JPH1143933A - Ground liquefaction preventing construction method and device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a ground liquefaction preventing construction method and device in the case where there is limit to a sheet pile length based on conditions at construction site in which a construction period can be shortened by adding a drain function to the sheet pile, in which cost is low, and in which construction is easy. SOLUTION: A method is composed of a process of connecting a tip part of a rod-like or cylindrical drain member 5 having water absorption performance or water permeability to an end surface protective member 3 installed on a sheet pile 1, a process of detachably connecting a tip part of the casing 2 to the end surface protective member 3, and detachably fixing the other side of the casing 2 to a detachably fixed casing lock member 4 to dispose the casing 2 to be roughly parallel to the sheet pile 1, a process of simultaneously placing the sheet pile 1 and the casing 2 in ground in the condition where the drain member 5 is installed, a process of placing the sheet pile 1, the casing 2, and the drain member 5 as they are vertically connected, and a process of pulling the casing lock member 4 and the casing 2 up after placing the sheet pile 1 to leave the sheet pile 1, the end surface protective member 3, and the drain member 5 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 and apparatus for preventing liquefaction of a ground which can prevent liquefaction occurring in a sandy ground during an earthquake and prevent liquefaction damage of various structures. is there.

[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 a casing, and removing the casing from the sandy ground to leave the drain pipe in the sandy ground.The drain pipe removes 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.

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

[0004]

The invention of the prior art 1 is as follows.
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.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and the construction time can be shortened by adding a drainage function to a sheet pile. It is intended to obtain a device. Another object of the present invention is to provide a method for preventing liquefaction of the ground and an apparatus therefor when the sheet pile length is limited due to the conditions of the construction site and the like.

[0006]

According to the present invention, there is provided a method for preventing liquefaction of a ground, comprising joining a tip end of a rod-shaped or cylindrical drain member having water absorbency or water permeability to an end face protection member attached to a sheet pile. A casing stopper member covering the entire drain member with a cylindrical casing, detachably connecting a tip end of the casing to the end face protection member, and detachably fixing the other side of the casing to the sheet pile. And placing the casing substantially parallel to the sheet pile, simultaneously placing the sheet pile and the casing in the ground with the drain member mounted, and connecting the sheet pile, the casing, and the drain member. Placing the sheet pile in the ground, and placing the sheet pile, and then leaving the sheet pile, end face protection member and drain member in the ground with the casing stopper member and the casing. Is a single those constituted by the pulling Ru process.

[0007] A liquefaction prevention device for ground according to the present invention is characterized in that a sheet pile driven into the ground, a substantially cylindrical end face protection member attached to the sheet pile, and a cylindrical shape, the tip of which is formed as described above. A casing detachably connected to the end face protection member,
A casing fixing member detachably fixed to the sheet pile, an upper portion of the casing being fixed, and having a water absorbing property or a water permeable property, and a lower end portion connected to the end face protecting member and inserted into the casing. It comprises a rod-shaped or cylindrical drain member, a connecting member for connecting the casing, and a joint pipe for connecting the drain member.

[0008]

1A and 1B show an embodiment of the present invention. FIG. 1A is a front view, FIG. 1B is a sectional view taken along line AA of FIG.
2A is an exploded perspective view of FIG. 1, and FIG. 2B is a perspective view of another example of the drain member. FIG. 3 is BB of FIG.
It is a CC expanded sectional view. In the drawing, reference numeral 1 denotes a steel sheet pile to which a plurality of steel sheet piles 11a and 11b are joined (hereinafter simply referred to as sheet pile), and reference numeral 2 denotes a plurality of steel members (hereinafter referred to as steel pipes) 21a and 21b having a circular cross section joined by a connection member 25. Sheet pile 1
A shorter casing.

An end face protection member 3 is fixed to the lower portion of the inner surface of the sheet pile 1 and the lower portion of the casing 2 is detachably connected thereto.
Reference numeral 5 denotes a casing stopper member to which the upper portion of the casing 2 is fixed and which is detachably attached to the upper portion of the inner surface of the sheet pile 1, and 5 is a drain member made of, for example, a polyethylene pressure-resistant tube. Reference numeral 6 denotes an end cap for reinforcing the lower end of the drain member 5, which comprises an inner cap 61 and an outer cap 65. Reference numeral 7 denotes a water-stop ring such as an O-ring, which is made of an elastic material such as rubber and is fitted to the end face protection member 3. 2 (a), the sheet pile 1, the casing 2, and the drain member 5 are shown one each, and the connecting member 25 is omitted.
Hereinafter, each of the above members will be described in detail.

FIGS. 1 to 3 show the case where the sheet pile 1 has a substantially U-shaped cross section. For example, the sheet pile 1 shown in FIG. 4 and the sheet pile shown in FIG. H-section steel 14,
(B) Steel pipe 15 as shown in the figure, steel sheet 16 with sheet pile as shown in the figure (c) may be used, and furthermore, concrete pile, ready-made reinforced concrete pile, prestressed concrete pile, steel pipe concrete pile, etc. (Hereinafter collectively referred to as “concrete piles”). Hereinafter, in the present specification, the above-described various sheet piles, steel pipes, concrete piles, and the like are collectively referred to as sheet piles.

[0011] Steel pipes 21a, 21 constituting the casing 2
The end of b is provided with an outer screw 22a or an inner screw 22b, or both. Also, as shown in FIG. 6 (a), internal threads 25a, 2 are provided at both ends of the joining member 25 for joining the steel pipes 21a, 21b constituting the casing 2.
6b, one inner screw 25b is deeply screwed in advance with an outer screw 22a provided at the lower end of one steel pipe 21b, as shown in FIG. 6 (b). 25 is rotated downward while rotating the other, the other inner screw 25a is screwed into the outer screw 22b of the other steel pipe 21a, and the two steel pipes 21a and 21b are integrally joined to form the casing 2. is there.

FIG. 7 shows another example of the connecting member 25. The connecting member 25 of this embodiment is a first connecting pipe in which external threads 26a and 26b are provided at both ends of a cylindrical steel material. 26
And internal screws 27 at both ends of a cylindrical steel material having a larger diameter.
a, 27b. Then, the internal thread 27a of the second intermediate pipe 27 is screwed into the external thread 26b of the first internal pipe 26 until the screw is removed, and is configured to be rotatable and extendable.

The steel pipes 21a, 21 constituting the casing 2
8a, when the outer thread 26 of the first intermediate pipe 26 of the joining member 25 is connected, as shown in FIGS.
a is screwed into the internal screw 22b of one steel pipe 21a, and then the second intermediate pipe 27 is moved upward while rotating, and as shown in FIG. 8 (c), the internal screw 27b is connected to the other steel pipe. The casing 2 is formed by screwing the outer screw 22a of the first pipe 21b and the inner screw 27a thereof with the outer screw 26b of the first relay pipe 26, and joining the two steel pipes 21a and 21b together.

FIG. 9 shows still another example of the connecting member 25. In this example, there is provided means for preventing the drain member 5 inserted into the casing 2 from dropping. That is, the notch 25c is provided at the lower end of the joining member 25 described with reference to FIG. 6, and the bottom of the joining member 25 has an inner thread 28a having the same inner diameter as the inside diameter of the joining member 25. Projection 28b engaged with notch 25c
Is provided with a stopper 28 provided with a.

The steel pipes 21a, 21 constituting the casing 2
In connecting the b, first, as shown in FIG. 10 (a), a stopper 28 is brought into contact with a lower end and a notch 25
c, the connecting member 25 having the protruding portion 28b engaged therewith is fitted into the lower end of one of the steel pipes 21b, and the inner screw 25a and the inner screw 28a of the stopper 28 are connected to the outer screw 2 of the steel pipe 21b.
2b.

Then, as shown in FIG. 10B, when the connecting member 25 is rotated and moved downward, the stopper 2
8, the inner screw 28a is separated from the outer screw 22a of the steel pipe 21b. Further, the connecting member 25 is lowered to screw the inner screw 25a thereof into the outer screw 22b of the other steel pipe 21a and to connect the other inner screw 25b to the outer steel pipe 21b as shown in FIG. Screw into the screw 22a,
Both steel pipes 21a and 21b are integrally joined. In addition, the steel pipe 21a,
Although the case where the casing 2 is formed by joining the joints 21b is shown, the structure of the joining member 25 and the joining procedure of the steel pipes 21a and 21b are not limited thereto, and can be changed as appropriate.

The end face protection member 3 has an outer diameter substantially equal to the inner diameter of the casing 2, a size that can be fitted inside the casing 2, and an inner diameter substantially equal to the outer diameter of the outer cap 65. Has a cylindrical main body 31 large enough to fit therein. The lower part of the main body 31 is obliquely cut off, its opening is closed by an elliptical plate, and a sharp part 32 is formed. Note that the sharp portion 32 may be omitted and the lower end may be formed flat. Reference numeral 33 denotes a holding belt, which is attached to a substantially middle portion of the main body 31 in the vertical direction by welding. The holding belt 33 plays the role of a stopper when the casing 2 is mounted, and its back surface is joined to the inner surface of the sheet pile 1 by welding. 34 is a bolt 71
The insertion hole.

FIG. 11 shows the casing stopper 4. 4
Reference numeral 1 denotes a casing stopper made of a cylindrical steel material whose inner diameter is large enough to fit the casing 2 therein. An inner screw 41a is provided at the upper end, and a backing plate 42 having a bolt insertion hole 43 is joined by welding. Have been. Reference numeral 44 denotes a cover for fixing the casing 2 to the casing stopper 41, and an outer screw 44 screwed into the inner screw 41a of the casing stopper 41.
a, and an outer screw 44b that is screwed into the inner screw 22b of the casing 2 is provided. In order to cope with the case where the length of the drain member 5 exceeds the length of the casing 2, the distal end of the drain member 5 is provided. There is provided an opening 45 from which is projected.

In order to attach the casing stopper 4 to the casing 2 as described above, as shown in FIG.
The casing stopper 41 is fitted to the upper end of the casing 2,
As shown in FIG. 12, the outer screw 44a of the lid 44 is screwed into the inner screw 41a of the casing stopper 41, and the outer screw 44b is screwed into the inner screw 22b of the casing 2, and these are integrally connected. At this time, when the drain member 5 is long, it protrudes outside from the opening 45 of the lid 44. FIG. 12C shows a state where the casing stopper member 4 is attached to the casing 2.

The drain member 5 is, for example, a water-absorbing or water-permeable rod-shaped or cylindrical-shaped member having a large number of holes 51 formed in a peripheral wall of a pressure-resistant tube made of a synthetic resin such as polyethylene. To prevent infiltration of earth and sand from 51,
For example, the filter may be covered with a filter made of synthetic fiber, synthetic resin, stainless steel or the like having water absorbency or water permeability and corrosion resistance. 52 is a bolt insertion hole provided in the lower part. In FIG. 14 and subsequent figures, the holes 51 are shown in a net shape. This drain member 5 is not limited to a synthetic resin,
It may be constituted by a metal tube having corrosion resistance such as stainless steel.

In the end cap 6, the inner cap 61 is formed of a cylindrical main body 62 having an outer diameter substantially equal to the inner diameter of the drain member 5 and having an upper part closed and a drain member 5 provided on the outer periphery of the lower end of the main body 62. Approximately equal to the outer diameter,
Alternatively, the flange 63 has a slightly smaller outer diameter, and the flange 63 plays a role of a stopper when fitted to the drain member 5. 64 is a bolt insertion hole. The outer cap 65 has a cylindrical shape with a bottom, and has an inner diameter substantially equal to the outer diameter of the drain member 5 and an outer diameter substantially equal to the inner diameter of the main body 31 of the end face protection member 3. 66 is a bolt insertion hole.

As shown in FIG. 2B, the joint pipe 55 connecting the drain member 5 is connected to the drain member 5.
A belt 57 is provided at a substantially central portion in the longitudinal direction of a cylindrical body 56 having an outer diameter substantially equal to the inner diameter of the cylindrical member 56. Both sides of the belt 57 are fitted into the drain members 51a and 51b, respectively, and the two are integrally joined. It was done. Note that a hole similar to the hole 51 of the drain member 5 may be provided in the cylindrical body 56 of the joint pipe 55.

Next, an example of an assembling procedure of the liquefaction preventing apparatus according to the first embodiment will be described. For ease of explanation, a case will be described in which the sheet pile 1, the casing 2, and the drain member 5 without joints are assembled. (1) As shown in FIG. 13, the main body 3 of the end face protection member 3
One or a plurality of water stop rings 7 are fitted into 1 and are positioned on the holding belt 33. In this case, it is desirable to use a water stop ring whose outer diameter is larger than the inner diameter of the casing 2 in order to increase the water blocking. Then, the end face holding member 3 is brought into contact with the lower portion of the inner surface of the sheet pile 1 and the holding belt 33 is moved to the sheet pile 1.
To join them together. Also, casing 2
Attach the casing stopper 4 to the upper end of the casing.

(2) As shown in FIG. 14, the inner cap 61 is fitted into the lower opening of the drain member 5,
The flange 63 is brought into contact with the lower end of the drain member 5.
Next, the outer cap 65 is fitted to the lower end of the drain member 5 to close the lower opening of the drain member 5, and the drain member 5 is closed by the inner and outer caps 61 and 65.
Reinforce the lower end of the. Note that only one of the inner cap 61 and the outer cap 65 may be attached to the lower opening of the drain member 5.

(3) Next, as shown in FIG. 15, the lower end of the drain member 5 to which the end cap 6 is attached is fitted into the main body 31 of the end face protection member 3, and bolts provided on each member are provided. The bolt 71 is inserted through the insertion holes 34, 66, 52, and 64, and is fixed with a nut to integrally connect the end face protection member 3 and the drain member 5. The main body 3 of the end face protection member 3
A step portion serving as a stopper for the drain member 5 may be provided on the inner wall of the first member. The above operation can be performed in a factory in advance.

(4) In this state, as shown in FIG. 16A, the casing 2 to which the drain stopper 4 is attached
Is advanced along the sheet pile 1, and the drain member 5 is inserted into the casing 2. When the casing 2 is further advanced, its lower end is fitted to the end face protection member 3 and abuts on the holding belt 33 via the water blocking ring 7 to stop the advance.
Next, the backing plate 42 of the casing stopper member 4 is fixed to the sheet pile 1 with bolts and nuts 46a and 46b through the bolt insertion holes 43. The state at this time is shown in FIG. Thereby, the assembly of the liquefaction prevention device is completed.

Although an example of the assembling procedure of the present embodiment has been described above, the present invention is not limited to this.
For example, the drain member 5 is inserted into the casing 2 joined to the casing stopper member 4 and is advanced along the sheet pile 1 together with the casing 2, the casing 2 is stopped at a certain position, and only the drain member 5 is advanced to drain. Member 5
Is connected to the end face protection member 3, and then the casing 2 is advanced to fit its tip to the cross-section protection member 3 to abut the holding belt 33, and the casing stopper member 4 is locked to the sheet pile 1, etc. Can be changed as appropriate.

Next, an example of the apparatus for preventing liquefaction of the ground according to the present invention and a method of erection on sandy ground will be described. (1) The end face protection member 3, the steel pipe 21a constituting the casing 2, the drain member 51a, and the casing stopper member 4 are set on the steel sheet pile 11a constituting the sheet pile 1 in the above-described manner.

(2) As shown in FIGS. 17A and 17B, the steel sheet pile 11a is driven into the ground by, for example, a hydraulic press-fitting device 8. At this time, if the sharp portion 32 is provided on the end face protection member 3, the penetration resistance at the time of driving can be reduced. Further, since the water stop ring 7 is interposed between the steel pipe 21a and the end face protection member 3, for example, even in the ground where the pressurized groundwater exists, water, earth and sand, etc., enter the steel pipe 21a. There is no danger that the construction can be performed.

(3) As shown in FIG. 17C, the casing stopper 4 is removed from the steel sheet pile 11a and the steel pipe 21a. (4) As shown in FIG. 17 (d), another steel sheet pile 11b for connection, on which the steel pipe 21b, the casing stopper member 4, and the drain member 51b are set, is lifted by a crane or the like, and the steel sheet pile 11b is built first. It is connected to the steel sheet pile 11a by welding 17. At this time, the connecting member 25 having the stopper 28 described in FIG. 9 may be attached to the lower end of the steel pipe 21b to prevent the drain member 51b from falling.

(5) Connect the connecting member 25 to the steel pipe 21a or 2
1b (with steel pipe 21 in advance)
a or 21b may be attached with the connecting member 25), and as shown in FIG.
5, the drain members 51a and 51b are joined. In this case, any one of the connection members 25 described with reference to FIG. 6, FIG. 7, or FIG. 9 or a connection member having another structure is selected as the connection member 25 according to the condition of the ground or the construction site.

(6) If the connecting member 25 is extended while being rotated and attached to either of the steel pipes 21a or 21b, as shown in FIG. 18A, the steel sheet piles 11a and 11b and the steel pipes 21a and 21b are provided. The connection of the drain members 51a and 51b is completed. (7) As shown in FIG. 18 (b), the steel sheet piles 11a, 11b after the joining, and hence the sheet pile 1, are driven into the ground by the hydraulic press-fitting device 8. If further connection is required, repeat the above procedure.

(8) After placing the uppermost steel sheet pile (eg, 11b) close to the surface of the ground, the casing stopper 4 is removed from the steel sheet pile 11b, and the sheet pile 1, the end face protection member 3, and the drain member 5 are placed in the ground. In the state where the casing 2 is left, the casing 2 is pulled out together with the casing stopper 4 by a crane or the like.
As a result, the drain member 5 is buried in the ground together with the sheet pile 1 as shown in FIG. Reference numeral 58 denotes a cap for closing the upper opening of the drain member 5.

By the way, the inside of the casing 2 is hollow, and at the moment when the casing 2 is pulled out, groundwater or earth and sand in the surrounding ground goes around the drain member 5 and the hole 5
There is a concern of blocking 1. In such a case, after driving the sheet pile 2 into the ground, a hose is inserted into the casing 2 and water is injected. Thereby, since the groundwater in the ground and the water in the casing 2 are kept in an equilibrium state, the closing phenomenon of the hole 51 of the drain member 5 is avoided.

When the casing 2 is pulled out, the lower end of the drain member 5 is reinforced by a double-structured end cap 6 composed of an inner cap 61 and an outer cap 65, and an end face protection member is provided by a bolt 71. There is no risk of damage because it is firmly connected to 3,
In addition, it does not go up with the casing 2.

In the present invention configured as described above,
Since the drain member 5 is provided near the sheet pile 1 and both are driven into the ground at the same time, construction is easy and the construction period can be shortened. Also, when driving the sheet pile 1,
Since the sheet pile 1, the casing 2, and the end face protection member 3 perform the earth blocking, closing, and compacting of the surrounding ground in parallel, the strength of the ground against liquefaction can be increased.

Further, since the sheet pile 1, the casing 2 and the drain member 5 are constructed so as to be connectable and their lengths can be adjusted, the length of the sheet pile 1 is limited, and the ground, the construction site and the like. A liquefaction prevention device for the ground can be installed according to the situation of the ground. In addition, the groundwater flows into the drain member 5 to dissipate the excess pore water pressure generated in the ground, and since the strong sheet pile 1 is provided in close proximity to this, it is possible to prevent liquefaction damage of various structures. Can be.

In each of the above embodiments, the case where the casing 2 and the end face protection member 3 are provided on the inner surface side of the sheet pile 1 and the drain member 5 is inserted into the casing 2 is shown. It may be provided on the outer surface side, or may be provided on both the inner surface side and the outer surface side. Further, as shown by broken lines in FIGS. 4 and 5, an appropriate number of drain members 5 can be provided at appropriate locations according to the type and shape of the sheet pile 1.

[0039]

The method for preventing liquefaction of the ground according to the present invention comprises:
A step of coupling the tip end of a rod-shaped or cylindrical drain member having water absorbency or water permeability to an end face protection member attached to a sheet pile, and covering the entire drain member with a cylindrical casing,
A step of detachably connecting the tip end of the casing to the end face protection member, fixing the other side of the casing to a casing stopper member detachably fixed to the sheet pile, and disposing the casing substantially parallel to the sheet pile; and a drain member. Simultaneously driving the sheet pile and casing into the ground with the
Connecting the sheet pile, the casing, and the drain member to the ground, and placing the sheet pile, and after placing the sheet pile, pulling the casing stop member and the casing with the sheet pile, the end face protection member, and the drain member remaining in the ground. The following effects can be obtained.

(1) The construction is easy, the construction period can be shortened, and the construction cost can be reduced. (2) Even when the sheet pile length is limited, it can be constructed. (3) In addition, when driving a sheet pile, the surrounding sheet is closed, closed, and compacted in parallel by the sheet pile and the end face protection member and the casing integrated with the sheet pile. Performance can be improved. (4) Furthermore, groundwater flows into the drain member to dissipate the excess pore water pressure generated in the ground, and a sheet pile is provided close to this, so that liquefaction damage of various structures can be prevented. .

The apparatus for preventing liquefaction of the ground according to the present invention comprises a sheet pile driven into the ground, a substantially cylindrical end face protection member attached to the sheet pile, and a cylindrical shape, the tip of which is protected by an end face. A casing detachably connected to the member, a casing fixing member detachably fixed to the sheet pile, and an upper portion of the casing fixed, and having water absorbency or water permeability, and a lower end portion coupled to the end face protection member. Since a rod-shaped or cylindrical drain member to be charged into the casing, a joining member for joining the casing, and a joint pipe for joining the drain member are provided, the effects of the above (1) to (4) are provided. Obtainable.

[Brief description of the drawings]

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

FIG. 2 is an exploded perspective view of FIG. 1 and an exploded perspective view of a drain member.

FIG. 3 is an enlarged sectional view taken along line BB and CC of FIG. 1;

FIG. 4 is a schematic view showing another example of the sheet pile of FIG. 1;

FIG. 5 is a schematic view showing another example of the sheet pile of FIG. 1;

FIG. 6 is a perspective view and an operation explanatory view of the joining member of FIG. 1;

FIG. 7 is a perspective view of another example of a connection member.

FIG. 8 is an operation explanatory view of the connection member of FIG. 7;

FIG. 9 is a perspective view of still another example of the joining member.

FIG. 10 is an operation explanatory view of the joining member of FIG. 9;

FIG. 11 is an exploded perspective view of a casing stopper, a casing, and a drain member of FIG. 1;

FIG. 12 is an operation explanatory view of the casing stopper of FIG. 1;

FIG. 13 is an explanatory view showing an assembling sequence of the present invention.

FIG. 14 is an explanatory view showing an assembling order of the present invention.

FIG. 15 is an explanatory view showing an assembling sequence of the present invention.

FIG. 16 is an explanatory view showing an assembling sequence of the present invention.

FIG. 17 is an explanatory view of a construction example of the present invention.

FIG. 18 is an explanatory diagram of a construction example of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 sheet pile 11a, 11b steel sheet pile 2 casing 21a, 21b steel pipe 25 connection member 3 end protection member 4 casing stop member 41 casing stop 42 backing plate 44 lid body 5, 51a, 51b drain member 55 joint pipe 6 end cap 7 water stop ring

 ──────────────────────────────────────────────────の Continued on the front page (72) Inventor Shigeru Nakagawa 1-2-1 Marunouchi, Chiyoda-ku, Tokyo Nihon Kokan Co., Ltd.

Claims (2)

[Claims] A step of coupling a tip end of a rod-shaped or cylindrical drain member having water absorbency or water permeability to an end face protection member attached to a sheet pile; and covering the entire drain member with a cylindrical casing;
A distal end portion of the casing is detachably connected to the end face protection member, and the other side of the casing is fixed to a casing stopper member detachably fixed to the sheet pile, and the casing is disposed substantially parallel to the sheet pile. A step of simultaneously driving the sheet pile and the casing into the ground with the drain member attached; a step of connecting the sheet pile, the casing and the drain member to the ground and driving the sheet pile; and A method for preventing liquefaction of the ground, comprising: a step of pulling up the casing stopper member and the casing while leaving the sheet pile, the end face protection member, and the drain member in the ground after installation. 2. A sheet pile driven into the ground, a substantially cylindrical end face protection member attached to the sheet pile, and a casing formed in a cylindrical shape and having a tip portion detachably connected to the end face protection member. A casing stopper member detachably fixed to the sheet pile, to which an upper portion of the casing is fixed; and a water absorbing or water permeable member, a lower end portion of which is connected to the end face protection member and inserted into the casing. An apparatus for preventing liquefaction of a ground, comprising: a rod-shaped or cylindrical drain member; a connecting member for connecting the casing; and a joint pipe for connecting the drain member.