JP7476459B2 - Waterside slope construction method - Google Patents

Description

The present invention relates to a method for constructing slopes in waterfront areas such as dams, reservoirs, flood control basins, levees, and irrigation channels.

In general, the slopes around the perimeter of a dam lake are prone to instability due to the harsh environment in which they are repeatedly flooded and exposed, and there are concerns that the collapse of the slopes could lead to soil inflow into the dam lake, the occurrence of tsunamis within the dam lake, and a shortening of the dam's lifespan. To prevent the slopes from collapsing, attempts have been made to stabilize the slopes by planting greenery, but the conventional methods of constructing slopes using concrete and gabions make it difficult for plants to take root, making greenery difficult.
In response to this, a method has been proposed in which soil material made by mixing cement, soil, chemical fertilizer, etc. is sprayed onto the slope (Patent Document 1), but this method has difficulty in achieving good plant growth due to the high alkalinity derived from the cement. In addition, a method has been proposed in which fresh water is supplied from the upstream side of the slope to create rich vegetation, and a method has been proposed in which seeds are sowed on vegetation sheets, but because the slopes around the dam lake are steep, the seeds are easily washed away by rainfall or water level fluctuations, making it difficult to achieve greening, and other effective methods have been desired.

JP 2005-155159 A

The objective of the present invention is to provide a waterside slope construction method that is easy to carry out on-site, allows planted seeds to grow well without being washed away, and does not deteriorate water quality.

The means for solving the problems of the present invention are as follows.
1. A process of covering a slope at a waterside with a first paste material including a granular base material, a polymer-based solidifying material, and a hydrophilic polymer, and forming a groove extending in a substantially horizontal direction on the surface;
A step of covering the solidified soil obtained by solidifying the first paste material with a second paste material containing a granular base material, a polymer-based solidification material, a hydrophilic polymer, and an aqueous plant seed;
A waterside slope construction method comprising the steps of:
2. The waterside slope construction method according to 1., wherein the first paste material contains pumice in a volume ratio of 30% or more to the total amount of the granular base material.
3. The waterside slope construction method according to 1. or 2., characterized in that the first paste material contains 0.5 v/v % or more more polymer-based solidification material relative to the granular base material than the second paste material.
4. The waterside slope construction method according to any one of 1. to 3., characterized in that the second paste material contains a hydrophilic polymer 0.05 w/v % or more more relative to the granular base material compared to the first paste material.
5. The waterside slope construction method according to any one of 1. to 4., wherein the second paste material contains an inorganic ion adsorbing/desorbing material.

In the waterside slope construction method of the present invention, the second paste material covering the surface contains the seeds of water-based plants, and the water-based seeds are sown at a shallow position, so the rate at which the seeds sprout is high, and the time until greening and the establishment of an ecosystem can be shortened. In the waterside slope construction method of the present invention, the solidified soil covered with the second paste material containing the seeds of water-based plants has grooves formed on its surface, so that the soil and seeds can be prevented from flowing out even on steep slopes. In addition, the waterside slope construction method of the present invention is also expected to be carried out on steep slopes, but since the solidified soil made of the first paste material has grooves extending in a substantially horizontal direction, it is excellent in safety and workability for workers when covering with the second paste material. The waterside slope construction method of the present invention can be carried out simply by covering with the paste mixed on site, so that construction of a large area such as the slope of a dam can be easily carried out. Therefore, the waterside slope construction method of the present invention can be suitably applied to civil engineering sites.

The method of constructing a waterside slope at a civil engineering site of the present invention, in which the first paste material contains 30% or more pumice by volume relative to the total amount of the granular base material, is able to retain water in the pores of the pumice even in an environment with poor water retention such as a steep slope, so that aquatic plants are less likely to wither. In addition, by adjusting the composition of the first and second paste materials and forming the solidified soil made of the first paste material to be hard and the layer made of the second paste material to be soft and contain many gaps, it is possible to firmly cover the slope and create an environment in which aquatic plants can easily grow. The upper layer made of the second paste material contains an inorganic ion adsorbent/desorbent as part of the granular base material, which promotes the initial growth of aquatic plants, shortens the period when they are weak in resistance and prone to withering, and increases the success rate of greening.

4A to 4C are diagrams illustrating the steps of the waterside slope construction method of the present invention. Graph showing the change in soil runoff amount over time in Experiment 1. Graph of germination number in experiment 2.

The present invention relates to a waterside slope construction method for dams, reservoirs, retarding basins, levees, irrigation channels, etc., and more particularly to a waterside slope construction method at civil engineering sites.
In the present invention, the term "waterside" refers to an area where aquatic plants grow. The present invention relates to a method for constructing a waterside slope, and for example, the water level of a dam changes on the scale of several tens of meters. Therefore, the waterside of the present invention includes places that are normally submerged and places that are underwater only when the water level rises.

The steps of the waterside slope construction method of the present invention will be described with reference to FIG.
In the present invention, the term "slope" refers to an inclined surface that is artificially constructed by cutting and filling the earth, a naturally formed inclined surface, etc. The range of the slope gradient (ratio of the horizontal length to the height of the slope) of the slope to which the present invention can be applied is not particularly limited, but the lower limit is at least smaller than 0.58 (angle larger than 60 degrees).

First, a slope at a waterside (FIG. 1A) is coated with a first paste material 1 containing a granular base material, a polymer-based solidifying material, and a hydrophilic polymer (FIG. 1B).
The coating thickness of the first paste material 1 is not particularly limited as long as it is within a range that allows a solidified soil to be constructed on the slope, but is usually about 3 cm to 20 cm.

Before the first paste material 1 solidifies, grooves 11 extending in a substantially horizontal direction are formed (FIG. 1C).
In the present invention, the substantially horizontal direction in which the grooves extend is not horizontal in the strict sense, but varies depending on the site environment (slope inclination, unevenness, etc.), and is usually within a range of about ±30° from the horizontal direction. The interval and depth of the grooves are not particularly limited, and for example, the interval can be about 3 to 30 cm, and the depth can be about 0.5 to 3 cm. In addition, the method of forming the grooves is not particularly limited, and for example, a method of scraping the surface with a rake can be mentioned.

Next, the solidified soil formed by the solidification of the first paste material is covered with the second paste material 2 containing a granular base material, a polymeric solidification material, a hydrophilic polymer, and a water-soluble plant seed (FIG. 1D). The first paste material solidifies overnight on a fine day, and in about two days on a cloudy day.
The solidified soil formed by solidifying the first paste material is used to cover the slope and may be constructed on a steep slope, but since the grooves 11 are formed on the solidified soil surface, workers can be prevented from slipping during the work of covering with the second paste material, improving safety and workability. In addition, the grooves 11 prevent the second paste material 2 from flowing and sliding down.
The thickness of the second paste material 2 is not particularly limited as long as it is a thickness that allows the seeds of aquatic plants to easily germinate, but is usually about 3 cm or less, and preferably 2 cm or less. Since the second paste material is located only in the surface layer, when the seeds of aquatic plants sprout, most of them reach the ground surface, and the amount of the seeds that are wasted can be reduced.

The first paste material contains a granular base material, a polymer-based solidifying material, and a hydrophilic polymer, and the second paste material contains these as well as an aquatic plant resin. The granular base material, polymer-based solidifying material, and hydrophilic polymer shown below can be used, and the first and second paste materials can be the same or different.

"Granular base material"
Granular base material is the main component of the solidified soil that covers the slope.
Examples of granular base materials include natural materials such as soil, sand (river sand, etc.), gravel, and pumice (Kanuma soil, Hyuga soil, etc.), planting base materials processed from volcanic rocks such as perlite, artificial materials such as molten slag derived from waste polystyrene foam, construction waste, and sewage sludge, and inorganic ion adsorbent/desorbent materials, and one or more of these can be used. However, since soil contains a lot of nutrients and these nutrients may run off and cause environmental load, the volume ratio of soil to the entire granular base material is preferably 10% or less, more preferably 5% or less, and most preferably does not contain soil. In the present invention, soil means an organic matter content of 10 wt% or more, and the organic matter content in soil means the weight loss amount after the soil is baked at 600 degrees after being completely dried.

The particle size of the granular base material is not particularly specified, but it is preferable that the particle size is equivalent to that of sand (particle size 0.074 mm to 2 mm) and fine gravel (particle size 2 to 4 mm). For example, fine sand (particle size 0.075 to 0.25 mm), medium sand (particle size 0.25 to 0.85 mm), and pumice (a representative example is Kanuma soil) with a particle size of 4 mm or less are preferable. Furthermore, materials with a narrow particle size distribution are preferable. With a narrow particle size distribution, small particles are not filled in the gaps between the particles, making it easier to adjust the three-phase distribution of solid, liquid, and gas within a preferable range.
As the granular base material, it is preferable to use a combination of sand and pumice because the particle size distribution is easy to control and the cost is low. In particular, pumice can hold water inside its pores, so that it can form solidified soil with excellent water retention even on sites with too good drainage such as steep slopes. In addition, aquatic plants can easily take root in the pores of the pumice and the gaps between the pumice, which prevents the aquatic plants from falling out and leads to ground stability. Therefore, the first paste material preferably contains pumice in a volume ratio of 30 v/v% or more, more preferably 35 v/v% or more, of the total amount of the granular base material.

(Inorganic ion adsorption/desorption material)
An inorganic ion adsorbent is an adsorbent that can adsorb inorganic ions that are useful for plant growth, and can also desorb and release the adsorbed inorganic ions. By using an inorganic ion adsorbent as part of a granular base material, the nutrients required by plants can be efficiently supplied, promoting their growth.
Examples of inorganic ion adsorbent/desorbent materials include inorganic ion exchangers, such as nitrate ion adsorbent/desorbent materials and phosphate ion adsorbent/desorbent materials. Examples of nitrate ion adsorbent/desorbent materials include functional carbon such as calcium-loaded carbon, and anion exchange resins. Examples of phosphate ion adsorbent/desorbent materials include baked adsorbents containing tobermorite allophane and kaolin clay. Adsorbents of different ions can also be used in combination as inorganic ion adsorbent/desorbent materials. In addition, inorganic ion adsorbent/desorbent materials may be porous materials containing inorganic ion adsorbing substances.

In the present invention, it is preferable that the second paste material contains an inorganic ion adsorbent/desorbent. By containing the inorganic ion adsorbent/desorbent in the second paste material, the initial growth of the plant can be promoted, the period when the plant is not yet fully grown and is weak in resistance and prone to withering can be shortened, and the success rate of greening can be increased. Note that in the present invention, the first paste material can also contain an inorganic ion adsorbent/desorbent.
The amount of inorganic ion adsorbent in the second paste material is preferably 0.1 v/v% or more and 30 v/v% or less in volume ratio to the total amount of the granular base material. If it is less than 0.1 v/v%, the amount of inorganic ions that can be supplied is small, and the plant growth improvement effect may not be achieved. If it is more than 30 v/v%, there is almost no further improvement in the plant growth effect and the cost becomes high. The volume ratio of the inorganic ion adsorbent to the total amount of the granular base material is more preferably 0.5 v/v% or more and 20 v/v% or less, and most preferably 1 v/v% or more and 15 v/v% or less.

"Polymer solidification material"
The polymer-based solidification material binds particles together, preventing the solidified soil from collapsing due to water flow or rainfall. In the waterside slope construction method at civil engineering sites of the present invention, the slope is covered with solidified soil, so it will not collapse even with rain of about 100 mm/hour. In addition, the solidified soil of the present invention allows the roots of aquatic plants to spread firmly, so the entire plant is stably supported, and the growth of aquatic plants can be promoted compared to a planting base that does not contain a polymer-based solidification material.

As the polymer-based solidification material, a material that has a soil hardness (Yamanaka method) of 15 mm to 35 mm after solidification and a soil hardness (Yamanaka method) of 15 mm to 30 mm when hydrated after solidification can be used. If the soil hardness after solidification is within the above range, plant roots can grow inside it. As the polymer-based solidification material, for example, acrylic resin, epoxy resin, rosin, etc. can be used. Note that there are also inorganic solidification materials such as asphalt, gypsum, and magnesium-based solidification materials, but inorganic solidification materials can cause problems such as filling the spaces between the particles of the granular base material and preventing water from penetrating, the bonds between the granular base materials being too strong and inhibiting root growth, and harmful substances dissolving in the water.

In the present invention, the amount of polymer solidifying material to be mixed can be adjusted depending on the hardness after solidification, the desired three-phase distribution value, etc., but is usually about 3 v/v% to 20 v/v% of the polymer solidifying material relative to the granular base material. The amount of this polymer solidifying material to be mixed is more preferably 4 v/v% to 15 v/v%, and even more preferably 5 v/v% to 10 v/v%.
The first paste material preferably contains more polymer solidification material than the second paste material. Specifically, the first paste material preferably contains 0.5 v/v % or more more polymer-based solidification material relative to the granular base material than the second paste material, and more preferably contains 1.0 v/v % or more more. By the first paste material containing more polymer solidification material than the second paste material, the solidified soil formed from the first paste material on the lower side can be constructed more firmly, and the collapse of the slope can be prevented.

"Hydrophilic polymers"
The hydrophilic polymer absorbs and retains rainwater and the like, and supplies water to the seeds in the soil base and to the aquatic plants that grow from the seeds. The solidified soil constructed from a paste containing hydrophilic polymers is more easily permeated by water than solidified soil constructed from a paste that does not contain hydrophilic polymers, and the difference in the values of each phase in the three-phase distribution (actual volume method) is smaller, which promotes the growth of aquatic plants. In addition, water rises through the hydrophilic polymers, so water can be supplied to a certain height above the water surface.
As the hydrophilic polymer, a material can be used whose liquid phase ratio (Ls (%)) in the three-phase distribution (actual volume method) after solidification is equal to or greater than the liquid phase ratio (Lp (%)) of the paste before solidification, i.e., Lp≦Ls, and examples of such a material include cellulose-based polymers, glucan, guar gum, and casein.

The amount of the hydrophilic polymer is not particularly limited as long as it is within the range that satisfies the above-mentioned liquid phase ratio relationship (Lp≦Ls), but is about 0.01 w/v% to 5.0 w/v% relative to the granular base material. The amount of the hydrophilic polymer is more preferably 0.03 w/v% to 3.0 w/v%, and even more preferably 0.05 w/v% to 1.0 w/v%.
The second paste material preferably contains more hydrophilic polymers than the first paste material. Specifically, the ratio of hydrophilic polymers to the total solid content in the second paste material (hydrophilic polymers/total solid content) is preferably 0.05 w/v % or more higher than the ratio of hydrophilic polymers to the total solid content in the first paste material (hydrophilic polymers/total solid content), and more preferably 0.1 w/v % or more higher. The second paste material contains aquatic plant seeds as described below in detail, and the second paste material contains a large amount of hydrophilic polymers, so that water can be supplied to the aquatic plant seeds and the germination rate can be increased.

The first paste material and the second paste material each contain three essential ingredients: a granular base material, a polymer-based solidifying material, and a hydrophilic polymer, and need only be uniformly mixed. If either or both of the polymer-based solidifying material and the hydrophilic polymer tend to form lumps, they can be mixed thoroughly with the granular base material beforehand, or dissolved or dispersed in water beforehand and then mixed. The amount of water in the paste should be within a range that provides a fluidity that allows it to be applied by a plasterer and a viscosity that does not run off when applied to an inclined surface, and is usually within a range of 1 v/v% to 30 v/v% by volume relative to the granular base material.

Aquatic plant seeds The aquatic plant seeds contained in the second paste material include submerged plants, floating plants, floating-leaf plants, emergent plants (emergent plants), and wetland plants, and one or more of these can be used. The aquatic plant seeds used in the present invention are more preferably emergent plants or wetland plants. An emergent plant is a plant that has roots on the bottom of the water, and the lower part of the stem is underwater, but at least a part of the stem or leaf protrudes above the water. A wetland plant is a plant that grows in a wet area such as a waterside, a wetland, or a marsh. In order to form a richer ecosystem, two or more types of seeds can be mixed, and different aquatic plant seeds can be used depending on the part to be covered, such as emergent plant seeds for the second paste that covers the part that is normally submerged in water, and wetland plants for the second paste that covers the part that is normally located at the waterside.

Examples of emergent or wetland plants that can be used in the present invention include the genus Watercress, the genus Spiraea, the genus Iris, the genus Myrsina, the genus Leucanthemum, the genus Paspalum, the genus Albicula, the genus Loach, the genus Zoysia, the genus Phragmites, the genus Salviata, the genus Scutellaria, the genus Ardisia, the genus Ardisia, the genus Cattail, the genus Falcon, the genus Scutellaria ... Examples of aquatic plants that can be used in the present invention include, but are not limited to, aquatic plants of the genus Calamus, Spiraea, Polygonum, Equisetum, Equisetum, Nelumbo, Eucalyptus, Monarchea, Pontederia, Menyanthes, Ranunculaceae, Parsley, Polygonum, Trachycarpa, Squatica, Eupatorium, Lythrum, Rumex, Lupinus, Chenopodium, and Lythrum salicaria. Examples of emergent or wetland plants that can be used in the present invention include, but are not limited to, reed canary grass, reed, burdock, loosestrife, wild iris, sedge, and wild rice.

"Experiment 1"
The components were mixed according to the composition shown in Table 1 below, and 2.5 v/v% water was added and stirred to prepare a paste. The paste was then filled into a wooden box (26.5 L = 77 cm x 57 cm x 6 cm deep) and air-dried outdoors for one week out of the rain to obtain a test soil.
The test soil was placed at a 45 degree incline, and artificial rain equivalent to 100 mm/hour was applied from above for 60 minutes, during which the amount of soil runoff was measured every 10 minutes. The change in the amount of soil runoff over time is shown in Figure 1.

Arakida
Granular base material 1: Sand Granular base material 2: Pumice (Kanuma soil)
Granular base material 3: Inorganic ion adsorption/desorption agent (functional carbon)
Polymer-based solidification material Acrylic-based Hydrophilic polymer Cellulose-based

Under the conditions using Arakida, approximately 300 g flowed out in the initial period (0 to 10 minutes), and the flow continued at a rate of approximately 50 g/10 minutes thereafter.
On the other hand, the soil solidified with a paste material containing a granular base material, a polymer-based solidification material, and a hydrophilic polymer showed almost no soil runoff even from the early stages of the experiment.
This suggests that the use of solidified soil prevents soil erosion, and that soaking seeds in the solidified soil can prevent the seeds from eroding.

"Experiment 2"
The components were mixed according to the ratio shown in Table 2 below, and 5.0 v/v % water was added and stirred to form a paste, which was then molded into a rectangular parallelepiped shape measuring 4 cm long x 6.5 cm wide x 50 cm high.
A paste was prepared using the same ingredients as above, except that 100 aquatic plant seeds (Alphabetella gracilis) were added. The paste was applied to a rectangular prism (6.5 cm x 50 cm) at a thickness of 0.5 cm, covering approximately 1/3 of the surface from the top in the height direction, to a dimension of 6.5 cm (horizontal) x 2 cm (vertical), to obtain a test specimen.
In addition, for the reference example (Arakida), after molding, seeds were sown in the same area to a depth of about 0.5 cm.

Arakida
Granular base material 1: Sand Granular base material 2: Pumice (Kanuma soil)
Granular base material 3: Inorganic ion adsorption/desorption agent (functional carbon)
Polymer-based solidification material Acrylic-based Hydrophilic polymer Cellulose-based

The test specimen was placed at an angle in a container filled with water so that the surface coated with the paste containing the aquatic plant seeds was facing up, and the part coated with the paste containing the aquatic plant seeds was about 5 cm above the water surface, and left for two weeks. Similarly, the test specimen of the reference example was placed so that the part sown with the aquatic plant seeds was 5 cm above the water surface, and left for two weeks.
The experiment was carried out by preparing two specimens (n=2) for each condition. The number of germinations after two weeks is shown in FIG.

In the present invention, Examples 1 and 2 showed a higher number of germinations than Comparative Example 1, in which no hydrophilic polymer was added. The aquatic plant seeds were sown at a position 5 cm or more above the water surface, and this result confirmed that the addition of the hydrophilic polymer provided the moisture necessary for germination, even when the seeds were sown above the water surface.

1 First paste material 11 Groove 2 Second paste material

Claims (5)

A step of covering a slope at a waterfront with a first paste material including a granular base material, a polymer-based solidifying material, and a hydrophilic polymer, and forming a groove extending in a substantially horizontal direction on the surface;
A step of covering the solidified soil obtained by solidifying the first paste material with a second paste material containing a granular base material, a polymer-based solidification material, a hydrophilic polymer, and an aqueous plant seed;
A waterside slope construction method comprising the steps of: The waterside slope construction method according to claim 1, characterized in that the first paste material contains pumice at a volume ratio of 30% or more to the total amount of granular base material. The waterside slope construction method according to claim 1 or 2, characterized in that the first paste material contains 0.5 v/v % or more more polymer-based solidification material relative to the granular base material than the second paste material. The waterside slope construction method according to any one of claims 1 to 3, characterized in that the second paste material contains at least 0.05 w/v % more hydrophilic polymer relative to the granular base material than the first paste material. The waterside slope construction method according to any one of claims 1 to 4, characterized in that the second paste material contains an inorganic ion adsorbent/desorbent.