Method for classifying influence degree of coal seam by fire area

Abstract

The application provides a coal seam fire area influence degree classification method, comprising the following steps: confirming the minimum distance D between the mining coal seam and the fire area; calculating the height H of the caving zone of the roof of the mining coal seam m ; calculating the height H of the fractured zone of the roof of the mining coal seam li ; calculating the safety thickness T of the coal rock pillar for preventing the collapse of the coal rock layer after mining; according to the obtained values of D, H m , H li and T, classifying the threat level of the mining coal seam from the fire area; when D>T, determining that the threat level of the mining coal seam from the fire area is III; when H li <D≤T, determining that the threat level of the mining coal seam from the fire area is II; when H m <D≤H li , determining that the threat level of the mining coal seam from the fire area is I; when D≤H m , determining that the threat level of the mining coal seam from the fire area is 0; the coal seam fire area influence degree classification method solves the problem that the threat degree of the upper coal seam fire area to the mining coal seam is difficult to determine in the prior art.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of coal mining, in particular, relates to a coal seam fire area influence degree classification method. BACKGROUND

[0002] Coalfield fire area is one of the serious threats to the safety of coal mining, the geological conditions of coal seam under the fire area will change constantly, under the conditions of close distance coal seam group mining and complex catastrophic geological body, the overburden rock is affected by multiple mining, the fracture zone is serious, multiple goaf communicates with each other, even the goaf in the coal mine communicates directly with the surface, forming a very complex air leakage, increasing the risk of goaf spontaneous combustion and concealment; under the condition that the upper catastrophic geological body (old mine fire, coalfield fire) has not been fundamentally treated, the toxic and harmful gases in the catastrophic body will flow into the lower mining coal seam through the communicating fracture, threatening the safety of personnel life.

[0003] At present, the fire area treatment technology and fire prevention technology are constantly improving, but due to the inability to judge the influence degree and type of the lower coal seam affected by the fire area, it is difficult to take targeted fire prevention measures. If the fire prevention measures underestimate the influence degree of the lower coal seam affected by the fire area, it is easy to cause the spread of the fire area due to insufficient fire prevention investment, and then threaten the safety of coal mining, resulting in greater loss in the later period; if the fire prevention measures overestimate the influence degree of the lower coal seam affected by the fire area, it is easy to cause resource waste and increase the cost of fire prevention due to excessive investment. SUMMARY

[0004] The main purpose of the present application is to provide a coal seam fire area influence degree classification method to solve the problem that the threat degree of the fire area of the upper coal seam to the mining coal seam is difficult to judge in the prior art.

[0005] In order to achieve the above purpose, according to one aspect of the present application, a coal seam fire area influence degree classification method is provided for determining the threat degree of the fire area of the coal mine to the mining coal seam, which comprises: confirming the minimum distance D between the mining coal seam and the fire area; calculating the height H m of the caving zone of the roof of the mining coal seam li ; calculating the safety thickness T of the coal rock pillar for preventing the collapse of the coal rock layer after mining; according to the values of D, H m , H li and T, the threat level of the fire area to the mining coal seam is classified; when D>T, it is determined that the threat level of the fire area to the mining coal seam is III; when H li <D≤T, it is determined that the threat level of the fire area to the mining coal seam is II; when H m <D≤H liWhen D≤H, it is determined that the threat level of the coal seam from the fire area is I level. m When D≤H, it is determined that the threat level of the coal seam from the fire area is 0 level; wherein the threat level of the coal seam from the fire area is sequentially increased according to III level, II level, I level and 0 level.

[0006] Further, before confirming the minimum distance D between the coal seam and the fire area, it is determined that the maximum inclination of the extension direction of the layer position of the fire area relative to the horizontal direction is greater than 35°, and mining is prohibited below the fire area.

[0007] Further, when the inclination of the coal seam relative to the horizontal direction is in the range of 0° to 54°, the height H m of the caving zone of the roof of the coal seam and the height Hli of the fractured zone of the roof of the coal seam are calculated according to the lithology of the rock of the roof of the coal seam, and the lithology of the rock of the roof of the coal seam is determined according to the compressive strength of the rock of the roof of the coal seam.

[0008] Further, when the compressive strength of the rock of the roof of the coal seam is greater than 80MPa, the height H m of the caving zone of the roof of the coal seam can be calculated by the following calculation formula: ; wherein M is the coal seam thickness of the coal seam, k is the crushing coefficient of the falling rock, and is the coal seam inclination of the coal seam.

[0009] Further, when the compressive strength of the rock of the roof of the coal seam is not greater than 80MPa, the height H m of the caving zone of the roof of the coal seam can be calculated by the following calculation formula: ; wherein M is the coal seam thickness of the coal seam, and W is the sinking height value of the roof during the rock falling process of the coal seam.

[0010] Further, when the coal seam needs to be mined in layers, and the single layer mining thickness is in the range of 1m to 3m, and the cumulative mining thickness is less than 15m, the height H m of the caving zone of the roof of the coal seam can be calculated by the following calculation method: ; wherein M is the coal seam thickness of the coal seam, and X, Y and Z are values according to the compressive strength of the rock of the currently mined coal seam.

[0011] Further, when the compressive strength of the rock ranges from 40 MPa to 80 MPa, X = 2.1, Y = 16, and Z = 2.5; and / or, when the compressive strength of the rock ranges from 20 MPa to 40 MPa, X = 4.7, Y = 19, and Z = 2.2; and / or, when the compressive strength of the rock ranges from 10 MPa to 20 MPa, X = 6.2, Y = 32, and Z = 1.5; and / or, when the compressive strength of the rock is less than 10 MPa, X = 7, Y = 63, and Z = 1.2.

[0012] Further, when the single mining thickness of the mining coal seam is not greater than 3 m or the cumulative mining thickness is less than 15 m, the height H of the fractured zone of the roof of the mining coal seam can be calculated by the following calculation method li : when the compressive strength of the rock ranges from 40 MPa to 80 MPa, ; and / or, when the compressive strength of the rock ranges from 20 MPa to 40 MPa, ; and / or, when the compressive strength of the rock ranges from 10 MPa to 20 MPa, ; and / or, when the compressive strength of the rock is less than 10 MPa, wherein M is the seam thickness of the mining coal seam.

[0013] Further, when the single mining thickness of the mining coal seam is greater than 3 m, the height H of the fractured zone of the roof of the mining coal seam can be calculated by the following calculation method li : when the compressive strength of the rock ranges from 40 MPa to 80 MPa, ; and / or, when the compressive strength of the rock ranges from 20 MPa to 40 MPa, ; and / or, when the compressive strength of the rock is less than 10 MPa, ; wherein M is the seam thickness of the mining coal seam.

[0014] Further, the calculation method of the safety thickness T of the coal rock pillar of the mining coal seam is as follows: ; wherein H b is the thickness of the protective layer of the mining coal seam, and the calculation method of the thickness H b of the protective layer of the mining coal seam is B▪A; wherein, ; M is the seam thickness of the mining coal seam, n is the number of the layered coal, and B is valued according to the compressive strength of the rock of the currently mined coal seam.

[0015] The coal seam fire area influence degree classification method can accurately classify the threat level of the mining coal seam from the fire area, and can obtain the threat type of the mining coal seam from the fire area through the roof fracture development condition of the mining coal seam and the vertical distance between the mining coal seam and the fire area, thereby being beneficial to guiding the mining coal seam to take corresponding fire prevention measures, and solving the problem that the threat degree of the upper coal seam from the fire area is difficult to determine in the prior art. BRIEF DESCRIPTION OF DRAWINGS

[0016] The accompanying drawings, which form a part of the specification, are included to provide a further understanding of the application and are incorporated herein in conjunction with the description of the application. The drawings are as follows:

[0017] Figure 1 A structural schematic diagram of an embodiment of the roof of the mining coal seam according to the application is shown;

[0018] Figure 2 A flowchart of the coal seam fire area influence degree classification method of the application is shown. DETAILED DESCRIPTION

[0019] It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other without conflict. The application will be described in detail below with reference to the drawings and in combination with the embodiments.

[0020] Reference Figure 1 , Figure 2 The coal seam fire area influence degree classification method of the embodiment is used to determine the threat degree of the mining coal seam from the fire area in the coal mine, and the coal seam fire area influence degree classification method comprises the following steps: confirming the minimum distance D between the mining coal seam and the fire area; calculating the height H m of the caving zone of the roof of the mining coal seam; li calculating the height H m of the fracture zone of the roof of the mining coal seam; li calculating the safety thickness T of the coal rock pillar for preventing the coal rock layer from collapsing after mining; and classifying the threat level of the mining coal seam from the fire area according to the values of D, H m , H li and T; when D>T, it is determined that the threat level of the mining coal seam from the fire area is III; when H li <D≤T, it is determined that the threat level of the mining coal seam from the fire area is II; when H m <D≤H li , it is determined that the threat level of the mining coal seam from the fire area is I; and when D≤H mWhen the threat level of the mining coal seam to the fire area is III, the mining coal seam is in a safe state. When the threat level of the mining coal seam to the fire area is II, the mining coal seam has a risk of existence of toxic and harmful gases. When the threat level of the mining coal seam to the fire area is I, the mining coal seam has a risk of existence of toxic and harmful gases, and the risk of existence of toxic and harmful gases is relatively large. When the threat level of the mining coal seam to the fire area is 0, the mining coal seam is likely to produce an open fire.

[0021] Specifically, when the threat level of the mining coal seam to the fire area is III, the mining coal seam is in a safe state. When the threat level of the mining coal seam to the fire area is II, the mining coal seam has a risk of existence of toxic and harmful gases. When the threat level of the mining coal seam to the fire area is I, the mining coal seam has a risk of existence of toxic and harmful gases, and the risk of existence of toxic and harmful gases is relatively large. When the threat level of the mining coal seam to the fire area is 0, the mining coal seam is likely to produce an open fire.

[0022] In some embodiments, when the conditions of the mining coal seam change significantly, the above steps are repeated.

[0023] In the coal seam fire area influence degree division method of the embodiment, before confirming the minimum distance D between the mining coal seam and the fire area, the size of the maximum inclination angle of the extension direction of the layer position of the fire area relative to the horizontal direction is first judged. If the maximum inclination angle is greater than 35°, mining is prohibited below the fire area.

[0024] In the coal seam fire area influence degree division method of the embodiment, when the inclination angle of the mining coal seam relative to the horizontal direction is in the range of 0° to 54°, the height H m of the caving zone of the roof of the mining coal seam is calculated according to the lithology of the rock of the roof of the mining coal seam, and the lithology of the rock of the roof of the mining coal seam is judged according to the compressive strength of the rock of the roof of the mining coal seam. li

[0025] In the coal seam fire area influence degree division method of the embodiment, when the compressive strength of the rock of the roof of the mining coal seam is greater than 80 MPa, the height H m of the caving zone of the roof of the mining coal seam can be calculated by using the following calculation formula: ; wherein M is the coal seam thickness of the mining coal seam; k is the crushing expansion coefficient of the falling rock; and is the coal seam inclination angle of the mining coal seam.

[0026] ​In the coal seam affected area influence degree classification method of the embodiment, when the compressive strength of the rock of the roof of the mining coal seam is not greater than 80 MPa, the height H of the caving zone of the roof of the mining coal seam can be calculated by using the following calculation formula m : ; wherein, M is the coal seam mining thickness of the mining coal seam, and W is the roof subsidence height value in the rock caving process of the mining coal seam.

[0027] In the coal seam affected area influence degree classification method of the embodiment, when the mining coal seam needs to be mined in layers, and the single layer mining thickness is in the range of 1 m to 3 m, and the cumulative mining thickness is less than 15 m, the height H of the caving zone of the roof of the mining coal seam can be calculated by using the following calculation method m : ; wherein, M is the coal seam mining thickness of the mining coal seam, and X, Y, and Z are valued according to the compressive strength of the rock of the current mining coal seam.

[0028] In the coal seam affected area influence degree classification method of the embodiment, when the compressive strength of the rock is in the range of 40 MPa to 80 MPa, X=2.1, Y=16, and Z=2.5; and / or, when the compressive strength of the rock is in the range of 20 MPa to 40 MPa, X=4.7, Y=19, and Z=2.2; and / or, when the compressive strength of the rock is in the range of 10 MPa to 20 MPa, X=6.2, Y=32, and Z=1.5; and / or, when the compressive strength of the rock is less than 10 MPa, X=7, Y=63, and Z=1.2.

[0029] In the coal seam affected area influence degree classification method of the embodiment, when the single mining thickness of the mining coal seam is not greater than 3 m, or the cumulative mining thickness is less than 15 m, the height H of the fractured zone of the roof of the mining coal seam can be calculated by using the following calculation method li : when the compressive strength of the rock is in the range of 40 MPa to 80 MPa, ; and / or, when the compressive strength of the rock is in the range of 20 MPa to 40 MPa, ; and / or, when the compressive strength of the rock is in the range of 10 MPa to 20 MPa, ; and / or, when the compressive strength of the rock is less than 10,

[0030] ; wherein, M is the coal seam mining thickness of the mining coal seam.

[0031] In the coal seam affected area influence degree classification method of the embodiment, when the single mining thickness of the mining coal seam is greater than 3 m, the height H of the fractured zone of the roof of the mining coal seam can be calculated by using the following calculation method li :

[0032] When the compressive strength of the rock ranges from 40 MPa to 80 MPa, ; and / or,

[0033] When the compressive strength of the rock ranges from 20 MPa to 40 MPa, ; and / or,

[0034] When the compressive strength of the rock is less than 10 MPa, ;

[0035] wherein M is the seam thickness of the mining seam.

[0036] In the method for classifying the influence degree of the fire area on the mining seam in the embodiment, the calculation method of the safety thickness T of the coal rock pillar of the mining seam is as follows:

[0037] ;

[0038] wherein H b is the thickness of the protective layer of the mining seam, and the calculation method of the thickness H b of the protective layer of the mining seam is B▪A;

[0039] wherein, ; M is the seam thickness of the mining seam, n is the number of the coal layering, and B is valued according to the compressive strength of the rock of the currently mined seam.

[0040] The classification method of the embodiment is described as follows:

[0041] Referring to Table 1

[0042] Table 1 Classification standard of the threat level of the mining seam affected by the fire area

[0043]

[0044] Calculation method of the caving zone height (for the seam with the inclination angle of 0°~54°):

[0045] (1) If there is an extremely hard rock layer in the overburden of the seam roof, and a suspended roof can be formed after mining, the height of the caving zone below the suspended roof can be calculated by the following formula:

[0046]

[0047] In the formula, M is the seam thickness, m;

[0048] k is the fragmentation and swelling coefficient of the caving rock;

[0049] is the inclination angle of the seam.

[0050] (2) When the roof strata of the coal seam are hard, medium-hard, weak, very weak, or interbedded, the maximum height of the caving zone for mining a single coal seam can be calculated using the following formula:

[0051]

[0052] where W is the roof subsidence value during caving.

[0053] (3) When the roof strata of the coal seam are hard, medium-hard, weak, very weak, or interbedded, the maximum height of the caving zone for mining a single coal seam can be calculated using the following formula:

[0054] Table A.1 Formula table for calculating the caving zone of thick coal seam mining

[0055]

[0056] Note: is the cumulative mining thickness, m.

[0057] (4) For a single coal seam thickness exceeding 3.0m and fully mechanized caving mining conditions, the following method is used to determine:

[0058] When the overburden strata of the coal seam are medium-hard and weak, the maximum height of the caving zone during mining can be calculated using the formula in Table A.2.

[0059] Table A.2 Formula table for calculating the caving zone under fully mechanized caving mining conditions

[0060]

[0061] Method for calculating the safety thickness of overburden coal and rock pillars

[0062] B.1 The safety thickness of overburden coal and rock pillars should be greater than or equal to the height of the post-mining fissure zone Hli of the working face plus the thickness of the protective layer H b i.e.

[0063]

[0064] B.2 For mining conditions where the thickness of a single coal seam does not exceed 3.0m or the cumulative mining thickness of a single coal seam is less than 15m, the calculation method is as follows:

[0065] 1) In coal seams with a dip angle of 0° to 54°:

[0066] When the overburden strata of the coal seam are hard, medium-hard, weak, very weak, or interbedded, the maximum height of the fissure zone for mining a single coal seam can be calculated using the formula in Table B.1:

[0067] Table B.1 Formula table for calculating the height of the fissure zone of thick coal seam mining

[0068]

[0069] B.3 For the conditions of mining a coal seam with a thickness of more than 3.0 m at one time and fully mechanized mining, the maximum height of the fissure zone of the overburden during mining can be calculated using the formula in Table B.3, and the maximum value is selected as the maximum development height of the fissure zone of the overburden.

[0070] Table B.3 Table of formulae for calculating the height of the fissure zone under the conditions of fully mechanized mining

[0071]

[0072] Note: n - number of coal sub-layers; h - vertical height of a small phase of a coal mining face, m; mc - thickness of a coal seam, m.

[0073] B.4 When mining a close distance coal seam group, the calculation of the height of the fissure zone should be calculated according to different situations:

[0074] 1) When the vertical distance h between the upper and lower coal seams is greater than the height of the caving zone generated when the lower coal seam is mined, the height of the fissure zone of each coal seam can be calculated using the formulae in Table B.1, Table B.2 and Table B.3, respectively, according to the thickness of the upper and lower coal seams, and the maximum height value is taken as the fissure zone height of the two coal seams.

[0075] 2) When the caving zone of the lower coal seam contacts or completely enters the range of the upper coal seam, the fissure zone height of the upper coal seam is calculated according to the thickness of the coal seam, and the fissure zone height of the lower coal seam is calculated according to the combined thickness of the upper and lower coal seams, and the maximum height value is taken as the maximum height of the fissure zone of the two coal seams.

[0076] The combined mining thickness of the upper and lower coal seams can be calculated using the following formula:

[0077]

[0078] In the formula: M1, M2 - thickness of the upper and lower coal seams; h1-2 - vertical distance between the upper and lower coal seams; y2 - ratio of the caving zone height of the lower coal seam to the mining thickness.

[0079] If the distance between the upper and lower coal seams is very small, the combined mining thickness is the cumulative thickness:

[0080]

[0081] B.5 Method for determining the thickness of a protective layer

[0082] For coal seams with a dip angle of 0°~54°

[0083] (1) For the conditions of mining a coal seam with a thickness of not more than 3.0 m at one time or sub-layer mining with a cumulative mining thickness of less than 15 m, the values in Table B.4 can be selected.

[0084] Table B.4 Safety coal pillar protection layer thickness (not applicable to fully mechanized caving mining)

[0085] Unit: m

[0086]

[0087] Note: , m.

[0088] For the condition of once mining coal seam thickness exceeding 3.0m and fully mechanized caving mining, when the overburden rock is medium hard and soft, the protection layer thickness is 3A~4A; when the overburden rock is hard, the protection layer thickness is 5A.

[0089] From the above description, it can be seen that the above-mentioned embodiments of the present application achieve the following technical effects:

[0090] By using the above-mentioned coal seam affected degree division method, the threat level of the mining coal seam affected by the fire area can be accurately divided, and the mining coal seam threat type can be obtained through the roof fracture development condition of the mining coal seam and the vertical distance between the mining coal seam and the fire area, thereby being beneficial to guiding the mining coal seam to take corresponding fire prevention measures, and solving the problem that the threat degree of the upper coal seam fire area to the mining coal seam is difficult to judge in the prior art.

[0091] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments in accordance with the present application. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and / or "comprising," when used in this specification, specify the presence of stated features, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, steps, operations, elements, components, and / or groups thereof.

[0092] The relative arrangement of parts and steps, numerical expressions, and numerical values set forth in the examples herein are not intended to limit the scope of the present application, unless otherwise specifically stated. It will be further understood that the dimensions of the various parts shown in the drawings are not necessarily to scale, for illustrative purposes. Techniques, methods, and apparatus known to those of ordinary skill in the relevant art can not be discussed in detail, but should be considered as if the disclosure was incorporated by reference in its entirety. In all examples shown and discussed herein, any specific values are to be interpreted as merely exemplary, and not as a limitation. Thus, other examples of example embodiments can have different values. It should be noted that like reference numerals and letters refer to like items in the following drawings, and thus, once an item is defined in one drawing, it need not be discussed further in subsequent drawings.

[0093] In the description of the present application, it should be understood that the orientation words such as "front, back, upper, lower, left, right", "transverse, vertical, perpendicular, horizontal" and "top, bottom" and the like indicated orientation or position relationship are generally based on the orientation or position relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, without the opposite description, these orientation words do not indicate and imply that the device or element indicated must have a particular orientation or be constructed and operated in a particular orientation, therefore it cannot be understood as a limitation on the scope of protection of the present application; the orientation words "inner, outer" refer to the inner and outer of the contour of each component itself.

[0094] For the convenience of description, spatial relative terms such as "over", "above", "upper surface", "upper" and the like can be used herein to describe the spatial positional relationship of one device or feature with other devices or features as shown in the drawings. It should be understood that the spatial relative terms are intended to include different orientations in use or operation in addition to the orientation of the device described in the drawings. For example, if the device in the drawings is inverted, the device described as "above" or "over" other devices or structures will be positioned "below" or "under" other devices or structures. Thus, the exemplary term "above" can include both "above" and "below" orientations. The device can also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatial relative descriptions used herein are interpreted accordingly.

[0095] In addition, it should be noted that the use of "first", "second" and the like words to define parts only facilitates the differentiation of corresponding parts, and the above words have no special meaning unless otherwise stated, and therefore cannot be understood as a limitation on the scope of protection of the present application.

[0096] The above only describes the preferred embodiments of the present application and is not intended to limit the present application. For those skilled in the art, the present application can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application shall be included in the scope of protection of the present application.

Claims

1. A method for classifying the degree of influence of coal seam fire zones, used to determine the degree of threat posed by underground fire zones to the mined coal seam, characterized in that, The method for classifying the degree of influence of the coal seam fire zone includes: Determine the minimum distance D between the coal seam being mined and the ignition zone; Calculate the height H of the caving zone of the roof of the coal seam. m ; Calculate the height H of the fracture zone in the roof of the coal seam. li ; Calculate the safe thickness T of the coal pillar used to prevent collapse after mining of the coal seam; According to the obtained D and H m , H li and the value of T, classify the threat level of the fire area to the extracted coal seam; when D > T, determine that the threat level of the fire area to the extracted coal seam is level III; when H li < D ≤ T, determine that the threat level of the fire area to the extracted coal seam is level II; when H m < D ≤ H li , determine that the threat level of the fire area to the extracted coal seam is level I; when D ≤ H m , determine that the threat level of the fire area to the extracted coal seam is level 0; The threat level of the ignition zone to the coal seam increases sequentially from Level III, Level II, Level I, to Level 0. The method for calculating the safe thickness T of the coal-rock pillar in the mined coal seam is as follows: ； Among them, H b The thickness of the protective layer for the coal seam being mined.

2. The method for classifying the degree of influence of coal seam fire zone according to claim 1, characterized in that, Before confirming the minimum distance D between the coal seam to be mined and the ignition zone, the maximum dip angle of the extension direction of the ignition zone relative to the horizontal direction is determined. If the maximum dip angle is greater than 35°, mining is prohibited below the ignition zone.

3. The method for classifying the degree of influence of coal seam fire zone according to claim 1, characterized in that, When the dip angle of the coal seam relative to the horizontal direction ranges from 0° to 54°, the height H of the caving zone of the roof of the coal seam is determined based on the lithology of the rock in the roof. m and the height H of the fracture zone in the roof of the coal seam being mined li Calculations are performed to determine the lithology of the rock in the roof based on its compressive strength.

4. The method for classifying the degree of influence of coal seam fire zone according to claim 3, characterized in that, When the compressive strength of the roof rock of the coal seam being mined is greater than 80 MPa, the height H of the caving zone of the roof of the coal seam can be calculated using the following formula. m : ； Where M is the coal seam thickness; k is the coefficient of rock fragmentation. The dipping angle of the coal seam being mined is denoted as .

5. The method for classifying the degree of influence of coal seam fire zone according to claim 3, characterized in that, When the compressive strength of the roof rock of the coal seam being mined is not greater than 80 MPa, the height H of the caving zone of the roof of the coal seam can be calculated using the following formula. m : ； Where M is the coal seam thickness, and W is the roof subsidence height during the rock caving process of the coal seam.

6. The method for classifying the degree of influence of coal seam fire-affected zones according to claim 3, characterized in that, When the coal seam to be mined requires layered mining, and the thickness of a single layer ranges from 1m to 3m, with a cumulative mining thickness of less than 15m, the height H of the caving zone of the roof of the coal seam can be calculated using the following method. m : ； Where M is the coal seam thickness, and X, Y, and Z are determined based on the compressive strength of the rock in the currently mined coal seam.

7. The method for classifying the degree of influence of coal seam fire zone according to claim 6, characterized in that, When the compressive strength of the rock ranges from 40 MPa to 80 MPa, X = 2.1, Y = 16, Z = 2.5; and / or, When the compressive strength of the rock ranges from 20 MPa to 40 MPa, X = 4.7, Y = 19, Z = 2.2; and / or, When the compressive strength of the rock ranges from 10 MPa to 20 MPa, X = 6.2, Y = 32, Z = 1.5; and / or, When the compressive strength of the rock is less than 10 MPa, X=7, Y=63, Z=1.

2.

8. The method for classifying the degree of influence of coal seam fire-affected zones according to claim 3, characterized in that, When the thickness of a single mining operation of the coal seam is no more than 3m, or the cumulative mining thickness is less than 15m, the height H of the fracture zone in the roof of the coal seam can be calculated using the following method. li : When the compressive strength of the rock ranges from 40 MPa to 80 MPa, ; and / or, When the compressive strength of the rock ranges from 20 MPa to 40 MPa, ; and / or, When the compressive strength of the rock ranges from 10 MPa to 20 MPa, ; and / or, When the compressive strength of the rock is less than 10 MPa, ; Where M is the coal seam thickness of the coal seam being mined.

9. The method for classifying the degree of influence of coal seam fire-affected zones according to claim 3, characterized in that, When the thickness of a single mining operation of the coal seam is greater than 3m, the height H of the fracture zone in the roof of the coal seam can be calculated using the following method. li : When the compressive strength of the rock ranges from 40 MPa to 80 MPa, ; and / or, When the compressive strength of the rock ranges from 20 MPa to 40 MPa, ; and / or, When the compressive strength of the rock is less than 10 MPa, ; Where M is the coal seam thickness of the coal seam being mined.

10. The method for classifying the degree of influence of coal seam fire-affected zones according to claim 1, characterized in that, The thickness H of the protective layer of the mined coal seam b The calculation method is B·A; in, M is the coal seam thickness, n is the number of coal layers, and B is determined based on the compressive strength of the rock in the currently mined coal seam.

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