Calculation model of active pressure of large volume self-compacting uncemented tailings in open pit subsequent filling

Abstract

The application discloses a kind of large-volume self-compacting non-cemented tailings active pressure calculation model of open field subsequent filling, it is characterized by comprising the following steps: carry out the evolution law of self-compacting mechanism of non-cemented tailings in large empty area and the physical mechanics characteristics and strength mechanics of tailings under self-compacting condition, realize the accurate characterization of effective stress, physical mechanics characteristics, strength mechanics characteristics of self-compacting tailings, and construct the calculation model of active pressure of large-volume self-compacting non-cemented tailings of open field subsequent filling.The application carries out the evolution law of self-compacting mechanism of non-cemented tailings in large empty area and the physical mechanics characteristics and strength mechanics of tailings under self-compacting condition, realizes the accurate characterization of effective stress, physical mechanics characteristics, strength mechanics characteristics of self-compacting tailings, and constructs the calculation model of active pressure of large-volume self-compacting non-cemented tailings of open field subsequent filling;The model has important significance to perfect soil mechanics, granular mechanics theoretical research system.

Description

Technical Field

[0001] This invention belongs to the field of mining technology, specifically relating to an active pressure calculation model for large-volume self-compacting non-cemented tailings sand used in subsequent backfilling of open areas. Background Technology

[0002] With the increasing demand for mineral products in the national economy, the problems of solid waste storage and potential environmental and hazard issues in mines are becoming increasingly serious. Backfilling, as the main means of ground pressure management and solid waste treatment, can realize the harmless treatment and resource utilization of mine solid waste, and is the optimal choice for the development and utilization of mineral resources at present.

[0003] The stope-and-backfill mining method is a typical "two-step" continuous mining method. Its essence is to consider the treatment of the stope, pillars, and goaf as a whole, systematically and comprehensively recovering the ore, maximizing pillar recovery and minimizing ore loss, thus achieving continuous pillarless mining of the ore body. Its typical process involves dividing the ore body into stopes and pillars, mining the pillars first, then the stope, and cementing the pillars to form artificial pillars. The support structure formed by the cemented artificial pillars provides a safe and reliable working environment for stope mining. After stope mining is completed, the space created by the mining is filled. To save on filling costs, non-cemented filling is generally used. This method features high resource recovery rate, high mining intensity, and low overall filling cost, making it the main mining method for mining moderately stable, medium-thick or thicker ore bodies in the surrounding rock.

[0004] The support framework formed by stable cemented backfill is the safety guarantee of the mining site. The stability of cemented backfill depends on its own mechanical properties and its ability to resist disturbances from external environmental factors. The main factors affecting the stability of cemented backfill include: its own weight, the force of surrounding rock, the force of roof rock movement and failure, and the active pressure of non-cemented tailings.

[0005] During the mining of adjacent stops, cemented backfill bodies are exposed 2 to 4 times due to the mining sequence. This inevitably results in a mechanical state where one side is free-running and the other side is filled with non-cemented tailings. The tailings in the stope are under lateral pressure conditions. The flowability of the tailings and the lateral expansion generate active pressure, causing the cemented body to tend to slide towards the free-running side. Due to the influence of stope structural parameters (stope span 20-30m, height 30-60m, or even up to 100m), the cemented backfill body is affected by the active pressure of tailings over a wide range. Due to the stope mining and backfilling cycle, the cemented backfill body is subjected to the active pressure of tailings for a long time.

[0006] As an important structure in the open area, the stability of the sealed retaining wall is also affected by the active flow dynamics of the tailings backfill, thus impacting downhole safety.

[0007] Therefore, how to achieve the stability of single-sided exposed cemented backfill under the large-scale and long-term action of tailings active pressure, and the stability of closed retaining walls under the long-term action of tailings active pressure, has become one of the bottlenecks restricting the development and application of subsequent backfilling and continuous mining technology in open areas.

[0008] Tailings are typical porous granular media. Under pressure, particle migration and pore structure reorganization occur, macroscopically manifesting as volume shrinkage. Consequently, their physical and mechanical properties, as well as their strength properties, change. The physical and mechanical properties determine the magnitude of the overburden pressure on the tailings, while the strength properties determine their ability to flow autonomously. However, the compressibility of tailings exhibits nondeterministic mechanical characteristics, posing significant challenges to mathematical modeling and calculation.

[0009] Based on this, this invention takes the self-compacting dynamic behavior of non-gel tailings backfill in a large open space as the starting point, explores the physical and mechanical properties, strength and mechanical properties and self-weight compaction response mechanism of tailings, as well as the restricted flow mechanism of self-compacting tailings, and constructs an active pressure calculation model for subsequent backfilling of large-volume self-compacting non-gel tailings in an open space. Summary of the Invention

[0010] To address the aforementioned technical problems, this invention designs an active pressure calculation model for large-volume self-compacting non-gel tailings after void filling. By investigating the self-compacting mechanism of non-gel tailings in large void areas and the evolution of the physical and mechanical properties and strength mechanics of tailings under self-compacting conditions, this invention achieves accurate characterization of the effective stress, physical and mechanical properties, and strength mechanics of self-compacting tailings, and constructs a calculation model for the active pressure of large-volume self-compacting non-gel tailings after void filling. This model is of great significance for improving the theoretical research system of soil mechanics and granular mechanics, and deepening the structural and strength design theory of underground mining structures.

[0011] To achieve the above-mentioned technical effects, the present invention is implemented through the following technical solution: an active pressure calculation model for subsequent filling of large-volume self-compacting non-adhesive end sand in an open area, characterized by comprising the following steps:

[0012] Step 1: Construct a physical and mechanical parameter characterization model for self-compacting tailings:

[0013] Step 1.1: Conduct tailings lateral confined compression tests, obtain tailings compression characteristic curves, and construct a mathematical model of tailings density and overburden pressure.

[0014] Step 1.2: Analyze the mechanical equilibrium conditions of the non-gel tailings in the vertical direction in the subsequent backfilling of the mining area, and construct a mathematical model of the overburden pressure characterized by the tailings storage height.

[0015] Step 1.3: Construct a mathematical model for tailings density and occurrence height.

[0016] Step 1.4: Construct a calculation model for the self-weight stress of tailings.

[0017] Step 2: Construct a characterization model for the strength mechanical parameters of self-compacting tailings:

[0018] Step 2.1: Conduct direct shear tests on tailings with different densities to obtain the strength characteristic parameters of tailings with different densities, including cohesion and internal friction angle. Plot the relationship curves between the tailings strength characteristic parameters and the overburden pressure, and construct a mathematical model of the tailings strength characteristic parameters and the overburden pressure.

[0019] Step 2.2: Using the overburden pressure characterized by the tailings occurrence height, establish a mathematical model of the tailings strength characteristic parameters and occurrence height.

[0020] Step 3: Construct an active pressure calculation model for self-compacting tailings:

[0021] Step 3.1: Analyze the active pressure state of tailings and the influence of the physical and mechanical properties and strength mechanical properties of self-compacted tailings on the active pressure distribution law.

[0022] Step 3.2: Construct a mathematical model of the nonlinear growth characteristics of the basic physical parameters and strength characteristic parameters of self-compacting tailings and their influence on active pressure.

[0023] Furthermore, the mathematical model for the tailings density and overlying pressure in Step 1.1 can be expressed by the following formula:

[0024]

[0025] In the formula: ρ σ — Tailings compressibility, t / m³ 3 ;

[0026] σ v —Tailings overburden pressure, MPa;

[0027] A1—Compression coefficient related to the natural bulk density of tailings and affecting the density of tailings;

[0028] B1—Compression coefficient that affects tailings density and is related to the overburden pressure of tailings;

[0029] D1—A compressibility coefficient related to the porosity of naturally deposited tailings, affecting the density of tailings.

[0030] Furthermore, the mathematical model of overburden pressure characterized by tailings storage height in Step 1.2 can be expressed by equation (9):

[0031]

[0032] Where: h—arbitrary height of the tailings backfill body in the subsequent backfilling mining area, m.

[0033] Furthermore, the mathematical model for the tailings density and occurrence height in Step 1.3 can be expressed by equation (12):

[0034] ρ h =I[h+J] L (12)

[0035] in:

[0036]

[0037]

[0038] Where: I—compression coefficient that affects the density of tailings under self-compacting conditions and is related to the natural bulk density of tailings;

[0039] J—Compression coefficient that affects tailings density under self-compacting conditions and is related to the tailings height in the stope;

[0040] L—The compressibility coefficient that affects the density of tailings under self-compacting conditions and is related to the porosity of the natural accumulation of tailings.

[0041] Furthermore, the calculation model for the tailings self-weight pressure in Step 1.4 can be expressed by equation (14):

[0042]

[0043] Where: σ1—Self-weight stress of tailings in the subsequent backfilling of the mining area, MPa;

[0044] g—acceleration due to gravity, N / Kg.

[0045] Furthermore, in Step 2, the mathematical model of the cohesion and storage height of the self-compacting tailings can be expressed by equation (17):

[0046]

[0047] In the formula: c h —The cohesive force of tailings at any height within the stope after the open area is filled, MPa;

[0048] A2—Compression coefficient related to the cohesion of tailings in natural accumulation;

[0049] B2—A compressibility coefficient that affects the cohesion of tailings, which is related to the overburden pressure of tailings.

[0050] D2—A compressibility coefficient related to the porosity of naturally deposited tailings and affecting the cohesion of tailings.

[0051] Furthermore, the mathematical model for the internal friction angle and storage height of the self-compacting tailings in Step 2 can be expressed by equation (18):

[0052]

[0053] In the formula: —The internal friction angle of tailings at any height within the open area subsequently filled in, °;

[0054] A3—A compressibility coefficient related to the internal friction angle of tailings natural accumulation and affecting the internal friction angle of tailings;

[0055] B3—A compressibility coefficient that affects the internal friction angle of tailings and is related to the overburden pressure of the tailings.

[0056] D3—A compressibility coefficient related to the porosity of naturally deposited tailings and affecting the internal friction angle of the tailings.

[0057] Furthermore, the active pressure calculation model for self-compacting tailings in Step 3 can be expressed by equation (37):

[0058]

[0059] The self-weight stress σ1 is calculated according to formula (14), the cohesion of the tailings is calculated according to formula (17), and the internal friction angle of the tailings is calculated according to formula (18).

[0060] The beneficial effects of this invention are:

[0061] This invention, by investigating the self-compacting mechanism of non-cemented tailings in large open areas and the evolution of the physical and mechanical properties and strength mechanics of tailings under self-compacting conditions, achieves precise characterization of the effective stress, physical and mechanical properties, and strength mechanics of self-compacted tailings. It also constructs a calculation model for the active pressure of large-volume self-compacted non-cemented tailings used for subsequent backfilling of open areas. This is of great significance for improving the theoretical research system of soil mechanics and granular mechanics, and deepening the structural and strength design theory of underground mining structures. It enables precise calculation of the active pressure of large-volume self-compacted non-cemented tailings used for subsequent backfilling of open areas, providing a theoretical basis for retaining wall design and cemented backfill strength design, ensuring economical construction of retaining walls and cemented backfill under stable conditions. Furthermore, it enables precise calculation of the backfilling volume of non-cemented tailings in open areas, playing a crucial role in rationally arranging stope backfilling plans and ensuring seamless connection between mining and backfilling. Attached Figure Description

[0062] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0063] Figure 1 This is a process flow diagram of the present invention;

[0064] Figure 2 A schematic diagram of the stress analysis of tailings at any height within the stope for subsequent backfilling of the open area;

[0065] Figure 3 A schematic diagram of active pressure analysis for tailings in the subsequent backfilling of the open area;

[0066] Figure 4 It is a WG type single-lever consolidation apparatus;

[0067] Figure 5 The following are the results of a confined compression test of tailings from a copper mine in the example;

[0068] Figure 6 This is the fitting result of the curve of the relationship between tailings density and overlying pressure in a copper mine in the example;

[0069] Figure 7 The above are the calculation results of the self-weight stress of tailings at different filling heights in a copper mine mining area in the example.

[0070] Figure 8 ZJ type strain-controlled direct shear apparatus;

[0071] Figure 9 The figure shows the relationship between the cohesion of tailings in a copper mine and the overlying pressure in the example.

[0072] Figure 10 This is the fitting result of the curve of the relationship between the cohesion of tailings and the overlying pressure in a copper mine in the example;

[0073] Figure 11 The figure shows the relationship between the internal friction angle of a copper mine tailings and the overlying pressure in the example.

[0074] Figure 12 This is the fitting result of the curve of the relationship between the internal friction angle and the overlying pressure of a copper mine tailings in the example;

[0075] Figure 13 The above are the calculation results of the active pressure of tailings at different filling heights in a copper mine mining area in the example.

[0076] Figure 14 This is a pressure box used in a copper mine in the example;

[0077] Figure 15 This is an installation diagram of a pressure box in a copper mine, as shown in the example.

[0078] Figure 16 The example shows the on-site stress measurement at a copper mine. Detailed Implementation

[0079] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0080] Example 1

[0081] See Figures 1 to 16 As shown, a method for constructing an active pressure calculation model for subsequent filling of a void with large-volume self-compacting non-adhesive end sand includes the following steps:

[0082] (1) Constructing a physical and mechanical parameter characterization model for self-compacting tailings:

[0083] ① Conduct a tailings lateral confined compression test, record the volume deformation of tailings under the action of overburden pressure, and calculate the compression density of tailings under different overburden pressures. Obtain the tailings compression characteristic curve, that is, the curve of the relationship between density and overburden pressure. Use Origin fitting software to fit it, and then obtain the mathematical model of tailings density and overburden pressure, which is described by equation (1).

[0084]

[0085] In the formula: ρ σ — Tailings compressibility, t / m³ 3 ;

[0086] σ v —Tailings overburden pressure, MPa;

[0087] A1—Compression coefficient related to the natural bulk density of tailings and affecting the density of tailings;

[0088] B1—Compression coefficient that affects tailings density and is related to the overburden pressure of tailings;

[0089] D1—A compressibility coefficient related to the porosity of naturally deposited tailings, affecting the density of tailings.

[0090] ②Analyze the mechanical equilibrium conditions of the non-gel tailings in the vertical direction in the subsequent backfilling of the mining area, and construct a mathematical model to characterize the overburden pressure using the tailings storage height.

[0091] Subsequently, the vertical mechanical state of the tailings in the backfilled mining area is as follows: Figure 2 As shown, the equilibrium condition is given by equation (2).

[0092] σ v +γ h dh=σ v +dσ v (2)

[0093] In the formula: γ h —Subsequently, the unit weight of tailings at any height within the filling site, MN / m 3 ;

[0094] dh — Height of tailings micro-element, m;

[0095] dσ v —Increment of overburden pressure on tailings micro-elements, MPa.

[0096] Simplifying equation (2) yields:

[0097]

[0098] Integrating equation (3) yields:

[0099]

[0100] Where: h—height of tailings backfill in the subsequent backfilling mining area, m.

[0101] Substituting (1) into equation (4) and unifying the units, we get:

[0102]

[0103] Equation (5) is equivalent to:

[0104]

[0105] Taking the indefinite integral of the right-hand side of equation (6), we get:

[0106]

[0107] In the formula: f — is the integration constant.

[0108] Based on the boundary conditions σ=0 and h=0, substituting into equation (7) yields:

[0109]

[0110] Substituting equation (8) into equation (7), we get:

[0111]

[0112] From equation (9), we can obtain a mathematical model of overburden pressure characterized by tailings storage height:

[0113]

[0114] ③ Construct a mathematical model for tailings density and occurrence height.

[0115] Substituting equation (10) into equation (1), we obtain a mathematical model of tailings density and occurrence height, which can be described by equation (11):

[0116]

[0117] In the formula: ρ h —Density of tailings at any height within the mining area, kg / m³ 3 .

[0118] Equation (11) can be expressed as:

[0119] ρ h =I[h+J] L (12)

[0120] in:

[0121]

[0122]

[0123] Where: I—compression coefficient that affects the density of tailings under self-weight compaction conditions and is related to the natural bulk density of tailings;

[0124] J—Compression coefficient that affects tailings density under self-weight compaction conditions and is related to the tailings height in the stope;

[0125] L—The compressibility coefficient that affects the density of tailings under self-weight compaction conditions and is related to the porosity of the natural accumulation of tailings.

[0126] ④ Construct a calculation model for the self-weight pressure of tailings.

[0127] Given the mathematical relationship between tailings density and storage height, the tailings self-weight pressure calculation model can be described using (13):

[0128]

[0129] Substituting equation (12) into equation (13) yields:

[0130]

[0131] Where: σ1—Self-weight stress of tailings at any height in the subsequent filling of the open area, MPa.

[0132] (2) Constructing a characterization model for the strength mechanical parameters of self-compacting tailings:

[0133] ① Conduct direct shear tests on tailings with different densities to obtain the strength characteristic parameters of tailings with different densities, including cohesion and internal friction angle. Plot the relationship curves between the tailings strength characteristic parameters and the overburden pressure, and construct a mathematical model of the tailings strength characteristic parameters and the overburden pressure.

[0134] The relationship between cohesion and overburden pressure was fitted using Origin fitting software, and a mathematical model of tailings cohesion and overburden pressure was obtained, which can be described by equation (15).

[0135]

[0136] In the formula: c σ — Cohesion of tailings under pressure, MPa;

[0137] A2—Compression coefficient related to the cohesion of tailings in natural accumulation;

[0138] B2—A compressibility coefficient that affects the cohesion of tailings, which is related to the overburden pressure of tailings.

[0139] D2—A compressibility coefficient related to the porosity of naturally deposited tailings and affecting the cohesion of tailings.

[0140] The relationship between the internal friction angle and the overburden pressure was fitted using Origin fitting software, and a mathematical model of the relationship between the internal friction angle and the overburden pressure of the tailings was obtained, which can be described by equation (16).

[0141]

[0142] In the formula: —Internal friction angle of tailings under pressure, °;

[0143] A3—A compressibility coefficient related to the internal friction angle of tailings natural accumulation and affecting the internal friction angle of tailings;

[0144] B3—A compressibility coefficient that affects the internal friction angle of tailings and is related to the overburden pressure of the tailings.

[0145] D3—A compressibility coefficient related to the porosity of naturally deposited tailings and affecting the internal friction angle of the tailings.

[0146] ② Using the overburden pressure characterized by the tailings occurrence height, a mathematical model of the tailings strength characteristic parameters and occurrence height is established.

[0147] Substituting equation (10) into equation (15), we obtain a mathematical model of the cohesion and storage height of tailings, which can be described by equation (17):

[0148]

[0149] In the formula: c h—Cohesion of tailings at any height within the open area after backfilling, MPa.

[0150] Substituting equation (10) into equation (16), we can obtain a mathematical model of the internal friction angle and the storage height of the tailings, which can be described by equation (18):

[0151]

[0152] In the formula: —The internal friction angle of tailings at any height within the open area after filling is °.

[0153] (3) Constructing an active pressure calculation model for self-compacting tailings:

[0154] ①Analyze the active pressure state of tailings and the influence of the physical and mechanical properties and strength mechanical properties of self-compacted tailings on the active pressure distribution law.

[0155] Tailings active pressure state as follows Figure 3 As shown. Based on trigonometric relationships, we can obtain:

[0156] According to equation (19), we can obtain:

[0157]

[0158] according to Figure 3 The following triangular relationship exists:

[0159]

[0160] Where: σ3—active pressure of tailings at any height within the mining area, MPa.

[0161] From equation (21), we can obtain:

[0162]

[0163] Equation (22) is equivalent to:

[0164]

[0165] In trigonometric functions, the following relationships exist:

[0166]

[0167]

[0168]

[0169] In the formula: A, B — angle symbols, °.

[0170] Based on the functional relationships shown in equations (24), (25), and (26), equation (23) can be transformed into:

[0171]

[0172] In trigonometric functions, the following relationships exist:

[0173] sin(AB)=sin A cos B-cos A sin B (28)

[0174] Using equation (28), the equation in (27) can be transformed. Equivalent to:

[0175]

[0176] Substituting equation (29) into equation (27), we get:

[0177]

[0178] Equation (30) can be simplified to:

[0179]

[0180] Equation (31) can be simplified to:

[0181]

[0182] In trigonometric functions, the following relationships exist:

[0183]

[0184]

[0185] Using equations (33) and (34), equation (32) can be transformed into:

[0186]

[0187] The influence of the physical and mechanical properties and strength properties of self-compacting tailings on the active pressure distribution law can be described by equation (36):

[0188]

[0189] ② Construct a mathematical model of the nonlinear growth characteristics of the basic physical parameters and strength characteristic parameters of self-compacting tailings and their influence on active pressure.

[0190] According to equation (36), the calculation model for the active pressure of tailings can be obtained, and it is described by equation (37):

[0191]

[0192] Considering the nonlinear growth characteristics of the basic physical parameters and strength characteristics of self-compacting tailings, and their influence on active pressure, the self-weight stress σ1 of tailings in equation (37) is calculated according to equation (14), the cohesion of tailings is calculated according to equation (17), and the internal friction angle of tailings is calculated according to equation (18).

[0193] Example 2

[0194] A method for constructing an active pressure calculation model for subsequent filling of a void with large-volume self-compacting non-adhesive end sand is described below:

[0195] (1) Construct a physical and mechanical parameter characterization model for self-compacting tailings

[0196] The basic parameters of tailings from a copper mine are shown in Table 1.

[0197] Table 1. Parameters of tailings from a copper mine

[0198] <![CDATA[Bulk density (Kg / m 3 )]]> <![CDATA[True density (Kg / m 3 )]]> Density % Porosity % 1.466 2.897 50.6 49.4

[0199] Lateral confined compression tests were conducted on the copper mine tailings. The testing equipment included... Figure 4 As shown in Table 2, the volumetric deformation of the tailings under overlying pressure was recorded, and the porosity and density of the tailings after compression were calculated. The test results are shown in Table 2.

[0200] Table 2. Results of Lateral Confined Compression Test of Tailings in a Copper Mine

[0201] Overhead pressure (MPa) Compression ratio (%) Porosity (%) <![CDATA[density (t / m 3 )]]> 0.0 0.00 49.4 1.466 0.1 7.19 42.21 1.674 0.2 9.12 40.28 1.730 0.3 9.84 39.56 1.751 0.4 10.62 38.78 1.774 0.5 11.31 38.09 1.793 0.6 11.86 37.54 1.81 0.7 12.39 37.01 1.825 0.8 12.84 36.56 1.838 0.9 13.27 36.13 1.850 1.0 13.66 35.74 1.862 1.1 14.02 35.38 1.872 1.2 14.35 35.05 1.881 1.3 14.67 34.73 1.891 1.4 14.97 34.43 1.899 1.5 15.26 34.14 1.908

[0202] The relationship between tailings density and overlying pressure in Table 2 is plotted as follows: Figure 5 As shown. Origin fitting software was used to fit the data. Figure 5 The characteristic relationship curve shown is fitted, and the result is as follows: Figure 6 As shown.

[0203] According to the fitting results, A1 = 1.8617, B1 = 0.0085, and C1 = 0.0500; therefore, the mathematical model of tailings density and overlying pressure expressed by equation (1) can be written as:

[0204] ρ σ =1.8617×(σ v +0.0085) 0.05

[0205] The mathematical model of overburden pressure, represented by the tailings storage height, as expressed in equation (10) can be written as follows:

[0206] σ v = [0.0177 × (h + 0.61)] 1.0527 -0.0085

[0207] The mathematical model of tailings density and occurrence height represented by equation (12) can be written as:

[0208] ρ h = 1.5053 × [h + 0.61] 0.0527

[0209] The calculation model for the tailings self-weight pressure represented by equation (14) can be written as follows:

[0210]

[0211] The calculated results of tailings self-weight pressure under different filling heights for a stope height of 70m are as follows: Figure 7 As shown. After the stope filling is completed, the maximum self-weight stress of the tailings at the bottom of the stope is 1.23 MPa.

[0212] (2) Constructing a characterization model for the strength and mechanical parameters of self-compacting tailings

[0213] Direct shear tests were conducted on tailings of different densities from this copper mine. The testing equipment included... Figure 8 As shown in Table 3, the strength characteristic parameters of tailings with different densities were obtained, including tailings cohesion and internal friction angle.

[0214] Table 3 Results of direct shear tests on tailings of different densities from a copper mine

[0215]

[0216]

[0217] Based on the tailings strength test results with different densities shown in Table 3, the relationship curve between the cohesion of the tailings and the overburden pressure is plotted as follows: Figure 9 As shown, Origin numerical simulation software was used to simulate... Figure 9 The experimental results shown are fitted, taking tailings with a moisture content of 8% as an example, and the results are as follows: Figure 10 As shown.

[0218] According to the fitting results, A2 = 0.0231, B2 = 0.1180, and D2 = 0.2423; therefore, the mathematical model of tailings density and overlying pressure expressed by equation (15) can be written as:

[0219] c σ =0.0231×(σ v +0.118) 0.2423

[0220] Based on the tailings strength test results with different densities shown in Table 3, the relationship curve between the internal friction angle of the tailings and the overlying pressure is plotted as follows: Figure 11 As shown, Origin numerical simulation software was used to simulate... Figure 11 The experimental results shown are fitted, taking tailings with a moisture content of 8% as an example, and the results are as follows: Figure 12 As shown.

[0221] According to the fitting results, A3 = 4.8765, B3 = 12.8769, and C4 = 0.6895; therefore, the mathematical model of tailings density and overlying pressure expressed by equation (16) can be written as:

[0222]

[0223] Using the overburden pressure characterized by the tailings' storage height, a mathematical model of the tailings strength characteristic parameters and storage height is established. The mathematical model of tailings cohesion and storage height expressed by Equation (17) can be written as follows:

[0224] c h =0.0231×{[0.0177×(h+0.61)] 1.0527 +0.1095} 0.2423

[0225] The mathematical model of tailings cohesion and storage height represented by equation (18) can be written as follows:

[0226]

[0227] (3) Constructing an active pressure calculation model for self-compacting tailings

[0228] Considering the self-compacting characteristics of tailings, the calculation model of the active pressure of tailings expressed by equation (37) can be written as follows:

[0229]

[0230] In the formula:

[0231] c h =0.0231×{[0.0177×(h+0.61)] 1.0527 +0.1095} 0.2423

[0232]

[0233] The active pressure of tailings is calculated under different backfilling heights for a stope height of 70m. Figure 13 As shown, with the stope backfilling complete, the maximum active pressure of the bottom tailings is 0.3761 MPa.

[0234] (4) On-site monitoring of tailings self-weight stress and active pressure in the mining area

[0235] In a copper mine, the 92-95 panel is mined using large-diameter downward deep holes. After mining, non-cement tailings are used for backfilling. Before backfilling, a sealed retaining wall needs to be constructed in the ore access road. The design of the retaining wall's strength and thickness depends on the accurate calculation of the tailings' active pressure. Traditional tailings active pressure calculations treat tailings as naturally loose. However, tailings are a typical porous bulk medium with significant compressibility. Therefore, the influence of its compaction characteristics must be considered when calculating the tailings' active pressure.

[0236] The 92-95 stope has a height of 70m, a width of 25m, and a length of 50m. The self-weight stress of the tailings at different filling heights is as follows: Figure 7 As shown, the active pressure is as follows Figure 13 As shown. The maximum self-weight stress of the tailings at the bottom retaining wall is 1.23 MPa, and the maximum active stress is 0.3761 MPa. The retaining wall is designed to be 0.8 m thick and constructed with C25 concrete. To verify the accuracy of the active pressure calculation results, two pressure cells were installed on the retaining wall: one horizontally installed to measure the self-weight stress of the tailings, and one vertically installed to measure the active pressure. The pressure cells are shown below. Figure 14 As shown, the on-site installation is as follows Figure 15 As shown, the on-site measurements are as follows: Figure 16 As shown.

[0237] Table 4 shows the calculated and measured results of the self-weight stress and active stress of the tailings under different filling heights of the non-gel tailings in the subsequent backfilling of the open area.

[0238] Table 4. Monitoring results of tailings self-weight stress and active pressure in the 92-95 stope of a copper mine.

[0239]

[0240]

[0241] As shown in Table 4, the monitoring results of tailings self-weight stress are basically the same as the model calculation results, with a maximum error of 1.62%, a minimum error of 0.00%, and an average error of 0.70%, indicating that the model calculation accuracy is high.

[0242] The results of the active pressure monitoring of tailings were basically the same as those calculated by the model, with a maximum error of 2.03%, a minimum error of 0.00%, and an average error of 1.15%, indicating that the model calculation accuracy was high.

[0243] In summary, the method described in this invention can accurately calculate the self-weight stress and active pressure of tailings, providing a theoretical basis for the strength design of structures within the mining area, and achieving optimal cost while ensuring the stability of the structures.

[0244] In the description of this specification, references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0245] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to the specific implementations described. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention. The invention is limited only by the claims and their full scope and equivalents.

Claims

1. A method for calculating the active pressure of subsequent filling of a void with large-volume self-compacting non-adhesive end sand, characterized in that, Includes the following steps: Step 1: Construct a physical and mechanical parameter characterization model for self-compacting tailings: Step 1.1: Conduct tailings lateral confined compression tests, obtain tailings compression characteristic curves, and construct a mathematical model of tailings density and overburden pressure; Step 1.2: Analyze the mechanical equilibrium conditions of the non-gel tailings in the vertical direction in the subsequent backfilling of the mining area, and construct a mathematical model of the overburden pressure characterized by the tailings storage height. Step 1.3: Construct a mathematical model for tailings density and occurrence height; Step 1.4: Construct a calculation model for the self-weight stress of tailings; Step 2: Construct a characterization model for the strength mechanical parameters of self-compacting tailings: Step 2.1: Conduct direct shear tests on tailings with different densities to obtain the strength characteristic parameters of tailings with different densities, including cohesion and internal friction angle. Plot the relationship curve between the tailings strength characteristic parameters and the overburden pressure, and construct a mathematical model of the tailings strength characteristic parameters and the overburden pressure. Step 2.2: Using the overburden pressure characterized by the tailings storage height, establish a mathematical model of the tailings strength characteristic parameters and storage height; Step 3: Construct an active pressure calculation model for self-compacting tailings: Step 3.1: Analyze the active pressure state of tailings and the influence of the physical and mechanical properties and strength mechanical properties of self-compacted tailings on the active pressure distribution law; Step 3.2: Construct a mathematical model of the nonlinear growth characteristics of the basic physical parameters and strength characteristic parameters of self-compacting tailings and their influence on active pressure; The mathematical model for tailings density and overlying pressure in Step 1.1 can be expressed by the following formula: （1） In the formula: — Tailings compressibility, t / m³; —Tailings overburden pressure, MPa; —The compressibility coefficient that affects the density of tailings, which is related to the natural stock density of tailings. —The compressibility coefficient that affects the density of tailings, which is related to the overburden pressure of the tailings. —The compressibility coefficient that affects the density of tailings, which is related to the porosity of the natural accumulation of tailings. The mathematical model of overburden pressure characterized by tailings storage height in Step 1.2 can be expressed by equation (9): (9) In the formula: —Subsequently, the tailings backfill body within the mining area can be filled to any height, in meters.

2. The method for calculating the active pressure of large-volume self-compacting non-adhesive tailing sand subsequently filled in an open area according to claim 1, characterized in that: The mathematical model for tailings density and occurrence height in Step 1.3 can be expressed by equation (12): （12） in: In the formula: —The compressibility coefficient that affects the density of tailings under self-compacting conditions and is related to the natural bulk density of tailings. —The compressibility coefficient that affects the tailings density under self-compacting conditions and is related to the tailings height in the stope; —The compressibility coefficient that affects the density of tailings under self-compacting conditions, which is related to the porosity of the natural accumulation of tailings.

3. The method for calculating the active pressure of large-volume self-compacting non-adhesive end-filling sand in an open area according to claim 1, characterized in that: The calculation model for the tailings self-weight pressure in Step 1.4 can be expressed by equation (14): （14） In the formula: —Subsequently, the self-weight stress of tailings in the filling area is MPa; —Acceleration due to gravity, N / Kg.

4. The method for calculating the active pressure of large-volume self-compacting non-adhesive end-filling sand in an open area according to claim 1, characterized in that: In Step 2, the mathematical model of the cohesion and storage height of the self-compacting tailings can be expressed by equation (17): （17） In the formula: —The cohesive force of tailings at any height within the stope after the open area is filled, MPa; —The compressibility coefficient that affects the cohesion of tailings in natural accumulation; —Compression coefficient that affects the cohesion of tailings, which is related to the overburden pressure of tailings; —A compressibility coefficient that affects the cohesion of tailings and is related to the porosity of the natural accumulation of tailings.

5. The method for calculating the active pressure of large-volume self-compacting non-adhesive end sand for subsequent filling of an open area according to claim 1, characterized in that: The mathematical model for the internal friction angle and storage height of the self-compacting tailings in Step 2 can be expressed by equation (18): （18） In the formula: —The internal friction angle of tailings at any height within the open area subsequently filled; —The compressibility coefficient that affects the internal friction angle of tailings, which is related to the natural accumulation of tailings. —The compressibility coefficient that affects the internal friction angle of tailings, which is related to the overburden pressure of the tailings. —The compressibility coefficient that affects the internal friction angle of tailings and is related to the porosity of the natural accumulation of tailings.

6. The method for calculating the active pressure of large-volume self-compacting non-adhesive end-filling sand in an open area according to claim 1, characterized in that: The active pressure calculation model for self-compacting tailings in Step 3 can be expressed by equation (37): （37） Among them, self-weight stress The cohesion of the tailings is calculated according to formula (14), the internal friction angle of the tailings is calculated according to formula (17), and the internal friction angle of the tailings is calculated according to formula (18).

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