Drilling method, drilling member support structure, and jig

Abstract

To provide a drilling method capable of suppressing the occurrence of buckling in a drilling member extended according to the height of a space, a support structure of the drilling member, and a jig.SOLUTION: The drilling method is a drilling method for drilling a drilling floor installation part 5 by rotating a drilling member 30 by a boring machine 20 installed to be separated upward from the drilling floor installation part 5 through a space 7, and includes an installation process for installing a guide pipe 40 for guiding the drilling member 30 so as to extend downward from the boring machine 20 toward the drilling floor installation part 5, an insertion process for inserting the drilling member 30 into the guide pipe 40, and a drilling process for rotating the drilling member 30 to drill the drilling floor installation part 5. In the installation process, a restraint member 10 for suppressing the radial displacement of the drilling member 30 is installed in the guide pipe 40, and in the insertion process, the drilling member 30 is inserted into the guide pipe 40 via the restraint member 10.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a hole-drilling method, a support structure for a hole-drilling member, and a jig. [Background technology]

[0002] Patent document 1 describes a support device in which a frame body, support material, support ring, the lowest single pipe of the guide pipe, and a stopper ring are firmly connected and fixed together to form an integrated guide pipe support device for water drilling. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Publication No. 2-11518 Summary of the Invention [Problem to be solved by the invention]

[0004] For example, in the open caisson construction method, in which water is poured into the caisson body and the ground at the bottom of the caisson body is excavated while resisting earth pressure, samples of the ground at the bottom of the caisson body are taken to evaluate its bearing capacity. In a boring survey to take such ground samples, a boring machine is installed above the ground via a space, and the boring member is rotated to drill the ground.

[0005] However, because the boring machine is installed above the ground and separated by a space, the drilling member is extended depending on the height of the space, which increases the weight of the drilling member. The weight of the drilling member and the resistance force applied to the drilling member as a reaction force from the ground during drilling increase the load applied to the drilling member from both the top and bottom ends, causing the extended drilling member to become eccentric and prone to buckling. As a result, the excavation work may be interrupted.

[0006] The present invention aims to provide a drilling method, a support structure for a drilling member, and a jig that can prevent buckling from occurring in a drilling member that is extended according to the height of a space. [Means for solving the problem]

[0007] (1) One aspect of the present invention is a drilling method for rotating a drilling member using a boring machine installed above the ground via a space, and drilling a hole in the ground. The method comprises an installation step of installing a guide tube that guides the drilling member so that the guide tube extends downward from the boring machine toward the ground, an insertion step of inserting the drilling member into the guide tube, and a drilling step of rotating the drilling member to drill a hole in the ground. In the installation step, a jig that suppresses radial displacement of the drilling member is installed in the guide tube, and in the insertion step, the drilling member is inserted into the guide tube via the jig.

[0008] In a drilling method according to one aspect of the present invention, in an installation step, a guide tube that guides the drilling member is installed so as to extend downward from the boring machine toward the ground, and a jig that suppresses radial displacement of the drilling member is installed in the guide tube. In an insertion step, the drilling member is inserted into the guide tube via the jig. Here, if the jig is not installed in the guide tube, the drilling member inserted into the guide tube may be radially displaced up to the inner surface of the guide tube. Such radial displacement of the drilling member promotes buckling of the drilling member. In contrast, by inserting the drilling member into the guide tube via a jig that suppresses radial displacement of the drilling member, the promotion of buckling can be suppressed. Therefore, according to the drilling method according to one aspect of the present invention, buckling of the drilling member that is extended according to the height of the space can be suppressed.

[0009] (2) Another aspect of the present invention is a support structure for a drilling member that is rotated by a boring machine installed above the ground via a space to drill a hole in the ground, the support structure comprising: a guide tube that is installed to extend downward from the boring machine toward the ground and that guides the drilling member; and a jig that is installed on the guide tube and that suppresses radial displacement of the drilling member, and the drilling member is inserted into the guide tube via the jig.

[0010] In another aspect of the support structure for a drilling member of the present invention, a guide pipe for guiding the drilling member is installed so as to extend downward from the boring machine toward the ground, and a jig for suppressing radial displacement of the drilling member is installed on the guide pipe. The drilling member is inserted into the guide pipe via the jig. Here, if the jig is not installed on the guide pipe, the drilling member inserted into the guide pipe may be radially displaced up to the inner circumferential surface of the guide pipe. Such radial displacement of the drilling member promotes buckling of the drilling member. In contrast, by inserting the drilling member into the guide pipe via a jig that suppresses radial displacement of the drilling member, the promotion of buckling can be suppressed. Therefore, the support structure for a drilling member of another aspect of the present invention makes it possible to suppress buckling of the drilling member extended according to the height of the space.

[0011] (3) Yet another aspect of the present invention is a jig used in the support structure for the hole-drilling member described in (2) above, which may be a tubular member provided in the space between the hole-drilling member inserted into the guide tube and the inner circumferential surface of the guide tube. In this case, the tubular member occupies the space between the hole-drilling member inserted into the guide tube and the inner circumferential surface of the guide tube, making it easier for the hole-drilling member to be positioned at the axial center of the guide tube. This reduces radial displacement of the hole-drilling member by the tubular member, thereby preventing buckling from occurring.

[0012] (4) Yet another aspect of the present invention is a jig used in the support structure for the hole-drilling member described in (2) above, which may include restraining members installed discretely along the guide tube and suppressing displacement of the hole-drilling member inserted into the guide tube relative to the inner circumferential surface of the guide tube. In this case, the restraining members suppress displacement of the hole-drilling member inserted into the guide tube relative to the inner circumferential surface of the guide tube, making it easier for the hole-drilling member to be positioned at the axial center of the guide tube. As a result, the restraining members reduce radial displacement of the hole-drilling member, thereby suppressing the promotion of buckling.

[0013] (5) In the jig described in (4) above, the restraining member may have a tapered portion that narrows downward. In this case, when the hole-drilling member is inserted into the guide tube via the jig, the hole-drilling member passes through the tapered portion that narrows downward, making it easier to insert the hole-drilling member from above.

[0014] (6) In the jig described in (4) above, the restraining member may have a flange fixed to the guide tube and a plurality of spring members extending radially inward from the flange and curved along the hole-drilling member. In this case, the elastic force of the spring members pushes the hole-drilling member back toward the axial center of the guide tube, thereby suppressing displacement of the hole-drilling member inserted into the guide tube relative to the inner surface of the guide tube. [Effects of the Invention]

[0015] According to the present invention, it is possible to prevent buckling from occurring in the drilling member that is extended according to the height of the space. [Brief explanation of the drawings]

[0016] [Figure 1] A cross-sectional view showing an example of ground to which the drilling method of the embodiment is applied and a support structure for the drilling member of the embodiment. [Figure 2] 1 is a flowchart illustrating an example of a hole-drilling method according to an embodiment. [Figure 3] FIG. 2 is an enlarged cross-sectional view of the support structure of the drilling member of FIG. 1. [Figure 4] FIG. 2 is a perspective view showing a jig according to an embodiment. [Figure 5] FIG. 10 is a perspective view showing a jig according to a modified example. [Figure 6] FIG. 10 is an enlarged cross-sectional view of a support structure for a hole-drilling member using a jig according to another modified example. [Figure 7] FIG. 7 is a plan view of the jig of FIG. 6. DETAILED DESCRIPTION OF THE INVENTION

[0017] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In the description of the drawings, the same or corresponding elements are designated by the same reference numerals, and duplicated explanations will be omitted as appropriate. The drawings may be partially simplified or depicted schematically to facilitate understanding, and the dimensional ratios and the like are not limited to those shown in the drawings. In the following description, the up-down direction refers to the up-down direction along the vertical direction, and corresponds to the up-down direction on the paper in FIG. 1.

[0018] FIG. 1 is a cross-sectional view showing an example of ground to which the drilling method according to the embodiment is applied, and a support structure 1 for the drilling member according to the embodiment. The drilling method according to the embodiment is a drilling method in which a drilling member is rotated by a boring machine installed above the ground and spaced apart from the ground. Here, "a boring machine installed above the ground and spaced apart" refers, as an example, to a boring machine used in boring surveys performed in conjunction with the open caisson method. The support structure 1 for the drilling member is a support structure for a drilling member that is rotated by a boring machine installed above the ground and spaced apart from the ground to drill a hole in the ground.

[0019] 2 is a flowchart showing an example of a hole-drilling method according to the embodiment. In the hole-drilling method according to the embodiment, first, an open caisson construction step is carried out (S01).

[0020] Figure 1 shows an example of a cross section of ground where the open caisson method has been used. The open caisson method uses an open caisson 2, and applies a downward force from a jack in addition to the weight of the open caisson 2, pushing the open caisson 2 downward into the ground. The open caisson method can be applied to large-scale foundation work such as bridge piers.

[0021] The cylindrical open caisson 2, which is open at both ends, is made by connecting multiple cylindrical caisson bodies 3 along the depth direction. The caisson body 3A at the tip of the open caisson 2 has a cutting edge portion 4 whose thickness gradually decreases toward the tip. The open caisson 2 is made of, for example, precast concrete.

[0022] In this embodiment, the open caisson construction method allows the open caisson 2 to be constructed using a known technique. For example, crushed stone replacement or ground improvement is performed in the area of ​​the ground where the open caisson 2 is to be constructed, and a caisson body 3A having a cutting edge portion 4 is lift-cast into place. Excavation proceeds by removing soil and sand using a bucket suspended by a crane inside the area where crushed stone replacement or ground improvement has been performed. During excavation, water is filled inside the open caisson 2 to counteract the earth pressure and water pressure inside and outside the open caisson 2.

[0023] A portion of the open caisson 2, to which the caisson body 3 has been successively added, is sunk on top of the caisson body 3A. After part of the open caisson 2 has sunk, a new caisson body 3 is formed at the end of the open caisson 2 on the ground surface G side, and underwater excavation and press-in are carried out again. As described above, the open caisson 2 is constructed by repeatedly performing underwater excavation, press-in, and adding new caisson bodies 3.

[0024] In such an open caisson method, a boring survey may be conducted on the excavation bedding section 5 of the open caisson 2. The excavation bedding section 5 refers to the bottom surface of the ground that remains after the soil in the open caisson 2 is excavated to the required depth in the open caisson method. In the boring survey, a sample of the ground at the excavation bedding section 5 is taken, and the bearing capacity of the ground is measured and evaluated. Alternatively, a borehole horizontal load test may be conducted at the excavation bedding section 5 as a boring survey.

[0025] Next, an installation step is performed in which the boring machine 20, the boring member 30, and the guide pipe 40 are installed (S02).

[0026] The boring machine 20 for the boring survey is installed on a work stage 6 that spans the end of the open caisson 2 on the ground surface G side. A portable multi-tester (PMT device) 21 for analyzing ground samples may be installed on the work stage 6. A general-purpose boring machine can be used as the boring machine 20. The boring machine 20 may be, for example, a rotary hydraulic feed type.

[0027] The work stage 6 is installed above and spaced apart from the excavation bed base (ground) 5 via a space 7. In other words, the boring machine 20 is installed above and spaced apart from the excavation bed base 5 via the space 7. The space 7 here is the space inside the open caisson 2, and includes a space filled with water and a space above the water surface filled with air. The height of the space 7 may be, for example, 10 m to 50 m.

[0028] A tower 22, for example, a tripod pipe, is erected above the boring machine 20 to support the excavation equipment. With the tower 22 supporting a hole-making member 30 (described below), the boring machine 20 rotates the hole-making member 30.

[0029] In the installation process, the guide pipe 40 is installed so as to extend downward from the boring machine 20 toward the drilling bedding portion 5. The guide pipe 40 is a tubular member that is provided around the drilling member 30 and guides the drilling member 30. Because the boring machine 20 is installed spaced above the drilling bedding portion 5 via the space 7, the guide pipe 40 is divided into a plurality of sections that extend downward from the boring machine 20 toward the drilling bedding portion 5, and as it extends downward, sections are added and the guide pipe 40 is extended. In the installation process, the guide pipe 40 can be installed using, for example, a crane or the like.

[0030] The guide pipe 40 is made of a steel pipe or the like with sufficient strength to suppress buckling of the drilling member 30, whose extension length increases according to the height of the space 7. Figure 3 is an enlarged cross-sectional view of the support structure of the drilling member in Figure 1. As shown in Figures 1 and 3, a tremie pipe having flanges 41 on both ends can be used as the guide pipe 40. In a tremie pipe, one section is, for example, about 3 to 4 m long, and the pipe section 42 between the flanges 41 is, for example, a steel pipe with a diameter of about 200 mm.

[0031] In the installation process, a restraining member (jig) 10 is installed in the guide tube. The restraining member 10 is a jig used in the support structure 1 for the hole-drilling member, and is a member that restrains the hole-drilling member 30 so as to suppress radial displacement of the hole-drilling member 30. The restraining member 10 suppresses displacement of the hole-drilling member 30 inserted into the guide tube 40 relative to the inner surface 43 of the guide tube 40.

[0032] Fig. 4 is a perspective view showing a jig according to an embodiment. As shown in Figs. 1 to 4, the restraining members 10 are installed discretely along the guide pipes 40. In the example of Fig. 1, the restraining members 10 are installed sandwiched between adjacent guide pipes 40, and thus are installed discretely along the guide pipes 40.

[0033] 3 and 4, the restraint member 10 has a flange 11 having a shape corresponding to, for example, the flange 41 of the guide pipe 40. The flange 11 is an annular portion that forms the outermost portion at the upper end of the restraint member 10. The flange 11 has a plurality of through holes 12 formed therein that communicate with a plurality of through holes (not shown) formed in the flange 41 of the guide pipe 40, and is fastened and fixed to the flange 41 of the guide pipe 40 by, for example, bolts and nuts.

[0034] The restraining member 10 has a tapered portion 13 that tapers downward. The tapered portion 13 is a cylindrical portion extending downward from the inner circumferential surface 11a of the flange 11 as its base end. The upper end 13a and lower end 13b of the tapered portion 13 are, for example, circular openings. The inner diameter of the tapered portion 13 is the same as the inner diameter of the inner circumferential surface 11a of the flange 11 at the upper end 13a of the tapered portion 13, becomes smaller than the inner diameter of the inner circumferential surface 11a of the flange 11 as it approaches the lower end 13b of the tapered portion 13, and is larger than the diameter of the casing 31 of the drilling member 30 at the lower end 13b of the tapered portion 13. The rate of change of the inner diameter of the tapered portion 13 in the vertical direction is not particularly limited, but in the examples of Figures 3 and 4, it is a linear function, and the tapered portion 13 is linear in vertical cross section.

[0035] The casing 31 of the drilling member 30 can be inserted into this tapered portion 13. The inner diameter of the lower end 13b of the tapered portion 13 may be approximately 10 mm larger than the outer diameter of the casing 31. In this case, the play between the lower end 13b of the tapered portion 13 and the casing 31 is approximately 5 mm. A member made of a wear-resistant material that reduces friction when the casing 31 rotates may be disposed at the portion of the lower end 13b of the tapered portion 13 that may come into contact with the casing 31.

[0036] Next, an insertion process is performed in which the drilling member 30 is inserted into the guide pipe 40 (S03). The drilling member 30 is a rod-shaped or tubular member that transmits rotational force from the boring machine 20 to drill or investigate the ground. The drilling member 30 has a casing 31 and a rod 32. The casing 31 is a metal tubular member that drills the ground prior to the rod 32. The casing 31 is, for example, divided into multiple sections, and is extended by adding sections as it extends downward. One section is, for example, approximately 2 m long. The outer diameter of the casing 31 can be, for example, approximately φ86 mm. In the insertion process, first, the casing 31 is inserted into the guide pipe 40.

[0037] The rod 32 is a rod-like or tubular metal member that connects the upper boring machine 20 and the lower core portion 33. The rod 32 is, for example, divided into multiple sections, and is extended by adding sections as it extends downward. Each section is, for example, about 2 m long. The core portion 33 is attached to the tip (lower end) of the rod 32. The diameter of the borehole into which the core portion 33 is inserted may be, for example, about φ66 mm, taking into account stable sample collection. In the insertion process, the casing 31 is inserted into the guide tube 40, and then the rod 32 is inserted into the casing 31.

[0038] In the insertion step, the drilling member 30 is inserted into the guide tube 40 via the restraining member 10. In this embodiment, in the insertion step, the casing 31 is first inserted into the guide tube 40, and at the location of the restraining member 10 fixed to the guide tube 40, the casing 31 is guided along the narrowing portion of the tapered portion 13 so as to approach the axial center of the guide tube 40.

[0039] When the casing 31 is inserted into the tapered portion 13, the radial displacement of the casing 31 is restricted by the lower end 13b of the tapered portion 13. In this state, the tapered portion 13 of the restraining member 10 is interposed between the drilling member 30 and the guide tube 40, so this can be said to be a state in which the drilling member 30 is inserted into the guide tube 40 via the restraining member 10.

[0040] In this way, the casing 31 is successively inserted through the plurality of restraining members 10, and as shown in Figure 1, the lower end of the casing 31 reaches the excavation bed 5. In the insertion process, the rod 32 is then inserted into the inside of the casing 31 that has been inserted into the guide pipe 40 via the restraining members 10. The core portion 33 at the lower end of the rod 32 reaches the excavation bed 5.

[0041] Next, a drilling step is performed in which the drilling member 30 is rotated to drill the drilling bedding portion 5 (S04). In the drilling step, for example, when the lower end of the casing 31 reaches the drilling bedding portion 5, the boring machine 20 may rotate the casing 31 to form the drilled portion 5a. Alternatively, when the core portion 33 at the lower end of the rod 32 reaches the drilling bedding portion 5, the boring machine 20 may rotate the rod 32 to form the drilled portion 5b.

[0042] At this time, because the casing 31 is inserted through the tapered portion 13, displacement of the casing 31 relative to the inner circumferential surface 43 of the guide pipe 40 is suppressed. In particular, the casing 31, which has been extended by adding multiple sections, is suppressed from bending to form multiple nodes. As a result, buckling of the drilling member 30 is unlikely to occur even when the drilling member 30 is rotated by the boring machine 20 installed above the drilling bed attachment portion 5 via the space 7.

[0043] As described above, according to the drilling method, support structure 1 for the drilling member, and restraining member 10 of this embodiment, a guide pipe 40 is installed to guide the drilling member 30, extending downward from the boring machine 20 toward the drilling bed attachment 5, and a restraining member 10 is installed on the guide pipe 40 to suppress radial displacement of the drilling member 30. The drilling member 30 is inserted into the guide pipe 40 via the restraining member 10. Here, if the restraining member 10 is not installed on the guide pipe 40, the drilling member 30 inserted into the guide pipe 40 may be radially displaced up to the inner circumferential surface 43 of the guide pipe 40. Such radial displacement of the drilling member 30 promotes buckling of the drilling member 30. In contrast, by inserting the drilling member 30 into the guide pipe 40 via the restraining member 10 that suppresses radial displacement of the drilling member 30, the promotion of buckling can be suppressed. Therefore, the drilling method, support structure 1 for the drilling member, and restraint member 10 of this embodiment make it possible to prevent buckling from occurring in the drilling member 30 extended according to the height of the space 7.

[0044] Restraint members 10 are installed discretely along guide tube 40 and suppress displacement of drilling member 30 inserted into guide tube 40 relative to inner circumferential surface 43 of guide tube 40. As a result, restraint members 10 suppress displacement of drilling member 30 inserted into guide tube 40 relative to inner circumferential surface 43 of guide tube 40, making it easier for drilling member 30 to be positioned at the axial center of guide tube 40. As a result, restraint members 10 reduce radial displacement of drilling member 30, making it possible to suppress the promotion of buckling.

[0045] Restraint member 10 has tapered portion 13 that narrows downward. As a result, when hole-drilling member 30 is inserted into guide tube 40 via restraint member 10, hole-drilling member 30 passes through tapered portion 13 that narrows downward, making it easier to insert hole-drilling member 30 from above.

[0046] The restraint member 10 not only prevents buckling of the casing 31 and rod 32, but also prevents problems such as loosening of the joints between sections, making construction less dependent on the skill of the drilling operator. As a result, the open caisson method facilitates boring surveys to collect ground samples at the excavation bed 5 and measure and evaluate the bearing capacity of the ground, and also facilitates in-hole horizontal load tests at the excavation bed 5. Furthermore, while pneumatic caisson construction typically requires workers to work under high pressure at the excavation bed 5, this embodiment allows the use of a drilling member 30 that can reach the excavation bed 5, eliminating the need for workers to work under high pressure.

[0047] The above describes one embodiment of the present invention, but the present invention is not limited to the above embodiment and may be modified within the scope that does not change the gist of the claims.

[0048] For example, although the restraining member 10 has been exemplified as a jig used in the support structure 1 for the hole-drilling member, the jig is not limited to this example. For example, the jig used in the support structure 1 for the hole-drilling member may be a restraining member (jig) 10A shown in FIG.

[0049] FIG. 5 is a perspective view showing a jig according to a modified example. As shown in FIG. 5, restraining member 10A is a cylindrical member with a coaxial through-hole 14 formed at its axial center and is used to suppress radial displacement of hole-drilling member 30. The outer diameter of restraining member 10A is equal to or slightly smaller than the inner diameter of guide tube 40, and the inner diameter of restraining member 10A may be approximately 10 mm larger than the outer diameter of casing 31. Restraining member 10A is inserted into guide tube 40, casing 31 is inserted through through-hole 14, and rod 32 is inserted through casing 31, thereby holding hole-drilling member 30 near the axial center of guide tube 40. In other words, restraining member 10A is a tubular member provided in space 15 between hole-drilling member 30 inserted into guide tube 40 and inner circumferential surface 43 of guide tube 40. As a result, restraining member 10A occupies space 15 between drilling member 30 inserted into guide tube 40 and inner peripheral surface 43 of guide tube 40, making it easier for drilling member 30 to be positioned at the axial center of guide tube 40. As a result, restraining member 10A reduces radial displacement of drilling member 30, making it possible to suppress the promotion of buckling.

[0050] Alternatively, the jig used in the support structure 1 for the hole-drilling member may be a restraining member (jig) 10B shown in Figures 6 and 7. The restraining member 10B may have a flange 11 fixed to the guide tube 40, and a plurality of spring members 16 fixed to the flange 11. The spring members 16 are elastic members that press the hole-drilling member 30 toward the axial center against the flange 11. A plurality of spring members 16 (e.g., 3 to 6) are attached to the flange 11.

[0051] The spring member 16 is provided in a cantilever shape so as to extend downward from the inner peripheral surface 11a of the flange 11 as a base end. The spring member 16 extends from the inner peripheral surface 11a of the flange 11 toward the radially inner side of the flange 11, and may be curved so as to follow the hole-drilling member 30 as it moves away from the inner peripheral surface 11a of the flange 11.

[0052] As shown in Figure 7, the distance between opposing spring members 16 may be smaller than the outer diameter of hole-drilling member 30 before hole-drilling member 30 is inserted into restraining member 10B. Even in this case, when hole-drilling member 30 is inserted into restraining member 10B, hole-drilling member 30 presses against spring member 16, causing it to elastically deform, thereby enabling spring member 16 to conform to hole-drilling member 30 as shown in Figure 6. The distance between opposing spring members 16 may be equal to or larger than the outer diameter of hole-drilling member 30.

[0053] According to the restraint member 10B, the elastic force of the spring member 16 pushes the drilling member 30 back toward the axial center of the guide tube 40, thereby suppressing displacement of the drilling member 30 inserted into the guide tube 40 relative to the inner surface 43 of the guide tube 40.

[0054] In the above-described embodiment and modified examples, the rate of change of the inner diameter of the tapered portion 13 of the restraint member 10 is a linear function in the examples of FIGS. 3 and 4 , but is not limited to this example and may be nonlinear, so that the tapered portion 13 is curved in vertical cross section.

[0055] In the above embodiment and modified examples, the restraint members 10, 10B are sandwiched between adjacent guide tubes 40 and are installed discretely along the guide tube 40, but this is not limiting. The restraint members 10, 10B may be installed midway along the guide tube 40 and be installed discretely along the guide tube 40.

[0056] In the above embodiment and modified example, the case where the open caisson 2 is surrounded by ground in the open caisson construction method is exemplified as an example in which the boring machine 20 is installed above and spaced apart from the excavation bed 5 via the space 7, but this is not limiting. For example, when collecting soil samples from underwater ground at the bottom of an ocean or lake, the boring machine may be installed on a work stage set up above water. In this case, an open caisson is not used, and the guide pipe may be submerged in the water of the ocean or lake.

[0057] In the above-described modified example, the restraint member 10A is a member already having a tubular shape, but this is not limiting. For example, the guide pipe 40 may be filled with a predetermined material, and the material may be drilled with the casing 31, so that the predetermined material remaining in the space between the casing 31 inserted into the guide pipe 40 and the inner circumferential surface 43 of the guide pipe 40 functions as a jig. The predetermined material may be a material that has excellent filling properties and solidifies to an appropriate strength, such as liquefied treated soil.

[0058] In the above embodiment and modified example, an example was shown in which a jig that suppresses radial displacement of the drilling member 30 is installed in the guide pipe 40, but a method is also conceivable in which a jig such as an outer diameter ring that fits into the space between the casing 31 inserted into the guide pipe 40 and the inner circumferential surface 43 of the guide pipe 40 is attached to the casing 31 to suppress radial displacement of the drilling member 30. In this case, considering that it is necessary to attach a jig to the casing 31, it can be said that the present invention, in which general-purpose boring machines 20 and drilling members 30 can be used as they are, is superior in terms of versatility and on-site workability. [Explanation of symbols]

[0059] 1...Support structure for drilling member, 5...Drilling bed attachment portion (ground), 7...Space, 10, 10A, 10B...Restraining member (jig), 11...Flange, 13...Tapered portion, 15...Space, 16...Spring member, 20...Drilling machine, 30...Drilling member, 40...Guide tube, 43...Inner surface

Claims

1. A drilling method for drilling a hole in the ground by rotating a drilling member using a boring machine installed above and spaced apart from the ground, an installation process of installing a guide pipe that guides the boring member so as to extend downward from the boring machine toward the ground; an insertion step of inserting the drilling member into the guide tube; a drilling step of rotating the drilling member to drill a hole in the ground, In the installation step, a jig for suppressing radial displacement of the hole-making member is installed in the guide tube; In the inserting step, the hole-drilling member is inserted into the guide tube via the jig.

2. A support structure for a boring member that is rotated by a boring machine installed above and spaced apart from the ground to drill a hole in the ground, A guide pipe that is installed so as to extend downward from the boring machine toward the ground and guides the boring member; a jig that is installed in the guide pipe and suppresses radial displacement of the drilling member; A support structure for a drilling member, wherein the drilling member is inserted into the guide tube via the jig.

3. A jig used in the support structure of the hole-making member according to claim 2, A jig that is a tubular member that is provided in the space between the drilling member inserted into the guide tube and the inner surface of the guide tube.

4. A jig used in the support structure of the hole-making member according to claim 2, A jig is a restraint member that is installed discretely along the guide tube and suppresses displacement of the drilling member inserted into the guide tube relative to the inner surface of the guide tube.

5. The jig according to claim 4 , wherein the restraining member has a tapered portion that narrows downward.

6. The jig according to claim 4 , wherein the restraining member has a flange fixed to the guide tube, and a plurality of spring members extending radially inward from the flange and curved to follow the drilling member.

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