JPH08199565A - Pile head joint construction of cast-in-place concrete pile - Google Patents

Abstract

PURPOSE: To provide pile head joint construction of a cast-in-place concrete pile excellent in earthquake resistance which dispenses with the disposal of surplus soil as well as easy execution by reinforcing a pile head. CONSTITUTION: A steel pipe 1 is provided on the upper end of a soil cement column 6, and a steel pipe 2 of the lower part of a pile projected from the soil cement column 6 is inserted into the steel pipe 1 through a gap. The steel pipe 1 is filled with concrete 3 so that projections 9 and 10 provided on the steel pipes 1 and 2 are cut thereinto.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pile head joint structure for cast-in-place piles, and more particularly to a head joint structure for steel pipe piles made of soil cement.

[0002]

2. Description of the Related Art With respect to cast-in-place concrete piles, various structures have been proposed so far for reinforcing the pile heads in consideration of earthquake resistance. One of them is to connect a steel pipe to the head of a reinforced concrete pile, and the joining structure of this head steel pipe is a technique that has been implemented many times and has already been established.

For example, Japanese Patent Laid-Open No. 60-47117 proposes a composite pile in which a steel pipe having a projection on its inner surface is joined to the head of a concrete pile. This composite pile is shown in Figure 5.
As shown in FIG. 6 and FIG. 6, a steel pipe 18 having a projection on the inner peripheral surface is arranged at the head of the cast-in-place reinforced concrete pile 12 which is cast in the ground. It is to reinforce. Further, the steel pipe with the inner surface projection has a structure as shown in FIGS. 3 and 4 showing an embodiment of the present invention.

When constructing the reinforced concrete piles 12, the earth and sand are excavated to a predetermined depth, that is, the ground surface 1
After excavating the pile hole 21 from 9 to reach the support layer 20,
A steel pipe 18 with a protrusion is inserted into the upper portion of the pile hole 21, and then a casing pipe 13 made of the steel pipe 18 with a protrusion is inserted.
A reinforced basket 17 is inserted thereinto, and the pile hole 21 is filled with concrete 16. In the case of FIG. 5, the rebar cage 17 is not provided in the upper portion of the casing pipe 13, but only the concrete 16 is filled, while in the case of FIG. 6, the rebar cage 17 is also provided in the upper portion of the steel pipe 18 with protrusions. It is filled with concrete 16.

[0005]

DISCLOSURE OF INVENTION Problems to be Solved by the Invention In the structure of the composite pile of concrete and the steel pipe of the pile head as disclosed above,
A sufficient required bending resistance moment can be obtained without enlarging the pile head, and the amount of concrete can be reduced, so that the pile head can be economically reinforced. Further, by adopting the steel pipe 18 with the inner surface projection as the steel pipe of the pile head, it is possible to obtain an effect that the adhesion strength of the steel pipe 18 and the concrete 16 filled therein can be maintained high.

However, the above-mentioned composite pile structure has the following problems. That is, in the conventional structure, since the cast-in-place pile is a concrete composite pile, the reinforcing bar cage 17 is naturally used to reinforce the concrete 16, but is stronger than the reinforcing bar cage 17 in torsion and bending stress. If steel pipes can be used, it is possible to manufacture a composite pile in which the pile head is reinforced more strongly, but the conventional composite pile does not have such a structure. Further, in the conventional cast-in-place concrete pile, the pile hole 21 is excavated for concrete filling, but residual soil treatment generated during this excavation is required. Especially in urban areas, when constructing a foundation with the above composite pile. However, there is a big problem that the work of discharging and transporting the remaining soil treatment and the great cost for it are required.

Therefore, the present invention solves such a drawback by using a steel pipe pile as a pile foundation structure and connecting the steel pipe and the steel pipe arranged at the pile head with a filler. The present invention provides a pile head reinforcement structure for cast-in-place piles configured by fitting both of them together.

[0008]

That is, in the pile head joint structure for cast-in-place piles according to the present invention, a steel pipe 1 having a projection 9 on the inner surface is arranged on the pile head of the cast-in-place pile, and the steel pipe 1 A steel pipe 2 extending from the lower part of the pile and having a projection 10 is inserted inside, and a steel pipe 1 at the head of the pile is filled with a filling material. The filling material filled inside the steel pipe 1 constituting the pile head is concrete 3
It is preferable that the lower pile structure is a composite pile structure of the steel pipe 2 in the lower pile and the soil cement 4 in which the steel pipe 2 is built.

[0009]

According to the present invention, the strength of the cast-in-place pile itself is improved by the pile lower steel pipe 2 embedded in the pile, and the pile head is provided in the pile head steel pipe 1 and in the pile head steel pipe 1. It is reinforced with filled concrete 3. Further, the steel pipes 1 and 2 are joined and integrated through the concrete 3 by the projections 9 and 10 provided on the steel pipes 1 and 2, respectively. Further, when the lower part of the cast-in-place pile is combined with the steel pipe 2 and the soil cement 4, it is not necessary to discharge the earth and sand at the time of excavating the pile hole, and thus the residual soil treatment at the time of excavation is unnecessary.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described below with reference to FIGS. 1 and 2 show an example of a composite pile to which the pile head reinforcement structure of a cast-in-place pile of the present invention is applied, and FIG. 1 shows that the lower portion of the soil cement synthetic steel pipe pile 5 is a steel pipe 2 on the soil cement 4 Soil cement pillar 6
FIG. 2 is an overall schematic view of a cast-in-place pile in which the steel pipe 1 for a pile head having the projection 9 on the inner surface is joined to the pile head, and FIG. 2 is a vertical cross-sectional view of FIG.

When constructing the soil cement synthetic steel pipe pile 5 shown in each drawing, before constructing the steel pipe 1 at the top of the pile, first, the cement milk is injected to excavate and mix the ground to a predetermined depth. Until then, the pile holes are excavated to form the soil cement columns 6. Next, after creating the soil cement pillar 6,
Protrusions 1 on the outer surface before the soil cement has yet solidified
The steel pipe 2 with 0 is built in the soil cement column 6.

In this way, by applying the soil cement synthetic steel pipe pile 5 as the pile foundation (that is, the lower portion of the pile), it is not necessary to discharge the stirred sediment generated by excavating the pile hole, so that the problem of residual soil treatment is not a problem. Will be resolved.

In this soil cement steel pipe pile 5, the steel pipe 2 built in the soil cement column 6 at the bottom of the column is usually preferable to be built up to reach the underground support layer as a basic structure of the structure.

When the steel pipe 2 under the pile is built in the soil cement column 6 constructed as described above, the steel pipe 2 is projected from the upper end 11 of the soil cement column 6 by a predetermined length, and this projection is made. The portion 2a is inserted into the steel pipe 1 of the pile head having the projection 9 on the inner surface with a gap. Steel pipe for pile head 1
Is to be arranged at the upper end of the soil cement column 6 when it is constructed. Thus, with the steel pipe 2 at the lower part of the pile inserted in the steel pipe 1 at the head of the pile, concrete 3 is filled into the steel pipe 1 as a time-hardening filler. The insertion length of the protruding portion 2a of the steel pipe 2 to be inserted into the steel pipe 1 of the pile head may be appropriately determined depending on the size of the steel pipe 1, the strength of the concrete 3 filled in the steel pipe 1, and the like. It is not something that will be done.

As described above, the projection 9 is formed on the inner surface of the steel pipe 1 at the head of the pile.
And the projection 10 is provided on the steel pipe 2 at the bottom of the pile, so that when the concrete 3 is filled into the steel pipe 1, the projections 9 and 10 and the concrete 3 are well eaten, Steel pipe 2 under the pile through concrete 3
Since the steel pipe 1 on the pile head and the steel pipe 1 on the pile head are firmly adhered to each other and high adhesion strength between them can be secured, the conventional reinforcing bar joint structure can be eliminated.

The protrusion formed on the steel pipe 2 below the pile is
Not only the projection 10 on the outer surface as shown, but also the inner surface,
Alternatively, it may be provided on both the inner and outer surfaces. By providing the projections on the inner and outer surfaces of the steel pipe 2 in this way, the adhesion strength with the concrete 3 is further increased, and a strong cast-in-place composite pile can be easily constructed.

Further, the projections 10 on the inner and outer surfaces of the steel pipe 2 at the bottom of the pile and the projections 9 provided on the inner surface of the steel pipe 1 at the pile head, which are combined with the soil cement 4, may be of any shape. Alternatively, for example, as shown in FIG. 3, it may be formed into a spiral protrusion 9 or a zigzag protrusion 9 as shown in FIG. 1 and the steel pipe 2 below the pile can be integrated.

[0018]

According to the pile head reinforcement structure for cast-in-place piles of the present invention, the following effects can be obtained. Steel pipe 2 at the bottom of the pile and steel pipe 2 at the top of the pile built in the pile
Are fitted with each other with a gap, and by filling the steel pipe 1 in the pile head with a filler,
0, the pile head of the cast-in-place pile is strongly reinforced, and the lower part of the pile is integrated with the steel pipe 2 as the reinforcing material and the filling material in which the steel pipe 2 is built. It will be a composite pile, and the structure will be extremely excellent in earthquake resistance. Further, when the soil cement steel pipe pile 5 is constructed as the foundation of the cast-in-place composite pile, the residual soil treatment which is a problem when constructing the cast-in-place concrete pile is not required, and the cast-in-place pile can be used even in an overcrowded area such as an urban area. Construction work can be performed easily and inexpensively.

[Brief description of drawings]

FIG. 1 is a side view showing a pile head joint structure for a cast-in-place pile according to an embodiment of the present invention.

FIG. 2 is a vertical cross-sectional side view showing a pile head joint structure for a cast-in-place pile according to an embodiment of the present invention.

FIG. 3 is a partially longitudinal side view showing an example of a pile head steel pipe with protrusions used when carrying out the present invention.

FIG. 4 is a vertical cross-sectional side view showing another example of a pile-head steel pipe with protrusions used when carrying out the present invention.

FIG. 5 is a vertical cross-sectional side view showing a pile made of concrete and a reinforcing bar that is cast in a conventional steel pipe.

FIG. 6 is a vertical cross-sectional side view showing a conventional reinforcing steel pile struck in a steel pipe and a pile made of concrete.

[Explanation of symbols]

 1 Steel pipe at the top of pile 2 Steel pipe at the bottom of pile 3 Concrete 4 Soil cement 5 Soil cement steel pipe pile 6 Soil cement column 9 Protrusion 10 Protrusion 12 Concrete pile 13 Casing pipe 14 Steel pipe with protrusion 17 Reinforcing cage 18 Steel pipe with protrusion 19 Ground surface 20 Support layer

Claims (2)

[Claims] 1. A steel pipe 1 having a protrusion 9 on its inner surface is arranged on the pile head of a cast-in-place pile, and a steel pipe 2 extending from the lower part of the pile and having a protrusion 10 is inserted into this steel pipe 1. ,
A pile head joint structure for a cast-in-place pile, which is formed by filling the steel pipe 1 of the pile head with a filler. 2. The filling material filled inside the steel pipe 1 constituting the pile head is concrete 3, and the lower pile structure comprises the lower steel pipe 2 and the steel pipe 2. The pile head joint structure for cast-in-place piles according to claim 1, which is a composite pile structure with soil cement 4.