Pressure relief effect investigation drill hole arrangement method for coal seam group protective layer mining

Abstract

The invention relates to a pressure relief effect investigation drill hole arrangement method for coal seam group protective layer mining, which mainly comprises the following steps of: firstly, determining a theoretical calculation pressure relief angle of an investigation area through theoretical analysis; secondly, a numerical value is obtained through numerical simulation, and a pressure relief angle is calculated; and determining a reference pressure relief angle of on-site investigation drilling design by combining the two, setting investigation drilling design parameters according to the reference pressure relief angle, and drawing a construction drawing. The method solves the problem that in the prior art, the design of the protective layer mining inspection drill hole is unreasonable. A reference pressure relief angle is determined by establishing a pressure relief angle theoretical model under the coal seam dip angle and protective layer mining condition and numerical simulation calculation, and accurate design of one coal seam and one pressure relief reference angle is achieved. According to the method, the arrangement quality of the protective layer effect investigation drill holes is improved, the delineation error of the pressure relief range under the protective layer mining condition is remarkably reduced, scientific guidance is provided for mine excavation deployment, and high-yield and high-efficiency development of a mine is promoted.

Description

Technical Field

[0001] The present invention belongs to the field of coal mine gas prevention and control, and particularly relates to a method for arranging inspection boreholes for the pressure relief effect of protective seam group mining. Technical Background

[0002] The mining of protective seams is the preferred regional outburst prevention measure for gas disaster control in outburst mines. Article 61 of Section 3, Chapter 3 of the Detailed Rules for the Prevention and Control of Coal and Gas Outbursts clearly states that in outburst-prone areas where the conditions for mining protective seams are available, protective seams must be mined, and reference values for pressure relief angles at different coal seam dips are given in Appendix E. During the mining of close-distance coal seam groups, due to the large differences in the geological occurrence conditions of each coal seam, there must be certain differences in their pressure relief angles. However, currently, for the design of on-site inspection boreholes, only the values in Appendix E of the Detailed Rules for the Prevention and Control of Coal and Gas Outbursts are simply referred to according to the dip of the coal seam to guide the design of on-site inspection boreholes, completely ignoring the actual occurrence conditions of the coal seam under the condition of protective seam mining, resulting in a large error in the delineation of the on-site protection range. When the coal seam spacing is small, it often leads to a small design value of the inspection borehole, and often all inspection boreholes are found to be effective, ultimately resulting in an overly conservative determination of the on-site protective seam inspection effect range; when the coal seam spacing is large, it often leads to a large design value of the inspection borehole, and there may be a pressure relief blind area when determining the final protection area. When the working face advances to the pressure relief blind area during the mining of the protected coal seam, coal and gas outburst disasters are extremely likely to occur, seriously affecting the mining deployment and high-yield and high-efficiency development of the mine.

[0003] In summary, in view of the current status of the inspection of the pressure relief effect of protective seam mining, it is necessary to scientifically and reasonably design the inspection boreholes for the pressure relief effect of protective seam mining. Summary of the Invention

[0004] In order to solve the technical problem of the unreasonable design of the inspection boreholes for protective seam mining, the present invention provides a method for arranging inspection boreholes for the pressure relief effect of protective seam group mining.

[0005] The technical solution adopted by the present invention is: a method for arranging inspection boreholes for the pressure relief effect of protective seam group mining, including the following steps:

[0006] Step S1: Determine the theoretically calculated pressure relief angle of the inspection area by using the theoretical analysis method;

[0007] Step S2: Determine the numerically calculated pressure relief angle of the inspection area by using the numerical simulation method;

[0008] Step S3: Finally determine the reference pressure relief angle for the design of on-site inspection boreholes according to the calculation results of Step S1 and Step S2;

[0009] Step S4: Determine the design parameters of the inspection boreholes and draw the on-site inspection construction drawings.

[0010] Further, in step S1, determining the theoretical calculated pressure relief angle includes the following steps:

[0011] Step S11: Determine the coal seam dip angle of 40° as the demarcation point;

[0012] Step S12: Taking the coal seam dip angle of 40° as the demarcation point, analyze the variation law of the dip pressure relief angle under different dip angle conditions by means of piecewise fitting, and then obtain the dip pressure relief angle calculation model under different dip angle conditions and different mining conditions;

[0013] When the coal seam dip angle ≤ 40°, the theoretical dip reference pressure relief angle is taken according to the following formula:

[0014]

[0015] When the coal seam dip angle > 40°, the theoretical dip reference pressure relief angle is taken according to the following formula:

[0016]

[0017] Step S13: Collect the coal seam occurrence characteristics of the test area, including the basic parameters and variation laws of the coal seam dip angle, coal seam thickness, and coal seam burial depth;

[0018] Step S14: Determine the coal seam dip angle parameter of the test area;

[0019] Step S15: Substitute the coal seam dip angle parameter obtained in step S14 into the dip pressure relief angle calculation model under different dip angle conditions and different mining conditions constructed in step S12, and calculate the theoretical dip pressure relief angle of the inspection area;

[0020] Step S16: According to the coal seam occurrence characteristics obtained in step S13, further determine the theoretical strike pressure relief angle of the inspection area (generally taking values of 56° - 60°);

[0021] Step S17: According to the relevant results of step S15 and step S16, finally determine the theoretical calculated pressure relief angle;

[0022] Further, in step S2, determining the numerical calculated pressure relief angle includes the following steps:

[0023] Step S21: Collect relevant data of the test strata, including the comprehensive stratigraphic columnar section of the test area, the occurrence of coal and rock strata, and the burial depth;

[0024] Step S22: Collect the physical and mechanical parameters of the coal and rock strata in the test area, including cohesion, internal friction angle, elastic modulus, Poisson's ratio, and density;

[0025] Step S23: Construct a three-dimensional geological calculation geometric model of the test area by using relevant numerical simulation software based on the relevant results of Step S21 and Step S22;

[0026] Step S24: Carry out numerical simulation calculations under the condition of protective layer mining by using the three-dimensional geological calculation geometric model constructed in Step S23, and obtain the stress change law, displacement change law and strain change law of each protected coal seam under the condition of protective layer mining;

[0027] Step S25: Determine the numerical calculation pressure relief angle according to the relevant results of Step S24 and in combination with the relevant regulations of national and local laws, regulations and documents;

[0028] Furthermore, in Step S3, determining the reference pressure relief angle for the on-site inspection borehole design includes the following steps:

[0029] Step S31: Obtain the value range of the dip reference pressure relief angle of the test area according to the results obtained in Step S1 and Step S2;

[0030] Step S32: Obtain the value range of the strike reference pressure relief angle of the test area according to the results obtained in Step S1 and Step S2;

[0031] Step S33: Determine the average value of the value range of the dip or strike reference pressure relief angle as the reference pressure relief angle for the on-site inspection borehole design according to the value ranges of Step S31 and Step S31. The specific calculation formula of the reference pressure relief angle is as follows:

[0032]

[0033] In the formula, is the reference pressure relief angle of the jth coal seam, is the maximum pressure relief angle of the jth coal seam, is the minimum reference pressure relief angle of the jth coal seam;

[0034] Furthermore, in Step S4, determining the design parameters of the inspection borehole and drawing the construction drawing of the inspection borehole includes the following steps:

[0035] Step S41: Conduct a survey on the actual situation of the test area on site and analyze the feasibility of constructing the protective layer effect inspection borehole;

[0036] Step S42: Determine the construction location of the protective layer effect inspection borehole according to the analysis results of Step S41;

[0037] Step S43: Based on the result obtained in Step S3 and in combination with the construction selection in Step S42, determine the design parameters of the pressure-relief angle for on-site investigation. The number of investigation boreholes designed for each construction location in each coal seam shall be no less than 12, including at least 6 along the strike and at least 6 along the dip. The 6 investigation boreholes along the strike include 2 boreholes corresponding to the reference pressure-relief angle along the strike and 4 boreholes corresponding to the comparison pressure-relief angle; the 6 investigation boreholes along the dip include 2 boreholes corresponding to the reference pressure-relief angle along the dip and 4 boreholes corresponding to the comparison pressure-relief angle. The design of the comparison pressure-relief angle can be calculated according to the size of the coal seam spacing d using the following empirical formula:

[0038]

[0039] In the formula, is the pressure-relief angle corresponding to the effect investigation of the jth coal seam.

[0040] Step S44: Based on the design parameters of the pressure-relief angle in Step S43, draw the construction drawing of the boreholes for the effect investigation of the protective layer in the test area in combination with the mine excavation engineering drawing.

[0041] The beneficial effects of the present invention are as follows: A method for arranging boreholes for investigating the pressure-relief effect in the mining of a coal seam group protective layer disclosed by the present invention, under the condition of fully considering the actual occurrence of the protective layer mining, obtains the theoretical pressure-relief angle through the established theoretical model of the coal seam dip angle and the pressure-relief angle under the condition of protective layer mining, combines with the simulated calculated pressure-relief angle obtained by numerical simulation calculation, determines the reference pressure-relief angle under the condition of protective layer mining, and finally completes the design of the parameters of the boreholes for investigating the protective layer according to the actual on-site situation and draws the construction drawing of the boreholes for investigation, which can greatly improve the layout quality of the boreholes for investigating the effect of the protective layer, reduce the error in delineating the on-site pressure-relief range under the condition of protective layer mining, and avoid the problem that the delineated range of the on-site protective layer investigation effect is too conservative due to a small coal seam spacing or there may be a pressure-relief blind area in the delineated range of the on-site protective layer investigation effect due to a large coal seam spacing, and scientifically guide the excavation deployment and high-yield and high-efficiency development of the mine. Description of the Drawings

[0042] In order to make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be described in detail with preference below in combination with the drawings, where:

[0043] Figure 1 is the flow chart of the present invention;

[0044] Figure 2 is the flow chart of the theoretically calculated pressure-relief angle in the present invention;

[0045] Figure 3 is the flow chart of the numerically calculated pressure-relief angle in the present invention;

[0046] Figure 4 is the flow chart of the reference pressure-relief angle in the present invention;

[0047] Figure 5 Schematic diagram of the reference pressure relief angle of the working face of the protective layer of the present invention along the inclined direction;

[0048] Figure 6 Schematic diagram of the reference pressure relief angle of the working face of the protective layer of the present invention along the strike direction;

[0049] Figure 7 Flow chart for designing the inspection borehole parameters and drawing the inspection borehole construction drawings in the present invention.

[0050] The reference numerals in the accompanying drawings of the specification include:

[0051] Protective layer 10, protected coal seams 11, 12, 13, 14, coal seam dip angle 20. Specific embodiments

[0052] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the scope of protection of the present invention.

[0053] A method for arranging inspection boreholes for investigating the pressure relief effect of mining a protective coal seam group in this embodiment is as Figure 1 shown, and specifically includes the following steps:

[0054] Step S1: Determine the theoretically calculated pressure relief angle of the investigated area of the protected coal seam by using the theoretical analysis method according to the dip angle of the protective coal seam;

[0055] In this embodiment, in step S1, to determine the theoretically calculated pressure relief angle of the protected coal seam, as Figure 2 shown, includes the following steps:

[0056] Step S11: Determine the dip angle of 40° as the demarcation point;

[0057] Step S12: According to the relevant data of the pressure relief angle of the protective layer along the inclined direction in Table E.1 of Appendix E of the "Regulations on the Prevention and Control of Coal and Gas Outbursts", taking the dip angle of 40° as the demarcation point, analyze the variation law of the dip pressure relief angle under different dip angle conditions by using the segmented fitting method, and then obtain the calculation model of the dip pressure relief angle under different mining conditions under different dip angle conditions;

[0058] When the dip angle of the coal seam ≤ 40°, the theoretically inclined reference pressure relief angle is taken according to the following formula:

[0059]

[0060] When the seam dip angle > 40°, the theoretical dip reference pressure relief angle is determined according to the following formula:

[0061]

[0062] Step S13: Collect the occurrence characteristics of the coal seam in the test area, including the seam dip angle 20, seam thickness, basic parameters of seam burial depth and their variation laws;

[0063] Step S14: Determine the seam dip angle parameter in the test area;

[0064] Step S15: Substitute the seam dip angle parameter obtained in Step S14 into the dip pressure relief angle calculation model under different mining conditions with different dip angles constructed in Step S12, and calculate the theoretical dip pressure relief angle of the inspected area of each protected coal seam;

[0065] Step S16: According to the protection range in the direction of the strike in Appendix E of the Detailed Rules for Preventing Coal and Gas Outbursts, and the coal seam occurrence characteristics obtained in Step S13, further determine the theoretical strike pressure relief angle (generally taking values of 56° - 60°) of the inspected area of the protected coal seam;

[0066] Step S17: According to the relevant results of Step S15 and Step S16, finally determine the theoretical calculated pressure relief angle of each protected coal seam.

[0067] Step S2: Use the numerical simulation method to determine the numerically calculated pressure relief angle of the inspected area of the protected coal seam;

[0068] In this embodiment, in Step S2, to determine the numerically calculated pressure relief angle, as Figure 3 shown, it includes the following steps:

[0069] Step S21: Collect relevant data of the test strata, including the comprehensive stratigraphic columnar section of the test area, occurrence of coal and rock strata, and burial depth;

[0070] Step S22: Collect the physical and mechanical parameters of the coal and rock strata in the test area, including cohesion, internal friction angle, elastic modulus, Poisson's ratio, and density;

[0071] Step S23: According to the relevant results of Step S21 and Step S22, use relevant numerical simulation software to construct a three-dimensional geological calculation geometric model of the test area. The specific three-dimensional geological calculation geometric model is established using existing simulation software and will not be elaborated here;

[0072] Step S24: Use the three-dimensional geological calculation geometric model constructed in Step S23 to carry out numerical simulation calculations under the condition of protective layer mining, and obtain the stress change law, displacement change law, and strain change law of each protected coal seam under the condition of protective layer mining;

[0073] Step S25: Determine the pressure-relief angle for numerical calculation of each protected layer according to the relevant results of Step S24, in combination with national and local regulations and relevant provisions of documents.

[0074] Step S3: Finally determine the reference pressure-relief angle for the on-site inspection boreholes designed for the protected coal seam according to the calculation results of Step S1 and Step S2.

[0075] In this embodiment, in Step S3, the determination of the reference pressure-relief angle for the on-site inspection boreholes designed for the protected layer is as Figure 4 shown, and specifically includes the following steps:

[0076] Step S31: Obtain the value range of the reference pressure-relief angle in the dip direction of each protected layer test area according to the theoretically calculated pressure-relief angle in the dip direction obtained in Step S1 and the numerically calculated pressure-relief angle in the dip direction obtained in Step S2.

[0077] Step S32: Obtain the value range of the reference pressure-relief angle in the strike direction of each protected layer test area according to the theoretically calculated pressure-relief angle in the strike direction obtained in Step S1 and the numerically calculated pressure-relief angle in the strike direction obtained in Step S2.

[0078] Step S33: Determine that the average value of the value range of the reference pressure-relief angle in the dip or strike direction is used as the reference pressure-relief angle for the on-site inspection borehole design according to the value ranges of Step S31 and Step S31. The specific calculation formula for the reference pressure-relief angle is as follows:

[0079]

[0080] In the formula, is the reference pressure-relief angle of the jth coal seam, is the maximum pressure-relief angle of the jth coal seam, is the minimum reference pressure-relief angle of the jth coal seam;

[0081] In this case, according to the implementation of Steps S1 to S3, schematic diagrams of the reference pressure-relief angles of each protected layer under the condition of protective layer mining can be obtained.

[0082] In this case, taking the upper and lower two protected layers as an example, the specific effect schematic diagrams are shown in Figure 5 and Figure 6 as shown.

[0083] The Figure 5 and Figure 6 are respectively the reference pressure-relief angles of each protected layer in the dip direction and the strike direction under the mining condition of the protective layer 10.

[0084] Among them, the protected layers include protected layer 11, protected layer 12, protected layer 13, and protected layer 14.

[0085] Step S4: Determine the design parameters of the exploration boreholes for the protected coal seam and draw the construction drawings for on-site exploration.

[0086] In this embodiment, in step S4, when determining the design parameters of the exploration boreholes and drawing the construction drawings of the exploration boreholes, as Figure 7 shown, the following steps are included:

[0087] Step S41: Conduct research on the actual situation at the test area site, analyze the feasibility of the construction of the exploration boreholes for the protective layer effect, and provide a technical basis for the subsequent selection of the exploration borehole construction.

[0088] Step S42: Determine the construction location of the exploration boreholes for the protective layer effect according to the analysis results of step S41.

[0089] Step S43: According to the results obtained in step S3, and in combination with the construction selection in step S42, determine the design parameters of the on-site exploration pressure relief angle. The number of exploration boreholes designed for each construction location of each protected coal seam is not less than 12, including at least 6 in the strike direction and at least 6 in the dip direction. The 6 exploration boreholes in the strike direction include 2 boreholes corresponding to the reference pressure relief angle in the strike direction and 4 boreholes corresponding to the comparison pressure relief angle; the 6 exploration boreholes in the dip direction include 2 boreholes corresponding to the reference pressure relief angle in the dip direction and 4 boreholes corresponding to the comparison pressure relief angle. The design of the comparison pressure relief angle can be calculated according to the size of the coal seam spacing d using the following empirical formula:

[0090]

[0091] In the formula, is the pressure relief angle corresponding to the exploration of the jth coal seam.

[0092] Step S44: According to the design parameters of the pressure relief angle in step S43, draw the construction drawings of the exploration boreholes for the protective layer effect in the test area in combination with the mine excavation and mining engineering drawings.

[0093] A method for arranging exploration boreholes for the pressure relief effect of multi-seam protective layer mining disclosed in the present invention, under the condition of fully considering the actual occurrence of the protective layer mining, obtains the theoretical pressure relief angle through the established theoretical model of the coal seam dip angle and the pressure relief angle under the condition of protective layer mining, combines with the simulated calculated pressure relief angle obtained by numerical simulation calculation, determines the reference pressure relief angle under the condition of protective layer mining, and finally completes the design of the parameters of the exploration boreholes for the protective layer according to the actual on-site situation and draws the construction drawings of the exploration boreholes, which can greatly improve the arrangement quality of the exploration boreholes for the protective layer effect, reduce the error of the delineated pressure relief range under the condition of protective layer mining, and avoid the problem that the delineated range of the on-site protective layer exploration effect is too conservative due to the small coal seam spacing or there may be a pressure relief blind area in the delineated range of the on-site protective layer exploration effect due to the large coal seam spacing, and scientifically guide the excavation and deployment and high-yield and high-efficiency development of the mine.

[0094] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the spirit and scope of the technical solutions of the present invention, and they should all be covered within the scope of the claims of the present invention.

Claims

1. A drilling arrangement method for investigating the pressure relief effect of coal seam group protective layer mining, characterized in that: The following steps are involved: Step S1: using a theoretical analysis method to determine the theoretical calculated pressure relief angle of the investigation area; Step S2: using a numerical simulation method to determine the numerical calculation pressure relief angle of the investigation area; Step S3: finally determining the reference pressure relief angle of the on-site inspection drilling design according to the calculation results of the steps S1 and S2; Step S4: Determine the inspection drilling design parameters and draw the on-site inspection construction drawings.

2. The drilling arrangement method for investigating the pressure relief effect of coal seam group protective layer mining according to claim 1 is characterized by: In step S1, a theoretical analysis method is used to determine the theoretical calculated pressure relief angle of the investigation area, including the following steps: The coal seam dip angle of 40° is determined as the dividing point; Step S12: Taking the coal seam dip angle of 40° as the dividing point, adopting the segmented fitting method to analyze the variation law of the dip pressure relief angle under different dip angle conditions, and then obtaining the dip pressure relief angle calculation model under different dip angle conditions and different mining conditions; When the coal seam inclination is ≤40°, the theoretical dip reference relief angle is taken according to the following formula: When the coal seam inclination angle is greater than 40°, the theoretical dip reference relief angle is taken according to the following formula: Step S13: Collecting coal seam occurrence characteristics in the test area, including basic parameters and change patterns of coal seam inclination, coal seam thickness, and coal seam burial depth; Step S14: determining the coal seam inclination parameters in the test area; Step S15: bringing the coal seam inclination parameter obtained in step S14 into the inclination relief angle calculation model under different inclination conditions and different mining conditions constructed in step S12 to calculate the theoretical inclination relief angle of the investigated area; Step S16: determining the theoretical strike relief angle of the investigated area according to the coal seam occurrence characteristics obtained in step S13; Step S17: According to the relevant results of step S15 and step S16, the theoretical calculated pressure relief angle is finally determined.

3. The drilling arrangement method for investigating the pressure relief effect of coal seam group protective layer mining according to claim 2 is characterized by: Wherein, in step S2, a numerical simulation method is used to determine the numerical calculation pressure relief angle of the investigation area, including the following steps: Step S21: Collecting relevant data of the test strata, including a comprehensive stratigraphic columnar diagram of the test area, occurrence of coal and rock strata, and burial depth; Step S22: Collecting physical and mechanical parameters of coal and rock formations in the test area, including cohesion, internal friction angle, elastic modulus, Poisson's ratio, and density; Step S23: Based on the relevant results of step S21 and step S22, a three-dimensional geological computational geometry model of the test area is constructed using relevant numerical simulation software. The specific three-dimensional geological computational geometry model is established using existing simulation software, which will not be described in detail here; Step S24: using the three-dimensional geological computational geometry model constructed in step S23, numerical simulation calculations are performed under protective layer mining conditions to obtain stress variation laws, displacement variation laws, and strain variation laws of each protected coal seam under protective layer mining conditions; Step S25: According to the relevant results of step S24, determine the numerical value of the pressure relief angle.

4. The drilling arrangement method for investigating the pressure relief effect of coal seam group protective layer mining according to claim 3 is characterized by: Wherein, in step S3, according to the calculation results of step S1 and step S2, the reference pressure relief angle of the on-site inspection drilling design is finally determined, including the following steps: Step S31: Calculating the pressure relief angle based on the theoretical calculated pressure relief angle of the inclination obtained in step S1 and the numerical calculated pressure relief angle of the inclination obtained in step S2, and obtaining the value range of the reference pressure relief angle of the inclination of the test area; Step S32: obtaining a range of values ​​of a reference pressure relief angle in the strike direction of the test area according to the theoretically calculated pressure relief angle in the strike direction obtained in step S1 and the numerically calculated pressure relief angle in the strike direction obtained in step S2; Step S33: According to the step S31 and the value range of the step S31, determine the average value of the dip or strike reference pressure relief angle value range as the reference pressure relief angle for field investigation drilling design. The specific calculation formula of the reference pressure relief angle is as follows: In the formula, is the reference pressure relief angle of the jth coal seam, δ j imax is the maximum pressure relief angle of the jth coal seam, δ j imin is the minimum reference relief angle of the jth coal seam.

5. The drilling arrangement method for investigating the pressure relief effect of coal seam group protective layer mining according to claim 4 is characterized in that: In step S4, determining the inspection drilling design parameters and drawing the on-site inspection construction drawing includes the following steps: Step S41: investigating the actual situation on site in the test area, analyzing the effect of the protective layer and examining the feasibility of drilling construction; Step S42: according to the analysis result of step S41, determining the drilling construction location for the protective layer effect inspection; Step S43: According to the result obtained in step S3, and in combination with the construction selection of step S42, determine the design parameters of the on-site inspection relief angle. The number of inspection boreholes designed for each construction position of each coal seam is not less than 12, including at least 6 strikes and at least 6 dips. The 6 strike inspection boreholes include 2 strike reference relief angle corresponding boreholes and 4 comparison relief angle corresponding boreholes; the 6 dip inspection boreholes include 2 dip reference relief angle corresponding boreholes and 4 comparison relief angle corresponding boreholes. The comparison relief angle design can be calculated according to the following empirical formula based on the coal seam spacing d: In the formula, This is the corresponding relief angle for the effect investigation of the j-th coal seam. Step S44: Based on the design parameters of the pressure relief angle in step S43, a drilling construction drawing for investigating the protective layer effect in the test area is drawn in combination with the mine excavation engineering drawing.

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