JP2576346B2 - Removal and recovery of steel - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for removing and recovering steel using superabsorbent fibers.

[0002]

2. Description of the Related Art In the field of civil engineering and construction, steel materials such as steel sheet piles and H-section steels are used for construction of temporary structures such as retaining lands, and the temporary structures are removed immediately after the completion of this work. It is necessary to collect the steel, and the steel must be removed from the soil and removed and collected.

Conventionally, in order to easily pull out a steel material, a method of applying a material for reducing friction, such as grease or asphalt, to the surface of the steel material in advance, and driving the material into the soil,
At the time of drawing, a construction method of injecting bentonite muddy water, oil, etc. around the steel material is adopted.

However, in the former method, when a long time has elapsed after the driving, it is very difficult to pull out.
In the latter method, it is difficult to pull out the material unless it is injected uniformly.

[0005]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a method for removing and recovering a steel material, which can reliably and easily pull out the steel material.

[0006]

According to the present invention, a steel material having a sheet made of superabsorbent fibers adhered to the surface is driven into the soil, and after the role of the steel is completed, the sheet on the surface swells. A method for removing and recovering a steel material characterized in that the steel material is pulled out of the soil in a state in which the steel material is adhered to a sheet material made of super-absorbent fibers, and the sheet material on the surface absorbs water.・ Punching into the soil in a swollen state, after the role of the steel material is finished, pouring salt water or an alkaline aqueous solution into the sheet material to shrink the sheet material, and then pulling out the steel material from the soil The gist is a method for removing and recovering steel materials, which is characterized by the following.

The super-absorbent fibers used in the present invention include, for example, fibers having acrylate units and acrylamide units obtained by reacting an acrylonitrile polymer with an aqueous alkali metal hydroxide solution, polyvinyl acetate and acrylic. Absorbs clear water, such as a copolymer fiber of vinyl alcohol and acrylate obtained by hydrolyzing a copolymer with an acid ester, and a fiber obtained by graft-polymerizing acrylic acid on cellulose fiber, for example, several tens of times. It is a fiber having the property of swelling up to several thousand times. These superabsorbent fibers are prepared by copolymerizing a crosslinkable monomer such as ethylene glycol dimethacrylate, polyethylene glycol dimethacrylate, N, N'-methylenebisacrylamide, divinyl ether, or the like. A crosslinked structure may be introduced by crosslinking with an agent, radiation or the like. The superabsorbent fiber may be a single-layer fiber in which the entire fiber has superabsorbency or a multi-layer fiber in which only the outer layer of the fiber has superabsorbency. Commercially available superabsorbent fibers include, for example, Lanseal-F (registered trademark, manufactured by Toyobo Co., Ltd.).

[0008] These superabsorbent fibers absorb water and swell to a high degree due to their ionic structure, but have the property of shrinking with salt water or an aqueous alkaline solution. It utilizes the swelling / shrinking characteristics of a super absorbent fiber.

[0009] The superabsorbent fibers are adhered to the surface (both front and back) of a steel material as a sheet such as a woven fabric, a nonwoven fabric and a knitted fabric.

[0010] The sheet-like material can be made of only super-absorbent fibers, but other fibers (for example, various plant fibers,
(Synthetic fiber, etc.), and can also be produced by laminating a sheet made of super-absorbent fibers with a sheet made of other fibers or other water-permeable material. .

In the first invention of the present invention, first, a steel material having a sheet made of superabsorbent fibers adhered to the surface is driven into the soil. It is. If there is water in the soil, the superabsorbent fibers absorb the water and swell, become viscous, and reduce the friction between the steel material and the soil, so that the steel material can be easily pulled out.

[0012] When there is little or no water in the soil (sandy, dry soil), the water absorption of
Because of insufficient swelling, prior to pulling out the steel,
Water is injected from the steel joint to fully absorb the super absorbent fibers.
It must be swollen.

In the second invention of the present invention, a steel material having a sheet made of super-absorbent fibers adhered to a surface thereof is firstly prepared.
Water is absorbed and driven into the soil while the sheet on the surface is absorbing and swelling. After the end of the role of the steel material, salt water or an alkaline aqueous solution is injected into the sheet-like material. This water injection is preferably performed from a steel material joint. By this water injection, the sheet material shrinks, a gap is formed between the steel material and the soil, and it becomes easy to pull out the steel material from the soil.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described with reference to the drawings.

[0015] More than a dozen steel sheet piles were driven into moist soil to a depth of about 10 meters to secure them (Fig. 1). The super-absorbent fiber woven fabric was bonded to the steel sheet pile on both sides. One month after the use of the mountain retaining, the steel sheet pile was easily pulled out. The surface of the drawn sheet pile was covered with a highly swollen super absorbent fiber woven fabric.

[0016]

According to the present invention, the following effects can be obtained.

(1) A steel material can be easily pulled out by a simple operation of naturally absorbing water into a sheet made of super-absorbent fibers or pouring fresh water, salt water, or an alkaline aqueous solution.

(2) The super-absorbent fiber is lightweight and flexible, and can be easily processed into a sheet and adhered to the surface of a steel material, so that both the steps of driving and drawing the steel material are simple.

(3) Since the swelling and shrinkage of the sheet made of the superabsorbent fiber adhered to the steel material is reversible, the steel material removed and collected is attached to the sheet made of the superabsorbent fiber. It is economical because it can be used repeatedly as it is.

[Brief description of the drawings]

FIG. 1 is a plan view showing a state where a steel sheet pile is driven into the ground.

[Explanation of symbols]

1. Super-absorbent fiber woven fabric 2. Steel sheet pile 3. Joint part 4. Ground

Claims (2)

(57) [Claims] 1. A steel material having a sheet made of superabsorbent fibers adhered to the surface thereof is driven into the soil, and after the role of the steel is completed, the steel is soiled in a state where the sheet material on the surface is swollen. A method for removing and collecting steel materials, which is drawn out from inside. 2. A steel material having a sheet made of superabsorbent fibers adhered to the surface is poured into the soil while the sheet on the surface is absorbing and swelling, and after the role of the steel is completed, A method of removing and recovering a steel material, which comprises injecting salt water or an aqueous alkali solution into the sheet material to shrink the sheet material, and then extracting the steel material from the soil.