JPH03212512A - Rotating settling engineering method for pile - Google Patents

Abstract

PURPOSE:To surely make the forward end of a pile sink to the bottom of a hole by setting an accompanying rotation preventing device to a digging rod, thereby preventing clay to be dug up from fixing to a bit and preventing a soil block from being accumulated on the bottom of a hole. CONSTITUTION:A vane-type bit 12 is fixed to the forward end of a hollow rod body 11, an accompanying rotation preventing device 15 is rotatably installed above the bit and blades 14 are fixed by means of plural stirring blades 13. At the time of drilling, the accompanying rotation preventing device 15 is not rotated in relation 18 a rotating digging rod 10 because the forward end portions of blades 18 of the device are caught in the soil around a digging hole and a soil block having a high viscosity is finely sheared between the rotating bit 12 and the blades 18, 18 not rotated. Further, the clay is kept from being fixed to the bit 12 and rotated together, and the sol block is prevented from being accumulated in the bottom of a hole. Thus, the lowering of a digging speed can be prevented, and a smoothing effect of a hole wall can be improved so as to form a strong hole wall, and the forward end of a pile can be surely made sink to the bottom of the hole.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an improvement of a pile rotary sinking method, which is one of the pile driving methods in foundation construction.

[Prior Art] As shown in Fig. 5, in the conventional rotary sinking method, a bit 2 equipped with an expanding blade 2a that can be expanded and retracted is attached to the tip, and a stirring blade 3 is attached above the bit 2. Using a hollow drilling rod 1 each having a plurality of blades 4 attached thereto, construction is carried out in accordance with the procedure shown in FIGS. 8a to 8f or 9a to 9f. Furthermore, as shown in Figures 10a to 10f, there is a construction method that does not involve expanding the base and hardening the base.

Figures 8a to 8f show a construction method called the widened bottom hardening method, in which the drilling rod 1 is first rotated and fed as shown in Figure 8a, and drilling fluid is sent from a mortar plant into the hollow part of the drilling rod 1. Discharge port provided in bit 2 (not shown)
Excavation is carried out to a predetermined depth while discharging more water and turning the inside of the borehole into mud.

After excavating to a predetermined depth, the drilling rod 1 is repeatedly moved up and down to turn the soil into mud in the drilling hole, and then, as shown in FIG.
While excavating while repeating up and down, the mortar plant sends a hardening solution (hardening material) and discharges it from the discharge port.
While stirring and mixing with the sand and gravel in the support layer 5, a wide-bottom hardening bulb 6 is built in the support layer 5 (Fig. 8c).Next, the excavation rod 1 is returned to normal rotation, and the expansion blade 2a is closed. The root hardening fluid is switched to drilling fluid, which is discharged from the discharge port, and the drilling rod 1 is pulled up while turning the soil in the drilling hole into mud (Fig. 8d).

After this, as shown in Fig. 8e, the pile 7 is suspended and set in the special rotating cap 8 attached to the auger motor, and the pile 7 is erected into the excavation hole. Bury it in the excavation hole by sinking it under its own weight and rotating it. In addition, when the joint pile 7a is provided, the lower part 7 is held by a holding device, the joint pile 7a is suspended by the rotary cap 8 in the same manner as described above, and the joint is connected by joint welding. And stake 7゜7a
is fixed to the expanded-bottom hardening bulb 6 built on the support layer 5 by settling under its own weight and rotating.

Figures 9a to 9f show a construction method called the method of expanding the bottom of the foundation and injecting fixing liquid around the pile, and Figures 9a to 9C are the same steps as those in Figures 8a to 8c, but Figure 9d shows When the rod is pulled out, pile circumferential fixing liquid is injected into the borehole instead of drilling fluid to form a strong hole wall.
．． The hole is drilled to a diameter larger than 7a, so that the pile circumferential fixing liquid (solidifying material) rises around the shaft 7.7a as the pile 7.7a sinks.

Incidentally, as shown in FIGS. 10a to 10f, this rotary sinking method also uses a drilling rod equipped with a normal type bit that does not have the enlarged blades 2a.

[Problems to be Solved by the Invention] However, in the above-mentioned conventional rotary sinking method, when excavating a highly viscous soil layer, especially a hard clay soil layer, the viscosity 20 sticks to the bit 2 as shown in Fig. 6. There was a problem in that the excavation speed was significantly reduced due to a synergistic phenomenon in which the excavation speed was significantly reduced.

Also, during excavation, hard, viscous soil becomes large lumps of soil that float in the borehole and accumulate at the bottom of the borehole before the pile 7 is sunk, as shown in Figures 7a and 7b. As shown in Figure 7a, if the pile does not have a wide-bottom hardening bulb at the lower end, there are cases where the tip of the pile 7 cannot be sunk to the bottom of the excavation hole (referred to as "high up"). The problem was that the heads of the piles that came out were uneven, and it took a lot of man-hours to install. In addition, when the expanded-bottom hardening bulb 6 is constructed as shown in Fig. 7b, the pile cannot be sunk to the middle of the bulb 6, and furthermore, due to the accumulation of soil clods 21, the amount of hardening material becomes insufficient, and the bulb 6 becomes insufficient in strength. There were drawbacks.

The present invention was developed in view of the above circumstances, and is designed to prevent viscosity from sticking to the bit during excavation, and to prevent soil clods from accumulating at the bottom of the hole, thereby ensuring that the tip of the pile reaches the bottom of the hole. Alternatively, it is an object of the present invention to provide a method for rotary laying of piles, which enables the installation of expanded-bottomed root hardening bulbs to a predetermined position.

[Means for Solving the Problems] In order to achieve the above object, the pile rotation method of the Japanese invention fixes a bit to the tip of the rod body, and above the bit there is a blade with a longer diameter than the diameter of the bit. A drilling rod, which is rotatably equipped with a co-rotation prevention device and has a plurality of stirring blades and a plurality of stroking blades fixed above it, is rotated and fed in the forward direction, and a drilling rod is rotated and fed in the forward direction, and a drilling rod is rotated and fed in the forward direction. The step of drilling a hole to a predetermined depth while discharging drilling fluid, and discharging drilling fluid or solidified material from near the tip of the rod body while rotating the rod body in the opposite direction and pulling it out halfway into the drilling hole. Next, the step of stopping the discharge of drilling fluid or solidifying material and pulling out the rod body to the ground level, and the step of fixing the pile to the bottom of the hole by sinking it under its own weight and rotating it while suspending the pile in the hole. According to claim 1, an enlarged O-bit that opens its wings by reverse rotation is provided at the tip of the rod body, and a synchronization prevention device having wings with a longer diameter than the diameter of the bit is rotatably mounted above the bit. Then, a drilling rod with a plurality of stirring blades and a plurality of smoothing blades fixed above the rod is rotated and fed in the forward direction while discharging the drilling fluid from near the tip of the rod body, and the diameter of the pile is adjusted. The process of drilling a hole of approximately the same diameter to a predetermined depth. After drilling to a predetermined depth, the rod body is rotated in the opposite direction to open the enlarged blades of the enlarged bit, and the expanded bottom hardening bulb part is drilled at a predetermined distance. While enlarging the excavation, the solidified material is discharged from the enlarging bit, and the rod body is repeatedly moved up and down to drill, mix and stir the hole, pass the upper end of the bulb part, and rotate the rod body in the forward direction. The step of opening the enlarged wings and withdrawing the rod body a predetermined distance while discharging drilling fluid from near the tip of the rod main end, then stopping the discharge of drilling fluid and withdrawing the rod body to the ground. , a second claim consisting of a step of fixing the pile to the middle of the bulb part by self-weight settling and rotation burial while suspending the pile in the drill hole, and in the second claim, the diameter of the drill hole in step (a) is , a third claim characterized in that the diameter is larger than the diameter of the pile to such an extent that the solidification material can rise around the pile when the pile is sunk, and the drilling fluid in step (c) is used as the solidification material. Consists of.

[Function] When drilling a hole, the rotating drilling rod does not rotate because the tip of its blade bites into the soil around the drilling hole, so even highly viscous soil clods are not rotated by the rotating bit. In addition to being finely sheared between the blades that do not rotate, the clay is also prevented from sticking to the bit and rotating together. Therefore, since clods of soil do not accumulate at the bottom of the hole, the tip of the pile can be reliably sunk to a predetermined position at the bottom of the hole or the hardening bulb.

[Example] Hereinafter, one embodiment of the present invention will be described based on the drawings.

FIG. 1 shows an example of a drilling rod used in the construction method of the present invention. This drilling rod 10 has a blade-shaped bit 12 fixed to the tip of a hollow rod body 11, and above which a co-rotation prevention device 15, which will be described later, is rotatably attached, and further above which a plurality of stirring It is formed by fixing a wing 13 and a smoothed wing 14.

The co-rotation prevention device 15 includes a boss 17 loosely fitted between a pair of flanges 16 and 16 protruding from the rod body 11;
It consists of a pair of wings 18 and 18 fixed to the outer periphery of the boss 17 axially symmetrically and having a longer diameter than the diameter of the bit 12. Note that the bit 12 may be provided with the enlarged wings 2a shown in FIGS. 8a to 8f and 9a to 9f.

Therefore, using the above-mentioned drilling rod 10, the above-mentioned FIGS.
When the rotary pile laying method is carried out according to the procedure shown in Fig. 8f or Figs. 9a to 9f, the co-rotation prevention device 15 moves its wings 18 and 18 against the rotating drilling rod 10 with respect to the drilling hole. Since the tip of the blade bites into the soil around the excavation hole and does not rotate, highly viscous soil clods are finely sheared between the rotating bit 12 and the non-rotating blades 18. It also prevents them from sticking and rotating together. Therefore, in the case of the conventional construction method that does not involve expanding the base as shown in Figures 10a to 10f,
As shown in the figure, clods of soil are deposited on the bottom of the hole, but in the construction method of the present invention, no clots of soil are deposited on the bottom of the hole, so the tip of the pile 7 is reliably sunk to the bottom of the hole as shown in FIG. 4a.

In addition, conventional Figs. 8a to 8f or Figs. 9a to 9f
As shown in the diagram, when installing an expanded root hardening bulb at the tip of the pile,
Since the soil clods accumulate at the bottom of the hole, the pile tip cannot be completely sunk to the middle of the bulb, and a strong bulb cannot be formed by the solidifying material.However, in the case of the method of the present invention, the pile tip does not accumulate at the pile bottom, so the pile tip cannot be completely sunk to the middle of the bulb. can be completely submerged to a predetermined position in the middle of the bulb, forming a strong bulb due to the solidification material.

Note that FIGS. 2 and 3 show modified examples of the drilling rod 10, and the drilling rod 10a in FIG. 2 is equipped with a screw-type bit 12a as a bit.
The drilling rod fob in Fig. 3 is a screw-type bit 12.
A different type of bit 12 is attached above a.

Other structures and functions are similar to the drilling rod 10 shown in FIG.

[Effects of the Invention] As explained above, according to the present invention, the soil does not stick to the bit during drilling, and the soil clods are shredded, so that a decrease in the excavation speed is prevented, and the smoothing blade This improves the smoothing effect of the hole wall, forming a strong hole wall and making it easier to sink the pile. Furthermore, since it is possible to prevent soil clods from accumulating at the bottom of the hole, the tip of the pile can be reliably sunk to the bottom of the hole or to a predetermined position in the expanded-bottom hardening bulb.

[Brief explanation of drawings]

FIG. 1 is a front view showing an example of a drilling rod used in the construction method of the present invention, FIGS. 2 and 3 are front views showing modified examples of the same drilling rod, and FIGS. 4a and 4b are front views showing an example of the drilling rod used in the construction method of the present invention. Fig. 5 is a front view of the excavation rod used in the conventional method, Fig. 6 is a front view showing the excavation rod with soil attached to it, Fig. 7a and Fig. Figure 7b is an explanatory diagram showing a state in which the pile is not completely sunk by the conventional construction method, Figures 8a to 8f are process diagrams showing an example of the conventional construction method, and Figures 9a to 9f are diagrams showing other examples of the conventional construction method. The process diagrams shown in FIGS. 10a to 10f are process diagrams showing still another example of the conventional construction method. 2a... Expanding wing, 7.78... Pile, 10.10a,
10b... Drilling rod, 11... Rod body, 2.12, 12a... Bit, 13... Stirring blade, 1
4... Smoothing wing, 15... Co-rotation prevention device, 18
...Wings.

Claims (3)

[Claims] (1) A pile rotation method consisting of the following steps: (a) Fixing the bit to the tip of the rod body,
A rotation prevention device having blades having a longer diameter than the diameter of the bit is rotatably mounted above the bit, and a drilling rod having a plurality of stirring blades and a plurality of smoothing blades fixed above the device is rotated in the forward direction. Step (b) Drilling a hole to a predetermined depth while rotating and feeding the rod body and discharging drilling fluid from the vicinity of the tip of the rod body; Reversely rotating the rod body,
Step (c) of pulling out the rod partway into the excavation hole, then stopping the discharge of the drilling fluid or solidifying material, and pulling out the rod body to the ground (c) The pile is suspended in the excavation hole by sinking under its own weight and by rotational burying. The process of fixing it to the bottom of the hole (2) A pile rotation method consisting of the following steps: (a) At the tip of the rod body, an enlarged bit and a bit whose wings open in reverse rotation are provided, and above the bit, a co-rotation prevention device having wings with a longer diameter than the diameter of the bit is rotatably attached, and A drilling rod with a plurality of stirring blades and a plurality of smoothing blades fixed to the upper part is rotated and fed in the forward direction while discharging drilling fluid from near the tip of the rod body, and is rotated and fed in a forward direction to create a rod with a diameter approximately the same as the pile diameter. Step of drilling a hole to a predetermined depth (b) After drilling a hole to a predetermined depth, the rod body is rotated in the opposite direction to open the expansion blades of the expansion bit, and the expanded bottom hardening bulb part is enlarged and drilled at a predetermined distance. (c) passing the upper end of the bulb part and rotating the rod body in the forward direction; The step of opening the enlarged wings and withdrawing the rod body a predetermined distance while discharging drilling fluid from near the tip of the rod main end, then stopping the discharge of drilling fluid and withdrawing the rod body to the ground. (d) The process of fixing the pile to the middle of the bulb by sinking it under its own weight and rotating it while suspending it in the excavation hole. (3) In the second claim, the diameter of the hole drilled in step (a) is made larger than the diameter of the pile to such an extent that the solidification material can rise around the pile when the pile is sunk, and step (c) ) A method for rotating piles and sinking piles, which is characterized by using drilling fluid as a solidifying agent.