Vibration reducing ground structure, and construction method of the same

Abstract

To provide a vibration reducing ground structure and a construction method of the same which can reduce vibration without using vibration-isolating materials to block ground vibrations and can avoid increase in environmental load caused by disposal of vibration-isolating materials.SOLUTION: A vibration reducing ground structure 500 is constructed by a friction pile member 10 and reflective layer portions 11, 12. The reflective layer portions 11, 12 include: pipe members 11P, 12P embedded in a ground 5 to be improved; and property-changed soils 11S, 12S that are present within the pipe members 11P, 12P and that utilize the soil of the ground 5 to have a property of attenuating vibrations input into the pipe members 11P, 12P, by reflection. The friction pile member 10 has a characteristic of attenuating, by reflection, vibrations that are input through the property-changed soil 11S.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a vibration reducing ground structure capable of reducing the transmission of vibration through the ground, and a method for constructing the same. [Background technology]

[0002] Patent Document 1 discloses a foundation pile for a building that uses prefabricated piles with a circular cross section, in which steel pipes are arranged concentrically at a fixed interval on the top of the foundation pile body, and vibration-isolating material for blocking ground vibrations is attached to the gap between the foundation pile body and the steel pipes or to part of the gap, and the steel pipes deform when an earth pressure acts on them, thereby disclosing a foundation pile equipped with a ground vibration blocking function that has sufficient rigidity not to generate an amount of compression in part of the vibration-isolating material that would significantly reduce the vibration-isolating performance. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 5-280046 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the above-mentioned conventional ground structure, vibration-proofing materials are required in the gap between the foundation pile body and the steel pipe or in part of the gap to block ground vibrations. Furthermore, if such ground is to be further improved, there is a risk that the vibration-proofing materials will become waste and cause a large environmental burden.

[0005] In view of the above circumstances, an object of the present invention is to provide a vibration-reducing ground structure and a method for constructing the same, which can reduce vibration without using vibration-damping materials to block ground vibrations and avoid the increase in environmental burden caused by the disposal of vibration-damping materials. [Means for solving the problem]

[0006] In order to solve the above-mentioned problems, the vibration-reducing ground structure of the present invention is characterized in that a reflective layer is constructed having a pipe member embedded in the ground to be improved, and characteristic-changing soil that is present within the pipe member and that utilizes the soil of the ground to have the characteristic of attenuating vibrations input to the pipe member by reflection.

[0007] With the above configuration, vibrations input from the ground to the characteristic-changed soil are reflected by the characteristic-changed soil, and the transmission of vibrations through the ground can be reduced. The characteristic-changed soil is clearly separated from the soil of the ground by the pipe member, making it easier to reflect vibrations. Furthermore, there is no need to use vibration-proofing materials to block vibrations, so an increase in environmental load can be avoided, and since the soil of the ground is used, almost no waste soil is generated.

[0008] The characteristic change soil may include friction pile members that have the property of attenuating the vibrations that pass through the characteristic change soil by reflection. This allows the ground to be improved to one that can both support the building and reduce vibrations by the friction pile members. In addition, the attenuation of the vibrations that enter the friction pile members from the characteristic change soil in the pipe members can further reduce the impact of vibrations on the building on the ground.

[0009] The frictional resistance of the characteristic-changing soil may be set higher than the frictional resistance of the soil of the ground, thereby improving the building bearing capacity of the friction pile members located in the characteristic-changing soil.

[0010] The reflective layer may be surrounded by one or more layers of other reflective layers made of other pipe members and other property-changing soil that uses the soil of the ground to have a property of attenuating the vibration input to the other pipe members by reflection. In this way, the reflective layer is formed in multiple layers, so that the transmission of vibration through the ground can be further reduced.

[0011] The method for constructing a vibration-reducing ground structure of the present invention is characterized in that the characteristic-changed soil is obtained by subjecting the soil of the ground inside the pipe member before the change to a rolling compaction treatment. With this method, it becomes easy to change the characteristics of the characteristic-changed soil in a direction that makes it harder than the soil of the ground.

[0012] In the above method, the soil of the ground before the change may be mixed with gravel having a higher density than the soil, and then the compaction treatment may be performed. With this method, it is easy to change the properties of the soil so that it becomes harder than the soil of the ground.

[0013] The method for constructing a vibration-reducing ground structure of the present invention is characterized in that the property-changed soil is obtained by mixing a biodegradable plastic into the soil of the ground before the change. With this method, it becomes easy to change the property of the property-changed soil in a direction that makes it softer than the soil of the ground.

[0014] The method for constructing the vibration-reducing ground structure of the present invention is a method for constructing the vibration-reducing ground structure, characterized in that the pipe member is first buried in the soil of the ground, and the friction pile member is driven into the soil of the ground inside the pipe member. With this method, the soil of the ground before the change inside the pipe member can be changed into hard and compacted soil by driving the friction pile member.

[0015] The method for constructing a vibration-reducing ground structure of the present invention is characterized in that the friction pile members are first buried in the soil of the ground, and the pipe members are buried in the soil of the ground so as to surround the friction pile members with the friction pile members at the center. With this method, it is easy to drive the friction pile members accurately into the specified positions, and therefore it is easy to arrange the multiple reflective layer portions adjacent to each other at regular intervals. Effect of the Invention

[0016] According to the present invention, the impact of vibration on a building on the ground can be reduced by attenuating the vibration input from the ground to the pipe member and the vibration input from the characteristic-changing soil in the pipe member to the friction pile member. In addition, since there is no need to use vibration-proofing materials to block vibrations, an increase in environmental load can be avoided, and since the soil of the ground is used, almost no waste soil is generated. [Brief description of the drawings]

[0017] [Figure 1] 1 is an explanatory diagram showing an example of constructing an embodiment of a vibration-reducing ground structure on the ground located under a building to be built. [Diagram 2] 1A and 1B are diagrams showing a multiple reflection section that constitutes an embodiment of a vibration reduction ground structure, in which FIG. 1A is a horizontal cross-sectional view of the multiple reflection section, and FIG. 1B is a vertical cross-sectional view of the multiple reflection section. [Diagram 3] 1 is an explanatory diagram showing an enlarged vertical cross section of a portion of a multiple reflecting portion that constitutes the vibration reducing ground structure of the embodiment. [Figure 4] This is an explanatory diagram showing another embodiment, showing an example of constructing a vibration-reducing ground structure on the ground on the side of a building to be constructed. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings. As shown in Fig. 1, a vibration-reducing ground structure 500 according to the embodiment is constructed on a ground 5 located under a building 6 to be constructed, for example. The vibration-reducing ground structure 500 has a number of multiple reflecting parts 1 located at regular intervals.

[0019] As shown in Figures 2(A) and 2(B), each multiple reflection section 1 is composed of a friction pile member 10 embedded in the ground 5 to be improved, a first reflection layer section 11 located around the friction pile member 10, and a second reflection layer section 12 (another reflection layer section) located around the first reflection layer section 11. The depth of each multiple reflection section 1 is set to be equal to or greater than the wavelength of the input wave to be attenuated, for example, 5.0 m or greater.

[0020] The friction pile member 10 is, for example, a wooden pile, a pile made of waste plastic, a concrete pile, etc. The diameter of this friction pile member 10 is, for example, 100 mm or more. The length of this friction pile member 10 is 5.0 m or more. Note that using the wooden pile or waste plastic pile reduces the environmental load compared to using concrete piles, etc.

[0021] The first reflective layer portion 11 is made up of a first tubular member 11P and a first characteristic change material 11S.

[0022] The first pipe member 11P is made of, for example, a round steel pipe having a diameter of 500 mm or more and a wall thickness of about 5 mm, and the length of this first pipe member 11P is set to 5.0 m or more.

[0023] The first characteristic change soil 11S exists in the first pipe member 11P. The first characteristic change soil 11S is endowed with a characteristic of attenuating the vibration input to the first pipe member 11P by reflection, by utilizing the soil of the ground 5. The above-mentioned characteristic of attenuating by reflection and the method of constructing the characteristic change soil will be described later.

[0024] The second reflective layer portion 12 is made up of a second tubular member 12P and a second characteristic change member 12S.

[0025] The second pipe member 12P is made of, for example, a round steel pipe having a diameter of 1500 mm or more and a wall thickness of about 5 mm, and the length of the second pipe member 12P is set to 5.0 m or more.

[0026] The second characteristic change soil 12S exists in the second pipe member 12P. The second characteristic change soil 12S is endowed with a characteristic of attenuating the vibration input to the second pipe member 12P by reflection, by utilizing the soil of the ground 5. The above-mentioned characteristic of attenuating by reflection and the method of constructing the characteristic change soil will be described later.

[0027] The characteristic of attenuating the above-mentioned reflection in the second characteristic changed soil 12S can be obtained by making at least one of the density and shear wave velocity of the second characteristic changed soil 12S different from at least one of the density and shear wave velocity of the soil of the ground 5.

[0028] Similarly, the characteristic of attenuating the reflection in the first characteristic change soil 11S can be obtained by making at least one of the density and shear wave velocity of the first characteristic change soil 11S different from at least one of the density and shear wave velocity of the soil of the second characteristic change soil 12S.

[0029] In addition, since at least one of the density and shear wave velocity of the friction pile member 10 is different from at least one of the density and shear wave velocity of the first characteristic change soil 11S, the friction pile member 10 has the property of attenuating, by reflection, the vibrations input through the first characteristic change soil 11S.

[0030] The characteristic change soil 11S, 12S or either one of them can be obtained by, for example, temporarily removing the soil of the ground 5, which is the soil in the pipe members 11P, 12P, to the ground, mixing the removed soil with high density gravel, and returning the mixed soil to the pipe members 11P, 12P and compacting it. By changing the mixing ratio of the gravel, at least one of the density, N value, and shear wave velocity of the characteristic change soil 11S, 12S can be changed. When the gravel is added or compacted, the soil of the ground 5 changes in a direction to become harder. It is also possible to add the gravel to the soil of the ground 5, which is the soil in the pipe members, and mix it while stirring the soil.

[0031] The characteristic change soil 12S can be constructed, for example, by inserting a pipe into the soil of the ground 5, which is the soil inside the pipe member 12P, and injecting, for example, liquid biodegradable plastic through the pipe. The biodegradable plastic is decomposed into water and air over a period of several months to several years by burying it in the soil of the ground 5. This makes the characteristic change soil have many voids or an air layer. That is, the soil of the ground 5 can be changed in a direction to become softer. Although it is difficult to construct an air layer, which is advantageous in blocking vibrations, as described above, an air layer can be constructed relatively easily inside the pipe member 12P. The characteristic change soil 11S can also be changed into soft soil by biodegradable plastic, but since it supports the friction pile member 10, it is better to avoid changing in a direction to make it softer.

[0032] The characteristic-changing soils 11S, 12S of the multiple reflection section 1 are clearly separated from the soil of the ground 5 by the pipe members 11P, 12P, so that it is easy to reflect the vibration. In addition, when a large number of the multiple reflection sections 1 are adjacent to each other, the presence of the pipe members 11P, 12P makes it easy to reduce the adjacent intervals.

[0033] [Table 1]

[0034] Next, under the conditions shown in Table 1 and Figure 3, the vibration transmission state of the multiple reflection section 1 was simplified and calculated (further reflected waves of the transmitted wave were omitted from the calculation) using the existing wave equation, and the reduction in the final transmitted wave compared to the input wave was estimated, resulting in an amplitude ratio (amplitude of transmitted wave 3 / amplitude of input wave) of 0.91. In other words, the predicted result showed that the vibration magnitude (amplitude) of the wave (transmitted wave 3) transmitted through the wooden pile, which is the friction pile member 10, would be reduced by approximately 10% compared to the input wave.

[0035] In this way, with the vibration reduction ground structure 500 equipped with the multiple reflection section 1, the impact of vibration on the building 6 on the ground 5 can be reduced by attenuating the vibration input from the ground 5 to the pipe members 11P, 12P in the multiple reflection section 1 and the vibration input from the characteristic change soils 11S, 12S to the friction pile member 10. Since there is no need to use vibration-proofing materials to block vibrations, an increase in the environmental load can be avoided, and since the soil of the ground 5 is used, almost no waste soil is generated.

[0036] By changing the characteristic-changed soil 11S supporting the friction pile member 10 to a harder one (increasing the N value), the frictional resistance of the friction pile member 10 can be made higher than the frictional resistance of the original soil of the ground 5, thereby improving the building bearing capacity of the friction pile member 10.

[0037] In the above example, the multiple reflection section 1 is composed of the friction pile member 10, the first reflection layer section 11, and the second reflection layer section 12 (other reflection layer sections), but is not limited to this and may have a structure without the second reflection layer section 12. On the other hand, the multiple reflection section 1 may have a structure having a third reflection layer section (multiple other reflection layer sections) around the second reflection layer section 12.

[0038] The multiple reflection section 1 may be constructed by driving the friction pile member 10 into the soil of the ground 5, and then burying the pipe member 11P in the soil of the ground 5 so as to surround the friction pile member 10 with the friction pile member 10 at the center. With this method, it is easy to drive the friction pile member 10 accurately into a specified position, so that multiple multiple reflection sections 1 can be easily arranged adjacent to each other at regular intervals.

[0039] On the other hand, the multiple reflection section 1 may be constructed by first burying the pipe member 11P in the soil of the ground 5, and then driving the friction pile member 10 into the soil of the ground 5 inside the pipe member 11P. With this method, the soil of the ground 5 before the change inside the pipe member 11P can be changed into hard, compacted soil by driving the friction pile member 10.

[0040] In the above example, the vibration-reducing ground structure 500 was constructed on the ground 5 located under the building 6 to be constructed, but this is not limiting, and the vibration-reducing ground structure 500 may be constructed on the ground 5 on the side of the building 6 as shown in Fig. 4. In addition, in such a structure, the friction pile members 10 that support the building 6 are not necessarily required, so the structure may omit the friction pile members 10. Furthermore, instead of using the multiple reflecting section 1, for example, a single-layer reflecting section may be used in which the friction pile members 10 and the first reflecting layer section 11 are omitted.

[0041] Although the embodiment of the present invention has been described above with reference to the drawings, the present invention is not limited to the illustrated embodiment. Various modifications and variations can be made to the illustrated embodiment within the same scope as the present invention or within an equivalent scope. [Explanation of symbols]

[0042] 1: Multiple reflection section 5: Ground 6: Building 10: Friction pile member 11: 1st reflective layer section 11P: 1st pipe member 11S: First characteristic change soil 12:Second reflective layer section 12P: 2nd pipe member 12S: Second characteristic change soil 500: Vibration reduction ground structure

Claims

1. A vibration-reducing ground structure characterized by the construction of a reflective layer having a pipe member buried in the ground to be improved and characteristic-changing soil that exists within the pipe member and has the property of attenuating vibrations input to the pipe member by reflection, using the soil of the ground.

2. 2. The vibration reducing ground structure according to claim 1, further comprising a friction pile member disposed within the characteristic changing soil, the friction pile member having a property of attenuating, by reflection, vibrations input through the characteristic changing soil.

3. 3. The vibration reducing ground structure according to claim 2, wherein the frictional resistance of the characteristic changing soil is higher than the frictional resistance of the soil of the ground.

4. A vibration-reducing ground structure as described in any one of claims 1 to 3, characterized in that around the reflective layer section there is provided one or more other reflective layer sections which are made of other pipe members and other characteristic-changing soil which utilizes the soil of the ground to have the property of attenuating vibrations input to the other pipe members by reflection.

5. A method for constructing a vibration-reducing ground structure as described in any one of claims 1 to 3, characterized in that the characteristic-changed soil is obtained by subjecting the soil of the ground within the pipe member before it is changed to a rolling compaction treatment.

6. 6. The method for constructing a vibration-reducing ground structure according to claim 5, characterized in that the soil of the ground before the change is mixed with gravel having a higher density than the soil and then the compaction treatment is carried out.

7. A method for constructing a vibration-reducing ground structure as described in any one of claims 1 to 3, characterized in that the characteristic-changed soil is obtained by mixing biodegradable plastic with the soil of the ground before it is changed.

8. A method for constructing a vibration-reducing ground structure as described in claim 2 or claim 3, characterized in that the pipe member is first buried in the soil of the ground, and the friction pile member is driven into the soil of the ground inside the pipe member.

9. A method for constructing a vibration-reducing ground structure as described in claim 2 or claim 3, characterized in that the friction pile member is first buried in the soil of the ground, and then the pipe member is buried in the soil of the ground so as to surround the friction pile member with the friction pile member at the center.

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