JP2002081288A - Branch shield driving method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a branch shield driving method capable of shortening a construction period by restraining an increase in the machine length, securing bendably advancing performance, simplifying a structure, preventing an entrance of earth and sand and muddy water into a shield driving machine body and reducing work manhours. SOLUTION: A rear end part of an inner shell member 5 is connected to a segment Sb by releasing a fixation of the inner shell member 5 to the shield driving machine body, the shield driving machine body and a shell member are relatively advanced to the inner shell member 5, the segment Sb equivalent to plural rings is constructed on an inside surface of the inner shell member 5, a branch starting port 60 is formed, a front end part of the inner shell member 5 is fixed to the shell member so that the fixation can be released, a shield machine 1 is advanced more than the branch starting port 60, a branch line shield machine 40 is branched and started from the branch starting port 60, and the fixation of the inner shell member 5 to the shell member is released.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a branch shield excavating method, and more particularly to a branch shield excavating method capable of eliminating a decrease in sealing performance of an inner trunk member with respect to a trunk member of a main line shield excavator and shortening a construction period.

[0002]

2. Description of the Related Art When excavating various shield holes (tunnels) for water and sewage and communication cables with a shield excavator, a small-diameter branch tunnel is often branched off from the middle of the tunnel. In the case of a branch start, the main line tunnel is normally dug by a main line shield excavator, and upon arrival at the branch point, the branch line shield excavator is branched and started rightward or leftward from the main line shield excavator. After the branch, the main tunnel is excavated independently with the main line shield excavator using the main line shield excavator.

For example, Japanese Unexamined Patent Publication No. Hei 8-165883 discloses a shield excavator capable of branch excavation, such as a cutter disk, a front trunk, a middle trunk, a rear trunk, a face-face shield jack near the rear end of the front trunk, and a front trunk end. Equipped with a shaft jack located near the shaft, an erector device installed in the rear fuselage, a branch starter provided in the middle fuselage, and a branch line shield excavator for branch tunnel excavation. An excavator is described.

[0004] In this shield machine, before reaching the branch point, excavation is performed while generating excavating thrust by the shaft-side shield jack, and at the branch point, the middle body of the triple structure is extended to open the branch start window. Then, the branch line shield excavator is started, and then the main line shield excavator separates the inner double structure of the middle trunk and the rear trunk from the front trunk, generates excavation thrust by the face side shield jack, and excavates the main line. In parallel with the tunnel excavation, the branch line tunneling machine is used to excavate the branch line tunnel.

On the other hand, the applicant of the present application has filed Japanese Patent Application No. 11-241.
No. 236 proposes and commercializes a branch shield excavation method that enables a branch line tunnel to branch from a plurality of locations on a main line tunnel. That is, the shield excavator is provided with an inner trunk member previously fitted to the trunk member so as to be relatively slidable in the axial direction of the tunnel. When excavating the main line tunnel, the inner trunk member is overlapped on the inner surface side of the trunk member, the inner trunk member is fixed to the excavator body, and the tunnel member is fixed with the trunk member, the excavator main body and the inner trunk member fixed. Do excavation.

During the excavation of the main line tunnel, when reaching the branch point where the branch line tunnel is branched, the fixing of the inner trunk member to the excavator body is released, and the rear end of the inner trunk member is covered with the segment. Is connected with a pin, for example. next,
When the excavator main body and the trunk member are moved forward with respect to the inner trunk member and advanced by one ring, a segment for one ring is constructed on the inner surface of the inner trunk member. By repeating this, segments for a plurality of rings are constructed on the inner surface of the inner trunk member, and the gap in the chamber of the branch line shield excavator is filled with a filler to form a branch start port.

Next, with the shield machine advanced from the branch start port, the branch line shield machine is branched and started from the branch start port. After the branch line shield excavator is branched and started, or while the branch line is started, the inner trunk member is moved forward with respect to the excavator body and the trunk member by a plurality of shield jacks so as to overlap the trunk member as much as possible. Thereafter, the inner trunk member is fixed to the excavator body, and excavation of the main line tunnel is performed. In the same manner as described above, the branch line shield excavators can be respectively branched and started from a plurality of branch points of the main line tunnel.

[0008]

Problems to be Solved by the Invention
The shield machine described in Japanese Patent No. 5884 has a front body, a middle body, and a rear body in the axial direction of the tunnel, so that the machine length is long. When the machine length is increased, the capacity of the shield jack is increased, the strength of the segment supporting the shield jack is insufficient, and there is a problem that the turning performance is reduced. Also, for the branch start of the branch line shield excavator, 3
Since it has a double structure, the number of parts increases, the structure becomes complicated, and the manufacturing cost becomes disadvantageous.

In the branch shield excavating method proposed by the applicant of the present invention, when the inner trunk member is maximally overlapped with the trunk member with earth and sand adhered to the outer peripheral surface of the inner trunk member, the gap between the inner trunk member and the trunk member is reduced. There is a problem that the sealing performance becomes insufficient and earth and sand or muddy water enters the inside of the excavator body. In addition, when stacking the inner body member on the body member, it is necessary to replace the stopper plate on the inner body member (repeated work of gas fusing and welding), which increases the number of man-hours, which leads to a longer construction period. There's a problem. SUMMARY OF THE INVENTION An object of the present invention is to suppress an increase in the length of a shield excavator, secure a turning performance and simplify the structure, prevent earth and sand or muddy water from entering the excavator body, and reduce the number of work steps. And to shorten the construction period.

[0010]

According to a first aspect of the present invention, there is provided a branch shield excavating method in which a main tunnel is excavated by a shield excavator and a branch line shield excavator is branched and started at a branch point in the middle of the main tunnel. In the excavation method, the shield excavator is provided in advance with an inner trunk member that is internally fitted to the trunk member so as to be relatively slidable rearward in the axial direction of the tunnel with respect to the trunk member, and overlaps the inner trunk member on the inner surface side of the trunk member. A first step of excavating the main line tunnel in a state where the inner trunk member is fixed to the excavator main body, and during the excavation of the main line tunnel, releasing the fixing of the inner trunk member to the excavator main body to release the inner trunk member A second step of connecting the rear end to the reinforced segment; moving the excavator body and the trunk member forward relative to the inner trunk member; A third step of constructing a segment and forming a branch start port, a fourth step of fixing a front end of the inner body member to the body member, and moving the shield excavator forward from the branch start port, A fifth step of branching and starting the branch line shield excavator from the start port and releasing the fixation of the inner trunk member to the trunk member is provided.

The shield machine is provided in advance with an inner trunk member which is slidably fitted to the trunk member rearward in the axial direction of the tunnel. In the first step,
The inner trunk member is overlapped on the inner surface side of the trunk member, the inner trunk member is fixed to the excavator body, and the main line tunnel is excavated in a state where the trunk member, the excavator main body, and the inner trunk member are fixed. In the second step, the fixing of the inner trunk member to the excavator body is released during the excavation of the main line tunnel, and a plurality of fixing plates are provided at equal intervals in the circumferential direction at the rear end of the inner trunk member on the inner surface side. By welding to connect these fixing plates to the reinforced segments.

In the third step, the excavator main body and the trunk member are moved forward relative to the inner trunk member, and when the excavator is advanced by one ring of the special segment forming the branch start port, the inner trunk member is moved forward. A special segment for one ring is constructed on the inner surface. This is repeated a plurality of times to construct a special segment for a plurality of rings on the inner surface of the inner trunk member, and the inside of the chamber of the branch line shield excavator is filled with a filler to form a branch start port. In the fourth step, the front end of the inner body member is fixed to the body member in a state where the body member has moved forward relative to the inner body member, and the fixing plates are removed. Thereafter, the entire shield excavator is moved forward from the branch start port so that the branch start port faces the ground. In the fifth step, the branch line shield excavator is branched and started from the branch start port, and the fixing of the inner trunk member to the trunk member is released. Thereafter, the inner trunk member is left in the ground.

In the branch shield excavating method according to a second aspect of the present invention, in the first aspect of the present invention, after the fifth step, a ring member with a tail seal is provided at the rear end of the trunk member of the shield excavator in an in-fit state. It is characterized by the following. After the fifth step, a ring member with a tail seal is provided at the rear end of the body member so as to be slidable in an inner fitting manner, and a special segment for one ring is constructed on the inner surface side of the tail seal. For example, a stop plate is disposed at the front end of the special segment and welded to the ring member, and a reaction force is applied to the ring member to advance the entire shield machine. Finally, the stopper plate is separated from the ring member, and the ring member is fixed to the body member.

[0014]

Embodiments of the present invention will be described below with reference to the drawings. First, the structure of the main line shield machine will be described. Note that the front, rear, left and right in the excavation direction will be described as front, rear, left and right. As shown in FIG.
The main line shield machine 1 includes a cutter disk 2, a body member 3, a machine body 4 inside the body member 3, and an inner body member 5.

The cutter disc 2 will be described.
As shown in FIG. 1, a cutter disk 2 is provided at a front end of the shield machine 1, and a chamber 6 is formed at the back of the cutter disk 2. A partition 8 that partitions the rear end of the chamber 6 is provided transversely inside the front body member 7 on the front end side of the body member 3 and is fixed to the front body member 7.
The cutter disk 2 is formed to have the same diameter as the front body member 7, and has a center frame 9 and a plurality of cutter spokes 10.
And a large number of cutter bits (not shown) attached to the front surface, and a support portion 11 rotatably supported by the partition wall 8. The partition wall 8 is provided with a protruding wall portion 12 bulging rearward, and the cutter disk 2 is configured to be driven to rotate forward and reverse by a plurality of cutter driving motors 13 attached to the protruding wall portion 12.

The trunk member 3 will be described. As shown in FIG. 1, the trunk member 3 is connected to the front trunk member 7 on the front end side and to the rear end of the front trunk member 7 via a center bent portion 14. A main body member 15 having a main body member 15 and cooperating with a front portion of the main body member 15 to form an annular gap having a predetermined thickness in a radial direction between the main body member 15 and the front portion. I have. A ring member 17 is welded to the outer surface of the rear end portion of the main body member 16 in the annular gap.
A flange portion 17a is welded to an outer edge portion of the base member. The main body member 15 includes a cylindrical inner body member 5 and a main body member 1.
5 is slidably fitted rearward in the axial direction of the tunnel relative to the center member 5, and between the flange portion 17 a of the ring member 17 and the main body member 15, the front part of the inner body member 5 is approximately 2 / A short cylindrical gap through which up to 3 can pass is formed.

The shield jack 18 will be described. As shown in FIGS. 1 and 2, a plurality (for example, eighteen) of the shield jacks 18 are shield jacks having a mounting flange at the front end of the jack body. Each flange is detachably fixed to a flange portion 16a at a front end portion of the main body member 16, and a rear end portion of the jack main body is supported by a ring member 17 of the main body member 16. The flange portion 16a is welded to the front end of the main body member 15 in a ring shape, and the inside of the annular gap is substantially liquid-tightly closed. FIG. 1,
As shown in FIG. 2, a partial spherical seat is formed on the outer surface of the center bent portion 14, and the partial spherical seat is rotatably engaged with a partial spherical concave seat on the inner surface of the rear end of the front body member 7. , Body trunk member 1
The front body member 7 is configured so as to be able to change its direction to the left and right with respect to 5. A plurality of middle fold jacks 19 are provided on the left and right sides inside the middle fold portion 14, respectively. The jack body of each middle fold jack 19 is connected to the bracket 20 of the partition wall 8 by a vertical pin. .

The inner body member 5 will be described. As shown in FIGS. 1, 2 and 6, the inner body member 5 is
The main body member is substantially the same length as the main body member from the position for main tunnel tunnel excavation where the rear ends of both body members 5 and 15 are brought close to the inside of the main body member 15 (see FIG. 6A). The position can be switched from the rear end portion 15 to a position for forming a branch start port extending rearward (see FIG. 6C).

As shown in FIGS. 1 and 3, the rear end of the inner body member 5 (about 1/2 ring of the segment Sa) is formed to be slightly thin, and a plurality of rows of tail grouts are formed at the rear end. A seal 21 is provided. At the rear end of the main body member 15, two rows of earth and sand seals 22 are disposed at appropriate intervals in the front and rear direction, and are constantly in pressure contact with the inner body member 5. At the rear end of the main body member 15, a plurality of leaf spring pieces 23 are disposed so as to be partially wrapped in the circumferential direction, and are urged against the inner body member 5.

The erector device 24 for lining a segment on the inner surface of the main line tunnel T will be described with reference to FIG.
As shown in FIG.
And an electric or hydraulic drive motor (not shown) that rotationally drives the rotary body 25 and the electret body 26. A plurality of brackets 27 are provided with support rollers 28, respectively. At 28, it is rotatably supported. Each time the tunnel T is excavated by one ring, the segment is assembled by the erector device 24 over the entire circumference of the tunnel wall of one ring.

The earth discharging device 29 for discharging earth and sand excavated by the cutter disk 2 will be described. The earth discharging device 29 has a screw conveyor 30 and the screw conveyor 3.
Reference numeral 0 denotes a divided-type cylindrical casing 31, an auger 32 disposed inside the cylindrical casing 31, an auger rotation drive mechanism 33, a screw gate (not shown) provided inside the cylindrical casing 31, and the like. Have. The auger 32 has a structure in which the auger 32 is divided at a bent portion at a substantially middle portion in the longitudinal direction of the cylindrical casing 31, and includes a first auger on the front side and a second auger on the rear side.
It consists of an auger. Auger rotation drive mechanism 33
Is composed of a first drive motor 33a and a second drive motor 33b, and the first and second augers are the first and second drive motors 33a.
a and 33b are configured to be rotatable respectively.

Next, the structure of the branch line shield machine 40 will be described. Note that the front, rear, left and right in the excavation direction will be described as front, rear, left and right. As shown in FIGS. 4 and 5, the branch line shield excavator 40 includes a trunk member 41, a cutter disk 42, a cutter driving motor 43, a plurality of center bending jacks 44, a plurality of shield jacks 45, and a muddy water discharging device. (Not shown) or an earth pressure type earth discharging device 46 and an elector device 47.

The body member 41 includes a front body 48 and a rear body 50 connected to a rear end of the front body 48 via a center bent portion 49. A chamber 51 is formed at the back of the cutter disk 42, and a partition wall 52 that partitions the rear end of the chamber 51 is
It is provided transversely inside the front trunk 48 and is fixed to the front trunk 48. The muddy-type soil discharging device will be described. The muddy-type soil discharging device is applied at the stage of branching and starting while sequentially adding the trunk member of the branch line shield excavator 40, and an opening / closing valve capable of opening and closing the muddy passage, and a pressure pump. And a muddy hose that occupies most of the muddy water passage, and a sediment pumping pipe (all not shown). The partition 52 is provided in advance with a gate mechanism 54 capable of opening and closing the suction port 53 of the muddy water discharging device.

The gate mechanism 54 is, for example, a double-opening type 1
It has a pair of gate plates, a pair of hydraulic cylinders for driving the gate plates to open and close along upper and lower guide members, and a nozzle for water injection for preventing sediment from accumulating on the opening and closing portions of the gate plates. The water injection nozzle is provided with a supply tank for supplying water, a pump, a hose, a connection fitting, and the like.

The earth pressure type earth discharging device 46 will be described.
At the stage where the addition of the trunk member of the branch line shield excavator 40 is completed, the earth pressure type earth removal device 46 is connected to the suction port 53 to which the drainage pipe of the mud type earth removal device is connected after removing the mud type earth removal device. It has a screw conveyor 55 to be connected. The screw conveyor 55 includes an auger 57 disposed inside the cylindrical casing 56 and an auger rotation drive mechanism 58.
And an advancing and retreating mechanism that can advance and retreat the auger 57 by a predetermined distance.

A process for excavating the main line tunnel T by the above-described main line shield excavator 1 and branching and starting the branch line shield excavator 40 at a branch point will be described. FIG. 6 is a schematic explanatory diagram thereof. 7 to 16 show cross-sectional planes of the main part of the left part at each stage of the shield tunneling of the main line tunnel T. In the first step, as shown in FIG. 7, the inner trunk member 5 is overlaid on the inner surface side of the main trunk member 15, and the inner trunk member 5 is fixed to the main trunk member 15 by a fixing bracket 59 so as to be releasable. The main line tunnel T is excavated while being held.

In the second step, as shown in FIGS. 8 and 9,
During the excavation of the main line tunnel T, the fixing bracket 59 is removed to release the fixing of the inner trunk member 5 to the main trunk member 15 (that is, the excavator main body 4), and between the reinforced segment Sa and the shield jack 18. Then, a steel special segment Sb (for example, a concrete segment other than steel) for forming the branch start port 60 (see FIG. 12) is constructed for one ring.
Next, the special segment Sb and the shield jack 18
And a plurality of fixed plates 61 are welded to the rear end of the inner body member 5 on the inner surface side at appropriate intervals in the circumferential direction. Thereafter, the shield jacks 18 are extended and the spreader is brought into contact with the fixing plate 61 to thereby integrally connect the inner trunk member 5 to the special segment Sb via the fixing plate 61.

In the third step, as shown in FIG. 10, the excavator body 4 and the trunk member 3 are moved forward relative to the inner trunk member 5, and moved forward by one ring of the special segment Sb. Then, after each fixing plate 61 is separated from the inner body member 5 by gas fusing, the special segment Sb is further constructed for one ring. By repeating a series of operations starting from the welding and joining of the fixing plate 61 a plurality of times, the inner trunk member 5 relatively extends rearward from the rear end portion of the trunk member 3 and branches as an opening of the special segment Sb. A launch port 60 can be formed.

Next, the entire shield excavator 1 is moved forward while excavating in the main tunnel T, and the shield jack 18 in which the reinforced special segment Sb and the rod are retracted.
And a water stop segment Sc for one ring is assembled.
The water stop segment Sc is a segment for stopping water between the main body member 15 and a tube seal is housed in an annular concave portion on the outer peripheral side thereof, and a pressurized water injection pipe for supplying pressurized water to the tube seal; A pressurized water injecting mechanism including a pressurized water supply source is provided.
5 is sealed in a liquid-tight manner.

Next, as shown in FIG.
A starting port ring 62 made of steel is assembled so as to be connected to zero, and connected to the special segment Sb by, for example, a bolt or welding. An annular water stop seal mechanism 6 is provided on the inner surface of the start port ring 62.
3 is mounted in advance. At this time, since the branch start port 60 is formed on the inner surface side of the inner trunk member 5, it is possible to prevent the groundwater from flowing into the tunnel T. Thereafter, the front end portion of the branch line shield excavator 40 (at least the portion including the cutter disc 42, the front trunk 48 of the trunk member 41 and its internal devices) is carried in from the outside, and partially inserted into the start port ring 62. Set. Next, the tube seal of the water-stop segment Sc is elastically deformed to an expanded state to seal the space between the water-stop segment Sc and the main body member 15 in a liquid-tight manner, and the water-stop seal mechanism 63 of the start-up port ring 62 is operated to close the tube seal. After that, the starter ring 62 is filled with a filler 64 such as high-concentration muddy water.

In the fourth step, as shown in FIGS. 11 and 12, the fixing plate 61 is separated from the inner body member 5 by gas fusing.
The front end of the inner trunk member 5 is attached to the body trunk member 15 by a plurality of fasteners 6.
5 and welded at equal intervals in the circumferential direction. afterwards,
The entire shield excavator 1 is moved forward while excavating the main line tunnel T, and the shield excavator 1 is moved from the branch start port 60 while the special segment Sb for a predetermined ring is constructed between the water stop segment Sc and the shield jack 18. Also move forward. That is, the rear end of the inner trunk member 5 is advanced forward from the branch start port 60.

In the fifth step, as shown in FIG. 13, the branch line shield excavator 40 is started from the branch start port 60 to start excavation of the branch line tunnel Ta. By connecting the trunk 50 and appropriately constructing or relocating the reaction force support member, the branch line tunnel T
Excavation of a is performed. After the fifth step, a ring member 66 with a tail seal is provided at the rear end of the main body member 15 of the shield machine 1 in an in-fit state. The ring member 66 with a tail seal is provided with a ring portion 67, a thin tail ring 68 integrally connected to the rear end of the ring portion 67, and an inner circumferential surface of the tail ring 68 at appropriate intervals in the front-rear direction. It is composed of two rows of tail seals 69 and the like, and is slidably disposed in the front-rear direction.

Thereafter, as shown in FIGS. 14 and 15, one ring of special segments S
b, a plurality of retaining plates 70 are arranged at the front end of the special segment Sb, and are welded to the ring portion 67 of the ring member 66 in a T-shaped cross section. Next, after the ring member 17 of the main body member 16 is welded to the main body member 15 with a reinforcing plate 71 to extend the shield jack 18, each stop plate 7
0 is sequentially separated from the ring member 66 by gas fusing. In parallel with this, the ring member 66 is welded to the body member 15. Next, as shown in FIG. 16, the plurality of spacers 72 are welded to the main body member 15 at appropriate circumferential intervals and on the front end side of the ring portion 67 of the ring member 66.
Thereafter, the excavation of the main line tunnel T is resumed while constructing the concrete segment Sa. Thereafter, the inner trunk member 5 is buried underground.

After the branch line shield excavator 40 is branched and started to excavate for a predetermined distance, the pair of gate plates are closed by the pair of hydraulic cylinders of the gate mechanism 54, and then the muddy soil removal device is removed. . Next, in place of the muddy discharge device, an earth pressure discharge device 4 including a screw conveyor 55 is used.
The earth pressure type earth discharging device 46 is connected to the suction port 53 to which the drain pipe of the muddy earth discharging device is connected, and the earth and sand is discharged by the earth pressure type earth discharging device 46.

According to the branch shield excavating method described above, the shield excavator 1 is provided with the inner body member 5 in advance,
By performing the process to the fifth process, the branch line shield machine 4
0 can be branched and started. Since the inner trunk member 5 is superimposed on the inner surface side of the trunk member 3 and the inner trunk member 5 is fixed to the excavator main body 4, excavation of the main line tunnel T is performed. This is advantageous in terms of rigidity of the trunk member 5 and the trunk member 3. Therefore, shield machine 1
Can be secured, the increase in the capacity of the shield jack 18 can be suppressed, and insufficient strength of the segment can be solved. The number of parts can be reduced and the structure can be simplified as compared with the conventional one described in the above publication, which is advantageous in terms of manufacturing cost.

In particular, after the branch line shield excavator 40 branches off and starts, the inner trunk member 5 does not need to be overlaid again on the trunk member 3 and may be left in the ground. Compared with the method, it is not necessary to keep the sealing performance between the inner trunk member 5 and the trunk member 3 high. Since it is not necessary to replace the stopper plate with the inner body member when the inner body member is superimposed on the body member, the number of work steps can be reduced accordingly, and the construction period can be shortened. After the fifth step, a ring member 66 with a tail seal is slidably provided in the rear end portion of the body member 3 so as to be fitted inside.
Since the body 6 is fixed to the trunk member 3, it is possible to prevent earth and sand from entering the inside of the excavator body 4 after the excavation of the main line tunnel T is resumed.

Next, a modified embodiment in which this embodiment is partially modified will be described. 1) In the second step, the rear end of the inner trunk member 5 may be releasably connected to the front end of the covered segment Sb by a fixing pin without using the fixing plate 61. 2) A concrete segment (for example, carbon fiber, glass fiber, aramid fiber, or the like is impregnated with resin in the starting port ring 62 or the branch starting port 60) using a fiber reinforcing material that can be cut by the cutter disk 42 of the branch line shield excavator 40. It is also possible to provide and seal in advance the concrete material provided in the concrete as a reinforcing material, and then start the branch while cutting the concrete material. In addition, without departing from the spirit of the present invention, it is possible to implement the above-described embodiment with various modifications.

[0038]

According to the first aspect of the present invention, the shield excavator is provided with the inner trunk member in advance, and the first to fifth steps are performed, so that the branch line shield excavator is branched and started. Can be. Since the inner trunk member is overlapped on the inner surface side of the trunk member and the inner trunk member is fixed to the excavator main body, the tunnel of the main line is excavated, so that the length of the shield excavator does not increase and the inner trunk member and the trunk member This is advantageous in terms of rigidity. Therefore, the turning performance of the shield excavator can be secured, the increase in the capacity of the shield jack can be suppressed, and insufficient strength of the segment can be solved. The number of parts can be reduced and the structure can be simplified as compared with the conventional one described in the above publication, which is advantageous in terms of manufacturing cost.

In particular, after the branch line shield excavator has started branching, the inner trunk member need not be overlaid on the trunk member and can be left in the ground, so that it can be compared with the branch shield excavation method proposed by the present applicant. Therefore, it is not necessary to keep the sealing performance between the inner trunk member and the trunk member high. Since it is not necessary to replace the stopper plate with the inner body member when the inner body member is superimposed on the body member, the number of work steps can be reduced accordingly, and the construction period can be shortened.

According to the second aspect of the present invention, after the fifth step, a ring member with a tail seal is provided at the rear end of the body member so as to be slidable in an inner fitting manner. Since it is fixed to the member, it is possible to prevent earth and sand from entering the inside of the excavator body after resuming the excavation of the main line tunnel. The other effects are the same as those of the first aspect.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a main line shield machine according to an embodiment of the present invention.

FIG. 2 is a vertical sectional view of a main part of an excavator main body of the main line shield excavator.

FIG. 3 is an enlarged longitudinal sectional view of a main part showing a rear end portion of an inner trunk member and a main trunk member.

FIG. 4 is a longitudinal sectional view of a branch line shield machine.

FIG. 5 is a vertical sectional view of a main part of an excavator body and the like of a branch line shield excavator.

FIG. 6 is an explanatory view of a stage in which a branch line shield excavator branches and starts from a branch point in the middle of a main line tunnel;
(A) is a diagram showing a preparation stage for forming a branch start port, (b) is a diagram showing a shield machine and a branch line shield machine before starting, and (c) is a state immediately after the branch line shield machine has started. (D) is a diagram showing a state after the branch excavation of the shield machine.

FIG. 7 is a cross-sectional plan view of a main part showing a preparation stage for moving the body trunk member forward.

FIG. 8 is a cross-sectional plan view of a main part showing a relationship between an inner trunk member and a reinforced segment.

9 is a cross-sectional plan view of a main part showing a state where the state shown in FIG. 8 is developed.

FIG. 10 is a cross-sectional plan view of a main part in a state where a main body member is moved forward.

FIG. 11 is a cross-sectional plan view of a main part of the shield excavator and a part of the branch line shield excavator showing a preparation stage for starting the branch line shield excavator.

FIG. 12 is a cross-sectional plan view of a main part in a state where the shield machine is advanced from a branch start port.

FIG. 13 is a cross-sectional plan view of a main part of a branch line shield machine immediately after a branch starts.

14 is a cross-sectional plan view of a main part showing a state where the state shown in FIG. 13 is developed.

15 is an essential part cross-sectional plan view showing a state where the state shown in FIG. 14 is developed.

16 is a cross-sectional plan view of a main part showing a state where the state shown in FIG. 15 is developed.

[Explanation of symbols]

 Reference Signs List 1 shield machine 3 body member 4 machine body 5 inner body member 40 branch line shield machine 60 branch start port 66 ring member Sb special segment

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Naoo Manabe 8 Harima-machi, Harima-cho, Kako-gun, Hyogo Kawasaki Heavy Industries, Ltd. Harima Factory Co., Ltd. (72) Inventor Mitsuo Shimizu 8 Harima-machi, Harima-cho, Kako-gun, Hyogo Prefecture Kawasaki Heavy Industries Co., Ltd. Harima Factory Co., Ltd. (72) Inventor Makoto Ukegawa 1-7-1 Kyobashi, Chuo-ku, Tokyo Toda Construction Incorporation (72) Inventor Takeshi Yagura 1-7-1 Kyobashi, Chuo-ku, Tokyo Toda Construction (72) Inventor Minoru Motoki 1-7-1, Kyobashi, Chuo-ku, Tokyo Toda Construction F-term (reference) 2D054 AA03 AC02 AD20 AD32 BA03 EA09

Claims (2)

[Claims] 1. A branch shield excavating method for excavating a main line tunnel with a shield excavator and branching and starting a branch line shield excavator at a branch point in the middle of the main line tunnel. An inner trunk member is fitted in advance so as to be relatively slidable rearward in the axial direction of the tunnel, and the inner trunk member is overlapped on the inner surface side of the trunk member and the main trunk member is fixed to the excavator body. A second step of releasing the fixing of the inner trunk member to the excavator body and connecting the rear end of the inner trunk member to the reinforced segment during the excavation of the main line tunnel; A third step of moving the excavator main body and the trunk member forward relative to the inner trunk member, constructing segments for a plurality of rings on the inner surface of the inner trunk member, and forming a branch start port. And a fourth step of fixing the front end of the inner trunk member to the trunk member and advancing the shield excavator from the branch start port, and branching and starting the branch line shield excavator from the branch start port, A fifth step of releasing the fixation of the inner trunk member to the trunk member. 2. The branch shield excavating method according to claim 1, wherein after the fifth step, a ring member with a tail seal is provided at the rear end of the trunk member of the shield excavator in an in-fit state. .