JP4683520B2 - Foundation structure of new building using existing piles - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a foundation structure of a new building that uses an existing pile left when an existing building is removed.
[0002]
[Prior art]
When rebuilding foundation structures with prestressed concrete (PC) piles or cast-in-place concrete piles due to aging of buildings or redevelopment plans, most existing piles are designed according to the design standards at the time of construction. Therefore, although the vertical support capacity is sufficient, the horizontal resistance capacity is remarkably inferior, it is difficult to satisfy the current design standards for existing piles, and it may be difficult to use the existing piles as piles for new buildings. It is almost.
[0003]
Therefore, when existing piles and new piles interfere with each other when rebuilding, conventionally, the existing piles are removed at the same time as the existing buildings are demolished and backfilled. When piles are buried and new piles are placed avoiding existing piles that have been buried, and the positions of the new piles and the pillars of the new building are misaligned, the new piles will bear the vertical force from the columns. In order to be able to do so, a method of reinforcing the foundation connecting the pillar and the new pile is generally adopted.
[0004]
[Problems to be solved by the invention]
However, in the conventional method of removing existing piles and newly placing new piles, it takes a long time to remove the existing pile foundation and existing piles and backfill the site. In addition, there is a problem that the cost increases. In addition, this method generates waste due to the removal of existing piles and requires new materials to drive new piles. Therefore, environmental considerations such as waste reduction and resource conservation are required. It has another problem of lack.
[0005]
In addition, in the method of placing new piles while avoiding the existing piles that were buried, the placement position of the new piles is restricted by the remaining existing piles. Has the problem of becoming low.
[0006]
In order to solve these problems, new piles are installed by placing new piles in the ground between the pile rows of existing pile foundations, and new foundations are installed freely on the existing pile foundations in the horizontal direction. A new building foundation using an existing pile foundation is proposed, in which only the vertical load is borne on the existing pile foundation, and the new foundation and the new pile are integrated by rigid joining to bear both the vertical load and the horizontal load on the new pile. (Japanese Patent Laid-Open No. 9-60007).
[0007]
However, in this proposed new building foundation, the existing pile foundation and the existing pile are not burdened with horizontal loads at all, and the new piles are all burdened. It has the problem that it cannot be said that it uses all the performance it has. In addition, there is a demand to reduce the cost by further reducing the diameter of the new pile by utilizing all the performance of the existing pile and reducing the number of piles.
[0008]
The objective of this invention is providing the foundation structure of the new building using the existing pile which can solve the above-mentioned problem in a prior art.
[0009]
[Means for Solving the Problems]
In order to solve the above problems, according to the present invention, an existing building is removed by leaving an existing pile, and the foundation structure of a new building using the remaining existing pile is provided, the existing pile and the existing pile. includes a foundation is established on a new pile is pouring avoiding anti, wherein the existing pile, the foundation is semirigid joined by subtracting the moment a joined state to be borne at the junction Luke, or the foundation is the existing pile and the contact area of the squeezed smaller to bending stiffness is reduced by half rigid connections between the new foundation, wherein the new pile, said base is bonded or the semirigid joint stiffness, horizontal forces encountered vertical force and earthquake received from said base, said existing pile and is shared by the newly pile, changing the allocation of the horizontal force of the new pile in accordance with the horizontal resistance ability the existing anti has Accordingly, before to be smaller than the new pile Basic structure of new buildings utilizing existing piles, characterized in that sharing a horizontal force to the existing pile is proposed.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an example of an embodiment of the present invention will be described in detail with reference to the drawings.
[0011]
FIG. 1 is a pile layout diagram for explaining an example of an embodiment of a foundation structure comprising a pile and a pile foundation according to the present invention. The dotted line in the figure indicates the boundary line g of the site, and the dotted line in the site partitioned by the boundary line g indicates that this site has not been built before the construction of the new building. The core lines x1 to x4 and y1 to y4 of the existing buildings that have been installed. Similarly, the solid lines shown in the site of the boundary line g are the core lines X1 to X3, Y1 of the new building newly constructed after the existing building is removed with the existing piles removed, in order to rebuild this existing building. Y4.
[0012]
Reference numerals 11 to 26 indicated by diagonal lines in the site are existing piles of cast-in-place concrete piles that are used to support existing buildings and are still installed in the ground G. Of these 16 existing piles, twelve shown by the diagonal lines rising to the right are the existing use piles 11 to 22 that are used to support the new building when the new building is constructed this time.
[0013]
Here, the existing pile that supported the existing building was built based on the design standards at the time of construction of the existing building, so the vertical force is sufficient to compare with the current design standards. However, it is extremely inferior to the horizontal force. Therefore, 12 existing use piles 11-22 depend on the horizontal resistance force which each existing use pile 11-22 judged based on the investigation result with the vertical force by the basic structure of the present invention. By changing the sharing of the horizontal force with the new pile, it is used to bear a part of the horizontal force during an earthquake.
[0014]
Like the existing use piles 11-22, what is indicated by reference numerals 23 to 26 is an existing pile previously installed to support an existing building, but is not used to support a newly constructed building, It is an existing buried pile that has been buried in the ground G. Reference numerals 31 to 33 denote new piles installed by placing new piles when constructing a new building this time. These three new piles 31 to 33 are the current design standards. It was designed and built based on the above, and was installed to support the new building while bearing vertical and horizontal forces.
[0015]
Among the columns of the new building, the columns used so as to allow the column axial force to flow through the piles are the core lines X1 and Y1, X2 and Y1, X3 and Y1, X1 and Y2, X2 and Y2, X3 and Y3, Twelve are constructed around the positions of the intersections of X1 and Y3, X2 and Y3, X3 and Y3, X1 and Y4, X2 and Y4, and X3 and Y4. In addition, the pile is generally installed at the same position as the pillar so as to support the building. Here, six of the twelve pillars are constructed at approximately the same position as the existing use piles 11, 14, 15, 18, 19, 22, but these six existing use piles 11, 14, 15, 18, 19, and 22 have a small horizontal resistance and overlap with the position of the column, so that piles that have been removed and designed according to the current design standards are constructed, but the foundation structure of the present invention is used. It is used so as to bear a part of vertical force and horizontal force.
[0016]
Three of the remaining six pillars are constructed at the same positions as the new piles 31-33. In addition, since the remaining three are built around the intersections of the core line X2 and Y2, Y3, Y4 of the new building, there are six existing uses that are used for these pillars. Pile 12, 13, 16, 17, 20, 21 will be installed in the position shifted from the position of a pillar. Existing use piles 12, 13, 16, 17, 20, and 21 have a small horizontal resistance force and their installation positions are shifted, but the foundation structure of the present invention can be used without any problem as a pile for a new building. It has become.
[0017]
Next, the elevational positional relationship between the pile installed as described above and the building will be described with reference to FIG. FIG. 2 is a cross-sectional view taken along line AA shown in FIG. 1. In FIG. 2, the dotted lines indicate the cores of the beams and pillars of the existing building, and the solid lines indicate the new building. It is a core wire as a beam and a pillar. What are indicated by reference signs z1 to z4 are the core wires of the existing building, and those indicated by reference signs Z1 to Z4 are the core wires of the new building. Although the three existing use piles 12, 16, and 20 are inferior in the horizontal resistance force and overlap with the optimum positions of the piles that are substantially in the same position as the core lines Z2 to Z4 of the new building, It is used without being removed by using the foundation structure. In addition, a new pile 32 is newly constructed at the position of the pillar core Z1 of the new building, and the existing buried pile 24 prevents the new pile 32 from being placed at a position adjacent to the new pile 32. Because it is not in a position, it is left buried without being removed.
[0018]
Next, in the foundation structure of the present invention using the existing use piles 11 to 22, the joining of the existing use pile 11 and the new foundation 3 of the new building will be described with reference to FIGS. 3 and 4. FIG. 3 is a view showing a joint portion between the existing use pile 11 and the new foundation 3 of the new building, and FIG. 4 is a cross-sectional view of FIG.
[0019]
The new foundation 3 is a foundation newly established on the existing use pile 11 installed in the ground G, and is configured as a mat foundation. The upper end portion 11A of the existing use pile 11 is formed into a tapered shape by processing or repetitively striking, and is constructed so as to reduce the contact area with the new foundation 3 constructed on the existing use pile 11. . Further, in FIG. 4, only two pile main bars 11a and 11b, which are visible only two, are inserted into the new foundation 3 so that the existing use pile 11 and the new foundation 3 are firmly connected to each other. In the state where the ends of the pile main bars 11a and 11b are stored in the use pile 11, the formwork and concrete placement of the new foundation 3 are performed on the existing use pile 11, and the joint between the existing use pile 11 and the new foundation 3 is formed. Semi-rigid connection. Here, the semi-rigid joint is a joining method between a rigid joint and a pin joint in a method of applying a moment to the joint, and a joining state in which the moment is reduced by reducing the moment at the joint. It means that two members are joined.
[0020]
With the semi-rigid joint as described above, the contact area between the existing use pile 11 and the new foundation 3 is reduced and the main bars 11a and 11b of the existing use pile 11 are not fixed to the new foundation 3 and the existing use pile. 11 is fixed to the new foundation 3 and the bending rigidity is reduced to reduce the horizontal force sharing. Therefore, depending on the supporting force of the existing use pile 11 and the performance such as bending and shear strength. In the event of an earthquake, it is possible to bear a smaller horizontal force than the new pile. In this embodiment, the main bars 11a and 11b are not fixed to the new foundation 3 in order to reduce the degree of fixation of the existing use pile 11 to the new foundation 3. However, the main bars 11a and 11b are not fixed to the new foundation 3. Of course, some of these may be extended and fixed on the new foundation 3, and the existing piles may be loaded with a horizontal force according to the performance of the piles. In addition, an axial line different from the main line may be fixed on the basis to resist the tensile axial force.
[0021]
As mentioned above, although the joining of the existing use pile 11 and the new foundation 3 was demonstrated, since it is the same also about the joining of the other existing use piles 12-22 and the new foundation 3, other existing use piles 12-22 and new construction Detailed description of the joining with the foundation 3 is omitted.
[0022]
About new piles 31-33, the pile main reinforcement arranged in each pile is inserted in the new foundation 3, and each new pile and the new foundation 3 are firmly joined to form a rigid joint. The vertical force and the horizontal force are borne while compensating for the insufficient horizontal resistance force by using the piles 11 to 22, but the rigid connection is generally performed. Detailed description of is omitted. Moreover, the new piles 31 to 33 can be semi-rigidly joined to the new foundation 3 by a method such as reducing the contact area, and the rigidity of the joined state between the new piles 31 to 33 and the new foundation 3 can be adjusted.
[0023]
Moreover, since the new foundation 3 is constructed as a mat foundation, it is possible to share the axial force to each pile regardless of the position of the pile, so even if the pile is displaced from the position of the pillar It can be used without any problems.
[0024]
Next, another embodiment according to the present invention will be described with reference to FIG. 5 corresponding to those in FIG. 4 are denoted by the same reference numerals, and description thereof is omitted. The existing use pile 40 shown in FIG. 5 is a steel pipe pile, and a concrete piece 41 having a shape in which the concrete is filled in the pile head 40A or the entire length of the pile in the existing use pile 40 and a trapezoidal cone is placed on a cylinder. Is embedded in half so that the tip 41A can be seen. It is constructed so that the new foundation 3 is placed on the upper surface 41Aa of the trapezoidal cone of the concrete piece 41, thereby reducing the contact area between the existing use pile 40 and the new foundation 3 and reducing the existing use pile 40. Is not fixed to the new foundation 3, the degree of fixation of the existing use pile 40 to the new foundation 3 is reduced, the bending rigidity is reduced, and the horizontal force sharing is reduced. As a result, a horizontal force smaller than that of the newly installed pile can be borne during an earthquake according to the horizontal resistance capability of the existing use pile 40.
[0025]
Next, another embodiment according to the present invention will be described with reference to FIG. 6 that correspond to those in FIG. 4 are assigned the same reference numerals, and descriptions thereof are omitted. The existing use pile 50 shown in FIG. 6 is a PC pile, and a concrete piece 51 having a shape in which a concrete is filled in the pile head 50A or the entire length of the pile in the existing use pile 50 and a trapezoidal cone is placed on a cylinder. Is embedded in half so that the tip 51A can be seen. The new foundation 3 is constructed on the upper surface 51Aa of the trapezoidal cone of the concrete piece 51, thereby reducing the contact area between the existing use pile 50 and the new foundation 3 and reducing the existing use pile 50 to the new foundation 3. On the other hand, the fixing degree of the existing use pile 50 to the new foundation 3 is lowered as non-fixed, and the bending rigidity is reduced to reduce the horizontal force sharing. As a result, it is possible to bear a horizontal force smaller than that of the newly installed pile at the time of an earthquake according to the horizontal resistance capability of the existing use pile 50.
[0026]
In the present embodiment, the mat foundation is constructed as the new foundation 3, but the present invention is not limited to this, and a large independent foundation that can bear a vertical force from the pillar of the new building to the corresponding existing use pile. You may make it build.
[0027]
According to the present invention, as described above, the include foundation is established on top of the existing pile and the existing anti-a to avoid pouring has been established pile, wherein the existing pile, the foundation is the moment at the junction is reduced semirigid a joined state to be borne by joining Luke, or the foundation is the smaller and bending stiffness squeeze the contact area between the existing pile and new foundation is being reduced semi rigid connections, the new pile horizontal, the said foundation being the rigid connections or the semirigid bonding, horizontal forces encountered vertical force and earthquake receiving from said foundation, said existing pile and is shared by the newly pile, the existing anti has By changing the horizontal force sharing with the new pile according to the resistance capacity, the horizontal force is shared with the existing pile so as to be smaller than the new pile, so it is not necessary to remove the existing pile. , It takes days to remove and backfill the site Bet it is possible to shorten the construction period because there is no, it is possible to reduce the construction cost because it does not take more than manpower and materials and equipment. In addition, since it is possible to share the axial force to each pile regardless of the installation position of the pile with the new foundation, even if the existing pile is displaced from the position of the pillar, it can be used without problems as needed, Since the new pile is not restricted by the existing pile, the degree of freedom of the placement position of the new pile can be increased.
[0028]
In addition, since existing piles can be loaded with a part of the horizontal load according to the horizontal resistance capacity of existing piles, the existing piles can be fully utilized to make effective use of resources. In addition to the utilization, the diameter of the new pile can be reduced and the number of piles can be reduced, so that further cost reduction can be achieved in the pile installation work. In addition, since the existing piles are not removed, the amount of waste generated can be reduced, and the number of materials required for new pile driving can be reduced by reducing the number of new piles driven. It is possible to carry out environmentally conscious construction that saves resources and saves resources.
[Brief description of the drawings]
FIG. 1 is a pile layout diagram for explaining an example of an embodiment of a foundation structure according to the present invention.
FIG. 2 is a cross-sectional view taken along line AA shown in FIG.
FIG. 3 is a view showing a joint portion between an existing use pile and a new pile foundation.
4 is a longitudinal sectional view of FIG. 3;
FIG. 5 is a longitudinal sectional view of a joint portion between an existing use pile and a new pile foundation for explaining another embodiment according to the present invention.
FIG. 6 is a longitudinal sectional view of a joint portion between an existing use pile and a new pile foundation for explaining another embodiment according to the present invention.
[Explanation of symbols]
3 New foundation 11-22 Existing use pile 23-26 Existing buried pile 31-33 New pile G Ground g Boundary line

Claims (2)

The existing building is removed by leaving the existing piles, and the existing piles left behind are removed.
Including a foundation newly established on the existing pile and a new pile placed avoiding the existing resistance;
In the existing pile, the foundation is semi-rigidly joined in a joining state in which the joint reduces the moment to bear ,
Wherein the new pile, said base is bonded or the semirigid joint stiffness,
Horizontal forces encountered vertical force and earthquake receives from the foundation, is shared by the new pile and the existing pile,
By changing the horizontal force sharing with the newly installed pile according to the horizontal resistance capability that the existing anti-have, the horizontal force was shared with the existing pile so as to be smaller than the newly installed pile ,
Basic structure of the new building that utilizes the already Sonkui.   The existing building is removed by leaving the existing piles, and the existing piles left behind are removed.
  Including a foundation newly established on the existing resistance and a new resistance installed avoiding the existing pile,
  The existing pile is semi-rigidly bonded with reduced bending rigidity by reducing the contact area between the existing pile and the new foundation,
  In the new construction, the foundation is rigidly joined or semi-rigidly joined,
  The vertical force received from the foundation and the horizontal force received in the event of an earthquake are shared between the existing resistance and the new pile,
  By changing the horizontal force sharing with the newly installed pile according to the horizontal resistance capability that the existing anti-have, the horizontal force was shared with the existing pile so as to be smaller than the newly installed pile,
  The basic structure of a new building that uses existing anti-body.

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