JP2000212973A - Lateral flow checking method for liquefied layer and member therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To check or reduce damages to structures due to lateral flow by suppressing flow speed of liquefied layer by a simple suppressing member. SOLUTION: In ground 2 where the formation of a liquefied layer 22 and an upper non-liquefied layer 23 on a lower non-liquefied layer 21 is forecast, the checking members are arranged at least in the lower non-liquefied layer 21 and liquefied layer 22 in the vicinities of a structure 1 constructed through the liquefied layer 22 and the upper non-liquefied layer 23. But they should not be arranged in the upper non-liquefied layer 23.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a countermeasure against lateral flow of ground due to liquefaction.

[0002]

2. Description of the Related Art Conventionally, when a large-scale earthquake occurs, a liquefaction phenomenon may occur on a loose sandy ground having a high groundwater level h as shown in FIG. When the ground surface is inclined or when the revetment structure is deformed, the liquefied layer d between the lower non-liquefied layer c and the upper non-liquefied layer e generates lateral flow g after liquefaction. However, if the external force due to the lateral flow is excessive, damage such as destroying a structure such as the substructure a occurs.

[0003] As a countermeasure against lateral flow, there is a method in which a steel sheet pile b is cast into a cylindrical shape to surround a substructure a, and the inside thereof is solidified by a ground improvement f to suppress the external force of lateral flow. Conceivable. However, if it is designed to withstand the external force of lateral flow, the countermeasures will be very large.

[0004]

SUMMARY OF THE INVENTION It is an object of the present invention to suppress lateral flow by a simple restraining member.

[0005]

SUMMARY OF THE INVENTION The present invention relates to a ground where a liquefied layer and an upper non-liquefied layer are expected to be formed on a lower non-liquefied layer. The lateral non-liquefaction layer is disposed on the lower non-liquefied layer and the liquefied layer around the structure constructed over the entire structure, and the lateral non-liquefied layer is not disposed on the upper non-liquefied layer. Lateral flow deterrence method, or in the ground where a liquefied layer and an upper non-liquefied layer are expected to be formed on a lower non-liquefied layer, at least over the liquefied layer and the upper non-liquefied layer A lateral flow suppressing member disposed in the liquefied layer and the upper non-liquefied layer around the structure to be constructed, and the lateral flow restricting member is not disposed in the lower non-liquefied layer. Or, in the lateral flow suppressing method, the lateral flow suppressing member is liquefied. Upstream of the construct, or downstream, or characterized by arranging around the structure, the lateral flow suppression method, or, in the side lateral flow suppression method,
The structure is a substructure that is constructed over the lower non-liquefaction layer, the liquefaction layer and the upper non-liquefaction layer, the lateral flow suppression method, or on the lower non-liquefaction layer. In the ground where the liquefaction layer and the upper non-liquefaction layer are expected to be formed, at least the lower non-liquefaction layer and the liquefaction layer around the structure constructed over the liquefaction layer and the upper non-liquefaction layer A lateral flow suppressing member, or a ground where a liquefied layer and an upper non-liquefied layer are expected to be formed on a lower non-liquefied layer, wherein the member is arranged and not disposed in the upper non-liquefied layer In the above, characterized by being disposed in the liquefied layer and the upper non-liquefied layer around the structure constructed at least over the liquefied layer and the upper non-liquefied layer, and not disposed in the lower non-liquefied layer, Lateral flow suppressing member, or the lateral flow suppressing member, The stop member is located upstream or downstream of the structure of the liquefied layer, or characterized in that it is arranged around the structure, the lateral flow suppressing member, or, in the lateral flow suppressing member, the structure is a lower part The lateral flow suppressing member is characterized by being a substructure constructed over a non-liquefied layer, a liquefied layer, and an upper non-liquefied layer.

[0006]

Embodiments of the present invention will be described below with reference to the drawings.

<B> Influence on structures due to lateral flow When an earthquake occurs, specific ground 2
A lower non-liquefied layer 21, an intermediate liquefied layer 22, and an upper non-liquefied layer 23 on the ground surface are generated. If the ground surface is sloped,
In the vicinity of a coast or a river, fluid pressure is generated by the flow of the liquefied layer 22, and the upper non-liquefied layer 23 moves due to the lateral flow 3 to cause ground displacement 4, thereby causing earth pressure. Occurs.

When the structure 1 is constructed on at least the liquefied layer 22 and the upper non-liquefied layer 23, the upper non-liquefied layer 22 of the structure 1 is deformed by the ground deformation of the upper non-liquefied layer 23.
A large bending moment is generated in the vicinity of the boundary between the liquefied layer 23 and the liquefied layer 23, and the rate at which the structure is destroyed particularly near the boundary increases.

The building 1 includes piers such as railroads and roads, basic structures such as oil tanks and gas tanks, condominiums, office buildings, factories and other buildings built in the Gulf area, harbor facilities, common ditches, lifelines, etc. There are various things. These are also disposed on the lower non-liquefied layer 21 as necessary.

[0010] By installing a lateral flow suppressing member around the structure 1, the flow velocity of the liquefied layer 22 around the structure 1 is reduced, the ground deformation of the upper non-liquefied layer 23 is suppressed, and the structure 1 is generated. The bending moment near the boundary between the upper non-liquefied layer 23 and the liquefied layer 22 is reduced.

The liquefied layer 22 and the upper non-liquefied layer 23
Can be predicted by calculating the liquefaction resistivity in the determination of liquefaction (for liquefaction determination, for example, "Railway structure design standards, the same description, foundation structure, pile earth pressure structure" railway Comprehensive Research Institute, March 1997, Maruzen Co., Ltd., 7
It is described in section 7.5 Judgment of liquefaction in the discussion on seismic resistance).

<B> Lateral flow suppressing member The lateral flow suppressing member 5 suppresses the lateral flow 3 of the liquefied layer around the structure, and the ground deformation of the upper non-liquefied layer caused by the lateral flow 3 It is to suppress. Lateral flow suppressing member 5
Is desirably a member having a large shear rigidity, and a member having a drainage mechanism is preferable because the occurrence of liquefaction itself can be suppressed and the rigidity of the ground can be increased. For example,
It is desirable that a porous structure or a gravel be attached to a pile of steel or an improved pile. In addition, the lateral flow suppressing member has a pile shape,
Various shapes such as a plate shape, a box shape, and a truss shape can be adopted.

<C> Lateral Flow Suppression Method 1 In the lateral flow suppression method 1, the lateral flow suppression members 5 are arranged over the lower non-liquefied layer 21 and the liquefied layer 22 around the structure. In this case, the lateral flow suppressing member 5 is not disposed on the upper non-liquefied
And the edges are cut off. As described above, since the lateral flow suppressing member 5 is held by the lower non-liquefied layer 21 and disposed in the liquefied layer, the velocity of the lateral flow 3 is reduced, and the ground deformation of the upper non-liquefied layer is reduced. Can be suppressed. Moreover, since the side flow suppressing member 5 is cut off from the upper non-liquefied layer 23, it does not receive a force from the upper non-liquefied layer 23 or transmit a displacement.

The lateral flow suppressing member 5 is arranged upstream of the lateral flow around a structure such as a substructure as shown in FIG. With such an arrangement, the flow direction can be controlled upstream of the construct and the flow velocity can be reduced.

The lateral flow suppressing member 5 is arranged downstream of the lateral flow as shown in FIG. With this arrangement,
The flow is received downstream of the construct, and consequently the flow velocity can also be reduced upstream of the construct.

The lateral flow suppressing member 5 is disposed so as to surround the building 1. With this arrangement, the flow velocity can be reduced more in the entire periphery including the upstream side and the downstream side of the construct.

<D> Lateral flow suppressing method 2 Another lateral flow suppressing method is to move the lateral flow suppressing member 5 around the structure by using a liquefied layer 22 and an upper non-liquefied layer 23.
To be arranged over. In that case, the lateral flow suppressing member 5 is
The lower non-liquefied layer 2 which is not disposed on the lower non-liquefied layer 21
1 is cut off. As described above, since the lateral flow suppressing member 5 is held by the upper non-liquefied layer 23 and disposed in the liquefied layer, the lateral flow velocity is reduced, and the ground deformation of the upper non-liquefied layer is reduced. Can be suppressed.

With this arrangement, the lower non-liquefied layer 2
1, the construction of the lateral flow suppressing member 5 is simplified. As described above, in the method of controlling the moving speed of the liquefied layer 22 by using the rigidity of the upper non-liquefied layer 23, the number and the pitch of the restraining members are important design parameters. If this is not satisfied, the speed of the lateral flow will be excessive, and conversely, the ground deformation of the upper non-liquefied layer 23 will recur. It is necessary to properly calculate the design external force and install a restraining member by an appropriate method.

As shown in FIG. 4, a plurality of lateral flow suppressing members 5 are arranged in the upper non-liquefied layer and the liquefied layer around the structure in a C-shape. With this arrangement, it is possible to control the flow direction and reduce the external force applied to the substructure, thereby providing a lateral flow brake. Further, by placing the lateral flow suppressing member on the ground, the compaction effect and the strength of the composite ground can be expected to be increased, and as a result, the rigidity of the ground can be increased. The length of the lateral flow suppressing member and the pitch of the driving are determined in consideration of the flow force.

As shown in FIG. 5, the lateral flow suppressing members are arranged in a C-shape so that the upper non-liquefied layer and the liquefied layer are inclined. With this arrangement, the flow direction can be controlled to reduce the external force, resulting in a lateral flow brake. Further, the rigidity of the ground is increased. The length of the lateral flow suppressing member and the pitch of the driving are determined in consideration of the flow force.

As shown in FIG. 6, the lateral flow suppressing members are arranged in a C-shape so that the upper non-liquefied layer and the liquefied layer are inclined. With this arrangement, the braking ability can be expected more than in FIG. 5, but if the fluid pressure is excessive, the upper non-liquefied layer may be subjected to a force to cause ground deformation. Therefore, it is necessary to appropriately select the inclination angle and the pitch of the casting.

As shown in FIG. 7, the lateral flow suppressing members are densely poured into the upper non-liquefied layer and the liquefied layer, and are arranged three-dimensionally.

[0023]

According to the present invention, the following effects can be obtained. <A> Lateral flow can be suppressed by a simple suppressing member. <B> Ground deformation of the upper non-liquefied layer can be suppressed, and destruction of the building can be prevented.

[Brief description of the drawings]

FIG. 1 is an explanatory view of a force due to a lateral flow of a liquefied layer.

FIG. 2 is a layout view of a lateral flow suppressing member.

FIG. 3 is another layout view of the lateral flow suppressing member.

FIG. 4 is another layout view of the lateral flow suppressing member.

FIG. 5 is another layout view of the lateral flow suppressing member.

FIG. 6 is another layout view of the lateral flow suppressing member.

FIG. 7 is another layout view of the lateral flow suppressing member.

FIG. 8 is a reinforcement diagram of a conventional substructure.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Building 2 ... Ground 21 ... Lower non-liquefied layer 22 ... Liquefied layer 23 ... Upper non-liquefied layer 3 ... Lateral flow 4 ... Ground deformation 5 ... Lateral flow suppression member

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Ryo Sawada 2-8-3 Hikaricho, Kokubunji-shi, Tokyo Inside the Railway Technical Research Institute (72) Inventor Masashi Matsumoto 1-16-114 Shibuya, Shibuya-ku, Tokyo Tokyu Construction Co., Ltd. (72) Inventor Osamu Endo 1-16-14 Shibuya, Shibuya-ku, Tokyo Tokyu Construction Co., Ltd. (72) Masahiko Kimura 1-16-14, Shibuya, Shibuya-ku, Tokyo Tokyu Corporation (72) Inventor Nozomu Takakura 1-16-14 Shibuya, Shibuya-ku, Tokyo Tokyu Construction Co., Ltd. F-term (reference) 2D046 DA17

Claims (8)

[Claims] In a ground where a liquefied layer and an upper non-liquefied layer are expected to be formed on a lower non-liquefied layer, at least a liquefied layer and an upper non-liquefied layer are constructed. A lateral flow suppressing method comprising: disposing a lateral flow suppressing member in a peripheral lower non-liquefied layer and a liquefied layer; and not disposing the lateral flow restricting member in an upper non-liquefied layer. 2. In a ground where a liquefied layer and an upper non-liquefied layer are expected to be formed on a lower non-liquefied layer, a structure constructed at least over the liquefied layer and the upper non-liquefied layer. A lateral flow suppressing method, wherein a lateral flow suppressing member is disposed in a peripheral liquefied layer and an upper non-liquefied layer, and the lateral flow restricting member is not disposed in a lower non-liquefied layer. 3. The lateral flow suppressing method according to claim 1 or 2, wherein the lateral flow suppressing member is disposed upstream or downstream of the liquefied layer structure or around the structure. Characterized by the lateral flow suppression method. 4. The lateral flow suppressing method according to claim 1, wherein the structure is a foundation constructed over a lower non-liquefied layer, a liquefied layer and an upper non-liquefied layer. A lateral flow suppression method characterized by being a structure. 5. In a ground where a liquefied layer and an upper non-liquefied layer are expected to be formed on a lower non-liquefied layer, a structure constructed at least over the liquefied layer and the upper non-liquefied layer. A lateral flow suppressing member, which is disposed on a lower non-liquefied layer and a liquefied layer in the periphery and is not disposed on an upper non-liquefied layer. 6. In a ground where a liquefied layer and an upper non-liquefied layer are expected to be formed on a lower non-liquefied layer, a structure constructed at least over the liquefied layer and the upper non-liquefied layer. A lateral flow suppressing member, which is disposed in a peripheral liquefied layer and an upper non-liquefied layer but is not disposed in a lower non-liquefied layer. 7. The lateral flow suppressing member according to claim 5, wherein the lateral flow suppressing member is disposed upstream or downstream of the liquefied layer structure, or around the structure. A lateral flow suppressing member, characterized in that: 8. The lateral flow suppressing member according to any one of claims 5 to 7, wherein the structure is formed on a lower non-liquefied layer, a liquefied layer, and an upper non-liquefied layer. A lateral flow suppressing member, which is a structure.