JPS645131B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for preventing collapse of the earth's surface. Conventionally, the so-called mortar spraying method has been generally used as the only method for protecting steeply sloped surfaces. This method generally involves scraping away the surface soil of a dangerous slope to expose a safe rock surface, covering it with a wire mesh fixed with anchor pins, and then applying a thick layer of mortar (usually 3 Although it is a highly effective and reliable construction method, it has the disadvantage of requiring large-scale equipment, specialized technology, and enormous costs. In contrast, the present invention provides a method for strengthening sloped ground surfaces using simple equipment and techniques and at low cost. That is, the present invention relates to a simple method for preventing collapse of a slope surface, in which a ground surface strengthening liquid made by mixing and dispersing Portland cement and a fiber material in a synthetic resin aqueous emulsion is uniformly spread over the slope surface to strengthen the surface. The collapse of sloped land surfaces occurs due to raindrops and running water washing away from the surface, internal fluidization due to seepage water, and slippage, and the present invention was arrived at as a result of intensive research on methods to prevent this.
In particular, the method of the present invention can be constructed without having to scrape off the low-strength surface soil in advance, unlike the mortar spraying method, and in addition, it can be constructed in locations that cannot be easily accessed by people. Of course, it is possible to strengthen the ground surface from a distance by spraying it in the form of raindrops by force-feeding, but it is also possible to put the ground surface strengthening liquid in a spraying bucket and transport it by helicopter to a distant slope, where it can be uniformly sprayed. It also has the advantage of being able to strengthen the ground surface. The key point of the present invention is that unlike methods such as mortar spraying, which firmly fix heavy and thick protective walls to the ground, it is possible to create a cement hardened layer that is lightweight, hard, and highly water resistant and can be applied over a wide area. The purpose is to firmly adhere to the surface of slopes that are at risk of collapse. In order to uniformly adhere and coat the ground surface, it is necessary to spray an appropriate amount of liquid with an appropriate viscosity, appropriate solid content, and appropriate adhesion performance using an appropriate method. For that purpose, 3 to 30% of synthetic resin emulsion is required.
A fixing solution is used in which 0.5 to 5 kg of % aqueous solution is added with Portland cement in an amount of 1 to 50 times the solid content of the synthetic resin and 5% by weight of fiber material or less of the cement. Water can be added. Synthetic resin emulsion penetrates into the slope surface and dramatically improves the adhesive strength of the fixed layer. It also supports the hydration hardening of cement, prevents dryout, and gives cement toughness, water resistance, and durability after hardening. Grant. Synthetic resin emulsions suitable for this purpose are not particularly limited, but they only need to have excellent miscibility with cement, do not excessively delay the hydration hardening reaction of cement, and have excellent water resistance and adhesive properties. Examples include styrene, acrylic, vinyl acetate, ethylene, vinyl acetate, beoba, SBR, MBR, vinyl chloride, and vinylidene chloride. Further, these may be used alone or in combination of two or more. If the spraying amount is less than 0.5 kg/m ² , uniform spraying is difficult and less effective, and if it exceeds 5 kg/m ² , a large amount will flow down and be lost on the slope surface, making it uneconomical. If the solid content of the synthetic resin emulsion is less than 3, the solution viscosity will be low, it will be easy to atomize (make into raindrops) during spraying, and it will penetrate well into the ground, but the fixing effect will be insufficient. Furthermore, if the solid content exceeds 30%, the viscosity of the solution becomes too high, making it difficult to atomize during spraying. The performance of Portland cement after hydration hardening is already well known, and there is no need to add any special explanation, but the feature of the present invention is that the cement is used alone without mixing sand, which separates and settles quickly in an aqueous solution. be. The shrinkage cracks that occur after curing when sand is not used in combination are almost completely eliminated by the addition of the aforementioned synthetic resin emulsion. Regarding the amount of spraying, if the ratio of solid content in the synthetic resin emulsion to cement is less than 1:1, the fixing force will be low, and if the ratio is more than 1:50, the viscosity of the mixed liquid will increase, making it difficult to pump and atomize the powder. As the dust becomes stiffer, the flow down the slope during spraying increases, which becomes uneconomical. Furthermore, since cement has a high specific gravity, it is expected that it will settle quickly.
Within the scope of the present invention, if very light stirring was continued in the mixing tank, sedimentation did not occur, and this did not pose any practical problems. Fiber substances are effective in preventing cracking and improving tensile strength of hard cement hardened products, and are particularly effective in the case of a thin hardened cement layer as in the present invention. The length of the fiber material used in the present invention is
Wood pulp, synthetic fibers within the range of 0.3 to 20 mm,
Linen, asbestos, rock wool, and glass fiber are suitable.
If it is less than 0.3 mm, the effect of preventing cracks will be low, and if it exceeds 20 mm, it will be difficult to pump it, and the atomization of the sprayed liquid will be uneven, making it impossible to achieve the desired purpose.
If the amount of fibrous material added is more than 5% based on the cement, the workability of liquid feeding and dispersion will deteriorate and the strength of the cement after hardening will be reduced. Hereinafter, the present invention will be specifically explained with reference to Examples, but the present invention is not limited to these Examples. Examples 1 to 24 Synthetic resin emulsion (trade name, Toughtac
200, a product of Sanyo Kokusaku Pulp Co., Ltd.), hardwood kraft pulp (average fiber length 1.0 mm) and ordinary Portland cement were added and dispersed to a soft volcanic ash stratum containing a large amount of small-diameter pumice, at a slope of 60° and a height.
It was pumped onto a 15m slope and sprayed in the form of raindrops from the ground using a spray nozzle. As a result, both coated the ground surface uniformly and had excellent surface strength and water resistance.

【table】

[Table] Example 25 Product name: Toughtac 200 water diluted liquid (solid content concentration: 10
%) 2Kg, cement 3Kg and nylon fiber (fiber length
10mm) linen (fiber length 15mm), asbestos (Canadian standard,
black type), rock wool (fiber length 10 mm), or glass fiber (fiber length 15 mm) respectively to cement 1
% of the aqueous solution was sprinkled on a sandy riverbed (area: 1 m ² ) to harden the surface. The surface hardness 10 days after spraying is shown in the table below.

[Table] Reference: Before strengthening the test ground surface
Hardness 5
Example 26 Testing was carried out on the same sloped surface under the conditions of Example 15, with only the pulp addition rate changed to 0%, 0.5%, 2%, and 4% relative to cement.

[Table] Note: Cracks...When the ground surface is hit with a hammer
The crack spreads around the dot.
Example 27 Under the conditions of Example 11, the product name and Toughtack were
The test was carried out by replacing 200 with the product name Hiflex 1000 (vinyl acetate/ethylene based, manufactured by Nippon Kasei Co., Ltd.) and the product name JSR670 (synthetic rubber latex, manufactured by Nippon Synthetic Rubber Co., Ltd.).

[Table] Example 28 Emulsion, cement, with the mixing ratio of Example 11
The fibrous substance mixture was placed in a portable bucket equipped with a conical, vertically movable discharge port on the bottom and lifted by a helicopter, and was transported horizontally at 10km/h at a height of 20m above the ground.
When the bottom of the bucket was opened while moving at a speed of Comparative Examples 1 to 6 and Reference Examples Tests were conducted using the formulations shown in the table below using the same location and method as in the examples.

[Table] *marked: Comparative example where cracks occur all the way to the periphery during hardness measurement 7 Mortar mixed with 18% cement, 74% sand, and 10% water (all percentages by weight) was prepared using a mortar spray gun in the same manner as in Examples 1 to 24. While supporting the body with a lifeline, the spray was applied to the ground surface under certain conditions until it reached a thickness of 10 cm. As a result, when a worker walked along the slope with a heavy hose and spray gun, the slope partially collapsed, and when the mortar layer reached 10 cm thick, it began to slide down the ground surface.

Claims (1)

[Scope of Claims] 1. A method for preventing ground surface collapse, which comprises mixing and dispersing Portland cement and fibrous material in a synthetic resin aqueous emulsion and spraying the mixture on the ground surface to strengthen the ground surface. 2. The method for preventing ground surface collapse according to claim 1, wherein Portland cement is sprinkled in an amount of 1 to 50 times the amount of solid synthetic resin per 1 m ² of land area. 3. The method for preventing ground surface collapse according to claim 1 or 2, wherein the fibrous material has a length of 0.3 to 20 mm and is added in an amount of 5% by weight or less of the cement. 4 Synthetic resin aqueous emulsion with a solid content of 3 to 30%
The method for preventing ground surface collapse according to claim ¹ , wherein 0.5 to 5 kg per square meter is sprayed as an aqueous solution. 5. The method for preventing ground surface collapse according to any one of claims 1 to 3, wherein the fibrous material is wood pulp. 6. The method for preventing ground surface collapse according to any one of claims 1 to 3, wherein the fibrous material is a synthetic fiber. 7 Claim 1 in which the fibrous material is hemp
The method for preventing ground surface collapse according to any one of Items 1 to 3. 8. The method for preventing ground surface collapse according to any one of claims 1 to 3, wherein the fibrous material is asbestos. 9. The method for preventing ground surface collapse according to any one of claims 1 to 3, wherein the fibrous material is rock wool. 10. The method for preventing ground surface collapse according to any one of claims 1 to 3, wherein the fibrous material is glass fiber. 11. The fabric according to any one of claims 1 to 3, wherein the fibrous material is a mixture of two or more of wood pulp, synthetic fiber, hemp, asbestos, rock wool, and glass fiber. Method for preventing surface collapse.