JP3210625B2 - Support unit and method of forming tunnel support body - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a support unit used for supporting a ton excavated wall surface excavated by a tunnel excavator and a method for forming a tunnel support body formed by combining the support units.

[0002]

2. Description of the Related Art When a tunnel is excavated in a rocky ground by a tunnel excavator, the excavated tunnel wall surface may fall off or fall off.
As shown in FIG. 11, a flat rectangular frame-shaped support unit 40 is formed by fixing straight end frame materials 43, 44 between both ends of the front and rear beam members 41, 42 curved in an arc shape in the tunnel circumferential direction,
A plurality of support units each having a rock fall prevention member 50 such as a wire mesh stretched over the support unit 40 are connected circumferentially in the skin plate 21 of the shield excavator as shown in FIG. Circular ring support smaller in diameter than diameter
After assembling A ′, the shield excavator excavates and relatively sends it out to the tunnel excavation wall surface side, and then the adjacent support unit 40 forming the lower half of the small-diameter circular ring-shaped support A ′. , Expansion jack connected between 40
As shown in FIG. 13 by 51, these support units 4
The outer peripheral surface of the expanded circular ring-shaped support A is tunnel-excavated by expanding the diameter of the circular ring-shaped support by pushing and expanding in the circumferential direction of the tunnel between the opposed straight end frame members 43, 44 of 0 and 40. Close to the wall T.

[0003]

However, according to the above-mentioned conventional support unit, the front and rear beam members curved in an arc shape are used.
It is formed in a planar rectangular frame by 41, 42 and straight end frame members 43, 44, and the skin plate 21 of the shield excavator is formed.
When assembling the support body A 'with a plurality of support units 40 in the inside, the straight end members of the adjacent support units 40, 40
A plurality of bolt mounting holes 4 formed in these straight end face members 43, 44
Since the parts 5 and 45 are connected in a temporarily tightened state by the bolts 52, there is a problem that the assembling operation requires labor and labor and the work efficiency is reduced.

[0004] This problem can be solved by a configuration in which the support units are connected by a single bolt. However, in this case, the support units connected by the bolt rotate about the axis of the bolt, and these support units 40 are connected to each other. In addition to the fact that the inner and outer peripheral surfaces of the circular ring-shaped support A assembled by the above method are not flush with each other, an unstable ring-shaped support is formed due to a step, and also the circular assembly previously assembled The rear end face cannot be accurately joined to the front end face of the ring-shaped support body, and the connection work between the circular ring-shaped support bodies requires a considerable amount of time.

[0005] Furthermore, the end members 43 and 44 of the supporting units which are abutted to each other are connected by bolts 52 to assemble a circular ring-shaped support A 'having a diameter smaller than the diameter of the tunnel excavation wall T, and then the diameter is increased in the tunnel. Since excessive tension acts on the temporarily tightened bolts, it becomes difficult to perform final tightening, and in some cases, there is a risk of breakage, and each support unit is bent in a direction that reduces the degree of curvature. There is a problem that a residual stress is generated due to the force acting, and the rock bearing capacity is weakened.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide a ring-shaped support body capable of performing an assembling operation accurately and efficiently and obtaining a strong rock supporting force. Another object of the present invention is to provide a support unit which can be constructed smoothly and a method of forming a tunnel support using the support unit.

[0007]

In order to achieve the above object, a support unit according to a first aspect of the present invention comprises a pair of support units which are arranged side by side at predetermined intervals in the length direction of the tunnel and are curved in the circumferential direction of the tunnel. An arc-shaped frame member is provided with an end face member provided with a convex portion and a concave portion between one ends in the tunnel circumferential direction, and has a shape capable of fitting to the convex portion and the concave portion between the other ends. An end member provided with a concave portion and a convex portion is fixed to form a frame-shaped support unit, and the support units are connected to the side surfaces in the tunnel circumferential direction of the end surface member of the support unit so that the support units can be freely bent in and out of each other. It has a structure provided with a connecting mechanism to make it work.

[0008] The connecting mechanism preferably comprises a connecting hole formed in a side surface of the end face member of the support unit in the circumferential direction of the tunnel, and a bolt inserted into the connecting hole. Although it is not particularly limited, when the convex and concave portions formed on the facing end face members of the support units are engaged with each other in a meshing manner and the connection holes are connected by bolts, the facing end face members It is sufficient to allow the support units to bend around the bolt while separating them, and to allow the opposing end members to be completely joined to each other when the support units are in close contact with the tunnel excavation wall surface. From this viewpoint, as described in claim 2, the shape of the connection hole is desirably a long hole that is long in the circumferential direction of the tunnel. A rock fall prevention member may be provided on the support unit formed in the frame shape.

According to a fourth aspect of the present invention, there is provided a method for forming a tunnel support body formed by combining a plurality of the support units according to the first aspect, wherein the convex portion is disposed in a circumferential direction of the tunnel. A plurality of frame-shaped support units provided with end members having recesses and recesses are engaged with each other in such a manner that the projections and recesses of the end members facing each other are engaged with each other in the skin plate of the tunnel excavator. By connecting the opposite side surfaces of the portion in the tunnel circumferential direction in the portion in such a manner as to be freely refracted by bolts, the support units adjacent in the tunnel circumferential direction form a tunnel support body that is refracted toward the center of the tunnel with the bolts as fulcrums, After sending out this tunnel support body to the position to be supported in the tunnel, all support units are expanded with bolts as fulcrums, so that the outer peripheral surface is It is characterized by forming a circular ring-shaped tunnel 支保 body by close contact with the tunnel excavation wall.

In this method of forming a tunnel support,
Since the collapse of the bedrock and the surface fall occur in the upper peripheral portion of the tunnel excavation wall surface, the support unit forming the upper half portion of the tunnel support body supporting the upper peripheral portion is provided as described in claim 5. It is desirable to provide a rock fall prevention member.

[0011]

The support body is formed by sequentially connecting a plurality of support units in the tunnel circumferential direction in the skin plate of the tunnel excavator. At this time, since the convex portion and the concave portion are formed on the end surface member facing the tunnel circumferential direction in the support unit, the support unit can be easily and accurately formed by fitting the convex portion and the concave portion of the end surface member facing each other. When the support units are combined with each other, the protrusions of one support unit and the protrusions of the other support unit are superimposed one on the other in the tunnel length direction, and opposing side surfaces of these protrusions These are refractively connected to each other via a connection mechanism such as a bolt.

When the supporting units are connected to each other by the connecting mechanism, the opposing side wall surfaces of the supporting units are joined to each other in a surface contact state, and are prevented from being deflected in the torsional direction. The inner and outer peripheral surfaces of the curved support units can be accurately continued in the tunnel circumferential direction, and the front and rear arc-shaped frame members of these support units can be continuously continuous without any step.

In this way, by sequentially arranging a plurality of support units in the circumferential direction of the tunnel and connecting the convex portions superimposed one on the other to bend freely, the circumferential length necessary to support the tunnel excavation wall surface is obtained. Form a support that is free at both ends. In this support body, the support unit is sequentially bent inward from the upper peripheral side to the lower peripheral side of the skin plate of the shield excavator. The support units, which are separated from each other without being connected to each other on the peripheral portion side, overlap inside and outside to form a support body having a spirally folded shape.

After the support body is sent out of the skin plate of the tunnel excavator to the tunnel excavation wall formed by the excavation of the tunnel excavator, the support body which forms the free end of the support body and which overlaps each other inside and outside is provided. When the unit is pushed using a jack or the like in the direction in which the overlapping arc lengths decrease, each support unit expands in the outer diameter direction centering on the connecting bolt, and the entire support body expands, and the outer peripheral surface thereof The whole surface is closely contacted with the tunnel excavation wall surface, and the opposite end members of the support units connected by the connection bolts are pressed against each other to form a circular ring-shaped support body capable of firmly supporting the tunnel excavation wall surface. .

As described above, when the support body having the spirally folded shape is expanded in a circular ring shape, the support units at the free end side of the support body, which have been stacked in the loaded state, are released. In this state, these support units are brought into a state in which the end face members facing each other are brought into close contact with each other. The support body is fixed in a circular ring shape by being connected by a connection mechanism such as a nut. In a state where the support body is expanded in a circular ring shape, opposed end surface members of the support units forming the free ends of the support body may be separated from each other. In this case, A spacer member may be interposed between the end surface members.

The support body expanded in a circular ring shape is formed every time the tunnel excavator excavates for a certain length, and the annular rear end face formed by the rear arc-shaped frame material of each support unit is already attached to the tunnel excavation wall surface. After contacting the annular front end face formed by the front arc-shaped frame material of each support unit of the existing support body supporting the existing support body, the front and rear arc-shaped frame materials are connected by bolts and nuts, and the tunnel length direction The support body will be constructed sequentially.

[0017]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a support unit a viewed from an inner peripheral surface side, according to an embodiment of the present invention.
In the figure, front and rear arc-shaped frame members 1 and 2 curved in an arc shape along the circumferential direction of the tunnel excavation wall surface T are arranged side by side at a certain interval in the tunnel length direction, and these front and rear arc-shaped frame members 1 are arranged. 2, the end face member 3 having the convex portion 5 and the concave portion 6 formed between one end portion, and the concave portion 6A and the concave portion 6 having a shape in which the convex portion 5 can be fitted between the other end portions. Convex portion 5A with matable shape
Are fixed to each other to form a frame shape.

The front and rear arc-shaped frame members 1 and 2 and both end surface members 3 and 4 are formed of channel steel having a U-shaped cross section. The supporting units a However, the support unit a made of the above-mentioned steel frame may be formed of a strip-shaped steel plate having a certain thickness and width. Further, the arc-shaped frame members 1 and 2 arranged before and after are the length of the arc length and the dimension between the outer peripheral end surface curved in the convex arc shape and the inner peripheral end surface curved in the concave arc shape, that is, the width which is the thickness of the support unit a. Are formed in the same manner, and the end face members 3 and 4 are formed by bending a straight steel material having the same width and a certain length as the arc-shaped frame materials 1 and 2.

The bent shape of the end face members 3 and 4 is such that the central portion in the length direction is formed on side wall face portions 3a and 4a of a fixed length parallel to the circumferential direction of the tunnel, and from both ends of the side wall faces 3a and 4a. End faces 3b, 3c; 4b, 4c which are refracted at right angles to the opposite directions and are parallel to the tunnel length direction, respectively. By being fixed to one of the opposite ends of the front and rear arc-shaped frame members 1 and 2 by welding, the front and rear ends of the other end face member 4 are fixed to the other opposite end of the front and rear arc-shaped frame members 1 and 2 by welding. The L-shaped concave portion 6 formed by the side wall surface portion 3a and the front end surface portion 3b of the one end face member 3 is formed in the front half of one end side of the front and rear arc-shaped frame members 1 and 2 and the rear half thereof. The end face member 3 has a side wall face 3a and a rear end face part 3c that project in the circumferential direction of the tunnel. Protrusion 5 is formed to have. Similarly, the front half of the front and rear arc-shaped frame members 1 and 2 is formed with a convex portion 5A that protrudes in the tunnel circumferential direction and includes the side wall surface portion 4a and the front end surface portion 4b of the other end surface member 4. In addition, an L including a side wall surface portion 4a and a rear end surface portion 4c in the rear half portion
A letter-shaped concave portion 6A is formed.

Further, in the support unit a, the protrusions 5 and 5A and the recesses 6 and 6A are formed in a size and a shape that can be fitted to each other. Therefore, the support units a and a are formed in the circumferential direction of the tunnel. When assembling, one support unit a
The concave and convex portions 5 and 6 of the other support unit a are the concave and convex portions 5 and 6 of the other support unit a.
The front and rear end faces of the support units a, a, which are curved in an arc shape, are flush with each other in the circumferential direction of the tunnel and are opposed to the end face members 3, 4, which are parallel to the tunnel length direction. The end surfaces 3b, 3c and 4b, 4c are pressed against each other in a state of surface contact. Also, the side wall surfaces 3a, 4a parallel to the tunnel circumferential direction in the opposing end surface members 3, 4 of the support units a, a come into contact with each other in a surface contact state, and the support units a, a slide with each other between the side wall surfaces 3a, 4a. The movement allows movement in the circumferential direction of the tunnel, but prevents twisting delusion.

In the side wall surfaces 3a, 4a of the end members 3, 4 of the support unit a, only one connection hole 7, 7A formed by a bolt formed of a long hole in the tunnel length direction is formed. As described above, when the opposing end surface members 3, 4 of the support units a, a are engaged with each other in such a manner that their concave and convex portions engage with each other, and the opposing side wall surface portions 3a, 4a are joined, the connecting holes 7, 7A are formed. Correspond to the state of communication in the length direction of the tunnel, and the bolts 8 are inserted into the connection holes 7 and 7A to screw the nuts 9 together, so that the support units a,
a are connected to each other so as to be able to freely bend inside and outside using the bolt 8 as a fulcrum.

Further, a rod-shaped metal wire is stacked in a grid pattern on the convexly curved outer peripheral surface of the support unit a formed in a frame shape by the front and rear arc-shaped frame members 1 and 2 and the end surface members 3 and 4. A collapsing prevention member 10 made of a wire mesh is also stretched, and its peripheral edge is fixed to the outer end surface of the frame of the support unit a by welding or the like. Further, several bolt connection holes 11 and 12 are formed in the front and rear arc-shaped frame members 1 and 2 of the support unit a at predetermined intervals in the tunnel circumferential direction. The collapse prevention member 10 may be a metal plate-shaped material or a cloth material having strength, such as canvas, other than a structure in which metal wires are combined in a lattice shape. Further, as shown in FIG. 2, a collapse prevention member 10 is provided on a hard rock ground where there is no possibility of rock collapse, or on a lower peripheral portion of a tunnel excavation wall T where rock collapse does not occur. A support unit a consisting only of a frame that has not been used is used.

A plurality of the supporting units a having the above-described structure are sequentially connected in the circumferential direction of the tunnel within the skin plate of the tunnel excavator as described below to form a supporting body A for supporting the tunnel excavation wall surface T. Form.

FIG. 3 shows a tunnel excavator 20, in which a support member 22 provided integrally with a skin plate 21 at the front end opening of a cylindrical skin plate 21 and a rotation of the support member 22 are provided. A cutter plate 23, which is freely supported and is rotationally driven by a drive motor (not shown) mounted in the support member 22, and a front end thereof integrally fixed to a rear end of the support member 22, A beam 24 extending horizontally rearward from the rear end of the skin plate 21 through a central space of the skin plate 21; and a radially expandable and retractable front mounted integrally on the upper, lower, left and right sides of the support member 22. A gripper 25, a rear support 26 protruding downward from the lower surface of the rear end of the beam body 24 and being vertically expandable and contractable by a jack 26a, and a rear gripper 27 slidably disposed along the lower surface of the beam body 24. , Support member 22 and rear bar And a propulsion jack 28 connecting the upper and lower beams 27.
A cylindrical sliding frame 29 that slides in the front-rear direction is fitted, and push-up jacks 31, 32 are fixed to front and rear portions of the upper surface of the sliding frame 29. Further, in the skin plate 21, there is provided an erect 33 for sequentially assembling a plurality of support units a in the circumferential direction.

The rear gripper 27 is provided on the skin plate 21.
As is well-known, both sides of the tunnel excavation wall T are disposed on the rear side of the beam body 24 projecting rearward from the lower side of the beam receiver 34 slidable relative to the beam body 24. , And both rear grippers 27, 27 are connected to both sides of the rear surface of the support member 22 by the propulsion jacks 28, 28, respectively. The earth and sand excavated by the cutter plate 23 is discharged backward by an appropriate carrying-out means such as a conveyor (not shown).

In the skin plate 21 of the tunnel excavator 20 configured as described above, first, a plurality of support units a are sequentially connected in the tunnel circumferential direction to thereby reduce the diameter of the support body A in which both ends in the tunnel circumferential direction are separated. 'Assemble.
The assembling of the reduced-diameter support body A 'is performed by holding the support unit a by using the eletric unit 33, lifting the support unit a from the lower peripheral side of the skin plate 21 along the inner peripheral surface of the skin plate 21, and attaching the support unit a to the support unit a. This is performed by joining and connecting the next support unit a.

More specifically, the tip of the support unit a is gripped by the eletric unit 33 with the curved surface of the support unit a facing the circumferential direction of the tunnel, and the support unit a is pivoted in the circumferential direction. After moving a predetermined circumferential length upward along the inner peripheral surface of the skin plate 21 and holding it at that position, the end face of the first support unit a facing the lower peripheral side of the skin plate Member 4
As shown in FIG. 4, one end face member 3 of the next support unit a (second support unit a) is opposed to the concave and convex portions 5 of these end face members 3 and 4 which face each other in the tunnel circumferential direction. , 5A, 6 and 6A are engaged with each other in a meshing manner to join the side wall surfaces 3a and 4a of the end surface members 3 and 4, and the connection holes 7 and 7A formed in the side wall surfaces 3a and 4a.
The bolts 8 are inserted into the connecting holes 7 and 7A, and the nuts 9 are loosely screwed to connect the support units a with each other so that the bolts 8 serve as a fulcrum.

Thereafter, the first support unit a is supported by the support member (not shown) projecting from the eletric 33 so as to be at a predetermined distance from the inner peripheral surface of the skin plate 21. In this state, the first and second support units a, a which are connected by further turning the eletric unit 33 in the circumferential direction are integrally moved upward, and then, again in the same manner as described above, the next (third) (2) The unevenness portions 5 and 6 of the end surface member 3 of the support unit a are fitted to the unevenness portions 5A and 6A of the end surface member 4 of the second support unit a, and the side wall surface portion 3 joined thereto.
As shown in FIG. 5, the connection holes 7 and 7A between the a and 4a are refractively connected by bolts and nuts 8 and 9, and then,
The second support unit a is supported by a support member protruding from the erection 33 so as to be at a predetermined distance from the inner peripheral surface of the skin plate 21, and the erection 33 is turned in the circumferential direction. First to third support units a to
a is moved upward.

In this way, the support units a are sequentially connected in the circumferential direction of the tunnel by using the eletrics 33 to form a support body A 'having a circumferential length capable of supporting the tunnel excavation wall surface T. Each support unit a supported by the support plate 33 is disposed at a predetermined distance inward from the skin plate 21, so that the support units a, a connected to each other are connected to the connection bolts 8 as shown in FIG. The end face members 3 and 4 which are bent inwardly of the skin plate 21 with the fulcrum as a fulcrum have a connection structure in which the end face members 3 and 4 open in a V shape toward the inner peripheral surface of the skin plate 21. Accordingly, the support body A ′ is formed in a support body having a diameter smaller than the diameter of the tunnel excavation wall surface T, and has a spiral folded structure in which the first support unit a overlaps the last support unit a. The first support unit a and the rearmost support unit a form a free end of the support body A 'without being connected.

After assembling the reduced-diameter support A 'in the skin plate 21 of the tunnel excavator 20 in this manner, the beam 24
As shown in FIG. 7, the sliding frame 29 is advanced by the jack 30 along the axis, and the push-up jacks 31 and 32 on the sliding frame 29 support the inner surface of the upper peripheral portion of the reduced diameter support body A ′, as shown in FIG. The support of the reduced diameter support body A 'by the erector 33 is released, and thereafter, the sliding frame 29 is moved backward from the skin plate 21 to thereby rearward the rear end face of the reduced diameter support body A' supported by the push-up jacks 31, 32. Is brought into contact with the front end face of the existing support body A which is assembled first and supports the tunnel excavation wall surface T.

Next, the support units a, which form the free end of the reduced-diameter support body A 'and which overlap each other inside and outside,
When a is pushed in the direction in which the overlap does not occur, the support units a, a connected by the connection bolt 8 approach each other while reducing the angle between the opposed end face members 3, 4 opened in a V-shape. In the direction of the tunnel excavation wall surface T and expands toward the tunnel excavation wall surface T, and the support units a, a whose reduced-diameter support body A ′ is entirely enlarged to form a free end are no longer overlapped with each other. Front and rear end face parts 3 and 4
b, 3c; 4b, 4c are pushed to a state where they are completely joined to each other, and the opposing end face members 3, 4 of the support units a, a, which are connected by the connecting bolt 8, are joined. As shown by a dotted chain line or as shown in FIG. 8, a circular ring-shaped expanded support body A having an outer peripheral surface closely contacted with the tunnel excavation wall surface T is formed.

As described above, when the diameter-reduced support body A 'is expanded into the circular ring-shaped support body A, the rear half of the diameter-reduced support body A' is sent out from the skin plate 21 to the tunnel excavation wall T side. When it is in the retracted state, the rear push-up jack 32 on the sliding frame 29 is extended so that the upper peripheral surface of the rear half of the reduced diameter support body A 'abuts on the tunnel excavation wall T, and then the front half. When it is sent from the skin plate 21 to the tunnel excavation wall T side, the front push-up jack 32 on the sliding frame 29 is extended to tunnel the upper peripheral surface of the front half of the reduced diameter support body A '. The diameter-reducing support body A 'is brought into contact with the excavation wall surface T, and thereafter the diameter is reduced as described above. Specific means for expanding the diameter-reduced support body A ′ into a circular ring shape include, for example,
A support unit a, which is formed inside and outside of the support unit a forming a free end of the reduced diameter support body A ', and a support unit a inside the a is connected to a jack (not shown) using the inner peripheral surface of the other support unit a as a fulcrum. This can be done by using and pushing in the circumferential direction of the tunnel.

In forming the support A,
As the support unit a constituting the upper half of the support body A, a support unit having the collapsing prevention member 10 stretched is used, and as the support unit a constituting the lower half, the collapsing prevention member 10 is not provided. Unit is used.

The support A expanded in the shape of a circular ring has a rear circular frame member 2 of each of the support units a and a front side of the existing support member A in which the rear circular frame member 2 abuts. The arc-shaped frame member 1 is integrated by connecting bolt connecting holes 11 and 12 formed in the front and rear arc-shaped frame members 1 and 2 with bolts and nuts, and the support units a and a are connected to each other. The bolts and nuts 8 and 9 that have been temporarily tightened are fully tightened and fixed.

As described above, the reduced diameter support body A 'assembled in the skin plate 21 is sequentially sent out from the rear end of the skin plate 21 to the tunnel excavation wall T according to the excavation of the tunnel excavator 20, and then expanded into a circular ring shape. By supporting the tunnel excavation wall surface T with a diameter, a series of supports that support the tunnel excavation wall surface T over the entire length are formed.

When the tunnel excavator 1 excavates a tunnel, its rear grippers 27, 27 are passed through the front and rear arc-shaped frame members 1 and 2 in a continuous portion between the upper half and the lower half of the support body A, thereby forming a tunnel excavation wall T. After the propulsion reaction force is obtained by crimping both sides of the tunnel excavator, the rear support 26 is contracted and separated from the bottom surface of the tunnel excavation wall T, and then the propulsion jack 28 is extended to extend the tunnel excavation via the rear gripper 27. The front gripper 25 is excavated by the cutter plate 23 while sliding the front gripper 25 against the excavation wall surface T while the reaction force is supported on the wall surface T. After excavating a tunnel of a certain length, the front gripper 25 is firmly pressed against the excavation wall T, and the rear support 26 is extended to be supported on the bottom surface of the excavation wall T, and the rear gripper 27 is contracted. The rear gripper 27 is advanced to the next crimping position along the beam member 24 by contracting 28.

The plurality of support units a constituting the support body A are all formed to have the same arc length. However, as shown in FIG. 9, the support units a having different arc lengths may be combined. May be formed. The shape of the uneven portions 5, 5A, 6, 6A formed on the end surface members 3, 4 of the support unit a is such that the side wall surface portions 3a, 4a are inclined in the tunnel length direction with respect to the tunnel circumferential direction. And one end face member 3
May be formed in the center of the other end surface member 4 and a recessed portion is formed in the center of the other end member 4 so that the protrusion can be fitted. Further, as a connection mechanism (connection means) of the support units a, a, the connection holes 7, 7A drilled in the projections 5, 5A and the bolts / nuts 8, which connect between the connection holes 7, 7A, 9, and as shown in FIG.
A connection hole 7 is provided on the side wall surface 3a of one of the protrusions 5 of the support unit a, and a bolt 8 'is provided on the side wall surface 4a of the other protrusion 5A so as to protrude in the tunnel length direction to connect these. It may be constituted by the hole 7, the bolt 8 ′, and the nut screwed to the bolt 8 ′.

[0038]

As described above, according to the present invention, a pair of arc-shaped frame members curved in the circumferential direction of the tunnel which are arranged side by side at a constant interval in the length direction of the tunnel are provided. An end face member provided with a convex portion and a concave portion between one end portion of the material was fixed, and a concave portion and a convex portion each having a shape capable of being fitted to the convex portion and the concave portion were provided between the other end portions. Since the end members are fixed to form a frame-shaped support unit, the support units can be easily and accurately combined by fitting the protrusions and recesses of the end members facing each other.

Further, a connection hole for connecting the support units to each other via bolts so as to be able to freely bend inward and outward is formed in the side wall surface in the circumferential direction of the tunnel facing the concave side of the protrusion of the end face member of the support unit. By providing the support units adjacent to each other in the circumferential direction of the tunnel in which the protruding portions of the opposed end surface members are superimposed one on the other in the tunnel length direction, the connecting holes formed in these side wall surfaces are connected to each other. It is possible to accurately and smoothly bend inward and outward directions while sliding the opposing surfaces of the opposing end surface members with the connected bolts as fulcrums. Therefore, the tunnel excavation wall surface is provided by a plurality of support units in the skin plate of the tunnel excavator. When forming a support body having a peripheral length corresponding to the peripheral length of the skin, the adjacent support units are refracted inwardly to each other to make the skin play. Condensation 径支 Hotai folded to the small diameter of the spiral than can be easily assembled.

In addition, since the adjacent support units are connected to each other by one bolt so as to be freely bent, the connection operation can be performed efficiently, and the workability of assembling the reduced diameter support body is improved. In addition, the opposing side wall surface portions of the convex portions overlapping in front and rear of the support units that are flexibly connected by the bolts are joined in a surface contact state in the tunnel circumferential direction and regulate each other in the twisting direction,
The inner and outer peripheral surfaces of the support unit curved in an arc shape can be accurately continued in the circumferential direction of the tunnel, and the front and rear arc-shaped frame members of these support units can also be continuously flushed without generating a step. It is possible to form an accurate reduced diameter support body.

Further, since the support body assembled in the skin plate is spirally folded and reduced in diameter as described above, the curved surfaces of the plurality of support units forming the support body are reduced. Despite being adapted to the tunnel excavation wall surface having a larger radius of curvature than the skin plate, a reduced diameter support body that can easily fit in the skin plate can be provided.

After the reduced-diameter support body thus formed is sent out to the tunnel excavation wall surface, the support body is expanded by pressing the free end face of the support unit forming a free end overlapping inside and outside of the support body. Each support unit expands in the outer diameter direction around the connection bolt, the entire support body expands, and the outer peripheral surface is brought into close contact with the tunnel excavation wall surface and the support units connected by the connection bolt are connected to each other. A circular ring-shaped support body capable of firmly supporting the tunnel excavation wall surface by the opposed end face members being pressed against each other in a face contact state can be constructed.

At this time, the bolts connecting the support units connect the side wall surface portions of the convex portions which overlap each other in front and rear of the support unit with the axial direction of the bolt facing the length of the tunnel. Tunnel excavation by smoothly rotating the support unit to the tunnel excavation wall side around the connecting bolt without any excessive tensile force acting on the bolt and without generating any bending stress on the support unit The diameter of the ring-shaped support body capable of supporting the wall surface can be smoothly expanded, and after the formation of the ring-shaped support body, the temporary tightening work of the connection bolt in the temporarily tightened state can be reliably performed, and Construction can be performed efficiently.

[Brief description of the drawings]

FIG. 1 is a simplified perspective view of a support unit,

FIG. 2 is a simplified perspective view of a support unit in which a collapse prevention member is not stretched;

FIG. 3 is a simplified longitudinal side view of a tunnel excavator on which a support body is being constructed,

FIG. 4 is a side view showing a connection state between the support units,

FIG. 5 is an exploded view of a part of the assembled support body,

FIG. 6 is a simplified front view of the reduced diameter support body assembled in the skin plate,

FIG. 7 is a simplified front view of a state where the reduced diameter support body is sent out to a tunnel excavation wall surface;

FIG. 8 is a simplified perspective view of a support body assembled into a circular ring shape,

FIG. 9 is a simplified front view of a reduced diameter support body formed using support units having different arc lengths.

FIG. 10 is a simplified perspective view of a support unit provided with another connection mechanism,

FIG. 11 is a perspective view of a conventional support unit,

FIG. 12 is a simplified front view of a support body formed using the support unit.

FIG. 13 is a simplified front view of a state where the support body is expanded in diameter.

[Explanation of symbols]

 1, 2 Front and rear arc-shaped frame material 3, 4 End member 3a, 4a Side wall 5, 5A convex 6, 6A concave 7, 7A Connecting hole 8 Bolt 10 Collapse prevention member 20 Tunnel excavator 21 Skin plate a Support unit A Support body T Tunnel excavation wall

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) E21D 11/14 E21D 11/04

Claims (5)

(57) [Claims] 1. A projection and a recess are provided between one end in the tunnel circumferential direction of a pair of arc-shaped frame members curved in the tunnel circumferential direction which are juxtaposed at a constant interval in the length direction of the tunnel. A frame-shaped support unit in which the end member provided with a concave portion and a convex portion which can be fitted into the convex portion and the concave portion, respectively, is fixed between the other end portions. ,
A support unit provided on a side surface of the end face member in the tunnel circumferential direction of the support unit, the connection mechanism for connecting the support units to each other so as to be able to freely bend inward and outward. 2. The connecting mechanism includes a connecting hole formed in a side surface of the end face member of the support unit in the circumferential direction of the tunnel, and a bolt inserted into the connecting hole. The support unit according to claim 1, wherein the support unit is a long hole. 3. The support unit according to claim 1, wherein a rock-fall prevention member is stretched over the frame-shaped support unit. 4. A projection and a recess are provided between one end in the tunnel circumferential direction of a pair of arc-shaped frame members curved in the circumferential direction of the tunnel which are arranged side by side at a constant interval in the length direction of the tunnel. A plurality of support units each having a fixed end face member and a fixed end face member provided with a concave portion and a convex portion each having a shape fittable with the convex portion and the concave portion between the other end portions,
The supporting unit adjacent in the circumferential direction of the tunnel is formed by fitting the convex portion and the concave portion of the end surface member facing each other in an engaging manner and connecting the opposing side surfaces of the fitting portion in the circumferential direction of the tunnel with a bolt. To form a tunnel support body which is refracted in the direction of the center of the tunnel with each other using bolts as fulcrums, sending out this tunnel support body to the position to be supported in the tunnel, and then expanding all the support units using the bolts as fulcrums A method of forming a tunnel support body, wherein the outer peripheral surface is brought into close contact with a tunnel excavation wall surface. 5. The method for forming a tunnel support according to claim 4, wherein a rock fall prevention member is stretched on a support unit forming an upper half portion of the tunnel support.