JP2013194459A - Removal method of back-filling material solidified on tail seal of shield machine, and segment piece used for the removal method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method which allows a back-fill material solidified on a tail seal of a shield machine to be easily removed.SOLUTION: In a shield tunneling method, a segment 6 is assembled in a tail part 4 of a shield machine 1, and a tail void formed between the inner peripheral surface of an excavated space and the outer peripheral surface of the segment is filled with a back-filling material 15 accompanying the movement of the tail part 4 caused by boring operation of the shield machine 1. In this method, the back-filling material 150 solidified on a tail seal which is provided in the tail part 4 so as to move in contact with the outer peripheral surface of the segment 6 is removed by making the back-filling material 150 collide with protrusions 20 provided on the outer peripheral surface 10 of the segment 6 constructed ahead of the tail seal.

Description

  The present invention relates to a method and the like that can easily remove a back-filling injection material solidified on a tail seal that is provided in a tail portion of a shield machine so as to move in contact with an outer peripheral surface of a segment.

  In the shield work, the shield machine is driven by a shield jack while the face is excavated by a cutter head provided on the front side of the shield machine, and the excavated shear is carried out of the shield machine by a screw conveyor or the like. Then, every time a predetermined amount is excavated, the excavation operation of the shield machine is stopped, and the segments are assembled by the erector apparatus in the tail portion of the shield machine. Then, along with the movement of the tail part by the excavation operation of the shield machine, mortar etc. in the gap between the inner peripheral surface of the excavated excavation space (inner periphery of the natural ground) and the outer peripheral surface of the segment (hereinafter referred to as tail void) By filling the backfill material, the natural ground is stabilized. The size of the tail void is determined by the thickness of the tail portion, the margin for assembling the segment in the tail portion, the inclination angle of the segment according to the radius of curvature in the tail portion during curve construction, and the like. If the tail void is left unattended, it may cause collapse of the ground in the excavated area or the settlement of the ground, so it is necessary to quickly fill the tail void with a backfill material such as mortar and solidify it. On the other hand, a tail seal is attached to the rear end of the tail part of the shield machine, and this tail seal prevents the groundwater and earth and sand from flowing into the shield machine from the tail void and the backfill injection material from leaking out. doing. In actual shield construction, the backfill injection material gradually flows out to the inside of the shield machine through the tail seal, so the backfill injection material gradually stays in the seal tail and solidifies (for example, in the longitudinal direction of the shield machine at the tail portion). The back-filling material gradually accumulates and solidifies between the front and rear tail seals provided in multiple stages). For this reason, there is no assembly allowance (tail clearance) of the segment, and it may become difficult to assemble the segment and correct the direction of the shield machine, or cause deformation or breakage of the segment. In addition, since a large tail clearance is required in shielded construction (steep curve construction) with a steep curve, a segment with a smaller outer diameter than the normal segment is used. The back-filling material is often solidified into the tail seal due to a decrease in the wrap margin of the tail seal and deterioration of the followability of the tail seal to the segment outer peripheral surface caused by the inclination of the segment in the tail portion. After exiting the curve in such a state of the tail part, the shield excavation shifts to linear construction, and after assembling the normal segment, if the shield machine is propelled, the back-filled injection material solidified in the tail seal is the reduced diameter segment. Usually, the shield machine collides with the stepped portion with the segment and does not dig, causing deformation of the segment, breakage of the tail seal, deformation of the tail portion, and the like. Therefore, when the backfilling injection material stays in the tail seal and solidifies, it is necessary to remove the backfilling injection material solidified in the tail seal.

Conventionally, there has been known a method of assembling a cleaning segment, and using a special tool or the like from the inside of the cleaning segment through an opening of the cleaning segment to remove the back-filling material solidified in the tail seal (Patent Document) 1).
In addition, as a back-filling material, a back-filling material (eg, a back-filling material mixed with water glass) that causes structural destruction by freezing and then thawing is used. A method of removing the back injection material by performing water jet injection etc. from the back material injection hole to the thawed back injection material after the back injection material is thawed by a freezer (See Patent Document 2).

JP 09-268892 A JP 2009-74318 A

However, as in the technique disclosed in Patent Document 1, in the method of removing the backfill injection material using a dedicated tool or the like, the work of crushing the backfill injection material solidified in the tail seal using the dedicated tool There is a problem in terms of cost and workability.
In addition, as in the technique disclosed in Patent Document 2, in the method of freezing the backfill injection material solidified in the tail seal with a freezing apparatus and then thawing and removing it, it is necessary to use a special backfill injection material. Yes, the shield machine must be equipped with a device for freezing and thawing the back-filled injection material, and further, by performing water jet injection etc. from the back-material injection hole to the thawed back-fill injection material Since the backfilling material must be crushed, there are difficulties in terms of cost and workability.
Thus, from the viewpoint of cost and workability, the conventional method is hardly a method that can easily remove the back-filling material solidified on the tail seal of the shield machine.
The present invention provides a method and the like that can easily remove the backfilling material solidified on the tail seal of the shield machine.

According to the present invention, the method of removing the backfill material solidified on the tail seal of the shield machine assembles the segments in the tail part of the shield machine, and the excavation space of the excavated excavation space as the tail part moves by the excavation operation of the shield machine. In the shield method that fills the back void injection material in the tail void formed between the inner peripheral surface and the outer peripheral surface of the segment, the tail seal provided on the tail part so as to move in contact with the outer peripheral surface of the segment Since the solidified backfill injection material is removed by colliding with the projections provided on the outer peripheral surface of the segment constructed in front of the tail seal, the backfill injection material solidified on the tail seal of the shield machine can be easily removed. .
The tail seal includes a rear tail seal and a front tail seal provided along the front-rear direction of the shield machine so as to move in contact with the outer peripheral surface of the segment at the rear end of the tail portion. Since the back-filling injection material that entered between the tail seal of the front stage and the front stage tail seal and solidified was made to collide with the protrusions provided on the outer peripheral surface of the segment constructed in front of the front stage tail seal, it was removed. The back-filled injection material solidified between the front and rear tail seals can be easily removed.
In addition, since the protrusion amount of the protrusion protruding from the outer surface of the segment is adjusted, even when the tail clearance is large, the backfilling material solidified in the tail seal, or between the rear tail seal and the front tail seal It is possible to easily remove the back-filled injection material that has entered and solidified.
In addition, the protrusion extends on the outer surface of the segment in a direction along the front-rear direction of the shield machine, and has an inclined portion that inclines in a direction away from the center line of the segment from the front-rear direction rear side to the front side of the shield machine. The back injection material solidified in the tail seal, or the back injection material solidified by entering between the rear tail seal and the front tail seal collides with a portion with a small protrusion amount of the protrusion. It is easily removed by being torn off with protrusions whose protrusion amount gradually increases continuously.
A segment piece used in the removing method, which is a back-injection material solidified in the tail seal, or a protrusion that enters between the rear-stage tail seal and the front-stage tail seal and collides with the solidified back-injection material Since the back surface injection material solidified in the tail seal of the shield machine or the back surface injection material solidified between the tail seals can be easily constructed.
A segment piece used in the removing method, which is a back-injection material solidified in the tail seal, or a protrusion that enters between the rear-stage tail seal and the front-stage tail seal and collides with the solidified back-injection material Is provided on the outer surface and the protrusion amount adjustment device for adjusting the protrusion amount of the protrusion protruding from the outer surface is provided, so even if the tail clearance is large by adjusting the protrusion amount of the protrusion according to the tail clearance It is possible to construct a segment that can easily remove the back-filling material solidified in the tail seal of the shield machine or the back-filling material solidified between the tail seals.

The figure explaining the shield construction using the segment which has a processus | protrusion on the outer surface in order to remove the backfill injection material solidified between tail seals (Embodiment 1). The perspective view which looked at the segment piece from the inner surface side (Embodiment 1). The perspective view which looked at the segment piece from the outer surface side (Embodiment 1). Sectional drawing of a segment piece (Embodiment 1). The figure which shows the removal method of the backfill injection material solidified between tail seals (embodiment 1). The figure which shows the removal method of the backfill injection material solidified between tail seals (embodiment 1). Sectional drawing of a segment piece (Embodiment 2). Sectional drawing which shows the detail of protrusion and the protrusion amount adjustment apparatus (Embodiment 2).

Embodiment 1
As shown in FIG. 1, the shield machine 1 includes a barrel 2, a drilling device 3 such as a cutter head provided at the front end of the barrel 2, and a tail (rear barrel) provided at the rear of the barrel 2. Tube portion) 4. For example, a shield jack 5 for propelling the shield machine 1, a driving device for an excavator 3 (not shown), a soil removal device such as a screw conveyor, etc. are provided inside the barrel 2, and a segment is provided inside the tail portion 4. 6 includes an erector device and the like that are not shown.

  The tail portion 4 is a ring-shaped tail seal that goes around the inner peripheral surface of the cylinder 7 and the inner peripheral surface on the rear end side of the cylinder 7, and is a rear stage provided along the front-rear direction of the shield machine 1. The tail seal 8 and the front tail seal 9 are provided. The front and rear tail seals 8; 9 are formed of a material excellent in followability to the outer peripheral surface 10 of the segment 6, and for example, a brush configuration in which fine steel wires are bundled is used.

  In the shield construction method, the segment 6 constituting the tunnel wall body is assembled by the erector device in the tail part 4 of the shield machine 1, and the shield jack 5 is excavated by the excavator 3 provided on the front side of the shield machine 1. To drive the shield machine 1 by taking the reaction force at the front of the segment 6 and assemble a new segment ring inside the tail part 4 of the shield machine 1 every time the propulsion for the segment 1 ring is completed Thereafter, the propulsion of the shield machine 1 and the assembly of the segment ring are repeated, and the inner periphery of the ground 11 that is the inner peripheral surface of the excavated excavation space as the tail part 4 is moved by the excavation operation of the shield machine 1. A not-shown note from the inside of the segment 6 to the tail void, which is a gap between the surface 12 and the outer peripheral surface 10 of the segment 6. To stabilize the natural ground by filling Urakomi injection material 15 such as mortar through the mouth.

  The tail portion 4 of the shield machine 1 includes the rear stage tail seal 8 and the front stage tail seal 9 provided along the front-rear direction of the shield machine 1 as described above. The tail seal 9 is provided so as to move in contact with the outer peripheral surface 10 of the segment 6 as the shield machine 1 is propelled, and prevents the penetration of groundwater, earth and sand, and the backfilling injection material 15 into the shield machine 1. The back-filling injection material 15 filled in the tail void passes between the tail seal 8 in the rear stage and the outer peripheral surface 10 of the segment 6 and is provided for the purpose of There is a case where it enters and stays between the tail seal 9 in the previous stage and solidifies.

  Therefore, in the first embodiment, the back-filled injection material 15 that has entered and stayed between the rear tail seal 8 and the front tail seal 9 and has solidified the segment 6 constructed in front of the front tail seal 9. It was made to collide with the protrusion 20 provided in the outer peripheral surface 10 and to be crushed.

2; as shown in FIG. 3, a segment piece 61 made of, for example, steel that constitutes the segment 6 includes an arcuate plate 63 called a skin plate having an outer surface 62 that forms the outer peripheral surface of the tunnel wall, and a segment joint surface A pair of joint plates 64; 64, a pair of main beams 65; 65 forming a ring joint surface, and a plurality of reinforcing ribs 66;
The pair of joint plates 64; 64 are respectively provided at both end edges in the direction along the circumference of the arc of the arc-shaped plate 63, and directed toward the center of the arc of the arc-shaped plate 63 in the direction along the arc diameter of the arc-shaped plate 63. And an arc center line of the arc-shaped plate 63 (a line passing through the center of one arc edge of the arc-shaped plate 63 and the center of the other arc edge of the arc-shaped plate 63). The pair of main girders 65; 65 are respectively provided at the arc edges at both ends in the direction along the arc center line of the arc plate 63, and the arc of the arc plate 63 in the direction along the arc radial line of the arc plate 63. It extends in a direction toward the center and extends in a direction along the circumference of the arc of the arc-shaped plate 63. The edge of the pair of joint plates 64 and the arcuate plate 63 of the pair of main girders 65 in the direction along the arc radial line is positioned in parallel with the edge of the arcuate plate 63. That is, the rising heights of the pair of joint plates 64 and the pair of main girders 65 extending so as to rise from the edge of the arc-shaped plate 63 are the same. Accordingly, the inner surface 67 of the arc-shaped plate 63 is surrounded by the pair of joint plates 64 and the pair of main girders 65, and the direction of the arc-shaped plate 63 of the pair of joint plates 64 and the pair of main girders 65 along the arc radial line. A bottomed arc-shaped box space whose end edge is an open edge is formed, and a reinforcing rib 66 is provided between the pair of main girders 65; 65 in the bottomed arc-shaped box space. A plurality of reinforcing ribs 66 are provided between the pair of joint plates 64; The reinforcing rib 66 includes, for example, a contact portion that contacts the inner surface 67 of the arc-shaped plate 63 between the pair of main girders 65; 65, and a contact portion that contacts the inner surface 70 of each of the pair of main girders 65; The contact portion of the reinforcing rib 66 and the inner surface 67 of the arc-shaped plate 63 and the contact portion of the reinforcing rib 66 and the inner surface 67 of the arc-shaped plate 63 are fixed by welding or the like.
In addition, it is formed in the segment joint surface of the adjacent segment piece 61; 61 arrange | positioned so that it may rank with the circumferential direction of the circle along the internal peripheral surface 12 of the natural ground 11 which is an internal peripheral surface of the excavated excavation space. The segment pieces 61 are arranged and connected so that the segment pieces 61 are arranged in the circumferential direction of the circle along the inner peripheral surface 12 of the natural ground 11 by fastening a nut (not shown) through a connection bolt (not shown) in the connecting hole 68. A ring is constructed. Further, the shield is obtained by fastening a nut (not shown) through a connecting bolt (not shown) to a connecting hole 69 formed in the ring joint surface of the segment piece 61; 61 arranged adjacent to the shield machine 1 in the front-rear direction. A segment 6 is constructed in which segment rings are arranged in the front-rear direction of the machine 1 and connected.

  The projection 20 is provided on the outer surface 62 of the arc-shaped plate 63 of the segment piece 61. A plurality of protrusions 20 are provided on the outer surface 62 of the arc-shaped plate 63 at a predetermined interval along the circumference of the arc of the arc-shaped plate 63. For example, the protrusion 20 is fixed to the portion of the outer surface 62 located on the back side of the inner surface 67 of the arc-shaped plate 63 with which the contact portion of each reinforcing rib 66 comes into contact by welding or the like. By welding the protrusion 20 to the portion located on the back side of the reinforcing rib 66 in this manner, the protrusion 20 can be firmly welded to the arc-shaped plate 63, and a hole is opened in the arc-shaped plate 63 by welding. Can be prevented.

For example, as shown in FIG. 3 and FIG. 4, the protrusion 20 is configured by a plate portion that extends in the direction along the arc center line of the arc-shaped plate 63 on the outer surface 62 of the arc-shaped plate 63 in the segment piece 61. The plate portion has a constant thickness in the direction along the circumference of the arc of the arc-shaped plate 63, and the surface 21 facing the surface attached to the outer surface 62 of the arc-shaped plate 63 has the other side from the main girder 65 side to the other side. It is formed by an inclined surface that gradually separates from the outer surface 62 of the arc-shaped plate 63 toward the main girder 65 side.
When the segment 6 is formed, the protrusion 20 extends in a direction along the front-rear direction of the shield machine 1, and the inclined surface as the inclined portion of the protrusion 20 is the rear side in the front-rear direction of the shield machine 1. An inclined surface that is inclined in a direction away from the center line of the segment 6 toward the front side is formed. In other words, the outer peripheral surface 10 of the segment 6 is provided with the protrusion 20 in which the protruding amount from the outer peripheral surface 10 of the segment 6 gradually and continuously increases from the rear side in the front-rear direction of the shield machine 1 toward the front side. .

  Therefore, the back injection material 150 that has entered and solidified between the front and rear tail seals 8; 9 collides with the protrusion 20 on the outer peripheral surface 10 of the front segment 6 as the shield machine 1 advances (FIG. 5A). (See (b)). In this case, the back-filling injection material that has entered between the front and rear tail seals and solidified collides with a portion of the protrusion 20 where the protrusion amount is small, and then is gradually cut by the protrusion 20 whose protrusion amount gradually increases. Therefore, the ring-shaped lump of the back injection material 150 that has entered and solidified between the front and rear tail seals 8; 9 collides with each protrusion 20 provided at a predetermined interval along the circumference of the arc of the arc-shaped plate 63. As a result of being divided into small lumps, as the shield machine 1 is propelled, the rear machine moves rearward from between the tail seal 8 at the rear stage and the outer peripheral surface 10 of the segment 6 formed by the segment piece 61. It will be removed from between the tail seals 8 and 9 (see FIG. 5C). As the shield machine 1 is propelled, a small lump of the back-filling injection material 150 moved rearward from between the rear tail seal 8 and the outer peripheral surface 10 of the segment 6 and removed between the front and rear tail seals 8; When the back void injection material 15 is filled in the tail void in a later process, it is pressed against the ground 11 or mixed with the back injection material 15.

In the case of a sharp curve construction, a large tail clearance is required. Therefore, as shown in FIG. 6, a segment 80 having a reduced outer diameter of the segment ring is used as the segment 6 of the sharp curve portion. The outer peripheral surface 10 of the segment 6 is a step portion due to a difference in outer diameter between the normal diameter segment 81 and the reduced diameter segment 80 at a portion that changes from the normal diameter segment 81 that is a segment used for the straight portion to the reduced diameter segment 80 of the sharp curve portion. The follow-up performance of the tail seal 8 at the rear stage is deteriorated, and the back injection material 15 easily enters between the front and rear tail seals 8 and 9. Then, the stepped portion 152 (the stepped portion 152 due to the difference in outer diameter between the normal diameter segment and the reduced diameter segment of the portion where the back injection material 150 that has entered and solidified between the front and rear tail seals 8 and 9 changes from the reduced diameter segment to the normal diameter segment. When colliding with FIG. 6B, the shield machine 1 may not be able to be propelled.
Therefore, in the first embodiment, in the case of sharp curve construction, the above-described protrusion 20 is provided on the outer peripheral surface 82 of the reduced-diameter segment 80, and the back-filling injection material 150 solidified by entering between the front and rear tail seals 8; Before colliding with the stepped portion 152, the back-filling injection material 150 was collided with the protrusion 20 and crushed.

In the case of the sharp curve construction, it is preferable to provide the protrusion 20 on the outer peripheral surface 82 of the reduced diameter segment 81 for several rings (for example, 3 rings) just before the portion where the reduced diameter segment 80 changes to the normal diameter segment 81.
Moreover, what is necessary is just to provide the processus | protrusion 20 in the outer peripheral surface 10 of the segment 6 regularly in cases other than steep curve construction.

According to the first embodiment, it becomes possible to easily remove the back-filling injection material 150 that has remained and solidified between the tail seals 8 and 9 before and after the shield machine 1.
Further, by using a segment piece 61 having a projection 20 on the outer surface 62 that collides with the back-filling injection material 150 that has entered between the rear tail seal 8 and the front tail seal 9 and has solidified, the front and rear of the shield machine 1 can be used. Thus, it is possible to construct a segment 6 that can easily remove the back-filling material 150 solidified between the tail seals 8;

Embodiment 2
The segment 6 is not necessarily assembled concentrically with the tail part 4 but may be assembled eccentrically or deformed. Therefore, the segment 6 is located between the outer peripheral surface 10 of the segment 6 and the inner peripheral surface of the tail part 4. The tail clearance, which is the distance, changes. When the tail clearance is increased, the thickness of the ring-shaped lump of the back-filling material 150 that is retained and solidified between the front and rear tail seals 8 and 9 is also increased. There is a possibility that the back-filled injection material 150 that has been retained and solidified between the seals 8 and 9 is not divided.
Therefore, in the second embodiment, the segment piece 600 including the protrusion 200 that can change the protrusion amount protruding from the outer peripheral surface 10 of the segment 6 as shown in FIGS. 7 and 8 is used. That is, by using the segment piece 600 including the protrusion 200 protruding from the outer surface 601 of the segment piece 600 and the protrusion amount adjusting device 300 for adjusting the protrusion amount of the protrusion 200 protruding from the outer surface 601 of the segment piece 600, By forming the segment 6 and changing the protrusion amount of the projection 200 according to the tail clearance, the back-filling injection material 150 that has remained and solidified between the front and rear tail seals 8 and 9 can be divided.
The protrusion 200 is formed of, for example, a high-strength bolt (bolt made of high-strength steel), and the protrusion amount adjusting device 300 includes a bolt shaft through hole 602 formed in the arc-shaped plate 630 of the segment piece 600 and the bolt shaft through hole. And a nut 604 welded (607) to the inner surface 670 of the arc-shaped plate 630 so that the screw hole 603 and the screw hole 603 are matched.
Further, one of the one end surface 605 of the bolt head of the high-strength bolt and the one end surface 606 of the nut 604, which are surfaces facing each other, is placed on the inside of the segment 6 via the bolt shaft through hole 602 and the screw hole 603. A water stop member 610 such as a water stop packing is provided for preventing the water from entering.
According to the second embodiment, by adjusting the protrusion amount of the protrusion 200 that protrudes from the outer surface 601 of the segment piece 600 according to the tail clearance measured by a non-illustrated measuring instrument, even when the tail clearance is large, the front and rear The back-filling material 150 that has remained and solidified between the tail seals 8 and 9 can be divided and easily removed.
In addition, the outer surface 601 includes a protrusion 200 that collides with the backfill injection material 150 that has entered between the rear tail seal 8 and the front tail seal 9 and has solidified, and the protrusion 200 protrudes from the outer surface 601. By using the segment piece 600 provided with the protruding amount adjusting device 300 for adjusting, the segment 6 that can easily remove the back-filling injection material 150 solidified between the front and rear tail seals 8; 9 even when the tail clearance is large. Can be built.
In addition, except when adjusting the protrusion amount of the protrusion 200, the high strength bolt 610 is held between the one end surface 605 of the bolt head of the high strength bolt and the one end surface 606 of the nut 604 so that the watertight state is maintained. Tighten the bolts.

The shape of the fixed protrusion 20 described in the first embodiment is not particularly limited, and may be, for example, a rod-shaped protrusion 20 that protrudes from the outer surface 62 of the arc-shaped plate 63.
The shape of the protrusion 200 that can adjust the protrusion amount described in the second embodiment is not particularly limited. For example, the protrusion amount of the protrusion 20 described in the first embodiment may be adjustable.
For example, the protrusion 20; 200 extends in the direction along the front-rear direction of the shield machine 1 on the outer surface of the segment 6, and is separated from the center line of the segment 6 from the rear side in the front-rear direction of the shield machine 1 toward the front side. It may be a triangular pyramid-shaped protrusion provided with a ridge line as an inclined portion inclined in the direction.
The protrusion 20; 200 has a protruding length that extends in the direction along the front-rear direction of the shield machine 1 on the outer surface of the segment 6 and protrudes from the outer surface of the segment 6 and does not include the inclined portion. The cross-sectional shape orthogonal to the center line of the segment 6 may be a projection such as a quadrangle, a triangle, or the like.

  Further, in the embodiment, the example in which the back-filling material 150 staying between the tail seals 8; 9 before and after the shield machine 1 and solidifying is removed is shown, but according to the present invention, the outer periphery of the segment is added to the tail portion. It is possible to remove the back-filling material that has solidified in one or more tail seals that are provided to move in contact with the surface.

1 Shield machine, 4 tail part, 6 segments, 8 tail seal at the back,
9 Tail seal of the front stage, 10 segment outer peripheral surface, 15 backfill injection material,
20; 200 protrusion, 61; 600 segment piece,
62; 601 the outer surface of the segment piece,
150 Back injection material solidified between tail seals, 300 Projection amount adjustment device.

Claims (6)

  Assemble the segments in the tail part of the shield machine, and inject the back into the tail void formed between the inner peripheral surface of the excavated excavation space and the outer peripheral surface of the segment as the tail part moves due to the excavation operation of the shield machine In the shield method that fills the material, the back injection material solidified in the tail seal provided so as to move in contact with the outer peripheral surface of the segment in the tail portion is applied to the outer peripheral surface of the segment constructed in front of the tail seal. A method for removing a back-filling material solidified on a tail seal of a shield machine, characterized in that it is removed by colliding with a provided projection.   As a tail seal, a rear tail seal and a front tail seal provided along the longitudinal direction of the shield machine so as to move in contact with the outer peripheral surface of the segment at the rear end portion of the tail portion are provided. The back injection material solidified by entering between the seal and the front tail seal is removed by colliding with a protrusion provided on the outer peripheral surface of the segment constructed in front of the front tail seal. Item 2. A method for removing a back-filling material solidified on a tail seal of a shield machine according to Item 1.   3. The method of removing a back-filling material solidified on a tail seal of a shield machine according to claim 1, wherein the protrusion amount of the protrusion protruding from the outer surface of the segment is adjusted.   The protrusion has an inclined portion that extends in a direction along the front-rear direction of the shield machine on the outer surface of the segment, and inclines in a direction away from the center line of the segment from the rear side in the front-rear direction of the shield machine toward the front side. The method for removing a back-filling injection material solidified on the tail seal of the shield machine according to any one of claims 1 to 3.   The segment piece used in the removing method according to claim 1 or 2, wherein the back-filled injection material solidified on the tail seal, or solidified by entering between the rear tail seal and the front tail seal. A segment piece characterized in that it has a projection on the outer surface that collides with the backfilling injection material.   The segment piece used for the removing method according to claim 3, wherein the back-filled injection material solidified in the tail seal or the back-filled injection solidified by entering between the rear tail seal and the front tail seal. A segment piece comprising a protrusion that collides with a material on an outer surface, and a protrusion amount adjusting device for adjusting a protrusion amount of the protrusion protruding from the outer surface.

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