JP3653696B2 - Structure to prevent the floating of underground structures - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a structure for preventing underground structures from floating due to liquefaction of surrounding ground.
[0002]
[Prior art]
As is well known, an underground structure having a density lower than that of the ground may be lifted by a large buoyancy when the ground is liquefied. To prevent this, measures such as preventing liquefaction by improving the ground, increasing the weight of underground structures to balance with buoyancy, and counteracting buoyancy by installing anchors and pull-out resistance piles, etc. Has been taken.
[0003]
In addition, as shown in FIG. 2, a shielding wall 4 that reaches the non-liquefied ground 3 is provided around the underground structure 2 provided in the surrounding ground 1 that may cause liquefaction. A structure is also known in which the ground below the object 2 is surrounded by the shielding wall 4 and the underground structure 2 itself and is isolated from the external ground to prevent the underground structure 2 from being lifted (Japanese Patent No. 2807696). According to this, compared with other conventional construction methods, an excellent anti-lifting effect can be obtained at low cost.
[0004]
[Problems to be solved by the invention]
By the way, in the measures for preventing the floating by the shielding wall 4 as described above, it is necessary to surely isolate the entire lower ground of the underground structure 2 from the external ground. When using a retaining wall or when waterproofing the outer wall surface of the underground structure 2, a slight amount of space is provided between the underground structure 2 and the shielding wall 4 as shown in FIG. In some cases, the gap 5 must be secured. When such a gap 5 is secured, it is assumed that the ground fluidizes in the gap 5 portion, and as shown in FIG. It is assumed that the earth around the lower part of the structure 2 or the earth and sand of the upper part of the underground structure 2 passes through the gap 5 to the lower part of the underground structure 2, and in such a situation It is also assumed that the floating of the structure 2 cannot be effectively prevented.
[0005]
Therefore, there is a need for an effective improvement measure that can make the above-described anti-lifting measure by the shielding wall 4 more reliable.
[0006]
[Means for Solving the Problems]
In view of the above circumstances, the invention of claim 1 is a structure for preventing the underground structure from floating due to liquefaction of the surrounding ground, and surrounds the underground structure by a shielding wall reaching the non-liquefied ground. together, and sealed by a sealing material made of a gap formed between the shield wall and underground structures from non-liquefaction material, between the sealing material and the shielding wall and said ground structure They are characterized in that at least one of them is provided with a cushioning material such as asphalt to cut out the edges .
[0007]
According to a second aspect of the present invention, in the structure for preventing floating of the underground structure according to the first aspect, a concrete material such as poor blended mortar or cement improved soil or a modified soil using a chemical solidifying agent is used as the sealing material. It is characterized by.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 shows an embodiment of the present invention. In the present embodiment, as shown in FIG. 2, the lower ground of the underground structure 2 is surrounded by the shielding wall 4 that reaches the non-liquefied ground 3 to prevent the floating of the underground structure 2. As shown in FIG. 1, the gap 5 is applied when it is necessary to secure a slight gap 5 between the shielding wall 4 and the underground structure 2 due to construction reasons. The sealing material 6 is used for sealing.
[0010]
As described above, even if fluidization occurs in the gap 5 by sealing the gap 5 between the shielding wall 4 and the underground structure 2 with the sealing material 6, the fluidized earth and sand are It is prevented that it goes around from the gap 5 to the lower part of the underground structure 2, and the earth and sand at the upper part of the underground structure 2 is prevented from going around to the lower part of the underground structure 2 through the gap 5. Therefore, the floating of the underground structure 2 can be effectively prevented.
[0011]
The material or form of the sealing material 6 is not particularly limited as long as it can effectively prevent the flow of the earth and sand fluidized in the gap 5, but concrete materials such as poor blended mortar and cement-modified soil are used. Employing the sealing material 6 is particularly suitable because it is easy to construct and advantageous in terms of construction cost. Further, when the sealing material 6 is provided in the gap 5 around the existing underground structure 2, the soil in the gap 5 is solidified with a chemical solidifying agent and the improved soil is used as the sealing material 6. Since the construction is particularly easy, it is preferable. However, the sealing material 6 should not be fluidized per se or damaged by the lifting pressure at the time of liquefaction, and has the strength to withstand it. It needs to be a thing.
[0012]
In the unlikely event of liquefaction, a frictional force is generated between the sealing material 6 and the shielding wall 4 or the underground structure 2 due to the lifting pressure, and an excessive stress is applied to the sealing material 6 due to the frictional force. because it may occur, it keeps edge cutting by interposing a cushioning material, for example asphalt layer or the like therebetween.
[0013]
In addition, as shown in FIG. 1, the position of the sealing material 6 is preferably the lowest part of the gap 5 (the bottom of the underground structure 2). Is not necessarily limited to the lower part, but may be provided in the middle part or upper part of the gap 5, or if necessary, the sealing material 6 may be provided in multiple stages up and down, or the whole gap 5 may be sealed. is not. Of course, it goes without saying that the present invention can be applied not only to newly constructing underground structures but also to existing underground structures.
[0014]
【The invention's effect】
According to the first aspect of the present invention, the floating prevention structure surrounds the underground structure with the shielding wall reaching the non-liquefied ground, and the gap formed between the shielding wall and the underground structure is made of a non-liquefied material. Since sealing is performed with the sealing material, even if fluidization occurs in the gap, the fluidized sediment is prevented from flowing from the gap to the lower part of the underground structure, and the upper part of the underground structure. It is also possible to prevent the earth and sand from passing through the gap to the lower part of the underground structure, so that even if a gap is secured between the shielding wall and the underground structure, the underground structure is not lifted up. It can be effectively prevented.
In addition, a buffer material such as asphalt is interposed between at least one of the sealing material and the shielding wall and the underground structure, so that the sealing material is cut off from the shielding wall and the underground structure, so that it is liquid. It is possible to prevent the sealing material from being damaged due to the fact that excessive stress is not generated in the sealing material due to the frictional force resulting from the lifting pressure when the sealing material is made.
[0015]
The invention of claim 2 uses a concrete material such as poor blended mortar or cement-improved soil or an improved soil using a chemical solidifying agent as the sealing material, so that the construction is easy and advantageous in terms of construction cost. Construction on the surroundings of underground structures is also possible.
[Brief description of the drawings]
FIG. 1 is a schematic diagram showing a floating prevention structure according to an embodiment of the present invention.
FIG. 2 is a schematic view showing a conventional lifting prevention structure.
FIG. 3 is a schematic diagram showing an example when a gap is provided between the shielding wall and the underground structure.
[Explanation of symbols]
1 Surrounding ground 2 Underground structure 3 Non-liquefied ground 4 Shielding wall 5 Gap 6 Sealing material

Claims (2)

A structure for preventing the underground structure from floating due to liquefaction of the surrounding ground, and surrounding the underground structure with a shielding wall reaching the non-liquefied ground, and the shielding wall and the underground structure and sealed by a sealing material a gap formed made of a non-liquefaction material between the buffer material such as asphalt to at least one of between said sealing material and said shielding walls and said ground structure A structure to prevent the floating of underground structures characterized by interposing and cutting them out .   2. The structure for preventing floating of underground structures according to claim 1, wherein concrete material such as poor blended mortar or cement improved soil or improved soil using a chemical solidifying agent is used as the sealing material.

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