Preparation method of water-retaining compacted backfill material with slow-release excitation structure

Abstract

The present invention discloses a preparation method of a water-retaining compacted backfill material with a slow-release excitation structure. The method comprises the following steps: first preparing a chitosan solution, then adding carbide slag, stirring evenly and then ultrasonically treating the mixture, followed by solid-liquid separation, washing the solid product, and freeze-drying the mixture to obtain a slow-release alkaline substance; uniformly mixing magnesium oxide, granulated blast furnace slag, red mud, fly ash, and sodium silicate to obtain a solidified precursor; uniformly mixing coarse sand, bentonite, and plain soil to obtain a filling aggregate; and finally uniformly mixing the slow-release alkaline substance, the solidified precursor, and the filling aggregate, and then adding water and stirring to obtain the material. The method prepares an encapsulated alkaline material, so that the active alumina and silicon dioxide in the solidified precursor undergo a continuous and stable hydration reaction to produce hydration products, which are filled in the pores of the skeleton material and connect the minerals in the skeleton, thereby improving the overall strength and solving the problems of poor excitation effect, low strength of the backfill material, and poor integrity in the existing alkali excitation system.

Description

Technical Field

[0001] The invention belongs to the field of environmental rock and soil technology, and particularly relates to a method for preparing a water-retaining compacted backfill material with a slow-release excitation structure. Background Art

[0002] With the advancement of industrialization, urban construction and mining activities have continued to increase, generating large amounts of industrial waste. The effective utilization of this waste has become a key research topic in materials science and environmental engineering. In recent years, the development of water-retaining compacted backfill materials has gradually gained attention, especially those with slow-release excitation structures. These materials have become a hot topic of research both domestically and internationally due to their outstanding performance in improving soil moisture retention and enhancing soil quality. These materials typically utilize a composite technology combining natural polymers with industrial waste. By adjusting the material's microstructure and composition, they achieve the dual tasks of slow-release excitation and moisture management.

[0003] Currently, research abroad is primarily focused on the combined utilization of polymer materials and industrial waste residues. Many researchers have explored the combined use of xanthan gum, starches, and silica gels, combining these materials with alkaline industrial waste residues to form slow-release excitation structures. For example, some European studies have shown that when xanthan gum is combined with slag, it can effectively delay the release of alkaline substances and improve the material's compressive strength. These studies have provided important theoretical foundations and experimental data support for similar materials in my country. Furthermore, international scholars have also conducted extensive research on particle size optimization, particularly in the construction of microporous structures using materials such as magnesium oxide and fly ash. These achievements demonstrate the advantages of small-particle materials in increasing porosity and water retention.

[0004] Domestic research on water-retaining compacted backfill materials started relatively late. In recent years, with the promotion of environmental protection policies and the increase in demand for ecological restoration, this field has gradually developed. Researchers have begun to pay attention to the resource utilization of industrial waste slag, especially in the activation mechanism and application effect of alkaline industrial waste slag, and have carried out a number of studies. Studies have shown that by optimizing the composition of the activator, the water retention capacity and strength of the material can be significantly improved, which echoes the results of foreign research. At the same time, China has gradually made progress in the compounding of multi-graded filling aggregates, exploring the optimal ratio of coarse sand, bentonite and plain soil to achieve higher material strength and lower permeability coefficient, in line with the needs of actual engineering applications.

[0005] At the technical application level, research both domestically and internationally has shown some common trends. With increasing emphasis on environmental protection, more and more engineering projects are adopting environmentally friendly backfill materials. In particular, in urban infrastructure construction and mine restoration, water-retaining compacted backfill materials are increasingly being used in soil remediation and ecological restoration. Practical experience abroad has shown that these materials not only effectively enhance soil water retention but also improve soil structure and chemical properties, promoting plant growth. This provides valuable insights for domestic research and application.

[0006] In general, water-retaining compacted backfill materials with a slow-release activation structure demonstrate strong research potential and application prospects both domestically and internationally. Although research in China began relatively late, considerable progress has been made in material combinations, activation mechanisms, and application technologies. In the future, with the increasing demand for environmentally friendly materials and the continued maturity of related technologies, such materials are expected to be widely used in more practical projects. However, existing alkali-activated systems generally suffer from poor activation effects, low backfill material strength, and poor integrity. Therefore, there is an urgent need to develop a water-retaining compacted backfill material with a slow-release activation structure. Summary of the Invention

[0007] The purpose of the present invention is to provide a method for preparing a water-retaining compacted backfill material with a slow-release activation structure to address the problems of poor activation effect, low backfill material strength, and poor integrity in the existing alkali activation system.

[0008] In order to achieve the above object, the present invention is implemented through the following technical solutions:

[0009] A method for preparing a water-retaining compacted backfill material with a slow-release excitation structure comprises the following steps:

[0010] S1. Chitosan was dissolved in 1% acetic acid solution to obtain a chitosan solution, carbide slag was added to the chitosan solution, stirred and ultrasonicated, and then solid-liquid separation was performed. The obtained solid product was washed and freeze-dried to obtain a slow-release alkaline substance;

[0011] S2. Magnesium oxide, granulated blast furnace slag, red mud, fly ash and sodium silicate are mixed uniformly in a mass ratio of (4-5):(18-22):(8-12):(4-6):(0.5-1.5) to obtain a solidified precursor;

[0012] S3. The coarse sand, bentonite and clay are mixed evenly to obtain a filling aggregate;

[0013] S4. The slow-release alkaline substance, the curing precursor, and the filling aggregate are mixed evenly to obtain a mixture, and then water is added and mixed and stirred to obtain a water-retaining compacted backfill material with a slow-release excitation structure.

[0014] Furthermore, in step S1, the mass ratio of the carbide slag to chitosan is (8-12):1.

[0015] Furthermore, in step S1, the freeze-drying temperature is -60°C and the time is 12 hours.

[0016] Furthermore, in step S1, the frequency of the ultrasonic treatment is 50 Hz, and the duration is 2 to 4 hours.

[0017] Furthermore, in step S2, the particle size of the granulated blast furnace slag is 100-200 mesh; the particle size of the red mud is 100-200 mesh; the particle size of the fly ash is 250-350 mesh; and the modulus of the sodium silicate is 1.5.

[0018] Furthermore, in step S3, the mass ratio of the coarse sand, bentonite and plain soil is 1:1:(3-8).

[0019] Furthermore, in step S3, the particle size range of the coarse sand is 0.5 mm to 2 mm, the particle size range of the bentonite is 0.001 mm to 0.05 mm, and the particle size range of the plain soil is 0.075 mm to 1 mm.

[0020] Furthermore, in step S4, the mass ratio of the slow-release alkaline substance, the curing precursor and the filling aggregate is (1-2):5:(36-40).

[0021] Furthermore, in step S4, the water-solid ratio is 5:1.

[0022] Beneficial Effects: The present invention discloses a method for preparing a water-retaining compacted backfill material with a slow-release excitation structure. This method involves preparing an encapsulated alkaline material to cause the activated alumina and silica in the solidified precursor to undergo a continuous and stable hydration reaction, producing hydration products that fill the pores of the skeleton material and connect the minerals in the skeleton, thereby improving the overall strength. The water-retaining compacted backfill material of the present invention is particularly suitable for use in construction projects (foundation pit projects), foundation treatment, and other fields. Compared with the existing technology, the present invention has the following advantages:

[0023] 1) The present invention uses chitosan to wrap alkaline industrial waste residue to prepare an activator, so that it slowly releases alkaline substances in the system, continuously stimulating the active ingredients. When the release is completed, the space left can be used as a pore water storage space;

[0024] 2) The present invention uses magnesium oxide, granulated blast furnace slag, red mud, fly ash and sodium silicate to prepare a solidification precursor. The micropores in the system are numerous with physical adsorption micropores and rich potential. After the micelles disappear, the system has the ability to retain water and absorb CO2. After the water reaches a certain saturation, it leaks into the lower layer through the pores.

[0025] 3) The present invention uses coarse sand, bentonite and plain soil to construct a dense skeleton, which is conducive to the adhesion of hydration products and the cementation of mineral particles and filling of pores, forming a water-retaining compacted backfill material with small deformation, low permeability, high strength and strong integrity. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 The permeability coefficient test results of the water-retaining compacted backfill material with a slow-release excitation structure prepared in Examples 1-3;

[0027] Figure 2 The unconfined compressive strength test results of the water-retaining compacted backfill material with a slow-release activation structure prepared in Examples 1-3;

[0028] Figure 3 The permeability coefficient test results of the water-retaining compacted backfill material with a slow-release excitation structure prepared in Examples 4-6;

[0029] Figure 4 The unconfined compressive strength test results of the water-retaining compacted backfill material with a slow-release activation structure prepared in Examples 4-6;

[0030] Figure 5 The permeability coefficient test results of the water-retaining compacted backfill material with a slow-release excitation structure prepared in Examples 7-9;

[0031] Figure 6 These are the unconfined compressive strength test results of the water-retaining compacted backfill materials with a slow-release activation structure prepared in Examples 7-9. DETAILED DESCRIPTION

[0032] The technical solution of the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments, but the protection scope of the present invention is not limited to the embodiments.

[0033] To clearly and completely illustrate the present invention, the following examples use granulated blast furnace slag as a commercial product with a particle size of 200 mesh; magnesium oxide as a commercial product with a particle size of 100 mesh; red mud as a commercial product with a particle size of 180 mesh; fly ash as a commercial product with a particle size of 300 mesh; sodium silicate as a commercial product with a modulus of 1.5; coarse sand with a particle size range of 0.5 mm to 2 mm; bentonite with a particle size range of 0.001 mm to 0.05 mm; and plain clay with a particle size range of 0.075 mm to 1 mm. However, the present invention is not limited to these examples.

[0034] Example 1

[0035] A method for preparing a water-retaining compacted backfill material with a slow-release excitation structure comprises the following steps:

[0036] S1. Chitosan was dissolved in 1% acetic acid solution to prepare a chitosan solution. Calcium carbide slag was then added at a mass ratio of 10:1. The solution was stirred evenly and ultrasonicated at 50 Hz for 2 hours. The solution was then separated into a solid and liquid state using a filter membrane. The solid product was washed three times with deionized water and three times with anhydrous ethanol, and finally freeze-dried at -60°C for 12 hours to obtain a slow-release alkaline substance.

[0037] S2. Magnesium oxide, granulated blast furnace slag, red mud, fly ash and sodium silicate were mixed in a mass ratio of 4:18:8:4:0.5 to obtain a solidified precursor;

[0038] S3. The coarse sand, bentonite and clay were mixed in a mass ratio of 1:1:5 to obtain a filling aggregate;

[0039] S4. The slow-release alkaline substance, the curing precursor, and the filling aggregate are uniformly mixed in a mass ratio of 1.5:5:36 to obtain a mixture, and then water is added and mixed in a water-solid ratio of 5:1 to obtain a water-retaining compacted backfill material with a slow-release excitation structure.

[0040] Example 2

[0041] A method for preparing a water-retaining compacted backfill material with a slow-release excitation structure comprises the following steps:

[0042] S1. Chitosan was dissolved in 1% acetic acid solution to prepare a chitosan solution. Calcium carbide slag was then added at a mass ratio of 10:1. The solution was stirred evenly and ultrasonicated at 50 Hz for 2 hours. The solution was then separated into a solid and liquid state using a filter membrane. The solid product was washed three times with deionized water and three times with anhydrous ethanol, and finally freeze-dried at -60°C for 12 hours to obtain a slow-release alkaline substance.

[0043] S2. Magnesium oxide, granulated blast furnace slag, red mud, fly ash and sodium silicate were mixed in a mass ratio of 5:20:10:5:1 to obtain a solidified precursor;

[0044] S3. The coarse sand, bentonite and clay were mixed in a mass ratio of 1:1:5 to obtain a filling aggregate;

[0045] S4. The slow-release alkaline substance, the curing precursor, and the filling aggregate are uniformly mixed in a mass ratio of 1.5:5:36 to obtain a mixture, and then water is added and mixed in a water-solid ratio of 5:1 to obtain a water-retaining compacted backfill material with a slow-release excitation structure.

[0046] Example 3

[0047] A method for preparing a water-retaining compacted backfill material with a slow-release excitation structure comprises the following steps:

[0048] S1. Chitosan was dissolved in 1% acetic acid solution to prepare a chitosan solution. Calcium carbide slag was then added at a mass ratio of 10:1. The solution was stirred evenly and ultrasonicated at 50 Hz for 2 hours. The solution was then separated into a solid and liquid state using a filter membrane. The solid product was washed three times with deionized water and three times with anhydrous ethanol, and finally freeze-dried at -60°C for 12 hours to obtain a slow-release alkaline substance.

[0049] S2. Magnesium oxide, granulated blast furnace slag, red mud, fly ash and sodium silicate were mixed in a mass ratio of 5:22:12:6:1.5 to obtain a solidified precursor;

[0050] S3. The coarse sand, bentonite and clay were mixed in a mass ratio of 1:1:5 to obtain a filling aggregate;

[0051] S4. The slow-release alkaline substance, the curing precursor, and the filling aggregate are uniformly mixed in a mass ratio of 1.5:5:36 to obtain a mixture, and then water is added and mixed in a water-solid ratio of 5:1 to obtain a water-retaining compacted backfill material with a slow-release excitation structure.

[0052] Example 4

[0053] A method for preparing a water-retaining compacted backfill material with a slow-release excitation structure comprises the following steps:

[0054] S1. Chitosan was dissolved in 1% acetic acid solution to prepare a chitosan solution. Calcium carbide slag was then added at a mass ratio of 10:1. The solution was stirred evenly and ultrasonicated at 50 Hz for 2 hours. The solution was then separated into a solid and liquid state using a filter membrane. The solid product was washed three times with deionized water and three times with anhydrous ethanol, and finally freeze-dried at -60°C for 12 hours to obtain a slow-release alkaline substance.

[0055] S2. Magnesium oxide, granulated blast furnace slag, red mud, fly ash and sodium silicate were mixed in a mass ratio of 5:20:10:5:1 to obtain a solidified precursor;

[0056] S3. The coarse sand, bentonite and clay were mixed in a mass ratio of 1:1:3 to obtain a filling aggregate;

[0057] S4. The slow-release alkaline substance, the curing precursor, and the filling aggregate are uniformly mixed in a mass ratio of 1.5:5:36 to obtain a mixture, and then water is added and mixed in a water-solid ratio of 5:1 to obtain a water-retaining compacted backfill material with a slow-release excitation structure.

[0058] Example 5

[0059] A method for preparing a water-retaining compacted backfill material with a slow-release excitation structure comprises the following steps:

[0060] S1. Chitosan was dissolved in 1% acetic acid solution to prepare a chitosan solution. Calcium carbide slag was then added at a mass ratio of 10:1. The solution was stirred evenly and ultrasonicated at 50 Hz for 2 hours. The solution was then separated into a solid and liquid state using a filter membrane. The solid product was washed three times with deionized water and three times with anhydrous ethanol, and finally freeze-dried at -60°C for 12 hours to obtain a slow-release alkaline substance.

[0061] S2. Magnesium oxide, granulated blast furnace slag, red mud, fly ash and sodium silicate were mixed in a mass ratio of 5:20:10:5:1 to obtain a solidified precursor;

[0062] S3. The coarse sand, bentonite and clay were mixed in a mass ratio of 1:1:6 to obtain a filling aggregate;

[0063] S4. The slow-release alkaline substance, the curing precursor, and the filling aggregate are uniformly mixed in a mass ratio of 1.5:5:36 to obtain a mixture, and then water is added and mixed in a water-solid ratio of 5:1 to obtain a water-retaining compacted backfill material with a slow-release excitation structure.

[0064] Example 6

[0065] A method for preparing a water-retaining compacted backfill material with a slow-release excitation structure comprises the following steps:

[0066] S1. Chitosan was dissolved in 1% acetic acid solution to prepare a chitosan solution. Calcium carbide slag was then added at a mass ratio of 10:1. The solution was stirred evenly and ultrasonicated at 50 Hz for 2 hours. The solution was then separated into a solid and liquid state using a filter membrane. The solid product was washed three times with deionized water and three times with anhydrous ethanol, and finally freeze-dried at -60°C for 12 hours to obtain a slow-release alkaline substance.

[0067] S2. Magnesium oxide, granulated blast furnace slag, red mud, fly ash and sodium silicate were mixed in a mass ratio of 5:20:10:5:1 to obtain a solidified precursor;

[0068] S3. The coarse sand, bentonite and clay were mixed in a mass ratio of 1:1:8 to obtain a filling aggregate;

[0069] S4. The slow-release alkaline substance, the curing precursor, and the filling aggregate are uniformly mixed in a mass ratio of 1.5:5:36 to obtain a mixture, and then water is added and mixed in a water-solid ratio of 5:1 to obtain a water-retaining compacted backfill material with a slow-release excitation structure.

[0070] Example 7

[0071] A method for preparing a water-retaining compacted backfill material with a slow-release excitation structure comprises the following steps:

[0072] S1. Chitosan was dissolved in 1% acetic acid solution to prepare a chitosan solution. Calcium carbide slag was then added at a mass ratio of 10:1. The solution was stirred evenly and ultrasonicated at 50 Hz for 2 hours. The solution was then separated into a solid and liquid state using a filter membrane. The solid product was washed three times with deionized water and three times with anhydrous ethanol, and finally freeze-dried at -60°C for 12 hours to obtain a slow-release alkaline substance.

[0073] S2. Magnesium oxide, granulated blast furnace slag, red mud, fly ash and sodium silicate were mixed in a mass ratio of 5:20:10:5:1 to obtain a solidified precursor;

[0074] S3. The coarse sand, bentonite and clay were mixed in a mass ratio of 1:1:5 to obtain a filling aggregate;

[0075] S4. The slow-release alkaline substance, the curing precursor, and the filling aggregate are uniformly mixed in a mass ratio of 1:5:36 to obtain a mixture, and then water is added and mixed in a water-solid ratio of 5:1 to obtain a water-retaining compacted backfill material with a slow-release excitation structure.

[0076] Example 8

[0077] A method for preparing a water-retaining compacted backfill material with a slow-release excitation structure comprises the following steps:

[0078] S1. Chitosan was dissolved in 1% acetic acid solution to prepare a chitosan solution. Calcium carbide slag was then added at a mass ratio of 10:1. The solution was stirred evenly and ultrasonicated at 50 Hz for 2 hours. The solution was then separated into a solid and liquid state using a filter membrane. The solid product was washed three times with deionized water and three times with anhydrous ethanol, and finally freeze-dried at -60°C for 12 hours to obtain a slow-release alkaline substance.

[0079] S2. Magnesium oxide, granulated blast furnace slag, red mud, fly ash and sodium silicate were mixed in a mass ratio of 5:20:10:5:1 to obtain a solidified precursor;

[0080] S3. The coarse sand, bentonite and clay were mixed in a mass ratio of 1:1:5 to obtain a filling aggregate;

[0081] S4. The slow-release alkaline substance, the curing precursor, and the filling aggregate are uniformly mixed in a mass ratio of 1.75:5:36 to obtain a mixture, and then water is added and mixed in a water-solid ratio of 5:1 to obtain a water-retaining compacted backfill material with a slow-release excitation structure.

[0082] Example 9

[0083] A method for preparing a water-retaining compacted backfill material with a slow-release excitation structure comprises the following steps:

[0084] S1. Chitosan was dissolved in 1% acetic acid solution to prepare a chitosan solution. Calcium carbide slag was then added at a mass ratio of 10:1. The solution was stirred evenly and ultrasonicated at 50 Hz for 2 hours. The solution was then separated into a solid and liquid state using a filter membrane. The solid product was washed three times with deionized water and three times with anhydrous ethanol, and finally freeze-dried at -60°C for 12 hours to obtain a slow-release alkaline substance.

[0085] S2. Magnesium oxide, granulated blast furnace slag, red mud, fly ash and sodium silicate were mixed in a mass ratio of 5:20:10:5:1 to obtain a solidified precursor;

[0086] S3. The coarse sand, bentonite and clay were mixed in a mass ratio of 1:1:5 to obtain a filling aggregate;

[0087] S4. The slow-release alkaline substance, the curing precursor, and the filling aggregate are uniformly mixed in a mass ratio of 2:5:36 to obtain a mixture, and then water is added and mixed in a water-solid ratio of 5:1 to obtain a water-retaining compacted backfill material with a slow-release excitation structure.

[0088] Performance testing:

[0089] The water-retaining compacted backfill materials with slow-release excitation structures prepared in Examples 1-9 were cured for 28 days (relative humidity 95%, temperature 20°C), and then their permeability coefficient and unconfined compressive strength were tested according to the method in GBT 50123-2019 "Standard for Geotechnical Test Methods".

[0090] Figure 1 The permeability coefficient test results of the water-retaining compacted backfill materials with slow-release excitation structures prepared in Examples 1-3 show that the permeability coefficients of the water-retaining compacted backfill materials prepared in Examples 1-3 are 8.3×10 -7 cm / s, 1.2×10 -7 cm / s, 4.9×10 -7 cm / s, indicating that the optimal ratio of magnesium oxide, granulated blast furnace slag, red mud, fly ash and sodium silicate is 5:20:10:5:1. Under this ratio, more hydration products are generated to fill the pore channels and prevent the penetration of water.

[0091] Figure 2 The unconfined compressive strength test results of the water-retaining compacted backfill materials with a slow-release excitation structure prepared in Examples 1-3 show that the unconfined compressive strengths of the water-retaining compacted backfill materials prepared in Examples 1-3 are 0.5 MPa, 1.2 MPa, and 0.7 MPa, respectively, indicating that the optimal ratio of magnesium oxide, granulated blast furnace slag, red mud, fly ash, and sodium silicate is 5:20:10:5:1. Under this ratio, more hydration products are generated to fill the pore channels and connect the skeleton together, thereby increasing the strength.

[0092] Figure 3 The permeability coefficient test results of the water-retaining compacted backfill materials with slow-release excitation structures prepared in Examples 4-6 show that the permeability coefficients of the water-retaining compacted backfill materials prepared in Examples 4-6 are 3.7×10 -7 cm / s, 2.6×10 -7 cm / s、7.9×10 -7 cm / s, indicating that the optimal mass ratio of coarse sand, bentonite and plain soil is 1:1:6. Under this ratio, the gradation is good, and the bentonite and plain soil fill the pores formed by the coarse sand, so the density is increased and water infiltration is prevented.

[0093] Figure 4 The unconfined compressive strength test results of the water-retaining compacted backfill materials with a slow-release excitation structure prepared in Examples 4-6 show that the unconfined compressive strengths of the water-retaining compacted backfill materials prepared in Examples 4-6 are 1.1 MPa, 1.3 MPa, and 0.6 MPa, respectively, indicating that the optimal mass ratio of coarse sand, bentonite, and plain soil is 1:1:6. The grading is good under this ratio, and the bentonite and plain soil are filled in the pores formed by the coarse sand, thereby increasing the density and thus the strength.

[0094] Figure 5 The permeability coefficient test results of the water-retaining compacted backfill materials with slow-release excitation structures prepared in Examples 7-9 show that the permeability coefficients of the water-retaining compacted backfill materials prepared in Examples 7-9 are 8.9×10 -7 cm / s, 3.1×10 -7 cm / s, 4.5×10 -7 cm / s, indicating that the optimal mass ratio of slow-release alkaline substance, curing precursor, and filling aggregate is 1.75:5:36. Under this ratio, the compacted material has the best density and can effectively prevent water penetration.

[0095] Figure 6 The unconfined compressive strength test results of the water-retaining compacted backfill materials with slow-release excitation structures prepared in Examples 7-9 show that the unconfined compressive strengths of the water-retaining compacted backfill materials prepared in Examples 7-9 are 1.2 MPa, 2.1 MPa, and 1.4 MPa, respectively, indicating that the optimal mass ratio of the slow-release alkaline substance, the solidified precursor, and the filling aggregate is 1.75:5:36. Under this ratio, the compacted material has a small proportion of pores and good strength.

[0096] As described above, although the present invention has been shown and described with reference to specific preferred embodiments, it should not be construed as limiting the present invention itself. Various changes in form and details may be made without departing from the core spirit and scope of the present invention as defined in the appended claims.

[0097] The above is only a preferred embodiment of the present invention. It should be pointed out that ordinary technicians in this technical field can make several improvements and modifications without departing from the concept of the present invention. These improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing a water-retaining compacted backfill material with a slow-release excitation structure, characterized in that: The steps include: S1. Chitosan was dissolved in 1% acetic acid solution to obtain a chitosan solution, carbide slag was added to the chitosan solution, stirred and ultrasonicated, and then solid-liquid separation was performed. The obtained solid product was washed and freeze-dried to obtain a slow-release alkaline substance; S2. Magnesium oxide, granulated blast furnace slag, red mud, fly ash and sodium silicate are mixed uniformly in a mass ratio of (4-5):(18-22):(8-12):(4-6):(0.5-1.5) to obtain a solidified precursor; S3. The coarse sand, bentonite and clay are mixed evenly to obtain a filling aggregate; S4. The slow-release alkaline substance, the curing precursor, and the filling aggregate are mixed evenly to obtain a mixture, and then water is added and mixed and stirred to obtain a water-retaining compacted backfill material with a slow-release excitation structure.

2. The method for preparing the water-retaining compacted backfill material with a slow-release excitation structure according to claim 1, characterized in that: In step S1, the mass ratio of the carbide slag to chitosan is (8-12):

1.

3. The method for preparing the water-retaining compacted backfill material with a slow-release excitation structure according to claim 1, characterized in that: In step S1, the freeze-drying temperature is -60°C and the time is 12 hours.

4. The method for preparing the water-retaining compacted backfill material with a slow-release excitation structure according to claim 1, characterized in that: In step S1, the frequency of the ultrasonic treatment is 50 Hz and the duration is 2 to 4 hours.

5. The method for preparing the water-retaining compacted backfill material with a slow-release excitation structure according to claim 1, characterized in that: In step S2, the particle size of the granulated blast furnace slag is 100-200 mesh; the particle size of the red mud is 100-200 mesh; the particle size of the fly ash is 250-350 mesh; and the modulus of the sodium silicate is 1.

5.

6. The method for preparing the water-retaining compacted backfill material with a slow-release excitation structure according to claim 1, characterized in that: In step S3, the mass ratio of the coarse sand, bentonite and plain soil is 1:1:(3-8).

7. The method for preparing the water-retaining compacted backfill material with a slow-release excitation structure according to claim 1, characterized in that: In step S3, the particle size range of the coarse sand is 0.5 mm to 2 mm, the particle size range of the bentonite is 0.001 mm to 0.05 mm, and the particle size range of the plain soil is 0.075 mm to 1 mm.

8. The method for preparing the water-retaining compacted backfill material with a slow-release excitation structure according to claim 1, characterized in that: In step S4, the mass ratio of the slow-release alkaline substance, the curing precursor and the filling aggregate is (1-2):5:(36-40).

9. The method for preparing the water-retaining compacted backfill material having a slow-release excitation structure according to any one of claims 1 to 8, characterized in that: In step S4, the water-solid ratio is 5:1.

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