JPH073785A - Constructing method for cast-in-place steel pipe concrete pile - Google Patents

Abstract

PURPOSE:To construct a cast-in-place steel pipe concrete pile through simplified processes without delivering earth and sand by utilizing a foundation improvement method whereby a slurry of cement type hardening material is injected. CONSTITUTION:A constructing machine provided with a rotating shaft 2 having a drill 3 and stirring blades 4 and with a cement type hardening material slurry injection pipe is hoisted vertically by a crane and the rotating shaft 2 and the cement type hardening material slurry injection pipe are inserted into a steel pipe 1 attached to a steel pipe holder 6. The construction machine is installed in a predetermined position to drill the ground 9 immediately therebelow, and stirring of the ground soil and injection of a slurry of cement type hardening material are started before the passage of the steel pipe 1 through dry-excavated portion 8, and injection of the slurry of cement type hardening material and drilling are stopped when the end of the steel pipe 1 has reached supporting ground 10. Then the steel pipe 1 is removed from the steel pipe holder 6 and the constructing machine is hoisted up by the crane with the stirring blades rotated, to wait for the improved foundation to be solidified by the cement type hardening material.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for constructing cast-in-place steel pipe concrete piles.

[0002]

2. Description of the Related Art The conventional method for constructing cast-in-place concrete piles is to first dig the ground with a ground drill, etc. to the required depth, then insert the rebar cage and the steel pipe into the digging hole, then insert concrete into the digging hole. The method of placing is common.

[0003]

In the conventional method, a large amount of earth and sand is generated due to excavation of the ground, and this earth and sand must be carried out and discarded. Since carrying out and disposing of sediment is not only environmentally preferable but also increases costs, it is desired to prevent the generation of sediment. Further, the conventional method has a long construction period due to the multi-steps of excavation, insertion of reinforcing bars / steel pipes, and concrete placing. Therefore, simplification of the steps is desired.

[0004]

SUMMARY OF THE INVENTION The present invention is to solve the problems of the conventional method, and by utilizing the ground improvement method for the construction of cast-in-place steel pipe concrete piles, without the generation of earth and sand, A cast-in-place concrete pipe pile is constructed by a simplified process.

That is, according to the present invention, the rotary shaft and the injection pipe of the construction machine equipped with the rotary shaft having the excavator and the stirring blade and the injection pipe of the cement-based solidifying material slurry are inserted into the steel pipe and installed at predetermined positions. Then, while excavating the ground directly below, press fit the steel pipe, start stirring the ground soil and injecting the cement-based solidifying material slurry shortly before the steel pipe tip passes through the hollow section,
This is a method for constructing cast-in-place concrete piles by stopping the injection and excavation of the cement-based solidifying material slurry when the tip of the steel pipe reaches the support ground, and pulling up the rotary shaft of the construction machine and the injection pipe.

In the present invention, as in the ground improvement method, the ground soil is mixed with the cement-based solidifying material while being agitated to be solidified, so that there is no excavation step and therefore no earth and sand that must be carried out and discarded is generated. . Further, since the steel pipe is press-fitted into the ground in the same process as that of mixing the ground soil with the cement-based solidifying material while stirring, the process of inserting the reinforcing bar / steel pipe is omitted and the process is simplified.

In the cast-in-place steel pipe concrete pile constructed according to the present invention, the compressive force is borne by the concrete and the steel pipe made of the cement-based solidifying material and the ground soil, and the bending moment and the shearing force are borne by the steel pipe and the concrete inside the steel pipe. The structure ensures excellent performance as a pile.
In order to secure the performance as a pile, it is preferable to provide a groove on the inner surface of the steel pipe so as to be integrated with the internal concrete.

[0008]

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

FIG. 1 is a vertical sectional view showing a construction procedure of the present invention.

The construction machine is equipped with a motor 5, a rotary shaft 2 driven by the motor 5, a steel pipe holder 6, an injection pipe (not shown) for cement-based solidifying material slurry, and other auxiliary equipment. An excavator 3 and a stirring blade 4 are attached to the tip of the rotary shaft 2.

The cement solidifying material slurry injection pipe is open in the vicinity of the stirring blade 4.

(1) The construction machine is suspended vertically by a crane, and the upper end of the steel pipe 1 is attached to the construction machine by a steel pipe holder 6. The length of the steel pipe 1 is such that the lower end thereof is at substantially the same level as the tip of the rotating shaft 2. Operate the crane to install the construction machine in place. (Fig. 1 (a)) (2) The construction machine is lowered while being supported by a crane, and the excavator 3 is rotated to start excavation of the ground immediately below. As the construction machine descends, the steel pipe 1 is press-fitted by its own weight and the weight of the construction machine. (Fig. 1 (b)) (3) Loosen the crane support of the construction machine and continue excavation. The rotation of the stirring blade 4 and the injection of the cement-based solidifying material slurry are started just before the lower end of the steel pipe 1 passes through the hollow section 8. (FIG. 1C) (4) The rotation of the excavator 3, the stirring blades 4 and the injection of the cementitious solidifying material slurry are continued. The bottom end of the steel pipe 1 is the excavated ground 9
After passing through and reaching the support ground 10, the rotation of the excavator 3 and the injection of the cementitious solidifying material slurry are stopped. (FIG. 1 (d)) (5) The steel pipe 1 is disconnected from the steel pipe 1 by the steel pipe holder 6, and the construction machine is pulled up by a crane while continuing to rotate the stirring blade 4. (Fig. 1 (e)) (6) When the construction machine is pulled up, the rotation of the stirring blade 4 is stopped, and after the solidification of the ground soil 7 by the cement-based solidifying material is awaited, the construction of the cast-in-place concrete pipe pile is completed. (Fig. 1
(F)) When the support ground 10 is deep and it is necessary to splice the steel pipe 1, the motor 5, the steel pipe holder 6 and the rotary shaft 2 of the construction machine are pressed at the stage where the first steel pipe 1 has been press-fitted. To
Separate from the steel pipe 1 and the already entered rotary shaft 2, and in between 2
It suffices to insert the first steel pipe 1 and the extension rotary shaft 2, restart the rotation of the excavator 3, the stirring blade 4, and the injection of the cement-based solidifying material slurry.

[0013]

By utilizing the ground improvement method for forming cast-in-place steel pipe concrete piles, cast-in-place steel pipe concrete piles can be formed in a simplified process without generating soil.

[Brief description of drawings]

FIG. 1 is a vertical sectional view showing a construction procedure of the present invention,
(A) is for positioning, (b) is for starting excavation, (c) is for solidifying material injection / steel pipe press fitting, (d) is for solidifying material injection / steel pipe press fitting, (e) is for construction machine pulling up, (F) indicates when the work is completed.

[Explanation of symbols]

1 ・ ・ Steel pipe, 2 ・ ・ Rotary shaft, 3 ・ ・ Drilling tool, 4 ・ ・ Stirring blade, 5 ・ ・ Motor, 6 ・ ・ Steel pipe holder, 7 ・ ・ Improved ground, 8 ・ ・ Drying section, 9 ・ ・Excavation ground, 10 ... Support ground

Claims (1)

[Claims] 1. A rotary shaft having an excavator and a stirring blade, and a rotary shaft and an injection pipe of a construction machine equipped with an injection pipe for cement-based solidifying material slurry are inserted into a steel pipe and installed at a predetermined position. The steel pipe is press-fitted while excavating the ground, stirring of the ground soil and the injection of the cement-based solidifying agent slurry are started just before the steel pipe tip passes through the hollow section, and the cement-based solidification is reached when the steel pipe tip reaches the supporting ground. Method for constructing cast-in-place concrete pile by stopping injection and excavation of material slurry and pulling up rotary shaft and injection pipe of construction machine