JP4167235B2 - Excavation method of horizontal shaft - Google Patents

Description

  The present invention relates to a method for excavating a horizontal shaft that can efficiently implement excavation of a horizontal shaft.

As a method for excavating a horizontal shaft in a natural ground composed of hard rock (rock having a compressive strength of 1000 to 4000 (kg / cm ² )), conventionally, there are blast excavation, mechanical excavation, and the like, in addition to the method using human power. However, excavation by human power is performed only when excavating a special horizontal shaft in a place where a large heavy machine does not enter because work efficiency is poor. On the other hand, excavation by blasting is suitable for large-scale excavation such as mountain tunnels, but from the viewpoint of safety and environmental problems, general horizontal shafts such as underground tunnels built in urban areas and the suburbs are used. Mechanical excavation is often used for excavation.
4 (a) and 4 (b) are diagrams showing an example of conventional mechanical excavation. After the support work 53 is constructed on the front ceiling portion 52 of the face surface 51a which is the excavation target part 51 of the horizontal shaft, the face surface is shown. A number of holes 54 having a predetermined depth are formed from 51 a in the direction of excavation, and steel pipes 55 are embedded in the holes 54. Then, a hydraulic wedge (not shown) is driven into the steel pipe 55 to cause cracks in the rock surrounding the steel pipe 55, and then the face is cut using a crusher such as a breaker or a rock drill 56 such as a call pick hammer (pick). The bedrock of the surface 51a is crushed. After that, the shot concrete is placed on the new face surface 51b advanced by this crushing, and a new support is built on the front ceiling portion 52A of the face face 51b to form a horizontal shaft (for example, , See Patent Document 1). The excavation target part 51 is an inner region of the natural ground 1 surrounded by the dotted line B in FIG. 4B, and the surface 2A of the excavation target part 51 is the ground surface of the natural ground 1 at the start of excavation. It is a surface set after the excavation progress, and it is the face. The face is the most advanced part of horizontal excavation.

On the other hand, as a method of crushing large rocks or the like, as shown in FIG. 5, a discharge hole 61 is formed in advance in the object to be destroyed 60, and an electrolytic solution 63 such as water is injected into the discharge hole 61 to perform this electrolysis. The discharge electrode 70 of the discharge crushing apparatus 50A is inserted into the liquid 63, and a high voltage of 8 kV to 20 kV is applied to the discharge electrode 70 to cause discharge. A shock wave is generated by this discharge energy, and the destruction object 60 is crushed by crushing the periphery of the discharge hole 61 with this shock wave. The discharge crushing device 50A is connected to a pulse power source 80 composed of a circuit having a capacitor 82 and switches 83 and 84 having a large capacity (for example, about 500 kJ) and one pole 82a of the capacitor 82 and A power supply unit 81 such as a generator connected to the other pole 82b via a switch 83, one electrode connected to one pole 82a of the capacitor 82, and the other pole 82b of the capacitor 82 via a switch 84 And the discharge electrode 70 formed of an insulator that insulates the one electrode from the other electrode. Although not shown, the circuit of the pulse power source 80 is grounded. The discharge electrode 70 is provided on, for example, a rod-shaped inner conductor 73 as one electrode such as a + electrode, a cylindrical insulator 74 that covers the outer periphery of the inner conductor 73, and the outer periphery of the insulator 74. It is constituted by an outer conductor 75 as the other electrode such as an electrode. That is, the discharge electrode 70 is a coaxial electrode having a configuration in which the inner conductor 73, the insulator 74, and the outer conductor 75 are coaxially arranged. The outer conductor 75 constitutes a plurality of floating electrodes 76; 76... Spaced apart in the direction along the center line of the inner conductor 73. The floating electrode is an electrode that is electrically insulated from the power supply side. A tip-side discharge gap 77 that generates discharge is formed between the tip portion 73t of the inner conductor 73 that protrudes and is exposed from the tip portion 74t of the insulator 74 and the tip portion 76t of the floating electrode 76 that is closest to the tip portion 73t. An intermediate discharge gap 78 for generating discharge is formed between the end portions 76s and the end portions 76s of the opposing floating electrodes 76. A plurality of intermediate discharge gaps 78 are formed. A discharge portion 79 is formed by the front end side discharge gap 77 and the plurality of intermediate side discharge gaps 78. After the discharge electrode 70 is inserted into the electrolytic solution 63 in the discharge hole 61 of the object to be destroyed 60 in a non-conductive state of the switch 84 and the switch 83, the switch 83 is turned on to connect the capacitor 82 to the capacitor 82 from the power supply unit 81. Accumulate the charge. Then, when the switch 84 is turned on and the electric charge stored in the capacitor 82 is applied to the discharge electrode 70 via the cable 71 and the connector 72, a discharge occurs in the front end side discharge gap 77, and a shock wave is generated by this discharge energy. . Similarly, discharge occurs in the plurality of intermediate discharge gaps 78, and shock waves are generated by the discharge energy. The destruction target 60 is crushed by these shock waves (see, for example, Patent Documents 2 and 3).
Japanese Patent Laid-Open No. 2000-136693 JP 2003-31175 A JP 2003-320268 A

However, the above hydraulic wedge cannot cause large cracks in the rock, so it takes time for excavation work by breakers and picks, as well as problems such as large noise due to impact and vibration due to crushing and excavation. There was a point.
Then, the method of excavating a horizontal shaft using the said electric discharge crushing method can be considered. That is, a plurality of discharge holes 61 are provided in the excavation target portion 51 of the horizontal shaft, and the discharge electrode 70 is inserted into the discharge hole 61 for discharge. It is conceivable to crush the bedrock.
However, the rocks of the excavation target part 51 of the horizontal shaft are different from independent block rocks such as excavated rocks and sandstones cut out from the site. As shown, even when a plurality of discharge holes 61 are formed in the excavation target part 51 and the discharge electrode 70 is inserted into the discharge hole 61 and discharged, the rock of the excavation target part 51 is cracked (cracked). ) Is difficult to generate, and it is difficult to crush the bedrock of the excavation target part 51. It is considered that the number of the discharge holes 61 is increased and the interval between the discharge holes 61 is reduced, so that the rock of the excavation target part 51 is likely to be cracked. In this case, it is necessary to provide a large number of discharge holes 61. In addition, the discharge work must be performed by providing the discharge electrodes 70 in the many discharge holes 61, and the number of discharge operations increases, so that the excavation of the horizontal shaft cannot be performed efficiently. There was a problem.
The present invention has been made in view of conventional problems, and an object of the present invention is to provide a method for efficiently excavating a horizontal shaft.

  The method of excavating a horizontal pit according to the present invention includes forming a free surface extending in the direction of excavation of the horizontal pit and a direction orthogonal to the direction of excavation in the excavation target portion of the horizontal pit, and discharging holes extending in the direction of excavation. Forming a discharge electrode in the discharge hole, generating a shock wave by discharge at the discharge part of the discharge electrode, and crushing the excavation target part between the discharge hole and the free surface with the shock wave It is characterized by excavating a horizontal shaft. A hole extending in the direction of excavation is formed in the excavation target part, and a free surface is formed by the inner surface of the hole, and a discharge hole is provided outside the free surface in the excavation target part to discharge in the discharge hole. In addition, a hole for forming a free surface was formed on the lower end side of the excavation target part, and a discharge hole was provided on a circular trajectory centering on the center of the hole forming the free surface in the excavation target part. In addition, the free surface is formed by the inner surface of the groove to divide the excavation target part or a part of the excavation target part by extending the excavation progress direction of the horizontal pit and the direction orthogonal to the excavation progress direction in the horizontal excavation target part. In addition, a discharge hole is provided in the region delimited by the groove to perform discharge in the discharge hole, or from discharge in the discharge hole located near the free surface, It is also characterized in that the extending direction is diagonally downward.

  According to the present invention, the free surface is formed in the excavation target portion of the horizontal shaft, and the excavation target portion between the discharge hole and the free surface is cracked by the shock wave generated by the discharge in the discharge hole. Therefore, the number of discharge holes and the discharge work can be reduced, and the excavation of the horizontal shaft can be performed efficiently. If the free surface is formed on the inner surface of the hole that forms the free surface (core hole), the free surface can be enlarged by increasing the diameter of the hole, and the free surface can be used effectively. Drilling can be done efficiently. Since the hole forming the free surface is formed on the lower end side of the excavation target portion, the horizontal shaft can be efficiently excavated from the lower end side of the excavation target portion. By disposing a plurality of discharge holes at a predetermined interval on a circular trajectory centered on the center of the hole in the excavation target part, the rock in the excavation target part on the outer peripheral side of the hole can be efficiently crushed. . Since the discharge is performed from the discharge hole located near the free surface, it is possible to cause many cracks in the rock in the excavation area between the free surface and the discharge hole. The rock in the excavation area between the drill holes can be easily crushed. A free surface is formed by the inner surface of the groove that divides the excavation target part or part of the excavation target part in a direction that is perpendicular to the excavation progress direction of the horizontal shaft and in the region delimited by the groove. By providing a discharge hole in the discharge hole and performing discharge in the discharge hole, the rock mass of the excavation target portion can be efficiently crushed in each region divided by the groove, and the horizontal shaft can be efficiently excavated. Since the direction of extension of the discharge hole is set obliquely downward, the work of sealing the periphery of the discharge hole so that the electrolyte does not flow out of the discharge hole can be omitted.

Hereinafter, the best mode of the present invention will be described with reference to FIGS. In addition, in each figure, the same or equivalent part as the prior art example of FIGS. 4-6 attaches | subjects the same code | symbol, and abbreviate | omits detailed description.
Best Mode
1 (a) and 1 (b) are diagrams showing a method for excavating a horizontal shaft according to the best mode 1. In this embodiment, first, the lower end side of the excavation target portion 51 of the horizontal shaft is excavated to perform centering. Hole 10 is formed. The centering hole 10 is formed so as to extend from the surface 2A of the horizontal excavation target portion 51 in the natural ground 1 in the horizontal excavation progressing direction X. The inner surface of the core hole 10 extends from the surface 2A of the excavation target portion 51 to the excavation target portion 51 of the horizontal shaft in the direction of the excavation progress X of the horizontal excavation and the direction perpendicular to the excavation progress direction X to form the free surface 3. To do. That is, the centering hole 10 is a hole that extends from the surface 2A of the excavation target portion 51 in the excavation progress direction X in the excavation target portion 51 and forms the free surface 3 on the inner surface. The discharge hole 11 formed by extending the core drilling hole 10 from the surface 2A of the drilling machine excavation target part 51 (not shown) in the excavation progress direction X is formed on the free surface 3 of the excavation target part 51 by the core drilling hole 10. On the outside, a plurality are provided at predetermined intervals on a circumferential locus (indicated by a one-dot chain line in FIGS. 1 and 2) centering on the center of the core hole 10. Further, the discharge hole 11 is formed to be inclined obliquely downward from the surface 2A side of the excavation target part 51 to the excavation progress direction X side. That is, the extending direction of the discharge hole 11 is set obliquely downward. Thus, the work of sealing the periphery of the entrance of the discharge hole 11 so that the electrolyte 63 does not flow out of the entrance of the discharge hole 11 can be omitted, so that the work can be simplified and the labor can be reduced. The core hole 10 and the discharge hole 11 are cut by a drilling machine not shown. For forming the centering hole 10, a drum drill having a diameter larger than that of the drill used for forming the discharge hole 11 is used. Further, after a plurality of small-diameter holes extending in the direction of excavation from the surface 2A of the excavation target portion 51 of the horizontal shaft are formed densely, discharge using the discharge electrode is performed in advance in these holes. 10 may be formed. 1 and 2, in the excavation target portion 51, a hole array composed of a plurality of discharge holes 11 arranged at a predetermined interval on a circumferential trajectory centered on the center of the core hole 10. Is shown as three rows of the first hole row 11A to the third hole row 11C. The number T of the hole rows, the distance L between the hole rows, the distance M between the discharge holes 11 and 11 adjacent to each other in one hole row, the discharge constituting the free surface 3 and the first hole row close to the free surface 3 For the shortest distance N between the working hole 11 and the like, a value obtained by an empirical rule such as an experiment is set according to the size of the cross section of the horizontal shaft and the hardness of the rock in the excavation target part 51. For example, the distance L between the hole arrays is 0.4 m to 0.5 m, and the distance M between the discharge holes 11 and 11 adjacent to each other in one hole array is 0.3 m to 0.8 m.

  The discharge operation is performed from the discharge hole 11 located near the free surface 3 formed by the inner surface of the core hole 10. For example, the electrolytic solution 63 such as water and the discharge electrode 70 are provided in the lowermost discharge hole 11 a in the first hole row 11 A composed of the discharge holes 11 closest to the core hole 10. That is, after the electrolytic solution 63 is injected into the discharge hole 11a, the discharge portion 79 of the discharge electrode 70 is inserted and the discharge portion 79 is immersed in the electrolytic solution 63, and the pulse power source 80 is applied to the discharge electrode 70. A high voltage of 8 kV to 20 kV is applied. After the discharge portion 79 of the discharge electrode 70 is inserted into the discharge hole 11a, the electrolytic solution 63 is injected into the discharge hole 11a, and the discharge portion 79 is immersed in the electrolytic solution 63. A high voltage of 8 kV to 20 kV from the pulse power source 80 may be applied. As a result, a discharge is generated in the discharge part 79 of the discharge electrode 70, a shock wave is generated by this discharge energy, and the excavation target part 51 is destroyed by the shock wave. At this time, it is preferable that the holder 21 is attached to the outer periphery of the connector 72 of the discharge electrode 70 and the holder 21 is supported by the small dedicated gripping device 22. If the pulse power source 80 to which the coaxial cable of the discharge electrode 70 is connected is mounted on the rear part of the loading platform of the small dedicated gripping device 22, it is convenient because the cable line does not need to be extended.

  In this embodiment, the free surface 3 is formed by the inner surface of the core hole 10 that is in contact with the space in the core hole 10, and the bedrock of the excavation target portion 51 is formed by the core hole 10 as a hole forming the free surface 3. Is cut off. Therefore, since the rock between the discharge hole 11a and the free surface 3 is easily moved to the side where the core hole 10 is not constrained by the rock, the rock between the discharge hole 11a and the free surface 3 is caused by the shock wave. Cracks (cracks) are likely to occur, and further, cracks are likely to occur in the rock between the discharge hole 11a and the free surface 3 due to the tensile force associated with the shock wave being reflected by the free surface 3 and returning. From the above, the bedrock between the discharge hole 11a and the free surface 3 is crushed by cracking, or the cracked portion is crushed using a rock drill such as a small breaker, so that the horizontal shaft can be efficiently You can excavate. On the other hand, when the free surface 3 is not formed, the shock wave gradually attenuates in the process of spreading from the periphery of the discharge hole 11 to the outside, so that the rock cannot be efficiently crushed by the shock wave.

When the discharge in the discharge hole 11a is completed, the electrolytic solution 63 and the discharge electrode 70 are provided in the discharge hole 11b of the first hole row 11A adjacent to the discharge hole 11a as described above, and the pulse power source When 80 capacitors 82 (for example, about 500 kJ) are filled, discharge in the discharge hole 11b is performed. As described above, the discharge holes 11 constituting the first hole array 11A arranged on the circumferential trajectory are discharged from the discharge holes 11a in order from the discharge hole 11a. 11 and finally discharging by the discharge holes 11m, the rock between the core hole 10 and the first hole row 11A is crushed as shown in FIG. 2 (a). At the same time, cracks (cracks) also occur in the rock on the outer peripheral side of the first hole row 11A, so that the bedrock between the first hole row 11A and the second hole row 11B indicated by circle 1 in FIG. Can be excavated by using a rock drill such as a small breaker to excavate a lateral hole 10A having an enlarged peripheral edge of the cored hole 10, as shown in FIG. Next, similarly to the case of the first hole row 11A, the discharge holes 11 of the second hole row 11B located on the outer peripheral portion of the lateral hole 10A are used in order from the lowermost discharge hole 11n. Let the discharge occur. Also in this case, since the inner surface of the horizontal hole 10A becomes the free surface 3, the rock on the side of the horizontal hole 10A of the discharge hole 11 can be efficiently crushed and the rock around the second hole row 11B is large. Cracks can be generated. Therefore, the rock mass between the horizontal hole 10A and the third hole row 11C indicated by the circle 2 in FIG. 2B can be crushed, and the horizontal hole 10B having an enlarged peripheral edge of the horizontal hole 10A is easily excavated. be able to.
Finally, the third hole row 11C located on the outer peripheral portion of the horizontal hole 10B is also discharged in the discharge hole 11 in the same manner as the first and second hole rows 11A and 11B. The rock can be excavated between the horizontal hole 10B indicated by the circle 3 in 2 (b) and the peripheral edge of the horizontal shaft indicated by the dotted line B in FIG. 2 (b).

  Thereafter, the core hole 10 and the discharge hole 11 that form the free surface 3 are formed on the face surface that becomes the surface 2A of the excavation target portion 51 after the excavation progresses, and the crushing operation by the shock wave is performed. Thus, excavation of the horizontal shaft can be performed efficiently.

  According to the present embodiment, the cored hole 10 that is a hole extending in the excavation traveling direction X is formed in the excavation target part 51, and the free surface 3 is configured by the inner surface of the cored hole 10 and the excavation target part 51 By providing discharge holes 11 outside the free surface 3 and performing discharge in the discharge holes 11, the number of discharge holes 11 can be reduced compared to the case where the free surface 3 is not provided, and the number of discharge operations can be reduced. Can be reduced, and the horizontal excavation can be performed efficiently. Since the free surface 3 is formed on the inner surface of the centering hole 10, the free surface 3 can be enlarged by increasing the diameter of the centering hole, and the free surface 3 can be used effectively. Can be done efficiently. Further, since the centering hole 10 is formed on the lower end side of the excavation target portion 51, the diameter of the hole forming the free surface 3 on the inner surface is increased from the lower end side of the excavation target portion 51 like the horizontal holes 10A and 10B. Therefore, the horizontal shaft can be efficiently excavated from the lower end side of the excavation target portion 51. Further, by arranging a plurality of discharge holes 11 at a predetermined interval on a circumferential locus centering on the center of the core hole 10 in the excavation target portion 51, excavation on the outer peripheral side of the core hole 10 is performed. The bedrock of the target part 51 can be efficiently crushed. Further, since the discharge is performed from the discharge hole 11 located near the free surface 3, many cracks are generated in the rock of the excavation target part 51 between the free surface 3 and the discharge hole 11. Thus, the bedrock of the excavation target portion 51 between the free surface 3 and the discharge hole 11 can be easily crushed. Further, since the centering hole 10 is formed on the lower end side of the excavation target portion 51, the diameter of the hole forming the free surface 3 on the inner surface is increased from the lower end side of the excavation target portion 51 like the horizontal holes 10A and 10B. Therefore, the horizontal shaft can be efficiently excavated from the lower end side of the excavation target portion 51. Further, by arranging a plurality of discharge holes 11 at a predetermined interval on a circumferential locus centering on the center of the core hole 10 in the excavation target portion 51, excavation on the outer peripheral side of the core hole 10 is performed. The bedrock of the target part 51 can be efficiently crushed. Further, since the discharge is performed from the discharge hole 11 located near the free surface 3, many cracks are generated in the rock of the excavation target part 51 between the free surface 3 and the discharge hole 11. Thus, the bedrock of the excavation target portion 51 between the free surface 3 and the discharge hole 11 can be easily crushed. Further, by disposing the electrolytic solution 63 and the discharge electrode 70 in the discharge hole 11 and performing discharge, the destructive force is increased by the pressure due to partial evaporation of the electrolytic solution 63, and further, excavation by the electrolytic solution 63 is performed. The propagation efficiency of the shock wave to the target part 51 can be increased.

In addition, the formation location of the core hole 10 is not limited to the lower end side of the excavation target portion 51, and may be provided in other locations such as the central portion of the excavation target portion 51. In addition, when the rock mass of the excavation target portion 51 has a strength distribution, if a portion having a relatively low strength is excavated to form the core hole 10, and a portion having a high strength is crushed by electric discharge crushing, A horizontal pit can be excavated efficiently.
Moreover, in the above, the cross-sectional shape of the core hole 10 is circular, and the discharge hole 11 is arranged on a circumferential trajectory centered on the center of the core hole 10. As for the arrangement method of the discharge holes 11 including the interval between the two discharge holes 11, 11, and the discharge order, etc., an empirical rule is to know the shape of the horizontal shaft and the strength distribution of the rock in the excavation target part 51. As appropriate.
Further, the method for supporting the discharge electrode 70 and the installation position of the pulse power source 80 are not limited to the above example, and may be appropriately devised according to the situation at the site.
In actual work, in order to efficiently perform the crushing work, a plurality of holes that can become discharge holes are drilled in advance, and the following of the above holes are selected according to the crushing situation. The discharge electrode 70 is inserted into a hole suitable for crushing so as to crush the discharge.

Best Mode 2
In the best mode 1, the centering hole 10 is formed, and the free surface 3 is formed by the inner surface of the centering hole 10. However, as shown in FIG. The free surface 3 is formed by the inner surface of the groove 30 that extends in a direction orthogonal to the digging target portion 51 or a part of the digging target portion 51, and in a plurality of regions R1 to R8 that are partitioned by the groove 30 By disposing the discharge hole 11 in the discharge hole 11 and performing discharge in the discharge hole 11, the rock mass may be crushed for each region R1 to R8 to dig a horizontal shaft. The groove 30 may be formed, for example, by a continuous hole in which a plurality of holes extending in the excavation progress direction X from the surface 2A are connected to each other in a direction orthogonal to the excavation progress direction X in the horizontal mine excavation target portion 51. The groove 30 that divides the excavation target part 51 is a groove that is formed along the peripheral edge of the horizontal shaft in the excavation target part 51 shown by B in FIG. 3 and extends in the excavation progress direction X to divide the entire excavation target part 51. . The grooves 30 that delimit a part of the excavation target part 51 extend in the excavation progress direction X in the excavation target part 51 and extend in a direction orthogonal to the excavation progress direction X to delimit each region R1 to R8 in FIG. It is a groove.
In the present embodiment, the rock is cut between the plurality of regions R1 to R8 of the excavation target part 51 by the groove 30. Therefore, since the rock between the discharge hole 11 and the free surface 3 is easily moved to the side where the groove 30 is not constrained by the rock, the rock between the discharge hole 11 and the free surface 3 is cracked by the shock wave. (Cracks) are likely to occur, and further, cracks are likely to occur in the rock between the discharge hole 11 and the free surface 3 due to the tensile force associated with the shock wave being reflected and returned by the free surface 3. Since the rock between the discharge hole 11 and the free surface 3 can be efficiently crushed, the plurality of regions R1 to R8 of the excavation target part 51 can be efficiently crushed for each region, and the horizontal shaft can be efficiently excavated. .
In addition, about the division method of the area | region of the excavation object part 51 by the groove | channel 30, and the arrangement | positioning method of the discharge hole 11 provided in each area | region divided by the groove | channel 30, it is not restricted to what was shown in the said FIG. What is necessary is just to determine suitably with the shape of a horizontal shaft, the strength distribution of the rock of the excavation object part 51, etc.

  A plurality of holes such as a cored hole 10 extending in the excavation progress direction of the horizontal shaft and forming a free surface on the inner surface are provided in the excavation target portion 51, and the plural holes are predetermined in a direction orthogonal to the excavation progress direction X. Since the free surface can be increased if the distance is provided, the lateral resistance can be excavated efficiently. The discharge electrode may be a discharge electrode in which a discharge gap is formed as a discharge portion. For example, a discharge electrode in which a discharge gap is formed by cutting a wire (wire), or other forms of discharge An electrode can be used. In addition, if a discharge electrode having a configuration in which a cartridge surrounding the discharge portion of the discharge electrode is provided and the cartridge is filled with the electrolyte and the discharge portion is immersed in the electrolyte can be used, the discharge hole 11 can be used. It is possible to prevent leakage of the electrolyte from the battery. Both the groove 30 separating the cored hole 10 and the excavation target part 51, both the groove 30 separating part of the hole 10 and the excavation target part 51, and the groove 30 and excavation target part separating the cored hole 10 and the excavation target part 51 from each other. You may make it provide all the grooves 30 which divide a part of 51, If it does in this way, the free surface 3 can be increased and a rock mass can be crushed more efficiently.

It is a figure which shows the excavation method of the horizontal shaft which concerns on the best form 1 of this invention. It is a figure which shows an example of the crushing method of the face rock according to this best form 1. It is a figure which shows the excavation method of the horizontal shaft which concerns on this best form 2. It is a figure which shows the conventional excavation method of a horizontal shaft. It is a figure which shows the crushing method of the rock by the crushing apparatus using the electrode for discharge. It is a figure which shows the crushing state of the rock mass by the crushing apparatus using the electrode for discharge.

Explanation of symbols

3 free surface, 10 centering hole (hole), 11 discharge hole, 30 groove, 51 excavation target part,
70 Electrode for discharge, 79 Discharge part, X Excavation direction.

Claims (7)

  A free surface extending in the direction of the horizontal digging and in a direction perpendicular to the direction of the digging is formed in the excavation target portion of the horizontal pit and a discharge hole extending in the direction of the digging is formed, and the discharge is discharged in the discharge hole. A shock wave is generated by the discharge at the discharge portion of the discharge electrode, and the excavation target portion between the discharge hole and the free surface is crushed by the shock wave to excavate the horizontal shaft. Excavation method of horizontal shaft.   A hole extending in the direction of excavation is formed in the excavation target part, and a free surface is formed by the inner surface of the hole, and a discharge hole is provided outside the free surface in the excavation target part to discharge in the discharge hole. The method for excavating a horizontal shaft according to claim 1.   The method for excavating a horizontal shaft according to claim 2, wherein a hole forming a free surface is formed on a lower end side of the excavation target portion.   4. The excavation of a horizontal pit according to claim 2, wherein a discharge hole is provided on a circumferential locus centering on the center of the hole forming the free surface in the excavation target portion. Method.   In the excavation target portion of the horizontal shaft, a free surface is formed by the inner surface of the groove that divides the excavation target portion or a part of the excavation target portion by extending in the direction of the horizontal excavation and the direction perpendicular to the excavation progress direction. 2. The method for excavating a horizontal shaft according to claim 1, wherein a discharge hole is provided in a region divided by the groove and discharge is performed in the discharge hole.   The method for excavating a horizontal shaft according to any one of claims 1 to 5, wherein the excavation is performed from a discharge in a discharge hole located at a position close to a free surface.   The method for excavating a horizontal shaft according to any one of claims 1 to 6, wherein an extending direction of the discharge hole is obliquely downward.

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