JP3278430B2 - Method of forming tunnel support - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to the tunnel支保 to支保the rock drilling walls excavated by a tunnel boring machine
It relates to a method of forming a body .

[0002]

2. Description of the Related Art When a tunnel excavator excavates a tunnel, the excavated tunnel wall surface may fall off or fall down. A ring-shaped support made of H-section steel is assembled along with a lining member such as expanded metal or a wire mesh between the adjacent ring-shaped supports, and is loosened from the tunnel wall surface in the tunnel by the lining member. It forms a shoring that prevents the rock mass from collapsing.

[0003]

However, according to the above-mentioned prior art, since the assembling of the shoring is performed behind a tunnel excavator in which the excavated tunnel wall surface is exposed, a ring-shaped shoring member is required. There is a risk that the bedrock may collapse when assembling or stretching the lining member, which is extremely dangerous and that the work cannot be performed smoothly. For this reason, a rectangular frame formed by stretching a wire mesh body on a rectangular steel frame curved in an arc shape in the circumferential direction of the tunnel is connected circumferentially in the skin plate of the tunnel excavator to form a ring-shaped support body. After assembling, a method of forming a support by sending it to the tunnel excavation wall side has also been proposed.However, since the ring-shaped support body assembled in the skin plate has a smaller diameter than the tunnel excavation wall side, it has been proposed. A gap will be created between the support body and the tunnel excavation wall surface when it is sent out. Such a problem also occurs in the case of a small-diameter ring-shaped support assembled in a tunnel. Therefore, in order to fill the gap, it is necessary to re-form the ring-shaped support body to have a large diameter. However, at present, no specific means for implementing this has been found.

[0004] The present invention has been made in view of such problems, and an object of the present invention is to provide a small-diameter ring-shaped support body assembled in a tunnel excavator by using a plurality of support pieces in a loose portion of rock. It is an object of the present invention to provide a method for forming a support body capable of easily and accurately expanding the diameter of a tunnel excavation wall and supporting the entire surface of a tunnel excavation surface while reliably preventing collapse and surface fall from the surface.

[0005]

According to one aspect of the present invention, there is provided a support piece comprising a rectangular frame curved in an arc shape having a radius of curvature smaller than that of a skin plate of a tunnel excavator. A method of forming a tunnel support body using a plurality of support pieces, wherein a support piece disposed at the center of the lower peripheral wall of the tunnel and a support disposed on both sides of the skin plate in the skin plate of the tunnel excavator. After temporarily assembling the pieces with each other and assembling the other support pieces together to assemble a small-diameter ring-shaped support body, the small-diameter ring-shaped support body moves relative to the tunnel excavation wall side as the tunnel excavator advances. When the small-diameter ring-shaped support is loosely released, the temporary fastening of the small-diameter ring-shaped support is released, and the support pieces that have become separable are pushed in the circumferential direction to expand the small-diameter ring-shaped support. Is expanded, the outer peripheral surface of the enlarged diameter ring 支保 body, characterized in that to close the tunnel excavation wall.

In the invention according to claim 2, the radius of curvature is
Smaller than the radius of curvature of the skin plate of the tunnel excavator
Multiple support pieces consisting of rectangular frames curved in a circular arc shape
Forming a tunnel support using the tunnel support.
Inside the skin plate of the excavator
On both sides in the support plate and skin plate
The support pieces that are arranged are joined so that they can be separated in the circumferential direction.
And connecting the other support pieces together.
After assembling a ring-shaped support with a small diameter, tunnel excavation
A small-diameter ring-shaped support is excavated as the drilling machine advances.
When it is relatively sent to the cut wall side, the small diameter ring-shaped support
The above support which is joined so as to be separable in the circumferential direction of the holder
Small diameter ring shape by pushing and expanding between pieces in the circumferential direction
The support body is expanded in diameter, and the outer peripheral surface of the expanded ring-shaped support body is
It is characterized by close contact with the tunnel excavation wall.

[0007]

The small-diameter ring-shaped support body is formed by connecting a plurality of arc-shaped support pieces having a radius of curvature smaller than that of the skin plate in the circumferential direction of the tunnel. The assembly of the small-diameter ring-shaped support is performed in the skin plate of the tunnel excavator.

At this time, first, one support piece is disposed at the center of the lower peripheral wall of the tunnel, which is exposed below the rear end of the skin plate, and then a support piece for supporting both side walls of the tunnel excavation wall is provided. Opposite joint plates of the support pieces arranged on both sides in the skin plate and the support pieces arranged on the central portion of the lower peripheral wall of the tunnel are joined and temporarily fastened. Further, a support piece for supporting the upper peripheral wall portion of the tunnel excavation wall is interposed between the support pieces on both sides, and the support piece is integrally connected to the support pieces on both sides, whereby the small-diameter ring-shaped support body is connected. Assemble.

After that, when the small-diameter ring-shaped support body is relatively sent to the tunnel excavation wall side in accordance with the excavation of the tunnel excavator, the support pieces are loosened temporarily and separated, and an expansion jack or the like is used. Then, the small-diameter ring-shaped support body is expanded in diameter by pushing and expanding the support pieces in the circumferential direction, and the outer peripheral surface thereof is brought into close contact with the tunnel excavation wall surface, whereby the tunnel excavation wall surface is supported by the support body.

In addition, as described in claim 2, the lower peripheral portion
The support pieces on both sides are temporarily
Without being fastened, they can simply be joined in a circumferentially separable manner.
The small-diameter ring-shaped support
When they are relatively sent to the flannel wall,
Of the small diameter by pushing the support pieces of
The diameter of the ring-shaped support body may be increased .

As described above, a ring-shaped support having a smaller diameter than the skin plate is assembled in the skin plate of the tunnel excavator, and the ring-shaped support is sent to the tunnel excavation wall surface side according to the excavation of the tunnel excavator, and the diameter is increased. Therefore, the ring-shaped support body can be safely and efficiently assembled without being affected by the collapse of the rock on the wall surface of the tunnel excavation surface or the surface falling, and the rear end face of the ring-shaped support body can be connected to the tunnel excavation wall surface. By sending it to the tunnel excavation wall side while keeping it close to the front end face of the expanded ring-shaped support body already installed in the tunnel, it is possible to prevent the rock excavation wall of the tunnel excavation wall from falling into the tunnel even if it looses It is possible to secure the safety of work in the tunnel.

[0012]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a tunnel excavator according to a first embodiment of the present invention;
This shows a state in which the front and rear opposing surfaces are integrally supported on a tunnel excavation wall T excavated by a ring-shaped support body A ′, A ′... The support A 'is a small-diameter ring-shaped support A assembled in the skin plate 11 of the tunnel excavator 10 and is sequentially sent out to the tunnel excavation wall T side according to the excavation of the tunnel excavator 10, and is a diameter expanding means described later. It is formed by expanding the diameter by the expansion jack 5 and pressing it against the tunnel excavation wall surface T.

The tunnel excavator 10 has a support member disposed integrally with the skin plate 11 at the front end opening of the cylindrical skin plate 11 from which the lower peripheral portion of the rear half is cut 19.
A cutter plate 13 rotatably supported by the support member 12 and driven to rotate by a drive motor (not shown) mounted in the support member 12; The skin plate is fixed with the tip
A beam member 14 extending horizontally rearward from the rear end of the skin plate 11 through a central space of the support member 11;
A telescopic front gripper 15 integrally mounted on the upper, lower, left and right sides of the body, and a rear support 16 which can be vertically extended and contracted by a jack 16a projecting downward from the lower surface of the rear end of the beam body 14.
, A rear gripper 17 slidably disposed along the lower surface of the beam body 14, and a propulsion jack 18 connecting the support member 12 and the rear gripper 17.

The skin plate 11 includes a beam member 14.
The rear gripper 17 is integrally fixed to and supported on the outer peripheral surface of the beam body 14 via a connecting frame member 21 and the rear gripper 17 is disposed on the rear side of the beam body 14 projecting rearward from the skin plate 11. A beam receiver 20 slidable relative to the body 14 projects horizontally from both lower sides of the beam receiving wall T toward both sides of the tunnel excavation wall T, and both rear grippers 17, 17 and the rear sides of the support member 12 The parts are connected by the propulsion jacks 18, 18, respectively. The earth and sand excavated by the cutter plate 13 is discharged backward by an appropriate carrying-out means such as a conveyor (not shown).

In the rear end portion of the skin plate 11 of the tunnel excavator 10 constructed as described above, first, as shown in FIG. 3, the tunnel excavation wall surface T whose curvature radius is formed smaller than the curvature radius of the skin plate 11 is formed. A plurality of support pieces 1, 1A, 1B having a certain arc length curved in an arc shape along the circumference are connected in the circumferential direction, and the diameter of the rock is smaller than the diameter of the tunnel excavation wall surface 2 and the rock falls on the outer peripheral surface of the upper half. A ring-shaped support body A having a circular front face formed by stretching the prevention member 2 is formed.
As shown in FIGS. 5 to 7, the support pieces 1 to 1B are longitudinal directions of the front and rear main girders 1a and 1b which are curved along the tunnel excavation wall T in an arc shape having a radius of curvature smaller than the radius of curvature of the skin plate 11. Is made of a steel rectangular frame integrally fixed between the two ends by flat plate-shaped joint plates 1c, 1c. And the support piece 1 disposed along the upper peripheral wall of the tunnel excavation wall T
Has a structure in which a rock-fall prevention member 2 made of a wire mesh in which bar-shaped metal wires are combined in a grid pattern is stretched at the outer peripheral open end of the rectangular frame as shown in FIG.

On the other hand, as shown in FIG. 7, the support piece 1B disposed along the lower peripheral wall portion, which is the bottom of the tunnel excavation wall surface T, is formed of a steel rectangular frame having no rock fall prevention member. . As shown in FIG. 6, the support piece 1A provided between the upper and lower support pieces 1 and 1B and disposed along both side walls of the tunnel excavation wall T is an upper half of a steel rectangular frame. Rock fall prevention member 2 'made of wire mesh
Is stretched. In addition, each support piece 1
Several bolt insertion holes 3 and 4 for connecting supporting pieces adjacent to each other in the tunnel length direction and the circumferential direction are drilled in the main girders 1a and 1b and the joint plate 1c.

Although the small-diameter ring-shaped support A is formed from four support pieces in FIG. 3, a small-diameter ring-shaped support may be formed by combining four or more support pieces. In this case, the rock fall prevention member 2
Support piece 1 at the top and a rock fall prevention member 2
As the intermediate support piece 1A between the lowermost support piece 1B and the lower support piece 1B, the support piece with the rock-fall prevention member 2 and the support piece without the support are vertically combined. In some cases,

In order to assemble the small-diameter ring-shaped support body A in the skin plate 11 of the tunnel excavator 10 using the support pieces 1, 1A, and 1B, first, a steel rectangular frame having no rock-fall prevention member 2 stretched. The supporting piece 1B is placed on the lower peripheral wall of the tunnel excavation wall T exposed at the cutout 19 of the skin plate 11 in the rear part of the skin plate 11. The skin plate 11 does not necessarily need to be formed in a cylindrical shape having a cut-out portion 19 in the lower peripheral portion of the latter half thereof, and at least a shape along the upper peripheral wall portion of the tunnel excavation wall surface T, that is, an arc shape The small-diameter ring-shaped support body A may be assembled on the exposed bottom surface of the tunnel excavation wall surface T in the skin plate 11.

The support piece 1B is disposed with its longitudinal center of the front and rear main girders 1a and 1b received on the central portion of the lower peripheral wall of the tunnel excavation wall T.
c and 1c are oriented in the normal direction from the outer peripheral surface side of the small-diameter ring-shaped support body A to form a surface in the width direction at the same height position toward the center. Further, this support piece 1B is joined and received to the front main girder 1a of the support piece 1B in the existing expanded ring-shaped support body A 'which has already sent the rear main girder 1b to the tunnel excavation wall T side. .

Next, the support pieces 1A, 1A for supporting both side walls of the tunnel excavation wall surface T are sequentially arranged on both sides in the skin plate 11, and the lower joint plate 1c is connected to the joint of the support piece 1B. By joining to the plate 1c, the front and rear main girders 1a, 1b of the support piece 1B are combined with the front and rear main girders 1a, 1b of the support pieces 1A, 1A on both sides in the circumferential direction, and then mutually joined. The bolt holes 4 formed in the joined joint plates 1c, 1c are temporarily fastened with bolts and nuts 3.

Thereafter, the support pieces arranged on both sides
A support piece 1 for supporting the upper peripheral wall of the tunnel excavation wall T is interposed between the upper joint plates 1c, 1c of the support pieces 1A, 1A, and the both-side joint plates 1c, 1c of the support piece 1 are connected to the support pieces 1A, 1A. The bolt holes 4 are connected to the joint plates 1c and 1c, respectively, and the bolt insertion holes 4, 4 communicating with each other are fastened by bolts and nuts 3 to be integrally connected. Note that the joining and connecting work between the support pieces is performed using an erector (not shown) disposed in the skin plate 11.

As described above, the plurality of support pieces 1, 1A, 1B
Are successively joined and connected from the lower peripheral side to the upper peripheral side in the skin plate 11 so that the center is located below the center of the skin plate 11 and the support on the upper peripheral side as shown in FIG. A circular small-diameter ring-shaped support A having a gap between the outer peripheral surface of the piece 1 and the inner peripheral surface of the upper surface of the skin plate 11 and having a radius smaller than the radius of curvature of the skin plate 11 is assembled. When assembled in this manner, the rock-fall prevention members 2, 2 ', which are stretched over the support pieces 1, 1A disposed on the upper and both sides, respectively, are connected to each other, and the upper half of the outer peripheral surface of the small-diameter ring-shaped support A is connected. Is covered. In addition, the support pieces on both sides of the support piece 1B
Instead of temporarily fastening 1A, 1A with the bolts and nuts 3, they may be assembled in a state where they are simply joined in a circumferentially separable manner.

When the ring-shaped support body A having a small diameter is assembled in the skin plate 11 while the tunnel excavator 10 is excavated to excavate a tunnel of a predetermined length, the skin plate 11 moves forward according to the excavation, and the tunnel excavation wall surface is formed. T
A small-diameter ring-shaped support A placed on the bottom surface of the skin plate 11 is relatively sent out from the rear end of the skin plate 11 to the tunnel excavation wall T side.

When the rear half of the ring-shaped support A is sent out from the rear end of the skin plate 11 to the tunnel excavation wall T side by the excavation of the tunnel excavator 10, the lower support piece 1B and both support pieces 1A are provided. As shown in FIGS. 2 and 4, the rear end side between the joint plates 1c, 1c, which are detachably joined to the joint plates 1a and 1a, is expanded in the circumferential direction by the expansion jack 5 to thereby reduce the diameter of the ring-shaped support A. Is enlarged in a tapered shape from the front end to the rear end, and the rear end of the enlarged ring-shaped support body is brought into close contact with the tunnel excavation wall surface T entirely.
If the joint plates 1c and 1c of the support piece 1A and the support piece 1B are temporarily fastened with the bolts and nuts 3, the bolts and nuts 3 are removed so that the joint plates 1c and 1c can be separated. Make it joined.

After expanding the diameter of the rear end side of the small-diameter ring-shaped support body A,
The tunnel excavator 10 further excavates, and according to the excavation, the front half of the ring-shaped support body A is a skin plate until the front end.
When it is relatively sent out from 11 into the tunnel excavation wall T, this time, the lower support piece 1B and both side support pieces 1A,
By expanding the front end side between the joint plates 1c, 1c, which are detachably joined to 1A, in the circumferential direction by the expansion jack 5 in the same manner as described above, the diameter of the ring-shaped support body is increased so as to have the same diameter. Then, the entire outer periphery of the expanded ring-shaped support body A 'is brought into close contact with the tunnel excavation wall surface.

The connecting structure of the joining portion by the expansion jack 5 includes two ends of the inner peripheral surface of the front and rear main beams 1a and 1b of the support piece 1B disposed along the lower peripheral wall of the tunnel excavation wall T, Bracket mounting screw holes 6a, 6b are provided at the lower ends of the inner peripheral surfaces of the front and rear main girders 1a, 1b of the support pieces 1A, 1A disposed along both peripheral wall portions of the tunnel excavation wall surface T.
(Shown in FIGS. 6 and 7) are provided, and brackets 7a and 7b are detachably fixed to these screw holes 6a and 6b by bolts. A structure is employed in which the expansion jack 5 is interposed between the brackets 7a and 7b to be detachably mounted on the brackets 7a and 7b. When the small-diameter ring-shaped support A is assembled in the skin plate 11, the expansion jack 5 is mounted before the small-diameter ring-shaped support A is relatively sent to the tunnel excavation wall T side. May be.

The expansion jack 5 is provided at the front and rear ends of the small-diameter ring-shaped support body A, as described above, with the joint plates 1c, 1c on both sides of the support piece 1B and the support pieces 1A on both sides opposed to these joint plates 1c, 1c. In this case, the expansion jacks 5 and 5 arranged on both sides are simultaneously extended by the same length as shown in FIG. The diameter of the small-diameter ring-shaped support body A is increased.

That is, when the extension jacks 5 on both sides are simultaneously extended by the same length, the lower support piece 1B is deformed in the radially expanding direction with the central portion received on the bottom surface of the tunnel excavation wall T as a fulcrum. Both end portions, which are separated inward from the tunnel excavation wall T, are pressed against both side surfaces of the lower peripheral wall of the tunnel excavation wall T, and the upper support piece 1 and the support piece 1
Support pieces 1A, 1A integrally connected to both end faces of
The lower C-shaped support body portion formed by the upper support piece 1 is lifted upward without being displaced in the circumferential direction from the central portion in the arc length direction of the upper support piece 1 and the both support pieces 1
Fig. 4
As shown in FIG. 7, an expanded ring-shaped support body A 'pressed against the tunnel excavation wall surface T is formed.

Therefore, the rock-fall prevention members 2, 2 'stretched on the outer peripheral surface of the upper half portion of the small-diameter ring-shaped support A are not displaced in the circumferential direction of the tunnel excavation wall T, and are not displaced in the tunnel excavation wall T. The upper excavation wall T is disposed in contact with the inner peripheral wall of the upper half to prevent the rock B on the upper peripheral wall of the tunnel excavation wall from falling or falling. When the small-diameter ring-shaped support A is expanded, the rear end face of the small-diameter ring-shaped support A is expanded first to support the tunnel excavation wall surface T. The diameter is increased while being in contact with the front end face of the body A '. After the diameter expansion, the joint plates 1c, 1c separated from each other are connected by bolts and nuts 3, or concrete is filled, or rigid members are inserted. The rear main girder 1b of the expanded ring-shaped support A ′ is aligned with the front main girder 1a of the existing expanded ring-shaped support A ′ by bolt insertion holes 3, 3 The spaces are connected by bolts and nuts to be integrated.

In the above embodiment, the expansion jack 5 is used as the expansion means, but the expansion jack may be replaced by a push bolt. That is, bolts are threaded through the front and rear ends of the both-side joint plate 1c of the lower support piece 1B, and the front and rear ends of the front and rear bolts are sequentially sent out from the skin plate 11 by the rear half and the front half of the small-diameter ring-shaped support A. In this case, the bolts may be sequentially expanded by rotating the bolts in the screwing direction in a state where the bolts are received on the end faces of the joint plate 1c of the both-side support pieces 1A, 1A facing the joint plate 1c. in this case,
After the expansion, it is not necessary to connect the separated joint plates 1c, 1c with the bolts and nuts as described above, and the expanded diameter expanding ring-shaped support body A 'is maintained in the expanded state by the push bolt. be able to.

The method of assembling the small-diameter ring-shaped support A is not limited to the method of assembling a plurality of support pieces from the lower side to the upper side as in the above embodiment.
An appropriate method such as assembling while sequentially connecting in the circumferential direction may be adopted. Also, if there is a margin between the small-diameter ring-shaped support A assembled in the skin plate 11 and the inner diameter of the skin plate 11, the skin-plate may be provided within a range where the small-diameter ring-shaped support A is not pressed against the inner surface of the skin plate 11. The diameter of the small-diameter ring-shaped support body A may be expanded inside.

As described above, the step of assembling the small-diameter ring-shaped support body A in the skin plate 11 of the tunnel excavator 10 and the step of assembling the small-diameter ring relative to the tunnel excavation wall T side as the tunnel excavator 10 advances. The rear end side and the front end side sent rearward from the skin plate 11 are sequentially expanded by expanding means in a state where the rear end face of the support A is joined to the front end face of the existing expanded ring support A ′. The step of making the diameter and supporting the tunnel excavation wall surface T is repeatedly performed to form a support structure for supporting the tunnel excavation wall surface.

In tunnel excavation by the tunnel excavator 1, the rear grippers 17, 17 are pressed against both side surfaces of the tunnel excavation wall T, and then the rear support 16 is contracted to separate from the bottom surface of the tunnel excavation wall T, and thereafter. Then, the front gripper 15 is excavated by the cutter plate 13 while sliding the front gripper 15 against the excavation wall surface T while the reaction force is supported on the tunnel wall surface 2 via the rear gripper 17 by extending the propulsion jack 18. After excavation of the tunnel of a certain length, the front gripper 15 is firmly pressed against the excavation wall 2 and the rear support 16 is extended to be supported on the bottom surface of the excavation wall 2 and the rear gripper 17 is contracted. The rear gripper 18 is contracted along the beam body 14
17 is advanced to the next crimping position.

[0034]

As described above, according to the method for forming a tunnel support body of the present invention, the curvature is obtained by connecting a plurality of support pieces each formed of a rectangular frame curved in an arc shape in the skin plate of the tunnel excavator. After assembling a small-diameter ring-shaped support whose radius is smaller than the radius of curvature of the skin plate, when the small-diameter ring-shaped support is sent out relatively to the tunnel excavation wall side as the tunnel excavator advances, the small-diameter ring-shaped support is formed. Since the diameter of the support body is enlarged and the outer peripheral surface of the expanded ring-shaped support body is brought into close contact with the tunnel excavation wall surface, first, a small-diameter ring-shaped support body is set in the skin plate of the tunnel excavator. As a result, the small diameter ring-shaped support can be safely and efficiently assembled without being affected by collapse or skin fall due to loose rock on the tunnel excavation wall. Further, since the small-diameter ring-shaped support body is relatively sent to the tunnel excavation wall side in accordance with the excavation of the tunnel excavator to expand the diameter, the tunnel excavation wall surface immediately after the skin plate is provided. The tunnel excavation wall immediately after the skin plate can be supported without hardly any gap between the outer surface of the small-diameter ring-shaped support body and the small-diameter ring-shaped support body. Work safety can be ensured.

Further, according to the present invention , in the skin plate of the tunnel excavator, the support pieces disposed at the center of the lower peripheral wall of the tunnel and the support pieces disposed on both sides of the skin plate are temporarily fastened. After assembling a small-diameter ring-shaped support body by integrally connecting the other support pieces, according to the excavation of the tunnel excavator, when the small-diameter ring-shaped support body is relatively sent to the tunnel excavation wall surface side, Since the small-diameter ring-shaped support body is to expand the diameter of the small-diameter ring-shaped support body by loosening the temporary fastening of the small-diameter ring-shaped support body and expanding in a circumferential direction between the separable support pieces, the small-diameter ring-shaped support body has a skin. The ring-shaped support body is assembled on the central portion of the lower wall of the tunnel, which is received in the central portion of the lower peripheral wall of the tunnel, which is exposed in the rear end portion of the plate, with the lower peripheral portion being received. The ring-shaped support is temporarily fastened, so that this small-diameter ring-shaped support is smoothly fed from the skin plate to the tunnel excavation wall side in accordance with the excavation of the tunnel excavator without the need for a pushing means such as a jack. In addition, the small-diameter ring-shaped support body can be expanded and brought into close contact with the wall of the tunnel excavation by releasing the above-mentioned fastening and spreading the support pieces in the circumferential direction after the delivery. In addition, as described in claim 2
The support pieces on both sides of the support piece
Pieces can be simply separated in the circumferential direction without temporarily fastening the pieces
Into a small ring-shaped support.
When the body is sent out relatively to the tunnel excavation wall side
In addition, it is necessary to push and expand these support pieces in the circumferential direction.
The smaller-diameter ring-shaped support may be expanded in diameter.

[Brief description of the drawings]

FIG. 1 is a simplified longitudinal side view of a tunnel excavator on which a ring-shaped support body is constructed,

FIG. 2 is a longitudinal side view showing a state where the diameter of the rear end of the ring-shaped support sent out from the rear end of the skin plate of the tunnel excavator is enlarged.

FIG. 3 is a simplified front view of a small-diameter ring-shaped support body assembled in a skin plate, a perspective view of a rectangular frame,

FIG. 4 is a simplified front view of an enlarged ring-shaped support body,

FIG. 5 is a perspective view of a support piece disposed at an upper part,

FIG. 6 is a perspective view of support pieces provided on both sides,

FIG. 7 is a perspective view of a support piece provided at a lower portion.

[Explanation of symbols]

 1-1B Support pieces 1a, 1b Main girder 1c Joint plate 2 Rock fall prevention member 5 Jack for expanding the diameter 10 Tunnel excavator 11 Skin plate A Small ring-shaped support A 'Expanded ring-shaped support T Tunnel excavation wall surface

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-10-252397 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) E21D 11/14

Claims (2)

(57) [Claims] 1. A method for forming a tunnel support body using a plurality of support pieces each having a rectangular frame curved in an arc shape having a radius of curvature smaller than a radius of curvature of a skin plate of a tunnel excavator, comprising: In the above-mentioned skin plate, the support pieces provided at the center of the lower wall of the tunnel and the support pieces provided on both sides of the skin plate are temporarily fastened and the other support pieces are integrally connected. After assembling the small-diameter ring-shaped support body, according to the excavation of the tunnel excavator, when the small-diameter ring-shaped support body is relatively sent out to the tunnel excavation wall surface side, the temporary fastening of the small-diameter ring-shaped support body is released, The diameter of the small-diameter ring-shaped support body is expanded by pushing and expanding the support pieces that have become separable in the circumferential direction, and the outer peripheral surface of the large-diameter ring-shaped support body is formed on the tunnel excavation wall surface. A method for forming a tunnel support body, wherein the tunnel support body is brought into close contact. 2. A method for forming a tunnel support body using a plurality of support pieces each having an arc-shaped curved rectangular frame having a radius of curvature smaller than a radius of curvature of a skin plate of a tunnel excavator, comprising: Around the support piece arranged at the center of the lower peripheral wall of the tunnel and the support pieces arranged on both sides of the skin plate.
Causes detachably joined in the direction, then the assembly of the small-diameter ring-shaped支保body by integrally connecting between other支保pieces, according to excavation of a tunnel boring machine, the small-diameter ring-shaped支保body in tunnel excavation wall surface When relatively delivered, the small diameter ring-shaped support body is detachably connected in the circumferential direction.
The small-diameter ring-shaped support body is expanded by pushing and expanding the supporting pieces in the circumferential direction, and the outer peripheral surface of the large-diameter ring-shaped support body is brought into close contact with a tunnel excavation wall surface. How the body is formed.