JPH09217592A - Tunnel lining device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To secure sufficient strength while reducing facility costs and to enhance operability. SOLUTION: A plurality of outwardly-open, curved inner forms 13 are arranged at predetermined intervals and parallel to one another into a ring shape on the interior wall surface 12 of an existing tunnel and securely connected together. A plurality of holding forms 15 are attached along the inner peripheral surfaces of the inner forms 13 connected together into the ring shape, the end faces of the inner forms 13 and the holding forms 15 are pressed and supported by means of pressing rings 25, and under this condition concrete is placed between the interior wall surface 12 of the tunnel and the inner forms 13 to form a tunnel structure 11.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tunnel lining apparatus and a tunnel lining method for lining a tunnel excavated by a tunnel excavator, an inner formwork used for the tunnel lining, and an inner formwork for the tunnel lining. The present invention relates to a tunnel structure constructed by.

[0002]

2. Description of the Related Art FIG. 8 schematically shows a general shield excavator.
FIG. 9 shows an outline of the automatic segment assembling apparatus, and FIG. 10 shows an outline showing the assembled state of the segments.

As shown in FIG. 8, in a shield excavator, an excavator body 101 has a cylindrical shape, and a cutter head 102 is rotatably mounted on a front portion of the excavator body 101. A large number of cutter bits 103 for excavating the ground at the front are fixed to the front surface 102, and can be driven and rotated by a cutter driving motor (not shown). Further, a plurality of shield jacks 104 are arranged in parallel in the excavator main body 101 along a plurality of circumferential directions, and the excavator main body 101 includes the shield jacks 10.
4 extends rearward in the excavation direction of the tunnel excavator, and can be advanced by a reaction force against the segment S assembled on the inner circumferential surface of the tunnel.

[0004] Behind the excavator body 101, an automatic segment assembling device 105, a segment transport device 106, and a perfect circle holding device 107 are provided, and a transport vehicle 108 is connected thereto. This segment automatic assembly device 105
As shown in FIG. 9, a first slide frame 111 is provided on a lift frame 110 that is movable up and down with respect to a support frame 109 connected to the rear part of the excavator body 101, and the second slide frame 111 is movable back and forth. The frame 112 is provided so as to be movable left and right, and the second slide frame 112 is provided.
The segment holding member 113 is provided so as to be swingable in the front, rear, left and right directions.

Accordingly, when a large number of segments S are carried into the existing tunnel, the segments S are transported forward by the segment transporting device 106, and the automatic segment assembling device 105 holds the segments S and holds them in a predetermined group. Then, this segment S is assembled on the inner wall surface of the existing tunnel. The perfect circle holding device 107 presses the inner peripheral surface of the segment S assembled in a ring shape and holds the same in a perfect circle, and connects the adjacent segments S in this state to form the tunnel structure T. . At this time, as shown in FIG. 10, the segments S are closely attached in the circumferential direction and the front-rear direction of the existing tunnel, and the adjacent segments S are connected by the bolts B and the nuts N.

Further, FIG. 11 shows an outline of a lining method for lining concrete directly without using segments.

As shown in FIG. 11, a tail plate 201 having substantially the same shape as the body of the excavator is provided at the rear of the body of the excavator (not shown).
A concrete pressure ring 202 is provided along an inner peripheral surface of the concrete pressure ring 202, and a seal member 203 is attached to an outer peripheral surface and an inner peripheral surface of the concrete pressure ring 202. The concrete pressure ring 202 can be moved behind the existing tunnel by the pressure jack 204. A concrete casting nozzle 205 is provided at the rear of the concrete pressure ring 202, and concrete C supplied from a concrete supply device (not shown) is discharged from the concrete casting nozzle 205. On the other hand, an unillustrated erector device for assembling the movable form F is provided behind the excavator body, and the erector apparatus assembles the movable form F carried into the tunnel at a predetermined position.

Therefore, when the tunnel is excavated and formed by the excavator, the movable form F is assembled in a ring shape by the erector device. The concrete pressure ring 202 is located between the inner wall surface of the tunnel and the movable form F, and is formed between the concrete casting nozzle 205 and the seal member 203 while preventing leakage of concrete into the excavator body. The concrete C is discharged into the formed space to form a tunnel structure.

[0009]

The above-mentioned segment S
In the tunnel structure T (see FIG. 8) using the S, although the rigidity of the tunnel itself is sufficiently secured, the weight of the segment S is large, so that the segment transfer device 106 and the automatic segment assembly device 105 are increased in size. I have no choice but to
The equipment cost will increase, the assembly time will be long, and the positioning accuracy will be troublesome. Also,
Since each segment S is connected by the bolt B and the nut N, there are problems that the cost is high and the assembling time is long.

On the other hand, in the case of a tunnel structure made by placing concrete (see FIG. 11), although the equipment cost is low and the assembly time is short, the rigidity of the tunnel itself is lower than that of the segment use, When reinforced concrete is used, anticorrosion treatment is required and fraud is complicated, and it is difficult to provide a reinforcing member inside the concrete. Further, there is a problem that cracks and voids are easily generated in the tunnel structure, and water leakage and skin fall are induced.

The present invention solves such a problem, and reduces the equipment cost, secures sufficient strength, and improves workability, a tunnel lining apparatus and tunnel lining method, and a tunnel lining method. An object of the present invention is to provide an inner formwork used for the tunnel lining and a tunnel structure constituted by the inner formwork.

[0012]

In order to achieve the above-mentioned object, a tunnel lining device of the present invention is provided with an outer peripheral ring provided along an inner wall surface of an existing tunnel and a predetermined interval on the inner wall surface of the existing tunnel. A plurality of pressing molds attached along the inner peripheral surface of a plurality of inner molds that are arranged side by side in a ring shape and open to the outside, and the outer peripheral surface faces the inner peripheral surface of the outer peripheral ring. And a pressing ring capable of contacting the end faces of the inner mold and the pressing mold, the pressing ring movably supported along the longitudinal direction of the existing tunnel, and the inner ring via the pressing ring. A mold and a pressing mold for pressing and positioning the mold, and concrete placing means for placing concrete between the inner wall surface of the existing tunnel and the positioned inner mold. What you do That.

Therefore, a plurality of inner molds are arranged side by side in a ring shape on the inner wall surface of the existing tunnel excavated by the excavator at predetermined intervals, and a plurality of pressers are provided along the inner peripheral surface of the ring-shaped inner mold. A pressing frame is attached, the pressing ring is brought into contact with the end surfaces of the inner frame and the pressing frame, and a pressing force is applied to the pressing ring rearward in the longitudinal direction of the existing tunnel by the pressing means. Position and support the inner formwork and the presser formwork via the, and in this state concrete is placed between the inner wall surface of the existing tunnel and the inner formwork by concrete placing means, and after the concrete has hardened The lining is done by removing it, and the tunnel structure is formed by repeating this work, and the inner molds arranged side by side in the ring shape and the concrete hardened by casting are tunneled. Will constitute a structure, it is possible to secure a sufficient strength while equipment costs are reduced.

Further, the tunnel lining method of the present invention is such that, for a tunnel having a predetermined cross-sectional shape excavated by an excavator, a plurality of inner walls of the existing tunnel are opened and curved outward at predetermined intervals. The molds are arranged side by side in a ring shape along the circumferential direction, the plurality of inner molds are connected and fixed to each other, and a plurality of pressers are provided along the inner peripheral surface of the plurality of inner molds connected in the ring shape. A mold is attached and the end faces of the inner mold and the press mold are pressed and supported along the longitudinal direction of the existing tunnel by pressing means, and in this state, between the inner wall surface of the tunnel and the plurality of inner molds. It is characterized in that concrete is poured into the to form a tunnel structure.

Therefore, the work is easy and the equipment to be used can be downsized. On the other hand, a plurality of inner molds arranged side by side in a ring shape and the concrete hardened by casting form a tunnel structure. By constructing, the facility cost can be reduced and sufficient strength can be secured.

Further, the inner formwork of the present invention is a box formwork in which side walls are connected to four sides of a plane part formed in a rectangular shape in plan view and curved by a predetermined amount, and the outside is opened. However, a large number of reinforcing protrusions are formed in the box mold.

Therefore, when this inner frame is used as a part of the tunnel structure, the tunnel structure having a sufficient strength can be formed by the box shape and the large number of reinforcing protrusions.

Further, in the tunnel structure of the present invention, a plurality of inner molds which are open outward and curved at predetermined intervals are arranged side by side in a ring shape on the inner wall surface of the excavated tunnel, It is characterized in that concrete is cast between the inner wall surface of the tunnel and a plurality of inner molds.

Therefore, the tunnel structure is composed of a plurality of inner molds arranged side by side in a ring shape and the concrete hardened by pouring, so that the equipment cost can be reduced, but at the same time, it is sufficient. The strength can be secured.

[0020]

Embodiments of the present invention will be described below.

The tunnel structure formed by the tunnel lining device of the present invention comprises a plurality of inner molds which are arranged in a ring shape on the inner wall surface of an existing tunnel and which are open to the outside, and the existing tunnels. It is made of concrete placed between the inner wall surface and a plurality of ring-shaped inner formwork. Therefore, for a plurality of inner molds arranged side by side along the inner wall surface of the existing tunnel, a plurality of presser molds that are attached along the inner peripheral surface to support the plurality of inner molds. Is required.

In the tunnel lining apparatus of the present invention, an outer peripheral ring connected to, for example, the rear portion of the excavator body of the tunnel excavator is provided along the inner wall surface of the existing tunnel. For example, a propulsion jack of a tunnel excavator is provided as a pressing means, and a pressing ring is attached to the tip of the drive rod of this propulsion jack. The pressing ring has an outer peripheral surface that faces the inner peripheral surface of the outer peripheral ring, and an end surface that is in contact with and supported by the end surfaces of the inner mold and the pressing mold. That is,
By extending the drive rod of this propulsion jack, the pressing ring can be moved rearward in the longitudinal direction of the existing tunnel to press and position the inner mold and the press mold.
Further, the outer ring is provided with a concrete pouring nozzle as a concrete pouring means for pouring concrete between the inner wall surface of the existing tunnel and the positioned inner formwork.

Therefore, a plurality of inner molds are arranged side by side in a ring shape on the inner wall surface of the existing tunnel excavated by the excavator at predetermined intervals, and a plurality of pressers are held along the inner peripheral surface of the ring-shaped inner formwork. A mold is attached, and the pressing ring is brought into contact with the end surfaces of the inner mold and the press mold by the propulsion jack, and by pressing, the inner mold and the press mold are positioned and supported through the press ring. In this state, it is discharged from the concrete pouring nozzle and concrete is poured between the inner wall surface of the existing tunnel and the inner formwork. Then, after the concrete is hardened, the pressing form is removed to perform lining, and by repeating this operation, the tunnel structure is formed. Therefore, a plurality of inner molds arranged side by side in a ring shape and the concrete that has been cast and hardened constitute a tunnel structure, which reduces equipment costs and ensures sufficient strength.

The tunnel lining method of the present invention is carried out by using the above-mentioned tunnel lining device. That is, for a tunnel having a predetermined cross-sectional shape excavated by an excavator, a plurality of inner molds curved outward and open at a predetermined interval on the inner wall surface of the existing tunnel are arranged in a ring shape along the circumferential direction. The inner formwork and the presser formwork are attached to each other by attaching and fixing the plurality of inner formwork to each other, and by attaching the plurality of presser formwork along the inner peripheral surface of the plurality of inner formwork connected in a ring shape. Is pressed along the longitudinal direction of the existing tunnel to be positioned and supported, and in this state, concrete is placed between the inner wall surface of the tunnel and the plurality of inner formwork to form a tunnel structure.

Therefore, the work is easy, and the equipment to be used can be downsized. On the other hand, a plurality of inner molds arranged side by side in a ring shape and the concrete hardened by casting form a tunnel structure. By constructing, the facility cost can be reduced and sufficient strength can be secured.

The inner formwork of the present invention constitutes a part of the tunnel structure. That is, the inner formwork has a rectangular shape in a plan view, and a flat surface portion formed by being curved by a predetermined amount so that it can be attached along an inner wall surface of an existing tunnel, and side wall portions are connected to four sides of the flat surface portion. The box form is open to the outside, and a large number of reinforcing projections are formed from the flat surface inside the box form.

Therefore, when this inner frame is used as a part of the tunnel structure, the tunnel structure having sufficient strength can be formed by the box shape and the large number of reinforcing protrusions.

The tunnel structure of the present invention is formed by the above-mentioned inner formwork and concrete. The inner formwork is curved with the outside open, and a plurality of inner formwork are arranged on the inner wall surface of the excavated tunnel at predetermined intervals in the circumferential direction to form a ring shape. Then, the tunnel structure is formed by placing concrete between the inner wall surface of the tunnel and the plurality of inner molds.

Therefore, the tunnel structure is composed of a plurality of inner molds arranged side by side in a ring shape and the concrete hardened by pouring, so that the facility cost can be reduced, but at the same time, it is sufficient. The strength can be secured.

[0030]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a schematic view of a tunnel lining apparatus according to an embodiment of the present invention, FIG. 2 is a schematic view for explaining a lining method by the tunnel lining apparatus of the present embodiment, and FIG. FIG. 7 shows a perspective view of the inner mold used, and FIG. 7 shows a cross section of the inner mold.

As shown in FIG. 1, a tunnel structure 11 formed by the tunnel lining device of the present embodiment has a plurality of inner molds arranged in a ring shape on an inner wall surface 12 of an existing tunnel at predetermined intervals. 13 and concrete 14 that is placed in the space between the inner wall surface 12 of the existing tunnel and the plurality of ring-shaped inner molds 13. Therefore, a plurality of inner molds 13 arranged along the inner wall surface 12 of the existing tunnel are attached along the inner peripheral surface of the inner molds 13 to support the plurality of inner molds 13. The presser mold 15 is required.

In the tunnel lining apparatus of this embodiment, the tail plate 21 of the tunnel excavator (not shown) is used.
An outer peripheral ring 22 is mounted on the inner peripheral portion of the drive rod, and a large number of shield jacks 23 are arranged inside the outer peripheral ring 22 along the circumferential direction. A drive rod extending rearward of the shield jack 23. A pressing ring 25 is attached to the tip of 24. An outer peripheral surface of the pressing ring 25 is positioned so as to face the inner peripheral surface of the outer peripheral ring 22, and a seal member 26 is attached. Further, the pressing ring 25 has two pressing surfaces 25a and 25b formed on the front end surface thereof with a step, and the first pressing surface 25a can contact and support the end surface of the inner formwork 13, The second pressing surface 25b can contact and support the end surface of the pressing formwork 15. Further, two concrete casting nozzles 27a and 27b are provided at the rear end of the outer peripheral ring 22,
The first concrete placing nozzle 27a faces the rear side of the existing tunnel, the second concrete placing nozzle 27b faces the inside of the existing tunnel, and the inner wall surface 12 of the existing tunnel and the inner formwork 13 positioned. Concrete 14 can be placed in between.

By the way, as described above, the inner formwork 13 of the present embodiment is for forming a part of the tunnel structure 11 and is formed of a steel plate. The flat surface portion 13a formed by being curved along the inner wall surface 12 and the side wall portions 13b connected to the four sides of the flat surface portion 13a form a box shape with the outside open, and A large number of stud bolts 13c as reinforcing protrusions are attached by welding.

Here, the operation of the tunnel lining apparatus of this embodiment will be described.

For an existing tunnel excavated by a shield excavator (not shown), first, as shown in FIG.
The shield jack 23 is contracted to form a space between the pressing ring 25 and the inner mold 13 and the press mold 15 assembled together. Then, as shown in FIG. 2, the existing inner formwork 1
3, new inner molds 13 are arranged at a predetermined interval from the inner wall surface 12 so as to be continuous with each other, and the inner molds 13 adjacent to each other in the front and rear are connected and fixed to each other by welding or a one-touch joint. At this time, the other shield jacks 23 arranged side by side in the circumferential direction of the tunnel are in an expanded state, and the inner form frames 13 are sequentially arranged in the circumferential direction in the above procedure to form a ring shape. continue,
As shown in FIG. 3, a plurality of presser molds 15 are attached along the inner peripheral surface of the ring-shaped inner mold 13 and adjacent presser molds 15 are connected to each other by bolts (not shown). At this time, the inner formwork 13 and the presser formwork 15 are positioned slightly offset in the longitudinal direction of the tunnel, so that the inner formwork 1
3 is easy to assemble, and the inner peripheral surface is connected without any step.

When the inner mold 13 and the presser mold 15 are assembled in this way, the shield jack 23 is extended to bring the pressing ring 25 into contact with the end surfaces of the inner mold 13 and the presser mold 15, and By pressing, the inner mold 13 and the press mold 15 are positioned and supported via the pressing ring 25. Further, when the shield jack 23 is extended, the excavator itself advances, and at this time, the concrete pouring nozzle 27
Concrete 14 is discharged from a and 27b, and concrete is press-fitted between the inner wall surface 12 and the inner formwork 13 of the existing tunnel as shown in FIG. When the shield jack 23 extends a predetermined stroke and the excavator itself moves by the width of the inner formwork 13, as shown in FIG. 5, the concrete 14 from the concrete placing nozzles 27a and 27b is moved.
To stop the discharge. By repeating this operation, the tunnel structure 11 is formed.

The pressing formwork 15 attached along the inner peripheral surface of the inner formwork 13 is removed after the concrete 14 hardens, but usually 10 to 10 along the longitudinal direction of the tunnel.
20 pieces are connected. That is, the presser form 15 installed at the end of the tunnel farthest from the excavator.
Is removed by a formwork erector not shown in the figure, and the cycle of transferring it to the front and attaching it to the newly assembled inner formwork 13 is repeated. The presser mold 15 has a cross-sectional structure with sufficiently high rigidity, and exerts a propulsive reaction force by shearing force and frictional force with the inner mold 13. Moreover, since the placing pressure of the concrete 14 is supported by the pressing formwork 15 having high rigidity, the inner formwork 13 itself does not need cross-sectional rigidity or strength to counter the propulsive reaction force or the placing pressure.

The inner frame 13 is not limited to the above-mentioned embodiment, but may be any one as long as the reinforcing protrusion is provided inside the box shape, and the inner frame 13 may have an external force acting on the tunnel structure 11. It can be changed as appropriate. For example,
As shown in FIGS. 6 and 7, the inner formwork 31 has a rectangular shape in plan view and is formed by being curved along the inner wall surface 12 of the existing tunnel. A box-like shape that is open to the outside is formed by the connected side wall portion 31b, and two ribs 31c having a T-shaped cross section are fixed to the inside along the longitudinal direction, and a large number of stud bolts 31d are fixed. Has been done. Therefore, it has sufficient strength against torsional stress. In this way, inside the box form, ribs, stud bolts, wraps, reinforcing bars,
Alternatively, reinforcing bars may be provided on the outer peripheral portion.

Thus, the inner formwork 13 and the concrete 1
When the tunnel structure 11 is lined by 4, the inner wall surface of the existing tunnel is made of the steel plate of the inner formwork 13, so secondary lining for makeup is unnecessary, and depending on the purpose of use of the tunnel. Anti-corrosion treatment and fire resistance treatment are applied. Further, the inner formwork 13 has a structure in which water can be stopped by a sealing material, and therefore, after removing the pressing formwork 15, the sealing material may be inserted and the inner formwork 13 may be fully assembled.

[0041]

As described above in detail with reference to the embodiments, according to the tunnel lining device of the present invention, the inside of the inner formwork arranged in a ring shape at a predetermined interval on the inner wall surface of the existing tunnel. Having a plurality of pressing formwork attached along the peripheral surface,
A pressing ring that can come into contact with the end faces of the inner form and the holding form is provided, and this pressing ring is moved by the pressing means along the longitudinal direction of the existing tunnel so that the inner form and the holding form can be pressed and positioned. In addition, since concrete placing means for placing concrete between the inner wall surface of the existing tunnel and the inner formwork was provided, the inner formwork was arranged in a ring shape and cured. Since concrete and the tunnel structure constitute the tunnel structure, the equipment cost for the lining can be reduced, while sufficient strength can be secured for the tunnel structure.

Further, according to the tunnel lining method of the present invention, a plurality of inner molds are arranged side by side in a ring shape on the inner wall surface of the existing tunnel at a predetermined interval, and a plurality of inner molds connected in the ring shape. Attach multiple presser formwork to the inner surface of
A tunnel structure is formed by placing concrete between the inner wall surface of the tunnel and a plurality of inner molds with the end faces of the inner mold and the press mold being pressed and supported along the longitudinal direction of the existing tunnel. As a result, the lining work can be simplified and the workability can be improved, and the equipment to be used can be downsized.On the other hand, it is possible to strike multiple inner formwork arranged side by side in a ring shape. The concrete that has been set and hardened constitutes a tunnel structure, which reduces equipment costs and ensures sufficient strength.

Further, according to the inner formwork of the present invention, the box formwork which has a rectangular shape in plan view and which has side walls connected to four sides of a flat part formed by being curved by a predetermined amount, is open to the outside. Since a large number of reinforcing protrusions are formed in this box formwork, if this inner formwork is used as a part of a tunnel structure, the box form and a large number of reinforcing protrusions provide sufficient strength. An inexpensive tunnel structure can be formed.

According to the tunnel structure of the present invention,
On the inner wall surface of the excavated tunnel, a plurality of inner molds that are open at the outside and curved at predetermined intervals are arranged side by side in a ring shape along the circumferential direction, and between the inner wall surface of the tunnel and the inner molds. Since the concrete was cast and formed, this tunnel structure is composed of the inner formwork arranged side by side in a ring shape and the concrete that has been cast and hardened, which can reduce the equipment cost. Thus, sufficient strength can be secured.

[Brief description of drawings]

FIG. 1 is a schematic view of a tunnel lining device according to an embodiment of the present invention.

FIG. 2 is a schematic diagram for explaining a lining method by the tunnel lining device of the present embodiment.

FIG. 3 is a schematic diagram for explaining a lining method.

FIG. 4 is a schematic diagram for explaining a lining method.

FIG. 5 is a schematic diagram for explaining a lining method.

FIG. 6 is a perspective view of an inner formwork used for tunnel lining.

FIG. 7 is a cross-sectional view of an inner mold form.

FIG. 8 is a schematic view of a general shield excavator.

FIG. 9 is a schematic view of an automatic segment assembly device.

FIG. 10 is a schematic view showing an assembled state of segments.

FIG. 11 is a schematic view of a lining method by pouring concrete.

[Explanation of symbols]

11 Tunnel Structure 12 Existing Tunnel Inner Wall Surface 13 Inner Form 13a, 31a Plane 13b, 31b Sidewall 13c, 31d Stud Bolt (Reinforcing Protrusion) 14 Concrete 12 Holding Form 21 Tail Plate 22 Outer Ring 23 Shield Jack (Pressing Means) ) 25 pressing ring 26a, 26b concrete pouring nozzle (concrete pouring means)

Claims (4)

[Claims] 1. An outer peripheral ring provided along an inner wall surface of an existing tunnel, and a plurality of inner molds arranged in parallel on the inner wall surface of the existing tunnel at predetermined intervals and open to the outside. A plurality of presser molds provided along the inner peripheral surface thereof, and a presser ring whose outer peripheral surface is positioned to face the inner peripheral surface of the outer peripheral ring and which is capable of contacting the inner mold and the end surface of the presser mold. And a pressing means for movably supporting the pressing ring along the longitudinal direction of the existing tunnel and pressing and positioning the inner frame and the pressing frame via the pressing ring, and an inner wall surface of the existing tunnel. And a concrete pouring means for pouring concrete between the positioned inner formwork and a concrete lining device. 2. With respect to a tunnel having a predetermined cross-sectional shape excavated by an excavator, a plurality of inner mold frames curved outward and open at a predetermined interval on the inner wall surface of the existing tunnel are ring-shaped along the circumferential direction. In parallel with each other, the plurality of inner molds are connected and fixed to each other, and a plurality of presser molds are attached along the inner peripheral surface of the plurality of inner molds connected in the ring shape. The end faces of the frame and the press form are pressed and supported along the longitudinal direction of the existing tunnel by pressing means, and in this state, concrete is placed between the inner wall surface of the tunnel and a plurality of inner forms to form a tunnel structure. A tunnel lining method characterized by forming a body. 3. A box form whose side wall is connected to four sides of a plane part formed in a rectangular shape in plan view and curved by a predetermined amount to form an outside open box, and inside the box form An inner formwork for a tunnel structure, characterized in that a large number of reinforcing protrusions are formed. 4. An inner wall surface of the excavated tunnel is provided with a plurality of inner molds, which are open outward and curved at predetermined intervals, in a ring shape along the circumferential direction. A tunnel structure characterized by being formed by placing concrete between a formwork.