Method for reinforcing ecological slope by combining biopolymer with charcoal

Abstract

The invention discloses an ecological slope reinforcing method by combining biopolymer with biochar, which comprises the following steps: improving the vegetation condition and initial strength of soil by using biochar and biopolymer with high cohesive force as soil additives, and filling plant planting holes with prepared improved soil and plant seeds, the shear strength of the slope soil is improved by utilizing the reinforcing effect of the plant root system and the biopolymer, and meanwhile, water and soil loss caused by rainfall and the like is reduced. The biochar is added to improve the planting conditions of the soil, improve the air permeability of the soil and prevent the problems of soil hardening and the like possibly caused by biopolymers. Results show that the combined action of the biopolymer and the biochar can effectively improve the soil strength and promote the plant growth, and guarantee is provided for the long-term stability of the side slope.

Description

Technical Field

[0001] The invention belongs to the technical field of geotechnical engineering, and specifically relates to an ecological slope reinforcement method combining biopolymer with biochar. Background Art

[0002] In the northwest plateau area of ​​my country, there are many mountains and canyons, and the terrain is undulating. This terrain feature makes the soil prone to collapse and sliding under the action of gravity. At the same time, the area is widely covered with loose loess with large porosity. This type of soil easily absorbs water during rainfall or snowmelt, resulting in a decrease in soil strength, which in turn causes geological disasters such as landslides. In recent years, landslides in loess areas have become an important issue hindering the economic development and infrastructure construction in the region. Therefore, how to improve the soil strength in the loess area and reduce the risk of slope instability in the area is of great significance to promoting the safe and stable development of the region.

[0003] Existing soil reinforcement and slope treatment technologies mainly use traditional curing agents such as cement and gypsum to improve soil strength through chemical reactions. These engineering methods mainly have the following disadvantages: large workload, high labor costs, and poor long-term effects. At the same time, since these methods improve slope stability by combining with the rigidity of the slope surface, this treatment process will destroy the original soil conditions, hinder plant growth, destroy the balance of the ecosystem, and cause irreversible damage to the environment. Therefore, it is necessary to design and explore an ecological slope reinforcement method that can not only improve slope stability in the long term, but also reduce the impact on the environment. Summary of the invention

[0004] To solve the above problems, the present invention discloses an ecological slope reinforcement method combining biopolymer and biochar. The addition of biopolymer gellan gum and biochar as soil conditioners effectively improves the early strength of the slope while increasing the growth rate of plants, thereby accelerating the construction process of the ecological plant slope protection project.

[0005] To achieve the above object, the technical solution of the present invention is as follows: An ecological slope reinforcement method combining biopolymer and biochar comprises the following steps: Step 1) dig out plant planting holes of approximately 10*10*10 cm at equal intervals on the surface of the slope to be reinforced; Step 2) using a dry mixing method, a suitable amount of slope soil is mixed with biopolymer and biochar in a ratio of 100:0.1-0.5:1-6 to form a uniform solid mixture; Step 3) The solid mixture is then mixed and stirred evenly with water accounting for 17.3% (optimal water content) of the soil mass, and the stirred soil is placed in a sealed container for curing until the water and the biopolymer fully react to form a viscous gel, and finally a uniform improved soil is prepared; Step 4) Fill the prepared improved soil into the plant planting hole, and sow the plant seeds soaked in clean water for two hours into the plant planting hole; Step 5) Regularly water and maintain the plant planting holes and record the growth of the plants; Step 6) After 30 days, use a ring cutter to take the original soil from the planting hole and test its shear strength.

[0006] As a supplement to the present invention, the biopolymer in step 2) is gellan gum.

[0007] As a supplement to the present invention, the biochar in step 2) includes a mixture of one or more of wood biochar, bamboo charcoal, agricultural waste biochar, and livestock manure biochar.

[0008] As a supplement to the present invention, the plant seeds in step 4) are Bermuda grass or tall fescue seeds.

[0009] The beneficial effects of the present invention are: The new ecological slope reinforcement scheme described in the present invention uses biochar and high-cohesion biopolymers as soil additives to improve soil vegetation conditions and initial strength, and utilizes the reinforcing effect of plant roots and biopolymers to improve the shear strength of slope soil. The survival rate of plants is low in the early stage of growth, and the root strength is low, which makes it difficult to play a good role in slope reinforcement. However, the addition of biopolymers can effectively improve the initial strength of slope soil, while reducing soil erosion caused by rainfall. The addition of biochar is to improve the soil vegetation conditions, increase the air permeability of the soil, and prevent problems such as soil compaction that may be caused by biopolymers. The combined effect of biopolymers and biochar can effectively improve soil strength and promote plant growth. At the same time, the comparison results with the blank control group show that the growth of vegetation in the slope can effectively improve the strength of the soil, providing a guarantee for the long-term stability of the slope.

[0010] The addition of ecological curing agent biopolymer has good bonding properties and water absorption characteristics. Its own properties are not affected in acidic, alkaline and saline environments. It can effectively improve the shear strength of slope soil in the early stage of plant planting, improve the initial strength of the slope, and reduce soil erosion caused by scouring. At the same time, the decomposition of biopolymer can provide nutrients for plants and promote plant growth.

[0011] However, due to the strong bonding properties of biopolymers, it may cause soil compaction, which is not conducive to plant growth. To address this situation, the present invention specifically adds a negative carbon-type porous material, biochar, which is a carbonaceous material made by heating biomass (such as wood, crop residues, animal manure, etc.) under low oxygen conditions (usually a pyrolysis process). It has the characteristics of high stability, large specific surface area and high cation exchange capacity, which can improve the physical structure of the soil, increase the air permeability and permeability of the soil, thereby promoting root growth and soil microbial activity, increasing the survival rate of plants and improving the reinforcement efficiency of plant slopes. DETAILED DESCRIPTION

[0012] The present invention will be further explained below in conjunction with specific implementation modes. It should be understood that the following specific implementation modes are only used to illustrate the present invention and are not used to limit the scope of the present invention.

[0013] Step (1): clean the surface of the slope to be reinforced and dig out plant planting holes with a volume of about 10*10*10cm at equal intervals; Step (2): Use a dry mixing method to mix an appropriate amount of slope soil with gellan gum and bamboo biochar in a ratio of 100:0.1:1 to form a uniform solid mixture. Then mix the solid mixture with water and stir evenly, with the water accounting for 17.3% of the soil mass (optimal moisture content). Place the stirred soil in a sealed container for curing until the water and biopolymer fully react to form a viscose gel, and finally prepare a uniform improved soil; Step (3): Fill the prepared improved soil into the plant planting hole, and sow the tall fescue seeds soaked in clean water for two hours into the plant planting hole; Step (4): Regularly water and maintain the plant planting holes, and record the growth of the plants; Step (5): After 30 days, use a circular cutter to take the original soil from the planting hole and test its shear strength.

[0014] Step (1): clean the surface of the slope to be reinforced and dig out plant planting holes with a volume of about 10*10*10cm at equal intervals; Step (2): First, mix bamboo biochar and livestock manure biochar in a ratio of 1:1, and use a dry mixing method to mix an appropriate amount of slope soil with gellan gum and biochar in a ratio of 100:0.3:3 to form a uniform solid mixture. Then, mix and stir the solid mixture with water accounting for 17.3% (optimal moisture content) of the soil mass, and place the stirred soil in a sealed container for curing until the water and biopolymer fully react to form a viscose gel, and finally prepare a uniform improved soil; Step (3): Fill the prepared improved soil into the plant planting hole, and sow the tall fescue seeds soaked in clean water for two hours into the plant planting hole; Step (4): Regularly water and maintain the plant planting holes, and record the growth of the plants; Step (5): After 30 days, use a circular cutter to take the original soil from the planting hole and test its shear strength.

[0015] Step (1): clean the surface of the slope to be reinforced and dig out plant planting holes with a volume of about 10*10*10cm at equal intervals; Step (2): First, mix bamboo biochar and livestock manure biochar in a ratio of 1:1, and use a dry mixing method to mix an appropriate amount of slope soil with gellan gum and biochar in a ratio of 100:0.5:6 to form a uniform solid mixture. Then, mix and stir the solid mixture with water that accounts for 17.3% (optimal moisture content) of the soil mass, and place the stirred soil in a sealed container for curing until the water and biopolymer fully react to form a viscose gel, and finally prepare a uniform improved soil; Step (3): Fill the prepared improved soil into the plant planting hole, and sow the Bermuda grass seeds soaked in clean water for two hours into the plant planting hole; Step (4): Regularly water and maintain the plant planting holes, and record the growth of the plants; Step (5): After 30 days, use a circular cutter to take the original soil from the planting hole and test its shear strength.

[0016] Step (1): clean the surface of the slope to be reinforced and dig out plant planting holes with a volume of about 10*10*10cm at equal intervals; Step (2): First, mix bamboo biochar and livestock manure biochar in a ratio of 1:1, and use a dry mixing method to mix an appropriate amount of slope soil with xanthan gum and biochar in a ratio of 100:0.3:3 to form a uniform solid mixture. Then, mix and stir the solid mixture with water that accounts for 17.3% (optimal moisture content) of the soil mass, and place the stirred soil in a sealed container for curing until the water and biopolymer fully react to form a viscous gel, and finally prepare a uniform improved soil; Step (3): Fill the prepared improved soil into the plant planting hole, and sow the tall fescue seeds soaked in clean water for two hours into the plant planting hole; Step (4): Regularly water and maintain the plant planting holes, and record the growth of the plants; Step (5): After 30 days, use a circular cutter to take the original soil from the planting hole and test its shear strength.

[0017] Step (1): clean the surface of the slope to be reinforced and dig out plant planting holes with a volume of about 10*10*10 cm at equal intervals; Step (2): Use the dry mixing method to mix an appropriate amount of slope soil with water accounting for 17.3% (optimal moisture content) of the soil mass and stir evenly, and place the stirred soil in a sealed container for curing; Step (3): Fill the prepared improved soil into the plant planting hole, and sow the tall fescue seeds soaked in clean water for two hours into the plant planting hole; Step (4): Regularly water and maintain the plant planting holes, and record the growth of the plants; Step (5): After 30 days, use a circular cutter to take the original soil from the planting hole and test its shear strength.

[0018] Step (1): clean the surface of the slope to be reinforced and dig out plant planting holes with a volume of about 10*10*10 cm at equal intervals; Step (2): Use a dry mixing method to mix an appropriate amount of slope soil and gellan gum in a ratio of 100:0.25 to form a uniform solid mixture. Then, mix and stir the solid mixture with water accounting for 17.3% (optimal moisture content) of the soil mass, and place the stirred soil in a sealed container for curing until the water and biopolymer fully react to form a viscose gel, and finally prepare a uniform improved soil; Step (3): Fill the prepared improved soil into the plant planting hole, and sow the tall fescue seeds soaked in clean water for two hours into the plant planting hole; Step (4): Regularly water and maintain the plant planting holes, and record the growth of the plants; Step (5): After 30 days, use a circular cutter to take the original soil from the planting hole and test its shear strength.

[0019] Step (1): clean the surface of the slope to be reinforced and dig out plant planting holes with a volume of about 10*10*10 cm at equal intervals; Step (2): Use the dry mixing method to mix an appropriate amount of slope soil and biochar in a ratio of 100:5 to form a uniform solid mixture. Then, mix the solid mixture with water that accounts for 17.3% (optimal moisture content) of the soil mass and stir it evenly. Place the stirred soil in a sealed container for curing until the water and biopolymer fully react to form a viscous gel, and finally prepare a uniform improved soil; Step (3): Fill the prepared improved soil into the plant planting hole, and sow the tall fescue seeds soaked in clean water for two hours into the plant planting hole; Step (4): Regularly water and maintain the plant planting holes, and record the growth of the plants; Step (5): After 30 days, use a circular cutter to take the original soil from the planting hole and test its shear strength.

[0020] The basic parameters of the various materials used in the present invention are shown in Table 1. The effects of different formulations on plant growth were tested using plant cultivation experiments, and a series of characteristic parameters such as growth rate, plant height and root length were used for standardization. The reinforcement effect of the new ecological slope reinforcement method of the present invention on the strength properties of slope soil was tested by direct shear tests. The above test results are shown in Tables 2 and 3 Table 1.1 Basic properties of materials

[0021] Table 1.2 Basic properties of materials

[0022] Table 2 Plant growth under different conditions

[0023] Table 3 Strength of biopolymer-biochar improved vegetation soil

[0024] Test methods and relevant standards: The basic properties test of soil refers to the engineering classification standard of soil "GB / T 50145-2007" and the geotechnical test method standard "GB / T 50123-2019", and the shear strength test is based on the geotechnical test method standard "GB / T 50123-2019".

[0025] From the above comparison data, it can be seen that the combined effect of biopolymer and biochar in the present invention can effectively promote the growth of slope plants and improve the strength of soil. Under the joint action of biopolymer and biochar, the germination rate, plant height and root length of plants have been significantly improved. Compared with the blank control group, the germination rate increased by 13.2%, the plant height increased by 36.9% in 30 days, and the root length increased by 47.8%, and the growth of plants was effectively improved. At the same time, the shear strength of the slope soil increased significantly. Compared with the unimproved soil, the shear strength of the soil under different positive stresses can be increased by 2-3 times. Under the reinforcement of this method, the cohesion and internal friction angle of the soil are effectively improved, thereby effectively improving the stability of the slope. Among them, the experimental group with gellan gum and wood biochar dung biochar mixture as soil additives and tall fescue as slope protection plants has the best slope protection effect, and the optimal addition ratio of soil, biopolymer and biochar is 100:0.3:3. The biopolymers and biochar used in this method are both eco-friendly materials that will not pollute the environment. Among them, biochar is a negative carbon material. The large-scale use of biochar can provide favorable support for my country's carbon storage industry.

[0026] It should be noted that the above content only illustrates the technical idea of ​​the present invention and cannot be used to limit the protection scope of the present invention. For ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications all fall within the protection scope of the claims of the present invention.

Claims

1. An ecological slope reinforcement method combining biopolymer and biochar, characterized by: The following steps are involved: Step 1) digging plant planting holes with a volume of 10*10*10cm at equal intervals on the surface of the slope to be reinforced; Step 2) using a dry mixing method to mix an appropriate amount of slope soil with biopolymer and biochar in proportion to form a uniform solid mixture; Step 3) The solid mixture is then mixed with water and stirred evenly, and the stirred soil is placed in a sealed container for curing until the water and the biopolymer fully react to form a viscose gel, and finally a uniform improved soil is prepared; Step 4) Fill the prepared improved soil into the plant planting hole, and sow the plant seeds soaked in clean water for two hours into the plant planting hole; Step 5) Regularly water and maintain the plant planting holes and record the growth of the plants; Step 6) After 30 days, use a ring cutter to take the original soil from the planting hole and test its shear strength.

2. The method for ecological slope reinforcement using biopolymer combined with biochar according to claim 1, characterized in that: The slope soil in step 2) is mixed with biopolymer and biochar in a ratio of 100:0.1-0.5:1-6.

3. The method for ecological slope reinforcement using biopolymer combined with biochar according to claim 1, characterized in that: The water in step 3) accounts for 17.3% of the soil mass.

4. The method for ecological slope reinforcement using biopolymer combined with biochar according to claim 1, characterized in that: Step 2) The biopolymer is gellan gum.

5. The method for ecological slope reinforcement using biopolymer combined with biochar according to claim 1, characterized in that: Step 2) The biochar comprises a mixture of one or more of bamboo biochar and livestock manure biochar.

6. The method for ecological slope reinforcement using biopolymer combined with biochar according to claim 1, characterized in that: Step 4) The plant seeds are Bermuda grass or tall fescue seeds.

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