JPS5961690A - Earth auger - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention involves cutting in-situ soil underground, mixing cement milk with the in-situ soil, and further adding steel materials such as H-shaped steel as necessary to create so-called soil soil. We cut underground holes to construct mortar piles and continuous walls, poured concrete into the underground holes after removing in-situ soil, and then brought in steel materials as necessary to construct the piles. For more information on earth augers used for forming underground holes, also known as poling, for constructing continuous walls, or for driving precast concrete piles into the underground holes, please see below. , relates to an improved technology for an earth auger in which a cutting blade is provided at the lower end of the auger body.

During underground cutting or underground excavation using an earth auger,
As shown in FIG. 1, when the cutting blade 3 comes into contact with a hard object A such as a stone underground, although the auger itself has the ability to crush it, the cutting load applied to the cutting blade 3 is In order to act on the dog unevenly with respect to the earth auger l, or when the cutting blade body 3 alternately passes through the sandy part and the clay part, for example, in a stratum where sandy part and clay part are mixed. Also, since the cutting load applied to the cutting blade body 3 is biased against the earth auger 1, the tip of the earth auger 1 escapes to the soft material side, and the earth auger I Qb Due to the bending of the core,
In either a cut hole formed by leaving in-situ earth and sand or an underground hole formed by removing in-situ earth and sand, the axis of the hole will be bent, resulting in a decrease in pile strength when constructing an underground pile. In addition, in the case of constructing an underground wall using a series of underground piles, problems such as gaps are created between the piles and water-stopping properties are reduced.

The present invention was devised in view of this situation, and
The purpose is to prevent the axis of the auger body from bending with a simple modification, and a cylindrical body that prevents the axis of the auger body from bending due to the cutting load applied to the cutting blade body is installed in the auger body. The cutting blade is provided substantially concentrically with the axis and protrudes downwardly, and the lower end of the cylindrical body is formed into a conical outer surface with a smaller diameter at the lower end, and the conical outer surface is characterized in that it is provided with a spiral body made of a steel plate and equipped with a cutting blade body.

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 2 shows a cross-sectional plan view of the earth auger l, and FIG. 3 shows a side view of the lower end side of the earth auger l of the first embodiment.

The earth auger 1 has an upper end attached to a lower end of an auger main body 2, which is attached to a rotary drive device (not shown), and the earth auger 1 has a phase difference of 1.
A pair of cutting blade bodies 3°3 are arranged in series with a difference of 80 degrees, and a cylindrical body 4 protruding downward from the cutting blade bodies 3, 3 is made to have approximately the same diameter as the auger main body 2, so that the auger is The cylindrical body 4 is connected to the main body 2 in a substantially concentric manner, and the cylindrical body 4 has a hollow structure. ) is formed into a conical outer surface S having a small diameter at the lower end side, and on this conical outer surface S, a pair of spiral bodies made of steel plates having approximately the same diameter as the outer peripheral diameter of the cylindrical body 4 are formed. 5, 5 are provided with a phase difference of 180 degrees from each other so as to act in a direction to lift up the earth and sand in situ as the earth auger 1 rotates in the excavation direction, and cutting blades are further provided on the lower edge of the spiral bodies 5, 5. Body 6・
In addition, an opening connected to the hollow part B of the cylindrical body 4 is provided at the lower end of the cylindrical body 4, and a triangular cutting blade 7 is attached so as to be connected to the lower end of the cylindrical body 4. .

In the figure, a... is an opening formed near the base of the blade bodies 3, 3, and the opening a... and the hollow part B are filled with a hardening agent such as cement milk, or a hardening agent such as sodium silicate. agent,
A flow path 8 for supplying a fluid such as thin ice or bentonite is provided.

To explain one means of constructing an underground pile using the earth auger 1 having the above configuration, first, the cylindrical body 4 is located underground, a fluid is discharged from the openings a and b through the channel 8, and the earth auger 1 is rotated as it digs.

In such a state, since earth pressure is applied to the opening, the amount of fluid discharged through the opening is extremely small, and the fluid remains in the hollow part B. Although the cylindrical body 4 becomes high in temperature due to frictional heat due to its rotation, it can be cooled down by the fluid.

Now, when cutting by the cutting blades 3, 3 is started, the fluid discharged prior to the cutting blades 3, 3 and the cut in-situ soil are mixed, and the in-situ soil is fluidized. become At this time, by using a hardening agent as a fluid, and if necessary, when pulling out and removing the earth auger 1, a hardening accelerator such as sodium silicate is introduced from the channel 8 while rotating the auger 1. By discharging it, a so-called soil mortar pile can be constructed, and of course, by mixing bentonite with the hardening agent, mixing the hardening agent in the drawing process of the earth auger 1, or mixing it with a hardening accelerator, etc. By constructing fill mortar piles, a continuous underground wall can be constructed by connecting these piles.

Note that steel materials such as H-shaped steel, channels, and steel sheet piles may be buried as necessary.

Now, in the digging process of forming a cutting hole by the earth auger 1, when the cutting blade 3 comes into contact with a hard object A such as a stone underground, or when the blade 3 passes through a soft object, the blade 3 tends to be biased toward the soft material side, but the cutting blade body 3
Since a cylindrical body 4 is provided below the blade body 3, the outer peripheral surface of this cylindrical body 4 serves as a resistance surface S1 against the ground that resists force in a direction perpendicular to the axial direction. Moreover, the lower end of the cylindrical body 4 is formed into a conical outer surface S with a smaller diameter at the lower end, and the conical outer surface S is provided with a spiral body 5,5 having a cutting blade 6... and the spiral body 5,
5 forcibly lift the in-situ soil,
Since this is pressed outward in the circumferential direction by the action of the conical outer surface S, in other words, earth and sand corresponding to the volume of the cylindrical body 4 is compacted onto the circumferential portion of the cylindrical body 40. The ground strength against the resistance surface S1 of the cylindrical body 4 is high υ, which effectively suppresses bending of the auger shaft due to the cutting load applied to the blade 3. It is possible to construct piles with extremely small bends or no bends.

Furthermore, even in a situation where the cutting ground is a stratum in which a sour-grained part and a clay part coexist, the cutting blade body 3 alternately cuts the sour-grained part and the clay part as it rotates, the above-mentioned method can be used. It is possible to effectively suppress the bending of the auger shaft core, and in the case of cutting, the spiral bodies 5, 5 preceding the cutting blade body 3 carry around a part of the in-situ soil as it rotates. It has the effect of pushing the earth and sand toward the soft ground side and solidifying it, and can be expected to improve the ground by strengthening local soft ground. Even in this case, bending of the auger shaft can be suppressed.

Incidentally, as shown by the phantom lines in Fig. 3, spiral bodies 9, 9 are provided in series with the cutting blade body 3.3 to remove in-situ earth and sand, and concrete is poured into the underground hole thus formed. By bringing reinforcing bars and steel materials as necessary, concrete piles can be constructed, and by connecting the piles, a continuous underground wall can be constructed.

Another embodiment of the earth auger 1 is shown in FIG. This earth auger differs from the earth auger 1 shown in FIG. 3 in the following points.

That is, three cutting blade bodies 3 are provided with a phase of 120 degrees, and a cylindrical body 10 is attached to the circumference of the cutting blade bodies 3. A cutting blade body 11... is provided on the lower end side, and a blade body 3'... shorter than the cutting blade body 3 is provided below the cutting blade body 3 and between the cutting blade bodies 3, 3. The auger shaft center is bent by the outer circumferential surface of the cylindrical body 10 as well as forming a cutting hole with a diameter increasing sequentially by the short blade body 3 and the long blade body 3. It is characterized by the fact that it suppresses the

In addition, in both of the earth augers shown in FIGS. 3 and 4, the number of cutting blades 3, 3' and spiral bodies 5°9 to be provided does not matter, and if multiple pieces are provided, Needless to say, it is desirable to arrange them at equal intervals so that the cutting load does not deviate around the auger shaft.

[Brief explanation of the drawing]

Figure 1 is a partial side view of a conventional earth auger, Figure 2 and subsequent figures relate to the present invention, Figure 2 is a cross-sectional plan view, Figure 3 is a partial side view, and Figure 4 is a perspective view of the cylindrical tip. be. FIG. 5 is a side view of a modified example, and FIG. 6 is a cross-sectional view of the cross section of FIG. 5. 2... Earth auger body, 3, 6... Cutting blade body, 4
... Cylindrical body, 5... Spiral body, S... Conical outer surface.

Claims (1)

[Scope of Claims] ■ An earth auger in which a cutting blade body is provided on the lower end side of the auger body, in which a cylindrical body that prevents the auger axis from bending due to a cutting load applied to the cutting blade body; The cylindrical body is provided approximately concentrically with the axis of the auger body and protrudes downwardly from the cutting blade body, and the lower end of the cylindrical body is formed into a conical outer surface with a smaller diameter at the lower end, and An earth auger characterized in that a spiral body made of a steel plate is provided with a cutting blade body on the outer surface of the earth auger. (2) The earth auger according to claim 0, wherein the outer circumferential diameter of the helical body is approximately the same as the outer circumferential diameter of the cylindrical body.