JPH0321719A - Pile driving method - Google Patents

Abstract

PURPOSE:To realize a low-pollution pile driving operation by burying a closed type casing on the tip of which a cutting tool capable of being freely loaded and unloaded is provided into a hole drilled by an auger, throwing cement milk into the casing, inserting a ready-made pile into it, and then drawing out the casing. CONSTITUTION:A closed type casing 2 on the tip of which a cutting tool 5 capable of being freely loaded and unloaded is provided, is inserted while it is rotated, into a vertical shaft 9 drilled by an auger. Then, cement milk 7 is thrown into the casing 2, and a ready-made pile 8 is inserted into the casing. After that, the casing 2 is drawn out with the cutting tool 5 on its tip left in the hole. Thus, a low-pollution pile driving operation can be performed with good operating performance and economy.

Description

[Detailed Description of the Invention] (Object of the Invention) The present invention relates to a pile driving method that is adopted as a civil engineering work to reinforce the bearing capacity of the ground, and in particular, it guarantees the embedment of prefabricated piles according to the design value. Furthermore, the present invention aims to provide a new construction method for embedding existing piles in the soil without causing noise pollution, vibration pollution, or milk pollution.

(Prior art) In civil engineering work in urban areas, noise pollution and vibration pollution generated during the work process, as well as the disposal of earth and sand, waste liquid, etc., have become major social problems, so diesel hammers and vibrating hammers, which had been used until then, were no longer used. It has become difficult to adopt the driving method of pre-fabricated piles, and in their place, reverse circulation method, donut auger method, and medium-drilling percussion method have been developed and put into practical use.

However, with the reverse circulation method, donut auger method, etc., the problem of disposing of large amounts of water, soil, or soil cement mixed with bentonite solution has not been solved, and with the hollow impact method, Due to the drawbacks such as being unsuitable for thick pre-fabricated piles such as concrete piles, the applicant of this application has decided to use pre-fabricated casings and pre-fabricated piles, which have already been developed as the invention of Japanese Patent Application No. 1-1-3877-1. We succeeded in developing a new pile driving method in combination with piles, and succeeded in achieving results that could not be achieved with previous methods. However, even with this new construction method, even if the casing is driven to a predetermined depth and the earth and sand are discharged, the earth and sand may flow around and accumulate at the bottom of the casing along with groundwater. Even if you pour cement milk into the inside and drop a prefabricated pile into it,
Naturally, the tip of the pile can only penetrate as far as the surrounding earth and sand, and if you are trying to achieve the specified driving depth of a prefabricated pile, it will penetrate through the area where the earth and sand have gone around (sometimes as much as 2 to 3 meters). Therefore, it is necessary to use a pile driver to drive and bury the piles, which not only requires extra work, but also causes noise or vibration pollution at this stage.

Therefore, when attempting to bury a prefabricated pile to the calculated depth, the casing should be pushed further than the calculated value in advance to form a deeper shaft in anticipation of encountering such a phenomenon. Or, although it is not a good thing, in order to avoid pollution problems, existing piles that have encountered such phenomena are unavoidably left protruding above the ground without reaching the specified depth. We had no choice but to cut off the heads of the existing piles and dispose of them.

It goes without saying that these measures are uneconomical in terms of construction efficiency, and most importantly, they leave behind the serious problem of creating piles that cannot achieve the design value. The development of an improved construction method was desired. In view of the above situation, this invention has been developed to further improve and improve the
As a result of pushing forward with development, we have finally achieved the desired result, and we will explain its structure in detail below. (Structure of the Invention) As can be clearly understood from the representative examples in which the construction process is shown as a model in the drawings, the pile driving method of the present invention consists of the following steps. [First step] This is the step of forming a shaft of a predetermined depth by digging with the spiral auger 1. When the spiral auger 1 rotates and excavates, if necessary, compressed air is ejected from the tip of the excavation head as before to smooth the discharge of excavation soil and to improve excavation efficiency.

Also, after completing this process, the spiral auger 1
is pulled out and removed from the drive device 3, and the drive device 3 itself is also removed from the reader (not shown) and replaced with a drive device 3' for gauging.

[Second step: After pulling out the cospiral auger 1, the casing 2 with the removable cutting blade 11 attached to its tip is rotated, and air or high-pressure water is spouted from the tip of the casing 2. 2 is forcibly buried in the shaft 9 formed in the first step.

The process in between is shown schematically in the process diagram in Figure 1 (opening). The casing 2 adopts a structure in which both the upper and lower ends are closed in a sealed manner, and the most typical embodiment thereof is shown in FIGS. 2 to 4. That is, as shown in the partially omitted exploded front view of FIG.
Makishimesu y! ．． A cap/connection part 41 formed at the center of the lower end of the casing 4 is removably fitted to the casing 2, and an inverted L-shaped connection notch 42, 42, . . . into the fitting pieces 21, 21 . . . on the outer periphery near the upper end of the casing 2,
When the joint shaft 43 is connected to the casing drive device 3' and slightly rotated, the cap connecting portion 41 connected to the joint shaft 43 rotates and the seaming device 4 is rotated.
and the casing 2 are irremovably connected. (
When detaching, rotate the joint shaft 43, that is, the cap joint 41, slightly in the opposite direction. ) Although not shown in the figure, the inner surface of the connecting part 41 that also serves as a cap, and the connecting notches 42, 42,
......A sealing member such as an O-ring is installed at a higher position to achieve close contact with the outer peripheral surface of the casing 2, and this sealing will be described later. FIG. 3 is a plan view of the head fitting 5, and A to Al in the figure.
Attaching the sealing member 55 shown in FIG. 4 which is a tfi view! It is formed in the same manner as the r4 structure.

The tightening arm 44 has a free ellipse with respect to the cap joint 41, that is, even if the joint shaft 43 and the cap joint 4l connected thereto are rotated by the casing drive device 3', The winding arm 44 is formed in a combination structure that does not rotate. In the figure, 45
shows a pulley for passing the seaming row 16. On the other hand, a head metal fitting 5 is detachably and tightly connected to the lower end of the casing 2. The head metal fitting 5 has an L-shaped connection notch 52,52, in its upper structure.
. . . is formed in a connecting portion 51 having
1 connection notch 52, 52. Fitting pieces 22, 22, . . . formed on the outer periphery near the lower end of the casing 2
By rotating and fitting, the head fitting 5 is irremovably connected to the lower end of the casing 2.

(When removing the head fitting 5, this is done by rotating the casing 2 in the opposite direction and pulling it up.) The inner surface of the connecting portion 51 has connection notches 5 2 , . 5 2
, . . . A sealing member 55 for realizing a sealing structure with the casing 2 is installed slightly below the forming position, as shown in the longitudinal sectional view of FIG. 4. The horizontal structure at the lower end of the head metal fitting 5 is formed with a cutting blade 53 as appropriate, and a valve 54 is arranged at the boundary with the upper oval structure, and compressed air or pressure water is supplied into the casing 2, which is sealed at both the upper and lower ends. is sent to eject from the valve 54, and the shaft 9
It functions to smoothly press fit the casing 2 into the inside.

In the illustrated embodiment, the most economical and functional horizontal structure of the drilling blade 53 is adopted, in which two steel plates intersect in an X-shape. There is no particular limitation, and any other '4:R structure may be adopted as long as it is economical and functional considering that it will eventually be disposed of at the bottom of the shaft 9. [Third Step] After pouring a predetermined amount of cement milk 7 into the casing 2 while embedding it in the shaft 9 and continuing the rotation of the casing 2, a prefabricated pile 8 such as a concrete pile, a steel pipe pile, or an H-steel pile is inserted.
Lift it up [see Figure 1 (c)], insert it gently into the casing 2, and lower it until its tip reaches the head fitting 5, until it is in the state shown in the process diagram in Figure 1 (2). Realize. The process of sustaining the rotation of the casing 2 during the injection of the cement milk 7 for root consolidation is extremely important in preventing deformation and destruction of the casing 2 and facilitating the removal of the casing 2. According to the experimental results, there have been cases where the casing 2 was destroyed due to earth pressure or other reasons due to continuing work with rotation stopped for more than 10 minutes, causing a great deal of trouble in the extraction work. It has been confirmed. Although omitted in the figure, the lifting of this existing pile 8,
During the lowering operation, the leader of the conventional pile driving machine used when operating the spiral auger 1 and casing 2 in the first and second steps may get in the way, so the upper part of the leader should be It is desirable that the conventional pile driving machine be equipped with a structure that allows it to be tilted at an inclination angle of about 5 to 10 degrees while being supported by a hydraulic cylinder. It is sufficient to prepare a crane, and while grasping the column head of the pre-fabricated pile 8 using a clamp or chuck as appropriate, lifting it up and lowering it into the casing 2 in line with the pile core, the casing 2 is rotated by the pile driver. This is to ensure that it continues to last. In addition, in order to position the prefabricated pile 8 at the center of the casing 2, a patent application filed in 1986-13, which was already developed, was applied.
Temporary fixing devices 5 such as those adopted in the invention of No. 8771 and other known fixing devices can be used. Fourth step While preventing the prefabricated pile 8 housed in the casing 2 from floating up, the casing 2 is rotated in the opposite direction to the previous rotation direction, the head fitting 5 is detached, and the casing 2 is rotated (in the correct direction). (rotate) and pull up gently. This process is schematically shown in the process diagram of FIG. 1 (e).

As a means to prevent the existing pile 8 from floating up, it is possible to place an appropriate weight on the pile capital, but there are other methods as well, such as those shown in the plan view in Fig. 3 and the vertical cross-sectional view in Fig. 4. The claw pieces 56 as shown are made to protrude in an inclined manner around the valve 54, and the claw pieces 5 are attached to the tips of the corresponding pre-made piles 8.
A protruding piece (not shown in the figure) that can be engaged with 6 is formed,
As the casing 2 rotates (forward rotation) during extraction, the rotational force is transmitted to the pre-fabricated pile 8 using the cement milk 7 as a medium, and when the pre-fabricated pile 8 itself rotates, the claw piece 56 causes the tip of the pre-fabricated pile 8 to It is also possible to adopt a structure in which the protrusions interlock to prevent lifting. In addition, in order to slightly increase the pile bearing capacity, expansion drilling blades 23, 23, . . . are provided at the bottom of the shaft 9 to enlarge the shaft diameter.
... on the lower outer periphery of the casing 2, the fitting pieces 22, 22.
It is formed at a position appropriately above the casing 2, so that when the casing 2 is rotated, it fits along the outer peripheral surface of the casing 2 and does not interfere with the rotation, and on the other hand, when the casing 2 is rotated in the opposite direction, That is, when the head fitting 5 is detached from the bottom of the shaft 9 and discarded, the tips of the blades 23, 23, . . . expand outward due to centrifugal force and touch the peripheral wall of the shaft 9. It is also possible to make it possible to cut into the hole and excavate and enlarge the peripheral wall at the lower part of the shaft 9 to an appropriate size. Therefore, as in the embodiment, this expanding digging blade 2
3,23. If the casing 2 equipped with... is adopted, the reverse rotation operation is not limited to only the reverse rotation operation to remove the head metal fitting 5, but also the reverse rotation operation for a while after the head metal fitting 5 has been removed. Allow the rotation to continue.

After pulling up the casing 2, if the cement milk 7 is too low below the ground surface (especially when the diameter of the hole is expanded as described above), replenish the appropriate amount of cement milk 7 around the existing pile 8. There are things to do.

The pile driving method of the present invention is completed by smoothly reversing the first to fourth steps. (Operation and Effect) The pile driving method of the present invention, which is realized through the steps described above, has the following characteristics. First of all, instead of adopting a casing with an open top and bottom as in the past, a sealed casing 2 was used, and the inside of the shaft 9, which had been excavated in advance with the spiral auger 1, was used. The casing 2 is forcibly inserted into the casing 2 until it reaches a predetermined depth, and even if the supply of compressed air or pressurized water is stopped after reaching the predetermined depth, water and earth and sand will still come out from the bottom of the casing 2. Because the water does not flow backwards and blow up inside the casing 2, it can exhibit an extremely excellent feature that allows both the cement milk 7 and the prefabricated piles 8 to reach the correct depth as designed. To become a. Therefore, it can be particularly effective in geological sites with severe collapsibility and strong spring water.

The realization of this highly effective construction method was achieved by using a head fitting 5 that realizes close-contact horizontal construction of the lower part of the casing, instead of burying the casing 2 while letting the spiral auger 1 lead the way, as was the case in the past. Equipped with a digging blade 53, the casing 2 alone excavates the inside of the shaft 9 previously excavated by the spiral auger 1, and after reaching a predetermined depth, the head fitting 5 is discarded at the bottom of the shaft 9. This was made possible only through the adoption of a unique method.

The second feature is that although the 50 head fittings are disposable and somewhat uneconomical in that respect, they are specially designed to displace or pierce groundwater, earth, etc. that have blown up inside the casing 2. Overall, this method is extremely economical when compared to the cost and time required.

The third feature is that in each process, there is no risk of generating noise or vibration that could become a source of pollution, no matter how bad the conditions are, such as a site with a stratum that is highly collapsible and prone to spring water. In that sense, it is especially suitable for piling construction methods in urban areas. In addition, the casing 2 completely protects the six surrounding walls of the pile, and any type of prefabricated pile 8 can be inserted, making pile driving extremely flexible in terms of design management. This makes it possible to realize pile driving that is superior in terms of workability, safety, and economy compared to other conventional pile driving methods.

As mentioned above, the pile driving method of the present invention is extremely reliable, economical, and efficient compared to previous pile driving methods due to its unique process. It is expected that it will not only benefit civil engineering contractors but also be highly evaluated by society.

[Brief explanation of drawings]

The drawings are based on representative examples of this invention, and Figure 1 is a process diagram showing the construction process in terms of the central aspects of each process, and Figure 2 is a process diagram showing the construction process adopted in the construction process. FIG. 3 is a plan view of the head metal fitting, and FIG. 4 is a sectional view taken from A to A. 1...Spiral auger, 2...Casing, 3.
3'... Drive device, 4... Sealing tightening device, 41...
・Connection part for the same cap, 42... Notch for the same connection,
43... Same joint shaft, 44... Same winding tightening arm, 5... Head metal fitting, 51... Same connection part, 52...
- Notch for continued coexistence, 53... Same excavating blade, 54... Same valve, 56... Same claw piece, 6... Sealing lobe, 7...
・Cement milk, 8... Prefabricated pile, 9... Vertical shaft, G
···ground. No.-11

Claims (1)

[Scope of Claims] A pile driving method in which prefabricated piles are buried underground in the following first to fifth steps. First step: A step of forming a shaft of a predetermined depth by digging with a spiral auger. Second Step After the spiral auger is pulled out, the casing, which has a removable excavation blade attached to its tip, is rotated, and while air or high-pressure water is spouted from the tip of the casing, the casing is shaped like the one formed in the first step. The process of forcibly burying the body in a vertical shaft. 3rd step After pouring a predetermined amount of cement milk into the casing while maintaining the rotation of the casing, lift the pre-fabricated piles such as concrete piles, steel pipe piles, and H-steel piles.
Gently insert it into the casing and lower it until its tip reaches the head metal fitting. Fourth step: While preventing the ready-made pile housed in the casing from floating up, the casing is rotated in the opposite direction to the previous rotation direction to remove the head fitting, and then the casing is gently pulled up.