JP2002339379A - Method for installing pile-head stress relaxation device to existing structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To rationally assemble a pile-head stress relaxation device into the pile head section of an existing structure, and to improve aseismicity. SOLUTION: When the pile-head stress relaxation device is installed among piles 2 for the existing structure (a distribution basin 1) and a superstructure (a water tank body 3) and earthquake-resistant repair is conducted, shafts 4 are mounted at places in the vicinity of the existing structure, adits (a main adit 5 and branched adits 6) are secured to the lower ground of the existing structure from the shafts, a ground in the periphery of the pile head sections is excavated by works from the insides of the adits and the pile head sections are exposed, and parts of the pile head sections are cut and removed, receiving the superstructure temporarily and the pile-head stress relaxation device is fitted. A device composed of a spherical support and an upper cover set up to the spherical support and supported in a rockable manner in all directions is adopted as the pile-head stress relaxation device, and these spherical support and upper cover are fixed to the lower sections and upper sections of the cut sections of the piles respectively. Brackets are fixed temporarily to the lower sections of the cutting predetermined places of the pile head sections, jacks are installed to the brackets, and the superstructure is received temporarily by the jacks.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pile head stress relaxation device for transmitting an axial force and a shear force between an existing structure and a pile and an upper structure of the existing structure while permitting their relative rotation. A method for installing the

[0002]

2. Description of the Related Art As is well known, a rigid connection between a pile head and an upper structure is conventionally generally performed. However, in the case of a rigid connection, relative rotation of both members is restricted, so that an earthquake occurs. In some cases, a large bending moment acts on the pile head, so that the pile head and joints are required to have not only axial strength but also shear strength, as well as bending strength. I can't get it.

[0003] Therefore, in recent years, instead of rigidly connecting the pile head and the upper structure, the relative rotation of the pile head and the upper structure has been substantially allowed in the form of a pin joint, so that the axial force and the shear force are simply transmitted. A pile head joint structure in which a bending moment is not transmitted while the pile head is being transmitted has been proposed, and various pile head stress relaxation devices for joining a pile head and an upper structure with such a structure have also been proposed.

[0004]

The pile head joint structure and the pile head stress relieving device described above have been widely adopted when newly constructing a structure. Recently, however, not only newly constructed structures but also existing structures have been used. There is a demand to improve the seismic performance by applying such structures and devices to structures, and therefore, development of effective and appropriate methods for incorporating such devices into pile heads of existing structures Is desired.

[0005]

SUMMARY OF THE INVENTION In view of the above circumstances, the invention of claim 1 is directed to an existing structure, in which an axial force and a shear force are allowed between the pile and the upper structure while allowing relative rotation between the pile and the upper structure. When installing a pile head stress relieving device that transmits heat, a vertical shaft is provided near the existing structure, a horizontal shaft is provided from the vertical shaft to the ground below the existing structure, and work around the pile head is performed from inside the horizontal shaft. Excavating the ground and exposing the pile head, cutting and removing a part of the pile head while temporarily supporting the superstructure supported by each pile, and installing a pile head stress relief device there It is characterized by.

According to a second aspect of the present invention, there is provided a method for installing a pile head stress relaxation device on an existing structure according to the first aspect of the present invention, wherein the pile head stress relaxation device is mounted on the ball seat and mounted on the ball seat in all directions. A swingable upper lid is used, and the ball seat and the upper lid are fixed to the lower and upper portions of the cut portion of the pile, respectively.

According to a third aspect of the present invention, in the method for installing a stress relief device for a pile head on an existing structure according to the first or second aspect of the present invention, when a part of the pile head is cut and removed, a position to be cut is determined. The bracket is temporarily fixed to a lower portion, a jack is installed on the bracket, and the upper structure is temporarily received by the jack.

[0008]

1 to 7 show an embodiment of the present invention.
This will be described with reference to FIG. In this embodiment, the present invention is applied to an existing seismic retrofitting work for an existing reservoir 1 provided in a water purification plant, and an existing pile 2 and a reinforced concrete tank as an upper structure supported by the pile 2 are provided. This is an application example in the case where a later described pile head stress relaxation device is installed between the main body 3 and the main body 3.

In this embodiment, first, as shown in FIG.
A shaft 4 is provided at a position close to the reservoir 1 (in this example, two places on both sides) and excavated. A main shaft 5 that crosses the lower part of the water tank body 3 from the bottom of the shaft 4 is excavated. A large number of branch shafts 6 are excavated between the pit 5 and the pile 2, and the ground around the pile head of the pile 2 is digged as shown in FIG. To expose.

The water tank body 3 supported by each of the piles 2
While temporarily accepting, a part of the pile head is cut and removed, and a pile head stress relaxation device is installed there. That is, as shown in FIG. 3, the bracket 7 is temporarily fixed to the lower part of the planned cutting position, the jack 8 is installed on the bracket 7, and the water tank main body 3 is temporarily received by the jack 8. The bracket 7 in this example has a half-ring body 7a made of a steel frame material connected to its base, and these half-ring bodies 7a are connected to each other and mounted around the pile head by a wedge 7b. 7 is temporarily fixed firmly to the pile head. The jack 8 is installed upward on the bracket 7 via the height adjustment stand 9 and supports the bottom surface of the water tank main body 3. Reference numeral 10 denotes a displacement gauge for measuring the position of the water tank main body 3 and adjusting the stroke of the jack 8.

With the water tank body 3 temporarily received by the jack 8 as described above, the pile head is cut at two places as shown in FIG. 4, and a part of the pile head is cut as shown in FIG. Remove. Then, a pile head stress relieving device 12 is installed in the cut portion 11 as shown in FIG.

As shown in FIG. 7, the pile head stress relieving device 12 in this embodiment comprises a ball seat 13 and an upper lid 14 mounted on the ball seat 13 and supported so as to swing in all directions. The ball seat 13 and the upper lid 14 are each cut into
1 is fixed to a lower part and an upper part via a fixing member 15. The fixing member 15 includes the ball seat 13 and the upper lid 1.
Steel plate 1 attached to bolt 4 with bolts and nuts
6 and a half steel pipe 17 welded to the periphery thereof.
Are respectively attached by bolts 18 and the steel plates 16
Are attached to the upper and lower cut surfaces of the cutting portion 11, respectively, and a half steel plate 17 is welded around each of the steel plates 16 to assemble, and the gap between the fixing member 15 and the pile head is not shrunk. A filler such as mortar is filled.

After the pile head stress relieving device 12 is installed in the above procedure, the jack 8 and the bracket 7 are removed, and a cover 19 for preventing earth and sand from flowing around the ball seat 13 and the upper lid 14 is attached. As the coating 19, a material made of a flexible material that does not restrict the operation of the pile head stress relaxation device 12, for example, styrene foam, can be suitably used. When the above operation is completed for all piles 2, around the pile head,
The construction is completed by backfilling the branch shaft 6, the main shaft 5, and the shaft 4.

The installation of the bracket 7 and the jack 8,
The installation of the pile head stress relaxation device 12 and the removal of the jack 8 and the bracket 7 are sequentially performed for each pile 2, and the removed bracket 7 and the jack 8 may be diverted to another pile 2, or all After the bracket 7 and the jack 8 are installed on the pile 2 and all the pile head stress relieving devices 12 are installed, all the jacks 8 and the bracket 7 may be removed. Further, by dividing the construction section, the backfilling work can be performed in parallel with the installation work of the pile head stress relaxation device 12.

As described above, the distribution reservoir 1 which is the existing structure
By installing the pile head stress relaxation device 12 at the pile head in the above, an excessive bending moment is not generated at the pile head, and therefore, the conventional method of reinforcing the pile itself or the pile head or adding a pile is used. The seismic resistance of the pile foundation can be improved without depending on the reinforcing method.

According to the above-described embodiment, the branch shaft 6 provided below the distribution reservoir 1 which is an existing structure to be repaired.
Since the work is performed from the inside, there is no need to make any changes to the reservoir 1 itself, so that construction can be performed while using the reservoir 1 as it is. In addition, according to the above embodiment, it is only necessary to cut and remove a part of the pile head and install the pile head stress relaxation device 12 there, and in this case, the water tank body 3 as the upper structure is jacked by the jack 8. It can be temporarily received without any trouble, so no extraordinary and complicated work is required, and no large heavy equipment is required except for excavation of the shaft 4, main horizontal shaft 5, and branch horizontal shaft 6. And effective.

The present invention can be applied not only to the above-mentioned seismic retrofitting work for the reservoir, but also to the work having a pile foundation and excavating the lower ground to provide a horizontal shaft. Naturally, it can be widely applied to existing structures of various uses, scales and forms, as long as it is of a suitable form, as well as the installation form of vertical shafts and horizontal shafts, the form of temporary receiving of existing structures, and adoption. Needless to say, the configuration of the pile head stress relaxation device to be performed, the specific working steps, and the like can be appropriately changed without being limited to the above embodiment.

[0018]

According to the first aspect of the present invention, it is possible to improve the seismic resistance of the existing structure by installing the pile head stress relaxation device at the pile head, and also to carry out the work with the existing structure. A vertical shaft is provided at a position close to the structure, and a horizontal shaft is provided below the existing structure from the vertical shaft, and the ground around the pile head is excavated by working from the horizontal shaft to expose the pile head, and each pile is exposed. While temporarily receiving the upper structure supported by the company, a part of the pile head was cut and removed, and a pile head stress relief device was installed there. There is no need to add them, so construction while using the existing structure as it is is possible, and no extraordinary and complicated work is required, which is extremely reasonable and effective.

According to the second aspect of the present invention, a pile head stress relieving device having a structure comprising a ball seat and an upper lid mounted on the ball seat and supported so as to swing in all directions is adopted. Since the seat and the top lid are fixed to the lower and upper parts of the cut section of the pile, respectively, the transmission of bending moment at the pile head can be reliably cut off by the pile head stress relaxation device, and the installation work is also easy and reliable. Can do.

According to the third aspect of the present invention, when cutting and removing a part of the pile head, the bracket is temporarily fixed below the expected cutting position, the jack is installed on the bracket, and the upper structure is temporarily fixed by the jack. As a result, the upper structure can be temporarily and easily temporarily received by the jack without any trouble.

[Brief description of the drawings]

FIG. 1 shows an embodiment of the method of the present invention, and shows a state in which a horizontal shaft is provided in the ground below an existing structure to be repaired.

FIG. 2 is a diagram showing a state in which a pile head is exposed.

FIG. 3 is a view showing a state in which the upper structure is temporarily received by a jack.

FIG. 4 is a diagram showing a cutting position of a pile head.

FIG. 5 is a view showing a state where the pile head is cut and removed.

FIG. 6 is a diagram showing a state in which the pile head stress relaxation device is installed.

FIG. 7 is a view showing a pile head stress relaxation device.

[Description of Signs] 1 Reservoir (existing structure) 2 Pile 3 Main body of tank (upper structure) 4 Vertical shaft 5 Main horizontal shaft (horizontal shaft) 6 Branch horizontal shaft (horizontal shaft) 7 Bracket 8 Jack 11 Cutting part 12 Piles Head stress relaxation device 13 Ball seat 14 Top cover 15 Fixing member

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Hideyuki Mano 1-3-2 Shibaura, Minato-ku, Tokyo Shimizu Corporation F-term (reference) 2D046 CA01 DA11 DA12 2E176 AA01 BB28

Claims (3)

[Claims] When installing a pile head stress relaxation device for transmitting an axial force and a shear force while allowing relative rotation between the pile and an upper structure for an existing structure,
A vertical shaft is provided at a position close to the existing structure, and a horizontal shaft is provided below the existing structure from the vertical shaft, and the ground around the pile head is excavated by work from within the horizontal shaft to expose the pile head, Pile head stress relief for existing structures characterized by cutting and removing a part of the pile head while temporarily receiving the superstructure supported by each pile and installing a pile head stress relief device there How to install the device. 2. A pile head stress relieving device comprising a ball seat and an upper lid mounted on the ball seat and supported so as to be swingable in all directions, wherein the ball seat and the upper lid are respectively lower and upper portions of a cut portion of the pile. The method according to claim 1, wherein the pile head stress relief device is installed on an existing structure. 3. When cutting off a part of a pile head, a bracket is temporarily fixed to a lower portion of a planned cutting position, a jack is installed on the bracket, and the upper structure is temporarily received by the jack. A method for installing a pile head stress relaxation device on an existing structure according to claim 1 or 2.