JP3472855B2 - Drilling ring for casing tube - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a drill ring attached to the tip of a casing tube used in an all casing method.

[0002]

2. Description of the Related Art As a typical construction method for cast-in-place concrete piles, an all-casing construction method using a casing tube and a drill ring is known. With the all-casing method, the drilling blades 23, 23 ... for drilling the ground are provided at the tip of the casing tube 22 of a unit length that can be added to each other over the entire circumference of the lower end, as shown in FIGS. A plurality of drilling rings 21 are attached,
The excavation ring 21 and the casing tube 22 are pushed into the ground while being rocked in the circumferential direction by a rocking type excavator, and the earth and sand accumulated in the tube are carried to the ground by a hammer mug to drill a vertical hole. As the excavation proceeds, another casing tube 2 is attached to the upper end of the casing tube 22.
Continue to excavate while continuing to add 2, 22, ... to prevent collapse of the hole wall. When the excavation ring 21 reaches the hard support ground, insert a reinforcing steel cage into the casing tube and pull up the casing tubes 22, 22 ... And the excavation ring 21 while collecting fresh concrete using the tremie pipe and collect it. It is a construction method to build concrete piles.

In order to reduce the frictional resistance generated between the casing tubes 22, 22 ... And the hole wall at the time of excavating the vertical holes and pulling up the casing tubes 22, 22 .. Excavating blade 23,23 ...
. Was projected outward from the outer surface of the excavation ring 21 by about 5 mm to 10 mm, and the ground outside the outer surface of the excavation ring was also excavated. By doing so, a slight gap is provided between the vertical hole that has been excavated and the casing tubes 22, 22 ...
The above-mentioned frictional resistance is reduced.

[0004]

However, the above-mentioned excavating blade 2
Since 3,23 ... Are attached at a predetermined interval, a corrugated locus is formed by the excavating blades 23, 23, ... on the hole wall of the vertical hole, and fresh concrete is poured into this vertical hole to build it. On the outer surface of the concrete pile 31, as shown in FIG. 6 (b), unevenness due to the wavy locus is formed.
There were variations in pile bearing capacity, bending capacity, shear capacity, etc. Therefore, in view of the above problems, the present invention provides a casing tube excavation ring capable of constructing a concrete pile having no unevenness on the side surface and no variation in strength, and easily pulling the casing tube from the vertical hole to the ground. Is an issue.

[0005]

The excavation ring of the invention as set forth in claim 1 for solving the above-mentioned problems is attached to the tip of a casing tube used in the all-casing method, and the excavation blade for excavating the ground is entirely at the lower end. A plurality of excavation rings attached along the circumference, wherein the excavation ring outer surface between the plurality of excavation blades has a protrusion, and the protrusion has a width substantially equal to a distance between adjacent excavation blades. It is what Further, in the excavation ring according to a second aspect, in addition to the structure according to the first aspect, the protrusion has a thickness corresponding to a protrusion width of the excavation blade to the outside of the excavation ring. Further, the excavation ring according to claim 3 is the structure according to claim 1 or 2, wherein the protrusion is formed by fixing a steel piece to an outer surface of the excavation ring.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of a drilling ring of the present invention will be described below with reference to the drawings. FIG. 1A is a perspective explanatory view of the excavation ring 1 according to the present invention seen obliquely from below, and FIG. 1B is a plan view of the excavation ring 1 seen from above. In addition, FIG. 2A shows the excavating blade 3 attached to the excavating ring 1.
3 ... and an enlarged view showing the thick-walled steel pieces 4, 4 ..., FIGS. 2B and 2C are respectively AA in FIG. 2A.
It is a line sectional view and a BB line sectional view.

The excavation ring 1 is attached to the tips of casing tubes 2, 2, ... With unit lengths that can be added to each other, and a plurality of excavation blades 3, 3 ,. Those drilling blades 3,
On the outer surface of the excavation ring between 3 ...
4 ... are fixedly formed by arc welding.
The excavating blades 3, 3 ... Are formed so as to project outward from the outer surface of the excavating ring by about 10 mm, and can be excavated slightly outside the outer surface of the excavating ring. In addition, thick-walled steel pieces 4, 4
-Has a rectangular parallelepiped shape and has a width and a vertical width which are substantially equal to the distance between the adjacent cutting blades 3 and 3, for example, a width and a vertical width of 50 mm, and the cutting blades 3, 3 ... It has a thickness corresponding to the protruding width, for example, 10 mm.

Next, a method of constructing a cast-in-place concrete pile using the excavation ring 1 will be described with reference to FIG. First, as shown in FIG. 3A, the excavation ring 1 is attached to the tip of the casing tube 2 and set on the swing excavator 6, and the excavation ring 1 and the casing tube 2 are swung in the circumferential direction. While pushing into the ground, the earth and sand collected in the tube are carried to the ground by the hammer mug 7, and the vertical hole is excavated. (Figure b). As the excavation progresses, the other casing tubes 2, 2, ... Are sequentially added to the upper end of the casing tube 2 to continue the excavation while preventing the collapse of the hole wall 5 of the vertical hole. When the excavation ring 1 reaches the hard support ground 8 (FIG. 7c), the reinforcing bar cage 9 is inserted into the tube (FIG. 4d), and the excavation ring 1 and the casing are injected while pouring fresh concrete using the tremie pipe 10. Tubes 2, 2 ... Are pulled up to the ground and collected (Figs. E and f),
A reinforced concrete pile 11 is built (g in the figure).

The operation of the excavation ring 1 in the building process will be described. Since the excavating blades 3, 3 ... Attached to the tip of the excavation ring 1 project outward from the excavation ring, a wavy locus is formed on the hole wall 5 during the excavation process, but immediately after that, between the wavy loci. Since the thickened steel pieces 4, 4 ... Are scraped off the remaining soil, as a result, almost no wavy trace remains on the hole wall 5. Further, when the excavation ring 1 and the casing tubes 2, 2 ...
.. and the gap between the excavating blades 3, 3 ... Relieves the soil, so that the excavating ring 1 is not caught by the hole wall 5 and becomes difficult to pull up. It should be noted that the drilling ring 1 has thick steel pieces 4, 4
It has been experimentally confirmed that the resistance when excavating (digging resistance) does not change even if the solid state is fixed.

If concrete is poured into a vertical hole excavated by using the excavation ring 1 described above to construct a concrete pile,
Since no wavy traces remain in the vertical holes, unevenness is hardly formed on the side surface of the pile as shown in Fig. 4 (b), and its cross section becomes a substantially perfect circle as shown in Fig. 4 (a), which provides stable support. A concrete pile that exhibits strength, bending resistance, and shear strength can be obtained. In addition, since the thick-walled steel pieces 4, 4, ... Of the drilling ring 1 are formed of a metal material having high hardness, the thick-walled steel pieces 4, 4 ,.
・ Maintenance work due to deformation and wear of can be reduced.

The excavation ring of the present invention is not limited to the above-described embodiment, and the shape, the mounting interval, the number of installations of the excavating blade, the material, the shape, the size, the number of installations, the arrangement of the protrusions, etc. Modifications can be made as appropriate without departing from the spirit of the invention. For example, the number of digging blades and protrusions to be installed can be appropriately changed depending on the pile diameter and other factors, and the mounting interval of the digging blades and the width dimension of the protrusions can be arbitrarily changed.
The thickness of the protruding portion can be arbitrarily changed according to the protruding width of the digging blade to the outside of the digging ring, but is preferably about 5 mm to 10 mm in consideration of digging resistance during digging. Further, the shape of the protruding portion is not limited to a rectangular parallelepiped shape, and may be a disk shape or a triangular shape. Also,
In the above-described embodiment, the protruding portion is described as a configuration in which a thick steel piece is fixed to the outer surface of the excavation ring, but in addition to this,
The protrusion may be provided by processing the excavation ring body.

[0012]

By constructing a concrete pile using the excavation ring according to the first and second aspects, the unevenness formed on the side surface of the pile can be reduced, and in particular, the protruding portion provided on the outer side surface of the excavation ring. If the thickness of the pile is the same as the protruding width of the excavating blade to the outside of the excavation ring, almost no unevenness is formed on the side surface of the pile, and a concrete pile exhibiting stable bearing capacity, bending strength, and shear strength can be obtained. Moreover, during the building process, it is not difficult to pull the casing tube to the ground from the excavated vertical hole. Further, according to the excavation ring of claim 3, the protrusion can be formed of a metal material having high hardness. As a result, in addition to the effect of claim 1 or 2, maintenance due to deformation or wear of the protrusion is performed. The labor of can be reduced.

[Brief description of drawings]

FIG. 1 is an explanatory view showing an example of an excavation ring according to the present invention, in which (a) is a perspective view seen obliquely from below and (b) is a plan view seen from above.

2 (a) is an enlarged explanatory view of the excavation ring shown in FIG. 1,
(B) is the sectional view on the AA line in (a), (c) is the sectional view on the BB line in (a).

FIG. 3 is an explanatory diagram showing a method for constructing a cast-in-place concrete pile.

FIG. 4 shows a concrete pile built using the excavation ring shown in FIG. 1, (a) is a side view thereof, and (b) is an image diagram showing a cross section of its head.

5A and 5B are explanatory views showing a conventional excavation ring, in which FIG. 5A is a perspective view seen obliquely from below and FIG. 5B is a plan view seen from above.

FIG. 6 shows a concrete pile built using the conventional excavation ring shown in FIG. 5, (a) is a side view thereof, and (b) is an image diagram showing a cross section of its head.

[Explanation of symbols]

1 ・ ・ Drilling ring 2 ・ ・ Casing tube 3 ・ ・ Drilling blade 4 ・ ・ Thick-walled steel slab 5 ・ ・ Hole wall 6 ・ ・ Swinging excavator 7 ・ ・ Hammer grab, 8 ・ ・Support ground, 9 ... Reinforcing cage, 10 ... Toremy pipe, 11 ... Concrete pile.

─────────────────────────────────────────────────── --Continued from the front page (56) Reference JP-A-6-272467 (JP, A) JP-A-55-26365 (JP, A) JP-A-7-62966 (JP, A) Actual development Sho-55- 71789 (JP, U) Actual Kaihei 4-112982 (JP, U) (58) Fields investigated (Int.Cl. ⁷ , DB name) E21B 7/20 E21B 10/02

Claims (3)

(57) [Claims] 1. An excavation ring, which is attached to a tip of a casing tube used for an all-casing method and has a plurality of excavation blades for excavating the ground all around the lower end, the outer surface of the excavation ring between the plurality of excavation blades. An excavation ring, characterized in that it has a protruding portion, and the protruding portion has a width substantially equal to a distance between adjacent excavating blades. 2. The excavation ring according to claim 1, wherein the protrusion has a thickness corresponding to a protrusion width of the excavation blade toward the outside of the excavation ring. 3. The excavation ring according to claim 1, wherein the protrusion is formed by fixing a steel piece to the outer surface of the excavation ring.