JPH05222725A - Lower end deferred type drilling blade for pile readily installed by inner excavation process - Google Patents

Abstract

PURPOSE:To execute pile installation work of inner excavation and bottom enlarging type surely and profitably by using a readily installed pile lower end differed type drilling blade for forming a bulb under pile. CONSTITUTION:A readily installed pile P integrated with a drilling blade formed out of an upper hollow frame 1, a lower frame, a middle frame, and the like on its extreme end is pressed in a prescribed position of the ground G, while drilling the ground G by means of the extreme end bit employed in inner excavation process and reversely rotating the pile P against the rotating direction of an auger. After implanting a pile into a decided depth, addition of succeeding piles to the readily installed pile P is repeated, and the piles are buried up top the supporting layer G1 of decided depth. next, rotation of the auger is stopped, integrated readily installed piles P, P... are rotated in the reverse direction against the rotating direction during implantation, the ground G outside the circumference of the readily installed pile P is scraped out by projecting and retreating blades 4, 4, and a bulbous hole is formed on the bottom part of the pile hole around the supporting layer. Finally, cement milk is poured in the hollow part of the readily installed piles P, P..., the piles are rotated in the same direction as that before stop in the condition in which the blades 4, 4 are projected, so as to fully mix the cement milk with pebbles.

Description

Detailed Description of the Invention

[0001]

It is an object of the present invention to provide a medium excavation method which is one of the pile driving methods, that is, an earth auger is inserted into the hollow portion of a prefabricated pile, and the tip of the prefabricated pile is excavated by a bid at the tip and the prefabricated pile is guided In the pile driving method that pushes in the pile, it is intended to provide an existing pile bottom end stationary excavating blade having a new structure of a disposable type adopted to form a bulb under the pile that enhances the bearing capacity of the existing pile. ..

[0002]

2. Description of the Related Art Even if the demand for expansion of domestic demand from foreign countries is not supported by this, it has been spurred by public works investment, which has been booming underpinned by the domestic situation in which the economy is booming. There is no difference between the central and rural areas, that is, the county area and the urban area, and there is no distinction between remote areas such as mountainous areas and downtown areas. Among them, it is the noise and vibration pollution problems that occur with pile driving work, which is essential for ground reinforcement, that always suffers from countermeasures in construction and civil engineering works in or near the town. .. In the past, some suggestions have been made to address these issues, including low vibration,
Many are actually adopted as low noise construction methods.

[0003] Medium excavation method, that is, the earth auger is inserted into the hollow portion of the precast pile, and the tip of the precast pile is excavated with the bid at the tip.
Pushing the precast pile while leading, reaching the predetermined support layer, pulling up the earth auger, pouring cement milk into the hollow part of the precast pile and solidifying it, it is supported by the support layer and placed at a predetermined position below the ground surface. The pile driving method to form one pile that reaches up to one after another is one of the low-vibration and low-noise pile driving methods that have been developed and put into practical use in response to those requests. Is playing an active part in the construction site. Recently, as an improved version of this construction method, a construction method called "medium excavation bottom expansion method" has appeared, and an expanded bulb is formed at the lower end of the pile reaching the support layer to increase the bearing capacity of the pile,
More effective pile formation is being realized.

A typical example of the construction method that has already been adopted as the "medium digging bottom expansion construction method" is called the STJ construction method, and after the pile reaches the support layer, cement cement for root consolidation is added to the earth auger. While ejecting at high pressure from the jet nozzle provided around the rotating bit through the hollow shaft, the auger is slowly raised to collapse the support layer and form an enlarged bulb at the lower end of the pile, which is called the NAKS method. After reaching the supporting layer, the bit at the tip of the earth auger is still dug to make the bit project further downward from the lower end of the pile, and then by remote control, the expanding blades pre-assembled into the bit are The cement milk and gravel and gravel on the cement milk while excavating the support layer at the bottom of the pile over a range larger than the pile diameter by rotating the bead while injecting the cement milk. The forming the enlarged bulb was sufficiently mixed, then, is seen to that as pulled then gently pursed expansion wings to the original state.

[0005] In the former deep digging bottom expansion method called STJ method, since cement milk is soft and kneading with sand and gravel is not always sufficient, piles are removed during the auger dismantling work carried out at the time of pulling out the earth auger. There is a drawback that the bottom of the pile will sink into the cement milk mixed with sand and gravel for bulb formation due to the load of the pile driver applied to the upper end, and the problem that the pile driving cannot be completed as designed, the latter NAKS In the construction method, after the expansion bulbs were formed under the piles, in the process of putting the expansion blades back into their original state, there was a situation in which gravel that had been drilled or kneaded was caught and could not be reduced as planned, and the diameter was still larger than the hollow part diameter. If it stops in the state of, the earth auger cannot be pulled up, and expensive bit with expanded blades built-in are forced to leave the earth auger in the pile, which is economical. Become to suffer a major blow.

In the present invention, in view of the above situation,
As a result of working on the development and research of a new device that can more reliably and economically implement the bottom digging bottom expansion method, we completed the existing bottom pile stationary drilling blade to finally realize it. It is obtained, and the configuration will be described in detail below.

DETAILED DESCRIPTION OF THE INVENTION The lower end stationary excavating blade of the precast pile of the present invention represented by the embodiment shown in the drawings basically has the following constitution.

That is, the hollow upper frame 1 according to the diameter of the prefabricated pile P
And a plurality of shaft members 3, which are attached as supporting portions, and a lower hollow frame 2 arranged at a predetermined distance below the upper hollow frame 1.
In contrast to 3, ..., the inlet / outlet blade 4 formed on the shaft mounting portion 41 on one end side and on the blade tip portion 42 on the other end side is rotatably pivoted in the horizontal plane by the shaft mounting portion 41, and is rotated in the horizontal plane. The moving range is regulated from a position that is substantially accommodated in the outer peripheral surface of the prefabricated pile P to be attached, to a position where the outer peripheral surface intersects and the cutting edge 42 projects from the outer peripheral surface of the prefabricated pile P. Digging method This method is used as a bottom-mounted stationary excavation blade for existing piles.

The hollow upper frame 1 and the hollow lower frame 2 are made of ring-shaped thick steel plates that are substantially equal to the horizontal cross-sectional shape of the prefabricated pile P, and support shaft members 3, 3 ,. While performing the function, the hollow upper frame 1 has its upper surface positioned at the lowermost end (that is, the contact surface with the pile lower end connecting steel plate), and both are integrated by welding. As a result, the excavating blade of the present invention can be attached to the lower end of the existing pile P. The hollow top frame 1 and the hollow bottom frame 2 are also connected to each other by appropriate members or metal fittings for mutual reinforcement (provided that they do not interfere with the later-described horizontal movement of the entrance / exit blade 4). If they are integrated, they will be convenient in terms of strength as an excavating blade.

The shaft member 3 is mounted on the hollow upper frame 1 and the hollow lower frame 2 by firmly integrating the upper and lower ends thereof by welding or other means. The blade tip portion 42 side ensures stable rotation in a horizontal plane within a regulated range, and the blade tip portion 42 projects from the outer periphery of the hollowed lower frame 2 to clean the surrounding ground. It functions so as not to be disengaged or deformed by the impact force received during excavation. Therefore, in order to achieve those functions, the material of the shaft member 3, the cross-sectional dimension, the hollow upper frame 1 and the hollow hollow The strength of connection to frame 2 and economic efficiency should be thoroughly examined in advance.

The blade 4 has a shaft mounting portion 41 attached to the shaft member 3 at one end and a blade tip portion 42 at the other end.
When it is mounted on the shaft member 3 and is used as the excavating blade of the present invention at the lower end of the regulating pile P, the exiting blade 4 is hollowed out when the precast pile P is gently pushed. Only when the precast piles P are rotated in any direction after reaching the support layer, the gravel scattered around the upper frame 1 and the hollowed-out lower frame 2 are housed in a posture in which they do not project to the outside. Due to the resistance, the cutting edge portion 42 is forced to have the hollow upper frame 1
It also functions so as to project outward from the outer periphery of the hollowed-out lower frame 2.

In connection with the drilling blade of the present invention based on the above-mentioned structure, the present invention also includes the following structures.

[Other related inventions] That is, the hollowed upper frame 1 corresponding to the diameter of the precast pile P and the hollowed lower frame 2 arranged below the hollowed upper frame 1 at a predetermined interval are used as supporting portions. With respect to the plurality of attached shaft members 3, one end side is the shaft mounting portion 41, and the other end side is the cutting edge portion 4.
The loading / unloading blade 4 formed in 2 is axially rotatably supported by the shaft mounting portion 41 in the horizontal plane, and the rotary range in the horizontal plane is
While restricting from a position that is substantially accommodated in the outer peripheral surface of the prefabricated pile P to be attached to a position in which the outer peripheral surface intersects and the blade edge portion 42 projects from the outer peripheral surface of the prefabricated pile P, the hollow frame Two
On the lower surface, a plurality of leading blades 5, 5, ... are formed by restricting and projecting so that they are gradually shifted inward from the outermost position in plan view. The bottom end of the pile P is a stationary type excavating blade.

The excavating blade of the present invention includes all the constitutions of the excavating blade of the basic invention described above, and a portion where a plurality of leading blades 5 are projectingly provided on the lower surface of the hollowed-out lower frame 2 thereof. This embodiment has a new structure, and the embodiment shown in each drawing is based on this example. The shape of the leading blade 5 is not particularly limited, and the support layer located at the lower end of the prefabricated pile P can be excavated to some extent, and the excavated gravel can be removed from the injected cement milk. Of course, any structure can be adopted as long as it can be stirred and mixed. In the following, one of the most typical embodiments embodying the other related invention will be described.

[0013]

Embodiment 1 As shown in the whole perspective view of the hollow bottom frame 2 of FIG. 1, the horizontal sectional view of FIG. 2, the front view of FIG. 3, and the bottom view of FIG. Is a hollow upper frame 1 made of thick steel plate formed in accordance with the diameter of the prefabricated pile P, and a hollow hollow lower frame 2 made of thick steel plate arranged at a predetermined distance below the hollow upper frame 1. Between the three insertion / removal blades 4, 4 and 4 formed by inserting the shaft member 3 into the shaft mounting portion 41 formed on one end side, are arranged so as to be evenly distributed in a plane arrangement. ，
Each of the upper and lower ends of 3 and 3 is provided with a hollow upper frame 1 lower surface and a hollow lower frame 2
By integrating with the upper surface, the respective blades 4, 4,
4 is rotatably mounted on the shaft mounting portions 41, 41, 41 so as to be rotatable in the horizontal plane, and the rotation range in the horizontal plane is the outer peripheral surface of the prefabricated pile P to be mounted, that is, the hollow punching. At a predetermined position where the outer peripheral surface intersects with the frame 1 and the hollowed lower frame 2 so as to intersect with each other, and the blade edge portion 42 projects from the outer peripheral surface of the existing pile P, the outer periphery of the shaft mounting portion 41 and the blade edge Part 42
It is regulated by the regulation piece 43 provided on the opposite side to the projecting side, and further rotation is prevented. On the other hand, on the lower surface of the hollowed-out lower frame 2, a plurality of leading blades 5, 5, ... are projected and regulated so that they are gradually displaced inward from the outermost position in plan view. By forming it, it is used as a lower end stationary type excavating blade of a pre-fabricated pile P with a medium excavation method.

In this embodiment, as a means for restricting the protruding state of the retractable blade 4 to a predetermined position, the restricting piece 43 also serves as a reinforcement for the upper hollow frame 1 and the lower hollow frame 2, respectively. This is realized by contacting the end of the inner frame 6 integrated inside the hollowed-out portion. However, the middle frame 6,
6 and 6 are not indispensable configurations of the present invention, and when these are omitted, contact projections dedicated to the restriction piece 43 may be formed at predetermined positions inside the frames 1 and 2, Further, the restricting piece 43 itself is omitted, and the middle portion between the shaft mounting portion 41 and the blade tip portion 42 when the inserting / removing blade 4 is rotated is set to each of the frames 1 and 2.
It is possible to employ an appropriate means capable of realizing a restricted rotation within a predetermined range in the horizontal plane, such as blocking by a restriction projection or a restriction rod provided inside the.

As shown in the bottom view of FIG. 4, the leading blades 5 are not only arranged in a uniform distribution, but the protruding positions of the individual leading blades 5, 5, ... The frame 2 should be projected so as to be regulated so that the position from the virtual center point is gradually shifted from the outermost one toward the center. In this example,
The insert / exit blade 4 is configured such that the blade edge portion 42 made of a thick steel plate is welded to and integrated with the side surface of the thick short steel pipe of the shaft mounting portion 41, and the integrated structure is reinforced by the reinforcing web 44. The leading blade 5 is made of a thick steel plate, but it is of course possible to integrally form them as a casting, and those having appropriate materials and structures in consideration of both strength and economy. Can be

[0016]

[Operation] First, with respect to the cap material P1 arranged at the lower end of the prefabricated pile (the prefabricated pile located at the lowermost position and reaching the support layer G1) P to be embedded first, the excavating blade of the present invention is used. In the above, the upper surface of the hollowed upper frame 1 is brought into contact with each other, and then the both edges are welded and integrated. Then, as before, the Nakahori machine (not shown) with the earth auger inserted through the hollow part
It is built almost vertically on the ground, and its upper end is connected to the excavation mechanism of the Nakahori machine, and the ground auger is rotated to dig down the ground G by rotating the earth auger. While rotating in the direction opposite to the rotation direction, the pre-excavated bit P is used as a guide, and the pre-existing pile P is grounded by the weight of the pre-existing pile P and the weight of the excavation mechanism.
Gradually push it into place.

The prefabricated pile P having the digging blade of the present invention integrated at the tip is driven to a predetermined depth, and when the tip reaches a predetermined height from the ground, the second prefabricated pile P is attached to both cap materials. After P1, P1 are welded together, integrated and replenished, by the same process as above, the existing piles P, P that have been replenished and integrated into one are further pushed deeper. Precast piles P that have been replenished to the specified length by repeating this process,
P, ... Is embedded up to the designed predetermined depth of the support layer G1. Precast piles P, P, which have been added to form a single pile
At the time of rotation of the embedding process of ……, the excavating blade of the present invention mounted on the most distal pile P has its moving blades 1, 1 ,.
Since it does not oppose rotation, it stays in a stable state along the outer peripheral surface of the prefabricated pile P and does not hinder the embedding process.

After that, the rotation of the earth auger is stopped, and the existing piles P, P ,. The excavating blade of the present invention at the tip of the pile has the blade tips 42, 42 of the inlet and outlet blades 4, 4 ,.
, The sand and gravel that had been excavated by the bit and scattered around the area entered the blades 4, 4, ..., and the blades 4, 4, ... resisted the shaft members 3, 3, .... It is rotated around the center, and the cutting edge portions 42, 42, ... Are drawn out in a direction so as to intersect with the outer circumference of the pile on the plane, and at the maximum position of the regulated rotation (the horizontal sectional view of FIG. 2). And FIG.
(The place indicated by the two-dot chain line in the bottom view of Fig. 1) rotates and stops, and as a result, further rotation is blocked, and as a result, the existing piles P, P, ... are forcibly rotated in the same direction. Then, due to the protruding and retracting blades 4, 4, ..., the ground G located outside the outer circumference of the existing pile P, which could not be excavated by the bit at the tip of the earth auger, is moved in and out.
By scraping in a range corresponding to the projecting dimension, a bulb-shaped bulged hole can be formed at the bottom of the pile hole and around the support layer, as shown in the sectional view of FIG.

After that, cement milk is poured into the hollow portions of the prefabricated piles P, P, ... After pulling up the earth auger, and the prefabricated piles P, P ,. Rotate in the same direction as it stops and stir to mix the gravel accumulated at the bottom of the pile hole sufficiently with the cement milk, wait for the cement milk to solidify, and then bury it at this point. The entry process is completed. as a result,
The excavating blade of the present invention is left in the solidified cement milk at the tip of the prefabricated piles P, P, ... with the projecting and retracting blades 4, 4, ... It will play a role.

[0020]

[Effects] Therefore, according to the bottom edge stationary type excavating blade of the precast pile of the present invention, which is a so-called disposable type excavating blade which is not premised on repeated use, the structure itself is extremely convenient. Since it can be made into a simple one and can be made inexpensive, it is profitable even as a disposable type, and like the one with the auger tip bit that can be expanded as before. , The expansion bits do not return to their original state during extraction, there is no possibility of suffering great economic and efficiency damage due to being unable to extract, and it is possible to form a reliable bulb part at the bottom of the pile hole, Stirring and mixing of sand and gravel into the cement milk is ensured, and after the cement milk is solidified, the blades 4, 4, which remain protruding from the outer periphery of the pile.
However, it plays the role of an anchor and strengthens the integration of the existing piles P, P, ... with the bulb-shaped cement milk portion, and the pile strength supported by the support layer G1 is always ensured to be higher than the design strength. In comparison with the conventional one, the drilling blade of the present invention achieves its purpose, in terms of function, economic efficiency, and work efficiency. It is capable of exerting an excellent effect that does not become.

Particularly, in the case where these drilling blades are made of thick steel plates, such as the one representative of the present invention shown in the embodiment, it can be easily commercialized anywhere and at an extremely low cost. It can be provided, and further, the leading blades 5, 5, ... Are provided on the lower surface of the hollow bottom frame 2.
In the case where the protrusion is formed, not only can the hole be expanded toward the bottom of the pile hole, but the function of evenly stirring and mixing the gravel excavated in them with cement milk is strengthened, and the strength of the bulb is improved. It has the advantageous feature of being stable. As described above, the present invention is extremely effective in efficiently carrying out pile driving work that is frequently carried out in various places in urban areas, and its structure is simple. Since it is easy to manufacture, it can be provided at a low price, and in terms of handling operability, it is simple, and it is expected that it will be highly evaluated by people engaged in civil engineering work.

[Brief description of drawings]

The drawings show an embodiment representative of the present invention.

FIG. 1 is an overall perspective view of a lower end stationary type excavating blade of a precast pile of the present invention, which is formed from a lower frame side.

FIG. 2 is a horizontal sectional view of the same as above.

FIG. 3 is a front view of the same.

FIG. 4 is a bottom view of the same.

FIG. 5 is a vertical cross-sectional view showing a usage state, with some parts omitted.

[Explanation of symbols]

 1 Hollow-out upper frame 2 Hollow-out lower frame 3 Shaft material 4 Entry / exit blade 41 Coaxial mounting part 42 Same blade tip part 43 Same regulation piece 44 Same reinforcing web 5 Leading blade 6 Middle frame G Ground G1 Same support layer P Prefabricated pile P1 Same connection cap

Claims (2)

[Claims] 1. A plurality of shaft members attached with a hollow upper frame corresponding to the diameter of a precast pile and a hollow lower frame arranged at a predetermined distance below the hollow upper frame as supporting portions. On the other hand, the insertion / removal blade having one end on the shaft mount and the other end on the blade tip should be mounted on the shaft mount so as to be rotatable in the horizontal plane, and the rotation range in the horizontal plane should be attached. Middle excavation method that regulates from a position that is almost set within the outer peripheral surface of the precast pile to a position where the cutting edge intersects the outer peripheral surface and the cutting edge projects from the outer peripheral surface of the precast pile. .. 2. A plurality of shaft members attached with a hollow upper frame corresponding to the diameter of the precast pile and a hollow lower frame arranged at a predetermined distance below the hollow upper frame as supporting portions. On the other hand, the insertion / removal blade having one end on the shaft mount and the other end on the blade tip should be mounted on the shaft mount so as to be rotatable in the horizontal plane, and the rotation range in the horizontal plane should be attached. While controlling from the position where it is almost accommodated in the outer peripheral surface of the precast pile to the position where it intersects with the outer peripheral surface and the cutting edge part protrudes from the outer peripheral surface of the precast pile, multiple leading blades are provided on the lower surface of the hollowed bottom frame. However, in terms of its planar arrangement, the lower end stationary excavating blade of the intermediate excavation method existing pile, which is formed so as to be regulated so as to be gradually shifted inward from the outermost position.