Short-term roof fall early warning method for underground mine based on multi-source monitoring and partition early warning value

Abstract

The application discloses a short-term and impending roof fall early warning method for underground mines based on multi-source monitoring and partition early warning values, and comprises the following steps: S1, multi-source monitoring is conducted on roof fall to obtain multi-source monitoring data; S2, based on existing several stope falling rock mass influencing factors, specific influencing factors are screened, and partition early warning is conducted based on the specific influencing factors, and an early warning value early warning scoring system of rock mass internal fracture and surface deformation is established; and S3, the early warning value early warning scoring system of rock mass internal fracture and surface deformation is utilized to conduct actual partition early warning. The method is based on multi-source monitoring means, and meanwhile, the specific engineering geological condition partition of the monitoring object is considered, different early warning values are set for different partitions, and the short-term and impending early warning accuracy is remarkably improved.

Description

Technical Field

[0001] This invention belongs to the field of mineral resource development safety and engineering geological disaster prevention and control technology, specifically involving a short-term early warning method for underground mine roof collapse based on multi-source monitoring and zonal early warning values. Background Technology

[0002] The roof of underground mines mainly consists of the roofs of roadways, large-section chambers, and larger exposed areas in mining areas, ranging from tens to thousands of square meters. Roof instability and collapse are among the most common types of accidents causing casualties in mines, making their prevention and control crucial. Roof instability and collapse have various causes: some are due to the cutting action of weak surfaces such as joints and fissures, forming unstable blocks that easily move along the free face; some are due to the continuous concentration of disturbance stress, generating new cracks in the rock mass and leading to roof instability; some are due to cumulative damage from groundwater erosion and weathering, blasting, and other dynamic loads; or some are due to the combined superposition of various causes. For this type of geotechnical engineering hazard, in addition to necessary roof reinforcement and support, it is even more important to use sophisticated instruments and equipment for monitoring and early warning. From a temporal perspective, early warning systems can be categorized into long-term, medium-term, and short-term warnings. Roof collapse is influenced by numerous factors, such as stress-displacement boundary constraints, rock mass geological structure, joint surface details, water content and seepage field, and the excavation face. Many of these major influencing factors are imprecise or unmeasurable. Furthermore, due to the anisotropy, nonlinearity, and multiphase-multi-field coupling inherent properties of geological bodies, the evolution of various geotechnical disasters is essentially a nonlinear dynamic system, exhibiting characteristics such as chaos, bifurcation, abrupt changes, irreversibility, long-term unpredictability, ambiguity, and gray areas. The mechanisms of geotechnical disaster evolution are complex and poorly understood, resulting in poor spatial delineation, temporal prediction scales, and early warning accuracy in risk assessment, posing a significant technical challenge for the safe development of mineral resources. Because rock masses in underground engineering possess multiphase-multi-field coupling, anisotropy, and heterogeneity, they belong to nonlinear dynamic systems, making medium- to long-term predictability extremely difficult; however, short-term early warning is feasible.

[0003] In their patent "A Multi-Parameter Integrated Early Warning Method and System for Rockburst," Song Bo et al. addressed the early warning of rockbursts affecting large areas of the roof in fully mechanized coal mine faces. They employed multi-source monitoring methods and their multi-parameter monitoring values, including microseismic monitoring, ground sound monitoring, coal seam stress monitoring, drill cuttings monitoring, electromagnetic radiation monitoring, support resistance monitoring, and roof delamination monitoring. Based on a predetermined weighting principle, they weighted and fused the rockburst hazard index to determine the rockburst hazard index and early warning level for each monitoring area, thus achieving a multi-parameter integrated early warning. While this method considers multi-source monitoring, it does not implement zoned early warning.

[0004] Therefore, there is an urgent need for a method that can provide early warnings for different zones based on multi-source monitoring methods and while taking into account the specific engineering geological conditions of the monitored objects. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the present invention aims to provide a short-term early warning method for roof collapse in underground mines based on multi-source monitoring and zonal early warning values. This method utilizes multi-source monitoring and considers the specific engineering geological conditions of the monitored objects in different zonal areas, setting different early warning values ​​for different zones, thus significantly improving the accuracy of short-term early warnings.

[0006] This invention provides a short-term early warning method for roof collapse in underground mines based on multi-source monitoring and zonal early warning values, comprising the following steps:

[0007] S1. Conduct multi-source monitoring of roof collapse to obtain multi-source monitoring data;

[0008] S2. Based on the existing factors affecting rock mass collapse in several mining areas, specific influencing factors are selected, and regional early warning is carried out based on these specific influencing factors. An early warning value scoring system for rock mass fracture and surface deformation is established.

[0009] S3. Utilize the early warning scoring system based on the early warning values ​​of fractures and surface deformation within the rock mass to conduct actual zonal early warning.

[0010] In step S1, the multi-source monitoring combines microseismic monitoring sensors, lidar deformation monitoring, and fully automatic total station deformation monitoring to simultaneously measure the internal fractures and overall surface deformation of the rock mass, thereby performing coupled detection and early warning of microseismic and deformation.

[0011] In step S2, the influencing factors of the rock mass collapse in the stope include the span of the stope, the exposed area, the size of the pillar, the quality grade of the roof rock mass, the relationship between the occurrence of the rock mass structure plane and the roof and sidewalls of the goaf, groundwater, blasting vibration of adjacent stopes, and the degree of influence of mining stress in adjacent stopes.

[0012] After comprehensively considering various influencing factors, three key factors were selected for zonal early warning: the quality grade of the rock mass of the mining roof, the safety factor obtained by comparing the Mathews stability coefficient with the hydraulic radius, and the degree of impact from blasting vibration. An early warning value scoring system for rock mass fracture and surface deformation was established.

[0013] The three factors—the quality grade of the stope roof rock mass, the safety factor obtained by comparing the Mathews stability coefficient with the hydraulic radius, and the degree of influence from blasting vibration—reflect not only the physical and mechanical properties of the goaf roof and the integrity of its rock mass structure, but also the quality of the environment surrounding the goaf roof rock mass and the relationship between the goaf roof and the dominant structural weak surfaces. Furthermore, the hydraulic radius characterizes the geometric dimensions of the goaf roof itself. Using these three factors—the quality grade of the stope roof rock mass, the safety factor obtained by comparing the Mathews stability coefficient with the hydraulic radius, and the degree of influence from blasting vibration—as the scoring indicators for establishing a zoning early warning model comprehensively and accurately extracts the physical, mechanical, geometric, and environmental factors of the goaf roof.

[0014] The calculation of the quality grade of the mining roof rock mass requires obtaining five classification parameters, including rock strength, rock quality index (RQD), joint spacing, joint state, and groundwater conditions. The method for obtaining the quality grade of the mining roof rock mass includes: first, obtaining the score value of each classification parameter according to the Rock Mechanics Classification (RMR) table of jointed rock mass, and accumulating them to obtain the total score of the rock mass; then, correcting the total score according to the degree of influence of fracture orientation on different engineering projects; and finally, determining the quality grade of the rock mass based on the total score.

[0015] The specific correspondence between the total score and the rock mass quality grade is as follows: Grade 1 corresponds to a total score range of [100, 80), Grade 2 corresponds to a total score range of [80, 60), Grade 3 corresponds to a total score range of [60, 40), Grade 4 corresponds to a total score range of [40, 20), and Grade 5 corresponds to a total score range of [20, 0).

[0016] The Mathews stability coefficient N of the stope roof is calculated using the following formula: ;in, The corrected NGI tunnel quality index; A is the rock stress coefficient; B is the joint orientation coefficient; C is the gravity adjustment coefficient;

[0017] The revised NGI tunnel quality index is calculated using the following formula: ROD is a rock quality index. The joint group number influence coefficient; The roughness coefficient of the most unfavorable joint surface; The joint surface alteration coefficient;

[0018] The rock stress coefficient A is the uniaxial compressive strength of the intact rock block. Maximum secondary stress on the parallel excavation face The ratio ranges from 0.1 to 1.0;

[0019] The joint orientation coefficient B is determined based on the mutual orientation relationship between the controlling joint and the mining surface. When the angle between the structural surface and the excavation surface is 90°, the coefficient B is assigned a value of 1. When the angle between the discontinuous structural surface and the excavation surface is 20°, the value of B is 0.2.

[0020] The gravity adjustment coefficient C is calculated using the following formula: ;in, The angle of the exposed surface.

[0021] The hydraulic radius is related to the span and exposed area of ​​the mining area, and is calculated using the following formula: Where HR is the hydraulic radius; X is the span of the stope roof; and Y is the length of the goaf roof.

[0022] The safety factor obtained by comparing the Mathews stability coefficient with the hydraulic radius is obtained using the following method:

[0023] Obtain actual mining site data, and obtain the relationship between the Mathews stability coefficient and the hydraulic radius based on data fitting;

[0024] Then calculate the hydraulic radius HR and Mathews stability coefficient N of the target mining area;

[0025] Based on the relationship between the Mathews stability coefficient and the hydraulic radius, the minimum Mathews stability coefficient N1 required for the roof exposure area of ​​the current hydraulic radius to be in the stable zone is obtained by using the hydraulic radius of the target mining area.

[0026] The safety factor F, obtained by comparing the Mathews stability coefficient with the hydraulic radius, is calculated using the following formula: .

[0027] The degree of blast vibration is characterized by the vibration velocity of rock particles in the blast area and is calculated using the following formula: Where v is the maximum permissible velocity of a particle; R is the distance from the measuring point to the center of the blast source; Q is the maximum charge in a single stage; and K is a coefficient based on the properties of the explosive, the blasting method, and the terrain and geological conditions. This is the seismic wave attenuation coefficient.

[0028] The early warning scoring system for fractures and surface deformation within the rock mass is as follows:

[0029] First, the scores for each of the three factors—the quality grade of the rock mass of the mining roof, the safety factor obtained by comparing the Mathews stability coefficient with the hydraulic radius, and the degree of impact from blasting vibration—are calculated. Then, the scores are summed by weighted summation to obtain the comprehensive score.

[0030] Based on the overall score, the partition level is determined, and the ratio value of the corresponding partition level is obtained;

[0031] Finally, the zonal warning value is calculated based on the preset daily average baseline value of the warning parameters and the obtained ratio value, and zonal warnings are issued.

[0032] The overall score was obtained using the following method:

[0033] The quality grade of the rock mass of the mining roof, the safety factor obtained by comparing the Mathews stability coefficient with the hydraulic radius, and the degree of impact from blasting vibration were obtained respectively.

[0034] Based on the quality grade of the mining area roof rock mass, the corresponding sub-item scores are as follows: Grade 1 mining area roof rock mass quality grade corresponds to a sub-item score of 50 points; Grade 2 mining area roof rock mass quality grade corresponds to a sub-item score of 40 points; Grade 3 mining area roof rock mass quality grade corresponds to a sub-item score of 30 points; Grade 4 mining area roof rock mass quality grade corresponds to a sub-item score of 20 points; Grade 5 mining area roof rock mass quality grade corresponds to a sub-item score of 10 points.

[0035] The safety factor, obtained by comparing the Mathews stability coefficient with the hydraulic radius, is used to derive the corresponding sub-scores: Safety Factor Corresponding to the Level 1 safety factor, the sub-item score is 30 points; safety factor Corresponding to the Level 2 safety factor, the sub-item score is 24 points; safety factor Corresponding to the Level 2 safety factor, the sub-item score is 18 points; safety factor Corresponding to the Level 2 safety factor, the sub-item score is 12 points; safety factor The corresponding level 1 safety factor is 6 points;

[0036] Based on the degree of impact from blasting vibration, the corresponding sub-scores are obtained as follows: Degree of impact from blasting vibration. The corresponding level of blasting intensity is 20 points; the degree of impact from blasting vibration. Corresponding to the Level 1 blasting intensity level, the sub-item score is 15 points; the degree of impact from blasting vibration. Corresponding to the Level 1 blasting intensity level, the sub-item score is 10 points; the degree of impact from blasting vibration. The corresponding level 1 blasting severity is scored out of 5 points.

[0037] The scores for each of the three factors are then weighted and summed to obtain the overall score.

[0038] The method of determining the partition level based on the comprehensive score and obtaining the multiplier value of the corresponding partition level is as follows: the comprehensive score range is divided into five levels: the total score range corresponding to level 1 is [100, 85), the comprehensive score range corresponding to level 2 is [85, 70), the comprehensive score range corresponding to level 3 is [80, 50), the comprehensive score range corresponding to level 4 is [50, 25), and the comprehensive score range corresponding to level 5 is [25, 0).

[0039] The partition levels and their corresponding multiplier values ​​are as follows: Level 1 corresponds to a multiplier of 3.5, Level 2 corresponds to a multiplier of 3, Level 3 corresponds to a multiplier of 2.5, Level 4 corresponds to a multiplier of 2, and Level 5 corresponds to a multiplier of 1.5.

[0040] The early warning parameters include microseismic event rate, microseismic energy rate, density of localized event clusters, cumulative deformation, deformation rate, percentage of monitoring points exceeding the early warning value, and ratio of cumulative deformation to the size of the detected object structure.

[0041] The preset daily average baseline values ​​for the early warning parameters are as follows: microseismic event rate: 15 events / day, microseismic energy: 5 joules / day, location event cluster density: 1 event / 1000 cubic meters, cumulative deformation: 150 mm, deformation rate: 5 mm / day (lasting 3-5 days), percentage of monitoring points exceeding the early warning value: 40%, and ratio of cumulative deformation to the structural size of the detected object. The percentage of monitoring points exceeding the warning value is specifically the percentage of the number of monitoring points exceeding the warning value out of the total number of monitoring points.

[0042] The specific zonal warning value is the product of the daily average baseline value and the ratio value of the warning parameter;

[0043] The specific process for the zoning early warning is as follows: First, the zoning level is determined based on three factors: the quality grade of the rock mass of the mining roof, the safety factor obtained by comparing the Mathews stability coefficient with the hydraulic radius, and the degree of impact from blasting vibration. Then, the zoning early warning value is calculated based on the zoning level. Finally, the zoning early warning value is compared with the actual early warning parameter values ​​monitored. If the actual early warning parameter values ​​exceed the zoning early warning value, a short-term early warning for roof collapse in the underground mine is issued.

[0044] This invention discloses a short-term early warning method for roof collapse in underground mines based on multi-source monitoring and zonal early warning values. Based on multi-source monitoring methods and considering the specific engineering geological conditions of the monitored objects in different zones, different early warning values ​​are set for different zones, which significantly improves the accuracy of short-term early warning. Attached Figure Description

[0045] Figure 1 This is a schematic flowchart of the method of the present invention;

[0046] Figure 2The rock stress coefficient A and the uniaxial compressive strength of the intact rock block are described in the embodiments of the present invention. Maximum secondary stress on the parallel excavation face A graph showing the relationship between the ratios;

[0047] Figure 3 This is a diagram showing the mutual orientation relationship between the joint orientation coefficient B and the mining surface in an embodiment of the present invention.

[0048] Figure 4 This is a diagram showing the relationship between the gravity adjustment coefficient C and the dip angle of the exposed surface in the mining area, as described in this embodiment of the invention.

[0049] Figure 5 This is a schematic diagram showing the relationship between the Mathews stability coefficient and the hydraulic radius;

[0050] Figure 6 This is a real-world schematic diagram of the multi-source monitoring described in the method of the present invention;

[0051] Figure 7 This is a schematic diagram of multi-source monitoring of large-scale cracking, collapse, and sliding disaster events around the high and steep overhanging roof in an embodiment of the present invention. Detailed Implementation

[0052] This invention provides a short-term early warning method for roof collapse in underground mines based on multi-source monitoring and zonal early warning values, the flowchart of which is shown below. Figure 1 As shown, it includes the following steps:

[0053] S1. Conduct multi-source monitoring of roof collapse to obtain multi-source monitoring data;

[0054] In step S1, the multi-source monitoring combines microseismic monitoring sensors, lidar deformation monitoring, and fully automatic total station deformation monitoring to simultaneously measure the internal fractures and overall surface deformation of the rock mass, thereby performing coupled detection and early warning of microseismic and deformation.

[0055] S2. Based on the existing factors affecting rock mass collapse in several mining areas, specific influencing factors are selected, and regional early warning is carried out based on these specific influencing factors. An early warning value scoring system for rock mass fracture and surface deformation is established.

[0056] In step S2, the influencing factors of the rock mass collapse in the stope include the span of the stope, the exposed area, the size of the pillar, the quality grade of the roof rock mass, the relationship between the occurrence of the rock mass structure plane and the roof and sidewalls of the goaf, groundwater, blasting vibration of adjacent stopes, and the degree of influence of mining stress in adjacent stopes.

[0057] After comprehensively considering various influencing factors, three key factors were selected for zonal early warning: the quality grade of the rock mass of the mining roof, the safety factor obtained by comparing the Mathews stability coefficient with the hydraulic radius, and the degree of impact from blasting vibration. An early warning value scoring system for rock mass fracture and surface deformation was established.

[0058] Specifically, the early warning value scoring system for fractures and surface deformation within the rock mass is shown in Table 1.

[0059] Table 1. Early Warning Values ​​and Scoring System for Fracturing and Surface Deformation within Rock Mass

[0060] The three factors—the quality grade of the stope roof rock mass, the safety factor obtained by comparing the Mathews stability coefficient with the hydraulic radius, and the degree of influence from blasting vibration—reflect not only the physical and mechanical properties of the goaf roof and the integrity of its rock mass structure, but also the quality of the environment surrounding the goaf roof rock mass and the relationship between the goaf roof and the dominant structural weak surfaces. Furthermore, the hydraulic radius characterizes the geometric dimensions of the goaf roof itself. Using these three factors—the quality grade of the stope roof rock mass, the safety factor obtained by comparing the Mathews stability coefficient with the hydraulic radius, and the degree of influence from blasting vibration—as the scoring indicators for establishing a zoning early warning model comprehensively and accurately extracts the physical, mechanical, geometric, and environmental factors of the goaf roof.

[0061] The calculation of the quality grade of the mining roof rock mass requires obtaining five classification parameters, including rock strength, rock quality index (RQD), joint spacing, joint state, and groundwater conditions. The method for obtaining the quality grade of the mining roof rock mass includes: first, obtaining the score value of each classification parameter according to the Rock Mechanics Classification (RMR) table of jointed rock mass, and accumulating them to obtain the total score of the rock mass; then, correcting the total score according to the degree of influence of fracture orientation on different engineering projects; and finally, determining the quality grade of the rock mass based on the total score.

[0062] The specific correspondence between the total score and the rock mass quality grade is as follows: Grade 1 corresponds to a total score range of [100, 80), Grade 2 corresponds to a total score range of [80, 60), Grade 3 corresponds to a total score range of [60, 40), Grade 4 corresponds to a total score range of [40, 20), and Grade 5 corresponds to a total score range of [20, 0).

[0063] The Mathews stability coefficient N of the stope roof is calculated using the following formula: ;in, The corrected NGI tunnel quality index; A is the rock stress coefficient; B is the joint orientation coefficient; C is the gravity adjustment coefficient;

[0064] The revised NGI tunnel quality index is calculated using the following formula: ROD is a rock quality index. The joint group number influence coefficient; The roughness coefficient of the most unfavorable joint surface; The joint surface alteration coefficient;

[0065] The rock stress coefficient A and the uniaxial compressive strength of the intact rock block Maximum secondary stress on the parallel excavation face The ratios are linearly related, ranging from 0.1 to 1.0, such as... Figure 2 As shown;

[0066] The joint orientation coefficient B is determined based on the relative orientation of the controlling joints and the mining surface, such as... Figure 3 As shown, when the angle between the structural surface and the excavation surface is 90°, the B coefficient is assigned a value of 1; when the angle between the discontinuous structural surface and the excavation surface is 20°, the B value is 0.2.

[0067] The gravity adjustment coefficient C takes into account the influence of gravity on the stability of the exposed surface of the mining area, such as collapse and slippage. Figure 4 As shown, the gravity adjustment coefficient C is calculated using the following formula: ;in, The dip angle of the exposed surface in the mining area.

[0068] The hydraulic radius is related to the span and exposed area of ​​the mining area, and is calculated using the following formula: Where HR is the hydraulic radius; X is the span of the mining roof; and Y is the length of the goaf roof.

[0069] The safety factor obtained by comparing the Mathews stability coefficient with the hydraulic radius is obtained using the following method:

[0070] Obtain actual mining site data, and based on data fitting, derive the relationship between the Mathews stability coefficient and the hydraulic radius, such as... Figure 5 ;

[0071] Then calculate the hydraulic radius HR and Mathews stability coefficient N of the target mining area;

[0072] Based on the relationship between the Mathews stability coefficient and the hydraulic radius, the minimum Mathews stability coefficient N1 required for the roof exposure area of ​​the current hydraulic radius to be in the stable zone is obtained by using the hydraulic radius of the target mining area.

[0073] The safety factor F, obtained by comparing the Mathews stability coefficient with the hydraulic radius, is calculated using the following formula: .

[0074] The degree of blast vibration is characterized by the vibration velocity of rock particles in the blast area and is calculated using the following formula: Where v is the maximum permissible velocity of a particle; R is the distance from the measuring point to the center of the blast source; Q is the maximum charge in a single stage; and K is a coefficient based on the properties of the explosive, the blasting method, and the terrain and geological conditions. This is the seismic wave attenuation coefficient.

[0075] The early warning scoring system for fractures and surface deformation within the rock mass is as follows:

[0076] First, the scores for each of the three factors—the quality grade of the rock mass of the mining roof, the safety factor obtained by comparing the Mathews stability coefficient with the hydraulic radius, and the degree of impact from blasting vibration—are calculated. Then, the scores are summed by weighted summation to obtain the comprehensive score.

[0077] Based on the overall score, the partition level is determined, and the ratio value of the corresponding partition level is obtained;

[0078] Finally, the zonal warning value is calculated based on the preset daily average baseline value of the warning parameters and the obtained ratio value, and zonal warnings are issued.

[0079] The overall score was obtained using the following method:

[0080] The quality grade of the rock mass of the mining roof, the safety factor obtained by comparing the Mathews stability coefficient with the hydraulic radius, and the degree of impact from blasting vibration were obtained respectively.

[0081] Based on the quality grade of the mining area roof rock mass, the corresponding sub-item scores are as follows: Grade 1 mining area roof rock mass quality grade corresponds to a sub-item score of 50 points; Grade 2 mining area roof rock mass quality grade corresponds to a sub-item score of 40 points; Grade 3 mining area roof rock mass quality grade corresponds to a sub-item score of 30 points; Grade 4 mining area roof rock mass quality grade corresponds to a sub-item score of 20 points; Grade 5 mining area roof rock mass quality grade corresponds to a sub-item score of 10 points.

[0082] The safety factor, obtained by comparing the Mathews stability coefficient with the hydraulic radius, is used to derive the corresponding sub-scores: Safety Factor Corresponding to the Level 1 safety factor, the sub-item score is 30 points; safety factor Corresponding to the Level 2 safety factor, the sub-item score is 24 points; safety factor Corresponding to the Level 2 safety factor, the sub-item score is 18 points; safety factor Corresponding to the Level 2 safety factor, the sub-item score is 12 points; safety factor The corresponding level 1 safety factor is 6 points;

[0083] Based on the degree of impact from blasting vibration, the corresponding sub-scores are obtained as follows: Degree of impact from blasting vibration. The corresponding level of blasting intensity is 20 points; the degree of impact from blasting vibration. Corresponding to the Level 1 blasting intensity level, the sub-item score is 15 points; the degree of impact from blasting vibration. Corresponding to the Level 1 blasting intensity level, the sub-item score is 10 points; the degree of impact from blasting vibration. The corresponding level 1 blasting severity is scored out of 5 points.

[0084] The scores for each of the three factors are then weighted and summed to obtain the overall score.

[0085] The method of determining the partition level based on the comprehensive score and obtaining the multiplier value of the corresponding partition level is as follows: the comprehensive score range is divided into five levels: the total score range corresponding to level 1 is [100, 85), the comprehensive score range corresponding to level 2 is [85, 70), the comprehensive score range corresponding to level 3 is [80, 50), the comprehensive score range corresponding to level 4 is [50, 25), and the comprehensive score range corresponding to level 5 is [25, 0).

[0086] The partition levels and their corresponding multiplier values ​​are as follows: Level 1 corresponds to a multiplier of 3.5, Level 2 corresponds to a multiplier of 3, Level 3 corresponds to a multiplier of 2.5, Level 4 corresponds to a multiplier of 2, and Level 5 corresponds to a multiplier of 1.5.

[0087] The early warning parameters include microseismic event rate, microseismic energy rate, density of localized event clusters, cumulative deformation, deformation rate, percentage of monitoring points exceeding the early warning value, and ratio of cumulative deformation to the size of the detected object structure.

[0088] The preset daily average baseline values ​​for the early warning parameters are as follows: microseismic event rate: 15 events / day, microseismic energy: 5 joules / day, location event cluster density: 1 event / 1000 cubic meters, cumulative deformation: 150 mm, deformation rate: 5 mm / day (lasting 3-5 days), percentage of monitoring points exceeding the early warning value: 40%, and ratio of cumulative deformation to the structural size of the detected object. The percentage of monitoring points exceeding the warning value is specifically the proportion of the number of monitoring points exceeding the warning value to the total number of monitoring points.

[0089] The specific zonal warning value is the product of the daily average baseline value and the ratio value of the warning parameter;

[0090] The specific process for the zoning early warning is as follows: First, the zoning level is determined based on three factors: the quality grade of the rock mass of the mining roof, the safety factor obtained by comparing the Mathews stability coefficient with the hydraulic radius, and the degree of impact from blasting vibration. Then, the zoning early warning value is calculated based on the zoning level. Finally, the zoning early warning value is compared with the actual early warning parameter values ​​monitored. If the actual early warning parameter values ​​exceed the zoning early warning value, a short-term early warning for roof collapse in the underground mine is issued.

[0091] S3. Utilize the early warning scoring system based on the early warning values ​​of fractures and surface deformation within the rock mass to conduct actual zonal early warning.

[0092] The method of the present invention will be further described below with reference to the embodiments:

[0093] This invention combines microseismic monitoring with lidar deformation monitoring or fully automated total station (commonly known as a "measuring robot") deformation monitoring to simultaneously measure the internal fractures and overall surface deformation of the rock mass, enabling coupled monitoring and early warning of microseismic and deformation phenomena. Figure 6 and Figure 7 As shown, after installing microseismic monitoring equipment to monitor rock mass fracture around the roof of the mining area, a lidar monitoring device with millimeter-level deformation measurement accuracy was installed. At the same time, multi-source coupled monitoring and early warning of roof collapse were carried out.

Claims

1. A method for short-term early warning of roof collapse in underground mines based on multi-source monitoring and zonal early warning values, characterized in that, Includes the following steps: S1. Conduct multi-source monitoring of roof collapse to obtain multi-source monitoring data; S2. Based on the existing factors affecting rock mass collapse in several mining areas, specific influencing factors are selected, and regional early warning is carried out based on these specific influencing factors. An early warning value scoring system for rock mass fracture and surface deformation is established. S3. Utilize the early warning scoring system based on the early warning values ​​of fractures and surface deformation within the rock mass to conduct actual zonal early warning.

2. The short-term early warning method for underground mine roof collapse based on multi-source monitoring and zonal early warning values ​​as described in claim 1, characterized in that, In step S1, the multi-source monitoring combines microseismic monitoring sensors, lidar deformation monitoring, and fully automatic total station deformation monitoring to simultaneously measure the internal fractures and overall surface deformation of the rock mass, thereby performing coupled detection and early warning of microseismic and deformation.

3. The short-term early warning method for roof collapse in underground mines based on multi-source monitoring and zonal early warning values ​​as described in claim 1, characterized in that, In step S2, the influencing factors of rock mass collapse in the stope include the stope span, exposed area, pillar size, roof rock mass quality grade, rock mass structure surface occurrence and its relationship with the roof and sidewalls of the goaf, groundwater, blasting vibration in adjacent stops, and the degree of influence of mining stress in adjacent stops. Three factors were selected for zonal early warning: stope roof rock mass quality grade, safety factor obtained by comparing Mathews stability coefficient with hydraulic radius, and degree of influence of blasting vibration. An early warning value scoring system for rock mass fracture and surface deformation was established.

4. The short-term early warning method for underground mine roof collapse based on multi-source monitoring and zonal early warning values ​​as described in claim 3, characterized in that, The calculation of the quality grade of the mining roof rock mass requires obtaining five classification parameters, including rock strength, rock quality index, joint spacing, joint state, and groundwater conditions. The method for obtaining the quality grade of the mining roof rock mass includes: first, obtaining the score value of each classification parameter according to the rock mechanics classification table of jointed rock mass, and accumulating them to obtain the total score of the rock mass; then, correcting the total score according to the degree of influence of fracture orientation on different engineering projects; and finally, determining the quality grade of the rock mass based on the total score.

5. The short-term early warning method for underground mine roof collapse based on multi-source monitoring and zonal early warning values ​​as described in claim 3, characterized in that, The Mathews stability coefficient N of the stope roof is calculated using the following formula: ;in, The corrected NGI tunnel quality index; A is the rock stress coefficient; B is the joint orientation coefficient; C is the gravity adjustment coefficient; The revised NGI tunnel quality index is calculated using the following formula: ROD is a rock quality index. The joint group number influence coefficient; The roughness coefficient of the most unfavorable joint surface; The joint surface alteration coefficient; The rock stress coefficient A is the uniaxial compressive strength of the intact rock block. Maximum secondary stress on the parallel excavation face The ratio ranges from 0.1 to 1.0; The joint orientation coefficient B is determined based on the mutual orientation relationship between the controlling joint and the mining surface. When the angle between the structural surface and the excavation surface is 90°, the coefficient B is assigned a value of 1. When the angle between the discontinuous structural surface and the excavation surface is 20°, the value of B is 0.

2. The gravity adjustment coefficient C is calculated using the following formula: ;in, The angle of the exposed surface.

6. The short-term early warning method for underground mine roof collapse based on multi-source monitoring and zonal early warning values ​​according to claim 3, characterized in that, The hydraulic radius is related to the span and exposed area of ​​the mining area, and is calculated using the following formula: Where HR is the hydraulic radius; X is the span of the stope roof; and Y is the length of the goaf roof. The safety factor obtained by comparing the Mathews stability coefficient with the hydraulic radius is obtained using the following method: Obtain actual mining site data, and obtain the relationship between the Mathews stability coefficient and the hydraulic radius based on data fitting; Then calculate the hydraulic radius HR and Mathews stability coefficient N of the target mining area; Based on the relationship between the Mathews stability coefficient and the hydraulic radius, the minimum Mathews stability coefficient N1 required for the roof exposure area of ​​the current hydraulic radius to be in the stable zone is obtained by using the hydraulic radius of the target mining area. The safety factor F, obtained by comparing the Mathews stability coefficient with the hydraulic radius, is calculated using the following formula: ; The degree of blast vibration is characterized by the vibration velocity of rock particles in the blast area and is calculated using the following formula: Where v is the maximum permissible velocity of a particle; R is the distance from the measuring point to the center of the blast source; Q is the maximum charge in a single stage; and K is a coefficient based on the properties of the explosive, the blasting method, and the terrain and geological conditions. This is the seismic wave attenuation coefficient.

7. The short-term early warning method for roof collapse in underground mines based on multi-source monitoring and zonal early warning values ​​as described in claim 1, characterized in that, The early warning scoring system for fractures and surface deformation within the rock mass is as follows: First, the scores for each of the three factors—the quality grade of the rock mass of the mining roof, the safety factor obtained by comparing the Mathews stability coefficient with the hydraulic radius, and the degree of impact from blasting vibration—are calculated. Then, the scores are summed by weighted summation to obtain the comprehensive score. Based on the overall score, the partition level is determined, and the ratio value of the corresponding partition level is obtained; Finally, the zonal warning value is calculated based on the preset daily average baseline value of the warning parameters and the obtained ratio value, and zonal warnings are issued.

8. The short-term early warning method for roof collapse in underground mines based on multi-source monitoring and zonal early warning values ​​as described in claim 7, characterized in that, The method of determining the partition level based on the comprehensive score and obtaining the multiplier value of the corresponding partition level is as follows: the comprehensive score range is divided into five levels: the total score range corresponding to level 1 is [100, 85), the comprehensive score range corresponding to level 2 is [85, 70), the comprehensive score range corresponding to level 3 is [80, 50), the comprehensive score range corresponding to level 4 is [50, 25), and the comprehensive score range corresponding to level 5 is [25, 0). The partition levels and their corresponding multiplier values ​​are as follows: Level 1 corresponds to a multiplier of 3.5, Level 2 corresponds to a multiplier of 3, Level 3 corresponds to a multiplier of 2.5, Level 4 corresponds to a multiplier of 2, and Level 5 corresponds to a multiplier of 1.

5.

9. The short-term early warning method for roof collapse in underground mines based on multi-source monitoring and zonal early warning values ​​as described in claim 7, characterized in that, The early warning parameters include microseismic event rate, microseismic energy rate, density of localized event clusters, cumulative deformation, deformation rate, percentage of monitoring points exceeding the early warning value, and ratio of cumulative deformation to the size of the detected object structure. The preset daily average baseline values ​​for the early warning parameters are as follows: micro-seismic event rate: 15 events / day; micro-seismic energy: 5 joules / day; location event cluster density: 1 event / 1000 cubic meters; cumulative deformation: 150 mm; deformation rate over 3-5 days: 5 mm / day; percentage of monitoring points exceeding the early warning value: 40%; and the ratio of cumulative deformation to the structural dimensions of the detected object. The percentage of monitoring points exceeding the warning value is specifically the percentage of the number of monitoring points exceeding the warning value out of the total number of monitoring points.

10. The short-term early warning method for roof collapse in underground mines based on multi-source monitoring and zonal early warning values ​​according to claim 7, characterized in that, The specific zonal warning value is the product of the daily average baseline value and the ratio value of the warning parameter; The specific process for the zoning early warning is as follows: First, the zoning level is determined based on three factors: the quality grade of the rock mass of the mining roof, the safety factor obtained by comparing the Mathews stability coefficient with the hydraulic radius, and the degree of impact from blasting vibration. Then, the zoning early warning value is calculated based on the zoning level. Finally, the zoning early warning value is compared with the actual early warning parameter values ​​monitored. If the actual early warning parameter values ​​exceed the zoning early warning value, a short-term early warning for roof collapse in the underground mine is issued.

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