CAVE CUTTING METHOD FOR PILLAR CONSTRUCTION

Description

TECHNICAL FIELD

The present disclosure relates to a method for excavating a pole erection hole using a casing tube.

BACKGROUND ART

A pole erection hole is manually excavated to the depth of about 1.5 m so as not to damage a buried object, and then excavated to a desired depth using a digger derrick truck. Manual excavation work is a time-consuming work with a large burden on the body.

A related method for excavating a pole erection hole is illustrated in FIG. 1. In FIG. 1, a reference sign 51 denotes an earth auger drill, and a reference sign 52 denotes a digger derrick truck. The earth auger drill 51 hung on the tip of a crane of the digger derrick truck 52 is rotated to excavate a pole erection hole (see, for example, Patent Document 1).

Since the earth auger drill 51 always digs soil and sand by rotation, the dug soil and sand need to be discarded manually or by a heavy machine as needed.

CITATION LIST

Patent Literature

Patent Literature 1: JP 8-177364 A

SUMMARY OF INVENTION

Technical Problem

However, in these related methods for excavating a pole erection hole, there is an issue that, while it takes a lot of time and a burden on the body if the manual excavating work is performed in the initial stage, if the earth auger drill 51 is used from the initial stage avoiding the manual excavation, an excavation force of the earth auger drill 51 becomes so large that a buried object is damaged.

An object of the present disclosure is to realize excavation of a pole erection hole by a machine to improve the efficiency of excavation work.

Solution to Problem

A method for excavating a pole erection hole of the present disclosure includes vibrating, by the vibrator, the casing tube to cause the casing tube to penetrate into the ground.

Specifically, the present disclosure is a method for excavating a pole erection hole including

• • a step 1 of suspending a vibrator to which a cylindrical casing tube is attached and disposing the vibrator on a surface of a ground,
  • a step 2 of vibrating, by the vibrator, the casing tube to cause the casing tube to penetrate into the ground, and
  • a step 3 of stopping vibration of the vibrator when the casing tube penetrates to a predetermined depth.

In the present disclosure,

• • the step 2 includes stopping vibration of the vibrator when the vibrator detects contact with a buried object.

In the present disclosure,

• • the vibrator detects contact with a buried object when the vibrator detects a pressure in a vertical direction larger than a predetermined value.

In the present disclosure

• • the vibrator detects contact with a buried object when the vibrator detects a penetration speed smaller than a predetermined value.

The present disclosure further includes

• • a step 4A of lifting soil inside the casing tube together with the casing tube and discarding the soil after the step 3.

The present disclosure further includes

• • a step 4B of stirring, sucking, and discarding soil inside the casing tube after the step 3.

The present disclosure further includes

• • a step 4C of connecting a utility pole to an upper surface of the casing tube after the step 3.

Note that, the inventions disclosed above can be combined where possible.

ADVANTAGEOUS EFFECTS OF INVENTION

According to the present disclosure, it is possible to realize excavation of a pole erection hole by a machine to improve the efficiency of excavation work.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a view for illustrating a relevant method for excavating a pole erection hole.

FIG. 2 is a view for illustrating a method for excavating a pole erection hole of the present disclosure.

FIG. 3 is a cross-sectional view of an example of a casing tube.

FIG. 4 is a view for describing a step of discharging soil.

FIG. 5 is a view for describing a step of discharging soil.

FIG. 6 is a view for describing a step of discharging soil.

FIG. 7 is a view for describing a step of discharging soil.

FIG. 8 is a view for describing a step of connecting a utility pole.

FIG. 9 is a view illustrating an example of connecting a utility pole.

FIG. 10 is a view illustrating an example of connecting a utility pole.

DESCRIPTION OF EMBODIMENTS

Hereinafter, an embodiment of the present disclosure will be described in detail with reference to the drawings. Note that, the present disclosure is not limited to the embodiment to be described below. These embodiment example is merely exemplary, and the present disclosure can be implemented in forms of various modifications and improvements based on the knowledge of those skilled in the art. Note that, components having the same reference signs in the present specification and the drawings indicate the same components.

A method for excavating a pole erection hole of the present disclosure will be described with reference to FIG. 2. A vibrator 11 to which a casing tube 12 is attached is transported by a carrying vehicle 13 to a place where a pole is erected. As the carrying vehicle 13, a digger derrick truck that has transported an earth auger drill may be used, or the vibrator may be transported by a carry.

Step 1

The vibrator 11 to which the casing tube 12 is attached is suspended and disposed on the ground surface. In a case of transportation by a digger derrick truck, the vibrator 11 is suspended by a crane of the digger derrick truck and disposed on the ground surface. In a case of transportation by a carry, the vibrator is suspended by a derrick and disposed on the ground surface.

The shape of the casing tube 12 may be a cylindrical shape with a hollow in the longitudinal direction inside thereof, and as illustrated in FIG. 3, a cylinder (a) or a square cylinder (b) can be exemplified. With such a shape, there is no sharp portion as compared with the earth auger drill, and the contact portion with a buried object is flat, so that the buried object is hardly damaged even if the casing tube 12 comes into contact with the buried object. Further, unlike the earth auger drill, a stone is not clogged between the blades.

Step 2

The vibrator 11 vibrates the casing tube 12 in a vertical direction to cause the casing tube 12 to penetrate into the ground. The amplitude of vibration obtained by the vibrator 11 is expressed by the following formula.

Amplitude (m)=eccentric moment (kgm)/total weight (kg)   (1)

Here, the total weight (kg) is defined as follows.

Total weight (kg)=vibrator weight (kg)+casing tube weight (kg)   (2)

In a case where a Uras Vibrator having an eccentric moment of 1.2 kgm/weight of 100 kg is used as a vibrator, according to the formulas (1) and (2), generation of vibration in a casing tube having a weight of 160 kg can generate an amplitude of 6 mm or more. It is empirically shown that with an amplitude of 6 mm or more, the casing tube can be penetrated into soil of many types. By adjusting the amplitude of the casing tube by the vibrator, it is possible to cope with various types of soil.

The vibrator 11 desirably includes a sensor that detects contact with a buried object. When the sensor detects that the vibrator 11 comes in contact with the buried object, the vibration of the vibrator 11 is stopped. This can prevent the casing tube from damaging the buried object.

As a sensor that detects contact with the buried object, a pressure gauge that detects a pressure in a vertical direction can be exemplified. When the casing tube 12 comes into contact with the buried object, the pressure on the vibrator 11 increases through the casing tube 12. When the pressure gauge of the vibrator 11 detects a pressure in the vertical direction larger than a predetermined value, the vibration of the vibrator 11 is stopped. By stopping the vibration of the vibrator 11 upon contact with the buried object, the buried object is not damaged, so that the pole erection hole excavation work can be realized with safety similar to that of the manual excavation work.

As another sensor that detects contact with a buried object, a speedometer that detects the penetration speed of the vibrator 11 can be exemplified. When the casing tube 12 comes into contact with a buried object, the penetration speed of the casing tube 12 is reduced. When the speedometer of the vibrator 11 detects the penetration speed smaller than a predetermined value, the vibration of the vibrator 11 is stopped. For example, when the penetration distance in 10 seconds is 1 mm, that is, the penetration speed is smaller than 0.1 mm/second, it is determined that the casing tube 12 has come into contact with the buried object. By stopping the vibration of the vibrator 11 upon contact with the buried object, the buried object is not damaged, so that the pole erection hole excavation work can be realized with safety similar to that of the manual excavation work.

Step 3

When the casing tube 12 penetrates to a predetermined depth, the vibration of the vibrator 11 is stopped. In a case of deep excavation, an extension bar is connected between the vibrator 11 and the casing tube 12.

Therefore, according to the present disclosure, it is possible to realize excavation of a pole erection hole by a machine to improve the efficiency of excavation work.

Step 4A

After the vibration of the vibrator 11 is stopped, the soil inside the casing tube 12 is lifted together with the casing tube 12 to discard the soil from a pole erection hole. A soil discarding step will be described with reference to FIG. 4. In FIG. 4, a reference sign 12 denotes a casing tube, and a reference sign 21 denotes soil. When the casing tube 12 is lifted, the soil 21 inside the casing tube 12 is also lifted together. When the soil 21 is discharged from the pole erection hole, the pole erection hole is completed.

Therefore, lift of the soil 21 together with the casing tube 12 can improve the efficiency of excavation work.

Step 4B

After the vibration of the vibrator 11 is stopped, the soil inside the casing tube 12 is stirred and sucked to be discharged from the pole erection hole. A discharging step will be described with reference to FIGS. 5, 6, and 7. In FIGS. 5, 6, and 7, a reference sign 12 denotes a casing tube, a reference sign 14 denotes a stirring device, a reference sign 14-1 denotes a rotation shaft of the stirring device, a reference sign 14-2 denotes nets of the stirring device, and a reference sign 15 denotes a suction pump.

The soil inside the casing tube 12 is stirred by the stirring device 14 to be loosened, and then sucked and discharged by the suction pump 15. The stirring device may be disposed inside the casing tube 12 before excavation, or may be inserted into the casing tube 12 after vibration of the vibrator 11 is stopped.

An example of the stirring device may be a drill mechanism as illustrated in FIG. 6. In a case where a drill function is disposed inside the casing tube 12 before excavation, it is preferable to dispose the drill mechanism at a position upper than the lowermost portion of the casing tube 12 so that the drill mechanism does not come into contact with a buried object.

As another example of the stirring device, nets having a tier structure as illustrated in FIG. 7 may be used. In the step structure, the lower nets are coarser and the upper nets are finer. While the rotation shaft 14-1 of the stirring device is rotated, soil is pushed out toward the lower portion of the casing tube 12. The soil is roughly and strongly loosened with a coarse mesh at the lower part of the nets 14-2 of the stirring device, and finely loosened with a fine mesh at the upper part of the nets 14-2 of the stirring device. By varying the sizes of the meshes of the nets from coarse to fine in the height direction, the soil is easily loosened.

Therefore, the soil inside the casing tube 12 is stirred, sucked, and discarded, whereby the efficiency of excavation work can be improved.

Step 4C

After the vibration of the vibrator 11 is stopped, a utility pole is connected to the upper surface of the casing tube 12. In this case, the shape of the casing tube 12 is desirably a cylindrical shape corresponding to a utility pole 22. A utility pole connecting step will be described with reference to FIGS. 8, 9, and 10. In FIGS. 8, 9, and 10, a reference sign 12 denotes a casing tube, a reference sign 16 denotes a casing tube bolt hole, a reference sign 17 denotes a casing tube bolt, a reference sign 18 denotes a casing tube bolt attachment, a reference sign 19 denotes an attachment bolt, a reference sign 20 denotes an attachment nut, a reference sign 21 denotes soil, a reference sign 22 denotes a utility pole, a reference sign 23 denotes a utility pole bolt hole, a reference sign 24 denotes a utility pole bolt, and a reference sign 25 denotes a utility pole attachment.

As illustrated in FIG. 8, the casing tube 12 is removed from the vibrator, and the utility pole 22 is disposed on the upper surface of the casing tube 12. In FIG. 8, the attaching mechanism is omitted. As illustrated in FIG. 9, the casing tube bolt holes 16 are formed in advance in the casing tube 12, and the utility pole bolt holes are formed in advance in the utility pole 22. As illustrated in FIG. 10, the casing tube bolt attachment 18 is fixed to the casing tube 12 with the casing tube bolts 17. The utility pole attachment 25 is fixed to the utility pole 22 with the utility pole bolts 24. Positions of the casing tube bolt attachment 18 and the utility pole attachment 25 are matched and the casing tube bolt attachment 18 and the utility pole attachment 25 are fixed with the attachment bolts 19 and the attachment nuts 20. The attaching mechanism is not limited to that described here. It is only needed that the casing tube 12 and the utility pole 22 are fixed.

Therefore, the casing tube 12 is used as a base of a utility pole when the utility pole is erected, so that labor when erecting the utility pole can be saved and the efficiency of excavation work can be improved. In addition, labor of waste soil treatment such as backfill of soil into the gap between the pole erection hole and the utility pole can be saved, so that the efficiency of excavation work can be improved.

As described above, according to the method for excavating a pole erection hole of the present disclosure, it is possible to realize excavation of a pole erection hole by a machine to improve the efficiency of excavation work.

Industrial Applicability

The present disclosure can be applied to various industries including the information communication industry.

REFERENCE SIGNS LIST

• • 11 Vibrator
  • 12 Casing tube
  • 13 Carrying vehicle
  • 14 Stirring device
  • 14-1 Rotation shaft of stirring device
  • 14-2 Nets of stirring device
  • 15 Suction pump
  • 16 Casing tube bolt hole
  • 17 Casing tube bolt
  • 18 Casing tube bolt attachment
  • 19 Attachment bolt
  • 20 Attachment nut
  • 21 Soil
  • 22 Utility pole
  • 23 Utility pole bolt hole
  • 24 Utility pole bolt
  • 25 Utility pole attachment
  • 51 Earth auger drill
  • 52 Digger derrick truck