JPH09209373A - Structure for taking measure for structure from liquefaction - Google Patents

Abstract

PROBLEM TO BE SOLVED: To minimize the effect of ground liquefaction, particularly on existing structures. SOLUTION: A cylindrical ring frame 5 is constructed in the ground G below the outer periphery of a tank 1, with the upper end of the ring frame 5 integrated with the outer periphery of the foundation 3 of the tank 1 via coping 6 and with the lower end located inside a liquefaction layer G1. Also, the lower end of the ring frame 5 may be located inside a non-liquefaction layer G2 so that it can sink. Further, piles may be placed in place of the ring frame 5.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquefaction of a structure which is suitable for being applied to a structure such as an existing tank (storage tank) installed on the ground where liquefaction may occur when an earthquake occurs. It is related to the countermeasure structure.

[0002]

2. Description of the Related Art Generally, an existing structure (constructed by the former Fire Defense Law) installed on a soft ground, such as a ground tank, may liquefy the ground below when an earthquake occurs. . At this time, the ground below the center of the tank is difficult to liquefy because it is pressed down by the weight of the tank, while the ground below the outer periphery of the tank is
Since the pressing force is smaller than the central part, and the force that the tank tries to rotate in the horizontal direction largely acts on the ground (rocking phenomenon), it has the property of being easily liquefied.

Therefore, conventionally, the following structure (construction method) has been adopted as a countermeasure against the liquefaction of the ground when such an existing tank is subjected to an earthquake. First, there is a structure in which a highly rigid cylindrical continuous wall that reaches a strong support layer is placed in the ground around the tank.

As another structure, there is also a structure in which a reinforcing material such as a rod-shaped anchor is obliquely inserted into the ground from the periphery of the tank toward the vertically downward position of the center of the tank.

[0005]

However, the conventional structure liquefaction countermeasure structure as described above has the following problems. First, in the structure of constructing a cylindrical continuous wall in the ground around the tank, when the ground directly below the tank is liquefied, the outer peripheral portion of the tank is supported on the strong support layer by the continuous wall. Since the amount of subsidence is small due to the presence of liquefaction, the amount of subsidence is large in the central part due to the influence of liquefaction, and a so-called unequal subsidence phenomenon occurs. As a result, the tank body may be distorted.

On the other hand, in the structure in which the reinforcing material is obliquely inserted from the periphery of the tank toward the center, the ground at the outer peripheral portion of the tank, which is the weakest point during the liquefaction of the ground, is not strengthened, so a fundamental measure against the liquefaction is taken. There is a problem that can not be said.

The present invention has been made in consideration of the above points, and particularly provides a structure liquefaction countermeasure structure capable of minimizing the influence of the liquefaction of the ground in an existing structure. The task is to do.

[0008]

The invention according to claim 1 is
A structure for preventing liquefaction of a structure constructed on a soft liquefaction layer, in which a pile or continuous wall is constructed in the ground below the outer periphery of the structure, and the upper end of the pile or continuous wall is The structure is integrated with the outer peripheral portion of the structure, and the lower end portion is located in the liquefied layer of the ground or in the non-liquefied layer on the strong support layer.

According to a second aspect of the present invention, there is provided a liquefaction countermeasure structure for a structure constructed on a soft liquefaction layer, wherein the outer periphery of the structure is located in the ground below the outer periphery of the structure. A first ground anchor extending vertically downward from the portion, and a second ground anchor diagonally extending from the outer peripheral portion of the structure toward the vertically downward position of the central portion thereof are placed, and The upper end of each of the first and second ground anchors is integrated with the outer peripheral portion of the structure, and the lower end is fixed to a strong support layer located below the liquefaction layer.

[0010] The invention according to claim 3 is the invention according to claim 1 or 2.
In the structure liquefaction countermeasure structure described, the liquefaction layer below at least the outer peripheral portion of the structure is improved.

The invention according to claim 4 is the invention according to claims 1 to 3
In the liquefaction countermeasure structure of the structure according to any one of
The structure is an existing structure, and the pile or continuous wall, ground anchor, and ground improvement are post-constructed.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION First to fifth embodiments of a structure liquefaction countermeasure structure according to the present invention will be described below with reference to FIGS.

[First Embodiment] Here, first, an example will be described in which a continuous wall having, for example, a cylindrical shape is constructed in the ground below the outer peripheral portion of the structure.

As shown in FIG. 1, an existing gas storage tank (structure) 1 is, for example, a liquefied layer G1 whose surface layer portion is easily liquefied, and a non-liquidified portion below the liquefied layer G1 which is difficult to liquefy. It is constructed on the ground layer G2 in which the chemical layer G2 and the supporting layer G3 therebelow are strong. The tank 1 includes a tank body 2 having a cylindrical shape in plan view and a liquefied layer G.
1 and a concrete foundation 3 having a predetermined thickness formed on the surface layer 1.

The liquefaction countermeasure structure of the ground G in which such an existing tank 1 is constructed is as follows. In the ground G immediately below the outer peripheral portion of the tank 1, a cylindrical ring frame (continuous wall) 5 along the outer peripheral portion of the tank 1 is provided.
Is being built. The ring frame 5 is configured by arranging a plurality of reinforced concrete sheet piles in a ring shape. The lower end of the ring frame 5 is located at a predetermined depth in the liquefied layer G1, and the upper end of the ring frame 5 is surrounded by the annular coping 6 made of reinforced concrete. It is integrated with the outer peripheral portion of the base 3.

Further, the liquefied layer G1 below the tank 1
The outer peripheral portion of the tank 1 and the annular portion 7 inside the coping 6 are ground-improved and solidified.

In order to realize such a liquefaction countermeasure structure, first, a plurality of sheet piles forming the ring frame 5 are provided on the outer peripheral side of the foundation 3 of the existing tank 1, for example, 2 to 3 m, and the liquefaction layer G1 of the ground G is provided. Drive to the specified depth inside. For driving the sheet pile, a driving method by hammering / vibration, an embedding method for embedding in a previously excavated hole, a press-fitting method, or the like is used.

After the ring frame 5 is constructed in this manner, the tank 1 is removed from the gap between the ring frame 5 and the foundation 3.
The annular portion 7 of the liquefaction layer G1 below the outer periphery of the base 3 of
The ground is improved and solidified by various ground improvement methods such as a chemical solution injection method and a high-pressure injection stirring method.

Next, the ground G near the upper end of the constructed ring frame 5 is dug down to expose the upper end of the ring frame 5. Then, by constructing a reinforced concrete coping 6 here, the ring frame 5 and the tank 1 are formed.
Integrate with the foundation 3 of. This completes the construction of the liquefaction countermeasure structure for the tank 1 shown in FIG.

In the liquefaction countermeasure structure of the tank 1 described above,
A ring frame 5 is constructed in the ground G below the outer periphery of the tank 1, the upper end of the ring frame 5 is integrated with the outer periphery of the foundation 3 of the tank 1 via the coping 6, and the lower end is liquefied. It is configured to be located in the layer G1. The ring frame 5 can generate vertical and horizontal resistance forces in the liquefied layer G1 of the ground G, thereby reducing the rocking phenomenon of the tank 1 even if the liquefied layer G1 is liquefied when an earthquake occurs. be able to. Also,
Since the ring frame 5 can block excess water pressure generated in the liquefied layer G1 on the outer side of the ring frame 5, the tank 1
It is possible to suppress the deformation of the liquefied layer G1 that supports the structure during an earthquake. In addition, since the lower end of the ring frame 5 is located in the liquefied layer G1 and does not reach the strong support layer G3, even if the liquefied layer G1 is liquefied, It is possible to prevent a large difference in the amount of subsidence between the central portion and the outer peripheral portion, thereby reducing unequal subsidence and preventing the tank 1 from being distorted. In this way, the influence of the liquefaction of the liquefaction layer 1 of the ground G on the existing tank 1 can be significantly reduced as compared with the conventional case.

[Second Embodiment] Next, a second embodiment of the structure liquefaction countermeasure structure according to the present invention will be described. Here, an example of the case where the lower end of the ring frame 5 is located in the non-liquefaction layer G2 and the range of ground improvement is expanded in contrast to the liquefaction countermeasure structure of the tank 1 shown in the first embodiment above Will be explained. In the following description, the same components as those in the first embodiment will be designated by the same reference numerals, and the description thereof will be omitted.

As shown in FIG. 2, in the tank 1, a cylindrical ring frame (continuous wall) 10 is constructed along the outer peripheral portion of the tank 1 in the ground G immediately below the outer peripheral portion thereof. ,
The upper end portion is integrated with the outer peripheral portion of the tank 1 through an annular coping 6 made of reinforced concrete over the entire circumference.

The ring frame 10 has a continuous wall-like structure in which a plurality of steel sheet piles are annularly arranged, and the lower end of the ring frame 10 is located at a predetermined depth in the non-liquefied layer G2. ing. A void 11 is formed below the ring frame 10, which allows the ring frame 10 to sink.

Further, the liquefied layer G1 below the tank 1
The entire surface portion 12 is ground-improved and solidified.

In order to realize such a liquefaction countermeasure structure, the construction method exactly the same as that of the first embodiment is applied, but when a plurality of sheet piles constituting the ring frame 10 is driven, this construction method is applied. After the sheet pile is once driven into the non-liquefied layer G2 to a predetermined depth, it is pulled up to form the voids 11 in the non-liquefied layer G2.

In the liquefaction countermeasure structure of the tank 1 described above,
A ring frame 10 is constructed in the ground G below the outer periphery of the tank 1, and the upper end of the ring frame 10 is a coping 6
It is integrated with the outer peripheral portion of the foundation 3 of the tank 1 via, and the lower end portion is located in the non-liquefied layer G2. As a result, the same effect as that of the first embodiment can be obtained.

Further, the lower end of the ring frame 10 is rooted up to the non-liquefied layer G2, and a void 11 is formed below the non-liquefied layer G2 so that the ring frame 10 can sink. As a result, even when the liquefied layer G1 is liquefied, lateral flow of the tank 1 can be prevented and a strong support structure can be realized. Moreover, the ring frame 10
Can sink, so tank 1 and ring frame 1
By substituting 0 and 0 together, it is possible to suppress uneven subsidence of the tank 1 and prevent the tank main body 2 from being distorted.

Further, since the entire lower surface portion 12 of the tank 1 is ground improved and solidified, a higher liquefaction resistance can be exhibited.

In the second embodiment described above, the ring frame 10 does not necessarily need to be continuous over the entire circumference. For example, when there is a pipe or the like connected to the tank 1, a sheet pile is provided only in that part. It does not have to be arranged. This is because the ring frame 10 does not expect the hoop tension to suppress the movement of the liquefied ground from flowing out from under the foundation.
This is because the flexural rigidity is expected, and the above countermeasure effect can be exerted even in the state where the sheet pile is partially missing. Further, although the ring frame 10 is made of steel sheet pile, it may be made of steel pipe sheet pile, soil mortar wall, concrete underground wall or the like.

[Third Embodiment] Next, a third embodiment of the structure liquefaction countermeasure structure according to the present invention will be described. Here, for example, a case of driving a pile in the ground below the structure will be described as an example. In the following description, the same components as those in the first and second embodiments will be designated by the same reference numerals and the description thereof will be omitted.

As shown in FIG. 3, in the ground G immediately below the outer peripheral portion of the tank 1, a large number of piles 20, 20, ... Are provided at an annular position in plan view along the outer peripheral portion of the tank 1. It is placed every predetermined interval.

Each of the piles 20 is a so-called node pile in which a large number of nodes 20a, 20a, ... Are formed at predetermined intervals along the axial direction, and the lower end portion thereof is located at a predetermined depth in the liquefied layer G1. It is supposed to do. The entire upper end of each pile 20 is integrated with the outer peripheral part of the tank 1 via the annular coping 6 made of reinforced concrete. In this way, the tank 1 is configured to be supported by the comb-shaped frame 21 which is formed in a so-called comb-like shape and is composed of the pile 20 and the coping 6.

Further, the liquefied layer G1 below the tank 1
The outer peripheral portion of the tank 1 and the annular portion 7 inside the coping 6 are ground-improved and solidified.

In order to realize such a liquefaction countermeasure structure, first, piles 20, 20, ... Are provided in the liquefaction layer G1 of the ground G on the outer side of the foundation 3 of the existing tank 1, for example, 2 to 3 m. Drive to the depth. For driving each pile 20, a driving method by hammering / vibration, an embedding method for embedding in a previously excavated hole, or the like is used.

After driving a predetermined number of piles 20 in this way, the liquefied ground G1 below the outer periphery of the foundation 3 of the tank 1
The annular portion 7 is ground-improved and solidified by various ground improvement methods such as a chemical injection method and a high-pressure injection stirring method.

Then, the ground G in the vicinity of the upper ends of the piles 20, 20, ... Is dug down to expose the upper ends of the piles 20, 20 ,. Then, by constructing a reinforced concrete coping 6 here, the piles 20, 20, ...
Integrate with the foundation 3 of. This completes the construction of the liquefaction countermeasure structure for the tank 1 shown in FIG.

In the liquefaction countermeasure structure of the tank 1 described above,
The piles 20, 20, ... In the ground G below the outer periphery of the tank 1.
Are piled up at predetermined intervals, the upper ends of these piles 20 are integrated with the outer periphery of the foundation 3 of the tank 1 via the coping 6, and the lower ends are located in the liquefied layer G1. . As a result, the piles 20, 20, which have been driven into the ground,
By the ..., The ground G can be compacted and liquefaction can be suppressed. Further, the ground G is formed by the comb-shaped frame 21 composed of the piles 20, 20 ,.
It is possible to generate vertical and horizontal resistance forces in the liquefied layer G1 of the liquefied layer G1 of the liquefied layer G1.
Even when 1 is liquefied, the locking phenomenon of the tank 1 can be reduced. Further, since the comb frame 21 can block the excess water pressure generated in the liquefied layer G1 outside thereof, the liquefied layer G1 supporting the tank 1
It is possible to suppress deformation during the earthquake. in addition,
Since the lower end of each pile 20 is located in the liquefied layer G1 and does not reach the strong support layer G3, even if the liquefied layer G1 is liquefied, It is possible to suppress a large difference in the amount of subsidence from the outer peripheral portion, thereby reducing unequal subsidence and preventing the tank body 2 from being distorted. In this way, the existing tank 1 by liquefaction of the liquefaction layer 1 of the ground G
It is possible to significantly reduce the influence on.

[Fourth Embodiment] Next, a fourth embodiment of the structure liquefaction countermeasure structure according to the present invention will be described. For example, the tank 1 shown in the third embodiment above
The liquefaction countermeasure structure of No. 2 will be described using an example in which the range of ground improvement is expanded. In the following description, the same components as those in the third embodiment will be designated by the same reference numerals and the description thereof will be omitted.

As shown in FIG. 4, the tank 1 has piles 30, 30, ..., Such as node piles, at predetermined intervals in the ground G immediately below the outer periphery thereof along the outer periphery of the tank 1. Is placed, and the upper end thereof is integrated with the outer peripheral portion of the tank 1 through the annular coping 6 made of reinforced concrete. In this way, the comb frame 32 including the pile 30 and the coping 6 is formed. Each stake 30
The lower end of the liquefied layer G1 is located at a predetermined depth. Further, the liquefaction layer G1 below the tank 1
The entire surface portion 12 is ground-improved and solidified.

In order to realize such a liquefaction countermeasure structure, the construction method exactly the same as that of the third embodiment is applied.

In the liquefaction countermeasure structure of the tank 1 described above,
The piles 30, 30, ... In the ground G below the outer peripheral portion of the tank 1.
Are piled up at predetermined intervals, the upper ends of these piles 30 are integrated with the outer peripheral part of the foundation 3 of the tank 1 via the coping 6, and the lower ends are located in the liquefied layer G1. . Thereby, the same effect as that of the third embodiment can be obtained. Furthermore, since the entire surface portion 12 below the tank 1 is ground-improved and solidified, it is possible to exhibit higher liquefaction resistance.

In the first to fourth embodiments, the annular portion 7 of the liquefied layer G1 below the tank 1 is used.
Alternatively, although the entire surface portion 12 is configured to improve the ground, the ground may not be modified depending on the size and weight of the tank 1, the soil quality of the liquefied layer G1, and the like.

[Fifth Embodiment] Next, a fifth embodiment of the structure liquefaction countermeasure structure according to the present invention will be described. Here, for example, an example of a case where a ground anchor is placed below a structure will be described. In the following description, the same components as those in the first to fourth embodiments will be designated by the same reference numerals, and the description thereof will be omitted.

As shown in FIG. 5, in the ground G immediately below the outer peripheral portion of the tank 1, a large number of ground anchors 40 are formed at predetermined intervals at an annular position along the outer peripheral portion of the tank 1. 41 is placed in a tension state.

The ground anchor (first ground anchor) 40 is installed so as to extend vertically downward. On the other hand, the ground anchor (second ground anchor) 41 is installed so as to extend obliquely from the outer peripheral portion of the tank 1 toward the vertically downward position of the central portion thereof. The lower ends of the ground anchors 40 and 41 are respectively liquefied layer G1 and non-liquefied layer G2.
Of the tank 1 through the block 42 made of reinforced concrete, the upper end of which is driven into the strong support layer G3.
It is integrated with the outer peripheral portion of the base 3. This block 4
2 has a wedge-like shape whose width dimension gradually decreases from the upper side to the lower side when viewed in cross section. As a result, when a tension force is introduced into the ground anchors 40, 41, the block 42 exerts a compressive force on the ground G.

In order to realize such a liquefaction countermeasure structure, first, ground anchors 40 and 41 are drilled and installed on the outer peripheral side of, for example, 2 to 3 m from the foundation 3 of the existing tank 1. Next, a block 42 is constructed by reinforced concrete on the ground of the outer periphery of the foundation 3, and ground anchors 40, 4
Integrate 1 and foundation 3. Then, a predetermined tension is applied to each ground anchor 40, 41 to fix it. This completes the construction of the liquefaction countermeasure structure for the tank 1 shown in FIG.

In the liquefaction countermeasure structure of the tank 1 described above,
A ground anchor 40 extending vertically downward is placed in the ground G below the outer periphery of the tank 1, and the upper end of the ground anchor 40 is integrated with the outer periphery of the foundation 3 of the tank 1 via a block 42. Is liquefied and the lower end is liquefied layer G1
The structure is fixed to a strong support layer G3 located below. By this ground anchor 40, a vertical load is introduced into the outer peripheral portion of the tank 1, whereby a pressing effect can be imparted to the ground G from the outer peripheral portion of the tank 1, and the liquefied layer G1 can be made difficult to liquefy. it can. In addition, a ground anchor 41 extending obliquely from the outer peripheral portion of the tank 1 toward the vertically lower position of the center portion.
Has been set up. The tensile resistance of the ground anchor 41 can suppress the shear deformation of the liquefied layer G1.

Furthermore, these ground anchors 40,
The upper end of 41 is fixed to a block 42 having a wedge shape in cross section. As a result, the tension applied to the ground anchors 40 and 41 causes the block 4 to move.
The compressive force can be effectively applied to the ground G from 2.
The above effect can be made more prominent. In this way, it is possible to significantly reduce the influence of the liquefaction of the liquefaction layer G1 of the ground G on the existing tank 1 as compared with the conventional case.

In the first to fifth embodiments, the cylindrical tank 1 is used as an example of the structure to which the structure liquefaction countermeasure structure according to the present invention is applied. The present invention can be applied not only to existing structures but also to new structures, regardless of scale, shape, etc.

[0050]

As described above, according to the structure liquefaction countermeasure structure of the first aspect, the pile or the continuous wall is constructed in the ground below the outer peripheral portion of the structure, and the upper end thereof is The structure is integrated with the outer peripheral portion of the structure, and the lower end portion is located in the liquefied layer or the non-liquefied layer on the strong support layer. The piles and continuous walls provided in this way generate vertical and horizontal resistance forces in the ground, thereby reducing the rocking phenomenon of the structure. Moreover, since excess water pressure generated in the ground outside the piles or the continuous wall can be blocked, it is possible to suppress shear deformation of the ground supporting the structure during an earthquake. In addition, since the piles and continuous walls are located in the liquefied layer or non-liquefied layer and the structure does not reach the strong supporting layer, the center of the structure can be maintained even when the ground is liquefied. It is possible to suppress a large difference in the amount of subsidence between the portion and the outer peripheral portion, thereby reducing uneven settlement and preventing distortion in the structure. In addition, when constructing a continuous wall, the bottom end of this continuous wall is rooted in the non-liquefied layer and allowed to sink, so that the lateral flow of the structure even when the liquefied layer is liquefied. Can be prevented. On the other hand, when the pile is constructed, the soil can be compacted by the pile, and liquefaction of the soil can be suppressed also from this point. In this way, the liquefaction structure makes it possible to significantly reduce the influence of the liquefaction of the ground as compared with the conventional case.

According to the structure liquefaction countermeasure structure of the second aspect, in the ground below the outer periphery of the structure, a first ground anchor extending vertically downward from the outer periphery of the structure, A second ground anchor extending from the outer peripheral portion toward the vertically lower position of the center portion is placed, the upper end portion of each of these ground anchors is integrated with the outer peripheral portion of the structure, and the lower end portion is liquefied layer. It is configured to be fixed to a strong support layer located below the. As a result, a vertical load is introduced to the outer peripheral portion of the structure by the first ground anchor, whereby a pressing effect can be imparted from the outer peripheral portion of the structure to the ground, making it difficult to liquefy. Further, the second ground anchor obliquely placed from the outer peripheral portion of the structure toward the vertically lower position of the center portion can suppress shear deformation of the structure due to its tensile resistance.

According to the structure liquefaction countermeasure structure of the third aspect, the ground at least below the outer periphery of the structure is improved. As a result, the resistance to liquefaction can be further increased, and
The effect according to can be made more remarkable.

According to the structure for preventing liquefaction of a structure according to claim 4, the structure is an existing structure, and the pile or the continuous wall, the ground anchor, and the ground improvement are post-constructed. Has become. In this way, by taking measures against liquefaction on the existing structure later, the influence on liquefaction can be significantly reduced as compared with the conventional case.

[Brief description of drawings]

FIG. 1 is a vertical sectional view showing a first example of a structure liquefaction countermeasure structure according to the present invention.

FIG. 2 is a vertical sectional view showing a second example of a structure liquefaction countermeasure structure according to the present invention.

FIG. 3 is a vertical sectional view showing a third example of a structure liquefaction countermeasure structure according to the present invention.

FIG. 4 is a vertical cross-sectional view showing a fourth example of a structure liquefaction countermeasure structure according to the present invention.

FIG. 5 is a vertical sectional view showing a fifth example of the structure liquefaction countermeasure structure according to the present invention.

[Explanation of symbols]

1 tank (structure) 5,10 ring frame (continuous wall) 20,30 pile 40 ground anchor (first ground anchor) 41 ground anchor (second ground anchor) G ground G1 liquefied layer G2 non-liquefied layer G3 Strong support layer

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Nobuhiro Tsuchiya 1-3-2 Shibaura, Minato-ku, Tokyo Shimizu Construction Co., Ltd. (72) Inventor Kazumi Miyata 1-3-2 Shibaura, Minato-ku, Tokyo Shimizu Construction Co., Ltd. (72) Inventor Ken Suzuki 1-3-2 Shibaura, Minato-ku, Tokyo Shimizu Construction Co., Ltd. (72) Inventor Mamoru Kawabe 1-3-2 Shibaura, Minato-ku, Tokyo Shimizu Construction Co., Ltd. ( 72) Inventor Masayoshi Sato 1-3-2 Shibaura, Minato-ku, Tokyo Shimizu Construction Co., Ltd. (72) Inventor Takeyoshi Fukutake 1-3-2 Shibaura, Minato-ku, Tokyo Shimizu Construction (72) Invention Yutaka Fujita 1-3-2 Shibaura, Minato-ku, Tokyo Shimizu Construction Co., Ltd. (72) Inventor Katsuyuki Tamaki 1-3-2 Shibaura, Minato-ku, Tokyo Shimizu Construction Co., Ltd. (72) Inventor Miyamoto Takeshi Shimizuura 1-3-2, Minato-ku, Tokyo Shimizu Corporation

Claims (4)

[Claims] 1. A structure against liquefaction of a structure constructed on a soft liquefaction layer, wherein a pile or a continuous wall is constructed in the ground below the outer periphery of the structure, and the pile or the continuous wall is constructed. The upper end of the wall is integrated with the outer peripheral portion of the structure, and the lower end is located in the liquefied layer of the ground or in the non-liquefied layer on the strong support layer. Liquefaction countermeasure structure of the characteristic structure. 2. A structure for preventing liquefaction of a structure constructed on a soft liquefaction layer, the structure extending vertically downward from the outer peripheral portion of the structure into the ground below the outer peripheral portion of the structure. An existing first ground anchor and a second ground anchor obliquely extending from the outer peripheral portion of the structure toward the vertically downward position of the central portion thereof are placed, and these first and second ground anchors are provided. A liquefaction countermeasure structure for a structure, characterized in that the upper end of each anchor is integrated with the outer periphery of the structure, and the lower end is fixed to a strong support layer located below the liquefaction layer. . 3. The structure liquefaction countermeasure structure according to claim 1 or 2, wherein the liquefaction layer below at least the outer peripheral portion of the structure is ground-improved. Countermeasure structure. 4. The structure for preventing liquefaction of a structure according to claim 1, wherein the structure is an existing structure, and piles or continuous walls, ground anchors, and ground improvement are A liquefaction countermeasure structure for a structure, which has been constructed.