Pile foundation structure

Abstract

To provide a pile foundation structure capable of suppressing the occurrence of twisting behavior of the entire building by reducing differences in rigidity due to pile length while suppressing an increase in cost.SOLUTION: A large number of support piles 4 are distributed from the bottom of a foundation 2 of a building 1 to a supporting layer 3 underground. The bottom of the foundation 2 is formed so that, among a large number of support pile joint points 6 to which the support piles 4 are joined, the support pile joint points 6 located at positions where the depth from a ground surface 7 to the supporting layer 3 is relatively large are positioned deeper underground than the support pile joint points 6 located at positions where the depth from the ground surface 7 to the supporting layer 3 is relatively small.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a pile foundation structure in which a plurality of support piles extending from the bottom of a building foundation to a support layer in the ground are dispersedly arranged.

Background Art

[0002] Patent Document 1 shows a pile foundation structure having a plurality of support piles extending from the bottom of a building foundation to a support layer. In this cited Document 1, while the ground surface is horizontal, the support layer is inclined, and the depths to the support layer at each of a number of support pile joint locations where the pile foundation at the bottom of the foundation is joined are different. Therefore, due to the different depths from the bottom of the foundation to the support layer, the lengths of the support piles are also different. In a pile foundation structure having a plurality of support piles extending from the bottom of a building foundation to a support layer, when the pile lengths of the plurality of support piles are different, the rigidity (EI / L) of the support pile with a large pile length becomes smaller than the rigidity (EI / L) of the support pile with a small pile length. Therefore, due to the difference in rigidity depending on the pile length, the entire building may exhibit a torsional behavior, and the soundness of the support piles may be impaired. Here, E is the Young's modulus, I is the second moment of inertia, and L is the pile length.

[0003] Therefore, as shown in Patent Document 1, it has been proposed to increase the diameter of the support pile with a relatively large pile length relative to the diameter of the support pile with a relatively small pile length to increase the rigidity, thereby reducing the difference in rigidity depending on the pile length and suppressing the occurrence of torsional behavior of the entire building.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, as in Patent Document 1, if the diameter of the support pile with a relatively large pile length is made larger than the diameter of the support pile with a relatively small pile length, there are problems such as an increase in the amount of concrete or the like constituting the support pile, a large-scale construction of the support pile, and a significant increase in cost. In addition, when an existing pile is used as a support pile, there are restrictions on the pile diameter depending on the construction method, so there is a risk that the support pile cannot be handled with a regulated pile due to an increase in the diameter of the support pile, and there is also a problem of cost increase in this regard.

[0006] In view of this actual situation, the main problem of the present invention is to provide a pile foundation structure that can suppress the behavior of the entire building from twisting by reducing the difference in rigidity due to the pile length while suppressing the increase in cost by providing no difference in the diameter of the support piles or reducing the difference in the diameter of the support piles.

Means for Solving the Problems

[0007] The first characteristic configuration of the present invention is in a pile foundation structure in which a plurality of support piles extending from the bottom of the building foundation to the underground support layer are dispersedly arranged. The bottom of the foundation is formed such that among a plurality of support pile joints to which the support piles are joined, the support pile joint at a position where the depth from the ground surface to the support layer is relatively large is located deeper in the ground than the support pile joint at a position where the depth from the ground surface to the support layer is relatively small.

[0008] Due to the inclination of one or both of the ground surface and the support layer, the depth from the ground surface to the support layer at the position where there are a plurality of support pile joints is different. According to this configuration, the bottom of the foundation is formed such that the support pile joints are located at depths corresponding to the depth from the ground surface to the support layer, and the difference in the lengths of the plurality of support piles can be reduced. Therefore, without providing a difference in the diameter of the support piles or reducing the difference in the diameter of the support piles to suppress the increase in cost, the difference in rigidity due to the pile length can be reduced, and the behavior of the entire building from twisting can be suppressed.

[0009] The second characteristic configuration of the present invention is that in a building, a basement floor is arranged at a position where the depth from the ground surface to the support layer is relatively large, and no basement floor is arranged at a position where the depth from the ground surface to the support layer is relatively small.

[0010] According to this configuration, by providing a basement floor at the support pile joint location where the depth from the ground surface to the support layer is relatively large, the support pile joint location can be positioned at a relatively deep position in the ground. Therefore, the support pile joint location can be effectively utilized as a location for providing a basement floor.

[0011] The third characteristic configuration of the present invention is that the depth positions of a large number of support pile joint locations at the bottom of the foundation are set so that the difference in the pile lengths of the large number of support piles is within a predetermined range.

[0012] According to this configuration, it is possible to equalize the depth from each support pile joint location to the support layer at each support pile joint location, and reduce the difference in the lengths of the large number of support piles. Therefore, it is possible to suppress the bending rigidity of the large number of support piles within a desired range without providing a difference in the diameters of the support piles or while reducing the difference in the diameters of the support piles.

Brief Description of the Drawings

[0013]

Figure 1

Embodiments for Carrying Out the Invention

[0014] An embodiment of the pile foundation structure according to the present invention will be described with reference to the drawings. As shown in FIG. 1, the pile foundation structure is a structure that supports the upper building part 1A composed of a column-beam framework or the like in the building 1, and a large number of support piles 4 are dispersedly arranged from the bottom of the foundation 2 of the building 1 to the support layer 3 in the ground. The pile foundation structure includes a foundation 1B below the building part 1A and a large number of support piles 4 dispersedly arranged over substantially the entire bottom of the foundation 2 of the foundation 1B. The base bottom 2 is formed such that, among a number of support pile joint locations 6 such as the bottom of a footing where the pile heads of the support piles 4 are joined, the support pile joint location 6 at a position where the depth from the ground surface 7 to the support layer 3 is relatively large is positioned deeper in the ground than the support pile joint location 6 at a position where the depth from the ground surface 7 to the support layer 3 is relatively small.

[0015] In the example shown in FIG. 1, the ground surface 7 is horizontal while the support layer 3 is inclined, so that the depth from the ground surface 7 to the support layer 3 at the positions where there are a number of support pile joint locations 6 is different. To add an explanation, the support layer 3 is inclined so as to descend as it goes to the left side X1 in FIG. 1, and the depth from the ground surface 7 to the support layer 3 at the positions where there are a number of support pile joint locations 6 becomes larger as it goes to the left side X1.

[0016] Also, in the example shown in FIG. 1, twelve support piles 4 as a number of support piles 4 are joined to the base bottom 2 of the building 1 in a state of being arranged in the left - right direction X, and twelve support pile joint locations 6 are provided. Among the twelve support pile joint locations 6, the three support pile joint locations 6 to which three support piles 4 are joined from the left side X1 are support pile joint locations 6 (hereinafter referred to as the first support pile joint location 6A) at positions where the depth from the ground surface 7 to the support layer 3 is relatively large, and the remaining nine support pile joint locations 6 to which the other support piles 4 are joined are support pile joint locations 6 (hereinafter referred to as the second support pile joint location 6B) at positions where the depth from the ground surface 7 to the support layer 3 is relatively small.

[0017] And the first support pile joint location 6A is provided in the left - hand portion 2A located at the end of the left side X1 in the base bottom 2, and the second support pile joint location 6B is provided in the right - hand portion 2B located on the right side X2 of the left - hand portion 2A in the base bottom 2. The base bottom 2 is formed such that the left - hand portion 2A is positioned deeper in the ground than the right - hand portion 2B. By providing a step in the base bottom 2 in this way, among the number of support pile joint locations 6, the first support pile joint location 6A is formed to be positioned deeper in the ground than the second support pile joint location 6B.

[0018] The depth positions of a large number of support pile joints 6 at the foundation bottom 2 are set so that the differences in the pile lengths of the large number of support piles 4 are within a predetermined range. To add an explanation, the difference between the longest pile length of the support piles 4 joined to the second support pile joint 6B and the shortest pile length of the support piles 4 joined to the second support pile joint 6B is set as the predetermined range. By forming the foundation bottom 2 as described above and keeping the pile lengths of the support piles 4 joined to the first support pile joint 6A within the predetermined range, the differences in the pile lengths of the large number of support piles 4 are within the predetermined range.

[0019] In the building 1, a basement floor 8 having a basement or an underground pit space or the like is arranged at the first support pile joint 6A, and the basement floor 8 is not arranged at the second support pile joint 6B. In the present embodiment, the basement floor 8 is arranged in the range where the first support pile joint 6A exists from the left end of the building 1, and the basement floor 8 is not arranged on the right side X2 from this range. In this way, in the building 1, by partially arranging the basement floor 8 at the location where the first support pile joint 6A exists, as described above, the foundation bottom 2 is formed so that the differences in the pile lengths of the large number of support piles 4 are within the predetermined range.

[0020] As shown in FIG. 1, only the ground surface 7 among the ground surface 7 and the support layer 3 is inclined, so that the depths from the ground surface 7 to the support layer 3 at the positions where there are a large number of support pile joints 6 are different. However, as described above, the foundation bottom 2 is formed so that the first support pile joint 6A is located deeper in the ground than the second support pile joint 6B among the large number of support pile joints 6 to which the support piles 4 are joined. Therefore, the foundation bottom 2 is formed so that the support pile joints 6 are located at depths corresponding to the depths from the ground surface 7 to the support layer 3. Therefore, it is possible to equalize the depths from each support pile joint 6 to the support layer 3 at each support pile joint 6, and it is possible to reduce the difference in the lengths of the large number of support piles 4. Therefore, while suppressing cost increase by using support piles of the same diameter as the large number of support piles, it is possible to reduce the difference in rigidity due to the pile length and suppress the building as a whole from causing torsional behavior.

[0021] 〔Alternative Embodiment〕 Another embodiment of the present invention will be described. Note that the configurations of the embodiments described below are not limited to being applied independently, and can also be applied in combination with the configurations of other embodiments.

[0022] (1) In the above embodiment, the case where only the support layer 3 among the ground surface 7 and the support layer 3 is inclined has been described. However, only the ground surface 7 among the ground surface 7 and the support layer 3 may be inclined, or both the ground surface 7 and the support layer 3 may be inclined.

[0023] (2) In the above embodiment, the configuration in which the number of basement floors 8 is 1 has been described as an example. However, the configuration in which the number of basement floors 8 is 2 or more may also be used. And, for example, when the number of basement floors 8 is 2, a basement first floor may be arranged in the left side X1 portion of the building 1, and a basement second floor may be arranged in the left side X1 portion of the range where the basement first floor is arranged.

[0024] (3) In the above embodiment, the bottom of the footing has been shown as an example of the support pile joint location 6 at the bottom of the foundation 2. However, it may be the bottom of the foundation slab, the bottom of the foundation beam, etc., as long as it is a location where the pile head of the support pile 4 is joined.

[0025] (4) In the above embodiment, the cost increase has been suppressed by not providing a difference in the diameters of a large number of support piles. However, even if there is a difference in the diameters of a large number of support piles, the cost increase may be suppressed by making the difference small.

[0026] (5) In the above embodiment, the pile foundation structure has been shown as an example. However, it may also be a design method for the pile foundation structure for designing the said pile foundation structure.

Explanation of Reference Numerals

[0027] 1 Building 2 Foundation Bottom 3 Support Layer 4 Support Pile 6 Support Pile Joint Location 7 Ground Surface

Claims

1. In a pile foundation structure in which a plurality of bearing piles extending from the bottom of a building foundation to a supporting layer underground are dispersedly arranged, the bottom of the foundation is formed such that, among a plurality of bearing pile joints to which the bearing piles are joined, a bearing pile joint at a position where the depth from the ground surface to the supporting layer is relatively large is positioned deeper underground than a bearing pile joint at a position where the depth from the ground surface to the supporting layer is relatively small.

2. The pile foundation structure according to claim 1, wherein in a building, a basement is arranged at a position where the depth from the ground surface to the supporting layer is relatively large, and no basement is arranged at a position where the depth from the ground surface to the supporting layer is relatively small.

3. The pile foundation structure according to claim 1 or 2, wherein the depth positions of a plurality of bearing pile joints at the bottom of the foundation are set such that the difference in the pile lengths of the plurality of bearing piles is within a predetermined range.

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