JP2019094738A - Shield tunneling machine - Google Patents

Abstract

To provide a shield tunneling machine capable of removing obstacles even by a central part of a cutter head with low peripheral velocity.SOLUTION: A shield tunneling machine 1 comprises: a cutter head 2, which rotates around a center axis A and has multiple cutter bits 30 on a front surface; a chamber 3, which is disposed on a rear surface side of the cutter head 2 and stores bored sediment; and an earth removal device 4 that discharges the sediment in the chamber 3. The cutter head 2 is disposed so as to be exposed forward at the center and has an open hole 40 communicated with the chamber 3. Multiple cutter bits 30 include multiple first cutter bits 31 that are disposed along circumference of the open hole 40 on the front surface of the cutter head 2.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a shield machine, and more particularly to a shield machine provided with a cutter bit.

  Conventionally, a shield machine having a cutter bit is known (see, for example, Patent Document 1).

  Patent Document 1 discloses a shield machine including a cutter head rotating around a central axis, a chamber in which excavated soil is stored, and a screw conveyor (earth removal device) for discharging soil in the chamber. It is done. In Patent Document 1 described above, a roller bit for rock breaking is provided at the center of the cutter head, and a through hole penetrating the cutter head is provided at the rear of the roller bit for rock breaking (center of the cutter head). In the vicinity of the center of the cutter head, the excavated soil crushed by the rock breaking roller bit passes through the through hole and is taken into the chamber.

Unexamined-Japanese-Patent No. 6-158994

  Here, in shield tunnel construction which passes underground of a construction object in an urban area etc., it is not uncommon to encounter obstacles such as iron piles and steel sheet piles in the ground. In some cases, unexpected obstacles may be encountered, or even if the existence of an obstacle is expected, the route can not be changed and it can not be excluded from the ground because of the superstructure. Therefore, the shield machine is required to have a function of removing obstacles buried in the ground.

  If an unavoidable obstacle is encountered, the shield machine attempts to gradually remove the obstacle by reducing the drilling speed, increasing the rotational speed of the cutter head. However, particularly at the central portion of the cutter head, the peripheral speed is low, so the cutter bit may be damaged because the obstacle can not be cut off, or the obstacle may not be taken up without being cut off and taken into the chamber.

  If it is attempted to remove the obstacle with the shield machine of Patent Document 1, there is a possibility that the obstacle can not be removed and damaged with the roller bit disposed at the central portion where the circumferential speed can hardly be obtained. In addition, since the roller bit is disposed in front of the through hole so as to overlap with the through hole, an obstacle may be caught by the roller bit and can not pass through the through hole and can not be taken into the chamber. If it becomes impossible to dig due to an obstacle, a worker will appear on the front side of the cutter head, and a high-risk work such as removal by gas cutting etc. is required. Therefore, it is desirable to be able to remove obstacles even at the central portion of a cutter head with low peripheral speed.

  The present invention has been made to solve the problems as described above, and one object of the present invention is to be able to remove an obstacle even at the central portion of a cutter head having a low peripheral speed. It is to provide a shield machine.

  In order to achieve the above object, a shield machine according to a first aspect of the present invention is provided with a cutter head which rotates around a central axis and has a plurality of cutter bits on its front face, and a rear face of the cutter head The cutter head has a through hole provided in the center so as to be exposed forward and communicating with the chamber; and The cutter bit includes a plurality of first cutter bits disposed along the periphery of the through hole on the front surface of the cutter head. The front, rear, front, and rear are all based on the front-rear direction in the digging direction. To be exposed forward means that the entire cross section of the through hole is open to the ground in front without being covered. However, the entire cross section of the through hole may not be covered, and a part may be covered locally.

  In the shield machine according to the first aspect of the present invention, as described above, the cutter head is provided with a through hole provided in the center so as to be exposed forward in front and communicating with the chamber, and the front surface of the cutter head And a plurality of first cutter bits disposed along the Here, since the plurality of first cutter bits are located along the periphery of the through hole separated from the central axis of the cutter head, the cutter bits are provided to overlap in front of the through hole (on the central axis) Unlike the case, a certain circumferential speed can be obtained, and the obstacle can be cut effectively. An obstacle present near the center of the cutter head is cut into a size equal to or smaller than the peripheral edge (diameter) of the through hole by the first cutter bit along the peripheral edge of the through hole. Therefore, the cut-off obstacle piece can be passed through and taken into the chamber by the through hole exposed forward at the center of the cutter head. By the above operation, according to the present invention, the obstacle can be removed even at the central portion of the cutter head having a low peripheral speed. Furthermore, the sliding distance (the locus of the first cutter bit along with the rotation) is short near the center of the cutter head, and the plurality of first cutter bits arranged along the periphery of the through hole passes substantially the same locus, It is possible to suppress bit wear during normal ground excavation.

  In the shield machine according to the first aspect, preferably, the plurality of cutter bits further include a plurality of second cutter bits arranged on the outer peripheral side of the first cutter bit, and the first cutter bit is a second cutter bit It has a smaller shape than the cutter bit. According to this structure, the contact area with the obstacle can be reduced and the obstacle can be easily cut by making the first cutter bit near the center with low peripheral speed small in size. Then, the obstacle can be gradually scraped off and cut by the plurality of small-sized first cutter bits.

  In this case, preferably, the first cutter bit is a rod-like or needle-like cutter bit for obstacle cutting, and the second cutter bit is a cutter bit for ground cutting. According to this structure, the second cutter bit disposed on the outer peripheral side having a high circumferential speed secures the advancing performance as a cutter bit for normal ground cutting, and the first cutter disposed at the center having a low peripheral speed. The bit can be made to cut an obstacle easily as a rod-like or needle-like cutter bit for obstacle cutting. In addition, since the center of the cutter head has a short sliding distance (the locus of the first cutter bit accompanying rotation) and the plurality of first cutter bits along the periphery of the through hole have substantially the same locus, the plurality of cutter bits pass Or even if it is a needle-like cutter bit, bit wear at the time of ground excavation can be suppressed.

  In the shield machine according to the first aspect, preferably, the plurality of first cutter bits are arranged along the periphery of the through hole so as to surround the entire periphery of the through hole. According to this structure, by arranging the first cutter bits so as to surround the entire circumference of the through hole, more first cutter bits can pass substantially the same locus as the cutter head rotates. Therefore, approximately the same location of the obstacle can be intensively cut by more first cutter bits. In addition, since more first cutter bits are disposed, even if some of the first cutter bits are damaged by contact with an obstacle, the remaining first cutter bits can remove the obstacle.

  In the shield machine according to the first aspect, the inner diameter of the through hole is preferably smaller than the inner diameter of the earth unloading device. According to this structure, the obstacle piece cut by the first cutter bit can be taken into the chamber through the through hole until it becomes smaller than the inner diameter of the soil removing device. Therefore, the obstacle taken through the through hole and taken into the chamber can be easily removed by the soil removing device, and the obstruction can be suppressed from being blocked in the soil removing device.

  In the shield machine according to the first aspect, preferably, the through hole is opened forward without covering at least the central portion, and configured to allow the obstacle cut by the first cutter bit to pass into the chamber. It is done. According to this structure, at least the central portion of the through hole is opened without being covered by the cutter bit or the like, so that clogging of the cutter bit or the like in the vicinity of the entrance of the through hole can be prevented from clogging the obstacle.

  The shield machine according to the second aspect of the present invention includes a cutter head rotating about a central axis, a chamber provided on the rear side of the cutter head, and a chamber in which excavated soil is stored, and the soil in the chamber. The cutter head is provided at the center, and the cutter head is provided with a through hole for passing an obstacle into the chamber, and a cutter bit for obstacle cutting located near the outer periphery of the periphery of the through hole. including.

  In the shield machine according to the second aspect of the present invention, as described above, the cutter head is provided with the through hole provided at the center for passing an obstacle into the chamber and the outer periphery of the through hole And a cutter bit for cutting the obstacle. Here, since the cutter bit for obstacle cutting is around the through hole distant from the center of the cutter head, a peripheral speed can be obtained to some extent unlike the case where it is provided in front of the through hole, effectively the obstacle Can be cut. Therefore, the obstacle existing near the center of the cutter head is cut by the cutter bit for obstacle cutting and can pass through the central through hole of the cutter head. As a result, the cut obstacle pieces are taken into the chamber through the through holes. As described above, according to the present invention, the obstacle can be removed even at the central portion of the cutter head having a low peripheral speed.

  According to the present invention, as described above, the obstacle can be removed even at the central portion of the cutter head having a low peripheral speed.

1 is a schematic vertical sectional view of a shield machine according to a first embodiment of the present invention. It is a typical front view which looked at a shield drilling machine from a drilling direction front. It is an expanded sectional view showing the through-hole circumference of a cutter head. It is the enlarged front view which showed the through-hole periphery of a cutter head. It is the expanded sectional view which showed the through-hole periphery of the shield machine by 2nd Embodiment of this invention. It is the enlarged front view which showed arrangement | positioning of the 1st cutter bit by the modification of 1st Embodiment. It is typical sectional drawing (A) and a perspective view (B) which showed an example of a 1st cutter bit. It is typical sectional drawing (A) and a perspective view (B) which showed an example of a 2nd cutter bit. It is a typical top view (A) and a perspective view (B) of the 1st modification of the 1st cutter bit. It is a typical top view (A) and a perspective view (B) of the 2nd modification of the 1st cutter bit.

  Hereinafter, embodiments of the present invention will be described based on the drawings.

First Embodiment
A shield machine 1 according to a first embodiment of the present invention will be described with reference to FIGS. 1 to 4.

(Overall configuration of shield machine)
As shown in FIG. 1, the shield machine 1 comprises a cutter head 2 constituting an excavating surface, a chamber 3 in which excavated soil is stored, and a soil removing device 4 for discharging soil in the chamber 3. Have. The shield machine 1 according to the first embodiment has a function of removing the obstacle OM present on the drilling path. In the following, when simply referring to the front, rear, front, rear and the like, the front and rear direction of the digging direction is taken as a reference.

  In the first embodiment, an example in which the shield machine 1 is a mud pressure shield machine is shown. In the mud pressure type shield machine 1, a mud material is injected into the soil excavated by the cutter head 2 in the chamber 3 and mixed with the earth, and the excavated soil is converted to a mud having impermeable and plastic flow properties Ru. The excavated soil (muddy soil) fills the chamber 3 and the soil removing device 4. The shield machine 1 maintains the state in which the excavated soil (muddy soil) is filled in the chamber 3 and the soil removing device 4 and generates pressure in the chamber 3 by the thrust of the shield jack 5 to Counter pressure (face pressure and groundwater pressure). The shield machine 1 digs while balancing the pressure by balancing the amount of digging and the amount of excavated soil.

  The shield machine 1 includes a body 6 formed of cylindrical front and rear portions 6a and 6b. The front torso portion 6a is a portion to which a propulsive force is applied and the cutter head 2 digs the ground, and the rear torso portion 6b constitutes a ring-shaped peripheral wall portion of the tunnel along with the front torso portion 6a. It is a part which advances while arranging segment SG by the elector which is not illustrated.

  The cutter head 2 is configured to rotate around a central axis A along the digging direction, and excavate the ground by rotation. As shown in FIG. 2, the cutter head 2 has a plurality of cutter bits 30 on the front surface. The cutter head 2 is formed in a circular shape as viewed from the digging direction. The front face of the cutter head 2 is composed of a plurality of radial spokes 11 and a cutter face plate 12, and a cutter slit 13 serving as an intake port for excavated earth and sand is formed in the gap between the spokes 11 and the cutter face plate 12. There is.

  In the first embodiment, the cutter head 2 has a through hole 40 communicating with the chamber 3 at the center. That is, the through hole 40 penetrates the radial direction center of the cutter head 2 in the digging direction, and communicates the front side (ground) and the rear side (chamber 3). The through hole 40 is provided at the center of the cutter head 2 so as to be exposed forward.

  As shown in FIG. 1, the cutter head 2 is attached to the swivel base 15 via a cutter column 14 and rotationally driven by a cutter drive unit 16. The swivel base 15 is rotatably supported by the partition wall 7 of the front barrel 6a. The cutter driving unit 16 is disposed at the rear of the partition wall 7 and applies a driving torque to the swivel base 15 to rotationally drive it. That is, the cutter head 2, the cutter column 14, and the swivel base 15 are integrally rotated (pivoted) by the cutter drive unit 16.

  The cutter column 14 is a hollow cylindrical beam member (beam), configured to support the cutter head 2 and to rotate together with the cutter head 2. The front end of the cutter column 14 is attached to the spoke portion 11 of the cutter head 2, and the rear end is attached to the swivel base 15.

  The swivel base 15 is formed in an annular shape, and supports a plurality of cutter columns 14 on the front side. The swivel base 15 is rotatably supported around the central axis A by a bearing provided on the partition 7 of the front barrel 6a.

  The chamber 3 is provided on the rear side of the cutter head 2. The chamber 3 is a space (a mud chamber) surrounded by the cutter head 2, the front body 6 a and the partition 7. Mud pressure in the chamber 3 is measured by a plurality of earth pressure sensors 3a provided at different positions of the installation height. The mud pressure in the chamber 3 is maintained so as to be approximately in equilibrium with the pressure acting on the cutter head 2 from the ground side.

  The shield construction machine 1 includes a shield jack 5 that pushes the segment SG to propel the body 6 (the front body 6a and the rear body 6b). The shield jack 5 is attached to the rear body 6b. A plurality of shield jacks 5 are provided and arranged along the circumferential direction of the body 6. The shield machine 1 is propelled in the digging direction by the propelling force of the shield jack 5. The plurality of shield jacks 5 constitute one block, and the plurality of blocks are arranged over the entire circumference of the inner periphery of the cylindrical rear body 6b. The rotational drive by the cutter drive unit 16 and the application (promotion) of jack thrust by the shield jack 5 are controlled independently.

  In the example of FIG. 1, the earth removal apparatus 4 is comprised by the screw conveyor. The earth unloading device 4 includes a casing 21, a screw 22 and a drive unit 23. The earth unloading device 4 is connected to the chamber 3 and configured to discharge the soil in the chamber 3.

  The casing 21 is a tubular member that constitutes a drainage path for excavated soil. The casing 21 has a cylindrical shape with an inner diameter (diameter) D2. In the casing 21, an inlet (opening) 24 which is open at one end penetrates the partition 7 and is exposed in the chamber 3, and an outlet (discharge) 25 which is an opening at the other end is rearward of the partition 7 It is exposed in the side work area WS. The earth and sand discharged from the outlet 25 is further transported backward by a transport device such as, for example, the belt conveyor 8. The earth unloading device 4 has a function of discharging the soil in the chamber 3 and adjusting the pressure in the chamber 3.

  The screw 22 is disposed in the casing 21 and imparts a conveying force to the excavated soil by rotation. The screw 22 is disposed coaxially with the cylindrical casing 21 and provided rotatably around a central axis. In the example of FIG. 1, the screw 22 is an example of a shafted screw including a rotary shaft 22a and a spiral blade 22b fixed to the rotary shaft 22a. The screw 22 may be a ribbon screw having a spiral blade 22b without a rotating shaft, or may be a composite type screw in which the inlet side is switched from the middle to the shafted screw by the ribbon screw. The screw 22 is rotated by the drive unit 23. By the relative rotation of the screw 22 with respect to the casing 21, earth and sand are transported in the transport direction from the inlet 24 toward the outlet 25.

  The pressure measurement value of the earth pressure sensor 3 a in the chamber 3 is sent to the data processor 17. The data processing device 17 is connected to the control unit 19 of the operation room (driver's cab) 18 of the shield machine 1. The control unit 19 includes a computer including a CPU, a memory, and the like, and controls the operation of the shield machine 1 based on pressure measurement values of the earth pressure sensor 3a and the like, operation input in the operation room 18, and the like. The control unit 19 controls the rotational speed of the cutter head 2 by the cutter drive unit 16, the propulsive force of the shield jack 5 (the digging speed of the shield drilling machine 1), the discharge amount of excavated soil by the soil removing device 4, and the like.

(Cutter head)
Next, the detailed configuration of the cutter head will be described.

  As described above, a plurality of cutter bits 30 are provided on the front surface of the cutter head 2. The cutter bit 30 is an excavating blade for removing soil. The excavated soil cut by the cutter bit 30 enters the chamber 3 inside the cutter head 2 through the cutter slit 13 (see FIG. 2) and the central through hole 40.

  As shown in FIG. 2, in the first embodiment, the plurality of cutter bits 30 includes a plurality of first cutter bits 31 disposed on the front surface of the cutter head 2 along the periphery of the through hole 40. Further, the plurality of cutter bits 30 includes a plurality of second cutter bits 32 disposed on the outer peripheral side of the first cutter bit 31. These cutter bits 30 are fixedly provided on the front surface of the cutter head 2 and excavate earth and sand while rotating integrally with the cutter head 2. In FIG. 2, for convenience, the first cutter bit 31 is shown hatched.

  The first cutter bit 31 is arranged side by side around the through hole 40. The plurality of first cutter bits 31 are disposed within a predetermined range from the center of the through hole 40 (the central axis A of the cutter head 2). The predetermined range is preferably sufficiently close to the through hole 40, and is, for example, a range not less than the radius (D1 / 2) of the through hole 40 shown in FIG. 3 and not more than twice the radius (D1 / 2). . In the example of FIG. 4, the plurality of first cutter bits 31 are positioned at a distance L1 within a predetermined range from the center of the through hole 40 (the central axis A of the cutter head 2) so as to be adjacent to the peripheral edge of the through hole 40 It is arranged side by side. In the example of FIGS. 3 and 4, the distance L1 corresponds to the radius (D1 / 2) of the through hole 40. By arranging the plurality of first cutter bits 31 so as to be adjacent to the peripheral edge of the through hole 40, the locus of the first cutter bit 31 when rotating the cutter head 2 approaches the size of the through hole 40 Can. Therefore, it is possible to cut an obstacle OM (see FIG. 1) such as an iron pile having a dimension larger than the inner diameter D1 of the through hole 40 as small as possible.

  The plurality of first cutter bits 31 are arranged side by side in the circumferential direction of the through hole 40. The plurality of first cutter bits 31 are arranged side by side in one or more rows (see FIG. 6) around the center of the through hole 40 (the central axis A of the cutter head 2). In the example of FIGS. 2 and 4, the plurality of first cutter bits 31 are arranged in a row in the circumferential direction at a distance (radius) L1 from the center of the through hole 40 (the central axis A of the cutter head 2). It is arranged.

  The plurality of first cutter bits 31 are arranged side by side in the circumferential direction, for example, over a predetermined angle range. The predetermined angle range may be less than one turn (360 degrees). In the first embodiment, the plurality of first cutter bits 31 are arranged along the periphery of the through hole 40 so as to surround the entire periphery of the through hole 40. In the example of FIGS. 2 and 4, the plurality of first cutter bits 31 are arranged at equal angular intervals so as to make a round along the periphery of the through hole 40. By arranging the first cutter bits 31 at equal angular intervals, performance variations are caused between normal rotation (for example, counterclockwise as viewed from the front) and reverse rotation (clockwise as viewed from the front) of the cutter head 2. It can be made hard to occur.

  Specifically, in the examples of FIGS. 2 and 4, eight first cutter bits 31 are arranged at an interval of 45 degrees. The number of first cutter bits 31 may be plural other than eight. The number of first cutter bits 31 is, for example, nine at an interval of 40 degrees per row, 12 at an interval of 30 degrees (see FIG. 6), 18 at an interval of 20 degrees, 24 at an interval of 15 degrees, an interval of 12 degrees 30 pieces, 36 pieces at intervals of 10 degrees, and so on. The number of first cutter bits 31 is preferably large. At the time of cutting the obstacle OM, cutting can be performed intensively by the large number of first cutter bits 31, and bit wear of the individual first cutter bits 31 can be suppressed during normal earth and sand cutting.

  In the first embodiment, the first cutter bit 31 has a smaller shape than the second cutter bit 32. The first cutter bit 31 is a rod-like or needle-like cutter bit for cutting an obstacle, and the second cutter bit 32 is a cutter bit for ground cutting different from the first cutter bit 31. For example, in the example of FIGS. 7A and 7B, the first cutter bit 31 is a chip made of cemented carbide embedded in the center of the upper end face of a cylindrical (rod-like or needle-like) base metal portion 31b ( Carbide tip 31a. The tip 31a has a cylindrical shape in which a tapered tip portion is formed, and one tip 31a is provided on the base portion 31b so that the tip portion is exposed from the upper end surface of the base portion 31b.

  For the second cutter bit 32, a cutter bit of an appropriate shape according to the soil quality of the ground to be excavated is selected. The peripheral speed of the second cutter bit 32 on the outer peripheral side of the first cutter bit 31 is higher than that at the center, so that the obstacle bit can be sufficiently removed even by a cutter bit for ordinary ground cutting. The plurality of second cutter bits 32 provided in the cutter head 2 can adopt, for example, one or more of a leading bit, a roller bit, and the like. For example, in the example shown in FIGS. 8A and 8B, the second cutter bit 32 has a structure in which plate-like chips 32a are provided at both corners of a substantially rectangular base metal 32b.

  Although schematically shown in FIG. 4, the second cutter bit 32 has, for example, a rectangular shape of short side a × long side b in a front view (as viewed from the front in the digging direction). The first cutter bit 31 has a circular shape with a diameter c in a front view, and the diameter c is smaller than both the short side a and the long side b. Therefore, the first cutter bit 31 is formed to have a smaller contact area with respect to the obstacle OM than the second cutter bit 32.

  In the example of FIG. 3, the first cutter bit 31 is formed to extend linearly in the digging direction. Further, the first cutter bit 31 has an acute angle at its tip. This makes it possible to further reduce the contact area of the first cutter bit 31 with respect to the obstacle OM. When the obstacle OM is a hard material such as steel, there is a possibility that the tip (tip 31a) of the first cutter bit 31 may chip due to the contact with the obstacle OM. Even in that case, by forming the first cutter bit 31 in a rod shape or a needle shape, it is expected that another tip portion will be formed at the chipped portion, and cutting of the obstacle OM can be continued. In the first embodiment, since the plurality of first cutter bits 31 move along the same locus (rotation locus with the distance L1 as the radius), each first cutter bit 31 is the same position of the obstacle OM as a saw. By sliding, it is possible to perform effective cutting even at a low peripheral speed, and the wear of each first cutter bit 31 can be averaged to suppress bit wear.

  The second cutter bit 32 is disposed on the front surface of the cutter head 2 on the outer peripheral side of the plurality of first cutter bits 31 arranged in a circumferential shape. Although schematically shown in FIG. 2, the second cutter bit 32 radially extends so as to pass through substantially the entire cross section of the front surface of the cutter head 2 except the positions of the through hole 40 and the first cutter bit 31. It is distributed and arranged. That is, the second cutter bits 32 are distributed such that the trajectories formed by the individual second cutter bits 32 pass substantially the entire cross section of the cutter head 2 when the cutter head 2 is rotated once. In the first embodiment, substantially the entire cross section excluding the formation position of the through hole 40 is excavated by the plurality of first cutter bits 31 and the plurality of second cutter bits 32.

  In the examples of FIGS. 2 to 4, the through hole 40 has a circular shape with an inner diameter (diameter) D1. The cross-sectional shape of the through hole 40 may be a polygonal shape such as a rectangular shape other than a circular shape, an elliptical shape, or the like. The inner diameter D1 of the through hole 40 is set according to the inner diameter D2 (see FIG. 1) of the earth unloading device 4. In the first embodiment, the inner diameter D1 of the through hole 40 is smaller than the inner diameter D2 of the earth unloading device 4. The inner diameter of the through hole 40 may be changed in the front-rear direction. Here, the inner diameter D1 of the through hole 40 is the minimum value of the inner diameter of the through hole 40. In the example of FIG. 3, the through hole 40 penetrates the cutter head 2 with a constant inner diameter D1.

  In the example of FIG. 1, the inner diameter D2 of the earth unloading device 4 is the inner diameter of the casing 21. That is, the inner diameter D1 of the through hole 40 is set to a size that allows the obstacle removing device 4 to discharge the obstacle piece that has passed through the through hole 40. The obstacle OM is cut by the first cutter bit 31 into a fine obstacle piece until it is sized to pass through the through hole 40. An obstacle piece cut to a passable size passes through the through hole 40 and is taken into the chamber 3 and discharged by the earth removing device 4. Under the present circumstances, since it cut | disconnected to the size which can pass the through-hole 40, in the earth removal apparatus 4 with an internal diameter larger than the through-hole 40, it is suppressed that the obstruction | occlusion by an obstacle piece generate | occur | produces.

  The inner diameter D1 of the through hole 40 is preferably sufficiently small so that an obstacle piece which has passed through the through hole 40 will not be clogged in the earth unloading device 4. The inner diameter D1 of the through hole 40 is, for example, 2/3 or less of the inner diameter D2 of the earth unloading device 4. In addition, the dischargeable size by the earth unloading device 4 differs depending on whether the screw 22 of the earth unloading device 4 is a screw with a shaft or a ribbon screw. In general, since the dischargeable size by the earth removing device 4 is set as a design specification, the inner diameter D1 of the through hole 40 is preferably equal to or smaller than the dischargeable size by the earth removing device 4. The inner diameter D1 of the through hole 40 may be larger than 2/3 of the inner diameter D2 of the earth unloading device 4 as long as the size is equal to or less than the dischargeable size.

  On the other hand, if the inner diameter D1 of the through hole 40 is too small, the obstacle piece will not easily pass through the through hole 40, and the through hole 40 will be easily clogged. Therefore, it is preferable that the inner diameter D1 of the through hole 40 is not smaller than necessary. The inner diameter D1 of the through hole 40 is, for example, 1/3 or more of the inner diameter D2 of the earth unloading device 4. Therefore, the range of the inner diameter D1 of the through hole 40 is, for example, (1/3) D2 ≦ D1 ≦ (2/3) D2. For example, when the inner diameter D2 of the earth unloading device 4 is sufficiently large, the inner diameter D1 of the through hole 40 may be about 1⁄4 of the inner diameter D2.

  Further, in the first embodiment, the through hole 40 is opened forward without covering at least the central portion, and configured to allow the obstacle OM cut by the first cutter bit 31 to pass into the chamber 3 There is. At least at the center of the through hole 40, at least the center of the through hole 40 is opened forward, and no cutter bit or other structure is disposed on the front on the central axis A, and it is cut. It means that there is no structure which blocks passage of an obstacle piece. At least the central portion, for example, a portion of the first cutter bit 31 or a structure for fixing the first cutter bit 31 in the vicinity of the outer peripheral edge of the through hole 40 partially overlaps the front of the through hole 40 It is meant to allow wrapping (covering the front). Therefore, it is preferable that substantially the entire through hole 40 except for the vicinity of the outer peripheral edge is opened forward without being covered. FIG. 3 shows an example in which the entire through hole 40 is opened forward without being covered. The first cutter bit 31 extends along the central axis A substantially in parallel with the through hole 40 and is provided so as not to overlap with the through hole 40.

  In the first embodiment, the through hole 40 is maintained open forward while the shield machine 1 is drilling. That is, the shield machine 1 is constructed so as to dig in the state where the through hole 40 is opened to the ground side without closing the through hole 40 by a lid, a shutter, a columnar member or the like. Thus, the through hole 40 is configured to pass an obstacle piece in the vicinity of the central portion cut by the first cutter bit 31 into the chamber 3 as the drilling progresses. When the obstacle OM is positioned on the outer peripheral side where the second cutter bit 32 is installed, the obstacle OM can be cut by the second cutter bit 32 having a high peripheral speed, and the cut obstacle piece is It is taken into the chamber 3 from the cutter slit 13.

  As described above, in the first embodiment, the cutter head 2 is provided at the center, and the through hole 40 for passing an obstacle into the chamber 3 and the obstacle arranged in the vicinity of the outer periphery of the through hole 40 And a cutter bit (first cutter bit 31) for cutting an object.

(Operation of shield machine)
Next, the operation of the shield machine 1 related to the removal of the obstacle OM will be described.

  The obstacle OM is an object buried in the ground other than earth and sand (including gravel, cobbles and the like) constituting the ground, and in particular includes an object such as an iron pile and a sheet pile that is difficult to remove. Iron piles and sheet piles are used, for example, at the time of construction of a structure. Iron piles are, for example, steel piles (such as H-shaped steel piles) and RC piles (reinforced concrete piles). The sheet pile is, for example, a steel sheet pile (sheet pile) or the like. These obstacles OM are high in strength, and it is not usually easy to cut or crush as soil. Therefore, when the obstacle OM is encountered, avoidance by digging route change and exclusion from the ground (shaft) are considered, but the route can not be changed, and exclusion from the ground is also possible due to the presence of the upper structure etc. If it can not, the shield machine 1 removes the obstacle OM by digging.

  When removing the obstacle OM, the shield machine 1 operates to remove the obstacle OM. In the operation for removing the obstacle OM, the shield machine 1 operates at a low speed operation where the speed of drilling by the shield jack 5 is lower than that at the time of normal drilling. Further, the shield machine 1 operates at a high-speed rotation that causes the rotation speed of the cutter head 2 by the cutter drive unit 16 to be higher than that at the time of normal digging. That is, the shield machine 1 increases the circumferential speed of the cutter bit 30 and promotes the cutting direction forward at a low speed, and gradually cuts the obstacle OM with the cutter bit 30.

  An obstacle OM near the center of the cutter head 2 is cut by the plurality of first cutter bits 31. Since the plurality of first cutter bits 31 are small and arranged in the circumferential direction along the periphery of the through hole 40, each of the plurality of first cutter bits 31 repeatedly cuts the same portion of the obstacle OM repeatedly Do. As a result, the obstacle OM near the center of the cutter head 2 is finely cut along with the digging. Since the first cutter bit 31 rotates to draw a circular locus of substantially the same size as the through hole 40, the cut obstacle piece is within the range of the size of the locus of the first cutter bit 31 due to rotation. And is easily taken into the through hole 40. An obstacle piece not taken in can be further finely cut by the first cutter bit 31. The obstacle pieces taken into the chamber 3 through the through holes 40 are discharged by the earth removing device 4. Since the inner diameter D1 of the through hole 40 is smaller than the inner diameter D2 of the soil removing device, the obstacle piece that has passed through the through hole 40 easily passes through the inside of the soil removing device 4 and is discharged. Therefore, clogging of the cut-off obstacle piece in the earth unloading device 4 is suppressed.

  Note that on the outer peripheral side of the cutter head 2 other than the center, the obstacle OM is finely cut by the second cutter bit 32 having a high peripheral speed. The cut obstacle pieces are taken into the chamber 3 from the cutter slit 13 and discharged by the soil removing device 4.

(Effect of the first embodiment)
In the first embodiment, the following effects can be obtained.

  In the first embodiment, as described above, the cutter head 2 is provided with the through hole 40 provided in the center so as to be exposed forward and communicating with the chamber 3, and the front face of the cutter head 2 is along the periphery of the through hole 40. A plurality of first cutter bits 31 arranged in the first embodiment are provided. Here, since the plurality of first cutter bits 31 are at positions along the periphery of the through hole 40 separated from the central axis A of the cutter head 2, the cutter bits are over in front of the through hole 40 (on the central axis A). Unlike in the case of being provided to wrap, a certain circumferential speed can be obtained, and the obstacle OM can be effectively cut. The obstacle OM present near the center of the cutter head 2 is cut by the first cutter bit 31 along the periphery of the through hole 40 into a size equal to the periphery (diameter) of the through hole 40. Therefore, the cut-off obstacle piece can be passed through and taken into the chamber 3 by the through hole 40 exposed forward at the center of the cutter head 2. By the above operation, according to the shield machine 1 of the first embodiment, the obstacle OM can be removed even at the central portion of the cutter head 2 having a low peripheral speed. Furthermore, the sliding distance (the locus of the first cutter bit 31 accompanying rotation) at the center of the cutter head 2 is short, and the locus of the plurality of first cutter bits 31 arranged along the periphery of the through hole 40 is substantially the same Therefore, it is possible to suppress bit wear during normal ground excavation.

  The through holes 40 also function to promote earth and sand uptake at the central portion of the cutter head 2 even during normal digging except during operation for removing the obstacle OM. That is, in a general shield machine, a large triangular wing-shaped bit called a fishtail cutter is often attached to the center of the cutter head 2, but the circumferential speed due to rotation is low in the central portion. Intake performance of Therefore, in the center of the cutter head 2, the soil may not be taken in and may be blocked, which may hinder the digging. On the other hand, in the first embodiment, the through hole 40 is provided at the center of the cutter head 2, and the excavated soil at the center can be taken into the chamber 3 from the through hole 40. Therefore, it can be expected that the penetration performance of excavated earth and sand at the center of the cutter head 2 can be improved by the through hole 40 even during normal digging except during operation for removing the obstacle OM.

  In the first embodiment, as described above, the first cutter bit 31 is formed in a smaller shape than the second cutter bit 32. As a result, by making the first cutter bit 31 near the center with a low peripheral speed into a small shape, it is possible to reduce the contact area with the obstacle OM and make it easier to cut the obstacle OM. Then, the obstacle OM can be gradually scraped and cut by the plurality of small-sized first cutter bits 31.

  In the first embodiment, as described above, the first cutter bit 31 is a rod-like or needle-like cutter bit for cutting an obstacle, and the second cutter bit 32 is a cutter bit for ground cutting. As a result, the second cutter bit 32 disposed on the outer peripheral side having a high circumferential speed secures the advancing performance as a cutter bit for normal ground cutting, and the first cutter bit 31 disposed at the center at a low circumferential speed is provided. The obstacle OM can be easily cut as a rod-like or needle-like cutter bit for obstacle cutting. Further, as described above, since the plurality of first cutter bits 31 have a short sliding distance and pass substantially the same trajectory, even if they are rod-like or needle-like cutter bits, bit wear during normal ground excavation can be avoided. It can be suppressed.

  In the first embodiment, as described above, the plurality of first cutter bits 31 are arranged along the periphery of the through hole 40 so as to surround the entire periphery of the through hole 40. As a result, as the cutter head 2 rotates, more first cutter bits 31 follow substantially the same trajectory. Therefore, substantially the same portion of the obstacle OM can be intensively cut by more first cutter bits 31. Also, since more first cutter bits 31 are disposed, even if some of the first cutter bits 31 are damaged by contact with the obstacle OM, the remaining first cutter bits 31 remove the obstacle OM. Can.

  In the first embodiment, as described above, the inner diameter D1 of the through hole 40 is smaller than the inner diameter D2 of the earth unloading device 4. Thereby, the obstacle piece cut by the first cutter bit 31 can be taken into the chamber 3 through the through hole 40 until it becomes smaller than the inner diameter D2 of the earth unloading device 4. Therefore, the obstacle OM taken through the through hole 40 and taken into the chamber 3 can be easily discharged by the soil removing device 4 and the obstruction OM is suppressed from being clogged in the soil removing device 4 it can.

  In the first embodiment, as described above, the through hole 40 is opened forward without covering at least the central portion, and the obstacle OM cut by the first cutter bit 31 is allowed to pass into the chamber 3 Configure as. As a result, at least the central portion of the through hole 40 is opened without being covered by a cutter bit or the like, it is possible to prevent the cutter bit or the like from being caught near the entrance of the through hole 40 and blocking the obstacle OM.

  In the first embodiment, as described above, the cutter head 2 is provided at the center and disposed in the vicinity of the outer side of the through hole 40 for passing the obstacle OM into the chamber 3 and the periphery of the through hole 40. And a cutter bit (first cutter bit 31) for cutting an obstacle. As a result, the obstacle OM existing near the center of the cutter head 2 is cut by the cutter bit (first cutter bit 31) for cutting an obstacle so that the inside of the central through hole 40 of the cutter head 2 can be passed. Become. As a result, since the cut obstacle piece can be taken into the chamber 3 through the through hole 40, the obstacle OM can be removed even at the central portion of the cutter head 2 having a low peripheral speed.

Second Embodiment
Next, a second embodiment of the present invention will be described with reference to FIG. FIG. 5 shows an enlarged cross section around the central portion (central axis A) of the cutter head 2 of the second embodiment, which corresponds to FIG. 3 of the first embodiment. In the second embodiment, an example will be described in which the positions and shapes of the through holes 140 and the first cutter bits 131 are different from those of the first embodiment. In the second embodiment, the configuration other than the positions and shapes of the through hole 140 and the first cutter bit 131 is the same as that of the first embodiment, and thus the description thereof will be omitted.

  In the second embodiment shown in FIG. 5, the through hole 140 is formed so that the inner diameter changes along the front-rear direction (drilling direction).

  Specifically, the through hole 140 has an enlarged portion 141 whose inner diameter increases toward the chamber 3 (rearward) at the rear of the chamber 3 side. The through hole 140 also has an inclined edge 142 formed on the front side by increasing the inner diameter toward the front. The through hole 140 has the smallest inside diameter at the intermediate portion 143 between the enlarged portion 141 and the inclined edge portion 142 in the front-rear direction.

  The inner diameter D11 of the middle portion 143 is, for example, substantially equal to the inner diameter D1 of the through hole 40 of the first embodiment. That is, the inner diameter D11 of the intermediate portion 143 is set according to the inner diameter D2 of the earth unloading device 4. The inner diameter D11 of the middle portion 143 is smaller than the inner diameter D2 of the earth removing device 4, and the range of the inner diameter D11 of the middle portion 143 is, for example, (1/3) D2 ≦ D11 ≦ (2/3) D2. In FIG. 5, the intermediate portion 143 is a boundary between the enlarged portion 141 and the inclined edge 142 (apex portion of the inclined inner peripheral surface of the through hole 140). The middle portion 143 may be formed to extend in the front-rear direction with a constant inner diameter between the enlarged portion 141 and the inclined edge portion 142.

  The enlarged portion 141 is formed to extend rearward from the intermediate portion 143 to the opening on the chamber 3 side (the rear surface of the cutter head 2). In the enlarged portion 141, the inner diameter is expanded at a substantially constant rate toward the chamber 3 (rearward), and the inner surface is a linear inclined surface in the cross section of FIG. The enlarged portion 141 has the largest inner diameter D12 at the opening on the chamber 3 side. The inner diameter D12 is larger than the inner diameter D11 of the intermediate portion 143, for example, larger than the inner diameter D2 of the earth unloading device 4.

  By thus enlarging the inner diameter of the through hole 140 to the rear side, it is possible to make the soil and obstacle pieces entering the through hole 140 easy to flow out into the chamber 3. That is, the inside of the through hole 140 is prevented from being clogged and blocked for some reason. In addition, since the through hole 140 has a shape narrowed at the intermediate portion 143 by the minimum inner diameter D11 more than the enlarged portion 141, passage of an obstacle piece having a size not to pass through the earth removing device 4 is suppressed. Ru.

  The inclined edge 142 is formed to extend forward from the middle portion 143 to the opening on the ground side (the front surface of the cutter head 2). The inner edge of the inclined edge portion 142 is expanded at a substantially constant rate toward the front, and the inner surface in the cross section of FIG. 5 is a linear inclined surface. The beveled edge 142 has a largest inside diameter D13 at the front opening. The inner diameter D13 is larger than the inner diameter D11 of the intermediate portion 143, for example, larger than the inner diameter D2 of the earth unloading device 4. The inner diameter D13 is smaller than, for example, the maximum inner diameter D12 of the enlarged portion 141. The inclined edge 142 is provided as an edge of the through hole 140 for installing the first cutter bit 131. In other words, in the second embodiment, the through hole 140 has the inclined edge 142 recessed conically from the front surface of the cutter head 2, and the plurality of first cutter bits 131 have a conical inclined edge. The portion 142 is circumferentially disposed along the sloped edge 142. Therefore, the inner diameter D13 of the inclined edge 142 is the size of the first cutter bit 131 (that is, the length of the slope on which the first cutter bit 131 is installed) and the direction of the first cutter bit 131 (that is, the inclined edge 142). Is set according to the inclination angle with respect to the central axis A of

  In the second embodiment, the plurality of first cutter bits 131 are disposed along the peripheral edge of the through hole 140 by being provided at the inclined edge 142. Although not shown, the first cutter bit 131 is arranged along the periphery of the through hole 140 so as to surround the entire periphery of the through hole 140, as in the first embodiment (see FIG. 4). The first cutter bit 131 has a needle-like shape that narrows toward the tip. The plurality of first cutter bits 131 are provided to project forward from the inclined edge 142 in the digging direction and to be inclined inward in the radial direction of the cutter head 2 (the side of the central axis A). As a result, in the second embodiment, the tip end portion 132 of each first cutter bit 131 is disposed slightly inside the minimum inner diameter D11 of the through hole 140, and slightly in the front-rear direction with the outer peripheral portion of the through hole 140. Overlap. That is, the movement locus of the tip portion 132 of the first cutter bit 131 along with the rotation of the cutter head 2 has a circular shape with a radius L2 around the central axis A. The diameter (2 × L2) of this movement trajectory is slightly smaller than the minimum inner diameter D11 of the through hole 140. However, also in the second embodiment, the through hole 140 is opened forward without covering at least the central portion, and is configured to pass the obstacle cut by the first cutter bit 131 into the chamber 3 There is.

  Thereby, when there is an obstacle OM located near the central portion of the cutter head 2, the first cutter bit 131 can cut the obstacle OM to a size smaller than the minimum inner diameter D11 of the through hole 140 is there. Then, the cut obstacle piece passes through the middle portion 143 of the minimum inner diameter D11 of the through hole 140 and is taken into the chamber 3. After passing through the intermediate portion 143, the inner diameter is enlarged by the enlarged portion 141, so that the occurrence of clogging of the through hole 140 is effectively suppressed.

(Effect of the second embodiment)
In the second embodiment, the following effects can be obtained.

  In the second embodiment, as in the first embodiment, the cutter head 2 is provided with a through hole 140 provided in the center so as to be exposed forward and communicating with the chamber 3, and the through hole 140 in the front surface of the cutter head 2. And a plurality of first cutter bits 131 disposed along the peripheral edge (inclined edge 142) of Thereby, the obstacle OM existing near the center of the cutter head 2 is cut by the first cutter bit 131 along the periphery of the through hole 140 into a size equal to the periphery (diameter) of the through hole 40 A cut-off obstacle piece can be passed through and taken into the chamber 3 by means of a through hole 140 exposed forward at the center of 2. As a result, the obstacle OM can be removed even at the central portion of the cutter head 2 having a low peripheral speed.

  In the second embodiment, an example in which the inclined edge 142, the intermediate portion 143, and the enlarged portion 141 are provided in the through hole 140 has been described, but the inclined edge 142 may not be provided. That is, in the through hole 40 of the first embodiment, the enlarged portion 141 may be provided on the rear surface side.

[Modification]
It should be understood that the embodiments and modifications disclosed herein are illustrative and non-restrictive in every respect. The scope of the present invention is indicated not by the description of the embodiments described above but by the claims, and further includes all modifications (modifications) within the meaning and scope equivalent to the claims.

  For example, although the example which applied this invention to the mud pressure type shield digging machine was shown in the said, 1st and 2nd embodiment, this invention is not limited to this. The present invention may be applied to a mud shield machine. In the case of a muddy water shield drilling machine, muddy water is sent into the chamber 3 to make excavated soil slurry, and excavated sediment is discharged from the soil removing device 4.

  In the first and second embodiments, the center of the through hole 40 (140) is aligned with the central axis A of the cutter head 2, but the present invention is not limited to this. The through hole may be disposed at the center of the cutter head. For example, the center of the through hole may be offset from the central axis of the cutter head within a range where the central axis of the cutter head passes through the inside of the through hole. However, since it is preferable to provide the through hole and the first cutter head in the vicinity of the rotation center of the cutter head having a low peripheral speed, it is preferable that the center of the through hole coincides with the central axis of the cutter head.

  In the first and second embodiments, the first cutter bit 31 (131) smaller than the second cutter bit 32 is provided. However, the present invention is not limited to this. In the present invention, the first cutter bit may be a cutter bit having the same shape or the same type as the second cutter bit.

  Moreover, although the example which made the 1st cutter bit 31 (131) the rod-shaped or needle-like cutter bit for obstacle cutting was shown in said 1st and 2nd embodiment, this invention is not limited to this. In the present invention, the first cutter bit may be a cutter bit having a shape other than a rod-like or needle-like shape.

  Further, although the example of the rod-like or needle-like first cutter bit 31 having one tip 31a (see FIG. 7) is shown in the first embodiment, the present invention is not limited to this. For example, as shown in FIGS. 9 and 10, a first cutter bit 31 having a plurality of tips 31a may be provided. FIGS. 9A and 9B show an example of the first cutter bit 31 having seven tapered tips 31a. 10A and 10B show an example of the first cutter bit 31 having four fan-shaped tips 31a as viewed from the tip end side. The number of chips 31a may be plural other than four or seven. In the configuration in which the first cutter bit 31 having a plurality of chips 31a is provided, the cutting performance of the first cutter bit 31 by the remaining chips 31a even if any one of the chips 31a is broken in one first cutter bit 31. It is possible to maintain That is, although the chip 31a may be greatly broken and damaged, in the case of a single chip 31a, there is a risk that the crack may progress inside the chip 31a and be largely dropped and lose cutting performance, but a plurality of chips 31a In this way, the progress of the crack stays in the chip 31a in which the crack has occurred, and the risk that the crack does not directly propagate to the other chips 31a can be avoided. Therefore, even when the wear of the tip 31a is severe such as when removing the obstacle OM having high strength, it is possible to suppress an increase in the replacement frequency of the cutter bit, which is effective. The same applies to the first cutter bit 131 of the second embodiment.

  In the first and second embodiments, the plurality of first cutter bits 31 (131) are arranged along the periphery of the through hole 40 (140) so as to surround the entire periphery of the through hole 40 (140). Although an example is shown, the present invention is not limited to this. In the present invention, for example, the plurality of first cutter bits may be provided only at several locations along the periphery of the through hole without surrounding the entire circumference of the through hole.

  In the first and second embodiments, the inner diameter D1 (D11) of the through hole 40 (140) is smaller than the inner diameter D2 of the earth removing device 4, but the present invention is not limited thereto. . In the present invention, for example, the inner diameter of the through hole may be substantially equal to the inner diameter of the earth removing device.

Reference Signs List 1 shield drilling machine 2 cutter head 3 chamber 4 soil removing device 30 cutter bit 31, 131 first cutter bit 32 second cutter bit 40, 140 through hole A central axis D1 through hole inner diameter D2 inner diameter of soil removing device OM obstacle

Claims (7)

A cutter head which rotates around a central axis and which has a plurality of cutter bits on its front surface;
A chamber provided on the rear side of the cutter head for storing excavated soil;
An earth removing device for discharging the earth and sand in the chamber;
The cutter head has a through hole provided in the center to be exposed forward and communicating with the chamber,
The shield machine according to claim 1, wherein the plurality of cutter bits include a plurality of first cutter bits disposed along a peripheral edge of the through hole on a front surface of the cutter head. The plurality of cutter bits further include a plurality of second cutter bits disposed on the outer peripheral side of the first cutter bit,
The shield machine according to claim 1, wherein the first cutter bit has a smaller shape than the second cutter bit. The first cutter bit is a rod-like or needle-like cutter bit for cutting an obstacle,
The shield machine according to claim 2, wherein the second cutter bit is a cutter bit for ground cutting.   The shield machine according to any one of claims 1 to 3, wherein the plurality of first cutter bits are arranged to surround the entire circumference of the through hole along the peripheral edge of the through hole.   The shield machine according to any one of claims 1 to 4, wherein an inner diameter of the through hole is smaller than an inner diameter of the earth unloading device.   The at least one through hole is open forward without covering at least a central portion, and is configured to pass an obstacle cut by the first cutter bit into the chamber. A shield machine as described in 1 above. A cutter head that rotates about a central axis,
A chamber provided on the rear side of the cutter head for storing excavated soil;
An earth removing device for discharging the earth and sand in the chamber;
The cutter head is provided at the center, and includes a through hole for passing an obstacle into the chamber, and a cutter bit for cutting an obstacle located in the vicinity of the outer periphery of the through hole. Machine.

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