A method for preventing and controlling rock burst based on fly ash-based polymer filling

Abstract

The application discloses a kind of prevention and treatment of rock burst method based on fly ash based polymer filling, first, adjacent goaf is divided into multiple filling areas, and the adjacent goaf overburden structure and gangue filling rate of each filling area are obtained;According to the monitoring data obtained, the filling type of each filling area is identified;According to the filling type of each filling area, the fly ash based polymer material ratio and grouting hole layout mode are formulated correspondingly, and the filling process of fly ash based polymer in each filling area is completed;Finally, the filling effect of each filling area is tested, if the test result is good, the filling prevention and treatment of rock burst process of this filling area is completed, if the test result is not good, continue to fill the filling area, until the test result is good, complete the filling process of entire adjacent goaf.The application not only can reuse fly ash, reduce its influence on environment, but also can have good effect on prevention and treatment of rock burst of coal mine.

Description

Technical Field

[0001] This invention relates to a method for preventing rockbursts, specifically a method for preventing rockbursts based on fly ash-based polymer fillers, belonging to the field of mine rockburst prevention technology. Background Technology

[0002] Due to the influence of the coal seam dip angle, the roof overburden fracture pattern and the goaf gangue accumulation state in steeply inclined longwall faces differ significantly from those in conventional longwall faces. Especially after steeply inclined longwall faces are mined, the thick, hard roof blocks fractured in the goaf move downwards under their own weight and gradually accumulate in the lower part of the goaf, resulting in an interwoven, unstable state of gangue blocks in the lower goaf. When mining begins in the lower part of the goaf, it leads to further roof movement. At this time, the already unstable gangue blocks in the adjacent goaf are further fractured due to mining activity, and the resulting dynamic load disturbance can easily affect the safe mining of this longwall face. The existing method of deep-hole blasting pre-splitting of the roof is used to blast the overlying rock structure above the adjacent goaf of the working face. The purpose of blasting to relieve pressure is to break the rock strata so that the degree of dynamic load disturbance generated when the rock strata move again is reduced compared with that before blasting. Although the dynamic load disturbance is reduced, when the working face is mined to the stress concentration area, even a small dynamic load disturbance can still cause roadway rockburst accidents. This is because this blasting pre-splitting method does not control the source of dynamic load disturbance.

[0003] Furthermore, with the increasing scale of coal mining enterprises and the gradual expansion of integrated coal-power systems, the output of waste materials such as slag and fly ash generated during power generation is increasing daily. These wastes not only waste resources but also cause environmental damage. Therefore, providing a method to organically combine coal mine rockburst prevention with the management of solid waste generated by coal-fired power plants—one that not only allows for the reuse of fly ash and reduces its environmental impact but also effectively prevents coal mine rockbursts—is one of the research directions in this industry. Summary of the Invention

[0004] To address the problems existing in the prior art, this invention provides a method for preventing rockbursts based on fly ash-based polymer fillers. This method combines rockburst prevention in coal mines with solid waste generated by coal-fired power plants, which not only enables the reuse of fly ash and reduces its environmental impact, but also has a good effect on preventing rockbursts in coal mines.

[0005] To achieve the above objectives, the technical solution adopted by this invention is: a method for preventing rockbursts based on fly ash-based polymer filling, the specific steps of which are as follows:

[0006] S1. In the adjacent goaf roadway, multiple filling areas are divided along the mining direction of the steeply inclined mining face. Multiple sets of boreholes are arranged in each filling area. Each set of boreholes consists of boreholes for detecting the overburden structure of the adjacent goaf and boreholes for detecting the gangue filling rate of the goaf. A borehole sighting instrument is used to extend into each borehole and obtain the parameters of each borehole, thereby obtaining the overburden structure and gangue filling rate of the adjacent goaf in each filling area.

[0007] S2. Pre-classify the filling types of adjacent goaf areas into Class I and Class II. Then, based on the overburden structure and gangue filling rate of the adjacent goaf areas in each filling area in step S1, determine the filling type of each filling area of ​​the current steep-angle longwall face.

[0008] S3. Determine the filling type of each filling area according to step S2, and formulate the corresponding fly ash-based polymer material ratio.

[0009] S4. Based on step S2, determine the filling type of each filling area, formulate the grouting hole layout method for filling the fly ash-based polymer in the adjacent goaf of the steep angle longwall face, and combine the fly ash-based polymer material ratio formulated in step S3 to complete the filling process of fly ash-based polymer in each filling area.

[0010] S5. Drill multiple filling effect inspection boreholes in each filling area, then use a borehole inspection instrument to insert into each filling effect inspection borehole and obtain the parameters of each borehole. Finally, inspect the filling effect of each filling area according to the obtained parameters, and classify the filling effect as good, average, and poor. If the inspection result of a filling area is good, the filling process for preventing rockburst in that filling area is completed. If the inspection result of a filling area is average or poor, continue to repeat the filling process of step S4 for that filling area until the inspection result of that filling area is good. When the inspection results of each filling area are all good, the filling process for preventing rockburst in the entire adjacent goaf is completed.

[0011] Furthermore, step S1 specifically includes:

[0012] S1.1. In the adjacent goaf roadway, a filling area is divided every 2X meters along the mining direction of the steeply inclined mining face, where X is the step distance of the roof of the mining face; in each filling area, a detection point is selected every 2X / 10 meters, and each detection point is equipped with adjacent goaf overburden structure detection boreholes and goaf gangue filling rate detection boreholes.

[0013] S1.2 The drilling depth of the detection borehole for the overburden structure of the adjacent goaf is H1, the drilling angle is α with the horizontal plane, and the borehole is arranged from the wall of the adjacent goaf roadway toward the adjacent goaf.

[0014] S1.3 The drilling depth of the adjacent goaf gangue filling rate detection borehole is H2, and the drilling angle is β with the horizontal plane; the borehole is arranged from the wall of the adjacent goaf roadway toward the adjacent goaf.

[0015] S1.4. Use formulas (1) and (2) to determine the depths H1 and H2 of the detection borehole, and use formulas (3) and (4) to determine the angles α and β of the detection borehole.

[0016] H1=(4~6)×h (1)

[0017] H2=(1~3)×L+H (2)

[0018] α=θ1+(5°~10°) (3)

[0019] β=θ2+(2°~5°) (4)

[0020] In the formula, h represents the coal seam thickness; L represents the length of the overhanging roof in the goaf; θ1 represents the rock strata fracture angle; and θ2 represents the coal seam dip angle.

[0021] S1.5. Use a borehole inspection instrument to record the cumulative width L1 of the circumferential fractures and the cumulative length L2 of the radial fractures in the boreholes of the overburden structure detection holes in each adjacent goaf area within each filling region.

[0022] S1.6. Use a borehole inspection instrument to record the non-collapsed borehole range L3 of the detection boreholes for the filling rate of each adjacent goaf in each filling area.

[0023] Furthermore, in step S2, identifying the filling type of each filling area in the current steep-angle longwall face specifically involves:

[0024] S2.1 Based on the monitoring data of each detection hole in each filling area in step S1, calculate the average value of the cumulative width L1 of the circumferential crack, the cumulative length L2 of the radial crack, and the range L3 of the non-collapsed hole in each detection hole in each filling area.

[0025] S2.2 and step S2.1 data are substituted into formula (5) to identify the filling type of each filling area in the current steep-angle longwall face:

[0026]

[0027] When K ≤ 50%, the filling type of the filled area is determined to be Class I;

[0028] When K > 50%, the filling type of the filled area is determined to be Class II.

[0029] Furthermore, the specific process for determining the proportion of fly ash-based polymer materials in step S3 is as follows:

[0030] S3.1 First, use formula (6) to determine the total weight M of fly ash-based polymer material per unit volume:

[0031] M=λ×M1 (6)

[0032] In the formula, λ represents the weight coefficient, which is 1 / 2 when the filling area is Class I and 2 / 3 when the filling area is Class II. M1 represents the average weight of the coal seam roof per unit volume.

[0033] S3.2 When the filling area is Class I, the fly ash-based polymer material proportioning scheme A is: 75% industrial sand by total polymer weight, 17.5% cement, 6% fly ash, 1.05% slag, 0.22% gypsum, 0.22% sodium sulfate, and 0.01% sodium citrate.

[0034] S3.3 When the filling area is Class II, the fly ash-based polymer material proportioning scheme B is: 75% industrial sand, 6% cement, 14% fly ash, 2.4% slag, 0.85% gypsum, 0.85% sodium sulfate, 0.85% sodium chloride, and 0.05% sodium citrate by total polymer weight.

[0035] S3.4. After mixing the fly ash-based polymer (which does not contain 75% industrial sand) according to Scheme A or Scheme B, grind it in a grinding mill until the polymer particle diameter meets the requirements, thus completing the material mixing process.

[0036] Furthermore, in step S3.4, the fly ash-based polymer that does not contain 75% industrial sand is placed in a grinding mill and ground for 1 minute at 900 r / min. The required standard for polymer particle diameter is that more than 90% of the polymer particles have a diameter of <40 μm.

[0037] Furthermore, the specific process of step S4 is as follows:

[0038] S4.1 When the filling area is Class I, the fly ash-based polymer prepared by Scheme A and 13.5% of the total weight of distilled water are put into a mixer for mixing; a set of grouting holes are arranged every 5m in the filling area, with a drilling depth of 1 / 2L and a drilling angle of α with the horizontal plane. The holes are arranged from the wall of the adjacent goaf roadway toward the adjacent goaf area.

[0039] S4.2 When the filling area is Class II, the fly ash-based polymer prepared by Scheme B and 13.5% of the total weight of distilled water are put into a mixer for mixing; a set of grouting holes are arranged every 8m in the filling area, with a drilling depth of 2 / 3L and a drilling angle of α with the horizontal plane. The holes are arranged from the wall of the adjacent goaf roadway toward the adjacent goaf area.

[0040] Furthermore, the specific process of drilling layout and filling effect inspection in step S5 is as follows:

[0041] S5.1. Select a detection point every 2X / 20 meters in each filling area, and arrange a borehole at each detection point for testing the filling effect of adjacent goaf areas;

[0042] S5.2 The drilling depth of the filling effect test borehole is 1 / 2H2, the drilling angle is β with the horizontal plane, and the borehole is arranged from the wall of the adjacent goaf roadway toward the adjacent goaf area.

[0043] S5.3. Use a borehole inspection instrument to record the cumulative width of the circumferential crack S1, the cumulative length of the radial crack S2, and the area of ​​the hole that has not collapsed S3 for each borehole.

[0044] S5.4 Based on the monitoring data of the boreholes for filling effect inspection in each filling area, calculate the average values ​​of the cumulative circumferential fracture width S1, the cumulative radial fracture length S2, and the non-collapsed borehole range S3 of each filling effect inspection borehole in each filling area.

[0045] S5.5. Use formula (7) to determine the filling effect of each filling area:

[0046]

[0047] When T≤20%, the area to be filled is determined to have a good filling effect;

[0048] When 20% < T ≤ 40%, the filled area is determined to have a mediocre filling effect;

[0049] When T > 40%, the filled area is determined to have poor filling effect;

[0050] S5.6 When the filling effect of a certain filling area is judged to be poor, repeat the filling process of step S4 for that filling area. When refilling, the filling material ratio and the grouting hole layout are the same as when filling for the first time. The total weight of the coal ash-based polymer material is 2 / 3 of the total weight M of the first filling material.

[0051] S5.7 When the filling effect of a certain filling area is judged to be average, repeat the filling process of step S4 for that filling area. When refilling, the filling material ratio and the grouting hole layout are the same as when filling for the first time. The total weight of the coal ash-based polymer material is 1 / 2 of the total weight M of the first filling material.

[0052] S5.8 When the filling effect of a certain filling area is judged to be good, the filling process for preventing rockburst in that filling area is completed.

[0053] Furthermore, the borehole diameters of the adjacent goaf overburden structure detection borehole, the goaf gangue filling rate detection borehole, and the filling effect inspection borehole are all 63mm; the borehole diameter of the grouting hole is not less than 50mm.

[0054] Compared with existing technologies, this invention first divides adjacent goaf areas into multiple filling zones and obtains the overburden structure and gangue filling rate of each filling zone. Based on the obtained monitoring data, the filling type of each filling zone is identified. According to the filling type of each filling zone, the proportion of fly ash-based polymer materials and the layout of grouting holes are formulated accordingly, and the filling process of fly ash-based polymer in each filling zone is completed. Finally, the filling effect of each filling zone is inspected. If the inspection result is good, the filling process for preventing rockburst in that filling zone is completed. If the inspection result is not good, the filling process for that filling zone continues until the inspection result is good, thus finally completing the filling process for preventing rockburst in the entire adjacent goaf area. This invention combines the prevention of rockburst in coal mines with the solid waste generated by coal-fired power plants, which not only enables the reuse of fly ash and reduces its impact on the environment, but also has a good effect on the prevention of rockburst in coal mines. Attached Figure Description

[0055] Figure 1 This is an overall flowchart of the present invention;

[0056] Figure 2 This is a schematic diagram of the borehole layout for detecting the overburden structure and gangue filling rate of adjacent goaf areas in this invention.

[0057] Figure 3 This is a schematic cross-sectional view of the grouting hole arrangement in the adjacent tunnel in this invention;

[0058] Figure 4 This is a schematic diagram showing the characteristics and width of circumferential fractures in the detection holes of the overlying rock structure in adjacent goaf areas in this invention;

[0059] Figure 5 This is a schematic diagram showing the radial fracture characteristics and length of the detection holes for the overlying rock structure in adjacent goaf areas in this invention;

[0060] Figure 6 This is a schematic diagram showing the non-collapsed hole characteristics and length of the detection hole for the fill rate of adjacent goaf areas in this invention;

[0061] Figure 7 This is a top view schematic diagram of the grouting hole arrangement in the adjacent tunnel in this invention;

[0062] Figure 8 This is a microseismic data analysis diagram of the filled and unfilled areas of the adjacent goaf in a mine's steeply inclined longwall face, as shown in the example. Detailed Implementation

[0063] The present invention will be further described below.

[0064] like Figure 1 As shown, a method for preventing rockbursts based on fly ash-based polymer fillers includes the following steps:

[0065] S1, such as Figure 2 As shown, multiple filling zones are divided along the mining direction of the steeply inclined mining face in the adjacent goaf roadway. Multiple sets of boreholes are arranged within each filling zone. Each set of boreholes consists of boreholes for detecting the overburden structure of adjacent goaf areas and boreholes for detecting the gangue filling rate of goaf areas. A borehole sight is inserted into each borehole to obtain the parameters of each borehole, thereby obtaining the overburden structure and gangue filling rate of adjacent goaf areas in each filling zone. Specifically:

[0066] S1.1. In the adjacent goaf roadway, a filling area is divided every 2X meters along the mining direction of the steeply inclined mining face, where X is the step distance of the roof of the mining face; in each filling area, a detection point is selected every 2X / 10 meters, and each detection point is equipped with adjacent goaf overburden structure detection boreholes and goaf gangue filling rate detection boreholes.

[0067] S1.2 The borehole diameter of the detection borehole for the overburden structure of the adjacent goaf is 63mm, the borehole depth is H1, the borehole angle is α with the horizontal plane, and the borehole is arranged from the wall of the adjacent goaf roadway toward the adjacent goaf.

[0068] S1.3 The borehole diameter for detecting the fill rate of gangue in the adjacent goaf is 63mm, the borehole depth is H2, and the borehole angle is β with respect to the horizontal plane; the borehole is arranged from the wall of the adjacent goaf roadway toward the adjacent goaf.

[0069] S1.4. Use formulas (1) and (2) to determine the depths H1 and H2 of the detection borehole, and use formulas (3) and (4) to determine the angles α and β of the detection borehole.

[0070] H1=(4~6)×h (1)

[0071] H2=(1~3)×L+H (2)

[0072] α=θ1+(5°~10°) (3)

[0073] β=θ2+(2°~5°) (4)

[0074] In the formula, h represents the coal seam thickness; L represents the length of the overhanging roof in the goaf; θ1 represents the rock strata fracture angle; and θ2 represents the coal seam dip angle.

[0075] S1.5, such as Figure 4 and 5As shown, a borehole inspection instrument was used to record the cumulative width L1 of the circumferential fractures and the cumulative length L2 of the radial fractures in the boreholes of the overburden structure detection holes of each adjacent goaf area within each filling region.

[0076] S1.6, such as Figure 6 As shown, a borehole inspection instrument was used to record the non-collapsed borehole range L3 of the detection boreholes for the filling rate of each adjacent goaf within each filling area.

[0077] S2. Pre-classify the filling types of adjacent goaf areas into Class I and Class II. Then, based on the overburden structure and gangue filling rate of the adjacent goaf areas in step S1, determine the filling type of each filling area in the current steep-angle longwall face. Specifically:

[0078] S2.1 Based on the monitoring data of each detection hole in each filling area in step S1, the average value of the cumulative width of the circumferential crack L1, the cumulative length of the radial crack L2, and the range of the uncollapsed hole L3 of each detection hole in each filling area is obtained as the monitoring data of each filling area.

[0079] S2.2 and step S2.1 data are substituted into formula (5) to identify the filling type of each filling area in the current steep-angle longwall face:

[0080]

[0081] When K ≤ 50%, the filling type of the filled area is determined to be Class I;

[0082] When K > 50%, the filling type of the filled area is determined to be Class II.

[0083] S3. Based on step S2, determine the filling type of each filling area and formulate the corresponding fly ash-based polymer material ratio. The specific process is as follows:

[0084] S3.1 First, use formula (6) to determine the total weight M of fly ash-based polymer material per unit volume:

[0085] M=λ×M1 (6)

[0086] In the formula, λ represents the weight coefficient, which is 1 / 2 when the filling area is Class I and 2 / 3 when the filling area is Class II. M1 represents the average weight of the coal seam roof per unit volume.

[0087] S3.2 When the filling area is Class I, the fly ash-based polymer material proportioning scheme A is: 75% industrial sand by total polymer weight, 17.5% cement, 6% fly ash, 1.05% slag, 0.22% gypsum, 0.22% sodium sulfate, and 0.01% sodium citrate.

[0088] S3.3 When the filling area is Class II, the fly ash-based polymer material proportioning scheme B is: 75% industrial sand, 6% cement, 14% fly ash, 2.4% slag, 0.85% gypsum, 0.85% sodium sulfate, 0.85% sodium chloride, and 0.05% sodium citrate by total polymer weight.

[0089] S3.4. After the proportioning of Scheme A or Scheme B, the fly ash-based polymer that does not contain 75% industrial sand is put into a grinder and ground for 1 minute at 900 r / min, so that more than 90% of the polymer particles have a diameter of <40μm, and the material proportioning work is completed.

[0090] S4. Determine the fill type of each fill area according to step S2, such as... Figure 3 and 7 As shown, the grouting hole layout for filling fly ash-based polymer in adjacent goaf areas of steeply inclined longwall faces is determined accordingly. Combined with the fly ash-based polymer material ratio determined in step S3, the filling process of fly ash-based polymer in each filling area is completed. The specific process is as follows:

[0091] S4.1 When the filling area is Class I, the fly ash-based polymer prepared by Scheme A and 13.5% of the total polymer weight of distilled water are put into a mixer and stirred for 5 minutes at 100 r / min. In the filling area, a set of grouting holes is arranged every 8m along the direction of the adjacent goaf roadway. The diameter of the hole is not less than 50mm, the depth of the hole is 1 / 2L, the angle of the hole is α with the horizontal plane, and the holes are arranged from the wall of the adjacent goaf roadway toward the adjacent goaf area. After the arrangement is completed, the adjacent goaf area is filled by grouting through the grouting holes.

[0092] S4.2 When the filling area is Class II, the fly ash-based polymer prepared by Scheme B and 13.5% of the total polymer weight of distilled water are put into a mixer and stirred for 5 minutes at 100 r / min. A set of grouting holes is arranged every 5 m along the adjacent goaf roadway in the filling area. The hole diameter is not less than 50 mm, the hole depth is 2 / 3L, the hole angle is α with the horizontal plane, and the holes are arranged from the wall of the adjacent goaf roadway toward the adjacent goaf area. After the arrangement is completed, the adjacent goaf area is filled by grouting through the grouting holes.

[0093] S5. Drill multiple filling effect inspection boreholes in each filling area, then use a borehole inspection instrument to insert into each borehole and obtain the parameters of each borehole. Finally, inspect the filling effect of each filling area based on the obtained parameters, and classify the filling effect as good, average, or poor. If the inspection result of a filling area is good, the filling process for preventing rockburst in that filling area is completed. If the inspection result of a filling area is average or poor, continue to repeat the filling process of step S4 for that filling area until the inspection result of that filling area is good. When the inspection results of all filling areas are good, the filling process for preventing rockburst in the entire adjacent goaf is completed. The specific process is as follows:

[0094] S5.1. Select a detection point every 2X / 20 meters in each filling area, and arrange a borehole at each detection point for testing the filling effect of adjacent goaf areas;

[0095] S5.2 The diameter of the borehole for the filling effect test is 63mm, the depth is 1 / 2H2, the borehole angle is β with the horizontal plane, and the borehole is arranged from the wall of the adjacent goaf towards the adjacent goaf area.

[0096] S5.3. Use a borehole inspection instrument to record the cumulative width of the circumferential crack S1, the cumulative length of the radial crack S2, and the area of ​​the hole that has not collapsed S3 for each borehole.

[0097] S5.4 Based on the monitoring data of the boreholes for filling effect inspection in each filling area, calculate the average value of the cumulative width of the circumferential fracture S1, the cumulative length of the radial fracture S2, and the non-collapsed range S3 of each borehole for filling effect inspection in each filling area, and use it as the monitoring data for each filling area.

[0098] S5.5. Use formula (7) to determine the filling effect of each filling area:

[0099]

[0100] When T≤20%, the area to be filled is determined to have a good filling effect;

[0101] When 20% < T ≤ 40%, the filled area is determined to have a mediocre filling effect;

[0102] When T > 40%, the filled area is determined to have poor filling effect;

[0103] S5.6 When the filling effect of a certain filling area is judged to be poor, repeat the filling process of step S4 for that filling area. When refilling, the filling material ratio and the grouting hole layout are the same as when filling for the first time. The total weight of the coal ash-based polymer material is 2 / 3 of the total weight M of the first filling material.

[0104] S5.7 When the filling effect of a certain filling area is judged to be average, repeat the filling process of step S4 for that filling area. When refilling, the filling material ratio and the grouting hole layout are the same as when filling for the first time. The total weight of the coal ash-based polymer material is 1 / 2 of the total weight M of the first filling material.

[0105] S5.8 When the filling effect of a certain filling area is judged to be good, the filling process for preventing rockburst in that filling area is completed.

[0106] Experiments have shown that:

[0107] To further verify the effectiveness of the present invention, this embodiment selects a steeply inclined longwall face in a mine and analyzes the effect of the method of the present invention by mining the area filled with fly ash-based polymer and the unfilled area.

[0108] like Figure 8 As shown, microseismic monitoring data indicates that the daily microseismic energy release in the filled area is reduced by 40.5% compared to the unfilled area in the steep-angle longwall face; the daily microseismic frequency is reduced by 15.7%. The microseismic monitoring data demonstrates that fly ash-based polymer filling has a significant effect on preventing rockbursts and effectively reduces the rockburst risk in steep-angle longwall faces.

[0109] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preventing rockbursts based on fly ash-based polymer fillers, characterized in that, The specific steps are as follows: S1. Multiple filling zones are defined along the mining direction of the steeply inclined mining face in the adjacent goaf roadway. Multiple sets of boreholes are laid out within each filling zone. Each set of boreholes consists of boreholes for detecting the overburden structure of adjacent goaf areas and boreholes for detecting the fill rate of gangue in goaf areas. A borehole sight is inserted into each borehole to obtain its parameters, thereby obtaining the overburden structure and gangue fill rate of the adjacent goaf areas in each filling zone. Specifically: S1.

1. In the adjacent goaf roadway, a filling area is divided every 2X meters along the mining direction of the steeply inclined mining face, where X is the step distance of the roof of the mining face; in each filling area, a detection point is selected every 2X / 10 meters, and each detection point is equipped with adjacent goaf overburden structure detection boreholes and goaf gangue filling rate detection boreholes. S1.2 The drilling depth of the detection borehole for the overburden structure of the adjacent goaf is H1, the drilling angle is α with the horizontal plane, and the borehole is arranged from the wall of the adjacent goaf roadway toward the adjacent goaf. S1.3 The drilling depth of the adjacent goaf gangue filling rate detection borehole is H2, and the drilling angle is β with respect to the horizontal plane; the borehole is arranged from the wall of the adjacent goaf roadway toward the adjacent goaf. S1.

4. Use formulas (1) and (2) to determine H1 and H2, and use formulas (3) and (4) to determine α and β. (1) (2) (3) (4) In the formula, h represents the coal seam thickness; L represents the length of the goaf roof; θ1 represents the rock strata fracture angle; and θ2 represents the coal seam dip angle. S1.

5. Use a borehole inspection instrument to record the cumulative width L1 of the circumferential fractures and the cumulative length L2 of the radial fractures in the boreholes used for detecting the overburden structure of each adjacent goaf area within each filling region. S1.

6. Use a borehole inspection instrument to record the non-collapsed borehole range L3 of the detection borehole for the gangue filling rate of each adjacent goaf area in each filling area; S2. Pre-classify the filling types of adjacent goaf areas into Class I and Class II. Then, based on the overburden structure and gangue filling rate of the adjacent goaf areas in step S1, determine the filling type of each filling area in the current steep-angle longwall face. Specifically: S2.1 Based on the monitoring data of each detection borehole in each filling area in step S1, the average values ​​of the cumulative width L1 of the circumferential crack of the borehole wall failure, the cumulative length L2 of the radial crack, and the range L3 of the non-collapsed borehole in each detection borehole in each filling area are obtained. S2.2 and step S2.1 data are substituted into formula (5) to identify the filling type of each filling area in the current steep-angle longwall face: (5) When K ≤ 50%, the filling type of the filled area is determined to be Class I; When K > 50%, the filling type of the filled area is determined to be Class II; S3. Determine the filling type of each filling area according to step S2, and formulate the corresponding fly ash-based polymer material ratio. S4. Based on step S2, determine the filling type of each filling area, formulate the grouting hole layout method for filling fly ash-based polymer in each filling area, and combine the fly ash-based polymer material ratio formulated in step S3 to complete the filling process of fly ash-based polymer in each filling area. S5. Drill multiple filling effect inspection boreholes in each filling area, then use a borehole inspection instrument to insert into each filling effect inspection borehole and obtain the parameters of each borehole. Finally, inspect the filling effect of each filling area according to the obtained parameters, and classify the filling effect as good, average, and poor. If the inspection result of a filling area is good, the filling process for preventing rockburst in that filling area is completed. If the inspection result of a filling area is average or poor, continue to repeat the filling process of step S4 for that filling area until the inspection result of that filling area is good. When the inspection results of each filling area are all good, the filling process for preventing rockburst in the entire adjacent goaf is completed.

2. The method for preventing rockbursts based on fly ash-based polymer fillers according to claim 1, characterized in that, The specific process for determining the fly ash-based polymer material ratio in step S3 is as follows: S3.1 First, use formula (6) to determine the total weight M of fly ash-based polymer material per unit volume: (6) In the formula, λ represents the weight coefficient, which is 1 / 2 when the filling area is Class I and 2 / 3 when the filling area is Class II. M1 represents the average weight of the coal seam roof per unit volume. S3.2 When the filling area is Class I, the fly ash-based polymer material proportioning scheme A is: industrial sand accounting for 75% of the total polymer weight, cement 17.5%, fly ash 6%, slag 1.05%, gypsum 0.22%, sodium sulfate 0.22%, and sodium citrate 0.01%. S3.3 When the filling area is Class II, the fly ash-based polymer material proportioning scheme B is: industrial sand accounting for 75% of the total polymer weight, 6% cement, 14% fly ash, 2.4% slag, 0.85% gypsum, 0.85% sodium sulfate, 0.85% sodium chloride, and 0.05% sodium citrate. S3.

4. After mixing the fly ash-based polymer (which does not contain 75% industrial sand) according to Scheme A or Scheme B, grind it in a grinding mill until the polymer particle diameter meets the requirements, thus completing the material mixing process.

3. The method for preventing rockbursts based on fly ash-based polymer fillers according to claim 2, characterized in that, In step S3.4, the fly ash-based polymer that does not contain 75% industrial sand is placed in a grinding mill and ground for 1 minute at 900 r / min. The required standard for polymer particle diameter is that more than 90% of the polymer particles have a diameter of <40 μm.

4. The method for preventing rockbursts based on fly ash-based polymer fillers according to claim 2, characterized in that, The specific process of step S4 is as follows: S4.1 When the filling area is Class I, the fly ash-based polymer prepared by Scheme A and 13.5% of the total weight of distilled water are put into a mixer for mixing; a set of grouting holes are arranged every 5m in the filling area, with a drilling depth of 1 / 2L and a drilling angle of α with the horizontal plane. The holes are arranged from the wall of the adjacent goaf roadway toward the adjacent goaf area. S4.2 When the filling area is Class II, the fly ash-based polymer prepared by Scheme B and 13.5% of the total weight of distilled water are put into a mixer for mixing; a set of grouting holes are arranged every 8m in the filling area, with a drilling depth of 2 / 3L and a drilling angle of α with the horizontal plane. The holes are arranged from the wall of the adjacent goaf roadway toward the adjacent goaf area.

5. The method for preventing rockbursts based on fly ash-based polymer fillers according to claim 1, characterized in that, The specific process for borehole layout and filling effect inspection in step S5 is as follows: S5.

1. Select a detection point every 2X / 20 meters in each filling area, and arrange a borehole at each detection point for testing the filling effect of adjacent goaf areas; S5.2 The drilling depth of the filling effect test borehole is 1 / 2H2, the drilling angle is β with the horizontal plane, and the borehole is arranged from the wall of the adjacent goaf roadway toward the adjacent goaf area. S5.

3. Use a borehole inspection instrument to record the cumulative width of the circumferential crack S1, the cumulative length of the radial crack S2, and the area of ​​the hole that has not collapsed S3 for each borehole. S5.4 Based on the monitoring data of the boreholes for filling effect inspection in each filling area, calculate the average values ​​of the cumulative circumferential fracture width S1, the cumulative radial fracture length S2, and the non-collapsed borehole range S3 of each filling effect inspection borehole in each filling area. S5.

5. Use formula (7) to determine the filling effect of each filling area: (7) When T≤20%, the area to be filled is determined to have a good filling effect; When 20% < T ≤ 40%, the filled area is determined to have a mediocre filling effect; When T > 40%, the filled area is determined to have poor filling effect; S5.6 When the filling effect of a certain filling area is judged to be poor, repeat the filling process of step S4 for that filling area. When refilling, the filling material ratio and the grouting hole layout are the same as when filling for the first time. The total weight of fly ash-based polymer material is 2 / 3 of the total weight M of the material in the first filling. S5.7 When the filling effect of a certain filling area is judged to be average, repeat the filling process of step S4 for that filling area. When refilling, the filling material ratio and the grouting hole layout are the same as when filling for the first time. The total weight of fly ash-based polymer material is 1 / 2 of the total weight M of the material filled for the first time. S5.8 When the filling effect of a certain filling area is judged to be good, the filling process for preventing rockburst in that filling area is completed.

6. The method for preventing rockbursts based on fly ash-based polymer fillers according to claim 5, characterized in that, The borehole diameters for the adjacent goaf overburden structure detection borehole, the goaf gangue filling rate detection borehole, and the filling effect inspection borehole are all 63mm.

7. The method for preventing rockbursts based on fly ash-based polymer fillers according to claim 4, characterized in that, The diameter of the grouting hole shall not be less than 50 mm.

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