JPH08308376A - Development execution of vegetational growth foundation of bedrock slope - Google Patents

Abstract

PURPOSE: To restore the usual natural vegetation by recovering original plants of a native species on a slope of a bare ground bedrock appearing by construction works. CONSTITUTION: A vegetational soil prepared by adding and mixing charcoal powder (e.g. fine tree bark charcoal powder), bentonite (e.g. KUROISHI bentonite), a humic acid (e.g. nitrohumic acid) and bases (e.g. ammoniacal nitrogen, phosphoric acid, calcium, magnesium or potassium) with collected volcanic soil is sprayed to 8-11cm thickness on a slope bedrock, brought into pressure contact therewith and consolidated to provide a soil dressing. A lawn grass (e.g. Italian ryegrass) of an early decline species and a plant of a native species are sparsely sown in the surface layer of the soil dressing to restore the natural vegetation according to an ecological technique. Furthermore, there is no fear of falling in the soil dressing and an embedded net is not required.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the formation of a vegetation base on a bare rock slope, and relates to a base construction method for protecting the bare rock slope and restoring it to a natural plant colony.

[0002]

2. Description of the Related Art Bare soil rock slopes that appear due to construction work are at risk of surface collapse due to weathering and erosion as they are, and damage the natural landscape. A variety of vegetation methods for revegetation have been proposed and implemented. In all of these, the vegetation soil is applied to the rock slope, and cultivated turfgrass, which is a fast-growing and highly sustainable plant, is densely vegetated on the slope to cover the slope and to be green.

If this is roughly divided, firstly, a concrete frame (free frame) is installed on a rock slope foundation, and a vegetation bag containing vegetation soil is installed in this area divided into a grid pattern. This is the method of vegetation with turfgrass. The concrete method frame is installed to prevent the vegetation bag from sliding down. This method is widely used for revegetation of rock slopes that appear during construction work.

Secondly, there is a construction method in which a buried net is laid on a rock slope foundation, vegetative soil (organic base material is the mainstream) is sprayed on the net, and turfgrass is vegetated on the soil. Buried nets are considered to prevent slipping of the soil. As for the steep slope slope, the adoption of this method is limited due to lack of verification of stability of the soil, and there are few examples.

[0005]

However, these greening and vegetation methods have the following problems. This is the first concrete construction method, but since the vegetation burial soil packed in the bag does not adhere to the rock foundation of the slope, it does not adhere to the rock foundation of the slope. A situation occurs in which the snow and ice blocks fall off the slope. In addition, the soil of the vegetation bag that is not in close contact with the bedrock foundation does not mature into the soil, so the growth of vegetation cannot be maintained without management such as additional fertilization, and we expect the restoration of natural vegetation here. It is not possible. Moreover, the concrete method frame installed to stabilize the vegetation bag on the slope is complicated in terms of workability and costly.

[0006] The construction method of laying a buried net on the second rock slope foundation and spraying the soil as a soil is cheaper than the construction method by the concrete method frame in terms of construction cost. Due to the lack of humus and clay (montmorolinite) necessary for maturation and agglomeration of the soil, this soil has no possibility of maturing into soil and restoration of natural vegetation cannot be expected here.

[0007] That is, the conventional vegetation method is to form a vegetation cover at an early stage by using a cultivated turfgrass, which has strong germination, strong growth, and strong sustainability, to protect the bare rock surface slope and to green the landscape. However, the restoration of natural vegetation on the bare rock slope is not considered, but rather the restoration of natural vegetation is hindered and desperate. However, the revegetation of bare rock slopes that has emerged due to construction work is not only for the purpose of landscape restoration, but must be restored to the original natural vegetation for the purpose of environmental conservation and ecosystem conservation and left for future generations. Is. Therefore, an object of the present invention is to create a vegetation growth base for restoring natural vegetation on the bare rock slope by an ecological method.

[0008]

[Means for Solving the Problems] In order to achieve the above object and achieve the object, a method for constructing a vegetation growth base according to the present invention is to add charcoal powder, bentonite, humic acid and bases to a collected volcanic soil. 8 to 11 cm of mixed vegetation soil
The vegetation growth base is created by compressing and consolidating soil on the sloped rock base with the thickness of the above, and the early decline turfgrass and native plants are sparsely sown on the surface of the vegetation growth base.

[0009]

In the method of constructing a vegetation growth base according to the present invention, a vegetation soil obtained by adding and mixing charcoal powder, bentonite, humic acid and bases to the collected volcanic soil is used as the guest soil. Charcoal powder improves the water retention of the collected volcanic soil, and retains and stores the water and oxygen required for plant growth and soil microbial growth even if the thickness of the soil is designed to be thin. This is brought about by the adsorbing / holding power of the enormous specific surface area of the fine porous charcoal powder, and it is particularly preferable to use the bark charcoal fine powder having a large specific surface area. Bentonite (Montmorolinite) and humic acid are substances necessary for maturation of soil, aggregation, and enhancement of fertilization capacity, and they are added to the collected volcanic soil that is deficient to enhance fertilization capacity. Promote maturation and aggregation. Bases are added to the collected volcanic soil to supplement and store the nutrients required for plant growth.

Next, in the construction method according to the present invention, the vegetation soil is sprayed by the energy of the compressed air, for example, without laying an embedded net on the slope foundation to form a pressure-bonded compacted soil. As a result, for example, a slope of 5 minutes has a thickness of 10
The cm soil can be settled without risk of slipping and falling, and a stable vegetation growth base can be created.

The soil layer thickness of the vegetation growth base is set to about 8 to 11 cm. This is shown in Figure 1 ("Soil story" by Shinho Iwata)
As shown in, the water content of soil becomes almost constant when the depth from the ground surface exceeds 8 cm, and it is based on the results of the test work performed so far.

Further, in the greening vegetation method according to the present invention, turfgrass of early decline type and native species plants are sparsely sown on the surface layer of the vegetation growth base,
Form a vegetation cover with the minimum required coverage for slope protection. This point is basically different from the conventional vegetation method. In the conventional vegetation method, cultivated turfgrass, which has strong germination, strong growth and strong sustainability, is densely sown to form a highly covered vegetation cover. However, the dense vegetation coverage of highly cultivated turfgrass blocks the invasion of native plants and hinders the restoration of natural vegetation. In the greening vegetation method according to the present invention, predominantly Italian ryegrass is predominantly sown, and native species are sparsely sown to form a minimum vegetation cover necessary to achieve the purpose of slope protection. Along with the decline of ryegrass, the invasion of native plants is promoted to restore the natural vegetation.

As described above, according to the method for constructing a vegetation growth base according to the present invention, there is no need to perform construction such as laying a buried net on the slope base, and therefore manpower-related work involving danger on a steep slope can be omitted. . There is no need to form and finish the slope flat.
Construction period is shortened and construction cost is reduced. By spraying the vegetation soil onto the slope with the blast energy of compressed air and pressing and compressing the soil, it is possible to create a stable vegetation growth base without the risk of slipping or collapsing even on the slope with a slope of 5 minutes. The construction cost is much more economical than the construction method. The growth of plants by adding charcoal powder, bentonite, humic acid, and bases to the collected volcanic soil as a vegetation soil with improved physical and biochemical properties.
It is possible to create a vegetation growth base with the conditions necessary for the reproduction of soil microorganisms and the generation and maturation of soil. Native natural vegetation can be restored by making invasion of native grass species into this vegetation growth base and forming a vegetation cover that measures the introduction of native species trees.

[0014]

[Examples] Examples of the present invention will now be described with reference to the accompanying drawings. The composition of vegetation soil, the design thickness of the vegetation growth base, the construction method and the stability of the growth base soil layer, the rapid greening and the introduction method of native seed trees. Will be explained in order.

(1) Composition of Vegetation Soil First, in the method for constructing a vegetation growth base of the present invention, vegetation soil obtained by mixing charcoal powder, bentonite, humic acid, and bases with mixed volcanic soil is used as a guest soil. , More specifically, charcoal powder is bark charcoal fine powder with a large specific surface area,
Bentonite is, for example, Kuroishi bentonite having a low sodium content and a large base substitution capacity, humic acid is, for example, nitrohumic acid having a large base substitution capacity, and the bases are ammoniacal nitrogen, phosphoric acid, calcium, magnesia, potassium and the like. The following table shows the added amount of each component.

[0016]

[Table 1]

[0017]

[Table 2]

The following table shows the relationship between the properties of the forest land and the growth of the trees (Sumiharu Kobayashi, Hiroshi Murai, Akira Kameyama, "Environmental Greening Engineering"), but Tables 1 and 2 The vegetation soil shown in Fig. 2 is adapted to the standard 2 in the table, which allows many tree species to grow normally, and it is considered that the native native species tree can sustain its growth.

[0019]

[Table 3]

The soil for the present vegetation contained 5 years worth of nitrogen required for the growth and continued growth of the young trees of the tree, and humic acid equivalent to the base substitution capacity (CEC) for saturating the ions. Is added in advance. It takes five years for the trees introduced into the immature growth base as soil to have a shortage of nitrogen components in order to continue to grow, and for the natural circulation of nutrient substances to take place smoothly. This is because it is considered necessary.

Further, two kinds of vegetation soils were prepared for the germinated seedling growth layer (Table 1) and the growth base layer (Table 2) for the following reasons. Figures 2 and 3 show the generation of soil and the transition of plant communities (Masao Maeda and Yoshio Matsuo, “Basic knowledge of soil”), and the transition of vegetation after cutting slope greening (Sumiharu Kobayashi, Hironobu Yoshida, Yukihiro Morimoto). (Co-authored "Slope greening")
FIG. To restore native woody vegetation on bare rock slopes, soil layers from the herbaceous stage to the shrub forest stage in the process of plant soil aging and plant community transition (Fig. 2) Plants that respond to soil maturation and accumulation due to life activities of plants and soil microorganisms over several years to several decades by creating a growth base corresponding to (Figure 1), growing herbs and starting vegetation transition There is no choice but to wait for the changing of the community.
However, in this case, as is clear from Fig. 3, it takes ten years or more for a native species forest to be established.

Therefore, in this method, a growth base corresponding to the soil layer in the shrub forest period of the vegetation transition process shown in FIG. 4 is created on the bare rock slope, and young trees of native species trees are grown and grown there. Consider developing vegetation transition. Therefore, the vegetation soil for the germination / seedling growth layer (Table 1, hereinafter referred to as “A layer soil”) mixed with organic matter (compost) containing seeds and soil
A vegetation soil (Table 2, hereinafter referred to as "B layer soil") for a growth base layer that does not mix seeds and organic matter (compost) is prepared.

(2) Design Thickness of Vegetation Growth Base As described above, the thickness of the vegetation growth base is 8 cm, which is created by using the vegetation soil in which the water retention capacity is enhanced by the bark charcoal fine powder and is improved. As shown in, the basement rock layer 11
Layer B, 5 cm thick, is the growth base layer 12, and A is on it.
A vegetation growth base consisting of a germination and seedling growth layer 13 with a layer soil thickness of 3 cm is created.

(3) Construction Method and Stability of Growth Foundation Soil Layer As shown in FIG. 5 at the construction site, the vegetation soil kneaded in a mud liquid by the mixer 15 is pressure-fed to the spraying point by the hose 16 by the pressure pump, From the compressor at the outlet 18 to the hose 1
Compressed air sent through 7 is sprayed, and this energy is blown onto the sloped rock foundation 11 for pressure bonding and compaction. At this time, the kinetic energy E of the soil particles is as follows, where w is the mass of the soil particles and v is the velocity at the time of jetting.

[0025]

[Equation 1]

By the kinetic energy E of the soil particles, the vegetation soil is pressure-bonded to the sloped rock foundation 11 to form a layered compacted soil, which is settled on the sloped rock foundation 11 to form a stable vegetation growth foundation.

Further, according to this construction method, it is not necessary to lay an embedded net on the slope base, and a vegetation growth base with a thickness of 10 cm slips even on a steep slope with a slope of 5 minutes and is established without the risk of collapse. Stabilize. This can be confirmed by the following stable calculation. 6, depth of soil layer is h, weight of soil layer is w, unit weight of soil is γ, slope angle of slope is α, internal friction angle of soil is φ, vertical to soil particles When the load is σ, the pore water pressure applied between soil particles is μ, and the strength constant of soil is C, the force s at which the soil layer tries to slip is given by the following equation.

[0028]

[Equation 2]

The shear resistance τ of soil is given by the following equation.

[0030]

(Equation 3)

Since the stability condition of the soil layer is s ≦ τ,
And the following equation holds from the equation (3).

[0032]

[Equation 4]

Since w = γh and σ = γhcos α, equation 4 is as follows.

[0034]

(Equation 5)

Therefore, the limit depth h of the soil layer is as follows.

[0036]

(Equation 6)

The soil having a thickness up to the critical depth of the soil layer is settled and stabilized on the steeply sloped foundation without the risk of slipping or collapsing. The critical depth (h) of the soil layer on the slope (α) slope is calculated. During spraying, during the snowmelt season (the water content of vegetation soil is saturated 1
00%) Shear test of soil with varying degree of saturation (Sumiharu Kobayashi, Hironobu Yoshida,
From Yukihiro Morimoto co-authored slope greening), 100% saturation, C =
10 g / cm ² , φ = 0, μ = 0, γ = 1.6 g /
slope gradient (alpha) is 10% as cm ³ (45 °), the limit depth (h) in the case of 8 minutes (52 °) and 5 minutes (63 °), respectively 8.8 cm, 7.9 cm, 7 .0c
m.

A state in which roots of turfgrass have grown (moisture content of vegetation soil is close to 100% saturation) Root system quantity and shear strength (Sumiji Kobayashi, Hironobu Yoshida, Yukihiro Morimoto)
Co-authored slope greening) Wet condition (close to saturation) C =
12 g / cm ² , φ = 20.4 degrees, μ = 0, γ =
Assuming 1.6 g / cm ³ , the slope (α) is 10% (45
Degrees), 8 minutes (52 degrees) and 5 minutes (63 degrees) limit depths (h) are 16 cm, 13 cm and 10 c, respectively.
m.

Therefore, construction such as laying a buried net is not necessary to fix and stabilize the soil on the slope foundation, and the slope is 5 minutes (63 degrees) depending on the shear resistance and strength of the soil itself.
It is confirmed that the soil with a thickness of 7 cm is stable and stable when spraying, and the soil with a thickness of 10 cm is stable when the grass roots grow. Moreover, in the conventional spraying method, a buried net is laid for the purpose of preventing slippage, but according to the above stability calculation, the effect of the buried net is that the strength constant (C) of the soil must be increased. I won't.
This depends on the adhesive force between the net and soil particles in the soil, but the adhesive force between the soil and the net having a saturation of 100% is equal to zero. Therefore, the buried net has no effect of increasing the soil strength constant (C), and the buried net is useless.

(4) Rapid greening and introduction method of native species trees In this method, native species plants are sparsely sown mainly on early-declining turfgrass, which is based on the following idea. Covering slopes with vegetation is the most effective way to protect slopes from weathering of bare ground slopes and erosion due to freezing and thawing, and rapid greening by turfgrass for fast-growing cultivation is effective. Is. In addition, the denser the cover with the initial vegetation, the greater the effect of preventing erosion, and the more dense the root mat is formed, the more stable the slope is. For this reason, dense vegetation covering by rapid greening has been performed for the purpose of preventing erosion and stabilizing the slope. However, it is clear from FIG. 3 that if the early vegetation does not decline and is predominant, the invasion of the native plant is prevented, and conversely if the early vegetation declines early, the invasion of the native plant becomes active. . Therefore, in order to intensify the invasion of native species plants to restore natural vegetation, the vegetation cover of cultivated turfgrass should be limited to the minimum degree of coverage necessary for the purpose of rapid greening, and grass species that decline early. Must form a vegetation cover.

FIG. 7 is a diagram showing the relationship between the number of Kentucky 31 fescue seedlings and the amount of soil eroded by rainfall (Masujiro Kurata "Greening Technology"). The figure shows 3000 per 1 m ² .
If grown, the amount of eroded soil will be one-fifth that of bare soil, indicating that the amount of eroded soil will not decrease so much even if the number of soils increases. In addition, the following table shows the experimental results of the covering density and the amount of eroded soil of the slope grass (red fescue) (Masujiro Kurata "Greening Technology"). The table shows that the coverage of the ground surface by grass leaves is 9
When it reaches 0%, the amount of eroded soil decreases to 10% and the coverage is 100%.
% Indicates that erosion hardly occurs.

[0042]

[Table 4]

Based on this, it is considered that the objective of rapid greening can be achieved if 3000 grasses per m ² are formed on the slope, and it is a native species mainly based on Italian ryegrass, which is a grass for cultivation that rapidly declines. It plans to establish 3000 grasses (mugwort and pests) per 1 m ² and sows the mixed seeds shown in the following table to form an initial vegetation cover. The seeds were designed on the assumption that the effective rate of seeds is significantly lower than the germination rate shown in the table.

[0044]

[Table 5]

Since the depth of the vegetation growth base is as shallow as 8 cm and the steep slope has a large area, it is difficult to plant native seedlings, and it is difficult to plant seedlings by manpower, and seeding by mechanical power is not possible. I don't get. However, it is said that the invasion of woody plants does not progress on the slope covered with vegetation of herbs and it is difficult to sow grasses and woody plants together. This is because woody plants germinate and grow slowly, and they are overwhelmed by fast-growing herbs and lose. Protective vegetation on bare slopes must be covered early with turfgrass that grows fast for that purpose, but we cannot expect woods to invade this vegetation slope and hope for successful seeding. I can't.

Therefore, in this method, as a method of introducing native seed trees, the coverage area of herbs is set to, for example, about 90% of the whole, and the remaining area is divided into zones where seeds of native seed trees are sown. Specifically, as shown in FIG. 8, a diameter of 1 m, for example, is used as an exclusive area of a tree for avoiding the pressure of turfgrass that is actively growing.
Circular zones 25 of a certain degree are randomly arranged on the slope.
If the total area of this zone 25 is 10% of the total, 10
Twelve places will be installed in the 0 m ² square area. This zone 25
The A layer soil mixed with the seeds of the native species tree is sprayed onto the soil, and the remaining slope portion 26 is the soil layer A mixed with the seeds of herbs to be sprayed on. In this way, the purpose of rapid greening is achieved, and the seeds and seedlings of the native species tree with slow germination growth also germinate and grow without being subjected to the pressure of turfgrass. Such native species of trees have been established, and the restoration of native vegetation can be expected.

[0047]

As described above, according to the method for constructing a vegetation growth base for a rock slope according to the present invention, it is possible to restore the original native plant to the slope of the bare rock surface, and the native natural vegetation can be restored. Can be restored.

[Brief description of drawings]

FIG. 1 is a diagram showing the amount of water in soil.

FIG. 2 is a diagram showing the generation of soil and the transition of plant communities.

FIG. 3 is a diagram showing a vegetation transition state after cutting slope greening construction.

FIG. 4 is a diagram schematically showing a vegetation growth base (a) created by the method of the present invention and a soil layer (b) during a vegetation transition process during a shrub forest period.

FIG. 5 is a diagram schematically showing a construction method for creating a vegetation growth base according to the present invention.

FIG. 6 is a cross-sectional view showing a soil layer formed on a steep slope.

FIG. 7 is a diagram showing a relationship between the number of seedlings and the amount of runoff soil.

[Fig. 8] Fig. 8 is a schematic view showing one construction example (early after construction) of the construction method according to the present invention. (A) is a front view of the slope, (b)
Is a side view of the slope.

FIG. 9 is a schematic view showing one construction example (several years after construction) of the construction method according to the present invention. (A) is a front view of the slope, (b)
Is a side view of the slope.

[Explanation of symbols]

 11 Slope foundation 12 Growth base layer (B layer soil) 13 Seed germination and seedling growth layer (A layer soil) 15 Mixer 16 Compressed air hose 17 Soil pressure feed hose for mud vegetation 18 Discharge port 25 Local species Tree sowing zone 26 Herbs Seeding zone

Claims (1)

[Claims] 1. Charcoal powder, bentonite,
Vegetative soil mixed with humic acid and bases is pressed and compacted on the slope bedrock with a thickness of 8 to 11 cm, and sown grass of early decline species and native plants are sparsely sown on the surface layer of the soil. A method of constructing a vegetation growth base characterized by restoring natural vegetation by an ecological method.