JP2000064265A - Lateral flow countermeasure structure for structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lateral flow countermeasure structure excellent in execution and economy to protect a structure from the lateral flow accompanied with the liquefaction of the ground. SOLUTION: A continuous wall 4 is constructed on an outer periphery of a foundation structure 2 for a pier located on the shore side of a revetment 1, and surrounds the foundation structure 2 in a circular manner. A steel member 3 having the water-discharging function in which the water discharging function is given to an inner surface side is used for the continuous wall 4. The liquefaction in the ground in the vicinity of the inner surface side of the continuous wall 4 is suppressed and degradation of the ground rigidity is prevented by dissipating the gap water pressure through a water discharge passage to be formed on the inner side of the steel member 3 having the water- discharging function when the excessive gap water pressure in a liquefied layer 11 is increased in an earthquake. The lateral flow FL attributable to the liquefaction of the ground in the earthquake is resisted by the continuous wall 4 and the ground rigidity of a liquefaction suppressing area 5a.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lateral flow countermeasure structure for protecting a structure from the lateral flow associated with the liquefaction of the ground, for example, the foundation of the structure constructed near the seawall. Is.

[0002]

2. Description of the Related Art Conventionally, as means for protecting a structure from lateral flow of the ground, a structure in which a streamline-shaped surrounding wall made of steel sheet pile or steel pipe sheet pile is provided on the outer periphery of the structure (Japanese Patent Laid-Open No. 9- 316865 gazette) or a surrounding wall of a sheet pile or a continuous underground wall on the outer periphery of the structure, and a drainage area for suppressing liquefaction by using a drain material or crushed stone on the outer periphery of the surrounding wall. Structure that protects underground structures by proof stress (see Japanese Patent Application Laid-Open No. 10-18309)
and so on.

[0003]

However, in the former case, in the case of constructing the surrounding wall with a material having low rigidity such as steel sheet pile, the interior of the surrounding wall should be improved to resist the lateral flow. It is uneconomical to secure the strength, and to secure the proof stress only by the surrounding wall without improving the ground, a material with high rigidity such as a steel pipe sheet pile is required.

On the other hand, the latter is constructed so that a pipe drain or the like is placed in the drainage area to suppress liquefaction in the drainage area. A considerable drainage capacity is required, and a huge construction site and cost are required. In addition, the pipe drain also has a problem of clogging when it is placed.

The present invention is intended to solve the above-mentioned problems in the prior art, and an object thereof is to provide a lateral flow countermeasure structure for a structure which is excellent in workability and economy.

[0006]

A structure for preventing lateral flow of a structure according to claim 1 of the present application is a structure for protecting a structure from lateral flow due to liquefaction of the ground, and an inner surface side And / or a steel material with a drainage function that has a large number of small holes or openings that allow water to enter in the area that contacts the ground on the outer surface side and has a drainage channel in the vertical direction. Is constructed to surround the structure to prevent liquefaction near the continuous wall and protect the structure from lateral flow.

As such a steel material having a drainage function, for example, a perforated sheet pile described in JP-A-2-225712 or the like can be used, but a drainage channel in the vertical direction is formed inside, It is not particularly limited as long as it has a large number of small holes or openings in the part in contact with the ground and can dissipate excess pore water pressure generated in the liquefied ground in the event of an earthquake using drainage channels. .

According to the present invention, the liquefaction of the ground near the continuous wall at the time of an earthquake is suppressed on the inner surface or the outer surface of the continuous wall, or the inner and outer surfaces, and the rigidity of the ground near the continuous wall is maintained. Therefore, compared to the case where the resistance is achieved only by the continuous wall, a great effect can be obtained as a lateral flow countermeasure.

Further, a steel material having a small rigidity can be used as the steel material forming the continuous wall, which is economical. According to a second aspect of the present invention, in the lateral flow countermeasure structure for a structure according to the first aspect, the surrounding shape of the continuous wall is circular, and a high resistance force due to the arch effect is obtained against the lateral flow, and particularly There is no need to consider the directionality.

A third aspect of the present invention is a lateral flow countermeasure structure for a structure according to the first or second aspect, wherein the lower end of the continuous wall is rooted to the non-liquefied layer. Liquefaction in the vicinity of the continuous wall is suppressed, and the lower end of the continuous wall reaches the inside of the non-liquefied layer, so that sufficient resistance to lateral flow can be secured.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows an embodiment of the present invention. As shown in FIG. 1 (a), the outer periphery of a pier foundation structure 2 located on the land side of the seawall 1. A continuous wall 4 is built in and surrounded by a circular shape.

The continuous wall 4 is made of the steel material 3 having a drainage function provided with a drainage function on the inner surface side, and the pore water pressure is increased against the increase of the excess pore water pressure of the liquefaction layer 11 which may be liquefied during an earthquake. Is diffused through the drainage channel formed on the inner surface side of the steel material 3 with a drainage function, whereby liquefaction in the ground near the inner surface side of the continuous wall 4 can be suppressed.
In the figure, the portion indicated by reference numeral 5a is a liquefaction prevention area on the inner surface side of the continuous wall.

As shown in FIG. 1 (b), the steel material 3 with drainage function is a non-liquefied layer 12 below the liquefied layer 11 on the outer ground of the foundation structure 2 consisting of footings 2a and foundation piles 2b.
It is deeply rooted, and has a structure that can secure sufficient resistance to lateral flow (in the direction of the arrow FL in the figure).

2 (a) to 2 (c) each show an example of the steel material 3 with a drainage function used in the present invention. FIG. 2 (a) is the same as the steel sheet pile with drainage function described in Japanese Patent Laid-Open No. 2-225712, in which a drainage member 3a made of grooved steel or the like is provided on one surface of a U-shaped steel sheet pile.
It forms a hollow drainage channel. The drainage member 3a is provided with a large number of small holes 3b in which a filter for preventing clogging is installed, and the pore water in the ground can be discharged into the drainage member 3a through the small holes 3b. There is.

FIG. 2 (b) shows a case where the main body of the steel material 3 with drainage function is a straight steel sheet pile having joints formed at both ends.
(c) is the case where the main body is a steel plate. FIG. 3 is a plan view showing, as another embodiment of the present invention, a state in which the substructure 2 is surrounded by a steel material 3 having a drainage function on both sides to have a circular shape.

In the case of the present embodiment, in addition to the effect described in FIG. 1, since the drainage function is also given to the outer surface side of the steel material 3, the outer surface side ground near the continuous wall 4 is also liquefied. A liquefaction prevention area 5b is formed to prevent the accompanying decrease in rigidity,
Lateral flow from the outer periphery of the continuous wall 4 is suppressed, and the substructure 2 can be protected more reliably.

[0017]

According to the present invention, liquefaction of the ground near the continuous wall at the time of an earthquake is suppressed on the inner surface or the outer surface side of the continuous wall, or the inner and outer surfaces, and the rigidity of the ground near the continuous wall is maintained. By doing so, a greater lateral flow countermeasure effect can be obtained as compared with the case of resistance only by the continuous wall.

In addition, as a steel material constituting the continuous wall, a steel sheet pile, a straight sheet pile or the like having a relatively small rigidity can be used, which is economical. Rapid grounding is possible because there is no need to improve the ground inside the continuous wall and there is no need to separately take extensive measures against liquefaction.

[Brief description of drawings]

FIG. 1 shows an embodiment of the present invention, in which (a) is a horizontal sectional view and (b) is a vertical sectional view.

2 (a) to (c) are perspective views each showing an example of a steel material with a drainage function used in the present invention.

FIG. 3 is a horizontal sectional view showing another embodiment of the present invention.

[Explanation of symbols]

1 ... Revetment, 2 ... Foundation structure, 2a ... Footing, 2b ...
Foundation pile, 3 ... Steel with drainage function, 3a ... Drainage member, 3
b ... small hole, 4 ... continuous wall, 5a ... liquefaction prevention area (inner surface side), 5b ... liquefaction prevention area (outer surface side), 11 ... liquefaction layer, 12 ... non-liquefaction layer, FL ... lateral flow

Claims (3)

[Claims] 1. A lateral flow countermeasure structure for protecting a structure from lateral flow due to liquefaction of ground, the inner surface side and / or
Or, a steel wall with a drainage function that has a number of small holes or openings that allow water to enter in the part that contacts the ground on the outer surface side, and has a drainage channel in the vertical direction, constructing a continuous wall on the outer peripheral ground of the structure A structure for preventing lateral flow of a structure, which prevents the liquefaction near the continuous wall by surrounding the structure and protects the structure from lateral flow. 2. The lateral flow countermeasure structure for a structure according to claim 1, wherein the surrounding shape of the continuous wall is circular. 3. The lateral flow countermeasure structure for a structure according to claim 1, wherein the lower end of the continuous wall is rooted to the non-liquefied layer.