Preparation method of water retention type compaction backfill material with slow release excitation structure

Abstract

The invention discloses a preparation method of a water-retaining compaction backfill material with a slow-release excitation structure, which comprises the following steps: preparing a chitosan solution, adding carbide slag, uniformly stirring, carrying out ultrasonic treatment, carrying out solid-liquid separation, washing a solid product, and freeze-drying 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 cured precursor; uniformly mixing coarse sand, bentonite and plain soil to obtain filling aggregate; and finally, uniformly mixing the slow-release alkaline substance, the curing precursor and the filling aggregate, and then adding water and stirring to obtain the composite material. According to the method, active aluminum oxide and silicon dioxide in a curing precursor are subjected to a hydration reaction continuously and stably by preparing an alkaline material with a wrapping property to generate a hydration product, pores of a framework material are filled with the hydration product, minerals in a framework are connected, the overall strength is improved, and the problems that in an existing alkali excitation system, the excitation effect is poor, and the service life is short are solved. The backfill material is low in strength and poor in integrity.

Description

Technical Field

[0001] The invention belongs to the field of environmental rock and soil technology, and in particular 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 a large amount of industrial waste residues. How to effectively utilize these wastes has become an important research direction in the fields of materials science and environmental engineering. In recent years, the research and development of water-retaining compacted backfill materials has gradually attracted attention, especially materials with slow-release excitation structures, which have become a hot topic of research at home and abroad because of their outstanding performance in improving soil moisture retention and improving soil quality. This type of material usually adopts the composite technology of natural polymers and industrial waste residues, and achieves the dual tasks of slow-release excitation and moisture management by adjusting the microstructure and composition of the material.

[0003] At present, in foreign countries, related research mainly focuses on the composite utilization of polymer materials and industrial waste residues. Many researchers have explored the combined use of xanthan gum, starch and silica gel materials, and formed a slow-release excitation structure by combining these materials with alkaline industrial waste residues. For example, some European studies have shown that when xanthan gum is compounded with slag, it can effectively delay the release of alkaline substances and improve the compressive strength of the material. These studies provide important theoretical basis and experimental data support for similar materials in my country. In addition, in terms of particle size optimization, foreign scholars have also conducted a lot of exploration, especially in the use of magnesium oxide, fly ash and other materials to construct microporous structures, and have achieved certain results, proving the advantages of small particle materials in improving porosity and water retention capacity.

[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, domestic and foreign research also shows some common trends. With the emphasis on environmental protection, more and more engineering projects have begun to use environmentally friendly backfill materials. Especially in urban infrastructure construction and mining area restoration, water-retaining compacted backfill materials have gradually been used in soil remediation, ecological restoration and other fields. Foreign practical experience shows that this type of material can not only effectively improve the water retention capacity of the soil, but also improve the structure and chemical properties of the soil and promote plant growth, which provides a reference for domestic research and application.

[0006] In general, water-retaining compacted backfill materials with a slow-release excitation structure show strong research potential and application prospects both at home and abroad. Although domestic research started a little later, certain progress has been made in material combination, excitation mechanism and application technology. In the future, with the increasing demand for environmentally friendly materials and the continuous maturity of related technologies, this type of material is expected to be widely used in more practical projects. However, the existing alkali excitation system generally has problems such as poor excitation effect, low strength of backfill materials, and poor integrity. Therefore, it is urgent to develop a water-retaining compacted backfill material with a slow-release excitation 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 in order to solve 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 by 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. dissolving chitosan in acetic acid solution having a mass concentration of 1% to obtain a chitosan solution, adding carbide slag to the chitosan solution, stirring evenly, ultrasonically treating, and then separating the solid from the liquid, washing the obtained solid product, and freeze-drying to obtain a slow-release alkaline substance;

[0011] S2. Mix magnesium oxide, granulated blast furnace slag, red mud, fly ash and sodium silicate 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. Evenly mix the slow-release alkaline substance, the solidification precursor, and the filling aggregate to obtain a mixture, and then add water and mix and stir 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 clay 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 clay 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. The method prepares an alkaline material with encapsulation, 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 to improve the overall strength. The water-retaining compacted backfill material of the present invention is particularly suitable for use in construction engineering (foundation pit engineering), foundation treatment and other fields. Compared with the prior art, 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 the alkaline substance is slowly released in the system, and the active ingredients are continuously activated. When the release is completed, the remaining space 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 system has many physical adsorption micropores in the micropores and rich potential. After the micelle disappears, it has the advantages of water retention and CO absorption. 2 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 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 excitation 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 excitation 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 in conjunction with the accompanying drawings and specific embodiments, but the protection scope of the present invention is not limited to the embodiments.

[0033] In order to clearly and completely illustrate the present invention, in the following embodiments, the granulated blast furnace slag used is an industrial product with a particle size of 200 mesh; magnesium oxide is an industrial product with a particle size of 100 mesh; red mud is an industrial product with a particle size of 180 mesh; fly ash is an industrial product with a particle size of 300 mesh; sodium silicate is an industrial product with a modulus of 1.5; the coarse sand particle size range is 0.5mm-2mm, the bentonite particle size range is 0.001mm-0.05mm; and the plain soil particle size range is 0.075mm-1mm. However, they are not limited thereto.

[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 chitosan solution, then carbide slag was added, the mass ratio of carbide slag to chitosan was 10:1, and after stirring evenly, ultrasonic treatment was performed at 50 Hz for 2 h, followed by solid-liquid separation with a filter membrane, and the solid product was washed with deionized water and anhydrous ethanol for 3 times respectively, and finally freeze-dried at -60°C for 12 h 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 are mixed in a mass ratio of 1:1:5 to obtain a filling aggregate;

[0039] S4. The slow-release alkaline substance, the solidification 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 chitosan solution, then carbide slag was added, the mass ratio of carbide slag to chitosan was 10:1, and after stirring evenly, ultrasonic treatment was performed at 50 Hz for 2 h, followed by solid-liquid separation with a filter membrane, and the solid product was washed with deionized water and anhydrous ethanol for 3 times respectively, and finally freeze-dried at -60°C for 12 h to obtain a slow-release alkaline substance;

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

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

[0045] S4. The slow-release alkaline substance, the solidification 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 chitosan solution, then carbide slag was added, the mass ratio of carbide slag to chitosan was 10:1, and after stirring evenly, ultrasonic treatment was performed at 50 Hz for 2 h, followed by solid-liquid separation with a filter membrane, and the solid product was washed with deionized water and anhydrous ethanol for 3 times respectively, and finally freeze-dried at -60°C for 12 h 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 are mixed in a mass ratio of 1:1:5 to obtain a filling aggregate;

[0051] S4. The slow-release alkaline substance, the solidification 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 chitosan solution, then carbide slag was added, the mass ratio of carbide slag to chitosan was 10:1, and after stirring evenly, ultrasonic treatment was performed at 50 Hz for 2 h, followed by solid-liquid separation with a filter membrane, and the solid product was washed with deionized water and anhydrous ethanol for 3 times respectively, and finally freeze-dried at -60°C for 12 h to obtain a slow-release alkaline substance;

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

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

[0057] S4. The slow-release alkaline substance, the solidification 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 chitosan solution, then carbide slag was added, the mass ratio of carbide slag to chitosan was 10:1, and after stirring evenly, ultrasonic treatment was performed at 50 Hz for 2 h, followed by solid-liquid separation with a filter membrane, and the solid product was washed with deionized water and anhydrous ethanol for 3 times respectively, and finally freeze-dried at -60°C for 12 h to obtain a slow-release alkaline substance;

[0061] S2. Magnesium oxide, granulated blast furnace slag, red mud, fly ash and sodium silicate are 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 solidification 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 chitosan solution, then carbide slag was added, the mass ratio of carbide slag to chitosan was 10:1, and after stirring evenly, ultrasonic treatment was performed at 50 Hz for 2 h, followed by solid-liquid separation with a filter membrane, and the solid product was washed with deionized water and anhydrous ethanol for 3 times respectively, and finally freeze-dried at -60°C for 12 h to obtain a slow-release alkaline substance;

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

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

[0069] S4. The slow-release alkaline substance, the solidification 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 chitosan solution, then carbide slag was added, the mass ratio of carbide slag to chitosan was 10:1, and after stirring evenly, ultrasonic treatment was performed at 50 Hz for 2 h, followed by solid-liquid separation with a filter membrane, and the solid product was washed with deionized water and anhydrous ethanol for 3 times respectively, and finally freeze-dried at -60°C for 12 h to obtain a slow-release alkaline substance;

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

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

[0075] S4. The slow-release alkaline substance, the solidification 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 chitosan solution, then carbide slag was added, the mass ratio of carbide slag to chitosan was 10:1, and after stirring evenly, ultrasonic treatment was performed at 50 Hz for 2 h, followed by solid-liquid separation with a filter membrane, and the solid product was washed with deionized water and anhydrous ethanol for 3 times respectively, and finally freeze-dried at -60°C for 12 h to obtain a slow-release alkaline substance;

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

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

[0081] S4. The slow-release alkaline substance, the solidification 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 chitosan solution, then carbide slag was added, the mass ratio of carbide slag to chitosan was 10:1, and after stirring evenly, ultrasonic treatment was performed at 50 Hz for 2 h, followed by solid-liquid separation with a filter membrane, and the solid product was washed with deionized water and anhydrous ethanol for 3 times respectively, and finally freeze-dried at -60°C for 12 h to obtain a slow-release alkaline substance;

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

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

[0087] S4. The slow-release alkaline substance, the solidification 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 a slow-release excitation structure 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 best mass ratio of coarse sand, bentonite and plain clay is 1:1:6. Under this ratio, the grading is good, and the bentonite and plain clay fill the pores formed by the coarse sand, so the density is increased and water penetration is prevented.

[0093] Figure 4 The unconfined compressive strength test results of the water-retaining compacted backfill material with a slow-release excitation structure prepared in Examples 4-6 show that the unconfined compressive strengths of the water-retaining compacted backfill material prepared in Examples 4-6 are 1.1 MPa, 1.3 MPa, and 0.6 MPa, respectively, indicating that when the optimal mass ratio of coarse sand, bentonite, and plain clay is 1:1:6, the grading is good under this ratio, and the bentonite and plain clay 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, solidification 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 a slow-release excitation structure 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 solidifying 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 may be made to it in form and detail without departing from the core spirit and scope of the present invention defined in the appended claims.

[0097] The above description 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 regarded as 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. dissolving chitosan in acetic acid solution having a mass concentration of 1% to obtain a chitosan solution, adding carbide slag to the chitosan solution, stirring evenly, ultrasonically treating, and then separating the solid from the liquid, washing the obtained solid product, and freeze-drying to obtain a slow-release alkaline substance; S2. Mix magnesium oxide, granulated blast furnace slag, red mud, fly ash and sodium silicate 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. Evenly mix the slow-release alkaline substance, the solidification precursor, and the filling aggregate to obtain a mixture, and then add water and mix and stir 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 clay 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 of the coarse sand is in the range of 0.5 mm to 2 mm, the particle size of the bentonite is in the range of 0.001 mm to 0.05 mm, and the particle size of the plain clay is in the range of 0.075 mm to 1 mm.

8. The method for preparing the water-retaining compacted backfill material with a slow-release excitation structure as claimed in 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 with 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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