JP3616891B2 - Ground lateral flow countermeasure structure - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a ground side flow countermeasure structure suitable for use as a foundation for various structures such as a building constructed on soft ground, for example, in the vicinity of a revetment.
[0002]
[Prior art]
As is well known, the foundation of various structures such as buildings built on soft ground, for example, loses its support when the ground below liquefies due to an earthquake. They use piles that reach the layer and improve the ground.
[0003]
By the way, in the 1995 Hyogoken-Nanbu Earthquake, the foundations of structures such as buildings and bridges were damaged due to the great damage even though the above liquefaction measures were taken. This damage is due to the lateral flow (horizontal displacement) that accompanies the liquefaction of the ground, which caused the foundation to move in the bridge, resulting in a falling bridge, and the foundation pile to deform in the building. It has become clear.
[0004]
Such damage due to lateral flow of the ground is particularly noticeable in structures near the revetment. As shown in FIG. 7, the revetment 1 moves due to the inertial force of the earthquake and the rigidity reduction due to the liquefaction of the ground G, and accordingly, the structure 2 is dragged by the large lateral flow of the ground G. It is determined that Foundation 3 was damaged.
[0005]
[Problems to be solved by the invention]
However, the conventional techniques as described above have the following problems. In order to prevent the lateral flow of the ground G in the vicinity of the revetment 1, it is the first to strengthen the revetment 1 so that it does not move due to an earthquake, but the owner of the revetment 1 and the buildings located in the vicinity of it etc. In many cases, the owner of the structure 2 is not the same. In this case, the owner of the structure 2 cannot take measures.
[0006]
For this reason, it is considered that the owner of the structure 2 may take measures such as strengthening the ground G by a ground improvement method or the like. However, the lateral flow of the ground G will be completely prevented by such a method. As a result, the construction period and construction cost are extremely enormous. In addition, even if the above measures are applied to the existing structure 2, it is often difficult to improve the ground G in the entire area below the structure 2. In addition, when a pile is used as the foundation 3, in order to avoid the damage caused by the lateral flow as described above, it is necessary to increase the rigidity of the pile by increasing the diameter of the pile or using a material having high hardness. There is no current situation. However, piles that will not be damaged by a strong earthquake with a seismic intensity of 7 will not only increase costs, but also require a large amount of materials. It is also realistic, and it is difficult to obtain a sufficient pile displacement suppression effect with conventional technology.
[0007]
The present invention was made in consideration of the above points, and can maintain its function without being damaged even if lateral flow occurs due to liquefaction of the ground due to an earthquake or the like, It is another object of the present invention to provide a ground side flow countermeasure structure that can be applied to existing structures.
[0008]
[Means for Solving the Problems]
The invention according to claim 1 is embedded in a non-liquefied layer in the ground on the revetment side of the structure located in the vicinity of the revetment as a countermeasure against lateral flow accompanying liquefaction of the ground due to an earthquake or the like. An underground wall is constructed, and another underground wall is constructed on the upstream side in the direction in which the lateral flow of the ground is expected with respect to the structure, and the other underground wall is formed from the upstream side. A flat cross-sectional shape whose width gradually increases toward the structure side is formed, and the flat cross-sectional shape is configured to decrease from the upper side to the lower side in the ground .
[0009]
According to a second aspect of the present invention, in the ground lateral flow countermeasure structure according to the first aspect, the other underground wall has a substantially V-shaped flat cross-sectional shape .
[0010]
The invention according to claim 3 is the ground lateral flow countermeasure structure according to claim 1 or 2, wherein the underground wall is on both sides of the structure with respect to the direction in which the lateral flow of the ground is expected. It is characterized by being extended.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an example of an embodiment of a ground side flow countermeasure structure according to the present invention will be described with reference to FIGS. 1 to 6.
[0012]
[First embodiment]
In the following description, the same reference numerals are given to portions common to FIG. 7 shown as the conventional example.
[0013]
As shown in FIG. 1, as a countermeasure against the ground side flow of the structure 2 located in the vicinity of the revetment 1, the structure 2 has a ground wall 5 built in the ground G on the revetment 1 side, An underground wall (another underground wall) 7 made of, for example, concrete is constructed in the ground G on the opposite side.
[0014]
The underground wall 5 is formed by, for example, a ground improvement body obtained by improving the ground in a columnar shape and continuing a columnar sheet pile, and the lower end portion thereof is the same as the underground continuous wall. It is fully embedded so as to reach the non-liquefied layer G2 below the liquefied layer G1.
[0015]
Furthermore, when the revetment 1 moves due to an earthquake and the ground G 'on the revetment 1 side liquefies from the underground wall 5, the underground wall 5 is soiled on both sides of the subsurface wall 5, that is, on the revetment 1 side. Considering that there is a difference between the pressure and the earth pressure on the structure 2 side, rigidity and strength are set so that the underground wall 5 does not break down due to this, and excessive deformation does not occur. This is because if the underground wall 5 is excessively deformed, a new sliding surface is formed by the underground wall 5.
[0016]
The underground wall 7 moves to the upstream side in the expected direction of movement of the ground G, that is, when the revetment 1 moves to the river or sea side (to the left in the figure) due to an earthquake, the ground G moves to the revetment 1 side. Therefore, in the ground G on the opposite side to the revetment 1, its lower end is built into the non-liquefaction layer G2.
[0017]
As shown in FIGS. 1 and 2, the underground wall 7 has a shape that is obtained by cutting off the tip of the hull. That is, as shown in FIG. 2, the underground wall 7 is substantially V-shaped in a plan view, and is predetermined from the distal end portion 7 a toward the end portions 7 b and 7 b located near both sides of the structure 2. It has a flat cross-sectional shape that is curved with the following curvature. And as shown in FIG. 1, the said flat cross-sectional shape of this underground wall 7 becomes small gradually toward the downward direction from upper direction, and becomes the structure which the front-end | tip part 7a approaches the structure 2 side as it goes below. ing.
[0018]
In the ground side flow countermeasure structure as described above, the underground wall 5 is constructed in the ground G on the side of the revetment 1 of the structure 2 located in the vicinity of the revetment 1, and the expected upstream movement direction of the ground G On the side, the underground wall 7 is constructed. These underground walls 5 and 7 cause the ground G 'on the revetment 1 side to liquefy as the revetment 1 moves due to the earthquake, or the ground G on the opposite side of the revetment 1 with respect to the structure 2 is liquid. Even in the case of the structure, it is possible to prevent the influence from reaching the foundation 3 of the structure 2, thereby improving the earthquake resistance of the structure 2. Moreover, since the underground wall 7 has a shape like a tip of a hull, the liquefied ground G can be smoothly guided to both sides of the structure 2. Further, these underground walls 5 and 7 can be independently provided by the owner on the structure 2 side even when the owners of the structure 2 and the revetment 1 are different. Furthermore, the ground G below the structure 2 is not improved or the foundation 3 is not strengthened, but the ground wall 5 may be provided in the ground G outside the structure 2. It can be minimized, and it does not ask whether the structure 2 is newly established or established.
[0019]
In the above embodiment, the underground wall 5 is provided only on the revetment 1 side of the structure 2, but the underground wall 5 ′ is provided on the revetment 1 side of the structure 2 as shown in FIG. 3. In addition, the two sides of the structure 2 may be extended so as to be substantially U-shaped so as to surround the three sides of the structure 2, thereby achieving a high effect.
In addition, the shape of the underground wall 7 is not limited to the above. For example, as shown in FIG. 4, the both ends 8 a and 8 a of the underground wall (another underground wall) 8 are rolled back to be liquefied. It is also possible to push back the flow of the ground G.
[0020]
Furthermore, the structure 2 and the form of the foundation 3 are not questioned. For example, as shown in FIGS. 5 and 6, the pier (structure) 11 of the bridge 10 is similarly applied to the ground side according to the present invention. It is possible to apply the counterflow structure. 5 and 6, the U-shaped underground wall 5 'is provided. Needless to say, the underground wall 5 as shown in FIG. 1 may be provided. .
In addition, the underground walls 5, 5 ′ and 7 do not ask the material, can be installed easily, at low cost and in a short construction period, and can exhibit a sufficient ground side flow countermeasure effect. Any of them may be used.
[0021]
【The invention's effect】
As explained above, according to the ground lateral flow countermeasure structure according to claim 1, the underground wall rooted in the non-liquefied layer is formed in the ground on the bank side of the structure located in the vicinity of the bank. built for the structure, the upstream side in the direction lateral flow of the ground is expected, other underground wall is constructed, which is a width spreads gradually toward the upstream side to the structure side Rights It has a cross-sectional shape and the flat cross-sectional shape becomes smaller from the upper side to the lower side in the ground .
In addition, according to the ground lateral flow countermeasure structure according to the third aspect, the underground wall has a structure that is extended and constructed on both sides thereof in the direction in which the lateral flow of the ground is expected.
In this way, by providing an underground wall or other underground wall on the revetment side or upstream of the ground flow direction, the revetment moves due to an earthquake, and when the ground liquefies along with this, It is possible to prevent the influence from reaching the foundation of the structure, thereby increasing the earthquake resistance of the structure. Moreover, this underground wall can be provided by the owner on the structure side even when the owner of the structure and the bank is different. Furthermore, since it is only necessary to provide an underground wall in the ground outside the structure, the construction period and cost can be minimized, and it does not ask whether the structure is newly installed or existing.
[Brief description of the drawings]
FIG. 1 is an elevational sectional view showing an embodiment of a structure to which a ground side flow countermeasure structure according to the present invention is applied.
2 is a cross-sectional plan view of FIG. 1. FIG.
FIG. 3 is a plan sectional view showing another example of the embodiment.
FIG. 4 is a plan sectional view showing still another example of the embodiment.
FIG. 5 is an elevational sectional view showing another application example of the ground lateral flow countermeasure structure according to the present invention.
6 is a plan sectional view of FIG. 5. FIG.
FIG. 7 is an elevational sectional view showing a state in which a conventional liquefaction countermeasure is damaged by an earthquake.
[Explanation of symbols]
1 Revetment 2 Structure 5, 5 'Underground wall 7, 8 Underground wall (other underground walls)
11 Pier (structure)
G, G 'ground

Claims (3)

As a countermeasure against lateral flow due to ground liquefaction due to earthquakes, etc., a ground wall built in a non-liquefied layer is built in the ground located on the revetment side of the structure located near the revetment. , Another underground wall is constructed on the upstream side in the direction in which the lateral flow of the ground is expected with respect to the structure, and the other underground wall extends from the upstream side toward the structure side. A ground side flow countermeasure structure characterized by having a flat cross-sectional shape in which the width gradually increases and the flat cross-sectional shape becoming smaller from the upper side to the lower side in the ground. 2. The ground lateral flow countermeasure structure according to claim 1, wherein the other underground wall has a substantially V-shaped flat cross section. The ground side flow countermeasure structure according to claim 1 or 2, wherein the underground wall is constructed to extend on both sides of the structure in a direction in which the side flow of the ground is expected. Ground side flow countermeasure structure.

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