JPH06240969A - Expansion drilling method and device thereof - Google Patents

Abstract

PURPOSE:To drill an expansion hole with a specified tilt angle where a hole wall is unbreakable simply and speedily. CONSTITUTION:An inner tube 4 is installed in a swivel part 1 to be connected to a drive shaft, setting up a key part 4a on a peripheral surface of this inner tube 4, and an outer tube 5 formed with a keyway engaging with the key part 4a, on an inner circumferential surface is fitted in the axial direction. In succession, the outer tube 5 is connected to a body 6, a slide frame 3 is liftably fitted in this body 6 with some play, and then it is suspended from the swivel part 1 via two connecting rods 2 and 2. An expansion blade 13 is supported on a slide frame 3 retractably toward a hole wall 20, while the expansion blade 13 installs a screw rod 11 shiftably via a nut block 12, and this screw rod 11 is turned by means of rotation of a pinion 8 engaging with a rack 7 installed in the body 6. With this constitution, the expansion blade 13 rotates as gradually shifting toward the hole wall 20 in linkage with the down motion and rotation of the slide frame 3.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bottom-drilling method and apparatus for drilling a so-called bottom-drilling hole having a portion larger than the shaft diameter of a cast-in-place foundation pile.

[0002]

[Prior Art] On-site foundation piles for construction work,
There is a so-called bottom pile with a part larger than the shaft diameter,
The bottom hole may be drilled to obtain this bottom pile.
A bottom expanding excavator is used for excavating the bottom expanding hole.

A bottom-drilling excavator is a device that is inserted into an underground hole excavated with a predetermined diameter to expand and excavate the bottom of a hole in a radial direction, separately from an ordinary excavator that excavates a hole with a predetermined diameter. It is often created, but in order to save time and trouble of excavator replacement, after excavating an underground hole of a predetermined diameter, the excavating blade of the excavator rotates while gradually expanding in the radial direction. Has also provided a large number of combined excavators that enable continuous drilling of bottom holes.

It should be noted that the bottom expanding hole is relatively gentle in order to prevent the wall of the hole from easily collapsing even if a stabilizing solution is used, when excavating from an underground hole having a predetermined diameter at a steep angle. It is desirable to excavate a bottom hole that has a predetermined inclination angle (12 degrees or less) and gradually expands.

[0005]

However, the conventional bottom-drilling excavator is structurally complicated, and if an attempt is made to excavate the bottom-drilling hole having the predetermined inclination angle, the delicate and delicate operation is performed. However, there is a drawback in that it is not easy, quick and easy to excavate the bottomed hole while maintaining the predetermined inclination angle.

Therefore, the present invention provides a bottom expanding excavation method and apparatus capable of excavating a bottom expanding hole having a predetermined inclination angle at which the hole wall is hard to collapse easily, quickly and easily.

[0007]

According to the bottom expanding digging method of the present invention, the bottom expanding wing is gradually moved toward and away from the hole wall side in conjunction with the elevating operation of the bottom expanding excavator to dig a bottom expanding hole having a predetermined angle. It is characterized by

Further, the bottom expanding excavator according to the present invention is
The outer tube is fitted to the inner tube connected to the drive shaft so that it can be expanded and contracted and rotational torque can be transmitted, the body of a specified length is connected to the outer tube, and the slide frame is slidably engaged with the body and slides. It is characterized in that the bottom expanding blades are provided on the frame so as to be movable toward the hole wall, and the movement of the bottom expanding blades is interlocked with the movement of the slide frame that moves up and down along the body.

[0009]

When the Kelly bar is rotated in the reverse direction, the bottom expanding excavator is inserted into a pre-drilled underground hole of a predetermined diameter, and when the lower end of the outer pipe and body land on the hole bottom, the drive shaft is rotated forward. While the inner pipe sinks into the outer pipe, the rotational force is transmitted to rotate the outer pipe, body and slide frame,
The slide frame descends toward the bottom of the hole, and in conjunction with the lowering, the bottom expanding blade gradually moves toward the wall of the hole for excavation.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. 1 is a front view, and FIG. 2 is a cross-sectional plan view. In the figure, 1 is a swivel portion provided on an upper portion of an inner pipe 4 to which a drive shaft such as a kelly bar or a drill pipe is connected, 2 is a connecting rod whose upper end is pivotally supported by the swivel portion 1, and 3 is a connecting rod thereof. A slide frame 4 suspended from the lower end of 2 is an inner pipe rotatably connected to the swivel unit 1 about its axis.

The inner pipe 4 is fitted in the outer pipe 5 so as to be able to expand and contract in the axial direction, and the inner pipe 4 has a key portion 4a on the outer peripheral surface thereof and a key groove 5a described later formed on the inner peripheral surface of the outer pipe 5. The outer pipe 5 is integrally supported by the body 6, and the body 6 is engaged with the slide frame 3
Is fitted to. The body 6 has rack portions 7 and 7 projecting from each other on opposite sides with a predetermined length. A pinion 8 meshes with the rack portion 7, and a large gear 9 coaxial with the pinion 8 is pivotally supported by the slide frame 3.

A small gear 10 meshes with the large gear 9, and the small gear 10 is fixed to the end portion of a screw rod 11. The screw rod 11 has its axis attached to the axis of the body 6 at a predetermined inclination angle δ and is rotatably supported. A nut block 12 having a threaded portion that meshes with the threaded portion 11a provided on the inner peripheral surface thereof is fitted to the screw rod 11.

The nut block 12 is connected to the bottom expanding wing 13, and as shown in FIG. 4, a guide 14 having a substantially C-shaped cross section is fixed to the bottom expanding wing 13 while the guide 14 holds a T-shaped cross section. The rail 15 is fixed to the side wall of the slide frame 3, and the bottom expanding blade 13 is movably supported in parallel with the outer side portion of the slide frame 3. Excavation blades 16 are attached to the bottom expanding blade 13 on the lower side and the side surface.

A cross-shaped stabilizer blade 18 grounded to the hole bottom 17 is connected to the lower end portion of the body 6, and as shown in FIG. 3, the outer tube 5 located at the center of the lower portion of the stabilizer blade 18.
A fish tail 19 is connected to the lower end of the.
A stabilizer 21 that contacts the hole wall 20 is connected to the upper end of the outer tube 5.

The structure of the inner pipe 4 and the outer pipe 5 will now be described. As shown in FIG. 5, the outer peripheral surface of the inner pipe 4 is axially concentric with the inner pipe 4 and has key portions 4a, 4a. Are opposed to each other in the direction and are fixed at a predetermined inclination angle. As shown in FIG. 6A, the key portion 4a has a constant arc angle θ concentric with the inner pipe 4 on the outer peripheral surface of the inner pipe 4.

On the other hand, on the inner circumferential surface of the outer tube 5 in the lengthwise direction, there is fixed a cylindrical body 22 having key grooves 5a with which the key portions 4a engage, which are formed on the inner circumferential surfaces opposed to each other in the diametrical direction. An L-shaped lock portion 23 having a step portion 5b is formed on the inner peripheral surface of the cylindrical body 22, and a wide key groove 5a is formed for the upper half minute of the lock portion 23.
And a narrow inlet 5e is formed in the lower half.
As shown in FIG. 6 (A), the key groove 5a is axially formed on the inner peripheral surface of the outer tube 5, and the upper half (key groove 5a) is the key portion 4a.
The width of the arc angle β ₁ is about twice the arc angle θ of a, and the lower half (inlet 5e) is formed to have the width of the arc angle β ₂ substantially equal to the arc angle θ of the key portion 4a.

Further, the relationship between the key portion 4a and the key groove 5a is shown in FIGS. 7 and 8 as a development view as seen from the inside of the inner pipe 4. The dotted line in the figure represents the inner tube 4 and the key portion 4a on the outer peripheral surface thereof, and the solid line represents the outer tube 5 and the key groove 5a thereof. The keyway 5a has a horizontal step portion 5 located at approximately the middle height thereof.
The width is wider than b and the width is narrower in the lower part. Moreover, the key portion 4a and the key groove 5a have a common twist angle γ of about 11 to 13 degrees in a common direction in the axial direction of the inner tube 4 and the outer tube 5, respectively.

The size of the twist angle γ, especially the key portion 4a
The magnitude of the downward thrust force sufficient to cancel the sliding frictional force generated at the meshing portion at the time of transmitting the rotational torque due to the meshing between the key groove 5a and the key groove 5a is Qμ = R, tanγ =
R / Q = μ (where Q is the normal force component of the rotational force P, R is the tangential force component, and μ is the friction coefficient).

The operation of the above-described embodiment will be described. After drilling an underground hole having a predetermined diameter with an appropriate excavator in advance, the excavator is pulled out and, as shown in FIG. The section is connected to a drive shaft (not shown) and replaced with a bottom-drilling excavator for suspension, and the bottom-drilling excavator is rotated in the reverse direction (direction b in the arrow in FIG. 6A) by a kelly bar while discharging the slime. Insert into the bore. That is, by the reverse rotation of the kelly bar,
As shown in FIG. 7, the key portion 4a of the inner pipe 4 is engaged with the left edge portion 5c while the lower end of the key portion 4a is in contact with the step portion 5b of the key groove 5a of the outer pipe 5, so that Rotation in the same direction (arrow b) is transmitted, but the lowering of the inner pipe 4 is blocked.

Then, as shown in FIG. 1, when the fish tail 19 and the stabilizing blade 18 land on the hole bottom 17, the kelly bar is switched to the forward rotation (direction a in FIG. 6B). That is, the forward rotation of the kelly bar causes the key portion 4a of the inner tube 4 to come into contact with the right edge 5d of the key groove 5a of the outer tube 5 as shown in FIG. At the same time that the rotation (arrow a) is transmitted, it is aligned with the lower half inlet 5e of the keyway 5a, and is ready to enter.

Then, when a downward thrust is applied to the inner pipe 4, the inner pipe 4 descends in the direction of arrow c. At this time, a downward thrust R (tangential component force) is generated at the meshing portion between the key portion 4a and the edge portion 5d of the key groove 5a due to the twist angle γ, and the sliding frictional force Qμ of the meshing component force is offset. To do.

Thus, by the forward rotation of the kelly bar, the inner tube 4 gradually enters into the outer tube 5 while rotating, and the slide frame 3 and the body 6 rotate integrally with the rotation of the outer tube 5, and further, slide. The frame 3 descends by its own weight along the body 6. When the slide frame 3 descends along the body 6, the pinion 8 meshing with the rack portion 7 rotates, and the large gear 9 rotates, whereby the small gear 10 rotates and the screw rod 11 rotates about the axis.

Therefore, the nut block 12 that meshes with the screw rod 11 moves along the screw rod 11, and the bottom expanding blade 13 comes into contact with the hole wall 20 and gradually moves in the radial direction while excavating. Then, as shown in FIG. 9, when the bottom expanding blade 13 reaches the hole bottom 17, the nut block 12 stops at the end of the screw rod 11.
A stopper with which the nut block 12 abuts may be provided at the end of the screw rod 11.

Thus, as the slide frame 3 descends, the bottom expanding blade 13 gradually moves toward the hole wall, and
Due to the rotation of the outer pipe 5, the body 6 and the slide frame 3 caused by the rotation of the inner pipe 4, a bottomed hole 23 having a predetermined angle α is formed in the excavating blade 16.

When the bottom expanding blade 13 moves toward the hole wall 20, the screw rod 11 engaged with the nut block 12 is easily opened by the component force of the excavation resistance received by the bottom expanding blade 13 at a predetermined angle δ. Because it is tilted at
Excessive load is not applied to the screw engaging portions of the nut block 12 and the screw rod 11. Further, when the inner pipe 4 and the outer pipe 5 expand and contract due to the excavation resistance received by the slide frame 3, the inner pipe 4 rotates because the key groove is inclined, but is absorbed by the swivel portion 1 spinning. .

Then, when the bottom expanding blade 13 reaches the bottom of the hole and the excavation of the bottom expanding hole 17 is completed, the drive shaft is rotated in the reverse direction again to move the inner pipe 4 upward from the outer pipe 5, and the connecting rod 2 is passed through. As the slide frame 3 rises along the body 6, the pinion 8 engaging with the rack portion 7 rotates in the opposite direction to the above, and the screw rod 11 rotates in the opposite direction to the above to expand the bottom blade 13 into a hole. It moves from the wall side to the slide frame 3 side and returns to the initial state shown in FIG. Then, the bottom expanding excavator is pulled out from the underground hole.

It goes without saying that the present invention can be used not only in the reverse circulation construction method but also in the earth drill construction method.

[0028]

According to the present invention described above, since the bottom expanding blade automatically advances and retreats in the direction of the hole wall in conjunction with the elevating operation of the slide frame, the bottom wall of the hole wall against the excavation depth due to the weight drop of the slide frame. The inclination angle can always be maintained at a predetermined value, and therefore, it is possible to easily excavate a bottomed hole having a predetermined inclination angle. Moreover, since no special drive means such as a hydraulic device for moving the bottom spreading blade is required,
Highly economical. Moreover, the structure is relatively simple and inspection and repair are easy.

[Brief description of drawings]

FIG. 1 is a front view showing an embodiment of the present invention.

FIG. 2 is a sectional view taken along line AA of FIG.

FIG. 3 is a partial bottom view of FIG.

FIG. 4 is a partial side view of FIG.

FIG. 5 is a perspective exploded partial cutaway perspective view of an inner pipe and an outer pipe.

FIG. 6 is a sectional view showing a relationship between a key portion and a key groove.

FIG. 7 is a development view showing a relationship between a key portion and a key groove.

FIG. 8 is a development view showing a relationship between a key portion and a key groove.

FIG. 9 is an operation explanatory view.

[Explanation of Codes] 1 ... Swivel part 2 ... Connection rod 3 ... Slide frame 4 ... Inner pipe 4a ... Key part 5 ... Outer pipe 5a ... Key groove 6 ... Body 7 ... Rack part 8 ... Pinion 9 ... Large gear 10 ... Small Gear 11 ... Screw rod 12 ... Nut block 13 ... Bottom blade 14 ... Guide 15 ... Rail 16 ... Excavation blade 17 ... Hole bottom 18 ... Stabilizer blade 19 ... Fish tail 20 ... Hole wall 21 ... Stabilizer

Claims (2)

[Claims] 1. A bottom expanding excavation method, which comprises excavating a bottom expanding hole having a predetermined angle by moving a bottom expanding blade progressively forward and backward toward the hole wall side in conjunction with a lifting operation of a bottom expanding excavator. 2. An outer pipe is fitted to an inner pipe connected to a drive shaft so that the outer pipe can expand and contract and rotational torque can be transmitted, a body of a predetermined length is connected to the outer pipe, and a slide frame can slide on the body. A bottom expanding digging device, characterized in that the bottom expanding blade is engaged with the slide frame so as to be movable toward the hole wall, and the movement of the bottom expanding blade is interlocked with the movement of the slide frame that moves up and down along the body.