JPH0841870A - Method of connection precast concrete pile - Google Patents

Abstract

PURPOSE:To facilitate a method of connecting precast concrete piles by combining a lower pile used for a knot-pile having the same diameter of the upper end as that of a knot section with an upper pile used for a straight pile having the same diameter as that of the knot section to connect. CONSTITUTION:A pile hole 3 is excavated up to specific depth with an excavator while injecting excavation liquid in the ground. After the excavator is pulled out while turning it, cement milk is poured into the pile hole 3. After that, a knot pile 1 reinforced with a diameter widening reinforced bar 10 is inserted into the pile hole 3. At that time, the lower end plate 6 of a straight pile 2 having the same diameter as that of a knot section of the upper end plate 5 of the knot pile 1 is welded to the upper end plate 5 of the knot pile 1 to connect the straight pile 2 to the upper part of the knot pile 1, and insertion is made again to install the whole connection pile. At that time, the cement milk injected into the front end of the pile hole 3 is raised in a gap between the connection pile and pile hole wall by insertion of the connection pile, and the gap is filled therewith. The cement milk is mixed with earth remaining in the pile hole 3 or solid part in the excavation liquid to form a cured- cement body 4, and the knot pile 1, straight pile 2 and ground are monolithically formed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for connecting ready-made concrete piles to construct a long ready-made concrete pile by connecting two or more ready-made concrete piles having different performances (shapes) in deep soft ground. .

[0002]

2. Description of the Related Art When driving ready-made concrete piles in deep soft ground where a soft stratum has accumulated more than 15 m, it is necessary to construct two or more piles in order to construct a joint pile due to the length. is there. As one of the construction of this connection pile, not only the transmission of the vertical load to the ground, but also the node pile is used as the lower pile of the part expected to be supported by the ground, and the transmission of the vertical load to the ground is mainly expected. However, there are cases where straight piles are used as the upper piles where the ground is hardly expected to support them.

When connecting two lower piles and upper piles having different performances (shapes), as shown in FIG. 2, a node pile whose upper end diameter is the same as the shaft diameter is used as the lower pile, and Generally, a straight pile having the same diameter as the shank diameter is used as the upper pile, and the upper end plate of the node pile and the lower end plate of the straight pile are welded.

[0004]

With the combination of the lower pile and the upper pile of the conventional method, the cement milk injection method, which is a typical ready-made concrete pile method (the ground is excavated to a predetermined depth while injecting the drilling fluid, is used). To form a drill hole, insert and install ready-made concrete piles with cement milk injected into the drill holes, and fix the ready-made concrete piles to the ground around the drill hole by solidifying the cement milk, drilling liquid, and sediment mixture. When the construction method is adopted, since the drill hole having a diameter larger than the node diameter of the node pile is formed, the gap between the upper pile and the hole wall becomes unnecessarily large as shown in FIG. Not only does the amount of milk injected increase, but the quality of the solidified solidified material also increases, and the upper pile is not fixed to the borehole wall unevenly. further,
Since the upper pile has a small diameter, the bending moment and shear strength against lateral load on the head of the pile tend to be insufficient, and high quality high prestressed piles and specially reinforced piles are forced to be used.

Also, when adopting another typical off-the-shelf concrete pile construction method, since the node pile is driven in first and the pile hole having the diameter equal to the node diameter is formed, The fact that the gap between the upper pile and the wall of the pile hole becomes unnecessarily large is the same as above, and there is a drawback in that the density of the ballast or the like filling this gap becomes uneven. The problem that the upper pile has a small diameter is the same as above.

The above-mentioned problems are exactly the same even when other construction methods are used.

[0007]

According to the present invention, there is provided a lower pile which is a node pile having an upper end diameter equal to a node diameter, and an upper pile which is a straight pile having the same diameter as the node diameter of the lower pile. By adopting the combination of, the problems of the conventional method are solved all at once.

That is, according to the present invention, in the connecting pile construction method in which the joint pile is a lower pile, the straight pile is an upper pile, and a connecting pile that connects the two is constructed in the ground, the diameter of the upper end portion of the joint pile is set to the joint portion. The same as the diameter, the diameter of the straight pile is made the same as the diameter of the node of the node pile, and the upper end plate of the node pile and the lower end plate of the straight pile are welded and connected. It depends on the pile construction method.

The knotted piles and straight piles used in the present invention are manufactured by an ordinary centrifugal compaction method, and may be either reinforced concrete piles or prestressed reinforced concrete piles. From the viewpoint of strength, it is preferable to use prestressed reinforced concrete piles. The tip may be either an open type or a closed type, but it is preferable to use a closed tip type as the node pile which is the lower pile. Since the upper end of the knot pile is made to have the same diameter as the knot part in a relatively long range, it is desirable to arrange the expanded part reinforcing bar in addition to the shaft reinforcing bar.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings.

FIG. 1 is an elevational sectional view showing a connecting pile constructed by the method of the present invention, (a) is an overall view, and (b) is an enlarged view of a connecting portion. The present invention will be described according to FIG. 1 including a construction procedure. In this embodiment, the cement milk injection method is adopted as the construction method.

(1) The ground is excavated to a predetermined depth by an ordinary excavator while injecting the drilling fluid prepared for the cement milk injection method, and the pile hole 3 is excavated.

(2) While raising the excavator, a predetermined amount of cement milk is injected into the tip of the pile hole 3. The excavator continues to rotate even during pulling up, and well mixes the excavated liquid with the excavated liquid that has not been exhausted to the outside of the pile hole 3 by stirring.

(3) After the excavator is pulled up, the diameter of the upper end is expanded in the pile hole 3 so as to be the same as the diameter of the node in a relatively long range, and the expanded diameter is reinforced by the expanded diameter reinforcing bar 10. The node pile 1, which is the closed tip type prestressed reinforced concrete pile, is inserted and installed. When the node pile 1 is considerably inserted, the lower end plate 6 of the straight pile 2 having the same diameter as the node diameter of the node pile 1 is welded to the upper end plate 5 of the node pile 1 to form the straight pile 2 on the node pile 1. Connect and restart the insertion and insert the entire connecting pile. As the straight pile 2, an open-ended prestressed reinforced concrete pile was used.

(4) The cement milk injected into the tip end of the pile hole 3 rises in the gap between the pile and the wall of the pile as the pile is inserted, and fills this gap. The cement milk forms a hardened cement body 4 together with the soil and the solid content in the drilling fluid that cannot be completely discharged to the outside of the pile hole 3, and integrates the node pile 1, the straight pile 2 and the ground. After that, the pile head treatment is performed as usual to complete the construction of the connecting pile.

The gap between the straight pile 2 and the pile hole 3 is small, and the quality of the cement hardened body 4 formed in this gap is uniform and there is little variation.

When the node pile 1 and the straight pile 2 are connected according to the conventional method and the connection pile is constructed by the same cement milk injection method as in this embodiment, the straight pile 2 and the pile hole are formed as shown in FIG. 3 has a large gap, and the quality of the cement hardened body 4 formed in this gap is non-uniform and varies greatly.

[0018]

Since the diameter of the upper pile connected to the lower pile having the same diameter is larger than that of the conventional method, the gap between the upper pile and the pile hole becomes smaller, and the pile fixing material formed in this gap becomes smaller. The quality is uniform and there is little variation. Further, since the upper pile has a large diameter, bending moment and shear strength against lateral load of the pile head will not be insufficient, and it is possible to use ready-made concrete piles of normal quality.

[Brief description of drawings]

FIG. 1 is a vertical sectional view showing a connecting pile constructed by a method of the present invention, (a) is an overall view, and (b) is an enlarged view of a connecting portion.

FIG. 2 is a vertical sectional view showing a connecting pile constructed by a conventional method.

[Explanation of symbols]

1 ... Knot pile (lower pile), 2 ... Straight pile (upper pile), 3
..Pile holes, 4. Cement hardening bodies, 5 ..
6 ・ ・ Straight pile bottom plate, 7 ・ ・ Knot pile node, 8 ・ ・ Knot pile shaft, 9 ・ ・ PC steel rod, 10 ・ ・ Knot pile expanded part reinforcement.

Claims (1)

[Claims] 1. A ready-made concrete pile having no nodes, which is a ready-made concrete pile with nodes provided with nodes having a diameter larger than the shaft diameter at appropriate intervals in the longitudinal direction (hereinafter referred to as "node pile"). (Hereinafter referred to as straight pile) is the upper pile,
In the connecting pile method of constructing a connecting pile that connects the two in the ground, the diameter of the upper end of the node pile is the same as the node diameter, and the diameter of the straight pile is the same as the node diameter of the node pile. A connecting pile method for ready-made concrete piles, characterized in that the upper end plate of the pile and the lower end plate of the straight pile are welded and connected.