JPS6049732B2 - Construction method for cast-in-place concrete piles - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for constructing a cast-in-place concrete pile, in which a concrete pile is constructed by filling a hole with concrete after drilling with an auger.

When drilling with a conventional auger, if the excavated ground is hard or contains cobbles or soft stones, the drilling has to be stopped when it hits cobbles, etc., and stabilizing liquid is not used, especially in silt and gravel layers. However, it was not possible to prevent the collapse of the hole wall, and it was not applicable to a wide variety of geological formations.

Also, after excavation, dirt, etc. gets stuck between the spiral blades, so
After excavation, the auger was pulled up, the sand, etc. was discharged, and the excavation was forced into the ground again, resulting in intermittent excavation, which resulted in poor work efficiency. Furthermore, excavated earth and sand are discharged onto the ground, which makes the work site dirty and requires disposal. Therefore, the present invention first uses the auger as an auger.
We have developed a machine that has cutting performance, uses the excavated earth and sand to fill the hole wall, almost eliminates ground discharge, and allows for continuous drilling penetration, and makes effective use of this auger to ensure reliable construction. We have developed a process for creating cast-in-place concrete piles that can be done quickly.

Hereinafter, the auger used in the pile driving method according to the present invention will be explained with reference to FIG. 3 and stirring blades 4 and 4' projecting radially from the peripheral surface at the tip and base ends of the shaft.The stirring blades 3 may be continuous in the circumferential direction of the shaft, or
They may be spaced apart in this direction as shown.

For its installation, a spiral blade 5 is used, which is provided around the shaft with the tip of the shaft in the direction of screwing. Stirring blade 4,
4'' are, for example, spaced apart in the longitudinal direction and circumferential direction of the shaft, and do not match in the circumferential direction but are alternately oriented in opposite directions, and the spiral blades 5 are also used for their installation.

That is, the helical blades 5 are cut out on both sides of the shaft 1 to provide the blade pieces 4, and the blade pieces 7 with opposite directions are provided between adjacent helical blade parts on the both sides, and these blade pieces 6, 7 are provided. The stirring 4,4″ is configured from
The base end 8 of the shaft 1 has a larger diameter than the distal end 2, and a spiral blade 9 is provided around the base end 8, with the shaft distal end being the screwing direction.

Furthermore, a cutter head 10 having cutting ability is attached to the tip of the shaft 1.

As a whole, the consolidation blade 3, the stirring blades 4, 4'', and the spiral blade 9 are in sliding contact with the wall surface of the hole drilled by the rotation of the cutter head 10, and the peripheral surface of the shaft base end portion 8 is, for example, 100 TIun. They are placed close to each other at intervals.

However, the stirring blades 4, 4'' may be short as long as they have the effect of stirring the excavated earth and sand.The construction method of the present invention using such an auger will be explained with reference to Figs. 1 to 7. is pressed into the ground while rotating, and a hole with a diameter of, for example, 650W$L is drilled up to the support layer S (see Fig. 1).

In the process, even if the shaft hits a layer containing boulders, boulders, or bedrock, the cutter head 10 at the tip of the shaft cuts the boulders and continues drilling. Perforated. When the bentonite liquid is injected into the hole, the mass stirring blade 4 sufficiently stirs and kneads the bentonite liquid and the excavated earth and sand, and then the consolidation blade 3 coats the kneaded material on the hole wall, and even then the inside of the hole is The kneaded material remaining in the stirring blade 4
'' is stirred and kneaded again, and then the spiral blade 9 of the base end portion 8 of the shaft is guided into the gap 11 between the hole wall and the peripheral surface and pressed against the hole wall by the peripheral surface, thereby kneading. Gravel, etc. created by cutting inside the material is pushed into the consolidated hole wall and this is further consolidated.For this reason, it is possible to reliably drill into a wide variety of geological strata, and it also consolidates the hole wall and prevents its collapse. It is possible to perform continuous drilling in a straight line using the hole wall as a guide by the consolidation blade 3 and the spiral blade 9 while preventing the hole wall from collapsing.Also, the excavated earth and sand are used for consolidation of the hole wall and are not discharged to the ground. Even if it is discharged, only a small amount is discharged.Furthermore, since the hole wall is consolidated, the amount of bentonite liquid used is small, and in some cases, spring water can be used instead of bentonite liquid. Possible.600mm with 5 bits 12 at the tip
A casing 13 of the same diameter is rotatably inserted into the borehole 14 using an excavator 15 (see FIG. 2).

At this time, the support layer is further excavated using the bit 12, and the lower end of the casing is bitten into the bottom of the drilled hole. After the auger is pulled up, the perforation 14 is further prevented from collapsing by the casing 13. 6. The soil removal packet 16 is inserted into the casing 13 and the soil is removed (see FIG. 3).

At that time, you can also process slime. 4. A reinforcing bar cage 17 is erected inside the casing 13 (see Fig. 4).

6 The tremie tube 1 is placed inside the casing 13 as a formwork.
8 and fill it with concrete 19 (see Figures 5 and 6).

1 Pull out the casing 13 while rotating it with the excavator 15 (
(See Figure 7).

The concrete 19 can also be compacted during this process.
Various types of earth removal packets 16 are conceivable, but in this embodiment, bottom-opening types shown in FIGS. 7 to 9 are used.

In other words, the scooping part 20, 2', which is formed by dividing a bilaterally symmetrical container into left and right parts along the symmetry plane, has a lever 21, which extends upwardly on the opposite side, at the upper end.
2", both of these levers are pivoted to the mounting shaft 22 in an x-shape, so that they can be opened and closed by being suspended from the mounting shaft 22 and normally closed by their own weight. When closed, the levers are closed by their own weight. To lock one lever 2
A lever-shaped closing stopper 23 that extends up and down in the rotational direction is attached to the upper end of the 1 by a pin 24, and a spring 25 is tensioned between the stopper 23 and the lower end of the mounting shaft 22 at the lower pivot point. By the action of the spring 25, the lower end of the stopper 23 rotates inward and hits the upper part of the scooping part 25'' to prevent the scooping part 2'' from opening.Also, it is pulled up and locked on the ground. In order to automatically release the state, both levers 21,
2'' are attached to the upper end of the stopper 23 and the rollers 26, 2'' to the leader 28 of the pile driving machine 27 surrounding the support shaft 29 that supports the mounting shaft 22. An opening stopper 30 corresponding to 26'' is attached, and when the stopper 30 hits, the stopper 23 is rotated in the unlocking direction, and the levers 21 and 2'' are rotated to open. In step 5, which involves drilling up to the support layer using a special auger, the holes 14 can be formed continuously in a compacted state, and the hole 14 can be continuously formed in the casing 1.
It can be protected by 3. With this casing 13, 8 steps of earth removal treatment, slime treatment, and 4 steps of reinforcing bar cage construction,
Furthermore, the 6-step concrete filling process can be performed easily and quickly. In the borehole where the hole wall does not collapse, the casing 13
Since the casing 13 can be rotated even if the concrete 19 is attached to a part of the casing 19 or even if a large concrete pressure is applied, the casing can be pulled out in one step reliably. The gap between the casing and the hole wall created by the casing is filled with protruding mortar, and since this mortar hardly penetrates into the hole wall, the pile can be constructed with high precision. This pile is stuck in the borehole, and friction is increased by gravel etc. that are biting into the borehole wall and protruding from the borehole wall. As described above, according to the present invention, it is possible to deal with a wide variety of geological strata,
In addition, the desired purpose can be achieved, such as construction can be done reliably and quickly.

[Brief explanation of the drawings] Figures 1 to 7 are cross-sectional views showing the construction process of the present invention;
The figure is a side view showing the usage status of the soil removal packet, Figure 9.
FIG. 10 is a front view showing the opened and closed state of the earth removal packet. 1...Shaft, 2...Tip, 3.
... Consolidation blade, 4,4''... Stirring blade, 5...
... Spiral wing, 6, 7... Wing piece, 8... Base end portion, 9... Spiral wing, 10... Cutter head, 11... ... Gap, 12 ... Bit, 13 ... Casing, 14 ... Drilling, 15 ... Excavation machine, 16 ... For earth removal Packet, 17... Reinforced cage, 18... Tremy pipe, 19... Concrete, 20, 2...
・・・Scooping part, 21,2 ``...Lever, 22...
...Mounting shaft, 23...Closing stopper, 24, 24''...Pin, 25...Spring, 26,26''...Roller, 27... - Pile driving machine, 28... Leader, 29... Support shaft, 30... Opening stopper.

Claims (1)

[Claims] 1 (a) The auger shaft is a stepped shaft whose base end is enlarged to a diameter close to the drilling diameter, and around the base end of the shaft, the tip end of the shaft is directed in the direction of screwing. A consolidation blade is provided around the tip of the shaft and is curved along the circumferential direction away from the circumferential surface of the shaft, and a stirring blade that protrudes radially from the circumferential surface of the shaft on the tip side of the shaft of the consolidation blade. An auger with a cutter head attached to the tip of the auger shaft is used, and the auger shaft is rotated to cut the cobblestone with the cutter head at the tip, and as the hole is being drilled, bentonite liquid is injected and the bentonite is mixed with a stirring blade. The liquid and excavated earth and sand are stirred and kneaded, then a compaction blade applies the mixture to the hole wall, and then a spiral blade at the base end of the shaft pushes the cut gravel in the mixture into the hole wall to drill the hole. Process. (b) The process of inserting the casing into the hole. (c) The process of building a reinforcing bar cage inside the casing. (d) Process of filling the inside of the casing with concrete using it as a formwork. (e) Process of pulling out the casing while rotating it. A construction method for cast-in-place concrete piles, characterized by performing the above steps in sequence.