Tunnel excavation method

Abstract

This tunnel excavation method for forming a lattice-like tunnel including an outer peripheral tunnel, a drift tunnel provided inside the outer peripheral tunnel, and a cross-cut tunnel provided so as to intersect the drift tunnel inside the outer peripheral tunnel using an excavator comprises excavating an excavation object in a first direction and a second direction intersecting the first direction through use of an excavator to form a part of the outer peripheral tunnel, and excavating the excavation object so as to reach an existing tunnel comprising a part of the formed outer peripheral tunnel to form at least one of the drift tunnel and the cross-cut tunnel.

Description

Title of Invention: TUNNEL EXCAVATION METHOD Technical Field

[0001] The present disclosure relates to a tunnel excavation method. Background Art

[0002] As an underground mining method, a block caving method as disclosed in PTL 1 is known. Citation List Patent Literature

[0003] PTL 1: WO2015 / 151583 Summary of Invention Technical Problem

[0004] In mining ore based on the block caving method, a grid-shaped tunnel is formed in a bedrock using an excavator. The excavator moves forward while excavating the bedrock so as to form a part of the grid-shaped tunnel. After moving backward along the tunnel immediately after the formation, the excavator moves forward while excavating the bedrock again so as to form another part of the grid-shaped tunnel. The excavator forms the grid-shaped tunnel while repeating forward movement and backward movement. If the work procedure for forming the grid-shaped tunnel is inappropriate, the workability of tunnel excavation may decrease.

[0005] An object of the present disclosure is to suppress a decrease in the workability of tunnel excavation. Solution to Problem

[0006] According to the present disclosure, there is provided a tunnel excavation method for forming, by using an excavator, a grid-shaped tunnel including a perimeter tunnel, a drift tunnel provided on an inner side of the perimeter tunnel, and a crosscut tunnel provided so as to intersect the drift tunnel on the inner side of the perimeter tunnel, and the tunnel excavation method includes: excavating an excavation target with the excavator in a first direction and a second direction intersecting the first direction, to form a part of the perimeter tunnel; and excavating the excavation target so as to reach an existing tunnel including the formed part of the perimeter tunnel, to form at least one of the drift tunnel and the crosscut tunnel. Advantageous Effects of Invention

[0007] According to the present disclosure, a decrease in the workability of tunnel excavation is suppressed. Brief Description of Drawings

[0008] [FIG. 1] FIG. 1 is a top view schematically showing an excavator according to an embodiment. [FIG. 2] FIG. 2 is a perspective view schematically showing a cutter head according to the embodiment. [FIG. 3] FIG. 3 is a diagram schematically showing a reinforced tunnel according to the embodiment. [FIG. 4] FIG. 4 is a diagram schematically showing a grid-shaped tunnel according to the embodiment. [FIG. 5] FIG. 5 is a block diagram showing a work procedure generation device according to the embodiment. [FIG. 6] FIG. 6 is a diagram illustrating a work procedure for forming the grid-shaped tunnel according to the embodiment. [FIG. 7] FIG. 7 is a diagram illustrating the work procedure for forming the grid-shaped tunnel according to the embodiment. [FIG. 8] FIG. 8 is a perspective view schematically showing a state where a second crosscut is connected to a first part according to the embodiment. [FIG. 9] FIG. 9 is a diagram schematically showing the state where the second crosscut is connected to the first part according to the embodiment. [FIG. 10] FIG. 10 is a diagram illustrating the work procedure for forming the grid-shaped tunnel according to the embodiment. [FIG. 11] FIG. 11 is a diagram schematically showing a state where a new tunnel is not connected to an existing tunnel. [FIG. 12] FIG. 12 is a diagram illustrating the work procedure for forming the grid-shaped tunnel according to the embodiment. Description of Embodiments

[0009] Hereinafter, an embodiment according to the present disclosure will be described with reference to the drawings, but the present disclosure is not limited to the embodiment. The elements of the embodiment described below can be combined as appropriate. Also, in some cases, some elements are not used.

[0010] [Excavator] FIG. 1 is a top view schematically showing an excavator 1 according to an embodiment. The excavator 1 is a tunnel boring machine (TBM). The excavator 1 excavates an excavation target in order to form a tunnel. In the embodiment, the excavator 1 excavates a bedrock as an excavation target in order to form a tunnel underground. The excavator 1 can form a tunnel underground by moving forward while excavating the bedrock.

[0011] As shown in FIG. 1, the excavator 1 includes a front body section 2, a rear body section 3, a thrust jack 4, and a trailer section 5. The front body section 2 includes a front body 6, a cutter head 7, and a front gripper 8. The rear body section 3 includes a rear body 13 and a rear gripper 14. The trailer section 5 includes a main beam 15 and a backup trolley 16.

[0012] FIG. 2 is a perspective view schematically showing the cutter head 7 according to the embodiment. The cutter head 7 is disposed at a front end part of the excavator 1. The cutter head 7 is rotatably supported by the front body 6. The cutter head 7 rotates about a center axis CX of the front body section 2. The center axis CX extends in the front-rear direction of the front body section 2. The center axis CX passes through the center of the cutter head 7.

[0013] The cutter head 7 includes a cutter body 9, a disc cutter 10 supported by the cutter body 9, an outer plate 11 disposed at a peripheral edge part of the cutter body 9, and a scraper 12 disposed at a peripheral edge part of the cutter body 9.

[0014] The cutter body 9 is substantially disk-shaped. The cutter body 9 is rotatably supported by the front body 6. A rotary motor, not illustrated, that is connected to the cutter body 9 is disposed in the front body 6. The cutter body 9 rotates about the center axis CX by a rotational force generated by the rotary motor.

[0015] The disc cutter 10 excavates the bedrock. The disc cutter 10 is supported by the cutter body 9. Multiple disc cutters 10 are provided on the cutter body 9. As the cutter body 9 rotates about the rotation axis CX, the bedrock is excavated by the multiple disc cutters 10.

[0016] The outer plate 11 prevents a crushed material of the bedrock crushed by the disc cutter 10 from being conveyed from the peripheral edge part of the cutter head 7 to a position rearward of the cutter head 7. The outer plate 11 has an annular shape. The outer plate 11 is fixed to a peripheral edge part of the cutter body 9. In the radial direction of the center axis CX, the outer plate 11 protrudes outward from an outer end part of the cutter body 9. The outer plate 11 is attachable to and detachable from the cutter body 9.

[0017] The scraper 12 picks up the crushed material of the bedrock crushed by the disc cutter 10. Multiple scrapers 12 are disposed at intervals on the peripheral edge part of the cutter body 9. The scraper 12 is fixed to the peripheral edge part of the cutter body 9. In the radial direction of the center axis CX, the scraper 12 protrudes outward from the outer end part of the cutter body 9. The scraper 12 is attachable to and detachable from the cutter body 9. The crushed material of the bedrock crushed by the disc cutter 10 accumulates on the ground below the cutter body 9. As the cutter body 9 rotates, the scraper 12 picks up the crushed material accumulating on the ground. A belt conveyor 18 is disposed rearward of the cutter body 9. The crushed material picked up by the scraper 12 is supplied to the belt conveyor 18. The belt conveyor 18 conveys the crushed material to a position rearward of the excavator 1.

[0018] The front gripper 8 is movably supported by the front body 6. Multiple front grippers 8 are disposed around the front body 6. Multiple front grippers 8 are disposed around the center axis CX. A hydraulic cylinder, not illustrated, that is connected to the front gripper 8 is disposed in the front body 6. The front gripper 8 is moved in the radial direction of the center axis CX by a driving force generated by the hydraulic cylinder disposed in the front body 6.

[0019] The thrust jack 4 is disposed between the front body section 2 and the rear body section 3. The front body 6 of the front body section 2 and the rear body 13 of the rear body section 3 are connected via the thrust jack 4. The thrust jack 4 is a hydraulic cylinder. Multiple thrust jacks 4 are provided. The thrust jack 4 operates such that the relative positions of the front body section 2 and the rear body section 3 change in the front-rear direction. When the thrust jack 4 extends, the front body section 2 moves forward in relation to the rear body section 3. When the thrust jacks 4 operate such that the amounts of extension of the multiple thrust jacks 4 differ from each other, the direction of the front body section 2 in relation to the rear body section 3 changes. The rear gripper 14 is movably supported by the rear body 13. Multiple rear grippers 14 are disposed around the rear body 13. Multiple rear grippers 14 are disposed around the center axis CX. A hydraulic cylinder, not illustrated, that is connected to the rear gripper 14 is disposed in the rear body 13. The rear gripper 14 moves in the radial direction of the center axis CX by a driving force generated by the hydraulic cylinder disposed in the rear body 13.

[0021] At least a part of the main beam 15 is disposed rearward of the rear body section 3. The backup trolley 16 is coupled to a rear part of the main beam 15. The backup trolley 16 is coupled to a rear part of the main beam 15. The trailer section 5 and the backup trolley 16 are pulled by the front body section 2. A front part of the main beam 15 is coupled to the front body 6 of the front body section 2. A through hole is provided in the rear body 13. At least a part of the main beam 15 is disposed in the through hole of the rear body 13. A front part of the main beam 15 is coupled to the front body 6 via the rear body 13. The worker can get on board a work space 15A of the main beam 15 and perform work. Devices such as an engine, a hydraulic device, an electric generator, a concrete spraying machine, a water tank, and a controller are installed on the backup trolley 16.

[0022] A rail 17 is laid in the tunnel. When the excavator 1 moves forward to excavate the excavation target, the backup trolley 16 moves forward along the rail 17. When the excavator 1 moves backward, the excavator 1 including the front body section 2, the rear body section, the thrust jack 4, and the trailer section 5 moves backward along the rail 17. The backup trolley 16 has wheels that can travel on the rail 17. The backup trolley 16 moves along the rail 17. The excavator 1 need not move along the rail. Tires may be mounted on the excavator 1. The excavator 1 may be moved by the rotation of the tires. The belt conveyor 18 is supported by the backup trolley 16. A front part of the belt conveyor 18 is disposed in the front body section 2. A rear part of the belt conveyor 18 is disposed at a rear part of the backup trolley 16. The crushed material dropped onto the front part of the belt conveyor 18 by the scraper 12 is conveyed to the rear part of the belt conveyor 18. The belt conveyor 18 supplies the crushed material to a transport vehicle 50 disposed rearward of the excavator 1. After the crushed material is loaded on a load-carrying platform of the transport vehicle 50, the transport vehicle 50 transports the crushed material to a predetermined discharging position. When the bedrock is excavated, the rear gripper 14 moves radially outward and is pressed against the inner wall of the tunnel that is being formed. As the rear gripper 14 is pressed against the inner wall of the tunnel, the rear body section 3 is fixed to the inner wall of the tunnel. After the rear gripper 14 moves radially outward so that the rear body section 3 is fixed to the inner wall of the tunnel, the front gripper 8 moves radially inward so as to move away from the inner wall of the tunnel. As the thrust jack 4 extends while the cutter head 7 rotates in the state where the rear body section 3 is fixed to the inner wall of the tunnel, the bedrock is excavated. The cutter head 7 excavates the bedrock while moving forward.

[0024] After the thrust jack 4 fully extends, the front gripper 8 moves radially outward and is pressed against the inner wall of the tunnel that is being formed. As the front gripper 8 is pressed against the inner wall of the tunnel, the front body section 2 is fixed to the inner wall of the tunnel. After the front gripper 8 moves radially outward so that the front body section 2 is fixed to the inner wall of the tunnel, the rear gripper 14 moves radially inward so as to move away from the inner wall of the tunnel. As the thrust jack 4 contracts in the state where the front body section 2 is fixed to the inner wall of the tunnel, the front body section 2 and the trailer section 5 including the main beam 15 and the backup trolley 16 move forward.

[0025] After the rear body section 3 and the trailer section 5 move forward, the rear gripper 14 moves radially outward so that the rear body section 3 is fixed to the inner wall of the tunnel, and the front gripper 8 moves radially inward so as to move away from the inner wall of the tunnel. As the thrust jack 4 extends while the cutter head 7 rotates in the state where the rear body section 3 is fixed to the inner wall of the tunnel, the bedrock is excavated. The cutter head 7 excavates the bedrock while moving forward. As the above-described operation is repeated, the bedrock is thus excavated little by little and the formation of the tunnel progresses.

[0026] The worker on board the main beam 15 performs reinforcement work for the tunnel immediately after being formed by the excavator 1. The reinforcement work includes work of drilling a hole in the inner wall of the tunnel using a drill, work of pouring concrete into the hole after laying a wire mesh on the inner wall surface of the tunnel, work of inserting a rock bolt into the hole after the concrete is poured, work of closing the hole with a metal plate, and work of spraying liquid concrete onto the inner wall surface of the tunnel using a spray nozzle. The wire mesh laid on the inner wall surface of the tunnel is fixed to the inner wall surface by the head of the rock bolt. The liquid concrete is sprayed onto the inner wall surface of the tunnel via the wire mesh. As the liquid concrete is solidified and changed into solid concrete, the tunnel is reinforced.

[0027] FIG. 3 is a diagram schematically showing the reinforced tunnel according to the embodiment. In FIG. 3, a dotted line Ta indicates the inner wall of the tunnel before reinforcement immediately after being formed by the excavator 1. The inner diameter of the tunnel before reinforcement is substantially equal to the outer diameter of the cutter head 7. A line Tb indicated by a solid line indicates the inner wall of the reinforced tunnel on which the reinforcement work is done. The inner wall of the reinforced tunnel includes a reinforcement layer 31 formed of solid concrete. Since the reinforcement layer 31 is formed, the inner diameter of the reinforced tunnel is smaller than the inner diameter of the tunnel before reinforcement.

[0028] After the reinforced tunnel is formed, the excavator 1 moves backward along the reinforced tunnel. The inner diameter of the reinforced tunnel is likely to be smaller than the outer diameter of the cutter head 7. At least a part of the cutter head 7 may be caught on the inner wall of the reinforced tunnel, and it may be difficult for the excavator 1 to move backward along the reinforced tunnel.

[0029] Therefore, the front end part of the excavator 1 is adjusted before the excavator 1 is moved backward along the reinforced tunnel. The adjustment of the front end part of the excavator 1 includes a process of reducing the outer diameter of the cutter head 7. The process of reducing the outer diameter of the cutter head 7 includes a process of removing a component from the cutter head 7. In the embodiment, the process of removing a component from the cutter head 7 includes a process of removing, from the cutter body 9, components such as the disc cutter 10, the outer plate 11, and the scraper 12 disposed at the peripheral edge part of the cutter body 9. The process of reducing the outer diameter of the cutter head 7 includes a process of moving the components of the cutter head 7 radially inward. The process of moving the components of the cutter head 7 radially inward includes a process of housing or laying down the components disposed on the peripheral edge part of the cutter body 9 radially inward. In the following description, components that are moved to reduce the outer diameter of the cutter head 7, such as the disc cutter 10, the outer plate 11, and the scraper 12 disposed at the peripheral edge part of the cutter body 9, are referred to as peripheral edge components, as appropriate.

[0030] In the radial direction of the center axis CX, the peripheral edge components protrude outward from the outer end part of the cutter body 9. The peripheral edge components are attachable to and detachable from the cutter body 9. The peripheral edge components are movable relative to the cutter body 9. As the peripheral edge components are detached or moved from the cutter body 9, the outer diameter of the cutter head 7 is reduced. As the outer diameter of the cutter head 7 is reduced, the cutter head 7 can pass through the reinforced tunnel. As the outer diameter of the cutter head 7 is reduced, the excavator 1 can move backward along the reinforced tunnel.

[0031] [Grid-Shaped Tunnel] FIG. 4 is a diagram schematically showing a gridshaped tunnel 100 according to the embodiment. In the embodiment, ore is mined based on the block caving method. As shown in FIG. 4, when ore is mined based on the block caving method, the grid-shaped tunnel 100 is formed underground using the excavator 1. After the grid-shaped tunnel 100 is formed, the ceiling wall at a drawpoint of the grid-shaped tunnel 100 is undercut and blasted. As the ceiling wall at the drawpoint is undercut and blasted, the ore spontaneously collapses and is mined.

[0032] The grid-shaped tunnel 100 includes a rectangular perimeter tunnel 200, a drift tunnel 300 provided on the inner side of the perimeter tunnel 200, and a crosscut tunnel 400 provided on the inner side of the perimeter tunnel 200 so as to intersect the drift tunnel 300.

[0033] The perimeter tunnel 200 includes a first part 201 extending in a first direction, a second part 202 extending in a second direction intersecting the first direction, a third part 203 extending in the first direction, and a fourth part 204 extending in the second direction. As an example, the first direction is a north-south direction. The second direction is an east-west direction. Each of the first part 201 and the third part 203 extends in the north-south direction. The first part 201 is provided to the east of the third part 203. Each of the second part 202 and the fourth part 204 extends in the east-west direction. The second part 202 is provided to the north of the fourth part 204.

[0034] A north end part of the first part 201 and an east end part of the second part 202 are connected together. A west end part of the second part 202 and a north end part of the third part 203 are connected together. A south end part of the third part 203 and a west end part of the fourth part 204 are connected together. An east end part of the fourth part 204 and a south end part of the first part 201 are connected together.

[0035] The drift tunnel 300 extends in the north-south direction. Multiple drift tunnels 300 are provided. The multiple drift tunnels 300 are provided substantially parallel to each other. In the embodiment, four drift tunnels 300 are provided. The drift tunnels 300 include a first drift 301, a second drift 302, a third drift 303, and a fourth drift 304. In the east-west direction, the multiple drift tunnels 300 are disposed between the first part 201 and the third part 203. The first drift 301, the second drift 302, the third drift 303, and the fourth drift 304 are disposed in this order from east to west.

[0036] A south end part of each of the first drift 301, the second drift 302, the third drift 303, and the fourth drift 304 is connected to the fourth part 204. A north end part of each of the first drift 301, the second drift 302, the third drift 303, and the fourth drift 304 is connected to the second part 202.

[0037] The crosscut tunnel 400 extends substantially in the east-west direction. In the embodiment, the crosscut tunnel 400 is inclined to the north as it goes to the east. Multiple crosscut tunnels 400 are provided. The multiple crosscut tunnels 400 are provided substantially parallel to each other. In the embodiment, twelve crosscut tunnels 400 are provided. The crosscut tunnels 400 include a first crosscut 401, a second crosscut 402, a third crosscut 403, a fourth crosscut 404, a fifth crosscut 405, a sixth crosscut 406, a seventh crosscut 407, an eighth crosscut 408, a ninth crosscut 409, a tenth crosscut 410, an eleventh crosscut 411, and a twelfth crosscut 412. In the northsouth direction, the multiple crosscut tunnels 400 are disposed between the second part 202 and the fourth part 204. The first crosscut 401, the second crosscut 402, the third crosscut 403, the fourth crosscut 404, the fifth crosscut 405, the sixth crosscut 406, the seventh crosscut 407, the eighth crosscut 408, the ninth crosscut 409, the tenth crosscut 410, the eleventh crosscut 411, and the twelfth crosscut 412 are disposed in this order from south to north.

[0038] A west end part of the first crosscut 401 is connected to the first drift 301. A west end part of the second crosscut 402 is connected to the second drift 302. A west end part of the third crosscut 403 is connected to the third drift 303. A west end part of the fourth crosscut 404 is connected to the fourth drift 304. An east end part of each of the first crosscut 401, the second crosscut 402, the third crosscut 403, and the fourth crosscut 404 is connected to the first part 201.

[0039] A west end part of each of the fifth crosscut 405, the sixth crosscut 406, the seventh crosscut 407, and the eighth crosscut 408 is connected to the third part 203. An east end part of each of the fifth crosscut 405, the sixth crosscut 406, the seventh crosscut 407, and the eighth crosscut 408 is connected to the first part 201.

[0040] A west end part of each of the ninth crosscut 409, the tenth crosscut 410, the eleventh crosscut 411, and the twelfth crosscut 412 is connected to the third part 203. An east end part of the ninth crosscut 409 is connected to the first drift 301. An east end part of the tenth crosscut 410 is connected to the second drift 302. An east end part of the eleventh crosscut 411 is connected to the third drift 303. An east end part of the twelfth crosscut 412 is connected to the fourth drift 304.

[0041] A mining area 500 for mining minerals is defined on the inner side of the perimeter tunnel 200. The mining area 500 and the perimeter tunnel 200 do not overlap each other. The mining area 500 and at least a part of the drift tunnel 300 overlap each other. The mining area 500 and at least a part of the crosscut tunnel 400 overlap each other.

[0042] [Work Procedure Generation Device] FIG. 5 is a block diagram showing a work procedure generation device 20 according to the embodiment. The work procedure generation device 20 generates a work procedure for forming the grid-shaped tunnel 100. If the work procedure for forming the grid-shaped tunnel 100 is inappropriate, the workability of tunnel excavation may decrease. The work procedure generation device 20 generates a work procedure for forming the grid-shaped tunnel 100 so as to suppress a decrease in the workability of tunnel excavation.

[0043] The work procedure generation device 20 includes a computer system 1000. The work procedure generation device 20 includes a processor 1001 such as a central processing unit (CPU), a main memory 1002 including a nonvolatile memory such as a read-only memory (ROM) and a volatile memory such as a random-access memory (RAM), a storage 1003, and an interface 1004 including an input / output circuit. The functions of the work procedure generation device 20 are stored as a computer program in the storage 1003. The processor 1001 reads the computer program from the storage 1003, loads the computer program into the main memory 1002, and generates a work procedure for forming the grid-shaped tunnel 100 according to the computer program. Here, the computer program may be distributed to the computer system 1000 via a network.

[0044] [Tunnel Excavation Method] Next, a tunnel excavation method according to the embodiment will be described. FIGS. 6 and 7 are diagrams illustrating the work procedure for forming the grid-shaped tunnel 100 according to the embodiment.

[0045] In the embodiment, after a part of the perimeter tunnel 200 is formed, the work procedure generation device 20 generates the work procedure for forming the grid-shaped tunnel 100 such that at least one of the drift tunnel 300 and the crosscut tunnel 400 is connected to a part of the formed perimeter tunnel 200. The work procedure generation device 20 generates the work procedure such that an end part of a new tunnel, which is a tunnel to be newly formed, is connected to an intermediate part of an existing tunnel, which is a tunnel that is already formed. That is, the work procedure generation device 20 generates the work procedure such that the new tunnel is connected to the existing tunnel from a lateral side of the existing tunnel. The excavator 1 excavates the bedrock, based on the work procedure generated by the work procedure generation device 20.

[0046] As shown in FIG. 6, the excavator 1 excavates the bedrock as an excavation target in the first direction and the second direction intersecting the first direction and thus forms a part of the perimeter tunnel 200. As indicated by an arrow S1 in FIG. 6, the excavator 1 excavates the bedrock such that the first part 201 and the second part 202 of the perimeter tunnel 200 are formed. The excavator 1 moves forward to the north while excavating the bedrock, thus forms the first part 201, subsequently changes course to the west at the north end part of the first part 201, moves forward to the west while excavating the bedrock, and thus forms the second part 202.

[0047] After the first part 201 and the second part 202 of the perimeter tunnel 200 are formed, the excavator 1 moves backward along the second part 202 and the first part 201 and returns to the south end part of the first part 201. Upon returning to the south end part of the first part 201, the excavator 1 starts excavation for forming the drift tunnel 300 and the crosscut tunnel 400.

[0048] As shown in FIG. 7, the excavator 1 excavates the bedrock so as to reach the existing tunnel formed of a part of the perimeter tunnel 200 that is already formed, and forms at least one of the drift tunnel 300 and the crosscut tunnel 400. In the example shown in FIG. 7, the existing tunnels are the first part 201 and the second part 202 of the perimeter tunnel 200. The excavator 1 excavates the bedrock so as to reach the first part 201 and the second part 202, which are existing tunnels.

[0049] In the embodiment, as indicated by an arrow S2 in FIG. 7, the excavator 1 excavates the bedrock such that the first drift 301 to be connected to the second part 202 and the second crosscut 402 to be connected to the first part 201 are formed. The excavator 1 moves forward to the west from the south end part of the first part 201 while excavating the bedrock, thus forms a part of the fourth part 204, subsequently changes course to the north, moves forward to the north while excavating the bedrock, and thus forms the first drift 301. The north end part of the first drift 301 is connected to the second part 202.

[0050] After the first drift 301 is formed, the excavator 1 moves backward along the first drift 301 and returns to the vicinity of the south end part of the first drift 301. Upon returning to the vicinity of the south end part of the first drift 301, the excavator 1 changes course to the east (northeast), moves forward to the east (northeast) while excavating the bedrock, and thus forms the second crosscut 402. The east end part of the second crosscut 402 is connected to the first part 201.

[0051] FIG. 8 is a perspective view schematically showing the state where the second crosscut 402 is connected to the first part 201 according to the embodiment. As indicated by the arrow S2 in FIG. 7, the excavator 1 excavates the bedrock so as to reach the first part 201, which is an existing tunnel, and thus forms the second crosscut 402. The second crosscut 402 is a new tunnel formed after the first part 201. The second crosscut 402 is connected to the first part 201 from a lateral side of the first part 201. After the east end part of the second crosscut 402, which is a new tunnel, is connected to the first part 201, which is an existing tunnel, the excavator 1 is stopped. As shown in FIG. 8, a worker can approach the front end part of the excavator 1 from the first part 201, which is an existing tunnel. A transport vehicle 70 can enter the second crosscut 402 from the first part 201. Predetermined work is performed for the excavator 1 to move backward. The transport vehicle 70 transports, for example, a worker or a work tool necessary for the work for the excavator 1 to move backward. An electric cable 61 is disposed in the first part 201, and a lighting device 60 is connected to the electric cable 61. The front end part of the excavator 1 is illuminated by the lighting device 60 disposed in the first part 201.

[0052] The worker can approach the front end part of the excavator 1 from the first part 201 and adjust the front end part of the excavator 1. The adjustment of the front end part of the excavator 1 includes the maintenance of the front end part of the excavator 1. The adjustment of the front end part of the excavator 1 includes a process of attaching a component to the front end part of the excavator 1. The adjustment of the front end part of the excavator 1 includes a process of removing a component from the front end part of the excavator 1. The adjustment of the front end part of the excavator 1 includes a process of reducing the outer diameter of the cutter head 7 disposed at the front end part of the excavator 1. The process of reducing the outer diameter of the cutter head 7 includes one or both of a process of removing a component from the cutter head 7 and a process of moving a component of the cutter head 7 radially inward. As the lighting device 60 illuminates the front end part of the excavator 1 and the first part 201 and the second crosscut 402 around the front end part of the excavator 1, the workability of the work of adjusting the front end part of the excavator 1 is improved. Also, since the work space is larger than when work is performed in a blind alley, workability is improved.

[0053] In the adjustment of the front end part of the excavator 1, the worker may approach the front end part of the excavator 1 from the first part 201 and adjust the front end part of the excavator 1, and may also approach the front end part of the excavator 1 from a position rearward of the front end part of the excavator 1 and adjust the front end part of the excavator 1. That is, the worker may adjust the front end part of the excavator 1 from both a position forward of and a position rearward of the front end part of the excavator 1.

[0054] FIG. 9 is a diagram schematically showing the state where the second crosscut 402 is connected to the first part 201 according to the embodiment. The reinforcement work is performed on the second crosscut 402, which is a new tunnel immediately after being formed by the excavator 1. As shown in FIG. 9, the reinforcement layer 31 is formed on the inner wall of the second crosscut 402.

[0055] After the second crosscut 402 is formed so as to be connected to the first part 201, the excavator 1 moves backward along the second crosscut 402. The inner diameter of the second crosscut 402 is reduced due to the reinforcement layer 31. Before the excavator 1 is moved backward along the second crosscut 402, the process of reducing the outer diameter of the cutter head 7 is performed. As described above, the process of reducing the outer diameter of the cutter head 7 includes one or both of the process of removing a component from the cutter head 7 and the process of moving a component of the cutter head 7 radially inward. The process of removing a component from the cutter head 7 includes a process of removing a peripheral edge component from the cutter body 9. The process of moving a component of the cutter head 7 radially inward includes a process of housing or laying down a peripheral edge component radially inward. After the front end part of the second crosscut 402, which is a new tunnel, is connected to the first part 201, which is an existing tunnel, the excavator 1 is stopped. In the state where the excavator 1 is stopped, the process of reducing the outer diameter of the cutter head 7 from the first part 201 is performed. That is, the process of reducing the outer diameter of the cutter head 7 from the front side of the cutter head 7 is performed in the state where the excavator 1 is stopped. Since the front end part of the second crosscut 402 is connected to the first part 201, which is an existing tunnel, the worker can approach the cutter head 7 from the first part 201 and smoothly perform the process of reducing the outer diameter of the cutter head 7.

[0056] As the peripheral edge component is removed from the cutter body 9 or moved radially inward, the outer diameter of the cutter head 7 is reduced. As the outer diameter of the cutter head 7 is reduced, the cutter head 7 can pass through the second crosscut 402 with the reinforcement layer 31 formed thereon. As the outer diameter of the cutter head 7 is reduced, the excavator 1 can move backward along the second crosscut 402, which is a new tunnel.

[0057] After the excavator 1 is moved backward, the worker can approach the second crosscut 402 from the first part 201 and form a reinforcement layer 32 on the inner wall of the second crosscut 402 in a predetermined region including the front end part of the second crosscut 402.

[0058] In the embodiment, the north end part of the first drift 301, which is a new tunnel, is connected to the second part 202, which is an existing tunnel. Therefore, when the excavator 1 forming the first drift 301 moves backward from the first drift 301, the worker can approach the front end part of the excavator 1 from the second part 202 and adjust the front end part of the excavator 1 or form the reinforcement layer 32 at the north end part of the inner wall of the first drift 301.

[0059] The excavator 1 excavates the bedrock so as to reach the first part 201 and the second part 202, which are existing tunnels, and sequentially forms the drift tunnel 300 and the crosscut tunnel 400. As described with reference to FIG. 7, the excavator 1 can form the first drift 301 and the second crosscut 402 by moving forward while excavating the bedrock along the arrow S2. After the first drift 301 and the second crosscut 402 are formed, the excavator 1 moves backward to the south end part of the first drift 301.

[0060] FIG. 10 is a diagram illustrating the procedure for forming the grid-shaped tunnel according to the embodiment. After moving backward to the south end part of the first drift 301, the excavator 1 moves forward along an arrow S3 in FIG. 10 while excavating the bedrock. As the excavator 1 moves forward along the arrow S3 while excavating the bedrock, the second drift 302 and the third crosscut 403 are formed. For example, after forming the second drift 302, the excavator 1 moves backward to the vicinity of the south end part of the second drift 302, and moves forward to the east (northeast) while excavating the bedrock so as to form the third crosscut 403. The north end part of the second drift 302 is connected to the second part 202. The east end part of the third crosscut 403 is connected to the first part 201. After the second drift 302 and the third crosscut 403 are formed, the excavator 1 moves backward to the south end part of the second drift 302.

[0061] Since the north end part of the second drift 302 is connected to the second part 202, when the excavator 1 moves backward along the second drift 302, the worker can approach the front end part of the excavator 1 from the second part 202. Since the east end part of the third crosscut 403 is connected to the first part 201, when the excavator 1 moves backward along the third crosscut 403, the worker can approach the front end part of the excavator 1 from the first part 201.

[0062] After moving backward to the south end part of the second drift 302, the excavator 1 moves forward along an arrow S4 in FIG. 10 while excavating the bedrock. As the excavator 1 moves forward along the arrow S4 while excavating the bedrock, the third drift 303 and the fourth crosscut 404 are formed. For example, after forming the third drift 303, the excavator 1 moves backward to the vicinity of the south end part of the third drift 303, and moves forward to the east (northeast) while excavating the bedrock so as to form the fourth crosscut 404. The north end part of the third drift 303 is connected to the second part 202, which is an existing tunnel. The east end part of the fourth crosscut 404 is connected to the first part 201, which is an existing tunnel. After the third drift 303 and the fourth crosscut 404 are formed, the excavator 1 moves backward to the south end part of the third drift 303.

[0063] After moving backward to the south end part of the third drift 303, the excavator 1 moves forward along an arrow S5 in FIG. 10 while excavating the bedrock. As the excavator 1 moves forward along the arrow S5 while excavating the bedrock, the fourth drift 304, the fifth crosscut 405, the seventh crosscut 407, the ninth crosscut 409, and the eleventh crosscut 411 are formed. For example, after forming the fourth drift 304, the excavator 1 moves backward to the vicinity of the south end part of the fourth drift 304, and moves forward to the east (northeast) while excavating the bedrock so as to form, for example, the fifth crosscut 405. After the fifth crosscut 405 is formed, the excavator 1 repeats forward movement and backward movement such that the seventh crosscut 407, the ninth crosscut 409, and the eleventh crosscut 411 are sequentially formed. The north end part of the fourth drift 304 is connected to the second part 202, which is an existing tunnel. The east end part of each of the fifth crosscut 405 and the seventh crosscut 407 is connected to the first part 201, which is an existing tunnel. The east end part of the ninth crosscut 409 is connected to the first drift 301, which is an existing tunnel, and the east end part of the eleventh crosscut 411 is connected to the third drift 303, which is an existing tunnel. After the fourth drift 304, the fifth crosscut 405, the seventh crosscut 407, the ninth crosscut 409, and the eleventh crosscut 411 are formed, the excavator 1 moves backward to the south end part of the fourth drift 304.

[0064] After moving backward to the south end part of the fourth drift 304, the excavator 1 moves forward along an arrow S6 in FIG. 10 while excavating the bedrock. As the excavator 1 moves forward along the arrow S6 while excavating the bedrock, the third part 203, the sixth crosscut 406, the eighth crosscut 408, the tenth crosscut 410, and the twelfth crosscut 412 are formed. For example, after forming the third part 203, the excavator 1 moves backward to the vicinity of the south end part of the third part 203, and moves forward to the east (northeast) while excavating the bedrock so as to form, for example, the sixth crosscut 406. After the sixth crosscut 406 is formed, the excavator 1 repeats forward movement and backward movement such that the eighth crosscut 408, the tenth crosscut 410, and the twelfth crosscut 412 are sequentially formed. The north end part of the third part 203 is connected to the second part 202. The east end part of each of the sixth crosscut 406 and the eighth crosscut 408 is connected to the first part 201, which is an existing tunnel. The east end part of the tenth crosscut 410 is connected to the second drift 302, which is an existing tunnel. The east end part of the twelfth crosscut 412 is connected to the fourth drift 304, which is an existing tunnel. After the third part 203, the sixth crosscut 406, the eighth crosscut 408, the tenth crosscut 410, and the twelfth crosscut 412 are formed, the excavator 1 moves backward to the south end part of the third part 203.

[0065] After moving backward to the south end part of the third part 203, the excavator 1 sequentially excavates an unexcavated part Sm indicated by a dotted line. As the unexcavated part Sm is excavated, the grid-shaped tunnel 100 is formed. After the grid-shaped tunnel 100 is formed, the excavator 1 moves forward along an arrow S7 in FIG. 8 and withdraws from the grid-shaped tunnel 100.

[0066] [Effects] As described above, according to the embodiment, after the first part 201 and the second part 202 of the perimeter tunnel 200 are formed as existing tunnels, the excavator 1 excavates the bedrock so as to connect to the existing tunnels in order to form at least a part of the drift tunnel 300 and the crosscut tunnel 400. Since the procedure of the excavation work by the excavator 1 is determined such that a new tunnel is connected to an existing tunnel, a decrease in the workability in forming the grid-shaped tunnel 100 is suppressed. As described above, the process of adjusting the front end part of the excavator 1 is performed after a new tunnel is formed and before the excavator 1 is moved backward. In the embodiment, since the worker can approach the cutter head 7 from the first part 201 and smoothly perform the process of adjusting the front end part of the excavator 1, the workability of the work of adjusting the front end part of the excavator 1 is improved. Since the procedure of the excavation work by the excavator 1 is determined such that the number of places where the front end part of a new tunnel is connected to an existing tunnel increases, the workability in forming the grid-shaped tunnel 100 is suppressed. Also, according to the embodiment, since the work space is larger than when work is performed in a blind alley, the workability is improved.

[0067] FIG. 11 is a diagram schematically showing a state where a new tunnel (tunnel before reinforcement) is not connected to an existing tunnel. As described above, after a new tunnel is formed, the process of removing a peripheral edge component from the cutter body 9 is performed to move the excavator 1 backward. As shown in FIG. 11, when the new tunnel (tunnel before reinforcement) is not connected to the existing tunnel, that is, when the front end part of the new tunnel is a dead end (blind alley), it is difficult to remove the peripheral edge component from the cutter body 9. That is, if the front end part of the new tunnel is a dead end, the bedrock is present in front of and around the cutter head 7 and therefore it is difficult for the worker to approach the front end part of the excavator 1 or adjust the front end part of the excavator 1. If the front end part of the new tunnel is a dead end, the worker needs to perform work of removing the peripheral edge component from a position rearward of the cutter head 7 or work of removing the peripheral edge component after moving from a position rearward of the cutter head 7 to a position forward of the cutter head 7. When removing the peripheral edge component from a position rearward of the cutter head 7, workability decreases because the work space is insufficient. As shown in FIG. 11, when removing the peripheral edge component after moving from a position rearward of the cutter head 7 to a position forward of the cutter head 7, workability decreases because it is a blind alley and the lighting is insufficient. Also, since work for preventing the collapse of the front end part of the new tunnel is required, workability decreases. Also, the reinforcement work is performed by the worker on board the main beam 15. Therefore, it is difficult for the worker to perform the reinforcement work for the inner wall of the new tunnel (tunnel before reinforcement) located forward of the main beam 15. In the formation of the grid-shaped tunnel 100, when there are many places where the front end part of the new tunnel is a dead end (blind alley), the workability in forming the gridshaped tunnel 100 decreases.

[0068] In the embodiment, the procedure of the excavation work by the excavator 1 is determined such that a new tunnel is connected to an existing tunnel. That is, in forming the grid-shaped tunnel 100, the procedure of the excavation work by the excavator 1 is determined such that the number of places where the front end part of a new tunnel is connected to an existing tunnel increases and the number of places where a new tunnel has a dead end (blind alley) decreases. Since the number of places where the front end part of a new tunnel is connected to an existing tunnel increases, a decrease in the workability of tunnel excavation in forming the grid-shaped tunnel 100 is suppressed. According to the embodiment, as described with reference to FIGS. 8 and 9, the worker can approach the front end part of the excavator 1 from an existing tunnel or adjust the front end part of the excavator 1. The front end part of the excavator 1 is adjusted from an existing tunnel.

[0069] [Another Embodiment] FIG. 12 is a diagram illustrating a procedure for forming a grid-shaped tunnel according to another embodiment. As shown in FIG. 12, the excavator 1 may move forward while excavating as indicated by an arrow S1 to form a part of the grid-shaped tunnel 100, then move forward while excavating as indicated by an arrow S2 to form a part of the grid-shaped tunnel 100, and then move forward while excavating as indicated by arrows S3, S4, S5, and S6 to sequentially form a part of the grid-shaped tunnel 100. Also in the example illustrated in FIG. 12, since there are few places where the front end part of a new tunnel is a dead end (blind alley), a decrease in the workability in forming the grid-shaped tunnel 100 is suppressed. The worker can approach the front end part of the excavator 1 present in a new tunnel from an existing tunnel and adjust the front end part of the excavator 1.

[0070] In the above-described embodiment, the worker approaches the front end part of the excavator 1 present in a new tunnel from an existing tunnel and adjusts the front end part of the excavator 1. In the above-described embodiment, an adjustment robot may approach the front end part of the excavator 1 present in a new tunnel from an existing tunnel and adjust the front end part of the excavator 1.

[0071] In the above-described embodiment, the perimeter tunnel 200 is rectangular. The perimeter tunnel 200 need not be rectangular. The perimeter tunnel 200 may have five or more corners. The perimeter tunnel 200 may be, for example, elliptical. Reference Signs List

[0072] 1 excavator 2 front body section 3 rear body section 4 thrust jack 5 trailer section 6 front body 7 cutter head 8 front gripper 9 cutter body 10 disc cutter 11 outer plate 12 scraper 13 rear body 14 rear gripper 15 main beam 15A work space 16 backup trolley 17 rail 18 belt conveyor 20 work procedure generation device 31 reinforcement layer 32 reinforcement layer 50 transport vehicle 60 lighting device 61 electric cable 70 transport vehicle 100 grid-shaped tunnel 200 perimeter tunnel 201 first part 202 second part 203 third part 204 fourth part 300 drift tunnel 301 first drift 302 second drift 303 third drift 304 fourth drift 400 crosscut tunnel 401 first crosscut 402 second crosscut 403 third crosscut 404 fourth crosscut 405 fifth crosscut 406 sixth crosscut 407 seventh crosscut 408 eighth crosscut 409 ninth crosscut 410 tenth crosscut 411 eleventh crosscut 412 twelfth crosscut 500 mining area 1000 computer system 1001 processor 1002 main memory 1003 storage 1004 interface S1 arrow S2 arrow S3 arrow S4 arrow S5 arrow S6 arrow S7 arrow Sm unexcavated part Ta line Tb line

Claims

1. A tunnel excavation method for forming, by using an excavator, a grid-shaped tunnel including a perimeter tunnel, a drift tunnel provided on an inner side of the perimeter tunnel, and a crosscut tunnel provided so as to intersect the drift tunnel on the inner side of the perimeter tunnel, the tunnel excavation method comprising:excavating an excavation target with the excavator in a first direction and a second direction intersecting the first direction, to form a part of the perimeter tunnel; andexcavating the excavation target so as to reach an existing tunnel including the formed part of the perimeter tunnel, to form at least one of the drift tunnel and the crosscut tunnel.

2. The tunnel excavation method according to claim 1, further comprising:stopping the excavator after an end part of a new tunnel formed of the formed at least one of the drift tunnel and the crosscut tunnel is connected to the existing tunnel; andmoving the excavator backward along the new tunnel after a front end part of the excavator is adjusted from the existing tunnel.

3. The tunnel excavation method according to claim 2, whereinthe excavator includes a cutter head disposed at the front end part of the excavator, andthe adjusting the front end part of the excavator includes a process of reducing an outer diameter of the cutter head.

4. The tunnel excavation method according to claim 3, wherein the adjusting the front end part of the excavator includes a process of removing a component from the cutter head.

5. A tunnel excavation method for forming a grid-shaped tunnel using an excavator, the tunnel excavation method comprising:excavating an excavation target using the excavator such that a first tunnel is formed;excavating the excavation target such that a second tunnel to be connected to the first tunnel is formed, after the first tunnel is formed;stopping the excavator after an end part of the second tunnel is connected to the first tunnel;approaching a front end part of the excavator from the first tunnel and adjusting the front end part of the excavator, after stopping the excavator; andmoving the excavator backward along the second tunnel after the front end part of the excavator is adjusted.

6. The tunnel excavation method according to claim 5, whereinthe excavator includes a cutter head disposed at the front end part of the excavator, andthe adjusting the front end part of the excavator includes a process of reducing an outer diameter of the cutter head.

7. The tunnel excavation method according to claim 6, whereinthe adjusting the front end part of the excavator includes a process of removing a component from the cutterhead.

8. The tunnel excavation method according to claim 5, further comprising:forming a reinforcement layer on an inner wall of the second tunnel in a predetermined region including a front end part of the second tunnel after the excavator is moved backward along the second tunnel.

9. The tunnel excavation method according to claim 5, whereinin the adjusting the front end part of the excavator, the front end part of the excavator is illuminated by a lighting device disposed in the first tunnel.

10. The tunnel excavation method according to claim 5, whereinin the adjusting the front end part of the excavator, the front end part of the excavator is approached from the first tunnel and the front end part of the excavator is adjusted, and the front end part of the excavator is approached from a position rearward of the front end partof the excavator and the front end part of the excavator is adjusted.

11. The tunnel excavation method according to claim 5, whereinthe second tunnel is connected to the first tunnel from a lateral side of the first tunnel.

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