JP2006118215A - Construction method of enlarged head pile - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a construction method for easily constructing an enlarged head pile from a precast pile by a preboring method. <P>SOLUTION: In this construction method, an excavated hole is formed beforehand by the preboring method, and the enlarged head pile formed of the precast pile is buried in the excavated hole. As an excavating rod for excavating the excavated hole, the projecting quantity of an agitation blade 8 provided at a rod portion corresponding to the height of an excavated hole part where the enlarged head pile is disposed, is set relatively large. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for constructing a head-expanded pile, which is a ready-made pile with an expanded head, by a pre-boring method.

  In the pre-boring method, a construction method for expanding the diameter of the middle or upper part of the excavation hole formed by the excavation rod includes, for example, those described in Patent Document 1 and Patent Document 2. In these construction methods, after excavating to a target depth with an excavating rod provided with an enlarged bit at the tip, an enlarged excavation is performed at the lowermost part of the excavation hole with the enlarged bit to form an enlarged rooted portion. Thereafter, the drill rod is pulled out.

In this drawing work, in the above-mentioned patent document, when the expansion bit provided at the tip of the excavation rod is pulled out to a depth that expands the diameter, the excavation rod is reversely rotated to expand the expansion bit and excavate, Increase the diameter of the drilling hole in that part. That is, with the same idea as the diameter expansion work of the enlarged root part, for example, the diameter expansion work is performed on the upper part with a diameter expansion bit.
Here, normally, a plurality of excavation rod members are sequentially added to excavate to a predetermined depth, but the same type of excavation rod members are used as all excavation rod members used in one construction. That is, excavation rod members having the same diameter are sequentially added to form an excavation hole having a desired depth.

In addition, when the excavation rod is pulled out after excavation to the target depth, the extraction operation is performed while sequentially removing the upper excavation rod member, contrary to the excavation operation.
JP 62-253817 A JP 2003-119775 A

  Here, the excavation work by the excavation rod is performed by connecting the rotation drive unit 9 to the excavation rod member located at the uppermost portion and rotating the excavation rod by the torque from the rotation drive unit 9. For this reason, at the time of excavation, each time the excavation rod member is added, the connection operation between the upper part of the excavation rod member that has been newly positioned at the uppermost portion and the rotation drive unit 9 is performed. When the excavation rod is pulled out, no excavation is required. Therefore, when the excavation rod members are sequentially removed, the upper portion of the excavation rod member, which is newly positioned at the uppermost end, and the rotation drive unit 9 It is not necessary to perform the connecting work.

On the other hand, in the above conventional construction method, after excavating once to the target depth, the excavation rod is pulled out while sequentially removing the excavation rod members, and when the enlarged bit at the bottom reaches the upper part of the excavation hole, it is renewed. As a result of the necessity of performing excavation work, when the upper part of the excavation hole is enlarged and excavated, the connection work between the upper part of the excavation rod and the rotary drive unit 9 is required at that time.
In addition, the expansion drilling at the upper part is different from the expansion drilling at the root consolidation part, and is performed in a soft part once the drilling is completed to a predetermined diameter. There is a risk that the opening and closing of the enlarged bit may not be successful because the reaction force cannot be taken well.
Furthermore, in order to sufficiently mix and agitate the enlarged excavated portion with only the enlarged blade of the enlarged bit, many up-and-down repetitions are required and the construction time becomes longer.
This invention pays attention to the above points, and makes it a subject to be able to construct the head-expansion pile which consists of ready-made piles easily by a pre-boring method.

In order to solve the above-mentioned problems, the invention described in claim 1 of the present invention forms a drilling hole by performing preboring to a predetermined depth with a drilling rod, and the diameter of the head is relative to the drilling hole. It is a construction method of a head-expanded pile that builds a head-expanded pile made of an expanded ready-made pile,
In the drilling rod, the stirring blade of the upper drilling rod portion that expands the drilling hole at the buried position of the enlarged head of the heading pile protrudes from the stirring blade of the lower drilling rod portion. It is characterized by a long length.

Next, the invention described in claim 2 is based on the configuration described in claim 1 and includes at least a stirring blade of the lower excavation rod portion in the stirring blade located at the lowermost portion of the upper excavation rod portion. Also, a drilling blade that protrudes downward is provided for the portion that protrudes outward.
Next, the invention described in claim 3 is a head expansion that performs excavation or stirring with respect to the configuration described in claim 1 or claim 2 while injecting drilling fluid or solidifying agent into the drilling hole from the tip of the drilling rod. In the pile construction method,
Drilling or stirring is performed while injecting drilling fluid or a solidifying agent into the drilling hole from the upper drilling rod.

  ADVANTAGE OF THE INVENTION According to this invention, it can be simply and efficiently constructed the excavation hole for building the head-expansion pile which consists of ready-made piles using the equipment used by normal construction.

Next, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a diagram showing a construction procedure according to the present embodiment.
The excavation rod 3 used in the construction of the present embodiment is composed of a lower first excavation rod member 1 and a second excavation rod member 2 connected to the upper side thereof (see FIG. 1C and the like). ).
The first excavation rod member 1 is provided with an excavation bit 4 as an excavation blade protruding downward from the distal end with respect to the distal end, and a known enlarged bit 5 is provided at the distal end. Furthermore, a plurality of stirring blades 6 called agitators are provided on the side surface of the first excavation rod member 1 along the axial direction. A drilling rod member is used in which the amount of protrusion of the stirring blade 6 is slightly larger than the small diameter portion of the expanded pile.

The tip of the first excavation rod member 1 is provided with an ejection hole 12 through which liquid can be ejected, as in the prior art, and the drilling fluid and solidifying agent are injected into the excavation hole 10 from the ejection hole 12. It is possible. As the solidifying agent, cement milk is most often used, so the case where cement milk is used will be described.
Moreover, the 2nd excavation rod member 2 is provided with the some stirring blades 7 and 8 along the axial direction with respect to the side surface. Of the stirring blades 7 and 8 of the second excavation rod member 2, when the tip of the first excavation rod member 1 is excavated to a target depth, the position where the head extension of the head extension pile is buried (expanded excavation for head extension) As shown in FIG. 2, the upper agitating blade 8 that should be positioned at a position) is set to have a protruding amount larger than that of the lower agitating blade 7, and The diameter is set to be slightly larger than the diameter. The amount of protrusion of the lower stirring blade 7 is the same as the amount of protrusion of the stirring blade 6 of the first excavation rod member 1. That is, the diameter of the second excavation rod member 2 is the same as that of the first excavation rod member 1 on the lower side, but the diameter on the upper side is larger than that of the first excavation rod member 1.

And the stirring blade 8 part by which the said protrusion amount was set large in the said 2nd excavation rod member 2 comprises an upper stirring rod part.
Here, in the following description, when the stirring blades are distinguished, the stirring blades 6 and 7 having a relatively small protruding amount are used as the small-diameter stirring blade, and the stirring blade 8 having a relatively large protruding amount is used as the large-diameter stirring blade. Call it.
Among the large-diameter agitating blades 8 set to have a large protruding amount, the large-diameter agitating blade 8 positioned at the lowermost part has an outer peripheral portion that projects beyond the lower-diameter agitating blade 7 as shown in FIG. On the other hand, one or more excavation bits 11 projecting downward are provided as excavation blades.

  Furthermore, an upper ejection hole 13 through which liquid can be ejected is also provided at a height position where the excavation bit 11 is provided in the second excavation rod member 2. The upper ejection hole 13 is provided in the shaft portion in the drawing, but may be opened on the outer peripheral side of the large-diameter stirring blade 8. In addition, the passage composed of a pipe or the like for supplying the liquid to the upper ejection hole 13 may share the passage for supplying the liquid to the ejection hole 12 of the first excavation rod member 1 or may be provided with a separate passage. May be. In addition, the said channel | path is provided so that the inside of the axial part of the excavation rod 3 may be extended up and down.

Next, a construction example of this embodiment will be described with reference to FIG.
First, as shown to Fig.1 (a), the upper part of the 1st excavation rod member 1 is connected with the rotation drive part 9 of an excavator, and excavation work is started. That is, as shown in FIG. 1B, the rotation drive unit 9 is driven to rotate the excavation rod 3, and excavation is performed with the excavation bit 4 at the tip. At this time, excavation is performed while cement milk is injected into the excavation hole 10 from the ejection hole 12 at the tip of the excavation rod 4.

When the first excavation rod member 1 excavates to a predetermined depth, the second excavation rod member 2 is connected to the upper portion of the first excavation rod member 1, and the rotation drive unit 9 is connected to the upper portion of the second excavation rod member 2. Are connected again to continue excavation (see FIG. 1C).
At this time, since the bit 11 is provided on the outer peripheral side of the large-diameter agitating blade 8 positioned at the lowermost part, the outer peripheral portion of the previously excavated hole is expanded and excavated by the bit 11. At this time, cement milk is also injected into the excavation hole 10 from the position of the second excavation rod member 2 so that only the necessary amount of cement milk is supplied even at the upper part of the expanded excavation hole 10.

Next, as shown in FIG. 1 (d), the excavation rod is moved up and down by a predetermined stroke while rotating the excavation rod, and the injected cement milk and earth and sand are agitated and kneaded to form a soil cement.
Subsequently, as shown in FIG. 1 (e), the diameter of the enlarged bit is increased and the lower end portion of the excavation hole 10 is expanded to form a rooted bulb portion 10 b.
When excavation is completed as described above, as shown in FIG. 1 (f), the excavation rod 1 is pulled out, and when the second excavation rod member 2 is completely pulled out to the ground, the second excavation rod member 2 is removed, and then Then, the first excavation rod member 1 is pulled out.
Subsequently, as shown in FIGS. 1 (g) and (h), the head-expanded pile 20 is sequentially built into the excavated hole 10 formed by its own weight subsidence and rotary subsidence. In addition, in this embodiment, the case where a head expansion pile consists of two ready-made piles 20A and 20B is illustrated.

As described above, in this embodiment, by expanding the protruding amount of the large-diameter agitating blade 8 provided on the upper side of the excavating rod 1, the upper enlarged excavation can be performed by one excavation.
Further, by providing the bit 11 also on the outer peripheral side of the large-diameter stirring blade 8, it is possible to efficiently perform the enlarged excavation above the excavation hole 10. Although the bit 11 need not be provided, it is necessary to increase the strength of the large-diameter agitating blade 8 and to make sure that expanded excavation is possible.

  Further, the upper portion of the excavation hole 10 is enlarged and excavated again by the large-diameter agitating blade 8 having a large protruding amount, but the upper diameter enlarged portion where the cement milk injected from the ejection hole 12 at the tip of the excavation rod is expanded and excavated. It is difficult to supply to 10a. Therefore, as it is, the proportion of the earth and sand is relatively increased, so that the quality of the mud is deteriorated and the strength at the upper part is deteriorated accordingly. In the present embodiment, the cement milk is also removed from the second excavation rod member 2. By ejecting, the cement milk of the newly expanded excavated soil can be properly supplied to the upper part of the excavation hole 10. As a result, even if the upper part of the excavation hole 10 is expanded and excavated, a sufficient quality soil cement can be secured.

  Here, when the cement milk is supplied to the lower ejection hole 12 and the upper ejection hole 13 through a common passage and the diameters of both the ejection holes 12 and 13 are the same, the lower soil As the pressure is higher, a larger amount is ejected from the upper ejection hole 13. In consideration of this, for example, the upper ejection hole 13 is made to have a relatively small diameter or a restriction so that an appropriate amount of cement milk is ejected from the ejection holes 12 and 13 according to the earth pressure. Thus, it is preferable to increase the resistance of the upper ejection hole 13 relative to the lower ejection hole 12.

  Moreover, in the said embodiment, although the case where the stirring blades 7 and 8 of the 2nd excavation rod member 2 differ by upper side and lower side is illustrated, it is not limited to this. For example, by using a drilling rod member having only a large-diameter stirring blade 8 having a large protruding amount and a plurality of drilling rod members having only a small-diameter stirring blade 6, 7, it is connected to the upper part and protrudes as a drilling rod member that performs expanded drilling You may make it use the excavation rod member only of the large diameter stirring blade 8 with a large quantity.

The head expansion pile 20 is not particularly limited as long as it is a ready-made pile, whether it is made of steel pipe or concrete.
Further, as the stirring blade of the excavating rod 3, a secondary stirring blade other than the above-mentioned small diameter and large diameter stirring blades 6, 7, 8 and having a smaller diameter than the stirring blades 6, 7, 8 are provided. In some cases.
Further, in the above embodiment, the explanation is made so that the cement milk at the time of excavation is injected into the excavation hole 10, but at the time of excavation, the excavating liquid such as water is injected, and the cement milk is injected at the time of mixing and stirring. May be.

It is a figure explaining the construction method of the head extension pile which concerns on embodiment based on this invention. It is a figure explaining a 2nd excavation rod member.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 1st excavation rod member 2 2nd excavation rod member 3 Excavation rod 4 Excavation bit 5 Expansion bit 6, 7 Small diameter agitating blade 8 Large diameter agitating blade 9 Rotation drive part 10 Excavation hole 10a Wide diameter part 10b Rooted bulb part 11 Bit 12 Lower jet hole 13 Upper jet hole 20 Expanded pile

Claims (3)

Pre-boring to a predetermined depth with a drilling rod to form a drilling hole, and with respect to the drilling hole, a method for constructing a head-expanded pile that builds a head-expanded pile made of a ready-made pile with an enlarged head diameter,
In the drilling rod, the stirring blade of the upper drilling rod portion that expands the drilling hole at the buried position of the enlarged head of the heading pile protrudes from the stirring blade of the lower drilling rod portion. A method for constructing an expanded pile characterized by its long length.   In the stirring blade located at the lowermost part of the upper excavation rod part, a drilling blade that protrudes downward is provided for at least a part of the lower excavation rod part that protrudes outward from the stirring blade. The construction method of the expansion pile according to claim 1. In the construction method of the expanded pile that performs excavation or stirring while injecting the drilling fluid or solidifying agent into the drilling hole from the tip of the drilling rod,
The method for constructing a head pile according to claim 1 or 2, wherein excavation or agitation is performed while injecting a drilling fluid or a solidifying agent into the drilling hole also from the upper excavation rod portion.

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