Preparation and construction method of vegetation macroporous material for spraying and covering bare and steep rock surface

Abstract

The invention discloses a preparation and construction method of a vegetation macroporous material for spraying and covering a bare and steep rock surface, and belongs to the technical field of crossing of ecological restoration and geotechnical engineering materials. Expanded perlite particles 1 are adopted as a carrier for storing and secreting microorganism mineralized bacteria liquid and are also adopted as an inner mold core material of a hardened spherical shell 2 of a framework of the prepared plant-growing macroporous material; polyhalite powder is used for regulating and controlling the spraying working performance of the material, also serves as a slow-release calcium and magnesium source required by mineralization reaction and also serves as a sacrificial pore template material, and is gradually dissolved and disappears after the sprayed material is hardened, so that water-permeable and air-permeable polyhalite impression pores 5 are formed in the mineralized cement 3, and nutrients are also provided for inducing directional growth of plant root systems. And a calcium-magnesium-based carbonate mineralized cement 3 is generated through microbial mineralization reaction, a large number of macropores 4 are reserved in the material, and finally the plant-growing macroporous material capable of anchoring plant root systems and being cemented on the rock surface is formed and is suitable for ecological regreening of high and steep rock slopes of mines, reservoirs, expressways and the like.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of ecological restoration and geotechnical engineering materials, and particularly relates to a preparation and construction method of an ecological vegetation large-pore material suitable for treating a rock slope surface before topsoil spraying and seeding of a high and steep bare rock slope, and suitable for mine restoration, high and steep rock slope re-greening and the like. BACKGROUND

[0002] With the continuous advancement of ecological civilization construction, the ecological restoration of bare rock slopes is increasingly valued, especially in mining areas, along highways, reservoir banks and mountainous regions. The bare and steep rock surface is smooth in surface, large in slope, dense in structure and has no soil coverage, which seriously restricts the adhesion and rooting of plant seeds. The traditional greening spraying and seeding method is difficult to achieve effective re-greening on such slopes, and problems such as sliding of sprayed materials, low plant survival rate and unstable restoration effect often occur. In recent years, the microbially induced carbonate precipitation technology has been introduced into the reinforcement and ecological restoration of engineering materials due to its controllability, sustainability and ecological friendliness. It induces calcium carbonate to deposit between material particles through microbial activity, enhances the bonding force and structural stability of the substrate, and has good mechanical properties and ecological compatibility. However, the existing materials based on microbial mineralization are mainly used for flat slopes or rock-soil media, and have poor adaptability to rock slopes, especially in terms of constructing re-greening substrates that can be sprayed, have large pore structures, good adhesion and suitable plant growth on steep rock surfaces.

[0003] Prior art solutions

[0004] For the re-greening of bare rock slopes, physical structure means such as setting anchor structures, hanging net substrates and concrete bases are mainly used to increase the bonding force of the materials; or the formula of the sprayed topsoil substrate is improved to improve the water retention, air permeability and plant suitability of the material; or ecological concrete and vegetation are combined to restore bare rock slopes; or microbial mineralization is used to cement coarse sand particles to increase the roughness of the bare rock surface and improve the adhesion of the sprayed topsoil substrate.

[0005] Disadvantages of prior art solutions

[0006] The existing technical solutions of setting anchor structures, net hanging substrates, concrete bases and the like generally have problems of complex construction, high cost, poor ecological adaptability and the like; the scheme of improving the substrate formula is difficult to solve the problem of substrate adhesion on bare steep rock surfaces, especially in high and steep slope surfaces and areas with alternating drought and rain, and it is still difficult to achieve long-term stable ecological restoration; the ecological concrete slope protection has the problem of high alkalinity of cement-based materials, which is not conducive to the long-term growth of plant roots, and the long-term greening effect of bare steep rock surfaces is poor; for the method of using microbial mineralization and cementation of coarse sand particles to increase the roughness of bare rock surface to solve the adhesion stability of the substrate of the sprayed soil, there are problems of high rebound rate, low strength, small and poorly connected pores, lack of soil nutrients for root growth in the pores, and poor long-term stability of the vegetation. SUMMARY

[0007] The purpose of the present application is to overcome the problems of difficult adhesion of vegetation materials on bare steep rock surfaces, poor construction adaptability, unstable restoration effect and the like in the prior art of bare steep rock surface greening, and to provide a preparation and construction method of a vegetation macroporous material for spraying on bare steep rock surfaces. The method firmly cements the vegetation macroporous material with a unique microstructure on the rock surface, effectively anchors the plant roots, carries the nutrient substrate, and has the functions of soil locking, water retention and air permeability. The microbial mineralization carbon fixation and plant carbon sink synergistically promote the long-term stability and ecological self-maintenance of the greening system.

[0008] Technical solution: Select large particle expanded perlite with excellent lightness, porosity, strong water absorption and the like as a microbial carrier and root anchoring skeleton template. Dry expanded perlite is divided into two parts. One part is soaked in a Bacillus pasteurii bacterial solution containing urea under vacuum negative pressure to make the expanded perlite aggregate particle surface and its internal pores fully pre-absorb the bacterial solution. The other part is soaked in a urea solution under vacuum negative pressure to make the internal pores of the expanded perlite aggregate fully pre-absorb the urea solution. The pre-absorbed bacterial solution expanded perlite, the pre-absorbed urea expanded perlite and the miscellaneous halite powder are mixed and stirred according to a specific ratio to make the expanded perlite particle surface uniformly coated with the miscellaneous halite powder, thereby preparing a spraying material with excellent spraying performance. The spraying material is sprayed on the bare steep rock surface, and after spraying urea-calcium formate mixed solution and clay slurry in sequence, a unique microstructure of vegetation light macroporous material layer with a hard particle shell, a loose internal structure and a high-strength cementation between particles, similar to the structure of animal bones, is finally prepared on the bare steep rock surface. The vegetation light macroporous material layer is used for long-acting anchoring and ecological self-maintenance of the substrate of the sprayed soil and the roots of the vegetation on the bare steep rock surface.

[0009] Technical principle: Adopting expanded perlite particles 1 as microbial mineralization bacteria liquid storage and excretion carrier, and at the same time as the inner mold core material in the shell structure of the prepared plant growth macroporous material; when the expanded perlite particles act as microbial mineralization bacteria liquid storage and excretion carrier, the porous space inside each particle is used as a storage carrier for bacteria liquid and mineralization slurry, after absorbing bacteria liquid and urea solution respectively under vacuum, the originally fluffy, light and easy to float expanded perlite particles can be directional jetting under the action of airflow, and the mineralization bacteria and ion excreted by the particles can also provide a continuous source of mineralization microorganisms and reaction substrates for subsequent mineralization reactions; after the expanded perlite particles are wrapped with a specific mixed ratio of carnallite powder, the bacteria liquid excreted by the expanded perlite particles (bacteria-releasing perlite particles) saturated with bacteria liquid and the urea excreted by the expanded perlite particles (urea-releasing perlite particles) saturated with urea solution undergo microbial urease reaction, the produced carbonate combines with the calcium and magnesium ions released from the carnallite powder to form a symbiotic body of calcium carbonate and magnesium carbonate, which quickly cements the expanded perlite particles, so that the expanded perlite particles and the carnallite powder can quickly form strength and firmly adhere on the bare and steep rock surface; when the expanded perlite particles act as the inner mold core material of the jetting material, the sprayed urea-calcium formate mixed solution and the bacteria liquid excreted by the carnallite powder and the expanded perlite particles further undergo mineralization reaction, the surface layer of the originally loose and low-strength expanded perlite particles is hardened to form a dense hardened shell 2, which is then connected with the mineralized cement 3 composed of microbial mineralized calcium carbonate and basic magnesium carbonate between the expanded perlite particles to form a high-strength framework structure, leaving a large number of macropores 4 between the particles, forming a macroporous material with light weight, high strength, large pore and good connectivity; innovatively, the carnallite powder originally used as agricultural fertilizer is used as a slow-release calcium and magnesium source for microbial mineralization reaction and fine aggregate of macroporous material to improve the contact efficiency with perlite particles and enhance the adhesion of the mixed material on the rock surface; the carnallite powder also acts as a sacrificial pore template material, which gradually dissolves and disappears after the jetting material is hardened, forming more water-permeable and air-permeable carnallite imprint small pores 5 in the mineralized cement 3; the carnallite powder, calcium formate and urea absorbed in the perlite particles provide calcium source and mineralization reaction substrate for rapid mineralization reaction and cementation in the early stage of material spraying on the rock surface, effectively inhibiting the release of ammonia gas, a harmful byproduct of microbial mineralization reaction, and after the macroporous material is hardened, it continuously diffuses and transports nutrients such as potassium, calcium, magnesium and nitrogen into the pores of clay, providing long-acting nutrients for inducing plant roots to grow and anchor in the macroporous material, which can greatly improve the ecological suitability and plant planting performance of the existing guest soil spray seeding technology when combined with the subsequent conventional guest soil spray seeding substrate.

[0010] A preparation and construction method of a plant growth macroporous material for spraying on bare and steep rock surfaces, characterized in that the method steps are as follows: a. The expanded perlite particles with a particle size grading range of 6-12 mm are soaked in OD 600 The bacteria-releasing perlite particles are prepared by soaking the expanded perlite particles with a particle size grading range of 8-12 mm in a 0.8 mol / L urea solution for 4-6 h; the urea-releasing perlite particles are prepared by soaking the expanded perlite particles with a particle size grading range of 6-12 mm in OD b. 6-8 parts of the bacteria-releasing perlite particles, 2-4 parts of the urea-releasing perlite particles and 3-5 parts of the miscellaneous halite powder are stirred to make the miscellaneous halite powder uniformly adhere to the surfaces of the bacteria-releasing perlite particles and the urea-releasing perlite particles, thereby preparing the spraying material; c. The urea-formic acid calcium mixed solution is prepared according to the ratio of 30 g of urea, 65 g of calcium formate, 15 g of tryptone, 5 g of soybean peptone and 7.5 g of sodium acetate per L of water; d. The spraying material is uniformly sprayed on the rock slope surface by using the air flow spraying equipment, and the thickness of the spraying material is not less than 20 mm, and the spraying material is left to stand for 1-3 h; e. The urea-formic acid calcium mixed solution is slowly sprayed on the surface of the spraying material on the rock slope by using the atomizing spraying equipment, and 35-45 L of the urea-formic acid calcium mixed solution is required for spraying 1 m 3 of the spraying material, and the spraying material is left to stand for 24 h; f. The clay slurry with a solid content of 2.5-3.5% is sprayed to infiltrate into the pores of the spraying material on the rock slope, and the pore volume filling rate of the spraying material reaches 65%, thereby completing the construction of the vegetative macroporous material.

[0011] The present application has the following advantages: 1. The prepared spraying material has outstanding jetting rapid setting performance and rock surface adhesion ability, and after hardening, it has a unique and excellent macroporous structure and mechanical strength, can be firmly cemented on the bare steep rock surface, and has the ability to firmly anchor the plant root system; 2. When the present application is used as a substrate for the rock surface treatment in the guest soil spray seeding technology, it not only efficiently solves the problem of poor adhesion between the substrate and the rock surface and the problem that the plant root system cannot be anchored on the steep rock surface in the existing guest soil spray seeding technology, but also provides a more optimal water retention, air permeability and nutrient release environment, thereby providing a good anchoring carrier and long-term growth conditions for the plant root system; 3. The present application can achieve the firm adhesion and self-stabilization of the macroporous material on the rock slope with a high inclination angle, a smooth or rough surface and variable conditions, thereby breaking through the technical bottleneck that the traditional ecological restoration material is easy to fall off and difficult to survive in extreme working conditions, and significantly improving the greening feasibility and durability of the high and steep rock slope; 4. The present application uses the natural mineral material miscellaneous halite and the microbial mineralization technology, does not rely on cement or other high carbon emission materials, and greatly reduces the release amount of the undesirable byproduct ammonia gas in the existing microbial mineralization reaction technology, thereby having the outstanding advantages of lower carbon and environmental protection compared with the existing technology. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 Schematic diagram of the pore and skeleton structure of vegetative macroporous materials

[0013] Reference numerals: 1 - expanded perlite particles; 2 - hardened spherical shells; 3 - mineralized cement; 4 - macropores; 5 - small pores of polyhalite impressions. DETAILED DESCRIPTION

[0014] The preparation and construction method of the vegetation macroporous material for spray coating on bare steep rock surfaces can obtain vegetation macroporous materials with different porosities and pore sizes by adjusting the particle size of the expanded perlite particles in step a and the mass ratio of the bacteria-released perlite particles, urea-released perlite particles, and polyhalite powder in step b; and the hardening time of the spray material can be controlled by adjusting the urea concentration in the bacterial solution.

[0015] Example 1

[0016] In this example, a method for preparing and constructing a macroporous vegetation material for spraying on bare steep rock faces is applied to steep rock slopes in mines with slope angles greater than 50°. The method uses a preparation and construction process that has good initial adsorption effect and rapid initial strength stability. The specific steps are as follows: a. Soak the expanded perlite particles with a particle size range of 8 to 10 mm in a vacuum negative pressure in OD 600 The urea-releasing perlite particles were prepared by immersing the expanded perlite particles with a particle size distribution range of 10 to 12 mm in a 0.8 mol / L urea solution under vacuum negative pressure for 6 hours. b. Take 8 parts by mass of bacteria-releasing perlite particles, 2 parts of urea-releasing perlite particles, and 3 parts of polyhalite powder and stir them thoroughly so that the polyhalite powder is evenly attached to the surface of bacteria perlite particles and urea-releasing perlite particles to form a spray material; c. A urea - calcium formate mixture was prepared by adding 30 g of urea, 65 g of calcium formate, 15 g of tryptone, 5 g of soy peptone, and 7.5 g of sodium acetate per L of water; d. Use air jet equipment to evenly spray the spray material onto the rock slope surface. The thickness of the spray material should not be less than 20mm. Let it stand for 1 hour. e. Use atomizing spray equipment to slowly spray the urea-calcium formate mixture on the surface of the injection material on the rock slope, every 1m 3 The volume of injection material needs to be sprayed with 35L of urea-calcium formate mixture and left to stand for 24 hours; f. Spraying the clay slurry with a solid content of 3.0% to infiltrate into the pores of the sprayed material on the rock slope surface, until the pore volume filling rate of the sprayed material reaches 65%, and the construction of the vegetation macroporous material is completed.

[0017] After the construction of the vegetation macroporous material is completed, the existing guest soil spraying technology can be used to continue to spray the guest soil substrate, and the conventional maintenance method is used for maintenance, so as to realize the ecological greening of the high and steep rock slope of the mine.

[0018] Example 2

[0019] In this example, the preparation and construction method of the vegetation macroporous material for spraying on the bare steep rock surface is applied to the rock slope vegetation protection engineering of the mountain highway. The preparation and construction process with general initial strength and large pores is more conducive to the rapid growth of plants, and the specific steps are as follows: a. The expanded perlite particles with a particle size grading range of 10-12 mm are soaked in the OD 600 bacteria solution with a negative pressure vacuum for 8 h to prepare bacteria-released perlite particles. The bacteria solution is composed of Bacillus pasteurii and liquid culture medium, and contains urea with a concentration of 1.5 mol / L; the expanded perlite particles with a particle size grading range of 8-10 mm are soaked in a 0.8 mol / L urea solution with a negative pressure vacuum for 5 h to prepare urea-released perlite particles; b. 7 parts of bacteria-released perlite particles, 3 parts of urea-released perlite particles, and 4 parts of miscellaneous halite powder are thoroughly stirred to make the miscellaneous halite powder uniformly adhere to the surface of the bacteria-released perlite particles and the urea-released perlite particles, and the sprayed material is prepared; c. The urea-calcium formate mixed solution is prepared according to the ratio of adding 30 g of urea, 65 g of calcium formate, 15 g of tryptone, 5 g of soybean peptone, and 7.5 g of sodium acetate per L of water; d. The sprayed material is uniformly sprayed and covered on the rock slope surface by using air flow spraying equipment, and the thickness of the sprayed material is not less than 20 mm, and it is left to stand for 2 h; e. The urea-calcium formate mixed solution is slowly sprayed on the surface of the sprayed material on the rock slope by using atomizing spraying equipment, and 40 L of the urea-calcium formate mixed solution is needed for every 1 m 3 of the volume of the sprayed material, and it is left to stand for 24 h; f. The clay slurry with a solid content of 3.5% is sprayed to infiltrate into the pores of the sprayed material on the rock slope surface, until the pore volume filling rate of the sprayed material reaches 65%, and the construction of the vegetation macroporous material is completed.

[0020] After the construction of the vegetation macroporous material is completed, the existing guest soil spraying technology can be used to continue to spray the guest soil substrate, and the conventional maintenance method is used for maintenance, so as to realize the ecological greening of the high and steep rock slope of the mine.

[0021] Example 3

[0022] In this example, a preparation and construction method of a vegetation macroporous material for spraying on bare cliff face is applied in the vegetation restoration project of the drawdown zone of reservoir bank. The preparation process adopts the preparation process of rapidly forming initial strength and small pore size for more stable later strength. The specific steps are as follows: a. The expanded perlite particles with particle size grading range of 6-8 mm are soaked in OD 600 The bacteria solution is composed of Bacillus pasteurii and liquid culture medium, and contains urea with concentration of 1 mol / L. The expanded perlite particles with particle size grading range of 8-10 mm are soaked in 0.8 mol / L urea solution for 4 h to prepare urea-releasing perlite particles; b. 6 parts of bacteria-releasing perlite particles, 2 parts of urea-releasing perlite particles and 5 parts of miscellaneous halite powder are fully stirred to make the miscellaneous halite powder uniformly adhere to the surface of the bacteria-releasing perlite particles and the urea-releasing perlite particles, thereby preparing the spraying material; c. The urea-calcium formate mixed solution is prepared according to the ratio of 30 g of urea, 65 g of calcium formate, 15 g of tryptone, 5 g of soybean peptone and 7.5 g of sodium acetate per L of water; d. The spraying material is uniformly sprayed and covered on the rock slope surface by using air flow spraying equipment, and the thickness of the spraying material is not less than 20 mm, and the standing time is 3 h; e. The urea-calcium formate mixed solution is slowly sprayed on the surface of the spraying material on the rock slope surface by using atomizing spraying equipment, and 45 L of the urea-calcium formate mixed solution is needed for every 1 m 3 The volume of the spraying material, and the standing time is 24 h; f. The clay slurry with solid content of 2.5% is sprayed to infiltrate into the pores of the spraying material on the rock slope surface, and the pore volume filling rate of the spraying material reaches 65%, and the vegetation macroporous material construction is completed.

[0023] After the vegetation macroporous material construction is completed, the guest soil base material with strong viscosity can be continuously sprayed on it according to the existing guest soil spraying technology, and the conventional maintenance method is used for maintenance, so as to realize the vegetation restoration of the drawdown zone of reservoir bank.

Claims

1. A preparation and construction method of a macroporous material for vegetation spraying on bare steep rock surface, characterized in that The steps of this method are as follows: a. Soak the expanded perlite particles with a particle size range of 6 to 12 mm in a vacuum negative pressure in OD 600 The method comprises: immersing expanded perlite particles with a particle size distribution range of 8 to 12 mm in a 0.8 mol / L urea solution under vacuum negative pressure for 4 to 6 hours to prepare urea-released perlite particles; and immersing the expanded perlite particles in a 0.8 mol / L urea solution under vacuum negative pressure for 4 to 6 hours to prepare urea-released perlite particles. b. Take 6 to 8 parts by mass of bacterium-released perlite particles, 2 to 4 parts of urea-released perlite particles, and 3 to 5 parts of polyhalite powder and stir them thoroughly so that the polyhalite powder is evenly attached to the surface of the bacterium-released perlite particles and urea-released perlite particles to form a spray material; c. A urea - calcium formate mixture was prepared by adding 30 g of urea, 65 g of calcium formate, 15 g of tryptone, 5 g of soy peptone, and 7.5 g of sodium acetate per L of water; d. Use air jet equipment to evenly spray the spray material onto the rock slope surface. The thickness of the spray material should not be less than 20mm. Let it stand for 1 to 3 hours. e. Use atomizing spray equipment to slowly spray the urea-calcium formate mixture on the surface of the injection material on the rock slope, every 1m 3 The volume of injection material needs to be sprayed with 35-45L of urea-calcium formate mixture and left to stand for 24 hours; f. Spray clay slurry with a solid content of 2.5-3.5% to allow it to penetrate into the pores of the shotcrete on the rock slope until the pore volume filling rate of the shotcrete reaches 65%, completing the construction of the vegetation macroporous material.

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