JP2848100B2 - Underground pile driving method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mid-digging pile driving method for embedding a hollow ready-made pile such as a steel pipe pile or a PC pile in the ground, and more particularly, to a method for excavating soil in an auger blade for excavating a hollow ground of a pile. The present invention relates to a technical improvement for preventing non-sticking.

[0002]

2. Description of the Related Art As is well known, in a mid-digging pile driving method, a pile is laid by excavating a hollow portion of a ready-made pile by applying its own weight, press-fitting, or hitting. An earth auger is generally used for excavation in a pile. This digging type pile driving method is suitable for reducing noise and vibration caused by pile driving.

[0003]

[0009] In the case of the middle-digging type pile driving method, the excavation of the soil and the excavation of the excavated soil from the pile head can be smoothly carried out, and the construction speed can be reduced. This is an important point in improving. A major problem in excavation and excavation work is that the auger blades are liable to sediment. Especially when excavating highly viscous ground with an earth auger, the frictional force, adhesion and bonding force between the auger blade and the earth and sand are large, so the excavation resistance is large and the excavation is at a satisfactory speed even with a large torque driving device Can not do it. Also, when the excavated earth and sand is discharged from the pile head, the viscous soil is firmly attached to the auger blade, so it takes a lot of trouble to scrape off the soil. Usually, the soil attached to the auger blade is removed manually using a scoop or the like. Although a scraping device for automating this operation has been developed, there is a problem that the mechanical equipment on the ground side is complicated and large. Especially in the medium digging type pile driving method, a device that presses or hits the pile while excavating is attached to the earth auger, so the device on the ground side alone is complicated, and a device for scraping off attached sediment is further added. Hard to do.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned conventional problems, and has as its object the purpose of performing a mid-digging pile driving method using an earth auger, the frictional force between an auger blade and excavated earth and sand, and an additional force. An object of the present invention is to make excavation and excavated earth and sand discharge processing efficient by weakening the bonding force and the binding force.

[0005]

Therefore, according to the present invention, a hollow ready-made pile partially or entirely made of a metal member is erected, and the ground is excavated in the hollow part of the pile by an earth auger while the pile is underground. In the digging type pile driving method, the auger blade is a negative pole between the auger blade in the ground during the pile driving process or after the pile driving and the metal member of the pile, and the DC A voltage is applied and energized, and electrolysis is caused by the electrolyte solution contained in the earth and sand in the hollow portion of the pile to generate hydrogen gas from the surface of the auger blade, thereby forming a bond between the auger blade and the earth and sand. I tried to weaken it.

[0006]

The ground under normal conditions contains a considerable amount of water and contains a large amount of electrolyte. Therefore, when two electrodes are inserted into the ground and a DC voltage is applied, an electrolysis reaction occurs between the electrodes via the electrolyte solution in the earth and sand, and hydrogen gas is generated on the negative electrode side. The same phenomenon occurs between the auger blade and the metal member of the pile, and hydrogen gas is generated from the surface of the auger blade. Due to the expansion of the gas at the time of the gas generation, the surface of the auger blade is separated from the earth and sand mass, the frictional force of the earth and sand against the rotation of the auger blade is reduced, and the earth and sand attached to the blade is also easily dropped. . Also, due to the electroosmosis phenomenon, moisture in the ground collects on the minus pole (auger blade) side, and the effect of softening the earth and sand around the surface of the auger blade also occurs, thereby further enhancing the above-described gas generation effect.

[0007]

FIG. 1 shows a state in which a PC pile is laid by a medium digging type pile driving method. As shown in the figure, the support column 2 is vertically supported by the base machine 1, and the auger driving device 3,
The pile press-in device 4 and the pile head holding device 5 are mounted so as to move up and down while being guided by the columns 2. PC pile 6
Is vertically erected along the column 2, and a pile head holding device 5 is applied to the upper end thereof, and a hydraulically driven pile press-in device 4 is provided.
Applies a pressure input to the PC pile 6 via the pile head holding device 5. A long auger shaft 7 extending downward from the auger driving device 3 penetrates the pile press-in device 4 and the pile head holding device 5 and enters the hollow portion of the PC pile 6. A screw-shaped auger blade 8 is integrally provided around the auger shaft 7, and the auger drive device 3 rotates the auger blade 8 to excavate the ground in the hollow portion of the PC pile 6. The above is a general embodiment of the inside digging type pile driving method using the earth auger.

Next, the features of the present invention will be described in detail.

As shown in detail in FIG. 2, a typical PC pile 6 has metal rings 6 at its upper and lower ends, respectively.
a is integrally provided, and a steel rod 6b is embedded inside the steel rod 6b over its entire length. The metal rings 6a at the upper and lower ends of the pile 6 are electrically connected via a steel bar 6b. The metal ring 6a and the steel bar 6b correspond to the metal members of the above-mentioned ready-made pile.

In this embodiment, an appropriate DC power supply 9 is prepared, and a metal ring 6a at the head of the PC pile 6 is connected to a positive terminal of the power supply 9 via a lead wire 10. The lead wire 10 and the metal ring 6a are firmly connected to each other through appropriate fasteners or by welding, and the metal ring 6a and the pile head holding device 5 are electrically insulated from each other. The configuration is such that only the insulating material 5a of the part holding device 5 contacts the metal ring 6a. Thus, the metal ring 6a at the tip of the PC pile 6 buried underground and the steel bar 6b inside are connected to the positive pole of the DC power supply 9.

On the other hand, the auger shaft 7 and the auger blade 8 are made of metal and are connected to the negative pole of the DC power supply 9 in the following configuration. That is, the slip ring 11 that rotates integrally with the shaft is attached to the outer periphery of the root portion of the auger shaft 7, and the brush 12 that always slides on the slip ring 11.
To the frame portion of the auger drive 3. Then, the brush 12 and the negative terminal of the DC power supply 9 are connected by the lead wire 13.

In the process of driving the pile 6, the metal ring 6a, the steel rod 6b, and the auger blade 8 at the tip of the pile are underground. When a DC voltage having the above-mentioned polarity is applied to the auger blade 8 and the metal ring 6a existing in the ground with earth and sand therebetween, an electric current flows through the electrolyte solution in the earth and sand to cause an electrolysis reaction.
As a result, the negative pole of the auger blade 8 and the auger shaft 7
Hydrogen gas is generated from the surface of the underground part, and moisture in the earth and sand collects on the minus pole side. At the time of gas generation, the earth and sand mass adhering to the surfaces of the auger shaft 7 and the auger blade 8 are separated from the surface of the auger blade 8 so as to float due to the expansion action of the gas.

Therefore, if excavation and pile driving are performed while energizing the DC power source 9 as described above, the auger blade 8
Excavation can be smoothly and efficiently performed in a state where the resistance of the earth and sand to the rotation of the soil is small.

When the pile driving is completed, the other mechanical equipment is moved to the next pile driving place together with the base machine 1 while the used auger blade 8 (auger shaft 7) remains in the pile. Electricity is supplied between the metal ring 6a of the driven pile 6 and the remaining auger blade 8 with the above-mentioned polarity for an appropriate time. Thereafter, when the remaining auger blade 8 is extracted with a crane or the like, the above-described effect of preventing the adhesion of the earth and sand by the energization is exerted, the earth and sand attached to the auger blade 8 easily falls off, and the work of scraping and removing the earth and sand is performed. Significant labor savings.

[0015]

As described above in detail, according to the present invention, a DC voltage is applied to the metal member of the pile to be driven and the auger blade for excavation in the mid-digging type pile driving method, thereby energizing underground. By means of simple equipment that can be easily implemented, the frictional force and resistance of earth and sand against the auger blade during excavation can be greatly reduced, and drilling and pile driving can proceed smoothly and efficiently with relatively small torque. Can be. Even when the excavated earth and sand is discharged, the earth and sand mass easily falls off the auger blade, so that the post-processing work is also very simple.

[Brief description of the drawings]

FIG. 1 is a view showing an embodiment of a middle digging type pile driving method according to an embodiment of the present invention.

FIG. 2 is a detailed view of a main part of the embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Base machine 2 Prop 3 Auger drive 4 Pile press-in device 5 Pile head holding device 6 PC pile 6a Metal ring 6b Steel rod 7 Auger shaft 8 Auger blade 9 DC power supply 10 Lead wire 11 Slip ring 12 Brush 13 Lead wire

Continuation of front page (72) Inventor Isamu Kuroshima 2-3-3 Kandaji-cho, Chiyoda-ku, Tokyo Obayashi Corporation Tokyo head office (56) References JP-A-59-192129 (JP, A) JP-A-52-155808 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) E02D 7/00

Claims (1)

(57) [Claims] 1. A mid-digging type pile driving method in which a hollow prefabricated pile partially or entirely made of a metal member is erected, and the pile is submerged in the ground while excavating the ground in the hollow portion of the pile with an earth auger. In the pile driving process or between the metal member of the pile and the auger blade in the ground after the pile driving, the auger blade is a negative pole and the metal member is a positive pole, and a DC voltage is applied and energized, An inner digging method characterized in that electrolysis is caused by the electrolyte solution contained in the earth and sand in the hollow portion of the pile to generate hydrogen gas from the surface of the auger blade, thereby weakening the bond between the auger blade and the earth and sand. Pile driving method.