Method for evaluating single coal seam in-seam pressure relief outburst prevention effect

Abstract

The application provides a single coal seam in-situ pressure relief outburst prevention effect evaluation method, clearly defines target observation values and influence factor values of pressure relief outburst prevention effect, determines positive and negative influence relations among the above factors; measures and collects related parameters and influence factor value data of in-situ pressure relief protective layer mining working face; sets boundary conditions, corrects target observation values, establishes a relation model between target observation values and influence factor values; adopts a grey relation method+non-quantitative dimensional expected interval method to clearly define corresponding relations of pressure relief outburst prevention effects and prediction target interval values of different in-situ pressure relief processes under different factors; performs inspection during working face recovery, updates and optimizes interval corresponding relations between target observation values and influence factor values; uses feedback of the recovery working face to correct the prediction model. Advantageous effects are that the application provides a prediction method and index for gas disaster control, reduces a passive situation of later production stoppage control, and ensures safety production of the mine.

Description

Technical Field

[0001] This invention relates to the field of underground coal mining technology, and more specifically, to a method for evaluating the effect of pressure relief and outburst prevention within a single coal seam. Background Technology

[0002] In-layer decompression protective layer mining technology refers to the process of removing coal at a fixed position (e.g., 1m above or 1m below) of the coal seam before mining, using methods such as hydraulic drilling or mechanical enlargement, thereby creating a decompression space similar to a mining protective layer.

[0003] The evaluation index for pressure relief and anti-outburst effect refers to a set of measurable, statistical, and quantifiable indicators that are selected and combined in a certain way to obtain the expected value. The result is then compared with the result of the interval corresponding to the expected value to evaluate whether the pressure relief and anti-outburst effect is good.

[0004] Although my country's current evaluation indicators for coal and gas outburst prevention and pressure relief are clearly stipulated in the "Detailed Rules for the Prevention and Control of Coal and Gas Outbursts," these indicators still have shortcomings such as limited pre-monitoring data, unclear comparative characteristics, and inability to effectively predict and implement targeted remediation in advance. This leads to situations where, during mining operations, if major indicators are within limits but minor indicators exceed limits, operations often need to be suspended and remediation intensified, resulting in production delays. Furthermore, the available measures are extremely limited (due to site constraints, bottom drainage roadways are often unsuitable for construction, and the available space for construction at the mining face is extremely limited), causing significant losses. Therefore, it is necessary to provide a reliable evaluation indicator and method for the effectiveness of pressure relief and outburst prevention within a single coal seam in advance. This would allow for the prediction of outburst prevention and pressure relief effects at the working face before mining operations, and the implementation of intensified remediation measures for locations that fail to meet the predictions, eliminating the passive situation of production shutdowns due to exceeding limits for indicators or return air gas during mining operations. Summary of the Invention

[0005] This invention addresses at least one of the aforementioned technical problems and proposes a method for evaluating the effectiveness of pressure relief and outburst prevention within a single coal seam in order to predict in advance whether the working face to be mined will achieve the goal of pressure relief and outburst prevention. This method can predict the pressure relief and outburst prevention effect of the working face before mining operations begin and provide a conclusion on the treatment effect based on the provided quantified expected range, thereby guiding the next stage of mine production and eliminating the impact of conventional monitoring and post-production remediation.

[0006] A method for evaluating the effect of intra-seam pressure relief and outburst prevention in a single coal seam, comprising the following steps:

[0007] S1. Determine the target observation value and influencing factor value that affect the pressure relief and anti-outburst effect, and determine the positive and negative influence relationship between the above factors;

[0008] S2. Measure and collect relevant parameters and influencing factor values ​​for the mining face of the pressure relief protective layer within the layer;

[0009] S3. Set boundary conditions, correct target values, and establish a relationship model between target values ​​and influencing factor values;

[0010] S4. The grey relational analysis method and the non-dimensional expected interval method are used to determine the pressure relief and anti-outburst effect of different layers under different conditions, geological and technological factors and the corresponding relationship between the predicted target interval values ​​of safe mining of the working face.

[0011] S5. During the longwall mining period, the target values ​​and influencing factor values ​​are examined, and the interval correspondence between the target values ​​and influencing factor values ​​is continuously updated and optimized.

[0012] S6. Based on the feedback of the target observation value and influencing factor value of the longwall face in step S5, revise the relationship model between the target observation value and the influencing factor value.

[0013] More preferably, in step S1, the influencing factor values ​​include: the average density of the original coal body, the average density of the coal body after depressurization, the average original gas pressure and content of the coal body, the average nozzle diameter and flushing pressure used in the perforation depressurization process, the cumulative amount of coal flushed out by the perforation process and the overall coal reserves within the control range, the cumulative flushing time of the perforation, the average f-value of the coal, the average thickness of the coal, the evaluation horizontal distance between the perforation depressurization location and the borehole opening, and the perforation qualification rate of the perforation within the block; the average f-value of the coal refers to the hardness of the coal, which is a dimensionless unit;

[0014] The target values ​​include residual gas content and pressure, outburst risk prediction indicators for the working face, and whether outburst signs occur during mining; the outburst risk prediction indicators for the working face include drill cuttings volume S value, borehole gas emission initial velocity q, drill cuttings desorption index Δh2, and K1;

[0015] Where Δh2 refers to the pressure difference generated by gas desorption at the 4th and 5th minutes after a coal sample (10g) is exposed to the atmosphere from the coal body, and the unit is Pa; K1 refers to the amount of gas desorption per unit weight of coal sample in the 1st minute after it is exposed to the atmosphere from the coal body, and the unit is ml / g.min1 / 2; and the amount of drill cuttings S refers to the weight of coal dust discharged per meter of borehole when the drill cuttings index method is used to detect the risk of coal seam outburst, and the unit is kg / m.

[0016] The influencing factor values ​​and target observation values ​​are all statistical values ​​collected from a certain block of the working face. The block is divided into rectangles with a length and width of 30m×30m to 40m×40m.

[0017] More preferably, in step S1, the positive or negative relationship between the influencing factor value and the target observation value is to see whether the influencing factor is beneficial to the pressure relief and anti-outburst effect; if beneficial, it is +, which is considered a positive influence, and if unfavorable, it is -, which is considered a negative influence.

[0018] More preferably, in step S3, the boundary conditions refer to: 1. There is a pressure relief zone in the excavated roadway or the mined working face. The pressure relief zone can be determined by actual measurement or by referring to the table in the "Method for Predicting Mine Gas Outbursts"; 2. If any indicator in the target observation value exceeds the critical value, it is considered as failing the pressure relief and outburst prevention measures; 3. If any outburst warning occurs during tunneling or mining in the block, it is considered as exceeding the critical value and failing the measures, which is also considered as failing the pressure relief and outburst prevention measures.

[0019] More preferably, in step S3, the correction target value is the percentage of the actual measured data to the critical value specified in the "Detailed Rules for the Prevention and Control of Coal and Gas Outbursts," and the correction target value includes:

[0020] Drill cuttings volume S-value percentage: η s = (100 × measured S value / 6)%

[0021] Percentage of initial gas emission velocity q from borehole: η q = (100 × measured q value / 5)%

[0022] Percentage of drill cuttings desorption index Δh2: η △h2 = (100 × measured Δb² value / 200)%

[0023] Drill cuttings desorption index K1 percentage:

[0024] Percentage of critical residual gas content: η Q = (100 × measured residual gas content / 6.0)%

[0025] Percentage of residual gas pressure critical value: η P = (100 × measured residual gas pressure / 0.6)%

[0026] The effectiveness of pressure relief and anti-outburst measures is determined by the percentage of the critical value.

[0027] More preferably, in step S4, the grey relational method + non-dimensional expectation interval means that the grey relational degree is used as the influence weight of each factor, and the expectation is calculated with positive and negative relationships, so that the expected calculation value interval corresponds to the target value. The interval value that conforms to a large amount of data is regarded as the corresponding interval between the target and the influencing factors.

[0028] Includes the following steps:

[0029] S4.1 Before drilling in the block, use cross-layer drilling to determine the original gas content, original gas pressure, original coal density, average coal thickness in the block, coal reserves in the block, and coal gas reserves in the block.

[0030] Use the cross-intersection method to determine the center point of the block and the average distance from the borehole opening of the central bottom extraction roadway. Simultaneously, fill in the relevant indicator data according to the table below:

[0031] Factors and target values Block 1 Block 2 Block 3 ...... Block N <![CDATA[Gas content (m 3 / t)]]> Gas pressure (MPa) <![CDATA[Original density of coal mass (t / m 3 )]]> Average coal thickness (m) Coal reserves (t) <![CDATA[Gas reserve (m 3 )]]> Average distance (m) between pressure relief location and orifice <![CDATA[Coal density after pressure relief (t / m 3 )]]> Nozzle diameter (mm) Coal flushing pressure (MPa) Cumulative coal consumption (t) Cumulative coal flushing time (h) Average f-value Punching pass rate (%) Residual gas content or maximum pressure percentage (%) Maximum percentage value of the forecast indicator (%) Number of prominent signs during mining ;

[0033] S4.2. Construct three 15×N matrices from the data in the table above. Matrix A is the statistical table of influencing factors + the maximum percentage value of residual gas content or pressure. Matrix B is the statistical table of influencing factors + the maximum percentage value of the prediction index. Matrix C is the statistical table of influencing factors + whether there are any signs of an outburst during mining.

[0034] Let Ain be the i-th row and n-th column of matrix A, Bin be the i-th row and n-th column of matrix B, and Cin be the i-th row and n-th column of matrix C.

[0035] S4.3. According to the grey relational analysis method, matrix A is processed to be dimensionless. The calculation formula is as follows:

[0036] Ain / =Ain / Ai1 (i=1,2,3,4,…..,14,15) The data in each row is divided by the first data in that row to perform dimensionless processing;

[0037] S4.4. Process the dimensionless data using the grey relational analysis method and calculate the correlation degree ρi (i = 1, 2, 3, ..., 14) of each factor.

[0038] S4.5 Calculate the expected value of the maximum percentage of gas content or pressure in the nth block:

[0039]

[0040] The maximum percentage of gas content or pressure in the nth block is correlated with the predicted maximum percentage of gas content or pressure in that block, and the expected value range within 100% and the expected value range outside 100% are divided.

[0041] After dimensionless processing of parameters for other new blocks, the expected value is calculated by multiplying the obtained correlation degree ρi and summing the results. Then, the expected range is compared to determine whether the gas content or pressure of the new block meets the standard (a percentage value within 100% is considered as a test of the effectiveness of the anti-outburst measures).

[0042] Similarly, the maximum percentage expected value of the predicted index for the nth block is correlated with the predicted maximum gas content or pressure percentage within that block, dividing the expected value range into those within 100% and those outside. The expected value is calculated by multiplying the parameters of other new blocks (after dimensionless processing) with the obtained correlation degree ρi, and then comparing the expected value ranges to determine whether the predicted index of the new block meets the standard (a percentage value within 100% is considered as meeting the standard for pressure relief and gas suppression).

[0043] Similarly, the maximum percentage expected value of the prediction index for the nth block is obtained and correlated with whether a prominent omens are predicted to occur within that block, and the above processing is performed.

[0044] Beneficial Effects: This invention first establishes the factors that significantly affect the pressure relief effect as target values, and then identifies factors closely related to these target values ​​as influencing factors. Next, by collecting parameters before and during the construction of anti-outburst measures in the pressure relief protection layer area, these parameters are used to establish a corresponding numerical interval table between the influencing factors and the target values ​​using a grey relational analysis method combined with a weighted expectation method. The influencing factors of the working face block to be predicted and assessed are then dimensionless and substituted into the weighted expectation method for calculation. The calculated expected values ​​are compared with the established numerical interval table to determine the pressure relief and anti-outburst effect of the block to be assessed, and to guide whether the mine needs to implement enhanced control measures in advance. This invention provides a method and indicators for advanced prediction of gas disaster management in mines, reducing the passive situation of subsequent shutdowns for remediation and ensuring safe production in the mine.

[0045] By employing the grey relational analysis method combined with the weighted expectation method, a corresponding numerical interval table is established between influencing factors and target values. The influencing factors of the working face block to be predicted and assessed are then dimensionless and substituted into the weighted expectation method for calculation. The calculated expected values ​​are compared with the established numerical interval table to determine the pressure relief and outburst prevention effect of the block under assessment, guiding whether the mine needs to implement enhanced control measures in advance. This technology provides an advanced prediction method and indicators for mine gas disaster management, reducing the passive situation of subsequent production shutdowns and ensuring safe production in the mine. Attached Figure Description

[0046] Figure 1 A flowchart of the present invention is shown;

[0047] Figure 2 An example diagram of the block division of the present invention is shown. Detailed Implementation

[0048] To better understand the above-mentioned objectives, features, and advantages of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be noted that, unless otherwise specified, the embodiments and features described in these embodiments can be combined with each other.

[0049] A method for evaluating the effect of intra-seam pressure relief and outburst prevention in a single coal seam, comprising the following steps:

[0050] S1. Determine the target observation value and influencing factor value that affect the pressure relief and anti-outburst effect, and determine the positive and negative influence relationship between the above factors;

[0051] S2. Measure and collect relevant parameters and influencing factor values ​​for the mining face of the pressure relief protective layer within the layer;

[0052] S3. Set boundary conditions, correct target values, and establish a relationship model between target values ​​and influencing factor values;

[0053] S4. The grey relational analysis method and the non-dimensional expected interval method are used to determine the pressure relief and anti-outburst effect of different layers under different conditions, geological and technological factors and the corresponding relationship between the predicted target interval values ​​of safe mining of the working face.

[0054] S5. During the longwall mining period, the target values ​​and influencing factor values ​​are examined, and the interval correspondence between the target values ​​and influencing factor values ​​is continuously updated and optimized.

[0055] S6. Based on the feedback of the target observation value and influencing factor value of the longwall face in step S5, revise the relationship model between the target observation value and the influencing factor value.

[0056] In step S1, the influencing factors include: the average density of the original coal body, the average density of the coal body after depressurization, the average original gas pressure and content of the coal body, the average nozzle diameter and flushing pressure used in the perforation depressurization process, the cumulative amount of coal flushed out by the perforation process and the overall coal reserves within the control range, the cumulative flushing time of the perforation, the average f-value of the coal, the average thickness of the coal, the evaluation horizontal distance between the perforation depressurization location and the borehole opening, and the perforation qualification rate of the perforation within the block; the average f-value of the coal refers to the hardness of the coal, which is a dimensionless unit;

[0057] The target values ​​include residual gas content and pressure, outburst risk prediction indicators for the working face, and whether outburst signs occur during mining. Outburst risk prediction indicators for the working face include drill cuttings volume S value, initial gas emission velocity q, drill cuttings desorption index Δh2, and K1.

[0058] Where Δh2 refers to the pressure difference generated by gas desorption at the 4th and 5th minutes after a coal sample (10g) is exposed to the atmosphere from the coal body, and the unit is Pa; K1 refers to the amount of gas desorption per unit weight of coal sample in the first minute after it is exposed to the atmosphere from the coal body, and the unit is ml / g.minl / 2; drill cuttings amount S refers to the weight of coal dust discharged per meter of borehole when the drill cuttings index method is used to detect the risk of coal seam outburst, and the unit is kg / m;

[0059] The influencing factor values ​​and target observation values ​​are all statistical values ​​collected from a certain block of the working face. The block is divided into rectangles with a length and width of 30m×30m to 40m×40m.

[0060] In step S1, the positive or negative relationship between the influencing factor value and the target value is to see whether the influencing factor is beneficial to the pressure relief and anti-outburst effect; if it is beneficial, it is +, which is considered a positive influence, and if it is unfavorable, it is -, which is considered a negative influence.

[0061] In step S3, the boundary conditions refer to: 1. If there is a pressure relief zone in the excavated roadway or the mined working face, the pressure relief zone can be determined by actual measurement or by referring to the table in the "Method for Predicting Mine Gas Outbursts"; 2. If any index in the target observation value exceeds the critical value, it is considered as failing the pressure relief and outburst prevention measures; 3. If any outburst precursor occurs during tunneling or mining in the block, it is considered as exceeding the critical value and failing the measures, which is also considered as failing the pressure relief and outburst prevention measures.

[0062] In step S3, the correction target value is the percentage of the actual measured data to the critical value specified in the "Detailed Rules for the Prevention and Control of Coal and Gas Outbursts". The correction target value includes:

[0063] Drill cuttings volume S-value percentage: η s = (100 × measured s value / 6)%

[0064] Percentage of initial gas emission velocity q from borehole: η q = (100 × measured q value / 5)%

[0065] Percentage of drill cuttings desorption index Δh2: η △h2 = (100 × measured Δ) h2 value / 200)%

[0066] Drill cuttings desorption index K1 percentage:

[0067] Percentage of critical residual gas content: η Q = (100 × measured residual gas content / 60)%

[0068] Percentage of residual gas pressure critical value: η P = (100 × measured residual gas pressure / 0.6)%

[0069] The effectiveness of pressure relief and anti-outburst measures is determined by the percentage of the critical value.

[0070] Example 1

[0071] The grey relational method combined with the non-dimensional expected range refers to using the grey relational degree as the influence weight of each factor, and using positive and negative relationships to calculate the expected value range so that the expected value range corresponds to the target value. The range value that matches a large amount of data is regarded as the corresponding range between the target and the influencing factors.

[0072] The influence of influencing factors on the target predicted value was classified by sign. Among them, nozzle diameter, coal flushing pressure, cumulative coal flushing amount, cumulative coal flushing time, average f value, and punching qualification rate were all negatively correlated with the predicted target value.

[0073] The collected and processed data yielded the following table:

[0074] Factors and target values Block 1 Block 8 Block 15 Block 22 Block 29 <![CDATA[Gas content (m 3 / t)]]> 8.5 10.2 11.5 9.8 7.2 Gas pressure (MPa) 0.63 0.69 0.75 0.67 0.44 <![CDATA[Original density of coal mass (t / m 3 )]]> 1.49 1.49 1.49 1.49 1.49 Average coal thickness (m) 5 6 7 5 3 Coal reserves (t) 11175 13410 15645 11175 6705 <![CDATA[Gas reserve (m 3 )]]> 94987.5 136782 179917.5 109515 48276 Average distance (m) between pressure relief location and orifice 10 18 50 20 3 <![CDATA[Coal density after pressure relief (t / m 3 )]]> 1.43 1.45 1.47 1.45 1.42 Nozzle diameter (mm) 3 5 5 5 3 Coal flushing pressure (MPa) 8 8 12 10 8 Cumulative coal consumption (t) 338 402 445 350 361 Cumulative coal flushing time (h) 423 513 561 451 453 Average f-value 0.17 0.18 0.27 0.25 0.2 Punching pass rate (%) 100 99 93 97 100 Residual gas content or maximum pressure percentage (%) 95 103 112 92 83 Maximum percentage value of the forecast indicator (%) 90 98 189 87 80 Number of prominent signs during mining 0 0 1 0 0

[0075] The table above can be split into three matrices, as follows:

[0076]

[0077] matrix

[0078] matrix The following calculation example uses matrix A as an example:

[0079] After dimensionless processing using the grey relational analysis method, matrix A is obtained as follows:

[0080] matrix

[0081] Let matrix A / Using the average value of each column as reference data, the following columns are obtained:

[0082] {1.0000, 1.2101, 1.5848, 1.1874, 0.8491}

[0083] Let matrix A / Subtract the row value from the row value in the reference data for each row in the matrix, and take the absolute value to form a matrix |A / As follows:

[0084] matrix

[0085] The matrix correlation coefficient is obtained using the formula calculated by the grey relational analysis method:

[0086] Incidence matrix = (matrix | A) / |Minimum value in each row + 0.5 * matrix|A / |Maximum value) / (Matrix|A) / |Numerical value + ρ*matrix|A / |Maximum value), the following correlation matrix is ​​obtained:

[0087]

[0088] The average value of each row in the correlation matrix is ​​the absolute value of the weight of each influencing factor, as follows:

[0089] {0.9707, 0.9201, 0.8910, 0.9341, 0.9341, 0.9084, 0.7022, 0.8962, 0.8886, 0.9453, 0.9314, 0.9371, 0.9227, 0.8829, 0.9223}.

[0090] The last value, 0.9223, represents the residual content and pressure value.

[0091] Therefore, the weights for the following factors are: original gas content (0.9707), original gas pressure (0.9201), original coal density (0.8910), average coal thickness (0.9341), coal reserves (0.9341), gas reserves (0.9084), average distance between depressurization location and orifice (0.7022), coal density after depressurization (0.8962), nozzle diameter (0.8886), flushing pressure (0.9453), cumulative flushing amount (0.9314), cumulative flushing time (0.9371), average f-value (0.9227), and orifice pass rate (0.8829).

[0092] Take the weight of each factor and use the calculation formula The following table shows the expected value and the range of the maximum percentage of residual gas content or pressure calculated from the dimensionless matrix A / (since the bottom row contains data from the predicted target value, it is not included in the calculation) in the current statistical data:

[0093] Content pressure percentage Expected value 95 1.6488 103 2.2645643 112 4.4132522 92 1.3777698 83 -0.761573

[0094] Based on the calculated range values, it can be concluded that when the expected value exceeds 1.6488, it indicates that the residual gas content or pressure of the evaluated block exceeds the critical value, and intensive treatment is required.

[0095] As the amount of data increases, the above process is repeated continuously to refine and correct the predicted interval values.

[0096] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for evaluating the outburst prevention effect of single coal seam in-situ pressure relief, characterized in that, The steps are: S1, determining the target observation value and the influence factor value affecting the pressure relief and outburst prevention effect, and determining the positive and negative influence relationship between the above factors; S2, measuring and collecting the related parameters and influence factor value data of the pressure relief protection layer mining face in the layer; S3, setting boundary conditions, correcting the target observation value, and establishing the relationship model between the target observation value and the influence factor value; S4, using the grey correlation method + non-quantitative dimensional expected interval method to determine the corresponding relationship of the pressure relief and outburst prevention effect and the working face safety mining prediction target interval value of different layer pressure relief methods under different geological and method factors; S5, testing the target observation value and the influence factor value during the mining of the mining face, and continuously updating and optimizing the interval corresponding relationship between the target observation value and the influence factor value; S6, according to the feedback of the target observation value and the influence factor value of the mining face in step S5, correcting the relationship model between the target observation value and the influence factor value; In step S3, the corrected target observation value is the percentage of the actual measured data and the critical value specified in the "Coal and Gas Outburst Prevention Regulations", and the corrected target observation value includes: Drilling cuttings amount S value percentage: ηs=(100×measured S value / 6)%; Drilling gas emission initial velocity q value percentage: ηq=(100×measured q value / 5)%; Drilling cuttings desorption index Δh2 value percentage: ηΔh2=(100×measured Δh2 value / 200)%; Drilling cuttings desorption index K1 percentage: ηk1=(100×measured K1 value / 0.5)%; Residual gas content critical value Q percentage: ηQ=(100×measured residual gas content value / 6.0)%; Residual gas pressure critical value P percentage: ηP=(100×measured residual gas pressure value / 0.6)%; Determine the advantages and disadvantages of the pressure relief and outburst prevention effect by the percentage of the critical value; In step S4, the grey correlation method + non-quantitative dimensional expected interval method refers to using the grey correlation degree as the influence weight of each factor, and performing expected calculation with positive and negative relationships, so that the expected calculation value interval corresponds to the target observation value, and the interval value meeting a large amount of data is regarded as the corresponding interval of the target observation and the influence factor; including the following steps: S4.1, before the construction of the block drilling, the original gas content, the original gas pressure, the original coal density, the average thickness of the coal body in the block, the coal body reserves in the block, and the coal body gas reserves in the block are measured by the through layer drilling; the center point of the block and the average distance from the middle bottom drainage roadway drilling opening are determined by the cross method, and the following index data of block 1 to block N are also counted: Gas content m3 / t, gas pressure MPa, original density of coal t / m3, average coal thickness m, coal reserves t, gas reserves m 3 , average distance between pressure relief position and orifice m, density of coal after pressure relief t / m3, nozzle diameter mm, coal flushing pressure MPa, cumulative coal flushing volume t, cumulative coal flushing time h, average f value, coal flushing qualified rate (%), maximum percentage value of residual gas content or pressure (%), maximum percentage value of prediction index (%), number of times of occurrence of outburst precursors during mining S4.2, count the data of each block and establish three 15×N matrices, matrix A is the influence factor statistical table + residual gas content or pressure maximum percentage value, matrix B is the influence factor statistical table + prediction index maximum percentage value, and matrix C is the influence factor statistical table + whether outburst precursors occur during mining; the i-th row and n-th column in matrix A is expressed as Ain, the i-th row and n-th column in matrix B is expressed as Bin, and the i-th row and n-th column in matrix C is expressed as Cin. S4.3, according to the grey correlation method, non-dimensional processing is performed on the matrix A, and the calculation formula is: Ain' = Ain / Ai1(i = 1, 2, 3, 4, 14, 15) the data of each row is divided by the first data of the row to perform non-dimensional processing; S4.4, the data processed by non-dimensional processing is processed by the flow of the grey correlation method, and the correlation degree ρi(i = 1, 2, 3, 14) of each factor is obtained; S4.5, the maximum percentage value expectation of the nth block gas content or pressure is obtained: The maximum percentage value expectation of the nth block gas content or pressure obtained is correspondingly associated with the predicted maximum gas content or pressure percentage in the block, and the expectation value interval within 100% and outside the expectation value interval are divided; after the implementation parameters of other new blocks are processed by non-dimensionalization, the correlation degree ρi obtained is multiplied and summed to calculate the expectation, and then the expectation interval is compared, so as to judge whether the gas content or pressure of the new block meets the standard, and the percentage value within 100% is regarded as the effect test of the outburst prevention measure; Similarly, the maximum percentage value expectation of the nth block predicted index is correspondingly associated with the predicted maximum gas content or pressure percentage in the block, and the expectation value interval within 100% and outside the expectation value interval are divided; after the implementation parameters of other new blocks are processed by non-dimensionalization, the correlation degree ρi obtained is multiplied and summed to calculate the expectation, and then the expectation interval is compared, so as to judge whether the predicted index of the new block meets the standard, and the percentage value within 100% is regarded as the effect test of the outburst prevention measure; Similarly, the maximum percentage value expectation of the nth block predicted index is correspondingly associated with the predicted maximum gas content or pressure percentage in the block, and the expectation value interval within 100% and outside the expectation value interval are divided; after the implementation parameters of other new blocks are processed by non-dimensionalization, the correlation degree ρi obtained is multiplied and summed to calculate the expectation, and then the expectation interval is compared, so as to judge whether the predicted index of the new block meets the standard, and the percentage value within 100% is regarded as the effect test of the outburst prevention measure; 2. The method for evaluating the outburst prevention effect of in-seam pressure relief in a single coal seam according to claim 1, characterized in that, Similarly, the maximum percentage value expectation of the nth block predicted index is correspondingly associated with the predicted maximum gas content or pressure percentage in the block, and the expectation value interval within 100% and outside the expectation value interval are divided; after the implementation parameters of other new blocks are processed by non-dimensionalization, the correlation degree ρi obtained is multiplied and summed to calculate the expectation, and then the expectation interval is compared, so as to judge whether the predicted index of the new block meets the standard, and the percentage value within 100% is regarded as the effect test of the outburst prevention measure; The influence factor values in step S1 include: the average density of the original coal body, the average density of the coal body after pressure relief, the average original gas pressure and content of the coal body, the average nozzle diameter and the coal punching pressure used in the punching pressure relief method, the cumulative coal punching amount and the overall coal body reserves in the control range of the drilling hole used in the pressure relief method, the cumulative coal punching time of the drilling hole, the average f value of the coal, the average thickness of the coal, the evaluation horizontal distance of the coal punching pressure relief position and the hole, and the drilling hole punching qualification rate in the block; the average f value of the coal refers to the hardness of the coal, which is a non-dimensional unit; The target observation values include residual gas content and pressure, working face outburst danger prediction index, and whether outburst precursor occurs during mining; the working face outburst danger prediction index includes drilling cuttings amount S value, drilling gas emission initial speed q, drilling cuttings desorption index Δh2, and K1; Wherein, Δh2 refers to the pressure difference generated by gas desorption of 10g coal sample exposed to the atmosphere for 4 minutes and 5 minutes, and the unit is Pa; K1 refers to the gas desorption amount of unit weight coal sample exposed to the atmosphere within 1 min, and the unit is ml / g.min1 / 2; the drilling cuttings amount S value is the drilling cuttings amount per meter when the drilling cuttings index method is used to detect the coal seam outburst danger, and the unit is kg / m; The influence factor value and the target investigation value are values of a certain block of the working face as a unit for statistics. The block unit is divided into a rectangle with a length of 30 m to 40 m and a width of 30 m to 40 m.

3. The method for evaluating the outburst prevention effect of in-seam pressure relief in a single coal seam according to claim 1, characterized in that, In step S1, the positive and negative relationship of the influence factor value and the target investigation value is whether the influence factor is beneficial to pressure relief and outburst prevention; + is beneficial, which is regarded as a positive influence, and - is not beneficial, which is regarded as a negative influence.

4. The method for evaluating the outburst prevention effect of in-seam pressure relief in a single coal seam according to claim 1, characterized in that, In step S3, the boundary condition refers to:

1. There is a pressure relief area in the excavated roadway or the mined working face, which can be measured or inquired according to the table in the "Mine Gas Emission Prediction Method"; 2. If any index in the target investigation value exceeds the critical value, it is regarded as not meeting the standard, which is regarded as the failure of the pressure relief and outburst prevention measures; 3. If any outburst precursor appears during the excavation or mining in the block, it is regarded as exceeding the critical value and not meeting the standard, which is regarded as the failure of the pressure relief and outburst prevention measures.

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