JP2004238831A - Sharp curve excavating method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sharp curve excavating method having little possibility of the fall of the natural ground and ground subsidence, allowing the resumption of an excavating process without problems even in the case of temporarily stopping the excavation of a curved part and moreover dispensing with ground construction. <P>SOLUTION: In this sharp curve excavating method, an outbreak part B is excavated at the side part of a shield machine 1, and a high viscosity / non-hardening filler is filled in the outbreak part B while keeping a prescribed pressure through a filling port 6 provided at the shield machine. Almost simultaneously with the formation of a tail void part D with the excavation of the shield machine 1, a slow-hardening back-filling material is filled in the tail void part D from a filling pipe 7 provided at the shield machine 1. The fall of rocks / ground subsidence is prevented, and ground reaction β is secured by projecting expansion bags 15 filled with a quick-hardening filler, from the inside of segments 10 to support the segments 10 into a pit C. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a sharp curve excavation method using a shield machine.
[0002]
[Prior art]
When excavating a tunnel underground for laying water and sewage systems or constructing a subway, a shield machine is generally used.
[0003]
Such a shield machine has a cylindrical shield body, a disk-shaped cutter head is arranged at the front of the shield body, and a disk cutter for earth and sand excavation is provided at the front of the cutter head, In addition, copy cutters are mainly provided on the outer peripheral portion of the cutter head so as to carry out extra cutting. Further, inside the shield main body, there are provided a shield jack for excavation, a segment elector for assembling an annular segment, a discharging device for discharging excavated earth and sand, and the like.
[0004]
According to such a shield machine, the shield jack is applied to the front end face of the segment already assembled in the previous excavation process, the reaction force along the traveling direction of the shield machine is secured from the segment, and the shield jack is used. Extending, excavating a tunnel with a length of one stroke of the shield jack, then assembling a new segment inside the tail part of the shield machine using the segment erector, and applying and extending the shield jack to the segment again. By repeating the process, a straight tunnel is gradually excavated.
[0005]
Since the segment is assembled inside the tail portion of the shield machine as described above, after the shield machine digs forward, it is located behind the tunnel dug in the ground and the shield machine. A gap (tail void portion) is formed between the outer surface of the segment and the thickness of the outer shell of the shield machine and the gap between the inner periphery of the tail portion of the shield machine and the outer periphery of the segment. Will be done. If such a tail void portion is left as it is, there is a danger that the ground will fall down and eventually cause the land subsidence. It is designed to prevent skin fall and land subsidence.
[0006]
By the way, in recent constructions, especially in urban areas, there are many demands for digging along sharp curves, that is, digging for sharp curves. When such a sharp curve excavation is performed, a copy cutter attached to the shield machine is used to dig the outer peripheral portion of the shield machine, and a space necessary for turning the direction of the shield machine (excess portion). In addition, it is necessary to secure a reaction force along the axial direction of the segment (a reaction force against the elongation of the shield jack) and a reaction force from the ground to the segment (ground reaction force). Therefore, a chemical solution injection method has been adopted in which a chemical solution is injected from the ground and hardened to protect the excavation portion to prevent skin fall and land subsidence and to secure a ground reaction force. However, according to such a construction method, it is necessary to secure a space on the ground because of injecting the chemical solution from the ground, and there is a problem that cost and labor are required. It is required that sharp curve construction be performed only by using this method.
[0007]
As a method of attempting to perform a sharp curve excavation only by underground construction, a bulging bag filled with a quick-hardening injection material is applied from the right part of the segment to the tail void generated after the shield machine passes. Utilizing the strength of the injection material inside the swelling bag, the segment is supported inside the ground pit so that the axis of the pit and the axis of the segment substantially coincide with each other. In addition to securing the ground reaction force required for the above, a method of injecting a quick-curing backfill material into the remaining portion of the tail void portion to prevent ground falling and subsidence (for example, Patent Document 1).
[0008]
Further, a method of excavating a sharp curve using a filler exhibiting a property of not hardening and a bag-equipped segment provided with a donut-shaped bag which covers the entire periphery of the segment has been attempted. According to the method using the segment with a bag and the filler, the filler is filled in the overhang, and when the shield machine passes through the overhang, the segments with the bag are sequentially assembled to secure the ground reaction force. In addition, injection of a quick-curing injection material into the bags of these bag-attached segments is performed for each predetermined number, and after the filler is present in the space between the bag and the bag, the filler is filled. It is replaced with backfill material to prevent surface fall and subsidence of the ground. Further, in order to omit the step of replacing the filler with the backfill material, a method of using a slow-hardening backfill material instead of the filler has been proposed.
[0009]
[Patent Document 1]
JP-B-63-6719
[0010]
[Problems to be solved by the invention]
However, in the construction method described in Patent Document 1, when a backfill material is injected into the tail void portion at the same time as or immediately after the shield machine passes, the backfill material is injected into the excess area from the side of the shield machine. There is a possibility that the curving and consolidation will harden and block the surplus portion, so that subsequent curve excavation cannot be performed. In recent years, with the increase in demand for sharp curve excavation, a mid-bend type shield machine in which the first half of the shield body is made refractible with respect to the second half is frequently used, and the excess area is dramatically reduced in space. For this reason, the backfill material is less likely to wrap around, but has not yet solved the fundamental problem. Further, such a problem can be avoided by injecting the backfill material into the tail void portion far behind the shield machine after a predetermined time has passed from the passage of the shield machine. If it is used, there is a gap between the passage of the shield machine and the injection of the backfill material, so that there is a problem in that the surface of the ground falls and the danger of land subsidence increases.
[0011]
In addition, according to the method using the bagged segment and the filler, it is necessary to replace the filler and the backfill material, but since both the filler and the backfill material have an extremely high viscosity, It is virtually impossible to completely replace both. For this reason, the filler often remains alone and as a lump in the tail void portion, which causes a problem that the surface of the ground falls and the ground sinks. In addition, if a slow-hard backfill material is used instead of the filler material, skin dropping and ground subsidence due to residual filler material will not occur, but when the shield machine stops operation due to some trouble, If the backfill injected into the overfill hardens and closes the overfill, a new problem arises in that it becomes impossible to excavate the curve thereafter.
[0012]
The present invention has been made in order to solve such a problem, and the danger of falling of the ground and subsidence is extremely low, without blocking the digging portion, and no ground work is required. It is intended to provide a sharp curve excavation method.
[0013]
[Means for Solving the Problems and Functions / Effects]
In order to achieve the above object, a sharp curve excavation method according to the present invention comprises:
In a sharp curve excavation method to excavate a tunnel along a sharp curve using a shield machine,
During the excavation of the shield machine, a high-viscosity non-curing filler is filled from the inside of the shield machine into an excess portion formed on the outer peripheral portion, and a slow-hard backfill material is injected into a tail void portion formed behind. Then, the loosening of the ground around the shield machine is suppressed, and then, when the shield machine is stopped, the swelling bag is protruded by injecting a quick-hardening injection material into the swelling bag at the tail void portion, thereby forming the shield jack. It is characterized by securing a reaction force.
[0014]
According to the present invention, by filling a high-viscosity non-curable filler in the surplus portion, the conventional effect of protecting the surplus portion and preventing skin fall and land subsidence is achieved, This can prevent the hardening of the steel and the clogging of the overhang. Therefore, even if any trouble occurs in the shield machine and the operation is stopped, the sharp curve excavation can be restarted without any problem.
[0015]
In addition, in the present invention, since the high-viscosity slow-hardening backfill material is injected into the tail void portion, the possibility of sneaking into the surplus portion of the outer periphery of the shield machine is low. Is continued, the solidified and hardened portion does not block the excess portion. Therefore, the slow-hardening backfill material can be injected almost simultaneously with the formation of the new tail void portion, without worrying about wraparound to the surplus portion and blockage of the surplus portion. Therefore, it is possible to minimize the possibility of the surface of the ground and the possibility of land subsidence.
[0016]
Further, in the present invention, a swelling bag into which a quick-hardening injection material is injected is projected from the tail void portion into which the slow-hard backfill material is injected. After protruding, the injected material in the inside quickly solidifies and exhibits a certain strength, so that the segment at the rear of the shield machine can be firmly supported in the pit excavated on the ground. Therefore, the ground reaction force from the ground to the outer peripheral surface of the segment, which is necessary for the sharp excavation of the shield machine, can be surely secured.
[0017]
Incidentally, the non-curable filler filled in the overhang portion is pushed forward by a slow-hard backfill material which is sequentially injected into the tail void portion after passing through the shield machine, or the earth and sand of the ground is removed. After the sharp curve is completed, the filler does not remain alone and as a lump between the segment and the pit excavated in the ground because the material enters the gap between the ground and the earth and sand. Therefore, it is also possible to prevent the surface of the ground from falling or the land subsidence due to the remaining filler. In addition, the filling of the filler, the filling of the slow-hardening backfill material, the bulging bag, and the overhanging of the filling material inside can all be performed in a mine (shielding machine or segment), thus completely eliminating ground work. And labor and cost can be reduced.
[0018]
It is preferable that the non-curable filler is filled in the surplus portion while maintaining a predetermined pressure. By doing so, it is possible to extrude the slow-hard backfill into the tail void behind the shield machine, so that the slow-hard backfill hardens in the overhang and hinders sharp curve excavation. Can be prevented.
[0019]
BEST MODE FOR CARRYING OUT THE INVENTION
Next, specific embodiments of the sharp curve excavation method according to the present invention will be described with reference to the drawings.
[0020]
FIG. 1 is a schematic view of a mid-fold type rear trunk supporting shield machine used in a sharp curve excavation method according to an embodiment of the present invention, and FIG. 2 is a main part of a segment supporting device fixed to a segment. FIG. 3 is a cross-sectional view of the ground when the bulging bag is overhanging, and FIG. 4 is an explanatory diagram showing the process of curve excavation.
[0021]
As shown in FIG. 1, a shielded machine 1 (hereinafter simply referred to as “shield machine 1”) used in the present embodiment is a shield including a front body 2 a and a rear body 2 b. The main body 2 is provided, and a cutter head 3 for excavating the ground A is arranged at a front portion of the front trunk portion 2a. A plurality of shield jacks 4 for propelling the shield machine 1 are supported inside the rear trunk portion 2b, and a segment elector (not shown) for assembling an annular segment (hereinafter simply referred to as "segment"). Etc. are arranged. The front trunk 2a and the rear trunk 2b are connected by a plurality of unillustrated articulate jacks disposed inside the front trunk 2a and the rear trunk 2b. By controlling the contraction of the jack, the front trunk 2a can be bent at a predetermined angle with respect to the rear trunk 2b in a predetermined direction.
[0022]
A copy cutter for excavating the outer peripheral portion of the shield machine 1 on the outer peripheral portion of the cutter head 3 to secure a space for refraction and direction change of the shield machine 1 (hereinafter referred to as “excess portion B”). 5 is provided so as to be able to move out and back. A plurality of filling ports 6 for filling a non-hardening filler (described later) are provided in an excavation portion B excavated by the copy cutter 5 on an outer peripheral portion of the front trunk portion 2a. In the inside of the front body 2a, near the filling port 6, a clay / bentonite liquid, which will be described later, and water glass, which are the raw materials of the filler, are mixed, and the mixture is supplied from the filling port to the surplus portion B. The mixing nozzle 8 is arranged. Further, an outer peripheral portion of the rear trunk portion 2b is formed between the outer surface of the segment 10 behind the shield machine 1 after passing through the shield machine 1 and the inner surface of the pit C excavated in the ground A. An injection pipe 7 for injecting a two-component mixed-type slow-hard backing material (described later) into a gap (hereinafter referred to as a “tail void portion D”) is provided near the rear end inside the injection pipe 7. Also, a mixing nozzle 9 for mixing a mortar and water glass described later and injecting the mixture from the rear end of the injection pipe into the tail void portion is provided.
[0023]
Inside the tail portion of the rear trunk portion 2b and behind the shield machine 1, segments 10, 10, 10,... Assembled in the previous excavation process are continuously arranged, and these segments 10, 10, 10,. Are provided with a plurality of holes 11, 11, 11,... Having screw portions 11 'only on the inner peripheral side of the segment (see FIG. 2). In addition, a segment supporting device 12 for supporting the segment 10 in the pit C excavated in the ground A with the axes thereof substantially aligned with each other is fixed to the holes 11, 11, 11. .
[0024]
As shown in FIG. 2, the segment support device 12 includes an outer cylinder 13 having a screw portion 13 ′ at the outer peripheral portion of the distal end portion and capable of being screwed with the screw portion 11 ′ of the hole 11. Inside the outer cylinder 13, an inner cylinder 14 is arranged so as to almost inscribe the inner peripheral portion of the outer cylinder 13. The inner cylinder 14 is formed to be slightly longer than the outer cylinder 13, and when the screw portion 13 ′ of the outer cylinder 13 is screwed with the screw portion 11 ′ of the hole 11, the tip portion is formed inside the hole 11. It is configured to face the periphery (a position closer to the outside than the screw portion 11 '). A swelling bag 15 is housed in a folded state inside the inner cylinder 14, and a quick-hardening injection material (described later) supplied from the inside of the segment 10 is stored inside the swelling bag 15. An injection cylinder 16 for injecting the inside of the swelling bag 15 is provided. According to the segment supporting device 12 configured as described above, when the quick-hardening injection material is injected into the bulging bag 15 from the inside of the segment 10 through the injection tube 16, the expansion pressure is caused by the injection pressure of the injection material. The filling material in the sack 15 and the swelling bag 15 swells and protrudes into the tail void portion D (see FIG. 3), whereby the segment 10 is inserted into the pit C excavated in the ground A. Can be supported substantially in line with the axis of. Here, the reference numeral 17 denotes a cap.
[0025]
As is well known, a driver's seat, a rotating device for rotating the cutter head 3, a cutter head chamber for taking in the earth and sand removed by the rotation of the cutter head, a cutter head chamber are provided inside the shield machine 1. Discharging device for discharging the sediment taken into the wake side, a drive control device for the shield jack, articulated jack, a transport device for transporting the parts of the segment 10 from behind, and segmenting the segment parts Although a transporting device, a power source, and the like for transporting to the erector are arranged, they are not directly related to the present invention, and therefore, illustration and detailed description thereof are omitted.
[0026]
In the present embodiment, as the filler (non-curable filler) to be filled in the overhang portion B, when a pebble having a diameter of 1 to 2 cm is dropped from about 10 cm above the filler, the pebble is filled with the filler. It is preferable that the material has a viscosity that does not sink into the inside, and it is preferable to use a two-liquid mixing type in order to improve the injection workability. Specifically, a clay / bentonite liquid obtained by adding bentonite to clay produced in Yoshinaga-cho or Kasaoka-shi, Waki-gun, Okayama, is mixed with 5% of water glass as a plastic strength modifier. It is preferable that the viscosity is adjusted by a visco tester to be 20,000 to 30,000 CP or more. The filler adjusted in this way exhibits a characteristic that the viscosity increases immediately after mixing, but does not cure. Therefore, it is assumed that the filler is injected from the mixing nozzle 8 into the overhang portion B through the filling port 6. Also, there is no hardening in the excavation part B, and there is no hindrance to the excavation of the sharp curve of the shield machine 1. Further, even when the material is taken into the chamber of the shield machine 1 together with the earth and sand, the excavation work is not adversely affected.
[0027]
As the slow-hardening backing material injected into the tail void portion through the injection port 7, the mixing ratio of mortar and water glass is changed from about 10: 1 of a normal backing material to about 10: 0.5. Is preferred. Such a slow-hardening backfill material has a high viscosity, but has a long time to cure because the ratio of water glass, which is a plastic strength modifier, is suppressed lower than that of a normal backfill material. (It does not cure for at least 6 hours.)
[0028]
Further, as a quick-curing injection material that is injected into the swelling bag 15 and protrudes into the tail void portion D together with the swelling bag 15, a chloride compound or the like is added to shorten the time until gelation. It is preferable to mix mortar and water glass as a plastic strength adjuster at a ratio of 10: 1.2 to 10: 1.3. Such an injecting material was added to the mortar with a chloride compound or the like for accelerating the gel time, and in addition, the mixing ratio of water glass, which is a plastic strength modifier, was set to be higher than that of a normal backfill material, so that it was promptly increased. Shows the property of initiating setting. Therefore, when the quick-hardening injection material is injected into the swelling bag 15 and the swelling bag 15 protrudes into the tail void portion D, it is already in a state of exerting considerable strength. Therefore, the segment 10 can be supported so as to substantially coincide with the axis of the pit C excavated in the ground A, whereby the ground reaction force required for the sharp curve excavation by the shield machine 1 (from the ground to the segment 10).
[0029]
Next, a sharp curve excavation method using the shield machine 1 will be described with reference to FIG. First, during the excavation of the shield machine 1, the outer peripheral portion of the shield machine is dug using the copy cutter 5 to secure a space (excavation portion B) for refraction and excavation of the shield machine 1 in the next step. At the same time, the clay / bentonite liquid and the water glass are supplied and mixed at the mixing nozzle 8 inside the front body 2a, and then the mixture (filler) of the clay / bentonite liquid and the water glass is supplied through the filling port 6. Is supplied to the surplus portion B while maintaining a predetermined pressure (see the arrow E in FIGS. 1 and 4 (a)), whereby the slackness of the surplus portion B is prevented, and the surface of the surplus portion B is removed. To prevent.
[0030]
At the same time, a slow-hardening backing material is injected from the injection pipe 7 into the rear tail void D substantially simultaneously with the formation of the tail void D. As shown by an arrow F in FIGS. 1 and 4 (a), such a slow-hardening backing material flows from above the segment 10 toward both sides, and finally reaches below the segment 10. Is injected into the tail void portion D so as to cover the entire circumference of the segment 10, so that the outer surface of the segment can be protected, and the occurrence of skin fall and ground subsidence of the ground A can be prevented. You can also.
[0031]
After the excavation of the shield machine 1 is completed, a quick-hardening injection material is injected from the inside of the segment 10 into the bulging bag 15 of the segment supporting device 12 attached to the segment 10 extruded rearward from the tail portion of the shield machine 1. Thereby, the swelling bag 15 is projected to the tail void portion D into which the slow-hard backing material has been injected. The bulging bag 15 protruding from the tail void portion D in this way swells until the outer surface thereof reaches the inner surface of the pit C while pushing the uncured slow-hard backing material in the tail void portion D, thereby swelling the tail void. After being in a state of projecting into the portion D, the quick-hardened injection material in the inside rapidly solidifies and exhibits a strength not lower than a predetermined value. Then, the segment 10 is supported (although partially) inside the pit C via the bulging bag 15 (see FIG. 3), whereby the segment A is separated from the ground A required for the sharp curve excavation. 10 to secure the ground reaction force applied to the outer surface. When the shield machine 1 is stopped, the shield jacks 4 and 4 are contracted, a new segment 10 is assembled inside the tail portion of the shield machine 1, and the segment support device 12 is set on the newly assembled segment 10. Is also performed.
[0032]
Next, a predetermined articulate jack is extended, and the front body 2a of the shield machine 1 is bent in a predetermined direction by a predetermined angle to determine the posture of the shield machine 1. The end faces of the shield jacks 4 and 4 are applied to the front end faces of the newly assembled segments 10 to extend them, and the reaction force along the axial direction of the segments 10 (see the arrow α in FIG. The ground reaction force (see arrow β in FIG. 4 (a)) applied to the outer surface of 10 is secured, and the shield machine 1 is dug slightly diagonally forward (see FIG. 4 (b)). Then, during this excavation, a new surplus portion B is formed on the outer peripheral portion of the shield machine 1 by using the copy cutter 5, and the surplus portion B is filled with a non-curing filler material, and at the rear. The newly formed tail void portion D is injected with a slow-hard backing material.
[0033]
Thereafter, the above-mentioned steps when the shield machine 1 is stopped (assembly of the segment 10, attachment of the segment support device 12, protrusion and protrusion of the bulging bag 15 to the tail void portion D, change of the attitude of the shield machine 1 by the articulated jack) (Depending on the case)) and the excavation of the shield machine 1 and the associated steps (formation of the surplus portion B, supply of the filler to the surplus portion B, injection of the slow-hardening backfill material into the tail void portion D), and a sharp curve. A tunnel along the road is excavated (see FIG. 4C).
[0034]
In the present embodiment, the filler material is filled into the surplus portion B to prevent the surface of the surplus portion B from falling off, and a slow-hard backing material is injected into the tail void portion D to protect the segment 10 and protect the ground. Skin fall and land subsidence can be prevented. In addition, the segment 10 is supported inside the pit C by the quick-hardening injection material in the swelling bag 15 protruding from the tail void portion D, and the ground 10 necessary for the sharp excavation of the shield machine 1 is moved from the ground A to the segment 10. Such ground reaction force can be secured.
[0035]
In the present embodiment, since the slow-hard backing material injected into the tail void portion D has a high viscosity, it hardly wraps around the shield portion 1 from the side of the shield machine 1 to the surplus portion B. 1 does not cure for a long time even if it goes around to the side, and also has the property that the filler supplied to the surplus portion B does not cure. Does not harden in the overhang portion B and closes the overhang portion B, so that the sharp excavation of the shield machine 1 is not hindered. Therefore, even if the shield machine 1 stops excavating during the excavation of a sharp curve, excavation can be resumed without any problem. In addition, since the slow-hardening backfill material injected into the tail void portion D hardens with the passage of time, the ground does not loosen after the completion of the sharp curve excavation work, which may cause skin fall or land subsidence. Absent.
[0036]
The filling material that fills the surplus portion B and protects the surplus portion B is sequentially pushed forward by the injection pressure of the slow-hard backfill material that is sequentially injected from the injection pipe 7 into the tail void portion D, and is shielded. It is taken into the shield machine 1 together with the earth and sand from the front of the machine 1 and is discharged, or enters between the earth and sand on the inner surface of the earth A and becomes a part of the earth A. For this reason, the filler does not exist alone and in a lump in the gap between the outer surface of the segment 10 and the ground A, and there is no occurrence of skin falling and ground subsidence due to the remaining filler. In addition, since the step of replacing the filler and the backfill material, which has been conventionally performed in the construction method using the filler, can be omitted, the step of excavating a sharp curve can be simplified.
[0037]
Furthermore, in the present embodiment, the supply of the filler into the surplus portion B, the injection of the slow-hard backing material into the tail void D, the overhang of the swelling bag 15 from the tail void D and the quick-hardening injection material therein. However, as described above, all the operations are performed in the mine (the filling port 6 provided in the shield machine 1, the injection pipe 7, and the segment support device 12 provided in the segment 10). . Therefore, the construction cost can be reduced and the labor can be saved.
[0038]
In the present embodiment, the shield machine 1 in which one injection pipe is arranged at the upper part has been described. However, according to the scale of the tunnel to be excavated, a plurality of injection pipes 7 are provided in the shield machine 1 in a predetermined pattern. May be.
[0039]
Further, in this embodiment, the mortar and 5% of water glass are mixed at a mixing ratio of about 10: 0.5, and the slow-hardening backing material is used. A mixture of mortar and stirring at about 5: 1 can be injected into the tail void portion as a slow-hardening backing material.
[0040]
In the present embodiment, the plurality of swelling bags 15 are made to project to the tail void portion D. For example, many swelling bags 15 are overhanged at a site where the ground reaction force acts particularly strongly, and other The number and arrangement method can be changed according to the curvature of the pit C, for example, by slightly reducing the number of arrangements at the site. Further, the non-curable filler to be filled in the surplus portion B may be injected from the rear trunk portion 2b of the shield machine 1. Furthermore, the same thing as the slow-hard backfill material injected from the injection pipe 7 of the shield machine 1 may be injected into the tail void portion D from some holes 11.
[Brief description of the drawings]
FIG. 1 (a) is a schematic explanatory view of a shield machine of a center-folding type rear trunk support type used in the present embodiment.
FIG. 2 is a sectional view of a main part of a segment supporting device.
FIG. 3 is a cross-sectional view of the ground when the swelling bag is overhanged.
FIGS. 4A to 4C are explanatory diagrams showing a process of curve excavation.
[Explanation of symbols]
1 Shield machine
2a Front trunk
2b Rear body
4 Shield jack
5 Copy cutter
6 Filling port
7 Injection tube
10 segments
15 bulging bag

Claims (2)

In a sharp curve excavation method to excavate a tunnel along a sharp curve using a shield machine,
During the excavation of the shield machine, a high-viscosity non-hardening filler is filled into the surplus portion formed on the outer peripheral portion from inside the shield machine, and a slow-hard backfill material is injected into a tail void portion formed behind. To prevent loosening of the ground around the shield machine, and then, when the shield machine is stopped, inject the quick-hardening injection material into the swelling bag at the tail void portion so that the swelling bag protrudes to prevent the shield jack from returning. A sharp curve excavation method characterized by securing power. 2. The sharp curve excavation method according to claim 1, wherein the non-curable filler is filled in an overhang while maintaining a predetermined pressure. 3.

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