JP7666182B2 - How to install a reverse-driven support - Google Patents

Description

The present invention relates to a method for erecting a reverse-cast support.

The inverted construction method is known as a construction method for constructing buildings with above-ground and underground portions. With this method, before the ground is excavated to construct the underground frame, inverted-construction pillars for supporting the above-ground portion of the building are erected into pile holes created in the ground, so that while the ground is excavated and the underground frame is constructed, the above-ground portion can be constructed on the inverted-construction pillars in parallel. This shortens the construction period for buildings compared to methods in which construction of the above-ground portion is carried out after construction of the underground portion is completed.

In this type of inverted construction method, if the inverted support has a certain length, a first-in construction method is generally used. In the first-in construction method, the inverted support is inserted into the pile hole before concrete is poured into the pile hole, and then the concrete is poured into the pile hole, so that the support is fixed to the cast-in-place concrete pile at the base (see, for example, Patent Document 1).

JP 2002-54164 A

If the inverted support pillar is fixed to the concrete pile in an inclined position relative to the vertical, this will have a significant impact on the connection with the beam and the construction of the above-ground portion, so it is necessary to support the inverted support pillar in a precisely vertical position until the concrete pile hardens.

However, when concrete is poured into a pile hole with the inverted support inserted, there is a problem in that the concrete can flow due to uneven height, and this flow can apply lateral pressure to the embedded part, reducing the verticality of the inverted support.

The present invention has been made in consideration of the above problems, and its object is to provide a method for erecting an inverted support pillar that can be precisely erected into a concrete pile.

The method for installing an inverted support of the present invention is a method for installing an inverted support in a pile hole provided in the ground, and is characterized in that it includes the steps of installing a reinforcing bar at a predetermined position on the bottom side of the pile hole, fixing a precision-maintaining steel material extending downward to the lower end of the root portion of the inverted support, inserting the inverted support with the precision-maintaining steel material fixed thereto into the pile hole, and after inserting the inverted support with the precision-maintaining steel material fixed thereto into the pile hole, pouring concrete inside the pile hole to fix the precision-maintaining steel material and the root portion to a cast-in-place concrete pile.

In the method for erecting a reverse-driven support pillar of the present invention, in the above configuration, it is preferable that the precision-maintaining steel material has at least one through hole.

According to the present invention, a method for erecting an inverted support pillar can be provided, which enables an inverted support pillar to be erected into a concrete pile with high precision.

This is a front view of an inverted support used in a method for installing an inverted support in one embodiment of the present invention. 2 is a cross-sectional view taken along line AA in FIG. 1. FIG. 2 is an enlarged front view of the precision-maintaining steel material shown in FIG. 1 . 4 is a cross-sectional view taken along line BB in FIG. 3. FIG. 2A is a diagram showing a pile hole drilled in the ground, and FIG. 2B is a diagram showing the state in which a reinforcing bar has been placed in the pile hole shown in FIG. FIG. 1A is a diagram showing a state in which an inverted support pillar with precision-maintaining steel material fixed thereto is inserted into a pile hole, and FIG. 1B is a diagram showing a state in which the precision-maintaining steel material is buried in concrete poured into the pile hole. FIG. 1A is a diagram showing a state in which the precision-maintaining steel material and a part of the embedded portion are buried in concrete poured into a pile hole, and FIG. 1B is a diagram showing a state in which a concrete pile has been formed by the concrete poured into the pile hole. This figure shows the state in which the above-ground part is being constructed while the underground part is being constructed after the inverted support pillars are fixed to the concrete piles. FIG. 13 is an enlarged front view of a precision-maintaining steel material according to a modified example. 10 is a cross-sectional view taken along line CC in FIG. 9. FIG. 4 is a diagram showing a portion of a modified inverted support pillar to which the precision-maintaining steel material shown in FIG. 3 is fixed. 12 is a cross-sectional view taken along line DD in FIG. 11. 9 is a diagram showing a portion of a modified inverted support pillar to which the precision-maintaining steel material shown in FIG. 8 is fixed.

Below, we will explain in detail the method for erecting an inverted support column and the inverted support column according to one embodiment of the present invention, with reference to the drawings.

The inverted support pillar 1 shown in Figure 1 is erected into a pile hole provided in the ground in a method for erecting an inverted support pillar according to one embodiment of the present invention.

The inverted support 1 is formed in a straight column shape of a predetermined length. In this embodiment, as shown in FIG. 2, the inverted support 1 is a box-shaped structure formed from a steel pipe with a rectangular cross section, and its interior is hollow. On the outer peripheral surface of the lower part of the inverted support 1, a plurality of studs 2 for engaging the inverted support 1 with the mat slab constituting the underground frame are fixed in a line at a predetermined interval from each other in the vertical and horizontal directions. Note that in FIG. 1, for convenience, only one stud 2 is given a reference number. The part of the inverted support 1 below the part where the plurality of studs 2 are fixed is the root part 3. The root part 3 is the part of the inverted support 1 that is inserted into the concrete poured in the pile hole and fixed to the concrete pile when the concrete hardens. The lower end of the inverted support 1 is blocked by a lower end blocking wall 4.

The inverted support 1 may have a temporary stake 10 attached to its upper end. The temporary stake 10 may be, for example, a straight, hollow pillar of a given length made of a steel pipe with a rectangular cross section of the same dimensions as the inverted support 1, with a pair of hanging hooks 11 at its upper end and multiple wing-shaped stoppers 12 fixed to its side to prevent it from falling.

A precision-maintaining steel material 20 is fixed to the lower end of the root portion 3 of the inverted support 1. The precision-maintaining steel material 20 extends downward from the lower end of the root portion 3 of the inverted support 1.

As shown in Figures 3 and 4, in this embodiment, the precision-maintaining steel material 20 is formed from an H-shaped steel. Specifically, the precision-maintaining steel material 20 has a web 21 formed from a thick plate in an elongated rectangular shape, and a pair of flanges 22 each formed from a thick plate in an elongated rectangular shape and connected to both sides of the web 21, and the cross-sectional shape perpendicular to the vertical direction is a uniform H-shape from the top to the bottom. The precision-maintaining steel material 20 is coaxial with the inverted support 1, and its upper end is fixed to the underside of the lower end closing wall 4 of the inverted support 1 by, for example, welding.

The width dimension (horizontal width dimension of the flanges 22) and depth dimension (dimension between the outer surfaces of the pair of flanges 22) of the precision-maintaining steel material 20 are smaller than the horizontal width dimension and depth dimension of the root portion 3 of the inverted support 1. In other words, the precision-maintaining steel material 20 is narrower than the root portion 3 of the inverted support 1.

It is preferable that the precision-maintaining steel material 20 is configured to have at least one through hole 23. In this embodiment, the precision-maintaining steel material 20 is configured to have five circular through holes 23 that penetrate the web 21 horizontally and are arranged at equal intervals in the vertical direction at the center of the width of the web 21, and five circular through holes 23 that penetrate the flange 22 horizontally and are arranged at equal intervals in the vertical direction at both sides of the web 21 of each flange 22. The number, arrangement, and shape of the through holes 23 provided in the precision-maintaining steel material 20 can be changed in various ways. The through holes 23 are also configured to be large enough to allow pre-hardened concrete to pass through.

Next, we will explain the procedure for erecting an inverted support pillar 1 into a pile hole created in the ground using the inverted support pillar erection method of this embodiment when constructing a building with above-ground and underground portions using the inverted construction method.

First, as shown in FIG. 5(a), a pile hole 31 of a predetermined depth is excavated using a drill or other excavation device at the planned location for erecting the inverted support pillar 1 in the ground 30 at a construction site where a building is to be constructed using the inverted construction method. In the illustrated example, the shape of the pile hole is cylindrical with an expanding diameter only at the bottom, but the shape can be changed as appropriate. Next, as shown in FIG. 5(b), a reinforcing bar 32 is erected at a predetermined position on the bottom side of the pile hole 31.

Next, as shown in FIG. 1, the precision-maintaining steel material 20 extending downward is fixed to the lower end of the root portion 3 of the inverted support 1. The precision-maintaining steel material 20 may be fixed to the member that constitutes the root portion 3 of the inverted support 1 in advance at the factory, or may be fixed to the lower end of the root portion 3 of the inverted support 1 at the construction site.

Also, pliers 10 are attached to the upper end of the reverse drive support 1.

Next, as shown in FIG. 6(a), the inverted support 1 with the precision-maintaining steel material 20 fixed to its lower end is hung by a crane (not shown) using a wire 33 connected to the hanging hook 11 of the pliers 10, and inserted into the pile hole 31 from its lower end. At this time, a stand 34 is installed above the opening of the pile hole 31, and the inverted support 1 and the pliers 10 are guided by guide rollers 35 provided on the stand 34 while being inserted into the pile hole 31 in a vertical position. In addition, multiple pantograph-type jacks 36 are attached to the outer periphery of the inverted support 1 in positions facing each other across the axis of the inverted support 1.

When the reverse driving support 1 is inserted to a position where its lower end reaches a predetermined depth in the pile hole 31, the stopper 12 is supported by the stand 34, and the reverse driving support 1 is held in that position. The vertical position of the reverse driving support 1 is adjusted by the journal jack 37 provided on the stand 34. Next, multiple pantograph-type jacks 36 are opened and the jacks 36 are abutted against the wall of the pile hole 31. When the reverse driving support 1 is inserted to a predetermined depth in the pile hole 31, the pliers 10 are supported by the guide rollers 35, so that the reverse driving support 1 is supported in a vertical position by the jacks 36 and guide rollers 35 that are separated vertically. By adjusting the degree of opening of the left and right pantograph-type jacks 36 and the position of the guide rollers 35, the verticality of the reverse driving support 1 is appropriately adjusted so that it is within a predetermined range. The verticality of the inverted support pole 1 can be measured using an inclinometer (not shown) attached to the outer periphery of the inverted support pole 1.

Next, a tremie pipe 38 is erected in the pile hole 31, and concrete 39 is poured into the pile hole 31 through the tremie pipe 38, fixing the precision-maintaining steel material 20 and the embedded portion 3 to the hardened concrete 39, i.e., the cast-in-place concrete pile in which the reinforcing bar 32 is embedded.

The concrete 39 is gradually poured into the pile hole 31 at a predetermined pouring speed, so that, as shown in FIG. 6(b), before the height of the concrete 39 poured into the pile hole 31 from the bottom of the pile hole 31 reaches the root portion 3 of the inverted-casting support 1, the precision-maintaining steel material 20 is embedded in the unhardened concrete 39 and fixed to the hardening concrete 39 from below. As a result, the inverted-casting support 1 is supported in the pile hole 31 via the hardened concrete 39 in the precision-maintaining steel material 29 fixed to the lower end of the root portion 3, before the concrete 39 has yet to reach the root portion 3.

When concrete 39 is gradually poured into pile hole 31 from this state at a predetermined pouring speed, as shown in FIG. 7(a), the concrete 39 reaches the root section 3. At this time, the inverted support pillar 1 is supported in pile hole 31 via the hardened concrete 39 at the precision-maintaining steel material 29 fixed to the lower end of the root section 3. Therefore, even if the unhardened concrete 39 flows due to height deviations and this flow applies lateral pressure to the root section 3, the inverted support pillar 1 is precisely maintained in a vertical position without being displaced by the lateral pressure.

Then, concrete 39 is gradually poured into the pile hole 31 at a predetermined pouring speed until the concrete 39 reaches the height of the upper end of the embedded section 3, as shown in FIG. 7(b). The inverted support column 1 is then fixed to the precision-maintaining steel material 29 and the hardened concrete 39 in the embedded section 3, i.e., the cast-in-place concrete pile in which the reinforcing bar 32 is embedded.

In this way, according to the method for erecting the inverted support of this embodiment, the precision-maintaining steel material 20 extending downward is fixed to the lower end of the root portion 3 of the inverted support 1, and the inverted support 1 with the precision-maintaining steel material 20 fixed thereto is inserted into the pile hole 31, and then concrete 39 is poured into the pile hole 31 to fix the precision-maintaining steel material 20 and the root portion 3 to the concrete pile. This prevents the inverted support 1 from shifting out of position due to the flow of the unhardened concrete 39, and allows the inverted support 1 to be erected accurately into the concrete pile.

The precision-maintaining steel material 20 is thinner than the root portion 3 of the inverted support 1. Therefore, when the precision-maintaining steel material 20 is embedded in unhardened concrete 39, even if the concrete 39 flows, the lateral pressure that the precision-maintaining steel material 20 receives from the concrete 39 is smaller than the lateral pressure that the root portion 3 receives, reducing the risk of the inverted support 1 becoming misaligned.

In particular, in the method of erecting a reverse-cast support of this embodiment, if the precision-maintaining steel material 20 is configured to have at least one through hole 23, when the precision-maintaining steel material 20 is embedded in unhardened concrete 39, even if the concrete 39 flows, the concrete 39 can flow through the through hole 23, thereby further reducing the lateral pressure that the precision-maintaining steel material 20 receives from the concrete 39. This prevents the precision-maintaining steel material 20 from shifting out of position when embedded in unhardened concrete 39, and allows the precision-maintaining steel material 20 to be erected more accurately into the concrete pile.

Using the same procedure as above, a predetermined number of inverted support columns 1 required for the building are fixed to the respective concrete piles of a predetermined number of pile holes 31 provided in the ground 30. When all of the inverted support columns 1 have been fixed to the hardened concrete piles of the corresponding pile holes 31, the pile holes 31 are backfilled, and then, as shown in FIG. 8, the work of constructing the aboveground portion 40 of the building supported by the inverted support columns 1 is carried out. At the same time, the ground 30 is excavated to a predetermined depth, and concrete is poured into the bottom from the tremie pipe 38 to form a pressure-resistant plate for the building's underground structure, and the work of constructing the underground portion 41 is carried out.

The present invention is not limited to the above-described embodiment, and it goes without saying that various modifications are possible without departing from the spirit of the invention.

In the above embodiment, the precision-maintaining steel material 20 made of H-shaped steel is fixed to the lower end of the root portion 3 of the box-shaped inverted support 1, but the shape or form of the inverted support 1 and the precision-maintaining steel material 20 can be changed in various ways.

For example, as shown in Figs. 9 and 10, the precision-maintaining steel material 20 made of cross H-shaped steel may be fixed to the lower end of the root portion 3 of the box-shaped inverted support 1. Specifically, the precision-maintaining steel material 20 may have a pair of webs 21 each formed of a thick plate in an elongated rectangular shape and perpendicular to each other at the center position in the width direction, and four flanges 22 each formed of a thick plate in an elongated rectangular shape and connected to both sides of each web 21, so that the cross-sectional shape perpendicular to the vertical direction is a uniform cross H shape from the upper end to the lower end. Even in this case, it is preferable that the precision-maintaining steel material 20 is configured to have at least one through hole 23, for example, a configuration in which each of the pair of webs 21 has five circular through holes 23 that penetrate the web 21 horizontally and are arranged at equal intervals in the vertical direction. By configuring the precision-maintaining steel material 20 as a cross H-shaped steel, it is possible to make the precision-maintaining steel material 20 symmetrical in all directions and difficult to move inside the concrete 39. In addition, multiple studs 24 may be attached to the outward facing surfaces of the pair of left and right flanges 22 to integrate the precision-maintaining steel material 20 with the concrete 39.

In addition, in this embodiment, the inverted support 1 is box-shaped, but the inverted support 1 may be configured to be made of cross H-shaped steel. Specifically, as shown in Figures 11 and 12, the inverted support 1 may have a pair of webs 1a that are each formed into an elongated rectangular shape using thick plates and perpendicular to each other at the center position in the width direction, and four flanges 1b that are each formed into an elongated rectangular shape using thick plates and connected to both sides of each web 1a, and the cross-sectional shape perpendicular to the vertical direction may be a uniform cross H shape from the top to the bottom.

Furthermore, when the inverted support 1 is configured to be formed from cross H-shaped steel, the precision-maintaining steel material 20 may be formed from H-shaped steel as shown in FIG. 11, or the precision-maintaining steel material 20 may be formed from cross H-shaped steel as shown in FIG. 13. In either case, it is preferable that the precision-maintaining steel material 20 is formed thinner than the inverted support 1.

Reference Signs List 1: inverted support 1a: web 1b: flange 2: stud 3: embedded portion 4: bottom end blocking wall 10: pliers 11: hanging hook 12: stopper 20: precision-maintaining steel material 21: web 22: flange 23: through hole 24: stud 30: ground 31: pile hole 32: reinforcing bar 33: wire 34: frame 35: guide roller 36: jack 37: journal jack 38: tremie pipe 39: concrete 40: aboveground portion 41: underground portion

Claims (2)

A method for erecting a reverse-cast support pillar in a pile hole provided in the ground, comprising:
A step of erecting a reinforcing bar at a predetermined position on the bottom side of the pile hole;
A step of fixing a precision-maintaining steel material extending downward to a lower end of the root portion of the inverted support;
A step of inserting the reverse-cast support to which the precision-maintaining steel material is fixed into the pile hole;
A method for erecting an inverted support, comprising the steps of: inserting the inverted support to which the precision-maintaining steel material is fixed into the pile hole; and then pouring concrete into the pile hole to fix the precision-maintaining steel material and the embedded portion to a cast-in-place concrete pile. The method for erecting a reverse-driven support pillar according to claim 1, wherein the precision-maintaining steel material has at least one through hole.

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