Method for calculating the compressive strength of mine waste-based backfill material

Abstract

This invention discloses a method for calculating the compressive strength of solid waste-based backfill materials in mining areas. The method includes: using the compressive strength of the backfill material as the dependent variable, and using the corresponding water-cement ratio, fly ash content, desulfurized gypsum content, foaming ratio, and water-reducing agent content as independent variables; fitting the linear relationship between the dependent variable and the five independent variables to obtain a multiple linear regression equation for compressive strength; substituting the water-cement ratio, fly ash content, desulfurized gypsum content, foaming ratio, and water-reducing agent content of the backfill material to be predicted into the multiple linear regression equation for compressive strength to obtain the predicted compressive strength of the backfill material. This invention proposes a method for calculating the compressive strength of solid waste-based backfill materials in mining areas, which can accurately predict the uniaxial compressive strength of these materials with an absolute error of less than 2%.

Description

Technical Field

[0001] This invention belongs to the field of mining area backfilling technology, specifically relating to a method for calculating the compressive strength of solid waste base backfilling materials in mining areas. Background Technology

[0002] The preparation of high-performance cemented backfill materials for mines based on high-volume solid waste has become a trend. This process uses fly ash, desulfurized gypsum and cement as raw materials. In this process, Ca(OH)2 generated by cement hydration will undergo a secondary pozzolanic reaction with active substances such as SiO2 and Al2O3 in fly ash, and finally generate aluminosilicate gel, which provides strength to the backfill material system and provides technical support for the large-scale resource utilization of industrial solid waste. However, current research still has some shortcomings. For example, when the fly ash content is 20% and 5% carbide slag is added, the physical and mechanical properties of the modified high-water material can be comparable to those of the pure high-water material, but the total solid waste content is only 25% and the cost advantage is insufficient (Shi Song, Liu Changwu, Wu Haikuan, et al. Study on physical and mechanical properties of high-water backfill material modified by fly ash-carbide slag double admixture [J]. Materials Reports, 2021, 35 (07): 7027-7032.). In addition, compressive strength is an important parameter of solid waste backfill material in mining areas. In order to accurately predict the compressive strength of solid waste backfill material in mining areas, existing technologies have proposed several strength prediction models. However, the existing strength prediction models are generally quite complex. For example, Lü Fengbin, Zhang Zhihong, Guo Lijie, et al. Establishment of backfill database and strength prediction model based on GA-SVM [J]. Mining and Metallurgy, 2025, 34(1):158-168. The GA-SVM model is used to predict the unconfined compressive strength of backfill. This GA-SVM model involves 13 independent variables and requires multiple database searches, data transformation, missing value imputation, etc., which makes the model too complex and cannot be widely applied. Summary of the Invention

[0003] To address the shortcomings of existing technologies, the present invention aims to provide a method for calculating the compressive strength of solid waste backfill materials in mining areas.

[0004] The objective of this invention is achieved through the following technical solution.

[0005] A method for calculating the compressive strength of solid waste backfill material in mining areas includes the following steps:

[0006] S1, taking the compressive strength of the solid waste backfill material in the mining area as the dependent variable, and the corresponding water-cement ratio, fly ash content, desulfurized gypsum content, foaming ratio, and water-reducing agent content as independent variables, the linear relationship between the dependent variable and the five independent variables is fitted as the multiple linear regression equation for compressive strength: ,in, This refers to the water-to-glue ratio. This refers to the fly ash content. The dosage of desulfurized gypsum. This refers to the foaming ratio. y represents the water-reducing agent dosage, and y represents the compressive strength. For constant terms, for The corresponding regression coefficients, for The corresponding regression coefficients, for The corresponding regression coefficients, for The corresponding regression coefficients, for The corresponding regression coefficients, wherein the compressive strength is the uniaxial compressive strength;

[0007] The preparation method of the solid waste base backfill material in the mining area includes: mixing the first system and the second system until uniform to obtain a slurry, pouring it, letting it stand until final setting, curing it, and obtaining the solid waste base backfill material in the mining area; the first system includes: a foaming agent and a first water; the second system includes: a cementitious material, a second water, and a water-reducing agent;

[0008] The ratio of foaming agent, first water, cementitious material, second water and water-reducing agent by mass parts is (1~2.5):(45~90):(180~600):(80~400):(0.5~6); the cementitious material is a mixture of cement, fly ash and desulfurized gypsum, and the ratio of cement, fly ash and desulfurized gypsum by mass parts is (30~350):(100~400):(10~150).

[0009] The water-cement ratio is the mass of the second water divided by the mass of the cementitious material; the fly ash content is the percentage of fly ash in the mass of the cementitious material; the desulfurized gypsum content is the percentage of desulfurized gypsum in the mass of the cementitious material; and the water-reducing agent content is the percentage of water-reducing agent in the mass of the cementitious material.

[0010] In S1, the compressive strength multiple linear regression equation is obtained by preparing N solid waste base filling materials from mining areas and fitting them, where N≥6.

[0011] S2, substitute the water-cement ratio, fly ash content, desulfurized gypsum content, foaming ratio and water-reducing agent content of the solid waste base filling material to be predicted into the multiple linear regression equation of compressive strength to obtain the compressive strength of the solid waste base filling material to be predicted.

[0012] In the above technical solution, the method for obtaining the first system includes: mixing a foaming agent and a first water to obtain a foaming agent solution, and stirring to make the foaming agent solution foam until the foaming ratio is 1~3.

[0013] In the above technical solution, the foaming agent is a plant protein foaming agent.

[0014] In the above technical solution, the water-reducing agent is a polycarboxylate-based water-reducing agent.

[0015] In the above technical solution, the settling time is 12~24h.

[0016] In the above technical solution, the method for obtaining the second system includes: mixing the cementitious material and the second water until uniform, adding the water-reducing agent, and mixing until uniform.

[0017] In the above technical solution, the first system and the second system are mixed and stirred until homogeneous.

[0018] In the above technical solutions, the curing time is 7 to 28 days.

[0019] In the above technical solution, the temperature of the maintenance environment is 19.5~20.5℃, and the relative humidity of the maintenance environment is 85~95%.

[0020] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0021] The solid waste-based backfill material for mining areas of this invention features high solid waste content (greater than or equal to 50%), high performance, and low cost. It effectively solves the problem of large-scale industrial solid waste accumulation in the region, improves the ecological and living environment of mines, and promotes green ecological governance in mines. This invention proposes a method for calculating the compressive strength of the solid waste-based backfill material for mining areas, using the uniaxial compressive strength of the material as the dependent variable and the corresponding water-cement ratio, fly ash content, desulfurized gypsum content, foaming ratio, and water-reducing agent content as independent variables. This method can accurately predict the uniaxial compressive strength of the material with an absolute error of less than 2%. Attached Figure Description

[0022] Figure 1 XRD patterns of cement, fly ash, and desulfurized gypsum;

[0023] Figure 2 The trend graph shows the plastic viscosity of the slurries prepared in Examples 1-16;

[0024] Figure 3 The trend graph shows the yield stress of the slurries prepared in Examples 1-16;

[0025] Figure 4 The XRD patterns of the solid waste-based backfill materials prepared in Examples 13-16 are shown below.

[0026] Figure 5SEM image of the solid waste-based backfill material prepared in Example 13, where b is a partial magnified view of a;

[0027] Figure 6 The elemental analysis diagram of the solid waste-based backfill material prepared in Example 13 is shown below.

[0028] Figure 7 SEM image of the solid waste-based backfill material prepared in Example 14, where b is a partial magnified view of a;

[0029] Figure 8 The elemental analysis diagram of the solid waste-based backfill material prepared in Example 14 is shown below.

[0030] Figure 9 SEM image of the solid waste-based backfill material prepared in Example 15, where b is a partial magnified view of a;

[0031] Figure 10 The elemental analysis diagram of the solid waste-based backfill material prepared in Example 15 is shown below.

[0032] Figure 11 SEM image of the solid waste-based backfill material prepared in Example 16, where b is a partial magnified view of a;

[0033] Figure 12 The elemental analysis diagram is shown for the solid waste-based backfill material prepared in Example 16.

[0034] exist Figure 2 and Figure 3 In the text, "L1" represents Example 1, "L2" represents Example 2, "L3" represents Example 3, "L4" represents Example 4, "L5" represents Example 5, "L6" represents Example 6, "L7" represents Example 7, "L8" represents Example 8, "L9" represents Example 9, "L10" represents Example 10, "L11" represents Example 11, "L12" represents Example 12, "L13" represents Example 13, "L14" represents Example 14, "L15" represents Example 15, and "L16" represents Example 16. Detailed Implementation

[0035] The technical solution of the present invention will be further described below with reference to specific embodiments.

[0036] Cement: Grade 42.5 ordinary Portland cement, purchased from Inner Mongolia Jidong Cement Co., Ltd., D50=11.37μm;

[0037] Fly ash: purchased from Donghua Thermal Power Plant in Inner Mongolia, D50=40.86μm;

[0038] Desulfurized gypsum: purchased from Donghua Thermal Power Plant in Inner Mongolia, D50=24.78μm.

[0039] The chemical composition of cement, fly ash, and desulfurized gypsum was determined using a Rigaku Ultima IV X-ray diffractometer, and the results are as follows: Figure 1 As shown. By Figure 1 It can be seen that the main phase composition of cement is tricalcium silicate, tetracalcium silicate, tricalcium aluminate and tetracalcium aluminoferrite, the main phase composition of fly ash is quartz, mullite and hematite, and the main phase composition of desulfurized gypsum is calcined gypsum.

[0040] Polycarboxylate superplasticizer: purchased from Shaanxi Qinfen Building Materials Co., Ltd., pale yellow liquid, density 1.1 g / cm³. 3 The water reduction rate is 37%.

[0041] Plant protein foaming agent: purchased from Dongguan Kaixuan Plastics Technology Co., Ltd., Guangdong Province; density: 1.09 g / cm³ 3 The solid content is 21.8%, and the pH is 6.8.

[0042] In the following embodiments, the temperature of the maintenance environment is 20°C and the relative humidity of the maintenance environment is 90%.

[0043] Foaming ratio (based on density calculation): A foaming agent solution with mass m1 is obtained by mixing the foaming agent and water. The volume of the foaming agent solution is denoted as V1. The density of the foaming agent solution is calculated based on m1 and V1 and denoted as ρ1. The solution is stirred to foam, and the density of the foam after foaming is measured by volumetric weighing and denoted as ρ2. The foaming ratio is essentially the volume ratio before and after foaming. Since only air is introduced during the foaming process, the mass of the foaming agent solution and the mass of the foam after foaming are essentially the same; therefore, the foaming ratio is calculated as ρ1 / ρ2.

[0044] Slump spread: Slump spread is one of the main methods for measuring flowability. Referring to GB / T 51450-2022 "Technical Standard for Backfilling Engineering in Metal and Non-metal Mines" and GB / T 50080−2016 "Standard for Test Methods of Performance of Ordinary Concrete Mixtures", a standard slump bucket with a top diameter of 100mm, a bottom diameter of 200mm, and a height of 300mm and a matching spread base were used to conduct three tests. The average value of the three tests was taken as the slump spread value.

[0045] The rheological properties of the slurry are evaluated by measuring yield stress and plastic viscosity, as these properties directly affect its flow and filling capacity during molding. The specific testing and calculation methods are as follows: The shear stress-shear rate curve of the slurry is measured using a rheometer. First, a shear stress-shear rate curve of 0.5 s⁻¹ is used. -1The shear rate was pre-sheared for 20 seconds, then held for 10 seconds, and then the shear rate was increased from 0.5 s⁻¹. -1 Reduced to 0.001 s -1 At a shear rate of 0.5 s⁻¹ -1 Reduced to 0.001 s -1 Ten sets of data were collected during the process (the shear rate corresponding to each of the ten sets of data was 0.5 s). -1 0.35 s -1 0.2 s -1 0.1 s -1 0.05 s -1 0.025 s -1 0.01 s -1 0.005 s -1 0.0025 s -1 and 0.001 s -1 Finally, the plastic viscosity and yield stress were calculated using the Bingham model based on the collected data.

[0046] Uniaxial compressive strength: Tests were conducted according to GB / T 51450-2022 "Technical Standard for Backfilling Engineering in Metal and Non-metal Mines" and GB / T 17671-2021 "Test Method for Strength of Cement Mortar". A TB-1 type 600kN microcomputer-controlled electro-hydraulic servo universal testing machine was used, with displacement control loading mode set, and uniaxial compression tests were performed at a rate of (1.00±0.05) mm / min. For each embodiment, multiple valid specimens were selected. After removing abnormal data with a deviation from the mean exceeding 15%, three specimens were randomly selected from the remaining valid specimens, and the arithmetic mean was taken as the final uniaxial compressive strength value.

[0047] Examples 1-16

[0048] A method for preparing a solid waste base filling material for mining areas includes: adding a first system to a second system, stirring at room temperature until uniform to obtain a slurry, immediately pouring the slurry into a standard cubic mold of 100mm × 100mm × 100mm, vibrating to remove large air bubbles, leveling the surface of the mold with a scraper, letting it stand for 24 hours until final setting, and curing it in a constant temperature and humidity curing room for 28 days to obtain the solid waste base filling material for mining areas;

[0049] The method for obtaining the first system includes: mixing the foaming agent and the first water to obtain a foaming agent solution, and stirring it at room temperature in a ZKR-5 type physical foaming machine (working pressure 0.6MPa) to make the foaming agent solution foam until the foaming ratio is A, thereby obtaining the first system;

[0050] The method for obtaining the second system includes: mixing the cementitious material and the second water, stirring at room temperature until homogeneous, adding the water-reducing agent, and stirring at room temperature until homogeneous to obtain the second system;

[0051] The ratio of foaming agent, first water, cementitious material, second water, and water-reducing agent by mass parts is X. The foaming agent is a plant protein foaming agent, the water-reducing agent is a polycarboxylate-based water-reducing agent, and the cementitious material is a mixture of cement, fly ash, and desulfurized gypsum. The ratio of cement, fly ash, and desulfurized gypsum by mass parts is Y. A, X, and Y are shown in Table 1.

[0052] Table 1

[0053]

[0054] Based on the values ​​of X and Y in Table 1, the "water-cement ratio," "fly ash content," "desulfurized gypsum content," and "water-reducing agent content" were calculated. Table 2 shows the "water-cement ratio," "fly ash content," "desulfurized gypsum content," "foaming ratio," and "water-reducing agent content" for Examples 1-16. The water-cement ratio was calculated as follows: the mass of the second water divided by the mass of the cementitious material; the fly ash content was the percentage of fly ash in the cementitious material's mass; the desulfurized gypsum content was the percentage of desulfurized gypsum in the cementitious material's mass; and the water-reducing agent content was the percentage of water-reducing agent in the cementitious material's mass.

[0055] Table 2

[0056]

[0057] The slump spread and uniaxial compressive strength of the solid waste base filling materials prepared in Examples 1-16 were tested, and the slump spread and uniaxial compressive strength obtained are shown in Table 3.

[0058] Table 3

[0059]

[0060] As shown in Table 3, the slump expansion and uniaxial compressive strength of the solid waste backfill material prepared in Example 12 are the highest. Among Examples 1 to 16, Example 12 is the optimal technical solution.

[0061] Plastic viscosity is an indicator of the internal frictional resistance of a fluid, reflecting the magnitude of intermolecular forces during fluid flow. The lower the plastic viscosity, the better the fluidity of the slurry and the easier it is to pump. Yield stress is the minimum shear stress required for a fluid to begin flowing. The lower the yield stress, the better the fluidity of the slurry. The slurries prepared in Examples 1-16 were tested for plastic viscosity and yield stress. Specifically, freshly prepared slurries were left to stand, and tests were conducted on slurries at 30 minutes, 60 minutes, and 90 minutes. The trend graphs of the plastic viscosity and yield stress of the slurries are shown below. Figure 2 and Figure 3 As shown. (Through) Figure 2 and Figure 3 It can be seen that with the increase of the water-cement ratio, the plastic viscosity and yield stress of the slurry both show a decreasing trend overall. This is because the more water there is, the thicker the water film layer adsorbed on the surface of the cementitious material particles, effectively reducing the frictional resistance between the cementitious material particles, thereby reducing the plastic viscosity of the slurry and improving the rheological properties of the freshly mixed backfill material (the slurry state that has just been prepared and has not yet hardened). Considering the plastic viscosity and yield stress of the slurry, as well as the slump spread and uniaxial compressive strength of the solid waste base backfill material in the mining area, Example 12 is the better choice.

[0062] The internal microstructure of the solid waste backfill material in the mining area was characterized using scanning electron microscopy (SEM) and X-ray diffraction (XRD). The solid waste backfill material was crushed and cleaved (cleavage: breaking it into powder), and the cleaved cross-section was taken as a sample. The sample was then sputter-coated with gold before characterization tests to eliminate the charging effect of non-conductive samples.

[0063] Figure 4 Example 13 ( Figure 4 (50% solid waste content in the middle), Example 14 ( Figure 4 (60% solid waste content in the middle), Example 15 ( Figure 4 "70% solid waste content" and Example 16 ( Figure 4 XRD pattern of the solid waste-based backfill material prepared from the mine (with an 80% solid waste content). The solid waste content is the sum of the fly ash content and the desulfurized gypsum content. Figure 4 It can be seen that the peak intensity of the quartz phase near 19.6° and 22.0° tends to increase with the increase of solid waste content. Kaolinite appears at 28.9° in Examples 13-16, and calcium silicate appears at 36.0° in Examples 13-16. Calcium silicate and kaolinite are hydration products, indicating that cement and fly ash undergo hydration. The different peak intensities of kaolinite and calcium silicate under different solid waste content indicate that the degree of hydration varies with different solid waste content. Characteristic peaks of ettringite and sodium mica can be detected in Examples 13-16, indicating that as the reaction proceeds, the active glass phase in fly ash dissolves and participates in the reaction to form ettringite (AFt) and sodium mica. Mullite and limestone are reaction byproducts.

[0064] Figure 5 a and Figure 5 b is a SEM image of the solid waste-based backfill material prepared in Example 13, wherein, Figure 5 b is Figure 5 A magnified view of part 'a'. Figure 6 The elemental analysis diagram is shown for the solid waste-based backfill material prepared in Example 13. Figure 7 a and Figure 7 b is a SEM image of the solid waste-based backfill material prepared in Example 14, wherein, Figure 7 b is Figure 7 A magnified view of part 'a'. Figure 8 The elemental analysis diagram is shown for the solid waste-based backfill material prepared in Example 14. Figure 9 a and Figure 9 b is a SEM image of the solid waste-based backfill material prepared in Example 15, wherein, Figure 9 b is Figure 9 A magnified view of part 'a'. Figure 10 The elemental analysis diagram is shown for the solid waste-based backfill material prepared in Example 15. Figure 11 a and Figure 11 b is a SEM image of the solid waste-based backfill material prepared in Example 16, wherein, Figure 11 b is Figure 11 A magnified view of part 'a'. Figure 12 The elemental analysis diagram is shown for the solid waste-based backfill material prepared in Example 16.

[0065] Example 13 (45% fly ash and 5% desulfurized gypsum) and Example 16 (60% fly ash and 20% desulfurized gypsum) were compared. Figure 5 a, Figure 5 b, Figure 11 a and Figure 11 As shown in b, in Figure 11 More ettringite (AFt) can be observed in b. Furthermore, from Figure 11 b also shows that, due to the excessive amount of fly ash, a small amount of fly ash that did not participate in the hydration reaction was present in the solid waste base filling material prepared in Example 16. Figure 11 (in b, "unhydrated FA").

[0066] Example 17

[0067] A method for calculating the compressive strength of solid waste backfill material in mining areas includes the following steps:

[0068] S1. Using the water-cement ratio, fly ash content, desulfurized gypsum content, foaming ratio, and water-reducing agent content corresponding to the 16 mining areas' solid waste base backfill materials in Table 2 as independent variables, and the uniaxial compressive strength of the 16 mining areas' solid waste base backfill materials in Table 3 as the dependent variable, the linear relationship between the dependent variable and the five independent variables is fitted as the multiple linear regression equation for compressive strength: ,in, This refers to the water-to-glue ratio. This refers to the fly ash content. The dosage of desulfurized gypsum. This refers to the foaming ratio. y represents the water-reducing agent dosage; y represents the uniaxial compressive strength. The fitting was performed using the analysis command in Origin, employing a linear least squares data fitting method.

[0069] S2, substitute the water-cement ratio, fly ash content, desulfurized gypsum content, foaming ratio and water-reducing agent content of the solid waste base filling material to be predicted into the multiple linear regression equation of compressive strength to obtain the uniaxial compressive strength of the solid waste base filling material to be predicted.

[0070] Comparative Example 1

[0071] A method for calculating the compressive strength of solid waste backfill material in mining areas is basically the same as that in Example 17, except that the water-cement ratio ( ), desulfurized gypsum dosage ( ), foaming ratio ( ) and water-reducing agent dosage ( Using uniaxial compressive strength (y) as the dependent variable and y as the independent variable, the linear relationship between the dependent variable and the four independent variables was fitted to obtain the multiple linear regression equation for compressive strength. The multiple linear regression equation for compressive strength obtained in Comparative Example 1 is: .

[0072] Comparative Example 2

[0073] A method for calculating the compressive strength of solid waste backfill material in mining areas is basically the same as that in Example 17, except that the difference lies only in the fly ash content ( ), desulfurized gypsum dosage ( ), foaming ratio ( ) and water-reducing agent dosage ( Using uniaxial compressive strength (y) as the dependent variable and y as the independent variable, the linear relationship between the dependent variable and the four independent variables was fitted to obtain the multiple linear regression equation for compressive strength. The multiple linear regression equation for compressive strength obtained in Comparative Example 2 is as follows: .

[0074] Comparative Example 3

[0075] A method for calculating the compressive strength of solid waste backfill material in mining areas is basically the same as that in Example 17, except that the water-cement ratio ( ), fly ash content ( ), desulfurized gypsum dosage ( ) and foaming ratio ( Using uniaxial compressive strength (y) as the dependent variable and y as the independent variable, the linear relationship between the dependent variable and the four independent variables was fitted to obtain the multiple linear regression equation for compressive strength. The multiple linear regression equation for compressive strength obtained in Comparative Example 3 is as follows: .

[0076] Comparative Example 4

[0077] A method for calculating the compressive strength of solid waste backfill material in mining areas is basically the same as that in Example 17, except that the water-cement ratio ( ), fly ash content ( ), foaming ratio ( ) and water-reducing agent dosage ( Using uniaxial compressive strength (y) as the dependent variable and y as the independent variable, the linear relationship between the dependent variable and the four independent variables was fitted to obtain the multiple linear regression equation for compressive strength. The multiple linear regression equation for compressive strength obtained in Comparative Example 4 is as follows: .

[0078] Comparative Example 5

[0079] A method for calculating the compressive strength of solid waste backfill material in mining areas is basically the same as that in Example 17, except that the water-cement ratio ( ), fly ash content ( ), desulfurized gypsum dosage ( ) and water-reducing agent dosage ( Using uniaxial compressive strength (y) as the dependent variable and y as the independent variable, the linear relationship between the dependent variable and the four independent variables was fitted to obtain the multiple linear regression equation for compressive strength. The multiple linear regression equation for compressive strength obtained in Comparative Example 5 is as follows: .

[0080] Formula applicability test:

[0081] As a verification example 1, the preparation method of the solid waste base filling material in the mining area includes: adding the first system to the second system, stirring until uniform at room temperature to obtain a slurry, pouring the slurry into a standard cubic mold of 100mm × 100mm × 100mm, vibrating to remove large air bubbles, leveling the surface of the mold with a scraper, letting it stand for 24 hours until final setting, and curing it in a constant temperature and humidity curing room for 28 days to obtain the solid waste base filling material in the mining area.

[0082] The method for obtaining the first system includes: mixing a foaming agent and a first water to obtain a foaming agent solution, and stirring it at room temperature in a ZKR-5 type physical foaming machine (working pressure 0.6MPa) to foam the foaming agent solution until the foaming ratio is 1, thereby obtaining the first system; the method for obtaining the second system includes: mixing a cementitious material and a second water, stirring at room temperature until homogeneous, adding a water-reducing agent, and stirring at room temperature until homogeneous, thereby obtaining the second system;

[0083] By mass parts, the ratio of foaming agent, first water, cementing material, second water and water-reducing agent is 1.2:58:597.55:235.6:0.589. The foaming agent is a plant protein foaming agent, the water-reducing agent is a polycarboxylate water-reducing agent, and the cementing material is a mixture of cement, fly ash and desulfurized gypsum. By mass parts, the ratio of cement, fly ash and desulfurized gypsum is 328.9:239.2:29.45.

[0084] As a verification example 2, the preparation method of the solid waste base filling material in the mining area includes: adding the first system to the second system, stirring until uniform at room temperature to obtain a slurry, pouring the slurry into a standard cubic mold of 100mm × 100mm × 100mm, vibrating to remove large air bubbles, leveling the surface of the mold with a scraper, letting it stand for 24 hours until final setting, and curing it in a constant temperature and humidity curing room for 28 days to obtain the solid waste base filling material in the mining area.

[0085] The method for obtaining the first system includes: mixing a foaming agent and a first water to obtain a foaming agent solution, and stirring it at room temperature in a ZKR-5 type physical foaming machine (working pressure 0.6MPa) to foam the foaming agent solution until the foaming ratio is 1, thereby obtaining the first system; the method for obtaining the second system includes: mixing a cementitious material and a second water, stirring at room temperature until homogeneous, adding a water-reducing agent, and stirring at room temperature until homogeneous, thereby obtaining the second system;

[0086] By mass parts, the ratio of foaming agent, first water, cementing material, second water and water-reducing agent is 1.2:58:589:353.6:5.89. The foaming agent is a plant protein foaming agent, the water-reducing agent is a polycarboxylate water-reducing agent, and the cementing material is a mixture of cement, fly ash and desulfurized gypsum. By mass parts, the ratio of cement, fly ash and desulfurized gypsum is 206.15:235.6:147.25.

[0087] The "water-cement ratio", "fly ash content", "desulfurized gypsum content", "foaming ratio" and "water-reducing agent content" of verification examples 1-2 are shown in Table 4.

[0088] Table 4

[0089]

[0090] Using verification examples 1-2 as the backfill materials for the solid waste base in the mining area to be predicted, and substituting them into the multiple linear regression equation for compressive strength in Example 17 and Comparative Examples 1-5, the compressive strength of the backfill materials for the solid waste base in the mining area to be predicted is obtained as the fitted value of the uniaxial compressive strength.

[0091] The uniaxial compressive strength of the backfill material prepared in Verification Example 1 was tested, and the experimental value of the uniaxial compressive strength was 5.89 MPa. Based on the multiple linear regression equation for compressive strength, the corresponding independent variables of Verification Example 1 were substituted into the multiple linear regression equations for compressive strength of Examples 17 and Comparative Examples 1-5 to obtain the fitted values ​​of the uniaxial compressive strength, as shown in Table 5. In Table 5, "Error (%)" = ((fitted value of uniaxial compressive strength - experimental value of uniaxial compressive strength) / experimental value of uniaxial compressive strength) * 100%.

[0092] Table 5

[0093]

[0094] The uniaxial compressive strength of the backfill material prepared in Verification Example 2 was tested, and the experimental value of the uniaxial compressive strength was 7.44 MPa. Based on the multiple linear regression equation for compressive strength, the corresponding independent variables of Verification Example 2 were substituted into the multiple linear regression equations for compressive strength of Examples 17 and Comparative Examples 1-5 to obtain the fitted values ​​of the uniaxial compressive strength, as shown in Table 6. In Table 6, "Error (%)" = ((fitted value of uniaxial compressive strength - experimental value of uniaxial compressive strength) / experimental value of uniaxial compressive strength) * 100%.

[0095] Table 6

[0096]

[0097] According to Tables 5 and 6, the uniaxial compressive strength calculated by the multiple linear regression equation of compressive strength in Example 17 of the present invention is closest to the uniaxial compressive strength obtained by actual testing. The multiple linear regression equation of compressive strength in Example 17 can well predict the uniaxial compressive strength of the solid waste base filling material in the mining area.

[0098] The present invention has been described above by way of example. It should be noted that any simple modifications, alterations or other equivalent substitutions that can be made by those skilled in the art without creative effort without departing from the core of the present invention fall within the protection scope of the present invention.

Claims

1. A method of calculating the compressive strength of a mine waste-based backfill material, characterised in that, Includes the following steps: S1, taking the compressive strength of the solid waste backfill material in the mining area as the dependent variable, and the corresponding water-cement ratio, fly ash content, desulfurized gypsum content, foaming ratio, and water-reducing agent content as independent variables, the linear relationship between the dependent variable and the five independent variables is fitted as the multiple linear regression equation for compressive strength: ,in, This refers to the water-to-glue ratio. This refers to the fly ash content. The dosage of desulfurized gypsum. This refers to the foaming ratio. For the dosage of water-reducing agent, Compressive strength; For constant terms, for The corresponding regression coefficients, for The corresponding regression coefficients, for The corresponding regression coefficients, for The corresponding regression coefficients, for The corresponding regression coefficient, the compressive strength is the uniaxial compressive strength; the preparation method of the mine solid waste base filling material includes: mixing the first system and the second system until uniform to obtain slurry, pouring, standing until final setting, curing, to obtain the mine solid waste base filling material; the first system includes: foaming agent and first water; the second system includes: cementing material, second water and water reducing agent; The ratio of foaming agent, first water, cementitious material, second water and water-reducing agent by mass parts is (1~2.5):(45~90):(180~600):(80~400):(0.5~6); the cementitious material is a mixture of cement, fly ash and desulfurized gypsum, and the ratio of cement, fly ash and desulfurized gypsum by mass parts is (30~350):(100~400):(10~150). The water-cement ratio is the mass of the second water divided by the mass of the cementitious material; the fly ash content is the percentage of fly ash in the mass of the cementitious material; the desulfurized gypsum content is the percentage of desulfurized gypsum in the mass of the cementitious material; the water-reducing agent content is the percentage of water-reducing agent in the mass of the cementitious material. S2, substitute the water-cement ratio, fly ash content, desulfurized gypsum content, foaming ratio and water-reducing agent content of the backfill material to be predicted into the multiple linear regression equation of compressive strength to obtain the compressive strength of the backfill material to be predicted; by preparing N backfill materials of the backfill material to be predicted, the multiple linear regression equation of compressive strength is obtained, N≥6.

2. The method for calculating the compressive strength of solid waste backfill material in mining areas according to claim 1, characterized in that, The method for obtaining the first system includes: mixing a foaming agent and a first water to obtain a foaming agent solution, and stirring the foaming agent solution to foam it until the foaming ratio is 1 to 3.

3. The method of claim 1, wherein, The method for obtaining the second system includes: mixing the cementitious material and the second water until homogeneous, adding the water-reducing agent, and mixing until homogeneous.

4. The method of claim 2, wherein, The foaming agent is a plant protein foaming agent.

5. The method of claim 3, wherein, The water-reducing agent is a polycarboxylate-based water-reducing agent.

6. The method of calculating the compressive strength of a mine waste based fill material according to claim 1, wherein, The settling time is 12-24 hours.

7. The method of calculating the compressive strength of a mine waste based fill material according to claim 1, wherein, The maintenance period is 7 to 28 days.

8. The method of claim 7, wherein, The temperature of the maintenance environment is 19.5~20.5℃, and the relative humidity of the maintenance environment is 85~95%.

9. The method of calculating the compressive strength of a mine waste based fill material according to claim 1, wherein, Mix the first and second systems and stir until homogeneous.

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