JP2751651B2 - Liquefaction control pile - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is used for constructing a structure on the ground where there is a possibility of liquefaction or for reinforcing an existing structure against earthquakes, and suppresses liquefaction due to external vibrations such as earthquakes and waves. In addition, the present invention relates to a liquefaction-preventing pile for suppressing lateral flow and slip of the ground.

[0002]

2. Description of the Related Art As liquefaction suppression means currently in use, there are ground compaction methods and crushed stone drain methods which have been frequently used (Japanese Patent Laid-Open No. 56-100919, Japanese Utility Model Application Laid-Open No. 56-116).
434 gazette) and is applied to the ground where liquefaction is expected to occur.

[0003] Further, for the purpose of collecting and draining pore water in the ground and as a countermeasure against liquefaction, pressure-resistant resin pipes provided with a filter on the pipe peripheral surface have been conventionally used.

Further, in recent years, in order to drain excess pore water in the ground at the time of an earthquake or the like, a large number of holes are formed in a pile made of a steel pipe or the like, and there is water permeability for preventing intrusion of earth and sand into the holes. A hollow holed pile (see Japanese Patent Application Laid-Open No. 61-146910) and a porous concrete pile (see Japanese Patent Application Laid-Open No.
3711) has been developed.

In addition, there is also a steel sheet pile provided with a vertical pipe for drainage (see Japanese Patent Application Laid-Open No. 62-146315).

[0006]

The ground compaction method is used when the ground that may be liquefied alternates with the soft ground.
There are difficulties in terms of cost, and the crushed stone drain method impairs the drainage effect due to clogging and the like, and there is no guarantee of long-term function retention.

[0007] In addition, in the pile with a hollow hole disclosed in JP-A-61-146910 and the porous concrete pile disclosed in JP-A-61-83711, the load carrying capacity of a pile body as a structural body is reduced due to holes for drainage. Will be done.

[0008] A pressure-resistant resin pipe having small holes in the pipe body has little strength and rigidity, so that it is hardly expected to resist lateral flow or slippage of the ground due to an earthquake or the like.

[0009] In addition, the steel sheet pile of Japanese Patent Application Laid-Open No. Sho 62-146315, in which a vertical pipe for drainage is attached, only drains water from the lower end to the upper end of the vertical pipe. It does not have an extensive drainage function, and there is doubt about the drainage effect as a liquefaction countermeasure.

[0010] Furthermore, in any of the above-mentioned technologies which are expected to have a drainage effect, the load application direction (the load application direction is defined as the direction in which the external force acting on the pile main body in which a large load that is more prominent than other directions acts). ), It does not exhibit reasonable cross-sectional performance in terms of the function as a pile, making it an uneconomical product.

As a solution to the above-mentioned problems, the applicant has previously developed a liquefaction-preventing pile described in Japanese Patent Application Laid-Open No. 2-300412. In the same gazette, taking into account the load acting direction, the liquefaction-preventing pile having an opening ratio different from that in the direction perpendicular to the load acting direction with respect to the filter opening of the pile body, and a drainage having an opening and a filter. A liquefaction-preventing pile in which members are provided only in the load acting direction of the pile body is described.

An object of the present invention is to solve the above-mentioned problems in the prior art in consideration of the load acting direction, similarly to the liquefaction-preventing pile disclosed in JP-A-2-300412.

[0013]

A liquefaction-preventing pile to which the present invention is directed prevents a large number of openings and soil from entering in the axial direction of the pile, that is, in the thickness direction of the ground where liquefaction may occur. A plurality of drainage members provided with a filter for performing the operation are provided on the outer peripheral surface of the pile main body. In addition, the pile referred to here is not limited to the foundation pile, and includes a ground reinforcing material that resists lateral flow of the ground, circular slip, and the like.

The opening of the drainage member may have any shape such as a circular hole or a slit, but the area of the opening is a predetermined ratio to the surface area of the drainage member.

In the present invention, with regard to the attachment of the drainage member to the pile, a drainage member having high strength and rigidity is provided in the load acting direction. In addition, a drainage member having small strength and rigidity is used in a direction other than the direction in which the load acts. The method of changing the strength and rigidity of the drainage member is to use different materials in the load application direction and other directions, and to change the cross-sectional shape of the drainage member when using the same material. As the drainage member, a drainage member having a larger section modulus than the drainage member in the other direction is used.

The drainage member is attached to such an extent that the drainage member is not damaged during construction, or is attached so that the drainage member and the pile body are integrated.

The filter for preventing inflow of earth and sand is preferably a filter made of synthetic fiber or synthetic resin, for example, a warp knitted cloth made of nylon, polyethylene monofilament, polyester or the like, polypropylene, polyester fiber or the like. Nonwoven fabric or the like can be used. Further, a filter may be formed by combining synthetic fibers or synthetic resins, or combining or overlapping synthetic fibers and a synthetic resin. For example, on one or both sides of a synthetic fiber filter made of a thin warp knitted cloth or nonwoven fabric, the filter is thicker than the synthetic fiber filter, the synthetic resin filter having a larger mesh, or thicker than the synthetic fiber filter.
A filter reinforced by laminating a synthetic resin net (filter) having many small holes larger than the mesh can also be used.

The mesh spacing or gap of the warp knitted fabric or nonwoven fabric as a filter is determined by taking into account the particle size distribution of the soil on the ground (usually sand ground) to be subjected to liquefaction prevention or the like. It is better to set so as not to cause clogging. This mesh interval or gap is a ground that is likely to be liquefied, the grain size of the soil is particularly large, and it is possible to set it as large as about 1 to 3 mm in the ground that is relatively uniformly distributed, Such a ground is small, and it is preferable that the ground is set to be considerably smaller than about 1 to 3 mm in a general ground having a possibility of liquefaction.

It is preferable that the permeability of the filter in the countermeasure against liquefaction be equal to or higher than the permeability of the ground on which the liquefaction inhibiting pile is installed.

Needless to say, the filter is attached to the opening of the drainage member, and may be attached in any manner. When the liquefaction-preventing pile of the present invention is installed in the ground, the filter may be damaged. Anything that does not need to be used.

For the drainage member, its cross-sectional shape (for example, circular, rectangular, triangular, U-shaped, U-shaped, etc.)
The material (steel, aluminum, synthetic resin, and the like) is not particularly limited, and any material may be used as long as the liquefaction-preventing pile of the present invention is not damaged when installed in the ground.

The pile body is generally made of steel, but may be made of another metal, synthetic resin, concrete or other material as long as it has a necessary strength as a means for reinforcing the pile or the ground against earthquake. It may be something.

[0023]

[Function] Excessive pore water generated in the ground during an earthquake or the like penetrates through the opening of the drainage member, is drained through the gap between the pile body and the drainage member, and liquefaction of the ground around the pile is suppressed. .
At this time, intrusion of earth and sand is prevented by the filter at the opening.

The liquefaction-preventing pile is provided with a drainage member having high strength and rigidity on the side of the pile body where the load acts, to such an extent that the drainage member is not damaged at the time of construction. . In addition, by integrating the drainage member with the pile body, the bending rigidity of the pile is increased, and the horizontal resistance is further increased.

In such a liquefaction inhibiting pile, a sufficient drainage effect can be exerted by providing a drainage member having strength and rigidity smaller than those of the drainage members in the load application direction other than the load application direction.

The above-mentioned drainage effect (the effect of suppressing liquefaction of the ground around the pile) and the effect of improving the cross-sectional performance of the pile are combined.
The pile is expected to have horizontal resistance to external force in the event of an earthquake, and can restrain the ground in the vicinity of the pile, and can resist lateral flow, slip, etc. of the ground.

[0027]

Next, the illustrated embodiment will be described.

FIG. 1 shows a first embodiment of the present invention, in which a drainage member 2 formed of a channel steel is integrally attached to a liquefaction prevention pile A in a load acting direction by welding or the like, and the right angle thereof is provided. A drain member 3 formed in a U-shape with resin in the direction is attached. In the hole 4 as an opening, the above-mentioned filter 5 for preventing inflow of earth and sand is provided.

A large number of holes 4 having the same shape are provided so that the opening ratio is about 3 to 20% of the surface area of the drainage members 2 and 3.

FIG. 2 shows a second embodiment of the present invention, in which a drainage member 2a having a wide flange width is integrally provided in the load acting direction of the liquefaction prevention pile A, and the flange width is perpendicular to the flange width. A narrow drainage member 3a is provided.

FIG. 3 shows a third embodiment of the present invention, in which a drainage member 2b having a large flange thickness is integrally provided in the load application direction of the liquefaction inhibiting pile A, and the flange thickness is perpendicular to the direction. A small drainage member 3b is provided.

FIG. 4 shows a fourth embodiment of the present invention, in which a drainage member 2c having a long web length is integrally provided in the load acting direction of the liquefaction inhibiting pile A, and the web length is set in a direction perpendicular to the direction. A short drainage member 3c is provided.

FIG. 5 shows a fifth embodiment of the present invention. The drainage member 2d has a wide flange width, a large flange thickness, and a long web length in the load acting direction of the liquefaction inhibiting pile A.
The flange width is narrow in the perpendicular direction,
This is provided with a drainage member 3d having a small flange thickness and a short web length.

In the embodiment shown in FIGS. 1 to 5, the rigidity of the liquefaction-preventing pile A with respect to the load acting direction is larger than that of the conventional liquefaction-preventing pile having a hole in the pile body. In addition, FIG.
In the embodiment of FIG. 5, it is conceivable to attach a drainage member formed of a material having a large Young's modulus in the load acting direction and a drainage member formed of a material having a small Young's modulus in a direction perpendicular thereto.

FIG. 6 shows an example in which the liquefaction inhibiting pile A of the present invention is applied to an embankment 11 as a specific application example.

In this example, the liquefaction-preventing pile A is installed near the bottom of the embankment 11 and penetrates the ground 13 where there is a possibility of liquefaction around the embankment and on the lower surface to reach the good ground 14. In the figure, reference numeral 12 denotes a crushed stone mat for drainage installed at the head of the liquefaction prevention pile A.

In the above structure, the external force acting in the direction perpendicular to the extending direction of the embankment 11 is predominant due to the difference in the effective stress on both sides of the liquefaction prevention pile A, and a drainage member having high strength or rigidity is provided in that direction. Thereby, the horizontal resistance of the liquefaction suppression pile A as a pile can be increased.

The liquefaction inhibiting pile of the present invention can be installed on the slope of the embankment 11 in the example of FIG.

In addition to the above, the liquefaction-preventing pile of the present invention is applied to a liquefaction-preventing pile which receives a load in a specific direction due to factors such as a structure or topography. The resistance can be increased efficiently.

[0040]

[Effects of the Invention] By attaching a drainage member having high strength and rigidity to the liquefaction-preventing pile on the load acting direction side of the pile main body, the strength of the ground when the horizontal resistance of the pile is exerted can be sufficiently utilized.

By providing the drainage member integrally with the pile main body, the bending rigidity of the pile is increased, and the horizontal resistance is also increased.

By providing a drainage member having a small strength and rigidity in addition to the load acting direction, a sufficient drainage effect as a liquefaction prevention pile can be exhibited.

[Brief description of the drawings]

FIG. 1 shows a first embodiment of a liquefaction inhibiting pile according to the present invention, wherein (a) is a horizontal sectional view and (b) is an elevation view.

FIGS. 2A and 2B show a second embodiment of the liquefaction inhibiting pile of the present invention, wherein FIG. 2A is a horizontal sectional view and FIG. 2B is an elevation view.

FIG. 3 shows a third embodiment of the liquefaction-preventing pile according to the present invention, wherein (a) is a horizontal sectional view and (b) is an elevation view.

FIG. 4 shows a fourth embodiment of the liquefaction-inhibiting pile of the present invention, wherein (a) is a horizontal sectional view and (b) is an elevation view.

5A and 5B show a fifth embodiment of the liquefaction inhibiting pile of the present invention, wherein FIG. 5A is a horizontal sectional view and FIG. 5B is an elevation view.

FIG. 6 is a vertical sectional view showing a construction example in a case where the liquefaction suppressing pile of the present invention is applied to liquefaction suppression and prevention of ground slip.

[Explanation of symbols]

A: Liquefaction inhibiting pile, 1: Pile body, 2: Drainage member with high strength and rigidity, 3: Drainage member with low strength and rigidity, 4
... holes, 5 ... filters, 11 ... embankments, 12 ... crushed stone mats for drainage, 13 ... ground that may be liquefied, 14 ... good ground

 ──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Yukio Saimura 1-3-1 Otemachi, Chiyoda-ku, Tokyo Sumitomo Metal Industries, Ltd. (56) References JP-A-2-300412 (JP, A) JP-A-2-225710 (JP, A) JP-A-2-96018 (JP, A)

Claims (3)

(57) [Claims] 1. A liquefaction-preventing pile comprising a plurality of drainage members having a large number of openings and a filter for preventing intrusion of earth and sand along a longitudinal direction of an outer peripheral surface of a pile body. A liquefaction-inhibiting pile, wherein a drainage member having greater rigidity than a drainage member in another direction in a load acting direction in a horizontal section of a pile body is provided. 2. The liquefaction-preventing pile according to claim 1, wherein a material having a higher elastic modulus than a material of a drainage member provided in another direction is used as a material of the drainage member provided in the load acting direction. 3. The liquefaction-preventing pile according to claim 1, wherein the drainage member provided in the load acting direction is a drainage member having a larger sectional modulus than the drainage member provided in another direction.