JP4808677B2 - Foundation pile excavator - Google Patents

Description

  The present invention relates to a foundation pile excavation apparatus used for forming a hole for laying an existing pile in the ground, particularly a hole having a diameter-enlarged portion for a root-solidifying bulb at the lower part in the foundation pile embedding method. About.

  In the foundation pile embedding method, a drill hole is provided in the ground with a drilling rod, and a solidified material such as cement milk is injected into the drill hole and mixed with the earth and sand. Since it is established, it can be constructed in a narrow space with low noise and low vibration compared to the impact method and cast-in-place concrete pile method, etc., it is frequently used especially for foundation pile construction in urban areas. And in this embedding method, in order to increase the supporting strength of the foundation pile by the ground, it is generally performed to form a rooted bulb part by expanding the diameter of the bottom of the hole reaching the underground supporting layer. .

  FIG. 10 shows an example of an embedding method for forming the above-described root-fixing bulb. In this case, a crawler type three-point support pile driving disposed on the ground using a drilling rod 50 equipped with a drilling head 51 having a fixed drilling blade 52 and a drilling blade for diameter expansion (also referred to as an expansion blade) 53 at the lower end. The excavation rod 50 is vertically attached to the upper end of an auger drive device (not shown) that is held by a leader of a pile driving machine such as a machine, and is driven to rotate forward by an auger motor and passes through the excavation rod 50. While discharging the supplied drilling fluid (usually water) from the lower end of the rod, the ground G is drilled by the fixed drilling blade 52 as shown in a), and the drilling hole H reaching the support layer S is formed as shown in b). Next, as shown in c), the excavation rod 50 is rotated in the reverse direction, and the predetermined length range in the support layer S is reciprocated up and down in a diameter expansion posture in which the diameter expansion excavation blade 53 protrudes to both sides in the radial direction. Drilling is performed to form the enlarged diameter portion E, and then a root-setting liquid C that is a solidifying material such as cement milk is discharged from the lower end of the rod as shown in d) instead of the drilling liquid. The excavation head 51 is reciprocated up and down several times in the range of the enlarged diameter portion E until the injection is completed and stirred. Then, after the completion of the injection of the root hardening liquid C, the excavating rod 50 is returned to the normal rotation as shown in f), the excavating rod 50 having the diameter-expanding excavating blade 53 in a reduced diameter posture is pulled up, and the excavation formed as shown in g). The pre-made pile P suspended by the pile driving device is inserted into the hole H, and as shown in h), the pre-made pile P is laid down to the depth where the lower part is placed in the enlarged diameter part E, and the mud slurry containing the root-setting liquid C is hardened. Thus, the existing pile P is fixed by setting the enlarged diameter portion E as the root of the bulb (for example, Patent Document 1).

  The excavation rod 50 shown in FIG. 10 is provided with a stabilizer 50a for stabilizing the posture that protrudes outward at regular intervals in the longitudinal direction. As the excavation rod, a stirring plate, spiral blades, and sand particles are pressure-bonded to the hole wall. What provided the pressing board etc. to be used is also used.

  In addition, as a similar embedding method, a bag body is attached to the lower end of a hollow preformed pile, and the solid body supplied through the hollow interior of the preformed pile is placed in the bag body positioned in the enlarged diameter portion of the previously formed excavation hole. There is also a method in which a rooted bulb portion is formed by injecting a cohesive fluid and hardening the inside of the bag body inflated in the enlarged diameter portion (for example, Patent Document 2). Furthermore, although the above-mentioned embedding method is a pre-drilling method in which the existing pile P is set after the excavation hole H is formed, the middle excavation method is also frequently used as the embedding method. In this intermediate excavation method, a drilling rod is placed in a hollow preformed pile, and the preformed pile is laid down to a mid-depth while excavating with a drilling head protruding from the lower end of the preformed pile. After that, the diameter of the excavation head is expanded by the excavation blade for expanding the diameter, the diameter of the excavation hole is increased, the excavation head is pulled up after the root-setting liquid L is injected, and the existing pile is brought to a predetermined depth. It is installed (for example, Patent Documents 3 and 4).

Generally, as shown in FIG. 11, for example, as shown in FIG. 11, the excavation rods used in these embedding methods have diameter-expanding excavation blades 53 and 53 on the both sides in the radial direction of the spiral blade 54 and pivot pins 55 respectively. It is pivotally attached through a fixed angle range. In the state where the excavation rod 50 is rotating forward as indicated by the solid line arrow A1, the entire excavation blades 53 and 53 for both diameter expansion are respectively accommodated in the recesses 56 and excavated by the fixed excavation blade 52 (see FIG. 10). The reduced diameter posture is accommodated inside the diameter D1, but when the excavating rod 50 rotates reversely as indicated by an imaginary line arrow A2, the diameter-expanding blades 53 and 53 are both reduced in diameter due to contact resistance with the earth and sand. Is turned into a diameter-expanded posture that protrudes outward as shown in the phantom line in the figure, and excavation is performed with an enlarged excavation diameter D2. As a means for changing the diameter-extracting excavating blade to the diameter-expanding posture, a swinging kicking member is attached to the base of the drilling blade, and the swinging kicking member swings when the excavation rod changes from normal rotation to reverse rotation. A method of kicking out the side surface of the diameter expanding excavating blade has also been proposed (Patent Document 5).
Registered Utility Model No. 3097046 JP-A-7-11634 Registered Utility Model No. 3007755 JP-A-5-247936 JP 11-62452 A

  In the conventional general excavation rod described above, the change from the reduced diameter posture to the expanded posture is performed by the contact resistance with the earth and sand accompanying the reverse rotation of the rod rotation. Depending on the operation status, there is a concern that the expanded excavation blade cannot be converted to the expanded posture due to the compacted earth and sand around the enlargement excavation blade or the rocks or rocks biting into it. is there. This is the same for the excavating rod provided with the proposed swinging kick member, and the swinging kicking member itself may also malfunction. In these conventional configurations, since it is not possible to confirm from the ground that the digging blade for diameter expansion has changed to a diameter-expanded posture, it is not known whether or not the diameter-expanded part as designed can be formed reliably, and therefore the reliability of construction. There was a problem that the support strength of the foundation pile based on the root bulb to be built was not reliable enough.

  In view of the above-mentioned situation, the present invention can easily and as designed as a drilling device used for the foundation pile embedding method, a diameter-enlarged part as a root-solidifying bulb part at the bottom of the drilling hole, and the formation status can be measured on the ground. The purpose of the present invention is to provide a structure that can be easily confirmed from the above, has high construction reliability, and can surely improve the support strength of the foundation pile by the root consolidation bulb portion to be constructed.

If the means of the present invention for achieving the above object is shown with reference numerals in the drawings, first, the excavation apparatus for foundation pile according to the invention of claim 1 is rotationally driven by connecting the upper end to the auger drive apparatus 1. A fixed excavation blade 4 and a diameter expansion excavation blade 5 are attached to the excavation head 3 at the lower end of the excavation rod 2, and a diameter expansion cylinder 6 is attached to the auger drive device 1. The lifting rod 7 that moves up and down is disposed along the excavating rod 2, and the lower end side of the lifting rod 7 is connected to the operating portion (lower sliding frame 9) of the diameter-excavating blade 5. A diameter-expanding posture in which the diameter-excavating blade 5 becomes a rotation diameter (expanded excavation diameter D2) larger than the rotation diameter (excavation diameter D1) of the fixed excavation blade 4 by the ascending / descending operation, and below the rotation diameter of the fixed excavation blade 4 To change to a reduced diameter posture that becomes the rotation diameter of Made is, in the longitudinal direction a plurality of locations of the drill rod 2, guide bracket 11 for inserting holding the lifting rod 7 vertically movably ... is configured to become provided.

  In the foundation pile excavation apparatus according to claim 1, the upper sliding frame 8 and the lower sliding frame 9 are fitted to the excavation rod 2 so as to be movable up and down. The lifting rod 7 is connected at the upper and lower ends, the expansion rod 6a of the diameter expansion cylinder 6 is connected to the upper sliding frame 8, and the diameter expansion excavating blade is connected to the lower sliding frame 9 via the link mechanism 10. 5 is connected.

  According to a third aspect of the present invention, in the foundation pile excavation apparatus of the first or second aspect, the diameter expansion cylinder and 6, the lifting rod 7 and the diameter expansion excavation blade 5 each have a pair of diameters of the excavation rod 2. It is configured to be arranged on both sides in the direction.

  According to a fourth aspect of the present invention, in the foundation pile excavation device of the third aspect, the fixed excavation blade 4 has a wing shape projecting to both sides in the radial direction of the excavation rod 2. The arrangement radial direction of the pair of diameter expanding excavating blades 5 and 5 is configured to be substantially orthogonal in a plan view.

The effects of the present invention will be described with reference numerals in the drawings. First, in the foundation pile excavating apparatus according to the first aspect of the present invention, the excavating rod 2 with the diameter-extracting excavating blade 5 having a reduced diameter is rotationally driven by the auger driving apparatus 1 and is fixed to a predetermined depth by the fixed excavating blade 4. After forming the drilling hole H, when forming the enlarged diameter portion E for forming a rooted bulb portion at the lower portion of the drilling hole H, the diameter expansion cylinder 6 attached to the auger drive device 1 on the ground is used. The diameter-excavating blade 5 is changed to a diameter-expanding posture, and the diameter-excavating blade 5 performs expansion excavation. Therefore, the expansion / contraction posture change of the diameter expansion excavating blade 5 can be performed easily and reliably by automatic operation, and the expansion / contraction state of the expansion rod 6a of the diameter expansion cylinder 6 remains as it is. In order to represent the state, even if the diameter-expanding excavation blade 5 is hardened with compacted soil or stones or rock fragments are bitten, it can be reliably grasped on the ground side. Therefore, there is no concern that the forming step of the enlarged diameter portion E will be completed while the excavating blade 5 remains in a reduced diameter posture or an incomplete enlarged diameter posture, and thus the enlarged diameter portion E as designed can be reliably formed.
Further, since the lifting rod 7 is inserted and held in the guide brackets 11 provided at a plurality of positions in the longitudinal direction of the excavating rod 2, it is difficult to cause bending, so that the driving force of the diameter expansion cylinder 6 is expanded through the lifting rod 7. It is transmitted without difficulty to the operating part of the excavating blade 5 for use, and thus the posture change of the excavating blade 5 for diameter expansion can be performed more smoothly.

  According to the invention of claim 2, the lifting rod 7 is connected to the upper and lower sliding frames 8, 9 fitted to the excavating rod 2 so as to be movable up and down at the upper and lower ends, and the upper sliding frame 8 is used for expanding the diameter. The expansion rod 6 a of the cylinder 6 is connected, and the diameter expansion excavation blade 5 is connected to the lower sliding frame 9 via the link mechanism 10, so that the diameter expansion excavation blade 5 is driven by driving the diameter expansion cylinder 6. The posture change is made smoothly.

  According to the invention of claim 3, since each pair of the diameter expansion cylinder 6, the lifting rod 7 and the diameter expansion excavation blade 5 is arranged on both sides in the radial direction of the excavation rod 2, the rotation balance of the excavation rod 2 and The load balance during expanded excavation is good and a stable excavation state can be obtained.

  According to the invention of claim 4, the protruding radial direction of the wing-shaped fixed excavating blades 4 and 4 and the arrangement radial direction of the pair of diameter-expanding excavating blades 5 and 5 are arranged so as to be substantially orthogonal in a plan view. Therefore, the rotary ballast of the excavation head 3 is good, so that excavation by the fixed excavation blade 4 and expansion excavation by the diameter expansion excavation blades 5 and 5 can be performed in a stable state.

  Hereinafter, an embodiment of a foundation pile excavator according to the present invention will be specifically described with reference to the drawings. 1 shows the entire excavation rod in the foundation pile excavator of the first embodiment, FIG. 2 shows an excavation state by the excavator for foundation pile, FIG. 3 to FIG. 5 show the excavation head of the excavation rod, and FIG. The excavation head of the excavation rod in the excavation apparatus for foundation piles of a 2nd embodiment is shown, respectively.

  In the foundation pile excavation apparatus according to the first embodiment, as shown in FIG. 1, the excavation rod 2 has a shaft portion 3 a of the cutting head 3 coaxially connected to a lower end of a rod body 2 a in which a plurality of pipe members are connected. The upper sliding frame 8 and the lower sliding frame 9 are fitted on the upper and lower parts of the excavating rod 2 so that the upper and lower sliding frames 8 and 9 can be moved up and down. Opposed to both sides in the radial direction and screwed together at the upper and lower ends. And guide brackets 11... Projecting to both sides in the radial direction are fixed at a plurality of longitudinal positions (eight places in the figure) of the rod body 2 a, and both the lifting rods 7, 7 are lifted and lowered by these guide brackets 11. It is freely inserted and held. Further, the inside of the rod body 2a and the shaft portion 3a of the cutting head 3 constitutes a liquid passage (not shown) that communicates between the two 2a and 3a, and this liquid passage is at the lower end of the shaft portion 3a of the cutting head 3. The discharge port 30 (see FIG. 5) is open.

  A cylinder mounting frame 12 is disposed so as to surround the top of the excavating rod 2, and a pair of diameter expansion cylinders 6, 6 are pivotally attached to the bottom surface of the excavating rod 2 on the base end side. On the other hand, the upper sliding frame 8 fitted on the upper portion of the excavating rod 2 is configured such that the annular frame 8b is rotatable relative to the outer side of the short cylindrical frame body 8a connected to the lifting rods 7 and 7 and is not relatively movable. A pair of brackets 8c and 8c are projected outwardly on both sides in the radial direction of the annular frame 8b, and extendable rods projecting downward from the diameter expansion cylinder 6 to the brackets 8c and 8c, respectively. The tip of 6a is pivotally connected.

  Therefore, in this excavation apparatus for foundation piles, as shown in FIG. 2, in the excavation work, the coupling portion 1a of the auger drive apparatus 1 held by the leader L of the crawler type three-point support pile driver M is used. At the same time, the cylinder mounting frame 12 is connected and integrated with the lower surface side of the auger drive device 1.

  As shown in detail in FIGS. 3 to 5, the cutting head 3 has a pair of wing-shaped fixed excavation blades 4, 4 projecting in the radial direction at the lower end portion of the shaft portion 3 a, and the shaft A pair of support brackets 13 and 13 projecting to both sides in the radial direction are fixed to the upper side of the portion 3a, and the diameter-excavating blade 5 is perpendicular to the support bracket 13 via the pivot pin 13a on the base end side. It is pivotally attached inwardly. The lower sliding frame 9 is externally fitted to the shaft portion 3a, and link pieces 10a and 10a are pivotally connected at both ends between the lower sliding frame 9 and both the diameter-extracting excavating blades 5 and 5. The link pieces 10a and 10a and both the diameter expanding excavating blades 5 and 5 form a link mechanism 10. In addition, a plurality of claw pieces 4a... Project downward from the lower edge of each fixed excavation blade 4, and a plurality of claw pieces 5a. It protrudes outward. Further, the upper end side of the shaft portion 3a forms a hexagonal column portion 3b for being inserted and connected to the lower end side of the rod body 2a so as not to be relatively rotatable.

  While the pair of diameter-extracting excavating blades 5 and 5 of the cutting head 3 are held by the link mechanism 10 in a reduced diameter posture as shown in FIG. 3 at the lower limit position of the lower sliding frame 9, As shown in FIGS. 4 and 5, the upper end of the sliding frame 9 has a C-shaped diameter-expanding posture with the lower end projecting outward, and the rotation diameter around the shaft portion 3a is fixed in the reduced-diameter posture. The rotation diameter (excavation diameter D1... See FIG. 5) smaller than the rotation diameter (excavation diameter D1... See FIG. 5) of the excavation blades 4 and 4. It is set to be. Further, the extending radial direction of the two fixed excavating blades 4 and 4 and the arrangement radial direction of the two enlarged diameter excavating blades 5 and 5 are arranged so as to be substantially orthogonal in a plan view as shown in FIG.

  Thus, the upper sliding frame 8 and the lower sliding frame 9 are in the lower limit position on the excavating rod 2 when the respective expansion rods 6a of the diameter expansion cylinders 6 and 6 are in the extended state, and each expansion rod 6a is also the same. Is set to the upper limit position when in the shortened state. Accordingly, the diameter-extracting excavating blades 5 and 5 are switched between the diameter-reduced posture and the diameter-expanded posture by the expansion and contraction operation of the diameter-expanding cylinders 6 and 6.

  The foundation pile excavation apparatus of the second embodiment shown in FIGS. 6 to 9 is different from the above-described foundation pile excavation apparatus of the first embodiment in the configuration of the excavation head 3, but the other parts have the same configuration. is there. That is, the excavation head 3 in the second embodiment includes a pair of wing-shaped fixed excavation blades 4 and 4 projecting to both sides in the radial direction at the lower end portion of the shaft portion 3a, and the arrangement diameter of the fixed excavation blades 4 and 4 A pair of support brackets 13 and 13 projecting to both sides in the radial direction orthogonal to the direction are fixed, and the diameter-excavating blade 5 is fixed to each support bracket 13 in the vertical plane via the pivot pin 13a on the base end side. It is pivotally attached so that it can rotate freely. And the lower sliding frame 9 is externally fitted to the shaft portion 3a, and the link pieces 10a, 10a are pivotally connected at both ends between the lower sliding frame 9 and the both-diameter excavating blades 5, 5. The link mechanism 10 is formed by the link pieces 10a, 10a and the two diameter-expanding excavating blades 5, 5. In contrast to the first embodiment, the link mechanism 10 is shown in FIG. While being held in an upright reduced diameter posture as shown, at the lower limit position of the lower sliding frame 9, as shown in FIG. 6 and FIG. . Therefore, the posture change of both the diameter expansion excavating blades 5 and 5 by the diameter expansion cylinders 6 and 6 is also opposite to that of the first embodiment, and when the expansion rod 6a of each diameter expansion cylinder 6 is in a shortened state. When in the reduced diameter posture and the same extended state, the diameter is increased.

  As shown in FIG. 9, also in the cutting head 3 in the second embodiment, both of the diameter-extracting excavating blades 5 and 5 are fixed excavating blades when the rotation diameter around the shaft portion 3a is reduced. The rotation diameter is set to be smaller than the rotation diameter of 4 and 4 (excavation diameter D1) and larger than the rotation diameter of the fixed excavation blades 4 and 4 (expansion excavation diameter D2). In addition, the protruding radial direction of the two fixed excavating blades 4 and 4 and the arrangement radial direction of the two enlarged diameter excavating blades 5 and 5 are arranged so as to be substantially orthogonal in a plan view.

  In the foundation pile excavation apparatus of the first and second embodiments, the excavation rod 2 is attached to the auger drive apparatus 1 of the pile driving machine M arranged on the ground as shown in FIG. The diameter excavating blades 5 and 5 are driven to rotate in a reduced diameter posture, and the fixed excavating blades 4 and 4 form the excavation hole H with the excavation diameter D1 to a predetermined depth. When forming the enlarged diameter portion E (see FIG. 10) for forming, the enlarged diameter cylinder 6 is shortened in the first embodiment and extended in the second embodiment, so that the expanded diameter excavating blades 5 and 5 are formed. It changes to a diameter expansion attitude | position, and the expansion excavation of the expansion excavation diameter D2 is performed by this diameter excavation blade 5,5. Further, when the excavating rod 2 is pulled up after forming the enlarged diameter portion E, if the expanding cylinder 6 is operated to extend in the first embodiment and shortened in the second embodiment, the expanding drilling blade 5, 5 shifts to a reduced diameter posture that does not hinder pulling.

  Therefore, according to these foundation pile excavating devices, the expansion / contraction posture change of the diameter expansion excavating blades 5, 5 can be easily and forcibly performed automatically, and the expansion / contraction state of the expansion rod 6 a of the diameter expansion cylinder 6 is achieved. Represents the expansion / contraction state of the diameter-expanding drilling blade 5 as it is, so even if the diameter-excavating blade 5 is hardened with compacted earth or stones or rocks or the like are bitten, Thus, there is no concern that the diameter-enlarged portion E may be finished with the diameter-extended excavating blade 5 in a reduced diameter posture or an incomplete diameter-expanded posture. Thus, when such a diameter expansion failure occurs, the failure is eliminated by moving the excavating rod 2 up and down, reversing, changing the rotation speed, etc. Or after confirming that the diameter-extracting excavation blade 5 has changed to the diameter-expanding posture, the expansion-excavation may be performed, so that the enlarged-diameter portion E as designed can be reliably formed.

  In these embodiments, the lifting rod 7 is connected to the upper and lower sliding frames 8 and 9 fitted to the excavating rod 2 so as to be movable up and down at the upper and lower ends, and the upper sliding frame 8 has a diameter expansion cylinder 6. The expansion rod 6a is connected to the lower sliding frame 9 via the link mechanism 10 and the diameter-excavating blade 5 is connected to the lower sliding frame 9. Conversion is made smoothly. Since the annular frame 8b connected to the telescopic rod 6a of the diameter expansion cylinder 6 is rotatable relative to the frame main body 8a connected to the lifting rods 7 and 7 of the upper sliding frame 8, the frame main body is used for excavation. Even if the 8a side rotates integrally with the excavating rod 2, the annular frame 8b is held non-rotating and does not cause any trouble.

  Further, in these embodiments, each pair of the diameter expansion cylinder 6, the lifting rod 7 and the diameter expansion excavation blade 5 is arranged on both sides in the radial direction of the excavation rod 2, and the wing-shaped fixed excavation blades 4, 4. Since the overhanging radial direction and the arrangement radial direction of the pair of diameter-extracting drilling blades 5 and 5 are arranged substantially perpendicular to each other in plan view, the rotation balance of the excavating rod 2 and the load balance during expanded excavation are good. Therefore, both the excavation by the fixed excavation blade 4 and the expansion excavation by the diameter expansion excavation blades 5 and 5 can be performed in a stable state. In addition, the lifting rods 7 and 7 are inserted and held in guide brackets 11 provided at a plurality of positions in the longitudinal direction of the excavating rod 2 so that they are not easily bent, and the driving force of each diameter expansion cylinder 6 is passed through the lifting rod 7. Therefore, the diameter change excavating blades 5 and 5 can be changed in posture more smoothly.

  Although illustration and description are omitted in the first and second embodiments, the excavation rod 2 is integrally formed with screw blades for soil removal and agitation in the excavation head portion 3, and further, the excavation head. Similar screw blades may be integrally formed from the portion 3 to the rod body 2a. However, these screw blades need to be provided in a form that does not interfere with the posture change of the diameter-excavating blade 5 and the lifting / lowering operation of the lower sliding frame 9 and the lifting / lowering rod 7 by setting the notch or discontinuous portion.

  In addition, in the foundation pile excavation apparatus of the present invention, the shape of the fixed excavation blade 4 and the diameter expansion excavation blade 5, the configuration of the link mechanism 10, the connection structure between the diameter expansion cylinder 6 and the upper sliding frame 8, the expansion In addition to the embodiment, various design changes can be made to the detailed configuration such as a structure for attaching the diameter cylinder 6 to the auger drive device.

The side view of the whole excavation rod of the excavation apparatus for foundation piles concerning a 1st embodiment of the present invention. The schematic side view which shows the excavation condition by the excavation apparatus for foundation piles. The front view of the excavation head which used the excavation blade for diameter expansion in the excavation apparatus for foundation piles as the diameter reduction attitude | position. The front view of the excavation head which made the diameter excavation blade the diameter expansion posture. The bottom view of the excavation head which made the same excavation blade for diameter expansion the diameter expansion posture. The side view of the excavation head which made the digging blade for diameter expansion in the excavation apparatus for foundation piles concerning 2nd Embodiment of this invention into the diameter expansion attitude | position. The front view of the excavation head which made the excavation blade for diameter expansion the diameter reduction posture. The front view of the excavation head which made the diameter excavation blade the diameter expansion posture. The bottom view of the excavation head which made the same excavation blade for diameter expansion the diameter expansion posture. The model longitudinal cross-sectional side view which shows the embedding method of the foundation pile which forms a root-fixing bulb part in order of the process of ah. The cross-sectional view explaining the action | operation of the excavation blade for diameter expansion in the conventional excavation head.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Auger drive device 2 Excavation rod 3 Excavation head 4 Fixed excavation blade 5 Diameter expansion excavation blade 6 Diameter expansion cylinder 6a Telescopic rod 7 Lifting rod 8 Upper sliding frame 9 Lower sliding frame (operation part)
10 Link mechanism 11 Guide bracket D1 Drilling diameter (rotating diameter)
D2 Expanded drilling diameter (rotating diameter)

Claims (4)

A fixed excavation blade and a drilling blade for diameter expansion are attached to the excavation head at the lower end of the excavation rod that is rotationally driven by connecting the upper end to the auger drive device,
An auger cylinder is attached to the auger drive device, and an elevating rod that moves up and down by the elongating cylinder is disposed along the excavating rod, and a lower end side of the elevating rod is an operating portion of the enlarged excavating blade. Connected to
By the lifting and lowering operation of the lifting rod, the diameter-extracting excavating blade has a diameter-expanding posture in which the rotating diameter is larger than the rotating diameter of the fixed excavating blade, and a diameter-reducing posture in which the rotating diameter is equal to or smaller than the rotating diameter of the fixed excavating blade. Configured to convert to
A foundation pile excavation apparatus in which guide brackets are provided at a plurality of locations in the longitudinal direction of the excavation rod so as to insert and hold the elevation rod so as to be movable up and down .   The upper slide frame and the lower slide frame are fitted to the excavation rod so as to be movable up and down, and the lift rod is connected to both slide frames at the upper and lower ends, and the upper slide frame is extended and contracted by the cylinder for expanding the diameter. The excavation apparatus for foundation piles according to claim 1, wherein a rod is connected and the lower excavation blade is connected to the lower sliding frame via a link mechanism.   The excavation apparatus for foundation piles according to claim 1 or 2, wherein a pair of the diameter expansion cylinder, the lifting rod, and the diameter expansion excavation blade are arranged on both sides in the radial direction of the excavation rod. The fixed excavating blade has a wing shape projecting to both sides in the radial direction of the excavating rod, and the extending radial direction of the fixed excavating blade and the arrangement radial direction of the pair of diameter expanding excavating blades are substantially orthogonal in a plan view. The excavation apparatus for foundation piles according to claim 3.

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