JPH11229403A - Connection method of existing pile and new foundation - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a connection method of an existing pile and a newly installed foundation, by which the axial force from a structure can be securely transferred between the existing pile and the new foundation without a change with the passage of time, in the base isolation of the existing structure supported by the pile foundation in the foundation part. SOLUTION: The periphery of an existing pile 10 of an existing structure supported by a pile foundation is excavated and a new foundation 4 is constructed around the lower part of the existing pile 10 exposed in the excavated part. Thereafter, the existing pile 10 exposed on the new foundation 4 is cut off and a base isolation device is interposed, and the load of the existing structure is supported by the existing piles 10 through the base isolation device and the new foundation 4. In this case, fixing jigs 11, 12, 13 protruded from the outer peripheral face of the existing pile 10 are fixed to the outer periphery of the existing pile 10 in the part to be embedded in the new foundation 4. Thereafter, the new foundation 4 is placed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for joining an existing pile and a new foundation, which is suitable for use in seismic isolation of an existing building using a pile foundation.

[0002]

2. Description of the Related Art In recent years, there has been an increasing demand for seismic isolation of various structures. For existing structures, a seismic isolation device such as a laminated rubber is interposed on the foundation of the structure. In addition, various seismic isolation methods have been developed to absorb vibrations that propagate from the ground to a structure due to an earthquake, thereby reducing stress and deformation occurring in the superstructure. Among such seismic isolation methods for existing structures, as shown in FIG. 2, existing structures 2 supported by a large number of piles 1.
In the case of seismic isolation in the base part, first, as shown in FIG. 3, the earth and sand 3 around and below the base part are excavated, and then, as shown in FIG. After constructing the new foundation 4 with a predetermined distance from the lower surface, a temporary member (not shown) such as a support jack is interposed between the new foundation 4 and the structure 2 to temporarily support the load of the structure. Then, in this state, the new foundation 4
The existing pile 1 exposed between the building and the structure 2
5, the seismic isolation device 5 is interposed as shown in FIG. 5, and then the temporary member is removed, so that the load of the structure 2 is reduced via the seismic isolation device 5 and the new foundation 4. The construction method of supporting with the pile 1 is adopted.

[0003]

By the way, in such a conventional seismic isolation method of an existing building using a pile foundation,
When seismic isolation is completed, existing pile 1 is replaced with new foundation 4
Therefore, transmission of the axial force between the existing pile 1 and the new foundation 4 not directly located below the seismic isolation device 5 becomes a problem. Therefore, when the existing pile 1 is cast-in-place concrete, before the new foundation 4 is cast, the outer peripheral surface of the existing pile 1 is usually roughened 6 as shown in FIG.
Although the transmission of the axial force is ensured by increasing the adhesion between the concrete and the concrete, the effect of improving the adhesion is limited.

[0004] In addition, the existing pile is precast (P
C) When the pile 10 is used, such roughening cannot be performed. For this reason, the adhesiveness between the newly installed foundation 4 and the concrete is similarly enhanced by spraying or applying an adhesive 7 having high adhesiveness to the outer peripheral surface of the PC pile 10 in general. There is a concern that the adhesion will decrease due to the change. For this reason, when seismic isolation of an existing building using this type of pile foundation is required, particularly, a means for transmitting a strong axial force between the existing piles 1 and 10 and the new foundation 4 is demanded.

SUMMARY OF THE INVENTION The present invention has been made in response to such a demand. When an existing structure supported by a pile foundation is made seismic-isolated at the foundation, the axial force acting on the structure is subject to aging. It is an object of the present invention to provide a method for joining an existing pile and a new foundation, which can be surely transmitted between the new foundation and the existing pile.

[0006]

According to a first aspect of the present invention, there is provided a method for joining an existing pile and a new foundation according to the present invention, wherein the excavation is performed around an existing pile of an existing structure supported by the pile foundation. After constructing a new foundation around the lower part of the existing pile exposed at the site, the existing pile exposed on the new foundation is cut and seismic isolation devices are interposed, and the load of the existing structure is passed through the seismic isolation device and the new foundation. A method of joining an existing pile and a new foundation when supporting the existing pile with the existing pile, wherein a locking jig protruding from the outer peripheral surface of the existing pile is provided on the outer periphery of the existing pile at a portion buried in the new foundation. After fixing, a new foundation is cast.

Here, the invention according to claim 2 is characterized in that the existing pile is a PC pile, and the invention according to claim 3 is according to claim 1 or 2. In the invention of the above, wedges are arranged on the outer periphery of the existing pile, a ring plate is installed around the tip of the wedge, the wedge and the ring plate are integrated, and stud bolts are fixed to the outer periphery of the ring plate. Thus, the above-mentioned locking jig is constituted.

In the invention according to any one of the first to third aspects, since a locking jig projecting therefrom is fixed to the outer periphery of the existing pile and a new foundation is cast, seismic isolation is achieved. After completion, the load of the structure transmitted from the seismic isolation device to the new foundation can be reliably transmitted to the existing pile via the integrated locking jig embedded in the new foundation. Become. Further, since the connection by the locking jig is a mechanical connection structure, there is no possibility that the transmission force is reduced due to aging.

Therefore, the invention according to claim 1 can obtain excellent effects even when the existing pile is cast-in-place concrete, but in particular, as in the invention according to claim 2, When the pile is a PC pile that cannot be roughened, it has a remarkable effect.

[0010] In such a PC pile, since concrete is compacted by centrifugal force, it is difficult to directly fix the locking jig to the outer peripheral surface. In this regard, as in the invention according to claim 3, the locking jig is constituted by a wedge and a ring plate, and a ring plate is installed around the tip of the wedge arranged on the outer periphery of the existing pile, and If the wedge and the ring plate are integrated by, for example, driving the plate into the wedge side, the locking jig can be easily and firmly fixed to the outer periphery of the PC pile. Further, by fixing the stud bolt to the outer periphery of the ring plate, the transmission of the axial force between the new foundation and the PC pile is further ensured.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 illustrates an embodiment in which the method for joining an existing pile and a new foundation according to the present invention is applied to a case where an existing building 2 supported by a PC pile 10 is subjected to seismic isolation. FIG. 2 is a longitudinal sectional view of a main part for carrying out. In the following description, since the general seismic isolation method is the same as that shown in FIGS. 2 to 5, the same reference numerals are given and the description is omitted. In this embodiment, first, FIGS.
In the same manner as described above, the foundation 3 in the existing structure 2 and the earth and sand 3 around the PC pile 10 are excavated. Next, as shown in FIG. 1, a plurality of wedges 11 are arranged at equal intervals in the circumferential direction on the outer periphery of the existing PC pile 10 exposed at the excavated portion. At this time, the sharp end (tip) 1 of the wedge 11
1a is arranged upward. Next, a semicircular ring plate 12 divided into two parts is installed around the sharp ends 11a of the wedges 11, and the ends are joined together by welding or high-strength bolts.

A plurality of stud bolts 13 are driven around the outer periphery of the ring plate 12. Next, the ring plate 12 to which the stud bolts 13 are fixed is beaten downward so that the wedge 11
And are fixed integrally via. As described above, the PC pile 1
A locking jig including a wedge 11, a ring plate 12, and a stud bolt 13 is fixed to the outer periphery of the zero.

Next, the new foundation 4 is constructed by placing foundation concrete below the excavated portion.
Further, a temporary member such as a support jack (not shown) is interposed between the new foundation 4 and the structure 2 to temporarily support the load of the structure 2. In this state, the portion 10a exposed between the new foundation 4 and the structure 2 of the PC pile 10 is provided.
At the position of the upper surface of the new foundation 4 shown by the dotted line in FIG.
The seismic isolation device 5 is interposed in this portion, and the temporary member is removed, whereby the load of the structure 2 is supported by the existing PC pile 10 via the seismic isolation device 5, the new foundation 4 and the locking jig.

According to the joining method of the existing PC pile and the new foundation 4 having the above-described configuration, the ring base 12 and the stud bolt 13 protruding from the existing PC pile 10 are fixed to the outer periphery of the existing PC pile 10 to strike the new foundation 4. When the load of the structure 2 is transmitted from the seismic isolation device 5 to the new foundation 4 after the seismic isolation is completed, the ring plate 12 and the stud bolt embedded in the new foundation 4 are installed. 13
In addition, a downward load is applied integrally with the new foundation 4. Then, the sharp end 1 is located below the ring plate 12.
Since the wedges 11 are arranged with the upper surface 1a facing upward, the direction of the load is the direction in which the wedges 11 act.
It is transmitted to the C pile 10.

Thus, the existing PC pile and the new foundation 4
According to the joining method, the axial force acting on the new foundation 4 is
The transmission can be reliably transmitted to the existing PC pile 10 via the wedge 11, the ring plate 12, and the stud bolt 13. In addition, the wedge 11, the ring plate 12
Since the connection by the stud bolt 13 is a mechanical connection structure, there is no fear that the transmission force is reduced by aging.

In the above embodiment, only the case where the existing pile is the PC pile 10 has been described. However, the present invention is not limited to this, and the present invention is applicable to the existing pile 1 made of cast-in-place concrete. It can be applied, and a similar effect can be obtained. Further, in the above-described embodiment, the case where the locking jig protruding from the existing pile is constituted by the wedge 11, the ring plate 12, and the stud bolt 13 is described. Various forms can be applied as long as they protrude outward and are buried integrally in the new foundation 4.

[0017]

As described above, according to the method for joining an existing pile and a new foundation according to any one of claims 1 to 3,
The axial force acting on the new foundation can be reliably transmitted to the existing pile via the locking jig, and the connection by the locking jig is a mechanical connection structure. There is no danger that the transmission force will decrease. Therefore, the present invention has a remarkable effect particularly when the existing pile is a PC pile, as in the second aspect of the present invention.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing a new foundation part constructed by an embodiment of a method for joining an existing pile and a new foundation according to the present invention.

FIG. 2 is a longitudinal sectional view showing a foundation portion of a structure based on a general pile foundation.

FIG. 3 is a longitudinal sectional view showing a state where a foundation portion of FIG. 2 is excavated.

FIG. 4 is a longitudinal sectional view showing a state in which a new foundation is cast in the excavation section of FIG. 3;

FIG. 5 is a longitudinal sectional view showing a state in which the exposed existing pile of FIG. 3 is cut and a seismic isolation device is interposed.

[Explanation of symbols]

 4 New foundation 10 Existing PC pile 11 Wedge 11a Sharp end (tip) 12 Ring plate 13 Stud bolt

Claims (3)

[Claims] 1. An existing pile exposed on the new foundation after excavating around the existing pile of the existing structure supported by the pile foundation, constructing a new foundation around a lower part of the existing pile exposed on the excavation part. The method for joining the existing pile and the new foundation when the existing pile is supported by the existing pile through the seismic isolation apparatus and the new foundation by cutting the Fixing the fixing jig protruding from the outer peripheral surface of the existing pile to the portion of the existing pile buried in the new foundation, and then driving the new foundation. How to join with the new foundation. 2. The method according to claim 1, wherein the existing pile is a precast pile. 3. A wedge is provided on the outer periphery of the existing pile, a ring plate is installed around the tip of the wedge, the wedge and the ring plate are integrated, and stud bolts are provided on the outer periphery of the ring plate. 2. The locking jig is constituted by fixing the fixing jig.
Or the joining method of the existing pile and the new foundation described in 2.