for constructing a widening tunnel including the entire cross section of the existing tunnel, a simple protector with an inverted concave section for ensuring the passage of the vehicle is provided inside the lining layer of the existing tunnel. The excavation of the upper half widening part is carried out prior to the lower half widening part, and the movable work gantry can be moved along the axial direction of the existing tunnel on the bench formed by the preceding excavation. Installed in, excavation of the upper half widening part and destruction and removal of the ceiling part of the lining layer by the work from the mobile work gantry,
The excavation of the lower half widened portion and the destruction and removal of the side wall portion of the lining layer are performed by road work outside the side wall portion.

According to the construction method of the existing tunnel thus constructed, the protector ensures only the functions necessary for ensuring the passage of the vehicle, and this is a simple type. Since it is a movable work gantry that can move along the axial direction of the tunnel, the excavation of the upper half widening part is performed prior to the lower half widening part, and it is installed on the bench formed by this preliminary excavation. Great rigidity is not required.

Therefore, even if the total length of the widening tunnel becomes long, the economical efficiency is not deteriorated and the installation can be performed easily, so that the traffic regulation time does not increase so much.

Further, according to the present invention, since the simple protector and the movable work gantry are separated, the degree of freedom in diverting both is increased, and even if the cross-sectional area of the existing tunnel to be widened is small, the movable work can be performed. The gantry can be increased in size, heavy equipment can be replaced on the gantry, and a decrease in construction efficiency can be avoided.

The mobile work gantry is disposed on the face of the face, and is equipped with a front work gantry on which an excavator for excavating the upper half widening section is mounted, and a rear of the front work gantry. It can consist of two blocks: a waiting area for heavy equipment and a rear work gantry used for loading and unloading heavy equipment and materials.

According to this structure, by appropriately selecting the length of the two blocks composed of the front work platform and the rear work platform, the widening work can be performed according to various construction conditions.

At the front end of the front work gantry, it is inserted between the ceiling part of the existing tunnel and the simple protector to prevent crushed material such as excavation scraps and concrete debris from falling forward of the face. It is possible to provide a fall prevention device that can be widened.

According to this structure, since the crushed material is prevented from falling in front of the face by the fall prevention device, it is possible to prevent damage to the simple protector.

The rear work gantry is formed in a two-divided state, and the rear rear work gantry on the rear side can be used for carrying out excavation scrap.

According to this structure, the excavation slip can be carried out smoothly.

The rear work gantry may be provided with a traveling path for vehicle entry such as a dump for dumping and a belt conveyor installation space for dumping for excavation.

According to this structure, the vehicle can be easily placed on or off the rear work gantry, and
It is easy to carry out the drilling scrap.

The rear work gantry is constructed so as to be separable from the front work gantry, and can be independently moved with a heavy machine or the like mounted.

According to this structure, for example, when concrete is sprayed on the widened cross section, unnecessary heavy equipment can be mounted on the loading / unloading gantry and moved rearward so that it can be evacuated and excavated. Separately from this, heavy equipment and materials can be mounted on the loading / unloading gantry.

The dip-preventing device may be provided with an expandable airbag that abuts the inner surface of the lining layer in a widened state and separates from the inner surface of the lining layer in a contracted state.

According to this structure, when the airbag is widened and brought into contact with the inner surface of the existing tunnel, the crushed material can be reliably prevented from falling, and when the airbag is contracted, it is removed from the inner surface of the existing tunnel. Since they are separated from each other, the front protection gantry can be easily moved.

[0025]

BEST MODE FOR CARRYING OUT THE INVENTION Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings. 1 to 13 show an embodiment of a method for expanding an existing tunnel according to the present invention.

The expansion method shown in the figure is applied to the case of constructing the widening tunnel 12 including the entire cross section of the existing tunnel 10 therein, as shown in FIG. The existing tunnel 10 has a lining layer 14 having a substantially horseshoe-shaped cross section, and the lining layer 14 includes an arch-shaped ceiling portion 16 and side wall portions 18 integrally connected to both sides thereof.

The widening tunnel 12 includes an upper half widening portion 20 located above the ceiling 16 of the lining layer 14, and the lining layer 1.
4, the lower half widening portion 2 located outside the side wall portions 18
It consists of 2.

In constructing such a widened tunnel 12, a simple protector 24 and a movable work gantry 26 are used in this embodiment. The simple protector 24 is used to secure the passage of the general vehicle 27, is a low-rigidity member such as a relatively thin steel plate, and has a flat ceiling formed in a reverse concave shape. It is installed inside the layer 14 over the entire length of the portion where the widening work is performed.

The mobile work gantry 26 is used for the existing tunnel 10
In the present embodiment, excavation of the upper half widening portion 20 is performed prior to excavation of the lower half widening portion 22, and the predetermined excavation is performed. It is installed on a bench 28 of length.

In the case of this embodiment, the bench 28 is set at a height level including a part of the upper end side of the ceiling portion 16 of the lining layer 14, but this position is set at the illustrated level. It is not limited, and can be roughly set according to the construction conditions and the shape of the lining layer 14 of the existing tunnel 10.

In the expanding method shown in the present embodiment, an excavator 29 such as a breaker with a breaker can run between the outer surface of the side wall 18 of the existing tunnel 10 and the inner surface of the widening tunnel 12. Space is provided.

In the case of the present embodiment, the movable work gantry 26 is composed of two blocks, a front work gantry 30 and a work gantry 32, and a dip prevention device 36 is arranged on the tip side. .

The fall prevention device 36 is used for the existing tunnel 1
0 is inserted between the lower surface of the ceiling portion 16 and the upper end surface of the simple protector 24 to prevent crushed materials such as excavation scraps and concrete debris from falling in front of the cutting face, and prevent damage to the simple protector 24. As shown in detail in FIG. 6, the airbag 36a and its supporting member 36b are provided.
It has and.

The support member 36b is of a gate type mounted and supported on the tip of the front work gantry 30, and has a flat top plate 3.
The top plate 360b includes a pair of side plates 361b vertically provided at both ends of the top plate 360b. The gate-shaped shape of the support member 360b is the lining layer 1 of the existing tunnel 10.
4 and has a size such that the simple protector 24 can be housed inside thereof.

The top plate 360b is lower than the front work gantry 30 by one step, and the airbag 36 on the upper surface side of this part.
a is arranged. The airbag 36a has an outer shape that widens by injecting air and contracts when air is discharged. In the present embodiment, the semicircular portion 360a having a predetermined width and the semicircular portion 360a are provided. The semicircular portion 360a includes a pair of ears 361a protruding from both ends of the 360a.
The surface opposite to the face is an inclined surface 362a that inclines downward.

The airbag 36a thus constructed is
When this is made into a contracted state, it is inserted between the lining layer 14 and the simple protector 24 together with the support member 36b, and then air is injected to widen it, so that the upper side of the semicircular portion 360a is covered with the lining layer 14a. While contacting the inner surface of the ceiling portion 16 and the ear portion 361a contacting the inner surface of the side wall portion 18 of the lining layer 14, the lining layer 14 and the simple protector 24 can be closed.

When the air bag 36a having such a structure is adopted as the fall prevention device 36, the crushed material can be surely prevented from falling, and when the air bag 36a is contracted,
Since this separates from the inner surface of the existing tunnel 10, the front work gantry 30 can be easily moved.

The front work gantry 30 is arranged on the face side,
An excavator 34 such as a hydraulic breaker that excavates the upper half widened portion 20 and destroys the ceiling portion 16 is mounted, and the details thereof are shown in FIGS. 7 to 13.

The front work gantry 30 shown in these figures is
The main body 30a, the outrigger 30b, the crane rail 30c, and the traveling drive mechanism 30d are provided. Body 3
0a is a plate having a flat upper end, and the excavator 34 is mounted in this portion.

Below the longitudinal end of the main body 30a, a plurality of bogies 30 are shown in detail in FIGS. 8 and 9.
e is attached. The outrigger 30b is shown in FIG.
As shown in FIG. 9 and FIG. 9, a pair of telescopic jacks 30g, each of which is arranged in the vicinity of the front surface of each bogie 30e, has its upper end supported by the lower surface of the main body 30a, and has a seat 30f pivotally attached to its tip. .

The crane rail 30c is used for the traveling drive mechanism 3
0d, the guide rail 3 is moved forward together with the main body 30 and, as shown in detail in FIG.
0h and its supporting portion 30i.

As shown in FIG. 8, the guide rails 30h are longer than the main body 30a, and a pair of guide rails 30h are arranged in parallel at a predetermined interval. Each guide rail 30
The wheels of the bogie 30e are arranged above h.

The traveling drive mechanism 30d includes a drive motor 30j arranged at the center of the lower surface of the main body 30a and a drive motor 30j.
A drive sprocket 30k rotatably supported by j and a pair of rotatably supported tension sprockets 30l disposed on both sides of the drive sprocket 30k and wound around these sprockets 30k, 30l. And a roller chain 30m that has been formed.

One end of the roller chain 30m is fixed to one end of a guide plate 30n provided on the crane rail 30c, extends along the longitudinal direction of the guide rail 30h, and has a chain tensioning device on the rear end side of the guide plate 30n. It is fixed through 30o.

In the traveling drive mechanism 30d configured as described above, the chain tensioning device 30o is used for the roller chain 30m.
Since the chain 30m is wound around the sprockets 30k and 30l when tensioned to a predetermined tension state, the crane rail 30c has a structure supported by the chain 30m.

In such a supporting state, the outrigger 30
When the telescopic jack 30g of b is extended, the seating portion 30f is bottomed, and the guide rail 30h is separated upward,
Since the crane rail 30c is suspended and supported by the roller chain 30m, the drive motor 30
When j is driven to rotate, the lift rail 30c moves to the main body 3
It can be moved back and forth along the longitudinal direction of 0a.

After such back-and-forth movement, when the telescopic jack 30g of the outrigger 30b is contracted to separate the seating portion 30f, the guide rail 30h moves downward and reaches the bottom.

At this time, since the bogie carriage 30e is mounted above the guide rail 30h, when the drive motor 30j is rotationally driven in this state, only the main body 30a is moved forward and backward along the guide rail 30h. be able to.

On the other hand, as shown in FIGS. 1 and 2, the rear work gantry 32 is arranged behind the front work gantry 30 so as to be separable from the gantry 30, and is used as a work scaffold and a waiting place for heavy equipment. Or, it is used for carrying in and out of heavy machinery and materials, and the main body 32a and the multi-zone traveling device 3
2b and a vehicle running path 32c.

The main body 32a is formed in a flat plate shape so that a heavy machine or the like can be placed on the upper part thereof, and the upper end surface thereof is located at substantially the same level as the main body 30a of the front work gantry 30. There is. The multi-zone traveling device 32b is for moving the main body 32a, and is arranged on the side of the main body 32a.

The traveling path 32c eliminates a step between the upper surface of the main body 32a and the traveling surface of a heavy machine, is formed in an inclined surface, and is arranged behind the main body 32a as a pair. By using such a traveling path 32c, it is possible to easily get in the vehicle on the main body 32a and get off the vehicle from the main body 32a, and it is possible to improve the construction efficiency.

When the rear work gantry 32 can be separated from the front work gantry 30 as in this embodiment, for example, when concrete is sprayed on the widened cross section,
Unnecessary heavy equipment can be mounted on the rear work gantry 32 and moved to the rear to evacuate, and the heavy equipment and materials can be separated from the excavation work, etc.
Can be mounted on.

Next, a procedure for constructing the widening tunnel 12 using the mobile work gantry 26 having the above-mentioned structure will be described. When constructing the widening tunnel 12, first, the drainage channel, the electrical circuit, the water pipe, etc. of the existing tunnel 10 are cut, and if necessary, a pre-reinforcing bolt is struck on the face mirror surface, etc. After being shaped, the simple protector 24 is installed over the entire length or a certain section of the existing tunnel 10.

Then, a temporary gantry of the same level as the height of the bench 28 is installed near the wellhead of the existing tunnel 10, and first, the upper half widening section 20 is excavated, and the upper half widening section 20 is excavated by a predetermined length. When the preliminary excavation of the semi-widened portion 20 is performed, the mobile work gantry 26 is installed on the bench 28 formed by this excavation.

In this case, in this embodiment, the movable work gantry 26 and the rear work gantry 32 are separable from each other.
Therefore, only the front work gantry 30 may be installed on the bench 28.

When the movable work gantry 26 is installed, the fall prevention device 36 on the front end side of the front work gantry 30 is inserted between the lining layer 14 of the existing tunnel 10 and the simple protector 24, Air is injected into the air bag 36a to widen it, thereby preventing excavation scraps and concrete debris from falling in front of the cutting face.

Next, the upper half widening portion 2 of the widening tunnel 12
Zero excavations are performed. In this case, as shown in FIG. 1, the upper half widening portion 20 located substantially above the ceiling portion of the existing tunnel 10 has the excavator 34 mounted on the front work gantry 30.
(Breaker) is used for excavation, and this excavator 3
4, the ceiling 16 of the lining layer 14 is destroyed and removed.

When the excavator 34 is mounted on the front work gantry 30, the telescopic jack 30g of the outrigger 30b is extended so that the seating portion 30f abuts and fixes it on the bench 28.
The bogie 30e is placed on the guide rail 30h, and the excavator 34 is placed on the main body 30a in this state.

When excavating the upper half widened portion 20 by the excavator 34, as the excavation work progresses, the drive motor 30j
Is driven to rotate while moving the main body 30a on the guide rail 30h.

The excavation scraps and concrete debris generated at this time are mounted on a dump truck mounted on the rear work gantry 32 and carried out to the outside of the mine, and the excavation of the upper half widening section 20 progresses to the main body 30a. Reach the vicinity of the face of the guide rail 30h, the crane rail 30c of the front work gantry 30 is moved forward.

Crane rail 30c of the front work gantry 30
When the vehicle is moved forward, the excavator 36 on the main body 30a is first moved to the rear work gantry 32 side, and then the telescopic jack 30g of the outrigger 30b is further extended to guide the guide rail 30h to the bench 28. The crane rail 30c is suspended and supported by being separated from above from above.

Then, in this state, the drive motor 30j is rotationally driven to move the crane rail 30c forward, and after this movement, the telescopic jack 30g of the outrigger 30b is contracted to separate the seat portion 30f, By this operation, the guide rail 30h is moved downward,
By landing on the bench 28, the movement to the front side is completed.

In such a state of forward movement, the bogie 30e is mounted on the guide rail 30h. Therefore, when the excavator 34 is mounted again on the main body 30 and the drive motor 30j is rotationally driven, 30a can be moved in the front-rear direction along the guide rail 30h, and in such a state, work such as excavation of the upper half widened portion 20 is restarted.

The front work platform 3 shown in the above embodiment is used.
The moving mechanism using the 0 rail can be replaced with a double-belt type moving mechanism of the rear working gantry 32, and the double-belt moving mechanism of the rear working gantry 32 can be replaced with a rail type moving mechanism. You can also

The movement of the front work gantry 30 as described above is
This operation is repeated a plurality of times as the excavation of the upper half widening portion 20 progresses, and during this moving operation, excavation work of the lower half widening portion 22 is temporarily stopped.

The schematic side wall portion 18 of the existing tunnel 10
The pair of lower half widened portions 22 located on the outside are excavated by an excavator 29 (shader with a breaker) that travels on the roadbed outside the side wall portion 18, and the lining layer 14 is excavated by the excavator 29. The side wall portion 18 of the mobile work gantry 2 is also removed and destroyed.
The excavation work of the upper half widening portion 20 on the 6 and the like is performed later so that the bench 28 of a predetermined length is always formed.

The excavation scrap excavated by the excavator 34 is carried out of the mine by the following means. ． A belt conveyor for carrying out the excavation scrap is installed on the simple protector 24, and the excavation scrap is carried out by this belt conveyor.

.. The rear work gantry 32 is divided into two,
The rear split work yard on the rear side is used for carrying out excavation scrap. ． A belt conveyor is provided which is bent laterally from the rear part of the rear work gantry 32 and extends rearward along the side part of the simple protector 24, and the excavation slip is carried out by this belt conveyor.

When the work such as excavation for a predetermined length is completed, concrete is sprayed onto the excavated surface of the widening tunnel 12 by the spraying robot to form the primary lining layer 50, and the lock bolt 5 is used by using a jumbo or the like.
Place 2

At this time, the spraying robot or jumbo performs the above-mentioned work by lowering the excavator 34, mounting it on the front or rear work gantry 30, 32, and retreating its position as appropriate.

The above-described work such as excavation is sequentially continued over the entire length of the existing tunnel 12 to be widened, and when these works are completed over the entire length, the mobile work gantry 26 is
The unnecessary portions are removed, leaving only the main body of each gantry 30 and 32.

When the secondary lining layer is formed on the primary lining layer 50, the simple protector 24 is removed and the widening tunnel 12 is removed.
The floor slab will be formed, the road surface will be restored, and drainage facilities will be restored to complete the construction.

According to the construction method for expanding an existing tunnel constructed as described above, the protector 24 is guaranteed to have only the functions necessary for ensuring the passage of the vehicle, and the protector 24 has a simple structure and is a gantry for excavation work. Is a movable work gantry 26 that is movable along the axial direction of the existing tunnel 10, the upper half widening portion 20 is excavated prior to the lower half widening portion 22, and the bench 28 formed by the preceding excavation is mounted. Therefore, the protector 24 does not need to have a large rigidity.

Therefore, even if the total length of the widening tunnel 12 becomes long, the economical efficiency is not deteriorated and the installation can be performed easily, so that the traffic regulation time does not increase so much.

Further, in the present invention, since the simple protector 24 and the movable work gantry 26 are separated, the degree of freedom in diverting both is increased, and even if the cross-sectional area of the existing tunnel 10 to be widened is small, The mobile work gantry 26 can be made large, heavy equipment can be replaced on the gantry, and a decrease in construction efficiency can be avoided.

[0076]

As described above in detail, according to the method for enlarging an existing tunnel according to the present invention, it is possible to economically widen the width even if the total length is long or the cross section is small.

[Brief description of drawings]

FIG. 1 is a side view for explaining an implementation state of an embodiment of a method for expanding an existing tunnel according to the present invention.

FIG. 2 is an upper surface explanatory diagram of FIG.

3 is a cross-sectional explanatory diagram of FIG.

FIG. 4 is an enlarged view of a main part of FIG.

5 is a view taken along the line AA of FIG.

6 is a view taken along the line BB of FIG.

FIG. 7 is an enlarged side view of a main part of the front work gantry shown in FIG.

FIG. 8 is an enlarged view of a main part of FIG.

9 is a side view of FIG.

10 is an enlarged view of a main part of FIG.

11 is a side view of FIG.

12 is a side view of a crane rail used for traveling of the front work gantry shown in FIG.

FIG. 13 is an enlarged view of a main part of FIG.

FIG. 14 is an explanatory diagram showing an example of a conventional method for expanding an existing tunnel.

[Explanation of symbols]

10 Existing tunnel 12 widening tunnel 14 Lining layer 16 ceiling 18 Side wall 20 Upper half widening part 22 Lower half widened part 24 Simple protector 26 Mobile work gantry 27 General vehicles 30 Front work gantry 32 Rear work gantry 34 excavator 36 Anti-fall device 36a airbag

   ─────────────────────────────────────────────────── ─── Continued front page    (71) Applicant 000166627             Goyo Construction Co., Ltd.             2-8 Koraku, Bunkyo-ku, Tokyo (71) Applicant 000219875             Tokyu Construction Co., Ltd.             1-16-14 Shibuya, Shibuya-ku, Tokyo (71) Applicant 000195971             Nishimatsu Construction Co., Ltd.             1-20-10 Toranomon, Minato-ku, Tokyo (71) Applicant 000201478             Maeda Construction Industry Co., Ltd.             2-10-26 Fujimi, Chiyoda-ku, Tokyo (71) Applicant 000005924             Mitsui Miike Manufacturing Co., Ltd.             2-1-1 Nihombashi Muromachi, Chuo-ku, Tokyo (72) Inventor Hideto Mashita             6-1 Nambara, Tsukuba City, Ibaraki Prefecture             Civil Engineering Research Institute (72) Inventor Hirohisa Kamata             6-1 Nambara, Tsukuba City, Ibaraki Prefecture             Civil Engineering Research Institute (72) Inventor Junichiro Nakamori             2-15-6 Otsuka, Bunkyo-ku, Tokyo Foundation Law             Human Advanced Construction Technology Center Advanced Construction Technology Research Institute             Inside the laboratory (72) Inventor Michiya Oura             2-15-2 Konan, Minato-ku, Tokyo Co., Ltd.             Obayashi Head Office (72) Inventor Tsuyoshi Fujii             2-15-2 Konan, Minato-ku, Tokyo Co., Ltd.             Obayashi Head Office (72) Inventor Hideki Takeuchi             Tochigi Prefecture Nasu-gun Nishinasuno-cho 4 Ward-cho 1534-1             Goyo Construction Co., Ltd. Technical Research Center (72) Inventor Ichiro Yamamoto             Tochigi Prefecture Nasu-gun Nishinasuno-cho 4 Ward-cho 1534-1             Goyo Construction Co., Ltd. Technical Research Center (72) Inventor Shozo Suzuki             1-16-14 Shibuya, Shibuya-ku, Tokyo Tokyu Construction Co., Ltd.             Inside the company (72) Inventor Satoshi Kimura             Nishimatsuken 1-20-10 Toranomon, Minato-ku, Tokyo             Inside the corporation (72) Inventor Hiroyuki Inoue             In front of 10-26, Fujimi-ni-chome, Chiyoda-ku, Tokyo             Within Ta Construction Industry Co., Ltd. (72) Inventor Atsushi Morita             In front of 10-26, Fujimi-ni-chome, Chiyoda-ku, Tokyo             Within Ta Construction Industry Co., Ltd. (72) Inventor Ryuji Teshima             2-1-1 Nihonbashi Muromachi, Chuo-ku, Tokyo Stocks             Company Mitsui Miike Manufacturing Industrial Machinery Department F-term (reference) 2D054 AA05 AB07 AC20 BA22 DA17

Claims (7)

[Claims] 1. An upper half widening portion located above a general ceiling portion of an existing tunnel, and a lower half widening portion located substantially outside both side portions of the existing tunnel, wherein the entire cross section of the existing tunnel is inside. In the expansion method of the existing tunnel to build the widening tunnel included in, a simple protector with an inverted concave cross section that secures the passage of the vehicle,
Installed inside the lining layer of the existing tunnel, excavating the upper half widening part prior to the lower half widening part, and the movable work gantry on the bench formed by the preceding excavation, the existing Installed movably along the axial direction of the tunnel, excavating the upper half widening part and destructing and removing the ceiling part of the lining layer by work from the movable work gantry, the lower half widening part The method for enlarging an existing tunnel, wherein the excavation and the destruction and removal of the side wall portion of the lining layer are performed by roadside work outside the side wall portion. 2. The movable work gantry is arranged on the face of a face, and has a front work gantry on which an excavator for excavating the upper half widening section is mounted, and a work arranging rear of the front work gantry. The method for expanding an existing tunnel according to claim 1, wherein the method comprises two blocks including a scaffold, a waiting place for heavy equipment, and a rear work gantry used for carrying in and out heavy equipment and materials. 3. The front work gantry is inserted between the ceiling part of the existing tunnel and the simple protector on the tip side thereof so that crushed material such as excavation scraps and concrete debris can fall to the front of the face. The method for expanding an existing tunnel according to claim 2, further comprising a fall prevention device capable of widening and preventing the expansion. 4. The method for expanding an existing tunnel according to claim 2, wherein the rear work gantry is formed in a two-divided state, and the rear split rear work gantry is used for carrying out excavation scrap. 5. The method for enlarging an existing tunnel according to claim 2, wherein the rear work gantry has a traveling path for vehicle entry such as a dump for unloading slips and a belt conveyor installation space for unloading digging slips. 6. The method for expanding an existing tunnel according to claim 2, wherein the rear work gantry is configured to be separable from the front work gantry, and is independently moved with a heavy equipment or the like mounted. 7. The sag prevention device has a widenable airbag that abuts an inner surface of the lining layer in a widened state and separates from the inner surface of the lining layer in a contracted state. The existing tunnel expansion method described in 3.