JPH0519612B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention is suitable for use as a parent pile because when the pile is driven into a cement layer, the rewetting lubricant layer provided in advance on the pile absorbs water and forms a lubricating surface. This invention relates to a pile with a lubricating layer for pulling out, which can be easily pulled out when the pile is to be retrieved after finishing.

Conventional technology A continuous row of holes are drilled in the ground using an earth auger.
Cement milk mixed with cement and bentonite, etc. is injected into this, and H-shaped steel piles are inserted into the key points of the hole to form a column retaining wall, and the ground soil surrounded by the retaining wall is removed in a box shape. , When a building basement etc. is constructed in the box-shaped pilot hole formed by this,
The earth retaining wall used when forming the pilot hole is no longer used. In this case, the H-shaped steel used as the main pile for the retaining wall is long and relatively expensive, so it should be recovered, but it is hard to pull out because it is firmly driven into the cement layer, so it is left as it is. Currently, attempts are being made to recover these piles by applying grease to the pile surface in advance and pulling the pile out with a special pile extraction device after use, but while the cement layer is solidifying, the grease layer is affected by earth pressure. As a result, it is difficult to retain the required amount of grease because it is removed from the pile surface, and it is not functionally sufficient as a lubricating surface, and it is still difficult to pull out, which has disadvantages such as requiring powerful special equipment. .

Problems to be Solved by the Invention The present invention provides a method for recovering piles driven into a cement layer by forming a good lubricating surface between the cement layer and the pile surface. The purpose of the present invention is to obtain a pile with a lubricating layer for pulling out, which can be pulled out by the force of a hoist, and which also makes it easy to set a lubricated surface on the pile surface and manage the pile with a lubricated surface in the air. do.

Means for Solving the Problems The present invention provides, as a means for solving the problems,
To provide a steel plate with a lubricant layer for drawing, which is coated with a rewetting lubricant layer made by kneading a water-absorbing polymer and a rewetting binder and drying and solidifying the mixture. The water-absorbing polymer is a highly water-absorbing polymer that is insoluble in water and absorbs hundreds of times its own weight in water to swell and form a hydrogel, such as acrylic acid copolymers (crosslinked polyacrylic acid, starch-based (polyacrylic acid copolymer, etc.), acrylic acid vinyl alcohol copolymer, crosslinked polyethylene oxide, crosslinked carboxymethylated cellulose sodium salt or calcium salt, etc.
The rewetting binder is a substance that becomes solid when dried, but becomes paste-like, mud-like, agar-like, etc. when water is absorbed, such as starch paste, polyvinyl alcohol-based paste, etc. It is desirable that it can be solidified into a film and also have some elasticity.

Effect The effect of the present invention is shown in FIG. When the pile 1 is put into the cement layer 8 made of cement milk, the water-absorbing polymer 5 and the rewetting binder 6 absorb the moisture in the cement layer 8. In this case, the water-absorbing polymer 5 swells into large and small spherical shapes due to water absorption, and the rewetting binder 6, if it is a sizing agent, softens into a paste-like state due to water absorption. The rewetting lubricant layer 2 then increases in thickness and eliminates the unsolidified cement layer 8 from the surface of the pile 1. After this, the cement layer 8 is solidified. It is not preferable that the thickness of the rewetting layer 2 when swollen is too large. This thickness is controlled by the combination of the water-absorbing polymer and the rewetting binder so that it does not rattle inside the pile hole in the solidified cement layer. In the swollen rewetting lubricant layer 2, the water-absorbing polymer 5 becomes large and small rolling balls, and the rewetting binder 6 gelatinizes and becomes slurry, acting as a lubricating oil and providing extremely smooth sliding between the cement layer and the pile surface. A lubricious edge cut surface is formed. Therefore, the pile can be easily pulled out by lifting the pile cap with the same crane used to insert the pile.

Embodiment 1 Embodiment 1 of the present invention will be explained with reference to FIGS. 1 to 3. 1 is an H-shaped steel pile with a total length of about 5 m, a cross section of 15 cm in flange length, 30 cm in web length, and 0.7 cm in thickness.
Weight is approximately 165Kg. 2 excludes the head of stake 1,
A rewetting lubricant layer applied to the pile surfaces of the flange 3 and web 4, with 100 parts of starch glue for corrugated board as the rewetting binder and Sumikagel (trade name) made of acrylic acid vinyl alcohol copolymer as the water absorbing polymer.
30 parts of SP-510 (manufactured by Sumitomo Chemical) was added with an appropriate amount of moisture and kneaded into a paste, and this paste was applied to the pile surface and dried and solidified to form a 100 μ thick layer. be. In Figure 3, 7 is a protective layer coated on the rewetting lubricant layer 2, which is a nonwoven fabric made of polyvinyl alcohol binder type and placed on the same layer while the rewetting lubricant layer 2 has adhesive strength. , which is mainly composed of polyester. Although this nonwoven fabric may be omitted, the mechanical strength of the rewetting lubricant layer 2 is maintained, and the water permeability to the rewetting lubricant layer 2 is controlled by the amount of polyvinyl alcohol and the density of the cloth.

When using the above-mentioned resistor, first, as shown in Fig. 4, continuous row holes 9 for the column retaining wall are bored in the ground using an earth auger, and then low alkaline cement, bentonite, excavated earth and sand are poured into the holes. Cement milk mixed with water, etc. was injected, and the pile, which was suspended by lowering the upper end of the pile, was inserted into a part of the continuous row holes 9 using the wire of the hoisting machine fed out from the leader mast of the earth auger. After the cement milk has solidified and the column walls of the cement layer 8 have been completed, that is, 10 days later, when the top end of the pile is secured with the wire mentioned above and the pile is pulled up, a slight traction force is added to the pile's own weight. I was able to pull out the stake. As shown in FIG. 5, the moisture in the cement layer 8 made of cement milk that has not yet solidified passes through the protective layer 7 and reaches the rewetting lubricant layer 2, and the water-absorbing polymer 5 absorbs water and swells, forming a rolling ball. , the rewetting binder 6 gelatinizes and pushes the cement milk away from the pile surface, and even after the cement layer 8 hardens, it maintains a water-absorbing state and maintains a good border lubricating layer between the cement layer 8 and the pile surface. It is estimated that It was thought that this lubricating layer would become thinner at the bottom of the pile due to earth pressure, but the lubricity was completely maintained when the pile was pulled out. One month later, due to continuous sunny weather, moisture did not enter the rewetting lubricant layer 2, the cement layer dried, and the moisture in the water absorbing polymer 5 and rewetting binder 6 escaped, reducing the entire structure to a skeleton shape.
The voids in the lubricant layer during swelling were maintained between the cement layer 8 and the pile surface. Therefore, when the top end of the pile was struck to destroy the skeletonized rewetting lubricant layer, the pile was easily pulled out.

Note that the rewetting lubricant layer 2 may be provided under the bookkeeping layer 7 and formed into a sheet, and may be adhered to the pile surface by applying an adhesive under the rewetting lubricant layer 2 or on the pile surface. When a silicone resin-based adhesive is used as the adhesive, it becomes easy to remove the deposits remaining on the pile surface after the pile is pulled out.

Embodiment 2 Embodiment 2 of the present invention will be explained with reference to FIG. 1
2 is an iron pipe, and 10 is a rewetting lubricating layer provided on the pipe surface. This rewetting lubricant layer uses polyvinyl alcohol-based rewetting glue as a rewetting binder.
100 parts, the product name Wonder Zeel (manufactured by Kao Soap), which is made of acrylic acid copolymer as a water-absorbing polymer.
Water was added to 20 parts to make a kneaded product, which was applied to the surface of the pipe 12 and dried and solidified to form a 100 μm thick layer. Reference numeral 11 denotes a coat layer which is pasted onto the rewetting layer 10 when it is solidified, and is made of kraft paper (50 g/m ² ).

This pipe 12 with a rewetting lubricant layer is set together with a formwork in a transverse state penetrating the earth retaining wall of the land being created, and when the pipe is pulled out after the cement has hardened, the pipe can be easily pulled out due to the lubricity of the rewettable lubricant layer 10. It was possible to drain the water and form a good drainage hole on the wall where the pipe remained.

Effects of the Invention In the present invention, the rewetting lubricant layer 1, which absorbs water and becomes a lubricant layer, is provided in a solidified state on the pile surface, so it does not peel off or drip during handling of the pile in the air. Also, after absorbing water, the water-absorbing polymer swells into a spherical shape and becomes a trochanter, and the rewetting binder gelatinizes and becomes slurry, acting as a lubricant, and between the cement layer and the pile surface, the thickness is maintained and the edges are cut into spheres. It forms a lubricated surface, which makes it easier to pull out the piles, allowing the piles to be used as recovered materials rather than abandoned materials, making construction costs economical.

[Brief explanation of the drawing]

FIG. 1 is a front view of Embodiment 1 of the present invention, FIG. 2 is an enlarged sectional view taken along the line A-A of the same as above, FIG. 3 is an enlarged sectional view of essential parts of Embodiment 1, and FIG. 4 is Embodiment 1 Fig. 5 is an enlarged sectional view of the main part showing the effect of Embodiment 1, and Fig. 6 is Embodiment 2.
FIG. In the figure, 1...Pile, 2...Rewetting lubricant layer, 5...
Water-absorbing polymer, 6...Rewetting binder.

Claims (1)

[Claims] 1. A pile with a lubricant layer for drawing, which is made by coating the pile surface with a rewetting lubricant layer made by kneading a water-absorbing polymer and a rewetting binder and drying and solidifying the mixture.