JP2005023749A5 - - Google Patents

Description

Elimination method of shaft bending in multi-axis drilling

  The present invention relates to a method for eliminating shaft bending in multi-axis excavation.

The Construction of the underground pillar column type continuous wall, traditional, wrap the construction stage method has been widely used. And the wrap construction stage method using a drilling device, to form a hole in sequential rows while overlapping the side end portions to the subject ground, therein, the solidifying material and soil, such as cement milk A continuous wall composed of a column of columns is formed in the ground by filling the mixture and inserting a core material into the mixture as necessary. However, this conventional wrap construction stage method, the overlap is incomplete by hole bending or the like, water leakage from the incomplete point there is a problem that occurs.

Therefore, currently, lap facilities Engineering using multi-axis drilling device as the drilling apparatus is widely used.
An example of the multi-axis excavator used here is shown in FIG.
That is, a reader cradle (not shown) of the base machine 2 and a reader (not shown) supported by the backstay 5, a rotary drive source 7 that can be raised and lowered along the reader, and a multi-axis speed reducer on the rotary drive source 7. .. Mainly connected through 8. The multi-axes 6, 6 ... are composed of a plurality of excavation shafts 6, 6 ... arranged in parallel, and the adjacent excavation shafts 6 rotate in opposite directions. Further, the multi-axes 6, 6... Are each provided with a drilling member 6b at the lower end portion thereof, and a stirring member 6a above it, and the rotation trajectories of the drilling members 6b, 6b. Are arranged in parallel. Therefore, when the wrap construction stage with such multi-axis drilling device 1, since the side cross plurality of holes to reliably overlap, the occurrence of leakage can be prevented as much as possible.

However, even by lap facilities Engineering using multi-axis drilling apparatus 1, prior to the hole group H comprising a plurality of holes drilled in, then may overlap with drilled hole group H may be incomplete, The occurrence of water leakage is not completely prevented.

There are mainly two reasons why the overlap between the hole groups H is incomplete.
That is, when multi-axis excavation is performed, the lower end position of the multi-axes 6, 6... Is rotated in a plan view with respect to the upper end position due to the state of the ground (the excavation axes 6, 6... Are twisted). ) May occur (hereinafter, this state is also simply referred to as a twisted state). In this case, as shown in FIG. 2A, the hole group H has its lower end (current excavation position) rotated in plan view with respect to the planned excavation position indicated by a broken line (FIG. 2A). In this case, it is formed at a position rotated clockwise on the paper surface, and this causes incomplete overlap of the hole groups H (Cause 1).

  Further, when multi-axis excavation is performed, depending on the ground condition or the like, an axial bend is generated in which the lower end position of the multi-axis 6, 6... Is shifted to one of the alignment directions in plan view with respect to the upper end position. There is a case (hereinafter, this state is also simply referred to as a lateral shift state). In this case, as shown in FIG. 2B, the hole group H has one lower end (current excavation position) in the direction in which the hole group H is aligned with respect to the planned excavation position indicated by the broken line (on the right side of the page). ), Which causes incomplete overlap between the hole groups H (Cause 2).

  Therefore, at present, when the hole group H is sequentially excavated, the subsequent hole group H is excavated so that the side end hole of the subsequent hole group H completely overlaps the side end hole of the hole group H previously excavated. Is going. That is, the excavation shaft 6 arranged at the side end in the multi-axis 6, 6... Is inserted into the side end hole of the preceding hole group H to excavate the subsequent hole group H.

  In general, as shown in FIG. 3, the hole group (1) is first excavated, and then the hole group (2) is excavated by flying one span, and then the hole group (1) and the hole are excavated. The excavation shafts 6 and 6 arranged on both side ends are inserted into the side end holes (1-1) and (2-1) of the group (2), respectively, and they are used as guide paths to Do excavation. The hole group (1) and the hole group (2) correspond to the preceding hole group, and the hole group (3) between them corresponds to the subsequent hole group. Further, excavation may be performed in the order of hole group (1), hole group (3), and hole group (2). Furthermore, excavation may be performed using a multi-axis excavator provided with a dedicated guide body that does not have an excavation function without using the excavation shaft disposed at the side end as a guide body (see, for example, Patent Document 1). .

  By excavating as described above, the hole groups are surely overlapped with each other, and therefore, the purpose of creating a completely continuous column is achieved.

However, in the above method, since at least one of the drilling shafts is inserted into the leading hole to form a guide body, the number of drilling holes increases less than the number of drilling shafts, and the drilling efficiency is poor. Have Therefore, in recent years, it has been demanded to improve the drilling accuracy itself of multi-axis excavation so that a completely continuous column array can be created without using such a method.
Japanese Patent No. 2809559

  Therefore, a main problem of the present invention is a method that can eliminate shaft bending in multi-axis excavation, more specifically, the above-described “twisted state” and “lateral slip state” can be solved relatively easily. It is to provide a method.

The present invention that has solved the above problems is as follows.
<Invention of Claim 1>
By inserting a multi-axis consisting of a plurality of excavating shafts arranged in parallel and rotating adjacent to each other in opposite directions into the ground with each excavating shaft rotating forward, During multi-axis drilling,
When the lower end position of the multi-axis has been bent in a state rotated in a plan view with respect to the upper end position, this is a method for eliminating this bending.
After stopping the insertion of the multi-axis,
In the state where each of the excavation shafts is reversed and in the state where the excavation diameter of the excavation shafts arranged on both side ends is enlarged, the multi-axis is pulled up,
Next, the multi-axis is inserted again to the stop position in a state where each of the excavation shafts is reversed and the excavation diameter of the enlarged excavation shaft is returned to the original size. A method for eliminating shaft bending in multi-axis excavation, which is a feature.

<Invention of Claim 2>
By inserting a multi-axis consisting of a plurality of excavating shafts arranged in parallel and rotating adjacent to each other in opposite directions into the ground with each excavating shaft rotating forward, During multi-axis drilling,
In the case where an axial bend occurs in which the lower end position of the multi-axis is shifted to one of the alignment directions in a plan view with respect to the upper end position, a method of eliminating the bend of the axis,
After stopping the insertion of the multi-axis,
In the state where each of the excavation shafts is reversed and at least the excavation diameter of the excavation shaft disposed on the side end opposite to the shift direction is enlarged, the multi-axis is pulled up,
Next, the multi-axis is inserted again to the stop position in a state where each of the excavation shafts rotates forward and an excavation diameter of the expanded excavation shaft is enlarged. A method to eliminate shaft bending in multi-axis drilling.

  According to the method of the present invention, it is possible to easily eliminate shaft bending in multi-axis excavation.

[Multi-axis drilling equipment]
The method according to the present invention is employed for multi-axis excavation.
A specific apparatus for performing multi-axis excavation is sufficient if it is provided with a multi-axis "consisting of a plurality of excavation axes arranged in parallel and rotating adjacent excavation axes in opposite directions" The remaining configuration is not particularly limited. For example, the multi-axis excavator 1 shown in FIG. 1 described above can be used. Also in the present embodiment, a case where such a multi-axis excavator 1 is used will be described.

  First, the multi-axis excavator 1 will be described in more detail. In the following description, the excavation shafts 6, 6... Are also expressed as the excavation shaft 6A when they are arranged at both ends, and as the excavation shaft 6B when they are arranged at the center.

  As described above, the multi-axis excavator 1 includes a multi-axis (6A and 6B) including a plurality of excavation axes 6A, 6B,. The number of excavation shafts 6 is not particularly limited. For example, as in the present embodiment, there may be three (shafts) or a plurality of two, four, five, or more.

  The plurality of excavating shafts 6A, 6B,... Are supported so as to be movable up and down using the steadying device 9 as a guide while the steadying device 9 fixed to the leader is steady. Further, the plurality of excavation shafts 6A, 6B... Are connected at appropriate positions by connecting members 10 that hold the excavation shafts 6A, 6B. This connection is performed because the plurality of excavation shafts 6A, 6B,... Tend to increase the distance between them as the depth increases.

  As shown in FIG. 4, excavation members 6b, 6b... Are provided at the lower ends of the excavation shafts 6A, 6B. In this embodiment, the excavation members 6b, 6b... Are adjacent to each other up and down, and in this embodiment, the central excavation member 6b is displaced upward from the excavation members 6b, 6b at both ends, and the rotation trajectories are in plan view. Some overlap.

  The excavation members 6b, 6b, as shown in FIGS. 7, 12, and 14, are each two spiral stirring blades 21, 21 attached around the excavation shafts 6A, 6B, The excavation bits 22, 22 ... attached to the lower end sides of the stirring blades 21, 21 ..., and the enlarged blade mechanisms 30 (40, 50, 60), 30 attached to the stirring blades 21, 21, ... respectively. (40, 50, 60) ... and so on.

  The stirring blades 21, 21... Spiral in the same direction as the rotation direction of the corresponding excavation shafts 6A, 6B. In the present embodiment, as shown in FIG. 4, the stirring blades 21 and 21 attached to the excavation shafts 6A and 6A at both ends are stirred in the clockwise direction as viewed from above and attached to the central excavation shaft 6B. The blades 21 and 21 spiral in a counterclockwise direction when viewed from above. The stirring blades 21, 21, and the like thus formed have an action of stirring the excavated earth and sand excavated by the excavating bits 22, 22.

  The enlarged blade mechanisms 30, 30... Are for enlarging the excavation diameter of the excavation shafts 6A, 6B. The structure of the magnifying blade mechanisms 30, 30... Will be described after the method for eliminating the shaft bending is described.

[How to eliminate shaft bending (when twisted)]
Next, FIG. 5 shows a method for eliminating the axial bending when the axial bending occurs in which the lower end position of the multi-axis (6A and 6B) is rotated in a plan view with respect to the upper end position. The description will be given with reference.

First, the ground excavation method until the shaft bending occurs is the same as the normal excavation method.
That is, as shown in (1) of FIG. 5, the ground G is excavated by inserting the multi-axis (6A and 6B) into the ground with the respective excavating shafts 6A, 6B. Here, normal rotation means that when excavating the ground, the excavation axis rotates in the originally planned direction (the direction planned for effectively excavating the ground). In this embodiment, the excavation shafts 6A and 6A at both ends rotate in the clockwise direction when viewed from above, and the central excavation shaft 6B rotates in the counterclockwise direction when viewed from above. Means.

  When the excavation work is continued in this way, as shown in FIG. 5 (2), when the shaft is "twisted", the multi-axis (6A and 6B) insertion work is stopped first. (When the insertion operation is stopped, the place (depth) where the lower end portions of the multi-axes (6A and 6B) are located is referred to as a stop position.)

  The confirmation of the twisted state can be performed, for example, by measurement with an inclinometer or the like. However, the insertion work can be stopped based on, for example, insertion up to a predetermined depth or the passage of a predetermined time.

  When the insertion operation is stopped, next, as shown in FIG. 5 (3), the excavation diameters of the excavation shafts 6A, 6A arranged on both side ends are increased while the excavation shafts 6A, 6B,. In the converted state, the multi-axis (6A and 6B) is pulled up. In addition, the hatching part in a figure is the ground G newly excavated by expansion of an excavation diameter. Further, in this embodiment, the reversal in this case means that the excavation shafts 6A, 6A arranged at both ends are rotated counterclockwise when viewed from above, and the excavation shaft arranged at the center. About 6B, it means rotating in the clockwise direction.

  The lifting of the multi-axes (6A and 6B) is performed in a state in which the excavating diameters of the excavating shafts 6A, 6A arranged at both ends are enlarged, when the excavating shafts 6A, 6B,. In contrast to (6A and 6B), a twisting action in a direction opposite to the twisting direction occurs upon insertion, and the twisted state is quickly eliminated by increasing the excavating diameter and increasing the resistance action from the ground G. Because.

  How much the multi-axis (6A and 6B) is pulled up is not particularly limited. For example, the twisted state is measured with an inclinometer or the like, and the lifted distance becomes a predetermined length until the twisted state is eliminated. Until a predetermined time elapses.

  When the multi-axes (6A and 6B) are pulled up in this way, next, as shown in (4) of FIG. 5, the excavation shafts 6A, 6B,. With the excavating diameters of the shafts 6A and 6A returned to their original sizes, the multi-axes (6A and 6B) are inserted again to the previous stop position. The reason why the re-insertion is performed in a state where the excavation shafts 6A, 6B,... Are rotated in reverse is to prevent the twisted state from being turned again. Further, the reason why the expanded excavation shafts 6A and 6A are returned to their original excavation diameters is to prevent the ground from being loosened due to excessive excavation and easily causing shaft misalignment. .

  After the twisted state is resolved, the insertion excavation work can be continued. This operation is performed in a state where the excavation shafts 6A, 6B,. When the twisted state of the multi-axis (6A and 6B) occurs while the insertion excavation work is continued, the canceling operation described above is performed again to cancel the twisted state. After that, depending on the state of deviation, the insertion excavation work / twist elimination work can be sequentially repeated in accordance with the lateral deviation elimination work described later, instead of the twist elimination work.

[How to eliminate axis bending (in the case of lateral displacement)]
Next, when an axial bending occurs in which the lower end position of the multi-axis (6A and 6B) is shifted to one side of the alignment direction in plan view with respect to the upper end position, a method of eliminating the axial bending Will be described with reference to FIG.

  First, the ground excavation method until the shaft bending occurs is the same as the normal excavation method. Since this method is the same as that in the “twisted state” described above, description thereof is omitted. In addition, (1) of FIG. 6 is a corresponding explanatory drawing.

  When the excavation work is continued, as shown in FIG. 6 (2), when the shaft is in a “laterally shifted state”, the multi-axis (6A and 6B) insertion work is first stopped (insertion work). The position (depth) at which the lower end of the multi-axis (6A and 6B) is located is referred to as a stop position.

  Confirmation of the lateral displacement state can be performed, for example, by measurement using an inclinometer or the like. However, the insertion work can be stopped based on, for example, insertion up to a predetermined depth or the passage of a predetermined time.

  When the insertion work is stopped, next, as shown in FIG. 6 (3), the excavation shafts 6A, 6B,... In the state where the excavation diameter of the excavation shaft 6A disposed at the side end of the shaft is enlarged, the multi-axis (6A and 6B) is pulled up.

  The multi-axis (6A and 6B) is pulled up with the excavating diameter of the excavating shaft 6A arranged at the side end opposite to the deviation direction enlarged, so that the opposite side of the deviation direction is excavated to the design line. This is to eliminate the problem. On the other hand, the excavation diameter of the excavation shaft 6A arranged at the side end on the shift direction side may be in an enlarged state or in an unexpanded state. However, from the viewpoint of preventing excessive excavation, it is preferable that the state is not enlarged. Further, the reason why the excavation shafts 6A, 6B,... Are reversed is to prevent the lateral displacement state from increasing.

  The extent to which the multi-axis (6A and 6B) is pulled up is not particularly limited. For example, the lateral shift state is measured by an inclinometer or the like, and the lift distance becomes a predetermined length until the lateral shift state is eliminated. Until a predetermined time elapses.

  After the multi-axes (6A and 6B) are pulled up by a predetermined length in this way, then, as shown in (4) of FIG. 6, the excavation shafts 6A, 6B,. With the excavating diameter of the shaft 6A still enlarged, the multi-axis (6A and 6B) is inserted again to the stop position. The re-insertion is performed in a state where each of the excavation shafts 6A, 6B,... Rotates forward and the excavation diameter of the expanded excavation shaft 6A is expanded. This is to realize.

  After the lateral slip state is resolved, the insertion excavation work can be continued. In this operation, as shown in FIG. 6 (5), the excavation shafts 6A, 6B,... Are rotated forward and the excavation diameter of the expanded excavation shaft 6A is returned to the original size. To do. If the multi-axis (6A and 6B) lateral shift state occurs during the insertion excavation operation, the above-described elimination work is performed again to eliminate the lateral shift state. After that, depending on the state of deviation, the insertion excavation work / lateral deviation elimination work can be sequentially repeated in place of the lateral deviation elimination work.

(Enlarged blade mechanism)
Next, the structure of the enlarged blade mechanisms 30, 30 ... will be described.
The structure of the enlarged blade mechanisms 30, 30... Is not particularly limited as long as it can expand the excavating diameter of the excavating shaft. However, in the method of the present invention, it is recommended to use the enlarged blade mechanism 40, 50 or 60 shown as the first to third embodiments below.

(First form)
First, a 1st form is shown to FIGS.
As shown in FIG. 7, the enlarged blade mechanism 40 in this form mainly includes a control main body 41 and an enlarged claw 42 provided on the bottom surface thereof.

  As shown in FIG. 10, the enlarged claw 42 has a proximal end portion connected to a distal end portion of the fulcrum pin 43. The fulcrum pin 43 is pivotable about the vertical direction, and is housed in the control body 41 with the tip projecting from the bottom surface of the control body 41. Further, the fulcrum pin 43 is connected to the lever 44 in a state where the base end portion of the lever 44 penetrates in the vertical direction. Therefore, the expansion claw 42 rotates around the fulcrum pin 43 integrally with the lever 44 around the base end portion.

  The rotation of the expansion pawl 42 is not particularly performed by the driving force from the driving source. As shown in FIG. 11A, when the excavation shaft 6 is reversed (rotates clockwise in the drawing), a force in the counterclockwise direction from the ground G is applied to the expansion claw 42 as indicated by the long dotted line. Thereby, the expansion pawl 42 protrudes outward, and the rotation trajectory is expanded. The reason why the expansion claw 42 is fixed in this state, that is, in a state where it is rotated by about 90 degrees, is that the lever 44 collides with the inner wall surface of the control main body 41 and further rotation is suppressed (see FIG. 9). On the other hand, as shown in FIG. 11B, when the excavation shaft 6 rotates in the forward direction (rotates counterclockwise on the paper surface), the force in the clockwise direction from the ground G to the expansion claw 42 as shown by the long dotted line. It takes. Thereby, the expansion claw 42 is stored in a normal rotation locus.

  As described above, the expansion pawl 42 of the present embodiment protrudes when the excavation shaft 6 reverses and returns to the original state when the excavation shaft 6 rotates forward. At the time of work, the excavation diameter is automatically enlarged as the excavation shaft 6 is reversed, and the object can be achieved very easily.

However, during the lifting operation in “elimination of the state of lateral displacement”, there is a case where the excavation diameter at one end is not enlarged. However, the enlarged blade mechanism 40 of the present embodiment can cope with this.
That is, as shown in FIGS. 9 and 10, a hole 44a penetrating in the vertical direction is formed at the tip of the lever 44 that rotates integrally with the enlarged claw 42. The hole 44a moves vertically in the hole 44a. One end portion of the lock pin 45 which can be passed is passed through. Therefore, as shown in FIG. 10, if the lock pin 45 is passed through the hole 44a, the rotation of the lever 44 is prevented, and the enlargement of the enlargement claw 42 is prevented. In this embodiment, the lock pin 45 is moved up and down by the DC solenoid 46 connected via the connecting member 47, but the present invention is not limited to this. For example, the lock pin 45 can be moved up and down using a cylinder mechanism.

The function of preventing the rotation of the expansion pawl 42 of the lock bin 45 can also be used for re-insertion (see (4) in FIG. 5) in the above-described “removal of twisted state”.
That is, at the end of the lifting operation of the plurality of excavating shafts 6A, 6B..., Once the plural excavating shafts 6A, 6B. The re-insertion is performed while reversing the excavation shafts 6A, 6B.

(Second form)
Next, a second form is shown in FIGS.
As shown in FIG. 13, the enlarged blade mechanism 50 of this embodiment has a box 51, an enlarged claw 52 that can be stored in the box 51, and the enlarged claw 52 protruding outward from the box 51, or The main components are the hydraulic cylinder 53 for storage in the box 51.

  According to this embodiment, when enlarging the excavation shaft, the expansion claw 52 is protruded outward from the box 51 by the hydraulic cylinder 53, and when returning to the original position, the expansion claw 52 is moved inside the box 51 by the hydraulic cylinder 53. It ’s enough to fit in. Therefore, according to this embodiment, it is possible to reliably cope with the expansion / contraction of the excavation diameter in the above-described “elimination of twist state and lateral displacement state” operation.

  In this embodiment, the hydraulic cylinder 53 is driven using a drive source 55 (see FIG. 4). The drive source 55 is mainly composed of a hydraulic tank and a case for storing the hydraulic tank. The drive source 55 is attached to blades 58, 58... Provided on the excavation shafts 6A, 6A above the excavation members 6b, 6b.

(Third form)
Furthermore, a 3rd form is shown to FIGS.
The enlarged blade mechanism 60 in this form includes a base material 61, an enlarged claw 62 whose base end portion is pivotally supported on the base material 61 by a shaft member 63, one end at the center of the enlarged claw 62, and the other end portion. The cylinder 64 is fixed to the excavation shaft 6.

  In this embodiment, due to the expansion and contraction of the cylinder 64, the expansion claw 62 rotates around the shaft member 63, thereby expanding and contracting the excavation shaft diameter.

The base material 61 is attached to the stirring blade 21 in a state of being inserted into a notch 65 formed in the central portion of the stirring blade 21. This attachment is made in a state where the tip of the expansion claw 62 is slightly lowered. This is to reduce the load on the expansion claw 62 when the excavation diameter is increased.

<Method of detecting shaft bending (tilt of drilling shaft)>
By the way, since the method according to the present invention is based on the assumption that the shaft is bent, it is naturally preferable that a system for detecting the shaft bend is provided.
This detection system is not particularly limited. For example, a detector such as an inclinometer is provided in a control pipe provided in the drilling shaft or separately from the drilling shaft, and the tilt angle signal obtained by this detector is used. The method of transmitting to the ground by a signal cable passed through the shaft can be used.
However, this method needs to secure a space for passing the signal cable in the excavation shaft, and it is difficult to detect the inclination angle during the rotation of the excavation shaft. It is necessary to stop.
Therefore, in the present invention, it is recommended to use a method in which a signal cable is not required and measurement can be performed without stopping the rotation of the excavation shaft. Examples of such methods include the methods described in Japanese Patent No. 3088307 and Japanese Patent No. 3233874.

<Others>
(1) Although the structure is not shown in the figure, the excavation shaft 6 is supplied with a ground solidifying material such as cement milk or a stabilizing liquid, and can be injected into the excavation hole.

(2) In the present embodiment, the method of performing “resolving the twisted state” or “resolving the laterally displaced state” alone has been described. Of course, these may be combined and performed according to the state of the shaft bending. it can.

(3) In the present invention, the extent to which the excavation range is expanded is not particularly limited. If the enlargement is too small, the effect of the present invention cannot be obtained. On the other hand, if the enlargement is too large, it can be appropriately set in consideration of the fact that the enlargement is excessive. When the inventors tested, a sufficient effect was obtained with an enlargement of 5 to 10 cm.

(Example)
When the underground column-type continuous wall was actually constructed by the above method, the axial bending was eliminated and a complete continuous wall having no discontinuous portions was created.

It is a front view of a multi-axis excavator. It is explanatory drawing which shows the state from which the excavation position shifted | deviated. It is explanatory drawing which shows the formation procedure of a hole group. It is a side view of the multiaxial tip part. It is explanatory drawing of a shaft bending (twisted state) elimination process. It is explanatory drawing of an axis | shaft bending (lateral deviation state) elimination process. It is a side view which shows the state in which the expansion blade mechanism (1st form) was attached to the excavation member. It is a bottom view which shows the state where the expansion blade mechanism (1st form) was attached to the excavation member. It is a bottom view of an enlarged blade mechanism (1st form). It is a longitudinal cross-sectional view of an enlarged blade mechanism (1st form) (locked state). It is explanatory drawing which shows a motion of an expansion nail | claw (1st form). It is a side view which shows the state in which the expansion blade mechanism (2nd form) was attached to the excavation member. It is a bottom view of an enlarged blade mechanism (2nd form). It is a side view which shows the state in which the expansion blade mechanism (3rd form) was attached to the excavation member. It is a partial side view which shows the state in which the expansion blade mechanism (3rd form) was attached to the excavation member. It is a bottom view of an expansion nail (3rd form).

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Multi-axis excavation apparatus, 2 ... Base machine, 5 ... Backstay, 6, 6A, 6B ... Excavation shaft, 6b ... Excavation member, 7 ... Rotation drive source, 8 ... Multi-axis reduction gear, 10 ... Connection member, 21 ... stirring blade, 22 ... excavation bit, 30, 40, 50, 60 ... expansion blade mechanism, 42, 52, 62 ... expansion claw, G ... ground, H ... group of holes.

Claims (2)

By inserting a multi-axis consisting of a plurality of excavating shafts arranged in parallel and rotating adjacent to each other in opposite directions into the ground with each excavating shaft rotating forward, During multi-axis drilling,
When the lower end position of the multi-axis has been bent in a state rotated in a plan view with respect to the upper end position, this is a method for eliminating this bending.
After stopping the insertion of the multi-axis,
In the state where each of the excavation shafts is reversed and in the state where the excavation diameter of the excavation shafts arranged on both side ends is enlarged, the multi-axis is pulled up,
Next, the multi-axis is inserted again to the stop position in a state where each of the excavation shafts is reversed and the excavation diameter of the enlarged excavation shaft is returned to the original size. A method for eliminating shaft bending in multi-axis excavation, which is a feature. By inserting a multi-axis consisting of a plurality of excavating shafts arranged in parallel and rotating adjacent to each other in opposite directions into the ground with each excavating shaft rotating forward, During multi-axis drilling,
In the case where an axial bend occurs in which the lower end position of the multi-axis is shifted to one of the alignment directions in a plan view with respect to the upper end position, a method of eliminating the bend of the axis,
After stopping the insertion of the multi-axis,
In the state where each of the excavation shafts is reversed and at least the excavation diameter of the excavation shaft disposed on the side end opposite to the shift direction is enlarged, the multi-axis is pulled up,
Next, the multi-axis is inserted again to the stop position in a state where each of the excavation shafts rotates forward and an excavation diameter of the expanded excavation shaft is enlarged. A method to eliminate shaft bending in multi-axis drilling.