New structure

Abstract

To provide a new structure that can be constructed using existing piles.SOLUTION: A new structure 1 is constructed by reusing existing piles 11, 12 of an existing structure 10. The new structure 1 includes the existing piles 11, 12 and a new superstructure 2 constructed on the existing piles 11, 12. The settlement stiffness K, K' of the existing piles 11, 12 before removal of the existing superstructure 13 is represented by settlement curves L, L', and the points on the settlement curves L, L' when removal of the existing superstructure 13 begins are defined as unloading start points P, P', and the residual settlement of the existing piles 11, 12 after removal of the existing superstructure 13 is defined as the unloading completion points Q, Q'; the settlement stiffness KE, KE' of the existing piles 11, 12 after removal of the existing superstructure 13 is represented by the reloading curves LE, LE' connecting the unloading completion points Q, Q' and the unloading start points P, P', and is greater than the settlement stiffness K, K' of new piles with the same shape as the existing piles 11, 12.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a new structure constructed by reusing existing piles of an existing structure. [Background technology]

[0002] Conventionally, there have been new structures constructed by reusing existing piles (see Patent Document 1). Patent Document 1 proposes a foundation structure in which a pile head load adjustment member is provided between the existing pile and the new foundation slab to adjust the load acting on the existing pile. Patent Document 2 shows a foundation structure for a new structure that uses existing piles. In order to change and adjust the settlement rigidity of the existing piles against settlement, a cylindrical pile head with a larger horizontal cross-sectional area than the existing piles is provided at the upper end of the existing piles. Patent Document 3 shows a foundation structure for a new building that uses existing piles. The existing piles are semi-rigidly connected to the new foundation, and new piles are rigidly or semi-rigidly connected to the new foundation. This allows the existing piles to bear a smaller horizontal force than the new piles. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2017-122364 [Patent Document 2] Japanese Patent Application Publication No. 2017-36572 [Patent Document 3] Patent No. 4683520 Summary of the Invention [Problem to be solved by the invention]

[0004] An object of the present invention is to provide a new structure that can be constructed using existing piles. [Means for solving the problem]

[0005] A new structure (for example, new structure 1 described later) of the first invention is a new structure constructed by reusing existing piles (for example, existing piles 11 and 12 described later) of an existing structure (for example, existing structure 10 described later), wherein the existing structure comprises the existing piles and an existing superstructure (for example, existing superstructure 13 described later) constructed on the existing piles, and the new structure comprises the existing piles and a new superstructure (for example, new superstructure 2 described later) constructed on the existing piles, and the existing The settlement stiffness of the existing piles before the removal of the superstructure (for example, settlement stiffness K, K′ described later) is expressed by a settlement curve (for example, settlement curve L, L′ described later), and the points on the settlement curve at the start of the removal of the existing superstructure are set as unloading start points (for example, unloading start points P, P′ described later), the residual settlement of the existing piles when the pile head load is zero after the removal of the existing superstructure is set as unloading completion points (for example, unloading completion points Q, Q′ described later), and the settlement stiffness of the existing piles after the removal of the existing superstructure (for example, K E , K. E ′) is a reloading curve (for example, L ′ described later) connecting the unloading completion point and the unloading start point. E , L E The settlement stiffness of the existing pile after the removal of the existing superstructure is greater than the settlement stiffness of a new pile of the same shape as the existing pile (for example, the settlement stiffnesses K and K' described below).

[0006] According to this invention, a new superstructure is constructed on top of the existing piles from which the existing superstructure has been removed, and is supported by the existing piles. In this case, the settlement stiffness of the existing piles before the removal of the existing superstructure is represented by a settlement curve, the point on the settlement curve at the start of the removal of the existing superstructure is set as the unloading start point, the residual settlement of the existing piles when the pile head load is zero after the removal of the existing superstructure is set as the unloading completion point, and the settlement stiffness of the existing piles after the removal of the existing superstructure is represented by a reloading curve connecting the unloading completion point and the unloading start point. Research and development on the settlement stiffness of existing piles has revealed that the settlement stiffness of the existing piles after the removal of the existing superstructure is greater than the settlement stiffness of new piles of the same shape as the existing piles. Therefore, since the existing piles can withstand a greater vertical load during reloading than new piles of the same shape as the existing piles, the vertical support capacity of the existing piles is utilized to the maximum extent, and the new superstructure that will be constructed on top of the existing piles after the existing superstructure is removed is supported by the existing piles alone, or by both the existing piles and the new piles.

[0007] In the case where the existing piles (for example, the existing piles 11 described later) are straight piles or enlarged piles, the new structure of the second invention calculates the reduction in the settlement of the existing piles after the removal of the existing superstructure, S, using the formulas (1) and (2) described later. p is calculated, and the residual settlement of the existing piles after the removal of the existing superstructure is the reduction in the settlement of the existing piles from the settlement at the start of unloading, S p In the case where an enlarged diameter portion (for example, an enlarged diameter portion 12A described later) is provided in the middle of the existing pile (for example, the existing pile 12 described later), the reduction in the settlement of the existing pile after the removal of the existing superstructure, S, is calculated using the formulas (3) and (4) described later. m is calculated, and the residual settlement of the existing piles after the removal of the existing superstructure is the reduction in the settlement of the existing piles from the settlement at the start of unloading, S m It is characterized in that it is calculated by subtracting

[0008] According to this invention, the reduction in the settlement of the existing piles after the removal of the existing superstructure is calculated, and the residual settlement at the completion of unloading is calculated by subtracting the reduction in the settlement of the existing piles from the settlement at the start of unloading. Therefore, the residual settlement at the completion of unloading can be calculated with high accuracy. [Effects of the Invention]

[0009] According to the present invention, a new structure can be provided that can be constructed using existing piles. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a schematic side view of a new structure according to a first embodiment of the present invention. FIG. [Figure 2] FIG. 2 is a schematic side view of an existing structure used in the new structure of the first embodiment. [Figure 3] 1 is a flowchart of a procedure for designing a new structure according to the first embodiment. [Figure 4] FIG. 1 is an explanatory diagram of the design procedure for a new structure according to the first embodiment (a diagram showing the settlement curve and reload curve of an existing pile). [Figure 5] 4 is a flowchart of a procedure for calculating the amount of residual settlement when designing a new structure according to the first embodiment. [Figure 6] FIG. 10 is a schematic side view of a new structure according to a second embodiment of the present invention. [Figure 7] 10 is a flowchart of a procedure for designing a new structure according to the second embodiment. [Figure 8] FIG. 10 is a schematic side view of an existing pile according to a modified example of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0011] The present invention is a new structure with a new superstructure that is constructed on the existing piles after the existing superstructure has been removed. The new structure of the first embodiment is supported only by the existing piles (Figs. 1 to 5). The new structure of the second embodiment is supported by new piles in addition to the existing piles (Figs. 6 and 7). DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In the following description of the embodiments, the same components will be denoted by the same reference numerals, and the description thereof will be omitted or simplified. [First embodiment] Fig. 1 is a schematic side view of a new structure 1 according to a first embodiment of the present invention. Fig. 2 is a schematic side view of an existing structure 10. The new structure 1 is constructed by reusing the existing piles 11 and 12 of the existing structure 10. The existing structure 10 comprises an existing pile 11 which is a straight pile, an existing pile 12 which has an expanded diameter portion 12A in the middle, and an existing superstructure 13 constructed on the existing piles 11 and 12. The new structure 1 comprises existing piles 11, 12 and a new superstructure 2 constructed on the existing piles 11, 12.

[0012] The procedure for designing the new structure 1 will be described below with reference to the flowchart of FIG.

[0013] In step S1, as shown in FIG. 4, subsidence curves L, L' representing the subsidence stiffness (relationship between pile head load and subsidence amount) K, K' are generated for the existing piles 11, 12 before the existing superstructure 13 is removed. Figure 4(a) shows the settlement curve L and reload curve L for the existing pile 11, which is a vertical pile. E 4(b) shows the subsidence curve L′ and the reload curve L for the existing pile 12 having the enlarged diameter portion 12A in the middle. E In Fig. 4(a) and Fig. 4(b), the solid lines are the settlement curves L and L', and the dashed dotted line is the reloading curve L. E , L E '.

[0014] In step S2, as shown in FIG. 4, points on the subsidence curves L and L' at the start of removal of the existing superstructure 13 are set as unloading start points P and P'. In step S3, as shown in Figure 4, the residual settlement of the existing piles 11, 12 when the pile head load is zero after the existing superstructure 13 is removed is set as the unloading completion points Q, Q'. The procedure for calculating this residual settlement will be described in detail later. In step S4, as shown in FIG. 4, the unloading completion points Q, Q′ and the unloading start points P, P′ are connected to calculate the settlement stiffness (relationship between pile head load and settlement amount) K for the existing piles 11, 12 after the removal of the existing superstructure 13. E , K. E Reloading curve L representing E , L E The settlement stiffness K of the existing piles 11 and 12 after the existing superstructure 13 is removed is generated. E , K. E ' is greater than the settlement stiffness K, K' of the new piles having the same shape as the existing piles 11, 12.

[0015] In step S5, the new superstructure 2 is designed. Specifically, the settlement stiffness K E , K. ESince ' has been calculated, the settlement stiffness K E , K. E Based on this, the amount of settlement of the existing piles 11, 12 when the new superstructure 2 is reloaded can be calculated, and the new superstructure 2 is designed so that it can be supported by the existing piles 11, 12.

[0016] The procedure for calculating the residual subsidence amount in step S3 will be described below with reference to the flowchart of FIG. First, in step S11, the reduction in the amount of settlement S of the existing piles 11 and 12 after the removal of the existing superstructure 13 is calculated. p , S m Calculate the following.

[0017] Specifically, for the existing pile 11, which is a straight pile, the reduction in the amount of settlement of the existing pile 11 after the removal of the existing superstructure 13 is S p is calculated using the following formulas (1) and (2).

number

[0018]

number

[0019] In addition, for the existing pile 12 having an enlarged diameter portion 12A in the middle portion, the reduction in the amount of settlement of the existing pile 12 after the removal of the existing superstructure 13 is S m is calculated using the following equations (3) and (4).

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[0020]

number

[0021] In step S12, as shown in FIG. 4, the residual settlement of the unloading completion points Q and Q' of the existing piles 11 and 12 after the removal of the existing superstructure 13 is calculated by subtracting the reduction in the settlement of the existing piles S from the settlement of the unloading start points P and P'. p , S m Calculate by subtracting.

[0022] The procedure for constructing the new structure 1 is as follows. First, only the existing superstructure 13 of the existing structure 10 is removed. This leaves the existing piles 11 and 12 remaining. Thereafter, the new superstructure 2 is constructed on top of the existing piles 11 and 12.

[0023] According to this embodiment, the following effects are obtained. (1) The settlement stiffness K, K' of the existing piles 11, 12 before the removal of the existing superstructure 13 is represented by the settlement curves L, L', the points on the settlement curves L, L' at the start of the removal of the existing superstructure 13 are the unloading start points P, P', the residual settlement of the existing piles 11, 12 when the pile head load is zero after the removal of the existing superstructure 13 is represented by the unloading completion points Q, Q', and the settlement stiffness of the existing piles 11, 12 after the removal of the existing superstructure 13 is represented by the reloading curve L connecting the unloading completion points Q, Q' and the unloading start points P, P'. E , L EResearch and development was conducted on the settlement rigidity of the existing piles 11, 12 (the relationship between pile head load and amount of settlement) and revealed that the settlement rigidity of the existing piles 11, 12 after the existing superstructure 13 is removed is greater than the settlement rigidity of new piles of the same shape as the existing piles 11, 12. Therefore, the existing piles 11, 12 can bear a larger vertical load during reloading than if the existing piles 11, 12 were newly installed, and therefore the new superstructure 2 that is constructed on the existing piles 11, 12 after the existing superstructure 13 is removed can be supported by only the existing pile 11. (2) The reduction in the amount of settlement of the existing piles 11 and 12 after the removal of the existing superstructure 13, S p , S m The residual settlement at the completion of unloading is calculated by subtracting the settlement at the start of unloading from the settlement of the existing pile, S p , S m Therefore, the residual settlement after unloading can be calculated with high accuracy.

[0024] (3) In the new structure 1 supported by the existing piles 11, 12, the load is appropriately shared by the existing piles 11, 12, thereby improving the stability and earthquake resistance of the new structure 1. In addition, by making maximum use of the vertical support capacity of the existing piles 11, 12 and sharing the load on the new structure 1, a strong foundation structure can be constructed. (4) For the new structure 1, the points on the settlement curves L and L′ at the start of the removal of the existing superstructure 13 are set as the unloading start points P and P′, and the residual settlement of the existing piles 11 and 12 at zero pile head load after the removal of the existing superstructure 13 is set as the unloading completion points Q and Q′. The unloading completion points Q and Q′ and the unloading start points P and P′ are connected to determine the settlement stiffness K of the existing piles 11 and 12 after the removal of the existing superstructure 13. E , K. E Reloading curve L representing E , L E Therefore, the vertical bearing capacity (vertical bearing force) of the existing pile 11 can be reasonably evaluated. In addition, by taking into account the residual settlement of the existing piles 11, 12 and the vertical bearing capacity (vertical bearing force) of the existing piles, the vertical bearing force and horizontal resistance force of the new structure 1 supported by the existing piles 11, 12 can be reasonably evaluated.

[0025] Second Embodiment FIG. 6 is a vertical cross-sectional view of a new structure 1A according to the second embodiment of the present invention. The new structure 1A is constructed by reusing the existing piles 11 and 12 of the existing structure 10. The new structure 1A comprises existing piles 11, 12, a new pile 3, and a new superstructure 2A constructed on the existing piles 11, 12 and the new pile 3.

[0026] The procedure for designing a new structure will be explained below with reference to the flowchart in FIG. Steps S1A to S4A are the same as steps S1 to S4 in the first embodiment. In step S5A, the new pile 3 and the new superstructure 2A are designed. Specifically, the settlement stiffness K E , K. E Since ' has been calculated, the settlement stiffness K E , K. E Based on this, the amount of settlement of the existing piles 11, 12 when the new superstructure 2 is reloaded can be calculated. Therefore, the new piles 3 and the new superstructure 2A are designed so that the new superstructure 2A can be supported by the existing piles 11, 12 and the new piles 3. According to this embodiment, the same effects as those (1) to (4) described above are obtained.

[0027] The present invention is not limited to the above-described embodiment, and modifications and improvements within the scope of achieving the object of the present invention are included in the present invention. For example, in this embodiment, the existing piles of the existing structure 10 are the existing pile 11, which is a straight pile, and the existing pile 12, which has an enlarged portion 12A in the middle, but this is not limiting, and an existing pile 14, which is an enlarged pile, may also be used as shown in Fig. 8. Note that for the existing pile 14, which is an enlarged pile, the residual settlement is calculated using the same procedure as for the existing pile 11, which is a straight pile. [Explanation of symbols]

[0028] 1, 1A...New structure 2, 2A...New superstructure 3...New pile 10...Existing structure 11...Existing straight pile 12... Existing pile with an enlarged diameter portion in the middle 12A... Enlarged diameter portion 13... Existing superstructure 14... Existing pile with enlarged base

Claims

1. A new structure constructed by reusing existing piles of an existing structure, The existing structure includes the existing piles and an existing superstructure constructed on the existing piles, The new structure comprises the existing piles and a new superstructure constructed on the existing piles, The settlement stiffness of the existing piles before the removal of the existing superstructure is represented by a settlement curve, The point on the settlement curve at the start of removal of the existing superstructure is set as the unloading start point, The residual settlement of the existing pile when the pile head load is zero after the removal of the existing superstructure is defined as the unloading completion point, The settlement stiffness of the existing pile after the removal of the existing superstructure is represented by a reloading curve connecting the unloading completion point and the unloading start point, A newly constructed structure characterized in that the subsidence rigidity of the existing piles after the removal of the existing superstructure is greater than the subsidence rigidity of new piles of the same shape as the existing piles.

2. When the existing piles are straight piles or enlarged piles, the reduction in the amount of settlement of the existing piles after the removal of the existing superstructure, S, is calculated by the following formulas (1) and (2). ｐ is calculated, and the residual settlement of the existing piles after the removal of the existing superstructure is calculated by subtracting the decrease in the settlement of the existing piles from the settlement at the start of unloading S ｐ It is calculated by subtracting When an enlarged diameter portion is provided in the middle of the existing pile, the reduction in the amount of settlement of the existing pile after the removal of the existing superstructure, S, is calculated by the following formulas (3) and (4). ｍ is calculated, and the residual settlement of the existing piles after the removal of the existing superstructure is calculated by subtracting the decrease in the settlement of the existing piles from the settlement at the start of unloading S ｍ The new structure according to claim 1, characterized in that it is calculated by subtracting the above. ...Formula (1) Here, S ｐ (m): Decrease in settlement of pile tip, d ｐ (m): Pile tip diameter, R ｐ (kN): Hang tip load, A ｐ (m ２ ): Hang apex cross-sectional area, (R ｐ / A ｐ )u(kN / m ２ ): Extreme front-end support strength, α: Initial wiring of the curve, n: the degree that determines the curve shape, ...Formula (2) Here, R ｐ１ (kN): Load just before unloading R ｐ (kN): Unloaded load (i.e., R ｐ１ (reduction in load from S ｐ (m): R ｐ The reduction in settlement caused by α': initial tangent gradient of the curve, initial stiffness K calculated by equation (1) ０ and the deformation coefficient of the ground E ０ The initial stiffness K calculated from Ｅ０ Coefficient obtained by multiplying the ratio of ν: Poisson's ratio of the ground a: Coefficient for changing the curve shape when unloading, a = (R pu + R p1 ) / R pu , and ...Formula (3) Here, S ｍ (m): Decrease in the amount of sinking of the enlarged diameter portion, d ｍ (m): diameter of the expanded portion, R ｍ (kN): Load on the expanded diameter portion, A ｍ (m ２ ): Cross-sectional area of the expanded diameter part, (R ｍ / A ｍ )u(kN / m ２ ): The ultimate support strength of the wide diameter part, α″: initial tangent gradient of the curve of the converging portion, n: order determining the curve shape, ...Formula (4) Here, R ｍ１ (kN): Load just before unloading R ｍ (kN): Unloaded load (i.e., R ｍ１ (reduction in load from S ｍ (m): R ｍ The reduction in settlement caused by α′′′ is the initial tangent gradient of the curve, and is the initial stiffness K calculated using equation (3). ０ ' and the deformation coefficient of the ground E ０ The initial stiffness K calculated from Ｅ０ Coefficient obtained by multiplying the ratio of ' by α a': Coefficient for changing the curve shape when unloading, a' = (R ｍu + R ｍ1 ) / R ｍu , is.

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