JP3594385B2 - Seismic isolation structure of structure - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a seismic isolation structure for a structure having a drainage function in addition to a buffer function.
[0002]
[Prior art]
Conventionally, as a seismic isolation structure of this kind, a foundation pile installed in the ground, a foundation part of a structure constructed above the foundation pile, and a foundation pile and the foundation part are located between the foundation pile and the foundation part. A thing provided with a large number of gravel is known (Japanese Patent Publication No. 1-44852).
[0003]
[Problems to be solved by the invention]
In the above case, since the structure is discontinuous to the pile via the gravel, even if a horizontal force is applied to the structure during an earthquake, the interposed individual gravel is not interposed. It does not transmit the horizontal force to the pile. Therefore, no tensile stress or shear stress acts on the pile.
[0004]
However, during the years since the seismic isolation structure was built, the buffer layer fluctuated and local cavities were formed due to various vibrations applied from the surroundings, weak earthquakes, and the effects of groundwater. In some cases, it may be difficult to perform the operation as originally designed during a large earthquake.
[0005]
[Means for Solving the Problems]
In order to solve the above-mentioned problem, the present inventors have conceived that the relative positional relationship between a large number of individual granular materials should be generally maintained in the initial state.
The present invention has been made to achieve the above object.
The invention according to claim 1 provides a foundation pile installed in the ground, a foundation portion of a structure constructed above the foundation pile, and a large number of granular bodies between the foundation pile and the foundation portion. And a buffer layer in which flexible bags having a water-permeable function are superimposed.
[0006]
Here, the foundation of the structure is composed of, for example, a foundation of the building itself or a footing provided to support the building as necessary.
As the foundation pile, for example, a ready-made pile such as an RC pile, a PC pile, a PHC pile, a round pile, a node pile, a wooden pile, a steel pipe pile, a steel pipe concrete composite pile, or a cast-in-place pile can be used.
[0007]
The buffer layer is located between the upper part of the foundation pile and the foundation part of the structure, and is used to buffer the impact of an earthquake or the like. It is formed in layers.
The granular material absorbs seismic force due to sliding, frictional movement, rolling, deformation, and the like, and is strong in compressive force and large in surface frictional force. The particle size does not necessarily need to be uniform, and may vary. The flat granular material has a large friction between the granular materials and easily absorbs the seismic force due to the friction between the granular materials. As specific granules, for example, so-called natural gravel, artificial crushed stone, hard waste plastic, and the like can be used.
[0008]
It is preferable that the bag has corrosion resistance, is flexible and has a water-permeable function, and has a strength that does not break with ordinary handling in a state in which the granular material is stored.
The function of water permeability is that the groundwater is a bag, such as a material that is permeable to water itself, a mesh formed in a mesh smaller than the particle size of the granular material, a material with many small holes smaller than the particle size of the granular material, etc. Means passing easily inside and outside As a simple material of the partition material, a plastic, a woven fabric, a nonwoven fabric and the like can be mentioned.
[0009]
The bag preferably has a shape such that the entire bag is flat with the granular body accommodated in the bag so that the bags can be easily stacked in a stacked manner.
The bags may be superimposed in a plurality of stages, or may be arranged in a single stage.
[0010]
BEST MODE FOR CARRYING OUT THE INVENTION
FIG. 1 is a longitudinal sectional view of the seismic isolation structure of the structure, and FIG. 2 is a perspective view of a bag body 60 partially cut away to show the inside.
In FIG. 1, a seismic isolation structure 10 of a structure includes a foundation pile 30 installed in the ground 20, a foundation 40 of a structure constructed on top of the foundation pile 30, and a foundation pile 30 and a foundation of the structure. A buffer layer 50, in which a flexible bag body 60 having a water-permeable function and containing a large number of granular bodies 51, is superposed between the bag section 50 and the portion 40.
[0011]
The foundation pile 30 is installed in the ground 20 at a predetermined interval in a substantially vertical direction to support the weight of the structure. In this case, the foundation pile 30 includes a plurality of knots 31 provided on the outer peripheral surface. Have been.
Further, it is preferable to provide a drain layer (not shown) made of gravel or the like around the foundation pile 30. Thereby, even if the pore water pressure in the ground 20 rises due to the earthquake, the excess pore water rises through the gap between the drain material layers and can move into the buffer layer 50. Therefore, it is possible to prevent a liquefaction phenomenon caused by an earthquake or the like.
[0012]
The foundation 40 of the structure may be constructed by directly installing the foundation of the building itself in the ground 20, but if necessary, a footing for supporting the building is provided. It may be installed on the upper part.
As shown in FIG. 2, the bag body 60 has corrosion resistance, is flexible and has a water-permeable function, and has a strength that is not broken by ordinary handling in a state in which the granular body 51 is housed. A number of small holes (not shown) smaller than the particle size of the granular material 51 are formed in a sheet or the like, and the sheet is formed by sewing in a bag shape.
[0013]
In order to accommodate the granular material 51 in the bag body 60, for example, the bag body 60 is transported to a construction site in a state where one side of the bag body 60 is opened and an opening is provided, and the bag body 60 is inserted into the bag body 60 from the opening. After the gravel or the like as the granular material 51 is filled, the opening is closed and the granular material 51 is sealed in the bag body 60. Alternatively, the granular material 51 may be stored in the bag body 60 in advance in another place such as a factory, and may be transported to the construction place. Perform as appropriate depending on the situation.
[0014]
It is necessary that the amount of the granular material 51 accommodated in the bag body 60 is such that the granular material 51 moves in the bag body 60 and absorbs stress such as an earthquake. , An appropriate amount of the granular material 51 is packed in the bag body 60.
Then, as shown in FIG. 1, a plurality of bags 60 accommodating the granules 51 are densely arranged in a substantially horizontal direction to form the first stage of the buffer layer 50, and a small amount of gravel is sprinkled over the first stage. A gap is not formed between the second step and the second step. After that, similarly to the first stage, the second stage bag 60 is densely stacked, and the third layer and the bag 60 are sequentially stacked on the first stage where the gravel is dispersed. Together, a buffer layer 50 is formed. At this time, it is preferable that the boundaries of the vertically stacked bags 60 are shifted so that the bags 60 of the respective layers do not shift in the horizontal direction. In addition, the bag bodies 60 are arranged closely, so as not to form a gap between the adjacent bag bodies 60, and a gap is formed as a whole by filling the generated gaps and between the steps with gravel. Not to be.
[0015]
In addition, the size of the bag body 60 and the number of steps for stacking the bag bodies 60 can be appropriately changed according to the area and thickness of the buffer layer 50 to be constructed.
Next, a method of constructing the seismic isolation structure 10 having the above configuration will be described.
First, the foundation piles 30 are installed at predetermined intervals below the ground 20 on which the foundation 40 of the structure is to be constructed.
[0016]
And before installing the foundation pile 30, or after installing the foundation pile 30, it is the depth from the vicinity of the head of the foundation pile 30 to the bottom of the foundation 40 of the structure, and the area of the bottom of the foundation 40. A so-called root cutting operation is performed to remove the earth and sand in the ground 20 to form a space for constructing the buffer layer 50 so as to make the space larger.
Next, in the space formed by the root cutting operation, the bag bodies 60 are stacked and arranged in a stacked manner to form the buffer layer 50.
[0017]
After the buffer layer 50 is formed, the foundation 40 of the structure is installed on the upper surface of the buffer layer 50.
In the above construction work, the granular body 51 is housed inside the bag body 60, so that the bag body 60 on the ground surface can be easily transported by any of a machine and human power. In addition, the operation of putting the bag body 60 into the space formed by the root cutting operation from the ground surface can be easily performed in units of the bag body 60.
[0018]
Furthermore, since the granular material 51 is housed inside the bag body 60, it is possible to suppress the dust and the dust generated from the granular material 51 from being blown out by wind or the like in the field work, to be scattered to the outside. This makes it possible to maintain a good working environment around the site construction.
[0019]
【The invention's effect】
The present invention is configured as described above, and has the following effects.
The present invention has a relatively simple structure, and does not transmit the horizontal force to the pile due to the displacement of the granular material of the buffer layer even if a large horizontal force is generated in the structure during an earthquake during an earthquake. Therefore, tensile stress and shear stress do not act on the pile, the design and construction of the pile can be simplified and the economic efficiency can be improved, and the granular material is stored in the bag body and separated, so that the surroundings can be It is possible to prevent the situation of the buffer layer from being changed from the initially set state, and to prevent the occurrence of a local cavity or the like due to various vibrations, weak earthquakes, groundwater and the like. In addition, the liquefaction phenomenon is prevented because the rising water from the deep portion is smoothly dissipated toward the surface of the ground through the gap between the bag having the water permeability function of the buffer layer and the granular material in the bag during the earthquake. In addition, since the granular material is stored in the bag, handling of the granular material and handling such as loading work can be facilitated, and on-site construction can be facilitated, and the environment around the on-site construction is favorable. Can be maintained.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view of a seismic isolation structure.
FIG. 2 is a perspective view of a bag body partially cut away to show the inside.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 Seismic isolation structure 20 Ground 30 Foundation pile 31 Knot part 40 Structural foundation 50 Buffer layer 51 Granular body 60 Bag

Claims (1)

A foundation pile installed in the ground, a foundation portion of a structure constructed above the foundation pile, and a plurality of granular materials accommodated between the foundation pile and the foundation portion, having a water permeable function. A seismic isolation structure for a structure, comprising: a buffer layer formed by overlapping flexible bags.

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