JPH05287739A - Inner excavation type pile driving method - Google Patents

Abstract

PURPOSE:To improve the efficiency of disposal of excavated and discharged earth by a method wherein energization is applied between an auger blade for inner excavation for driving of a pile and the metallic member of a pile and binding between the blade and earth is weakened by means of hydrogen gas generated from an auger blade surface through electrolysis. CONSTITUTION:A DC source 9 is first prepared and a metallic rod 6a of the head part of a PC pile 6 is connected to the plus terminal of the power source 9 through a lead wire 10. Only an insulating material 5a of a pile head part press device 5 is brought into contact with the metallic ring 6a, and the metallic ring 6a at the tip of the PC pile 6 buried in a ground and an internal steel rod 6b are connected to the plus pole of the DC source 9. A slip ring 11 rotated integrally with a shaft is attached to the outer periphery of the root part of an auger shaft 7 and a brush 12 making constant slide contact with the slip ring is mounted on the frame part of an auger drive device 3. Further, the brush 12 is connected to the minus terminal of the DC source 9 through a lead wire 13. In a drive process of the pile 6, a DC voltage is applied on an auger blade 8 and the metallic ring 6a for energization.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hollow digging method for embedding hollow prefabricated piles such as steel pipe piles and PC piles in the ground, and particularly to earth and sand for auger blades for excavating the ground in the hollow portion of the pile. The present invention relates to technical improvements for preventing non-adhesion.

[0002]

2. Description of the Related Art As is well known, in the medium excavation type pile driving method, the pile is sunk by applying weight, press-fitting, or striking the pile while excavating the hollow portion of the ready-made pile. An earth auger is generally used for excavation in the pile. If you want to reduce the noise and vibration associated with pile driving, this hollow-digging method is suitable.

[0003]

[Problems to be Solved by the Invention] In the case of the medium excavation type pile driving method, it is possible to smoothly advance the excavation of the earth and sand accompanying the sinking of the pile and the process of discharging the excavated earth and sand from the pile head, thereby increasing the construction speed. This is an important point to improve. A major problem in the work of excavation and discharge of excavated sediment is that sediment tends to adhere to the auger blade. Especially when excavating highly viscous ground with an earth auger, the frictional force, the adhesion force, and the binding force between the auger blade and the sand are large, so the excavation resistance is large, and even if a driving device with a large torque is used, the excavation is performed at a satisfactory speed. Can not do it. Further, even when the excavated soil is discharged from the pile head, the cohesive soil is firmly attached to the auger blade, so that it is very troublesome to scrape it off. Normally, a scoop is used to manually remove the attached soil from the auger blade. A scraping device for automating this work has also been developed, but there is a problem that mechanical equipment on the ground side is complicated and large. Especially in the medium excavation type pile driving method, a device for press-fitting or striking piles while excavating is attached to the earth auger, so this alone complicates the device on the ground side, and a device for scraping off adhered sand is added. It's hard to do.

The present invention has been made in view of the above-mentioned conventional problems, and an object thereof is to carry out a frictional force between an auger blade and excavated earth and sand when carrying out a medium excavation type pile driving method using an earth auger. The purpose is to weaken the cohesive force and the binding force so that excavation and excavation of excavated soil can be performed efficiently.

[0005]

Therefore, in the present invention, hollow prefabricated piles partially or wholly made of metal members are erected and the piles are grounded while excavating the ground in the hollow portions of the piles with an earth auger. In the medium excavation type pile driving method, the auger blade is a negative pole and the metal member is a positive pole between the metal member of the pile and the auger blade in the ground after the pile driving process or DC driving. Applying a voltage and energizing, electrolysis is generated through the electrolyte solution contained in the earth and sand in the hollow portion of the pile to generate hydrogen gas from the auger blade surface, thereby binding the auger blade and the earth and sand. I tried to weaken it.

[0006]

[Function] The ground under normal conditions contains a considerable amount of water and also contains a large amount of electrolyte. Therefore, when two electrodes are inserted into the ground and a DC voltage is applied, an electrolytic 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 gas generation, the surface of the auger blade and the earth and sand lumps are separated, 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 easily removed. .. Further, due to the electroosmosis phenomenon, moisture in the ground gathers on the minus electrode (auger blade) side, and the soil around the surface of the auger blade is softened, which further enhances the gas generation effect.

[0007]

[Example] Fig. 1 shows a state in which a PC pile is sunk by the medium excavation type pile driving method. As shown in the figure, the support 2 is vertically supported by the base machine 1, and the auger drive device 3,
The pile press-fitting device 4 and the pile head pressing device 5 are attached to the pillar 2 so as to be vertically moved. PC pile 6
Is erected vertically along the column 2, and the pile head pressing device 5 is applied to the upper end thereof, and the hydraulically driven pile press-fitting 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 drive device 3 penetrates the pile press-fitting device 4 and the pile head pressing 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. The auger driving 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 medium excavation type pile driving method using an earth auger.

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

As shown in detail in FIG. 2, in a general PC pile 6, a metal ring 6 is provided at each of the upper end and the lower end.
a is integrally attached, and a steel rod 6b is embedded in the inside over the entire length. The metal rings 6a at the upper and lower ends of the pile 6 are electrically connected via the steel rod 6b. The metal ring 6a and the steel rod 6b correspond to the metal member of the above-described ready-made pile.

In this embodiment, an appropriate DC power supply 9 is prepared, and the metal ring 6a on the head of the PC pile 6 is connected to the plus terminal of the power supply 9 via the lead wire 10. The lead wire 10 and the metal ring 6a are firmly connected to each other via a suitable fastener or by welding so that the metal ring 6a and the pile head pressing device 5 are electrically insulated. Only the insulating material 5a of the part pressing device 5 contacts the metal ring 6a. With this, the metal ring 6a at the tip of the PC pile 6 buried in the ground and the steel rod 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 source 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 base portion of the auger shaft 7, and the brush 12 that is always in sliding contact with the slip ring 11 is attached.
Is attached to the frame portion of the auger drive device 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 6 are in the ground. When a direct current voltage is applied to the auger blade 8 and the metal ring 6a existing in the ground with sand and sand sandwiched therebetween, a current flows through the electrolyte solution in the sand and electrolysis reaction occurs.
As a result, the auger blade 8 and the auger shaft 7 that are negative poles
Hydrogen gas is generated from the surface of the underground part of, and the water content in the soil gathers on the negative pole side. At the time of gas generation, due to the expansion action of the gas and the like, the lump of earth and sand adhering to the surface of the auger shaft 7 and the auger blade 8 is separated so as to float.

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

Further, when the pile driving is completed, other mechanical equipment is moved to the next pile driving place together with the base machine 1 while the used auger blades 8 (auger shaft 7) are left in the pile, and in the meantime. Electricity is applied between the driven metal ring 6a of the pile 6 and the remaining auger blade 8 with the above polarity for an appropriate period of time. After that, when removing the remaining auger blades 8 with a crane or the like, the effect of preventing the adhesion of the above-mentioned earth and sand due to energization is exerted, the earth and sand adhering to the auger blades 8 easily drop off, and the work of scraping and removing the earth and sand is performed. Significant labor savings.

[0015]

As described in detail above, according to the present invention, a DC voltage is applied to the metal member of the pile driven in the medium excavation type pile driving method and the excavating auger blade to energize in the ground. By means that can be easily implemented with such simple equipment, it is possible to greatly reduce the frictional force and resistance force of the earth and sand against the auger blade during excavation, and to smoothly and efficiently excavate and pile with relatively small torque. You can Even when the excavated sediment is discharged, the mass of sediment easily falls off from the auger blade, so the post-treatment work is also very easy.

[Brief description of drawings]

FIG. 1 is a diagram showing an embodiment of a medium excavation type pile driving method according to an embodiment of the present invention.

FIG. 2 is a detailed view of the essential parts of the above embodiment.

[Explanation of symbols]

 1 Base Machine 2 Support 3 Auger Drive 4 Pile Press-in Device 5 Pile Head Presser 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 the front page (72) Inventor Isamu Kuroshima 2-3 Kandaji-cho, Chiyoda-ku, Tokyo Obayashi Corporation Tokyo Head Office

Claims (1)

[Claims] 1. A hollow excavated pile driving method in which hollow prefabricated piles partially or wholly made of metal members are erected, and the piles are sunk into the ground while excavating the ground in the hollow portion of the piles with an earth auger. In, in the pile driving process or after pile driving in the ground between the auger blade and the metal member of the pile, the auger blade is a negative pole and the metal member is a positive pole, and a DC voltage is applied to apply electricity. A hollow excavation method characterized by weakening the bond between the auger blade and the earth and sand by causing electrolysis through the electrolytic 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. Pile driving method.