JPS5851570B2 - Method for forming a water stop film on the concave surface of an excavated pond - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to forming a water-stop film to prevent water leakage in a concave surface such as a peripheral wall or bottom surface of an excavated pond used for storing water or dumping industrial waste. It is something.

These days, not only are drilled ponds used to store water, but also a large number of drilled ponds are being drilled to dump industrial waste.

Naturally, these excavated ponds are equipped with waterproof measures.

This waterproofing measure only needs to be considered for an excavated pond for storing water, but only to prevent water loss due to leakage of the stored water, but for an excavated pond for dumping industrial waste, it is necessary to consider the prevention of water loss due to water leakage. Consideration must be given to the first problem of pollution, such as toxic substances being dissolved in rainwater, seeping into water, and flowing into groundwater.

Conventionally, waterproofing measures for these excavated ponds include forming a water-stopping film by stretching the pond with an asphalt sheet made of a rubber sheet or mat-like nonwoven fabric impregnated with asphalt, or by coating the pond with a special hydrophilic urethane resin. Methods such as letting

However, all of these methods have the following defects and cannot provide complete waterproofing measures, and improvements are needed.

In other words, rubber sheets and asphalt sheets of any size are jointed with appropriate adhesives, etc., but since the sheets are constantly soaked with water, they deteriorate over time. As the rubber deteriorates, the joint portions between the sheets develop poor adhesion due to the rubber deterioration and water pressure, causing them to separate.

In addition, asphalt sheets can peel or break due to poor adhesion at the joints of the sheets, and they also contain carcinogenic substances such as tar, which is a major problem because they can be leached into groundwater from the broken parts. .

Furthermore, in the case of waterproof membranes using urethane resin, the membrane is only a surface film and is weak, and the permeation pressure caused by the water buildup causes blistering, and the membrane peels off or breaks from this area. Another drawback is that toxic phenol in the urethane resin component is eluted.

The inventor of the present invention has investigated the formation of a water-stop film that overcomes the drawbacks of conventional waterproofing methods, and has found that water absorption, moisture absorption,
An emulsion mixture that produces a large amount of emulsion hydrate, mainly consisting of an emulsion of highly swellable ethylene-vinyl acetate copolymer, is infiltrated into the concave surfaces of the circumferential wall and bottom of the excavation pond to a predetermined depth, and is dried and stopped. If a water film is formed, even if water percolates from the bottom due to water permeation pressure, when it reaches the water stop film, the water will be trapped in the emulsion in the water stop film, causing the emulsion to swell and become smaller. The present invention has been based on the discovery that it is possible to prevent the seepage of .

That is, the present invention was conceived from the idea of making full use of the water absorption, moisture absorption, and swelling properties of the emulsion of ethylene-vinyl acetate copolymer, which is the main component, which are normally considered to be defects. The above-mentioned properties of this emulsion attract water and when the molecules become large, the suction force between the molecules becomes stronger than the osmotic pressure of the water, preventing further water from penetrating, making it effective as a water-stop film. It shows itself.

From this point of view, in the present invention, a material such as ethylene-vinyl acetate emulsion, which has a very high water absorption rate and swelling rate when dried to form a film, is used. An emulsion mixture that can produce a large amount of emulsion hydrate by adding inorganic substances is poured onto the peripheral wall and bottom of the excavation pond to form a water-stopping film as described above at a required depth in the soil.

Specifically, the film formed by the emulsion of ethylene-vinyl acetate copolymer takes advantage of the special property that it swells and breathes when it absorbs water, and as an admixture, it has water absorption and water retention properties and improves drying properties. Portland cement is mixed with silica sand, natural pumice, etc. to increase the density, strength, pressure resistance, and chemical resistance of the membrane, and methyl cellulose is added to make a paste-like emulsion for water conservation during pouring, and to form a thick membrane. Cellulose derivatives such as ethyl hydroxyethyl cellulose and ethyl hydroxyethyl cellulose are added.

Because the membrane in the soil is formed by pouring such an emulsion mixture, even if the water stored in the excavation pond reaches the membrane due to osmotic pressure, particles of admixtures such as silica sand and natural pumice cannot be removed. The breathing action of the surrounding flexible, breathable ethylene-vinyl acetate copolymer emulsion draws in water, causing the molecules to grow and intertwine, and the attraction between the molecules prevents further water seepage. That's what I do.

In the present invention, when making the emulsion mixture that constitutes the water-stop film, the base emulsion is an emulsion of ethylene-vinyl acetate copolymer that has excellent water absorption, water retention, and swelling properties, and is alkali-resistant as a water-stop film. The best emulsion in terms of swelling rate and other factors is an emulsion containing polyvinyl alcohol as a protective colloid.

However, the emulsion mixture used in the present invention to form a water-stopping film is poured into the concave surface of the excavation pond as a cement paste-like viscous substance using Portland cement.
As a method, it may be poured at once as a moderately viscous material, but it is preferable that the emulsion penetrates into a thickness of approximately 20 m/m, so in this case, if the emulsion is viscous, it will take time to form the film. In addition, since it may not penetrate sufficiently into the soil, first pour a highly diluted admixture into the soil with a small amount of cement to reach the desired depth of 1.
A two-step construction method may be used, including infiltration with water and then pouring a cement-rich consistency.

In this way, if the stored water seeps into the water,
It has a water-stopping effect that completely prevents water from penetrating.

This will be explained with reference to the drawings.

Figure 1 is a state diagram of the water-stopping film A when the paste-like emulsion mixture is poured into soil S and dried, and Figure 2 is a state diagram of the water-stopping film A when water is injected into the concave surface on which the water-stopping film A is formed. FIG. 3 is a state diagram showing changes in a water-stop film over time.

The waterproof membrane A is composed of a first waterproof membrane (1) and a second waterproof membrane (2), and its molecular size is approximately 0.3 to 1 μm, which has better permeability than cement and aggregate in the emulsion mixture. A large amount of emulsion P of ethylene-vinyl acetate copolymer permeates to form a second waterproofing film, and on top of that, a first waterproofing film containing more aggregates such as cement and silica sand than the emulsion of ethylene-vinyl acetate copolymer. A film is formed.

When water W is poured into the concave surface having the water-stop film A made up of the first waterproof film 1 and the second waterproof film 2, the first waterproof film 1 swells slightly due to water penetration, as shown in Fig. 2. However, since the amount of the emulsion that swells when it attracts dark water into the first waterproof membrane 1 is small, the water penetrates further into the second waterproof membrane 2.
reach.

In this second waterproof membrane 2, a large amount of emulsion in the membrane attracts a large amount of permeated water, absorbs water, and swells. As a result, the molecular diameter of the emulsion y increases from 0.3 to 1 μ to 1 to 3 μ. Moreover, as shown in Figure 2, the molecules intersect with each other, making it possible to form a more complete water-stop film A.

In addition, the blending ratio as an emulsion mixture is such that the emulsion of ethylene-vinyl acetate copolymer has a total solid content of 2 to 2.
10%, inorganic substances 6-30%, cellulose derivative substances o,
oi ~ 0.03φ is appropriate, and among the inorganic substances, Portland cement and other silica sand, natural pumice, slag, and other aggregates with high compressive strength are poured at a ratio of 1:1 to 20 depending on the condition of the soil. The decision should be taken into consideration.

The present invention will be explained in detail below with reference to Examples.

Example 80 parts of ethylene-vinyl acetate copolymer resin (concentration of 50 parts) 23 23 672 000 Carboxycellulose Portland cement silica Sand water Mix the ethylene-vinyl acetate copolymer resin, carboxycellulose, and water, and pour into the mixture. A cement paste-like emulsion mixture was prepared by adding Portland cement buttons and silica sand. This was poured into the collected earth and sand using a beaker and left to dry overnight.

When water was poured over the earth and sand into which this water-stopping film-forming emulsion mixture had been poured, the degree of reduction was observed.
At first, the water permeated into the soil, but once the permeated water reached the water-stop film containing a high emulsion content of ethylene-vinyl acetate copolymer, no reduction in water was observed due to subsequent permeation.

From this, it was demonstrated that the emulsion in the water-stop membrane, especially in the second waterproof mask, swells with water and becomes a dense membrane, completely suppressing subsequent water permeation.

[Brief explanation of the drawing]

Figure 1 is a state diagram of a water-stop film obtained by the method of the present invention in which a paste-like emulsion mixture is poured into soil and dried. FIG. 3 is a state diagram showing changes in a water film.

Claims (1)

[Claims] 1. Drilling an emulsion mixture in which a large amount of emulsion hydrate is produced by adding a cellulose derivative substance and one or more inorganic substances such as Portland cement, bentonite, or silica sand to an ethylene-vinyl acetate copolymer emulsion. 1. A method for forming a water stop film in a concave surface of an excavated pond, the method comprising infiltrating the concave surface of the peripheral wall and/or bottom of the pond to a predetermined depth.