JP2576755B2 - Pile head treatment method for ready-made prestressed concrete pile - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pile head structure for a precast prestressed concrete pile to be cast and a pile head treatment method after the precast prestressed concrete pile is cast.

[0002]

2. Description of the Related Art Conventionally, precast prestressed concrete piles are driven by a driving method or an embedding method. After the driving of the pile head, the inside of the pile is cleaned to about twice the diameter of the pile, and the basket is placed there. This is done by arranging rebar and casting concrete to integrate the pile with the foundation. Laitance due to centrifugal molding adheres to the inner surface of the ready-made prestressed concrete pile in a layered form and cannot be easily removed even by cleaning, thus reducing the adhesion performance with the concrete to be poured. In particular, in the embedding method, an overflowing drilling solution (which later becomes a solid) is often put inside the pile, and the solid cannot be completely removed even by cleaning. Due to the overlap of several causes, the adhesion performance of the inner surface of the pile to the concrete is reduced, but the concrete is usually poured as it is.

[0003]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to improve the adhesion performance between the inner surface of a pile head and concrete.

[0004]

According to a first aspect of the present invention, a plurality of cotter plates are buried along the circumference of the pile inner surface, and a plurality of cotter plate groups are buried in the pile axis direction. A plurality of cotter plates in the group of cotter plates are prepared by placing a pre-stressed concrete pile having a cut in the center at a predetermined position, then cleaning the inside of the pile head to a predetermined depth, and bottling the inside of the pile head. A pre-stressed concrete pile, characterized by inserting a cage rebar integrated with an iron plate, fitting the end of the bottom iron plate into the cut in the center of the cotter plate, fixing it, and then pouring concrete into the pile head. It is a pile head treatment method.

[0005] The first invention can be divided into an improvement on the ready-made prestressed concrete pile side and an improvement on the cage rebar side. First, the improvement of the ready-made prestressed concrete pile side is to bury a plurality of cotter plates as a group along the circumference of the pile inner surface, install a plurality of cotter plate groups in the pile axis direction, and furthermore, The cotter plate group has a plurality of cotter plates in which a notch is provided at the center. And the improvement of the cage rebar side,
The bottom iron plate is fixed to the bottom by welding etc., the shape of the bottom iron plate can be inserted inside the pile, and when inserted to the predetermined position and rotated in the circumferential direction, the end is the center of the lowermost cotter plate This is a point that has a shape that can be fitted into the cut of the portion. Together with the improvement on both sides, the cage rebar is firmly restrained inside the pile, and the adhesion of the post-cast concrete to the inner surface of the pile head is greatly improved by the cotter plate. As a result, the anchoring length of the cage rebar can be reduced to the same extent as the pile diameter, and as a secondary effect, the volume and area of the cleaning section inside the pile head can be reduced. Further, by integrating the bottom iron plate with the cage rebar, a bottom formwork at the time of casting concrete is not required.

A second aspect of the present invention relates to an improvement of a precast prestressed concrete pile, in which, besides the cotter plate, a stop plate is buried at a position substantially at the same height as the lowermost cotter plate group. . By providing this stop plate, when inserting the cage rebar integrated with the bottom iron plate into the inside of the pile, the end of the bottom iron plate is left standing on this stop plate, and the cage rebar is positioned below it Is not inserted, and the work of inserting the cage rebar is simplified.

[0007] The third invention also relates to an improvement of the ready-made prestressed concrete pile side, in which the entire surface of the cotter plate buried portion on the inner surface of the pile head (the surface that comes in contact with the post-cast concrete) is covered with a protective sheet. This is where concrete piles are cast. As described above, the inside of the pile head after casting is clogged with earth and sand, solidified drilling solution, etc., and these are discharged and cleaned, and then concrete is poured, but in the present invention, the inside of the pile head is There are many places where the cotter plate is buried and it is difficult to clean. Therefore, contamination of the inner surface of the pile head is prevented, and the cleaning operation is simplified.

[0008]

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

FIG. 1 (a) is a vertical sectional view showing a state in which a cage rebar is inserted into a pile head of a pre-stressed concrete pile used in the present invention and left standing, and FIG. 1 (b) is a pre-stressed concrete. It is a sectional elevational view showing the state where the pile head inner surface of the pile was covered with the protection sheet.

FIG. 2A is a view taken in the direction of arrows AA in FIG. 1A, FIG. 2B is a view taken in the direction of arrows BB in FIG.
FIG. 2C is a plan view of the bottom iron plate. (In addition, the cage rebar is omitted in the arrow view.) First, the pile head of the ready-made prestressed concrete pile will be described.

On the inner surface of a pre-stressed concrete pile 1, three groups of cotter plates 2 are buried in the upper, middle and lower tiers with eight cotter plates 2 as one group. Four of the eight lower cotter plates 2 are cotter plate / bottom iron plate holding plates 5 and have a cut 10 at the center. The number of cotter plates 2 in one group,
The number of groups and how many of the lowermost cotter plates 2 are used as the cotter plate / bottom iron plate holding plate 5 are appropriately determined according to the diameter of the pre-stressed concrete pile 1 and the like. In order to facilitate the work of inserting the cage rebar, it is preferable to embed several stop plates 6 at predetermined positions as shown in FIG. It is preferable to increase the arc length in the direction. These buried plates are fixed to reinforcing bars (not shown) of the pre-stressed concrete pile 1 at the time of manufacturing the pre-stressed concrete pile 1 by welding or the like. FIG. 1 (b) shows an example in which the inner surface of the pile head of the ready-made prestressed concrete pile is covered with the protective sheet 8, but this protective sheet 8 may be formed by directly bonding the cylindrical protective sheet 8 to the inner surface of the pile head. It is easier to mount the annular plate 9 on both ends of the cylindrical protective sheet 8 in advance, and to attach the annular plate 9 to the inner surface of the pile head by bonding or the like.

Next, the cage rebar bottom will be described.

A bottom iron plate 4 is welded to the bottom of the cage reinforcing bar 3. As shown in FIG. 2C, a number of cuts 7 corresponding to the number of the groups of the cotter plates 2 are provided at the peripheral end of the bottom iron plate 4, and the shape of the cuts 7 is a cross section of the cotter plate 2. The cage rebar is similar to the shape, and can be inserted inside the pile head without disturbing the cotter plate 2 with the cage rebar integrated with the bottom iron plate 4. The cage rebar is inserted to a predetermined position inside the pile head, is rotated in the circumferential direction, and its end is fitted into the notch 10 of the cotter plate / bottom iron plate holding plate 5 to be fixed to the pile 1.

The construction sequence of the present invention will be described with reference to FIG.

(1) Soil, solidified matter and the like inside the pile head of the ready-made prestressed concrete pile 1 are discharged. If a protective sheet is used, remove the protective sheet. Clean the inside of the pile head. (FIG. 3 (a)) (2) The cage reinforcing bar 3 is suspended and inserted into the inside of the head of the pre-stressed concrete pile 1. (FIG. 3
(B)) (3) When the cage rebar 3 reaches a predetermined position, the cage rebar 3
Is rotated in the circumferential direction to fit the end of the bottom iron plate 4 into the notch 10 of the cotter plate / bottom iron plate holding plate 5.
(FIG. 3 (c)) (4) Concrete is poured into the pile head of the ready-made prestressed concrete pile 1 to complete the work. (FIG. 3
(D))

[0016]

According to the present invention, the adhesion performance of the post-cast concrete to the inner surface of the pile head is improved, and the anchoring length of the cage rebar can be reduced to about the same as the diameter of the pile. The volume and area of the cleaning unit can be reduced.
Furthermore, the bottom formwork at the time of concrete casting can be eliminated.

[Brief description of the drawings]

FIG. 1 is a vertical sectional view of a pile head and a cage rebar of a ready-made prestressed concrete pile used in the present invention,
(A) shows a state in which a cage rebar is inserted into the pile head of the ready-made prestressed concrete pile and allowed to stand, and (b) shows a state in which the inner surface of the pile head of the ready-made prestressed concrete pile is covered with a protective sheet.

FIG. 2A is a view taken in the direction of arrows AA in FIG. 1A;
(B) is a BB view of FIG. 1 (a), and (c) is a plan view of the bottom iron plate.

FIG. 3 is an elevational sectional view showing a construction order of the present invention.

[Explanation of symbols]

1. Precast prestressed concrete piles, 2. Cotter plates, 3. Basket reinforcement, 4. Bottom iron plate, 5.
Cotter plate and bottom iron plate holding plate, 6 ... stop plate, 7 ... bottom iron plate cut, 8 ... protection sheet, 9
..Circular plate, 10 ... Cotter plate and bottom iron plate holding plate notch

Claims (3)

(57) [Claims] 1. A plurality of cotter plates are buried along a circumference of an inner surface of a pile, a plurality of cotter plates are buried in a pile axis direction, and a plurality of cotter plates in a lowermost cotter plate group are buried. After casting a ready-made prestressed concrete pile with a notch in the center at a predetermined position, clean the inside of the pile head to a predetermined depth, insert a cage steel bar integrated with the bottom iron plate inside the pile head, Pile head treatment method for ready-made prestressed concrete piles, which is characterized in that the end face of the bottom iron plate is fitted and fixed in the notch in the center of the cotter plate and then concrete is poured into the pile head 2. A pre-stressed concrete pile in which a stop plate for stopping a bottom iron plate is added to a cotter plate at a position substantially at the same height as the lowermost cotter plate group to bury the cotter plate. Head treatment method for ready-made prestressed concrete piles 3. A pre-stressed concrete pile in which a cotter plate buried portion on the inner surface of a pile head is entirely covered with a protective sheet is cast into a predetermined position, and the protective sheet is removed before inserting a cage rebar. Pile head treatment method for the ready-made prestressed concrete pile according to claim 1 or 2.