JP2015203245A - Tunnel excavator and tunnel excavation method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fastening tunnel excavator capable of releasing the excavator in a short time when caught by a collapsed natural ground or excavated sediment, without having an operator come out of the excavator.SOLUTION: A trunk member 2 of a tunnel excavator 1 has an inner barrel 2A and an outer barrel 2B that is positioned concentrically with the inner barrel leaving a prescribed gap. At least a bottom plate part 42a of the outer barrel is held in a fixed state to the inner barrel, and a pair of variable connecting part 60 is installed in the right and left at a middle stage section of the outer barrel, the variable connecting part parting the outer barrel in a way that may vary the diameter of the outer barrel. Assuming the part of the outer barrel above the variable connecting part as an upper outer barrel 41 and the part of the outer barrel below the variable connecting part as a lower outer barrel 42, the lower outer barrel has a bottom plate part held in a fixed state to the inner barrel, and the pair of variable connecting parts have a pair of first driving means that connect the upper outer barrel to the inner barrel and may be driven to reduce the diameter of the outer barrel.

Description

  The present invention relates to a tunnel excavator, and in particular, when a tunnel excavator starts to be restrained by a natural ground due to collapse of a natural ground or tightening by excavated earth and sand (hereinafter referred to as collapse of natural ground), the restriction can be released. Therefore, the present invention relates to a tunnel excavator in which the diameter of the body member can be reduced.

  In a tunnel excavator that excavates a large-diameter, long-distance, large-depth tunnel, when the fault zone is encountered, the fuselage may be restrained by the natural ground due to the collapse of the natural ground, making it impossible to excavate. Therefore, in order to release the collapse of the upper part of the natural ground that restrains the trunk, as a measure to prevent the natural ground from collapsing under an environment where large water pressure or earth pressure acts, , I was doing the work of expanding and cutting the restraint by human power.

  Patent Document 1 discloses a variable section shield shield machine capable of gradually increasing and decreasing the diameter of the excavation cross section evenly in all directions in order to expand and contract the excavation diameter of the shield mine as necessary.

JP-A-8-93381

  Especially when it is constrained to a fault zone at a deep depth, even if ground improvement material is injected, it is unlikely that water pressure and earth pressure can be completely sealed, and it is necessary for the operator to go out of the fuselage and perform the expansion work. Is always dangerous. Moreover, in a large-diameter tunnel excavator, it is assumed that the amount of work for cutting and expanding is large and the work period is long.

  This invention is made | formed in view of such a condition, and it aims at providing the tunnel excavator which can cancel | release the restraint from a natural ground in a short time without relying on human power.

  The tunnel excavator according to claim 1 is a tunnel excavator having a cutter head and a trunk member, wherein the trunk member includes an inner trunk and an outer trunk arranged concentrically with a predetermined gap with respect to the inner trunk. And a pair of left and right variable connecting portions that are divided so that the outer cylinder can be reduced in diameter are provided at the middle stage of the outer cylinder, and the outer cylinder portion above the variable connecting portion is the upper portion of the outer cylinder, and the variable connecting portion A lower outer body portion is an outer body lower part, and the outer body lower part has a bottom plate portion held in a fixed state with respect to the inner body, and the pair of left and right variable connecting parts are the outer body part. It is characterized by comprising a pair of left and right first drive means for connecting the upper part to the inner cylinder so as to be capable of reducing diameter driving.

  A tunnel excavator according to a second aspect is the invention according to the first aspect, wherein the lower part of the outer trunk has a pair of left and right lower side plates rotatably connected to both ends of the bottom plate portion, and the pair of left and right is variable. The connecting portion is characterized in that it includes a pair of left and right second driving means for connecting the pair of left and right lower side plates to the inner body so as to be capable of reducing diameter driving.

  The tunnel excavator according to claim 3 is the invention according to claim 1 or 2, wherein a plurality of members for urging the top plate portion in the diameter increasing direction when the diameter is reduced between the top plate portion and the inner shell at the upper part of the outer trunk. The urging means is provided.

  A tunnel excavator according to a fourth aspect is the invention according to the second aspect, wherein the upper portion of the outer body includes a top plate portion and a pair of left and right upper side plates rotatably connected to both left and right ends of the top plate portion, A third driving means is provided to support the top plate portion so that the diameter of the top plate portion can be reduced.

  The tunnel excavator according to claim 5 is the invention according to claim 1, wherein a first intrusion prevention mechanism for preventing intrusion of earth and sand between the inner trunk and the outer trunk is provided at the front end of the inner trunk and the front end of the outer trunk, A second intrusion prevention mechanism for preventing intrusion of earth and sand between the inner cylinder and the outer cylinder is provided at the rear end of the inner cylinder and the rear end of the outer cylinder.

  The tunnel excavator of claim 6 is the invention of claim 5, wherein a pair of left and right third intrusion prevention mechanisms for preventing intrusion of earth and sand between the inner cylinder and the outer cylinder from the pair of left and right variable connecting portions are provided. It is characterized by.

  The tunnel excavator of claim 7 is characterized in that, in the invention of claim 1 or 2, at least one load detecting means for detecting a load acting from a natural ground is provided on a top plate portion of the upper outer trunk.

  The tunnel excavator according to claim 8 is the invention according to claim 1 or 2, wherein the cutter head is provided with a plurality of over cutters for enlarging the excavation diameter, and is provided at the lower end portion of the inner cylinder and the outer cylinder near the front end. A movable sled capable of projecting to the outside of the outer body and an advancing / retreating drive means for advancing / retreating the movable sled are provided.

  The tunnel excavation method according to claim 9 is a tunnel excavation method in which a tunnel is excavated by a tunnel excavator having a cutter head and a trunk member. In the tunnel excavation method, a diameter reducing means capable of reducing the diameter of the trunk member is provided in the trunk member in advance. A plurality of overcutters are provided in the cutter head, and the excavation is expanded by the plurality of overcutters when a compressive load by which the natural ground compresses the trunk member exceeds a predetermined first reference value. A first step of performing tunnel excavation in a cross section, and a tunnel in a state where the diameter of the trunk member is reduced by the diameter reducing means when the compressive load exceeds a second reference value larger than a predetermined first reference value. And a second step of performing excavation.

  According to invention of Claim 1, a trunk | drum member has an inner cylinder and the outer cylinder arrange | positioned concentrically at predetermined intervals to this inner cylinder, and diameter reduction of an outer cylinder is possible in the middle step part of the said outer cylinder. A pair of left and right variable connecting portions are provided, the outer body lower portion has a bottom plate portion that is fixedly held with respect to the inner body, and the pair of left and right variable connecting portions includes an outer upper portion inside. Since the pair of left and right first driving means connected to the body so as to be able to reduce the diameter is provided, the following effects can be obtained.

  When the tunnel excavator is constrained from the natural ground, the outer trunk upper part is driven inward (downward) by a pair of left and right first drive means to reduce the diameter of the outer trunk upper part, Can be released. Therefore, the operator can efficiently and safely release the restraint in a short time without going out of the tunnel excavator.

  Since the lower part of the outer cylinder has a bottom plate portion that is held in a fixed state with respect to the inner cylinder, the height position of the axial center of the tunnel excavator can be kept constant even when the diameter of the upper part of the outer cylinder is reduced. Sound excavation is possible without the risk of the tunnel excavator sinking downward.

  According to the second aspect of the present invention, the pair of left and right variable drive units include a pair of left and right second drive means for connecting the lower part of the outer body to the inner body so as to be able to reduce the diameter of the outer body. By reducing the diameter of the lower part of the outer trunk in conjunction with the reduced diameter, the earth pressure acting on the part of the outer trunk excluding the bottom plate can be reduced, and the release of restraint from the natural ground can be promoted.

  According to the invention of claim 3, since the plurality of urging means for urging the top plate portion in the diameter increasing direction when the diameter is reduced are provided between the top plate portion of the upper portion of the outer cylinder and the inner cylinder. When expanding the diameter from the reduced diameter state, the top plate portion is urged toward the diameter expansion side by a plurality of urging means, and the diameter expansion of the outer body can be promoted.

  According to the invention of claim 4, the upper part of the outer cylinder includes a top plate part and a pair of left and right upper side plates rotatably connected to the left and right ends of the top plate part. Since the third driving means for supporting the top plate portion so as to be able to reduce the diameter is provided between the body and the body, a finer diameter reducing operation can be performed.

  According to the invention of claim 5, the first intrusion prevention mechanism for preventing intrusion of earth and sand between the inner cylinder and the outer cylinder is provided at the front end of the inner cylinder and the front end of the outer cylinder, and the rear end of the inner cylinder and the outer cylinder Since the second intrusion prevention mechanism for preventing the invasion of earth and sand between the inner cylinder and the outer cylinder is provided at the rear end portion, it is possible to prevent the earth and sand from entering between the inner cylinder and the outer cylinder.

  According to the sixth aspect of the present invention, since the pair of left and right third intrusion prevention mechanisms for preventing the intrusion of earth and sand between the inner cylinder and the outer cylinder are provided from the pair of left and right variable connecting portions, the inner cylinder and the outer It can prevent intrusion of earth and sand between the torso.

  According to the seventh aspect of the present invention, since at least one load detecting means for detecting the load acting from the natural ground is provided on the top plate portion at the upper part of the outer trunk, it becomes possible to detect a sign of the collapse of the natural ground, It becomes possible to detect the restraint accompanying the collapse or the like.

  According to the eighth aspect of the present invention, the cutter head is provided with a plurality of overcutters for enlarging the excavating diameter, and the movable sled that can protrude to the outside of the outer cylinder at the lower end portions of the inner cylinder and the front cylinder in the vicinity of the front end. And an advancing / retreating drive means for driving the movable sled back and forth, so that when a plurality of overcutters are operated to expand the excavation diameter, the movable sled is projected by the advancing / retreating drive means, so that the axis of the tunnel excavator The tunnel excavation can be continued in a state where the height position is kept constant.

  According to the tunnel excavation method of claim 9, in the first step, the excavation expanded in diameter by the plurality of overcutters when the compression load by which the natural ground compresses the trunk member exceeds a predetermined first reference value. Tunnel excavation is performed in a cross section, and in the second step, when the compressive load exceeds a predetermined second reference value, tunnel excavation is performed in a state where the diameter of the trunk member is reduced by the diameter reducing means. The first step can suppress the tunnel excavator from being restrained by the natural ground, and the second step can release the restraint of the tunnel excavator restrained by the natural ground.

It is a longitudinal cross-sectional view of the tunnel excavator (normal state) which concerns on Example 1 of this invention. It is a front view of a cutter head. It is the III-III sectional view taken on the line of FIG. It is the IV-IV sectional view taken on the line of FIG. It is a longitudinal cross-sectional view of a tunnel excavator (reduced diameter state). There was no drawing. FIG. 6 is a cross-sectional view taken along line VI-VI in FIG. 5. It is the VII-VII sectional view taken on the line of FIG. It is an enlarged view of the A section of FIG. It is an enlarged view of the B section of FIG. It is an enlarged view of the D section of FIG. It is an enlarged view of the C section of FIG. It is an enlarged view of the E section of FIG. It is explanatory drawing which shows the structure of an outer trunk. It is a longitudinal cross-sectional view of the tunnel excavator (normal state) which concerns on Example 2. FIG. It is the XV-XV sectional view taken on the line of FIG. It is the XVI-XVI sectional view taken on the line of FIG. It is a longitudinal cross-sectional view of a tunnel excavator (reduced diameter state). It is the XVIII-XVIII sectional view taken on the line of FIG. It is the XIX-XIX sectional view taken on the line of FIG.

EMBODIMENT OF THE INVENTION The form for implementing this invention is demonstrated based on an Example.
In addition, front and rear, right and left in the state facing the tunnel excavation direction will be described as front and rear and right and left.
Further, in the following examples, “expanded diameter” that means an increase in diameter and “reduced diameter” that means a decrease in diameter are “amplified diameter” that is asymmetric in the vertical direction with respect to the axis of the tunnel excavator, It means “reduced diameter”.

  In the tunnel excavator 1 according to the present embodiment, the body member 2 is composed of an inner body 2A and an outer body 2B arranged concentrically with a predetermined gap with respect to the inner body 2A. The tunnel excavator is a large-diameter tunnel excavator that has a diameter, and the internal structure, equipment, and equipment installed in the tunnel excavator 1 are almost the same as those of a normal tunnel excavator, and will be described briefly.

  As shown in FIGS. 1 to 4, the tunnel excavator 1 includes, as basic components, a trunk member 2, a cutter head 3, a bulkhead structure 4, a cutter driving mechanism 5, a plurality of thrust jacks 6, and a plurality of shield jacks 7. Two rotation control jacks 8, a movable sled 9 and a plurality of front grippers 10, a plurality of main grippers 11, a swiveling ring 12 and an erector 13, a work deck 14, a segment shape holding device 15, a soil removal facility 16, etc. Yes.

Next, the trunk member 2 will be described.
The inner cylinder 2A includes a front inner cylinder 20a, an intermediate inner cylinder 20b, and a rear inner cylinder 20c. The cylindrical front inner cylinder 20a is externally fitted to the cylindrical intermediate inner cylinder 20b so as to be slidable for a predetermined stroke. Yes.
The outer cylinder 2B is disposed concentrically with a predetermined gap (for example, 400 mm) with respect to the inner cylinder 2A outside the inner cylinder 2A. The outer body 2 </ b> B has a front outer body 40 and a rear outer body 50, and a rear end side portion of the front outer body 40 is externally fitted to the front part of the rear outer body 50 so as to be slidable for a predetermined stroke. Yes. The details of the outer body 2B will be described later.

Next, the cutter head 3, the partition structure 4, and the cutter drive mechanism 5 will be described.
As shown in FIGS. 1 and 2, the cutter head 3 includes a plurality of (e.g., eight) cutter frames 21 extending in the radial direction, a plurality of outer peripheral frames 22 to which outer end portions of the cutter frames 21 are fixed, and a plurality of cutter frames 21. A plurality of roller cutters 23 respectively attached to the cutter frame 21, a plurality of (e.g., 8 sets) overcutters 24 respectively provided on the outer peripheral end portions of the plurality of cutter frames 21 in a forward and outward inclined manner, A plurality of (for example, eight) fan-shaped face plates 25 are provided. A gap 26 for introducing earth and sand is formed between one side of the face plate 25 and the cutter frame 21, and rear end portions of the plurality of cutter frames 21 are fixed to the cutter drum 27.

  The overcutter 24 is configured to be switchable between an advanced position and a retracted position by a hydraulic cylinder. When the sign of the collapse of the natural ground appears and the compression load for compressing the trunk member 2 starts to increase, the diameter of the excavation cross section can be increased by switching the over cutter 24 to the protruding position.

  A cutter chamber 17 is formed on the rear side of the cutter head 3, and a rear end of the cutter chamber 17 is partitioned by a partition wall structure 4. The partition wall structure 4 includes a disk member 4a at the center side portion, an annular plate member 4b at the outer peripheral side portion, and a device mounting frame 4c on the rear surface side of the disk member 4a and the annular plate member 4b. The working frame 4c is fixed to the front inner cylinder 20a, the disc member 4a, and the annular plate member 4b. The cutter drum 27 is rotatably mounted between the disc member 4a and the annular plate member 4b via a seal member or a bearing.

  Next, with respect to the cutter driving mechanism 5, as shown in FIGS. 1 and 3, an internal ring gear 5a is fixed to the cutter drum 27, and a pinion gear 5c fixed to the output shafts of a plurality of cutter driving motors 5b is internally connected. The internal ring gear 5a meshes with the tooth ring gear 5a, and is rotatably supported by the device mounting frame 4c via a slewing bearing 5d. In this way, the cutter drum 27 and the cutter head 3 can be rotationally driven by the plurality of cutter drive motors 5b via the internal ring gear 5a. The plurality of cutter drive motors 5b are attached to the device attachment frame 4c.

Next, the thrust jack 6 will be described.
As shown in FIGS. 1 and 3, an annular member 28 having a closed cross section is fixed to the rear surface of the equipment mounting frame 4c, and an annular web 29 having a large front and rear width is fixed to the inner surface of the rear inner barrel 20c. A plurality of (for example, 14) thrust jacks 6 for generating a propulsive force are attached in the front-rear direction near the inner periphery of the annular web 29 at appropriate intervals in the circumferential direction.

  The jack body of the thrust jack 6 is pin-coupled to the bracket of the annular member 28, and the piston rod of each thrust jack 6 is pin-coupled to the bracket on the inner surface of the annular web 29. By driving the plurality of thrust jacks 6 to extend, the excavator front 1A including the front inner cylinder 20a, the front outer cylinder 40, the partition wall structure 4, the cutter driving mechanism 5, the cutter head 3, and the like is transferred to the excavator rear 1B. Tunnel excavation is performed while moving forward relatively. In addition, since the pin coupling part which connects the front and rear ends of the thrust jack 6 has a slight backlash, the direction of excavation can be changed by a small angle in the left-right direction or the up-down direction.

Next, the shield jack 7 will be described.
As shown in FIGS. 1 and 4, a plurality of (for example, 32) shield jacks 7 are arranged in the front-rear direction at appropriate circumferential intervals, and these shield jacks 7 are attached to the annular web 29 in a penetrating manner. It is fixed. The piston rod of each shield jack 7 can extend backward from the jack body.

  The connecting piece 7a extending from the front end of the jack body of each shield jack 7 is pin-coupled to the connecting piece 7b of the annular frame 30 fixed to the inner surface of the intermediate inner cylinder 20b by a pin in the radial direction. Since the plurality of pin coupling portions for pin coupling the jack bodies of the plurality of shield jacks 7 have slight backlash, the excavation direction can be changed by a small angle in the left-right direction or the vertical direction.

  A spreader 7c is connected to the ends of the two piston rods of the two shield jacks 7 in one set. The plurality of spreaders 7c are brought into contact with the front end surface of the segment S which has been covered from the front, and the piston rods of the plurality of shield jacks 7 are driven to extend, whereby the entire tunnel excavator 1 corresponds to the segment 1 ring. It can be moved forward by a predetermined stroke.

  Next, the rotation control jack 8 will be described. As shown in FIGS. 1 and 3, the rotation control jack 8 controls the rolling angle so that the excavator rear part 1B does not rotate relative to the excavator front part 1A. A pair of left and right rotation control jacks 8 are disposed on the left and right sides of the space between the annular frame 30 and the annular web 29, and the base end portion of the jack body of the rotation control jack 8 is a bracket 8 a of the annular frame 30. The tip of the piston rod is pin-coupled to a bracket 8b fixed to the annular web 29.

  Next, the movable sled 9 and the front gripper 10 will be described. As shown in FIGS. 1 and 3, the movable sled 9 and the four sets of front grippers 10 are mounted on the equipment mounting frame 4 c at a portion corresponding to the front end portion of the body member 2. At the bottom of the device mounting frame 4c, a movable sled 9 having a rectangular shape in plan view that is elongated in the circumferential direction is provided so as to protrude in the vertical direction, and the movable sled 9 is driven forward and backward by two sets of hydraulic cylinders incorporated in the movable sled 9. It is configured to be possible.

  When the overcutter 24 of the cutter head 3 protrudes and the diameter of the excavation cross section is enlarged, the movable sled 9 is switched to the protruding position by two sets of hydraulic cylinders, and the tunnel excavator 1 is prevented from moving downward. The position of the shaft center of the excavator 1 is maintained constant. In view of performing tunnel excavation in a state where the movable sled 9 is switched to the protruding position, the front portion of the lower end surface of the movable sled 9 is formed as a tapered surface 9a that is inclined forwardly upward.

  In the four sets of front grippers 10, two sets on the lower side and two sets on the upper side are arranged at, for example, a circumferentially equally divided position. The front gripper 10 can be switched between a protruding position and a retracted position by a built-in hydraulic jack. A tapered surface 10 a similar to the movable sled 9 is formed on the front end surface of the front gripper 10. These front grippers 10 are held in a protruding position with low pressure hydraulic pressure during tunnel excavation, and prevent vibration of the tunnel excavator 1. Note that the number of front grippers 10 is not limited to four.

Next, the main gripper 11 will be described.
For example, the four main grippers 11 are arranged at appropriate intervals in the circumferential direction at the upper portion of the annular web 29 at the front-rear position corresponding to the rear portion of the annular web 29. The main gripper 11 can be switched between a protruding position and a retracted position by a hydraulic jack. Tunnel digging while generating thrust with a plurality of thrust jacks 6 while maintaining the piston rods of all shield jacks 7 in a contracted state with the reaction force of the tunnel digging propulsion force taken by these main grippers 11 In parallel with the tunnel excavation, the lining of the segment can be performed by the elector 13.

  Each time a plurality of thrust jacks 6 are excavated for one stroke, the excavation is interrupted, and the operation of contracting the piston rods of the plurality of thrust jacks 6 and the operation of extending the piston rods of the plurality of shield jacks 7 are synchronized. By performing, the tunnel excavator 1 is moved forward by one stroke, and then the next one stroke of tunnel excavation and segment assembly are repeated.

Next, the turning ring 12 and the erector 13 will be described.
As shown in FIGS. 1 and 4, the upper and lower ends of a pair of left and right vertical columns 31 are connected to an annular web 29, and a pair of left and right brackets 31 a are fixed to the middle part of the pair of left and right columns 31. The front end portions of the pair of left and right guide members 32 having a circular cross section are fixed to the pair of brackets 31a, respectively, and the pair of guide members 32 extend horizontally rearward.

  A pair of cylindrical members 32a are provided on the pair of guide members 32 so as to be freely movable back and forth. A support frame 33 orthogonal to the tunnel axis is fixed to the cylindrical members 32a. The swivel ring 12 is attached to the front surface of the outer periphery of the swivel ring via a swivel bearing 34, and the connecting member 35 fixed to the lower end of the swivel ring 12 is equipped with the erector 13. A pair of left and right guide members 35a extending horizontally are fixed to the connecting member 35, and the guide member 35a is equipped with the erector 13 so as to be movable in the front-rear direction.

  A plurality of turning drive devices 37 (not shown) for driving the turning ring 12 to turn are provided. By driving the turning drive device 37, the erector 13 is driven to turn together with the turning ring 12. A pair of left and right hydraulic cylinders 36 for driving the erector 13 in the front-rear direction together with the turning ring 12 are also provided.

  The work deck 14 is connected to the left and right support columns 31 via members not shown. The work deck 14 is also equipped with a segment S assembly movable basket 14a. A shape holding device 15 for holding the shape of the segment covered on the inner surface of the tunnel is disposed on the rear side of the erector 13. A belt conveyor 16 serving as a soil removal facility for carrying out excavated earth and rocks and rocks is disposed in an upwardly inclined shape, and a belt conveyor gate 16a slidable back and forth is also provided at the front end.

Next, the outer trunk 2B of the trunk member 2 will be described.
As shown in FIGS. 1, 3, and 13, the outer cylinder 2 </ b> B includes a front outer cylinder 40 and a rear outer cylinder 50. The front outer body 40 is divided into a front outer body upper part 41 and a front outer body lower part 42. The front outer trunk upper portion 41 is divided into a front outer trunk top plate portion 41a and a pair of front outer trunk upper side plates 41b and 41c on the left and right sides thereof. The front outer trunk lower part 42 is divided into a front outer trunk bottom plate part 42a and a pair of front outer trunk lower side plates 42b and 42c on the left and right sides thereof.

  In the following description, the front outer trunk top plate portion 41a is described as a top plate portion 41a, the left and right front outer cylinder upper side plates 41b and 41c are described as upper side plates 41b and 41c, and the front outer trunk bottom plate portion 42a. Is described as a bottom plate portion 42a, and left and right front outer lower portion side plates 42b and 42c are described as lower side plates 42b and 42c.

  As shown in FIGS. 1, 4, and 13, the rear outer cylinder 50 is divided into a rear outer trunk upper part 51 and a rear outer trunk lower part 52, and the rear outer trunk upper part 51 is a rear outer trunk top plate part. 51a and a pair of rear outer trunk upper side plates 51b and 51c on both the left and right sides thereof. The rear outer trunk lower part 52 is divided into a rear outer trunk bottom plate part 52a and a pair of rear outer trunk lower side plates 52b and 52c on the left and right sides thereof.

  In the following description, the rear outer trunk top plate portion 51a is the top plate portion 51a, the left and right rear outer trunk upper side plates 51b and 51c are the upper side plates 51b and 51c, the rear outer trunk bottom plate portion 52a is the bottom plate portion 52a, and the left and right rear outer portions. The trunk lower side plates 52b and 52c are referred to as lower side plates 52b and 52c, respectively.

  As shown in FIG. 3, the bottom plate portion 42 a is fixed to the front inner body 20 a by a pair of left and right connecting ribs 43 that are arranged in the front-rear direction on both sides in the circumferential direction of the movable sled 9. As shown in FIGS. 1 and 4, a plurality of connecting ribs 45 for fixing the bottom plate portion 52 a to the rear inner cylinder 20 c are provided.

As shown in FIGS. 3, 9, and 10, a pair of left and right front outer body variable connecting portions 60 are provided in the middle of the front outer body 40 so that the front outer body 40 can be reduced in diameter. It has been. Since the left and right front outer trunk variable connecting portions 60 are symmetrical, the right front outer variable joint 60 will be described.
The right front outer cylinder variable connecting portion 60 has a divided seal structure 61 in which the upper side plate 41c and the lower side plate 42c are divided so that the diameter can be reduced, and the front outer cylinder upper portion 41 can be driven to be reduced in diameter to the front inner cylinder 20a. A plurality of (for example, six) front first hydraulic cylinders 62 and a plurality of (for example, six) front second hydraulic cylinders that connect the front outer cylinder lower portion 42 to the front inner cylinder 20a so as to be able to be reduced in diameter. 63. The first and second hydraulic cylinders 62 and 63 are arranged in a substantially vertical posture and in a crossing manner. In addition, a large driving force can be generated by supplying high pressure oil pressure to the first and second hydraulic cylinders 62 and 63.

  The split seal structure 61 will be described. Between the lower end of the upper side plate 41c and the upper end portion of the lower side plate 42c, a slit 61a having a predetermined width (for example, 300 to 400 mm) in the front-rear direction is formed over the entire length. A partially cylindrical sealing plate 61b that covers the slit 61a from the inside is provided, the lower end side portion of the sealing plate 61b is welded to the inner surface of the lower side plate 42c, and the upper end side portion of the sealing plate 61b is the inner surface of the upper side plate 41c. It seals so that earth and sand may not invade or adjoin to.

  The six sets of front first hydraulic cylinders 62 are disposed at, for example, front and rear direction positions that divide the front inner body 2a into front and rear equal to five. The front second hydraulic cylinder 63 is disposed at the same longitudinal position as the front first hydraulic cylinder 62. However, the number and positions of the front first and second hydraulic cylinders 62 and 63 are not limited to the above.

  For example, a rectangular inspection window 64 for inspecting and repairing the front first and second hydraulic cylinders 62 and 63 of each set is provided, and a window frame 65 of the inspection window 64 is fixed to the front inner cylinder 20a. At the time of excavation, the inspection window 64 is closed by a steel lid plate 64a, and at the time of inspection, inspection can be performed by loosening a plurality of bolts and removing the lid plate 64a. The base end portion of the cylinder body of the front first hydraulic cylinder 62 is pin-coupled to a lower end portion of the window frame 65 by a pin coupling portion 62a having a front and rear axis, and the piston rod ( The tip end portion (usually in an extended state) is pin-coupled by a pin coupling portion 62b having an axial center in the front-rear direction near the lower end of the upper side plate 41c.

  The base end portion of the cylinder body of the front second hydraulic cylinder 63 is pin-coupled to the upper end portion of the window frame 65 by a pin coupling portion 63a having a front and rear axial center, and the piston rod ( The tip end portion (usually in a stretched state) is pin-coupled by a pin coupling portion 63b having a front-rear axial center in the vicinity of the upper end of the lower side plate 42c.

  Since there is the divided seal structure 61, the front outer cylinder upper part 41 including the left and right upper side plates 41b and 41c is made into the front inner cylinder 20a by contracting the piston rods of the plurality of front first hydraulic cylinders 62 on the left and right sides. On the other hand, the diameter can be reduced by pulling downward. Further, by contracting the piston rods of the plurality of front second hydraulic cylinders 63 on both the left and right sides, the front outer cylinder lower part 42 including the lower side plates 42b and 42c is attracted upward with respect to the front inner cylinder 20a to reduce the diameter. Can be made.

  As shown in FIGS. 4, 11, and 12, a pair of left and right rear outer body variable connecting portions 70 are provided in the middle portion of the rear outer body 50 so that the rear outer body 50 is divided so that the diameter of the rear outer body 50 can be reduced. . Since the left and right rear outer trunk variable coupling portions 70 are symmetrical, the right rear outer trunk variable coupling portion 70 will be described. The right rear outer cylinder variable connecting portion 70 connects the upper side plate 51c and the lower side plate 52c so that the upper side plate 51c and the lower side plate 52c can be reduced in diameter, and the rear outer cylinder upper portion 51 connected to the rear inner cylinder 20c so as to be reduced in diameter. A plurality of (for example, seven) rear first hydraulic cylinders 72 and a plurality of (for example, seven) rear second hydraulic cylinders 73 that connect the rear outer cylinder lower portion 52 to the rear inner cylinder 20c so as to be capable of reducing diameter driving. The first and second hydraulic cylinders 72 and 73 are arranged in a substantially vertical posture and intersecting with each other. In addition, a large driving force can be generated by supplying a high hydraulic pressure to the first and second hydraulic cylinders 72 and 73. Note that the first hydraulic cylinder 72 and the second hydraulic cylinder 73 do not necessarily have to be arranged in a substantially vertical posture and in an intersecting manner.

  The split seal structure 71 will be described. Between the lower end of the upper side plate 51c and the upper end portion of the lower side plate 52c, a slit 71a in the front-rear direction having a predetermined width (for example, 300 to 400 mm) is formed over the entire length. A partial cylindrical blocking plate 71b that closes the slit 71a from the inside is provided, a lower end side portion of the sealing plate 71b is welded to an inner surface of the lower side plate 52c, and an upper end side portion of the blocking plate 71b is an inner surface of the upper side plate 51c. It seals so that earth and sand may not invade or adjoin to.

  The seven sets of the rear first and second hydraulic cylinders 72 and 73 are arranged at, for example, front and rear direction positions that divide the rear outer cylinder 50 into six equal parts, but this arrangement position is an example and is limited to this. It is not a thing. For example, a rectangular inspection window 74 for inspecting and repairing the rear first and second hydraulic cylinders 72 and 73 is provided, and a window frame 75 of the inspection window 74 is fixed to the rear inner cylinder 20c, and is inspected during normal excavation. The window 74 is closed with a steel window plate 74a, and can be inspected by loosening a plurality of bolts and removing the window plate 74a during inspection.

  A base end portion of the cylinder body of the rear first hydraulic cylinder 72 is pin-coupled to a lower end portion of the window frame 75 by a pin coupling portion 72a having a front and rear axial center, and a piston rod (usually, the rear first hydraulic cylinder 72) The distal end portion in the extended state is pin-coupled by a pin coupling portion 72b having a front and rear axial center in the vicinity of the lower end of the upper side plate 51c.

  The base end portion of the cylinder body of the rear second hydraulic cylinder 73 is pin-coupled to the upper end portion of the window frame 75 by a pin coupling portion 73a having an axial center in the front-rear direction, and the piston rod (usually the rear second hydraulic cylinder 73) The distal end portion in the extended state is pin-coupled by a pin coupling portion 73b having an axial center in the front-rear direction in the vicinity of the upper end of the lower side plate 52c.

  Since there is the divided seal structure 71, the piston rods of the plurality of rear first hydraulic cylinders 72 on both the left and right sides are contracted, so that the left and right upper side plates 51b and 51c are connected to the inner cylinder 2A centering on the connecting portion with the top plate portion 51a. Can be rotated in the direction. That is, the rear outer cylinder upper part 51 can be pulled down with respect to the rear inner cylinder 20c to reduce the diameter. Further, by contracting the piston rods of the plurality of rear second hydraulic cylinders 73 on both the left and right sides, the left and right lower side plates 52b and 52c are rotated in the direction of the inner cylinder 2A around the connecting portion with the bottom plate portion 52a. The diameter can be reduced. That is, it is possible to reduce the diameter by pulling the portion of the rear outer body lower part 52 excluding the bottom plate part 52a upward with respect to the rear inner body 20c.

Here, the left front outer trunk variable connecting portion 60 and the left rear outer variable joint 70 are equivalent to the left “variable connecting portion”. The right rear outer body variable connecting portion 70 corresponds to the right “variable connecting portion”.
The plurality of left front first hydraulic cylinders 62 and the left plurality of rear first hydraulic cylinders 72 correspond to “left first driving means”, and the right plurality of front first hydraulic cylinders 62 and the right side first hydraulic cylinders 62 The plurality of rear first hydraulic cylinders 72 correspond to “right first drive means”, and the left plurality of front second hydraulic cylinders 63 and the left plurality of rear second hydraulic cylinders 73 are “left side first drive means”. The right plurality of front second hydraulic cylinders 63 and the right plurality of rear second hydraulic cylinders 73 correspond to “right second drive means”.

Next, the hinge coupling portions 46b and 46c will be described.
As shown in FIG. 3, for example, six sets of hinge coupling portions 46 b (having axial centers in the front-rear direction) that hinge-connect the left end portion of the top plate portion 41 a and the upper end portion of the upper side plate 41 b are provided. The six sets of hinge coupling portions 46b are provided at the front-rear direction positions corresponding to the front first and second hydraulic cylinders 62, 63, for example. In addition, you may provide more hinge coupling parts 46b than six sets.

The hinge coupling portion 46b is fixed to the inner surface of the upper side plate 41b and extends to the inner surface side of the top plate portion 41a, a pivot piece 46n fixed to the inner surface of the top plate portion 41a, and a tip portion of the hinge arm 46m. And a pin member 46p that is pin-coupled to the pivot piece 46n.
For example, six sets of hinge coupling portions 46c that hinge-connect the right end portion of the top plate portion 41a and the upper end portion of the upper side plate 41c are also provided. These right hinge coupling portions 46c are symmetrical to the left hinge coupling portion 46b. In addition, you may provide more hinge coupling | bond parts 46c than six sets.

Next, the hinge coupling portions 47b and 47c will be described.
As shown in FIG. 3, for example, six sets of hinge coupling portions 47 b (having axial centers in the front-rear direction) are provided to hinge-couple the left end portion of the bottom plate portion 42 a and the lower end portion of the lower side plate 42 b. The six sets of hinge coupling portions 47b are provided, for example, at positions in the front-rear direction corresponding to the six sets of hinge coupling portions 46b. Since the hinge coupling portion 47b is the same as the hinge coupling portion 46b, description thereof is omitted.

  For example, six sets of hinge coupling portions 47c that hinge-connect the right end portion of the bottom plate portion 42a and the lower end portion of the lower side plate 42c are also provided. The hinge coupling portion 47c is bilaterally symmetric with the hinge coupling portion 47b, and a description thereof will be omitted.

Next, the hinge coupling portions 48b and 48c will be described.
As shown in FIG. 4, there are provided, for example, seven sets of hinge coupling portions 48b (having axial centers in the front-rear direction) that hinge-join the left end portion of the top plate portion 51a and the upper end portion of the upper side plate 51b. Seven sets of hinge coupling portions 48b are provided at positions in the front-rear direction corresponding to the seven sets of rear first and second hydraulic cylinders 72, 73. Since the hinge coupling portion 48b is the same as the hinge coupling portion 46b, description thereof is omitted. For example, seven sets of hinge coupling portions 48c (having an axial center in the front-rear direction) that hinge-connect the right end portion of the top plate portion 51a and the upper end portion of the upper side plate 51c are provided. The hinge coupling portion 48c is symmetrical with the hinge coupling portion 48b.

  Next, the top hydraulic cylinders 81b and 81c for expanding the diameter of the top plate portion 41a will be described. As shown in FIGS. 1 and 3, for example, two top hydraulic cylinders 81b and 81c are disposed between the top plate portion 41a and the front inner cylinder 20a at a position corresponding to the rear portion of the device mounting frame 4c. . The two top hydraulic cylinders 81b and 81c are disposed at portions corresponding to the left and right portions of the top plate portion 41a.

  The cylinder bodies of the top hydraulic cylinders 81b and 81c are disposed vertically in a recess formed in the front inner cylinder 20a, and the tip of the piston rod is in contact with a seat plate fixed to the inner surface of the top plate portion 41a. When the front outer cylinder 40 is in a normal state where the diameter of the front outer cylinder 40 is not reduced, the piston rods of the top hydraulic cylinders 81b and 81c are held in an extended state, and when the front outer cylinder 40 is switched to a reduced diameter state, the top hydraulic cylinder 81b. , 81c are retracted, and when the front outer cylinder 40 is switched from the reduced diameter state to the expanded diameter state, the piston rods of the top hydraulic cylinders 81b, 81c are extended.

  Next, the four top hydraulic cylinders 82b, 82c, 83b, 83c capable of driving the top plate portion 51a in the diameter increasing direction will be described. A pair of left and right top hydraulic cylinders 82b and 82c are disposed in the vicinity of the front end of the rear outer cylinder upper portion 51 between the top plate portion 51a and the rear inner cylinder 20c in the same manner as the top hydraulic cylinders 81b and 81c. A pair of left and right top hydraulic cylinders 83b and 83c are arranged in the same manner as the top hydraulic cylinders 81b and 81c between the top plate part 51a and the rear inner cylinder 20c at the rear part of the rear outer cylinder upper part 51. The top hydraulic cylinders 81b, 81c; 82b, 82c; 83b, 83c correspond to “third drive means”.

Next, the first intrusion prevention mechanism 84 provided at the front end portions of the inner cylinder 2A and the outer cylinder 2B will be described.
As shown in FIGS. 1 and 8, an inclined plate 21a is fixed to the outer peripheral end of the cutter frame 21 of the cutter head 3, and a partial conical fixed inclined plate 18 is disposed in the vicinity of the outer surface of the plurality of inclined plates 21a. The inner peripheral end of the fixed inclined plate 18 is welded to the annular plate member 4b of the partition wall structure 4. The first intrusion prevention mechanism 84 prevents soil and sand from entering between the front end portion of the front inner cylinder 20a and the front end portion of the front outer cylinder 40.

  The first intrusion prevention mechanism 84 includes a first ring plate 84a that protrudes outward from the front end of the front inner cylinder 20a, and an outer peripheral side portion of the first ring plate 84a from the front side of the first ring plate 84a. A second ring plate 84b that is close to or slidably contacted with the second ring plate 84b, the outer peripheral end of which is welded to the inner surface of the front outer shell 40, and the outer peripheral end of the second ring plate 84b at the rear of the first ring plate 84a. A third ring plate 84c welded to the inner surface of the outer body 40. The width of the third ring plate 84c may be set larger than that shown in the figure. The number of ring plates is not limited to three, four or more may be provided, and the third ring plate 84c may be omitted.

A second intrusion prevention mechanism 85 that prevents intrusion of earth and sand between the rear end of the rear inner cylinder 20c and the rear end of the rear outer cylinder 50 is also provided at the rear ends of the inner cylinder 2A and the outer cylinder 2B. It has been. Since the second intrusion prevention mechanism 85 has the same structure as the first intrusion prevention mechanism 84, description thereof is omitted.
The left and right divided seal structures 61 and 71 prevent sand and sand from intruding between the inner body 2A and the outer body 2B from the left and right front outer body variable connecting portions 60 and the left and right rear outer body variable connecting portions 70. This corresponds to a “third intrusion prevention mechanism” to be prevented.

  Next, load detection means for detecting a compressive load acting on the top of the outer trunk 2B from the natural ground will be described. A load detector 86a (load detection means) for detecting a load (compressive load) acting on the top plate portion 41a from the natural ground between the top plate portion 41a and the front inner body 20a at the front-rear position in the vicinity of the front side of the annular frame 30. Is provided. Further, a load detector 86b for detecting a load (compressive load) acting on the top plate portion 51a from the natural ground between the top plate portion 51a and the rear inner trunk 20c at a position in the front-rear direction corresponding to the vicinity of the rear side of the main gripper 11. Load detection means) is provided, and the detection signals of these load detectors 86a and 86b are supplied to a control unit (not shown). However, the load detectors 86 a and 86 b have a configuration that does not prevent the diameter reduction of the front outer cylinder 40 and the rear outer cylinder 50. The top plate portions 41a and 51a correspond to the “top plate portion” in the upper part of the outer trunk.

Next, the operation and effect of the tunnel excavator 1 described above will be described.
When the load (for example, average load) detected by the load detectors 86a and 86b is less than the first set load during tunnel excavation, the outer body 2B is moved as shown in FIGS. Tunnel excavation is performed in a normal state maintained in an expanded state. In this expanded state, the piston rods of the top hydraulic cylinders 81b, 81c; 82b, 82c; 83b, 83c are maintained in an extended state, and the plurality of front first and second hydraulic cylinders 62, 63 and the plurality of rear parts Tunnel excavation is performed with the piston rods of the first and second hydraulic cylinders 72 and 73 maintained in an extended state.

  When the load detected by the load detectors 86a and 86b starts to become abnormally large and exceeds a predetermined first reference value, all the overcutters 24 of the cutter head 3 are switched to the projecting positions to widen the excavation cross section. Continue the tunnel excavation with the diameter. At this time, in order to maintain the position of the axial center of the tunnel excavator 1 at a constant height, the tunnel excavation is continued with the movable sled 9 being switched to the protruding position. The first reference value is a value determined by the operator according to the specifications of the tunnel excavator, the characteristics of the natural ground, and the like.

  When the collapse of the natural ground starts, the load detected by the load detectors 86a and 86b exceeds the predetermined second reference value, and the tunnel excavator 1 starts to be restrained by the natural ground, all the overcutters 24 are used. Is held in the protruding position, and the outer cylinder 2B is switched to the reduced diameter state. At this time, the piston rods of the top hydraulic cylinders 81b, 81c; 82b, 82c; 83b, 83c are switched to a contracted state, and a plurality of front first and second hydraulic cylinders 62, 63 and a plurality of rear first and second The piston rods of the hydraulic cylinders 72 and 73 are switched to the contracted state. The second reference value is also a value determined by the operator according to the specifications of the tunnel excavator, the characteristics of the natural ground, and the like, like the first reference value.

  Then, the top plate portions 41a and 51a can approach the inner cylinder 2A, and the upper side plates 41b and 41c; 51b and 51c are hinged portions 46b and 46c; 48b and 48c with the top plate portions 41a and 51a. The lower side plates 42b, 42c; 52b, 52c are rotated in the direction of the inner cylinder 2A around the hinge coupling portions 47b, 47c; 49b, 49c with the bottom plate portions 42a, 52a. Thus, as shown in FIGS. 5-7, the part except the baseplate part 42a, 52a of the outer cylinder 2B will be in a diameter-reduced state.

  Therefore, the restraint from the natural ground on the front outer trunk upper portion 41 and the rear outer trunk upper portion 51 of the tunnel excavator 1 can be released, and earth pressure acting on the front outer trunk lower portion 42 and the rear outer trunk lower portion 52 is reduced. It is possible to cancel. As a result, the worker can safely release the restraint in a short period of time without going out of the tunnel excavator 1. Since the outer cylinder 2B provided outside the inner cylinder 2A is reduced in diameter, the shape of the inner cylinder 2A does not change, so the structure of the excavator body inside the tunnel excavator 1 and the attached equipment (cutter head drive mechanism) 5, the outer trunk 2 </ b> B can be reduced in diameter without affecting the thrust jack 6, the shield jack 7, the earth removal equipment 16, the erector 13, and the like. Moreover, since there is the inner body 2A, there is no possibility of water entering the tunnel excavator 1.

  Since at least the bottom plate portions 42a and 52a of the outer cylinder 2B are held in a fixed state with respect to the inner cylinder 2A, the height position of the axial center of the tunnel excavator 1 is kept constant even when the diameter of the outer cylinder 2B is reduced. And there is no risk of the tunnel excavator sinking downward.

  A plurality of top hydraulic cylinders 81b, 81c; 82b, 82c; 83b capable of driving the top plates 41a, 51a in the diameter increasing direction between the top plate portions 41a, 51a of the outer cylinder 2B and the inner cylinder 2A. , 83c, when the outer cylinder 2B is expanded from the reduced diameter state, the top plate portions 41a, 51a are driven to the diameter expansion side by the plurality of top hydraulic cylinders 81b, 81c; 82b, 82c; 83b, 83c, The diameter expansion of the outer body 2B can be promoted.

  A first intrusion prevention mechanism 84 is provided at the front end of the inner cylinder 2A and the front end of the outer cylinder 2B to prevent intrusion of earth and sand between the inner cylinder 2A and the outer cylinder 2B, and the rear end of the inner cylinder 2A and the rear of the outer cylinder 2B. Since the second intrusion prevention mechanism 85 that prevents intrusion of earth and sand between the inner cylinder 2A and the outer cylinder 2B is provided at the end, it is possible to prevent earth and sand from entering between the inner cylinder 2A and the outer cylinder 2B.

Since the pair of left and right third intrusion prevention mechanisms 61 and 71 (divided seal mechanisms) for preventing intrusion of earth and sand between the inner cylinder 2A and the outer cylinder 2B from the pair of left and right variable connection parts 60 and 70 are provided, the variable connection part 60 , 70 can prevent earth and sand from entering between the inner cylinder 2A and the outer cylinder 2B.
Since two load detectors 86a and 86b for detecting loads acting on the natural ground are provided on the top plate portions 41a and 51a of the upper and lower outer shell upper portions 41 and 51, it is possible to detect signs and progress such as collapse of the natural ground. It becomes possible to detect the restraint of the tunnel excavator 1 from the natural ground.

  The cutter head 3 is provided with a plurality of overcutters 24 for enlarging the excavation diameter, and a movable sled 9 capable of projecting to the outside of the outer cylinder 2B at the lower end portion in the vicinity of the front ends of the inner cylinder 2A and the outer cylinder 2B. Since the hydraulic cylinder (advancing / retracting drive means) that drives the movable sled to advance / retract is provided, when the plurality of over cutters 24 are operated to expand the excavating diameter, the movable sled 9 is projected by the hydraulic cylinder, so that the tunnel excavator Tunnel excavation can be continued in a state where the height position of the axial center of 1 is kept constant.

In the tunnel excavation method using the tunnel excavator 1, a diameter reducing means capable of reducing the diameter of the trunk member 2 is provided in the trunk member 2 in advance, and a plurality of over cutters 24 are provided in the cutter head 3. A first step of performing tunnel excavation with an excavation cross-section expanded by a plurality of overcutters 24 when a compressive load by which the natural ground compresses the trunk member 2 exceeds a predetermined first reference value; A second step of performing tunnel excavation in a state where the diameter of the body member 2 is reduced by the diameter reducing means when a second reference value larger than a predetermined first reference value is exceeded.
Therefore, it is possible to suppress the tunnel excavator 1 from being constrained by the ground in the first step, and to release the restraint of the tunnel excavator 1 constrained by the ground in the second step.

A tunnel excavator 1M according to a second embodiment will be described with reference to FIGS.
In this tunnel excavator 1M, the front outer cylinder upper portion 41A is made into one plate member without being divided into three plate members, and the rear outer cylinder upper portion 51A is made into one plate member without being divided into three plate members. The tunnel excavator described above is provided with a plate member and a plurality of spring-type biasing means 90a, 90b, 90c instead of the plurality of top hydraulic cylinders 81b, 81c; 82b, 82c; 83b, 83c. 1 and different. Therefore, the same constituent elements as those of the tunnel excavator 1 are denoted by the same reference numerals, description thereof is omitted, and different constituent elements are mainly described.

  As shown in FIGS. 14 and 15, the inner cylinder 2A includes a front inner cylinder 20a, an intermediate inner cylinder 20b, and a rear inner cylinder 20c. The outer body 2 </ b> B has a front outer body 40 and a rear outer body 50. The front outer body 40 is divided into a front outer body upper part 41A and a front outer body lower part 42 at a slightly upper side in the middle step. The rear outer cylinder 50 is divided into a rear outer cylinder upper part 51 </ b> A and a rear outer cylinder lower part 52 at a slightly upper side of the middle stage part.

The split part obtained by dividing the front outer trunk upper part 41A and the front outer trunk lower part 42 is provided with a pair of left and right front outer trunk variable connecting parts 60, and a rear outer trunk upper part 51A and a rear outer trunk lower part 52, A pair of left and right rear outer body variable connecting portions 70 are provided in the divided portion.
The front outer torso variable connecting portion 60 has the same structure as the front outer torso variable connecting portion 60 of the tunnel excavator 1, and the rear outer torso variable connecting portion 70 is variable to the rear outer torso of the tunnel excavator 1. The structure is the same as that of the connecting portion 70.

  The front outer body lower part 42 is divided into a front outer body bottom plate part 42a, a left front outer body lower side board 42b, and a right front outer body lower side board 42c. Similarly to the tunnel excavator 1, a plurality of hinge coupling portions 47b for connecting the front outer shell bottom plate portion 42a and the left front outer shell lower side plate 42b are also provided, and the front outer shell bottom plate portion 42a and the right front portion A plurality of hinge coupling portions 47c that connect the outer body lower side plate 42c are also provided.

  The rear outer trunk lower part 52 is divided into a rear outer trunk bottom plate part 52a, a left rear outer trunk lower side board 52b, and a right rear outer trunk lower side board 52c. Similarly to the tunnel excavator 1, a plurality of hinge coupling portions 49b for connecting the rear outer shell bottom plate 52a and the left rear outer lower plate 52b are also provided, and the rear outer shell bottom plate 52a and the right rear outer lower plate are provided. There are also provided a plurality of hinge coupling portions 49c that connect 52c.

  In the front-rear direction position corresponding to the rear part of the device mounting frame 4, the front outer cylinder upper part 41A is located between the top of the front outer cylinder upper part 41A (corresponding to the top plate part) and the front inner cylinder 20a when the diameter is reduced. There is provided a spring-type biasing means 90a that can bias the spring in the diameter-expanding direction and incorporates a spring in a non-compressed state or a slightly compressed state. In addition, a coil spring or a disc spring laminated body is employable as a spring.

  In the front-rear direction position corresponding to the front portion of the annular web 29, when the diameter of the rear outer trunk upper portion 51A is reduced between the top of the rear outer trunk upper portion 51A (corresponding to the top plate portion) and the rear inner barrel 20c, the diameter of the rear outer trunk upper portion 51A is increased. A spring-type biasing means 90b similar to the above can be provided. In the front-rear direction position corresponding to the middle part of the rear outer cylinder 50, the rear outer cylinder upper part 51A can be urged in the diameter increasing direction when the diameter is reduced between the top of the rear outer cylinder upper part 51A and the rear inner cylinder 20c. The same spring type urging means 90c is provided. The arrangement position and number of the spring-type biasing means are not limited to the above example.

The operation and effect of the tunnel excavator 1M described above will be described.
When the load acting on the top of the outer trunk 2B begins to become abnormally large, exceeds a predetermined second reference value, and the tunnel excavator 1M starts to be restrained by the natural ground, the left and right variable connecting portions Tunnel excavation is performed by switching the outer cylinder 2B from the enlarged diameter state to the reduced diameter state by contracting the piston rods of the first and second hydraulic cylinders 60, 70;

  When switching to this reduced diameter state, the springs built in the spring-type biasing means 90a to 90c are switched to the compressed state, so that the diameter reduction of the outer body 2B is not hindered and the reduced diameter state is restored to the expanded diameter state. In doing so, the return of the diameter-enlarged state can be facilitated by the extension of the compressed springs of the spring biasing means 90a to 90c.

Next, an example in which the above embodiment is partially changed will be described.
1) In the tunnel excavators 1 and 1M, the lower side plates 42b and 42c; 52b and 52c may be omitted, and the plurality of second hydraulic cylinders 63 and 73 may be omitted.
2) In the tunnel excavator 1, 1M, the “middle stage portion” of the outer trunk is a middle area having a width in the vertical direction (for example, an area having a width of about 1/3 of the vertical width of the outer trunk). That means.

3) In the tunnel excavator 1, 1M, the first and second driving means do not necessarily have to be provided in the middle stage portion, and may be arranged in parts other than the middle stage portion.
4) In the tunnel excavator 1M, a hydraulic cylinder may be employed instead of the spring-type biasing means 90a to 90c.
5) The present invention is not limited to a large-diameter tunnel excavator but can be applied to tunnel excavators having various diameters.
6) The present invention can be similarly applied to a tunnel excavator of a type in which a thrust jack is omitted and excavation propulsion force is generated by a plurality of shield jacks.

  The present invention can be applied to various tunnel excavators that excavate a tunnel with a cutter head equipped with a roller cutter.

1, 1M tunnel excavator 2 body member 2A inner body 2B outer body 3 cutter head 9 movable sled 24 overcutter 40 front outer body 50 rear outer body 41, 41A front outer body upper part 41a front outer body top plate part 41b, 41c Left and right front outer upper side plates 42a Front outer bottom plate portions 42b, 42c Left and right front outer lower side plates 46b, 46c, 47b, 47c Hinge coupling portions 48b, 48c, 49b, 49c Hinge coupling portion 51 Rear outer Trunk upper part 51a Rear outer trunk top plate parts 51b, 51c Left and right rear outer trunk upper side plates 52a Rear outer trunk bottom plate parts 52b, 52c Left and right rear outer trunk lower side plates 60 Front outer trunk variable connecting part 61 Split seal structure (third intrusion) Prevention mechanism)
62 Front First Hydraulic Cylinder 63 Front Second Hydraulic Cylinder 70 Rear Outer Body Variable Connection 71 Cut-off Seal Structure (Third Intrusion Prevention Mechanism)
72 Rear first hydraulic cylinder 73 Rear second hydraulic cylinder 81b, 81c, 82b, 82c, 83b, 83c Top hydraulic cylinder 84, 85 First and second intrusion prevention mechanisms 86a, 86b Load detectors 90a, 90b, 90c Spring type Energizing means

Claims (9)

In a tunnel excavator having a cutter head and a body member,
The body member has an inner body and an outer body disposed concentrically with a predetermined gap with respect to the inner body,
A pair of left and right variable connecting portions are provided at the middle stage of the outer body so that the outer body can be reduced in diameter, and the outer body portion above the variable connecting portion is located at the upper portion of the outer body and below the variable connecting portion. The outer body part is the lower part of the outer body,
The outer torso lower portion has a bottom plate portion held in a fixed state with respect to the inner torso,
The pair of left and right variable connecting portions includes a pair of left and right first driving means for connecting the upper part of the outer body to the inner body so as to be capable of reducing the diameter of the tunnel excavator.   The lower part of the outer body has a pair of left and right lower side plates that are pivotally connected to both ends of the bottom plate part, and the pair of left and right variable connecting parts contracts the pair of left and right lower side plates to the inner body. 2. The tunnel excavator according to claim 1, further comprising a pair of left and right second driving means coupled so as to be capable of radial driving.   3. A plurality of urging means for urging the top plate portion in the diameter-expanding direction when the diameter is reduced is provided between the top plate portion and the inner cylinder at the upper portion of the outer cylinder. The tunnel excavator described.   The outer trunk upper portion includes a top plate portion and a pair of left and right upper side plates rotatably connected to the left and right ends of the top plate portion, and is provided with third driving means for supporting the top plate portion so that the diameter of the top plate portion can be reduced. The tunnel excavator according to claim 2, wherein:   A first intrusion prevention mechanism is provided at the front end of the inner cylinder and the front end of the outer cylinder to prevent intrusion of earth and sand between the inner cylinder and the outer cylinder, and the inner cylinder at the rear end of the inner cylinder and the rear end of the outer cylinder. The tunnel excavator according to claim 1, further comprising a second intrusion prevention mechanism that prevents intrusion of earth and sand between the outer body and the outer trunk.   6. The tunnel excavator according to claim 5, wherein a pair of left and right third intrusion prevention mechanisms for preventing intrusion of earth and sand between the inner cylinder and the outer cylinder are provided from the pair of left and right variable connecting portions.   The tunnel excavator according to claim 1 or 2, wherein at least one load detecting means for detecting a load acting from a natural ground is provided on a top plate portion of the outer shell upper part. The cutter head is provided with a plurality of overcutters for expanding the excavation diameter,
2. A movable sled capable of projecting to the outside of the outer cylinder and an advancing / retreating drive means for advancing and retracting the movable sled are provided at lower end portions of the inner cylinder and the vicinity of the front end of the outer cylinder. 2. The tunnel excavator according to 2. In a tunnel excavation method for excavating a tunnel with a tunnel excavator having a cutter head and a body member,
In advance, a diameter reducing means capable of reducing the diameter of the body member is provided in the body member, and a plurality of over cutters are provided in the cutter head,
A first step of performing tunnel excavation with an excavation cross section expanded by the plurality of overcutters when a compressive load by which the natural ground compresses the trunk member exceeds a predetermined reference value;
A tunnel excavation method comprising: a second step of performing tunnel excavation in a state where the diameter of the trunk member is reduced by the diameter reducing means.