JPS6320274B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention improves the rockability of the soil and reduces the frictional force with equipment by adding a super absorbent polymer that becomes a spherical elastic body after absorbing water and mixing and stirring the soil. This article relates to a method of pumping excavated soil, which is characterized by its characteristics. As a method for continuously transporting earth and sand in a narrow space without contaminating the surrounding area, there is a construction method that uses a medium to transport the earth and sand inside a pipe. The media include compressed air and muddy water, which are called pneumatic transport and muddy water transport, respectively. When compressed air is used, the soil must be smooth and sandy with a low moisture content, and when muddy water is used, it is difficult to separate the muddy water and sand after transporting it, which requires a lot of effort. There was a problem. In addition, in construction methods that attempt to transport the excavated soil inside the tube without using a medium, if a pressure pump such as a concrete pump is used to pump the excavated soil as it is inside the tube, problems may occur due to the internal friction angle of the soil. There was a problem in that the frictional force caused by this and the adhesive force caused by the adhesion of the soil were generated between the pipe and the soil, and this became a resistance force, making it impossible to transport long distances. In order to reduce the resistance in these methods of continuously transporting earth and sand, a method has been proposed in which a friction reducing material is mixed with the soil, the mixture is thoroughly stirred, and the soil is pumped using a pressure pump. This anti-friction material is based on bentonite slurry, which is made by adding water, bentonite (a mineral substance), and other additives. In this case, if about 30% or more of the earth and sand is mixed, the friction reduction effect is good, but the earth and sand after being conveyed has a high viscosity and is difficult to dispose of. As a result of various studies on these problems, the present inventors found that when excavated soil is mixed with a specific type of superabsorbent polymer that absorbs water and becomes a spherical elastic body, the friction reduction effect is significant and Super absorbent polymer absorbs water,
The present inventors have discovered that the discharge of water occurs reversibly, and there is no problem even if the transported earth and sand is used as embankment material, making it easier to dispose of the transported earth and sand, resulting in the present invention. An object of the present invention is to provide a construction method for pumping excavated soil. In other words, by using a small diameter spherical elastic body made of a specific type of super absorbent polymer, the properties of the spherical elastic body as a solid substance, that is, the bearing action, are utilized, and the specific type of super absorbent polymer is used. Based on its excellent features such as good water retention and high strength when swollen, it improves the sustainability of its good anti-friction effect and makes it widely applicable to various types of excavated soil. The content of the present invention will be specifically shown below. After the superabsorbent polymer used in the present invention absorbs water,
It becomes a spherical elastic body, and is a saponified copolymer obtained by suspension polymerization of vinyl ester and acrylic acid or its ester, or a crosslinked copolymer of acrylic acid or its salt obtained by suspension polymerization. Consists of merging. Suspension polymerization is essential for obtaining an elastic body that becomes spherical when it absorbs water. Suspension polymerization of vinyl ester and acrylic acid or its ester is carried out at a molar ratio of 20:80 to 80:
It is preferable to do this in the range of 20. Examples of this crosslinked polymer include self-crosslinked acrylic acid and/or acrylate polymers, polymers obtained by polymerizing acrylic acid and/or acrylates in the presence of a crosslinking agent, and acrylic acid and/or acrylic acid polymers. Acrylic acid and/or acrylic acid having a structure in which an acid salt polymer is post-crosslinked with a compound having two or more epoxy groups, isocyanate groups, hydroxyl groups, amino groups, etc., and crosslinked with divalent or higher metal ions. Examples include salt copolymers. The water absorption rate and average particle size of the superabsorbent polymer used in the present invention, which becomes a spherical elastic body when water is absorbed, are not particularly limited.
A particle size of 100 to 3000 times is desirable, and a practical particle size is one that becomes a spherical elastic body of 0.01 mm to 15 mm after absorbing distilled water. The ratio of these spherical superabsorbent polymers to the excavated soil varies depending on the type or water content of the excavated soil, and is not particularly limited, but is generally about 0.01% to 100% of the excavated soil. Next, a typical implementation method of the present invention will be shown using figures. (1) Implementation method-1 (Figure 1) Super absorbent polymer that has absorbed liquid produced on the ground or underground is placed into the bulkhead of a shield excavator 1 equipped with an earth removal device (screw conveyor 4). The excavated soil can be injected as is or mixed with the excavated soil using the stirring device inside the cutter to reduce the frictional resistance inside the cutter, and to cut off the pressure water in the cutter and earth removal device. After receiving the soil in a hopper in the mine, it is pumped by a pressure pump 5 to a hopper 10 on the ground or directly to a dump for disposing of earth and sand. Alternatively, the soil is directly pumped to the ground using a pressure pump 5 installed in the soil removal device. (2) Implementation method-2 (Figure 2) Earth and sand excavated by a shield excavator 11 that directly discharges excavated soil from the face is discharged to a hopper by an earth and sand transport device (belt conveyor 14), and then the soil is placed on the ground or A method in which a superabsorbent polymer produced in a mine is put in, mixed and stirred with excavated sand, and the mixture is pumped using a pressure pump 15 to a hopper on the ground or directly to a dump for disposing of earth and sand. In this way, after absorbing water as an anti-friction material in the excavated soil,
By adding a specific type of superabsorbent polymer that becomes a spherical elastic body, when excavated soil is pumped by a pressure pump, the pressure resistance is reduced and it becomes possible to continuously convey it over a long distance. In the construction method of the present invention, conventionally used mineral substances, organic glues, surfactants, oils, etc. are used together with a specific type of super absorbent polymer that becomes a spherical elastic body when absorbed by the present invention. are also included in the present invention. The present invention will be explained in more detail with reference to Reference Examples and Examples below, but the present invention is not limited thereto. Reference Example 1 Add 0.5 g of benzoyl peroxide as a polymerization initiator to 60 g of vinyl acetate and 40 g of methyl acrylate, and add 0.2 g of partially saponified polyvinyl alcohol (degree of saponification 88 mol%, degree of polymerization 2000) and 8 g of sodium chloride. The mixture was dispersed in 200 ml of water, and suspension polymerization was carried out at 65°C for 6 hours. Next, 30 g of the copolymer was added to a solution of 16.2 g of sodium hydroxide dissolved in a mixed solvent of 100 ml of methanol and 30 ml of water, and the mixture was further heated at 30°C for 2 hours.
Saponification reaction is carried out at 60°C for 5 hours. After the saponification reaction was completed, the product was sufficiently washed with methanol and then dried under reduced pressure to obtain 24 g of a spherical dry saponified product having a particle size of 20 μm to 200 μm. The spherical saponified product thus obtained was insoluble in water, swelled quickly in water, and had a water absorption rate of 750 g/g with respect to distilled water. Reference Example 2 133.1 g of water was placed in a polymerization tank, and 44.7 g of sodium hydroxide was added and dissolved with stirring. While cooling with ice, 100 g of acrylic acid was gradually added and neutralized with stirring. Potassium persulfate 0.0667g and N,N'-methylenebisacrylamide 0.01g
Add. Furthermore, add 6.0 g of sorbitan monostearate and 700 ml of normal hexane, and add 6.0 g of sorbitan monostearate while stirring.
Polymerization was carried out at ℃ for 3 hours. After the polymerization was completed, 125.2 g of a spherical superabsorbent polymer was obtained by separating solid and liquid and drying under reduced pressure. The particle size of the obtained superabsorbent polymer was 10μ to 150μ. Also, the water absorption rate is 560g/
It was hot at g. Example 1 The superabsorbent polymer obtained in Reference Example 1 was used as a component of an anti-friction material, and sandy soil was mixed in various proportions. At this time, the blending ratio of the anti-friction material was as follows.

[Table] The internal friction angle and adhesive strength of this mixed soil were determined by a direct shear test. The results are shown in Figure 3, which compares the results with the conventionally used bentonite mud-type antifriction material mixed with sandy soil. The effect of conventional bentonite mud type anti-friction material is that the mixing ratio of anti-friction material (weight of anti-friction material/weight of mixed soil) is approximately 15
It is hardly effective at less than 15% to 30%, and becomes rapidly effective. On the other hand, the anti-friction material of the present invention is approximately proportional to the mixing ratio, and the effect of the anti-friction material appears. (Coefficient of friction
tan decreases. ) This shows that the anti-friction material of the present invention has a better long-lasting anti-friction effect even if the anti-friction material contains soil from the ground and the mixing ratio of the anti-friction agent becomes low. Furthermore, it is shown that the friction reduction effect is excellent when the mixing ratio is less than 30%. Furthermore, the same effect was obtained even when the superabsorbent polymer obtained in Reference Example 2 was used.

[Brief explanation of the drawing]

FIGS. 1 and 2 are schematic diagrams showing a typical implementation method of the present invention. 1... Shield body, 2... Bulkhead, 3... Sediment inside the bulkhead, 4... Earth removal device, 5... Pressure pump, 6
...Anti-friction material injection pipe, 7...Mixed soil removal pipe, 8
... Gland pump, 9 ... Batch for injecting anti-friction material, 10 ... Hopper or dump, 11 ...
Shield body, 12... Partition wall, 13... Earth and sand in partition wall, 14... Belt conveyor, 15... Pressure pump, 16... Stirrer, 17... Anti-friction material injection pipe,
18...Batch for injecting anti-friction material, 19...Ground pump, 20...Pipe line for removing mixed soil, 21...Hopper or dump. FIG. 3 is a graph showing the relationship between the friction reducing agent mixing ratio and the friction coefficient (tan) of the friction reducing material mixed soil of the present invention. The horizontal axis in the figure shows the mixing ratio of anti-friction material (weight of anti-friction material/weight of mixed soil x 100) (%).

Claims (1)

[Claims] 1. When soil is pumped with a pressure pump, it absorbs water and becomes a spherical elastic body, and is a saponified copolymer obtained by suspension polymerization of vinyl ester and acrylic acid or its ester. A method in which a spherical elastic body made of a superabsorbent polymer absorbs water and is present in the soil to increase the rockability of the soil and reduce pressure resistance. 2. When soil is pumped with a pressure pump, it absorbs water and becomes a spherical elastic body. Let it exist in the soil,
A method to increase soil oscillation and reduce pressure resistance.