Microbial improver for loess-shaped salinized soil and application of microbial improver in ecological restoration of side slope

Abstract

The invention discloses a loess-shaped salinized soil microbial modifier and application thereof in slope ecological restoration, the microbial modifier comprises a first modifier and a second modifier, and a preparation method of the first modifier comprises the following steps: S-A1, preparing a first cementing liquid; s-A2, preparation of a first improver; a preparation method of the second modifier comprises the following steps: S-B1, preparing a second cementing liquid; preparing S-B2 and a second improver; the microbial bacterial liquid is bacillus pasteurii. According to the invention, two different modifying agents are used as main components of the modifying agent, the first modifying agent effectively enhances gas diffusion in soil, improves the content of nutrient elements in the soil, achieves the purpose of ecological improvement, and plays an auxiliary role in rain prevention and seepage prevention; and the second modifier enhances the strength of the internal structure of the side slope and is matched with the fixing hole positions to achieve the purpose of reinforcing the side slope, and finally a set of complete side slope ecological restoration and protection integrated system is formed.

Description

Technical Field

[0001] The invention relates to the technical field of soil ecological management, and in particular to a loess-like saline soil microbial improver and application thereof in slope ecological restoration. Background Art

[0002] Loess-like saline soil is a special soil that is similar to loess in structure and composition, and contains a large amount of soluble salt. Therefore, it not only has the characteristics of loess, such as strong water permeability, collapsibility, and significantly reduced strength when exposed to water, but also has the three major unfavorable engineering characteristics of saline soil, namely salt swelling, dissolution and corrosion. Therefore, this type of soil is very harmful to soil tools, especially to slope engineering.

[0003] Slope protection projects generally use external engineering measures such as face walls, slope foot supports, anchor frames, geomembrane waterproofing, and internal slope soil improvement measures such as lime and fly ash. These measures are not only energy-intensive, but the chemicals such as cement and lime used can also cause environmental damage. Therefore, it is very important to find a suitable alternative to traditional slope protection projects for slope protection.

[0004] In recent years, microbial modifiers have received a lot of attention in geotechnical protection technology. They are not only environmentally friendly and pollution-free, but also low-cost and effective in protection. They are the focus of current research. However, the impact of microbial modifiers on soil slope stability needs further study.

[0005] The invention patent with the patent publication number CN111424689A discloses a method for protecting soil slopes from rainwater erosion by using phosphogypsum and microorganisms. The method comprises: (1) placing Bacillus pasteurianus in a culture medium to prepare a microbial solution, and mixing urea, calcium chloride and water to prepare a binder; (2) mixing the mixture, the microbial solution and water evenly, and then adding the binder and water to prepare an improved mixture slurry; (3) using a wet spraying method, spraying the improved mixture slurry onto the slope surface twice, and then mixing the improved mixture slurry with grass seeds evenly, spraying it onto the slope surface once, covering it with non-woven fabric and tying it firmly, and spraying water for maintenance every day. The method can meet the requirements of soil slopes such as loess and gravel soil for rainwater erosion resistance and slope ecological greening protection, and can consume phosphogypsum, reduce the occupation of cultivated land, and the effective phosphorus can promote plant growth. The phosphogypsum improved by microorganisms can realize the solidification of harmful elements and reduce pollution to the environment. However, the microbial modifier in this method is relatively single, and the effect of the simple covering method used in its application is also relatively limited. Summary of the invention

[0006] In view of the above-mentioned problems, the present invention provides a loess-like saline soil microbial improver and its application in slope ecological restoration.

[0007] The technical solution of the present invention is:

[0008] A loess-like saline soil microbial improver, the microbial improver comprising a first improver and a second improver, the first improver and the second improver are stored separately, and the usage ratio of the first improver and the second improver is 1-2:1-3;

[0009] The preparation method of the first improver is:

[0010] S-A1, preparation of the first cementing liquid: by weight, take 1-1.4 parts of urea powder and 2-2.2 parts of calcium chloride powder, mix them, add 20-21 parts of distilled water, stir for 20-30 minutes, and obtain the first cementing liquid;

[0011] S-A2, preparation of the first improver: 2-3 parts of the first binder solution and 0.1-0.2 parts of the microbial solution are mixed, and then 4-6 parts of metakaolin powder are gradually added, and stirred continuously to obtain the first improver;

[0012] The preparation method of the second improver is:

[0013] S-B1, preparation of the second cementing liquid: by weight, take 1-1.5 parts of urea powder and 2.2-2.5 parts of modified MgO-NH 2 powder, add 20 to 22 parts of distilled water after mixing, and stir for 20 to 30 minutes to obtain a second cementing liquid;

[0014] S-B2, preparation of the second improver: 2-3 parts of the second binder and 0.1-0.2 parts of the microbial liquid are mixed, and then 5-7 parts of metakaolin powder are gradually added, and stirred continuously to obtain the second improver;

[0015] The microbial culture solution is the concentration OD 600 2±0.05 for Bacillus pasteurianus.

[0016] Furthermore, the urea powder, calcium chloride powder and metakaolin powder are all sieved through a 100-mesh sieve.

[0017] Note: By further optimizing the particle sizes of urea powder, calcium chloride powder and metakaolin powder, it is ensured that the first modifier and the second modifier are evenly dispersed during preparation, and the effect is better.

[0018] Furthermore, the stirring method is magnetic stirring, the stirring speed is 300-500 rpm, and the addition speed of the metakaolin powder is 10-60 g / s.

[0019] Note: By optimizing the stirring mode and stirring speed, the first modifier and the second modifier are ensured to be evenly mixed and dispersed during preparation, and by controlling the addition speed of the metakaolin powder, it is ensured to be evenly mixed with other substances in the raw materials.

[0020] Furthermore, the modified MgO-NH 2 The powder is prepared by:

[0021] 1-2 parts of nano-MgO powder are placed in 10-15 parts of isopropanol solution with a mass concentration of 60-80% for ultrasonic dispersion for 20-30 minutes, and then 0.5-1 parts of 3-aminopropyltriethoxysilane are gradually added dropwise, heated to 65-70° C. in a water bath and stirred continuously for 6-8 hours, and then centrifuged to obtain a solid product, and the solid product is washed 2-3 times with anhydrous ethanol and then dried to obtain a modified MgO-NH 2 powder.

[0022] Description: By using modified MgO-NH 2 The powder is used as the main component of the second improver, and the Mg 2+ It exchanges with cations in soil particles and adsorbs on the surface of kaolin and loess-like saline soil, reducing the thickness of the electric layer of loess-like saline soil particles, promoting the connection and agglomeration of loess-like saline soil and kaolin, and enhancing the soil strength between the two.

[0023] Furthermore, the dropping speed of the 3-aminopropyltriethoxysilane is 1-5 mL / s, the drying temperature is 55-60° C., the drying time is 12-24 h, the stirring method is magnetic stirring, and the stirring speed is 300-500 rpm.

[0024] Description: By optimizing and adjusting the modified MgO-NH 2 Details of the powder preparation parameters to prepare the modified MgO-NH 2 The powder is prepared uniformly and densely with good performance.

[0025] Furthermore, the preparation method of the microbial culture liquid is as follows: culturing Bacillus pasteurianus in a mixed culture medium containing 5-8 g / L sodium chloride, 18-20 g / L urea, 5-6 g / L soy peptone and 14-16 g / L casein, maintaining the humidity at 88-90% and the temperature at 30±0.5°C, performing shaking expansion culture in a constant temperature incubator for 34-36 hours, centrifuging and removing the mixed culture medium to obtain a microbial culture liquid, and adding distilled water to control the concentration OD of the microbial culture liquid. 600 It is 2±0.05.

[0026] The present invention also provides the use of the loess-like saline soil microbial improver in slope ecological restoration. The microbial improver is used in the ecological restoration and protection of loess-like saline soil slopes. The specific method is:

[0027] S1. Setting of fixed holes: Preset fixed holes on the surface of the slope to be cared for. The arrangement of the fixed holes is a diamond four-point method, that is, four fixed holes form a diamond area, and multiple diamond areas are adjacent to each other up and down and front and back to form the entire fixed hole network. The depth of the fixed holes is 20 to 60 cm, and the spacing between adjacent fixed holes in the diamond area is 1 to 5 m. The diameter of the fixed holes is R, which has the following relationship with the angle a of the slope to be cared for and the length s of the slope surface:

[0028] R=2.5×s—0.05×a

[0029] Among them, the unit of R is cm, the unit of a is °, and the unit of s is m;

[0030] S2. Mixing the first improver: First, cover the first improver on the surface of the slope to be maintained, and then mix it with the soil on the surface of the slope to be maintained. The addition amount of the first improver is 300-400g / m 3 , the stirring depth is 10 to 15 cm;

[0031] S3, second improver coverage: 200-300g / m 3 The second improver is added in an amount to cover the first improver after stirring;

[0032] S4. Fixed hole injection: inject the remaining second improver evenly into the fixed holes of each rhombus area.

[0033] Furthermore, after the completion of S4, it is necessary to reserve a drainage channel on the slope surface, the extension direction of the drainage channel is perpendicular to the long diagonal line in the diamond area, and a diamond area is separated between two adjacent drainage channels. Then, the slope surface is maintained by covering the slope surface with non-woven fabric and spraying water twice a day at a spraying volume of 0.4-0.6L / m 3 , which lasts for 7 to 14 days, and then shrubs are planted inside the diamond-shaped areas where there are no drainage channels, and herbaceous plants are planted inside the diamond-shaped areas where there are drainage channels.

[0034] Preferably, before the implementation of S1, the surface of the slope to be maintained needs to be leveled and debris removed, the shrub plants are one or more of Amorpha fruticosa, Sabina vulgaris or Caragana microphylla, and the herbaceous plants are one or more of Tall Fescue, Bermuda grass, Bahiagrass or White Clover.

[0035] The beneficial effects of the present invention are:

[0036] (1) The loess-like saline soil microbial improver of the present invention is aimed at the ecological restoration of loess-like saline soil slopes. Two different improvers are used as the main components of the improver. The first improver is used as an improver that is turned over and mixed inside the slope surface. It is mainly composed of microorganisms + calcium chloride + urea + a small amount of kaolin, which effectively enhances the gas diffusion in the soil, improves the content of nutrient elements in the soil, achieves the purpose of ecological improvement, and plays an auxiliary role in rain and seepage prevention; the second improver is used as an improver that covers the surface and penetrates into the slope. It is mainly composed of microorganisms + modified MgO-NH 2 + urea + a large amount of kaolin is mainly used to enhance the internal structural strength of the slope, and cooperate with fixed holes to achieve the purpose of slope reinforcement, and finally form a complete integrated system of slope ecological restoration and protection.

[0037] (2) The loess-like saline soil microbial improver of the present invention adopts modified MgO-NH 2 The powder is used as the main component of the second improver, and the Mg 2+ It exchanges with cations in soil particles and adsorbs on the surface of kaolin and loess-like saline soil, reducing the thickness of the electric layer of loess-like saline soil particles, promoting the connection and agglomeration of loess-like saline soil and kaolin, and enhancing the soil strength between the two.

[0038] (3) The application of the loess-like saline soil microbial improver of the present invention in the ecological restoration of slopes further designs the fixed hole network of the slope and a series of parameters thereof, wherein the diameter R of the fixed hole is correlated with the angle a and the slope length s of the slope to be maintained, and an empirical formula for the correlation is given, so that the fixed hole positions can be reasonably adjusted according to the slope structure, thereby enhancing the stability and sustainability of the fixed hole network and improving the loess-like saline soil slope. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 It is a schematic diagram of the fixed hole positions and the planar structure of the drainage channel for the application of the loess-like saline soil microbial modifier of the present invention in the ecological restoration of the slope;

[0040] Figure 2 is a schematic diagram of the moisture content of each case in Experimental Example 1 of the present invention;

[0041] Figure 3 Schematic diagram of dry density of each case in Experimental Example 1 of the present invention. DETAILED DESCRIPTION

[0042] Example 1

[0043] A loess-like saline soil microbial improver, the microbial improver comprises a first improver and a second improver, the first improver and the second improver are stored separately, and the usage ratio of the first improver and the second improver is 1:1;

[0044] The preparation method of the first improver is:

[0045] S-A1, preparation of the first cementing liquid: by weight, take 1.2 parts of urea powder and 2 parts of calcium chloride powder, mix them, add 20 parts of distilled water, and stir for 25 minutes to obtain the first cementing liquid;

[0046] S-A2, preparation of the first improver: 2.5 parts of the first binder solution and 0.15 parts of the microbial solution were mixed, and then 5 parts of the metakaolin powder were gradually added, and the mixture was stirred continuously to obtain the first improver;

[0047] The preparation method of the second improver is:

[0048] S-B1, preparation of the second cementing liquid: by weight, take 1.2 parts of urea powder and 2.3 parts of modified MgO-NH 2 powder, add 21 parts of distilled water after mixing, and stir for 25 minutes to obtain a second cementing liquid;

[0049] Modified MgO-NH 2 The powder is prepared by:

[0050] By weight, 1.5 parts of nano-MgO powder were placed in 12 parts of isopropanol solution with a mass concentration of 70% and ultrasonically dispersed for 25 minutes, and then 0.8 parts of 3-aminopropyltriethoxysilane was gradually added dropwise at a dropping rate of 3 mL / s. The temperature was raised to 66° C. and heated in a water bath with continuous stirring for 7 hours. The solid product was then centrifuged to obtain a solid product. The solid product was washed 3 times with anhydrous ethanol and then dried at a drying temperature of 58° C. for 20 hours to obtain a modified MgO-NH 2 powder;

[0051] S-B2, preparation of the second improver: 2.5 parts of the second binder and 0.15 parts of the microbial liquid were mixed, and then 6 parts of the metakaolin powder were gradually added while stirring continuously to obtain the second improver;

[0052] In the above steps, urea powder, calcium chloride powder and metakaolin powder were all sieved through a 100-mesh sieve, the stirring method was magnetic stirring, the stirring speed was 400 rpm, and the addition rate of metakaolin powder was 40 g / s;

[0053] Microbial culture is the concentration of the culture OD 600 2 of Bacillus pasteurianus.

[0054] The preparation method of the microbial culture liquid is as follows: Bacillus pasteurianus is cultured in a mixed culture medium containing 6 g / L sodium chloride, 19 g / L urea, 5.5 g / L soy peptone and 15 g / L casein, the humidity is maintained at 89% and the temperature is 30°C, and the culture is expanded by shaking in a constant temperature incubator for 35 hours, and the mixed culture medium is removed by centrifugation to obtain the microbial culture liquid, and the concentration OD is measured. 600 Detection, add distilled water to control the concentration of microbial solution OD 600 is 2.

[0055] Example 2

[0056] The difference between this embodiment and embodiment 1 is that the preparation method of the first improver is different.

[0057] The preparation method of the first improver is:

[0058] S-A1, preparation of the first cementing liquid: take 1 part of urea powder and 2 parts of calcium chloride powder by weight, mix them, add 20 parts of distilled water, stir for 20 minutes, and stir at a speed of 300 rpm to obtain the first cementing liquid;

[0059] S-A2, preparation of the first improver: take 2 parts of the first binder and 0.1 parts of the microbial liquid and mix them, then gradually add 4 parts of kaolin powder, the addition rate of kaolin powder is 10g / s, and keep stirring at a speed of 500rpm to obtain the first improver.

[0060] Example 3

[0061] The difference between this embodiment and embodiment 1 is that the preparation method of the first improver is different.

[0062] The preparation method of the first improver is:

[0063] S-A1, preparation of the first cementing liquid: by weight, take 1.4 parts of urea powder and 2.2 parts of calcium chloride powder, mix, add 21 parts of distilled water, stir for 30 minutes, and stir at a speed of 500 rpm to obtain the first cementing liquid;

[0064] S-A2, preparation of the first improver: mix 3 parts of the first binder liquid and 0.2 parts of the microbial liquid, then gradually add 6 parts of kaolin powder at a rate of 60 g / s, and stir continuously at a speed of 300 rpm to obtain the first improver.

[0065] Example 4

[0066] The difference between this embodiment and embodiment 1 is that the preparation method of the second improver is different.

[0067] S-B1, preparation of the second cementing liquid: by weight, take 1 part of urea powder and 2.2 parts of modified MgO-NH 2 powder, add 20 parts of distilled water after mixing, stir for 20 minutes at a stirring speed of 500 rpm to obtain a second cementing liquid;

[0068] S-B2, preparation of the second improver: take 2 parts of the second binder and 0.1 parts of the microbial liquid and mix them, then gradually add 5 parts of kaolin powder, the addition rate of kaolin powder is 10g / s, and keep stirring at a speed of 300rpm to obtain the second improver.

[0069] Example 5

[0070] The difference between this embodiment and embodiment 1 is that the preparation method of the second improver is different.

[0071] S-B1, preparation of the second cementing liquid: by weight, take 1.5 parts of urea powder and 2.5 parts of modified MgO-NH 2 powder, add 22 parts of distilled water after mixing, stir for 30 minutes at a stirring speed of 300 rpm to obtain a second cementing liquid;

[0072] S-B2, preparation of the second improver: take 3 parts of the second binder and 0.2 parts of the microbial liquid and mix them, then gradually add 7 parts of kaolin powder, the addition rate of kaolin powder is 60g / s, and keep stirring at a speed of 500rpm to obtain the second improver.

[0073] Note: In Examples 1 to 5, the examples of improver preparation parameters given are multiple optional items within the optimal parameter range, and the same technical effect can be achieved by selecting any set of parameters.

[0074] Example 6

[0075] The difference between this embodiment and embodiment 1 is that: modified MgO-NH 2 Powders are prepared in different ways.

[0076] By weight, 1 part of nano-MgO powder was placed in 10 parts of isopropanol solution with a mass concentration of 60% and ultrasonically dispersed for 20 minutes, and then 0.5 parts of 3-aminopropyltriethoxysilane was gradually added dropwise at a dropping rate of 1 mL / s, and the temperature was raised to 70°C for heating in a water bath and stirred continuously for 6 hours, and then centrifuged to obtain a solid product, and the solid product was washed twice with anhydrous ethanol and then dried at a drying temperature of 55°C for 24 hours to obtain a modified MgO-NH 2 powder.

[0077] Example 7

[0078] The difference between this embodiment and embodiment 1 is that: modified MgO-NH 2 Powders are prepared in different ways.

[0079] By weight, 2 parts of nano-MgO powder were placed in 15 parts of isopropanol solution with a mass concentration of 80% and ultrasonically dispersed for 30 minutes, and then 1 part of 3-aminopropyltriethoxysilane was gradually added dropwise at a dropping rate of 5 mL / s. The temperature was raised to 65° C. and heated in a water bath with continuous stirring for 8 hours. The solid product was then centrifuged to obtain a solid product. The solid product was washed 3 times with anhydrous ethanol and then dried at a drying temperature of 60° C. for 12 hours to obtain a modified MgO-NH 2 powder.

[0080] Note: In the parameter examples given in Examples 6 and 7, when the amount of nano-MgO powder added is greater, the ultrasonic dispersion time is appropriately extended, and the dripping speed of 3-aminopropyltriethoxysilane can be appropriately increased. The higher the water bath heating temperature, the shorter the stirring time can be appropriately, and the higher the drying temperature, the shorter the drying time can be appropriately.

[0081] Example 8

[0082] The difference between this embodiment and embodiment 1 is that the preparation method of the microbial liquid is different.

[0083] The preparation method of the microbial culture liquid is as follows: Bacillus pasteurianus is cultured in a mixed culture medium containing 5 g / L sodium chloride, 18 g / L urea, 5 g / L soy peptone and 14 g / L casein, the humidity is maintained at 88% and the temperature is 29.5°C, and the culture is expanded by shaking in a constant temperature incubator for 34 hours, and the mixed culture medium is removed by centrifugation to obtain the microbial culture liquid, and the concentration OD is measured. 600 Detection, add distilled water to control the concentration of microbial solution OD 600 is 1.95.

[0084] Example 9

[0085] The difference between this embodiment and embodiment 1 is that the preparation method of the microbial liquid is different.

[0086] The preparation method of the microbial culture liquid is as follows: Bacillus pasteurianus is cultured in a mixed culture medium containing 8 g / L sodium chloride, 20 g / L urea, 6 g / L soy peptone and 16 g / L casein, the humidity is maintained at 90% and the temperature is 30.5°C, and the culture is expanded by shaking in a constant temperature incubator for 36 hours, and the mixed culture medium is removed by centrifugation to obtain the microbial culture liquid, and the concentration OD is measured. 600Detection, add distilled water to control the concentration of microbial solution OD 600 is 2.05.

[0087] Note: In Examples 8 and 9, the examples of preparation parameters of the microbial culture liquid given are multiple optional items within the optimal parameter range, and the same technical effect can be achieved by selecting any set of parameters.

[0088] Example 10

[0089] This embodiment is the application of the loess-like saline soil microbial modifier of Example 1 in the ecological restoration of the slope. The microbial modifier is applied to the ecological restoration and protection of the loess-like saline soil slope. The specific method is:

[0090] S1, fixed hole setting: Figure 1 As shown, fixed holes are preset on the surface of the slope to be maintained, and the arrangement of the fixed holes is a diamond four-point method, that is, four fixed holes surround a diamond area, and multiple diamond areas are adjacent to each other up and down and front and back to form the entire fixed hole network. The depth of the fixed holes is 40cm, and the spacing between adjacent fixed holes in the diamond area is 2m. The diameter of the fixed holes is R, which has the following relationship with the angle a of the slope to be maintained and the length s of the slope:

[0091] R=2.5×s—0.05×a

[0092] Among them, the unit of R is cm, the unit of a is °, and the unit of s is m;

[0093] Before S1 is implemented, the slope surface to be maintained needs to be leveled and debris removed;

[0094] S2. Mixing the first improver: First, cover the first improver on the surface of the slope to be maintained, and then mix it with the soil on the surface of the slope to be maintained. The addition amount of the first improver is 350g / m 3 , the stirring depth is 12cm;

[0095] S3, second improver covering: 250g / m 3 The second improver is added in an amount to cover the first improver after stirring;

[0096] S4. Fixed hole injection: inject the remaining second improver evenly into the fixed holes of each rhombus area.

[0097] After S4 is completed, it is necessary to reserve drainage channels on the slope surface. The extension direction of the drainage channels is perpendicular to the long diagonal line in the diamond area, and a diamond area is separated between two adjacent drainage channels. Then the slope surface is maintained by covering it with non-woven fabric and spraying water twice a day at a rate of 0.5L / m 3, which lasted for 10 days, and then shrubs were planted inside the diamond-shaped areas where there were no drainage channels, and herbaceous plants were planted inside the diamond-shaped areas where there were drainage channels. The shrubs were juniper and caragana, and the herbaceous plants were bermudagrass and bahia grass.

[0098] Embodiment 11

[0099] The difference between this embodiment and embodiment 10 is that: S1, the setting parameters of the fixed hole positions in the fixed hole position setting are different.

[0100] The depth of the fixing holes is 20 cm, and the distance between adjacent fixing holes in the diamond area is 1 m.

[0101] Example 12

[0102] The difference between this embodiment and embodiment 10 is that: S1, the setting parameters of the fixed hole positions in the fixed hole position setting are different.

[0103] The depth of the fixed holes is 60 cm, and the distance between adjacent fixed holes in the diamond area is 5 m.

[0104] Note: In Example 11 and Example 12, the setting parameters of the fixed hole positions are related to the length and area of ​​the slope. When the area of ​​the slope is larger, the depth of the fixed hole positions is deeper, and the spacing between adjacent fixed hole positions in the diamond area is larger.

[0105] Example 13

[0106] The difference between this embodiment and embodiment 10 is that:

[0107] S2. Mixing the first improver: First, cover the first improver on the surface of the slope to be maintained, and then mix it with the soil on the surface of the slope to be maintained. The addition amount of the first improver is 300g / m 3 , the stirring depth is 10cm;

[0108] S3, second improver coverage: 200g / m 3 The second improver is added in an amount that covers the first improver after stirring.

[0109] Embodiment 14

[0110] The difference between this embodiment and embodiment 10 is that:

[0111] S2. Mixing the first improver: First, cover the first improver on the surface of the slope to be maintained, and then mix it with the soil on the surface of the slope to be maintained. The addition amount of the first improver is 400g / m 3 , the stirring depth is 15cm;

[0112] S3, second improver coverage: 300g / m3 The second improver is added in an amount that covers the first improver after stirring.

[0113] Note: In Example 13 and Example 14, the mixing depth of the improver is related to the length and area of ​​the slope. When the area of ​​the slope is larger, the coverage amount is larger and the mixing depth is deeper. At the same time, the usage ratio of the first improver and the second improver is controlled to be 1:1. Therefore, the sum of the second improver for filling the fixed hole and the second improver for covering is equal to the usage of the first improver.

[0114] Embodiment 15

[0115] The difference between this embodiment and embodiment 1 and embodiment 10 is that:

[0116] The dosage ratio of the first improver to the second improver is 2:1.5, wherein the addition amount of the first improver is 400g / m 3 In S4, the second improver covers the first improver after stirring, and the amount of the second improver added is 240g / m 3 The remaining second improver is used in S3, which is suitable for fixing shallow holes with small hole diameters.

[0117] Example 16

[0118] The difference between this embodiment and embodiment 1 and embodiment 10 is that:

[0119] The dosage ratio of the first improver to the second improver is 1:2.6, wherein the addition amount of the first improver is 300g / m 3 In S4, the second improver covers the first improver after stirring, and the amount of the second improver added is 280g / m 3 The remaining second improver is used in S3, which is suitable for fixing holes with deeper holes and larger diameters.

[0120] Embodiment 17

[0121] The difference between this embodiment and embodiment 10 is that:

[0122] After S4 is completed, water is sprayed twice a day at a rate of 0.4L / m 3 , which lasted for 14 days, and then shrubs were planted inside the diamond-shaped areas without drainage channels, and herbaceous plants were planted inside the diamond-shaped areas with drainage channels. The shrubs were Amorpha fruticosa and the herbaceous plants were tall fescue.

[0123] Embodiment 18

[0124] The difference between this embodiment and embodiment 10 is that:

[0125] After S4 is completed, water is sprayed twice a day at a rate of 0.6L / m3 , which lasted for 7 days, and then shrubs were planted inside the diamond-shaped areas without drainage channels, and herbaceous plants were planted inside the diamond-shaped areas with drainage channels. The shrubs were Caragana and the herbaceous plants were white clover.

[0126] Note: In Example 17 and Example 18, the amount of water sprayed and the plants planted can be reasonably adjusted according to the local climate, rainfall and humidity.

[0127] Experimental Example 1

[0128] In this experimental example, we mainly studied and analyzed different modified MgO-NH 2 The effect of the second modifier prepared by adding powder on the consolidation strength of loess-like saline soil. In an indoor test, the second modifier in Example 1 was mixed with loess-like saline soil in a mass ratio of 1:1, compacted into a cylinder using a static pressure membrane, and its dry density and moisture content were tested after curing. At the same time, it was compared with the comparative example, wherein the comparative example 1 was not added with modified MgO-NH 2 Powder, comparative example 2 is to add 1 part of modified MgO-NH 2 Powder, comparative example 3 is to add 3 parts of modified MgO-NH 2 The remaining steps are the same as those in Example 1. The moisture content and dry density after curing for 12 hours are as follows: Figure 2 and Figure 3 shown.

[0129] It can be seen that changing the modified MgO-NH 2 The amount of powder added has a great influence on the consolidation strength of loess-like saline soil as the second modifier. Since the hydrolysis reaction of urea induced by microorganisms requires water, the modified MgO-NH 2 The addition of powder can accelerate this process and modify MgO-NH 2 The powder also reacts with water inside the metakaolin and loess-like saline soil, and the produced product has expansion and cementation properties, thereby reducing the moisture content and dry density of the entire soil system, thereby improving the consolidation strength, and has a good effect when used as a fixed hole position;

[0130] In comparative example 3, the modified MgO-NH 2 The amount of powder added has little effect on the moisture content and dry density of the soil system, so it is appropriate to select the addition range given in the present invention.

[0131] Experimental Example 2

[0132] In this experimental example, we mainly study and analyze the actual effect of the application method in Example 10. We conducted tests in bare land on a solid slope of sufficient length, selected 5m*5m as a test section, the slope angle was 52°, and correspondingly R=2.5*5-0.05*52=9.9cm. The first test section adopted the method in Example 10, and the first improver was added to the second test section without using the second improver. The second improver was added to the third test section without using the first improver. After the maintenance was completed, the rainfall was set to 100mm / d, and rainfall was simulated for 7 consecutive days. The permeability coefficient and vertical displacement of the slope were tested, and the plant species diversity was detected after 3 months. The experimental results are shown in Table 1.

[0133] Table 1 Permeability coefficient and vertical displacement of the slope in each case

[0134]

[0135] It can be seen from the data in Table 1 that when only the first modifier is added, the permeability coefficient is higher, and when only the second modifier is added, the permeability coefficient is lower. The lower the permeability coefficient, the stronger its ability to resist rainwater erosion. The modified MgO-NH 2 Powder addition has a strong ability to consolidate the soil and reduce the risk of vertical displacement, but it has limited help for plant growth and development. Therefore, it is recommended to be used in fixed holes and surface covering.

[0136] The first improver uses traditional calcium chloride as an auxiliary additive, so that the calcium carbonate precipitates generated by microorganisms in the loess-like saline soil can fill the pores of the soil, which is helpful for the diversity of plant species. At the same time, it strengthens the connection between the metakaolin and loess-like saline soil particles, has a high permeability coefficient, and can help prevent vertical displacement. Therefore, a layer of the second improver needs to be covered on top.

[0137] The two types of amendments have different nutritional components. Only when they are applied together can the elements required for plant growth be diversified, and plant species diversity develop faster and more rapidly. Therefore, the combined application of the first amendment and the second amendment can achieve the best ecological restoration effect.

Claims

1. A loess-like saline soil microbial improver, characterized in that: The microbial improver includes a first improver and a second improver, the first improver and the second improver are stored separately, and the usage ratio of the first improver and the second improver is 1-2:1-3; The preparation method of the first improver is: S-A1, preparation of the first cementing liquid: by weight, take 1-1.4 parts of urea powder and 2-2.2 parts of calcium chloride powder, mix them, add 20-21 parts of distilled water, stir for 20-30 minutes, and obtain the first cementing liquid; S-A2, preparation of the first improver: 2-3 parts of the first binder and 0.1-0.2 parts of the microbial solution are mixed, and then 4-6 parts of metakaolin powder are gradually added, and stirred continuously to obtain the first improver; The preparation method of the second improver is: S-B1, preparation of the second cementing liquid: by weight, take 1-1.5 parts of urea powder and 2.2-2.5 parts of modified MgO-NH2 powder, mix them, add 20-22 parts of distilled water, stir for 20-30 minutes, and obtain the second cementing liquid; S-B2, preparation of the second improver: 2-3 parts of the second binder and 0.1-0.2 parts of the microbial liquid are mixed, and then 5-7 parts of metakaolin powder are gradually added, and stirred continuously to obtain the second improver; The microbial culture solution is the concentration OD 600 2±0.05 for Bacillus pasteurianus.

2. The loess-like saline soil microbial improver according to claim 1, characterized in that: The urea powder, calcium chloride powder and metakaolin powder are all sieved through a 100-mesh sieve.

3. The loess-like saline soil microbial improver according to claim 1, characterized in that: The stirring method is magnetic stirring, the stirring speed is 300-500 rpm, and the addition speed of the metakaolin powder is 10-60 g / s.

4. The loess-like saline soil microbial improver according to claim 1, characterized in that: The preparation method of the modified MgO-NH2 powder is: By weight, 1 to 2 parts of nano-MgO powder are placed in 10 to 15 parts of an isopropanol solution with a mass concentration of 60 to 80%, and ultrasonically dispersed for 20 to 30 minutes. Then, 0.5 to 1 part of 3-aminopropyltriethoxysilane is gradually added dropwise, and the temperature is raised to 65 to 70° C. for heating in a water bath and continuously stirred for 6 to 8 hours. Then, a solid product is obtained by centrifugation. The solid product is washed 2 to 3 times with anhydrous ethanol and then dried to obtain a modified MgO-NH2 powder.

5. The loess-like saline soil microbial improver according to claim 4, characterized in that: The dropping speed of the 3-aminopropyltriethoxysilane is 1-5 mL / s, the drying temperature is 55-60° C., the drying time is 12-24 h, the stirring method is magnetic stirring, and the stirring speed is 300-500 rpm.

6. The loess-like saline soil microbial improver according to claim 1, characterized in that: The preparation method of the microbial bacterial liquid comprises: culturing Bacillus pasteurianus in a mixed culture medium containing 5-8 g / L sodium chloride, 18-20 g / L urea, 5-6 g / L soy peptone and 14-16 g / L casein, maintaining the humidity at 88-90% and the temperature at 30±0.5°C, carrying out shaking expansion culture in a constant temperature incubator for 34-36 hours, centrifugally separating and removing the mixed culture medium to obtain a microbial bacterial liquid, and adding distilled water to control the concentration OD of the microbial bacterial liquid. 600 It is 2±0.

05.

7. Use of the loess-like saline soil microbial improver according to any one of claims 1 to 6 in slope ecological restoration, characterized in that: The microbial modifier is applied to the ecological restoration and protection of loess-like saline soil slopes, and the specific method is as follows: S1. Setting of fixed holes: Preset fixed holes on the surface of the slope to be cared for. The arrangement of the fixed holes is a diamond four-point method, that is, four fixed holes form a diamond area, and multiple diamond areas are adjacent to each other up and down and front and back to form the entire fixed hole network. The depth of the fixed holes is 20 to 60 cm, and the spacing between adjacent fixed holes in the diamond area is 1 to 5 m. The diameter of the fixed holes is R, which has the following relationship with the angle a of the slope to be cared for and the length s of the slope surface: R=2.5×s—0.05×a Among them, the unit of R is cm, the unit of a is °, and the unit of s is m; S2. Mixing the first improver: First, cover the first improver on the surface of the slope to be maintained, and then mix it with the soil on the surface of the slope to be maintained. The addition amount of the first improver is 300-400g / m 3 , the stirring depth is 10 to 15 cm; S3, second improver coverage: 200-300g / m 3 The second improver is added in an amount to cover the first improver after stirring; S4. Fixed hole injection: inject the remaining second improver evenly into the fixed holes of each rhombus area.

8. The use of the loess-like saline soil microbial modifier in slope ecological restoration according to claim 1, characterized in that: After S4 is completed, it is necessary to reserve drainage channels on the slope surface. The extension direction of the drainage channels is perpendicular to the long diagonal line in the diamond area, and a diamond area is separated between two adjacent drainage channels. Then the slope surface is maintained by covering the slope surface with non-woven fabric and spraying water twice a day at a spraying volume of 0.4-0.6L / m 3 , which lasts for 7 to 14 days, and then shrubs are planted inside the diamond-shaped areas where there are no drainage channels, and herbaceous plants are planted inside the diamond-shaped areas where there are drainage channels.

9. The use of the loess-like saline soil microbial modifier in slope ecological restoration according to claim 8, characterized in that: Before the implementation of S1, the surface of the slope to be maintained needs to be leveled and debris removed. The shrub plants are one or more of Amorpha fruticosa, Sabina vulgaris or Caragana korshinskii, and the herbaceous plants are one or more of Tall Fescue, Bermuda grass, Bahe grass or White Clover.

Images