JP4481662B2 - Pile setting method and blade plate - Google Patents

Description

  The present invention relates to a pile settling method and a blade plate used therefor, and more particularly to a settling method that minimizes the amount of excavated soil, and mainly relates to a concrete pile settling method and a blade plate used in this method.

  Conventionally, in order to reduce the amount of excavated soil as much as possible when substituting support piles in the ground, an auger drill with spiral blades only on the lower end side is inserted into the pile, and this auger drill and pile are At the same time, a technology has been developed to raise the auger drill without raising the excavated soil that has been consolidated in the pile by allowing the excavated soil to settle down, leaving the excavated soil in the pile to remain, and rotating the auger drill in reverse. .

  For example, a friction cutter is provided on the outer periphery of the lower end of the pile, a disc having a size that closes the lower end surface of the pile and a cutter blade mounted on the lower surface is provided, and an auger drill inserted into the hollow hole of the pile has the disc Penetrating with a drilling blade at the lower end, with an engaging part that engages with the disk, with a spiral blade near the lower end in the pile, with a fluid passage opening in the vicinity of the drilling blade in the shaft, and The auger drill can be given a rotation and thrust different from that of the pile, and in the hard ground, the rotation and thrust different from the pile can be applied to the auger drill, and the pile can be drilled while excavating the ground below the lower end of the pile. There is a method for laying a pile to enter the ground (for example, see Patent Document 1).

  In this technique, a pile setting machine that rotates and sinks a concrete pile and an auger drive unit that separately provides the auger drive unit that applies rotational force and thrust to the auger drill in the pile are used.

  In addition, a flange-shaped bottom expansion plate is attached to the outer periphery of the lower end of the steel pipe pile, a notch discharge port is provided in the bottom expansion plate, and an upper blade inclined from the rotation direction edge of the notch discharge port toward the anti-rotation direction There is a technique including a lower blade disposed with a receding angle with respect to the rotation direction from the edge of the notch discharge port in the anti-rotation direction (for example, see Patent Documents 2 and 3).

This technique is a technique in which the steel pipe pile itself is rotated and excavated by a bottom expansion plate, and the steel pipe pile is press-fitted and settled, and is a technique for forming a consolidated cylindrical layer of earth and sand on the outer periphery of the pile.
Application for Japanese Patent Application No. 2003-32059 JP 2003-27475 A (page 2-4, FIG. 1) JP 2003-232035 A (page 2-4, FIG. 1)

  The present invention is a further improvement of the technique described in Patent Document 1 above. In soft ground, the ground is compacted without rotating the pile, and in hard ground, into the hollow portion of the pile by excavation. The piles can be easily settled by the inflow of sediment and the rise to the periphery of the piles, the ground around the piles is consolidated, the power is saved, the ground around the piles is improved, and the excavated soil The purpose is to provide a technique for further reducing the amount of emissions.

The present invention was made to solve the above problems, and in a method of inserting an auger drill into a pile and sinking the pile into the ground while excavating with the auger drill,
(A) A plurality of notches having a diameter larger than the outer diameter of the pile and opened at the top and bottom of the outer periphery, and a blade plate having a drilling blade on the lower surface is attached to the lower end of the auger drill,
(B) The auger drill is provided with a spiral blade only on the lower end side of the entire length,
(C) In the ground where the N value is a certain value or less, the pile lowers while the excavated soil is consolidated to the outer periphery of the pile without rotating the auger drill by bringing the lower end of the pile close to the blade plate and rotating the pile. In the ground where the N value exceeds a certain value, drilling with the auger drill leading below the lower end of the pile, sinking the pile while consolidating the excavated soil in the pile,
(D) After the lower end of the pile reaches the support layer, by rotating and thrusting the auger drill and the blade plate while spraying the root hardening liquid from the nozzle of the auger drill, the support layer is excavated and stirred. It is a pile settling method characterized by forming a bulb inside, reversing the auger drill, leaving the blade plate in the bulb and lifting the auger drill.

The present invention further improves the technique of Patent Document 1, and the difference from Patent Document 1 is as follows.
(B) Attach to the lower edge of the auger drill with a plurality of notches that are larger than the outer diameter of the pile and open at the top and bottom of the outer periphery, and have a drilling tool on the lower surface. It is sinking without rotating a pile, abutting the said blade board and rotating an auger drill.

  Since the blade plate of the present invention has a larger diameter than the outer diameter of the pile, a hole larger than the outer diameter of the pile can be excavated and easily settled without rotating the pile. Moreover, the earth and sand excavated from the notch provided in the circumferential part of the blade plate is raised upward, and the excavated earth receives the resistance of the earth and sand accumulated above, and a consolidation action is always generated. Therefore, a strong consolidated layer is formed around the pile.

  If the high pressure fluid is injected into the ground from the tip of the auger drill in the above method of sinking the pile, it facilitates excavation of difficult formations and contributes to stabilization of the formation around the pile. It is easy and preferable to form a supporting bulb in the supporting ground. Here, examples of the high-pressure fluid include compressed compressed air for agitation discharged from the auger drill tip during excavation, pile peripheral fluid injected into the ground in contact with the outer periphery of the pile, cement milk injected into the bulb portion, and high-pressure water.

As a member of the present invention for suitably carrying out the method of the present invention, it is composed of a disk having an outer diameter of 1.15 to 1.20 times the outer diameter of the pile, and an excavation blade is attached to the lower surface of the disk. Mounting, provided with a plurality of notches that open in the part larger than the outer diameter of the pile, with no openings other than the engagement holes that engage the auger drill in the part facing the inner diameter of the pile, and closes the lower end inner diameter of the pile A disc is provided with an inclined surface that guides earth and sand upward through the notch at the edge of the notch along with the forward rotation of the auger drill, and the tip of the auger drill is at the center of the disc. parts to maintain the engagement with the auger drill during forward rotation of the engaging auger drill, comprising a coupling structure separates from the reverse rotation when the auger drill auger drill, rotary spaced apart downwardly from the proximity or pile lower surface pile bottom surface A blade plate characterized by being capable of being used is used.

  By using this blade plate, the excavation hole larger than the outer periphery of the pile is excavated, so that the pile can easily sink without rotating, and the excavated soil rises from the notch of this blade plate, By forming a compacted cylinder of excavated soil and supplying a pile peripheral fluid to the compacted cylindrical part at a high pressure, a pile peripheral ground having a large bearing capacity can be formed.

Since the blade plate has an outer diameter of 1.15 to 1.20 times the outer diameter of the pile, a compacted cylinder of excavated soil having appropriate dimensions can be formed on the outer periphery of the pile. The diameter of the blade plate is made larger than the outer diameter of the pile because the mud that is stirred and mixed with compressed air is generated around the pile when the excavated soil rises through the notch of the blade plate. This is because it is possible to facilitate the installation of the above. In addition, the diameter of the blade plate is 1.15 to 1.20 times larger than the outer diameter of the pile in order to secure the tip support force of the large pile, by leaving the blade plate fixed in the support layer. , The pressure-receiving area of the bulb part is the square of 1.15 to 1.2, for example, pile supporting force Ra = αNAp (α: shaft-converting supporting force coefficient, N: ground N value, Ap: pile shaft area ), It is said that the bearing force coefficient α = 200 at the bottom of a normal ground, but by increasing the diameter, it is possible to ensure that the pile shaft equivalent supporting force coefficient is α≈350.

In the present invention by estimating the compaction degree of the type of soil from the construction experiment, the soil column-like view can be determined by calculating the discharge amount of soil for pile diameter and pile length in advance.

  According to the present invention, in a pile settling method that minimizes the discharge of excavated soil to the ground, the amount of discharged soil can be further reduced, and the pile can be lowered without rotating, thereby saving power. . Moreover, a compacted cylindrical layer is formed in the outer layer of the pile, and a large bulb is easily formed in the support layer, thereby increasing the support force.

  Further, the blade plate is left on the bottom of the bulb by rotating the auger drill in the reverse direction, and does not cause any difficulty in the work process.

  Embodiments of the present invention will be described below with reference to the drawings.

  The present invention is applied to PC (prestressed concrete) piles and RC (steel reinforced concrete) piles. The applied pile diameter is 300-1200 mm.

  Fig. 2 (a) is a longitudinal sectional view of a pile showing the situation during construction of the method of the present invention, and Fig. 2 (b) is a bottom view thereof. An auger drill 20 is inserted into the pile 10, and a blade plate 30 is engaged with the lower end portion of the auger drill 20.

  The auger drill 20 includes a drilling blade 21 at the lower end, and a spiral blade 22 is attached only to the lower end side of the shaft 23. The spiral blade 22 guides the excavated soil generated by excavating the auger drill 20 to the inside of the pile 10, and compacts and fills the pile 10. This action is achieved by providing only the lower end side of the shaft 23.

  The blade plate 30 is engaged with and attached to the lower end portion of the auger drill 20 and is integrally engaged when the auger drill rotates in the forward direction.

  FIG. 3A is a plan view of an embodiment of the blade plate 30, and FIG. 3B is a side view thereof.

  The blade plate 30 is made of a disk having a diameter larger than the outer diameter of the pile, and has a shape including a plurality of notches 31 around the disk. The notch 31 is opened only on the outer peripheral side of the pile 10 and is not opened inside the pile 10. As shown in FIG. 3B, the edge portions 32 and 33 of the notch 31 are inclined surfaces. The inclined surfaces of the edge portions 32 and 33 are respectively rotated by the blade plate 30 in the direction of the arrow 38 ( When the auger drill rotates forward), the excavated soil is guided upward from the lower surface side of the blade plate 30 to the upper surface side.

The lower surface of the cutter plate 30 is attached a cutting blade 34 excavated.

  Further, a hole 35 is opened at the center of the blade plate 30, and the hole 35 has a shape obtained by cutting a rectangular hole 36 from both sides of the center round hole, and two holes are formed on the lower surface of the plate. The projection 37 is provided. At the tip of the auger drill 20, as shown in FIG. 2 (b), the shaft 23 inserted from above through the hole 35 is provided with an engaging portion with a lateral bar 24 projecting sideways. When the shaft 23 is inserted through the hole 35 and the auger drill 20 is rotated 90 degrees in the forward rotation direction, the horizontal bar is positioned on the lower surface of the blade plate 30 and engages with the protrusion 37 as a stopper.

  When the auger drill 20 is rotated in the reverse direction, the blade plate 30 is detached from the auger drill 20 in the opposite manner.

FIG. 1A to FIG. 1H are process diagrams showing a pile setting method according to an embodiment of the present invention. The pile setting process is as follows.
(1) Pile erection As shown in FIG. 1 (a), a pile 10 is externally fitted to an auger drill 20, a cutter plate 30 is set on the lower end of the auger drill 20 on the ground, and a pile tip and a cutter plate , The forward rotation 25 of the auger drill 20 is started, and excavation of the ground 100 is started by the blade 21 and the blade plate 30 of the auger drill 20.
(2) Excavation and setting of piles (when N value of ground is small)
When the ground is soft and the N value is small, as shown in FIG. 1 (b), rotation 25 is given to the auger drill 20, the blade plate 30 is rotated forward through the auger drill shaft, the ground is excavated, and the pile is laid. To do. At this time, the excavated soil rises through the blade plate 30 and is consolidated around the pile. In order to enhance the consolidation effect, excavation is performed with the distance between the tip of the pile 10 and the blade plate 30 closed. Moreover, since it sinks easily even if it does not rotate a pile in the area where the N value of a ground is small, a rotation is not given to a pile.
(3) Pile excavation and sinking (when N value of the ground is large)
As shown in FIG. 1 (c), the blade plate 30 is rotated forward to excavate the ground. However, since the consolidation of the ground becomes difficult, the gap between the lower end 11 of the pile 10 and the blade plate 30 is increased. Then, the blade plate 30 is preceded below the lower end 11 of the pile 10, and as shown by an arrow 41, the excavated soil is caused to flow into the hollow portion of the pile 10 to promote pile setting. Therefore, in the middle of the pile 10 installation, the interval between the blade plate 30 and the lower end 11 of the pile 10, that is, the opening size of the inner diameter portion of the pile is adjusted while adjusting the hardness of the ground. In order to assist the sedimentation of the pile 10 during this process, the pile 10 may be disposed by being reversely rotated. In this step as necessary, for example, by discharging 0.7MPa compressed air from the auger drill point, or slurried with the groundwater and excavating the ground by mixing and stirring, or perform injection injection of high-pressure water, Rotating piles to make it easier to set up piles.

In the above excavation settlement process, the current value of the auger drill is confirmed, the support layer is confirmed, and the like. In addition, when the installation of the lower pile is completed, the set of the hired pile is replaced, the upper pile is connected by a joint, and the installation is continued.
(4) Support layer excavation When the excavation and settlement is advanced to a predetermined depth and the lower end 11 of the pile 10 reaches the support layer, the pile depth is set so as to penetrate into the support layer only by the penetration depth not less than the pile diameter. As shown to (d), the space | interval of the front-end | tip 11 of the pile 10 and the blade board 30 is narrowed, and the lower end of the pile 10 is made into a closed prone state.
(5) Pile circumference fixing liquid injection Next, as shown in FIG. 1 (e), the auger drill 20 is rotated forward while the tip of the pile 10 is closed, and the auger 20 is reversely rotated. A predetermined amount is injected while injecting 27 the pile periphery fixing liquid from the nozzle 26 of the drill 20 at an injection pressure of 5 to 15 MPa . Pile circumferential fixative through the notches 31 of the cutter plate 30 shown in FIG. 3, the consolidated bed in the outer periphery of the pile 10 rises as indicated by arrow 42 in FIG. 1 (e), the frictional force expression of piles 10 Improve. At this time, a split friction cutter is previously applied to the reinforcing band provided on the outer periphery of the tip of the pile 10 so that a gap is generated between the outer periphery of the pile 10 and the formation so that the pile fixing liquid can be smoothly injected. It is preferable that the pile 10 is rotated after being attached.
(6) Bulb construction After completion of the injection of the pile circumference fixing liquid, the auger drill is switched to low speed rotation, and a bulb is built in the support layer below the pile as shown in FIG. At this time, rotation 25 and thrust 61 are applied to the auger drill 20 and the blade plate 30 while spraying 27 the root hardening liquid at a high pressure of 20 MPa or higher, and the support layer is excavated and stirred to bear a large support force. Build bulb 51.
(7) Removing the blade plate After building the ball 51 having a predetermined height, as shown in FIG. 1 (g), when the auger drill 20 is reversely rotated 28, the blade plate 30 and the auger drill 20 are engaged. Is released. Thereafter, the auger drill 20 applies pulling force 62 and pulls it out on the ground while rotating in reverse.
(8) Pile construction completion FIG.1 (h) is sectional drawing which shows the construction completion state of the pile 10 after extracting an auger drill. The pile 10 is supported by a large bulb 51 and develops a large pile support force by hardening of the root hardening liquid. The blade plate 30 is left in the bulb 51, and no special process is required for its operation. A support layer 43 having an excellent frictional force is formed on the outer periphery of the pile 10 and has a stable formation and pile support force due to solidification of the pile periphery fixing liquid. The pile is filled with the excavated soil 63 in a compacted state, and the excavated soil is discharged to the ground with zero or a very small amount.

It is process drawing of the Example of this invention. It is process drawing of the Example of this invention. It is process drawing of the Example of this invention. It is process drawing of the Example of this invention. It is process drawing of the Example of this invention. It is process drawing of the Example of this invention. It is process drawing of the Example of this invention. It is process drawing of the Example of this invention. It is a longitudinal cross-sectional view of the pile which shows the condition under construction of this invention method. FIG. 3 is a bottom view of FIG. It is a top view of the Example of the blade board 30. FIG. FIG. 4 is a side view of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Pile 11 Lower end 20 Auger drill 21 Drilling blade 22 Spiral blade 23 Shaft 24 Horizontal bar 25 Forward rotation 26 Nozzle 27 Injection 28 Reverse rotation 30 Cutlery plate 31 Notch 32, 33 Edge 34 Drilling blade 35 Hole 36 Rectangular hole 37 Protrusion 38 Arrow 41 Arrow 42 Arrow 43 Support layer 51 Bulb 61 Thrust 62 Lifting force 63 Excavated soil 100 Ground

Claims (3)

In a method of inserting an auger drill into a pile and sinking the pile into the ground while excavating with the auger drill,
(A) A plurality of notches having a diameter larger than the outer diameter of the pile and opened at the top and bottom of the outer periphery, and a blade plate having a drilling blade on the lower surface is attached to the lower end of the auger drill,
(B) The auger drill is provided with a spiral blade only on the lower end side of the entire length,
(C) In the ground where the N value is a certain value or less, the pile lowers while the excavated soil is consolidated to the outer periphery of the pile without rotating the auger drill by bringing the lower end of the pile close to the blade plate and rotating the pile. In the ground where the N value exceeds a certain value, drilling with the auger drill leading below the lower end of the pile, sinking the pile while consolidating the excavated soil in the pile,
(D) After the lower end of the pile reaches the support layer, by rotating and thrusting the auger drill and the blade plate while spraying the root hardening liquid from the nozzle of the auger drill , the support layer is excavated and stirred. A pile settling method comprising: forming a bulb therein, reversing the auger drill, leaving the blade plate in the bulb, and lifting the auger drill.   2. The pile settling method according to claim 1, wherein high pressure fluid is injected into the ground from the auger drill tip.   It consists of a disk with an outer diameter of 1.15 to 1.20 times the outer diameter of the pile, and an excavation blade is attached to the lower surface of the disk, and a plurality of notches opened in a portion larger than the outer diameter of the pile Provided, a portion facing the inner diameter of the pile is not provided with an opening other than an engagement hole that engages with the auger drill, and is a disc that closes the inner diameter of the lower end of the pile. With the forward rotation of the auger, it has a slope that guides the soil upward through the notch, engages the tip of the auger drill at the center of the disc, and engages with the auger drill during the forward rotation of the auger drill A cutter plate characterized in that it has a coupling structure that keeps and separates from the auger drill when the auger drill rotates in reverse, and is rotatable close to the lower surface of the pile or spaced downward from the lower surface of the pile.

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