JP6542179B2 - Core material burial method - Google Patents

Description

  The present invention relates to a method of digging the ground by applying a rotational force and a striking force to a casing provided with a bit at a tip end portion, and embedding a core material such as a lock bolt in a drilled hole formed.

  Conventionally, in order to stabilize the ground such as various slopes and tunnel inner walls, a core material such as a lock bolt made of deformed rebar is embedded in a hole formed by excavating the ground, and around the core material It is carried out that a solidifying material (grout) such as cement milk is filled and reinforced. As such a core material burying method, in particular when applied to a ground which is poor in geology and prone to pore wall collapse, a double pipe lock bolt method is often used.

  In this double-tube type lock bolt construction method, generally, a double-tube type drilling tool is used which comprises an outer tube provided with a tip outer bit (ring bit) and an inner tube provided with an inner bit at the tip. While applying drilling power and striking force to the drilling tool to drill the ground and injecting drilling water or compressed air through the inner pipe, the generated excavated soil is discharged between the inner pipe and the outer pipe, After drilling the required depth, the inner pipe with the inner bit is pulled out, a lock bolt is inserted into the left outer pipe and a solidifying material is injected, and then the outer pipe with the outer bit is pulled out. However, in such a construction method, the drilling tool is complicated and expensive, and since it is a double pipe, it is necessary to add both the outer pipe and the inner pipe when adding the drilling rod. Since it requires complicated procedures such as pulling out the inner pipe after drilling, inserting the lock bolt, injecting the solidified material, and pulling out the outer pipe, there was a problem that it took a lot of labor and time and was inferior in working efficiency. .

  Therefore, as a means to cope with the problem of working efficiency in the double-pipe type lock bolt construction method, the protective cylinder is covered with a hollow lock bolt having a drill bit at the tip via a detachable means to secure the lock bolt and protection. A self-piercing double tube lock bolt method has been proposed in which a solidifying material is injected through the inside of a lock bolt after inserting a solid material into the ground while pushing the ground into the ground while rotating the cylinder, and extracting the protective cylinder (Patent Document 1) . In this construction method, the lock bolt itself constitutes the inner pipe of the double pipe, and the work efficiency is improved because the inner pipe withdrawal after the drilling is unnecessary and the expensive drilling bit is left in the ground as a lot bit, In addition, the use of the hollow lock bolt has a drawback that the construction cost is high and the versatility is lacking.

  In addition, as a lock bolt embedding method that does not use an inner pipe, an outer bit (ring bit) having a fitting groove along the axial direction is provided at the tip of a tubular drill rod (casing pipe). After inserting a lock bolt into the drill rod from the tip, install a small lost bit that fits through a fixing member such as a lock pin in the fitting groove of the outer bit and drill the ground by drilling the ground. The drill rod is later pulled out, but the fixed member is cut off by the axial force and rotational force of the drill rod in the drilled hole, leaving the lost bit detached from the drill rod in the ground and the lock bolt by its own weight. There is also proposed a method of extracting from the inside of the drill rod and setting it in the drilled hole, and finally filling the solidified material in the drilled hole and fixing it (Patent Document 2). In this method, the workability is greatly improved because the inner pipe is not used, but even if it is small, the lost bit is left in the ground, which increases the cost, and it solidifies by the hole wall collapse after the drill rod is pulled out. There is a possibility that the material can not be filled evenly, and there is also a concern that the fixing member is not cut well and the lost bit can not be detached and the lock bolt can not be withdrawn.

  Furthermore, as a double pipe lock bolt construction method, a double pipe drilling tool having an outer pipe having an outer bit attached to its tip and an inner bit attached to the inner side of the outer bit and located at the tip of the inner pipe After drilling the ground, only the inner pipe is extracted, and then the core material (lock bolt) is inserted into the outer pipe left behind in the ground and the solidifying material is injected, and the inner bit is pressed by the core material and the outer A method has been proposed in which the attachment to the bit is released, the inner pipe is inserted between the core and the outer pipe, and the outer pipe and the inner pipe are extracted while the core and the inner bit are left in the ground. (Patent Document 3). In this construction method, the workability is improved by eliminating the need for desorption operation of the inner pipe to the ground drilling equipment, but the cost is high in that the inner bit is left in the ground as a lost bit, and the inner bit is an outer bit. Against friction, fasteners such as wooden pins, hinges, etc., but there is a concern that the impact from the impact may cause the outer bit to become untrivial before drilling is completed, and that the drilling rod should The basic problem of requiring both outer and inner pipe addition operations is not solved.

JP, 2002-129899, A JP 2003-106100 A JP, 2013-079487, A

  In view of the above-described circumstances, the present invention does not require a complicated procedure such as the conventional double pipe lock bolt construction method as a construction method for embedding a core material such as a lock bolt in a borehole, and only a single pipe Additives can be used to continue drilling, avoid cost increases due to lost bits, and there is no concern about hole wall collapse until grout is injected into the drill hole, and core material inserted into the drill hole can be firmly secured. It is an object of the present invention to provide a construction method which can be fixed, and in addition to which a boring tool to be used can be structurally simple and inexpensively manufactured, and is excellent in operation reliability.

In the core material embedding method according to the invention of claim 1, the means for achieving the above object is shown with reference numerals of the drawings, in the inside of the ring bit 2 provided at the tip of the casing pipe 1 Using a drilling tool T in which a pilot bit 3 having a recovery locking portion 32 at its end is inserted in a manner such that it can be rotationally displaced in a circumferential direction in a constrained state and a non-restrained state. Applying a rotational force and a striking force to the casing pipe 1 and holding the pilot bit 3 in the restraining state by the rotational reaction force and the cutting force to excavate the ground G, and a casing pipe in the formed drilling hole H Insert the recovery rod 5 provided with the engagement connector 4 to the recovery lock portion of the pilot bit 3 at the tip into the inside of 1, and engage the engagement connector 4 to the recovery lock portion 32 For process and ring bit 2 A step of recovering the pilot bit 3 from the ground by extracting the pilot bit 3 in the restricted state integrally with the recovery rod 5 from the inside of the casing pipe 1, and in the casing pipe 1 after recovery of the pilot bit 3. a step of injecting grout 7 is inserted a core material 6, a step of pulling out the casing pipe 1 from the ground G and leaving the core material 6 into the excavation hole H, Ri sequentially through,
The locking portion 32 for recovery of the pilot bit 3 is provided with locking projections 32 a and 32 a that protrude laterally on the rear end shaft portion 31 along the direction of the axis O, and the engaging connector for the recovery rod 5 4 is a cylindrical portion 4a which can be externally fitted to the rear end shaft portion 31 of the pilot bit 3, the guide grooves 41, 41 axially inserted from the front end, and the casing pipe rotating direction continuously from the guide grooves 41, 41 The locking grooves 42 and 42 extending in the circumferential direction opposite to r are cut out so that the locking projections 32a and 32a are inserted into the guide grooves 41 and 41 when the pilot bit 3 is recovered. Then, externally fit the cylindrical portion 4a of the engagement connector 4 to the rear end shaft portion 31 of the pilot bit 3 and then twist the recovery rod 5 to hold the locking projections 32a and 32a from the guide grooves 41 and 41. By shifting to the locking grooves 42, 42 side, It is characterized in that to engage connecting pilot bit 3 in the collection rod 5.

According to a second aspect of the present invention, in the core material embedding method according to the first aspect, the ring bit 2 has a plurality of first convex wall portions 21 equally spaced in the circumferential direction at an axially intermediate portion of the inner periphery. A plurality of second convex wall portions 22 narrower in circumferential direction width than the first convex wall portion 21 are equally formed in the circumferential direction on the inner peripheral portion 20 on the tip side of the first convex wall portions 21 and adjacent to each other Between the first convex wall portions 21 and 21 forming the insertion groove 23 in the axial direction, and the second convex wall portions 22 overlap the first convex wall portions 21 in the axial direction, and The pilot bit 3 is disposed on the opposite side to the rotational direction r, and the pilot bit 3 has a plurality of engagement projections 33 corresponding to the insertion groove 23 of the ring bit 2 circumferentially equally distributed on the tip side of the outer periphery And each engaging projection 33 has a circumferential width through which the insertion groove 23 can be passed, and the rear of the engaging projection 33 In the outer peripheral portion of the second embodiment, the retaining protrusion 34 is formed, and the non-restrained state at the rotational position where the engagement protrusion 33 faces the insertion groove 23 of the ring bit 2 in the axial direction It is assumed that the restraint state is achieved at the moving position.

  Hereinafter, the effects of the present invention will be described with reference to the drawings. According to the core material burying method according to the invention of claim 1, using the drilling tool T in which the pilot bit 3 is inserted into the ring bit 2 provided in the casing pipe 1, the drilling tool T Since the ground is drilled in the form of single pipe digging by applying a rotational force and a striking force, the complicated procedure involving the attachment and detachment of the inner tube as in the conventional double tube lock bolt method is not required, and the casing pipe 1 Since the drilling can be continued with the addition of only one, and the core material 6 is inserted and the grout 7 is injected with the casing pipe 1 left in the ground after the drilling, there is no concern about the hole wall collapse, and the core material 6 is not It can be firmly fixed firmly. The pilot bit 3 is pivotally displaceable in the axial direction with respect to the ring bit 2 in the restraining state and the non-restraining state. Since the restraint state is maintained, the rotational force and the striking force applied to the casing pipe 1 can be reliably transmitted to exhibit a high digging function. Moreover, since the pilot bit 3 after drilling is engaged with and connected to the recovery rod 5 and recovered from the ground, in addition to the fact that the cost increase due to the conventional lost bit can be avoided, the pilot bit 3 is repeatedly Since it can be used, there are few cost restrictions and it is possible to select the specifications of the structure, material, etc. in terms of enhancing the drilling power. Further, since the pilot bit 3 only needs to be able to be pivoted and displaced in the axial direction with respect to the ring bit 2 in the restraining state and the non-restraining state, there is also an advantage that the fitting structure between the two bits 2 and 3 can be set simply. In order to displace the pilot bit 3 after drilling from the restraining state to the non-restraining state, the casing pipe 1 is slightly rotated in the direction opposite to the rotational direction at the time of drilling or engaged with the pilot bit 3 It is only necessary to slightly rotate (twist) the recovery rod 5 after connection in the rotational direction at the time of drilling the casing pipe 1.

Further, according to the invention of claim 1, when the pilot bit 3 after drilling is recovered, the locking projections 32a, 32a of the recovery locking portion 32 are used as guides of the engaging connector 4 of the recovery rod 5 By inserting the grooves 41 and 41 and then twisting the recovery rod 5 in the rotation direction of the casing pipe 1, the locking projections 32 a and 32 a move to the locking grooves 42 and 42 of the engagement connector 4. Since the pilot bit 3 is engaged with the engaging connector 4 so as not to move in the axial direction, the pilot bit 3 brought into the non-restrained state relative to the ring bit 2 is made integral with the recovery rod 5. It can be pulled out from inside the casing pipe 1 and recovered easily.

According to the invention of claim 2 , when the pilot bit 3 is rotatably movably fitted to the ring bit 2 in the axial direction in the constrained state and the non-restrained state, a plurality of inner circumferences of the ring bit 2 are provided. A first convex wall portion 21 and a second convex wall portion 22 are provided, and an insertion groove 23 in the axial direction is formed between the adjacent first convex wall portions 21 and 21 while the ring bit 2 is inserted into the outer periphery of the pilot bit 3 Since it is only necessary to provide a plurality of engaging convex portions 33 and retaining convex portions 34 corresponding to the grooves 23, both the bits 2 and 3 can be manufactured at low cost and high operation reliability can be obtained.

It is a longitudinal cross-sectional view which shows the drilling tool used for the core material embedding | flush-mounting method which concerns on one Embodiment of this invention. The drilling head part in the drilling tool is shown, (a) is the perspective view seen from the tip end side, (b) is the perspective view seen from the rear end side. The same excavation head part is shown, (a) is a front view when a pilot bit is in an unrestrained state, (b) is a front view when it is in the same restraint state. It is a front view of the same pilot bit. It is a front view of the ring bit of the drilling tool. It is arrow sectional drawing of the XX line of FIG. It is a perspective view of the engaging connector provided in the rod for collection | recovery used for a concentric-materials burying method. The engagement coupler is shown, (a) is a front view, (b) is a longitudinal cross-sectional side view, and (c) is a rear view. It is a perspective view showing connection operation to the pilot bit of the engagement connector in order of (a)-(c). It is a vertical side view which shows the process from the completion of a wellbore in the core material burial method to recovery of a pilot bit in order of (a)-(e). It is a longitudinal cross-sectional view which shows the process from core material insertion to core material fixation after pilot bit collection | recovery in the core material embedding | flush-mounting method in order of (a)-(d).

  Hereinafter, a core material embedding method according to an embodiment of the present invention will be specifically described with reference to the drawings. In the core burying method of this embodiment, a drilling tool T shown in FIGS. 1 to 6 and a recovery rod 5 with an engaging connector 4 shown in FIGS. 7 to 9 are used.

  As shown in FIG. 1, the drilling tool T used for this core material burying method is excavated comprising a ring bit 2 and a pilot bit 3 inside thereof at the tip of a cylindrical casing pipe 1 shown by a phantom line. A head unit 10 is provided. The casing pipe 1 is connected to an excavating apparatus provided with a drifter or the like whose rear end is not shown, and the excavating apparatus rotates a rotational force r (see FIGS. 2 and 3) around the axis O. An impact force directed toward the axial distal end, and a propulsive force directed toward the axial distal end if necessary, are applied. Although the casing pipe 1, the ring bit 2 and the pilot bit 3 are made of a metal material such as steel, the tip surfaces of the ring bit 2 and the pilot bit 3 are bits as shown in FIGS. A large number (21 in the drawing) of drilling die 8 made of cemented carbide or the like having a hardness higher than that of the main body is implanted so as to be dispersed substantially uniformly.

  The ring bit 2 has a cylindrical shape as a whole, and the rear side having the male screw 2a engraved on the outer periphery is screwed to the lower end having the female screw 1a engraved on the inner periphery of the casing pipe 1 Concentrically connected to 1. The direction of twisting of the male and female screws 1a and 2a is set in the direction in which the screwing is deepened by the rotational force of the casing pipe 1 at the time of drilling. The inner diameter of the ring bit 2 is substantially equal to the inner diameter of the casing pipe 1, but the diameter of the middle portion of the casing pipe 1 to the tip end is tapered in the direction from the outer diameter of the casing pipe 1 to the tip side. ing. A plurality (eight in the drawing) of discharge grooves 25 having a concave arc shape in cross section along the axial direction are equally formed in the circumferential direction at the enlarged outer peripheral portion.

  Further, as shown in detail in FIGS. 5 and 6, on the inner periphery of the ring bit 2, a plurality of (three in the drawing) first convex wall portions 21 are equally distributed in the circumferential direction in the radial direction intermediate portion thereof. The adjacent first convex wall portions 21 and 21 form an insertion groove 23 in the axial direction, and the first convex wall portion 21 is formed on the inner circumferential portion 20 on the tip end side of the first convex wall portions 21. A plurality of second convex wall portions 22 narrower in circumferential width than the circumferential direction are equally formed in the circumferential direction. And each 2nd convex wall part 22 overlaps with the 1st convex wall part 21 in the direction of an axis, and is arranged on the opposite side to the rotation direction r of casing pipe 1, and is arranged. The side edge portion is at the same position as the side edge portion on one side of the first convex wall portion 21 in the circumferential direction.

  On the other hand, as shown in FIG. 1, the pilot bit 3 has a substantially multistage cylindrical shape in which the front end side has a larger diameter than the rear end side, and the front end protrudes inward of the ring bit 2 inside the ring bit 2. It is inserted in the state. As shown in FIG. 4, the main body portion 30 with a large diameter on the tip end side has a length of half of the total length, and a plurality (three in the figure) corresponding to the insertion grooves 23 of the ring bit 2 on the outer periphery The engagement projection 33 on the front end side and the retaining projection 34 on the rear side are equally spaced in the circumferential direction. In addition, the rear end side of the small pilot bit 3 is provided with a pair of locking projections 32a, 32a at the axially intermediate portion of the rear end shaft portion 31 as the recovery locking portion 32 so as to protrude on both sides in the radial direction. ing. As shown in FIG. 3, both sides in the radial direction orthogonal to the direction in which the locking projections 32a and 32a are provided are the collecting engagements including the rear end shaft portion 31 and both locking projections 32a and 32a. A flat surface is formed by parallel cutting the entire stop 32.

  Each engaging convex portion 33 and each retaining convex portion 34 of the pilot bit 3 have a circumferential width that can pass through the insertion groove 23 of the ring bit 2 in the axial direction, and they are disposed to face each other in the axial direction. The distance between the convex portions 33 and 34 is greater than the axial width of the first convex wall portion 21 of the ring bit 2. Then, as shown in FIGS. 1 to 3, the circumscribed circle diameter at the position of the engagement convex portion 33 and the retaining convex portion 34 of the pilot bit 3 is slightly smaller than the inner diameter of the ring bit 2 and the ring bit The diameter of the inscribed circle at the position of the first convex wall 21 and the second convex wall 22 is set to be slightly larger than the outer diameter of the main body 30 of the pilot bit 3.

  With the above configuration, the pilot bit 3 inserted into the ring bit 2 is in a state where the first convex wall portion 21 of the ring bit 2 is disposed between the spaced engagement convex portion 33 and the retaining convex portion 34. The ring bit 2 can be rotated in the circumferential direction. The rotation range is such that the respective engaging convex portions 33 of the pilot bit 3 are disposed on the inner peripheral portion 20 between the adjacent second convex wall portions 22 and 22 in the ring bit 2, the inner peripheral portion 20. It becomes the circumferential direction movable range of the engagement convex part 33 inside. That is, the position where the side edge 33a on the rear side in the casing pipe rotation direction r abuts on the side edge 22a on the front side in the same rotation direction r of the second convex wall 22; It is movable between the position where the side edge 33b on the front side is in contact with the side edge 22b on the front side in the same rotational direction r of the second convex wall 22.

  Then, as shown in FIG. 2 (a), the pilot bit 3 is engaged at the rotational position where the engagement convex portion 33 and the retaining convex portion 34 face the insertion groove 23 of the ring bit 2 in the axial direction. When the portion 33 and the retaining projection 34 pass through the insertion groove 23, the ring bit 2 can be axially moved in a non-restrained state. On the other hand, as shown in FIG. 2 (b), at the rotational position where the engagement convex portion 33 and the retaining convex portion 34 axially face the first convex wall portion 21 of the ring bit 2, relative to the ring bit 2 It will be in the restraint state which can not move in the axial direction. Therefore, in assembling the drilling tool T, the pilot bit 3 is positioned with respect to the ring bit 2 by positioning so that the engagement convex portion 33 or the retaining convex portion 34 faces the insertion groove 23 of the ring bit 2. While being able to be inserted from any of the front end side and the rear end side, the pilot bit 3 after insertion is rotationally displaced in the direction opposite to the rotation direction r of the casing pipe 1 so as to be in the axially immovable restraint state It can be converted. That is, when the tip side of the drilling tool T is directed downward, the retaining bit 34 abuts against the first convex wall 21 of the ring bit when the pilot bit 3 is in the constrained state, and the drilling tool is reversed. When the tip end side of T is directed upward, the engaging convex portion 33 abuts on the first convex wall portion 21, so there is a concern that it may be pulled out by its own weight or to the inner deep side of the casing pipe 1 in reverse. There is no.

  When drilling a ground by applying a rotational force and a striking force to the drilling tool T, the pilot bit 3 is restrained in the axial direction as shown in FIG. 2 (b) by the rotational reaction force and the digging resistance. When the side edge 33a of each engaging convex portion 33 is in contact with the side edge 22a of each second convex wall portion 22 of the ring bit 2 at this time, the rotational force applied to the casing pipe 1 through the ring bit 2 As shown in FIG. 1, the front end face 21 a of each first convex wall 21 of the ring bit 2 is pressed against the rear end face 33 c of each engagement convex part 33 to be added to the casing pipe 1. The striking force and the axial propulsive force are transmitted, thereby cooperating with the ring bit 2 to exhibit a high drilling ability.

  As shown in FIGS. 1 to 4, the pilot bit 3 has a central blow hole 35 a extending from the rear end along the axis O to the vicinity of the front end, and 2 from the front end to the bit front end surface. Branch blow holes 35b and 35b, and a blow groove 35c extending from the tip end opening of each branch blow hole to the bit peripheral portion along the bit tip surface, and compressed in the casing pipe 1 when drilling. Air is set to be jetted to the tip end surface of the bit through the central blow hole 35a and the branch blow holes 35b, 35b. Thus, the compressed air also spouts from the space between the adjacent second convex wall portions 22 and 22 through the insertion groove 23 of the ring bit 2 to the tip end face of the bit, along with the flow of polluted powder generated by the drilling, The discharge groove 25 around the ring bit 2 discharges rearward through the gap between the drilled hole and the outer periphery of the casing pipe 1.

  7 and 8 show the engaging connector 4 attached to the tip of the recovery rod 5 used in the core material embedding method. The engagement connector 4 is engaged with and coupled to the recovery locking portion 32 of the pilot bit 3 when the pilot bit 3 after drilling is recovered. And a rear side cylindrical portion 4b having a bottomed mounting hole 44 in which a female screw 44a is engraved on the inner periphery. Are integrated concentrically.

  In the cylindrical portion 4a on the front side, a pair of guide grooves 41 and 41 which enter in the axial direction from both radial direction positions of the front end, and from the guide grooves 41 and 41, the direction reverse to the casing pipe rotation direction r The locking grooves 42 and 42 extending in the circumferential direction of the are formed in a cutout. The inner diameter of the cylindrical portion 4a is the outer diameter of the rear end shaft portion 31 of the pilot bit 3, and the width of the guide groove 41 is the circumferential width of the locking projection 32a of the recovery locking portion 32. The locking grooves 42 are set to be slightly larger than the axial width of the locking projection 32a.

  Further, a plurality (three in the drawing) of convex ridges 43 along the axial direction are equally distributed in the circumferential direction on the outer periphery of the rear cylindrical portion 4b. The circumscribed circle diameter is set to be slightly smaller than the inner diameter of the casing pipe 1 and the ring bit 2. And the front end side with an external screw (illustration omitted) of the rod 5 for collection | recovery shown by the imaginary line of FIG. 7 is screwed in the attachment hole 44 of this cylindrical part 4b.

  In order to engage and couple the engaging connector 4 of the above configuration to the recovery locking portion 32 of the pilot bit 3, first, as shown in FIG. 9A, both guide grooves 41, 41 are the recovery locking portion The distal end side of the engaging connector 4 is concentrically opposed to the rear end side of the pilot bit 3 so as to face the 32 locking projections 32a and 32a, and then both are engaged as shown in FIG. 9 (b). The cylindrical portion 4a on the front side of the engagement connector 4 is formed as the rear end shaft 31 of the pilot bit 3 in such a manner that the two locking projections 32a and 32a of the recovery locking portion 32 enter the guide grooves 41 and 41. After being inserted and fitted, as shown in FIG. 9 (c), the engagement locking member 4 is rotationally displaced in the casing pipe rotation direction r by the twisting operation of the recovery rod 5, whereby the recovery locking portion The engaging positions of the two locking protrusions 32a, 32a from the guide grooves 41, 41 to the locking grooves 42, 4 It is sufficient to migrate to. As a result, the pilot bit 3 can not be removed axially with respect to the engagement connector 4. In addition, even if the initial direction of the engagement connector 4 with respect to the recovery locking portion 32 of the pilot bit 3 is not matched, both guide grooves 41 and 41 can be obtained by twisting while pressing the recovery rod 5. The cylindrical portion 4a is inserted into the rear end shaft portion 31 of the pilot bit 3 when the two locking projections 32a, 32a are oriented.

  Next, an embodiment of the core material burying method of the present invention using the drilling tool T and the recovery rod 5 having the above-described configuration will be specifically described with reference to FIGS. 10 and 11. In addition, in this embodiment, the case where it drills diagonally downward with respect to the ground G of a slope is illustrated.

  In this core material burying method, as shown in FIG. 10 (a), the drilling tool T with the pilot bit 3 in the restraining posture is mounted on an excavating apparatus (not shown) equipped with a drifter etc. Similar to pipe digging, the ground G is drilled to form a drill hole H of a predetermined depth by giving the drilling tool T a rotational force and a striking force and, if necessary, a thrust toward the tip end in the axial direction. Do. In the drilling process, as described above, the pilot bit 3 maintains the restricted state by the rotational reaction force and the digging resistance, and cooperates with the ring bit 2 to exhibit high digging ability. Further, the polluted powder generated during the drilling is a gap between the drilling hole H and the outer periphery of the casing pipe 1 from the discharge groove 25 around the ring bit 2 by the compressed air supplied into the casing pipe 1 and jetted from the tip end surface of the bit. It is discharged backward through the

  Thus, after forming the drilling hole H, as shown in FIG. 10 (b), the recovery rod 5 having the engaging connector 4 mounted at its tip is inserted into the casing pipe 1 in the ground from the rear. Eccentricity of the recovery rod 5 at the time of insertion is suppressed with respect to the casing pipe 1 by the plurality of protruding portions 43 protruding from the periphery of the engagement connector 4. Then, as shown in FIG. 10C, the engaging connector 4 of the recovery rod 5 is fitted to the recovery locking portion 32 of the pilot bit 3, and the recovery rod 5 is rotated in the casing pipe rotation direction r. By twisting, the engagement connector 4 and the recovery locking portion 32 are engaged and coupled, and by further twisting the recovery rod 5, the pilot bit 3 is not made relative to the ring bit 2. Rotate and displace to the restraint state.

  Here, instead of converting the pilot bit 3 into the unconstrained state by twisting the recovery rod 5 in this manner, the casing pipe 1 is formed at the stage where the drilling hole H of a predetermined depth is formed as shown in FIG. The pilot bit 3 may be converted into the unrestrained state in advance by slightly rotating it in the direction opposite to the rotation direction at the time of drilling. Also, after engaging and connecting the engaging connector 4 of the recovery rod 5 to the recovery locking portion 32 of the pilot bit 3, the pilot pipe 3 is rotated in the reverse direction, so that the pilot bit 3 is not rotated. It may be converted to a restraint state. However, if the contact resistance of the pilot bit 3 to the ground G after drilling is small, there is a possibility that the pilot bit 3 may rotate together in the restraining state due to the reverse rotation of the casing pipe 1. It is recommended to switch the pilot bit 3 to the unconstrained state by the time.

  After the pilot bit 3 in the non-restraint state is engaged and coupled to the recovery rod 5 as described above, the pilot bit is extracted by pulling out the recovery rod 5 from the inside of the drilling hole H as shown in FIG. Recover 3 from the ground. As a result, as shown in FIG. 10E, the casing pipe 1 and the ring bit 2 are left in the drill hole H.

  Next, as shown in FIG. 11 (a), a core material made of a metal material such as a deformed reinforcing bar and the like with the hooking prevention member 61 fitted on the tip end side in the drilling hole H in which the casing pipe 1 and the ring bit 2 are left. 6 is inserted, and grout 7 such as cement milk is injected as shown in FIG. 11 (b). The insertion of the core material 6 and the injection of the grout 7 may be performed either before or after, or may be performed simultaneously. In addition, the engagement prevention tool 61 of the core member 6 is a pair of ring portions 61a, 61a externally fitted to the core member 6, in which a plurality of arc-shaped pieces 61b equally distributed in the circumferential direction are integrated at both ends. .

  After inserting the core material 6 and injecting the grout 7, as shown in FIG. 11 (c), the casing pipe 1 left behind is pulled out integrally with the ring bit 2. Since grout 7 is filled in drill hole H at the time of this extraction, the collapse of the hole wall is prevented, and the arc-shaped piece 61b of the engagement prevention member 61 protrudes around the tip end side of the core 6 Therefore, there is no concern that the unevenness on the inner circumference of the ring bit 2 coming off may be caught on the tip of the core 6 or the surface unevenness.

  Then, after the casing pipe 1 and the ring bit 2 are extracted, as shown in FIG. 11 (d), the core 6 inserted is excavated by the hardening of the grout 7 in the excavated hole H after the required time passes. Firmly firmly fixed at the approximate center of H, ground G is effectively reinforced.

  In such a core burying method, since the ground G is drilled in the form of single pipe digging with a drilling tool T, a complicated procedure involving attachment and detachment of the inner pipe as in the conventional double pipe lock bolt method is required. Since drilling can be continued by adding only a single pipe, that is, the casing pipe 1, work efficiency is good and high construction efficiency can be obtained. Moreover, since the pilot bit 3 after drilling is engaged with and connected to the recovery rod 5 and recovered from the ground, in addition to the fact that the cost increase due to the conventional lost bit can be avoided, the pilot bit 3 is repeatedly Since it can be used, there are few cost restrictions and it is possible to select the specifications of the structure, material, etc. in terms of enhancing the drilling power.

  In the drilling tool T used for the core material burying method of the present invention, the pilot bit 3 may be rotationally displaced in the axial direction with respect to the ring bit 2 in the restraining state and the non-restraining state. The combination structure can be set variously in addition to those exemplified in the embodiment. For example, in the configuration in which the pilot bit 3 is inserted only from the rear end side of the ring bit 2, the retaining convex portion 34 may be an annular convex portion continuous in the circumferential direction. Further, regarding the ring bit 2, in the embodiment, the first convex wall portion 21 and the second convex wall portion 22 on the inner periphery are axially separated, but both convex wall portions 21 and 22 are continuous in an L shape It may be a form.

  On the other hand, the engagement connector 4 of the recovery rod 5 only needs to be able to engage and couple the recovery locking portion 32 of the pilot bit 3, and the guide grooves 41 and 41 and the locking groove 42 in the cylindrical portion 4 a as illustrated. , 42, for example, a mechanism including various engaging and connecting mechanisms including a mechanism for engaging and disengaging with the recovery locking portion 32 by an open / close clamp arm can be adopted. Then, the recovery locking portion 32 on the pilot bit 3 side may be configured to correspond to the engagement and coupling mechanism of the engagement and coupling device 4. However, since the engaging connector 4 exemplified in the embodiment has a simple structure without moving parts, there is an advantage that it can be manufactured at low cost without concern of failure.

  In addition, in the present invention, the outer peripheral shape of the ring bit 2 in the drilling tool T to be used, the form of the bit surface of the pilot bit 3, the number and arrangement of the drilling tips 8 to be implanted in both bits 2 and 3, rods for recovery 5 The attachment structure of the engaging connector 4 with respect to the surface shape of the core member 6 and the detailed configuration such as the surface shape of the core member 6 can be variously changed in design other than the embodiment.

Reference Signs List 1 casing pipe 2 ring bit 20 inner circumferential portion 21 first convex wall portion 22 second convex wall portion 23 insertion groove 3 pilot bit 31 rear end shaft portion 32 recovery locking portion 32a locking protrusion 33 engagement protrusion 34 Retaining convex part 4 Engaging connector 4a Tubular part 41 Guide groove 42 Locking groove 5 Recovery rod 6 Core material 7 Grout G Ground H Drill hole O Axis r Casing pipe rotation direction T Drill hole tool

Claims (2)

Inside the ring bit provided at the front end of the casing pipe, a pilot bit provided with a recovery lock at the rear end is rotatably fitted in the axial direction in a constrained state or a non-restraint state. Using a drilling tool that
Applying a rotational force and a striking force to a casing pipe of the drilling tool and holding the pilot bit in the constrained state by the rotational reaction force and the digging resistance to excavate the ground;
Inside the casing pipe in the drilled hole formed, insert the recovery rod provided with the engagement connector at the tip to the recovery lock section of the pilot bit and insert the engagement connector into the recovery lock section Engaging the
Recovering the pilot bit from the ground by extracting the pilot bit unrestrained to the ring bit integrally with the recovery rod from the inside of the casing pipe;
Inserting the core material and injecting grout into the casing pipe after recovery of the pilot bit;
Leaving the core material in the borehole and withdrawing the casing pipe from the ground;
Sequentially through Ri,
The recovery locking portion of the pilot bit is provided with a locking protrusion projecting laterally on the rear end shaft portion along the axial direction,
The engaging connector of the recovery rod is a cylindrical portion which can be externally fitted to the rear end shaft portion of the pilot bit, a guide groove axially inserted from the front end, and a casing pipe rotating direction continuously from the guide groove And a locking groove extending in the circumferential direction opposite to that in FIG.
When recovering the pilot bit, the cylindrical part of the engagement connector is externally fitted to the rear end shaft of the pilot bit so that the locking projection is inserted into the guide groove, and then the recovery rod is twisted. The core material burying method is characterized in that the pilot bit is engaged with and connected to the recovery rod by causing the locking projection to shift from the guide groove to the locking groove side . The ring bit has a plurality of first convex wall portions equally spaced in the circumferential direction at an axially intermediate portion of the inner circumference, and a first inner circumferential portion on the tip end side of the first convex wall portions A plurality of second convex wall portions narrower in circumferential direction width than the convex wall portions are equally formed in the circumferential direction, and adjacent first convex wall portions form an axial insertion groove, and each first convex wall portion And each second convex wall portion is disposed so as to overlap in the axial direction and to be biased to the opposite side to the casing pipe rotation direction,
In the pilot bit, a plurality of engaging convex portions corresponding to the insertion groove of the ring bit are equally formed in the circumferential direction on the tip side of the outer periphery, and a circumferential width at which each engaging convex portion can pass through the insertion groove And a retaining projection is formed on the outer peripheral portion on the rear side of the engaging projections, and the non-restraint is performed at a rotational position where the engaging projection faces the insertion groove of the ring bit in the axial direction. state, and the constrained state by turning position disengaged from said insertion passage grooves, a core material embedded method of claim 1.

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