JP2015010328A - Installation method for underground column - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an installation method for an underground column, which can easily shorten a construction period and which can easily increase installation accuracy.SOLUTION: In an installation method for an underground column, an underground column 7 is installed in a position eccentric with respect to a bearing pile 3a in an inverted construction method. A positioning member 8 protruding downward eccentrically from the underground column 7 is integrally pre-provided at a lower end of the underground column 7. The underground column 7 is suspended in a predetermined eccentric position within a bearing pile excavation range 12, and the positioning member 8 is integrated with placed concrete 11 in the state of being buried in the placed concrete 11 of the bearing pile 3a.

Description

  The present invention relates to an underground column installation method for installing an underground column at a position eccentric to a support pile in a reverse driving method.

In the reverse construction method of a building, a floor part that divides the upper part of the underground space is constructed, and then the lower side of the floor part is excavated.
Patent Documents 1 and 2 disclose a method of installing a conical column concentric with a support pile in a reverse driving method.
By the way, when installing an underground column (non-structured column) at a position eccentric to the support pile in the reverse driving method, conventionally, after excavating the lower side of the already constructed floor part, It is installed by inserting a pillar and connecting it to the lower surface side of the floor portion.

Japanese Patent Application Laid-Open No. 07-300869 JP 09-158224 A

In the conventional underground column installation method, after excavating the underside of the constructed floor portion, the underground column is installed under the floor portion. Can not be installed. Therefore, there are significant restrictions on the process of installing the underground pillars, and it is difficult to shorten the construction period.
Also, if the underground space is divided into multiple floors, each time the floor part of each floor is constructed and the lower part is excavated by the floor height, an underground column with a short length corresponding to each floor height is It is necessary to enter the lower side of the floor and connect to the floor portion, which may complicate the installation work of the underground pillar.
This invention is made | formed in view of the said situation, Comprising: It aims at providing the underground pillar installation method which is easy to aim at shortening of the construction period for installing an underground pillar, and the improvement of installation accuracy.

  The characteristic configuration of the present invention is an underground column installation method in which an underground column is installed at a position eccentric with a support pile in a reverse driving method, and a positioning member that is eccentric from the underground column and protrudes downward, Provided integrally with the lower end of the underground column, the underground column was suspended at a predetermined eccentric position within the support pile excavation range, and the positioning member was embedded in the concrete cast in the support pile It is in the point of making it integrate with the placement concrete concerned in a state.

The underground pillar installation method of this configuration suspends the underground pillar at a predetermined eccentric position within the support pile excavation range, so it is easy to use the underground excavation part excavated to install the support pile. Can be arranged.
In addition, the positioning member provided integrally with the lower end of the underground pillar is integrated with the cast concrete in a state where it is embedded in the cast concrete of the support pile. Can be installed with high accuracy in the position or posture.
Therefore, there are few restrictions on the process of installing the underground pillar, it is easy to shorten the work period for installing the underground pillar, and it is easy to improve the installation accuracy.
In addition, even when the underground space is divided into multiple floors, a series of underground pillars can be installed across multiple floors without installing a short underground pillar corresponding to each floor height of each floor. Therefore, the installation work can be simplified.

  Another characteristic configuration of the present invention is that the positioning member has a bending rigidity set lower than that of the underground pillar.

  If it is this structure, the stress transmission between an underground pillar and a support pile can be relieve | moderated by the bending deformation of a positioning member. For this reason, it is possible to prevent a large bending stress from acting on the underground column.

  According to another characteristic configuration of the present invention, the positioning member includes: an extending portion extending along a column radial direction from a lower end of the underground column; and a fixing portion extending along a column longitudinal direction from the tip of the extending portion. It is in the point which forms in the provided shape.

If it is this structure, the fixing | fixed part extended | stretched along the column longitudinal direction from the front-end | tip of an extending | stretching part can be arrange | positioned to the center side of a support pile excavation range by the extending | stretching part extended | stretched along a column radial direction.
For this reason, it is easy to allow the anchoring part to enter the inside of the rebar cage installed in the support pile excavation range for constructing the support pile, and the positioning member is difficult to interfere with the rebar cage. easy.

  Another characteristic configuration of the present invention is that the positioning member is formed in a shape including an extending portion inclined downward on the outer side in the column radial direction from the lower end of the underground column.

In this configuration, for example, a crank-shaped positioning member having an extending portion extending along the column radial direction from the lower end of the underground column and a fixing portion extending along the column longitudinal direction from the tip of the extending portion. In comparison, the length of the positioning member can be shortened, and the bending angle of the bent portion of the positioning member can be set to an obtuse angle.
For this reason, it is easy to alleviate the stress concentration on the bent portion and share the stress without difficulty in the entire positioning member.

It is sectional drawing which shows the underground pillar installation method of 1st Embodiment. It is sectional drawing which shows the underground pillar installation method of 1st Embodiment. It is sectional drawing which shows the underground frame of 1st Embodiment. It is a side view which shows the positioning member provided in the lower end part of the underground pillar of 1st Embodiment. It is a side view which shows the positioning member provided in the lower end part of the underground pillar of 2nd Embodiment. It is a side view which shows the positioning member provided in the lower end part of the underground pillar of 3rd Embodiment.

Embodiments of the present invention will be described below with reference to the drawings.
[First Embodiment]
1 and 2 are cross-sectional views showing an underground pillar installation method according to the present invention. FIG. 3 is a cross-sectional view showing an underground frame 2 of a reinforced concrete building constructed by a back-stripping method inside the retaining wall 1. The underground frame 2 is integrally constructed of reinforced concrete on top of a plurality of reinforced concrete support piles 3a and 3b embedded in the ground G.

  The underground frame 2 includes an above-ground floor portion 4a that divides the uppermost portion of the underground space, an underground floor portion 4b that divides the intermediate portion in the height direction of the underground space, and support piles 3a and 3b at the lowermost portion of the underground space. It has the foundation beam 5 constructed | assembled integrally, the construction pillar 6 and the underground pillar 7 constructed | assembled integrally over each floor part 4a, 4b and the foundation beam 5. FIG.

  The structural pillar 6 is disposed in the inner region of the underground space, and is constructed integrally and concentrically on the upper portion of the support pile 3b. The underground pillar 7 is disposed in the outer peripheral area of the underground space, and is installed at a position above the support pile 3a and eccentric with the axis of the support pile 3a. Loads from the underground column 7 and the structural column 6 are transmitted to the support piles 3a and 3b through the foundation beam 5.

1 and 2 show an underground column installation method in which the underground column 7 is installed at a position eccentric to the support pile 3a when the support pile 3a is constructed in the reverse driving method.
As shown in FIG. 1, each of the support piles 3 a and 3 b is formed by inserting a cylindrical reinforcing bar 10 into a drilling hole 9 obtained by excavating the ground G in a circular shape from the ground surface GL, and then placing the concrete into the drilling hole 9. As shown in FIG.
The excavation range of the circular excavation hole 9 corresponds to the support pile excavation range 12.

  As shown in FIG. 1, the rebar cage 10 is inserted into the excavation hole 9 until its upper end reaches a predetermined depth from the ground surface GL, and the concrete 11 is driven into the excavation hole 9 to a depth corresponding to the lower surface of the foundation beam 5. Established. Therefore, each support pile 3a, 3b is constructed such that its upper end is located at a depth corresponding to the lower surface of the foundation beam 5.

The underground pillar 7 is made of, for example, a section steel such as an H-section steel. A steel positioning member 8 that is eccentric from the underground pillar 7 and protrudes downward is provided in advance at the lower end of the underground pillar 7 by being integrally connected by welding.
As shown in FIG. 4, the positioning member 8 includes an extending portion 8 a extending from the lower end of the underground pillar 7 along the column radial direction, and a fixing portion extending downward from the distal end of the extending portion 8 a along the column longitudinal direction. 8b is integrally formed with a crank shape.

  As shown in FIG. 1, the underground pillar 7 is inserted into the excavation hole 9 after placing the concrete 11 together with the positioning member 8 before the concrete 11 is hardened. The underground pillar 7 is suspended and held at a predetermined eccentric position in the support pile excavation range (circular excavation hole 9) 12 so that the tip portion of the fixing portion 8b enters the uncured concrete 11 inside the reinforcing bar cage 10. Is done.

As shown in FIG. 2, the underground pillar 7 is constructed integrally with the support pile 3 a in a state where the tip portion of the fixing portion 8 b in the positioning member 8 is embedded in the placement concrete 11.
The extending portion 8a and the fixing portion 8b are made of, for example, a shape steel having a bending rigidity smaller than that of the shape steel constituting the underground column 7, and are integrally welded and fixed in a posture orthogonal to each other.

  The structural pillar 6 is made of, for example, a shape steel such as an H-shaped steel, and is inserted into the excavation hole 9 after the rebar cage 10 is inserted and the concrete 11 is placed, and the lower end portion thereof is supported. Constructed integrally with the pile 3b.

That is, the structural pillar 6 is inserted into the excavation hole 9 after placing the concrete 11 as shown in FIG. 1 before the concrete 11 is hardened, and its lower end portion is unhardened inside the reinforcing bar 10. It is suspended and held concentrically inside the excavation hole 9 so as to enter the concrete 11.
Therefore, as shown in FIG. 2, the structural pillar 6 is constructed integrally with the support pile 3 b in a state where the lower end portion is embedded in the placement concrete 11.

[Second Embodiment]
FIG. 5 shows a positioning member 8 according to another embodiment of the present invention.
In the present embodiment, the positioning member 8 is formed in a shape including an extending portion 8a inclined downward from the lower end of the underground pillar 7 on the outer side in the column radial direction.
That is, the positioning member 8 extends from the lower end of the underground pillar 7 along the direction inclined with respect to the axis of the underground pillar 7 and extends downward from the distal end of the extending part 8a along the column longitudinal direction. And a fixing portion 8b to be formed.
Other configurations are the same as those of the first embodiment.

[Third Embodiment]
FIG. 6 shows a positioning member 8 according to another embodiment of the present invention.
In the present embodiment, the positioning member 8 is formed in a shape including a series of extending portions 8a inclined downward from the lower end of the underground column 7 on the outer side in the column radial direction.
Other configurations are the same as those of the first embodiment.

3a Support pile 7 Underground pillar 8 Positioning member 8a Extension part 8b Fixing part 11 Casting concrete 12 Support pile excavation range

Claims (4)

An underground pillar installation method in which an underground pillar is installed at a position eccentric to the support pile in the reverse driving method,
A positioning member that is eccentric from the underground pillar and protrudes downward is provided in advance at the lower end of the underground pillar,
Installation of the underground pillar that suspends the underground pillar at a predetermined eccentric position within the support pile excavation range and integrates the positioning member with the placement concrete in a state where the positioning member is embedded in the placement concrete of the support pile. Method.   The underground positioning method according to claim 1, wherein the positioning member has a bending rigidity set lower than that of the underground pillar.   The positioning member is formed in a shape including an extending portion extending along a column radial direction from a lower end of the underground pillar, and a fixing portion extending along a column longitudinal direction from the tip of the extending portion. Item 3. An underground pole installation method according to item 1 or 2.   The underground positioning method according to claim 1 or 2, wherein the positioning member is formed in a shape including an extending portion that is inclined downward on the outer side in the column radial direction from the lower end of the underground column.

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