Method for predicting outburst of coal mine underground driving working face

Abstract

The invention provides a coal mine underground driving face outburst prediction method. The coal mine underground driving face outburst prediction method comprises the steps that S1, outburst prediction drill holes are evenly formed in a driving face; s2, the transverse distance and the longitudinal distance of the outburst prediction drill holes are set; s3, setting the hole opening distance of the outburst prediction drill hole of the driving working face; s4, calculating the number of outburst predicted drill holes needing to be set; s5, calculating the volume of the coal body with the outburst risk tendency; s6, calculating the relative outburst strength of the outburst simulation test; s7, predicting the average outburst coal mass quality when coal and gas outburst occurs on the roadway driving face; and when the mass of the outburst coal body is smaller than the mass of the one-time blasting dropped coal, outburst prediction indexes are measured for the tunneling face construction outburst prediction drill hole. According to the method disclosed by the invention, the outburst prediction drill holes are uniformly distributed, so that the comprehensiveness and accuracy of prediction are ensured; by reasonably setting the hole opening distance, the driving working face continues to advance after a new round of outburst prediction, and the driving working face can enter an effective prediction zone formed by the new round of prediction.

Description

Technical Field

[0001] The invention relates to the field of coal mine underground outburst prediction and prevention, and in particular to a method for predicting outburst at an underground coal mine excavation working face. Background Art

[0002] As my country's basic energy source, coal's dominant position cannot be ignored for a long time. At present, more than 90% of my country's coal mining mines are underground mining. Coal and gas outburst dynamic disasters triggered during the mining process occur from time to time. Its long-term, complex and recurring nature significantly restricts the safe and efficient production of mines.

[0003] A large number of observations and studies at home and abroad have shown that in the coal seams at the sites of gas outbursts, there are soft layers with loose coal quality, disordered bedding, serious damage to the original structure, and layered or lens-shaped distribution. This kind of coal is usually called soft layered coal, and the softening of coal quality is a sign of gas outburst. The destruction of coal body structure is the product of strong structural compression and shear damage to the coal seam. Due to the imbalance of force size, scope of action and state of force, the natural layers of different ranges and thicknesses in the coal seam are deformed, losing the original homogeneous and clearly bedding banded structure, and forming broken particles or powdery structurally damaged coal, which is called tectonic coal.

[0004] With the normalization of deep mining, the number of mines with outbursts has increased year by year, and the prevention and control of outburst disasters and outburst prediction work has become more severe. At present, the layout mode of outburst prediction drilling holes in the excavation working face is generally to construct at least 2 to 3 prediction holes with a depth of 8 to 10 meters in coal seams with different inclinations, and the prediction holes are arranged in the soft layer as much as possible. One hole is located in the middle of the tunnel section and parallel to the tunnel excavation direction. The terminal points of other holes should be located 2-4 meters outside the contour lines on both sides of the tunnel section.

[0005] However, when the prediction index is used on site to predict the danger of outburst, it is still inevitable that an outburst accident will occur. When the range of tectonic movement is relatively small, such as the development of faults with a small drop, there will be no obvious soft stratification in the coal seam, but the tectonic soft coal produced will be present in the coal seam in the form of local "coal bags". This situation can be called the "local tectonic coal may exist in the hard coal seam" model. If the excavation of the working face does not expose this part of the coal body, it is difficult to ensure that the prediction borehole will be drilled into the coal body in this area when constructing the outburst prediction drilling hole, resulting in the final measured prediction index value not being able to truly reflect the level of outburst danger in the coal body of the working face. In many cases, it is because the borehole is not drilled in the coal body with outburst danger, the measured prediction index value is lower than the reference critical value, and a "low index outburst accident" occurs. Therefore, there is an urgent need for an outburst prediction method to determine the layout pattern of outburst prediction drilling holes and improve the accuracy of outburst prediction of underground excavation working faces. Summary of the invention

[0006] In order to solve the problems existing in the above-mentioned prior art, the present invention provides a method for predicting outburst in an underground coal mine excavation working face, which specifically includes the following technical solutions:

[0007] A method for predicting outburst in an underground coal mine excavation working face comprises the following steps:

[0008] S1, evenly distribute the predicted drilling holes on the excavation working face;

[0009] S2, collect the width data of the outburst holes of the tunnel excavation working face outburst accidents, set the horizontal spacing of the outburst prediction drilling holes; determine the vertical spacing of the outburst prediction drilling holes according to the minimum structural zone height exposed by the coal body;

[0010] S3, set the opening distance of the predicted drilling holes on the excavation working face to ≤ 0.5m;

[0011] S4, according to the actual area of ​​the tunnel excavation working face, based on the spacing of the predicted protrusion drilling holes and the opening distance obtained in steps S1-S3, the number of predicted protrusion drilling holes to be set is calculated by comparing the spacing and the opening distance.

[0012] S5, calculate the volume of coal body with a tendency to cause a dangerous outburst by the following formula, and obtain the maximum range of coal body with a tendency to cause a dangerous outburst at the excavation working face:

[0013]

[0014] In the formula,

[0015] V' is the volume of coal with outburst hazard tendency, m 3 ; h is the predicted excavation depth, m; S1 is the cross-sectional area close to the working face; S2 is the cross-sectional area close to the predicted bottom of the borehole, m 2 ;

[0016] S6, calculating the relative outburst strength of the outburst simulation test according to the outburst simulation test result, wherein the relative outburst strength refers to the ratio of the amount of coal thrown out in the outburst simulation test to the total amount of coal;

[0017] S7, the average outburst coal mass when coal and gas outburst occurs in the tunnel excavation working face is predicted by the following formula:

[0018] m'=ψm

[0019] In the formula,

[0020] n=ρV'

[0021] m' is the predicted coal outburst amount at the working face, kg; ψ is the relative outburst strength of the coal body, %;

[0022] m is the mass of coal with outburst danger tendency, kg; ρ is the apparent density of coal, kg / m 3 ; V' is the volume of coal with outburst danger tendency, m 3 ;

[0023] When the mass of the protruding coal body is less than the mass of coal dropped in one blasting, the outburst prediction index is determined for the outburst prediction drilling holes constructed on the tunnel excavation working face according to the "Detailed Rules for Preventing and Controlling Coal and Gas Outbursts" and the number of outburst prediction drilling holes determined in step S4.

[0024] Furthermore, the uniform distribution of the outburst prediction drill holes includes: the outburst prediction drill holes are arranged in the soft stratification area with coal and gas outburst indicators of the excavation working face, and are arranged in the non-outburst indicator area of ​​the excavation working face.

[0025] Furthermore, the number of samples of tunnel excavation face outburst accidents collected is ≥100, and includes outburst accidents in domestic and foreign coal mine tunnel excavation faces; a bar graph of the width of the outburst holes of the outburst accidents is made based on the collected samples, and the distribution data of the width of the outburst holes is obtained.

[0026] Furthermore, the lateral spacing of the prominent prediction boreholes is set to 4-6m.

[0027] Furthermore, under the upper limit of the hole opening distance of ≤0.5m, the hole opening distance of the outburst prediction drilling hole is accurately calculated by the following formula:

[0028]

[0029] In the formula,

[0030] l is the opening distance, m; x is the predicted advance distance, m; b is the sidewall control range, m; h is the predicted depth, m.

[0031] Furthermore, the opening angle of the prediction borehole is determined according to the inclination of the coal seam and the excavation direction.

[0032] Furthermore, according to the critical value of the initial released gas expansion energy, the coal and gas outburst intensity is divided into a weak outburst level and a strong outburst level; the outburst intensity of the weak outburst level is 42.98mJ / g~103.8mJ / g, and the outburst intensity of the strong outburst level is ≥103.8mJ / g.

[0033] Furthermore, the average values ​​of different relative prominence strengths under strong prominence level and weak prominence level are used to represent the relative prominence strength under different prominence levels.

[0034] Furthermore, the average relative protrusion strength of the weak protrusion is set to 22.79%, and the average relative protrusion strength of the strong protrusion is set to 63.28%.

[0035] Based on the above technical solution, the present invention has the following beneficial effects:

[0036] 1. The method for predicting outbursts recorded in the present invention arranges outburst prediction boreholes evenly in the coal mine underground excavation working face, thereby avoiding the previous practice of only considering the locations where outbursts may occur while ignoring the fact that obvious soft stratification may not be seen in all excavation working faces, thereby ensuring the comprehensiveness and uniformity of the prediction and improving the accuracy and coverage of the prediction.

[0037] 2. The method for predicting outbursts recorded in the present invention ensures that under different prediction conditions, the working face can continue to advance after a new round of outburst prediction by selecting a reasonable opening distance for the outburst prediction borehole, and when the advancement distance reaches the predicted advance distance left by the previous round of prediction, it can enter the effective prediction zone formed by the new round of prediction.

[0038] 3. The outburst prediction method described in the present invention can more accurately evaluate the outburst hazard of the excavation working face by calculating the average amount of outburst coal that may occur in the excavation working face under different outburst intensities and comparing it with the amount of coal dropped in one blasting. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 : Schematic diagram of the prediction method described in the present invention;

[0040] Figure 2 : Schematic diagram of the main view of the uniform arrangement of the predicted drilling holes on the excavation working face;

[0041] Figure 3 : Schematic diagram of top view of uniform arrangement of drilling holes for prediction of protrusion on excavation working face;

[0042] Figure 4 : Schematic diagram of the bar chart recording the width of the protruding hole in foreign protruding accidents;

[0043] Figure 5 : Schematic diagram of the bar chart recording the width of the protruding holes in domestic protruding accidents. DETAILED DESCRIPTION

[0044] It should be noted that:

[0045] 1. Certain words are used in the specification and claims to refer to specific components. Those skilled in the art should understand that technicians may use different nouns to refer to the same component. This specification and claims do not use the difference in nouns as a way to distinguish components, but use the difference in components' functions as the criterion for distinction.

[0046] 2. Unless otherwise defined, technical or scientific terms used in the present disclosure should have the common meanings understood by persons having ordinary skills in the field to which the present disclosure belongs.

[0047] The following is combined with Figure 1 To Attachment Figure 5 , the present invention is described in detail by way of embodiments.

[0048] A method for predicting outburst in an underground coal mine excavation working face comprises the following steps:

[0049] S1, arranging projection prediction drill holes on the excavation working face, wherein the projection prediction drill holes are evenly distributed on the excavation working face.

[0050] Uniform distribution of outburst prediction drill holes means that in addition to soft layers with coal and gas outburst indicators, outburst prediction drill holes are also set up in non-outburst indicator areas of the roadway.

[0051] Evenly distributing outburst prediction drill holes on the tunnel excavation working face can ensure the comprehensiveness and uniformity of coal and gas outburst prediction and improve the accuracy and coverage of the prediction.

[0052] S2, set the horizontal spacing and vertical spacing of the highlighted predicted drilling holes.

[0053] in,

[0054] The lateral spacing refers to the spacing between adjacent predicted drill holes in the horizontal plane, that is, along the direction of the coal seam strike;

[0055] Longitudinal spacing refers to the distance between adjacent predicted drill holes in the direction perpendicular to the direction of the coal seam.

[0056] Determine the lateral spacing of the projection prediction boreholes by following these steps:

[0057] S201. Collect data on tunnel excavation face outburst accidents occurring at home and abroad, wherein the data at least includes width data of the outburst hole after the outburst accident occurs.

[0058] In order to obtain more accurate data distribution patterns, the sample size of prominent accidents should be ≥ 100;

[0059] In addition, based on the technological differences in comprehensive mining operations in coal mines at home and abroad, the foreign sample data collected is set to ≥ 50 pieces, and the domestic sample data is set to ≥ 50 pieces, so as to obtain more scientific and rigorous statistical results.

[0060] This embodiment selected 367 prominent accidents, including 274 overseas and 93 domestic ones.

[0061] After the outburst accident occurs, the proportion of different outburst hole widths in the sample data is calculated with each meter as the statistical unit to obtain the distribution pattern of the outburst hole width.

[0062] Attached Figure 4 A bar chart showing the width of the protruding holes in foreign protruding accidents;

[0063] Attached Figure 5 A bar chart showing the record width of the protruding holes in domestic protruding accidents is shown.

[0064] S202. Analyzing the statistical data of step S2021, it can be seen that:

[0065] Among the 274 outbursts that occurred abroad, 89.05% of the outbursts had a width of less than 6m, and 76.64% of the outbursts had a width of less than 4m.

[0066] Among the 93 outbursts that occurred in China and formed prominent holes, 98.93% of the outbursts had a hole width of less than 6m, and 90.33% of the outbursts had a hole width of less than 4m.

[0067] Therefore, in this embodiment, the horizontal spacing of the outburst prediction boreholes is set to 4-6m, which can predict most of the dangerous coal bodies with outbursts. The vertical spacing is determined according to the minimum structural zone height of the coal body previously exposed.

[0068] S3, as a powerful barrier to relieve pressure and prevent the sudden exposure of potential coal bodies ahead, the predicted advance distance must ensure that when the working face advances to the end of the predicted advance distance formed by the previous round of prediction cycle, the working face should be in the effective prediction zone formed by the new round of prediction cycle, that is, the delayed safety effect of the predicted advance distance. Based on the delayed safety effect of the predicted advance distance, the opening distance of the predicted drilling hole of the excavation working face is set to ≤0.5m.

[0069] Under the upper limit of the hole distance of ≤0.5m, the hole distance of the prominent prediction drilling hole can be accurately calculated by the following formula:

[0070]

[0071] In the formula,

[0072] l is the opening distance, m; x is the predicted advance distance, m; b is the sidewall control range, m; h is the predicted depth, m.

[0073] Through the accurate calculation of the drilling opening distance of the predicted outburst through the above formula, it can be ensured that under different prediction conditions, the excavation working face will continue to advance after a new round of outburst prediction. When its advancement distance reaches the predicted advance distance left by the previous round of prediction, it can enter the effective prediction zone formed by the new round of prediction.

[0074] The opening angle of the predicted drilling hole is determined according to the inclination of the coal seam and the excavation direction, that is, the principle of drilling arrangement is to ensure that the borehole is arranged in the coal seam, and the inclination of the borehole is parallel to the bottom plate of the tunnel or inclined upward or downward according to the thickness of the coal seam.

[0075] S4, according to the actual area of ​​the tunnel excavation working face, based on the spacing of the predicted protrusion drilling holes and the opening distance obtained in step S1, the two are compared to calculate the number of predicted protrusion drilling holes that need to be set.

[0076] S5, calculate the volume of coal with a tendency to cause a dangerous outburst by the following formula, and evaluate the maximum range of coal with a tendency to cause a dangerous outburst at the excavation face:

[0077]

[0078] In the formula,

[0079] V' is the volume of coal with outburst hazard tendency, m 3 ; h is the predicted excavation depth, m; S1 is the cross-sectional area close to the working face; S2 is the cross-sectional area close to the predicted bottom of the borehole, m 2 .

[0080] The mass of coal with outburst hazard tendency is calculated by the following formula:

[0081] n=ρV'

[0082] In the formula,

[0083] m is the mass of coal with outburst danger tendency, kg; ρ is the apparent density of coal, kg / m 3 ; V' is the volume of coal with outburst danger tendency, m 3 .

[0084] S6. According to the critical value of the initial released gas expansion energy, the coal and gas outburst intensity is divided into weak outburst level and strong outburst level. Specifically, the outburst intensity of the weak outburst level is 42.98mJ / g~103.8mJ / g; the outburst intensity of the strong outburst level is ≥103.8mJ / g.

[0085] S601, Jiang Chenglin, Yu Qixiang, et al. "Spherical Shell Instability Mechanism and Prevention Technology of Coal and Gas Outburst" [M]. China University of Mining and Technology Press, 1998. In the fifth chapter of the experimental study of the "spherical shell instability" hypothesis, a detailed description of the outburst simulation test is recorded, including the outburst simulation device and simulation materials, the preparation and sampling of the outburst coal seam, the outburst simulation test, and the classification of the outburst simulation results. The results of 46 outburst simulation tests recorded in the literature are used to quantitatively analyze the on-site outburst strength and obtain the relative outburst strength of the 46 outburst tests. The relative outburst strength refers to the ratio of the amount of coal thrown out in the outburst simulation test to the total amount of coal.

[0086] For a single category of weak or strong prominence, the difference in relative prominence strength is small, so the average value of different relative prominence strengths under strong and weak prominence levels is selected to characterize the relative prominence strength under different prominence levels.

[0087] The calculation results in:

[0088] The average relative protrusion strength of weak protrusions is 22.79%;

[0089] The average relative protrusion strength of strong protrusion is 63.28%

[0090] S602: The relative protrusion strengths at different protrusion levels obtained in step S601 can accurately quantify the actual protrusion strengths at the production site. Therefore, according to the average relative protrusion strengths at the strong / weak protrusion levels and the mass of the dangerous coal body with protrusion obtained in step S5, the average mass of the protruding coal body when coal and gas protrusion may occur at the tunnel excavation working face at the strong / weak protrusion level is calculated by the following formula:

[0091] m'=ψm

[0092] In the formula,

[0093] m' is the predicted amount of coal outburst in the working face, kg; ψ is the relative outburst strength of the coal body, %; m is the amount of coal in the coal body with a tendency to cause outburst danger, kg.

[0094] S7, based on the average mass of coal body when coal and gas outburst may occur in the tunnel excavation working face under the strong / weak outburst level calculated in step S601, when the mass of the coal body is less than the mass of coal dropped in one blasting, determine the outburst prediction index for the outburst prediction drilling holes constructed for the tunnel excavation working face according to the "Detailed Rules for Prevention and Control of Coal and Gas Outburst" and the number of outburst prediction drilling holes determined in step S4.

[0095] By calculating the average amount of coal that may burst in the excavation face under different burst intensities and comparing it with the amount of coal dropped in a single blast, the danger of burst in the excavation face can be assessed more accurately.

[0096] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments, and the above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, and these changes and improvements all fall within the scope of the present invention to be protected.

Claims

1. A method for predicting outburst in an underground coal mine excavation working face, characterized in that: The following steps are involved: S1, evenly distribute the predicted drilling holes on the excavation working face; S2, collect the width data of the outburst holes of the tunnel excavation working face outburst accidents, set the horizontal spacing of the outburst prediction drilling holes; determine the vertical spacing of the outburst prediction drilling holes according to the minimum structural zone height exposed by the coal body; S3, set the opening distance of the predicted drilling holes on the excavation working face to ≤ 0.5m; S4, according to the actual area of ​​the tunnel excavation working face, based on the spacing of the predicted protrusion drilling holes and the opening distance obtained in steps S1-S3, the number of predicted protrusion drilling holes to be set is calculated by comparing the spacing and the opening distance. S5, calculate the volume of coal body with a tendency to cause a dangerous outburst by the following formula, and obtain the maximum range of coal body with a tendency to cause a dangerous outburst at the excavation working face: In the formula, V' is the volume of coal with outburst hazard tendency, m 3 ; h is the predicted excavation depth, m; S1 is the cross-sectional area close to the working face; S2 is the cross-sectional area close to the predicted bottom of the borehole, m 2 ; S6, calculating the relative outburst strength of the outburst simulation test according to the outburst simulation test result, wherein the relative outburst strength refers to the ratio of the amount of coal thrown out in the outburst simulation test to the total amount of coal; S7, the average outburst coal mass when coal and gas outburst occurs in the tunnel excavation working face is predicted by the following formula: m′=ψm In the formula, n=ρV' m' is the predicted coal outburst amount at the working face, kg; ψ is the relative outburst strength of the coal body, %; m is the mass of coal with outburst danger tendency, kg; ρ is the apparent density of coal, kg / m 3 ; V' is the volume of coal with outburst hazard tendency, m 3 ; When the mass of the protruding coal body is less than the mass of coal dropped in one blasting, the outburst prediction index is determined for the outburst prediction drilling holes constructed on the tunnel excavation working face according to the "Detailed Rules for Preventing and Controlling Coal and Gas Outbursts" and the number of outburst prediction drilling holes determined in step S4.

2. A method for predicting outburst in underground coal mine excavation working face according to claim 1, characterized in that: The uniform distribution of the outburst prediction drill holes includes: the outburst prediction drill holes are arranged in the soft layered area with coal and gas outburst indicators of the excavation working face, and are arranged in the non-outburst indicator area of ​​the excavation working face.

3. A method for predicting outburst in underground coal mine excavation working face according to claim 1, characterized in that: The number of samples of tunnel excavation face outburst accidents collected is ≥100, and includes outburst accidents in domestic and foreign coal mine tunnel excavation faces; a bar graph of the width of the outburst holes of the outburst accidents is made based on the collected samples, and the distribution data of the width of the outburst holes is obtained.

4. A method for predicting outburst in underground coal mine excavation working face according to claim 3, characterized in that: The lateral spacing of the prominent prediction boreholes is set to 4-6m.

5. A method for predicting outburst in underground coal mine excavation working face according to claim 1, characterized in that: Under the upper limit of the hole distance of ≤0.5m, the hole distance of the prominent prediction drilling hole can be accurately calculated by the following formula: In the formula, l is the opening distance, m; x is the predicted advance distance, m; b is the sidewall control range, m; h is the predicted depth, m.

6. A method for predicting outburst in underground coal mine excavation working face according to claim 5, characterized in that: The opening angle of the outburst prediction borehole is determined according to the coal seam inclination and the excavation direction.

7. A method for predicting outburst in underground coal mine excavation working face according to claim 1, characterized in that: According to the critical value of the initial released gas expansion energy, the coal and gas outburst intensity is divided into weak outburst level and strong outburst level; the outburst intensity of the weak outburst level is 42.98mJ / g~103.8mJ / g, and the outburst intensity of the strong outburst level is ≥103.8mJ / g.

8. A method for predicting outburst in underground coal mine excavation working face according to claim 7, characterized in that: The average values ​​of different relative prominence strengths under strong prominence level and weak prominence level are used to represent the relative prominence strength under different prominence levels.

9. A method for predicting outburst in underground coal mine excavation working face according to claim 8, characterized in that: The average relative protrusion strength of the weak protrusions is set to 22.79%, and the average relative protrusion strength of the strong protrusions is set to 63.28%.

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