JP2006291607A - Foundation reinforcing method for existing structure - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a simple method for reinforcing earthquake resistance of an existing structure at low cost. <P>SOLUTION: In this method for providing a new row of piles around the existing structure to increase horizontal resistance strength of the existing structure, one tip supporting pile or more and one friction pile or more are driven, respectively, these piles and a foundation of the existing structure are mutually connected by a beam to increase earthquake resistance of the existing foundation, and self weight by connection of the friction pile and the beam is supported by the tip supporting pile to avoid application of load on the existing foundation. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a foundation pile for a building, and more particularly to a seismic reinforcement method for increasing the horizontal strength of an existing foundation.

  In recent years, there has been a growing demand for earthquake resistance of buildings, and in particular, reinforcement of existing foundations designed under the old earthquake resistance regulations is required.

For foundations of structures designed under the old seismic code, it may be judged that the horizontal strength and horizontal rigidity of pile foundations are insufficient if they are evaluated based on the current standards.
On the other hand, in foundations where a large load has been applied to many piles due to the earthquake, the horizontal rigidity is greatly reduced due to plastic deformation of the piles, and even if the piles are not broken, It is also conceivable that the deformation becomes larger than expected. Under such circumstances, it may be necessary to increase the horizontal strength and the horizontal rigidity.

  One method for reinforcing the foundations of existing structures with low or reduced horizontal strength and horizontal rigidity is a method of directly reinforcing the foundations and piles by excavating the bottom ends of the foundations. However, such a method often requires enormous labor and cost. Furthermore, for soft ground, the pile may sink with time and the stress applied to the footing may increase, which is a major obstacle when reinforcing the foundation.

  Therefore, it is required to perform seismic reinforcement of existing foundations economically.

  In view of the above problems, the present invention provides a pile row around an existing structure, so that the horizontal strength of the foundation of the existing structure can be easily increased without requiring enormous labor and cost such as excavation of the lower end of the foundation. A method capable of improving horizontal rigidity is provided.

  To this end, the present invention is a method for seismic reinforcement of an existing foundation, in which one or more tip support piles and friction piles are driven in, and the piles and foundations of existing structures are connected with beams to seismicize the existing foundation. We propose a seismic reinforcement method for existing structures that increases the performance and avoids the load on the existing foundation by supporting the dead weight by connecting the friction pile and the beam with the tip support pile.

  Further, a method of reducing torsion occurring in the foundation by arranging the tip support pile or the friction pile so that the point of action of the seismic horizontal force acting on the foundation coincides with or approaches the rigid center of the element resisting the seismic horizontal force Also provide. By these, higher strength can be obtained. A structure using these methods is also provided.

  The present invention is a method for increasing the seismic strength of an existing structure at a low cost, which will be described below with reference to the drawings.

  FIG. 1 is a cross-sectional view showing a first embodiment of the present invention. The existing pile 6 is driven into the soft ground 2, and the pile 6 reaches the hard rock 5. Building 1 is built on top of this. Next, the reinforcing foot 3 is driven into the foundation footing 7 and is installed thereon. Further, the tip support pile 4 for reinforcement is driven so as to reach the hard rock. Connect the basic footing to this as well. As a result, the stress on the foundation footing due to its own weight due to the connection structure between the friction pile and the beam can be greatly reduced.

  FIG. 2 is a top view of the first embodiment. A new pile is driven around the existing pile 6. The friction pile 3 and the tip support pile 4 are arranged in a grid so as to be adjacent to each other. In this way, the force applied to the foundation of the building can be dispersed. Also, as shown in the figure, by connecting to the beam 8, a portal ramen structure composed of a pile, a beam, and a foundation footing can be obtained, and the stress applied to the existing foundation can be greatly reduced as compared with the case of a single row. .

  The present Example shown by FIG. 3, 4 is the figure which showed the method of disperse | distributing and arranging a new pile. In FIG. 3, the number of friction piles 3 is one on the left side of the building, but two on the right side. The top view of this is FIG. In the area 14 of FIG. 4, new piles are dispersed, and the area 9 is intensively arranged. Thereby, the rigid center position 10 only in the existing pile moves to the rigid center position 11 by the installation of the new pile, which approaches the center of gravity position of the foundation. As a result, the point of action of the seismic horizontal force acting on the foundation, that is, the center of gravity of the foundation and the stiffness center of the element resisting the seismic horizontal force can be matched or brought closer, and the torsion of the foundation during an earthquake can be reduced.

  In this embodiment, the friction piles 3 are arranged unevenly, but the tip support piles can be arranged unevenly. Long piles can be placed evenly and friction piles can be placed unevenly.

FIG. 1 is a cross-sectional view of a first embodiment of the present invention. FIG. 2 is a top view of the first embodiment of the present invention. FIG. 3 is a cross-sectional view of a second embodiment of the present invention. FIG. 4 is a top view of the second embodiment of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Existing structure 2 Soft ground 3 Friction pile 4 Tip support pile 5 Hard bed 6 Existing pile 7 Foundation footing 8 Beam 9 Pile dense area 10 Rigid position only with existing pile 11 Rigid position with new pile 13 Existing structure Center of gravity position 14 Area where piles are dispersed

Claims (3)

  It is a seismic strengthening method for existing foundations. One or more tip support piles and friction piles are driven in, and these piles and existing structure foundations are connected with beams to increase the earthquake resistance of the existing foundations. A seismic reinforcement method for existing structures that avoids the load from being applied to existing foundations by supporting its own weight due to the connection between friction piles and beams.   The tip support pile or the friction pile is arranged such that the point of action of the seismic horizontal force acting on the foundation and the stiffness center of the element resisting the seismic horizontal force are aligned or close to each other, thereby reducing torsion occurring in the foundation. The method according to 1.   With one or more tip support piles and friction piles provided around the existing foundation, and a connection structure connecting these piles and the existing foundation with beams, increasing the earthquake resistance of the existing foundation, Seismic strengthening structure of existing structure that avoids load on existing foundation by supporting its own weight due to connection of friction pile and beam with tip support pile.

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