JPH06313392A - Ground excavating construction method and auger head used for ground excavating construction method - Google Patents

Abstract

PURPOSE:To reduce the weight and the torque for a vertical load given to an auger head to excavate a pile hole in a solid ground. CONSTITUTION:A periodical up and down movement of a small size is operated by an earth auger 11 by feeding a plenty of compressed air from the tip of an auger head 23 while continuing the rotation of the earth auger 11. The auger head 23 has a feeding port which can feed the compressed air from the tip, and plural edges are provided in the condition arranging in almost the radius direction placing intervals, at the lower end edges of two lines of spiral parts formed to follow the spiral part of the lower end of the screw 22 of the earth auger 11. Furthermore, the edge near the center is provided separately projecting to the tip side more than the edges of the other parts.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an excavation method for mainly excavating a pile hole for installing steel pipe piles, concrete piles, H steel piles, etc. on relatively hard ground including rocks and boulders. The present invention relates to an auger head used for excavation by a construction method.

[0002]

2. Description of the Related Art Conventionally, when excavating a pile hole having a diameter of about 300 to 1000 mm on a relatively hard ground including rocks and boulders, a crawler crane is used with an earth auger. Is normal. The outline thereof will be explained. As shown in FIG.
The vehicle body portion 3 and the tow rope 4 are vertically fixed and supported by a three-point type support, and an excavation device 5 using an earth auger is provided so as to dig along the leader 2. In the figure,
Reference numeral 6 is a rotary drive unit, 7 is a screw, and 8 is an auger head. In this case, since the rotary drive unit 6 requires a large torque, a motor of 80 to 240 horsepower is used,
Although its own weight is large, a weight is added to give a vertical load for excavation, and a vertical load of about 10 to 15 tons can be given. When excavating a pile hole, a large torque and a vertical load can be applied to the auger head 8, so that it is possible to drill a relatively hard ground including rocks and boulders. In addition, generally, in order to reduce the tackiness of soil, digging is performed while supplying water from the tip of the auger head. The auger head 8 is configured such that bite-shaped blade portions are provided symmetrically on the tip edges of the two spiral portions, and the blade portions in the peripheral portion project toward the tip side rather than the central portion.

In the case of excavating the above-mentioned pile hole in the ground where it is easy to excavate, a truck crane may be used with an earth auger. However, since this type of crane has a small load-bearing capacity, it cannot use a large-capacity rotary drive unit and has a small vertical load, so it cannot be excavated if there is rock or boulders.

[0004]

The excavation of a pile hole by a device having a conventional crawler crane equipped with an earth auger is limited because the installation position of the leader 2 is limited to a specific position close to the crawler crane. There is also a problem in that the position is limited to the vicinity of the foot of the place where the crawler crane can be entered. For example, if the excavation position of the pile hole is higher than the ground on which the crawler crane is stepped and has a step, it cannot be excavated. Therefore, it is necessary to level the ground to eliminate the step in advance, and extra work is required. In addition, the crawler crane is often difficult to enter into a narrow space, and when a weight is added to apply a vertical load, the crawler crane may easily fall down, resulting in a problem in workability. The cause of the above problems is that the solid ground as described above cannot be excavated unless the bit is rotated with a large torque while applying a large vertical load due to the weight or the like. There is no choice but to use a crawler crane that has a large supporting capacity. The present invention provides a pile hole excavation method capable of reducing the weight and torque for a vertical load applied to an auger head when excavating a pile hole in solid ground, and an appropriate auger head used in the construction method. The purpose is to reduce the weight of the excavation equipment required for excavation so that it can be mounted on a rough terrain crane that excels in the ability to penetrate narrow spaces.

[0005]

SUMMARY OF THE INVENTION According to the means of the present invention, a large amount of compressed air is supplied from the tip of the auger head while continuing the rotation of the earth auger, so that the earth auger can be vertically moved in a small size. It is characterized by being performed. The auger head used in the above-mentioned means has a supply port capable of supplying compressed air from the tip portion and is formed at the lower end edge of each of the two spiral portions formed so as to follow the spiral portion at the lower end of the screw of the earth auger. A structure is used in which a plurality of blades are arranged in a substantially radial direction at intervals, and the blade near the center is further projected toward the tip side than the blades of other parts. Is good.

[0006]

According to the means of the present invention, when the compressed air is supplied after the pile hole is dug to some extent, the compressed air first fills the lower part of the pile hole and the earth auger is slightly lifted.
Next, the filled compressed air suddenly leaks from the excavated part and the earth auger falls. The upward movement and the downward movement of the earth auger occur periodically when the compressed air is continuously supplied. The cycle varies depending on the amount of compressed air supplied and the like, and is preferably about 3 to 5 seconds. The excavation is interrupted during this upward movement, but the blade edge of the auger head bites slightly into the ground during downward movement, and the earth auger continues to rotate, so the excavation continues. When it hits a rock or boulder, when it descends, the cutting edge simply bites a bit into the rock or boulder, or causes a crack, or crushes it, and when it is rotated, it causes a crack,
Alternatively, the crack is expanded or crushed, and the digging is performed so as to expand the range of the crack or the crush. In other words, because the cutting edge of the cutting edge works effectively when moving downward, it is comparable to the conventional case of increasing the vertical load and rotating with a large torque without adding a weight to increase the vertical load. A drilling action is obtained.

When the auger head is used, the blade portion in the vicinity of the central portion is provided so as to project toward the tip side more than the blades in other portions, so that the auger head enters the ground from the central portion of the tip of the auger head. Therefore, the blade portion near the central portion receives the excavation resistance predominantly, and the blade portion in the peripheral portion excavates the prepared hole enlarged by the blade portion near the central portion. For this reason, the direction in which the digging proceeds is less likely to change than when the cutting edge in the peripheral portion is subject to digging resistance. This is because the blade portion near the central portion of the auger head has a small turning radius, so that when the excavation resistance differs between the left and right blade portions, it is less affected than the peripheral blade portions. In addition, when the excavation resistance is focused on the position where the turning radius is small, the rotational force that overcomes it is smaller than when the excavation resistance is focused on the position where the turning radius is large. It can also be used with a relatively small output.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to FIGS. FIG. 1 shows an example of an apparatus used for this pile hole excavation method, including an earth auger 11, a rough terrain crane 12,
The generator 13 and the air compressor 14 are included. The earth auger 11 includes a rotation drive unit 21, a screw 22, an auger head 23, and the like. The rotation driving unit 21 is 30 to 5
It is an electric motor of about 0 horsepower and is supplied with electric power from the generator 13 to rotate. The screw 22 is connected to the output shaft of the rotary drive unit 21, and a compressed air supply path is provided through a swivel joint so that compressed air from the air compressor 14 is supplied into the pipe 24 forming the shaft of the screw 22. It is connected. The earth auger 11 is rotatably supported at the upper position of the rotary drive unit 21 on the tip of the boom 15 by a shaft perpendicular to the undulating surface of the boom.

An example of the auger head 23 is shown in FIGS.
As shown in the enlarged view of FIG. 1, a hexagonal tubular joint portion 25 is formed so as to be coupled to the lower end of the screw 22. Two spiral portions 27, 27 are provided so that one is continuous with the spiral portion, and blade portions 29, 29 are respectively provided on the lower ends 28, 28 in the radial direction of the lower ends of the spiral portions.
30 is attached by welding. Also, the cylindrical body 2
As shown in FIG. 3B, the lower end (tip) opening of 6 is
A plate-like check valve 32 made of rubber is provided, and the check valve 32 is provided.
An arcuate valve protection member 33 is attached to the lower end of the cylindrical body 26 by welding with the lower side separated by a gap necessary for opening the check valve. And the blade parts 31, 31
Are attached by welding. The blade portion 31 is provided at the position closest to the center of the auger head 23, and the blade tip projects most toward the tip side. The blade portions 30 and 29 are sequentially provided closer to the outer periphery of the auger head 23, and the blade tip position is also sequentially rearward of the blade portion 31. The auger head 23 of this embodiment has an outer diameter of 400 mm and blade portions 31 and 30.
The difference in the amount of protrusion to the tip side of the blade is about 70 mm, and the blades 29 and 30
The difference is about 20 mm, and the blade portion is a welding type flat blade with a commercially available bit whose chamfer is about 3 mm.

The air compressor 14 has a pressure of 7 to 10 Kgf / cm.
^{2. The} amount of discharged air is about 15 to ³⁰ m ³ / min.

When excavating a pile hole using this device,
As shown in FIG. 1, the earth auger 11 is hung above the desired excavation position, gradually lowered vertically while rotating, and the boom 15 is shortened as the excavation proceeds to maintain the vertical state. . After excavating about 5 m, supply of compressed air is started. This causes the earth auger 11 to start moving up and down. Even if it hits a boulder or rock, if the excavation is continued as it is, the excavation time per predetermined length becomes long, but the excavation can proceed. The first about 5m
Even if the compressed air is supplied up to the depth of 1, the desired vertical movement does not occur because much air leaks. Therefore, when the existence of boulders and rocks can be predicted, the first excavation up to a depth of about 5 m can be performed by using an auger head to which a bit having a relatively sharp cutting edge is attached in advance. However, since this auger head has severe blade wear and chipping, it is limited to excavation up to the initial depth of about 5 m.

According to the experiment using the above-mentioned apparatus, if the digging is first carried out to a depth of 5 m on the ground with boulders or rocks, and further digging without further supplying compressed air, the rocks or boulders will not be struck. Become. In that state, the blade slides on the surface of the rock and is idling. Then, when the supply of compressed air of 20 m ³ / min at 10 Kgf / cm ² was started, the earth auger 11 started to move up and down at intervals of 1 to 2 seconds with a stroke of 5 to 50 mm, and could dig. The maximum vertical load was measured while supporting the lower end of the screw of the above device, and it was about 5 tons. Further, according to the experiment, this excavation method can be applied to a depth of about 5 m to about 30 m. If it is deeper than this, the desired vertical movement of the earth auger cannot be obtained. Further, instead of the auger head of the above-mentioned device only auger head that is normally used in the past, that is, instead of the auger head in which the blade tip near the center is slightly behind the blade tip near the periphery, the same. It was possible to excavate in almost the same way. However, the straightness of the pile hole tends to be lowered when the rock is hit against the rock or the boulder to proceed with the digging, and it was confirmed that the auger head of the above-described example is superior in the straightness of the pile hole.

[0013]

According to the excavation method of the present invention, it is not necessary to add a weight for increasing the vertical load as compared with the conventionally used earth auger, and it is rotationally driven in a state in which a large vertical load does not act. Since it does not require a motor with a very large output, does not need to use a leader, and only needs to supply compressed air, a rough terrain crane, which has a better ability to enter narrow spaces than a crawler crane, can be used for pile driving. It became possible to excavate a pile hole. Therefore, the equipment for excavating the pile holes of the same degree is downsized, and the cost for excavating the pile holes is reduced. Also,
Since a rough terrain crane is used, it is easy to enter into narrow spaces, and since the earth auger hangs directly from the boom without using a leader, it is not only the foot of the crane vehicle as in the past, but also the ground at a remote position, It is possible to excavate a pile hole on a ground having a step and separated, for example, a ground higher or lower than the ground where the crane vehicle is located.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing a schematic configuration of an example of an apparatus used for carrying out a construction method of the present invention.

FIG. 2 is a front view showing an example of an auger head of an earth auger used for carrying out the construction method of the present invention.

3 (a) is a bottom view of the auger head of FIG. 2,
(B) is an AA cross-section partial view of (a).

FIG. 4 is a configuration diagram showing a schematic configuration of an apparatus used for carrying out a conventional construction method.

[Explanation of symbols]

 11 Earth Auger 12 Rough Terrain Crane 15 Boom 21 Rotation Drive 22 Screw 23 Auger Head 26 Auger Main Body 27 Spiral Part 28 End Edge 29 Blade 30 Blade 31 Blade 32 Check Valve

Claims (2)

[Claims] 1. A ground excavation method characterized in that a large amount of compressed air is supplied from the tip of the auger head while the earth auger continues to rotate, thereby causing the earth auger to periodically move up and down in small dimensions. . 2. The auger head used in the construction method according to claim 1, which has a supply port capable of supplying compressed air from a tip portion and is formed so as to follow a spiral portion at a lower end of a screw of an earth auger. A plurality of blade portions are provided at the lower end edge of each spiral portion of the spiral portion so as to be arranged at intervals in the substantially radial direction, and the blade portion in the vicinity of the central portion protrudes further toward the tip side than the blades of other portions. An auger head characterized by being provided as.