JP4738075B2 - Pipe installation method and drilling device - Google Patents

Description

  The present invention relates to a pipe installation method and a hole drilling device, and more specifically, for example, a method of installing an injection pipe for injecting grout in a ground improvement work in the ground and a suitable cutting method for carrying out the method. The hole device

  In recent years, unnecessary drainage of groundwater is also restricted in tunnel construction from the viewpoint of protecting the natural environment. Under such circumstances, when a soft ground is encountered during tunnel construction, ground improvement work may be required as an auxiliary construction method before tunnel excavation. As one of the ground improvement works, a method is known in which after drilling a boring hole in a ground to be excavated, the boring rod is extracted, and a grout injection pipe is inserted into the boring hole to inject grout. In particular, the injection pipe is provided with a large number of injection holes at a predetermined pitch, a check valve made of a rubber sleeve is provided on the outer periphery thereof, and a grout supply pipe equipped with a double packer is inserted into the injection pipe to gradually grout the injection pipe. The method of discharging the ink is known as the Solentans method (see, for example, Patent Document 1).

  In such ground improvement works, the natural ground that is required for this is originally a collapsible ground and has a large amount of spring water, so the bored hole wall collapses and the injection pipe is cut by the spring water. Insertion may become impossible. In such a case, it is conceivable to apply a double pipe excavation method in which an injection pipe is an outer pipe, a bore hole is excavated by a double pipe having a bit attached to the inner pipe, and the inner pipe is pulled out.

However, in the case of this double pipe excavation method, since the injection pipe having a rubber check valve is used as the outer pipe, the outer pipe cannot be moved back and forth during excavation, and the swarf can be discharged smoothly. Not only is there a drawback, but the check valve may be damaged. Furthermore, the double-pipe excavation method has a problem that the work of adding and detaching the pipe is complicated and the workability is poor.
JP-A-61-186613

The present invention has been made based on the technical background as described above, and achieves the following object.
An object of the present invention is to install a pipe on a ground that is collapsible and has a large amount of spring water, and can smoothly perform excavation and subsequent pipe installation and, for example, a member attached to a pipe such as a rubber sleeve An object of the present invention is to provide a tube installation method and a hole drilling device that are not damaged.

The present invention employs the following means in order to achieve the above object.
That is, the present invention includes a step of excavating the ground by a drilling device in which a bit is detachably attached to a tip portion of a boring rod;
Releasing the engagement between the bit and the boring rod after excavating to a predetermined position;
Inserting a tube provided with a piston slidable on the inner periphery of the boring rod at the rear end until the tip abuts the bit in the boring rod ;
And a step of pulling out the boring rod while applying fluid pressure to the piston while leaving the bit and the pipe in the ground.

  In the above construction method, it is possible to adopt a mode in which the engagement between the bit and the boring rod is released by inserting the pipe. Further, the engaging portion between the bit and the boring rod is composed of a first engaging portion and a second engaging portion. By inserting a release member into the boring rod, the engaging portion of the first engaging portion is inserted. It is possible to adopt a mode in which the engagement of the second engagement portion is released by releasing the engagement and pulling out the boring rod.

  Moreover, in the said construction method, it is good for the said piston to be provided with the annular ratchet which a nail | claw faces the back of the said pipe | tube and can bite into the inner periphery of the said boring rod.

  In the above method, a check valve is incorporated in the bit. The pipe is a ground improvement grout injection pipe.

Further, the present invention is a drilling device comprising a boring rod and a bit fitted and attached to the inner periphery of the tip of the boring rod,
A clamp mechanism for holding the bit on the inner periphery of the boring rod so as to be freely disengaged;
A torque transmission mechanism for transmitting rotational torque from the boring rod to the bit;
The drilling device is characterized in that an annular stepped portion is provided on the outer periphery of the bit to engage the tip of the boring rod and transmit the feeding force.

More specifically, the bit comprises a bit body, and a bit sub that is fixed to the inner periphery of the boring rod with a tip end fixed to the bit body and a rear portion.
The clamp mechanism is provided on the bit sub, and includes a latch claw that can be engaged and disengaged on an inner periphery of the boring rod.
The torque transmission mechanism may employ a structure provided at a fitting portion between the boring rod and the bit sub.

Further, the bit comprises a bit body having a cylindrical portion fitted to the boring rod at a rear portion, and a bit sub fitted to the inner periphery of the cylindrical portion of the bit body,
The clamp mechanism is provided in the bit sub, and is accommodated in a latch claw that is detachably engageable with an inner periphery of the boring rod, and a through hole provided in a peripheral wall of the cylindrical portion of the bit body. By engaging, it consists of an engagement piece that protrudes radially outward and engages the inner periphery of the boring rod,
The torque transmission mechanism may employ a structure including the engagement pieces. In this case, it is preferable that the engaging piece has a forward tapered surface on the outer periphery. In each of the above structures, a check valve is incorporated in the bit.

  According to the present invention, the pipe is inserted into the boring rod after excavation, and the boring rod is pulled out while leaving the bit and the pipe. Then, the subsequent pipe can be installed smoothly, and the member attached to the pipe such as a rubber sleeve is not damaged.

  Embodiments of the present invention will be described below with reference to the drawings. FIG.1 and FIG.2 is a construction procedure figure which shows embodiment of this invention construction method. As shown in FIG. 1 (a), a mouth apparatus 1 having packers 1a and 1b on the front and back of a natural ground surface where excavation is started and a drainage port 1c for drilling water at the center is installed. First, it excavates to a predetermined position with the drilling apparatus which consists of the boring rod 2 penetrated by the mouth apparatus 1, and the bit 3 with which the front-end | tip is mounted | worn. At the time of excavation, a water swivel 4 is attached to the rear end of the boring rod 2, and a drill head (not shown) is connected to the water swivel 4, and feed force and rotational force are transmitted from the drill head to the boring rod 2.

  Further, during excavation, drilling water is supplied to the water swivel 4, and the drilling water is poured from the tip of the bit 3 through the inside of the boring rod 2. At this time, the front packer 1a is “open” and the rear packer 1b is “closed”, and the drilling water accompanied by the swarf passes between the boring rod 2 and the drilling hole wall and is discharged from the drain port 1c. The

  Here, the detailed structure of the tip of the boring rod 2 to which the bit 3 is attached will be described with reference to FIG. As shown in FIG. 2A, the boring rod 2 is composed of unit rods 5 that are sequentially added along with excavation and a rod sub 11 that is connected to the leading unit rod 5 by screws 10. On the other hand, the bit 3 includes a bit body 12 and a bit sub 14 connected to the outer periphery of the bit body by a screw 13. Drilling water passages 15 and 16 are formed in the bit body 12 and the bit sub 14 along the axial direction, respectively.

  An annular stepped portion 17 is formed on the outer periphery of the intermediate portion of the bit sub 14, and a rear portion 18, which is a rear portion of the stepped portion 17, is fitted to the inner periphery of the rod sub 11. A fitting portion 19 between the rear portion 18 of the bit sub 14 and the rod sub 11 has a fitting structure of a spline or a polygonal portion. A stepped portion 32 is further formed in the rear portion 18 of the bit sub 14, and a slit 20 penetrating in the radial direction is formed in a portion rearward of the stepped portion 32. A pair of latch claws 22, 22 constituting a clamp mechanism is incorporated in the slit 20. One end of each of the latch claws 22 and 22 is pivotally supported by a pin 23 and is biased by a spring 24 so that each other end is always expanded. An annular recess 25 is formed on the inner periphery of the rod sub 11, and the other ends of the latch claws 22, 22 are engaged with the annular recess 25 in an expanded state.

  The bit body 12 has a cutting tip 25 on the tip surface, and an extraction channel 26 communicating with the channel 15 is opened on the tip surface. A check valve 27 is incorporated in the bit body 12. In this embodiment, the check valve 27 urges the ball 28 as a valve body, a sleeve 29 that defines a movement path of the ball 28, an annular valve seat 30, and the ball 28 toward the valve seat 30. It consists of a spring 31. The check valve 27 does not cause the drilling fluid to flow back, and spring water does not enter the injection pipe 35 even after the injection pipe 35 described later is inserted.

  In the drilling device having the above structure, the latch claws 22 and 22 constituting the clamp device are engaged with the inner periphery of the rod sub 11, whereby the bit 3 is held by the boring rod 2. Therefore, during excavation, it is possible to move the boring rod 2 back and forth to promote the discharge of digging waste. On the other hand, the excavation torque is transmitted to the bit 3 through the fitting portion 19 between the bit sub 14 and the rod sub 11. The feeding force is transmitted to the bit 3 through the stepped portion 17 with which the tip end of the rod sub 11 is engaged. Further, the drilling water supplied into the boring rod 2 opens the check valve 27 against the spring 31 through the flow path 16 and passes through the flow path 15 and the extraction flow path 26 to the tip of the bit 3. Supplied.

  Now, referring again to FIG. 1, when excavating to a predetermined position, as shown in FIG. 1B, the front packer 1 a is “closed” and the other part of the mouth apparatus 1 is removed except for this part. . Then, a grout injection tube 35 is inserted into the boring rod 2. As shown in FIG. 3 (b), the injection tube 35 is inserted until its tip abuts against the stepped portion 32 of the bit sub 14, and when inserted to that position, the latch claws 22 and 22 are forcibly closed, The engagement between the latch claw and the rod sub 11 is released. As a result, it is possible to draw only the boring rod 2 while leaving the bit 3 and the injection pipe 35.

  Therefore, the boring rod 2 is pulled out. However, since the injection pipe 35 is merely in the boring rod 2, the water pressure acts on the bit 3 particularly in the case of ground having a large amount of spring water. Therefore, the bit 3 and the injection pipe 35 may come out of the excavation hole along with the boring rod 2. In order to prevent this, as shown in FIG. 1 (b), a piston 36 is attached in advance to the rear end of the injection tube 35, and after the insertion of the injection tube 35 is completed, as shown in FIG. 1 (c). As shown, the water swivel 4 is mounted again at the rear end of the boring rod 2.

  Then, as shown in FIG. 2 (d), a fluid such as water or air is supplied from the water swivel 4 into the boring rod 2 and a fluid pressure is applied to the piston 36, that is, while the injection pipe 35 is pressed. Pull out the rod 2. Thereby, the injection tube 35 does not come out with the boring rod 2.

  Here, the detailed structure of the piston 36 will be described with reference to FIG. The piston 36 includes a piston main body 37 and a cylindrical coupler 38 fixed to the front surface thereof. A joint pipe 39 is fixed to the rear end of the injection pipe 35, and the coupler 38 is rotatably fitted to the outer periphery of the joint pipe 39 via a bearing 40. The piston body 37 is an annular member, and a seal member 41 is provided on the outer periphery so that the inner periphery of the boring rod 2 can slide in the axial direction. A cap 42 for closing the opening is detachably attached to the rear end of the piston main body 37.

  Now, referring again to FIG. 2, when the boring rod 2 is pulled out and the rod sub 11 reaches the vicinity of the front packer 1a of the mouth apparatus as shown in FIG. 2 (e), the rod sub 11 and the rod sub 11 are connected thereto. The drawing is completed with the short unit rod 5 remaining (see also FIG. 3C).

  Then, as shown in FIG. 5F, the water swivel 4 is removed, and as shown in FIG. 5G, the cap 42 (see FIG. 4) of the piston 36 is removed, and the grout is grounded through the injection pipe 35. inject.

  FIG. 6 shows an example of grout injection. When grout injection is performed in the same manner as the Solentans method, injection holes are provided in the injection pipe 35 at a predetermined pitch in the length direction, and a rubber sleeve (check valve) is provided on the outer periphery of the injection hole 70. 71 is attached. At the time of grouting, a supply pipe having a double packer (not shown) is inserted into the injection pipe 35, and both sides of the injection hole 70 are packed and the grout supplied from the supply pipe is discharged from the injection hole 70.

  FIG. 5 is a cross-sectional view showing another embodiment of the piston 36. In this embodiment, the piston main body 37 has a tapered cylindrical portion 43 whose outer diameter gradually decreases toward the rear end at the rear portion. An annular ratchet 45 supported by a spring 44 on the front and rear is fitted to the outer periphery of the tapered cylindrical portion 43 so as to be movable in the axial direction.

  The pawl 46 of the ratchet 45 faces the back of the injection tube 35. Therefore, when the boring rod 2 is pulled out, the pawl 46 does not bite into the inner periphery of the boring rod 2, and the boring rod 2 can be pulled out. On the other hand, when the water swivel 4 is removed after the boring rod 2 has been pulled out (the state shown in FIG. 2 (f)), when the force F that pulls out of the drilling hole is applied to the injection pipe 35, the claw 46 is short. It tries to bite into the inner circumference of the rod 5. For this reason, it is possible to prevent the injection pipe 35 from coming out of the excavation hole. Such a piston structure is effective for construction on the ground where the amount of spring water is large and a large water pressure acts on the bit 3.

  FIG. 7 is a cross-sectional view showing another embodiment of the hole drilling device. As shown in FIG. 5A, the point that the bit 3 is composed of the bit body 12 and the bit sub 14 is the same as in the above embodiment. In this embodiment, an annular stepped portion 50 is formed on the outer periphery of the bit body 12, and the bit body 12 has a cylindrical portion 51 that is fitted to the inner periphery of the rod sub 11 behind the stepped portion 50. is doing. The bit sub 14 has a cylindrical shape that forms the drilling fluid flow path 16 therein, and has a small-diameter portion 52 fitted to the cylindrical portion 51 of the bit body 12 at the front portion.

  The bit sub 14 is formed with a slit 20 penetrating in the radial direction. A pair of latch claws 53, 53 constituting a clamp mechanism are incorporated in the slit 20. Each latch claw 53 has a substantially L shape having two claw portions 53a and 53b, and is pivotally supported by a pin 54 at the base portion. The pair of latch claws 53 and 53 are always urged so that the one claw portions 53a and 53a are expanded by the spring 55 and the other claw portions 53b and 53b are closed. The claw portions 53a and 53a are engaged with an annular recess 25 formed on the inner periphery of the rod sub 11 in the expanded state.

  A plurality of through holes 56 are provided in the circumferential wall of the cylindrical portion 51 of the bit body 12 at intervals in the circumferential direction, and an engagement piece 57 is accommodated in the through hole 56. The engagement piece 57 projects radially outward from the through hole 56 by fitting the small diameter portion 52 of the bit sub 14 into the cylindrical portion 51, and is engaged with an annular recess 58 provided on the inner periphery of the rod sub 11. It comes to match. The engagement piece 57 has a tapered surface 59 facing forward on the outer periphery. In addition, the check valve 27 is incorporated in the bit 3 in the same manner as in the above embodiment, and the same reference numerals are given to the same members.

  In the case of this embodiment, the clamp mechanism is composed of first and second engaging portions, and the pair of latch claws 53 and 53 and the engaging piece 57 correspond to the first and second engaging portions, respectively. The bit 3 is held by the boring rod 2 by this clamping mechanism. Therefore, as in the case of the above embodiment, during excavation, it is possible to move the boring rod 2 back and forth to promote the discharge of digging waste. On the other hand, the excavation torque is transmitted from the rod sub 11 to the bit 3 through the engagement piece 57. The feeding force is transmitted to the bit 3 through the stepped portion 50 with which the tip of the rod sub 11 is engaged.

  In order to install the injection pipe 35, after the excavation (the state shown in FIG. 1A), as shown in FIG. 7A, the disengaging member (spear and spear) having a protrusion 60 at the tip in the boring rod 2 is used. 61) is inserted, the projection 60 is engaged with one of the claw portions 53b and 53b of the latch claw 53 and 53, and the space between both the claw portions 53b and 53b is expanded. As a result, the other claw portions 53a and 53a rotate in a direction to close each other, and the engagement between the claw portions 53a and 53a and the rod sub 11 is released (release of the first engagement portion). Next, when the engagement releasing member 61 is pulled out, the small diameter portion 52 of the bit sub 14 is pulled out from the tubular portion 51 of the bit body 12, and the bit sub 14 is pulled out along with the engagement releasing member 61. The state where the bit sub 14 is pulled out is shown in FIG.

  Next, as shown in FIG. 7C, the injection tube 35 is inserted into the boring rod 2 until the tip comes into contact with the cylindrical portion 51 of the bit body 12. Then, as shown in FIGS. 1C and 1D, the boring rod 2 is pulled out while applying fluid pressure to the rear end piston 36 of the injection pipe 35. When the pulling operation is performed, as shown in FIG. 7 (d), the outer periphery of the engaging piece 57 has a tapered surface 59, so that the engaging piece 57 is formed in the cylindrical shape of the bit body 12 by pulling out the boring rod 2. It is pushed into the part 51. That is, the engagement between the engagement piece 57 and the rod sub 11 is released (release of the second engagement portion), and the boring rod 2 can be pulled out. The steps after the boring rod 2 is pulled out are exactly the same as in FIGS. 1 (e), (f), and (g).

  In the case of the construction method using the hole drilling device of this embodiment, an original process for releasing the engagement of the latch claws 53 and 53 is required, and the number of processes is larger than that of the above-described embodiment, but the bit sub 14 is recovered. There is an advantage that you can. Further, since the bit 3 is held by the rod sub 11 by the clamp mechanism having the first and second engaging portions, there is an advantage that the bit 3 does not rattle even if the boring rod 2 is moved back and forth.

  The above embodiment is merely an example, and the shape of the bit, the structure of the clamp mechanism, and the like can take various forms, and the present invention is not limited to the above embodiment. The present invention can be applied not only to an injection pipe for grout injection but also to a general pipe installation method such as a strainer pipe.

It is a construction procedure figure which shows embodiment of this invention construction method. It is a construction procedure figure following FIG. It is sectional drawing which shows the detail of a drilling apparatus. It is sectional drawing which shows the detail of a piston. It is sectional drawing which shows another embodiment of a piston. It is sectional drawing which shows an example of injection construction. It is sectional drawing which shows another embodiment of a hole drilling apparatus.

Explanation of symbols

1 Neck device 1a Front packer 1b Rear packer 1c Drain port 2 Boring rod 3 Bit 4 Water swivel 5 Unit rod 11 Rod sub 12 Bit body 14 Bit sub 17 Stepped portion 19 Fitting portion 20 Slit 22 Latch claw 27 Check valve 28 Ball 35 Injection pipe 36 Piston 37 Piston body 38 Tubular coupler 40 Bearing 41 Seal member 42 Cap 43 Tapered tubular portion 45 Annular ratchet 46 Claw 50 Stepped portion 51 Tubular portion 52 Small diameter portion 53 Latch claw 56 Through hole 57 Engagement piece 58 Annular recess 59 Tapered surface 60 Projection 61 Disengagement member

Claims (10)

A step of excavating the ground with a drilling device in which a bit is detachably attached to the tip of the boring rod;
Releasing the engagement between the bit and the boring rod after excavating to a predetermined position;
Inserting a tube provided with a piston slidable on the inner periphery of the boring rod at the rear end until the tip abuts the bit in the boring rod ;
And a step of pulling out the boring rod while applying fluid pressure to the piston while leaving the bit and the pipe in the ground.   The pipe installation method according to claim 1, wherein the engagement between the bit and the boring rod is released by inserting the pipe.   The engaging portion between the bit and the boring rod is composed of a first engaging portion and a second engaging portion, and the first engaging portion is engaged by inserting a release member into the boring rod. 2. The pipe installation method according to claim 1, wherein the engagement of the second engaging portion is released by releasing the bore and pulling out the boring rod.   The pipe installation method according to claim 1, 2 or 3, wherein the piston is provided with an annular ratchet in which a claw faces the rear of the pipe and can bite into an inner periphery of the boring rod.   The pipe installation method according to any one of claims 1 to 4, wherein a check valve is incorporated in the bit.   The pipe installation method according to any one of claims 1 to 5, wherein the pipe is an injection pipe for a ground improvement grout. A drilling device comprising a boring rod and a bit fitted and attached to the inner periphery of the tip of the boring rod, wherein the drilling device is used in the pipe installation method according to any one of claims 1 to 6 ,
A clamp mechanism for holding the bit on the inner periphery of the boring rod so as to be freely disengaged;
A torque transmission mechanism for transmitting rotational torque from the boring rod to the bit;
A drilling device characterized in that an annular stepped portion is provided on the outer periphery of the bit to transmit a feeding force by engaging a tip of the boring rod. The bit is composed of a bit body, and a bit sub whose front end is fixed to the bit body and whose rear portion is fitted to the inner periphery of the boring rod,
The clamp mechanism is provided on the bit sub, and includes a latch claw that can be engaged and disengaged on an inner periphery of the boring rod.
The hole drilling device according to claim 7, wherein the torque transmission mechanism is provided in a fitting portion between the boring rod and the bit sub. The bit comprises a bit body having a cylindrical portion fitted to the boring rod at a rear portion, and a bit sub fitted to an inner periphery of the cylindrical portion of the bit body,
The clamp mechanism is provided in the bit sub, and is accommodated in a latch claw that is detachably engageable with an inner periphery of the boring rod, and a through hole provided in a peripheral wall of the cylindrical portion of the bit body. By engaging, it consists of an engagement piece that protrudes radially outward and engages the inner periphery of the boring rod,
The drilling device according to claim 7, wherein the torque transmission mechanism includes the engagement piece.   The drilling device according to claim 9, wherein the engagement piece has a forward-facing tapered surface on an outer periphery.

Images