JPS5858491B2 - underground pile - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to improvements in underground piles constructed by a screw rotation method.

The screw rotary pile has a screw 11 at the tip of a shaft 10 as shown in FIG. It is something that I will devote myself to.

Because it can be driven with a simple rotary tool without the need for a special large driving device such as a drop hammer, it is attracting particular attention for use in reinforcing the foundations of transmission line towers with poor footing.

The strength of this seed pile is related to the friction between the soil around the pile and the pile, as well as the shear force of the soil itself, so the deeper the pile is driven, the stronger it becomes.

However, although it is difficult to disagree, as the depth increases, the friction with the soil increases and the rotational torque increases.

This rotational torque increases as the outside diameter of the shaft of the pile increases, and between a pile with a thick outside diameter as shown in Figure 2 A and a pile with a thin outside diameter as shown in Figure 2, the one with thinner B has the same torque. This allows you to drive deeply.

1.71) Although the pile B can be driven deeply, since its outer diameter is small, the shaft is likely to buckle when subjected to stress in the direction of sinking, resulting in a decrease in strength in that direction.

The present invention aims to provide a material that can prevent such buckling, allow deeper driving, and ensure greater strength.

This will be explained below based on a specific example.

As shown in FIG. 3, the present invention is constructed of a peg B having a thin shaft 20 with a screw 21 at the tip and a concentric circle with the peg B, and as shown in FIG. The guide 32 and spacer 33 penetrated by
and a pile C having a shaft 30 with a larger diameter than that of the pile B having a screw 31 at the tip (or a pile D having an even larger diameter shaft if necessary), and the pile B and the pile C are connected concentrically as shown in Figure 5,
Each can be rotated independently.

To drive this stake, first drive a thin, uncut stake B as shown in Figure 2, and then drive it deeply with a small torque.

Next, as shown in FIG. 5, a peg C is fitted so that the shaft 20 of the peg B passes through the center of the interior, and this peg C' is rotated independently to reinforce the parts of the peg B that are prone to buckling.

Needless to say, the soil is softer at shallower depths, and buckling is more likely to occur there.

Therefore, there is no need to drive the pile C too deeply, and the shaft 3
Even if the zero diameter is large, there is no need for large torque.

If the pile C' alone is not strong enough, reinforcing it with a pile with a larger diameter, such as a pile E, will ensure sufficient strength to prevent buckling even in extremely soft soil such as sand. be.

Next, the excellent effects of the pile according to the present invention will be explained using calculations based on driving experiments.

The soil friction force is under the following conditions.

(Depth) (Soil friction force) 0~3m 500Kg/m" 3~6 〃 600 〃6~12/
/700//12~15tt
850// 15~18// 1000 n18~
21// 1200 〃21～24//
1400 //24~27tt
1700t/27~301/2
000 // (1') Gui AC conventional type) The dimensions are shown in Figure 6 and the torque coefficient is determined by 91.

R2: Radius of pipe, L: Length, Rs Radius of Niscrew wing, Ks Torque coefficient of part of Niscrew, KP: Torque coefficient of shaft part, (1) Part of pipe of 89 body φ 27rR2p xL=2π0.0445 x3000
=3.73X10-277? (2) 254. One side 2πCR of φ screw part
83-KP3)=3.91 XIO-3(3)
Izutsu 5.56XIO of the screw part of 279mmφ
? r? (4) 9.22X on one side of the 330mφ screw part
10 1 (5) Bottom surface of the 381wnφ screw portion 1.
44X10n? (6) The top surface of the screw part of 381y++y++φ is 120x10 m' or more.
．． 56x10-3+9.22XIO-')X2+1.4
4X10'2+1.20X10-"=1.OIXlo-
1i (7) 216mmφ pipe part (per 3m) K
P=2πX0.108 X3.0=2.2X10-'
The torque of type A is 24m and 1400x1.01xlO-"+(1200-1000
+850+700+600+500)X2.2XIO-
1208 Ky・m (b) Pile B dimensions are shown in Figure 7.

Torque coefficient for the 3m section at the tip of type B (1) 89rrrInφ pipe section 3.73
x 10-27? /(2) 254mmφ screw part Izutsu 3.91X10-i (3) 279mmφ screw part one side 5.56
X10-i (4) One side of the screw part of 330rranφ9.
22 X' I 0-3772' The total above is Ks""3.73
0-3+5.56x10-3+9.22x10-3)x
2 near, 47xlOmll Torque coefficient of 89mm diameter pipe other than the tip (5) 89r
Pipe part of rrjnφ (per 3m) 3.73 to KP
X l 0-2 The torque of type B is 2000x7.47xlO-111700+1400+ at 30m
1200+1000+850+700+600+500
)X3.73Xlo-2=446 to 9-m ←) Gui C The dimensions are shown in Fig.

The torque of C type is 21mK and 1200x2.46xlO-1+C1000+850+
700+600+500)X2.2X10-1=I09
8Kf-m It can be seen from the above that if type B is screwed in and then type C is screwed in, a peg that can reach deep and hard strata with less torque than type A can be created.

Compare the lifting capacity of Tsugiyaku.

[For type A]

Let Ap be the effective friction area of a pile per 3 m.

AP=2πRpL=2.04i Aps=2.8P? Z
22.04X (1200+1000+850+700+
600+500)+2.8X1400=13814Kg [When combining type B and C] (1) Screw 0.84x (1700+1400)+2.8x2000 for 21m or less
=8200Kg (2) Pipe 2.04 above 21m (1200+1000+850+700+60
0 + 500) = 9894 (3) Total: 8200 + 9894 = 18,094 7 As a result, a pile with a large yield strength can be made with a small torque, and the thick part of the C shape increases the buckling strength of the pile under compressive stress. It has become clear that it is useful for increasing

In the future, the present invention will have a wide range of applications, such as foundation work for power transmission line towers, and its industrial significance will be great.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram showing a conventional pile, Fig. 2 is an explanatory diagram showing how the pile is driven in, Figs. 3 to 5 are explanatory diagrams showing an embodiment of the pile according to the present invention, and Figs. Figure 8 is an explanatory diagram showing the dimensions of each part of the pipe used in the experiment. 10.20,30: Gui no axis, 1121 31 Niscrew.

Claims (1)

[Claims] 1 A pile body that is driven into the ground by a screw rotation method, and the shaft of the pile is made up of multiple concentric cylindrical shafts with different diameters that are fitted and connected in the longitudinal direction, and each shaft has a tip. 1. An underground pile characterized in that the screws are arranged in order from underground to the surface of the earth, and each screw is configured to be rotatable.