Rockburst risk assessment method for coal mining roadway based on microseismic disturbance cumulative damage
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- CHINA UNIV OF MINING & TECH
- Filing Date
- 2026-04-27
- Publication Date
- 2026-07-10
Smart Images
Figure CN122362484A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of mine safety engineering technology, specifically relating to a method for assessing the impact hazard of coal mine roadways based on cumulative damage from micro-vibration disturbances. Background Technology
[0002] With the continuous increase in coal mining depth and mining intensity, deep coal and rock masses are in a complex mechanical environment of "high ground stress, high gas, and high mining disturbance". The frequency and intensity of mine earthquakes and rock bursts during the mining process have increased significantly, seriously threatening the stability of the surrounding rock in the mining roadway and the life safety of underground workers. This has become the core bottleneck restricting the safe and efficient mining of deep coal resources.
[0003] Existing rockburst risk assessment and early warning technologies are mainly divided into three categories: The first category is static assessment methods, which assess roadway rockburst risk through theoretical calculations or numerical simulations based on measured ground stress, coal seam rockburst tendency tests, and rock mass structure survey results. This type of method cannot reflect the damage impact of dynamic disturbances on the surrounding rock during mining, has poor timeliness, and is difficult to adapt to the dynamic evolution of the stress field during mining. The second category is early warning methods based on single microseismic parameters, which use the energy, magnitude, frequency, and spatial concentration of microseismic events as core indicators and set thresholds for risk warning. This type of method only focuses on the triggering of a single strong earthquake event. The first category is the effect of near-field microseismic events. The first category generally ignores the long-term cumulative damage effect of multiple small and medium energy microseismic events on coal and rock masses, and cannot reflect the deterioration process of the mechanical properties of the surrounding rock, which is very easy to miss the risk assessment. The second category is the seismic wave parameter assessment method, which uses the peak particle velocity (pgv) to characterize the intensity of vibration disturbance. However, existing technologies mostly directly use pgv data monitored by far-field stations, without distinguishing the difference in the propagation effect of seismic waves between the near-field and far-field regions. The vibration in the near-field region is mainly a displacement field, and the strong dynamic impact effect on the surrounding rock of the roadway is much greater than that in the far-field region. Existing methods seriously underestimate the damage effect of near-field microseismic events on the roadway, resulting in insufficient accuracy of risk assessment.
[0004] In summary, existing rockburst risk assessment technologies generally suffer from problems such as ignoring the cumulative damage effect of microseismic disturbances, failing to distinguish between near-field and far-field vibration effects, using static risk criteria, and exhibiting delayed or missed early warnings. These limitations prevent them from achieving quantitative, dynamic, and proactive assessment of rockburst risks in mining roadways. Therefore, developing a rockburst risk assessment method that comprehensively considers the cumulative effect of microseismic disturbances, accurately characterizes the evolution of surrounding rock damage, and is adapted to the dynamic process of mining is of significant engineering importance and application value. Summary of the Invention
[0005] To address the problems of existing technologies, this invention provides a method for assessing the rockburst risk of coal mine roadways based on cumulative damage from microseismic disturbances. By dividing the near-field and far-field action areas of microseismic events, constructing quantitative indicators of cumulative damage to coal and rock masses, and establishing dynamic risk growth criteria, this invention solves the problems of existing technologies neglecting the cumulative damage effect of microseismic events, low assessment accuracy caused by strong near-field impact effects, and delayed early warning and missed judgments. This method enables a quantitative, dynamic, and proactive assessment of the rockburst risk in coal mine roadways.
[0006] To achieve the above objectives, the technical solution adopted by this invention is: a method for assessing the risk of rockburst in coal mining face roadways based on cumulative damage from micro-vibration disturbance, comprising the following steps: S1. Collect information on the layout of the microseismic network, microseismic monitoring data, and working face roadway layout of the target mine to delineate the target area for rockburst risk assessment.
[0007] S2. Based on the target area determined in step S1, all historical valid microseismic events within the spatial range of the target area are selected, and the peak particle velocity pgv and peak particle acceleration pga of the vibration waveform of each microseismic event are extracted. Simultaneously, the local magnitude M of the microseismic events is also considered. L Calculate the focal radius r0 of the corresponding microseismic event.
[0008] S3. For each microseismic event selected in step S2, based on the peak particle velocity pgv of the waveform received by different microseismic stations, calculate the source distance R between the microseismic event and each receiving station, obtain the vibration intensity parameter pgvR corresponding to each station for the microseismic event, and select the maximum value pgvR. max This serves as a characterization parameter for the intensity of far-field vibrations in this microseismic event.
[0009] S4. Discretize the coal mining face roadway in the target area into several evaluation units of equal length along the strike, calculate the vertical distance d between each microseismic event screened in step S2 and the center of each evaluation unit, and determine whether the evaluation unit is in the near field or far field of the microseismic event by using the critical value.
[0010] S5. Based on the field determination results of step S4, for each micro-seismic event, calculate the near-field vibration intensity induced by it on the near-field assessment unit of the mining roadway and the far-field vibration intensity induced by it on the far-field assessment unit.
[0011] S6, Preset low-intensity vibration filtering threshold pgv k Threshold filtering is performed on all near-field and far-field vibration intensities obtained in step S5, retaining those greater than pgv. kEffective vibration intensity data; based on all effective vibration intensity data within each assessment unit, calculate the cumulative damage index NHGM (Number of High-intensity Ground Motions) for coal and rock mass in each assessment unit, and generate a spatial distribution map of NHGM for the entire roadway.
[0012] S7. Based on the daily NHGM spatial distribution map generated in step S6, calculate the NHGM increment ΔNHGM of the same assessment unit in the roadway in front of the working face on the current day and the previous day, and draw a line graph showing the correlation between ΔNHGM and the working face mining distance.
[0013] S8. Based on the correlation between ΔNHGM and mining distance obtained in step S7, risk criteria are set to identify the degree of damage evolution of roadway surrounding rock and high-risk areas of rockburst.
[0014] Further, in step S1, the microseismic network layout information includes the microseismic network layout time, the three-dimensional coordinates of each microseismic station, and station relocation records; the microseismic monitoring data includes the original microseismic waveform files, the occurrence time of the microseismic event, the three-dimensional source coordinates, and the arrival time marker data of the seismic waves for each microseismic station; the working face roadway layout information includes the roadway direction and three-dimensional coordinates, the elevation of the floor contour lines, and the coordinates of the intersections with the roadway; and at least four microseismic stations are arranged around the target area to ensure that the microseismic event location accuracy meets the evaluation requirements.
[0015] Further, in step S2, the formula for calculating the source radius r0 of the microseismic event is: In the formula, M L The local magnitude of the microseismic event is r0, expressed in meters (m).
[0016] Furthermore, step S3 specifically includes: S31. Calculate the focal distance R between microseismic event i and microseismic station b. The calculation formula is as follows: In the formula, (x b y b , z b Let (x) be the three-dimensional coordinates of the b-th microseismic station. i y i , z i ) represents the three-dimensional coordinates of the source of microseismic event i.
[0017] S32. Based on the peak particle velocity and source distance recorded at each station, calculate the vibration intensity parameter pgvR. The calculation formula is as follows: In the formula, pgv b R represents the peak velocity of the microseismic event recorded at station b, in m / s. b denoted as b, representing the distance between the b-th station and the epicenter of the microseismic event, in meters.
[0018] S33. Select PGVR data from all stations corresponding to the same microseismic event. b The maximum value in pgvR is used as a characterization parameter of the far-field seismic intensity of this microseismic event. max Eliminate the influence of seismic wave propagation attenuation and station layout on the characterization of seismic intensity.
[0019] Further, in step S4, the field determination rule is as follows: taking twice the source radius of the microseismic event, 2r0, as the critical value, if the distance d between the evaluation unit and the source of the microseismic event is ≥2r0, then the evaluation unit is determined to be in the far field region of the microseismic event; if d <2r0, then the evaluation unit is determined to be in the near field region of the microseismic event; the length of the evaluation unit is 10m; taking into account both evaluation accuracy and calculation efficiency.
[0020] Furthermore, in step S5, the calculation formulas for near-field vibration intensity and far-field vibration intensity are as follows: Far-field vibration intensity: The far-field seismic waves propagate in the form of spherical waves, and the vibration intensity is inversely proportional to the propagation distance. Based on the far-field vibration intensity characterization parameters, the vibration intensity at different distances can be directly calculated.
[0021] Near-field vibration intensity: In the formula, d is the distance between the assessment unit and the source of the microseismic event, in meters; ρ is the density of the coal and rock mass, in kg / m³; C s denoted as shear wave velocity of the coal and rock mass, in m / s; G is the stiffness of the coal and rock mass; pga is the peak acceleration of a particle.
[0022] Further, in step S6, the low-intensity vibration filtering threshold PGV k =0.01m / s, this threshold is the critical vibration intensity for plastic damage to coal and rock mass; the calculation formula for the cumulative damage index NHGM of coal and rock mass is: In the formula, NHGM i pgv is the cumulative damage index value of the i-th evaluation unit. jdenoted as the vibration intensity induced by the j-th microseismic event in this assessment unit; q is the latest recorded total sequence number of the microseismic event; the larger the NHGM value, the more times the coal and rock mass in this area is subjected to high-intensity vibration disturbance, and the more severe the cumulative damage.
[0023] Further, in step S7, the formula for calculating the NHGM increment ΔNHGM is: In the formula, NHGM i,t Let NHGM be the NHGM value for the i-th assessment unit on that day. i,t-1 The NHGM value is the value of the previous day for the same assessment unit; the daily growth rate of ΔNHGM is calculated using the following formula: In the formula, v is the daily growth rate of ΔNHGM, which characterizes the evolution rate of surrounding rock damage.
[0024] Further, in step S6, the low-intensity vibration filtering threshold pgv k The value range is 0.005m / s to 0.02m / s, and is adjusted according to the impact tendency level of the target coal seam. The lower value is used for coal seams with strong impact tendency, and the higher value is used for coal seams with weak impact tendency. In step S8, the growth rate threshold of the risk criterion is 30% to 60%, and is adjusted according to the mine rockburst risk level. The lower value is used for high-risk mines, and the higher value is used for low-risk mines.
[0025] Furthermore, in step S8, as the working face advances, the NHGM data of the mined area is deleted in real time, and the incremental NHGM data ΔNHGM data of the unmined area in front of the working face is continuously updated. The risk assessment process is executed cyclically until the working face is mined out, thus achieving dynamic risk assessment throughout the entire mining cycle.
[0026] Furthermore, in step S8, the daily growth rate of NHGM increment ΔNHGM exceeding 50% is used as a risk criterion to identify the degree of damage evolution of the surrounding rock in the roadway and high-risk areas for rockburst; if the daily growth rate of ΔNHGM in a certain assessment unit is >50%, it is determined that the degree of damage to the surrounding rock in that area is high and it has a high risk of rockburst.
[0027] Compared with the prior art, the present invention has the following advantages: 1. This invention proposes for the first time to divide the near-field and far-field regions of microseismic events on roadways using twice the source radius as the critical value. It establishes vibration intensity calculation models for the vibration wave propagation characteristics of different fields, accurately distinguishes the damage effects of near-field strong dynamic impact and far-field vibration disturbance, solves the problem of existing technologies seriously underestimating the damage of near-field microseismic events to the surrounding rock of roadways, and greatly improves the calculation accuracy of vibration disturbance intensity.
[0028] 2. This invention constructs a unique cumulative damage index for coal and rock masses, NHGM. By filtering out low-intensity vibrations that do not produce plastic damage through a critical threshold, it accumulates and counts the number of disturbances of historical effective micro-seismic events, quantitatively characterizing the cumulative damage degree of coal and rock masses. This solves the problem of existing technologies neglecting the cumulative damage effect of multiple small and medium energy micro-seismic events, and achieves accurate characterization of the deterioration process of the mechanical properties of surrounding rock.
[0029] 3. This invention uses the daily growth rate of ΔNHGM as the criterion for rockburst risk, and combines it with the dynamic update assessment data of the working face mining progress to achieve dynamic and advanced assessment of rockburst risk. It solves the problems of static risk criteria and delayed early warning in existing technologies, and can identify high-risk areas of accelerated evolution of surrounding rock damage in advance, allowing sufficient time for the implementation of rockburst prevention measures and mining decisions.
[0030] 4. The method of this invention can be implemented using the microseismic monitoring system commonly deployed in underground coal mines, without the need for additional hardware equipment. The operation process is standardized, the calculation parameters are quantifiable, and the repeatability is strong. It is applicable to the full-cycle impact risk assessment of mining roadways in coal seams with different mining depths and different impact tendencies, and has strong engineering applicability and promotion value. Attached Figure Description
[0031] Figure 1 This is a schematic diagram of the distribution of microseismic stations and the layout of the target working face roadway in an embodiment of the present invention.
[0032] Figure 2 This is a graph showing the correspondence between near-field vibration intensity and microseismic energy in a microseismic event according to an embodiment of the present invention.
[0033] Figure 3 This is a spatial distribution map of NHGM in the mining roadway according to an embodiment of the present invention.
[0034] Figure 4 This is a trend graph showing the variation of ΔNHGM with the working face mining distance in an embodiment of the present invention. Detailed Implementation
[0035] The present invention will be further described below.
[0036] like Figure 1 As shown, this embodiment uses the 401102 working face of a mine in Shaanxi Province as the engineering background and employs the method of this invention to conduct a risk assessment of rockburst in the mining roadway. The mine has a mining depth of over 800m, the main coal seam has a strong tendency to rockburst, and the roof of the coal seam is composed of multiple layers of thick and hard composite sandstone. During the mining process, mine seismic activity is frequent, and rockburst events have occurred many times. The roadway has experienced serious problems such as floor heave, cracking of the anchor mesh, and damage to the support structure, which seriously threaten the safe production of the mine.
[0037] The specific implementation steps of this embodiment are as follows: Step 1: Basic data collection and target area determination: Collect information on the layout of the microseismic network, microseismic monitoring data and roadway layout of the 401102 working face of the mine.
[0038] Microseismic network layout information: A total of 6 microseismic monitoring stations were deployed around the working face to record the three-dimensional coordinates, deployment time, and relocation records of each station. The station distribution is as follows: Figure 1 As shown, it meets the positioning requirements of no less than 4 stations.
[0039] Microseismic monitoring data: The microseismic energy, occurrence time of microseismic events, three-dimensional coordinates of the seismic source, and local magnitude of the microseismic events collected during the mining of the 401102 working face are shown in Table 1.
[0040] Table 1 Roadway layout information: Collect the direction, three-dimensional coordinates, and bottom plate contour elevation data of the transport roadway and return air roadway of the 401102 working face, and delineate the advanced area of the two roadways within the working face mining influence range as the risk assessment target area.
[0041] Step 2: Microseismic event screening and core parameter extraction: Historical valid microseismic events within the target area were screened, and invalid events with positioning errors greater than 10m and waveform signal-to-noise ratios below 30dB were removed. A total of four key microseismic events were selected, and the peak particle velocity (pgv) of the vibration waveforms for each event was extracted. Based on the local magnitude (M) of each microseismic event... L Calculate the source radius r0.
[0042] The calculation results are shown in Table 2.
[0043] Table 2 Step 3: Calculation of far-field vibration intensity characterization parameters: For the four microseismic events in Table 2, the focal distance R between each event and the six receiving stations was calculated using the following formula: Based on the PGV data recorded by each station, the vibration intensity parameter PGVR is calculated using the following formula: Select the maximum pgvR value of all stations corresponding to each event. max As a characterization parameter of the far-field vibration intensity of this event, the calculation results are shown in Table 3.
[0044] Table 3 Step 4: Roadway discretization and near-field / far-field region determination: The transport roadway and return air roadway of the 401102 working face were discretized into assessment units with a length of 10m along the strike. The vertical distance d between each microseismic event and the center of each assessment unit was calculated. The field attributes of each assessment unit were determined with twice the source radius 2r0 as the critical value. The determination rule is: d≥2r0 is the far field area, and d<2r0 is the near field area. The field determination results of the key events are shown in Table 4.
[0045] Table 4 Step 5: Calculation of vibration intensity in different fields: Based on the field determination results, the vibration intensity caused by the microseismic event to different assessment units was calculated as follows: Figure 2 As shown, the specific calculation process is as follows: Step 6: Calculation and distribution map generation of cumulative damage index NHGM: Preset low-intensity vibration filtering threshold pgv k =0.01m / s. All vibration intensity data calculated in step 5 are filtered, and valid vibration intensity data with a value greater than 0.01m / s are retained.
[0046] For each 10m long evaluation unit, the cumulative number of effective vibration events within the unit is counted, and the NHGM value is calculated using the following formula: Based on the NHGM calculation results of each assessment unit, a spatial distribution map of NHGM across the entire orientation of the mining roadway is generated, such as... Figure 3 As shown, the higher the NHGM value, the more severe the cumulative damage to the coal and rock mass.
[0047] Step 7: Calculation of NHGM increments and plotting of trend charts: Based on the daily generated NHGM spatial distribution map, the NHGM increment ΔNHGM of the same assessment unit on the current day and the previous day is calculated using the following formula: In the formula, NHGM i,t Let NHGM be the NHGM value for the i-th assessment unit on that day. i,t-1 The NHGM value is the value of the previous day for the same assessment unit; the daily growth rate of ΔNHGM is calculated using the following formula: In the formula, v is the daily growth rate of ΔNHGM, which characterizes the evolution rate of surrounding rock damage.
[0048] Calculate the daily growth rate of ΔNHGM and plot a line graph showing the relationship between ΔNHGM and the working face recovery distance, such as... Figure 4 As shown.
[0049] Step 8: Identification of rockburst risk areas: Using the daily growth rate of ΔNHGM v > 50% as the core risk criterion, the rockburst risk of each assessment unit in the roadway is determined: Following the microseismic event on April 8, the daily growth rate of ΔNHGM in the area 1220m to 1280m from the cut-off point reached 78%, exceeding the 50% threshold, thus classifying the area as a high-risk zone for rockburst.
[0050] The on-site verification results showed that significant rockburst occurred during the subsequent mining process in the area, with the maximum floor heave reaching 800 mm, which is completely consistent with the risk assessment results of this invention, verifying the accuracy and reliability of this method.
[0051] As the mining progresses, the NHGM data of the mined area is deleted in real time, and the ΔNHGM data of the advanced area in front of the working face is continuously updated. The above assessment process is repeated until the mining of the 401102 working face is completed, thus realizing dynamic assessment of rockburst risk throughout the entire mining cycle.
[0052] 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 assessing the impact hazard of coal mine roadways based on cumulative damage from microseismic disturbances, characterized in that, Includes the following steps: S1. Collect information on the layout of the microseismic network, microseismic monitoring data, and working face roadway layout of the target mine to delineate the target area for rockburst risk assessment; S2. Based on the target area determined in step S1, all historical valid microseismic events within the spatial range of the target area are selected, and the peak velocity and peak acceleration of the particle in the vibration waveform of each microseismic event are extracted. At the same time, the source radius of the corresponding microseismic event is calculated based on the local magnitude of the microseismic event. S3. For each microseismic event selected in step S2, based on the peak velocity of the waveform particles received by different microseismic stations, calculate the source distance between the microseismic event and each receiving station, obtain the vibration intensity parameters of each station corresponding to the microseismic event, and select the maximum value as the characterization parameter of the vibration intensity in the far field region of the microseismic event. S4. Discretize the coal mining face roadway in the target area into several equal-length evaluation units along the strike, calculate the vertical distance between each microseismic event screened in step S2 and the center of each evaluation unit, and determine whether the evaluation unit is in the near field or far field of the microseismic event by using the critical value. S5. Based on the field determination results of step S4, for each micro-seismic event, calculate the near-field vibration intensity induced by it on the near-field assessment unit of the mining roadway and the far-field vibration intensity induced by it on the far-field assessment unit. S6. Preset a low-intensity vibration filtering threshold, and perform threshold filtering on all near-field vibration intensity and far-field vibration intensity obtained in step S5, retaining valid vibration intensity data that are greater than the threshold. Based on all effective vibration intensity data within each assessment unit, the cumulative damage index (NHGM) of coal and rock mass in each assessment unit is obtained, and a spatial distribution map of NHGM for the entire roadway is generated. S7. Based on the daily NHGM spatial distribution map generated in step S6, calculate the NHGM increment of the same assessment unit in the roadway in front of the working face on the current day and the previous day, and draw a line graph showing the correlation between the NHGM increment and the working face mining distance. S8. Based on the correlation between the NHGM increment and the mining distance obtained in step S7, risk criteria are set to identify the degree of damage evolution of the surrounding rock in the roadway and high-risk areas of rockburst.
2. The evaluation method according to claim 1, characterized in that, In step S1, the microseismic network layout information includes the microseismic network layout time, the three-dimensional coordinates of each microseismic station, and station relocation records; the microseismic monitoring data includes the original microseismic waveform files, the occurrence time of microseismic events, the three-dimensional source coordinates, and the arrival time marker data of the seismic waves for each microseismic station; the working face roadway layout information includes the roadway direction and three-dimensional coordinates, the elevation of the floor contour lines, and the coordinates of the intersections with the roadways; and at least four microseismic stations are arranged around the target area.
3. The evaluation method according to claim 1, characterized in that, In step S2, the formula for calculating the focal radius r0 of the microseismic event is: In the formula, M L This refers to the local magnitude of the microseismic event.
4. The evaluation method according to claim 1, characterized in that, Step S3 specifically includes: S31. Calculate the focal distance between microseismic event i and microseismic station b. The calculation formula is: In the formula, (x b y b , z b Let (x) be the three-dimensional coordinates of the b-th microseismic station. i y i , z i () represents the three-dimensional coordinates of the source of microseismic event i; S32. Based on the peak particle velocity and source distance recorded at each station, calculate the vibration intensity parameter pgvR. The calculation formula is as follows: In the formula, pgvR b R represents the peak velocity of the microseismic event recorded at station b. b denoted as b-th station, representing the distance between the epicenter of the microseismic event; S33. Select PGVR data from all stations corresponding to the same microseismic event. b The maximum value in pgvR is used as a characterization parameter of the far-field seismic intensity of this microseismic event. max .
5. The evaluation method according to claim 1, characterized in that, In step S4, the field determination rule is as follows: taking twice the source radius of the microseismic event, 2r0, as the critical value, if the distance d between the evaluation unit and the source of the microseismic event is ≥2r0, then the evaluation unit is determined to be in the far field region of the microseismic event; if d <2r0, then the evaluation unit is determined to be in the near field region of the microseismic event; the length of the evaluation unit is 10m.
6. The evaluation method according to claim 1, characterized in that, In step S5, the calculation formulas for near-field vibration intensity and far-field vibration intensity are as follows: Far-field vibration intensity: Near-field vibration intensity: In the formula, d is the distance between the assessment unit and the source of the microseismic event; ρ is the density of the coal and rock mass; C s denoted as , where is the transverse wave velocity of the coal and rock mass; G is the stiffness of the coal and rock mass; and pga is the peak acceleration of a particle.
7. The evaluation method according to claim 1, characterized in that, In step S6, the low-intensity vibration filtering threshold PGV k =0.01m / s; the calculation formula for the cumulative damage index NHGM of the coal and rock mass is: In the formula, NHGM i pgv is the cumulative damage index value of the i-th evaluation unit. j q represents the vibration intensity induced by the j-th microseismic event in this assessment unit; q is the latest recorded microseismic event sequence number.
8. The evaluation method according to claim 1, characterized in that, In step S6, the low-intensity vibration filtering threshold pgv k The value range is 0.005m / s to 0.02m / s, adjusted according to the impact tendency level of the target coal seam; in step S8, the growth rate threshold of the risk criterion ranges from 30% to 60%, adjusted according to the mine rockburst risk level.
9. The evaluation method according to claim 1, characterized in that, In step S8, as the working face advances, the NHGM data of the mined area is deleted in real time, and the incremental NHGM data of the unmined area in front of the working face is continuously updated. The risk assessment process is repeated until the working face is mined.
10. The evaluation method according to claim 8, characterized in that, In step S8, the daily growth rate of NHGM increment ΔNHGM exceeding 50% is used as the risk criterion to identify the degree of damage evolution of the surrounding rock in the roadway and high-risk areas of rockburst. If the daily growth rate of ΔNHGM in a certain assessment unit is greater than 50%, the surrounding rock in that area is judged to be of high damage level and has a high risk of rockburst.