JP2008303628A - Friction reducing material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To minimizes the settling of a buried object itself such as a steel sheet pile, prevents the deterioration of a shielding effect, avoids an adverse effect on the circumferential ground, and contributes to improved workability and cost efficiency. <P>SOLUTION: The friction reducing material is formed on the surface of the buried object such as the steel sheet pile by being applied or stuck to the buried object that is inserted to some midpoint of a soft stratum. The friction reducing material is preferably formed of a composition containing a water-absorbing resin and an alkaline water-soluble resin as essential ingredients. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a friction reducing material for a buried portion buried in the ground, and more specifically, a buried object that does not reach the support layer in the ground (floating steel sheet pile method or a combination of floating steel sheet pile and low steel sheet pile) It is related with the friction reduction material which reduces the friction of the pile steel etc. which are used with the column steel sheet pile method etc. which are.

In the downstream part of the river, thick soft soil is often distributed, and when embankment embankment is carried out on such soft ground, in order to cause consolidation settlement over a long period of time, the surrounding houses are inclined, displaced or cracked. In addition to the above, it also causes various subsidence problems such as generating puddles for paddy fields.
Therefore, conventionally, in order to prevent adverse effects such as land subsidence on the surrounding ground, a construction method in which a large number of long steel sheet piles are driven through the soft layer until it reaches the support layer. The bottom steel sheet pile method has been carried out. In other words, the conventional bottomed steel sheet pile method uses a large number of steel sheet piles of almost the same length, and all the steel sheet piles are placed in a row to the lower support layer of the soft layer, and the wall surface (sheet pile wall) is formed. This is a construction method.
According to the results of dynamic measurements such as subsidence and deformation after the construction of such a bottomed steel sheet pile method, subsidence of subsidence was remarkable and the effect of the countermeasure was clear.

So far, the effectiveness of the bottomed steel sheet pile method has been proved, but on the other hand, it has the great disadvantage of being extremely uneconomical. For example, in order to cast up to the support layer, a casting length of 40 m or more may be necessary. In Japan, there are many areas where soft layers of about 40 m or more exist in this area, including the Kanto Plain. In order to drive such a long steel sheet pile, from the viewpoint of transportation and driving of the steel sheet pile, a steel sheet pile having a length of about 20 to 30 m at the maximum is used, and the steel sheet pile is driven. It is necessary to perform the work of welding on site and adding and then placing. Such work must be performed for all steel sheet piles. Therefore, a troublesome work is required for placing one long steel sheet pile. Since the placing work is temporarily interrupted for the welding extension work on the way, the subsequent placing may be difficult, and the work time is long. Therefore, huge construction costs are required to construct the sheet pile wall, and the construction period is long.
By the way, such a grounded steel sheet pile method and subsequent observations have yielded important knowledge that subsidence due to embankment embankments is limited to strata shallower than 20m, about half of the soft layer. . Therefore, a construction method (floating steel sheet pile construction method) in which steel sheet piles were cast halfway through the soft layer was proposed, and the experiment was attempted. However, such a floating steel sheet pile method is effective in shortening the construction period and reducing the construction cost, but the effect of reducing settlement is smaller than the bottomed steel sheet pile method, and the shorter the steel sheet pile length, The margin cutting effect was small. The subsidence caused by embankment embankment was similar to the bottomed steel sheet pile method in that it was limited to the shallower layer than 20m, which is about half of the soft layer about 40m. It is known that the edge cutting effect of subsidence is not sufficient only by shortening the sheet pile.

As a proposal to solve the problems of the floating steel sheet pile method described above, a construction method (post steel) in which a low steel sheet pile (post steel sheet pile) that reaches a support layer is reached to a part of the floating steel sheet pile that is continuously cast. Sheet pile method), that is, a method of combination of floating steel sheet piles and some low steel sheet piles. The basic idea of this construction method is (1) placing floating steel sheet piles to a depth that does not cause subsidence due to embankment embankment, and (2) structure that prevents steel sheet piles from subsiding even if pulling in due to embankment occurs. It is supposed that the two conditions of satisfying are satisfied (patent document 1).
However, it is necessary to provide a large number of landing posts, which is still not sufficient in terms of reducing construction costs and shortening the construction period. Moreover, compared with the conventional complete bottomed steel sheet pile construction method in which all steel sheet piles are cast to the support layer, the blocking effect was still insufficient.

JP 2001-317043 A

The purpose of the present invention is to prevent deterioration of the blocking effect in floating steel sheet pile construction methods, etc., in order to prevent adverse effects on the surrounding ground such as inclination, displacement, cracks, etc. of surrounding houses, underground irrigation channels, circuit pipes, etc. An object of the present invention is to provide a means for minimizing the settlement of the buried object itself, and a treatment agent for the surface of the buried object useful for achieving this.
The purpose of the present invention is to minimize the tip support force of the column steel sheet pile method during subsidence in order to improve work safety and economy in the column steel sheet pile method, etc. The object of the present invention is to provide a means for minimizing the settlement of the embedded object itself even if the number of the material is further reduced, and a treatment agent for the surface of the embedded object useful for achieving this.

  The present invention is a friction reducing material formed on the surface of an embedded object, and is a friction reducing material formed on an embedded object inserted halfway through a soft layer. Thereby, in a construction method (floating steel sheet pile construction method or the like) in which a large number of buried objects that do not reach the support layer in the ground are continuously cast to prevent ground settlement, the settlement of the buried objects can be suppressed. In addition, even in the column steel sheet pile method, etc., even if the tip bearing capacity of the column steel sheet pile method is minimized and the number of partially bottomed steel sheet piles that become the columns is further reduced, the subsidence of the embedded object itself that has been continuously placed can be reduced. Can be suppressed.

  In the present invention, the friction reducing material is preferably a composition containing water-absorbing resin and alkaline water-soluble resin as essential components. The water-absorbent resin absorbs groundwater and swells to form an extremely high water-containing gel. This hydrogel layer is formed on the boundary surface between the surface of the buried object and the ground, and is the material that minimizes the frictional force with the ground. In general, the water-absorbing resin is in the form of a powder, and a binder for bonding is required to form it on the surface of the embedded object. As the binder, an alkali water-soluble resin is an optimal binder that does not prevent water absorption swelling while firmly adsorbing the water absorbent resin to the embedded object. According to this configuration, in a construction method (floating steel sheet pile construction method or the like) for continuously placing a large number of buried objects that do not reach the support layer in the ground and blocking the ground settlement, the settlement of the buried objects can be further suppressed. . In addition, even in the column steel sheet pile method, etc., even if the tip support capacity of the column steel sheet pile method is minimized and the number of partially bottomed steel sheet piles that become the columns is further reduced, the subsidence of the buried object itself that has been continuously placed can be reduced. It can be suppressed more.

  In the present invention, the buried object is preferably a steel sheet pile. Steel sheet piles are the most economical and economical to place a large number of buried objects in the ground. According to this configuration, in a construction method (floating steel sheet pile construction method or the like) for continuously placing a large number of buried objects that do not reach the support layer in the ground and blocking the ground settlement, the settlement of the buried objects can be further suppressed. . In addition, even in the column steel sheet pile method, etc., even if the tip bearing capacity of the column steel sheet pile method is minimized and the number of partially bottomed steel sheet piles that become the columns is further reduced, the subsidence of the embedded object itself that has been continuously placed can be reduced. It can be suppressed more.

  Furthermore, in the present invention, it is preferable that the formation method on the surface of the embedded object is application or pasting. Applying the friction reducing material directly to the buried object is good in construction workability and economical. In the case of pasting, for example, a sheet-like friction reducing material obtained by coating (applying) a friction reducing material on a sheet-like base material such as cloth is pasted on the surface of the embedded object with an adhesive or the like. In this case, the construction workability is further improved, and the work time on site can be shortened.

According to the configuration of the present invention, by significantly reducing the friction on the surface of the buried object used in the floating steel sheet pile method or the column steel sheet pile method, the settlement of the buried object can be minimized. Thereby, the following effects are produced.
(1) Minimize the settlement of buried objects that have been laid continuously to prevent deterioration of the barrier effect, and suppress adverse effects on the surrounding ground such as slopes, displacements and cracks of surrounding houses, underground irrigation channels, and electric pipes. Let
(2) Reduce the load (friction resistance) applied to the buried object, minimize the required strength of the pile, reduce the thickness of the buried object, or change the shape of the buried object to a simple shape such as a simple flat plate. It is possible to improve the weight and handling of buried objects, and improve work safety and economy.
(3) The tip support capacity of the steel sheet pile method during subsidence can be minimized, and the number of partially bottomed steel sheet piles that can be used as support pillars can be further reduced, improving workability, work safety, and economy. Let
(4) For buried objects such as steel sheet piles, it is economically preferable to recover after subsidence, but it is possible to prevent soil from adhering to the ground when the object is withdrawn and removed. Prevent the negative effects of.
(5) It is possible to accelerate the consolidation of the ground to stabilize the ground, which is performed by continuously placing buried objects on both sides of the subsidence such as embankment, which is performed before the start of full-scale construction, shortening the construction period. Is realized.
(6) When the buried object is an underground structure such as a box culvert, tank, or tube, the displacement, crack, or damage of the box culvert, tank, or tube disposed at a predetermined position is prevented.

As an embedded object used in the present invention, a barrier wall, a retaining wall, a consolidation settlement facilitating wall, or a box culvert embedded in the ground, constructed by continuously placing steel sheet piles or the like in the ground There is no particular limitation as long as it is desired to prevent subsidence of steel pipes and tanks.
Specific types of buried objects include, for example, steel sheet piles (sheet piles), steel pipes, fume pipes, H-shaped steels, I-shaped steels, steel pipe piles (steel pipe piles), steel columns, concrete piles, poles, and tubular shapes. Examples include a pile (hollow pile), a flat plate, and a corrugated plate. Among these, steel sheet piles and steel pipe piles that are easy to continuously cast are suitable. The shape, material, surface roughness, etc. of the embedded object are not particularly limited, and the surface may be rusted or contaminated, or may have a smooth surface free of dirt.

  Further, the length in the depth direction of the buried object does not reach the support layer and is a length up to the middle of the soft layer, and is in the range of 5% to 95% of the length from the ground to the support layer. . If it is less than 5%, for example, when used as a blocking wall, the blocking effect is reduced, and the original intended effect is not exhibited. On the other hand, if it exceeds 95%, an extremely long buried object is required, which causes problems in terms of construction workability and economical efficiency. The range is preferably 10% or more and 90% or less, more preferably 25% or more and 75% or less, and particularly preferably 40% to 60%.

  The thickness of the buried object in which the friction reducing material is formed on the surface of the present invention can be made thinner than that required by the conventional method. The thickness can be 90% or less, preferably 75% or less, more preferably 50% or less of the conventional thickness.

The buried object in which the friction reducing material is formed on the surface of the present invention is used for various applications where friction is to be cut and is not particularly limited, but is used for preventing settlement of the surrounding ground or for preventing soil adhesion when the buried object is pulled out and collected. It is preferably used for (preventing soil co-up). Among them, the use for preventing settlement of the surrounding ground by embankment is preferable. More preferably, it is used for prevention of settlement of surrounding ground due to embankment embankment in rivers / ports or road embankment constructed on soft ground.
In addition, by continuously placing an embedded object in which a friction reducing material is formed on the surface of the present invention on both sides of or around the embankment of the embankment and the underground structure, the frictional resistance of the soil with the surface of the embedded object can be reduced. It is possible to improve the subsidence speed of the soil and promote consolidation settlement of the ground.

Next, the friction reducing material of the present invention will be described below.
The friction reducing material is not particularly limited as long as it can exhibit lubricity, but for example, lubricating resins such as water-absorbing resin, fluorine resin, olefin resin, wax, grease, tar, asphalt, etc. Examples thereof include oils and minerals such as bentonite, and one or more of these can be used. Among these, a water-absorbing resin is suitable, and a resin composition containing a water-absorbing resin and water, and a resin composition containing a water-absorbing resin and a binder resin for adhering it to a steel material or the like are also suitable. . The binder resin is particularly preferably an alkaline water-soluble resin, and a form containing a resin composition containing a water-absorbing resin and an alkaline water-soluble resin is one of the preferred forms of the present invention. . In addition, you may contain a solvent as needed.
By using the resin composition containing the water-absorbent resin and the alkaline water-soluble resin, the possibility of inhibiting the volume expansion when the water-absorbent resin swells by absorbing water is reduced, and the water-absorbing performance of the water-absorbent resin is reduced. The water-absorbing resin can be sufficiently swollen with water. As a result, the friction on the surface of the buried object can be greatly reduced.
In the resin composition containing the water-absorbent resin and the alkali-water-soluble resin, the mass ratio of the water-absorbent resin and the alkali-water-soluble resin (water-absorbent resin / alkaline water-soluble resin) includes these compositions, combinations, and working environments. However, it is preferably 1/99 to 99/1, for example. More preferably, it is 10 / 90-90 / 10, More preferably, it is 25 / 75-75 / 25.

  The water-absorbing resin is preferably a resin that swells by absorbing water and has a water absorption ratio of 3 times or more (25 ° C., 1 hour) with respect to its own weight. More preferably, the absorption ratio is 10 times or more. Examples of such a water-absorbing resin include poly (meth) acrylic acid crosslinked bodies, poly (meth) acrylate crosslinked bodies, poly (meth) acrylic ester crosslinked bodies having sulfonic acid groups, and polyoxyalkylene groups. Poly (meth) acrylic acid ester cross-linked product, poly (meth) acrylamide cross-linked product, copolymer cross-linked product of (meth) acrylate and (meth) acrylamide, hydroxyalkyl (meth) acrylate and (meth) acrylic acid Cross-linked copolymer with salt, cross-linked polydioxolane, cross-linked polyethylene oxide, cross-linked polyvinyl pyrrolidone, sulfonated polystyrene cross-linked product, cross-linked polyvinyl pyridine, saponified starch-poly (meth) acrylonitrile graft copolymer, starch-poly ( (Meth) acrylic acid (salt) graft cross-linked copolymer, polyvinyl Water-soluble or hydrophilic compounds such as reaction products of cole and maleic anhydride (salt), crosslinked polyvinyl alcohol sulfonate, polyvinyl alcohol-acrylic acid graft copolymer, polyisobutylene maleic acid (salt) crosslinked polymer ( Monomer and / or polymer) is a synthetic water-absorbing resin obtained by cross-linking with a cross-linking agent; one or more of natural water-swelling materials such as gelatin and agar are suitable. Among them, it is preferable to use a synthetic water-absorbing resin obtained by cross-linking a water-soluble or hydrophilic compound with a cross-linking agent, thereby improving the balance of swelling ratio, water-soluble content, water absorption speed, strength, and the balance. It is also possible to easily adjust.

A preferred form of the water absorbent resin is a water absorbent resin having a nonionic group and / or a sulfonic acid (salt) group. More preferably, it is a water-absorbing resin having an amide group or a hydroxyalkyl group, such as a copolymer crosslinked product of (meth) acrylate and (meth) acrylamide, hydroxyalkyl (meth) acrylate and (meth) acrylic. Examples thereof include a crosslinked copolymer with an acid salt. In these forms, the water absorption with respect to water containing metal ions such as alkaline water and seawater is improved, and the reduction in friction reduction performance due to the influence of soil quality can be prevented.
As the water-absorbing resin, a resin obtained by polymerizing a monomer component containing a water-soluble ethylenically unsaturated monomer and, if necessary, a crosslinking agent can be used. A water-absorbing resin obtained by (co) polymerizing an ethylenically unsaturated monomer is superior in swellability to water and is generally inexpensive. Therefore, by using such a water-absorbing resin, friction reducing performance can be obtained. And can be carried out economically. The crosslinking agent is not particularly limited. In addition, the water-absorbing resin can be formed by adding a crosslinking agent to the linear polymer for crosslinking, or by irradiation with an electron beam for crosslinking.

  Examples of the ethylenically unsaturated monomer include acrylic acid, methacrylic acid, itaconic acid, maleic acid, fumaric acid, crotonic acid, citraconic acid, vinyl sulfonic acid, (meth) allyl sulfonic acid, and 2- (meth). Acrylamide-2-methylpropanesulfonic acid, 2- (meth) acryloylethanesulfonic acid, 2- (meth) acryloylpropanesulfonic acid, and alkali metal salts and ammonium salts of these monomers; N, N-dimethylaminoethyl (Meth) acrylate, and quaternized product thereof; (meth) acrylamide, N, N-dimethyl (meth) acrylamide, 2-hydroxyethyl (meth) acrylamide, diacetone (meth) acrylamide, N-isopropyl (meth) acrylamide, (Meth) acryloylmorpholine and other (meta Acrylamides and derivatives of these monomers; hydroxyalkyl (meth) acrylates such as 2-hydroxyethyl (meth) acrylate and 2-hydroxypropyl (meth) acrylate; polyethylene glycol mono (meth) acrylate, polypropylene glycol mono ( Polyalkylene glycol mono (meth) acrylates such as meth) acrylate, methoxypolyethylene glycol mono (meth) acrylate, and methoxypolypropylene glycol mono (meth) acrylate; N-vinyl simple such as N-vinyl-2-pyrrolidone and N-vinylsuccinimide N-vinylamide monomers such as N-vinylformamide, N-vinyl-N-methylformamide, N-vinylacetamide, N-vinyl-N-methylacetamide; It can be used one or two or more such; methyl ether.

  Among the ethylenically unsaturated monomers, ethylenically unsaturated monomers having a nonionic group and / or a sulfonic acid (salt) group are preferable, for example, 2- (meth) acrylamido-2-methylpropanesulfonic acid , 2- (meth) acryloylethanesulfonic acid, 2- (meth) acryloylpropanesulfonic acid, (meth) acrylamide, hydroxyalkyl (meth) acrylate, methoxypolyethyleneglycol mono (meth) acrylate, etc. Can be used. Water-absorbing resins obtained by polymerizing monomer components containing these are preferable because they are particularly excellent in swelling properties with respect to water containing metal ions such as alkaline water and seawater. By using the water-absorbing resin, friction is achieved. Improve the reduction performance.

In the water-absorbent resin, when two or more ethylenically unsaturated monomers are used in combination as a monomer component, the monomer has a nonionic group and / or a sulfonic acid (salt) group in the entire monomer component. It is preferable that the ratio of the ethylenically unsaturated monomer is 1% by mass or more. If it is less than 1% by mass, the workability of the work of drawing out steel or the like may not be further improved. More preferably, it is 10 mass% or more.
In addition, as a suitable combination in the case of using together 2 or more types of ethylenically unsaturated monomers as a monomer component, the combination of (meth) acrylic-acid alkali metal salts, such as sodium acrylate, and acrylamide, ( Although the combination etc. of a meth) acrylic-acid alkali metal salt and methoxypolyethyleneglycol mono (meth) acrylate are mentioned, It does not specifically limit.

The water-absorbing resin can be obtained by (co) polymerizing the monomer components described above, but the (co) polymerization method is not particularly limited, and can be performed by a commonly used method. . Further, the average molecular weight and shape of the water-absorbent resin, the average particle diameter, and the thickness and the coating amount of the lubricating layer having such a water-absorbent resin may be appropriately set according to the use application or work environment, It is not particularly limited. For example, as an average particle diameter, it is preferable that an upper limit is 1000 micrometers. If it exceeds 1000 μm, the coating property (coating property) for forming the lubricating layer is not sufficient, and the distribution of the water-absorbing resin in the lubricating layer is not uniform, and the lubricating performance is excellent. There is a risk that it will not be possible. A more preferable upper limit is 500 μm, and a further preferable upper limit is 200 μm. The lower limit is preferably 1 μm. A more preferred lower limit is 5 μm, and a still more preferred lower limit is 10 μm.
In the resin composition of a suitable form of the friction reducing material, the alkali water-soluble resin means a resin that does not dissolve in water exhibiting acidity or neutrality but dissolves in water exhibiting alkalinity. Here, “neutral water” is water having a pH value in the range of 6 to 8, and “water exhibiting acidity” is water having a pH value less than the neutral range, “Water exhibiting alkalinity” is water having a pH value larger than the neutral range.
In addition, as said alkali-water soluble resin, the thing of 50-100% of the reduction | decrease rate calculated | required by the following evaluation test as a grade of the solubility to alkaline water is preferable. More preferably, it is 60 to 100%, and still more preferably 70 to 100%.

(Evaluation test for solubility in alkaline water)
An alkaline water-soluble resin that can be obtained using a twin screw extruder is measured using a resin molded into a cylindrical pellet shape having a diameter of 5 mm and a length of 5 mm. 10 g of this molded body is put into 500 g of a 0.4% by weight NaOH aqueous solution in a 1 L beaker, and stirred at 25 ° C. with a diameter of 40 mm and four splashes at 300 rpm for 24 hours. . It evaluates by the decreasing rate from the original molded object of the mass melt | dissolved in the alkaline water in the molded object of subsequent alkali water soluble resin. That is, for the resin component remaining undissolved after stirring for 24 hours, it is filtered, washed with water, the mass after drying is determined, and from the mass of the original alkaline water-soluble resin before being subjected to the solubility test % (%); (Original mass-mass after solubility test) / (original mass). Moreover, even if it is not pelletized, even if it is a molded product of an arbitrary shape of 5 mm square or less, when it shows solubility in alkaline water, it is within the range of the alkaline water-soluble resin.

  Examples of the alkaline water-soluble resin include one or more resins such as a resin having a substituent such as a carboxylic acid group, a sulfonic acid group, and a phosphonic acid group; a novolak resin containing a phenolic hydroxyl group; and a polyvinyl phenol resin. Can be used. Among them, in addition to α, β-unsaturated carboxylic acid monomers and α, β-unsaturated carboxylic acid monomers in terms of excellent solubility in alkaline water, economic efficiency, and various physical properties of the resin composition. A resin obtained by copolymerization with a vinyl monomer is preferred.

In addition, cellulose derivatives such as hydroxypropylmethylcellulose phthalate, hydroxypropylmethylcellulose acetate succinate, cellulose acetate hexahydrophthalate, hydroxypropylmethylcellulose acetate phthalate, and hydroxypropylmethylcellulose hexahydrophthalate, which are resins having a carboxylic acid group, can also be used.
Examples of the α, β-unsaturated carboxylic acid monomer include α, β-unsaturated monocarboxylic acids such as acrylic acid and methacrylic acid; α, β-unsaturated materials such as itaconic acid, maleic acid, and fumaric acid. Saturated dicarboxylic acids; α, β-unsaturated dicarboxylic anhydrides such as maleic anhydride and itaconic anhydride; α, β-unsaturated dicarboxylic monoesters such as maleic acid monoester, fumaric acid monoester and itaconic acid monoester 1 type, or 2 or more types can be used. Among them, acrylic acid and / or methacrylic acid are preferable because of excellent flexibility and toughness.

Examples of the vinyl monomer include, for example, methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, stearyl acrylate, methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, stearyl methacrylate. Esters of monohydric alcohols having 1 to 18 carbon atoms such as (meth) acrylic acid; nitrile group-containing vinyl monomers such as acrylonitrile and methacrylonitrile; amide group-containing vinyl monomers such as acrylamide and methacrylamide Body; hydroxyl group-containing vinyl monomers such as hydroxyethyl acrylate and hydroxypropyl methacrylate; epoxy group-containing vinyl monomers such as glycidyl methacrylate; α, β-unsaturated such as zinc acrylate and zinc methacrylate Metal salt of carboxylic acid; styrene, α-me Aromatic vinyl monomers such as rustyrene; Aliphatic vinyl monomers such as vinyl acetate; Halogen group-containing vinyl monomers such as vinyl chloride, vinyl bromide, vinyl iodide and vinylidene chloride; Allyl ethers Maleic acid derivatives such as maleic anhydride, maleic acid monoalkyl esters and maleic acid dialkyl esters; fumaric acid derivatives such as fumaric acid monoalkyl esters and fumaric acid dialkyl esters; maleimide, N-methylmaleimide, N-stearylmaleimide, N; -Maleimide derivatives such as phenylmaleimide and N-cyclohexylmaleimide; Itaconic acid derivatives such as itaconic acid monoalkyl ester, itaconic acid dialkyl ester, itaconic amides, itaconic imides and itaconic amide esters; alkenes such as ethylene and propylene; Tajien, dienes such as isoprene and the like, can be used alone or in combination.
Among these vinyl monomers, acrylic acid alkyl esters and / or methacrylic acid alkyl esters are preferable in terms of excellent flexibility, weather resistance, and toughness. More preferably, it is a (meth) acrylic acid alkyl ester obtained by esterifying these monohydric alcohols having 1 to 18 carbon atoms and (meth) acrylic acid. Moreover, it is preferable that the usage-amount of (meth) acrylic-acid alkylester shall be 30-100 mass% with respect to 100 mass% of vinyl-type monomers used, and, thereby, the softness | flexibility of a resin composition or The weather resistance and toughness can be further improved. More preferably, it is 50-100 mass%.

As a mass ratio of the α, β-unsaturated carboxylic acid monomer and the vinyl monomer, the α, β-unsaturated carboxylic acid monomer is used with respect to a total amount of 100% by mass. It is preferable that it is 9 mass% or more, and it becomes possible to improve the solubility with respect to alkaline water more by this. In addition, the range of the α, β-unsaturated carboxylic acid monomer is preferably 9 to 40% by mass, and in this case, not only the solubility in alkaline water but also the flexibility and weather resistance. Alkaline water-soluble resin having particularly excellent properties and toughness can be obtained.
The alkaline water-soluble resin can be obtained by (co) polymerizing monomer components such as the above-described α, β-unsaturated carboxylic acid monomer and vinyl monomer. The polymerization method can be carried out by a commonly used method.
In the alkaline water-soluble resin such as the above-mentioned alkaline water-soluble resin, the weight average molecular weight (Mw) can be appropriately set according to the composition of the soil and hydraulic composition constituting the ground, the pH of the alkaline water, the working environment, and the like. However, the lower limit is preferably 10,000 and the upper limit is preferably 2,000,000. In this range, adhesion to the steel material and workability will be more fully exhibited. A more preferred lower limit is 30,000, a still more preferred lower limit is 50,000, and a particularly preferred lower limit is 100,000. A more preferred upper limit is 1.5 million, a still more preferred upper limit is 1 million, and a particularly preferred upper limit is 900,000.
The weight average molecular weight (Mw) is determined by using TSK standard polystyrene PS-oligomer kit (manufactured by Tosoh Corporation) as a standard substance for molecular weight calibration, and tetrahydrofuran (stabilizer-containing (manufactured by Wako Pure Chemical Industries, Ltd., special grade reagent) as a solvent. ) Using a high-speed GPC apparatus / HLC-8120GPC (manufactured by Tosoh Corporation).

  The acid value (mgKOH / g) of the alkaline water-soluble resin is preferably 15 or more. If it is less than 15, the solubility in alkaline water is lowered, so that the pullability and friction reduction effect of the pile may be lowered, and the drawing work may not be facilitated. More preferably, it is 30 or more, More preferably, it is 50 or more, Most preferably, it is 70 or more. Moreover, it is preferable that it is 500 or less. If it exceeds 500, the water resistance of the alkaline water-soluble resin will not be sufficient, and there is a risk of dissolution and damage if it comes into contact with water having a neutral or acidic pH such as rain. There is a possibility that work or the like cannot be performed more efficiently.

As the glass transition temperature of the alkali water-soluble resin, the glass transition temperature (from −80 to 120 ° C. is considered from the viewpoint of compatibility between the adhesion to the steel material surface and the toughness of the resin composition when the steel material is embedded in the soil. It is preferable to have at least one Tg), more preferably two or more. By setting the glass transition temperature within the above range, the strength and flexibility of the friction reducing material layer can be made sufficient, and the working efficiency can be further increased. As a particularly preferable form of the alkaline water-soluble resin, it has a Tg on the low temperature side in the range of −30 to 20 ° C., and two or more glass transition temperatures on the high temperature side in the range of 40 to 100 ° C. It is preferable to have Tg, whereby the balance between the softening component and the shape-retaining component can be further improved.
The glass transition temperature is the peak top (DSC curve inflection point) of the DSC differential curve obtained by differential scanning calorimetry (DSC).

In the resin composition of the suitable form of the said friction reduction material layer, it does not specifically limit as a solvent which may be contained, For example, the solvent used for a normal coating material etc. may be used. Specifically, alcohols such as methanol, ethanol and isopropyl alcohol; aromatic hydrocarbons such as benzene and toluene; ketones such as acetone and methyl ethyl ketone; aliphatic esters such as ethyl acetate and butyl acetate; ethylene glycol; One or more of ethylene glycol derivatives such as ethylene glycol monomethyl ether, and propylene glycol derivatives such as propylene glycol monomethyl ether and propylene glycol monomethyl ether acetate can be used. In addition, the solvent contained in alkaline water soluble resin can also be used as a solvent.
The solvent (solvent) also preferably has a property of dissolving the alkaline water-soluble resin. When the solvent dissolves the alkaline water-soluble resin, the alkaline water-soluble resin is more uniformly dispersed in the resin composition. Thus, the performance as an alkaline water-soluble resin can be preferably expressed. As a solvent for dissolving the alkaline water-soluble resin, it is preferable to use a polar solvent. More preferably, it is at least one selected from alcohols, ketones, aliphatic esters and alkylene glycols from the viewpoint of solubility in alkaline water.
The resin composition may also contain additives such as other resins, pigments, surfactants, various stabilizers, and various fillers as long as the effects of the resin composition are not impaired.

The form of the friction reducing material of the present invention includes a liquid, a viscous body (including a dispersion), a powder, a sheet form, and the like, and is not particularly limited as long as friction on the surface of the embedded object can be reduced. From the viewpoint of forming the liquid, a liquid or sheet form is preferable.
When the friction reducing material is a liquid, it can be applied directly to the surface of an embedded object, which is economical and preferable.
When the friction reducing material of the present invention is a liquid friction reducing material, it is necessary to make it a liquid having an appropriate viscosity that can be applied, and it is prepared by selecting a suitable binder resin or a solvent. Alkaline water soluble resins are suitable as binder resins.
Moreover, when a friction reducing material is a sheet | seat form, it affixes on the surface of an embedded object through an adhesive agent etc.

Sheet-like friction reducing materials can be made by forming a resin-like material by melting or molding a lubricious resin, or by applying a powder-like friction reducing material to a sheet-like substrate such as cloth together with a binder resin (coating) It is obtained by the method to do. Compared to the case where the friction reducing material is applied directly to the buried object, the sheet-like friction reducing material is easier to apply to the surface of the buried object and improves the workability of work. Since a material layer can be formed, it is one of the preferable forms.
The method for forming the friction reducing material layer on the surface of the sheet-like base material is not particularly limited as long as it is appropriately selected depending on the lubricity substance (lubricant), the material of the base material, and the like. In addition to spray coating, brush coating, roller coating, and the like, a method of impregnating a substrate with a solution containing a lubricant may be used. Specifically, for example, in the case of using a resin composition containing an alkaline water-soluble resin and a water-absorbing resin, a dispersion (resin) obtained by dispersing (or dissolving) both in a dispersion medium such as an organic solvent or water. A method of spraying (solution) onto the surface of a substrate; a method of applying a resin solution by brushing or using a roller; a method of impregnating a resin solution on a substrate; a solution or dispersion containing an alkaline water-soluble resin After spraying or coating the surface of the substrate, a method of spraying or coating the solution or dispersion on the surface of the water-absorbing resin uniformly distributed on the surface, and the like can be mentioned.

The thickness of the friction reducing material layer is not particularly limited as long as it is appropriately set according to the components and the like, and for example, the lower limit is preferably 0.01 mm and the upper limit is preferably 5 mm. If the thickness is less than 0.01 mm, the effect of each layer may not be sufficiently exhibited. If the thickness exceeds 5 mm, the handleability and storage stability of the sheet may not be sufficient. A more preferred lower limit is 0.02 mm and an upper limit is 1 mm, and a still more preferred lower limit is 0.05 mm and an upper limit is 0.5 mm.
Further, the ratio of the friction reducing material layer to the base material, that is, the amount of the lubricant attached per unit area of the base material may be set according to the composition and combination of both, the working environment, etc., and is not particularly limited. For example, it is preferably within the range of 1 to 10000 g / m2. More preferably, it is 10-5000 g / m <2>, More preferably, it is 20-1000 g / m <2>. In addition, it is preferable that it is 1-10000 weight part as a ratio of the lubricant with respect to 100 weight part of base materials. More preferably, it is 10-1000 weight part, More preferably, it is 20-500 weight part.

  The ground to which the friction reducing material of the present invention is applied is not particularly limited as long as it causes ground subsidence, but the effect is remarkable when applied to a soft layer having an N value of 40 or less, which is preferable. More preferably, it is applied to a soft layer having an N value of 25 or less. More preferably, it is applied to a soft layer having an N value of 10 or less. It is particularly preferable to apply to a soft layer having an N value of 5 or less.

  The present invention will be described in more detail with reference to the following examples. However, the present invention is not limited to these examples. Unless otherwise specified, “part” means “part by weight” and “%” means “mass%”.

  In the following, the weight average molecular weight (Mw) is obtained by using TSK standard polystyrene PS-oligomer kit (manufactured by Tosoh Corporation) as a standard substance for molecular weight calibration, and tetrahydrofuran (stabilizer-containing (manufactured by Wako Pure Chemical Industries, Ltd., reagent special grade) as a solvent. The glass transition temperature (Tg) was measured by a differential scanning according to the plastic transition temperature measurement method of JIS K7121-1987, using a high-speed GPC device / HLC-8120GPC (manufactured by Tosoh Corporation). It was measured (heating rate: 10 ° C./min) with a calorimeter / DSC6200 (manufactured by Seiko Denshi Kogyo).

[Preparation of alkaline water-soluble resin]
Alkaline water-soluble resin was prepared by the following method. That is, in a tank reactor having a capacity of 100 L equipped with a thermometer, a stirring blade, a reflux condenser and a dropping device, 1.8 kg of acrylic acid, 10.2 kg of ethyl acrylate, and 2,2′-azobis which is a polymerization initiator. -24 g of (2,4-dimethylvaleronitrile) and 28 kg of methyl alcohol as a solvent were charged. In addition, from the dropping device, 2.7 kg of acrylic acid, 5.4 kg of methyl acrylate, 9.9 kg of methyl methacrylate, 66 g of 2,2′-azobis- (2,4-dimethylvaleronitrile), and 2 kg of methyl alcohol A mixed solution was prepared.
The above methyl alcohol solution was heated to 65 ° C. with stirring in a nitrogen gas atmosphere and allowed to react for 20 minutes. Thereby, the polymerization rate of the contents was adjusted to 72%. Subsequently, while maintaining the internal temperature at 65 ° C., the above mixed solution was uniformly dropped from the dropping device over 2 hours. After completion of dropping, the contents were aged at 65 ° C. for another 3 hours. After completion of the reaction, the content was mixed with 60 kg of methyl ethyl ketone to obtain a 25% by mass solution of an alkaline water-soluble resin.
The acid value of the obtained alkali-soluble resin was 117 mgKOH / g. Moreover, the weight average molecular weight Mw of this alkaline water soluble resin was 16,000, and the number average molecular weight Mn was 69,000. Furthermore, when measured with a differential scanning calorimeter, glass transition temperatures (Tg) were observed at 10 ° C. and 67 ° C. Moreover, the solubility of the binder resin in ion exchange water at 25 ° C. was less than 0.5%, and the solubility in alkaline water was 100%.

(Water absorbent resin)
As the water-absorbent resin, a commercially available polyacrylic acid sodium salt crosslinked product (trade name: Aqualic CA ML-70, average particle size 50 μm, manufactured by Nippon Shokubai Co., Ltd.) was used.

[Production of friction reducing material]
By mixing the ASP solution and SAP so that the solid content of the alkaline water-soluble resin (hereinafter referred to as ASP) and the water-absorbing resin (hereinafter referred to as SAP) is 1: 1, the lubricating layer and A composition (resin solution) to be obtained was obtained. The composition is applied to a woven fabric (90 g / m 2, thickness 0.23 mm, polyester / cotton = 60/40, blended woven fabric) cut to a size of 75 × 40 mm, and the resin solid content coating amount is 120 g / m 2. Before drying, the auxiliary base material (weight: 41 g / m2, thickness: 0.08 mm, elongated film (fiber) width: 0.5-2 mm, lattice hole width: 2 mm) is combined from the top of the composition layer. The sample was then dried to produce a sheet-like friction reducing material.

[Friction test]
Using the testing machine shown in FIGS. 2 and 3, the frictional force between the soil (ground) and the pile (buried object) under pressure was measured.
First, a pile with a friction reducing material attached to the surface is vertically inserted in the center of a stainless steel main body container having an inner diameter of 80 mm and a height of 180 mm, and soil is put into the soil filling portion having an inner diameter of 80 mm and a height of 80 mm. Filled. Next, cover the main body container with the top plate and the bottom plate, and measure the frictional force generated when the pile is rotated at a speed of 10 mm per minute with a pressure of 20 kg / cm2 applied with a pressurizer for one year. did.
The pile used in the test is a steel pipe having a length of 300 mm and an outer diameter of 21 mm, and the soil used in the test is a soil obtained by mixing 840 g of Toyoura standard sand and 190 g of water.
The pressurizer used in the test was RIKEN SEIKI CO. LTD. This is a hydraulic pump manufactured by (RIKEN). (Measurement limit 100 MPa)
The top plate and the bottom plate are iron plates having an outer diameter of 200 mm and a thickness of 24 mm. The main body is installed between the top plate and the bottom plate, and the top plate and the bottom plate can be fixed with long bolts and nuts. Pressure can be applied from below by a pressurizer.
The results are shown in FIG.

  Compared to the untreated pile that did not use the friction reducing material, the friction force of the pile treated with the friction reducing material (FRC treatment) is 1/10 compared with the data after one year. It was found to reduce the frictional resistance.

From this result, it was found that the friction of the buried object surface can be made very small. Therefore, the settlement of the buried object itself can be minimized, the adverse effects on the surrounding ground can be suppressed, and the load applied to the pile can be reduced. The size can be reduced, the thickness can be reduced, and the shape of the buried object can be changed to a simple shape.
Moreover, when applied to the case of a steel pillar sheet pile, it is possible to reduce the tip support force of the bottomed steel sheet pile required during subsidence, it is possible to reduce the number of bottom steel sheet piles, In addition, when extracting and recovering buried objects, it is possible to suppress soil adhesion (co-up), and to accelerate the consolidation of the ground to stabilize the ground before full-scale construction starts. This makes it possible to reduce the work period. Furthermore, it is possible to prevent displacement, cracking, and damage of a box culvert, a tank, a tubular body, etc. that are buried in the ground and arranged at a predetermined position.

It is a figure which shows the result of having measured the frictional force which arises in a pile. In the figure, solid line 1 is a result of measuring the friction force generated in the pile coated with the friction reducing material of the present invention, and broken line 2 is a result of measuring the friction force generated in the pile not coated with the friction reducing material of the present invention. It is. It is a figure which shows the shape of the testing machine used for the frictional force measurement test. In addition, the unit of the number in a figure is a millimeter. It is a photograph which shows the external appearance of the testing machine used for the frictional force measurement test.

Claims (4)

A friction reducing material formed on the surface of an embedded object, wherein the friction reducing material is formed on an embedded object inserted halfway through a soft layer. The friction reducing material according to claim 1, wherein the friction reducing material is a composition comprising a water-absorbing resin and an alkaline water-soluble resin as essential components. The friction reducing material according to claim 1 or 2, wherein the buried object is a steel sheet pile. The friction reducing material according to any one of claims 1 to 3, wherein the formation method on the surface of the embedded object is coating or pasting.

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