JPH0742151A - Method and device for excavating pile foundation having bottom expanding part - Google Patents

Abstract

(57) [Summary] (Corrected) [Purpose] To prevent the ground subsidence of the surrounding structures and to be able to perform construction even in a narrow space, to improve the construction efficiency and to construct a widened bottom that allows the construction of a large bottom. A pile foundation excavating method and an apparatus therefor are provided. [Structure] The soil improvement liquid is injected around the area where the bottom of the pile foundation is to be expanded to improve the ground, and the anchor steel pipe 3 is installed in the center of the area where the pile foundation is to be constructed, and the anchor PC wire is inside the steel pipe. -31 is inserted and the tip of the wire is fixed with a solidifying material, and the turning steel pipe 5 having a drilling member 61 capable of expanding the drilling range at the tip is sheathed on the anchor steel pipe. The steel pipe pile 8 is installed as an exterior, the turning steel pipe is rotated in a state where the excavation area of the excavating member is reduced, and the steel pipe for anchoring is pre-drilled while receiving a reaction force, and the steel pipe pile is press-fitted to the planned bottom expansion portion, and then turned. The excavating member of the steel pipe for use is expanded, and the planned expansion part is expanded.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for excavating a pile foundation having an expanded bottom portion.

[0002]

[Problems of the prior art] When excavating a high-resilience foundation structure in a narrow space where the construction space of the soft ground area in an urban area is limited, a large excavator cannot be used, so groundwater is drained to lower the water level. It was excavating manually. Therefore, there is a possibility that the ground subsidence may have a great influence on the surrounding structures, and at the same time, a decrease in construction efficiency has been a problem.

[0003]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, prevents ground subsidence of surrounding structures, and enables construction in a narrow space, and improves construction efficiency. An object of the present invention is to provide a pile foundation excavating method and apparatus having a bottom expanding part capable of constructing a large bottom expanding part.

[0004]

[Means for Solving the Problems] That is, according to the present invention, a soil improvement liquid is injected around a portion of a pile foundation to be expanded to improve the soil, and an anchor steel pipe is constructed at the center of the portion to be constructed the pile foundation. Then, a PC wire for an anchor is inserted into the steel pipe, the tip of the wire is fixed by a solidifying material, and a swiveling steel pipe having a drilling member capable of expanding the excavation range at the tip portion is used as the anchor steel pipe. The outer pipe is further covered with a steel pipe pile on the swiveling steel pipe, the swiveling steel pipe is rotated in a state where the excavation range of the excavating member is reduced, and the steel pipe pile is pre-digged while taking a reaction force to the anchor steel pipe. This is a pile foundation excavation method having a bottom expansion part, which is performed by press-fitting to the bottom expansion planned part, expanding the excavation member of the turning steel pipe, and expanding and excavating the bottom expansion planned part. Further, the present invention is an excavation device used for a method for excavating a pile foundation having the above-mentioned bottom portion, wherein a steel pipe for swiveling built in the center of the pile foundation, a boom provided at the tip of this steel pipe so as to be openable and closable, and this boom It is an excavation device for a pile foundation having an expanded bottom portion, which is composed of an excavation member provided at the tip of a ram.

[0005]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. <B> Ground improvement As shown in FIG. 2, a pedestal 2 is installed on the ground above the planned bottom expansion part 1 of the pile foundation, and a ground improvement ruler 21 and an injection pipe 22 are built to a predetermined depth.

[0006] Then, a ground improvement liquid is injected into the outer periphery of the planned bottom expansion portion 1 to build the ground improvement portion 23. The ground improvement section 23 is for preventing the surrounding ground from collapsing when excavating the bottom expansion scheduled portion 1.

<B> Anchor anchoring As shown in FIG. 1, an anchor steel pipe 3 is installed in the center of the pile foundation construction planned portion, and an anchor PC wire is installed therein.
31 is inserted and penetrated, and its tip is fixed with a solidifying material.

<C> Structure of excavator As shown in FIG. 1, the excavator according to the present invention has a steel pipe 5 for swiveling built in the center of a pile foundation and an opening / closing boom provided at its tip end so as to be openable and closable. 6 and an excavating member 61 provided at the tip
And consists of.

The open / close boom 6 is constructed such that one end thereof is pivotally supported by the swiveling steel pipe 5 and both ends thereof can be opened / closed by a telescopic jack 62 pivotally supported by the swiveling steel pipe 5 and the boom 6. The excavating member 61 may have various other structures such as a structure in which an excavating bit is planted on the peripheral surface of a rotatable drum.

<D> Excavation of pile section A swivel machine 4 is installed on the pedestal 2, and the anchor steel pipe 3 in which the swivel steel pipe 5 is installed is exteriorly mounted. Further, the steel pipe pile 8 is exteriorly mounted on the swivel steel pipe 5. To do.

Then, the opening / closing boom 6 is folded and the excavation member 6 is folded.
In the state where the excavation range of 1 is reduced, the turning steel pipe 5 is rotated by the turning machine 4 to dig ahead, and the steel pipe pile 8 is expanded to the bottom part 1
Press into. For press-fitting the steel pipe pile 8, the anchor steel pipe 3
A center wheel jack 71 having a reaction force with (PC wire-7) is used.

<E> Guide device As shown in FIG. 1, when excavating with an excavator, a guide device is mounted around the turning steel pipe 5. This device
As shown in FIG. 3, a mounting board 51 mounted on the outer circumference of the swiveling steel pipe 5, guide rollers 52 installed at a plurality of locations around the steel board 5, and a drop-off brush 5 projecting on the peripheral surface of the mounting board 51.
It consists of three.

The guide roller 52 is for pressing the turning steel pipe 5 against the wall of the hole when the turning steel pipe 5 is installed so that the turning steel pipe 5 maintains its center position. The drop-off brush 53 is for scraping off the irregularities of the hole wall to facilitate the construction of the steel pipe pile 8.

<F> Excavation of bottom expansion part After the excavation member 61 and the steel pipe pile 8 reach the bottom expansion planned part 1, excavation is performed while gradually expanding the opening / closing boom 6. This enables excavation of the expanded bottom portion 11 as shown in FIG.

[0015]

Since the present invention is as described above, the following effects can be obtained. <B> Since mechanical excavation is possible, it is not necessary to lower the groundwater level, and it is possible to prevent ground subsidence of surrounding structures. Further, since the construction efficiency is improved as compared with the conventional manual excavation, the construction period can be greatly shortened and the safety of the work is secured. Furthermore, mechanical excavation made it possible to construct a deep foundation structure.

<B> When the excavator of the present invention is used, since the width of the foundation pile portion can be made small and the width of the bottom expanding portion can be made large, it is possible to construct a foundation having low cost and high yield strength.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of a ground improvement process according to an embodiment of the present invention.

FIG. 2 is an explanatory view of an expanded bottom excavation process according to an embodiment of the present invention.

FIG. 3 is an explanatory view of a guide device.

Claims (2)

[Claims] 1. A ground improvement liquid is injected around the area where the bottom of the pile foundation is to be expanded to improve the ground, and an anchor steel pipe is installed in the center of the area where the pile foundation is to be constructed,
An anchor PC wire is inserted into this steel pipe, the tip of the wire is fixed by a solidifying material, and a swiveling steel pipe having an excavating member capable of expanding the excavation range at the tip is sheathed on the anchor steel pipe. Further, a steel pipe pile is further installed on the turning steel pipe, the turning steel pipe is rotated in a state where the excavation member has a reduced excavation range, and the steel pipe for anchoring is pre-digged while taking a reaction force to expand the bottom of the steel pipe pile. A method for excavating a pile foundation with a bottom expansion part, in which the excavation member of the steel pipe for turning is expanded and then the part to be expanded bottom is expanded and excavated. 2. An excavating device used in the method for excavating a pile foundation having an expanded bottom portion according to claim 1, wherein a swiveling steel pipe is built in a central portion of the pile foundation, and a buoy provided at the tip of the steel pipe so as to be openable and closable. An excavation device for a pile foundation having an expanded bottom portion, which comprises a boom and an excavation member provided at the tip of the boom.