CN110506573B

CN110506573B - Method for ecological restoration of side slope

Info

Publication number: CN110506573B
Application number: CN201910772831.3A
Authority: CN
Inventors: 阮正; 宁杨; 陈雪
Original assignee: Guizhou Survey and Design Research Institute for Water Resources and Hydropower
Current assignee: Guizhou Survey and Design Research Institute for Water Resources and Hydropower
Priority date: 2019-08-21
Filing date: 2019-08-21
Publication date: 2022-03-29
Anticipated expiration: 2039-08-21
Also published as: CN110506573A

Abstract

The invention discloses a method for slope ecological restoration, which summarizes reasonable material proportion of a spray-seeding matrix according to a large amount of test data and engineering experience, so that the physicochemical property of the matrix reaches the optimal index required by plant growth; compared with highly dispersed soil particles formed by the similar technology, the soil structure with rich gaps formed in the invention can preserve water and ventilate, slow down leaching loss of nutrient elements and ensure good growth of plant roots; the sprayed artificial soil has small density, light unit weight and large internal friction angle, is easy to adhere to a steep slope and is not easy to peel off, and compared with the similar technology, the spraying and sowing thickness can be obviously improved, and the long-term growth requirement of plants is met. The use of polyacrylamide has flocculation effect on solid matrix, so that the solid-liquid separation of the matrix sprayed to the slope surface is realized, clear water is filtered out, and the loss of the solid matrix and nutrients is reduced; in the dehydration and shrinkage process of the matrix, the solid matrix forms a granular structure with certain porosity, which is more beneficial to plant growth.

Description

Method for ecological restoration of side slope

Technical Field

The invention relates to a method for ecological restoration of a side slope, and belongs to the technical field of water and soil conservation and ecological restoration.

Background

With the social progress, the ecological environment is more and more emphasized. Project construction causes serious damage and influence on ecological environment, and how to recover the damaged ecological environment in construction as soon as possible becomes an important and urgent subject.

An important part of ecological restoration is to reconstruct vegetation, and the vegetation restoration of the side slope is the key point and difficulty. After decades of research and exploration, developed countries such as Japan, Europe and America and the like form the basic theory and technical scheme of the respective vegetation slope protection technology. The research on the ecological restoration of the side slope is started later in China, before the 90 s of the 20 th century, the side slope protection mainly takes the traditional engineering measures of stone masonry, slope protection, spray anchor support and the like as main measures, and the systematic research on the ecological restoration of the side slope is started after the 90 s along with the improvement of social progress and understanding of environmental problems. At present, the slope protection technology is developed from the traditional engineering measures into the combination of the engineering measures and the plant measures, and the main adopted modes comprise turf paving, plant growing bags, three-dimensional vegetation net slope protection, vetiver grass hedgerow planting, geocells, grouted rubble stone frameworks, spray seeding and the like.

In the existing slope ecological restoration technology, spray seeding is an effective means, and can realize vegetation restoration of a soilless slope. Since the technology is introduced into China, through the development of ten years, numerous methods are developed, and a large number of messy names are presented. The names of the related spray seeding greening technologies appearing in the national engineering and technology circles and academia at present are as follows: "Hydraulic spray" (Wangzhian et al, 1999); "hydraulic spray" (lie and equant, 1999); "spray seeding of extra soil" (azadirachta, 2000); mixed spraying rapid greening (chapter changjiang et al, 2000); mixed spray greening (Xiaobiao et al, 2001); "mixed spray vegetation" (Zhou Ying et al, 2001); concrete spraying and grass planting (Jinzhong, 2001); "vegetation concrete" (schwann year et al, 2001); "organic substrate spray-seeding greening" (wandong et al, 2003); in addition, the engineering industry also has a statement of 'foreign soil blowing', and the translated terms are 'fibrous soil greening method', 'high-order granule SF greening method', 'continuous fiber greening method' and the like.

The world recognizes that the soil structure most conducive to plant growth is the granular structure (the relation between the granular structure and soil fertility, Libra, agricultural Press). The soil aggregate structure is a soil structure formed by bonding a plurality of soil single grains together to form an aggregate. Since small pores are formed between the single particles and large pores are formed between the aggregates, the total porosity is larger than that of the single particle structure. The small pores can retain water, and the large pores can retain air. The soil with the granular structure has the coordination capability of the optimal factors such as water, gas, heat, fertilizer and the like, and can ensure the good growth of the plant root system. The amount of aggregate structures in the soil is an important mark for soil fertility.

The existing spray seeding technology is that soil, peat soil, fiber, fertilizer, water-retaining agent, binder, seeds and the like are mixed with water and stirred into colloidal mixed slurry, and then the colloidal mixed slurry is sprayed to a slope surface by a pressure pump. The addition proportion and the addition time sequence of various materials and the application of scientific additives in the method are the key points for success, and the vegetation recovery effect is directly influenced. But the corresponding tests are lacked, the unified standard is not available, the materials are used in a wide range, and the implementation effect is good and uneven. The current common spray-seeding technology generally has the following defects:

(1) the material proportion is unreasonable, and the physicochemical property of the spray-seeding matrix can not reach the optimal index required by plant growth.

(2) The soil and water are stirred into mixed slurry, the granular structure of the soil is damaged, the artificial soil formed on the slope surface after being sprayed loses the pores among the granules, the soil is saturated with capillary water, and the soil cannot be permeated with water and air, is similar to a hardened state and is unfavorable for the growth of plants. The high-order granule spraying technology is used for solving the problem in the industry, but the special additive has high cost, needs special equipment and has high manufacturing cost, and is difficult to be widely applied.

(3) The soil is highly dispersed, the nutrient controlled release capability is weak, nutrient elements in the soil are quickly leached, the fertility is exhausted too early, the essential nutrients cannot be maintained for the plants for a long time, and the vegetation recovery effect is degraded.

(4) The sprayed matrix is in a suspension state of solid-liquid mixing. After the solid matrix is sprayed to the slope, the solid matrix cannot be separated from water and flows down with the water under the action of gravity, and a large amount of matrix particles and nutrient components are taken away.

(5) The sprayed artificial soil has high density, large unit weight, small internal friction angle, difficult adhesion on a steep slope and easy peeling, and the problem of the artificial soil needs to be solved by using an additive to improve the bonding strength, but the hardening state is aggravated due to overhigh strength, and the artificial soil is not beneficial to plant growth.

(6) Due to the characteristics of large density, low strength and low cohesive force of the matrix, the soil layer formed by spray-seeding is usually thin (about 10 cm), and cannot reach the thickness required by long-term growth of plants.

(7) The matrix is not provided with a skeleton structure, can be subjected to shrinkage expansion under the alternate action of drought and rainwater, is easy to be corroded by water power and freeze-thaw corrosion in winter, so that the loss of the originally limited matrix is caused, and a water and soil loss surface is artificially manufactured, which is contrary to the concept of water and soil conservation.

(8) The proportion of the additive is unscientific, and the expected effect cannot be achieved by adding too little additive; too much addition results in changes in the physical and chemical properties of the soil, which is not favorable for plant growth.

Disclosure of Invention

The invention aims to provide a method for ecological restoration of a side slope, which overcomes the defects in the prior art.

The technical scheme of the invention is as follows: a method for slope ecological restoration comprises the following steps:

step one, uniformly mixing 40-60% of soil, 20-30% of coconut tile powder and 20-30% of peat by volume percentage to obtain a basic matrix. Through repeated experiments of the inventor, the soil proportion is optimal to be 40-60%. If the soil proportion is more than 60%, the properties of the artificial substrate cannot be effectively improved. Besides nitrogen, phosphorus and potassium, the soil contains a large amount of elements required by plant growth, and the proportion of the soil is less than 40%, so that the later-stage plants lack the required elements, are unbalanced in nutrition and influence the growth. The addition of 20-30% of coconut brick powder can increase water retention and air permeability, increase organic matter content, release nutrients in slow decomposition, reduce matrix density, lighten matrix and increase internal friction angle. As the coconut tile powder is 'barren' compared with soil, the plant malnutrition can be caused when the proportion is too high, and the physical and mechanical indexes of the matrix can be reduced when the proportion is too low. The peat can increase the organic matter content of the matrix by 20-30%, improve the fertility and balance the pH value of the soil. The peat soil is expensive, the cost is increased when the proportion is too high, and the aim of soil improvement cannot be achieved when the proportion is too low.

And step two, adding 0.9kg of polypropylene fiber, 7.5kg of wood fiber, 13kg of rice hull and a plurality of fertilizers (the amount of the fertilizers is determined according to soil physicochemical detection) into each cubic meter of basic matrix, and uniformly mixing to obtain the dry matrix. The addition of a proper amount of polypropylene fiber and wood fiber can reduce the drying shrinkage expansion of the matrix, has certain toughness, increases the adhesive force, increases the maximum spray-seeding thickness and reduces the deformation. The rice hulls have good toughness, porosity, low density and rough texture, and the porosity and air permeability of the matrix can be increased by adding the rice hulls into the matrix, so that the growth of plants is facilitated; the density of the matrix is reduced, the internal friction angle is increased, the adhesion is increased, and the spray-seeding thickness is increased; the fertilizer is added into the matrix, generally slow release type fertilizers with slow release speed, such as calcium magnesium phosphate fertilizer, slow release compound fertilizer, organic fertilizer and the like, and the specific adding amount is determined according to the soil property in the matrix.

And step three, adding 400g of large-particle water-retaining agent not smaller than 8 meshes into each cubic dry matrix, and simultaneously adding 400-700 g of soil adhesive or 5-8 kg of ordinary portland cement into each cubic dry matrix to obtain the base layer (artificial soil layer) spray-seeding material. The water-retaining agent absorbs and stores water in rainfall and releases water in drought, the expected effect cannot be achieved when the adding amount is too small, and the artificial soil structure is influenced when too much water is added, so that the root rot of plants is caused. In order not to affect the aggregate property of the soil, the particle size of the base layer water-retaining agent is controlled to be 8 meshes or below.

Step four, carrying out spray seeding on the base layer (artificial soil layer) on the slope surface by adopting a common alien soil spray seeding machine, wherein the volume ratio of the base layer (artificial soil layer) to the artificial soil layer is 1: 8, adding 5 per mill of anionic polyacrylamide solution into the spray seeding material of the base layer (artificial soil layer), fully stirring uniformly, then spraying, wherein the spray seeding thickness is more than or equal to 10cm, adding water and adding the material in a common soil dressing spray seeding machine while stirring, controlling the concentration at 60-65%, causing equipment blockage when the concentration is too high, and causing matrix cohesive force to be reduced when the concentration is too low, so that the matrix cohesive force is difficult to attach to the slope surface. The inventors found that the soil fine particles were highly dispersed in the well-stirred base material, and the sprayed base material was in a suspended state of solid-liquid mixture. After the solid matrix is sprayed to the slope, the solid matrix cannot be separated from water and flows down with the water under the action of gravity, and a large amount of matrix particles and nutrient components are taken away. The polyacrylamide plays a role in flocculating the solid matrix, so that the solid and liquid of the matrix sprayed to the slope are separated, clear water is filtered out, and the loss of the solid matrix and nutrients is reduced. In the dehydration and shrinkage process of the matrix, the solid matrix forms a granular structure with certain porosity, which is more beneficial to plant growth.

Step five, after the spray seeding of the base layer is finished, the surface layer (seed layer) is spray-seeded, and the construction steps of the surface layer (seed layer) are as follows:

(a) firstly, adding water to 1/3 position of a material tank of a common soil dressing spray-seeding machine, adding water and wood fiber and plant seeds while stirring, wherein the dosage of the wood fiber is 35kg/m³The seed consumption is configured according to the ground conditions;

(b) continuously adding water, adding an adhesive and a water-retaining agent, stirring, adding a fertilizer after the water is full, and continuously stirring for 5-10 minutes, wherein the water-retaining agent is powder with the granularity of more than 100 meshes, and the using amount of the water-retaining agent is 0.2-1.0 kg/m³The amount of the binder is 0.5 to 1.5kg/m³；

(c) The thickness is kept uniform when the surface layer (seed layer) is sprayed, and the spraying of the substrate of each square is controlled to be 100m²And after spray sowing, covering 20g/m in time²Non-woven fabrics, keeping the soil wet until emergence of seedlings.

Step three in the method, when the gradient is less than 70 degrees, 400-700 g/m of soil adhesive is added into the matrix³The adding amount is determined according to the viscosity and gradient of the soil in the matrix; when the gradient is larger than 70 degrees, common Portland cement is used as a binder, and the dosage is 5-8 kg/m³. The binder can stabilize the spray seeding matrix attached to the slope surface, and is not influenced by rain wash, but the addition of too much binder can change the physical and chemical properties of soil, cause soil hardening, and increase salinization; if the addition amount of the binder is too small, the requirements of loss prevention and scouring resistance cannot be met.

In the method, gypsum is added to adjust the pH value of the material before the base layer (artificial soil layer) is sprayed with the material, and the pH value is controlled to be 6.0-7.0.

In the method, when the fertilizer of the base layer (artificial soil layer) is sufficient, in order to avoid burning seeds and seedlings, the fertilizer on the surface layer is mainly the microbial fertilizer, the using amount is determined according to the effective bacterial content, and the using amount of the microbial fertilizer of 8 ten thousand units is 300g/m³。

Due to the adoption of the technical scheme, the invention has the advantages that:

(1) according to a large amount of test data and engineering experience, the reasonable material proportion of the spray-seeding matrix is summarized, so that the physicochemical property of the matrix reaches the optimal index required by plant growth.

(2) Compared with highly dispersed soil particles formed by the similar technology, the soil structure with rich gaps formed by the invention can preserve water and ventilate, slow down leaching loss of nutrient elements and ensure good growth of plant roots.

(3) The sprayed artificial soil has small density, light unit weight and large internal friction angle, is easy to adhere to a steep slope and is not easy to peel off, and compared with the similar technology, the spraying and sowing thickness can be obviously improved, and the long-term growth requirement of plants is met.

(4) The use of polyacrylamide has flocculation effect on solid matrix, so that the solid-liquid separation of the matrix sprayed to the slope surface is realized, clear water is filtered out, and the loss of the solid matrix and nutrients is reduced; in the dehydration and shrinkage process of the matrix, the solid matrix forms a granular structure with certain porosity, which is more beneficial to plant growth.

(5) The application of the polypropylene fiber and the wood fiber ensures that the matrix has a certain skeleton structure, reduces the shrinkage and expansion, avoids the erosion of water power and freeze-thaw, controls the water and soil loss, and conforms to the water and soil conservation concept.

(6) The scientific dosage of various chemical additives is determined, the physicochemical properties of the soil are not changed while the using effect is achieved, and the plant growth is not influenced.

(7) The ordinary soil-dressing spray-seeding machine can be constructed without special equipment and special additives, replaces high-cost technology and reduces the construction cost.

Drawings

FIG. 1 is a construction flow chart of the present invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention will be further described in detail with reference to the accompanying drawings and examples.

Example 1

A certain highway slope in a mountain area has 50-60 degrees of slope of a cutting, is a soil slope, mainly comprises sandy loam, and is measured to have a pH value of 5.5-6.0. The altitude of the project area is 1100m, the annual average precipitation is 1150mm, the annual average temperature is 15.1 ℃, the extreme low temperature is between 7.1 ℃ and the extreme high temperature is 37.8 ℃, the frost-free period is 234 days, and the sunshine hours are 1000 h.

The project is a soil slope with good soil quality, and the surface layer is directly sprayed without spraying a base layer. According to the characteristics of higher altitude and long freezing time in winter in a project area, perennial ryegrass, tall fescue, purple fescue and poa annua are selected and mixed for sowing. At 10m³The volume of the spray seeder is firstly added with 3m³Adding 264kg of wood fiber and 28kg of mixed seeds into clear water, continuously stirring, and adding water to 8m³2kg of water-retaining agent and 3.2kg of adhesive are added in the process of adding water, stirring is carried out continuously, and finally 24kg of calcium magnesium phosphate fertilizer, 2.4kg of microbial agent, 180kg of organic fertilizer and 36kg of slow-release compound fertilizer are added. And after all the materials are added, continuously stirring for 5-10 minutes, and then carrying out spray sowing by adopting a common soil dressing spray sowing machine, wherein the spray sowing is carried out from high to low, the spray sowing is carried out from left to right, the width of the spray sowing is 5-6 meters, the width of the spray sowing is 1 meter, and the spray sowing is carried out for 40cm of stubble. The sprayed seed slurry is not missed, repeated and uniform. After spraying, the spraying is supplemented according to the specific situation, and the non-woven fabric is covered for watering and maintenance.

In this example, construction was carried out in 5 th of 2019, seedlings emerged 15 days after spray seeding, and the lawn was completely built in 7 th of the middle of the month.

(2) Example 2

A slope is excavated in a certain wind power plant in the southwest, the slope is 70 degrees, and the sand shale is moderately weathered. The altitude of the project area is 900m, the annual average rainfall is 1120mm, the annual average temperature is 16.8 ℃, the extreme low temperature is between 7.9 ℃ and 43 ℃ and the extreme high temperature is 294 days in a frost-free period, and the sunshine hours are 1200 h.

Firstly, cleaning loose rock and dangerous stones on the slope surface, finishing a down slope and chamfering, and flattening the slope surface as much as possible. Drilling holes perpendicular to the slope surface at the interval of 2m, inserting a main anchor rod, performing grouting protection, wherein the main anchor rod adopts ribbed steel bars with the diameter of 18mm, and the rock-entering depth is 70 cm. Drilling and interpolation secondary anchor rods between the main anchor rods, controlling the density according to interpolation 1-2 secondary anchor rods between every two main anchor rods, adopting smooth round steel bars with the diameter of 10mm as the secondary anchor rods, ensuring the rock-entering depth to be 40cm, and performing grouting protection. And laying a galvanized iron wire net along the slope from top to bottom, attaching the net surface to the slope, stretching and tensioning the net surface, and fixing the net surface by using primary and secondary anchors. The anchor rod is encrypted at the uneven part of the slope surface.

Carrying out basic layer spray seeding: preparing a basic matrix according to the volume ratio, and uniformly mixing 60% of planting soil, 20% of the soaked coconut powder bricks and 20% of peat soil to obtain the basic matrix. 13kg of rice hulls, 7kg of wood fibers, 0.9kg of polypropylene fibers, 0.6kg of calcium magnesium phosphate fertilizer, 4.5kg of organic fertilizer, 0.6kg of compound fertilizer and 60g of microbial agent are added into each cubic meter of basic matrix and are uniformly mixed to obtain the dry matrix. At 10m³Adding water 1m into spray seeding machine³Slowly adding the prepared dry matrix into a spray seeder, continuously adding water during the process, and continuously stirring. Dry substrate added 4.8m³When the addition is stopped, the substrate in the material tank is preferably 7m³. Adding 3.2kg of water-retaining agent, stirring for enough time to make the water-retaining agent fully absorb water, adding 50kg of ordinary Portland cement, and adding 20kg of gypsum powder (CaSO)₄·2H₂O), stirring uniformly, adding 1m³And stirring the polyacrylamide solution with the concentration of 5 per mill for 5 to 10 minutes to spray the base layer. And carrying out spray-seeding by adopting a common soil dressing spray-seeding machine, wherein the spray-seeding adopts a top-down mode, and the width of a single block is controlled according to 4-6 m. Spraying for multiple times to form a base layer with the thickness of more than or equal to 10 cm. After the spray seeding is finished, the mesh surface is covered by the matrix by more than 80 percent.

And (5) carrying out surface layer spray seeding for 3-4 h after the base layer construction is finished. According to the regional site conditions, clover, cassia tora, locust tree, magnolia multiflora, lespedeza, pigeon pea and the like are selected and mixed for sowing. At 10m³The volume of the spray seeder is firstly added with 3m³Adding 264kg of wood fiber and 32kg of mixed seeds into clear water, and continuously stirring. Adding water to 8m³Adding 1.2kg of water-retaining agent and 3.2kg of adhesive in the process, stirring continuously. Because the fertilizer in the spray seeding base layer is sufficient, in order to avoid burning seeds and seedlings, other fertilizers are not added except 2.4kg of microbial agent. And after all the materials are added, continuously stirring for 5-10 minutes and then spraying. After spraying, the spraying is supplemented according to the specific situation, and the non-woven fabric is covered for watering and maintenance.

In this embodiment, the construction is carried out in 11-month upper ten days in 2018, seedlings emerge 30 days after spray seeding, the vegetation coverage rate in 12-month upper ten days reaches 30%, the vegetation coverage rate is over 90% in 4-month next year after safe wintering.

Claims

1. A method for slope ecological restoration is characterized by comprising the following steps:

step one, uniformly mixing 40-60% of soil, 20-30% of coconut tile powder and 20-30% of peat by volume percentage to obtain a basic matrix;

step two, adding 0.9kg of polypropylene fiber, 7.5kg of wood fiber, 13kg of rice hull and a plurality of fertilizers into each cubic meter of basic matrix, and uniformly mixing to obtain a dry matrix;

adding 400g of water-retaining agent with the particle size of less than 8 meshes into each cubic dry matrix, and simultaneously adding 400-700 g of soil adhesive or 5-8 kg of ordinary portland cement into each cubic dry matrix to obtain a base layer spray-seeding material;

and step four, carrying out basic layer spray seeding on the slope surface by adopting a common soil dressing spray seeding machine, wherein 10 minutes before the spray seeding, the volume ratio is 1: 8, adding 5 per mill of anionic polyacrylamide solution into the base layer spray seeding material, fully and uniformly stirring, then spraying and seeding, wherein the spray seeding thickness is more than or equal to 10cm, adding water while stirring in a common soil-dressing spray seeding machine, and controlling the concentration to be 60-65%;

step five, after the spray seeding of the base layer is finished, the surface layer is sprayed and seeded, and the surface layer construction steps are as follows:

(a) firstly, adding water to 1/3 of a material tank of a common soil dressing spray seeder, adding wood fiber and plant seeds while adding water, and carrying out high speed cultivation with the wood fiber dosage of 35kg/m and the seed dosage according to the ground conditions;

(b) continuously adding water, adding an adhesive and a water-retaining agent, stirring, adding a fertilizer after the water is full, continuously stirring for 5-10 minutes, wherein the water-retaining agent is powder with the granularity of more than 100 meshes, the using amount of the powder is 0.2-1.0 kg/m, and the using amount of the adhesive is 0.5-1.5 kg/m for carrying out thin film planting;

(c) keep thickness even when top layer spray seeding, control each side matrix spray seeding 100m, cover 20g/m non-woven fabrics in time after spray seeding, keep soil moist until emerging.

2. The method for slope ecological restoration according to claim 1, characterized in that: in the third step, when the gradient is less than 70 degrees, 400-700 g/m of soil binder is added into the matrix, and the adding quantity is determined according to the soil viscosity and the gradient in the matrix; and when the gradient is larger than 70 degrees, using common Portland cement as a binder, and carrying out the high-speed dry top-dressing and high-speed dry top-dressing with the use amount of 5-8 kg/m.

3. The method for slope ecological restoration according to claim 1, characterized in that: before the basic unit spray-seeding material is spray-seeded, gypsum is added to adjust the pH value of the material, and the pH value is controlled to be 6.0-7.0.

4. The method for slope ecological restoration according to claim 1, characterized in that: when the fertilizer of the base layer is sufficient, in order to avoid burning seeds and seedlings, the fertilizer of the surface layer is mainly the microbial fertilizer, the using amount is determined according to the effective bacterial content, and the using amount of the microbial fertilizer of 8 ten thousand units is 300g/m for cultivating trees.