JPH0658093A - Shield excavating machine - Google Patents

Abstract

PURPOSE:To provide a shield excavating machine favorable if used in tunnel excavation under ultra-high water pressure, for example a tunnel with super- large section or in a super-large depth, which can inject a grease seal material uniformly in a seal chamber, presents good pursuit after rapid pressure change in the seal chamber, does not impair the sealing effect, and exerts a high sealing performance. CONSTITUTION:A seal wall 20 is provided in a location behind the backmost part of a tail 3 to form a rear tail seal 21, and a seal wall 23 is provided at a certain spacing ahead of the rear tail seal 21 to form a front tail seal 24. A seal chamber 25 is bounded by these front and rear tail seals, tail part 3, and segment 5 and filled with a grease seal material G. In or around the tail part 3, a heater sheet 70 is furnished for heating that portion of grease seal material G filling the seal chamber 25 which contacts the tail part 3, and therewith the grease seal material G is heated and warm kept in the condition with a high fluidity.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to an ultra large cross section, an ultra large depth,
Alternatively, the present invention relates to a shield machine suitable for excavating a tunnel (including not only a horizontal shaft but also a vertical shaft and an inclined shaft) under ultra-high water pressure such as a seabed (seabed, lakebed, riverbed).

[0002]

2. Description of the Related Art Generally, a tail seal is provided at a tail portion of a shield machine. This tail seal is
Inside the shield machine body including the tail part, such as groundwater from the rear of the shield machine and the backfill injection agent injected on the outer peripheral surface of the segment formed along the inner periphery of the tail part. It seals so that it does not flow into the.

Conventionally, as a tail seal structure of this type of shield machine, a wire brush, which is continuous in a ring shape, is formed between the tail end of the tail part and the inner part of the tail part. From the front end of the shield machine to form a seal chamber between the front and rear wire brushes. It is known that the seal chamber is filled with a grease seal material so as to resist the external pressure.

[0004]

By the way, in a seal structure in which a seal chamber is defined between the wire brushes and the grease seal material is filled in the seal chamber,
Although it can be sufficiently counteracted when the external pressure such as underground spring water is at a low level such as the conventional level, when the depth of the tunnel to be excavated is extremely deep and the external pressure becomes very high, or the tunnel diameter is large and the tunnel top is located at the lower end of the tunnel. It has been found that the following problems occur when a very large water pressure is applied as compared with the water pressure.

That is, since the grease seal material has a predetermined hardness and viscosity, the injection resistance in the vicinity of the seal chamber injection port becomes large when the grease seal material is supplied to the seal chamber through the oil supply pipe and the like, and in addition, the shield excavation progresses. Although a very high external pressure acts on the rear of the machine, the grease seal material must be injected at a pressure higher than such a high external pressure when the grease seal material is filled in the seal chamber. As a result, since it is necessary to set the injection pressure on the fuel pump side to an extremely high level and to inject the grease seal material, it becomes very difficult to inject the grease seal material itself, and it is difficult to evenly inject it into the seal chamber.

Further, since the grease seal material is injected with a very high injection pressure as described above, a considerable amount of the grease seal material injected with the injection leaks to the outside of the rear tail seal of the shield machine. However, the grease sealant is expensive, which is very uneconomical.

Furthermore, under ultra-high pressure such as in the case of ultra-high-strength or ultra-large-diameter shield excavation, even after the grease seal material is filled in the seal chamber, the entire grease seal material filled in the seal chamber has a predetermined hardness and viscosity. Since the grease seal material cannot keep up with the pressure fluctuation when a partial and rapid narrow fluctuation occurs in the seal chamber due to the operation of the shield machine, for example, the narrow side of the seal chamber space. In the space part of, the grease seal material injected leaked out behind the tail seal of the shield machine at a stretch,
Also, in the space portion of the seal chamber space that is widened, the grease seal material cannot follow negative pressure fluctuations, so backfill injectant, underground spring water, etc. are sucked in from the rear, and the seal chamber The tail seal mechanism was destroyed by invading the space, and in an extreme case, there was a problem that the infiltrated backfilling agent and the like penetrated into the shield machine through the seal chamber.

The present invention has been made in view of the above circumstances, and an object of the present invention is to allow a grease sealant to be uniformly injected into a seal chamber with a required minimum relatively low pressure, and The grease seal material does not easily leak to the outside, and it can follow rapid pressure fluctuations in the seal chamber and exhibit high sealing performance without impairing the sealing action. An object of the present invention is to provide a shield machine suitable for use in tunnel excavation under ultrahigh water pressure.

[0009]

In order to achieve such an object, the present invention extends from the tail portion to the outer peripheral surface of a segment formed in a ring shape along the inner peripheral portion of the tail portion. In the shield machine having a tail seal that slides on the outer peripheral surface of the segment following the movement of the tail portion in the excavation direction, the shield machine is positioned on the rear side of the rear end portion of the tail portion. A seal wall is provided on the rear tail seal to form a rear tail seal, and a seal wall is provided in front of the rear tail seal with a predetermined gap to form a front tail seal. The front and rear tail seals, the tail portion, and A seal chamber is defined by the segment, the seal chamber is filled with a grease seal material, and
A heating means for heating the grease seal material portion in contact with the tail portion of the grease seal material filled in the seal chamber is provided around the tail portion or the tail portion.

[0010]

Since the grease seal material is supplied in a state of good fluidity in the vicinity of the inlet of the seal chamber, it is possible to inject at a lower pressure than the conventional one, and it is possible to inject and replenish almost uniformly in the seal chamber. it can.

After the injection, the grease seal material is cooled to normal temperature in the seal material chamber, and at the portion contacting the segment and the tip end of the wire brush which is a seal wall constituent member,
It exhibits a certain hardness and viscosity. Therefore, there is no problem with the sealing function.

Since the grease seal material having fluidity is filled along the outer peripheral surface side of the seal chamber (the inner peripheral surface side of the tail portion of the shield machine main body), the seal chamber accompanying the operation of the shield machine In response to the partial and rapid narrowing fluctuations of the grease sealant, the grease sealant can freely flow and move from the narrowed space to the widened space, or conversely from the widened space to the narrowed space. it can. Therefore, the grease seal material does not leak from the seal chamber at a stretch, and the back-filling agent, underground spring water, etc. do not enter the seal chamber space.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. FIG. 2 is a cross-sectional view showing a schematic configuration of the present invention. In the figure, reference numeral 1 is a shield machine main body 3 having a cutter portion 2 at the front end and excavating the ground ahead in the excavation direction with the cutter portion 3, 3 is a tail portion. Reference numeral 4 is a tail plate, and 5 is a segment in which the segment pieces 6 are assembled and assembled in a ring shape.

In the tail portion 3 of the shield machine main body 1,
The segment 5 is extended from the tail portion 3 along the inner peripheral portion thereof onto the outer peripheral surface 8 of the segment 5 and follows the movement of the tail portion 3 in the excavation direction. A tail seal 10 that slides on the outer peripheral surface 8 is provided.

The tail seal 10 will be described. A rear tail seal 21 is formed by providing a seal wall 20 at the rear end of the tail portion 3 so as to be positioned on the rear side thereof. A seal wall 23 is provided in front of the rear tail seal 21 at a predetermined interval, and the front tail seal 24 is provided.
Is configured. Then, both sealing walls 20, 2
3, a space is formed between the outer peripheral surface 8 of the segment 5 and the tail portion 3, and this space serves as a seal chamber 25.

Further, in this embodiment, a seal wall 26 is further provided in front of the front tail seal 24 to form a tail seal 27. The tail seal 27, the front tail seal 24, and the outer peripheral surface 8 of the segment 5. A seal chamber 28 is formed between the above and the like.

That is, in this embodiment, the seal chambers are continuously provided in two stages at the front and rear. Then, in the seal chambers 25 and 28, as described later, a grease seal material G
Is filled.

As shown in FIG. 1, the sealing wall 20 includes a tail waterproof plate 31 arranged at the rear end of the tail plate 4 and a shape retaining plate 32 arranged in front of the tail waterproof plate 31. The tail waterproof plate 31, the wire brush 33 and the like are held by a mounting member 34. The other seal walls 23 and 26 in front of the seal walls 20 have the same structure, and the same reference numerals are given here and the description thereof will be omitted.

The tail waterproof plate 31 is formed of a rubber plate, a urethane plate, or the like that is waterproof and has elasticity. Further, the wire brush 33 is used in a broad sense here including a brush made of bias wire mesh as well as a wire brush in a narrow sense. As a material, a stainless steel wire which is excellent in rust prevention and strength is preferable, but a simple steel wire or a synthetic fiber wire may be used.

Further, the shape-retaining plate 32 holds and protects the shape of the wire brush 33 as described above, and a stainless steel plate or a Teflon-treated steel plate having appropriate elasticity is used.

The shape retaining plate 32 and the tail waterproof plate 31 are formed by being divided in the circumferential direction. In particular, the tail waterproof plates 31 are formed in a scale-like manner so that the circumferential end portions of the tail waterproof plates 31 overlap with each other in the joints of the segments 6, and the tail waterproof plates 31 are formed to have a sealing action. 6 is provided so as to be in sliding contact with and slide.

The grease seal material G filled in the seal chambers 25 and 28 is composed mainly of a petroleum-based material or a resin material, and is insoluble in water and harmful to heavy metals and the like. No substance used. Further, a sealing material is mixed in the grease seal material G as needed. As the sealing material, in addition to the fiber material, a sheet-shaped piece or a granular material is used. Further, the sealing material is preferably made of a material having high water absorption, flexibility and elasticity and oil resistance. In the case of a sheet-shaped piece, for example, a cut piece of cloth-shaped material or paper-shaped material, etc. Is used. Specific examples of the material for the sealing material include starch-based, cellulose-based, and synthetic polymer-based highly water-absorbent resin materials.

The grease seal material supply system for injecting the grease seal material G into the seal chambers 25 and 28 will be described. As shown in FIGS.
The grease seal material supply nozzle 40 (40a, 40a
b, 40c) are located and arranged at the uppermost part, the middle part, and the lowermost part of the seal chambers 25, 28, respectively.
The supply nozzles 40 may have a structure in which the surroundings are covered with a wire mesh or the like as necessary so that dust is not clogged carelessly.

The supply nozzle 40 is connected to an oil supply pipe 41 provided outside the tail plate 4 through a hole provided in the tail plate 4.

The oil supply pipe 41 is formed along the longitudinal direction inside a rod-like member 43 having a substantially trapezoidal cross section which is fixed to the outside of the tail plate 4.

The front end portion of the oil supply pipe 41 is connected to a connecting portion 42 fixed to the inner peripheral surface of the tail plate 4 through a hole provided in the tail plate 4 along the thickness direction, and the connecting portion 42 is connected to the connecting portion 42. The portion 42 is connected to a ring-shaped header pipe 44 having a diameter slightly smaller than that of the shield machine main body via an oil supply pipe 43.

A pressure adjusting valve 46 and a pressure gauge 47 are individually provided in the oil supply pipe 43. Pressure control valve 4
6 is set so that the lowermost part is high, the uppermost part is low, and the intermediate part has a value between them, corresponding to the pressure behind the shield machine main body.

Specifically, at the rear end of the shield machine main body 1, a pressure sensor for measuring the external pressure behind the machine main body is provided with the grease seal material supply nozzles 40a, 40b.
The pressure adjusting valve 46 is provided at substantially the same height as 40c, and the pressure adjusting valves 46 are individually controlled based on the detection values from these pressure sensors.
The external pressure near the rear end of the shield machine main body 1 (pressure of spring water or muddy water or pressure of backfilling agent) is about the same or slightly higher.

The header pipe 44 is connected to an oil supply pump 50 via an oil supply pipe 48 in which a pressure adjusting valve 46 is interposed. As shown in FIG. 4, in the oil supply pump 50, a piston 52 is arranged inside a container 51 filled with the grease sealing material G, and the piston 52 is provided at a center of the container 51 along a longitudinal direction with a guide rod 53. The structure is such that it can be moved in the longitudinal direction by being guided by. The inner space of the container 51 is partitioned by the piston 52, one space 55 of which is a pressure air chamber and the other space 56 is a grease seal material filling chamber. Further, the oil supply pump may be installed not only horizontally but also vertically and inclined, but in this case, the space 55 (pressure air chamber) is located at the upper position.

An air pipe 58 in which a pressure adjusting valve 57 is interposed is connected to the mirror portion 51a on the pressure air chamber side of the container 51,
The tip of the air pipe 58 is connected to the compressor 58a. Further, an exhaust pipe 60 having a gate valve 59 is connected to the other mirror portion 51b of the container 51.

On the other hand, the oil supply pipe 48 is connected to the mirror portion 51b on the grease seal material filling chamber side of the container 51, and the grease seal material supply pipe 61 is connected to the grease seal material supply pipe 61. The grease seal material G is replenished in the container 51 according to the amount of the seal material G used. The grease seal material supply pipe 61 is connected to a dispersion pipe 62 which is arranged on the same axis as the guide rod 53 in the container 51 and has a plurality of holes 62a formed in the periphery thereof.

Although only one refueling pump 50 is provided in this illustrated example, the number of refueling pumps 50 is not limited to this, and a plurality (for example, two) may be provided in parallel. If a plurality of oil supply pumps 50 are provided in this manner, the oil supply pumps on the other side can be kept in a driven state even when one oil supply pump is forced to stop for replenishing the grease seal material, and the seal chambers 25, 28 can be maintained. Therefore, the grease seal material G can be continuously replenished with a predetermined pressure.

The grease seal material supply system described above is provided with a heating means for heating and keeping the grease seal material G at a predetermined temperature to impart fluidity. The heating means will be described. First, as shown in FIG.
A heater sheet 70 for heating the grease sealing material portion in contact with the tail portion 3 of the grease sealing material G filled in the seal chambers 25, 28 is provided on the inner surface of the tail portion 3 facing the sealing chambers 25, 28. It is provided along the ring. The heater sheet 70 may be provided over the entire tail portion facing the seal chambers 25 and 28, or may be provided at predetermined intervals in the circumferential direction or the front-rear direction. The area where these heater sheets 70 are provided is the grease seal material G.
It is set by the heat capacity of or the thermal conductivity of the tail portion 3.

As shown in FIGS. 5 and 6, a heater sheet 71 is provided around the oil supply pipes 41, 43 and 48, and a heater sheet 72 is also provided around the header 44. Further, the mirror portion 51b of the container 51 constituting the oil supply pump is provided on the grease seal material filling chamber side.
Also, a heater sheet 73 is provided. The heater seats 71, 72, 73 cause the temperature of the grease seal material existing in the oil supply pipe and the oil supply pump to
In order to obtain good fluidity and keep the temperature below the boiling point of the grease sealant, for example, the grease sealant is fluidized by heating and keeping it in the range of 40 to 80 ° C. As a temperature control method using the heater sheet, there is a method in which a temperature sensor is provided in the seal chamber or the pipe, and the heater sheet is turned on / off based on an output signal from the temperature sensor, a step control method, or the like.

The heater sheets 70, 71, 72, 7
Examples of 3 include various types such as a sheet-shaped one containing a heater electric wire and a sheet-shaped one mixed with a powdery resistor. Further, the heater electric wire may be wound directly around the oil supply pipe and the outside thereof may be covered with a heat insulating material.

Next, the operation of the embodiment will be described. The oil supply pump 50 is driven and the seal wall 20 at the rear end of the tail portion of the shield machine is passed through the grease seal material supply system.
The grease seal material is filled in the seal chambers 25 and 28 defined between the spaces 23 and 26. As a result, the rear end of the tail portion has a seal structure, which opposes the external pressure behind the shield machine, that is, the pressure of the backfill injection material or the underground spring water, and prevents the backfill injection material or the like from entering the shield machine body. .

After injecting the grease seal material,
The grease seal material injection pressure into the seal chambers 25, 28 is set so as to correspond to the external pressure behind the shield machine main body and become lower as it goes to the upper part of the shield machine and becomes higher as it goes to the lower part of the shield machine. .

Specifically, based on the detected value from the pressure sensor provided at the rear of the shield machine, the pressure regulating valve 46 interposed between the grease seal material supplying header 44 and the nozzle 40 is spooled. Adjust by moving and balance with the external pressure.

Here, in the case of this embodiment, the seal chamber 2
5 and 28 are provided continuously in two stages in the front and rear, and balance the pressure of the rear seal chamber 25 so as to be substantially equal to the external pressure, and the pressure of the front seal chamber 28 and the rear seal chamber 25 and the shield. It may be controlled so as to be an intermediate value with the underground pressure of the excavator.
Both of the pressures 8 may be controlled so as to substantially match the external pressure.

When the grease seal material is replenished and replenished, a heating means is provided in the grease seal material co-feed system, and the grease seal material G is appropriately heated and supplied in a state of good fluidity. The injection can be performed at a lower pressure than that, and the injection and replenishment can be performed almost uniformly in the seal chambers 25 and 28.

After the injection, the grease seal material is cooled to normal temperature in the seal chambers 25 and 28, and at the portion contacting the outer peripheral surface 8 of the segment 5 and the tip of the wire brush, which is a seal wall constituting member, It exhibits a certain hardness and viscosity. Therefore, there is no problem with the sealing function.

Further, since the outer peripheral surface side of the seal chambers 25 and 28 (the inner peripheral surface side of the tail portion of the shield machine main body) is filled with a fluid grease seal material, the shield machine can be operated. The grease seal material smoothly moves from the narrowed space portion to the widened space portion, or conversely from the widened space portion to the narrowed space portion in response to the partial and rapid narrowing fluctuations of the seal chambers 25 and 28. To do. Therefore, the grease sealant G leaks from the seal chambers 25 and 28 from the space portion where the grease sealant G is narrowed to the rear of the seal chamber at once, or conversely, in the widened space portion, the backfilling agent or underground spout is introduced from the rear of the shield machine. Negative pressure such as water will not be sucked into the seal chamber.

In this embodiment, not only the tail portion 3 and the oil supply pipes 41, 43, 48 but also the mirror portion 51b of the container 51 constituting the oil supply pump 50 on the grease seal material filling side.
Although it is also heated, by heating a part of the container in this way, the fluidity of the grease sealant in the system passages supplying the oil supply pipes 41, 43, 48 can be made constant, so It becomes easier to adjust the pressure of the grease seal material, and therefore the pressure in the seal chambers 25 and 28 can be controlled with higher accuracy. Also, the oil supply pipes 41, 4
Since the flow path resistances of 3, 48 and the like are lowered, the operating pressure of the oil supply pump 50 can be set low, and thus there is an advantage that the durability and safety of the entire supply system can be improved.

A supplementary explanation of the method for replenishing the grease seal material of the oil supply pump 50 will be described. First, the adjusting valve 57 is closed to stop the supply of compressed air from the compressor 58a and the partition provided in the oil supply pipe 48. Valve 48
Close a and stop the supply of the grease seal material.

Then, the sluice valve 61a provided in the grease seal material supply pipe 61 is opened, and the grease seal material is injected from the supply pipe 61. It should be noted that when the piston 52 reaches the leftward movement limit position in FIG. 4 when a predetermined amount of grease seal material is replenished, and the grease seal material is further injected,
I cannot inject.

Then, the sluice valve 61a is closed, the sluice valves 48a and 57 are opened, and the compressor is driven again to bring it into a normal operating state.

The structure of the shield machine of the present invention is as follows.
Not limited to the above embodiment, the shape, material,
Specific constituent elements such as dimensions can be appropriately changed in implementation.

For example, in the above embodiment, the grease seal material supply nozzle 40 is provided at three positions in the height direction of the shield machine, that is, the uppermost part, the middle part, and the lowermost part. However, the present invention is not limited to this. It may be provided only at two places, or may be provided at two places above and below or at a place where the height direction is divided into four or more. Further, in the above-mentioned embodiment, the seal walls 20, 23 and 26 are connected to the wire brush 33 and the waterproof plate 31.
However, the invention is not limited to this, and the wire brush 33 alone or the waterproof plate 31 alone may be used.

In the first embodiment, the seal walls 20, 23 and 26 are provided in three rows at intervals, and the seal chambers 25 and 28 are formed between them to form the grease seal material G therein. However, the present invention is not limited to this, and the structure may be such that two sealing walls are provided and only one sealing chamber is provided between them and the grease sealing material G is filled therein. By providing four or more and a seal chamber for filling the grease seal material G between them, it may be possible to cope with even higher ultra-high pressure.

Further, by providing a seal wall in front of the seal wall forming the seal chamber 20 and providing a water pressure chamber or a pressure air chamber behind the seal chamber, the seal chamber filled with the grease seal material is predetermined from the front. You may make it a structure to support with pressure.

Further, in the above embodiment, the heating means for heating the grease seal material is not limited to being provided in the tail portion 3 of the shield machine, but is also provided in the oil supply pipe and the oil supply pump. Also, it is not always necessary for the fuel pump, and it is sufficient if it is provided only in the tail portion.
Further, when the heating means is provided in the tail portion 3, the heating means is not limited to the inner peripheral surface of the tail portion 3 facing the seal chambers 25 and 28 as in the above-described embodiment, but may be provided in the joint portion with the seal wall. .

[0052]

As described above, according to the present invention, the rear tail seal is formed by providing the seal wall so as to be located on the rear side of the rear end portion of the tail portion, and the front side of the rear tail seal is formed. A front tail seal is formed by providing a seal wall with a predetermined gap between the front and rear tail seals, the tail portion, and the segment to form a seal chamber, and the seal chamber is filled with a grease seal material. In addition, since the heating means is provided around the tail portion or the tail portion for heating the grease seal material portion in contact with the tail portion of the grease seal material filled in the seal chamber, It has an excellent effect like.

Since the grease seal material can be supplied in the state of good fluidity in the vicinity of the supply nozzle which is the injection port into the seal chamber, the grease seal material can be injected at a lower pressure than the conventional one and can be injected almost uniformly in the seal chamber. And can be replenished. After the injection, the grease seal material cools down to the normal temperature in the seal material chamber, and exhibits a predetermined hardness and viscosity at the portion in contact with the segment and the tip portion of the wire brush which is a seal wall constituent member. Therefore, there is no problem with the sealing function.

Further, as described above, since the injection can be performed at a pressure lower than that of the conventional one, the grease seal material injected with the injection is less likely to leak to the outside beyond the seal wall, which is economically advantageous. become.

Further, since the outer peripheral surface side of the seal chamber (the inner peripheral surface side of the tail portion of the shield machine main body) is filled with the fluid grease seal material, the seal chamber accompanying the operation of the shield machine The grease seal material can flow and move smoothly due to a partial and rapid narrowing fluctuation of the seal. Water and the like do not enter the seal chamber space, and good sealability can be secured.

Further, if the structure is such that the pressure in the seal chamber is controlled based on the information from the external pressure sensor provided at the rear of the shield machine, the pressure in the seal chamber can be adjusted with high accuracy so as to correspond to the external pressure fluctuation and balance with it. It is possible to control with the use of, and it is possible to further improve the sealing property and reduce the consumption amount of expensive grease seal material, and it is suitable for use in large-section tunnel excavation and tunnel excavation under high water pressure. be able to. Further, by providing the seal chambers in a plurality of stages, it is possible to provide a shield machine that withstands external water pressure of ultrahigh pressure.

[Brief description of drawings]

FIG. 1 is a longitudinal sectional view showing a main part of an embodiment of the present invention.

FIG. 2 is a schematic longitudinal sectional view of the entire shield machine showing an embodiment of the present invention.

FIG. 3 is a schematic explanatory view showing a grease seal material supply system of the shield machine.

FIG. 4 is a cross-sectional view showing an oil supply pump.

5 is a cross-sectional view taken along line XX of FIG.

6 is a cross-sectional view taken along the line YY of FIG.

[Explanation of symbols]

 1 Shield Machine 3 Tail 5 Segment 20 Seal Wall 21 Rear Tail Seal 23 Seal Wall 24 Front Tail Seal 25 Seal Room 27 Tail Seal 28 Seal Room 31 Tail Waterproof Plate 32 Shape Plate 33 Wire Brush 41 Oil Supply Piping 44 Header Pipe 43 Oil Supply Pipe 48 Oil Supply Pipe 49 Oil Supply Pump 50 Oil Supply Pump 58a Compressor 70 Heater Seat 71 Heater Seat 72 Heater Seat 73 Heater Seat

Claims (1)

[Claims] 1. The tail portion is extended along the inner peripheral portion of the tail portion onto the outer peripheral surface of a segment formed in a ring shape, following the movement of the tail portion in the excavation direction. In a shield machine having a tail seal that slides on the outer peripheral surface of the segment, a rear tail seal is formed by providing a seal wall so as to be located on the rear side of the rear end of the tail portion, and A seal wall is provided in front of the tail seal with a predetermined gap to form a front tail seal, and a seal chamber is defined by the front and rear tail seals, the tail portion, and the segment, and a grease seal is formed in the seal chamber. A grease seal material that is filled with a material and is in contact with the tail portion of the grease seal material filled in the seal chamber around the tail portion or the tail portion. Shield machine, characterized in that a heating means for heating the minute.