JP4095098B2 - Method for confirming expanded wing diameter of excavator for foundation pile construction - Google Patents

Description

  The present invention relates to a method for confirming the expanded state in the ground of an expanded wing of a diameter expanded excavator for foundation pile construction used in the case of constructing a root-enlarged bulb part by a medium digging method or the like.

  In order to secure the tip bearing capacity of the foundation pile, it is often practiced to create a root-enlarged bulb part, and as an expansion drilling device for that purpose, an enlargement provided on the excavation head when creating the enlarged bulb part Various types have been developed in which the wings are expanded to expand the diameter, and the diameter is reduced again when the blades are pulled up.

  As a principle of expansion / contraction of the expansion blade, there are one that expands / contracts by operation of a hydraulic device, another that expands / contracts mechanically, and one that utilizes resistance from the ground.

  As such a diameter expanding excavator, for example, Patent Documents 1 and 2 disclose excavation treatment for foundation pile construction in which the diameter expansion amount can be set large while preventing sudden resistance from the ground during diameter expansion. As a tool, the diameter can be increased by being supported by the drive shaft, the excavation shaft splined to the drive shaft, the shaft digging blade provided at the tip of the excavation shaft, and the drive shaft and the excavation shaft. An excavation jig for foundation pile construction comprising an expansion blade with an expansion excavation blade attached thereto, wherein the drive shaft and the excavation shaft are splined so as to be relatively displaceable in the vertical direction, and the expansion blade The upper end portion of the expansion wing is connected to the drive shaft so as to be rotatable in the vertical direction, and the lower end portion of the expansion wing or the intermediate position in the extending direction is connected to the upper end portion of the auxiliary link so as to be rotatable in the vertical direction. The lower end of can be rotated up and down with respect to the drilling shaft Drilling jig for foundation piles construction, characterized in that the sintering is described.

  That is, in the inventions described in Patent Documents 1 and 2, the drive shaft and the excavation shaft at the tip can be moved relative to each other in the axial direction via the keyway and the key constituting the spline, and are provided on the drive shaft side. The expansion blade expands and contracts via an auxiliary link that connects the expansion blade and the excavation shaft.

  Further, Patent Document 3 discloses a data collection / pipeline system for grasping the situation of the construction of the enlarged bulb part, and the construction status data of the enlarged bulb part by the pile driving machine, that is, the opening / closing amount of the enlarged wing and the cement milk The accumulated flow rate, etc. are collected and held sequentially, and a construction status image that simulates the cross-sectional shape of the pile and the enlarged bulb is displayed on the display or wireless terminal, and a corresponding message is provided and construction status image data Is transmitted wirelessly to a pile driving machine for remote display.

  As other background art, Patent Documents 4 and 5 describe a structure for expanding and contracting using a spline composed of a key groove and a key, and Patent Document 3 describes a means for expanding the diameter of an expanding blade using a horizontal diameter expanding plate. Yes.

JP 2003-106082 A JP 2005-023561 A JP-A-2005-240284 Japanese Examined Patent Publication No. 56-047355 Japanese Patent No. 3330850 JP 2004-076384 A

  In the conventional diameter expansion drilling device that forms a root-enlarged bulb part, the drive shaft is excavated in the forward direction (direction in which it is screwed into the ground as the screw at the tip rotates), and reversed by the root-enlarged bulb part. Most devices expanded the expanded wing and excavated the expanded bulb by reversing it.

  In particular, in a device that gradually expands the diameter of an enlarged blade due to a spline structure, the shape of the spline is a Z-shape as shown on the left side of FIG. 4 (corresponding to those described in Patent Documents 1 and 2 as a conventional example). As a result, I had to drill in reverse.

  That is, as shown as a conventional example on the left side of FIG. 4, when excavating while the diameter of the enlarged blade is reduced and rotating in the middle digging method or the like (state A), the key is a Z-shaped key in the figure. When it is locked to the locking part at the top of the groove and starts expanding the diameter of the enlarged bulb (state B), the key is unlocked by reversing the key, and the key is locked in the reverse direction. The expanding blade gradually opens and expands in diameter while moving along the tapered surface opposite to the position (state C).

  When the diameter expansion is completed from that state, the key is locked to the engaging portion at the lower part of the Z-shaped key groove while being reversed, and the enlarged bulb part is created while moving the excavation head up and down (state D). At that time, a curable filler such as cement milk is injected into the enlarged bulb portion through piping provided inside the drive shaft and the excavation shaft, and mixed with earth and sand.

  After the formation of the enlarged bulb part is completed, the locked state of the key is released by normal rotation and pulled up by normal rotation (not shown).

  In the conventional example on the left side of FIG. 4, the key groove is on the drive shaft side and the key is on the excavation shaft side. In the opposite case, the relationship between the key groove and the key is reversed.

  The construction of the procedures such as forward excavation (state A), reverse diameter expansion (states B and C), reverse root consolidation enlarged bulb portion excavation (state D), and forward pulling have the following problems. is there.

(1) At the tip of the excavator, there is usually a screw-shaped excavation blade, which is cut in the direction of the screw propelled by normal rotation. Excavation can be carried out, but excavation becomes difficult in the case of reverse rotation.

(2) The excavated soil may accumulate at the bottom of the bulb. Insufficient stirring and mixing may cause difficulty in creating a uniform enlarged bulb portion.

(3) The sediment deposited on the upper screw in the medium digging method is consolidated in the steel pipe, and an excessive load is applied to the auger. In addition, the earth and sand deposited on the upper part of the screw may fall into the root-enlarged bulb portion, which may adversely affect the quality of the root-solidification.

(4) When the excavation head is lifted up, it rotates in the forward direction, so that negative pressure is applied and the root-setting liquid such as cement milk in the root-enlarged bulb may be pulled up. Further, since the head is lifted while rotating in the direction of raising the soil, the amount of soil removal may increase.

(5) In the Z-shaped spline shape, the rotation direction after the key is released from the lock at the time of expansion blade contraction is one direction. Therefore, the third stage on the left side of FIG. ), The key may hit the corner at the position indicated by a black circle, and the key may be damaged.

  In addition, in a diameter-excavating machine that forms a root-enlarged bulb, there is a conventional method for confirming the expansion of the expansion blade by using a double pipe for the rod and using hydraulic pressure or water pressure. However, since a double pipe is used, it will be very expensive. There is a method of confirming on the ground using electromagnetic waves or the like when the wings expand, but electromagnetic waves may flow to other places and may not be confirmed reliably.

  On the other hand, although the thing of patent document 3 is that the image data of a construction condition can be seen in real time, expansion blade opening / closing amount data and cement milk flow rate data are obtained with an expansion blade opening / closing sensor or cement milk flow meter. It is to measure, and it is not described how to acquire the expansion blade opening / closing amount data in the ground.

  By designing the flow path for injecting drilling fluid, cement milk, etc., the present invention can easily and reliably grasp the diameter expansion situation of the expansion wing in the ground without requiring any special equipment or equipment. The purpose of the present invention is to provide a method for confirming the expanded wing diameter of the excavator for foundation pile construction.

The invention according to claim 1 of the present application includes a hollow drive shaft that constitutes an excavation head, and an excavation shaft that is accommodated inside the drive shaft so as to be relatively movable in the axial direction. Using the relative movement in the axial direction, the expansion wing whose one end is pivotally supported on the drive shaft side so as to be rotatable in the vertical direction can be expanded and contracted via the expansion assisting means provided on the excavation shaft side. A method for confirming a diameter expansion state of an enlarged blade in a foundation pile construction excavator, wherein a key provided on one of the drive shaft and the excavation shaft passes through a key groove provided on the other and the axial direction of the excavation head and The keyway has a longitudinal guide portion that guides the axial movement of the drive shaft and the excavation shaft, and extends from the guide portion in the circumferential direction. The key is engaged in the circumferential direction when the drilling shaft is rotated in the radial state. A pipe for injecting excavation water or a curable filler provided inside the drive shaft and the excavation shaft, on the drive shaft side and the drive shaft. The excavation shaft side conduit accommodated so as to be capable of relative movement in the axial direction is located across a space enabling relative movement of the drive shaft and the excavation shaft, and the relative relationship between the drive shaft and the excavation shaft is With the movement, at the stage where the expansion blade expands greatly, the space is eliminated due to the reduction of the excavation head, and the channel on the drive shaft side and the pipeline on the excavation shaft side are in contact with each other by shifting. When the key is engaged with the locking lock portion, the opening of the pipeline on the drive shaft side is accommodated in the opening of the pipeline on the excavation shaft side, and the resistance is increased. To reduce the resistance and reduce the relative movement of the drive shaft and excavation shaft. It is characterized in that to check the engagement state to the locking locking portions of the expanded state or the key for the expansion blades by increasing or decreasing Urn fluid injection pressure.

  Using the relative movement in the axial direction of the drive shaft and the excavation shaft, the expansion wing whose one end is pivotally supported on the drive shaft side can be expanded and contracted via a diameter expanding means provided on the excavation shaft side. This is the same as that using a conventional spline structure.

  In the present invention, when a flow path for injecting a curable filler such as drilling water or cement milk is formed inside the drive shaft and the excavation shaft (usually, such a flow path may be formed). Excavation head expansion and contraction (relative movement in the axial direction of the drive shaft and excavation shaft) and the opening and closing of the expansion wing are mechanically linked. In addition to changes in the cross section of the flow path, etc., the fluid resistance in the flow path is changed intentionally by devising the form of the flow path, etc. It is to grasp the state.

In particular, the case where scaling of the stretch and expand wing drilling head is subjected to constraints spline connection consisting of the keyway and key, so the fluid resistance changes in the flow path from the relationship between the spline-coupled with the channel, with it The diameter expansion state of the expansion blade is grasped from the increase / decrease of the fluid injection pressure.

  In the present invention, the present invention facilitates the expansion state of the expanding wing in the ground without the need for a special device or equipment by the design of the flow path for injecting drilling fluid, cement milk or the like. And it can be grasped reliably.

  Since no sensor or the like is required, the cost is low and field work is easy.

  FIG. 1 shows an embodiment of an excavation head portion of a foundation pile construction excavator to which the present invention is applied, from the start of excavation by normal rotation in a reduced diameter state to the expansion bulb portion by normal rotation in an expanded diameter state. It shows the positional relationship between the position of the key and the enlarged blade in the keyway until excavation and agitation.

  The excavation head 1 has a hollow drive shaft 2 and an excavation shaft 3 accommodated therein so as to be relatively movable in the axial direction. In this example, the excavation head 1 performs relative movement in the axial direction of the drive shaft 2 and the excavation shaft 3. Utilizing the enlarged wing 4 whose one end is pivotally supported by a pin joint on the drive shaft 2 side so as to be rotatable in the vertical direction, the auxiliary enlarged diameter plate 5a and the main enlarged diameter plate 5b provided on the excavation shaft 3 side are used. Can be scaled.

  In the drawing, the portion protruding from the upper portion of the drive shaft 2 is a connecting portion 8 to the upper portion of the excavator, and a rod having spiral blades on the outer periphery is usually connected to this portion.

  In this example, although not visible from the outer surface, a U-shaped key groove 6 is formed on the inner surface side of the drive shaft 2. On the outer surface side, the key 7 projects from the key groove 6 to form a spline. This spline portion is made watertight by interposing packing or the like between the inner surface of the drive shaft 2 and the outer surface of the excavation shaft 3 to prevent the entrainment of earth and sand, and 70% of the spline volume inside. A certain amount of lubricant should be sealed.

  The keyway 6 formed on the inner surface side of the drive shaft 2 extends in the circumferential direction from a longitudinal guide portion 6a that induces relative movement of the drive shaft 2 and the excavation shaft 3 in the axial direction, and a lower end of the guide portion 6a. A first locking lock portion 6b that engages the key 7 in the circumferential direction when the drive shaft 2 is rotated forward in the reduced diameter state of the expansion blade 4, and the expansion blade 4 extends in the circumferential direction from the guide portion 6a. When the drive shaft 2 is rotated forward in the diameter state, the key 7 is U-shaped from the second locking portion 6c engaged in the circumferential direction (in this example, it is U-shaped when viewed from the back of the paper). Is formed.

  FIG. 1 (a) shows a state where the drive shaft 2 is rotated forward while the enlarged blade 4 is in a reduced diameter state, and at this time, the key 7 is a first locking lock portion at the lower end of the key groove 6. FIG. The rotation of the drive shaft 2 is transmitted to the excavation shaft 3 while being engaged with 6b.

  (b) is a state in which the excavation head 1 reaches the enlarged bulb formation position at a predetermined depth and starts to expand the diameter of the expansion blade 4 by reversing the drive shaft 2. It abuts against the surface opposite to the stop lock portion 6b.

  At this time, rotation in the reverse direction is transmitted to the excavation shaft 3 at this contact portion. Further, in this example, the auxiliary diameter-expanding plate 5a whose diameter is gradually increased is provided horizontally on the excavation shaft 3, and due to the reverse rotation of the excavation shaft 3, the expanding blade 4 extends along the outer edge of the auxiliary diameter-expanding plate 5a. Open while sliding.

  (c) shows a state in which the key 7 has moved up the guide portion 6a of the key groove 6 to the upper end of the guide portion 6a with the drive shaft 2 reversed.

  The guide portion 6a is provided with a taper, and the vertical component of the force acting on the key 7 from the guide portion 6a of the key groove 6 pushes the key 7 upward by rotating the drive shaft 2 in the reverse direction. At this time, the expansion blade 4 is pushed upward by the auxiliary diameter expansion plate 5a due to relative displacement in the axial direction.

  From this state, by rotating the drive shaft 2 forward, the key 7 enters and engages with the second locking lock portion 6c as shown in (d).

  At that time, the expansion blade 4 is in a substantially horizontal expansion state by riding on the main diameter expansion plate 5b located at the lower end on the drive shaft 2 side, and this state is maintained during normal rotation.

  A spiral blade 9 is attached to the lower end of the excavation head 1 (illustration of this portion is omitted for (b) and (c) in FIG. 1), and a plurality of excavation blades 10 are attached to the lower end of the spiral blade 9. It has been. In the present invention, since the enlarged bulb portion is excavated and stirred by forward rotation with the enlarged blade 4 expanded in diameter, the functions of the spiral blade 9 for forward rotation and the excavating blade 10 attached in the forward direction are maximized. Can be used.

  Usually, the excavating blade 11 on the lower surface side of the expanding blade 4 is also attached so as to function in the normal direction. However, in the illustrated example, the excavating blade 12 is also attached to the upper surface side of the expanding blade 4 so that excavation can be performed upward. I have to.

  FIG. 2 shows an enlarged bulb portion by forward rotation in the expanded diameter state from the start of excavation by forward rotation in the reduced diameter state in another embodiment of the excavation head portion of the excavator for foundation pile construction to which the present invention is applied. The positional relationship between the expansion blade and the diameter expansion plate until excavation and agitation is shown. In (b) to (d), the spiral wing 9 at the tip is not shown.

  The basic structure and function are the same as in the case of FIG. 1, but the resistance is reduced by minimizing the cross section of the auxiliary enlarged plate 5a as much as possible. Further, a rib 5c is provided on the outer peripheral portion of the auxiliary diameter expanding plate 5a, and the upper portion of the rib 5c is in direct contact with the lower surface of the expanding blade 4 to push up the expanding blade 4. By providing an inclination on the upper part of the rib 5c, the enlarged blade 4 can be pushed up smoothly.

  Further, in the process of expanding the diameter of the expansion blade 4 from (d) to (e) in FIG. 2, when the rotation of the drive shaft 2 changes to normal rotation, the expansion blade 4 is detached from the diameter expansion plate 5 and contracted. The end of the rib 5c and the base of the enlarged wing 4 are engaged so as not to stir (see cross section AA in (d)).

  FIG. 3 is an enlarged wing and drilling water or hardened filling from the start of excavation by forward rotation in the reduced diameter state to excavation of the enlarged bulb portion by forward rotation in the expanded diameter state and stirring in another embodiment of the present invention. The positional relationship with the flow path for injecting a material is shown.

  In a diameter-excavating machine that creates a root-enlarged bulb, there is a conventional method for confirming the expansion of the expansion blade by using a double pipe for the rod and using hydraulic pressure or water pressure. The use of heavy pipes is very expensive.

  In addition, there is a method of confirming on the ground using electromagnetic waves or the like when the wings expand, but electromagnetic waves may flow to other places and may not be confirmed reliably.

  On the other hand, in this type of large-diameter excavator, construction is generally performed while injecting curable filler such as drilling water or cement milk through a pipe line penetrating the inside, and the embodiment of FIG. 3 is expanded. In order to confirm the expanded state of the blade 4, the relative movement of the drive shaft 2 and the excavation shaft 3 with respect to the pipe for injecting excavation water and cement milk provided inside the drive shaft 2 and the excavation shaft 3 The diameter expansion state of the expansion blade 4 is confirmed from the increase or decrease in the fluid injection pressure accompanying the change in the fluid resistance of the pipe line.

  More specifically, in FIG. 3, the use of the fact that the excavation head 1 expands and contracts when the diameter of the expansion blade 4 is expanded, and in the processes (a) to (c), a space 21 is formed between the upper and lower pipe lines 22 and 23. In the stage where the expanded blade 4 is greatly expanded in diameter by the relative displacement in the axial direction in the reverse state as shown in (d) from the state in which the drilling water or cement milk is injected in a state where resistance is low, the drilling head The space 21 is eliminated by the reduction of 1 and the pipe line 22 on the drive shaft 2 side and the pipe line 23 on the excavation shaft 3 side are in contact with each other so that the flow path is narrowed and the resistance is increased (see the enlarged view of the same A). After the enlargement, in the forward rotation state of (e), the pipe 22 on the drive shaft 2 side fits in the opening of the pipe 23 on the excavation shaft 3 side (see the enlarged view of A), and the flow path is the original size. Thus, the resistance is reduced.

In this way, more elevated over the drilling water and cement milk pressure, it is possible to confirm that the expansion blades 4 are enlarged.

  FIG. 4 shows a conventional Z-shaped spline and a newly invented U-shaped spline, from the start of excavation by normal rotation in a reduced diameter state to excavation of an enlarged bulb portion by normal rotation in an expanded state. This shows a comparison between the position of the key in the key groove until stirring and the positional relationship of the enlarged blades.

  The case of the conventional Z-shaped spline is as described in the section of the problem to be solved by the invention. Briefly speaking, the state A is forward excavation, the states B and C are reverse diameter expansion, State D is during excavation of the inversion root and expanded bulb.

  There is no significant difference between states A and B, but in the case of the conventional Z-shaped spline shape, the rotation direction is the same in the process from state C to D, and the surface where the key and the key groove abut (see FIG. 4). Since the key is about to be engaged with the second locking portion located on the contact surface side while the right side surface of the key remains unchanged, a state in which the contact area temporarily decreases occurs. For this reason, the problem of damage due to corner contact of the key occurs. On the other hand, in the present invention, in the process from state C to D, the key is engaged with the second locking portion of the key groove by switching the rotation from the reverse rotation to the normal rotation. The contact area does not decrease and there is no problem with corner contact.

  Also in the state D, in the case of the conventional Z-shaped spline shape, excavation and agitation of the enlarged bulb portion are performed by reversing, which may cause problems of excavability, problems of soil removal, sedimentation of excavated soil, etc. While there is a problem of the quality of the root-enlarged bulb portion, the excavation head according to the present invention performs the normal rotation, so that all these problems are solved.

  FIGS. 5 to 8 show the effects of forward excavation and reverse excavation during expanded bulb excavation in comparison with the prior art.

  In FIG. 5, in the conventional example of (a), the rotation of the excavation head 1 during the expanded excavation is reverse, whereas in the invention of (b), the rotation is normal.

  Therefore, in FIG. 6, in the conventional example of (a), the force of dropping the sediment deposited on the screw of the rod 31 connected to the upper part of the excavation head 1 acts downward as shown by the arrow, In the invention, since it is normal rotation, the excavated soil is subjected to a force that pushes it upward, and there is little sediment on the lower end of the enlarged bulb.

  Further, in FIG. 7, in the conventional example of (a), excavated earth and sand may accumulate at the lower end of the enlarged bulb part, so that it becomes difficult to re-excavate to the ground once excavated as described above. Since stirring and mixing with the root-setting liquid at the lower end is insufficient, it may be difficult to create a uniform root-enlarged bulb portion. Moreover, the earth and sand deposited on the screw 32 of the rod 31 connected to the upper part of the excavation head 1 may be consolidated inside the steel pipe, and an excessive negative pressure may be applied to the auger. On the other hand, in the invention of (b), since there is little accumulation of excavated earth and sand, it is easy to excavate again.

  In FIG. 8, in the conventional example of (a), when the excavation head 1 is recovered, a negative rotation is applied, and there is a possibility that the root-setting liquid of the root-enlarged bulb part is pulled up, and the amount of soil is also increased. Increase. On the other hand, in the invention of (b), when the excavation head 1 is recovered, there is no possibility of pulling up the root-setting liquid of the root-enlarged bulb part, and it is possible to create a healthy enlarged bulb part. Yes, the amount of soil can be reduced.

About one embodiment of the excavation head portion of the excavator for foundation pile construction to which the present invention is applied, from the start of excavation by normal rotation in the reduced diameter state in one embodiment of the excavation by normal rotation in the reduced diameter state, the diameter expanded state FIG. 6 is a front view and a horizontal sectional view showing the positional relationship between the position of the key and the expanding blade in the keyway until excavation and agitation of the expanding bulb part by normal rotation in the case of FIG. From the start of excavation by normal rotation in the reduced diameter state to the excavation of the expanded bulb portion by normal rotation in the expanded diameter state and stirring in other embodiments of the excavation head portion of the excavator for foundation pile construction to which the present invention is applied It is the front view and horizontal sectional view which showed the positional relationship of an enlarged wing | blade and a diameter expansion board. About one specific embodiment of the present invention, from the start of excavation by forward rotation in the reduced diameter state to the excavation of the enlarged bulb portion by forward rotation in the expanded diameter state, the expansion blade and drilling water or curable filler from stirring It is the front view and horizontal sectional view which showed the positional relationship with the flow path for injecting. For the conventional Z-shaped spline and the newly invented U-shaped spline, the key from the start of excavation by normal rotation in the reduced diameter state to the excavation of the expanded bulb by normal rotation in the expanded diameter state and stirring It is the front view which showed the position of the key in a groove | channel, and the positional relationship of an expansion blade, and the expanded view of a spline part. It is the vertical sectional view which showed the influence by normal rotation excavation and reverse rotation excavation at the time of expansion bulb part excavation as contrasted with the prior art. It is the vertical sectional view which showed the influence by forward rotation excavation at the time of expansion bulb part excavation, agitation, and reverse excavation compared with the prior art. It is the vertical sectional view which showed the influence by forward rotation excavation at the time of expansion bulb part excavation, agitation, and reverse excavation compared with the prior art. It is the vertical sectional view which showed the influence by the normal rotation excavation and reverse rotation excavation at the time of raising of an excavation head as contrasted with the prior art.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Excavation head, 2 ... Drive shaft, 3 ... Excavation shaft, 4 ... Expansion blade, 5a ... Auxiliary diameter expansion plate, 5b ... Main diameter expansion plate, 6 ... Key groove, 6a ... Guide part, 6b ... 1st engagement Stop lock portion, 6c ... second locking lock portion, 7 ... key, 8 ... connecting portion, 9 ... spiral wing, 10, 11, 12 ... excavation blade, 21 ... space, 22, 23 ... piping, 31 ... rod 32 ... Screw, 41 ... Expanding bulb part

Claims (1)

A hollow drive shaft that constitutes the excavation head; and an excavation shaft that is accommodated inside the drive shaft so as to be relatively movable in the axial direction, and uses relative movement in the axial direction of the drive shaft and the excavation shaft. The expansion wing of the excavator for foundation pile construction in which the expansion wing whose one end is pivotally supported on the drive shaft side so as to be pivotable in the vertical direction can be expanded and contracted via the expansion auxiliary means provided on the excavation shaft side. A method of confirming the diameter expansion state, wherein a key provided on one of the drive shaft and the excavation shaft is relatively movable in a keyway provided on the other in the axial direction and the circumferential direction of the excavation head. The keyway is a longitudinal guide portion that induces relative movement of the drive shaft and the excavation shaft in the axial direction, and extends in the circumferential direction from the guide portion when the excavation shaft is rotated in the expanded state of the enlarged blade. The key has a locking lock portion engaged in the circumferential direction, A pipe for injecting drilling water or a curable filler provided inside the dynamic shaft and the excavation shaft is accommodated in the pipe on the drive shaft side and the inner side of the drive shaft so as to be relatively movable in the axial direction. The pipeline on the excavation shaft side is located across a space allowing relative movement between the drive shaft and the excavation shaft, and the expansion blade greatly expands with the relative movement of the drive shaft and the excavation shaft. the diameter progressively eliminates the space reduction of the drilling head, and the flow path becomes narrower increases the resistance in line of the drive shaft side and the in contact with the conduit of the drill shaft side deviates, the said key In the state of being engaged with the locking lock portion, the opening of the pipe on the drive shaft side is accommodated in the opening of the pipe on the excavation shaft side, and the flow path becomes the original width and the resistance is reduced. The structure is increased by increasing or decreasing the fluid injection pressure with the relative movement of the drive shaft and excavation shaft. The locking enlargement wings expanded state confirmation process of the foundation pile construction for an excavator, characterized in that to check the engagement state of the lock portion of the enlarged diameter state or the key expansion wings.

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