JP4703428B2 - How to prevent red soil runoff - Google Patents

Description

  The present invention relates to a method for preventing the outflow of soil containing red soil, and more particularly to a method for provisional prevention and permanent prevention (greening) of red soil outflow.

  In recent years, with the development of golf courses in the forests and wilderness, road construction, land improvement, etc., the topsoil flows out from the bare land of those sites during heavy rains, polluting rivers and seas, and a society with great environmental destruction It is a problem. In particular, in the Okinawa region, there is a problem that acidic topsoil called red soil flows into the sea to such an extent that the coast is dyed red and has a great impact on marine organisms. .

  Conventionally, various methods have been taken to prevent red soil spills. For example, a red soil sedimentation basin (sedimentation basin) was provided at the terminal treatment plant, and red soil particles were sedimented. In heavy rain, settling was not in time and was not effective. Patent Document 1 proposes a retaining wall for preventing red soil outflow, but there is a problem that it cannot cope with instantaneous heavy rain and heavy flooding.

In order to make the red soil itself difficult to flow out, Patent Document 2 proposes a method in which a soil hardening agent and soil are mixed with water to form a slurry and sprayed on the soil surface. Although the outflow of fine particles can be kept, there are problems such as low outflow prevention effect during heavy rain and high processing costs.
Patent Document 3 proposes a sheet made of natural fibers covering the surface of the red soil layer, but it requires a thick sheet and has problems such as insufficient fixation during heavy rain.

In addition, there are provisional measures to temporarily prevent sediment runoff and permanent measures, including greening measures, to prevent red soil runoff. Temporary measures include non-biodegradable blue sheets, emulsifier spraying, and aggregates. Chemical spraying is used and vegetation is widely used as a permanent measure, but no effective method has been known to satisfy both the temporary measure and the permanent measure at the same time.
JP 2004-116141 A Japanese Patent Laid-Open No. 4-203003 JP 2000-31890 A

  The problem of the present invention is that it can maintain the red soil runoff prevention effect even under severe weather conditions such as heavy rain and heavy flooding, solve the problems of economic efficiency and workability, and implement permanent measures including greening. It is to provide a red soil runoff prevention method.

  In order to solve the above-mentioned problems, the inventor of the present invention significantly improves the prevention of red soil outflow by combining a sheet having water absorption and breathability within a specific range and an aggregating agent. As a result, the present invention has been completed.

That is, the invention claimed in the present application is as follows.
(1) At least 50% by weight of regenerated cellulose fiber having a water absorption of 1 to 15 times its own weight, an air permeability of 100 to 1000 cc / cm ² · sec, and a basis weight of 10 to 100 g / m ² in soil containing red soil After laying the non-woven fabric containing the above , a red soil spill prevention method characterized by having a step of spraying the aggregating agent,
(2) The method according to ( 1 ), wherein the aggregating agent is sprayed in a range of 5 to 50 g / m ² .
(3) The method according to (1) or (2) , wherein plant seeds or seedlings are sown in advance in soil containing red soil,
(4) The method according to (1) or (2) that the nonwoven fabric is a nonwoven fabric of seeds and / or seedlings with,
(5) The method according to any one of (1) to (4) , wherein the nonwoven fabric is a nonwoven fabric made of regenerated cellulose long fibers.

  ADVANTAGE OF THE INVENTION According to this invention, the efficient red soil outflow prevention method which can perform a temporary countermeasure and a permanent countermeasure simultaneously by one construction is provided. In particular, the present invention has good adhesion to the red soil surface of the water-absorbing sheet during water spraying, and the interaction is exhibited by combining the sheet and the aggregated material, for example, rapid sediment during heavy rain. Great effect on erosion and outflow.

Hereinafter, the present invention will be specifically described.
FIG. 1 is an explanatory diagram showing an embodiment of the present invention in which the present invention is applied to a soil slope where there is a risk of outflow of red soil. In the figure, 1 is a red soil soil slope, 2 is the nonwoven fabric sheet of this invention laid on it.

  The sheet 2 used in the present invention is required to have water absorption and breathability, and examples thereof include non-woven fabrics, woven fabrics, knitted fabrics or paper, felts, etc., but flexibility, durability, workability, economy, etc. From the viewpoint of properties, nonwoven fabrics are preferred.

  The degree of water absorption is preferably in the range of 1 to 15 times its own weight, more preferably 5 to 13 times in terms of water absorption. When the water absorption ratio is within this range, the sheet absorbs sufficient moisture, and the weight of the moisture allows the sheet to be laid on the surface of the red soil without any gaps, significantly improving the adhesion and covering of the sheet to the soil. To do.

  The sheet preferably has an appropriate aperture, and in order for the aggregating agent to permeate the sheet and reach the red clay surface, the diameter of the perforated hole is preferably in the range of 0.1 to 5 mm, more preferably 0. The range is 5 to 3 mm. This is preferable because rainwater necessary for germination and growth of seeds permeates the sheet when the sheet is laid after seeding on red soil, or when a sheet with seeds is laid. Non-porous and non-permeable sheets of resin sheets typified by blue sheets are inappropriate because the aggregating agent cannot reach the soil.

The air permeability is preferably in the range of 100 to 1000 cc / cm ² · sec, more preferably in the range of 100 to 400 cc / m ² · sec, as measured by the Frazier method. Air permeability within this range is preferable from the viewpoint of vegetation.

  The water absorption is preferably 1 to 15 times, more preferably 5 to 13 times the own weight. When the water absorption is within this range, the sheet has excellent water absorption and water retention characteristics, and the aggregating agent is quickly absorbed by the sheet, and then can reach the red clay surface uniformly and smoothly.

  The fiber material constituting the sheet is preferably a biodegradable fiber, for example, an aliphatic polyester fiber typified by polylactic acid, or a cellulose fiber, such as cotton, hemp, coconut fiber, straw, pulp, rayon, cupra fiber, Examples include lyocell fiber. From the viewpoints of biodegradability, water absorption, water retention, flexibility, and the like, regenerated cellulose fiber rayon, cupra fiber, and lyocell fiber are more preferable.

  Cellulose fibers are preferably contained in the sheet at least 30% by weight or more, more preferably 50% by weight or more, and most preferably 100% by weight. When the cellulose fiber content is less than 30% by weight, the water absorption ratio is low, the adhesion to the soil is weak, and the effect of preventing instantaneous soil outflow is weakened.

As the non-woven fabric, a cellulose long fiber non-woven fabric, particularly a regenerated cellulose fiber non-woven fabric is preferable, and a cupra long fiber non-woven fabric is most preferable from the viewpoints of biodegradability, flexibility, workability, particularly the followability of the non-woven fabric to the red land surface, and stickability. . The range of the basis weight of the sheet is preferably 10 to 100 g / m ² , more preferably 20 to 70 g / m ² . Cellulose-based long-fiber nonwoven fabric has the effect of following and sticking to the ground surface, and it adheres to the ground due to its erosion-preventing effect, problems of restraining such as skewers and sandbags, and the property of being decomposed by bacteria in the soil. Therefore, the decomposition is quick and preferable in relation to the timing of seed germination.

  In particular, the regenerated cellulose fiber nonwoven fabric is particularly preferable because the fiber itself has high water absorption characteristics, has high water swellability, and the fiber itself absorbs water and at the same time easily absorbs water into the fiber gaps of the nonwoven fabric. In addition, when wet, the rigidity is extremely reduced, there is no stiffness, and even with slight irregularities on the soil surface, the curved surface followability is excellent, and the so-called adhesion performance to the soil surface is also excellent. A cupro nonwoven fabric (registered trademark, manufactured by Bennett Asahi Kasei Fibers), which is a regenerated cellulose long fiber, has high water absorption characteristics, high water swellability, and sufficiently absorbs water into the fiber gaps of the nonwoven fabric. There are about 13 times its own weight. After laying the cupra nonwoven fabric as a sheet, when the aggregating agent is diluted in water and sprayed, the cupra nonwoven fabric absorbs at the same time as spraying, the nonwoven fabric becomes transparent and can adhere to the soil surface and spread. The degree can be grasped instantly and it is excellent in terms of handling in construction.

  The aggregating agent used in the present invention may be spread after laying the sheet, or may be spread before laying the sheet, but it is possible to spread after laying the sheet. From the viewpoint of enhancing the synergistic effect with the agent. By spreading after laying the sheet, the adhesion between the sheet and the ground is further increased.

The application amount of the aggregating agent is preferably in the range of 5 to 50 g / m ² , more preferably in the range of 10 to 30 g / m ² . As for the volume of the soil, it is preferable to add an aggregating agent at a rate of 2 to 4 liters per 1 m ³ of the soil, and it is preferable to dilute with water about 100 times and spray.

  Aggregating agent refers to an additive that promotes the formation and maintenance of soil aggregates. For example, a polymer composed of a composite of Mg salt of acrylic acid / dimethylaminoethyl methacrylate copolymer and polyethyleneimine. Compounds etc. are used. The aggregating agent can be used by being previously mixed with soil and / or water and uniformly kneaded with a mixer or the like. As a specific aggregating agent, “Grand CTS” or “Grand PG” (manufactured by Omotogumi Co., Ltd., trade name), “EMN Coat 21” (product name of Hiranaka Co., Ltd.), etc. .

  The aggregating agent is composed of a polymer compound in which each molecule has a strong positive charge, and when it is mixed in the soil, it instantaneously binds to the soil having a negative charge opposite to that of the aggregating agent. Soil particles combine to form large aggregates (aggregates). Further, these aggregates are connected and crosslinked to form a three-dimensional network structure. The three-dimensional network structure formed in this way has excellent strength, stability, durability and durability, and also has high liquid permeability, water retention and air permeability, and inhibits plant germination and vegetation. Without having an effect of promoting.

  The sheet used in the present invention has a high water absorption ratio, excellent liquid absorbency, and extremely excellent curved surface followability and curved surface coverage when wet. As a result, by using this sheet, it is possible to attach the sheet tightly to the soil surface without a gap with respect to the uneven surface of the red soil as shown in FIG. Further, by spraying the aggregating agent through the sheet, the aggregating agent enters in two stages. That is, by first infiltrating the sheet into the sheet and then entering the soil surface, the aggregating agent can evenly enter even the slight uneven gaps on the soil surface. It can penetrate into the soil without any gaps. Due to the action of the aggregating agent, the soil and the aggregating agent are combined to form a three-dimensional network structure, and the sheet is closely adhered to the aggregated aggregate without any gaps. The soil and the sheet are integrated. Further, the sheet itself is partially integrated with the three-dimensional network structure, and the sheet itself is partially incorporated into the three-dimensional network structure. For this reason, the sheet is in close contact with the soil surface without any gaps against the anticipated rapid soil surface runoff, especially during heavy rains, so that the action of preventing the soil movement and runoff is greatly enhanced.

  It is possible to agglomerate fine particles in the soil and keep the runoff even with the aggregating agent alone, but in the event of heavy rain, a large amount of rapid erosion (erosion) on the soil surface It is difficult to prevent. However, when the sheet and the aggregating agent are combined as in the present invention, these synergistic effects can suppress the erosion of the sheet from the soil surface and reduce the amount of eroded red soil flowing into the river and sea. it can. In the case of a sheet alone, there is an effect in preventing surface erosion, but there is a limit in keeping out fine particles from flowing out. In the case of single use of the sheet, the integrated bonding effect with the aggregating agent is not expected, the soil surface having a lot of fine particles that easily flow out, it is easy to flow, and there may be cases where sufficient adhesion with the ground cannot be secured, There is a limit to the effect of preventing the outflow, and there arises a problem that many tools for fixing the sheet such as a skewer and a sandbag are required.

  In the present invention, after seeds are sown in red soil in advance, a sheet is laid and then an aggregating agent is applied, or a sheet pre-applied with seeds and / or seedlings is laid, and then aggregated In the case where the agent is applied, it is possible to expect the growth effect as a temporary measure until seed germination and covering, and further, the anti-runoff effect due to the vegetation effect is expected, and the temporary measure and permanent measure can be performed at once. . In addition, it saves the labor of construction and can be said to be advantageous in terms of cost.

  When a biodegradable sheet is used, after sowing or when a seed-integrated sheet is used, it is not necessary to peel off the sheet after germination and growth, and labor and costs can be saved. Compared to synthetic fibers that do not decompose for a long time, biodegradation is advantageous in terms of environmental load and aesthetics. Furthermore, when the sheet | seat containing a cellulose fiber is used, since the water | moisture content required for germination can be hold | maintained, a germination rate can be improved.

The present invention will be described based on examples. The measurement methods used in the examples are as follows.
1. Breathability: According to the fragile method according to JIS-L-1906.
2. Water absorption rate The water absorption rate in the present invention means that the sample was left standing at 20 ± 2 ° C. and 65 ± 2% RH for 16 hours or longer and the weight of the sample sampled to 10 cm × 10 cm was measured (W1), and the water was sufficiently filled. After immersing the sample in the pad for 10 minutes, taking it out and letting it drop from the sample until the drop of water drops, measure the weight of the sample (W2), and mean the water absorption magnification indicated by (W2-W1) / W1 To do.

3. Calculate the average value by measuring the four corners and the center of the sheet sample of 1m × 1m.
4. Single yarn decitex: The constituent single yarn is enlarged and calculated as dtex.
5. WET peeling strength After cutting the sheet sample into 1 m (vertical) x 1 m (wide), it is moistened with water 100 times the weight of the sample. Next, after sticking a sheet sample on the red soil surface, a hook is put on the center of the sample, and a peel strength value (N) when the sample is pulled 5 cm in a direction perpendicular to the sample is measured.

6. WET initial adhesion Adhesiveness when wetted with water 100 times the weight of the sheet sample and then attached to a coating (red soil: the difference in height between the concave and convex portions is less than 3 cm) Was determined as follows.
A: Very good.
○: Excellent.
X: unsuitable.

7. Sticking retention property A sheet of 1 m in length and 1 m in width is moistened with water 100 times the weight of the sheet. Next, the sheet sample was left to dry overnight under no wind, and then the peelability of the sample was judged as follows when a wind of 10 m / sec was applied from the side to the sample for 30 seconds.
(Double-circle): It does not peel.
○: Partially peeled off.
X: Completely peeled off and scattered.

[Example 1]
A regenerated cellulose continuous long-fiber nonwoven fabric (Bennet (registered trademark), manufactured by Asahi Kasei Fibers Co., Ltd.) having an average basis weight of 23 g / m ² and a single yarn decitex of 1.4 dtex was prepared as a sheet for preventing red soil outflow (long). 300m, width 1.8m). The air permeability was 350 cc / cm ² · sec, and the water absorption ratio was 13 times. The red soil spill prevention test was conducted under the following conditions.

(1) Location: Red soil in Izumi, Motobu, Okinawa Prefecture was used as the red soil slope.
(2) Laying on the slope of the sheet: As shown in FIG. 1, the non-woven fabric of the present invention (bennet having a width of 1.8 m) rolled on a red clay slope of two stages is laid (width 10 m). , 30 m long).
(3) Dispersion of the aggregating agent: As the aggregating agent, trade names “Grand CTS” and “Grand PG” manufactured by Omotogumi Co., Ltd. were mixed in half and diluted to a 1% by weight aqueous solution. In the shower, the aqueous solution was sprayed at 3 liter / m ² (corresponding to 100 times its own weight). The application amount of the aggregating agent was 30 g / m ² .

  The nonwoven fabric of the present invention was able to adhere and coat very well against the irregularities on the surface of the red soil, and it was easy to work and could be laid very well.

Next, separately prepare a sheet of 1 m ² in size, perform the same treatment, hook a hook at the center, and use a spring balance to keep the nonwoven fabric peeled off from the red soil surface in a direction perpendicular to the sample. Pulled up. As a result, it was confirmed that the initial adhesion was very good (evaluation ◎).

Next, a hook was hooked on the center of the sheet, and the sheet was pulled vertically with respect to the sample until the sheet peeled off from the red soil surface to a height of 5 cm using a spring balance. As a result, the WET peel strength was a value of 1.0 N / m ² , and it was confirmed that the film has extremely good sticking properties.

Further, when the sheet after spraying with water was left to dry overnight, the sheet maintained extremely good stickiness (evaluation）) even when 30 seconds of wind at a wind speed of 10 m / sec was applied from the lateral direction.
(4) One day after spraying the agglomerating agent, water equivalent to 100 mm / hour is poured from the upper part of the red soil slope as rain of a large typhoon, and the runoff state of the red soil slope is visually observed. I observed it.

  As a result, when covered with the sheet of Example 1, runoff of the red soil was very slight, and there was almost no problem level. It was found that the sheet remained in close contact with the slope of the red soil so that the red soil was protected by the sheet and the outflow of the red soil was completely prevented.

  In the above test, as Comparative Example 1, without using a sheet, only the aggregating agent was used, and when other conditions were the same as in Example 1, there was an agglomeration effect of red soil, Under the conditions corresponding to the amount of rainfall (100 mm / hour) that is equivalent to that of a large typhoon, red soil runoff was observed, and sufficient runoff prevention effects could not be obtained.

  INDUSTRIAL APPLICABILITY The present invention can be expected to have an excellent red soil runoff prevention effect by a simple and economical construction method against sudden red soil erosion and runoff during heavy rain, and can be effectively used for red soil runoff prevention measures mainly in Okinawa Prefecture. .

Explanatory drawing which shows one Example of this invention which applied this invention to the soil slope which may run out of red soil.

Explanation of symbols

  1: Red soil soil slope, 2: Non-woven fabric sheet of the present invention.

Claims (5)

Nonwoven fabric containing at least 50% by weight or more of regenerated cellulose fiber having a water absorption of 1 to 15 times its own weight, an air permeability of 100 to 1000 cc / cm ² · sec, and a basis weight of 10 to 100 g / m ² in soil containing red soil A method for preventing red soil spillage, characterized by having a step of spraying an aggregating agent after laying . The method according to claim 1, characterized in that spraying the group grain agent in the range of 5 to 50 g / m ^2. The method according to claim 1 or 2 , wherein plant seeds or seedlings are sown in advance in soil containing red soil. The method according to claim 1 or 2, wherein the nonwoven fabric is a seed and / or seedlings with the nonwoven fabric. The nonwoven fabric A method according to any one of claims 1 to 4, characterized in that a nonwoven fabric made of regenerated cellulose filaments.

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