Settlement suppression structure for spread foundation

Abstract

To suppress settlement exceeding a predetermined amount while allowing settlement up to a predetermined amount, for a structure supported on a spread foundation.SOLUTION: A settlement suppression structure for a spread foundation comprises a spread foundation that supports a structure, and settlement suppression members that are buried in the ground with a vertical gap from the underside of the spread foundation and that suppress the amount of settlement of the spread foundation within an allowable value.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to a settlement suppression structure for a direct foundation.

Background Art

[0002] In the differential settlement control method for a foundation described in Patent Document 1, a settlement control pile having a spring mechanism that expands and contracts in the vertical direction built into the pile head is combined with a foundation structure that supports a structure, and a part of the weight of the structure is transferred from the foundation structure to the settlement control pile as the structure sinks.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In reclaimed land and newly constructed land, the ground composition is different. In such a case, for a structure that adopts a direct foundation, the strength of the ground that supports the direct foundation also varies depending on the part that supports the direct foundation. Then, the settlement amount of the structure with respect to the ground differs between one part of the structure and another part. In such a case, a method of driving piles with different lengths according to the depth of the ground, a method of using a hybrid foundation of a direct foundation and a pile foundation, etc. are adopted.

[0005] The problem of the present disclosure is to suppress settlement exceeding a predetermined amount for a structure supported by a direct foundation, after allowing a predetermined amount of settlement.

Means for Solving the Problems

[0006] The settlement suppression structure for a direct foundation according to the first aspect includes a direct foundation that supports a structure, and a settlement suppression member that is buried in the ground at a vertical distance from the lower surface of the direct foundation and suppresses the settlement amount of the direct foundation within an allowable value.

[0007] According to the above aspect, when a load within the assumed range is applied to the structure by wind, earthquake, or the like, the structure is supported by the ground, and the separated state between the direct foundation and the settlement suppression member is maintained. On the other hand, when a strong earthquake beyond the assumption occurs and the structure attempts to settle beyond a predetermined settlement amount, the load applied to the structure is directly transmitted from the direct foundation of the structure to the settlement suppression member. Thereby, the settlement of the structure is suppressed.

[0008] In this way, for a structure adopting a direct foundation, after allowing a predetermined amount of settlement, it is possible to suppress settlement exceeding the predetermined settlement amount.

[0009] The settlement suppression structure of the direct foundation according to the second aspect is the settlement suppression structure of the direct foundation described in the first aspect, wherein the settlement suppression member is columnar and extends in the vertical direction.

[0010] According to the above aspect, the load applied to the structure from the direct foundation of the structure is transmitted to the settlement suppression member from the top of the columnar settlement suppression member. Thereby, compared with the case where the load applied to the structure is transmitted to a settlement suppression member extending in the horizontal direction, it is possible to effectively suppress the settlement of the structure exceeding the predetermined settlement amount.

[0011] The settlement suppression structure of the direct foundation according to the third aspect is the settlement suppression structure of the direct foundation described in the second aspect, wherein the direct foundation is supported by a soft layer of the ground, the settlement suppression member extends in the vertical direction, and the lower end portion of the settlement suppression member is embedded in a support layer stronger than the soft layer.

[0012] According to the above aspect, the lower end portion of the settlement suppression member is embedded in a support layer stronger than the soft layer. Thereby, the load directly transmitted from the structure to the settlement suppression member is transmitted to the support layer. In this way, compared with the case where the lower end portion of the settlement suppression member does not reach the support layer, it is possible to effectively suppress the settlement of the structure exceeding the predetermined settlement amount.

[0013] The settlement suppression structure of the direct foundation according to the fourth aspect is the settlement suppression structure of the direct foundation described in the second aspect, wherein a part of the direct foundation is supported by the soft layer of the ground, and another part of the direct foundation is supported by a support layer stronger than the soft layer, and the settlement suppression member extends in the vertical direction and is vertically separated from the lower surface of a part of the direct foundation, and the lower end portion of the settlement suppression member is embedded in a support layer stronger than the soft layer.

[0014] According to the above aspect, a part of the direct foundation of the structure is supported by the soft layer, and another part is supported by the support layer. And the settlement suppression member is vertically separated from the lower surface of a part of the direct foundation, and the lower end portion of the settlement suppression member is embedded in the support layer. Thereby, the settlement of the structure can be suppressed in a well-balanced manner.

Effect of the Invention

[0015] According to the present disclosure, in a structure supported by a direct foundation, it is possible to suppress settlement exceeding a predetermined settlement amount after allowing a predetermined amount of settlement.

Brief Description of the Drawings

[0016]

Figure 1

Figure 2

Figure 3

Mode for Carrying Out the Invention

[0017] An example of a structure supported by a direct foundation according to an embodiment of the present disclosure will be described with reference to FIGS. 1 to 3. The arrow H shown in each figure indicates the vertical direction, which is the up-and-down direction of the structure supported by the direct foundation, the arrow W shown in each figure indicates the width direction of the structure, which is orthogonal to the arrow H and is a horizontal direction, and the arrow D shown in each figure indicates the depth direction of the structure, which is orthogonal to the arrows H and W and is a horizontal direction.

[0018] (Overall configuration) The settlement suppression structure 10 (hereinafter referred to as "settlement suppression structure 10") according to the present embodiment is used for a structure 100 constructed using a direct foundation 100a, as shown in FIG. 1.

[0019] This structure 100 is constructed so as to straddle the ground support layer 110a and the ground soft layer 110b. Specifically, a part on one side (the right side in the figure) in the width direction of the structure 100 is supported by the soft layer 100b, and a part on the other side (the left side in the figure) in the width direction of the structure 100 is supported by the support layer 110a, which is stronger than the soft layer 100b. In other words, a part of the direct foundation 100a is supported by the soft layer 110b of the ground 110, and another part of the direct foundation 100a is supported by the support layer 110a, which is stronger than the soft layer 110b.

[0020] Furthermore, below the soft layer 110b that supports the structure 100, the support layer 110a on the other side in the width direction extends and penetrates. That is, a support layer 110a is formed below the soft layer 110b.

[0021] The settlement suppression member 12 that constitutes the settlement suppression structure 10 is buried in the ground 110 at a vertical distance from the lower surface of the part of the direct foundation 100a supported by the soft layer 110b. As an example, the support layer 110a is composed of bedrock, and the soft layer 110b is composed of embankment soil.

[0022] (Main part configuration) In this embodiment, the settlement suppression member 12 is a columnar H-shaped steel extending in the vertical direction, and a plurality of such members are provided. Specifically, as shown in FIG. 1 when viewed from the depth direction, a plurality of settlement suppression members 12 are arranged side by side in the width direction. And the settlement suppression member 12 arranged on one side in the width direction is disposed directly below the foundation 100a at the portion on one side in the width direction.

[0023] Also, as shown in FIG. 2 when viewed from the width direction, a plurality of settlement suppression members 12 are arranged side by side in the depth direction. And the settlement suppression member 12 arranged on the back side (right side in the figure) in the depth direction is disposed directly below the foundation 100a at the portion on the back side in the depth direction, and the settlement suppression member 12 arranged on the front side (left side in the figure) in the depth direction is disposed directly below the foundation 100a at the portion on the front side in the depth direction.

[0024] Further, as shown in FIGS. 1 and 2, the upper end of the settlement suppression member 12 is vertically spaced from the lower surface of the direct foundation 100a. In this embodiment, the upper end of the settlement suppression member 12 and the lower surface of the direct foundation 100a are spaced apart by about 25 [mm] to 30 [mm] in the vertical direction. That is, during normal times when a major earthquake or the like has not occurred, the load from the direct foundation 100a is not directly transmitted to the settlement suppression member 12. Here, the separation distance between the upper end of the settlement suppression member 12 and the lower surface of the direct foundation 100a is a predetermined value (allowable value) that allows settlement in the structure 100, and is a settlement amount such that no damage occurs to the structure 100.

[0025] Here, the lower end portion of the settlement suppression member 12 is embedded in the support layer 110a, and the upper portion with respect to the lower end portion of the settlement suppression member 12 is embedded in the soft layer 110b. That is, the lower end portion of the settlement suppression member 12 is supported by the support layer 110a.

[0026] As described above, since the settlement suppression member 12 is vertically separated from the direct foundation 100a, it is not a member constituting the structure 100. That is, in the building confirmation application for the structure 100, there is no need to describe the settlement suppression member 12 in the application documents. In other words, the structure 100 conforms to the Building Standards Act in a state without the settlement suppression member 12.

[0027] (Function) Next, the function of the settlement suppression structure 10 will be described.

[0028] When a load within the assumption is applied to the structure 100 due to wind, earthquake, etc., as shown in FIGS. 1 and 2, the structure 100 is supported by the ground 110, and the separated state between the settlement suppression member 12 and the direct foundation 100a is maintained.

[0029] On the other hand, when an unexpected strong earthquake occurs and an unexpected load is applied to the structure 100, due to the application of this unexpected load, the part of the structure 100 supported by the soft layer 110b may sink.

[0030] However, when the structure 100 sinks, as shown in FIG. 3, the distance between the upper end of the settlement suppression member 12 and the lower surface of the direct foundation 100a becomes narrower, and the load applied to the structure 100 is directly transmitted from the direct foundation 100a to the settlement suppression member 12. Thereby, the settlement suppression member 12 supports the structure 100 from below, suppressing the settlement of the structure 100. In this way, the settlement suppression member 12 functions as a stopper.

[0031] That is, the settlement amount of the structure 100 is limited by the settlement suppression member 12. In other words, settlement to the extent that the structure 100 is not damaged is allowed, and settlement to the extent that the structure 100 is damaged is suppressed.

[0032] (Summary) As described above, in the settlement suppression structure 10, when an unexpected strong earthquake occurs, the settlement amount of the structure 100 can be restricted. That is, for the structure 100 adopting a direct foundation, after allowing a predetermined amount of settlement, the settlement exceeding the predetermined settlement amount can be suppressed.

[0033] Further, in the settlement suppression structure 10, since the settlement amount of the structure 100 is restricted, damage to the structure 100 can be suppressed.

[0034] Further, in the settlement suppression structure 10, the settlement suppression member 12 is columnar and extends in the vertical direction. Thereby, compared with the case where the load of the structure is transmitted to the settlement suppression member extending in the horizontal direction, the settlement of the structure exceeding the predetermined settlement amount can be effectively suppressed.

[0035] Further, in the settlement suppression structure 10, the lower end portion of the settlement suppression member 12 is embedded in the stronger support layer 110a compared with the soft layer 110b. Thereby, the load directly transmitted from the structure 100 to the settlement suppression member 12 is transmitted to the support layer 110a via the settlement suppression member 12. In this way, compared with the case where the lower end portion of the settlement suppression member does not reach the support layer, the settlement of the structure 100 exceeding the predetermined settlement amount can be effectively suppressed.

[0036] Further, in the settlement suppression structure 10, since the settlement suppression member 12 is separated from the direct foundation 100a, it is not a member constituting the structure 100. Therefore, compared with the case of suppressing settlement by adopting a pile foundation, a simple configuration can be achieved.

[0037] Further, in the settlement suppression structure, the settlement suppression member 12 is separated from the direct foundation 100a. Thereby, for the settlement suppression member 12, a unique specification can be determined separately from the specification conditions of the structure 100. Therefore, compared with the case of suppressing the settlement of the structure 100 by a pile foundation, the construction period can be shortened and the cost increase can be suppressed.

[0038] In the settlement suppression structure 10, the structure 100 is disposed at a portion where the ground composition is different. Specifically, the structure 100 is disposed so as to straddle the support layer 110a and the soft layer 110b. Therefore, by providing the settlement suppression member 12 at the portion of the soft layer 110b where the structure 100 may sink when an unexpected strong earthquake occurs, it is possible to effectively suppress the tilting of the structure 100. In other words, it is possible to suppress the settlement of the structure exceeding a predetermined settlement amount in a well-balanced manner.

[0039] In the settlement suppression structure 10, the settlement suppression member 12 is provided directly below the horizontal end portion of the direct foundation 100a. Thereby, compared with the case where the settlement suppression member 12 is provided only at the horizontal central portion of the direct foundation, the settlement of the structure 100 can be effectively suppressed.

[0040] Although the present disclosure has been described in detail with respect to specific embodiments, it is obvious to those skilled in the art that the present disclosure is not limited to such embodiments and that various other embodiments can be taken within the scope of the present disclosure. For example, in the above embodiment, the H-shaped steel is used as the settlement suppression member 12, but a pipe material or ground improvement may be used. It may be a member that is separated from the direct foundation 100a during normal times and to which the load of the structure 100 is directly transmitted when the structure 100 sinks due to an unexpected earthquake or the like.

[0041] In the above embodiment, the H-shaped steel is used as the settlement suppression member 12, but the pile member formed by the regulated pile method may be disposed separately from the direct foundation 100a. It may be a member that is separated from the direct foundation 100a during normal times and to which the load of the structure 100 is directly transmitted when the structure 100 sinks due to an unexpected earthquake or the like.

[0042] In the above embodiment, the direct foundation 100a of the structure 100 is disposed so as to straddle the support layer 110a and the soft layer 110b, but the direct foundation may be disposed only on the soft layer. In this case, the settlement suppression member 12 is disposed so as to suppress the settlement of the entire direct foundation.

[0043] In addition, although not particularly described in the above embodiment, when the structure 100 sinks while inclining about the support layer 110a, the separation distance between the settlement suppression member 12 far from the support layer 110a and the direct foundation 100a may be made longer than the separation distance between the settlement suppression member 12 close to the support layer 110a and the direct foundation 100a so that the load from the direct foundation 100a is directly transmitted to all the settlement suppression members 12.

Explanation of Signs

[0044] 10 Settlement suppression structure 12 Settlement suppression member 100 Structure 100a Direct foundation 110 Ground 110a Support layer 110b Soft layer

Claims

1. A direct foundation for supporting a structure, A settlement suppression member that is buried in the ground above and below the lower surface of the direct foundation and suppresses the settlement amount of the direct foundation within an allowable value, A settlement suppression structure for a direct foundation comprising the above.

2. The settlement suppression member is columnar and extends in the vertical direction, The settlement suppression structure for a direct foundation according to Claim 1.

3. The direct foundation is supported by a soft layer of the ground, The settlement suppression member extends in the vertical direction, and the lower end portion of the settlement suppression member is buried in a support layer that is stronger than the soft layer, The settlement suppression structure for a direct foundation according to Claim 2.

4. A part of the direct foundation is supported by a soft layer of the ground, and another part of the direct foundation is supported by a support layer that is stronger than the soft layer, The settlement suppression member extends in the vertical direction, is spaced above and below the lower surface of a part of the direct foundation, and the lower end portion of the settlement suppression member is buried in a support layer that is stronger than the soft layer, The settlement suppression structure for a direct foundation according to Claim 2.

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