KR101407965B1 - Reinforced Upper Tunnel Using Pre-support Structure and its Construction Method - Google Patents

Abstract

A tunnel top leading guard structure and method of constructing the same are disclosed. In the upper tunnel supporter structure according to the present embodiment, a first reinforcing material is inserted into a plurality of perforated holes formed by a depth measured on the upper part of the main tunnel to be excavated to be bound to a hinge, The first reinforcing member is connected to the grouting hose body. The first reinforcing member is provided with a caulking unit to pass through the grouting hose body to seal the opening of the hole and to expose the excavated cross section of the tunnel. A second reinforcing member having a screw thread at one end thereof is inserted into the hollow stiffener to be coupled to the hinge, and a piercing plate through which the second reinforcing member passes is pressed on the excavating end face, In the present invention,

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a tunnel structure,

More particularly, the present invention relates to a tunnel top leading support structure and a method of constructing the same, and more particularly, to a tunnel top structure for providing structural stability when a soft ground is present on an upper part of a tunnel, And a method of constructing the same.

When the ground on the upper part of the tunnel is composed of soft ground such as weathered rock or weathered soil, the excavation section can easily collapse due to the ground load.

Therefore, in the conventional tunnel method of NATM (New Austria Tunneling Method), prior to excavation of this tunnel, it is necessary to install the support material from the surface of the upper part of the tunnel downward to a certain height of the upper part of the tunnel excavation section, The tunnel was installed up to a certain height on the upper part of the tunnel excavation section upward from the advanced gang, and then the tunnel was excavated based on the advanced gang to enable stable excavation of the NATM tunnel.

Korean Patent No. 10-0740200, 'Sunji Beam Tunnel Construction Method and Apparatus therefor', discloses concrete examples of the installation and grouting method of the above-mentioned prior art support.

However, in the above-described prior art, the preceding support should be protruded downward from the main tunnel excavation surface when the main support is installed. This is because the preceding supporting stiffener has to be pressed by a press plate pressed against the excavation section.

 Therefore, the preceding-stay stiffener interferes with the perforated bits formed at the time of perforation for installation of blasting equipment or perforation for line drilling, and the perforated bits are damaged as well as the stiffener has a serious problem.

In particular, if the pre-support stiffener is broken or bent to reduce the stiffness, and if the pre-support stiffener intersects with the perforated bit, the grout is damaged due to vibration for a considerable period of time and the stiffener is broken or cut at the time of excavation there was.

On the other hand, there is a problem that only one hose for grouting is used, so that the pressure grouting is not uniformly applied to the entire reinforcing section.

Registration No. 10-0740200 (Date of Publication 2007. 07. 18)

SUMMARY OF THE INVENTION The object of the present invention is to effectively reinforce the soft ground of the tunnel without interfering with the reinforcement of the preceding support when the tunnel is excavated and to prevent the reinforcement from being damaged by the fatigue of the long term, And a method of constructing the same.

According to one aspect of the present invention, a first reinforcing member (11) is inserted into a plurality of perforation holes (H) formed by a depth measured on an upper portion of a main tunnel (1) to be excavated, A hollow stiffener (30) that is bound to a metal (20) and surrounds and hermetically seals the hinge (20) is provided. The first stiffener (11) is coupled to the grouting hose A caulking means 50 is provided to penetrate the grouting hose body 40 so as to seal the opening of the hole H and to open the empty stiffener 30 exposed on the excavation end face 10 of the excavated main tunnel 1 A second reinforcing member 12 having a thread 12a formed at one end thereof is inserted into the hollow stiffener 30 to be coupled to the hinge 20 and the second stiffener 12 Is fixed to the excavation end surface (10) by the fixed head (70).

In addition, the grouting hose body 40 may include a plurality of grouting hoses 41 having different lengths.

The grouting hose body 40 may include an air ejection hose 42 for removing air in the perforation hole H sealed by the caulking means 50.

At least one of the latches 21 through which the first stiffener 11 passes may be fixed to the surface of the hole H at a rear side of the hinge 20.

The insertion guide portion 22 may be formed on the other side of the hinge 20 so that the second stiffener 12 can be inserted easily.

The protruding portion 31 may be formed on the outer circumferential surface of the hollow stiffener 30. The protruding portion 31 may be formed on the outer circumferential surface of the hollow stiffener 30. The protruding portion 31 may be formed at one end of the hollow stiffener 30,

The second reinforcing member 12 may be inserted between the support plate 60 and the fixed head 70 so that the second reinforcing member 12 is thickened toward one side.

A tensile stiffener 90 may be connected to the other end of the first stiffener 11 and fixed to the ground surface.

According to another aspect of the present invention, there is provided a method of constructing a tunnel upper preceding-stage support structure, comprising: drilling (S10) a plurality of perforation holes (H) by a measured depth on a main tunnel (1) to be excavated; A hollow stiffener 30 is attached to the first reinforcing member 11 to which the grouting hose member 40 is coupled and has a hollow stiffener 30 to surround the hinge 20, A first stiffener inserting step (S20) for inserting the first stiffener; A caulking step (S30) of sealing the opening of the perforation hole (H) with a caulking means (50) through which the grouting hose body (40) penetrates; A grouting step (S40) of grouting the perforation hole (H) using the grouting hose body (40); A main tunnel excavation step (S50) of excavating the main tunnel (1); A second reinforcing member binding step of inserting the second reinforcing member 12 into the empty stiffener 30 and bonding the second reinforcing member 12 to the hinge 20 in a state that one end of the vacant stiffener 30 exposed to the excavating end face 10 is opened (S60); A second stiffener tensioning step S70 of pressing the platen 60 against the excavating end face 10 so as to penetrate the second stiffener 11 and fixing the platen 60 with the fixing head 70; And an empty stiffener filling step (S80) for grouting the inside of the empty stiffener (30).

The reinforcing pipe 13 is inserted into the perforation hole H after the perforation step S10 so that the first reinforcing member 11 is inserted into the reinforcing pipe 13, Step S11).

The method may further include a first stiffener fixing step (S21) of exposing the other end of the first stiffener (11) to the ground surface after the first stiffener insertion step (S20) and fixing the other end of the first stiffener (11) to the structure.

And a tensile stiffener connecting step (S22) for connecting the tensile stiffener (90) to the other end of the first stiffener (11) after the first stiffener inserting step (S20); And a tensile stiffener fixing step (S41) of exposing the tensile stiffener (90) to an earth surface and then fixing the tensile stiffener (90) to the structure after the grouting step (S40).

According to the present invention, since the first reinforcing member is installed outside the tunnel and the second reinforcing member is coupled to the first reinforcing member using the hinge after the tunnel is excavated, It is possible to solve the problem of the breakage of the preceding support stiffener due to the tunnel excavation or the problem of the grout being broken off, and the excavation section can be structurally stabilized by being pulled by the second stiffener.

In addition, it is possible to prevent the puncturing bits from being damaged due to no interference with the tunnel bit.

In addition, a plurality of grouting hoses can be provided so as to evenly grout the entire reinforcing section.

On the other hand, there is an advantage that the reinforcing material is not damaged by the long-term fatigue despite the curvature of the excavated cross section.

FIG. 1A is a cross-sectional view showing a method of reinforcing on the ground surface among conventional prior art support installation methods. FIG.
FIG. 1B is a cross-sectional view showing a method of reinforcing a conventional leading guard installation method in an advanced gang. FIG.
2 is an exploded view of the uppermost supporter structure of a tunnel according to the present invention.
FIG. 3A is a cross-sectional view of a preceding support structure provided on a ground surface before tunneling according to an embodiment of the present invention; FIG.
FIG. 3B is a sectional view showing a preceding support structure after tunnel tunneling according to an embodiment of the present invention; FIG.
FIG. 3c is a cross-sectional view showing a preceding guard structure provided in the advanced gang before the tunnel excavation according to an embodiment of the present invention. FIG.
FIG. 4 is a sectional view showing a preceding guard structure installed in an advanced gang during grouting according to an embodiment of the present invention. FIG.
5 is a cross-sectional view of the uppermost supporter structure of a tunnel according to an embodiment of the present invention after construction.
FIG. 6 is a block diagram of a method for constructing a supersonic tunnel top support structure according to the present invention. FIG.
FIGS. 7 to 13 are detailed views of a method of constructing the uppermost supporter structure of a tunnel according to an embodiment of the present invention.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the following description of the present invention, a detailed description of known configurations and configurations that may unnecessarily obscure the gist of the present invention will be omitted. The same reference numerals are given to the same constituent elements.

FIGS. 1A and 1B are cross-sectional views showing a method of reinforcing on the ground surface and a method of reinforcing in the advanced gang, respectively, among conventional prior art support methods.

In the conventional prior art support method, the preceding support stiffener is required to protrude from the tunnel excavation section before tunnel excavation. The preceding support stiffener is interfered with the main tunnel boring bit to break the perforated bead or the preceding support stiffener, .

FIG. 2 is an exploded view of the uppermost supporter structure according to the present invention.

3A to 5, the uppermost supporter structure of the tunnel according to the present invention will be described in more detail.

According to an embodiment of the present invention, a first reinforcing member 11 having a thread 11a formed at one end thereof is inserted into a perforation hole H formed in a plurality of holes at a depth measured on the upper part of the main tunnel 1 to be excavated So that the hinge 20 is engaged with the thread 11a.

As shown in FIGS. 3A to 3C, the perforation holes H may be formed on the surface of the ground or may be formed from advanced gangways.

On the other hand, the first stiffener 11 is formed into a rod shape, and a screw thread 11a is formed at one end thereof. The thread 11a may be replaced with a clip or a fitting such that the thread 11a is engaged with the hinge 20. The other end of the first stiffener 11 may be cut.

The first reinforcing member 11 may be made of a material capable of maintaining rigidity as a tensile member, but it is preferable to use a steel pipe, a steel bar, a strand, or a geosynthetic fiber.

The first reinforcing member 11 is installed on an upper portion of the tunnel 1 so as not to protrude from the excavation end face 10 and when the perforation hole H is formed on the ground surface, However, it is also possible to fix the other end of the first reinforcing member 11 to the structure by exposing the other end of the first reinforcing member 11 to the ground surface.

The tensile stiffener 90 may be connected to the other end of the first stiffener 11 and fixed to the ground surface.

The hitch 20 is configured to fasten the first stiffener 11 and the second stiffener 12 to be described later so that sufficient strength can be ensured while ensuring easy binding.

The hitches 20 are preferably threaded to engage the first and second stiffeners 11 and 12, but they may also be fastened together with a clip or clip. The first and second stiffeners 11 and 12 may be coupled by forming a female screw and a male screw at one end of the first and second stiffeners 11 and 12, respectively.

At least one of the latches 21 through which the first stiffener 11 passes may be fixed to the surface of the hole H at a rear side of the hinge 20.

That is, even if the hinge 20 receives a tensile force through the first stiffener 11, the hanger 21 will bear a part of the tensile force, thereby preventing the hinge 20 from being released by the tensile force.

The insertion guide portion 22 may be formed on the other side of the hinge 20 so that the second stiffener 12 can be inserted easily. The insertion guide portion 22 is narrowed in a direction in which the second reinforcing member 12 is inserted so that the insertion is guided smoothly.

In the meantime, the tunnel top leading edge support structure of the present invention is provided with a hollow stiffener 30 to surround the hinge 20, the first stiffener 11 is coupled with the grouting hose body 40, And a caulking means 50 is provided to seal the opening of the perforation hole H so that the body 40 is penetrated.

The hollow stiffener 30 allows the first stiffener 11 having the hinge 20 to be easily inserted into the hole H and protects the hinge 20 and the first stiffener 11 .

Therefore, at one end of the empty stiffener 30, the tip portion 32 may be formed to facilitate insertion into the perforation hole H, and the protrusion 31 may be formed to increase the rigidity of the outer periphery. The protrusions 31 may be formed in such a manner as to form a bend or protrusion, which not only enhances the rigidity but also increases the adhesive strength during grouting.

On the other hand, at the time of excavating the tunnel, one side end of the empty stiffener 30 is broken and opened, and it is preferable that the synthetic resin material is made of a material that can be broken. In addition, the material of the empty stiffener 30 may be made different, and one side may be made of a highly cracked material such as a synthetic resin material, and the other side may be made of a rigid material such as a steel pipe .

However, before the tunnel is excavated, the other side of the empty stiffener 30 should be sealed to prevent the grout liquid from flowing into the empty stiffener 30.

The grouting hose body 40 may include a plurality of grouting hoses 41 having different lengths, and the grouting hoses 41 may be spaced apart by 2 to 3 m.

The grouting hose body 40 may include an air ejection hose 42 for removing air in the perforation hole H sealed by the caulking means 50.

3A, when the preceding support structure is installed on the ground surface, the caulking means 50 is provided between the first reinforcement 11 and the ground surface, as shown in FIG. 3A. As shown in FIG. 3B, the caulking means 50 should be provided between the empty stiffener 30 and the excavation end of the advanced gangway when the preceding guard structure is installed in the advanced gangway.

When the other end of the first reinforcing member 11 is exposed to the ground surface and fixed to the structure, it is preferable to provide caulking means at a depth close to the ground surface and grouting.

As shown in FIG. 4, when the preceding support structure is installed in the advanced gang, the first caulking means 51 for disposing and the second caulking means 52 for repeated use are used in parallel. Can be effectively performed.

The first caulking means 51 is constructed such that both ends of a bag made of cloth or the like are sealed by a fixing clip 51a and a filling material such as foamed urethane or cement is injected by using the grouting hose 41 to inflate the bag, (H) is sealed.

On the other hand, the second caulking means 52 is composed of a rubber packer and is configured to inflate using pressure or air, and is preferably installed adjacent to the first caulking means. The second caulking means (52) can be recovered and used repeatedly, and the grouting hose body (40) is to pass through the second caulking means (52).

When the preceding guard structure is installed in the advanced gangway, it is preferable that the grouting hose body 40 penetrate the empty stiffener 30.

In the meantime, according to the present invention, the uppermost supporter structure of a tunnel is provided with a thread 12a formed at one end thereof in a state in which one end of the vacant stiffener 30 exposed in the excavation end face 10 of the excavated main tunnel 1 is open, 2 stiffener 12 is inserted into the hollow stiffener 30 and bound to the hinge 20. [

The second stiffener 12 is engaged with the first stiffener 11 after the first stiffener 11 is installed and then the tunnel 1 is excavated.

Although the second reinforcing member 12 is preferably made of the same material and shape as the first reinforcing member 11, the length of the second reinforcing member 12 may be significantly shorter than that of the first reinforcing member, It is sufficient that only a length sufficient to be able to be combined with the present invention is secured.

At this time, the second stiffener 12 is not installed after the excavation of the tunnel 1, but is preliminarily bound to the first stiffener 11, and is inserted together when the first stiffener is inserted to join the second stiffener after the excavation It is also possible to reduce.

The second reinforcing member 12 is wound and inserted into the empty stiffener 30 so that the second reinforcing member 12 is inserted into one end of the empty stiffener 30 opened when the main tunnel 1 is excavated, So that it can be fixed.

In the process of coupling the second stiffener 12 with the hinge 20, the compression force is applied to the excavation end face 10 continuously by applying a tensile force in advance or by using an elastic means such as a spring. .

The reinforcing pipe 13 is inserted into the hole H to insert the first reinforcing member 11 into the reinforcing pipe 13 to improve the reinforcing effect when the tunnel 1 is excavated We can do it.

The reinforcement pipe 13 should not protrude from the excavation end face 10 of the tunnel 1 to prevent interference with the drilled bit and increase the adhesive strength at the time of grouting so that the second reinforcement 12 is fastened It is possible to secure a certain partial structural stability.

Meanwhile, the pressure plate 60 through which the second reinforcing member 12 penetrates is pressed on the excavation end face 10 and fixed by the fixing head 70.

The fixing head 70 can be pulled and fastened to the second reinforcing member 12 or the pressing plate 60 can be pressed to the excavation end face 10 and its shape can be changed according to the use application.

The second reinforcing member 12 may be inserted between the support plate 60 and the fixed head 70 so that the second reinforcing member 12 is thickened toward one side.

The wedge 80 is provided such that the thickness of the wedge 80 is different along the excavation end face 10 so that the second stiffener 12 is linearly tensioned without bending. And may be provided vertically.

Meanwhile, as shown in FIG. 5, the assembled block B may be installed on the excavation end surface 10 and coupled with the support plate 60 to form the excavation surface more stably.

Further, it may be combined with the pressure plate 60 before or after the shotcrete is poured to form a more stable leading-edge support structure.

FIG. 6 is a block diagram of a method of constructing a tunnel top prior art support structure according to the present invention, which includes a block road piercing step S10, a first stiffener insertion step S20, a caulking step S30, a grouting step S40, (S50), a second reinforcing material binding step (S60), a second reinforcing material tensioning step (S70), and an empty stiffener filling step (S80).

7 to 13, a method of constructing the uppermost supporter structure of a tunnel according to the present invention will be described in more detail.

The perforating step S10 is a step of forming a plurality of perforation holes H by a depth measured on the main tunnel 1 to be excavated.

At this time, the perforation hole (H) is excavated so as to protrude from the excavation end face (10) of the main tunnel (1). This is because the empty stiffener 30 is required to protrude from the excavation end face 10 and furthermore a space in which the grout generated in the piercing step S10 and the grout solution mixed with the gravel in the grouting step S40 .

The reinforcing pipe 13 is inserted into the perforation hole H after the punching step S10 so that the first reinforcing member 11 is inserted into the reinforcing pipe 13, And may include step S11.

The first reinforcing material inserting step S20 includes joining the hinge 20 to the first stiffener 11 to which the grouting hose body 40 is coupled and attaching an empty stiffener 30 to surround the hinge 20. [ And inserted into the perforation hole (H).

The first reinforcing material fixing step S21 may include exposing the other end of the first reinforcing material 11 to the ground surface and fixing the first reinforcing material 11 to the structure after the first reinforcing material inserting step S20.

The method may further include a tensile stiffener connecting step (S22) for connecting the tensile stiffener (90) to the other end of the first stiffener (11) after the first stiffener inserting step (S20).

The caulking step S30 is a step of sealing the opening of the perforation hole H with the caulking means 50 through which the grouting hose body 40 penetrates.

At this time, the method of inflating the caulking means 50 is as described above.

The grouting step S40 is a step of grouting the perforation hole H using the grouting hose body 40. [

The grouting hose body 40 uses a plurality of grouting hoses 41 having different lengths. The grouting hoses 41 are used for pressure grouting in multiple stages. When the grouting hoses 41 are removed after the pressure grouting is completed, And the remaining perforation holes (H) except the section are filled with soil or cement.

The perforation hole H is filled with the caulking means 50 before the press grouting and the perforation hole H in the upper part of the caulking means 50 is filled with the cement or cement and then the first reinforcement 11 is inserted The grouted portion may be subjected to pressure grouting.

The method may further include a tensile stiffener fixing step (S41) of exposing the tensile stiffener (90) to an earth surface and fixing the tensile stiffener (90) to the structure after the grouting step (S40) when the tensile stiffener connecting step (S22) is included.

The main tunnel excavation step S50 is a step of excavating the main tunnel 1 after the grouting step S40.

The second reinforcing material binding step S60 is a step of inserting the second reinforcing material 12 into the empty stiffener 30 in a state in which one end of the vacant stiffener 30 exposed in the excavation end face 10 is opened, (20).

The second reinforcing material tensioning step S70 is a step of pressing the platen 60 against the excavating end face 10 so as to penetrate through the second reinforcing member 11 and fixing the platen 60 with the fixing head 70. [

Finally, the empty stiffener filling step (S80) is a step of grouting the inside of the empty stiffener (30). At this time, it is preferable to grout to the excavation end face 10.

When the preceding guard structure is installed on the ground surface as described above, the caulking means 50 must be provided between the first stiffener 11 and the ground surface. When the preceding guard structure is installed in the advanced gang, The caulking means 50 should be provided between the reinforcing member 30 and the excavating end face of the advanced gangway.

In the foregoing detailed description of the present invention, only specific embodiments thereof have been described. It is to be understood, however, that the invention is not to be limited to the specific forms thereof, which are to be considered as being limited to the specific embodiments, but on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention as defined by the appended claims. .

1: Tunnel H: Perforated hole
10: Excavation Section 11: First stiffener
11a, 12a: thread 12: second stiffener
13: reinforcement tube 20: hinge
21: Catch 22: Insertion guide part
30: Empty stiffener 31: Projection
32: tip end portion 40: grouting hose body
41: grouting hose 50: caulking means
60: Platen 70: Fixing head
80: Shrinkage 90: Tensile stiffener
S10: Drilling step S11: Insertion step of reinforcing tube
S20: first stiffener inserting step S21: first stiffener fixing step
S22: Tensile stiffener connecting step S30: Calking step
S40: grouting step S41: tensile stiffener fixing step
S50: tunnel excavation step S60: second reinforcing material binding step
S70: Second Stiffener Tension Step S80: Empty Stiffener Fill Step

Claims (12)

A first reinforcing member 11 is inserted into the perforation holes H formed in the upper portion of the main tunnel 1 to be excavated by a depth measured and bound to the hinges 20, The first reinforcing member 11 is coupled to the grouting hose member 40 so that the caulking member 50 is inserted into the grouting hose member 40 so that the grouting hose member 40 can pass therethrough. And the opening of the perforation hole (H) is closed,
A second reinforcing member 12 having a thread 12a formed at one end of the hollow stiffener 30 exposed at the excavation end face 10 of the excavated main tunnel 1 in an open state is inserted into the hollow stiffener 30 And the piercing plate 60 engaged with the hinge 20 and passing through the second reinforcing member 12 is pressed on the excavation end face 10 and fixed by the fixed head 70. [ Support structure at the top of the tunnel.
The method according to claim 1,
Wherein the grouting hose body (40) comprises a plurality of grouting hoses (41) having different lengths.
The method according to claim 1,
Wherein the grouting hose body (40) comprises an air ejection hose (42) for removing air in the perforation hole (H) sealed by the caulking means (50).
The method according to claim 1,
Wherein at least one brace (21) through which the first stiffener (11) passes is fixed to the surface of the perforation hole (H) on the rear side of the hinge (20).
The method according to claim 1,
Wherein the insertion guide portion (22) is formed on the other side of the hinge (20) so that the second stiffener (12) can be easily inserted.
The method according to claim 1,
Wherein a protrusion (31) is formed on an outer circumferential surface of the hollow stiffener (30) to increase rigidity and a tip portion (32) is formed at one end of the hollow supporter (30) .
The method according to claim 1,
Wherein the second supporter (12) penetrates through between the support plate (60) and the fixed head (70), and a wedge (80) having a shape thicker toward one side is provided.
The method according to claim 1,
And a tensile stiffener (90) is connected to the other end of the first stiffener (11) and fixed to the ground surface.
A drilling step (S10) of forming a plurality of perforation holes (H) at a depth measured on the upper part of the main tunnel (1) to be excavated;
A hollow stiffener 30 is attached to the first reinforcing member 11 to which the grouting hose member 40 is coupled and has a hollow stiffener 30 to surround the hinge 20, A first stiffener inserting step (S20) for inserting the first stiffener;
A caulking step (S30) of sealing the opening of the perforation hole (H) with a caulking means (50) through which the grouting hose body (40) penetrates;
A grouting step (S40) of grouting the perforation hole (H) using the grouting hose body (40);
A main tunnel excavation step (S50) of excavating the main tunnel (1);
A second reinforcing member binding step of inserting the second reinforcing member 12 into the empty stiffener 30 and bonding the second reinforcing member 12 to the hinge 20 in a state that one end of the vacant stiffener 30 exposed to the excavating end face 10 is opened (S60);
A second stiffener tensioning step S70 of pressing the platen 60 against the excavating end face 10 so as to penetrate the second stiffener 11 and fixing the platen 60 with the fixing head 70; And
An empty stiffener filling step (S80) for grouting the inside of the empty stiffener (30);
Wherein the uppermost support structure of the tunnel top is supported by the upper support structure.
10. The method of claim 9,
A reinforcing pipe inserting step of inserting a reinforcing pipe 13 into the perforation hole H after the perforating step S10 so that the first reinforcing member 11 is inserted into the reinforcing pipe 13 S11);
Wherein the uppermost support structure of the tunnel top is supported by the upper support structure.
10. The method of claim 9,
And a first stiffener fixing step (S21) of fixing the other end of the first stiffener (11) to the structure by exposing the other end of the first stiffener (11) after the first stiffener insertion step (S20)
Wherein the uppermost support structure of the tunnel top is supported by the upper support structure.
10. The method of claim 9,
A tensile stiffener connecting step (S22) for connecting the tensile stiffener (90) to the other end of the first stiffener (11) after the first stiffener inserting step (S20); And
A tensile stiffener fixing step (S41) of exposing the tensile stiffener (90) to an earth surface and fixing the tensile stiffener (90) to the structure after the grouting step (S40);
Wherein the uppermost support structure of the tunnel top is supported by the upper support structure.

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