JP3150080B2 - Drilling casing head - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a casing head for excavation used for excavating a pile hole or the like with a casing in civil engineering work or building construction work.

[0002]

2. Description of the Related Art Conventionally, in general, when a pile hole or the like is excavated by a casing in civil engineering work or building construction work, as shown in FIG. Is attached to the lower end of the casing 3, the casing 3 is supported by the press-fitting device 4, set vertically, and the inside of the casing 3 is excavated and discharged by a hammer grab 5 or a screw. The casing 3 is pressed into the ground by excavating with the bit 2 at the lower end of the casing head 1 by applying a rotating force and a pressing force to the casing 3.

At this time, the bit 2 projects slightly (about 1 cm) outside the outer periphery of the casing head 1 so that a pile hole slightly larger than the diameter of the casing 3 can be excavated. However, while the excavation is configured to reduce the frictional resistance due to the earth pressure acting on the outer periphery of the casing 3, the earth pressure acting on the outer periphery of the casing 3 gradually increases as the excavation proceeds. Tightening increased frictional resistance and eventually made excavation impossible.

[0004]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a casing head for excavation which can reduce the frictional resistance acting on the casing and perform excavation reliably and smoothly.

[0005]

In order to solve the above-mentioned problems, in the present invention, a clearance between a casing and a hole wall is secured on the outer periphery of a body provided with a drill bit at the tip.
Multiple protrusions to reduce frictional resistance due to earth pressure
These projections are oriented in the circumferential direction of the body.
Tilt so that the rear side in the direction of excavation rotation gradually becomes higher
It has an outer surface and its height is the same as that of the bit
It is formed slightly higher and has a step on the outer peripheral surface of the body.
Be sure to attach them so that they are spirally connected with a difference.
And a casing head for excavation is provided.

According to the casing head having the above-described structure, the outer peripheral projections press the hole wall during the excavation rotation, and the soil on the wall is compacted and stabilized, so that the earth pressure acting on the casing becomes very small. Friction resistance is also reduced, and excavation can be performed reliably and smoothly.

According to a specific configuration of the present invention, the protrusion is formed so as to have a substantially crescent-shaped cross section.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In FIG. 1, reference numeral 10 denotes a cylindrical casing for excavating a casing; This is a press-fitting device called a full-rotating machine for applying force. The press-fitting device 12 uses the hydraulic pressure to
0 is held from the surroundings, and a rotating force and a pressing force are applied to the casing 10 in that state, and a known one can be used.

As can be seen from FIGS. 2 and 3, the casing head 11 has a cylindrical body 10a having the same diameter as the casing 10, and a drill bit 13 is provided at the tip of the body 10a. A plurality of projections 14 are provided on the outer periphery of the body 10a to secure a gap between the casing 10 and the hole wall 16a of the pile hole 16 to reduce frictional resistance due to earth pressure.

The projection 14 presses the hole wall 16a of the pile hole 16 excavated by the bit 13 to compress the earth and sand on the wall surface and stabilize the state of the wall surface. A gap for reducing frictional resistance is secured between the wall 10a and the wall 16a. The shape is not particularly limited as long as it has such a function. Outer surface 1 that slopes smoothly so that the rear side in the rotational direction becomes gradually higher
4a. Projection 1 of the illustrated embodiment
Reference numeral 4 denotes a crescent having an arc-shaped outer surface 14a or a cross-sectional shape similar thereto, and a plurality of projections 14 are spirally attached to the outer periphery of the body 10a. Therefore, the outer surface 14 of each of the protrusions 14
The radius of curvature of a is smaller than the radius of curvature of the cylindrical surface of the body 10a.

The height of the projection 14 (the body 10a)
Is preferably equal to or slightly larger than the length h of the bit 13 projecting outward from the outer peripheral surface of the body 10a. Particularly, when excavating soft ground, It is better to make it a little higher.

The casing excavation using the casing head 11 having the above-described structure is performed in the same manner as the conventional one shown in FIG. At this time, as the casing head 11 excavates and rotates, the projections 14 on its outer periphery press the hole wall 16a outward to compact the soil on the wall surface and stabilize the state of the wall surface. 16a and a sufficient gap will be ensured.
The earth pressure acting on the casing 10 becomes very small, the frictional resistance is reduced, and the excavation can be performed reliably and smoothly. If the height of the projection 14 is higher than the bit 13,
Since the diameter of the hole wall 16a is slightly increased by the projection 14, excavation can be performed more smoothly. The above casing 10
Are connected in sequence according to the excavation depth.

The length of the casing head 11 is naturally determined to be optimal according to the number of protrusions and the arrangement thereof.

[0014]

As described above, according to the present invention, by providing a simple means of providing a projection on the outer periphery of the casing head, the frictional resistance due to earth pressure acting on the casing during excavation is reduced, and the excavation is performed. It can be performed reliably and smoothly.

[Brief description of the drawings]

FIG. 1 is a sectional view of a main part in a use state showing an embodiment of the present invention.

FIG. 2 is an enlarged view of a main part of FIG.

FIG. 3 is a sectional view taken along line AA of FIG. 2;

FIG. 4 is a sectional view showing a conventional excavation method.

[Description of References] 10 Casing 10a Body 11 Casing head 13 Bit 14 Projection 14a Outer surface 16a Hole wall

Claims (2)

(57) [Claims] 1. A cylindrical body having an excavating bit at a tip thereof, and a clearance between a casing and a hole wall provided on an outer periphery of the body to reduce frictional resistance due to earth pressure. It has a plurality of projections, and these projections
The rear side in the excavation rotation direction is gradually higher toward the circumference of
It has an outer surface that slopes so that it becomes
Is the same as or slightly higher than the bit
The outer surface of the body has a step so that it is spirally connected
An excavating casing head, being mounted . 2. A casing according to claim 1, upper
The projection has a substantially crescent-shaped cross section.
What to sign.