A method for determining the heterogeneous characteristic parameters of a large-inclination roadway gangue cemented filling body

Abstract

The present application belongs to the technical field of coal mine filling mining, and particularly relates to a method for determining the heterogeneous characteristic parameters of gangue cemented filling body in a large-inclination roadway. First, the mining geological condition information of the large-inclination filling roadway is collected, and the heterogeneous characteristic parameters are tested through the pouring, demolding, curing and heterogeneous characteristic parameter testing of the material according to the composition and proportioning of the filling material. The heterogeneous characteristic parameters of the gangue cemented filling body under the conditions of the gangue particle size and the mold inclination change are studied. Finally, the relationship between the heterogeneous characteristic parameters and the inclination and the gangue particle size is obtained through the fitting analysis of the test data. Finally, the actual engineering parameters of the large-inclination roadway, i.e. the inclination and the gangue particle size, are substituted into the relationship to further determine the heterogeneous characteristic parameters of the gangue cemented filling body in the actual engineering site of the large-inclination roadway. The method can provide a new method for determining the heterogeneous characteristics of the filling body in the large-inclination roadway, thereby providing more accurate parameter basis for the stability analysis and control of the roadway surrounding rock.

Description

Technical Field

[0001] This invention belongs to the field of coal mine backfilling technology, specifically relating to a method for determining the heterogeneous characteristic parameters of gangue cemented backfill in steeply inclined roadways. Background Technology

[0002] Coal mining generates a large amount of coal gangue, whose stockpiling poses serious environmental and safety problems. Backfilling technology is an effective means of large-scale disposal of coal gangue and control of surrounding rock deformation in goaf areas. Gangue cemented backfill materials use coal gangue as aggregate, supplemented with cement, fly ash, and other cementing materials, and are filled into goaf areas or roadways to support the roof and control the surrounding rock. However, in existing theoretical research and engineering applications, the backfill body is treated as a homogeneous material for mechanical property testing, numerical simulation analysis, and engineering applications. In reality, especially when backfilling roadways with large dip angles, significant spatial heterogeneity in mechanical properties, i.e., non-homogeneity, will form inside the backfill body due to differences in slurry fluidity and the sedimentation and segregation of coarse solid particles under gravity. This non-homogeneity caused by dip angle and gangue particle size is macroscopically manifested as a significant difference in the spatial mechanical parameters of the backfill body at different locations along the dip length of the roadway. Current testing and application methods based on the traditional assumption of homogeneous characteristics are insufficient for accurately predicting and controlling the stability of surrounding rock. Their precision is also insufficient to scientifically guide field applications, and they pose certain engineering safety risks. Therefore, there is an urgent need for a scientific method to determine the heterogeneous characteristic parameters of cemented gangue backfill in steeply inclined tunnels, thereby solving practical engineering problems in the field. Summary of the Invention

[0003] In view of the shortcomings of the aforementioned background technology, the present invention aims to solve the technical problem of inaccurate prediction of mechanical parameters caused by treating the gangue cemented backfill of steeply inclined roadways as a homogeneous material. Specifically, the present invention provides a method for determining the heterogeneous characteristic parameters of gangue cemented backfill in steeply inclined roadways, so as to quantify the spatial heterogeneity (i.e., heterogeneity) of the mechanical properties of the backfill caused by the influence of roadway dip angle and gangue particle size, thereby providing accurate parameter basis for the stability analysis and control of roadway surrounding rock.

[0004] To achieve the above objectives, the present invention adopts the following technical solution:

[0005] A method for determining the heterogeneous characteristic parameters of gangue cemented backfill in steeply inclined roadways includes the following steps:

[0006] S1. Collect the actual engineering geological parameters of the steeply inclined roadway to be filled, including at least the roadway inclination angle. Length of tunnel And the composition and proportion of filling materials used for on-site tunnel filling;

[0007] S2. Based on the actual engineering geological parameters and the preset geometric similarity ratio Determine the mold length used to prepare laboratory standard test specimens. ;

[0008] S3, Controlling gangue particle size Keeping the angle constant, prepare multiple sets of mold tilt angles Different standard samples of gangue cemented backfill were tested, and the heterogeneous characteristic parameters of each group of samples were obtained. Through data fitting, a relationship between the heterogeneous characteristic parameters and the mold inclination angle was established. Relationship;

[0009] S4, Control mold tilt angle With the same parameters, multiple groups of gangue particle sizes were prepared. Different standard samples of gangue cemented backfill were tested, and the heterogeneous characteristic parameters of each group of samples were obtained. Through data fitting, a relationship between the heterogeneous characteristic parameters and gangue particle size was established. Relationship;

[0010] S5. The tunnel dip angle in the actual engineering geological parameters... and gangue particle size Substitute the values ​​into the relationships obtained in steps S3 and S4 respectively to perform calculations and determine the different positions of the steeply inclined roadway along its length. The heterogeneous characteristic parameters of the gangue cemented backfill at the location.

[0011] Furthermore, in steps S3 and S4, the heterogeneous characteristic parameters include at least one of uniaxial compressive strength, density, elastic modulus, cohesion, and internal friction angle.

[0012] Further, step S3 specifically includes: maintaining the particle size of the gangue. Unchanged, at multiple different mold tilt angles The molds were cast, cured, and prepared into multiple sets of standard specimens. Specimens within the same set were numbered and tested along the length of the mold to obtain the heterogeneous characteristic parameters of each numbered location. The results were then analyzed for different mold inclination angles. By fitting the parameter values ​​of samples with the same number, the heterogeneous characteristic parameters at each number position and the mold tilt angle are obtained. The relational expression.

[0013] Further, step S4 specifically includes: maintaining the mold tilt angle The same applies, but various different gangue particle sizes are used. The aggregates were cast, cured, and prepared into multiple sets of standard samples. Samples within the same set were numbered and tested along the length of the mold to obtain the heterogeneous characteristic parameters of samples at each numbered location. Different gangue particle sizes were also tested. By fitting the parameter values ​​of samples with the same number, the heterogeneous characteristic parameters and gangue particle size at each number position were obtained. The relational expression.

[0014] Furthermore, in step S1, the inclination angle of the steep-angle tunnel... The range is 35°≤ ≤70°.

[0015] Further, in step S2, the cross-section of the mold is square, and the geometric similarity ratio... It is obtained through the following formula:

[0016] ;

[0017] In the formula, The length of the tunnel; The number of samples numbered along the length of the mold; The length of a single sample.

[0018] Further, in steps S3 and S4, the particle size of the gangue... maximum value No more than 20 mm.

[0019] Beneficial effects:

[0020] This invention overcomes the limitations of the traditional assumption of homogeneous properties in backfill materials. Through systematic experiments and mathematical regression analysis, a quantitative relationship is established between the heterogeneous property parameters of the backfill material and the roadway dip angle and gangue particle size, thereby determining the heterogeneous property parameters of gangue-cemented backfill materials in steeply inclined roadways in actual engineering sites. Based on laboratory test results, this method can scientifically determine the spatial distribution characteristics of the heterogeneous properties of backfill materials in steeply inclined roadways in actual engineering sites, thus providing more accurate parameter basis for the stability analysis and control of roadway surrounding rock. Attached Figure Description

[0021] Figure 1 This is a schematic diagram illustrating the principle of the method for determining the heterogeneous characteristic parameters of gangue cemented backfill in steeply inclined tunnels according to the present invention.

[0022] Figure 2 This is a laboratory mold used in the present invention for determining the heterogeneous characteristic parameters of a cemented gangue filling body in a steeply inclined tunnel.

[0023] Figure 3 Different tilt angles in Embodiment 1 of the present invention Curves showing the variation of heterogeneous characteristic parameters (uniaxial compressive strength) of gangue cemented backfill under varying conditions.

[0024] Figure 4This is a fitting curve of the uniaxial compressive strength of the cemented heterogeneous backfill of gangue in the roadway versus the roadway location in Embodiment 1 of the present invention.

[0025] Figure 5 Different gangue particle sizes in Embodiment 2 of the present invention Curves showing the variation of heterogeneous characteristic parameters (uniaxial compressive strength) of gangue cemented backfill under varying conditions.

[0026] Figure 6 This is a fitting curve of the uniaxial compressive strength of the cemented heterogeneous backfill material of gangue in the roadway and the roadway location in Embodiment 2 of the present invention.

[0027] In the figure: 1-filling pump; 2-upper end of steep angle roadway; 3-filling pipeline; 4-gangue filling slurry; 5-fine-particle gangue filling body; 6-coarse-particle gangue filling body; 7-filling retaining wall; 8-lower end of steep angle roadway; 9-standard cubic sample; 10-mold body. Detailed Implementation

[0028] 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, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0029] Example 1

[0030] A certain mine has a designed annual production capacity of 3 million tons. The main coal seam is No. 2 coal seam, with a burial depth of approximately 400m, an average thickness of 3m, and an average dip angle of 40°, making it a typical steeply dipped coal seam. The longwall mining method of roadway cemented backfilling is used for coal mining.

[0031] S1. Collect actual engineering geological parameters of the steeply inclined tunnel to be filled.

[0032] Collect the geological conditions and design parameters of the target steeply inclined tunnel to obtain the tunnel inclination angle. The angle is 40°, falling within the large dip angle range of 35° to 70°, and the planned filling length of the tunnel is... The tunnel is 50m long, with a cross-sectional dimension of 4m wide and 3m high. The on-site filling system mainly includes a filling pump 1 located at the top of the tunnel. The filling pump 1 is connected to the upper end 2 of the steeply inclined tunnel via a filling pipeline 3, and is used to pump gangue filling slurry 4. A filling retaining wall 7 is installed at the lower end 8 of the steeply inclined tunnel. During the actual filling process, as the gangue filling slurry 4 pumped into the tunnel flows downward along the steeply inclined tunnel, it is subjected to gravity. Finer particles settle slowly and tend to accumulate in the upper part of the tunnel, forming fine-particle gangue filling body 5; while coarser particles settle quickly and tend to accumulate in the lower part or lower end of the tunnel, forming coarse-particle gangue filling body 6. This difference in filling body structure caused by particle sorting is one of the fundamental reasons for the heterogeneous characteristics of the filling body. At the same time, the composition and proportion of the filling materials to be used on site were obtained: cement and fly ash are used as cementing materials, and the aggregate has an average particle size of =18mm coal gangue, the sand-to-cement ratio (mass ratio of aggregate to cementitious material) is set at 7:3, and the water-to-cement ratio is 0.5.

[0033] S2. Determine the size of the laboratory mold based on actual engineering geological parameters and a preset geometric similarity ratio.

[0034] To simulate the formation process and heterogeneous characteristics of tunnel filling under laboratory conditions, scaled-down specimens need to be fabricated. The mold length used to fabricate the laboratory standard specimens needs to be determined. The sample diameter was 707 mm, the number of sample numbers was 10, and the calculated geometric similarity ratio was 70.7:1. The method used was as follows: Figure 2 The mold body 10 shown has three parallel casting grooves, each with a cross-section designed as a square of 70.7mm × 70.7mm. A single casting can simultaneously obtain three sets of parallel sample groups with identical mix proportions and casting conditions. After demolding and curing, each set of samples can be divided along the mold length to obtain ten standard cubic sample 9s with dimensions of 70.7mm × 70.7mm × 70.7mm, numbered sequentially from 1# to 10#. Sample 1# corresponds to the high end of the mold (simulating the upper end of the tunnel), and sample 10# corresponds to the low end of the mold (simulating the lower end of the tunnel).

[0035] S3. Controlling the gangue particle size to remain constant, investigate the effect of the mold tilt angle on heterogeneous characteristic parameters.

[0036] Maintain consistency between laboratory and on-site proportions (sand-cement ratio 7:3, water-cement ratio 0.5), and ensure the average particle size of the gangue aggregate is consistent. Set the pouring angle of the molds to 18mm. For four different inclination angles (35°, 45°, 55°, and 65°), cemented gangue backfill samples were cast, demolded, and cured using standard methods at each angle. For each set of 10 samples obtained at each inclination angle, uniaxial compressive strength tests were performed on each sample. This strength is one of the key mechanical parameters characterizing the heterogeneous properties of the backfill. The test results are detailed in Table 1.

[0037] Table 1 Different Inclination Angles Uniaxial compressive strength of cemented heterogeneous backfill material under certain conditions

[0038]

[0039] To establish the relationship between heterogeneous property parameters and mold tilt angle The quantitative relationship was analyzed based on the data in Table 1. For specimens with the same number (e.g., all #1 specimens), the uniaxial compressive strength value varied with the mold inclination angle. Changes. Through mathematical regression analysis, the strength value and tilt angle of the specimen at each numbered location were analyzed. The fitting process yielded a total of 10 fitting equations, which describe the uniaxial compressive strength at positions 1# to 10#. With tilt angle Evolutionary relationships, specific equations, and goodness of fit The values ​​are shown in Table 2. The corresponding trend curves can be found in the appendix to the instruction manual. Figure 3 .

[0040] Table 2 Uniaxial compressive strength With tilt angle Evolutionary relationship fitting equation

[0041]

[0042] S4. By keeping the mold tilt angle constant, the influence of gangue particle size on heterogeneous characteristic parameters is studied.

[0043] This embodiment mainly demonstrates the influence of the tilt angle. This step shares the same set of data and fitting relationships as step S3 in this embodiment, but focuses on different factors. To fully demonstrate the method, the logic of this step is briefly described as follows: Under the same material ratio (sand-cement ratio 7:3, water-cement ratio 0.5) and a fixed mold tilt angle... Multiple groups of gangue particle sizes were prepared under conditions such as (e.g., 40°). Different samples were tested and their uniaxial compressive strength was obtained. Then, the relationship between strength and gangue particle size was established through fitting. The relationship is shown in detail in Example 2. The detailed data and results of this operation are presented in detail.

[0044] S5. Substitute the actual engineering parameters into the relational formula to determine the heterogeneous characteristic parameters of the roadway filling body.

[0045] The actual dip angle parameters of the roadway to be filled Substituting 40° into the relational formula obtained in step S3 (i.e., the 10 fitting equations in Table 2), calculations are performed to predict the uniaxial compressive strength of the filling material corresponding to different sections of the roadway. The calculation results are shown in Table 3. The table also lists the actual roadway length segments corresponding to the predicted values ​​of each numbered sample. (Converted according to geometric similarity ratio).

[0046] Table 3 Inclination Angle Uniaxial compressive strength of cemented heterogeneous backfill material at 40°

[0047]

[0048] To obtain the law of continuous distribution of the strength of the filling material along the entire roadway length, the predicted strength values ​​in Table 3 are used. The corresponding tunnel segment location (By taking the midpoint values ​​of the segments and correlating them) further comprehensive analysis was conducted. Through data fitting, the uniaxial compressive strength of the actual roadway filling body was obtained. Along the inclined length Continuous functional relationship of distribution: ( The unit is m. The unit is MPa), and its fitting curve can be found in the appendix of the instruction manual. Figure 4 This function can be used to determine the location of the tunnel filling material at any position. Uniaxial compressive strength at the location.

[0049] By repeating the experimental and calculation procedures in S3 and S5 above, but replacing the test parameters with other heterogeneous property parameters such as density, elastic modulus, cohesion, and internal friction angle, the distribution pattern of these parameters along the roadway length can be obtained simultaneously, thereby comprehensively quantifying the heterogeneous characteristics of the filling material. The heterogeneity of the filling material predicted by this method can provide accurate parameters for roadway support design.

[0050] Example 2

[0051] A certain mine has a designed annual production capacity of 3 million tons. The main coal seam is No. 2 coal seam, with a burial depth of approximately 400 m, an average thickness of 3 m, and an average dip angle of 40°, classifying it as a typical steeply dipped coal seam. The working face employs longwall, roadway-by-road cemented backfilling mining. The backfilling length of a single roadway is... The tunnel is 50 m long with a cross-sectional dimension of 4 m × 3 m. Cement and fly ash are used as the cementing material, and coal gangue with an average particle size of 18 mm is used as aggregate, with a sand-to-ash ratio of 7:3 and a water-to-ash ratio of 0.5. To study the influence of different gangue particle sizes on the heterogeneous characteristics of the backfill under steep inclination angles, and thus scientifically guide the design of the backfill and the control of surrounding rock stability, it is necessary to accurately test and predict the characteristics of the heterogeneous backfill formed under different gangue particle size backfill schemes, in order to quantify the spatial distribution characteristics of its mechanical parameters. The geological and mining conditions of this mine are the same as in Example 1, aiming to specifically study the influence of different gangue particle sizes on the heterogeneous characteristics of the backfill under a fixed tunnel inclination angle.

[0052] S1. Collect actual engineering geological parameters of the steeply inclined tunnel to be filled.

[0053] Collect the tunnel inclination angle The angle is 40°, and the tunnel length is... The length is 50m, and the cross-sectional dimensions are 4m × 3m. The composition and proportion of the on-site filling material are as follows: cement and fly ash are used as binders, and the aggregate has an average particle size of [missing information]. The coal gangue is 18 mm thick, with a sand-to-ash ratio of 7:3 and a water-to-ash ratio of 0.5.

[0054] S2. Determine the size of the laboratory mold based on actual engineering geological parameters and a preset geometric similarity ratio.

[0055] Based on the geological conditions of steeply inclined tunnels, the appropriate laboratory mold length for preparing standard samples of heterogeneous gangue cementing materials was determined. The diameter is 707 mm. The mold has three casting grooves, each with a cross-section of 70.7 mm × 70.7 mm square. Three sets of parallel specimens with the same mix proportions and inclination angles can be produced at once. Each set yields ten standard cubic specimens of heterogeneous gangue cementitious material, each measuring 70.7 mm × 70.7 mm × 70.7 mm. The calculated geometric similarity ratio is 70.7:1. Figure 2 As shown.

[0056] S3. Controlling the gangue particle size to remain constant, investigate the effect of the mold tilt angle on heterogeneous characteristic parameters.

[0057] (This embodiment mainly demonstrates the influence of particle size; this step is a fixed condition in this embodiment. Set the mold tilt angle.) (The angle was fixed at 40° for subsequent experiments.)

[0058] S4. By keeping the mold tilt angle constant, the influence of gangue particle size on heterogeneous characteristic parameters is studied.

[0059] Based on the composition and proportion of the on-site backfill material, the composition and proportion of the laboratory backfill material were determined as follows: cement and fly ash as binders, sand-to-ash ratio 7:3, water-to-ash ratio 0.5. The average particle size of the aggregate was obtained through sieve analysis. Coal gangue with particle sizes of 2.5 mm, 5 mm, 10 mm, and 20 mm, respectively. The average particle size of the coal gangue used to prepare the aggregate was determined. Gangue binder materials with diameters of 2.5 mm, 5 mm, 10 mm, and 20 mm were used, and the mold tilt angle was... The casting, demolding, curing, and preparation of standard specimens were carried out under 40° conditions. The heterogeneity characteristics of the specimens were tested. Taking the uniaxial compressive strength as an example, the heterogeneity characteristics parameters of the gangue cementing material are shown in Table 4 below.

[0060] Table 4. Different Gangue Particle Sizes Uniaxial compressive strength of cemented heterogeneous backfill material under certain conditions

[0061]

[0062] To establish the heterogeneous characteristic parameters and gangue particle size The quantitative relationship was analyzed based on the data in Table 4. For samples with the same number, the uniaxial compressive strength value increased with the particle size of the gangue. Changes. Through mathematical regression analysis, the strength value and particle size of the sample at each numbered location were analyzed. By fitting the data, 10 values ​​describing uniaxial compressive strength were obtained. Depending on the particle size of the gangue The equations illustrating the evolutionary relationships are shown in Table 5. The corresponding trend curves can be found in the appendix to the instruction manual. Figure 5 .

[0063] Table 5 Uniaxial compressive strength Depending on the particle size of the gangue Evolutionary relationship fitting equation

[0064]

[0065] S5. Substitute the actual engineering parameters into the relational formula to determine the heterogeneous characteristic parameters of the roadway filling body.

[0066] The planned particle size of the gangue to be used on site Substituting 18mm into the relational formula obtained in step S4 (i.e., the 10 fitting equations in Table 5), the predicted uniaxial compressive strength of the filling material corresponding to different segments of the roadway is obtained through calculation. The calculation results are shown in Table 6.

[0067] Table 6. Gangue Particle Size Uniaxial compressive strength of 18 mm gangue cemented heterogeneous infill material

[0068]

[0069] Further fitting analysis yielded the uniaxial compressive strength of the filling body for steeply inclined roadways in actual engineering sites. Along the inclined direction with length The curve showing the changing pattern and the corresponding fitting equation are as follows: Figure 6 As shown in the figure, the length of the steeply inclined tunnel to be filled in the actual engineering site can be determined based on the fitted equation in the figure. For any location of the 50 m filling body Uniaxial compressive strength parameters at the location .

[0070] By repeating steps S4 and S5, the actual length of the steeply inclined tunnel to be filled at the engineering site can be obtained. For any location of the 50 m filling body Other heterogeneous property parameters, such as density, elastic modulus, cohesion, and internal friction angle, are also considered.

[0071] The above are merely preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A method for determining the heterogeneous characteristic parameters of gangue cemented backfill in steeply inclined roadways, characterized in that, Includes the following steps: S1. Collect the actual engineering geological parameters of the steeply inclined roadway to be filled, including at least the roadway inclination angle. Length of tunnel And the composition and proportion of filling materials used for on-site tunnel filling; S2. Based on the actual engineering geological parameters and the preset geometric similarity ratio Determine the mold length used to prepare laboratory standard test specimens. ; S3, Controlling gangue particle size Keeping the angle constant, prepare multiple sets of mold tilt angles Different standard samples of gangue cemented backfill were tested, and the heterogeneous characteristic parameters of each group of samples were obtained. Through data fitting, a relationship between the heterogeneous characteristic parameters and the mold inclination angle was established. Relationship; S4, Control mold tilt angle With the same parameters, multiple groups of gangue particle sizes were prepared. Different standard samples of gangue cemented backfill were tested, and the heterogeneous characteristic parameters of each group of samples were obtained. Through data fitting, a relationship between the heterogeneous characteristic parameters and gangue particle size was established. Relationship; S5. The tunnel dip angle in the actual engineering geological parameters... and gangue particle size Substitute the values ​​into the relationships obtained in steps S3 and S4 respectively to perform calculations and determine the different positions of the steeply inclined roadway along its length. The heterogeneous characteristics of the gangue cemented backfill at the location; In step S2, the cross-section of the mold is square, and the geometric similarity ratio is... It is obtained through the following formula: ； In the formula, The length of the tunnel; The number of samples numbered along the length of the mold; The length of a single sample.

2. The method for determining the heterogeneous characteristic parameters of gangue cemented backfill in steeply inclined tunnels according to claim 1, characterized in that, In steps S3 and S4, the heterogeneous characteristic parameters include at least one of uniaxial compressive strength, density, elastic modulus, cohesion, and internal friction angle.

3. The method for determining the heterogeneous characteristic parameters of a cemented gangue filling body in a steeply inclined tunnel according to claim 1 or 2, characterized in that, Step S3 specifically includes: maintaining the particle size of the gangue. Unchanged, at multiple different mold tilt angles The molds were cast, cured, and prepared into multiple sets of standard specimens. Specimens within the same set were numbered and tested along the length of the mold to obtain the heterogeneous characteristic parameters of each numbered location. The results were then analyzed for different mold inclination angles. By fitting the parameter values ​​of samples with the same number, the heterogeneous characteristic parameters at each number position and the mold tilt angle are obtained. The relational expression.

4. The method for determining the heterogeneous characteristic parameters of gangue cemented backfill in steeply inclined tunnels according to claim 1 or 2, characterized in that, Step S4 specifically includes: maintaining the mold tilt angle The same applies, but various different gangue particle sizes are used. The aggregates were cast, cured, and prepared into multiple sets of standard samples. Samples within the same set were numbered and tested along the length of the mold to obtain the heterogeneous characteristic parameters of samples at each numbered location. Different gangue particle sizes were also tested. By fitting the parameter values ​​of samples with the same number, the heterogeneous characteristic parameters and gangue particle size at each number position were obtained. The relational expression.

5. The method for determining the heterogeneous characteristic parameters of cemented gangue backfill in steeply inclined tunnels according to claim 1, characterized in that, In step S1, the inclination angle of the steep-angle roadway The range is 35°≤ ≤70°.

6. The method for determining the heterogeneous characteristic parameters of cemented gangue backfill in steeply inclined tunnels according to claim 1, characterized in that, In steps S3 and S4, the particle size of the gangue... maximum value No more than 20 mm.

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