JPS6250516A - Formation work of composite pile - Google Patents

Abstract

PURPOSE:To enhance the bearing capacity of a composite pile by a method in which concrete is placed to the expanded tip portion of a prebored pit, and a custom-made reinforced concrete pile having reinforcing bars on its tip peripheral side is penetrated into and fixed to the concrete. CONSTITUTION:A prebored pit 1 is excavated in the ground, and an expanded bottom portion 2 is formed on the tip portion of the pit 1. In-situ concrete 3 is packed into the expanded bottom 2 of the pit 1, a custom-made reinforced concrete pile P having reinforcing bars 4 on its tip peripheral side is inserted into the pit 1, and its tip portion is penetrated into the concrete 3.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application This invention relates to a method for constructing a composite pile by combining a cast-in-place reinforced concrete pile and a ready-made reinforced concrete pile.

Problems to be solved by the prior art and the invention Fill concrete is obtained by enlarging the bottom of a pre-bored hole, injecting cement milk into the hole, and stirring it with earth and sand as a low-vibration, low-noise foundation pile burying method. Insert a ready-made stake inside,
A method of supporting ready-made piles with hardened fill concrete has been put into practical use. However, this construction method currently only allows a predetermined lower bearing capacity than the conventional method of driving ready-made piles. One of the reasons for this is that even though the bulb has an expanded base, it does not have a reinforced structure with reinforcing bars, and the bulb and the ready-made pile are not sufficiently integrated.〇The applicant has proposed an invention that can solve the above problems. Special application 1973-
We have already developed a method shown in No. 102455 (Japanese Unexamined Patent Publication No. 55-30040). This invention further develops and improves the invention to improve the supporting capacity of the pile.

Means for Solving the Problems The gist of the invention is as described in the scope of the claims, and the main part thereof consists of pouring cast-in-place concrete into a pre-bored hole with an enlarged bottom. Next, the ready-made reinforced concrete pile with the concrete reinforcement attached is inserted into the concrete and fixed and integrated.Thus, a composite pile is created, and reinforcing bars such as reinforcing bars are buried in the cast-in-place concrete part. As a result, the cast-in-place concrete, which has a larger diameter than ready-made piles, is expected to have greater bearing capacity, which in turn improves the bearing capacity of the pile as a whole.

Embodiment First, a pre-boring hole 1 is excavated by an excavator using a muddy water method, and the tip portion is made into an enlarged bottom hole 2 using a wing-expanding bit of the excavator. An example of this is shown in Figure 1, where the cross-sectional area of the pre-bored hole is A, while the cross-sectional area of the expanded hole is 2A.
and the depth is 4 to 5D or more.

Next, the expanded bottom hole 2 is filled with cast-in-place concrete 3. A reinforcing bar 4 corresponding to a length of 4D or more is attached to the outer periphery of the tip of the ready-made reinforced concrete pile P shown in Fig. 2.The reinforcing bar 4 is formed of strip-shaped iron strips, and the outer periphery of the reinforcing bar 4 is Spiral reinforcing bars 5 are welded at the factory.

As another invention, at the tip of a prefabricated reinforced concrete pile P,
Steel pipes 6 having a length of D or more are welded and connected, and a spiral reinforcing bar 5 is welded to the outer periphery at a factory. Note that the adhesion force with the concrete can be increased by forming a through hole in the steel pipe 6 to communicate the inner and outer concrete, or by forming the steel pipe 6 into an uneven shape.

The above pile P is inserted into the pre-bored hole 1, and its tip is inserted into the cast-in-place concrete 6.

At this time, if necessary, the rod-shaped pie break may be lowered to the vicinity of the tip of the pile and vibrated to improve the adhesion between the pile P and the surrounding concrete.

If cement milk is poured into the upper part of the cast-in-place concrete 6, the area around the pre-bored hole 1 and the pile P will be filled.

Effects of the Invention The present invention has the above-mentioned configuration, and includes reinforcing bars attached to the outer periphery of the tip of a ready-made reinforced concrete pile, or a steel pipe attached to the tip of a ready-made reinforced concrete pile, and placed in the expanded bottom of a pre-bored hole. By inserting a large diameter cast-in-place pile at the bottom of the ready-made pile, a large diameter cast-in-place pile with a required reinforcing bar ratio, for example, 0.4% or more, is created, which provides greater support than the conventional cement milk foundation method. You can expect power.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of the pre-bored hole, FIGS. 2 and 3 are cross-sectional views of the completed construction state, and FIGS. 4 and 5 are detailed views of the tip of the pile, which are partial views. 1. Pre-boring hole, 2. Expanded hole, 3. Cast-in-place concrete, P. Pile, 4. Reinforcement bar, 5. Spiral reinforcing bar, 6. Steel pipe. Figure 1 ノ2u':;3:: Figure 4, 15 ro

Claims (2)

[Claims] (1) A pre-bored hole with an enlarged bottom end is formed, then cast-in-place concrete is poured into the bottom end of the pre-bored hole, and reinforcing bars of the concrete are attached to the outer periphery of the tip end of the ready-made reinforced concrete pile. A method for constructing a composite pile, characterized by inserting and fixing into the concrete and integrating it. (2) A pre-bored hole with an enlarged tip is formed, then cast-in-place concrete is poured into the enlarged tip of the pre-bored hole, and a steel pipe is attached to the tip to serve as reinforcement for the concrete. A construction method for a composite pile, characterized by inserting and fixing a reinforced concrete pile into the concrete and integrating it.