JP3711527B2 - Reinforcement method of existing building foundation with slant pile - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention belongs to the technical field of a method for reinforcing an existing building foundation with diagonal piles, and more specifically, relates to a method for retrofitting an existing building foundation by using a group pile consisting of two diagonal piles.
[0002]
[Prior art]
In the case of a pile foundation building, the pile must bear and bear both a vertical load (building weight) and a horizontal load (seismic force). Pile foundations for buildings built after the mid-1980s have been designed to take account of both loads, but pile foundations for buildings built before that are not designed for horizontal loads. General and low earthquake resistance.
[0003]
In addition, sandy ground with a shallow groundwater level may cause liquefaction. When the liquefaction phenomenon occurs, the resistance of the ground to the pile becomes extremely small, so that the resistance to the load in the horizontal direction is rapidly reduced. Regarding this liquefaction phenomenon, its stability is generally not examined until the 1990s.
Therefore, existing buildings before the above-mentioned age are strongly required to reinforce their foundations from the viewpoint of seismic performance against seismic force and stability against liquefaction.
[0004]
Next, the present applicant has devised a slant pile construction method in which the pile is inclined with respect to the vertical line and strongly resists horizontal forces such as seismic force, and (1) JP-A-7-90830, (2) JP-A No. 7-90860 and {circle around (3)} Japanese Laid-Open Patent Publication No. 8-170346 disclose oblique pile type artificial ground, respectively. In the above publications (2) and (3), a set pile in which two diagonal piles are arranged symmetrically by changing the direction of the plane by 180 degrees and the pile heads of the diagonal piles are connected to each other is disclosed. Has been.
[0005]
As shown in FIG. 7, the assembled pile can expect the horizontal resistance force (F) obtained by the formula of F = 2Rsin θ with respect to the axial resistance force (R) of each slant pile 1, 1. It is applied. Since the two slant piles 1 and 1 are arranged symmetrically in a plane, the vertical force of the pair of slant piles 1 and 1 is offset in the opposite direction to form a stable frame. In addition, the stress generated in each slant pile 1, 1 is mainly tensile stress or compressive stress, and there is an advantage that bending moment (approximate solution is M = 0) and shear stress are small due to structural characteristics of the pile pile. .
[0006]
However, there is no prior art relating to a method of applying a group pile composed of diagonal piles to an existing building and reinforcing the existing building foundation in the future.
[0007]
[Problems to be solved by the present invention]
The purpose of the present invention is to increase horizontal resistance by constructing a group pile consisting of two diagonal piles in the ground near the foundation of an existing building and supporting the vertical load of the building on the pile head of the group pile Provide a method for reinforcing existing building foundations with diagonal piles, which can improve the seismic performance of existing building foundations against seismic forces and can maintain the stability against liquefaction phenomenon permanently. That is.
[0008]
[Means for Solving the Problems]
As a means for solving the problems of the prior art, the method for reinforcing an existing building foundation with a diagonal pile according to the invention described in claim 1 is a method of planarly arranging two diagonal piles in the ground near the foundation of the existing building. and applying a Kumikui by symmetrically arranged connecting the pile head ends of the piles by changing the substantially 180 degrees inward, and applying a first footing linked the pile head of the set piles, just above the A second footing integrated with the foundation of the existing building is installed at the position, and a hydraulic jack and a support jack are provided substantially vertically between the first footing and the second footing. The hydraulic jack serves as the foundation of the existing building. The first footing that connects the pile heads of the piles is applied to part or all of the acting vertical load, and the second footing that is integrated with the foundation of the existing building is installed immediately above the first footing. 1 footing and 2nd footing A hydraulic jack and a support jack are provided substantially vertically, and part or all of the vertical load acting on the foundation of the existing building is replaced with the above-mentioned piles by the hydraulic jack, and the rearrangement state is also supported by the support. After fixing with a jack, the hydraulic jack is removed, concrete is placed between the first footing and the second footing, and the support jack is buried to kill the pile head of the group pile and the existing building. load transfer and foundation can be characterized and rigid connection to Turkey.
[0009]
The invention according to claim 2 is the reinforcing method of the existing building foundation by the inclined pile according to claim 1, wherein the foundation of the existing building is a footing .
[0010]
The invention described in claim 3 is the reinforcement method of the existing building foundation by the slant pile described in claim 1, wherein the foundation of the existing building is a foundation beam.
[0011]
BEST MODE FOR CARRYING OUT THE INVENTION
As shown in FIGS. 1 and 2, the method for reinforcing an existing building foundation with diagonal piles according to the present invention is generally applied to the outer peripheral portion of the existing building 2 in the pile foundation 3 of the existing building 2 including the pile 4. This is preferably implemented for the footing 3a. However, the implementation location is not limited to the footing 3a in the outer peripheral portion, but can be suitably applied to the foundation beam 3b in the outer peripheral portion of the existing building 2 as well. As shown in FIG. 2, the assembled piles A and B composed of two diagonal piles have a direction that the resistance force in the vertical plane where the piles are inclined is very large. Are arranged in two orthogonal directions of X and Y.
[0012]
Next, the construction process for implementing the reinforcing method of the present invention will be described. The ground 5 in the vicinity of the outer surface of each footing 3a located in the outer peripheral part of the existing building 2 is excavated, and the two slant piles 1 and 1 are symmetrically arranged in the ground with their directions changed by approximately 180 degrees. To construct. Then, the pile heads of the two diagonal piles 1, 1 are connected to each other and constructed as a pile pile A, B. After that, the pile heads of the group piles A and B and the footing 3a of the existing building 2 are rigidly connected so that a load can be transmitted. Thus, the piles A and B including the two oblique piles 1 and 1 are arranged so as to surround the existing building 2 when viewed in plan (FIG. 2).
[0013]
In addition, the inclination angle θ of each inclined pile 1 is preferably about 65 degrees with respect to the horizontal plane so as to strongly resist horizontal force such as seismic force. However, the inclination angle θ is not limited to the above, and is designed in a range that can sufficiently resist the horizontal force. This assembled pile (tilted pile structure) has the advantage that the horizontal displacement is small because of its high rigidity against horizontal forces such as seismic forces. Further, the stress generated in the inclined piles 1 and 1 is mainly tensile stress and compressive stress, and has an advantage that bending moment and shear stress are small due to structural characteristics of the pile pile.
[0014]
3A and 3B and FIGS. 4A and 4B show means and steps for rigidly connecting the pile heads of the assembled piles and the footings 3a of the existing building 2 so as to be able to transmit loads. First, the 1st footing 6 which connected the pile head of the pile which consists of the said 2 diagonal piles 1 and 1 is constructed. A second footing 7 integrated with the footing 3a of the existing building 2 is constructed at a position immediately above the hydraulic jack 8 and the support jack 9 between the first footing 6 and the second footing 7 in a substantially vertical position. (FIG. 3A, B). And, by the action of the hydraulic jack 8, part or all of the vertical load acting on the footing 3 a of the existing building 2 is replaced with the assembled pile, and the changed state is fixed by the action of the support jack 9. To do. Thereafter, the hydraulic jack 8 is removed and collected (FIGS. 4A and B), and concrete 10 is placed between the first footing 6 and the second footing 7 to bury the support jack 9 (FIGS. 4A and 4B). B). When the concrete 10 exhibits strength, the rigid state is made permanent. In the figure, reference numeral 3b indicates a foundation beam, and reference numeral 11 indicates an existing column.
[0015]
By placing part or all of the vertical load acting on the footing 3a of the foundation 3 of the existing building 2 on the assembled pile, the assembled pile is shown in FIG. 5 and described in [Prior Art]. Since the magnitude of the vertical load Wtanθ is further added to the horizontal resistance force (F) obtained by the equation of F = 2Rsinθ, a pile having a larger horizontal resistance force is realized.
[0016]
For example, for the horizontal force F in the X direction acting from the right side to the left side in FIG. 2, the pile pile A composed of the two diagonal piles 1, 1 arranged in the X direction effectively resists, An advantageous support state in which the bending moment is reduced is exhibited. Moreover, the pile pile B installed in the Y direction effectively resists the horizontal force F ′ acting in the Y direction in FIG. Thus, the two types of piles A and B that oppose each other against the horizontal force in the X and Y2 directions acting on the entire existing building 2 effectively resist the seismic force of the foundation 3 of the existing building 2. Seismic performance can be improved later. Similarly, stability against liquefaction can be maintained permanently.
[0017]
In addition, in the said Example, it implements for every footing 3a of the outer peripheral part of the existing building as a means to rigidly couple the pile heads of the said piles A and B and the foundation 3 of the existing building 2 so that a load can be transmitted. However, the present invention is not limited to this. In addition, the present invention is not limited to the outer peripheral portion of an existing building, but can be applied to the foundation of the inner peripheral portion in a building having a courtyard or the like. Furthermore, the number of the pile piles A and B in the X direction and the Y direction in FIG. 2 is preferably set according to the direction such as the length and pile diameter of the diagonal pile 1 and the inclination angle of the diagonal pile 1 constituting the pile pile. Therefore, the numbers are not necessarily the same.
[0018]
In addition, when the distance between the footings 3a is short or the length of the slant pile 1 is long, the slant piles 1 are alternately arranged as shown in FIGS. 6A and 6B so that the slant piles do not collide with each other. It is also effective to do.
[0019]
[Effects of the present invention]
According to the method for reinforcing an existing building foundation with a diagonal pile according to the present invention, a pile pile composed of two diagonal piles is constructed in the ground near the foundation of the existing building, and the vertical load of the building is applied to the pile head of the same pile. The horizontal resistance of the existing building foundation can be increased by transmitting to. Therefore, it can sufficiently resist the horizontal load such as seismic force and can improve the seismic performance against the seismic force of the existing building foundation. At the same time, the stability against the liquefaction phenomenon can be permanently maintained, and a highly reliable method of reinforcing an existing building foundation can be realized.
[Brief description of the drawings]
FIG. 1 is a front view schematically showing a method for reinforcing an existing building foundation using a diagonal pile according to the present invention.
FIG. 2 is a plan view schematically showing a method for reinforcing an existing building foundation using a diagonal pile according to the present invention.
FIG. 3A is a front view showing a construction process of a method for reinforcing an existing building foundation using diagonal piles according to the present invention, and B is a right side view thereof.
FIG. 4A is a front view showing a construction completion state of a method for reinforcing an existing building foundation using a diagonal pile according to the present invention, and FIG. 4B is a right side view thereof.
FIG. 5 is a schematic view showing the function of a group pile composed of two diagonal piles in the present invention.
FIG. 6A is a front view showing a pile pile used in another embodiment, and FIG. 6B is a plan view thereof.
FIG. 7 is a schematic diagram showing the function of a group pile composed of two diagonal piles in the prior art.
[Explanation of symbols]
1 diagonal pile 2 existing building 3 foundation 3a footing 3b foundation beam 4 pile 5 ground 6 first footing 7 second footing 8 hydraulic jack 9 support jack 10 concrete 11 existing column 12 newly installed footing

Claims (3)

Arranged symmetrically changed planarly approximately 180 degrees facing two oblique pile in the ground for foundation near the existing building by connecting the pile head ends of the piles and construction of Kumikui, the The first footing connecting the pile heads of the group pile is constructed, the second footing integrated with the foundation of the existing building is constructed at the position directly above, and the hydraulic jack between the first footing and the second footing, A support jack is installed substantially vertically, and the first footing that connects the pile heads of the assembled piles to the part or all of the vertical load acting on the foundation of the existing building is constructed by the hydraulic jack, and the position directly above A second footing that is integrated with the foundation of the existing building is installed, and a hydraulic jack and a support jack are provided substantially vertically between the first footing and the second footing. The hydraulic jack acts on the foundation of the existing building. Lead Part or all of the load is replaced by the pile, and the replacement state is fixed by the support jack. Thereafter, the hydraulic jack is removed, and concrete is driven between the first footing and the second footing. and set, characterized the set piles of the pile head and the existing rigidly the foundation to allow load transfer of the building to Turkey than killing fills the support jack, reinforcing the existing building foundation by Hasukui Method. The method for reinforcing an existing building foundation by using a slant pile according to claim 1, wherein the foundation of the existing building is a footing. The method for reinforcing an existing building foundation with a slanted pile according to claim 1, wherein the foundation of the existing building is a foundation beam.

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