Pile driving method

Abstract

To provide a pile head striking cap, a pile driver equipped with the same, and a pile driving method, which enable high-quality, low-cost construction of ready-made piles such as steel pipe piles by striking the piles without vibrating them.SOLUTION: A pile head striking cap 21 for striking a pile head of a ready-made pile 24 comprises: a cap body 25 fitted to the pile head so as to be movable in a pile axis direction; and a striking part 28 provided on the cap body 25 and applying a striking force to the pile head. The cap body 25 is cylindrical, and the striking part 28 is an annular projection formed on an inner circumference of the cap body 25.SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] The present invention relates to a pile driving method. [Background technology]

[0002] A known method for driving precast piles, particularly steel pipe piles, into the ground is the steel pipe pile with internal excavation and vibro-drilling. In this method, a pile driver, such as that described in Patent Document 1, is used to excavate the ground first with a screw auger inserted into the steel pipe pile, and when driving through a hard intermediate layer, a vibration excitation device mounted on the leader is used to vibrate the pile body and press it into the ground.

[0003] Furthermore, if a problem such as the pile tilting occurs during pile construction, the pile body is grasped and vibrated with a chuck mechanism connected to the vibration excitation device, and then pulled out once, and then pressed back in, ensuring the pile's vertical accuracy, enabling high-quality, low-cost construction of ultra-long steel pipe piles and other structures.

[0004] However, methods of vibrating piles to press them into the ground (such as the above method, the vibrohammer method, and the vibration method) are no longer applicable to the 2017 Road Bridge Specifications, and therefore can no longer be used in construction projects designed in accordance with these specifications. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2013-53495 Summary of the Invention [Problem to be solved by the invention]

[0006] The present invention has been made based on the above technical background and has the following objectives. The object of this invention is to provide a pile driving method that enables the installation of prefabricated piles such as steel pipe piles at high quality and low cost by striking the piles without vibrating them. [Means for solving the problem]

[0007] In order to achieve the above object, the present invention employs the following means. That is, the present invention is With the leader, a rotation drive device provided on the reader so as to be able to move up and down; a vibration generating device provided on the leader below the rotation drive device so as to be able to move up and down; a striking cap connected to the lower part of the vibration generating device, the cap having a cylindrical cap body that is fitted to the head of the prefabricated pile and is movable in the axial direction of the pile, and the cap body has a striking part formed of an annular protrusion on its inner periphery; A pile driving method using a pile driver equipped with a screw auger connected to the output shaft of the rotary drive device, penetrating the vibration excitation device and the pile head striking cap, and inserted into a prefabricated pile, The pile head of the prefabricated pile is fitted into the pile head striking cap, A pile driving method characterized by transmitting only downward displacement of the vertical displacement caused in the pile head striking cap by the vibration of the vibration excitation device to the pile head of the prefabricated pile via the striking part while the ground is pre-excavated by the screw auger, thereby striking the prefabricated pile and pressing it into the ground. is located.

[0008] The pile head striking cap may be configured to include a chuck member provided on the cap body for gripping the pile head.

[0010] In addition, the chuck member can be configured to have a plurality of chuck claws housed in a plurality of holes spaced circumferentially in the peripheral wall of the cap body, and each chuck claw can be freely moved forward and backward radially toward the inside of the cap body. [Effects of the Invention]

[0013] According to this invention, by striking the pile without vibrating it, it is possible to install prefabricated piles such as steel pipe piles with high quality and at low cost. [Brief explanation of the drawings]

[0014] [Figure 1] FIG. 1 is a side view showing an embodiment of a pile driver used in the construction method of the present invention. [Figure 2] FIG. 2 is an enlarged side view showing a main part of the embodiment. [Figure 3] FIG. 2 is an enlarged front view showing a main part of the embodiment. [Figure 4] FIG. 1 is a plan view showing an embodiment of a pile head striking cap used in the construction method of the present invention. [Figure 5]FIG. [Figure 6] FIG. 5 is a cross-sectional view taken along the line AA in FIG. 4. DETAILED DESCRIPTION OF THE INVENTION

[0015] An embodiment of the present invention will be described below with reference to the drawings. Used in construction methods 2 and 3 are enlarged side and front views, respectively, showing the main parts of the pile driver 10. The pile driver 10 includes a base machine 11 having a lower traveling body 11a that travels on crawlers and a rotatable upper rotating body 11b. The lower end of a leader 12 that can be raised or lowered by a stay 13 is rotatably mounted on the upper rotating body 11b.

[0016] The leader 12 is provided with a guide rail 14, and a rotary drive device 15 and a vibration generator 16 are mounted below the rotary drive device 15 so that they can move up and down along the guide rail 14. The rotary drive device 15 is suspended by a wire 18 wound around a top sheave 17. The rotary drive device 15 moves up and down by letting out and reeling in the wire 18 with a winch (not shown).

[0017] The vibration exciter 16 is also suspended by a wire (not shown) wound around the top sheave 17, and is raised and lowered by the payout and retraction operations of a winch (not shown). A pulley 19 shown in Figures 2 and 3 is used to wind the wire that suspends the vibration exciter 16.

[0018] An earth removal device 20 is connected and fixed to the lower part of the vibration exciter 16, and a pile head striking cap 21 is further connected and fixed to the lower part of the earth removal device 20. As shown in Figure 1, a screw auger 23 is connected to the output shaft 22 of the rotary drive device 15, and this screw auger 23 is arranged to pass through the vibration exciter 16, the earth removal device 20, and the pile head striking cap 21, and is further inserted into the inside of a prefabricated pile 24, such as a steel pipe pile, whose head is fitted with the pile head striking cap 21.

[0019] The vibration generator 16 has a pair of rotors (not shown) made of eccentric weights inside, and generates vertical vibrations by rotating these rotors in opposite directions. The vibrations of the vibration generator 16 are transmitted to the pile head striking cap 21 via the soil removal device 20.

[0020] The earth removal device 20 is for discharging the excavated earth and sand that has been excavated by the screw auger 23 and rises inside the precast pile 24. The excavated earth and sand is discharged from a horizontal opening 20a provided in the earth removal device 20.

[0021] Figure 4 shows the invention Used in construction methods Fig. 5 is a plan view showing an embodiment of the pile head striking cap, Fig. 6 is a cross-sectional view taken along line AA in Fig. 4. The pile head striking cap 21 comprises a cylindrical cap body 25 into which the pile head of a prefabricated pile 24 is fitted so as to be movable in the axial direction of the pile. As described above, the screw auger 23 passes through the cap body 25, so both the top and bottom ends of the cap body 25 are open.

[0022] A flange 26 is provided at the upper end of the cap body 25, and the pile head striking cap 21 is connected and fixed to the lower end of the earth removal device 20 via this flange 26. A number of holes 27 are provided at intervals around the circumferential direction in the flange 26 for passing bolts that secure the earth removal device 20 and the pile head striking cap 21.

[0023] An annular protrusion 28 is formed on the inner periphery of the cap body 25. This annular protrusion 28 constitutes a striking portion that strikes the head of the prefabricated pile 24 that is fitted into the cap body 25 from below. Therefore, the lower surface of the annular protrusion 28 is flat and constitutes a striking surface 29. The annular protrusion 28 is not limited to a circumferentially continuous annular protrusion as in the illustrated embodiment, but may be configured to be annular as a whole by a plurality of protrusions protruding from the inner periphery of the cap body 25.

[0024] A chuck member 30 is provided on the peripheral wall of the cap body 25 to grip the prefabricated stake 24 fitted into the cap body 25. The chuck member 30 has a plurality of chuck claws 31a, 31b (three in this embodiment), and these chuck claws 31a, 31b are housed in a plurality of holes 32 provided at intervals in the circumferential direction on the peripheral wall of the cap body 25, and can freely advance and retreat radially toward the inside of the cap body 25.

[0025] Of the chuck jaws 31a and 31b, the two chuck jaws 31b are moved back and forth by an actuating cylinder 33, such as a hydraulic cylinder, which is provided laterally on the outer periphery of the cap body 25, and the chuck jaw 31a is moved back and forth by an actuating cylinder 34, such as a hydraulic cylinder, which is provided diagonally upward on the outer periphery of the cap body 25.

[0026] 1 shows the state of a precast pile 24 during construction. At this time, the head of the precast pile 24 is fitted into the striking cap 21, but is no longer gripped by the chuck member 30. The screw auger 23 inserted into the precast pile 24 is rotated by the drive of the rotary drive device 15, and the ground is excavated in advance.

[0027] The excavated soil rises through the precast piles 24 and is discharged from the discharge port 20a of the soil discharge device 20. When the ground is pre-excavated, the precast piles 24 sink due to their own weight and also due to the downward force applied to the piles by a tightening wire (not shown). However, when it becomes necessary to drill through a particularly hard intermediate layer, the vibration exciter 16 is activated depending on the strength of the ground.

[0028] When the vibrator 16 is activated, the vibration is transmitted to the striking cap 21 via the soil removal device 20. As a result, the striking cap 21 is displaced up and down at a predetermined frequency set in the vibrator 16, as shown by the arrow in Figure 6.

[0029] However, when the striking cap 21 is displaced upward, the striking portion 28 moves away from the head of the precast pile 24, so that displacement is not transmitted to the head of the pile, and only the downward displacement of the striking cap 21 is transmitted to the head of the pile. In other words, the vibration of the vibration exciter 16 is transmitted as a striking force to the head of the precast pile 24 via the striking portion 28 of the striking cap 21. This striking force efficiently presses the precast pile 24 into the ground.

[0030] If a problem such as tilting of the precast pile 24 occurs during installation, the operation of the rotary drive device 15 and the vibration excitation device 16 is temporarily stopped. Then, the operating cylinders 33 and 34 of the chuck member 30 are operated, and the head of the precast pile 24 is gripped by the chuck claws 31a and 31b. This makes it possible to temporarily pull out the precast pile for driving correction.

[0031] According to the above embodiment, by using the striking cap, it is possible to strike the head of the pile rather than vibrating the prefabricated pile, thereby enabling high-quality and low-cost pile construction.

[0032] Furthermore, by using a vibration generator as a source of impact force, construction can be carried out efficiently without generating large noise.

[0033] The above embodiment is merely an example, and the present invention can take various forms. In the above embodiment, the striking cap is configured so that the pile head fits into its inner periphery, but it can also be configured so that the pile head fits into the outer periphery of the striking cap. In this case, since it is difficult to provide a chuck member on the striking cap, the chuck member may be installed separately. [Explanation of symbols]

[0034] 10: Pile driver 12: Leader 15: Rotation drive device 16: Excitation device 20:Earth removal equipment 21: Pile head impact cap 23: Screw Auger 24: Prefabricated pile 25: Cap body 28: Ring-shaped protrusion 29: Striking surface 30: Chuck member 31a, 31b: Chuck jaws 33, 34: Working cylinder

Claims

[Claim 1] A reader; a rotation drive device provided on the reader so as to be able to move up and down; a vibration generating device provided on the leader below the rotation drive device so as to be able to move up and down; a striking cap connected to the lower part of the vibration generating device, the cap having a cylindrical cap body that is fitted to the head of the prefabricated pile and is movable in the axial direction of the pile, and the cap body has a striking part formed of an annular protrusion on its inner periphery; A pile driving method using a pile driver equipped with a screw auger connected to the output shaft of the rotary drive device, penetrating the vibration excitation device and the pile head striking cap, and inserted into a prefabricated pile, The pile head of the prefabricated pile is fitted into the pile head striking cap, A pile driving method characterized by the fact that while the ground is excavated in advance with the screw auger, only the downward displacement of the vertical displacement caused in the pile head striking cap by the vibration of the vibration excitation device is transmitted to the pile head of the prefabricated pile via the striking section, thereby striking the prefabricated pile and pressing it into the ground.

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