Method for determining rock burst coal seam drilling cutting method construction parameters and early warning critical value

Abstract

The invention provides a rock burst coal seam drilling cutting method construction parameter and early warning critical value determination method, and relates to the technical field of mine safety. The method comprises the following steps: firstly, acquiring rock mechanical parameters of a coal body in surrounding rock of a to-be-drillings early-warning roadway, and calculating critical parameters of rock burst of the to-be-drillings early-warning roadway; then, according to the calculated radius of the critical softening area where the roadway rock burst occurs, the depth of a drill hole constructed through a drilling cutting method in surrounding rock of the roadway to be monitored and early warned is determined; then determining the actual critical mining-induced stress index engineering value of rock burst of the same coal seam roadway where the roadway to be pre-warned is located; and finally, the grading early warning index critical value of the maximum single-meter drilling cutting amount of the roadway to be subjected to drilling cutting early warning and the grading early warning index critical value of the surrounding rock depth where the maximum single-meter drilling cutting amount occurs in the drill hole of the roadway to be subjected to drilling cutting early warning are determined, and the danger grade of the roadway to be subjected to drilling cutting early warning is determined. According to the method, the drilling cutting method construction design and early warning critical parameter value determination are more scientific, the universality is higher, and the method is suitable for coal rocks with different strengths.

Description

Technical Field

[0001] The present invention relates to the field of mine safety technology, and in particular to a method for determining construction parameters and early warning critical values ​​of a rock burst coal seam cuttings method. Background Art

[0002] In recent years, rock burst accidents have occurred frequently, causing a large number of tunnels, equipment damage and casualties, threatening the lives of underground workers and seriously restricting economic development. More than 95% of rock bursts in my country occur in tunnels. Monitoring and early warning of rock bursts is the first prerequisite for rock burst control. Among them, the drill cuttings method has simple equipment, intuitive monitoring results of drill cuttings, and is easy to operate and identify on-site. It is an important monitoring and early warning method for rock burst hazards. The drill cuttings method is a method of identifying rock burst hazards by drilling small diameter holes (42 to 50 mm in diameter) in coal seams using a pneumatic drill or an electric drill, based on the amount of coal powder discharged at different depths, its changing patterns, and related dynamic effects.

[0003] The key to determining when and where to prevent and control rock burst is to determine the construction depth of coal drilling and the critical value of coal dust discharged at different depths to warn rock burst. At present, the warning critical value of the drilling cuttings method is determined by multiplying the normal coal dust amount that is not affected by mining stress by the drilling dust rate index. However, in recent years, the occurrence of soft coal and high-water content coal bodies in deep mining projects has increased, resulting in unreasonable determination of the current critical indicators of drilling cuttings, frequent excessive warnings, and greatly reduced production efficiency.

[0004] The main problems currently exist are as follows: 1) In the method of determining the critical warning value by using the drill dust rate index and the normal amount of drill cuttings, the drill dust rate index is often a numerical value (1.5-3.0) artificially and mechanically determined, and its determination fails to be quantitatively related to the brittleness and strength properties of the coal material, the borehole size, etc., resulting in low universality and accuracy of the critical value determination method. 2) The determination of the critical warning value is completely dependent on experimental testing and engineering experience. The size of the index value fails to be associated with the critical stress of rock burst, and there is a lack of criteria for predicting the impact hazard. 3) The current national standard proposes that the drilling depth be determined as 3-4 times the tunnel height. The depth determination lacks a theoretical basis. Insufficient drilling depth will not be able to well reflect the stress distribution state of the elastic zone of the tunnel surrounding rock. Summary of the invention

[0005] The technical problem to be solved by the present invention is to provide a method for determining the construction parameters and warning critical values ​​of the drilling method for coal seams with impact ground pressure in view of the deficiencies of the above-mentioned prior art, which is used to determine the construction parameters and warning critical values ​​of the drilling method for coal seams with impact ground pressure.

[0006] In order to solve the above technical problems, the technical solution adopted by the present invention is: a method for determining construction parameters and early warning critical values ​​of rock burst coal seam drilling cuttings method, comprising the following steps:

[0007] Step 1: Obtain rock mechanical parameters of coal bodies in the surrounding rock of the tunnel to be drilled; the rock mechanical parameters include uniaxial compressive strength σ c , elastic modulus E, impact modulus index K = λ 1 / E, residual drop modulus λ 2 and residual strength coefficient ξ; where λ 1 is the post-peak softening modulus;

[0008] Step 2: Calculate the critical crushing zone radius ρ of the rock burst warning tunnel to be drilled fcr , critical softening zone radius ρ cr , Critical softening depth of surrounding rock L pcr , critical ground stress P cr And the optimized critical mining peak stress P of the roadway rock burst to be warned mcr * ;

[0009] Step 3: Determine the depth L of the drilling hole constructed by the cuttings method in the surrounding rock of the tunnel to be monitored and warned drill-bits ;

[0010] The critical softening zone radius ρ of the tunnel rock burst calculated in step 2 cr , determine the depth L of the drilling hole constructed by the cuttings method in the surrounding rock of the monitored and early-warning tunnel drill-bits =η drill ρ cr , where η drill The drilling depth margin factor for cuttings;

[0011] Step 4: Define the critical mining stress index K for calculating rock burst in tunnels cr , and then determine the critical mining stress index engineering value K of the actual rock burst in the same coal seam where the warning roadway is located fcr ;

[0012] Step 4.1: Define the critical mining stress index K for calculating rock burst in tunnels cr , as shown in the following formula:

[0013]

[0014] Where P m is the mining peak stress in the surrounding rock of the tunnel;

[0015] Step 4.2: Obtain the actual mining peak stress P of the rock burst in the same coal seam where the roadway to be warned is located mfBased on the definition of the critical mining stress index for rock burst in the roadway, the engineering value of the critical mining stress index for the actual rock burst in the same coal seam of the roadway to be warned is calculated.

[0016] If the coal seam in the area to be drilled cuttings warned has not experienced rock burst, the critical mining stress index engineering value K of rock burst that actually occurs is calculated by referring to the coal seam with the same rock burst tendency that has experienced rock burst. fcr ;

[0017] Step 5: Determine the maximum amount of drilling cuttings per meter M in the tunnel to be drilled cuttings warning max The critical value M of the graded warning indicator max(弱) 、M max(中等) With M max(强) , and then determine the danger level of the tunnel to be drilled cuttings warning;

[0018] Step 5.1: Determine the distance u from the borehole wall diameter of the cuttings warning tunnel to be drilled a ;

[0019] Set drilling and crushing area d <r<r f The coal body is incompressible, so the borehole wall diameter is moved closer by u a , as shown in the following formula:

[0020]

[0021] In the formula, r d is the radius of the crushing zone of the borehole; r f is the radius of the plastic softening zone of the drilled hole; r 0 is the drilling radius or the drill cutting radius;

[0022] Step 5.2: Determine the critical conditions for the occurrence of drilling impact;

[0023] Calculate the critical crushing zone radius r where drilling impact occurs dcr , radius of critical plastic softening zone r pcr and critical environmental stress P hcr , as shown in the following formula:

[0024]

[0025]

[0026]

[0027] in, is the stress of the surrounding rock crushing zone on the plastic softening zone when drilling impact occurs, d is the borehole diameter or the drill bit cutting diameter, d = 2r 0 ; m is an intermediate variable, is the internal friction angle of coal-rock medium in the crushing zone;

[0028] Step 5.3: According to the physical principle of drill bit cuttings generation, determine the maximum single-meter cuttings volume M of the tunnel to be drilled cuttings warning max , as shown in the following formula:

[0029]

[0030] Among them, γ is the bulk density of coal;

[0031] Step 5.4: Set the critical crushing zone radius of the drill hole Substitute r into equation (6) d , and obtain the critical maximum single-meter cuttings M before the impact starts maxcr , as shown in the following formula:

[0032]

[0033] Step 5.5: Determine the critical maximum amount of drilling cuttings per meter M max The graded warning value M max(弱) 、M max(中等) With M max(强) , and then determine the danger level of the tunnel to be drilled cuttings warning;

[0034] The critical maximum single meter cuttings amount M maxcr The graded warning value M max(弱) 、M max(中等) With M max(强) As shown in the following formula:

[0035]

[0036] When 0<M max <0.25K fcr M maxcr , wait for the drilling cuttings warning lane to be free of impact danger warning; when 0.25K fcr M maxcr ≤M max <0.5K fcr M maxcr , wait for the cuttings warning lane to be a weak impact danger warning; when 0.5K fcr M maxcr ≤M max <0.75K fcr M maxcr , the cuttings warning lane is a medium impact danger warning; when M max ≥0.75K fcr M maxcr , the cuttings warning tunnel is a strong impact hazard warning;

[0037] Step 6: Determine the maximum amount of drilling cuttings per meter in the drilling hole of the tunnel to be warned of drilling cuttings M max The depth of surrounding rock L p The critical value L of the graded warning indicator p(弱) , L p(中等) With L p(强) , further determine the danger level of the tunnel to be drilled cuttings warning;

[0038] The surrounding rock depth L p The critical value L of the graded warning indicator p(弱) , L p(中等) With L p(强) As shown in the following formula:

[0039]

[0040] When 0<L p <0.25K fcr L pcr , the evaluation of the tunnel to be drilled cuttings warning is that there is no impact danger warning; when 0.25K fcr L pcr ≤L p <0.5K fcr L pcr , the evaluation of the tunnel to be drilled cuttings warning is a weak impact hazard warning; when 0.5K fcr L pcr ≤L p <0.75K fcr L pcr , the tunnel to be drilled cuttings warning is evaluated as a medium impact hazard warning; when L p ≥0.75K fcr L pcr , and evaluate the drilling cuttings warning tunnel as a strong impact hazard warning.

[0041] The beneficial effect of adopting the above technical scheme is that: the present invention provides a method for determining the construction parameters and warning critical values ​​of the drilling cuttings method for impact ground pressure coal seams, wherein the method for determining the construction parameters and critical index values ​​of the drilling cuttings method is directly related to the coal rock mechanical parameters, borehole structure parameters, tunnel structure parameters and current environmental stress, so that the drilling construction design parameters of the drilling cuttings method are more scientific, and the method for determining the drilling cuttings warning critical value is more universal for coal rocks of different strengths. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 A flow chart of a method for determining construction parameters and warning critical values ​​of a rock burst coal seam cuttings method provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0043] The specific implementation of the present invention is further described in detail below in conjunction with the accompanying drawings and examples. The following examples are used to illustrate the present invention, but are not intended to limit the scope of the present invention.

[0044] This embodiment takes a coal seam in a mine as an example, and adopts the rock burst coal seam drilling cuttings construction parameter and early warning critical value determination method of the present invention to determine the drilling cuttings construction parameter and drilling early warning critical index value of the coal seam. Among them, the drilling cuttings construction parameter mainly refers to the drilling depth; the drilling early warning critical index is the critical maximum single meter drilling cuttings M maxcr And the maximum amount of drilling cuttings per meter in the drilling hole of the drilling cuttings warning lane M max The depth of surrounding rock L p .

[0045] In this embodiment, a method for determining construction parameters and early warning critical values ​​of rock burst coal seam drilling method is provided. Figure 1 As shown, the following steps are included:

[0046] Step 1: Obtain rock mechanical parameters of coal bodies in the surrounding rock of the tunnel to be drilled; the rock mechanical parameters include uniaxial compressive strength σ c , elastic modulus E, impact modulus index K = λ 1 / E, residual drop modulus λ 2 and residual strength coefficient ξ; where λ 1 is the post-peak softening modulus;

[0047] Step 2: Calculate the critical crushing zone radius ρ of the rock burst warning tunnel to be drilled fcr , critical softening zone radius ρ cr , Critical softening depth of surrounding rock L pcr , critical ground stress P cr And the optimized P of rock burst in the tunnel to be warned mcr ;

[0048] Step 2.1: Obtain the support stress p of the tunnel to be warned s ;

[0049] Step 2.2: Calculate the critical crushing zone radius ρ of the rock burst in the tunnel to be monitored and warned fcr and the critical softening zone radius ρ cr , as shown in the following formulas:

[0050]

[0051]

[0052] Calculation of critical softening depth L of surrounding rock for rock burst in tunnel pcr , as shown in the following formula:

[0053]

[0054] Among them, B is the width of the tunnel to be drilled for anti-collision construction. It is the internal friction angle of coal-rock medium in the plastic softening zone of tunnel surrounding rock.

[0055] Calculate the critical ground stress P for rock burst in the tunnel to be monitored and warned cr for:

[0056]

[0057] Among them, ρ 0 is the radius of the laneway after the laneway to be monitored is equivalent to a homogeneous, continuous and isotropic circular laneway; m is an intermediate variable, is the internal friction angle of coal-rock medium in the plastic softening zone, p fcr is the stress of the surrounding rock crushing zone on the plastic softening zone when the tunnel impact starts, as shown in the following formula:

[0058]

[0059] in, is the internal friction angle of coal-rock medium in the crushing zone,

[0060] Step 2.3: Calculate the critical mining peak stress P for the occurrence of rock burst in the tunnel to be warned mcr ;

[0061] Step 2.4: According to the cross-sectional shape of the tunnel to be warned, optimize the critical mining peak stress P of the tunnel to be warned for rock burst mcr , as shown in the following formula:

[0062] P mcr * =n 1 ×P mcr

[0063] Among them, P mcr * is the optimized critical mining peak stress for rock burst in the tunnel to be warned, n 1 is the cross-section correction coefficient; when the cross-section shape of the tunnel to be warned is rectangular, trapezoidal, straight-walled arched, or circular, n 1 They are 0.89, 0.92, 0.95, and 0.98 respectively;

[0064] Step 3: Determine the depth L of the drilling hole constructed by the cuttings method in the surrounding rock of the tunnel to be monitored and warned drill-bits ;

[0065] The critical softening zone radius ρ of the tunnel rock burst calculated in step 2cr , determine the depth L of the drilling hole constructed by the cuttings method in the surrounding rock of the monitored and early-warning tunnel drill-bits =η drill L pcr , where η drill The drilling depth margin coefficient for cuttings is generally 1.1 to 1.3.

[0066] Step 4: Define and calculate the critical mining stress index K for rock burst in tunnels cr , and then determine the critical mining stress index engineering value K of the actual rock burst in the same coal seam where the warning roadway is located fcr ;

[0067] Step 4.1: Define and calculate the critical mining stress index K for rock burst in tunnels cr , as shown in the following formula:

[0068]

[0069] Where P m is the mining peak stress in the surrounding rock of the tunnel, MPa;

[0070] Step 4.2: Use the common method of surrounding rock mining stress testing to obtain the actual mining peak stress P of the same coal seam roadway where the warning roadway is located. mf Based on the critical mining stress index of rock burst in the tunnel, the engineering value of the critical mining stress index of rock burst in the same coal seam in the tunnel to be warned is calculated.

[0071] Step 4.3: If the coal seam in the area to be drilled cuttings warned has not experienced rock burst, the critical mining stress index engineering value K of rock burst can be calculated by referring to the coal seams with the same rock burst tendency that have experienced rock burst. fcr .

[0072] Step 5: Determine the critical maximum single-meter cuttings volume M of the tunnel to be drilled cuttings warning maxcr The critical value M of the graded warning indicator max(弱) 、M max(中等) With M max(强) ;

[0073] Step 5.1: Determine the distance u from the borehole wall diameter of the cuttings warning tunnel to be drilled a The calculation method and analytical formula of ;

[0074] Set drilling and crushing area (r d <r<r f ) The coal body is incompressible, then ε r +ε θ =0, that is Solved so Equivalent strain Because the boundary between the crushing zone and the plastic softening zone meets have to Therefore, the borehole wall diameter is moved closer by u a :

[0075]

[0076] In the formula, r d is the radius of the crushing zone of the borehole, in m; r f is the radius of the softening zone of the drilled hole, in m;

[0077] Step 5.2: Determine the critical conditions for the occurrence of drilling impact;

[0078] Calculate the critical crushing zone radius r where drilling impact occurs dcr , radius of critical plastic softening zone r pcr and critical environmental stress P hcr , as shown in the following formula:

[0079]

[0080]

[0081]

[0082] in, is the stress r acting on the plastic softening zone from the surrounding rock crushing zone when drilling impact occurs 0 is the drilling radius or the drill cutting radius;

[0083] Step 5.3: According to the physical principle of drill bit cuttings generation, determine the maximum single-meter cuttings volume M of the tunnel to be drilled cuttings warning max , as shown in the following formula:

[0084]

[0085] Among them, γ is the bulk density of coal;

[0086] Step 5.4: Set the critical crushing zone radius of the drill hole Substitute r into formula (11) d , and obtain the critical maximum single-meter cuttings M before the impact starts maxcr , as shown in the following formula:

[0087]

[0088] Step 5.5: Determine the critical maximum amount of drilling cuttings per meter M maxcr The graded warning value M max(弱) 、Mmax(中等) With M max(强) ;

[0089]

[0090] When 0<M max <0.25K fcr M maxcr , wait for the drilling cuttings warning lane to be free of impact danger warning; when 0.25K fcr M maxcr ≤M max <0.5K fcr M maxcr , wait for the cuttings warning lane to be a weak impact danger warning; when 0.5K fcr M maxcr ≤M max <0.75K fcr M maxcr , the cuttings warning lane is a medium impact danger warning; when M max ≥0.75K fcr M maxcr , the cuttings warning tunnel is a strong impact hazard warning;

[0091] Step 6: Determine the maximum amount of drilling cuttings per meter in the drilling hole of the tunnel to be warned of drilling cuttings M max The depth of surrounding rock L p The critical value L of the graded warning indicator p(弱) , L p(中等) With L p(强) ;

[0092]

[0093] When 0<L p <0.25K fcr L pcr , the evaluation of the tunnel to be drilled cuttings warning is that there is no impact danger warning; when 0.25K fcr L pcr ≤L p <0.5K fcr L pcr , the evaluation of the tunnel to be drilled cuttings warning is a weak impact hazard warning; when 0.5K fcr L pcr ≤L p <0.75K fcr L pcr , the tunnel to be drilled cuttings warning is evaluated as a medium impact hazard warning; when L p ≥0.75K fcr L pcr , and evaluate the drilling cuttings warning tunnel as a strong impact hazard warning.

[0094] In this embodiment, the coal seam has an average thickness of 7.03m, an inclination of 13°, and an average burial depth of 984m. The average uniaxial compressive strength of the coal body is 11.12MPa, the coal seam has a weak impact tendency, the roof has a weak impact tendency, and the floor has no impact tendency. The results of determining the coal rock physical parameters, support strength, tunnel geometric characteristic parameters, and warning critical values ​​are shown in Table 1;

[0095] Table 1 Results of determination of tunnel parameters and warning critical values ​​of drilling method for rock burst coal seams

[0096]

[0097]

[0098] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some or all of the technical features therein. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope defined by the claims of the present invention.

Claims

1. A method for determining construction parameters and early warning critical values ​​of rock burst coal seam drilling method, Features: The following steps are involved: Step 1: Obtain rock mechanical parameters of coal bodies in the surrounding rock of the roadway to be drilled; Step 2: Calculate the critical crushing zone radius ρ of the rock burst warning tunnel to be drilled fcr , critical softening zone radius ρ cr , Critical softening depth of surrounding rock L pcr , critical ground stress P cr And the optimized critical mining peak stress P of the roadway rock burst to be warned mcr * ; Step 3: The critical softening zone radius ρ of the tunnel rock burst calculated in step 2 cr , determine the depth L of the drilling hole constructed by the cuttings method in the surrounding rock of the monitored and early-warning tunnel drill-bits ; Step 4: Define the critical mining stress index K for calculating rock burst in tunnels cr , and then determine the critical mining stress index engineering value K of the actual rock burst in the same coal seam where the warning roadway is located fcr ; Step 5: Determine the maximum amount of drilling cuttings per meter M in the tunnel to be drilled cuttings warning max The critical value M of the graded warning indicator max(弱) 、M max(中等) With M max(强) , and then determine the danger level of the tunnel to be drilled cuttings warning; Step 6: Determine the maximum amount of drilling cuttings per meter in the drilling hole of the tunnel to be warned of drilling cuttings M max The depth of surrounding rock L p The critical value L of the graded warning indicator p(弱) , L p(中等) With L p(强) , and further determine the danger level of the tunnel to be warned of drilling cuttings.

2. A method for determining construction parameters and early warning critical values ​​of a rock burst coal seam cuttings method according to claim 1, Features: The rock mechanics parameters include the uniaxial compressive strength σ c , elastic modulus E, impact modulus index K = λ 1 / E, residual drop modulus λ 2 and residual strength coefficient ξ; where λ 1 is the post-peak softening modulus.

3. A method for determining construction parameters and early warning critical values ​​of a rock burst coal seam drilling method according to claim 2, Features: Step 3 is based on the critical softening zone radius ρ of the tunnel rock burst calculated in step 2 cr , determine the depth L of the drilling hole constructed by the cuttings method in the surrounding rock of the monitored and early-warning tunnel drill-bits =η drill ρ cr , where η drill It is the excess coefficient of drilling depth for drill cuttings.

4. A method for determining construction parameters and early warning critical values ​​of a rock burst coal seam drilling method according to claim 3, Features: The specific method of step 4 is: Step 4.1: Define the critical mining stress index K for calculating rock burst in tunnels cr , as shown in the following formula: Where P m is the mining peak stress in the surrounding rock of the tunnel; Step 4.2: Obtain the actual mining peak stress P of the rock burst in the same coal seam where the roadway to be warned is located mf Based on the definition of the critical mining stress index for rock burst in the roadway, the engineering value of the critical mining stress index for the actual rock burst in the same coal seam of the roadway to be warned is calculated. If the coal seam in the area to be drilled cuttings warned has not experienced rock burst, the critical mining stress index engineering value K of rock burst that actually occurs is calculated by referring to the coal seam with the same rock burst tendency that has experienced rock burst. fcr .

5. A method for determining construction parameters and early warning critical values ​​of a rock burst coal seam drilling method according to claim 4, Features: The specific method of step 5 is: Step 5.1: Determine the distance u from the borehole wall diameter of the cuttings warning tunnel to be drilled a ; Set drilling and crushing area d <r<r f The coal body is incompressible, so the borehole wall diameter displacement u a , as shown in the following formula: In the formula, r d is the radius of the crushing zone of the borehole; r f is the radius of the plastic softening zone of the drilled hole; r 0 is the drilling radius or the drill cutting radius; Step 5.2: Determine the critical conditions for the occurrence of drilling impact; The critical conditions for the occurrence of drilling impact include the critical crushing zone radius r where drilling impact occurs dcr , radius of critical plastic softening zone r pcr and critical environmental stress P hcr , as shown in the following formula: in, is the stress of the surrounding rock crushing zone on the plastic softening zone when drilling impact occurs, d is the borehole diameter or the drill bit cutting diameter, d = 2r 0 ; m is an intermediate variable, is the internal friction angle of coal-rock medium in the crushing zone; Step 5.3: According to the physical principle of drill bit cuttings generation, determine the maximum single-meter cuttings volume M of the tunnel to be drilled cuttings warning max ; The maximum amount of drilling cuttings per meter in the tunnel to be drilled is determined as M max As shown in the following formula: Among them, γ is the bulk density of coal; Step 5.4: Set the critical crushing zone radius of the drill hole Substitute r into equation (6) d , and obtain the critical maximum single-meter cuttings M before the impact starts maxcr , as shown in the following formula: Step 5.5: Determine the critical maximum amount of drilling cuttings per meter M max The graded warning value M max(弱) 、M max(中等) With M max(强) , and then determine the danger level of the tunnel to be drilled cuttings warning.

6. A method for determining construction parameters and early warning critical values ​​of rock burst coal seam drilling method according to claim 5, Features: The critical maximum single meter cuttings amount M maxcr The graded warning value M max(弱) 、M max(中等) With M max(强) As shown in the following formula: When 0<M max <0.25K fcr M maxcr , wait for the drilling cuttings warning lane to be free of impact danger warning; when 0.25K fcr M maxcr ≤M max <0.5K fcr M maxcr , wait for the cuttings warning lane to be a weak impact danger warning; when 0.5K fcr M maxcr ≤M max <0.75K fcr M maxcr , the cuttings warning lane is a medium impact danger warning; when M max ≥0.75K fcr M maxcr , the cuttings warning tunnel will be a strong impact hazard warning.

7. A method for determining construction parameters and early warning critical values ​​of rock burst coal seam drilling method according to claim 6, Features: The surrounding rock depth L in step 6 p The critical value L of the graded warning indicator p(弱) , L p(中等) With L p(强) As shown in the following formula: When 0<L p <0.25K fcr L pcr , evaluate the tunnel to be drilled cuttings warning as having no impact hazard warning; When 0.25K fcr L pcr ≤L p <0.5K fcr L pcr , the evaluation of the tunnel to be drilled cuttings warning is a weak impact hazard warning; when 0.5K fcr L pcr ≤L p <0.75K fcr L pcr , the tunnel to be drilled cuttings warning is evaluated as a medium impact hazard warning; when L p ≥0.75K fcr L pcr , and evaluate the drilling cuttings warning tunnel as a strong impact hazard warning.

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