JPH0468407B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method of constructing a cast-in-place concrete pile that can withstand horizontal forces by increasing the diameter of the pile head.

[Conventional technology] There have been various methods of constructing cast-in-place concrete piles with enlarged pile bottoms.Piles with enlarged pile bottoms are widely used because they have a large vertical bearing capacity. has achieved results.

On the other hand, for cast-in-place concrete piles that can withstand large horizontal forces, that is, cast-in-place concrete piles that are the subject of this invention, the amount of reinforcing bars is increased or decreased on the premise that the pile diameter is constant. When designing, it is necessary to
It is considered that the part up to about 10 m mainly controls the horizontal force, and that the part deeper than that plays the role of transmitting the vertical supporting force.

[Problems to be Solved by the Invention] By the way, when explaining cast-in-place concrete piles that can withstand large horizontal forces, it is important to understand that the diameter of the cast-in-place concrete piles that can withstand large horizontal forces is smaller than the pile diameter that is required for vertical bearing capacity. The required pile diameter is larger and, as a result, the pile diameter is often determined by the horizontal force. For this reason, the diameter from the pile head to the pile bottom is the same, and the pile bottom has an uneconomical configuration.

This invention solves these conventional problems.

[Means for Solving the Problems] In order to solve the above-mentioned conventional problems, the method for constructing cast-in-place concrete piles according to the present invention involves embedding a thick casing in a hollow manner, and then installing an auger that passes through the casing. Then, while raising the auger to the lower end of the casing, mortar is injected from the tip of the auger to the lower end of the casing to create a relatively small-diameter pile corresponding to the outside diameter of the auger. Mortar is injected from the tip of the auger while simultaneously pulling up the casing and auger to form a relatively large pile head corresponding to the outside diameter of the casing, and reinforcing steel is inserted into the injected mortar. The feature is that the pile bottom and the pile head are integrated by inserting the pile.

[Function] The method for constructing cast-in-place concrete piles of the present invention creates a space for forming a pile head with a relatively large diameter by the embedding trace of the casing, and further extends the space below the casing through the inside of the casing. A cast-in-place concrete pile is constructed in which the pile head has a larger diameter than the pile bottom and can withstand a large horizontal force by making the space for forming the pile bottom relatively small in diameter by the excavation trace of the auger being excavated.

[Example] Hereinafter, an example of the present invention will be described based on the drawings.

FIGS. 1a, b, c, and d are explanatory diagrams of an embodiment of the present invention, and show the construction process of cast-in-place concrete piles in the order shown.

First, as shown in figure a, a thick casing 1
Prepare this casing 1 and embed it in a hollow manner. This casing 1 has a combined structure of a plurality of components and has a length of about 10 m. Casing 1
For example, it is possible to use an auger, which will be used in the next step, as a medium digging method for burying.

Next, as shown in FIG. 1B, the auger 2 is lowered into the casing 1 from above while rotating, and the auger 2 further excavates the area below the casing 1. Excavation by the auger 2 reaches the support layer of the ground.

After that, with casing 1 left in place, mortar is injected from the tip of auger 2 while pulling it up, and then
(See figure c). This results in
A relatively small diameter pile bottom corresponding to the outer diameter of the auger 2 is formed.

Then, while pulling up the casing 1 together with the auger 2, more mortar is injected from the tip of the auger 2. As a result, the diameter of the mortar injection space is expanded by the thickness of the casing 1, and a relatively large diameter pile head corresponding to the outer diameter of the casing 1 is formed.

After the mortar is injected in this manner, the reinforcing bars 3 are inserted into the mortar from above, as shown in FIG. 4D, to integrate the pile head and the pile bottom.
The reinforcing bars 3 are, for example, combined in a basket shape, and are appropriately overlapped and added depending on the length of the pile. The diameter of the reinforcing bars 3 located at the boundary between the pile bottom and the pile head gradually increases from the pile bottom side toward the pile head side, so that the stress can be easily transmitted at this point. This reinforcing bar 3 is inserted to complete the construction of the concrete pile.

[Effects of the Invention] As explained above, the method for constructing cast-in-place concrete piles according to the present invention involves embedding a thick casing and then excavating from inside the casing to the support layer of the ground using an auger. The pile bottom has a relatively small diameter due to the space left by the auger, and the pile head has a relatively large diameter due to the space left by the casing, so the horizontal force on the pile head can be reduced. The diameter of the pile is relatively large in order to fully meet the requirements for withstanding the above conditions, while the bottom of the pile has a relatively large diameter in order to obtain vertical bearing capacity, regardless of the relatively large diameter of the pile head. It can be made to a relatively small diameter sufficient for Therefore, the diameters of the pile head and the pile bottom can be determined independently according to their functions, and in particular, the pile bottom can be economically made with a diameter as small as necessary. In addition, mortar is injected from the tip of the auger while pulling up the casing and auger to create a large diameter pile head. During pouring, the mortar is restrained from moving upward by the auger and receives constant pressure from the tip of the auger, so the mortar is poured uniformly and densely, and the created pile head is The structure becomes uniform and dense, and sufficient strength can be obtained.

Furthermore, while raising the auger to the lower end of the casing, mortar is injected from the tip of the auger to the lower end of the casing to form a relatively small pile bottom corresponding to the outer diameter of the auger, and then, while simultaneously raising the casing and auger, Mortar is injected from the tip of the auger to form a relatively large pile head that corresponds to the outside diameter of the casing. It is possible to create piles with different pile bottoms and pile heads.

[Brief explanation of the drawing]

FIGS. 1a, b, c, and d are explanatory diagrams showing the construction method of the present invention in order of steps. 1...Casing, 2...Auger, 3...Rebar.

Claims (1)

[Claims] 1. A thick casing is buried in a hollow manner, and then an auger passing through the casing is used to excavate to the support layer of the ground below the casing.Then, while the auger is pulled up to the bottom of the casing, mortar is poured into the casing from the tip of the auger. Inject mortar to the bottom of the auger to form a relatively small diameter pile base corresponding to the outside diameter of the auger, and then inject mortar from the tip of the auger while simultaneously pulling up the casing and auger to create a pile base that corresponds to the outside diameter of the casing. A method for constructing cast-in-place concrete piles, which is characterized by forming a pile head with a relatively large diameter, and inserting reinforcing bars into poured mortar to integrate the pile bottom and the pile head.