JP5191071B2 - Drilling method - Google Patents

Description

  The present invention relates to a drilling method in an excavator having an auger head equipped with an enlarged head, and more particularly, excavation in an excavator capable of easily confirming the diameter of a drilled hole and the continuity of the hole wall drilled by an enlarged blade of an auger head Regarding the method.

In the construction of buildings with high vertical loads, such as high-rise buildings, foundation works such as pile foundation construction in which piles are placed on the ground on which the building is constructed are carried out in order to improve the durability and seismic strength of the building. Yes.
In this pile foundation construction, a field construction pile construction method in which reinforcing bars are placed in the excavated excavation hole (pile hole) and concrete is filled, a pre-boring method in which an existing pile is built in the excavation hole, and a pile hole is excavated However, the medium digging method is adopted in which the existing piles are gradually lowered into the pile holes and built.

When building piles using these pre-boring methods and medium excavation methods, in order to improve the bearing capacity of the foundation pile, the diameter of the bottom of the pile hole, etc. is expanded and excavated, and an expanded root-solidified part is provided in the root-solidified part. It is being built to increase the tip area of the pile.
In order to excavate the small-diameter pile hole and the large-diameter pile hole, there is known an enlarged rooting method in which the enlarged head at the tip of the excavating rod of the excavator is expanded to construct an enlarged rooting part (patent) Reference 1).
In this expansion consolidation method, the current value or integrated current value of the motor that rotates the excavating rod of the drive unit is measured, and the current value / integrated current value at the time of excavation before the expansion process and the current at the expansion excavation process after the blade expansion When the increase ratio of the current value / integrated current value during expanded excavation becomes larger than the set value, it may be determined that the expanded head has expanded. A method of judging that the expansion process is completed when it is moved repeatedly and the current value / integrated current value in the vertical movement repeating process decreases and approaches the current value / integrated current value at the time of excavation before the expansion process becomes stable. The method is taken.

  However, with this technique or method, it is possible to confirm whether or not the expanded excavation has been performed, but when excavating the expansion hole at the bottom, the operator has an expanded excavation diameter preset by the expansion head from the ground. It is not possible to confirm whether or not.

In order to solve this problem, the cast-in-place concrete pile construction method is used, but the excavation arm can be swung on the auger head by detecting the swinging angle of the excavating arm with a sensor. A method for confirming the position of a pile hole excavation head that can grasp the size of the excavation diameter of the auger head at a depth is known (see Patent Document 2).
However, in this position confirmation method, from the sensor for detecting the swing angle of the excavating arm and the data obtained by the sensor, the swing angle of the excavating arm and the size of the excavating diameter of the auger head are grasped. A data processing device is required. In addition, the method for confirming the position of the pile hole excavation head has a problem that not only the error is large because the angle is converted to a diameter, but also the cost is high.

  In addition, when excavating a pile hole as described above, when confirming whether the excavated pile hole has the target diameter, simply grasping the size of the auger head excavation diameter However, the excavation diameter of the auger head does not necessarily become the diameter of the pile hole to be excavated as it is, and therefore it cannot be sufficiently confirmed by itself. Further, this position confirmation method cannot confirm the continuity of the hole wall of the enlarged portion.

On the other hand, in order to confirm whether the excavated pile hole has the desired diameter, an ultrasonic distance detector is suspended in the pile hole with a wire, and ultrasonic waves are transmitted from the ultrasonic distance detector to the hole wall. Also known is a hole wall shape measuring device that detects ultrasonic waves emitted and reflected, detects the distance from the ultrasonic distance detector to the hole wall, and measures the state of the hole wall, that is, the diameter of the pile hole. (See Patent Document 3).
If the diameter of the pile hole is measured with this hole wall shape measuring device, the operator can confirm the portion where the excavation is insufficient based on the measurement result, and the unevenness on the surface of the hole wall can be eliminated. it can.

  However, when performing measurement with this hole wall shape measuring device, the auger head is once lifted to the ground during or after excavation, and then the ultrasonic distance detector is suspended in the pile hole to form the shape of the hole wall. Therefore, when it is determined that the hole diameter is insufficient, it is necessary to insert the auger head into the excavation hole again and resume excavation. Therefore, when this hole wall shape measuring apparatus is used, not only the apparatus itself is costly but also labor is required and the work period is extended. In addition, since the hole wall is checked in a non-contact manner using an ultrasonic sensor, there is another problem that the error may be large.

JP 2008-127938 A JP 2008-150834 A JP-A-8-68620

  The present invention has been made to solve the above-described conventional problems, and its purpose is to confirm the excavation diameter of the expanding blade and the continuity of the hole wall easily and in a short time without cost and labor. It is possible to drill a hole having a diameter larger than that of the drilled hole concentrically with the drilled hole, and to check and repair the drilling failure of the large diameter drilled hole at the same time. Is to do.

The present invention includes an auger head having an enlargement head having a pair of enlargement blades capable of expanding and reducing the excavation diameter, an excavation rod connected to the auger head, and an excavation rod driving means for rotating the excavation rod about an axis. An outer rod that rotates integrally with the excavating rod and operates an expansion / contraction mechanism that expands / contracts the expansion head by axial displacement, an outer rod driving unit that displaces the outer rod in the vertical direction, and the outer rod A guide member that moves up and down along the excavating rod according to the vertical movement thereof, and the expansion and contraction mechanism that expands and contracts the expansion blade according to the vertical movement of the guide member and expands and contracts the excavation diameter of the expansion head; The outer rod is a drilling method in a drilling apparatus having a marking indicating the displacement of the outer rod at a predetermined position, and the expansion head is not positioned at the expansion position. A step of moving in the direction of the wellbore while rotating the drill hole in a state set by a constant, in the step, when the outer rod is relatively positional displacement relative to the drill rod, with the enlarged head And re-excavating the excavation hole.

  According to the present invention, it is possible to easily and quickly excavate a drill hole having a predetermined large diameter concentrically with the excavated drill hole without incurring costs. In addition, since inspection of a drilling hole after drilling and confirmation of continuity of a hole wall can be performed using the same expansion head for drilling, inspection and repair can be performed simultaneously.

It is the schematic side view which showed an example of the excavation apparatus. It is an enlarged side view of an auger head. It is an enlarged side view of a hydraulic jack and an outer rod. It is a figure explaining the excavation procedure of the large diameter hole using an excavator. It is a figure which shows the procedure which test | inspects the already formed large diameter hole. It is a figure which shows the procedure of hole wall finishing of a large diameter hole.

Hereinafter, excavation methods according to embodiments of the present invention will be described with reference to the accompanying drawings.
FIG. 1 is a schematic side view showing an example of an excavation apparatus M that implements the excavation method according to the present embodiment.
As shown, the excavator M includes a pile driver (base machine) 1, an auger head 7 for excavating the ground, a pile driver leader 2 for positioning the auger head 7 and moving the excavator up and down. A driving unit 3 such as an electric motor for applying a rotational force to the auger head 7, a drilling rod 4 for transmitting the rotational force of the driving unit 3 to the auger head 7 and applying a propulsive force, and the horizontal of the drilling rod 4 A pair of outer rods 8 arranged symmetrically along the outer periphery of the excavating rod 4 in order to expand and contract the steady rest 5 for preventing the deflection in the direction and an expansion head 73 (see FIG. 2) of the auger head 7 which will be described later. And.

The pile driver 2 is vertically supported by the pile driver 1, and is attached to the drive unit 3 on a guide rail 2a on the front surface of the pile driver 2 so as to be movable up and down.
The drive unit 3 has a wire rope 11a from a winch 11 installed in the pile driving machine 1 connected to the upper part, and the winch 11 winds up or unwinds the wire rope 11a, whereby the pile driving machine leader 2 The guide rail 2a is moved up and down.
Moreover, the drive part 3 is provided with the output shaft 3a for transmitting rotational force to the excavation rod 4 in the lower end part, and this output shaft 3a has the hydraulic jack 20a which moves the pair of outer rods 8 in the axial direction. A hydraulic swivel 20 is attached integrally. Therefore, the hydraulic swivel 20, the hydraulic jack 20a, and the pair of outer rods 8 rotate together with the excavating rod 4, that is, integrally with the rotation of the output shaft 3a.

The excavation rod 4 has an auger head 7 connected to its tip, and propels the auger head 7 from the tip toward the ground toward the ground and discharges excavated earth and sand to the outside (ground). A spiral wing 6 is provided.
The outer rod 8 is disposed along the excavation rod 4 through the spiral blade 6 at symmetrical positions on both sides of the excavation rod 4 (in the front-rear direction in the drawing). Moreover, the upper end part of the outer rod 8 is connected with the hydraulic jack 20a. When the hydraulic jack 20a is operated by the hydraulic pressure supplied from the hydraulic swivel 20, the outer rod 8 is lowered or raised.

  The outer rod 8 rotates simultaneously with the excavation rod 4 (shaft 71) by the output shaft 3a of the electric motor 3 of the drive unit 3, and moves up and down by the hydraulic jack 20a while rotating together with the excavation rod 4, and the auger head 7 will be described later. The enlargement head 73 (enlargement blade 73a) (see FIG. 2) is enlarged or reduced. Next, the expansion / contraction operation of the expansion blade 73a will be described.

2 is an enlarged side view of the auger head 7. FIG. 2A shows a state in which the enlargement head is contracted, and FIG. 2B shows a state in which the enlargement head is expanded.
As shown in FIG. 2A, the auger head 7 can be inserted into the excavation rod 4 shown in FIG. 1 at the upper end, and the shaft 71 is formed integrally with the excavation rod 4 with a detent key or the like. A cylindrical slider 74 that is externally fitted and moves up and down along therewith, and an enlarged head 73 that is rotatably supported at one end by a cylinder of the slider 74 and has a plurality of excavating blades 73b on the outer surface of the other end side. It consists of a pair of enlarged wings 73a and a spiral excavation body 72 that is integrally attached to the lower end of the shaft 71 and has a plurality of excavation blades 72a on the lower end surface.
The auger head 7 rotates with the rotation of the shaft 71 by the drive unit 3 and is propelled in the ground direction by the spiral blade 6 while excavating the ground with the excavating blade 72a, and discharges the excavated earth and sand upward. The pair of expansion blades 73a can be rotated in the vertical direction (that is, in a vertical plane) to expand and contract the excavation diameter of the expansion head 73.

The lower ends of the pair of outer rods 8 are rotatably attached by shafts 75 at radially symmetric positions on the outer peripheral surface of the slider 74. Therefore, when the hydraulic jack 20a shown in FIG. 1 is operated to move the outer rod 8 up and down, the slider 74 moves up and down along the shaft 71 accordingly.
One end of a pair of support arms 77 is rotatably attached to the shaft 71 by a shaft 76 at a lower end side of the shaft 71 at a distance from the shaft 75. The other end of the support arm 77 is rotatably attached to the shaft 78 at an intermediate position (center portion) of the magnifying wing 73 a constituting the magnifying head 73. Thus, the pair of enlarged wings 73a and the pair of support arms 77 constitute a pantograph.

  In the above configuration, when the outer rod 8 is lowered by the hydraulic jack 20 a (see FIG. 1), the slider 74 is lowered along the shaft 71. As a result, the pair of support arms 77 pivots outward from each other about a shaft 76 fixed to the shaft 71, and the enlarged wings 73 a connected to the other ends of the pair of support arms 77 are also pivoted. Expands around 75. When the expansion wing 73a is expanded outward, the digging diameter of the expansion wing 73a, and thus the expansion head 73, is expanded (see FIG. 2B).

On the other hand, when reducing the excavation diameter of the expansion head 73, the reverse operation is performed. That is, when the outer rod 8 is raised by the hydraulic jack 20a (see FIG. 1), the slider 74 rises along the shaft 71.
As the slider 74 rises, one end portion of the enlarged wing 73a attached to the slider 74 with the shaft 75 is pulled upward, whereby the intermediate portion of the enlarged wing 73a rises while rotating around the shaft 78. Accordingly, the pair of support arms 77 rotate inward from each other about the shaft 76. As a result, the pair of expansion blades 73a, and therefore the expansion head 73 is reduced so that the excavation diameter is within the diameter of the excavation body 72 of the auger head 7 (see FIG. 2A).

As an expansion / contraction mechanism of the expansion blade 73a of the expansion head 73, one end of the expansion blade 73a is fixed to the shaft 71 with the shaft 75, and one end of the support arm 77 is fitted to the distal end side of the shaft 71 with the shaft 76. One end of the outer rod 8 may be connected to the slider 74 by being rotatably fixed to the outer periphery of the slider 74.
In this case, when the outer rod 8 is lifted by the hydraulic jack 20a (see FIG. 1), the shaft end side of the shaft 76 of the support arm 77 is lifted, and the intermediate portion of the expanding blade 73a is pushed upward accordingly. The enlargement blade 73a rotates upward about the shaft 75, and its excavation diameter increases. Conversely, when the outer rod 8 is lowered, the slider 74 descends along the shaft 71, the pair of enlarged blades 73a are contracted, and the excavation diameter is reduced.

  By the way, when the excavator M excavates a large-diameter pile hole Hb (root consolidation pile hole) on the bottom side of the pile hole Ha, the operator operating the excavator on the ground is naturally the auger head 7. It is impossible to confirm the state of the enlargement head 73, that is, whether or not the enlargement head 73 is expanded as shown in FIG. 2B.

  However, since the present embodiment is configured as described above, information on the correspondence relationship between the displacement amount of the slider 74 shown in FIG. 2, and thus the displacement amount of the outer rod 8, and the expansion amount of the digging diameter of the expansion head 73 is previously stored. It is acquired and the displacement amount of the outer rod 8 is detected on the ground by visual observation and / or measurement means (sensor or the like), thereby confirming whether or not the expansion head 73 is expanded by a desired expansion amount. be able to.

That is, for example, an expansion test of the expansion head 73 is performed, and a displacement amount of the outer rod 8 required for the expansion amount of the expansion head 73 to expand to a predetermined value, for example, 2100 mm, is acquired in advance.
When excavating a consolidation pile hole Hb with a bottom (large diameter part) diameter of 2100 mm, when excavating the pile hole Ha with the expansion head 73 closed to a predetermined depth, and reaching a predetermined depth Then, the hydraulic jack 20a is actuated to expand the expansion blade 73a in the procedure already described.
That is, the hydraulic jack 20 a is operated to lower the outer rod 8 and expand the outer side while rotating the expanding blade 73 a around the shaft 71. In this case, since there is unexcavated ground above the expansion wing 73a, the expansion wing 73a gradually excavates the ground while excavating the ground with a plurality of excavation blades 73b provided on the upper surface of the end of the expansion wing 73a. Increase the diameter.

This operation is continued until a predetermined excavation diameter of the expansion blade 73a is obtained, that is, until the outer rod 8 is lowered by a predetermined distance, and then the auger head 7 and the expansion head 73 are pulled up together with the excavation rod 4.
The amount of displacement of the outer rod 8 at this time is, for example, based on the position where the hydraulic jack 20a is most retracted when the outer rod 8 is pulled up most as a reference. It is possible to visually confirm an object to be detected, such as a marking, which serves as a position display means for detecting the provided position.
Of course, a measuring instrument such as a displacement meter, which is a detecting means for detecting the amount of displacement, may be used.

3 is an enlarged view of the hydraulic jack 20a and the outer rod 8 of the excavator, FIG. 3A shows a state before the outer rod 8 is displaced, and FIG. 3B shows a state after the displacement.
In order to confirm the displacement amount of the outer rod 8, the excavator M is provided with a marking 21 at a position corresponding to the outer periphery of the outer rod 8, for example, the lower end portion of the hydraulic jack 20a, as shown in FIG. 3A. .
When the outer rod 8 is pushed downward by the hydraulic jack 20a in order to expand the pair of expansion blades 73a of the expansion head 73 shown in FIG. 2, the marking 21 attached to the outer periphery thereof is also shown in FIG. 3B. Move down.

The operator of the excavator M measures the length L from the lower end of the hydraulic jack 20a to the upper end of the marking 21 shown in FIG. 3B on the ground with a measuring device such as a displacement meter (stroke meter), for example. By displacing the outer rod 8 to the displacement amount, the expansion head 73 can be expanded to a desired diameter.
In this case, a control device may be provided to control the hydraulic jack 20a for expanding the expansion head 73 based on the displacement detected by the stroke meter. For example, when it is detected by a stroke meter that the outer rod 8 has been displaced to a predetermined displacement amount, the control device automatically stops the operation of the hydraulic jack 20a to stop the displacement of the outer rod 8, An operator can be notified by a buzzer or lamp lighting.

  In place of the measuring device, for example, at a position corresponding to the lower end of the outer rod 8 on the outer periphery of the excavating rod (its position is already known), for example, by marking with a colored tape, The operator may monitor the coincidence between the marking position and the marking of the descending outer rod 8, and the operator may control the hydraulic jack 20a to lower the outer rod 8 to that position. This method has an advantage that the cost is hardly increased although the accuracy is lower than that in the case of using the measuring apparatus.

  As described above, according to the present embodiment, the operator of the excavator can easily excavate the expansion head 73 by measuring or visually observing the descending amount of the outer rod 8, that is, the stroke length L on the ground. The drilling diameter at the time can be confirmed. Therefore, the large-diameter pile hole Hb having a desired diameter can be excavated and formed around the small-diameter pile hole Ha by rotating and expanding the enlarged blades 73a having reached the excavation diameter at the bottom of the pile hole Ha.

The reference position indicating the displacement amount of the outer rod 8 is arbitrary as long as it is a position on the outer rod 8. In short, it is sufficient that the displacement amount from the reference position can be correctly grasped.
Further, as described above, when the configuration in which the expansion blade 73a of the expansion head 73 is expanded by pulling up the outer rod 8, the marking 21 attached to the peripheral surface of the outer rod 8 is the lower end position of the hydraulic jack 20a. The marking 21 may be attached at a position away from the lower end of the hydraulic jack 20a by a predetermined distance so that the enlargement head 73 has a desired excavation diameter.
It is desirable that the marking 21 be detachable or position-changeable so that the mounting position of the marking 21 can be changed in accordance with various excavation diameters of the expansion head 73.

Next, referring to FIG. 4, a drilling method for drilling a large-diameter consolidation hole Hb at the bottom of the small-diameter pile hole Ha using the excavator and confirming a drilling defect (an unexcavated portion) after excavation will be described. I will explain.
First, when excavating with the excavator M, relational data between the amount of displacement of the outer rod 8 (and hence the slider 74) and the amount of enlargement of the enlargement blade 73a of the enlargement head 73 and hence the amount of enlargement of the excavation diameter are acquired in advance. Is as already described.
FIG. 4A first shows the excavator M arranged at a location to be excavated. In the state of FIG. 4A, the expansion wing 73a of the expansion head 73 of the excavator M is closed, and the pile hole Ha is excavated by the excavation blade 72a of the excavation body 72 attached to the lower end of the auger head 7 in this state.
FIG. 4B shows a state where excavation by the excavation body 72 is stopped when the excavation body 72 of the auger head 7 is rotationally driven to excavate the pile hole Ha to a predetermined depth.

FIG. 4C shows a state in which a large-diameter excavation hole Hb is excavated around the pile hole Ha upward from the state.
Here, as already described, the outer rod 8 is lowered and the expansion head 73 (a pair of expansion blades 73a) is rotated while being expanded, and the ground around the pile hole Ha is excavated by the expansion blades 73a. Go. The operator monitors the descending position of the outer rod 8 and rotates the expansion head 73 until the excavation diameter corresponding to the required hole diameter is obtained, while gradually expanding the expansion blade 73a, Excavate. The procedure up to the diameter expansion is as already described.
FIG. 4D shows a state where the enlargement head 73 is rotated and pulled up to a predetermined position, that is, a state where a large-diameter root fixing hole Hb having a predetermined length is formed around the pile hole Ha. As a result, a large-diameter root consolidation hole Hb having a desired diameter continuous to the bottom of the pile hole excavated first can be formed.
By measuring or confirming that the outer rod 8 has been displaced by a predetermined amount on the ground, it can be confirmed that the expansion head 73 has excavated with a predetermined excavation diameter.

By the way, even when excavation is performed by rotating the expansion head 73 with a predetermined excavation diameter, the hard rock remains without being excavated and protrudes from the hole wall, or conversely, the hole wall collapses, etc. The continuity of the wall may not be maintained, and a hole having a predetermined diameter is not always ensured.
Therefore, the present invention also examines whether there is an unexcavated region where a hole excavated using this excavator does not reach a predetermined diameter, or whether the continuity of the hole wall of the excavated hole is maintained. I try to do it at the same time.

FIG. 4E shows that the enlarged head 73 is moved up and down in the expanded state after forming the large-diameter root hardening hole Hb.
That is, it is inspected whether there is a portion having a diameter less than a predetermined diameter, that is, a poorly drilled portion, in the large-diameter rooting hole Hb excavated when the expansion head 73 (the pair of expansion blades 73a) moves up and down.

The inspection of the excavation defective portion is performed as follows.
(1) In a state in which the expansion blade 73a is fixed (locked) to the expansion position by hydraulic pressure, that is, in a state where the outer rod 8 is pushed down by the hydraulic jack 20a and the expansion blade 73a is locked in the expansion position, 73a) is pulled up while being rotated by the motor of the drive unit 3. At that time, if the tip of the enlarged blade 73a hits the small diameter portion of the hole wall of the large-diameter root fixing hole Hb, a load is applied to the motor due to the resistance. For example, when the motor is an electric motor, the drive current increases. Therefore, by monitoring the drive current value or the integrated current value and confirming that the drive current exceeds a certain threshold value, You can see in which part the defective excavation exists. In the case of using a hydraulic motor, it can be similarly detected as an increase in the load pressure generated when the tip of the enlarged blade 73a hits a small diameter portion of the hole wall of the large diameter rooting hole Hb.
The operator moves the magnifying head 73 up and down around a portion where the driving current or pressure increases beyond a certain threshold value, confirms that the driving current does not change, and further raises the magnifying head 73. Or monitor while lowering.
By doing in this way, the excavation defect of the large diameter solidification hole Hb can be eliminated.

(2) The auger head 7 is lowered to the bottom of the excavated large-diameter root hole Hb, and the pair of expansion blades 73a are expanded to a predetermined excavation diameter, and act on the expansion blades 73a via the outer rod 8. The auger head 7, here, the expansion head 73, is rolled up by the winch 11 while being rotated while the hydraulic lock to be released is rotated (open and unfixed state) (see FIG. 1). In that case, when the tip of the expansion wing 73a hits the small diameter portion of the hole wall of the large-diameter root consolidation hole Hb, the expansion wing 73a expanded by receiving the external force is closed. Position relative to each other (in this case, it will rise). That is, the operator monitors whether or not the outer rod 8 moves relative to the excavating rod 4, and if the relative movement is found, it can be seen that there is an excavation defective portion in the large-diameter root consolidation hole Hb.
Therefore, the necessary hole diameter can be ensured by re-digging the part in the procedure already described.

FIG. 5 is a diagram illustrating a procedure for inspecting a large-diameter root consolidation hole Hb that has been formed, that is, for example, that has been previously expanded by another excavation head.
The state of FIG. 5A shows that the excavator M is lowered into the pile hole Ha formed with the auger head 7 and the large diameter rooting hole Hb.
FIG. 5B shows the inside of the large-diameter root fixing hole Hb in the direction of the hole, here in the upward and / or downward direction, while rotating the enlarged wing 73a of the excavating device M placed down to the bottom of the pile hole Ha. While moving, the load of the electric motor of the drive unit 3 which is the drive means of the excavating rod 4, for example, the current value of the drive current or the hydraulic pressure of the hydraulic motor is measured to check whether the measured value increases. . When the drive current or hydraulic pressure increases beyond a predetermined value (threshold value), it indicates that the rotation of the expansion blade 73a is subjected to the resistance of the hole wall of the expansion hole at that portion. The hole wall is excavated until the driving current or the hydraulic pressure becomes a predetermined value or less by rotating up and down 73a.
FIG. 5C finally confirms the state of poor drilling of the hole wall (or discontinuity of the hole wall) by moving the expansion wing 73a up and down, and when the drilling defect cannot be detected (or the continuity of the hole wall is confirmed). Is shown). In this state, cement milk is injected into the hole, or cement milk is injected while performing enlarging excavation, mixing and stirring are performed, and the auger head 7 is pulled up.

Next, another embodiment of the present invention will be described.
The large-diameter root consolidation hole Hb is formed by excavating while expanding the expanded wing 73a while rotating, so that a spiral ridge remains on the inner peripheral surface or the hole wall collapses There is. Therefore, the surface of the spiral protrusions on the inner peripheral surface may be leveled to protect the hole wall.
FIG. 6 is a diagram illustrating a finishing procedure for the hole wall of the large-diameter root-solidifying hole Hb. FIG. 6A is a view similar to FIG. 5A. However, here, a wall leveling collar 79 is attached to the tip of the enlarged wing 73a.
FIG. 6B shows that the excavator M equipped with the rod 79 is lowered to the bottom of the large-diameter excavation hole, and the ridges on the inner peripheral surface of the large-diameter consolidation hole Hb, that is, the jaggedness, are smoothed while being pulled up from there. The state just before the start of work to be performed is shown.

FIG. 6C shows a state in which a flat surface is finished by hitting the hole wall surface of the excavated large-diameter root consolidation hole Hb. That is, the expansion head is pulled up or pulled down while rotating by applying a heel to the hole wall surface of the large-diameter root fixing hole Hb to smooth the hole wall surface.
The hole finished in this way is filled with cement milk to complete the operation.
The process of smoothing the hole wall surface by applying a ridge to the hole wall surface may be carried out following re-excavation of a poorly drilled portion of the large-diameter hole, or a large-diameter solidification already drilled by another drilling head. Instead of performing the re-digging to protect the wall of the hole, it may be performed.

  As described above, according to this embodiment, the operator confirms whether the diameter of the excavated pile hole is excavated to a desired diameter, that is, the continuity of the hole wall of the excavated large diameter hole. When the diameter of the pile hole is excavated smaller than the desired diameter, the hole wall may be reexcavated or leveled to form a pile hole with the desired diameter. The time required for the step of checking the diameter of the pile hole and the step of forming the pile hole of a desired diameter can be shortened.

Moreover, according to this embodiment, the operator can confirm easily the state of the expansion head 73 of the auger head 7, and the shape of the excavated pile hole on the ground, and excavate the pile hole of a desired diameter reliably. be able to.
In addition, the auger head 7 according to this embodiment can be used to confirm or expand the expansion head 7 using a measuring instrument such as a simple measure or stroke meter without using a special instrument (such as a conventional non-contact sensor). Therefore, an increase in cost can be suppressed.
In the above description, the drilling hole having a diameter larger than that of the drilled hole that has already been drilled is finished by using a scissors or re-excavated at a poorly drilled part. The finishing of the wall and the re-excavation of the poorly drilled portion are not limited to the above-mentioned large-diameter drill hole, and can be applied to any drill hole.

  DESCRIPTION OF SYMBOLS 1 ... Pile driver, 2 ... Pile driver leader, 3 ... Drive part, 3a ... Output shaft, 4 ... Drilling rod, 5 ... Stabilizer, 6 ... Spiral Wings, 7 ... auger head, 8 ... outer rod, 11 ... winch, 20 ... hydraulic swivel, 20a ... hydraulic jack, 21 ... marking, 71 ... shaft, 72 .. excavation body, 73 ... enlargement head, 73a ... enlargement blade, 73b ... excavation blade, 74 ... slider, 75, 76 ... shaft, 77 ... support arm.

Claims (1)

An auger head having an enlargement head having a pair of enlargement blades capable of expanding and reducing the excavation diameter, an excavation rod connected to the auger head, an excavation rod driving means for rotating the excavation rod about an axis, and the excavation rod And an outer rod that operates an expansion / contraction mechanism that expands / contracts the expansion head by axial displacement, an outer rod driving means that displaces the outer rod in the vertical direction, and an outer rod connected to the outer rod. A guide member that moves up and down along the excavation rod according to the vertical movement; and an expansion / contraction mechanism that expands and contracts the expansion blade according to the vertical movement of the guide member to expand and contract the excavation diameter of the expansion head, The outer rod is a drilling method in a drilling apparatus having a marking representing the displacement of the outer rod at a predetermined position,
Moving in the direction of the excavation hole while rotating the inside of the excavation hole in a state where the expansion head is set unfixed to the expansion position;
In the step, when the outer rod is relatively positional displacement relative to the drill rod, drill method characterized by a step of performing a re-digging of the wellbore in the enlarged head.

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