Building foundation structure and method

Abstract

To make use of existing piles while rendering detailed evaluation of existing piles unnecessary.SOLUTION: A foundation structure for a building to be built on a site with existing piles includes new piles that are driven into a different location from the existing piles, and a foundation body that is newly constructed on the new piles and the existing piles. A lower part of the foundation body faces the existing piles in the vertical direction and faces them in the horizontal direction being spaced apart.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a building foundation and method. [Background technology]

[0002] A foundation structure for a new building is known, which has a newly constructed foundation on existing piles and new piles. In this foundation structure, the existing piles are semi-rigidly connected to the foundation, and the new piles are rigidly or semi-rigidly connected to the foundation. In this technology, it is expected that the existing piles and the new piles will share the vertical force received from the foundation, and that the existing piles and the new piles will share the horizontal force received from the foundation during an earthquake so that the existing piles are smaller than the new piles. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2003-082688 A Summary of the Invention [Problem to be solved by the invention]

[0004] Incidentally, when existing piles are used in addition to newly constructed piles to share vertical forces and horizontal forces during earthquakes, the existing piles will affect whether or not various construction requirements (such as earthquake resistance requirements) are met. For this reason, it becomes necessary to evaluate the details of the existing piles. However, due to retrospective factors such as aging, it may be difficult to evaluate (survey) the details of existing piles based on the design information at the time of construction.

[0005] Therefore, an object of the present invention is to enable the use of existing piles while eliminating the need to evaluate the details of the existing piles. [Means for solving the problem]

[0006] In one aspect, a foundation structure for a building constructed on a site having existing piles, comprising: A new pile is driven into a location different from the existing pile; The new pile and the foundation body newly installed on the existing pile, A foundation structure is provided in which the lower part of the foundation body faces the existing pile in the vertical direction and faces the existing pile while being spaced apart in the horizontal direction. Effect of the Invention

[0007] The present invention makes it possible to utilize existing piles while eliminating the need to evaluate their details. [Brief description of the drawings]

[0008] [Figure 1] FIG. 2 is a schematic explanatory diagram of the foundation structure of the building of this embodiment, and is a schematic top view of the building erected on the site. [Diagram 2] 2 is a schematic cross-sectional view showing the foundation structure of the building, corresponding to a cross-sectional view taken along line AA in FIG. 1 passing through the first existing pile. [Figure 2A] 3 is a diagram showing a schematic view of the foundation body as viewed in the direction along the arrow V2 in FIG. 2. FIG. [Diagram 3] FIG. 3 is an enlarged view of part Q1 in FIG. [Figure 4] FIG. 1 is an explanatory diagram of the behavior of a building's foundation structure during a small to medium-sized earthquake. [Diagram 5] FIG. 1 is an explanatory diagram of the behavior of a building's foundation structure during a major earthquake. [Figure 6] FIG. 1 is an explanatory diagram of the horizontal deformation of a newly constructed pile during an earthquake. [Figure 7] 2 is a schematic cross-sectional view showing the foundation structure of the building, corresponding to a cross-sectional view taken along line BB in FIG. 1 passing through the second existing pile. [Figure 8A] FIG. 1 is an explanatory diagram (part 1) of a preferred example of positions of a plurality of first existing piles. [Figure 8B] FIG. 2 is an explanatory diagram (part 2) of a preferred example of positions of the multiple first existing piles. [Figure 8C] FIG. 11 is an explanatory diagram (part 3) of a preferred example of positions of the multiple first existing piles. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Each embodiment will be described in detail below with reference to the accompanying drawings.

[0010] FIG. 1 is a schematic explanatory diagram of a foundation structure 7 of a building 1 of this embodiment, and is a schematic top view of the building 1 erected on a site S.

[0011] The building 1 may be any type of structure, but is preferably a building such as an apartment building or a building. The building 1 may have a basement floor. In FIG. 1, the exterior shape of the building 1 is rectangular, but the exterior shape is arbitrary. The building 1 may also have a structure in which multiple building parts are connected by a corridor or the like.

[0012] In this embodiment, existing piles 20 are arranged on the site S. The arrangement of the existing piles 20 is determined according to the structure of the demolished building (not shown), and the present invention is applicable to any arrangement of the existing piles 20. In this embodiment, as an example, five existing piles 20 are arranged on the site S.

[0013] FIG. 2 is a schematic cross-sectional view showing the foundation structure 7 of the building 1, and corresponds to a cross-sectional view taken along line AA in FIG. 1 passing through the first existing pile 21 (a cross-sectional view cut along a plane including the vertical direction). In FIG. 2 (and the following figures), the symbol G represents the ground. FIG. 2A is a schematic view of the foundation main body 30 as viewed in the direction along arrow V2 in FIG. 2, and is an explanatory diagram of a vertically opposed portion 31 and a horizontally opposed portion 32, which will be described later. FIG. 3 is an enlarged view of part Q1 in FIG. 2.

[0014] The foundation structure 7 of the building 1 has new piles 10 and a foundation body 30 below the building body 90.

[0015] The new piles 10 are driven into the site S at a location different from the existing piles 20. The location and number of the new piles 10 may be appropriately determined according to the characteristics of the building 1 and the site S. For example, the new piles 10 may be placed at a distance from the existing piles 20 and the site boundary that takes into consideration workability. The lower ends of the new piles 10 may extend to a ground layer (not shown) underground in order to increase the bearing capacity and stability of the foundation body 30. The upper ends of the new piles 10 are appropriately joined to the foundation body 30. Earthquake-resistant rubber or the like may be placed between the new piles 10 and the foundation body 30.

[0016] The foundation body 30 is newly installed on the new pile 10 and the existing pile 20. In this embodiment, the existing piles 20 are composed of a first existing pile 21, a second existing pile 22, and a third existing pile 23, and the foundation body 30 is newly installed on the new pile 10, the first existing pile 21, and the second existing pile 22. The difference between the first existing pile 21, the second existing pile 22, and the third existing pile 23 may be only a difference in function (use), which will be described later. The existing pile 20 is basically used as it is, but may be processed appropriately in relation to the foundation body 30. For example, the height of the head of the existing pile 20 may be adjusted so that the head (upper end) is located at a height corresponding to the lower part of the foundation body 30. The cross-sectional shape of the existing pile 20 is arbitrary and may be constant, or the head and other parts may be different (i.e., the specifications of the pile head may be different).

[0017] The lower part of the foundation body 30 is formed by a foundation beam, a pressure plate, etc. The lower part of the foundation body 30 may be made of precast concrete, but in this embodiment, it is preferable that the lower part is formed by casting in place.

[0018] The lower part of the foundation body 30 faces the existing pile 20 in the vertical direction and faces the existing pile 20 while being spaced apart in the horizontal direction. Specifically, the lower part of the foundation body 30 has a vertically facing part 31 and a horizontally facing part 32 as parts related to the existing pile 20.

[0019] The vertically facing portion 31 overlaps the entire upper end face of the first existing pile 21 when viewed in the vertical direction. That is, the vertically facing portion 31 faces the entire upper end face of the first existing pile 21 in the vertical direction. In FIG. 2A, the dashed line indicates the outline (outline when viewed from above) of the upper end face of the first existing pile 21. In addition, of the double circles on the outer side of the dashed line, the inner circle (dotted line) indicates the outline of the vertically facing portion 31, and the region between the inner circle (dotted line) and the outer circle (dotted line) is the region of the horizontally facing portion 32. In addition, the vertically facing portion 31 and the horizontally facing portion 32 are portions for explanation, and may be portions continuous with each other (both are parts of the lower part of the foundation main body 30).

[0020] The vertically facing portion 31 is spaced apart from the first existing pile 21 in the vertical direction. That is, the lower portion of the foundation main body 30 is spaced apart from the first existing pile 21 in the vertical direction over the entire periphery of the range of the vertically facing portion 31. Therefore, in this embodiment, the first existing pile 21 does not substantially bear any vertical force from the foundation main body 30.

[0021] In this manner, the vertically opposing portion 31 faces the first existing pile 21 while being spaced apart from it in the vertical direction.

[0022] The vertical distance between the vertically facing portion 31 and the first existing pile 21 is arbitrary, and may be, for example, about 50 mm. The lower surface of the vertically facing portion 31 is a substantially horizontal plane, but may have irregularities or the like as long as it is vertically separated from the first existing pile 21.

[0023] The horizontally facing portion 32 at least partially surrounds the outer periphery of the first existing pile 21 when viewed in the vertical direction. In this embodiment, the horizontally facing portion 32 surrounds the entire outer periphery of the first existing pile 21 when viewed in the vertical direction. In other words, the horizontally facing portion 32 surrounds the first existing pile 21 without overlapping with the first existing pile 21 when viewed in the vertical direction.

[0024] As shown in Fig. 3, the horizontally facing portion 32 is spaced apart from the first existing pile 21 in the horizontal direction. In the example shown in Fig. 3, the horizontally facing portion 32 is spaced apart from the first existing pile 21 by a horizontal distance L1. Note that the horizontal distance L1 between the horizontally facing portion 32 and the first existing pile 21 is preferably constant around the first existing pile 21, but does not need to be strictly constant.

[0025] As shown in Fig. 3, the horizontally facing portion 32 overlaps with the head of the first existing pile 21 when viewed in the horizontal direction. The overlapping amount (vertical length) between the horizontally facing portion 32 and the head of the first existing pile 21 is arbitrary as long as the effects described below are achieved, but may be about 100 mm. The overlapping amount is also preferably constant around the first existing pile 21, but does not have to be strictly constant.

[0026] In this manner, the horizontally facing portion 32 faces the first existing pile 21 while being spaced apart from it in the horizontal direction.

[0027] As will be described later with reference to Figures 4 and 5, the horizontally opposing portion 32 provides the first existing pile 21 with the function of withstanding horizontal force as reserve force (hereinafter also referred to as "reserve force function") in the event of an earthquake of a specified magnitude or greater.

[0028] As shown in Fig. 3, the horizontally facing portion 32 protrudes vertically downward from the vertically facing portion 31. In the example shown in Fig. 3, the horizontally facing portion 32 is formed in the minimum necessary range to ensure the reserve capacity of the first existing pile 21. In this case, the reserve capacity can be ensured with the minimum material cost. However, in a modified example, the horizontally facing portion 32 may be a part of a portion protruding over a relatively wide range around the vertically facing portion 31.

[0029] The horizontally facing portion 32 may be integrally formed as a part of the lower portion of the foundation body 30. That is, when the lower portion of the foundation body 30 is formed by casting in place, the horizontally facing portion 32 may be formed at the same time. Alternatively, the horizontally facing portion 32 may be a separate piece from the other portions of the lower portion of the foundation body 30, and may be integrated with the other portions of the lower portion of the foundation body 30 to form the lower portion of the foundation body 30. In this case, the horizontally facing portion 32 may be precast concrete, or may be a member of a material different from the material of the lower portion of the foundation body 30, for example, a metallic member (a member with high rigidity).

[0030] The cushioning material 40 is disposed between the vertically opposing portion 31 and the first existing pile 21 in the vertical direction, and is disposed between the horizontally opposing portion 32 and the first existing pile 21 in the horizontal direction. Note that the cushioning material 40 disposed between the horizontally opposing portion 32 and the first existing pile 21 in the horizontal direction and the cushioning material 40 disposed between the vertically opposing portion 31 and the first existing pile 21 in the vertical direction may be separate bodies.

[0031] The material of the buffer material 40 is arbitrary as long as the first existing pile 21 does not substantially bear the vertical force through the buffer material 40. The buffer material 40 may be, for example, styrofoam or a heat insulating material. In a modified example, the buffer material 40 may be omitted, and an air layer may be formed between the vertically facing portion 31 and the first existing pile 21 in the vertical direction, and / or between the horizontally facing portion 32 and the first existing pile 21 in the horizontal direction. However, when it is difficult to maintain the air layer for a long period of time, the buffer material 40 is advantageous. In addition, in the case of an air layer, other members or substances such as sand (other members or substances that do not have buffer properties) may be intentionally or unintentionally mixed into a part of the air layer. In this case, the first existing pile 21 may bear a slight vertical force through, for example, sand, but such a form is within the concept that the first existing pile 21 does not substantially bear the vertical force. In a further modified example, the vertically opposing portion 31 may abut vertically against the first existing pile 21 (i.e., may not be spaced apart) in a manner in which there is substantially no transmission of vertical force (for example, in a manner in which the transmission of vertical force between the lower part of the foundation body 30 and the newly constructed pile 10 is negligible, such as 10% or less).

[0032] Next, the effect of this embodiment will be described in relation to the reserve force function of the first existing pile 21 with reference to Figs.

[0033] FIG. 4 is an explanatory diagram of the behavior of the foundation structure 7 of the building 1 during a small to medium-sized earthquake less than a specified scale, with an enlarged view of the Q1 portion shown in a balloon at the bottom. FIG. 5 is an explanatory diagram of the behavior of the foundation structure 7 of the building 1 during a large earthquake of a specified scale or greater, with an enlarged view of the Q1 portion shown in a balloon at the bottom. FIG. 6 is an explanatory diagram of the horizontal deformation of the newly installed pile 10 during an earthquake. Note that the actual value of the specified scale may differ depending on the environment, etc., but the target value (design value) of the specified scale may correspond to a "large-scale earthquake (seismic intensity 6+ to 7) that occurs very rarely" based on the new earthquake resistance standards.

[0034] In this embodiment, as described above, the horizontally facing portion 32 overlaps with the first existing pile 21 when viewed in the horizontal direction, but is spaced apart from the first existing pile 21 in the horizontal direction.

[0035] During an earthquake, the newly-installed pile 10 undergoes horizontal deformation due to the inertial force from the building body 90, as shown in Fig. 6. The amount of horizontal deformation tends to increase as the scale of the earthquake increases. In Fig. 6, the left side shows the state during a small to medium-sized earthquake, and the right side shows the state during a large earthquake.

[0036] In the event of a small to medium-sized earthquake of less than a predetermined scale, the amount of deformation related to the horizontal deformation of the new pile 10 is relatively small. For this reason, as shown in FIG. 4, in the event of a small to medium-sized earthquake, the first existing pile 21 does not receive a horizontal force from the foundation body 30. That is, even if the lower part of the foundation body 30 is displaced in the horizontal direction in the event of a small to medium-sized earthquake, the separation distance between the first existing pile 21 and the lower part of the foundation body 30 (horizontally facing part 32) in the horizontal direction is 0 or more. In other words, the horizontal distance L1 (separation distance under normal conditions) between the horizontally facing part 32 and the first existing pile 21 described above may be adapted to be equal to or greater than the reduction in the separation distance between the first existing pile 21 and the lower part of the foundation body 30 (horizontally facing part 32) in the event of a small to medium-sized earthquake.

[0037] In this way, in this embodiment, the first existing pile 21 does not directly receive horizontal force from the foundation body 30 during a small to medium earthquake.

[0038] In the event of a major earthquake of a predetermined scale or greater, the amount of deformation related to the horizontal deformation of the new pile 10 becomes relatively large. Therefore, as shown in FIG. 5, in the event of a major earthquake, the first existing pile 21 can receive a horizontal force from the foundation body 30. That is, in the event of a major earthquake, the lower part of the foundation body 30 is displaced relatively large in the horizontal direction, so that the distance between the first existing pile 21 and the lower part of the foundation body 30 (horizontally facing part 32) in the horizontal direction becomes substantially "0", and the first existing pile 21 can bear the horizontal force. Note that, in the event that the buffer material 40 also extends between the first existing pile 21 and the lower part of the foundation body 30 (horizontally facing part 32) in the horizontal direction, the buffer material 40 is crushed, so that the distance between the horizontally facing part 32 and the first existing pile 21 in the horizontal direction becomes substantially "0". For this purpose, the horizontal distance L1 (the separation distance under normal conditions) between the above-mentioned horizontally opposing portion 32 and the first existing pile 21 may be adapted to be equal to or less than the horizontal relative displacement between the first existing pile 21 and the lower part of the foundation body 30 (horizontally opposing portion 32) during a major earthquake (the relative displacement assuming that the first existing pile 21 does not exist).

[0039] In this way, in this embodiment, in the event of a major earthquake, the first existing pile 21 can directly receive the horizontal force from the foundation body 30 ("directly" since the buffer material 40 can be ignored). Therefore, for example, according to this embodiment, the first existing pile 21 can be used only when it is deformed by an earthquake larger than expected. This makes it possible to reduce the amount of deformation of the new pile 10 and the amount of deformation of the building 1, compared to the case where the first existing pile 21 does not exist as shown in FIG. 6.

[0040] In recent years, there has been a trend to improve earthquake resistance, but little effort has been put into improving the earthquake resistance of piles. Generally, pile construction is relatively expensive, so if existing piles can be effectively used, earthquake resistance can be improved at low cost.

[0041] However, as described above in the section "Problems to be Solved by the Invention," if the existing piles 20 are used to share vertical forces or horizontal forces during an earthquake, the existing piles 20 are also subject to review in the application for confirmation. In other words, if the existing piles 20 are used as part of the foundation, the existing piles 20 are also subject to review in the application for confirmation.

[0042] In contrast, according to this embodiment, the first existing pile 21 can be used as "surplus capacity" and therefore the first existing pile 21 can be excluded from the examination target in the confirmation application. In other words, the details of the first existing pile 21 do not need to be known. However, if the details of the first existing pile 21 are known, it is possible to accurately grasp the surplus capacity.

[0043] Thus, according to this embodiment, by utilizing the first existing piles 21 as "reserve capacity," it is possible to effectively improve seismic performance in the event of an earthquake greater than expected by using the first existing piles 21, and to eliminate the need to understand the details of the first existing piles 21. Therefore, even if the first existing piles 21 are defective as piles, no problem will arise in terms of the confirmation application (the new piles 10 required by the Building Standards Act will be driven).

[0044] Next, with reference to FIG. 7 while still referring to FIG. 1, an example of a method for differentiating the use of the existing piles 20 in one site S will be described.

[0045] FIG. 7 is a schematic cross-sectional view showing the foundation structure 7 of the building 1, and corresponds to a cross-sectional view taken along line BB in FIG. 1 passing through the second existing pile 22.

[0046] In this embodiment, all of the existing piles 20 located below the foundation body 30 may constitute the first existing piles 21 described above, or only a portion of them may constitute the first existing piles 21, as shown in Figure 1.

[0047] That is, in the example shown in FIG. 1, the second existing pile 22 is located below the foundation body 30, but does not have the above-mentioned reserve force function of the first existing pile 21, as shown in FIG. 7. Specifically, the foundation body 30 has a third portion 33 that overlaps the second existing pile 22 when viewed in the vertical direction, and a fourth portion 34 that surrounds the outer periphery of the second existing pile 22 when viewed in the vertical direction. The third portion 33 and the fourth portion 34 are separated from the second existing pile 22 in the vertical direction and extend above the second existing pile 22. That is, the second existing pile 22 is separated from the foundation body 30 in the up-down direction and does not overlap with it when viewed in the horizontal direction. Therefore, the second existing pile 22 does not bear a vertical force under normal conditions, and does not receive a horizontal force even during a major earthquake. In the example shown in FIG. 7, the second existing pile 22 is located below the foundation body 30, but may not be located below the foundation body 30, but may be located below the building body 90.

[0048] In this way, even if one of the existing piles 20 is located below the foundation body 30 and therefore capable of forming the first existing pile 21, it may be configured as the second existing pile 22 rather than the first existing pile 21.

[0049] However, when the second existing piles 22 are removed, the compacted soil may be disturbed, resulting in a weak ground. In this regard, according to the present embodiment, the second existing piles 22 are left in place, thereby making it possible to avoid such inconvenience.

[0050] Here, as described above, the first existing pile 21 receives a horizontal force from the foundation body 30 during a major earthquake, and therefore, depending on the position of the first existing pile 21 relative to the foundation body 30 when viewed in the vertical direction, the foundation body 30 may become eccentric due to the reaction force from the first existing pile 21. Such eccentricity is likely to occur when the position of the first existing pile 21 relative to the foundation body 30 when viewed in the vertical direction is away from the center (e.g., center of gravity) of the foundation body 30 or the center (e.g., center of gravity) of the building body 90 when viewed in the vertical direction.

[0051] In consideration of this point, the first existing pile 21 is preferably selected so as to be located near the center of the foundation body 30 (more inward than the second existing pile 22) when the center side of the foundation body 30 is considered to be the inside when viewed in the vertical direction. In this case, the reserve capacity function of the first existing pile 21 can be ensured while reducing the possibility of the above-mentioned eccentricity that may occur when the reserve capacity function is exerted.

[0052] Alternatively, as shown in FIG. 8A and FIG. 8B, even if the position of the first existing pile 21 is far from the center (e.g., center of gravity) of the foundation body 30 or the center (e.g., center of gravity) of the building body 90 when viewed in the vertical direction, the possibility of the above-mentioned eccentricity can be reduced if the multiple first existing piles 21 are arranged in a well-balanced manner. That is, FIG. 8A and FIG. 8B show multiple first existing piles 21 within the outline of the foundation body 30 or the building body 90 when viewed from above, and when the average value of the positions of the multiple first existing piles 21 is close to the center position (e.g., centroid position of the outline) of the foundation body 30 or the building body 90, the possibility of the above-mentioned eccentricity can be reduced. Close to the center position refers to a state closer to the center position than the outer edge position of the foundation body 30 or the building body 90 when viewed from above, but preferably refers to a state approximately coinciding with the center position. Note that in the example shown in FIG. 8C, the average value of the positions of the multiple first existing piles 21 is slightly away from the center position of the foundation body 30 or the building body 90, and eccentricity is more likely to occur than in the example shown in FIG. 8A and FIG. 8B. Although not shown in FIG. 8A etc., one or more second existing piles 22 may be arranged within the outer shape of the foundation body 30 or the building body 90.

[0053] In the example shown in Fig. 1, of the existing piles 20, there are three piles located below the foundation body 30, one of which is the first existing pile 21 and the remaining two are the second existing piles 22. However, the number and arrangement of the first existing piles 21 are arbitrary, and in a modified example, all of the existing piles 20 located below the foundation body 30 may form the first existing piles 21.

[0054] Furthermore, among the existing piles 20, the third existing piles 23 that are not located below the foundation body 30 may not be used at all, or may be used for other purposes. For example, the third existing piles 23 that exist in a specific site portion of the site S may contribute to preventing subsidence of that site portion. In this case, it is preferable that the specific site portion is a site portion used as a parking lot, such as a multi-story parking lot. This is because in multi-story parking lots in particular, fluctuating weight during operation is likely to be large, and subsidence is more likely to occur than in other site portions (for example, site portions with plantations or site portions of parks).

[0055] Although each embodiment has been described above in detail, the present invention is not limited to the specific embodiment, and various modifications and changes are possible within the scope of the claims. In addition, it is also possible to combine all or a plurality of the components of the above-described embodiments. [Explanation of symbols]

[0056] 1 Building 6. Seismic Intensity 7 Basic structure 10 New piles 20 Existing piles 21 First existing pile 22 Second existing pile 23 Third existing pile 30 Foundation Body 31 Vertically opposing parts 32 Part 2 33 Part 3 34 Part 4 40 Cushioning material 90 Building body G underground L1 horizontal distance S Site

Claims

1. A foundation structure for a building to be constructed on a site having existing piles, A new pile is driven into a location different from the existing pile; The new pile and the foundation body newly installed on the existing pile, A foundation structure in which the lower part of the foundation body faces the existing pile vertically and faces the existing pile while being spaced apart horizontally.

2. The foundation structure according to claim 1 , wherein a lower portion of the foundation body protrudes vertically downward around a head of the existing pile.

3. The foundation structure according to claim 1 , wherein a lower portion of the foundation body is spaced apart from the existing pile in the vertical direction.

4. The foundation structure according to claim 1 , further comprising an air layer or a buffer material between the existing pile and the lower part of the foundation body in the vertical direction.

5. The foundation structure according to claim 1 , further comprising an air layer or a buffer material between the existing pile and the lower part of the foundation body in the horizontal direction.

6. The foundation structure according to claim 1 , wherein the lower part of the foundation body is formed by a foundation beam or a pressure plate.

7. The foundation structure described in claim 1, wherein, during an earthquake, the existing pile does not directly receive a horizontal force from the foundation body when the horizontal displacement of the foundation body relative to the head of the existing pile is greater than 0 and less than a predetermined value.

8. The foundation structure according to claim 7 , wherein the building satisfies a desired seismic performance only by the new piles out of the new piles and the existing piles.

9. When the existing pile is a first existing pile, the site has a second existing pile different from the first existing pile, The foundation structure according to claim 1 , wherein the second existing pile is vertically spaced apart from the main body of the building or the main body of the foundation and does not overlap with the main body in the horizontal direction.

10. The foundation structure according to claim 9 , wherein when viewed in the vertical direction, the center side of the foundation body is defined as the inside, the first existing pile is located more inward than the second existing pile.

11. The first existing pile is arranged in plurality, The foundation structure described in claim 9, wherein when a horizontal plane along the site is defined as an xy plane and a direction perpendicular to the xy plane is defined as the z direction, as viewed in the z direction, the average position of the x and y coordinates of each of the positions of the multiple first existing piles is closer to the center position of the main body of the building or the center position of the foundation body than the outer edge position of the main body of the building or the outer edge position of the foundation body.

12. A method for forming a foundation structure for a building on a site having existing piles, comprising: Driving a new pile into a location different from the existing pile; The method includes a step of constructing a foundation body on the new pile and the existing pile, A method in which the step of constructing the new foundation body is carried out so that the lower part of the foundation body faces the existing pile vertically and faces the existing pile while being spaced apart in the horizontal direction.

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