JPH0995932A - Liquefaction preventing construction method for ground - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a ground liquefaction preventing construction method which can shorten execution time by giving drainage function to a sheet pile, and moreover is inexpensive and easy in execution. SOLUTION: The tip part of a casing 2 which is formed to be cylindrical or about U-shaped in section is connected to an end protecting member 3 attached to a sheet pile, and the casing 2 is held about parallel to the sheet pile 1 by an attaching member 4 and unified. A bar-shaped or cylindrical drain member having water absorbing ability or permeability is inserted in a cylindrical part formed inside the casing 2 or between the sheet pile 1 and the casing 2. The sheet pile 1 is drivenly installed in the ground in a state where the drain member is inserted. After the sheet pile 1 is drivenly installed, the casing 2 is pulled up in a state where the sheet pile 1, the end protecting member 3 and the drain member are left in the ground.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for preventing liquefaction of ground, which can prevent liquefaction occurring in sandy ground during an earthquake and prevent damage to liquefaction of various structures.

[0002]

2. Description of the Related Art Various measures have been proposed to prevent liquefaction of sandy ground.
There is an invention described in Japanese Patent Publication No. 0 (hereinafter referred to as Prior Art 1). The present invention relates to a process of driving a casing into a sandy ground by using vibration while compacting the sandy ground, and a method of permeating a pipe having a pressure resistance against a predetermined pressure of the ground and having a hole for water permeation formed in a peripheral wall. Inserting a drain pipe covered with a porous filter into the casing, and withdrawing the casing from the sandy ground to leave the drain pipe in the sandy ground, and draining excess pore water pressure in the sandy ground. The present invention relates to a method for preventing liquefaction of sandy ground which is reduced by using the method.

The invention disclosed in Japanese Patent Application Laid-Open No. 2-225712 (hereinafter referred to as "prior art 2") has a large number of openings in a predetermined section along the longitudinal direction of the sheet pile body and the ground from the openings. One or a plurality of drainage members provided with a filter for preventing intrusion are provided on at least one surface of the sheet pile body.

[0004]

DISCLOSURE OF THE INVENTION The invention of the prior art 1 is
Since the drain pipe and sheet pile must be constructed separately, it is difficult to cope if there are restrictions on the construction time,
There is a problem in workability. Further, the invention of the prior art 2 is capable of shortening the construction time because the steel sheet pile to which the drainage member is previously attached is cast, but the drainage member can be reduced more than the effect of shortening the construction time. Processing and mounting on steel sheet piles are costly and have problems in terms of economy.

The present invention has been made to solve the above-mentioned problems. By adding a drainage function to the sheet pile, the construction time can be shortened, and a method for preventing liquefaction of the ground which is inexpensive and easy to construct is obtained. This is the purpose.

[0006]

[Means for Solving the Problems]

(1) In the ground liquefaction prevention method according to the present invention, a tip portion of a casing formed in a tubular shape or a substantially U-shaped cross section is connected to an end face protection member attached to a sheet pile, and the casing is attached by the attachment member. A step of holding the sheet pile substantially parallel to the sheet pile and integrating it, and inserting a rod-shaped or tubular drain member having water absorbability or water permeability into a tubular portion formed in the casing or between the sheet pile and the casing. Step, driving the sheet pile into the ground with the drain member inserted, and after pulling the sheet pile, pull up the casing with the sheet pile, the end face protection member and the drain member left in the ground It consists of a process.

(2) Further, in the ground liquefaction prevention construction method of (1) above, after the sheet pile integrated with the end face protection member and the casing is driven into the ground, it is placed in the casing or between the sheet pile and the casing. The drain member is inserted into the tubular portion formed on the.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows an embodiment of the present invention. (A) is a front view, (b) is a sectional view taken along line AA,
FIG. 2 is an exploded perspective view of FIG. FIG. 3 shows FIG.
(A) BB enlarged sectional view, CC enlarged sectional view and D-
It is a D expanded sectional view. In the figure, 1 is a steel sheet pile, 2 is a casing made of square steel pipes 21 and shorter than the steel sheet pile 1, 3 is an end face protection member that is fixed to the lower inner surface of the steel sheet pile 1, and the lower portion of the casing 2 is connected, 4, 4 Mounting members fixed to the upper inner surface of the steel sheet pile 1 and holding the casing 2, 5, 5
Is a drain member made of, for example, a perforated pressure resistant pipe made of polyethylene. Hereinafter, each of the above members will be described in detail.

The steel sheet pile 1 is shown in FIGS. 1 to 3 in the case where the steel sheet pile 1 having a substantially U-shaped cross section is used. For example, the H section steel 11 shown in FIG. 6 and the steel sheet pile shown in FIG. H-section steel with sheet pile 1
2, a steel pipe 13 as shown in FIG. 2 (b), a steel pipe 14 with a sheet pile as shown in FIG. 2 (c), etc. may be used.
Concrete piles, ready-made reinforced concrete piles, prestressed concrete piles, steel pipe concrete piles, and the like (hereinafter collectively referred to as “concrete piles”) may be used.
Hereinafter, in the present specification, the above-described various sheet piles, steel pipes, piles, and the like are collectively referred to as sheet piles.

The casing 2 is shown in the drawing using a steel pipe 21 having a rectangular cross section, but a steel plate may be welded to form a rectangular cross section or a substantially U-shaped or V-shaped cross section. Alternatively, a member having an appropriate cross-sectional shape, such as a channel steel 22 having a substantially U-shaped cross-section as shown in FIG. 4, a shape steel having a substantially V-shaped cross-section, or a steel pipe 23 having a circular cross-section as shown in FIG. 5, may be used. Can be used.

As shown in FIG. 2 and FIGS. 3 to 5C, the end face protection member 3 has an inner shape substantially equal to the outer shape of the casing 2, and the outer surface of the casing 2 can be fitted inward. In addition, the outer surface fitting portion 31 having a substantially U-shape in a plan view and having an upper opening is formed (outer bag type), and the sharp portion 32 is formed in the lower portion by a triangular shape or a triangular pyramid shape like a bow of a ship. Has been done.

As shown in FIG. 8, the end face protecting member 3 has an outer shape substantially equal to the inner shape of the casing 2,
The inner surface of the casing 2 has an inner surface fitting portion 33 having a substantially U-shaped cross-section with an opening so that the inner surface can be fitted to the outer side (inner bag type). Welding a rod or the like to provide the contact portions 34, 34, or further, welding an L-shaped holding plate 35 to the front surface to form the fitting portion 36 of the casing 2 between the front wall and the like. It may be formed so that the lower end of the casing 2 can be fitted to the outside thereof.

Further, when the end face protection member 3 is formed in a cylindrical shape, a smooth outer surface fitting portion 31 or inner surface fitting portion 33 may be provided as described above, or the outer surface fitting portion 31.
A female screw may be provided on the inner periphery of the casing 2, or a screw may be provided on the outer periphery of the inner surface fitting portion 33, and a male screw or a female screw corresponding thereto may be provided on the lower portion of the casing 2 for screw connection. In the above description, the case where the lower portion of the end face protection member 3 is formed to be sharp is shown, but it may be formed to be flat.

In such an end face protecting member 3, the U-shaped opening is brought into contact with the lower inner surface of the sheet pile 1 and fixed by welding.
Alternatively, it is detachably attached with bolts and nuts. In the case of the cylindrical end face protection member 3, it is fixed to the sheet pile 1 by welding directly or through the mounting arm, or detachably attached to the sheet pile 1 with bolts and nuts.

As shown in FIGS. 2 to 4, the mounting members 4 and 4 are substantially L-shaped metal fittings, and one of the pieces 41 and 41.
The bolt 6 inserted into the screw insertion hole 43 provided in the insert is inserted into the screw insertion hole 11 provided in the sheet pile 1, the casing 2 is sandwiched between the other pieces 42, 42, and the nut 61 is detachably fixed, Hold the casing 2 firmly. In this case, one piece 41, 41 of the mounting members 4, 4 may be welded and fixed to the sheet pile 1, or the other piece 42, 42 and the casing 2 may be fixed with bolts and nuts. . Further, if the screw insertion holes 43, 43 provided in the one piece 41, 41 are elongated holes, the casing 2 can be easily clamped.

When the steel pipe 23 is used for the casing 2, as shown in FIG. 5, the mounting member 4 is formed into a substantially Ω shape, and the outer periphery of the casing 2 is surrounded by the holding members 45, 45. The arms 44, 44 may be detachably fixed to the sheet pile 1 with the bolt 6 and the nut 61. The mounting member 4 is not limited to the structure described above, and can be appropriately changed according to the shape of the casing 2.

The drain member 5 is, for example, a water-absorbing or water-permeable rod-shaped or cylindrical member having a large number of holes 51 formed in the peripheral wall of a pressure resistant tube made of synthetic resin such as polyethylene. In order to prevent the infiltration of earth and sand from 51,
For example, as shown in FIG. 8, the filter 52 may be covered with a filter 52 made of synthetic fiber, synthetic resin, stainless steel, or the like having water absorption or water permeability and corrosion resistance. The drain member 5 is not limited to the synthetic resin, and may be a metal tube having corrosion resistance such as stainless steel.

In the present invention composed of the above-mentioned members, as shown in FIG. 9A, the end face protection member 3 is attached to the lower inner surface of the sheet pile 1 by welding, screwing or the like, and the casing 2 is attached to the sheet pile 1. It is arranged along the inner surface of. And FIG.
As shown in (b), the lower end portion of the casing 2 is fitted into the outer surface fitting portion 31 of the end surface protection member 3 until it comes into contact with the inner wall of the sharp portion 32. Then, place the upper part of the casing 2 on the sheet pile 1.
It is fixed substantially parallel to the sheet pile 1 by the attachment members 4 and 4 attached to the casing 2, and finally, as shown in FIG.
If the drain member 5 is inserted inside, each member can be integrated.

Further, as shown in FIG. 4, when a grooved steel 22 or a V-shaped cross-section steel is used as the casing 2, the opening side is brought into contact with the sheet pile 1 and the lower part thereof is an end face protection member. 3 and the upper part is fixed by the mounting member 4, and the drain members 5 and 5 may be inserted into the tubular portion formed between the sheet pile 1 and the casing 2. Further, in the case of the end surface protection member 3 having the inner surface fitting portion 33, the casing 2 may be fitted until the lower end portion of the end surface comes into contact with the contact portion 34, and a screw is provided on the end surface protection member 3 and the lower end portion of the casing 2. In this case, these screws may be screwed together to connect the two.

When integrating the members,
The end face protection member 3 is attached to the sheet pile 1, and the casing 2 in which the drain member 5 is previously attached is attached thereto, or the drain member 5 is placed in the casing 2 in which the end face protection member 3 is attached, and this is attached to the sheet pile 1. The end face protection member 3 may be attached to the casing 2 in which the drain member 5 is inserted in advance, and the end face protection member 3 may be attached to the sheet pile 1.

As shown in FIG. 10A, the sheet pile 1, the casing 2, the end face protection member 3, the attachment members 4, 4 and the drain member 5 which are integrated in this way are driven into the ground. By doing so, it is integrally buried in the ground.
Then, when the driving is finished, as shown in FIG. 10B, the mounting members 4 and 4 are removed or loosened, and the sheet pile 1, the end face protection member 3 and the drain member 5 are left in the ground. Pull out the casing 2. In this case, the casing 2 may be detached from the sheet pile 1, or the casing 2 may be pulled up partway and held at that position. Alternatively, the sheet pile 1 may be driven with the casing 2 attached, the drain member 5 may be inserted into the casing 2 after the driving is finished, and then the casing 2 may be pulled out.

By the way, when the casing 2 is pulled out, there is a risk that the drain members 5 and 5 will also go up (up). Therefore, in the present invention, the following supply prevention measures are taken. That is, as shown in FIG. 8, the inner surface fitting portion 33 is formed on the end surface protection member 3, and the cap 37 having the hook 38 is attached to the upper end portion thereof. And
Synthetic fiber filter 5 covering the drain members 5 and 5
The lower ends of 2, 52 are wound around the hook 38 to be fixed. As a result, even if the casing 2 is pulled out, the drain members 5 and 5 are held by the end face protection member 3 and do not come up.

A cap with a hook may be attached to the lower end portions of the drain members 5 and 5, and the hook may be engaged with a stopper provided on the end face protecting member 3, or the casing 2 may be, for example, as shown in FIG. As shown in FIG. 4, in the case of the open cross section made of the channel steel 22, a holding member projecting to the drain member 5, 5 side is attached at a position corresponding to the top of the drain member 5, 5 of the sheet pile 1. , 5 may be blocked.

Further, when the lower end portions of the drain members 5 and 5 are closed with a cap or the like, for example, a weight made of steel bar having a diameter smaller than the inner diameter of the drain members 5 and 5 and having a wire or the like attached to the upper portion thereof is used as the drain member. Insert the inside of the casing 5 and 5 to set the tip to the bottom, and act as a reaction force when pulling out the casing 2 to prevent it from rising, and pull up the weight when the casing 2 is pulled out. Good. Also,
When the lower ends of the drain members 5 and 5 are not closed, a plate material larger than the outer shape of the drain members 5 and 5 is attached to the upper portion of the weight directly or via a wire, and the weight is inserted into the drain members 5 and 5. Then, an appropriate means such as placing the plate member on the top of the plate member and acting it as a reaction force can be used.

In the apparatus of the present invention constructed as described above, the drain member 5 is provided close to the sheet pile 1 and both of them are simultaneously driven into the ground, so that the construction is easy and the construction period is shortened. You can In addition, when the sheet pile 1 is driven, the sheet pile 1, the casing 2 and the end face protection member 3 simultaneously perform soil stopping, closing and compaction of the surrounding ground, so that the strength against liquefaction of the ground can be increased. it can. In addition, groundwater flows into the drain member 5 to dissipate excess pore water pressure generated in the ground, and a strong sheet pile 1 is provided close to it to prevent liquefaction damage of various structures. You can

In the above embodiment, the casing 2, the end face protection member 3 and the mounting member 4 are provided on the inner surface side of the sheet pile 1,
Although the case where one or two drain members 5 are inserted into the casing 2 is shown, these respective members may be provided on the outer surface side of the sheet pile 1, or may be provided on both the inner surface side and the outer surface side. . Further, the number of drain members 5 can be appropriately increased or decreased. Further, as shown by the broken lines in FIGS. 6 and 7,
Depending on the type and shape of the sheet pile 1, an appropriate number of drain members 5 can be provided at appropriate locations.

[0027]

The method for preventing liquefaction of the ground according to the present invention is
A step of connecting a tip end portion of a casing formed in a tubular shape or a substantially U-shaped section to an end face protection member attached to the sheet pile and holding the casing substantially parallel to the sheet pile by the attachment member to integrate the casing; The step of charging a water-absorbing or water-permeable rod-shaped or cylindrical drain member into the cylindrical portion formed in the casing or between the sheet pile and the casing, and the sheet pile in the ground with the drain member loaded. Since it is configured by a step of driving the sheet pile, and a step of driving the sheet pile, and then pulling up the casing with the sheet pile, the end face protection member and the drain member left in the ground, the construction is inexpensive and easy, The construction period can be shortened.

In addition, when the sheet pile is driven, the sheet pile, the casing integrated with the sheet pile, and the end face protection member simultaneously perform earth stopping, closing, and compaction of the surrounding ground. It is possible to improve the sex. Furthermore, since groundwater is caused to flow into the drain member to dissipate excess pore water pressure generated in the ground and a sheet pile is provided in the vicinity thereof, liquefaction damage to various structures can be prevented.

[Brief description of drawings]

FIG. 1 is a front view of an embodiment of the present invention and a sectional view taken along line AA of FIG.

FIG. 2 is an exploded perspective view of FIG.

3 is an enlarged cross-sectional view of BB, CC, DD of FIG.

FIG. 4 is an enlarged sectional view corresponding to FIG. 3 of another example of the present invention.

FIG. 5 is an enlarged cross-sectional view of another example of the present invention, which corresponds to FIG.

FIG. 6 is a schematic view of another example of the sheet pile of FIG. 1;

FIG. 7 is a schematic view of another example of the sheet pile of FIG.

FIG. 8 is a front view and a side view of another example of the end face protection member and the drain member of FIG.

FIG. 9 is a process explanatory view of an example of a construction method according to the present invention.

FIG. 10 is a process explanatory view of an example of a construction method according to the present invention.

[Explanation of symbols]

 1 Sheet Pile 2 Casing 3 End Face Protecting Member 31 Outer Surface Fitting Part 33 Inner Surface Fitting Part 34 Abutment Part 35 Holding Plate 4 Mounting Member 5 Drain Member 51 Hole 52 Filter

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Shigeru Nakagawa 1-2-1, Marunouchi, Chiyoda-ku, Tokyo Nihon Steel Pipe Co., Ltd. (72) 1-2-2-1 Marunouchi, Chiyoda-ku, Tokyo Nippon Steel Tube Co., Ltd. (72) Inventor Takayoshi Morikawa 2-3-2 Uchisaiwaicho, Chiyoda-ku, Tokyo Kawasaki Steel Works (72) Inventor Yugo Oka 2-3-2 Uchisaiwai-cho, Chiyoda-ku, Tokyo Saki Steel Co., Ltd.

Claims (2)

[Claims] 1. A casing or a casing formed in a U shape in cross section is connected to an end face protection member attached to a sheet pile, and the attachment member holds the casing substantially parallel to the sheet pile and is integrated. And a step of loading a rod-shaped or tubular drain member having water absorbability or water permeability into a tubular portion formed in the casing or between the sheet pile and the casing, and the drain member is attached. Constituted by a step of driving the sheet pile into the ground in an inserted state, and a step of driving the sheet pile, and then pulling up the casing with the sheet pile, the end face protection member and the drain member left in the ground. The liquefaction prevention method of the ground characterized by the above. 2. The sheet pile according to claim 1, wherein the sheet pile integrated with the end face protection member and the casing is driven into the ground,
A method for preventing the liquid of the ground, wherein a drain member is inserted into a tubular portion formed inside the casing or between the sheet pile and the casing.