JP2006291636A - Concrete placing device and tunnel excavator equipped with the device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a concrete placing device which facilitates washing of a concrete placing line, contributes to shortening of a washing time, and achieves setup of re-excavation in a short period of time, and also to provide a tunnel excavator equipped with the concrete placing device. <P>SOLUTION: The concrete placing device is comprised of: an inner form S for covering a peripheral wall of the excavated natural ground G so as to be spaced a predetermined interval away from the same; and an end form 46 for securing a concrete placement space E between the inner form and the peripheral wall of the natural ground. The end form has a front end of a straight pipe portion of a concrete placing pipe 50 inserted therein and fixed thereto. Then a branch pipe portion branched from a proximal end of the straight pipe portion has a concrete placing pipe arrangement 51 detachably connected thereto, which communicates with a concrete feed source. Further the proximal end of the straight pipe portion has connected thereto a block valve device 60 having a jack 62 and a rod piston 63 attached to the rod tip od the jack. When the jack is contracted, the rod piston recedes, and then the branch pipe portion of the placing pipe communicates with the straight pipe portion. On the other hand when the jack is extended, due to advancement of the rod piston, communication between the branch pipe portion and the straight pipe portion is interrupted, and concrete remaining in the straight pie portion is pushed into a placement space. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a concrete placing apparatus used in a lining method by ECL (Excluded Concrete Lining) and a tunnel excavator equipped with the apparatus.

  As a tunnel excavator employing the lining method, a mud pressure shield excavator is well known (see Patent Document 1). While excavating the ground with a cutter head provided on the front part of the cylindrical excavator body, the inner wall surface of the tunnel that has been dug is covered with an inner mold frame at a predetermined interval. Concrete is placed by direct placement (place-in-place), for example, by appropriately placing reinforcing bars between the inner wall surface, and lining is performed after curing and hardening.

  In the mud pressure shield excavator as described above, a ring-shaped wife mold (device) for closing the space between the inner wall surface of the tunnel and the inner mold is provided, and through the wife mold, the ring mold While concrete is cast, the wife form frame can be slid in the front-rear direction (longitudinal direction of the tunnel) through the expansion and contraction of the wife form frame jack.

  Further, in the concrete placing apparatus used in the lining method, as shown in FIG. 7, the tip of the concrete pipe (hose) 100 in the concrete placing line is a blocking valve 101 such as a ball valve type and a sheath pipe 102. Connected to the wife formwork 103. In the figure, reference numeral 104 denotes an excavator body (skin plate), 105 denotes an inner mold, C denotes concrete placed, and G denotes a natural ground.

  Therefore, under excavation by a shield excavator, the blocking valve 101 is opened, and the peripheral wall of the natural ground G passes through a concrete pipe (hose) 100 → the blocking valve 101 → the sheath pipe 102 from a concrete supply source (not shown). The concrete C is placed and filled in the gap between the inner mold 105 and the previously assembled inner mold 105.

  On the other hand, when the shield excavator is stopped by inspection or the like, after closing the closing valve 101, the concrete pipe (hose) 100 is removed from the closing valve 101, and the residual concrete in the concrete pipe (hose) 100 is cured. The concrete pipe (hose) 100 is cleaned with high-pressure cleaning water or the like. On the other hand, the sheath tube 102 and the closing valve 101 are cleaned after the concrete C placed in the gap between the peripheral wall of the natural ground G and the inner mold 105 is cured. That is, the sheath tube 102 is withdrawn from the sheath tube insertion hole 103a of the closing mold 101 for each of the closing valves 101, and then the sheath tube 102 and the closing valve 101 are separated and cleaned, and then the wife is reconnected. The concrete pipe (hose) 100 that has been cleaned is attached to the mold 103 and finally to the closing valve 101.

JP 2001-173387 A JP 2001-090488 A JP-A-10-115196

  However, in the conventional concrete placing apparatus described above, when the shield excavator is stopped and then re-excavated, the concrete C placed in the gap between the peripheral wall of the natural ground G and the inner mold 105 is awaited to harden. In this case, the step of removing the sheath tube 102 and the closing valve 101 from the wife formwork 103 and cleaning them is necessarily performed, so that it takes a lot of time to set up the re-excavation. Further, in cleaning the sheath tube 102 and the shut-off valve 101, there is a problem that the cleaning operation is troublesome because the concrete remaining inside is also hardened.

  In Patent Document 2, the concrete supply pipe inserted obliquely into the end form frame is opened and closed with a piston type valve body that can move in the valve body accommodation hole formed in the end form frame, and the shield excavator A technique is disclosed in which the concrete supply pipe is closed by the movement of the valve body at the time of stopping and the concrete remaining in the valve body accommodation hole is pushed out into the concrete placement space. However, also in this patent document 2, when the shield excavator is stopped, the concrete supply pipe must be removed from the wife formwork and cleaned, and after cleaning, it must be attached to the wife formwork again, so that the cleaning work becomes complicated. There is.

  Further, in Patent Document 3, a concrete supply pipe connected to a casing having a filling port and a washing pipe through which washing water flows are appropriately switched by the movement of a piston provided with a water supply passage, and concrete pouring is performed. A technique is disclosed in which each tube is washed with washing water alternately. However, in Patent Document 3, there is a problem that the piping is complicated and the apparatus becomes large, resulting in an increase in cost.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a concrete placement device that can easily clean a concrete placement line, shorten the cleaning time, and can perform setup for re-digging in a short time, and a tunnel excavator equipped with the device. .

In order to achieve such an object, a concrete placing apparatus according to the present invention includes an inner mold frame that covers an inner wall surface of a tunnel at a position spaced a predetermined distance from the inner wall surface of the tunnel, the inner mold frame, and an excavator. It is arranged between a skin plate that forms an outer shell, and includes a wife formwork that forms a concrete placement space between the inner formwork and the inner wall surface of the tunnel,
Insert and fix the end of the straight pipe part in the concrete casting pipe to the end formwork,
While detachably connecting the concrete placement pipe leading to the concrete supply source to the branch pipe part branched from the base end side of the straight pipe part, a blocking valve device is connected to the base end of the straight pipe part,
The closing valve device has a jack and a rod-like piston attached to the rod tip of the jack,
When the jack contracts, the branch pipe portion of the concrete placing pipe communicates with the straight pipe portion by retreating the rod-shaped piston, while when the jack extends, the branch pipe portion and the straight pipe portion are moved by the advance of the rod-shaped piston. And the residual concrete in the straight pipe portion is pushed out into the concrete placement space.

  Further, the rod-like piston is provided with a first packing detachably at its tip, and a second packing is detachably provided at the outer periphery of the intermediate portion. When the jack is extended, the branch pipe portion is formed by the second packing portion. The connection between the pipe and the straight pipe portion is cut off.

  The blocking valve device is connected to the base end of the straight pipe portion via a connecting pipe.

In order to achieve such an object, a tunnel excavator according to the present invention is supported by a tubular excavator main body, a propulsion jack for advancing the excavator main body, and a front part of the excavator main body so as to be rotationally driven. In a tunnel excavator comprising a cutter head and a driving means for rotating the cutter head,
The concrete placing device is provided.

  According to the concrete placing device according to the present invention, it is not necessary to remove and clean the concrete placing pipe and the blocking valve device between re-digging after the stop in inspection of the excavator and the like. Cleaning is easy, shortening the cleaning time and setting up re-digging in a short time.

  In addition, the rod-like piston has a first packing detachably attached to the tip thereof, and a second packing detachably attached to the outer periphery of the intermediate portion. When the jack is extended, the branch packing portion and the straight pipe portion are used as the second packing portion. Therefore, it is possible to maintain good sealing performance by appropriately replacing each packing. Further, since the blocking valve device is connected to the proximal end of the straight pipe portion via a connecting pipe, the stroke of the jack can be arbitrarily selected, and the degree of freedom in designing the blocking valve device can be obtained.

  According to the tunnel excavator according to the present invention, the concrete excavation line can be easily cleaned, and the concrete excavation apparatus can be provided to shorten the cleaning time and perform the re-excavation in a short time, thereby increasing the excavation efficiency of the tunnel excavator. be able to.

  Hereinafter, a concrete placing device according to the present invention and a tunnel excavator equipped with the device will be described in detail with reference to the drawings.

  1 is a schematic cross-sectional view of a tunnel excavator showing an embodiment of the present invention, FIG. 2 is an enlarged cross-sectional view of a concrete placing device (when a closing valve is open), and FIG. 3 is a cross-sectional view taken along line III-III in FIG. 4 is a detailed enlarged sectional view of the closing valve, FIG. 5 is an enlarged sectional view of the concrete placing device when the closing valve is closed, and FIG. 6 is a sectional view taken along line VI-VI in FIG.

  The tunnel excavator described in this embodiment is a mud pressure shield excavation that builds a tunnel while stabilizing the face by filling the chamber with excavated earth and sand and maintaining the inside of the chamber at a predetermined pressure. Machine.

  In this mud pressure shield excavator, as shown in FIG. 1, the excavator main body 11 has a front barrel 12 and a rear barrel 13 which are formed in a cylindrical shape having substantially the same diameter, and are connected to each other by a connecting shaft 14 so as to be bent right and left. It can be bent by a plurality of middle folding jacks 15 installed between them. A rotating ring 16 is rotatably supported on the front portion of the front barrel 12, and a cutter head 18 is connected to the rotating ring 16 via a connecting beam 17.

  The cutter head 18 is configured such that a plurality of cutter spokes 19 are arranged radially from the center portion, and the respective front end portions are connected by an outer peripheral ring 20. A fishtail cutter 21 is attached to the center of the cutter head 18, while a plurality of cutter bits 22 are attached to both sides of each cutter pork 19 along the longitudinal direction thereof. A copy cutter 23a and a rescue bit 23b for performing excessive digging are provided at the front end portion so as to freely appear and disappear.

  A ring gear 24 is fixed to the rear portion of the rotary ring 16, and a plurality of cutter turning motors (drive means) 25 are attached to the front body 12 of the excavator body 11. The drive gears 26 are meshed with the ring gear 24, respectively. Accordingly, when the cutter turning motor 25 is driven to drive the drive gear 26 to rotate, the cutter head 18 can be rotated via the ring gear 24, the rotating ring 16, and the connecting beam 17.

  In addition, a bulkhead 27 is provided at the front portion of the front cylinder 12 so as to be located behind the cutter head 18, and a chamber 28 is formed between the cutter head 18 and the bulkhead 27 for filling excavated earth and sand. Yes. A plurality of fixed stirring rods 29 project from the front side of the bulkhead 27, while a plurality of swirling stirring rods 30 project from the rear surface side of the cutter head 18. A part of the fixed stirring rod 29 is provided with a not-shown mud-material injection port for injecting a mud-material into the excavated soil in the chamber 28, and a not-shown chemical-solution injection pipe for injecting a chemical solution (consolidated material). Is provided. In the excavator main body 11, a screw conveyor 33 for carrying the excavated earth and sand to the outside is disposed, and the front portion is inclined downward to penetrate the bulkhead 27 and open into the chamber 28. ing.

  A ring garter 34 is fixed to the rear cylinder 13 of the excavator body 11 along the inner peripheral surface thereof, and a plurality of shield jacks (propulsion jacks) 35 are arranged on the ring garter 34 in the circumferential direction of the rear cylinder 13. The excavator body 11 can be advanced by the reaction force by extending the shield jack 35 rearward and pressing the spreader 36 against the existing inner formwork (formwork) S. .

  A plurality of inner molds S are assembled in a ring shape in the circumferential direction with a predetermined interval on the inner wall surface of the tunnel (the peripheral wall of the natural ground G). The concrete is placed by direct placement (place-in-place) by a concrete placement device described later in the space (concrete placement space E) between the peripheral wall of the inner mold S and the outer peripheral surface of the inner mold S assembled in a ring shape, A tunnel is built. Further, the inner mold S is assembled in a plurality of stages in the longitudinal direction of the tunnel.

  In addition, a swivel ring 38 is supported on the ring gutter 34 so as to be able to swivel along the circumferential direction of the inner wall surface of the tunnel, and can be driven and swiveled by a drive motor (not shown). An inner mold assembly apparatus 39 is provided. Further, a pair of left and right columns 40 are fixed to the ring gutter 34, and a substantially horizontal frame 41 is extended rearward from the column 40, and this frame 41 assists in assembling the inner formwork S. A pair of front and rear shape holding devices 42 are mounted so as to be movable in the front-rear direction.

  Further, a plurality of transfer carts (not shown) are connected to the rear end of the gantry 41, and an inner mold release device for removing the inner mold S at the rear stage, and the inner mold release device are connected to these transfer carts. A hoist that transports the inner mold form S that has been removed in step 1 to the front of the tunnel, a power unit of a concrete placing device, and the like are mounted.

  Furthermore, between the rear trunk (skin plate) 13 and the inner mold S, there is a ring-shaped wife mold 46 that forms a concrete placement space E between the inner mold S and the peripheral wall of the natural ground G. In addition to being disposed, a plurality of wife form jacks 47 are arranged in parallel along the circumferential direction, and the head base end portion passes through the ring gutter 34 and is connected to the inner peripheral portion of the rear barrel 13. On the other hand, the tip end of the rod is connected to the end form frame 46. A rubber seal member 48 (see FIG. 2) is attached to the outer peripheral surface of the end form frame 46 along the circumferential direction, and a metal brush seal 49 is provided on the inner peripheral surface of the end form frame 46. It is mounted along the circumferential direction.

  Accordingly, the ring-shaped wife mold frame 46 can be moved back and forth by expanding and contracting the wife mold jack 47. At this time, the seal member 48 is pressed against the inner peripheral surface of the rear barrel 13, and the brush By pressing the seal 49 against the outer peripheral surface of the existing inner mold S assembled in a ring shape, it is possible to prevent water from entering the excavator body 11.

  A plurality of concrete placement pipes 50 are inserted into the end form frame 46 at a predetermined interval in the circumferential direction toward the rear of the excavation direction, and the concrete placement pipes 50 are connected to a closing valve device 60 described later. It is possible to communicate with a concrete placement pipe (hose: concrete placement line) 51 by switching between them. These concrete placement pipes 51 are communicated with a concrete supply source via the power unit on the transport carriage described above.

  Therefore, under the state where the concrete placement pipe 50 and the concrete placement pipe 51 are communicated with each other by the closing valve device 60, the ready-mixed concrete fed from the concrete supply source is connected to the concrete placement pipe 51 and the concrete placement pipe 50. It passes through the concrete placement space E described above. At this time, in the concrete placement space E, the concrete placement pipes 50 are sequentially placed in the circumferential direction.

  Further, a concrete placing device is constituted by the inner form S, the end form 46, the concrete placing pipe 50, the concrete placing pipe 51, the closing valve device 60 and the like.

  As shown in FIGS. 2 and 3, the concrete placing pipe 50 is formed in a Y-tube shape including a straight pipe portion 50a and a branch pipe portion 50b, and the latter half portion of the straight pipe portion 50a is a wife formwork. 46 is fixedly inserted. The concrete placement pipe 51 is detachably flanged to the front end of the branch pipe portion 50b, while the blocking valve device 60 is assembled to the front end of the straight pipe portion 50a via the connecting pipe 61.

  The closing valve device 60 is connected to the opening / closing / cleaning jack 62 connected to the front end of the connecting pipe 61 and the rod end of the jack 62, and is connected to the connecting pipe 61 and the straight pipe portion 50a of the concrete placing pipe 50. When the jack 62 is contracted (when contracted), the straight pipe portion 50a and the branch pipe portion 50b of the concrete placing pipe 50 are moved by the retreat of the rod-like piston 63. In communication (see FIGS. 2 and 3), when the jack 62 is extended (when extended), as shown in FIGS. 5 and 6, the rod-like piston 63 is advanced to branch from the straight pipe portion 50a of the concrete placing pipe 50. The communication with the pipe part 50b is blocked, and the residual concrete in the straight pipe part 50a is pushed out into the concrete placement space E.

  As shown in FIG. 4, the rod-like piston 63 is connected to a center rod 64 screwed to the rod tip of the jack 62, and to the tip of the center rod 64 by a bolt 66 and a holding plate 66a via a first collar 65. The first packing 67, the first pipe (spacer) 68, the second collar 69, the second packing 70, the second pipe (spacer) 71, and the like, which are sequentially fitted onto the central rod 64 from the front end side. In order to prevent the fitting member from coming off, a nut 72 screwed to the proximal end of the center rod 64 is provided. When the jack 62 is extended, as shown in FIGS. Thus, the branch pipe portion 50b of the concrete placing pipe 50 is closed in a sealed state by the second packing 70, and the concrete placing space E is sealed by the first packing 67.

  In FIG. 3, reference numeral 73 denotes a cleaning water discharge elbow that is paired with a cleaning water supply elbow (not shown) for cleaning the inside of the connecting pipe 61, and 74 is a pressure gauge for detecting the pressure in the concrete placing pipe 51. Reference numeral 75 denotes a support for supporting the concrete placing pipe 51.

  Next, tunnel excavation work by the mud pressure shield excavator of the above-described embodiment will be described.

  As shown in FIG. 1, while rotating the cutter head 18 by the cutter turning motor 25, the plurality of shield jacks 35 are extended to press the spreader 36 against the existing inner form S, and the reaction force causes the excavator body 11 to move. Move forward. Then, each cutter bit 22 of the cutter head 18 excavates the front ground, and excavated earth and sand are taken into the chamber 28 from between the respective cut porks 19 and are carried out by the screw conveyor 33 to the outside.

  In the inner formwork assembly apparatus 39, the inner formwork S carried into the tunnel is grasped and moved along the inner wall surface of the tunnel, and the grasped inner formwork S is fixed at a predetermined position in a ring shape. Assemble. At this time, the front shape holding device 42 corrects the inner mold frame S to a normal assembly position while avoiding interference with the inner mold frame assembling device 39, and the rear shape holding device 42 is assembled in a ring shape. The inner mold S is corrected to be a perfect circle.

  In parallel with the assembly of the inner formwork S by the inner formwork assembling apparatus 39, the concrete placement apparatus E creates a concrete placement space E between the peripheral wall of the excavated ground G and the outer peripheral surface of the existing inner formwork S. Ready-mixed concrete is cast.

  That is, the jack 62 of the closing valve device 60 is contracted, and the straight pipe portion 50a and the branch pipe portion 50b of the concrete placing pipe 50 communicate with each other by the retreat of the rod-shaped piston 63 (the state shown in FIGS. 2 and 3). Reference), the ready-mixed concrete fed to the concrete placement pipe 51 is supplied to the concrete placement space E through the branch pipe portion 50b and the straight pipe portion 50a.

  At this time, by operating the end form jack 47 to the extension side, the end form mold 46 is pressed against the placed concrete, and the concrete is filled to every corner of the concrete placement space E. . Thereafter, when a predetermined time elapses, the concrete is cured and hardened, and the tunnel structure is firmly constructed.

  Further, when the excavator body 11 is propelled, the inner mold S is assembled and assembled. That is, when a predetermined time elapses after the ready-mixed concrete is continuously poured into the concrete placing space E, the concrete is gradually cured and hardened. Therefore, the inner mold S on the rear side corresponding to the cured and hardened concrete is removed (demolded) by an inner mold demolding device (not shown) and transported to the front of the tunnel by a hoist (not shown) to assemble the inner mold. It is used for new assembly by the device 39.

  On the other hand, when the mud pressure shield excavator is stopped by inspection or the like, the placement of ready-mixed concrete into the concrete placement space E by the concrete placement device is stopped. At this time, the jack 62 of the closing valve device 60 is extended, and the communication between the straight pipe portion 50a and the branch pipe portion 50b of the concrete placing pipe 50 is blocked by the second packing 70 portion by the advance of the rod-like piston 63. At the same time, the residual concrete in the straight pipe portion 50a is pushed out into the concrete placement space E by the first packing 67 portion (see the state of FIGS. 5 and 6).

  Thereafter, the concrete placement lines are washed before the ready-mixed concrete in the concrete placement pipe 51 and the branch pipe portion 50b of the concrete placement pipe 50 is not hardened. That is, the concrete placement pipe 51 is separated from the concrete placement pipe 50 and washed with high-pressure washing water as before, while the branch pipe portion 50b of the concrete placement pipe 50 places the concrete placement pipe 50 into the wife formwork 46. It is washed with high-pressure washing water in the attached state.

  In this embodiment, the ready-mixed concrete leaked from the second packing 70 into the connecting pipe 61 is washed with high-pressure washing water using a washing water discharge elbow 73 that is paired with a washing water supply elbow (not shown). You can also

  In this way, in this embodiment, when the mud pressure shield excavator is stopped, the branch pipe portion 50b of the concrete placing pipe 50 that leads to the supply source of the ready concrete through the concrete placing pipe 51 is the first piston 63. Since the residual concrete in the straight pipe portion 50a of the concrete placement pipe 50 leading to the concrete placement space E is pushed out to the concrete placement space E by the first packing 67, the mud pressure type is closed. At the time of cleaning after stopping the shield excavator, there is no residual concrete in the blocking valve device 60 and the straight pipe portion 50a of the concrete placing pipe 50. There is no work of removing and cleaning concrete after it has hardened. In other words, re-digging can be started as it is. Moreover, since the branch pipe part 50b of the concrete placing pipe 50 is also a short pipe, it can be easily cleaned as it is even if it cannot be removed.

  As a result, the concrete placement line can be easily cleaned and the cleaning time can be shortened, and the number of parts removed at the time of cleaning can be reduced, so that the re-digging can be set up in a short time. Further, even during excavation by a mud pressure shield excavator, when waiting for placing in the state shown in FIG. 2 and FIG. The dead concrete adhered and deposited in the straight pipe portion 50a of the concrete placing pipe 50 can be pushed out into the concrete placing space E and removed.

  Further, in this embodiment, the rod-like piston 63 is provided with a first packing 67 detachably at its tip, and a second packing 70 is detachably attached to the outer periphery of the intermediate portion. When the jack 62 is extended, the second packing 70 is provided. Since the communication between the branch pipe part 50b and the straight pipe part 50a is cut off at 70 parts, it is possible to maintain good sealing performance by appropriately replacing each packing. Further, since the blocking valve device 60 is connected to the proximal end of the straight pipe portion 50a via the connecting pipe 61, the stroke of the jack 62 can be arbitrarily selected, and the degree of freedom in designing the blocking valve device 60 is obtained. It is done.

  In this way, the concrete placement apparatus is provided with a concrete placement device that can easily clean the concrete placement line and can shorten the cleaning time and set up re-digging in a short time, so that the excavation efficiency of the mud pressure shield excavator can be increased.

  The tunnel excavator according to the present invention can be applied not only to a mud pressure shield excavator but also to a mud shield excavator, a mechanical shield excavator, a tunnel boring machine (TBM), and the like.

It is a schematic sectional drawing of the tunnel excavator which shows one Example of this invention. It is an expanded sectional view of a concrete placement apparatus part (at the time of a blocking valve opening). It is the III-III sectional view taken on the line of FIG. It is a detailed enlarged sectional view of a blocking valve. It is an expanded sectional view of the concrete placement apparatus part at the time of a closing valve closing. FIG. 6 is a cross-sectional view taken along line VI-VI in FIG. 5. It is principal part explanatory drawing of the conventional concrete placement apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Excavator main body 12 Front trunk 13 Rear trunk 14 Connecting shaft 15 Half-fold jack 16 Rotating ring 17 Connecting beam 18 Cutter head 19 Cutter pork 20 Outer ring 21 Fish tail cutter 22 Cutter bit 23a Copy cutter 23b Rescue bit 24 Ring gear 25 Cutter Rotating motor 26 Drive gear 27 Bulk head 28 Chamber 29 Fixed stirring rod 30 Rotating stirring rod 33 Screw conveyor 34 Ring gutter 35 Shield jack 36 Spreader 38 Rotating ring 39 Inner formwork assembly device 40 Support column 41 Mounting base 42 Shape holding device 46 Wife Formwork 47 Wife formwork jack 48 Seal member 49 Brush seal 50 Concrete placement pipe 50a Straight pipe section 50b Branch pipe section 51 Concrete placement pipe 60 Blocking valve device 61 Connecting pipe 6 Closing-cleaning of the jack 63 rod-like piston 64 around rod 65 first collar 66 volt 66a retainer plate 67 first packing 68 first pipe (spacer)
69 Second collar 70 Second packing 71 Second pipe (spacer)
72 Nut 73 Elbow for draining washing water 74 Pressure gauge 75 Support

Claims (4)

An inner mold that covers the inner wall surface of the tunnel at a predetermined distance from the inner wall surface of the tunnel and a skin plate that forms an outer shell of the excavator are disposed between the inner mold frame and the tunnel. With a wife formwork that forms a concrete placement space with the inner wall surface of
Insert and fix the end of the straight pipe part in the concrete casting pipe to the end formwork,
While detachably connecting the concrete placement pipe leading to the concrete supply source to the branch pipe part branched from the base end side of the straight pipe part, a blocking valve device is connected to the base end of the straight pipe part,
The closing valve device has a jack and a rod-like piston attached to the rod tip of the jack,
When the jack contracts, the branch pipe portion of the concrete placing pipe communicates with the straight pipe portion by retreating the rod-shaped piston, while when the jack extends, the branch pipe portion and the straight pipe portion are moved by the advance of the rod-shaped piston. The concrete placement device is characterized in that the continuous concrete is blocked and the residual concrete in the straight pipe portion is pushed out into the concrete placement space.   The rod-like piston is provided with a first packing detachably at its tip, and a second packing is detachably attached to the outer periphery of the intermediate piston. When the jack is extended, the second packing portion is directly connected to the branch pipe portion. The concrete placement device according to claim 1, wherein communication with the pipe portion is blocked.   3. The concrete placement device according to claim 1, wherein the blocking valve device is connected to the proximal end of the straight pipe portion via a connecting pipe. A tubular excavator body, a propulsion jack that advances the excavator body, a cutter head that is rotatably supported at the front of the excavator body, and a drive unit that rotates the cutter head. Tunnel excavator
A tunnel excavator comprising the concrete placing device according to any one of claims 1 to 3.

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