Solidification method of aeolian sand

Abstract

The invention belongs to the technical field of civil engineering rock soil, and particularly relates to a solidification method of aeolian sand. According to the invention, calcium carbonate deposition is induced based on urease, the basalt fibers and the wool fibers are combined for reinforcement and solidification, the basalt fibers have the characteristics of high strength, high temperature resistance, corrosion resistance and the like, the wool fibers have good flexibility and tensile strength, and the basalt fibers and the wool fibers have good mechanical properties and environmental adaptability; the excellent performance can be maintained under different environmental conditions. The two kinds of fibers are combined with the EICP technology, the friction and curing effect between aeolian sand particles can be improved, the tensile property and shear resistance of cured aeolian sand are effectively improved, the strength and toughness of the cured aeolian sand are improved, the durability and aging resistance of a cured body are improved, and the service life of the cured body is prolonged. The cured body can still keep good mechanical properties and stability in the long-term use process, wind erosion damage is prevented, and the brittleness problem of the EICP technology in the process of curing aeolian sand is solved.

Description

Technical Field

[0001] The present invention belongs to the technical field of geotechnical engineering in civil engineering, and particularly relates to a method for solidifying aeolian sand. Background Art

[0002] In the field of civil engineering, aeolian sand, as a common soil type in desert areas, brings many challenges to engineering construction due to its characteristics such as fine particles, loose structure, and low bearing capacity. In terms of particle characteristics, aeolian sand particles are relatively uniform, mainly fine sand, with a particle size generally between 0.075 and 0.25 mm. The pores between particles are large, the cohesion is extremely low, and it is in a loose state. In terms of chemical composition, compared with other soil or sandy soils, the main components of aeolian sand are minerals such as quartz and feldspar, the organic matter content is extremely low, generally less than 1%, and the content of cementing substances such as calcium carbonate is also very small. In terms of pore structure, aeolian sand has large and connected pores, and the pore distribution is relatively uniform, resulting in difficult effective retention and uniform distribution of calcium carbonate precipitation in the pores. Therefore, compared with other soil or sandy soils, the solidification of aeolian sand is more difficult.

[0003] Traditional methods for solidifying aeolian sand include chemical solidification, physical solidification, and biological solidification, etc. However, these methods often have problems such as non - persistent solidification effects. In recent years, urease - induced calcium carbonate precipitation (EICP), as a new biochemical solidification technology, has received wide attention due to its good solidification effect and other advantages. The EICP technology catalyzes the hydrolysis of urea by urease to produce calcium carbonate, and the calcium carbonate deposits on the surface of soil particles, thereby enhancing the bonding force between soil particles and improving the strength and stability of the soil. However, the EICP technology also has some problems when solidifying aeolian sand, such as an increase in the brittleness of the solidified soil, which is prone to damage when subjected to external forces. Summary of the Invention

[0004] The purpose of the present invention is to provide a method for solidifying aeolian sand, which can avoid the increase in brittleness while solidifying aeolian sand.

[0005] In order to achieve the above purpose, the present invention provides the following technical solutions:

[0006] The present invention provides a method for solidifying aeolian sand, comprising the following steps:

[0007] (1) Mix the dried aeolian sand with basalt fiber and wool fiber to obtain a fiber - sand material;

[0008] (2) Compact the fiber - sand material in layers, then mix it with soybean urease solution and cementing solution, and let it stand.

[0009] Preferably, the particle size of the aeolian sand is not greater than 1.2 mm; the dry density of the aeolian sand is 1.40 - 1.70 g / cm 3 .

[0010] Preferably, the mass ratio of the total mass of the basalt fiber and the wool fiber to the mass of the aeolian sand is 0.25-1:99-99.75; the mass ratio of the basalt fiber to the wool fiber is 1-4:4-1.

[0011] Preferably, the lengths of the basalt fiber and the wool fiber are independently 3-12 mm.

[0012] Preferably, the number of layers of the layering is 3-6 layers.

[0013] Preferably, the compaction pressure is not higher than 800 kPa, the single compaction time is 1-2 s, and the compaction times are 36-60 times.

[0014] Preferably, the concentration of soybean urease in the soybean urease solution is 30-110 g / L; the mass ratio of the fiber sand material to the soybean urease solution is 1:40.8-67.2.

[0015] Preferably, the cementing solution includes an aqueous calcium chloride solution and an aqueous urea solution; the mass ratio of anhydrous calcium chloride in the aqueous calcium chloride solution to urea in the aqueous urea solution is 1-4:4-1; the concentration of the aqueous calcium chloride solution is 1-2 mol / L; the concentration of the aqueous urea solution is 1-2 mol / L; the pH value of the cementing solution is 8.00±0.05; the enzyme-cement ratio of the soybean urease solution to the cementing solution is 1-4:4-1.

[0016] Preferably, the second mixing is carried out by batch perfusion; the number of batch perfusion times is 1-10 times; the single perfusion of the batch perfusion is: perfusion of the soybean urease solution into the fiber sand material after layered compaction, perfusion of the aqueous calcium chloride solution after the soybean urease solution is immersed, and then perfusion of the aqueous urea solution.

[0017] Preferably, the standing time is 1-4 h.

[0018] The present invention provides a method for solidifying aeolian sand. Based on urease-induced calcium carbonate precipitation (EICP), the present invention combines basalt fiber (BF) and wool fiber (WF) for reinforcement and solidification. Basalt fiber has characteristics such as high strength, high temperature resistance, and corrosion resistance, while wool fiber has good flexibility and tensile strength. Both have good mechanical properties and environmental adaptability and can maintain their excellent properties under different environmental conditions. By combining these two fibers with EICP technology, the present invention can increase the friction and solidification between aeolian sand particles, effectively improve the tensile resistance and shear resistance of the solidified aeolian sand, enhance the strength and toughness of the solidified aeolian sand, and improve the durability and anti-aging performance of the solidified body, so that the solidified body can still maintain good mechanical properties and stability during long-term use, prevent wind erosion damage, overcome the brittleness problem of EICP technology in solidifying aeolian sand, thereby improving its overall performance, and providing a new solution for engineering construction in desert areas.

[0019] Compared with the traditional gravel covering method, the solidification method provided by the present invention reduces costs, effectively reduces the exploitation of natural resources, and conforms to the concept of sustainable development. Compared with the traditional cement solidification of aeolian sand, the solidification method provided by the present invention can achieve an ideal solidification effect without a long time. Compared with the MICP technology for solidifying aeolian sand, the solidification method provided by the present invention does not require the maintenance of microorganisms, is easy to operate, and shortens the cycle of the entire solidification process. In addition, basalt fiber and wool fiber, as natural materials, have the characteristics of being renewable and environmentally friendly, meeting the current social demand for green and environmentally friendly materials. The solidification method provided by the present invention improves the shear strength and bearing capacity of aeolian sand, enhances its ability to resist wind and sand erosion and flow, and is of great significance for improving the engineering properties of aeolian sand and preventing desertification, etc. Brief Description of the Drawings

[0020] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required to be used in the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0021] Figure 1 Process flow chart for preparing soybean urease solution;

[0022] Figure 2 Process flow chart for preparing cementing solution;

[0023] Figure 3 Process flow chart for the solidification method of the present invention;

[0024] Figure 4It is a bar chart showing the relationship between the unconfined compressive strength of EICP collaborative fiber-reinforced solidified aeolian sand in the embodiments of the present invention and fiber types; among them, (a) is the unconfined compressive strength diagram of fiber length FL = 3mm, EICP-BF and EICP-WF fiber types; (b) is the unconfined compressive strength diagram of FL = 6mm, EICP-BF and EICP-WF fiber types; (c) is the unconfined compressive strength diagram of FL = 9mm, EICP-BF and EICP-WF fiber types; (d) is the unconfined compressive strength diagram of FL = 12mm, EICP-BF and EICP-WF fiber types;

[0025] Figure 5 It is a bar chart showing the change of the unconfined compressive strength of EICP collaborative fiber-reinforced solidified aeolian sand in the embodiments of the present invention with the fiber length (FL); among them, (a) is the unconfined compressive strength diagram of fiber content accounting for the total mass of aeolian sand (FC) = 0.25%, FC = 0.50%, FC = 0.75%, FC = 1%, and EICP-BF fiber length; (b) is the unconfined compressive strength diagram of FC = 0.25%, FC = 0.50%, FC = 0.75%, FC = 1%, and EICP-WF fiber length;

[0026] Figure 6 It is a bar chart showing the change of the unconfined compressive strength of EICP collaborative fiber-reinforced solidified aeolian sand in the embodiments of the present invention with the fiber content (FC); among them, (a) is the unconfined compressive strength diagram of FL = 3mm, FL = 6mm, FL = 9mm, FL = 12mm, and EICP-BF fiber content (FC); (b) is the unconfined compressive strength diagram of FL = 3mm, FL = 6mm, FL = 9mm, FL = 12mm, and EICP-WF fiber content (FC);

[0027] Figure 7 It is the FL, FC and UCS regression analysis fitting model of the solidification method of the present invention; among them, (a) is the regression analysis surface of FL, FC and UCS (unconfined compressive strength) of EICP-BF solidified aeolian sand; (b) is the regression analysis surface of FL, FC and UCS of EICP-WF solidified aeolian sand; (c) is the fitting surface of the Poly model of EICP-BF solidified aeolian sand; (d) is the fitting surface of the Poly model of EICP-WF solidified aeolian sand. Detailed implementation manners

[0028] The present invention provides a method for solidifying aeolian sand, comprising the following steps:

[0029] (1) Mix the dried aeolian sand with basalt fiber and wool fiber to obtain fiber sand material;

[0030] (2) After compacting the fiber sand material layer by layer, it is mixed with soybean urease solution and cementing solution and then left standing.

[0031] In the present invention, dry aeolian sand is mixed with basalt fiber and wool fiber (denoted as the first mixing) to obtain fiber sand material. In the present invention, the drying temperature is preferably 120 - 150 °C, specifically it can be 130 °C or 140 °C, and the heat preservation drying time is preferably 24 - 30 h, specifically it can be 27 h; the drying equipment is preferably an oven.

[0032] In the present invention, the particle size of the aeolian sand is preferably not more than 1.2 mm, specifically it can be 0.5 mm, 0.7 mm or 0.9 mm; the dry density of the aeolian sand is preferably 1.40 - 1.70 g / cm 3 。

[0033] In the present invention, the mass ratio of the total mass of the basalt fiber and wool fiber to the mass of the aeolian sand is preferably 0.25 - 1:99 - 99.75, specifically it can be 0.3:99.7, 0.4:99.6, 0.5:99.5, 0.6:99.4, 0.7:99.3, 0.75:99.25, 0.8:99.2, 0.9:99.1.

[0034] In the present invention, the mass ratio of the basalt fiber and wool fiber is preferably 1 - 4:4 - 1, specifically it can be 1:1, 1:2, 1:3, 3:1 or 2:1.

[0035] In the present invention, the lengths (FL) of the basalt fiber and wool fiber are independently preferably 3 - 12 mm, specifically it can be 5 mm, 7 mm, 9 mm or 11 mm. The present invention significantly improves the curing effect by optimizing parameters such as the type, length and content of the fiber. In the present invention, through mixing, the fibers are evenly distributed in the aeolian sand.

[0036] In the present invention, when the fiber sand material is used for the laying of the road base, considering the relatively high requirements of the road base for the material stability and compressive strength, the dry density of the aeolian sand is more preferably 1.65 - 1.70 g / cm 3 , the mass ratio of the total mass of the basalt fiber and wool fiber to the mass of the aeolian sand is more preferably 0.60 - 0.75:99.25 - 99.40, and the lengths (FL) of the basalt fiber and wool fiber are independently more preferably 6 - 9 mm.

[0037] In the present invention, the first mixing is preferably stirring mixing; the stirring mixing is preferably mechanical stirring; the rotation speed of the stirring mixing is preferably 300 - 400 rpm, specifically it can be 350 rpm, and the stirring time is preferably 15 - 20 min, specifically it can be 17 min. Through the above stirring in the present invention, it is ensured that the fibers can be more evenly distributed in the dried aeolian sand, thereby improving the overall performance of the fiber sand material and meeting the requirements for material strength and stability in road bases, etc.

[0038] After obtaining the fiber sand material, in the present invention, the fiber sand material is compacted layer by layer and then mixed with soybean urease solution and cementing solution (denoted as the second mixing) and then left standing. In the present invention, the number of layers for the layering is preferably 3 - 6 layers, specifically it can be 4 layers or 5 layers.

[0039] In the present invention, when the solidified aeolian sand is used for building foundations, considering the complexity and uniformity requirements of the actual stress on the foundation, it is preferred to compact the fiber sand material in 5 - 6 layers.

[0040] In the present invention, the pressure for compaction is preferably not higher than 800 kPa, specifically it can be 200 kPa, 300 kPa, 400 kPa, 500 kPa, 600 kPa or 700 kPa, the single compaction time is preferably 1 - 2 seconds, specifically it can be 1 second or 1.5 seconds, and the number of compaction times is determined according to the characteristics of the sand material and the expected bearing effect, preferably 36 - 60 times, specifically the number of compaction times for the first layer is preferably 30 - 35 times, and starting from the second layer, it increases by 3 - 5 times for each subsequent layer; the compaction is preferably carried out in a sample preparation device; the bottom of the sample preparation device preferably has reserved small holes to facilitate the subsequent outflow of the EICP solution; the equipment for compaction is preferably a heavy compaction instrument. Through the above compaction in the present invention, it is ensured that the compaction degree of each layer is uniform and meets the requirements of actual engineering.

[0041] In the present invention, after compaction, it is preferably further included to perform scraping treatment on the obtained product; the equipment for scraping treatment is preferably a serrated scraper; the depth of the serrations of the serrated scraper is preferably 3 - 5 mm, specifically it can be 4 mm. In the present invention, scraping treatment is performed between layers, which can ensure that the scraping depth is uniform, effectively increasing the interfacial friction between layers, enabling better bonding between layers, and thus being closer to the actual building foundation.

[0042] In the present invention, the preparation method of the soybean urease solution is preferably: mixing crushed soybeans with water and then centrifuging; the crushing is preferably grinding; the water is preferably deionized water. The supernatant obtained by centrifuging in the present invention is the soybean urease solution.

[0043] In the present invention, the concentration of soybean urease in the soybean urease solution is preferably 30 - 110 g / L, specifically it can be 50 g / L, 70 g / L or 90 g / L.

[0044] In the present invention, the mass ratio of the fibrous sand material to the soybean urease solution is preferably 1:40.8 - 67.2, and specifically can be 1:42, 1:47, 1:52, 1:57, 1:62 or 1:67.

[0045] In the present invention, the cementing solution preferably comprises an aqueous calcium chloride solution and an aqueous urea solution; the mass ratio of anhydrous calcium chloride in the aqueous calcium chloride solution to urea in the aqueous urea solution is preferably 1 - 4:4 - 1, and specifically can be 1:1, 1:2, 1:3, 3:1 or 2:1; the concentration of the aqueous calcium chloride solution is preferably 1 - 2 mol / L, and specifically can be 1.0 mol / L, 1.2 mol / L, 1.4 mol / L, 1.6 mol / L or 1.8 mol / L; the concentration of the aqueous urea solution is preferably 1 - 2 mol / L, and specifically can be 1.0 mol / L, 1.2 mol / L, 1.4 mol / L, 1.6 mol / L or 1.8 mol / L; the pH value of the cementing solution is preferably 8.00 ± 0.05.

[0046] In the present invention, the enzyme - cement ratio (mass ratio) of the soybean urease solution to the cementing solution is preferably 1 - 4:4 - 1, and specifically can be 1:1, 1:2, 1:3, 1:4, 2:1, 2:3, 3:1, 3:2, 3:4, 4:1 or 4:3.

[0047] In the present invention, when the wind - deposited sand is solidified and used in the emergency engineering repair scenario, the enzyme - cement ratio is more preferably 3:2. Such conditions help to accelerate the reaction process, enabling the material to reach a relatively high strength in a short time and meeting the requirements of rapid repair for emergency engineering.

[0048] In the present invention, the second mixing is preferably carried out by batch perfusion; the number of batch perfusions is preferably 1 - 10 times, and specifically can be 3 times, 4 times, 5 times, 6 times or 7 times; the single - time perfusion for batch perfusion is preferably: perfusion of the soybean urease solution into the fibrous sand material after layered compaction, perfusion of the aqueous calcium chloride solution after complete immersion, and then perfusion of the aqueous urea solution.

[0049] In the present invention, the standing time is preferably 1 - 4 h, and specifically can be 2 h or 3 h.

[0050] In the present invention, after standing, it preferably further includes drying the obtained product; the drying temperature is preferably 70 - 120 °C, and specifically can be 70 °C, 80 °C, 90 °C, 100 °C, 110 °C or 120 °C, and the heat - preservation drying time is preferably 10 - 40 °C, and specifically can be 20 °C, 24 °C, 28 °C, 32 °C or 36 °C.

[0051] To further illustrate the present invention, the solutions of the present invention will be described in detail below in conjunction with the accompanying drawings and embodiments, but they should not be construed as limiting the protection scope of the present invention.

[0052] Example 1

[0053] A method for solidifying aeolian sand has a process as Figure 3 shown and includes the following steps:

[0054] (1) Use a vibrating screen with a vibration frequency of 50 Hz and an amplitude of 8 mm to ensure that the aeolian sand can pass through a 0.5 mm sieve more efficiently and evenly, effectively reducing the situation of blocking the sieve holes and improving the screening efficiency and quality; put it in an oven at 135 °C and bake for 27 h for later use.

[0055] (2) Weigh the baked aeolian sand in step (1) according to a dry density of 1.50 g / cm 3 and, according to a fiber content (FC) of 0.75% of the total mass of the aeolian sand, a fiber length (FL) of 6 mm, and a mass ratio of basalt fiber to wool fiber of 1:1, stir and mix to make the fibers evenly distributed in the baked aeolian sand to obtain fiber sand material.

[0056] (3) Select a PVC pipe with an inner diameter of 39.1 mm and a height of 150 mm as the specimen mold. The mold is split in half for easy removal of the specimen, the connection is fixed with a hot melt glue gun, and the bottom is blocked with a rubber stopper and a small hole is reserved for the solution to flow out. To avoid sticking to the wall and side leakage, apply a layer of vaseline and pad a thin plastic sheet on the inner wall of the mold before sample preparation. According to the "Standard for Geotechnical Test Methods" (GB / T 50123-2019), the weighed aeolian sand is loaded into the mold in 4 layers, and scraping treatment is carried out between layers to obtain a specimen. Pad two layers of filter paper at the bottom of the specimen and one layer of filter paper on the top of the specimen before loading the sample.

[0057] (4) Dry soybeans and then crush them with a pulverizer to obtain soybean powder. After sieving, add deionized water to prepare a mixed solution with a concentration of 100 g / L, and use a magnetic stirrer to stir for 30 min to obtain soybean liquid. Centrifuge the soybean liquid at a speed of 4000 rpm for 15 min using a high-speed centrifuge, and the supernatant taken out from the centrifuge tube is the soybean urease solution. The process flow is as Figure 1 shown.

[0058] (5) The cementing solution consists of calcium chloride solution and urea solution. The calcium source of EICP is provided by anhydrous calcium chloride, with a relative molecular mass of 110.99, in the form of white cubic crystals, and is easily soluble in water; urea has a relative molecular mass of 60.06, in the form of transparent rod-shaped crystals, and is easily soluble in water. Anhydrous calcium chloride and urea are respectively mixed evenly with deionized water to prepare solutions with a concentration of 1.25 mol / L. According to "Preparation of Standard Titration Solutions for Chemical Reagents" (GB / T 601 - 2016), HCl standard solution (c = 1.0005 mol / L) and NaOH standard solution (c = 1.0008 mol / L) are used to adjust the pH value until the pH meter shows a value of 8.00 ± 0.05. The preparation process is as Figure 2 shown.

[0059] (6) The soybean urease solution and the cementing solution are in an enzyme-cement ratio of 3:2. The two-stage method is used to sequentially perfuse the sample with the soybean urease solution and the cementing solution. After the soybean urease solution is completely immersed, 10 mL of calcium chloride solution is poured in, and finally 10 mL of urea solution is poured in. The next round of perfusion is carried out after 24 hours. The mass ratio of the fibrous sand material to the soybean urease solution is 1:40.8. After all the perfusion times are completed, the sample is immediately left to stand for 3 hours in a constant temperature and humidity environment (temperature set at 25 °C, relative humidity maintained at 60%). After standing, the sample is rinsed 3 times with deionized water to terminate the internal reaction. After that, the mold is removed, and the sample is placed in an 80 °C oven for 36 hours for drying treatment.

[0060] Example 2

[0061] A method for solidifying aeolian sand includes the following steps:

[0062] (1) Pass the aeolian sand through a 0.5 mm sieve, put it in an oven at 120 °C for 24 hours, and prepare dry sand for later use.

[0063] (2) Weigh the dried aeolian sand in step (1) according to a dry density of 1.40 g / cm 3 According to the fiber content accounting for 0.25% of the total mass of the aeolian sand (FC), fiber length FL = 3 mm, and the mass ratio of basalt fiber to wool fiber being 1:2, evenly distribute them in the baked aeolian sand to obtain the fibrous sand material.

[0064] (3) Compact the fibrous sand material obtained in step (2) in 3 layers, and perform scraping treatment between layers to obtain a sample; the sample is prepared by a sample maker, and small holes are reserved at the bottom of the sample maker to facilitate the outflow of the solution.

[0065] (4) Add the soybean urease solution and the cementing solution in an enzyme-cement ratio of 1:1 to the sample in step (3) in sequence. The mass ratio of the fiber sand material to the soybean urease solution is 1:47.2, and let it stand for 1 h. The soybean urease solution is the supernatant obtained by crushing soybeans, adding deionized water, stirring, and then centrifuging. The cementing solution is a solution obtained by mixing anhydrous calcium chloride and urea solution and adjusting the pH value to 8.00 ± 0.05.

[0066] Example 3

[0067] A method for solidifying aeolian sand includes the following steps:

[0068] (1) Pass the aeolian sand through a 0.7-mm sieve, put it into an oven at 130 °C for 26 h, and then obtain the dry sand for reserve.

[0069] (2) Weigh the baked aeolian sand in step (1) according to a dry density of 1.50 g / cm 3 According to the fiber content accounting for 0.50% of the total mass of the aeolian sand, the fiber length FL = 6 mm, and the mass ratio of basalt fiber to wool fiber being 1:3, uniformly distribute them in the baked aeolian sand to obtain the fiber sand material.

[0070] (3) Compact the fiber sand material obtained in step (2) in 4 layers, and perform scraping treatment between layers to obtain the sample. The sample is obtained through a sample preparation device, and small holes are reserved at the bottom of the sample preparation device to facilitate the outflow of the solution.

[0071] (4) Add the soybean urease solution and the cementing solution in an enzyme-cement ratio of 2:3 to the sample in step (3) in sequence. The mass ratio of the fiber sand material to the soybean urease solution is 1:56.8, and let it stand for 2 h. The soybean urease solution is the supernatant obtained by crushing soybeans, adding deionized water, stirring, and then centrifuging. The cementing solution is a solution obtained by mixing anhydrous calcium chloride and urea solution and adjusting the pH value to 8.00 ± 0.05.

[0072] Example 4

[0073] A method for solidifying aeolian sand includes the following steps:

[0074] (1) Pass the aeolian sand through a 0.9-mm sieve, put it into an oven at 140 °C for 28 h, and then obtain the dry sand for reserve.

[0075] (2) Weigh the baked aeolian sand in step (1) according to a dry density of 1.60 g / cm 3 According to the fiber content accounting for 0.75% of the total mass of the aeolian sand, the fiber length FL = 9 mm, and the mass ratio of basalt fiber to wool fiber being 1:4, uniformly distribute them in the baked aeolian sand to obtain the fiber sand material.

[0076] (3) Compact the fiber sand material obtained in step (2) in 5 layers, and perform scraping treatment between layers to obtain a specimen; the specimen is prepared by a sample preparation device, and small holes are reserved at the bottom of the sample preparation device to facilitate the outflow of the solution.

[0077] (4) Add the soybean urease solution and the cementing solution in an enzyme-cement ratio of 3:2 to the specimen in step (3) in sequence. The mass ratio of the fiber sand material to the soybean urease solution is 1:60.8, and let it stand for 3 h; the soybean urease solution is the supernatant obtained by crushing soybeans, adding deionized water, stirring, and then centrifuging; the cementing solution is a solution obtained by mixing anhydrous calcium chloride and urea solution and adjusting the pH value to 8.00 ± 0.05.

[0078] Example 5

[0079] A method for solidifying aeolian sand includes the following steps:

[0080] (1) Pass the aeolian sand through a 1.2 mm sieve, put it in an oven at 150 °C for 30 h, and then obtain dry sand for standby.

[0081] (2) Weigh the baked aeolian sand in step (1) according to a dry density of 1.70 g / cm 3 According to the fiber content accounting for 1.00% of the total mass of the aeolian sand FC, fiber length FL = 12 mm, and the mass ratio of basalt fiber to wool fiber being 4:1, evenly distribute them in the baked aeolian sand to obtain a fiber sand material.

[0082] (3) Compact the mixed fiber sand material obtained in step (2) in 6 layers, and perform scraping treatment between layers to obtain a specimen; the specimen is prepared by a sample preparation device, and small holes are reserved at the bottom of the sample preparation device to facilitate the outflow of the solution.

[0083] (4) Add the soybean urease solution and the cementing solution in an enzyme-cement ratio of 1:2 to the specimen in step (3) in sequence. The mass ratio of the fiber sand material to the soybean urease solution is 1:67.2, and let it stand for 4 h; the soybean urease solution is the supernatant obtained by crushing soybeans, adding deionized water, stirring, and then centrifuging; the cementing solution is a solution obtained by mixing anhydrous calcium chloride and urea solution and adjusting the pH value to 8.00 ± 0.05.

[0084] Test Example 1

[0085] Test the relationship between the unconfined compressive strength of the solidified aeolian sand in the example and the fiber type. The results are as Figure 4 shown. According to Figure 4It can be seen that after adding fibers, the strength of the specimens is significantly improved. When basalt fibers are added, the strength improvement range of the specimens is 28.51 - 53.80%; when FL = 6 mm and FC = 0.75%, the maximum strength of the specimens reaches 849.65 kPa; when wool fibers are added, the strength improvement range of the specimens is 28.28 - 55.66%, and when FL = 9 mm and FC = 0.75%, the maximum strength of the specimens reaches 885.31 kPa.

[0086] Test Example 2

[0087] The unconfined compressive strength of the aeolian sand cured in the example was tested with respect to the change in fiber length (FL). The results are as Figure 5 shown. According to Figure 5 It can be seen that when the length of basalt fibers added is 3 - 6 mm, the strength of the specimens shows an increasing trend with the increase in fiber length; when the length is 9 - 12 mm, the strength of the specimens shows a decreasing trend with the increase in fiber length; when reaching the peak strength, the optimal reinforcement condition for basalt fibers is FL = 6 mm; when the length of wool fibers added is 3 - 9 mm, the strength of the specimens shows an increasing trend with the increase in fiber length; when the fiber length is 12 mm, the strength of the specimens decreases; when reaching the peak strength, the optimal reinforcement condition for wool fibers is FL = 9 mm.

[0088] Test Example 3

[0089] The unconfined compressive strength of the aeolian sand cured in the example was tested with respect to the change in fiber content (FC). The results are as Figure 6 shown. According to Figure 6 It can be seen that when FC = 0.25 - 0.75% is added, the strength of the specimens shows an increasing trend with the increase in fiber content; when FC = 1.00% is added, the strength of the specimens decreases; comparing the two types of fibers, when reaching the peak strength, the optimal reinforcement condition for basalt fibers is FC = 0.75%, and the unconfined compressive strength is 849.65 kPa; the optimal reinforcement condition for wool fibers is FC = 0.75%, and the unconfined compressive strength is 885.31 kPa.

[0090] Test Example 4

[0091] The unconfined compressive strength of the specimens was analyzed. Taking the unconfined compressive strength of the specimens as the dependent variable and the fiber content (FC) and fiber length (FL) as the independent variables, a multiple linear regression analysis surface and a model fitting surface were established. Through regression analysis, an unconfined compressive strength model - the regression analysis fitting model of FL, FC and UCS was obtained, as Figure 7 shown; a Poly model was established:

[0092] U = aFL + bFC + c(FL) 2 + d(FC)2 +fFL·FC+z

[0093] In the formula, U is the unconfined compressive strength of EICP collaborative fiber-reinforced solidified aeolian sand, kPa; FL is the fiber length, mm; FC is the fiber content, %; a, b, c, d, f are parameters, and z is a constant. As can be seen from the figure, the fitting surface relatively evenly covers the regression analysis surface. In the Poly model of the aeolian sand specimens solidified by EICP-BF and EICP-WF, the parameter values of a, b, c, d, f, and z are shown in Table 1.

[0094] Table 1 Parameter values of the solidified aeolian sand model of the present invention

[0095] specimen a b c d f z <![CDATA[R 2 > EICP-BFR 119.21 864.35 -7.39 -590.14 -8.88 58.64 0.9270 EICP-WFR 110.45 810.71 -7.48 -622.01 2.35 112.39 0.8815

[0096] It can be seen from Table 1 that the determination coefficients of the model of the present invention are 0.9270 and 0.8815 respectively, indicating that FL, FC and UCS have a good correlation.

[0097] It can be known from the above embodiments that the solidification method provided by the present invention can increase the friction and solidification effect between aeolian sand particles, effectively improve the tensile resistance and shear resistance of the solidified aeolian sand, improve the strength and toughness of the solidified aeolian sand, and improve the durability and anti-aging performance of the solidified body, so that the solidified body can still maintain good mechanical properties and stability during long-term use, and prevent wind erosion damage.

[0098] Although the above embodiments have described the present invention in detail, they are only a part of the embodiments of the present invention, rather than all embodiments. Other embodiments can be obtained according to these embodiments without creative efforts, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A method for solidifying aeolian sand, characterized in that: The following steps are involved: (1) mixing the dried aeolian sand with basalt fiber and wool fiber to obtain a fiber sand material; (2) compacting the fiber sand material in layers, mixing it with soybean urease solution and a binder solution, and then letting it stand.

2. The curing method according to claim 1, characterized in that: The particle size of the aeolian sand is not greater than 1.2 mm; the dry density of the aeolian sand is 1.40 to 1.70 g / cm 3 .

3. The curing method according to claim 1 or 2, characterized in that: The mass ratio of the total mass of the basalt fiber and the wool fiber to the mass of the aeolian sand is 0.25-1:99-99.75; the mass ratio of the basalt fiber to the wool fiber is 1-4:4-1.

4. The curing method according to claim 1, characterized in that: The lengths of the basalt fibers and wool fibers are independently 3 to 12 mm.

5. The curing method according to claim 1, characterized in that: The number of layers of the stratification is 3 to 6 layers.

6. The curing method according to claim 1 or 5, characterized in that: The compaction pressure is no higher than 800 kPa, the single compaction time is 1 to 2 seconds, and the compaction times are 36 to 60 times.

7. The curing method according to claim 1, characterized in that: The concentration of soybean urease in the soybean urease solution is 30-110 g / L; the mass ratio of the fiber sand material to the soybean urease solution is 1:40.8-67.

2.

8. The curing method according to claim 1 or 7, characterized in that: The binder comprises a calcium chloride aqueous solution and a urea aqueous solution; the mass ratio of anhydrous calcium chloride in the calcium chloride aqueous solution to urea in the urea aqueous solution is 1-4:4-1; the concentration of the calcium chloride aqueous solution is 1-2 mol / L; the concentration of the urea aqueous solution is 1-2 mol / L; the pH value of the binder is 8.00±0.05; the enzyme-binder ratio of the soybean urease solution and the binder is 1-4:4-1.

9. The curing method according to claim 1, characterized in that: The second mixing is performed by batch pouring; the number of batch pouring is 1 to 10 times; a single pouring of the batch pouring is: pouring soybean urease solution into the layered and compacted fiber sand material, pouring calcium chloride aqueous solution after the soybean urease solution is immersed, and then pouring urea aqueous solution.

10. The curing method according to claim 1 or 9, characterized in that: The standing time is 1 to 4 hours.

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