A regional hazard classification under a combination fault and a solution

Abstract

The application provides a regional danger grade division and solution under combination faults, relates to the technical field of coal mine safety, and specifically comprises the following steps: obtaining a fault ground stress increment matrix and combination faults, obtaining the influence range and peak influence range of each combination fault structure according to the combination faults and the ground stress increment matrix, obtaining the plastic zone range and elastic zone range according to the basic data of the faults and the working face, obtaining the advanced regional danger grade of the combination faults according to the combination fault structure influence range and the fault structure peak range, and executing corresponding measures according to the danger grade. The application dynamically considers the interaction between the faults and the coupling relationship with the advanced abutment stress, is helpful to accurately evaluate the potential rock burst risk, establishes the rock burst danger prevention and control system of "fault structure-advanced abutment stress", and correctly controls the contradiction between the advanced pressure relief strength, range and cost of the crossheading.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of coal mine safety, in particular to a regional danger grade division and solution under combined faults. BACKGROUND

[0002] The output of underground mines in China accounts for more than 85% of the total output, and faults, as a kind of geological structure commonly existing in the form of complex combination in underground mines, often interact with mining activities to induce larger-scale rock burst. Therefore, in actual mining work, the advanced position of the crossheading at both ends of the working face needs to be strengthened by blasting to unload pressure to ensure the safe conduct of mining activities.

[0003] In the production safety planning of multi-fault mines, the hazard of multiple faults is statically evaluated by a single fault system, and the problem of not dynamically considering the coupling between faults and faults, and the coupling between fault structure stress and advanced support stress is common. In the production of multi-fault mines, the combination of faults and faults is complex, and the coupling factors between fault structure stress and advanced support stress are various, making it difficult to correctly establish a "fault structure-advanced support stress" impact danger and anti-impact system. In the production operation of combined fault mines, the energy released and the range of damage caused by the rock burst caused by combined faults are indefinite, while the advanced pressure relief scheme of the crossheading at both ends of the working face tends to be a mechanical design with fixed distance and quantity, making it difficult to correctly control the contradiction between the unloading strength, range and cost of the crossheading.

[0004] The above information disclosed in the background section is only used to enhance the understanding of the background of the present disclosure, and therefore it can include information that does not constitute prior art known to those of ordinary skill in the art. SUMMARY

[0005] The purpose of the present application is to provide a regional danger grade division and solution under combined faults to solve the problems raised in the background.

[0006] To achieve the above purpose, the present application provides the following technical solutions:

[0007] A regional danger grade division and solution under combined faults, the specific steps comprising:

[0008] S1. Constructing the profile and plan view of the combined fault and the working face, collecting the basic data of the fault and the working face, including the throw of each fault, the in-situ stress of the unstructured area, the vertical stress around the fault, the horizontal stress, the average unit weight of the overburden rock, the coal seam depth, the coal seam thickness, the stress concentration coefficient of the coal and rock strata, the residual stress of the surrounding rock, the friction coefficient of the micro unit in the plastic zone of the coal body, the internal friction angle of the coal body, and the lateral pressure coefficient of the coal body;

[0009] S2. Obtain the calculated dip angle and plane grid matrix of the fault in the combined fault according to the profile and plan view of the combined fault and working face, vertical stress, and horizontal stress, obtain the ground stress increment matrix of the fault according to the calculated dip angle and plane grid matrix of the fault in the combined fault, obtain the influence range of each fault according to the ground stress increment matrix of the fault, judge the combination relationship of the fault according to the influence range of each fault, and obtain the combined fault;

[0010] S3. Obtain the ground stress increment matrix of the combined fault according to the fault contained in the combined fault and the ground stress increment matrix, obtain the ground stress influence range and the ground stress peak value influence range of the combined fault according to the ground stress increment matrix of the combined fault;

[0011] S4. Obtain the throw influence range and throw peak value influence range of each combined fault structure according to the throw of each fault and the combined fault, and obtain the throw influence range and throw peak value influence range of each combined fault structure according to the effective throw of the combined fault;

[0012] S5. Obtain the influence range and peak value influence range of the combined fault structure according to the ground stress influence range, ground stress peak value influence range, throw influence range and throw peak value influence range of the combined fault structure;

[0013] S6. Perform data processing on the average unit weight of overburden rock, coal seam depth, coal seam thickness, stress concentration coefficient of coal and rock layer, residual stress of surrounding rock, friction coefficient of micro unit in plastic zone, and coal internal friction angle to generate the plastic zone range, and perform data processing on the lateral pressure coefficient of coal, coal seam thickness, stress concentration coefficient, and friction coefficient of micro unit in plastic zone to generate the elastic zone range;

[0014] S7. Divide the working face into a working face facing stage and a working face away stage, and judge the danger level of the combined fault in advance according to the influence range of the combined fault structure, the peak value influence range of the combined fault structure, the plastic zone range and the elastic zone range, and perform corresponding measures according to the danger level.

[0015] Further, a vertical profile along the working face roadway is made, and a fault profile line is obtained, four inflection points with large slope changes are found in the fault profile line, the included angle and length are counted, and the calculation formula is:

[0016]

[0017] Where, L i is the fault length, θ i is the calculated dip angle of the i-th fault, i is the index of the fault, the value range of i is [1, I], I is the number of faults penetrating the working face, and θi1 , θ i2 , θ i3 , and θ i4 are the first, second, third, and fourth inflection angles of the fault profile line and the horizontal line, respectively, h i1 , h i2 , h i3 , and h i4 are the first, second, third, and fourth inflection line lengths of the fault profile line in the vertical profile diagram;

[0018] On the fault profile diagram, a Cartesian coordinate system xoy is established with the working face horizontal midpoint as the center, the actual I fault relative profile relationship as the radius, and the working face advancing direction as the positive half-axis direction of the x-axis, and an arbitrary point relative to the fault is represented by a moving point M;

[0019] Six plane grid matrices of the same size and corresponding to the Cartesian coordinate system are established, the number of rows and columns of the plane grid matrices is m, and the plane grid matrices include distance matrices and angle matrices, and the elements of the six plane grid matrices are corresponding to the Cartesian coordinate system plane;

[0020] The elements of the six plane grid matrices are:

[0021]

[0022] The position of the matrix element a mm is (m, m);

[0023] The corresponding relationship between the element position of the plane grid matrix and the coordinates in the Cartesian coordinate system is:

[0024]

[0025] Where (x, y) M are the coordinates of the point M in the Cartesian coordinate system, x and y are the horizontal and vertical coordinates of the point M in the Cartesian coordinate system, respectively, is the element position of the plane grid matrix, and are the horizontal and vertical coordinates of the point M in the plane grid matrix, respectively, m The size of the maximum value of the fault length L i is twice the maximum value, m = 2Max(L1, L2,..., L i );

[0026] l i1 , l i2 , l i3 are the distances from the moving point M(x, y) to the fault points D i1 , D i2 , D i3the distance between the moving point M and the fault point D i1 , l i2 , l i3 , and the distance matrix is obtained;

[0027] α i1 , α i2 , α i3 are the angles between the connecting lines of the moving point M (x, y) and the fault points D i1 , D i2 , D i3 and the positive direction of the x-axis in the Cartesian coordinate system, and the angle matrix is obtained by using α i1 , α i2 , α i3 ;

[0028] D i1 , D i2 , D i3 are the upper end point, the middle point and the lower end point of the i-th fault in the profile.

[0029] Further, the i-th fault stress increment matrix is calculated according to the following formula:

[0030] Vσ i = Max (|Vσ xi |, |Vσ yi |, |Vσ xyi |)

[0031] Vσ xi = -σ i (A i -B i -1)

[0032] Vσ yi = -σ i (1-A i -B i )

[0033] Vσ xyi = -σ i C i

[0034]

[0035]

[0036] wherein Vσ i is the i-th fault stress increment matrix, Vσ xi is the stress increment along the x direction on the i-th fault, Vσ yi is the stress increment along the y direction on the i-th fault, and Vσ xyiis the increment of shear stress on the i-th fault, σ i is the simulated dip angle of the i-th fault, A i is the distance from the moving point M to the fault point D i3 is the distance from the moving point M to the fault point D i1 and D i2 is the ratio parameter between the distance from the moving point M to the fault point D i and the distance from the moving point M to the fault point D i3 is the ratio parameter between the distance from the moving point M to the fault point D i and the angle, C i2 is the ratio parameter between the distance and the angle from the moving point M to the fault point D hi is the horizontal ground stress of the i-th fault, σ vi is the vertical ground stress of the i-th fault.

[0037] Further, according to the ground stress increment matrix of the i-th fault, the influence range of each fault is obtained, and the specific steps are as follows:

[0038] According to the ground stress increment matrix Vσ i of the i-th fault, the stress increment curve of the working face under the influence of I faults is obtained, and according to the stress increment curve, the influence range of each fault is obtained, and the formula is as follows:

[0039] x i =(x i1 +x i2 ) / 2

[0040] Wherein, x i is the influence range of the i-th fault, x i1 and x i2 are the influence ranges on both sides of the i-th fault, defined as the two critical distances on both sides of the i-th fault to the stress increment reaching the original rock stress σ0, σ0 refers to the stress borne by the rock itself when not subjected to external force;

[0041] According to the influence range x i of the i-th fault and the relative position of the fault, the combination relationship of I faults is judged, and the specific process is as follows:

[0042] Satisfies:

[0043] L dtc <(x a +x b )

[0044] x a =(x a1 +x a2 ) / 2

[0045] x b =(xb1 +x b2 ) / 2

[0046] L dtc =Min(L dtc1 ,L dtc2 ,L dtc3 ,L dtc4 ,L dtc5 )

[0047] x a is the influence range of fault a, x b is the influence range of fault b, x a1 and x a2 are the two critical distances on both sides of fault a when the stress increment reaches the original rock stress σ0, x b1 and x b2 are the two critical distances on both sides of fault b when the stress increment reaches the original rock stress σ0, L dtc1 , L dtc2 , L dtc3 , L dtc4 , L dtc5 L is the length of the segment of the propulsion line sandwiched between the two fault planes, dtc is the minimum value among them;

[0048] The distance L between fault a and fault b dtc If it is smaller than the sum of the influence ranges of the two faults, then fault a and fault b are combined faults;

[0049] By combining all faults, we can get the combined relationship of the faults and obtain J combined faults.

[0050] Furthermore, the ground stress increment matrix of the j-th combined fault is obtained:

[0051] VΦ j =Max(Vσ xa +Vσ xb |,|Vσ ya +Vσ yb |,Vσ xya +Vσ xyb |)

[0052] Among them, VΦ j is the ground stress increment matrix of the jth combined fault, a∈[1,I]∩b∈[1,I]∩a≠b, Vσ xa 、Vσ ya 、Vσ xya are the stress increment along the x direction, the stress increment along the y direction, and the shear stress increment on the ath fault, Vσ xb 、Vσ yb 、Vσ xybrespectively are the stress increment along x direction, the stress increment along y direction and the increment of shear stress on the bth fault respectively;

[0053] According to the stress increment matrix VΦ of the jth combination fault j , the stress increment curve of the working face level under the influence of the jth combination fault is obtained, and the formula of the stress influence range and the peak influence range of the jth combination fault is obtained according to the stress increment curve of the working face level under the influence of the combination fault as follows:

[0054] X1, j = Max(x j1 , x j2 )

[0055] X, 2j = Max(x j3 , x j4 )

[0056] Wherein, X1, j is the stress influence range of the jth combination fault, X, 2j is the peak stress influence range of the jth combination fault, x j1 and x j2 are the influence ranges on both sides of the jth combination fault, which are defined as two critical distances from the combination fault to the stress increment reaching the original rock stress σ0, x j3 and x j4 are the peak ranges on both sides of the jth combination fault, which are defined as two critical distances from the combination fault to the stress increment reaching 10σ0 of the original rock stress.

[0057] Further, according to the drop of each fault and the J combination faults, the drop influence range and the drop peak influence range of each combination fault structure are obtained, and the specific process is as follows:

[0058] The effective drop of the jth combination fault is obtained, and the calculation formula is as follows:

[0059]

[0060] Wherein, LLC j is the effective drop of the jth combination fault, LC i is the drop of the ith fault, L dtc-Min and L dtc-Max are the minimum and maximum distances between the faults in the combination fault respectively;

[0061] According to the effective drop of the jth combination fault, the formula of the drop influence range and the drop peak influence range of the jth combination fault structure is obtained as follows:

[0062]

[0063] Among them, Y 1j is the drop influence range of the jth combined fault, Y 2j is the impact range of the peak drop of the jth combined fault;

[0064] According to the j-th combined fault stress influence range X1, j , the impact range of the peak ground stress X, 2j , the impact range of the combined fault structure Y 1j And the drop peak impact range Y 2j , obtain the influence range and peak influence range of the j-th combined fault structure, based on the following formula:

[0065] Z 1j =Max(X1, j ,Y 1j )

[0066] Z 2j =Max(X2, j ,Y 2j )

[0067] Among them, Z 1j is the combined fault structure influence range of the jth combined fault, Z 2j is the combined fault structure peak influence range of the jth combined fault.

[0068] Furthermore, in step S6, the specific formula for obtaining the plastic zone range and the elastic zone range is as follows:

[0069]

[0070] Among them, X et is the plastic zone range, X pt is the elastic region, kγH is the X et The stress peak is at the point where H is the depth of the coal seam, γ is the average density of the coal seam overburden, k is the stress concentration coefficient, σ r is the residual stress of the surrounding rock, is the internal friction angle of the coal body, f is the friction coefficient of the small unit in the plastic zone, p is the thickness of the coal seam, and λ is the lateral pressure coefficient of the coal body.

[0071] Furthermore, in step S7, the specific process of obtaining the regional hazard level of the combined fault advance and executing corresponding measures according to the hazard level is as follows:

[0072] The regional advance of the combined fault is divided into two stages: the working face approach stage and the working face divergence stage;

[0073] Working surface facing stage:

[0074] The influence range Z of the j-th combined fault structure 1j , plastic zone range X et and elastic range X pt Add up and set the plastic zone range X et and the peak influence range Z of the jth combined fault structure 2j Add the sum, and the summed values ​​are all equal to D + For comparison:

[0075] When D + >Z 1j +X et +X pt , indicating that the combined fault advance regionality is a general dangerous area, and roof blasting and coal blasting are required;

[0076] When X et +Z 2j <D + ≤Z 1j +X et +X pt , indicating that the combined fault advance regionality is a medium-risk area, which requires roof blasting, coal blasting and large-diameter drilling to relieve pressure;

[0077] When 0≤D + ≤X et +Z 2j , indicating that the combined fault advance area is a dangerous area, which requires roof blasting, coal blasting, and large-diameter drilling to relieve pressure. In addition, roof and large-diameter densification treatment is also required;

[0078] Working face departure stage:

[0079] The influence range Z of the j-th combined fault structure 1j , plastic zone range X et and elastic range X pt Add up and set the plastic zone range X et and the peak influence range Z of the jth combined fault structure 2j Add the sum, and the summed values ​​are all equal to D - For comparison:

[0080] When D - ≤X et +Z 2j , indicating that the combined fault advance area is a dangerous area, which requires roof blasting, coal blasting, and large-diameter drilling to relieve pressure. In addition, roof and large-diameter densification treatment is also required;

[0081] When X et +Z 2j <D - ≤Z 1j+X et +X pt , indicating that the combined fault advance regionality is a medium-risk area, which requires roof blasting, coal blasting, and large-diameter drilling to relieve pressure;

[0082] D - >Z 1j +X et +X pt , indicating that the combined fault advance regionality is a general dangerous area, and roof blasting and coal blasting are required;

[0083] D + It indicates the distance from the nearest fault in the fault group when the working face is excavated towards the fault group, D - It indicates the distance from the nearest fault in the fault group when the working face advances away from the fault group.

[0084] Compared with the prior art, the present invention has the following beneficial effects:

[0085] The present invention constructs cross-sectional and plan views of combined faults and working surfaces, collects basic data of the faults and working surfaces, obtains fault stress increment matrix and combined faults based on the cross-sectional and plan views of the combined faults and working surfaces, original rock stress in non-structural areas, vertical stress and horizontal stress around the faults, obtains the fault stress increment matrix and the combined faults, obtains the influence range and peak influence range of each combined fault structure based on the combined faults, the stress increment matrix and the drop of each fault, obtains the plastic zone range and elastic zone range based on the average bulk density of the coal seam overburden, the coal seam burial depth and thickness, the stress concentration coefficient, the residual stress of the surrounding rock, the friction coefficient of the micro-units in the plastic zone, the friction angle of the coal body and the lateral pressure coefficient of the coal body, obtains the advanced regional hazard level of the combined fault based on the influence range of the combined fault structure and the fault structure peak range, plastic zone range and elastic zone range, and implements corresponding measures based on the hazard level. Therefore, by constructing cross-sectional and plan views of the combined faults and working faces, and dynamically considering the interaction between the faults and the coupling relationship with the advance support stress, a more comprehensive geological structure analysis is provided. This dynamic analysis helps to more accurately assess the potential risk of rock burst, establish a "fault structure-advance support stress" rock burst hazard prevention and control system, and correctly control the contradiction between the intensity, scope and cost of the advance unloading of the horizontal tunnel. BRIEF DESCRIPTION OF THE DRAWINGS

[0086] Figure 1 Schematic diagram of the overall method flow of the present invention;

[0087] Figure 2 The working face plan view and vertical cross-sectional view along the working face lane of the present invention;

[0088] Figure 3 A comparative diagram of the planar sections of the combined fault and the mining area section of the present invention;

[0089] Figure 4 The stress increment nephogram of the fault and the stress increment curve of the working face roadway of the present application;

[0090] Figure 5 The schematic diagram of the fault spacing of the present application;

[0091] Figure 6 The stress increment nephogram of the combined fault and the stress increment curve of the working face roadway of the present application. DETAILED DESCRIPTION

[0092] In order to make the objects, technical solutions and advantages of the present application clearer and more comprehensible, the present application will be further described in detail below in combination with specific embodiments.

[0093] It should be noted that, unless otherwise defined, the technical terms or scientific terms used in the present application should be understood as the general meanings understood by those skilled in the art to which the present application belongs. The terms "first", "second" and similar terms used in the present application do not represent any order, number or importance, but are only used to distinguish different components. The terms "include" or "contain" and similar terms mean that the elements or objects before the terms cover the elements or objects listed after the terms and their equivalents, without excluding other elements or objects. The terms "connect" or "connected" and similar terms are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. The terms "upper", "lower", "left", "right" and the like only represent relative positional relationships, which can change accordingly when the absolute positions of the described objects change.

[0094] Embodiment 1:

[0095] Please refer to Figure 1 The present application provides a technical solution:

[0096] A regional hazard level division and solution under a combined fault, the specific steps comprising:

[0097] S1. Constructing the profile and plan view of the combined fault and the working face, collecting the basic data of the fault and the working face, including the throw of each fault, the in-situ stress of the unstructured area, the vertical stress around the fault, the horizontal stress, the average bulk density of the overburden of the coal seam, the buried depth of the coal seam, the thickness of the coal seam, the stress concentration coefficient of the coal and rock stratum, the residual stress of the surrounding rock, the friction coefficient of the micro unit in the plastic zone of the coal body, the internal friction angle of the coal body and the lateral pressure coefficient of the coal body;

[0098] S2. Obtain the calculated dip angle of the fault in the combined fault and the plane grid matrix according to the profile and plan view of the combined fault and the working face, the vertical stress, the horizontal stress, the plane grid matrix including the distance matrix and the angle matrix, obtain the ground stress increment matrix of the fault according to the calculated dip angle of the fault in the combined fault and the plane grid matrix, obtain the influence range of each fault according to the ground stress increment matrix of the fault, judge the combination relationship of the fault according to the influence range of each fault, and obtain the combined fault;

[0099] S3. Obtain the ground stress increment matrix of the combined fault according to the fault contained in the combined fault and the ground stress increment matrix, obtain the ground stress influence range and the ground stress peak value influence range of the combined fault according to the ground stress increment matrix of the combined fault;

[0100] S4. Obtain the throw influence range and the throw peak value influence range of each combined fault structure according to the throw of each fault and the combined fault, obtain the throw influence range and the throw peak value influence range of each combined fault structure according to the effective throw of the combined fault;

[0101] S5. Obtain the influence range and the peak value influence range of the combined fault structure according to the ground stress influence range, the ground stress peak value influence range, the throw influence range and the throw peak value influence range of the combined fault structure;

[0102] S6. Perform data processing on the average unit weight of overburden rock, the coal seam depth, the coal seam thickness, the stress concentration coefficient of coal and rock, the residual stress of surrounding rock, the friction coefficient of the micro unit in the plastic zone and the internal friction angle of the coal body to generate the plastic zone range, and perform data processing on the lateral pressure coefficient of the coal body, the coal seam thickness, the stress concentration coefficient and the friction coefficient of the micro unit in the plastic zone to generate the elastic zone range;

[0103] S7. Divide the working face into the working face facing stage and the working face away stage, and respectively judge the danger level of the combined fault in the advanced area according to the influence range of the combined fault structure, the peak value influence range of the combined fault structure, the plastic zone range and the elastic zone range, and perform corresponding measures according to the danger level.

[0104] On the basis of the above embodiment, the equipment and method for collecting the throw of each fault, the in-situ stress of the structureless area, the vertical stress and the horizontal stress around the fault, the average unit weight of overburden rock, the coal seam depth, the coal seam thickness, the stress concentration coefficient of coal and rock, the residual stress of surrounding rock, the friction coefficient of the micro unit in the plastic zone of the coal body, the internal friction angle of the coal body and the lateral pressure coefficient of the coal body are as follows:

[0105] Determine the height difference and the throw of the fault by a geological measuring instrument (such as a total station or a GPS);

[0106] Through stress measurement instrument (such as borehole stress meter), by placing sensors in underground boreholes, directly measuring the stress state in the rock, using data acquisition system to monitor and record stress data, usually need to measure multiple times at different time periods to capture the dynamic process of stress change, through the analysis of measurement results, the stress state of the original rock can be obtained, including horizontal stress and vertical stress.

[0107] Through strain gauge, seismic measuring instrument, on-site testing and numerical simulation to calculate the vertical ground stress around the fault;

[0108] Strain gauges are installed in boreholes, and horizontal ground stress is calculated using strain data from strain gauges;

[0109] Through geotechnical testing instrument (such as density meter), calculate the average unit weight of overburden rock of coal seam;

[0110] Through drilling equipment, geological radar to obtain the depth data of coal seam;

[0111] Through drilling sampling and geological profile analysis to obtain the thickness of coal seam;

[0112] Run finite element calculation to obtain stress distribution diagram under external load, calculate stress concentration coefficient for stress concentration area, the calculation formula of stress concentration coefficient is the ratio of maximum stress of a point to average stress of surrounding area;

[0113] Use borehole testing method, drill holes in surrounding rock, hole diameter and depth are selected according to actual situation, carry out local disassembly, observe stress release and deformation, use laser measuring instrument to measure deformation around the borehole, and then calculate residual stress;

[0114] By applying shear force, measure the deformation of coal body under different shear stresses, calculate the friction coefficient through the relationship between shear stress and normal stress;

[0115] Through direct shear test or triaxial shear test, measure the shear deformation of coal body under different stress states, calculate the internal friction angle of coal body through stress-strain curve;

[0116] Through triaxial test, configure corresponding sensors to monitor stress and strain in real time, gradually apply axial stress, maintain a certain confining pressure, record deformation data under different stress conditions, calculate lateral pressure coefficient through test data, lateral pressure coefficient is equal to the ratio of horizontal stress to vertical stress.

[0117] On the basis of the above embodiments, the specific process of step S2 is as follows:

[0118] For example, Figure 2 and Figure 3As shown in the figure, a vertical profile is made along the working face lane with the upper and lower ranges being the length of the fault. In the vertical profile, four inflection points with large slope changes are found and connected to form the fault profile line. The angle and length are calculated. The calculation formula is:

[0119]

[0120] Among them, L i is the fault length, θ i is the calculated dip angle of the i-th fault, i is the index of the fault, the value range of i is [1, I], I is the number of faults passing through the working surface, θ i1 ,θ i2 ,θ i3 and θ i4 are the angles between the first, second, third and fourth inflection points of the fault profile and the horizontal line, h i1 、h i2 、h i3 and h i4 They are the first, second, third and fourth broken line lengths of the fault section line in the vertical section diagram;

[0121] On the fault profile, a Cartesian coordinate system xoy is established with the horizontal midpoint of the working surface as the center of the circle, the actual relative profile relationship of the I faults, and the working surface advancement direction as the positive semi-axis direction of the x-axis. The moving point M represents any point relative to the fault.

[0122] Establish 6 plane grid matrices of the same size (m×m) corresponding to the Cartesian coordinate system. The plane grid matrix includes l i1 、l i2 、l i3 , α i1 , α i2 , α i3 , the number of rows and columns of the plane grid matrix are both m, and the elements of the 6 plane grid matrices correspond to the Cartesian coordinate plane;

[0123] Among them, the elements of the 6 plane grid matrices are:

[0124]

[0125] Among them, the matrix element position is defined as the two subscripts of the matrix element, for example: matrix element a 11 The position is (1, 1), the matrix element a mm The position of is (m, m);

[0126] The corresponding relationship between the element positions of the plane grid matrix and the coordinates in the Cartesian coordinate system is:

[0127]

[0128] Where (x,y) M is the coordinate of point M in the Cartesian coordinate system, x and y are the horizontal and vertical coordinates of point M in the Cartesian coordinate system respectively, is the element position of the plane grid matrix, and are the horizontal and vertical coordinates of point M in the plane grid matrix, m The size of the fault length L i twice the maximum value in L1, L2, ..., L i );

[0129] l i1 、l i2 、l i3 In the Cartesian coordinate system, the moving point M(x, y) is respectively moved to the fault point D i1 、D i2 、D i3 distance, using l i1 、l i2 、l i3 , get the distance matrix;

[0130] α i1 , α i2 , α i3 In the Cartesian coordinate system, the moving point M(x, y) is respectively moved to the fault point D i1 、D i2 、D i3 The angle between the line connecting the two and the positive direction of the x-axis is calculated using α i1 , α i2 , α i3 , get the angle matrix;

[0131] D i1 、D i2 、D i3 are the upper endpoint, midpoint and lower endpoint of the i-th fault in the cross-section respectively;

[0132] Using matrix point operations, the stress increment matrix of the i-th fault is calculated according to the following formula:

[0133] Vσ i =Max(Vσ xi |,|Vσ yi |,|Vσ xyi |)

[0134] Vσ xi =-σ i (A i -B i -1)

[0135] Vσyi =-σ i (1-A i -B i )

[0136] Vσ xyi =-σ i C i

[0137]

[0138] Among them, Vσ i is the ground stress increment matrix of the i-th fault, Vσ xi is the stress increment along the x direction on the i-th fault, Vσ yi is the stress increment along the y direction on the i-th fault, Vσ xyi is the increment of shear stress on the i-th fault, σ i is the simulated inclination of the i-th fault ignoring shear stress, A i From the moving point M to the fault point D i3 The distance from the moving point M to the fault point D i1 and D i2 The ratio parameter between the distances, B i From the moving point M to the fault point D i3 The proportional parameter of the distance and the corresponding angle, C i From the moving point M to the fault point D i2 The proportionality parameter between the distance and the angle, σ hi is the horizontal stress of the i-th fault, σ vi is the vertical stress of the i-th fault.

[0139] According to the fault stress increment matrix, the combination relationship of I fault is determined. The specific steps are as follows:

[0140] like Figure 4 and Figure 5 As shown, according to the ground stress increment matrix Vσ1, Vσ2, ..., Vσ of the i-th fault i ,Vσ Z , obtain the stress increment cloud map and fault stress increment curve of the working face under the influence of I fault, Vσ i is the ground stress increment matrix of the i-th fault;

[0141] Among them, the basic logic of drawing the stress increment cloud map is:

[0142] The ground stress increment matrix Vσ of the i-th fault iThe grid points are laid on the plane according to the relative position of elements in the matrix, the points with the same value on the grid are connected with an interval of 1 MPa, and the stress increment nephogram of I faults is obtained by repeating the above steps;

[0143] The basic logic of drawing the stress increment curve of the fault is as follows:

[0144] Referring to the Cartesian coordinate system, the element position of the matrix and the relative position of the actual fault to the working face, the position of the working face roadway in the stress increment nephogram of the i-th fault is found, and the stress increment curve of the working face is drawn along the horizontal according to the stress increment nephogram;

[0145] The basic logic of obtaining the influence range of the i-th fault according to the stress increment curve of the working face horizontal under the influence of I faults is as follows:

[0146] x i =(x i1 +x i2 ) / 2

[0147] Where x i is the influence range of the i-th fault, x i1 and x i2 are the influence ranges on both sides of the i-th fault, defined as the two critical distances on both sides of the i-th fault to the stress increment reaching the original rock stress σ0, and σ0 refers to the stress borne by the rock itself when not subjected to external force;

[0148] According to the influence range x i of the i-th fault and the relative position of the fault, the combination relationship of I faults is judged, and the specific process is as follows:

[0149] Satisfies:

[0150] L dtc <(x a +x b )

[0151] x a =(x a1 +x a2 ) / 2

[0152] x b =(x b1 +x b2 ) / 2

[0153] L dtc =Min(L dtc1 ,L dtc2 ,L dtc3 ,L dtc4 ,L dtc5 )

[0154] xa is the influence range of fault a, x b is the influence range of fault b, x a1 and x a2 are two critical distances on both sides of fault a to the stress increment reaching the in-situ stress σ0, x b1 and x b2 are two critical distances on both sides of fault b to the stress increment reaching the in-situ stress σ0, L dtc1 , L dtc2 , L dtc3 , L dtc4 , L dtc5 is the length of the line segment between the two fault planes, L dtc is the minimum value of the two;

[0155] If the distance L dtc between fault a and fault b is less than the sum of the influence ranges of the two faults, then the fault a and the fault b are combined faults;

[0156] All faults are combined to determine the combination relationship of the faults, and J combined faults are obtained.

[0157] On the basis of the above embodiment, the geo-stress increment matrix of the jth combined fault is obtained:

[0158] VΦ j = Max (Vσ xa + Vσ xb |, |Vσ ya + Vσ yb |, |Vσ xya + Vσ xyb |)

[0159] Wherein, VΦ j is the geo-stress increment matrix of the jth combined fault, a∈[1, I]∩b∈[1, I]∩a≠b, Vσ xa , Vσ ya , Vσ xya are the stress increment along the x direction, the stress increment along the y direction, and the shear stress increment on the ath fault respectively, Vσ xb , Vσ yb , Vσ xyb are the stress increment along the x direction, the stress increment along the y direction, and the shear stress increment on the bth fault respectively;

[0160] According to the geo-stress increment matrix VΦ j of the jth combined fault, the stress increment curve of the working face under the influence of the jth combined fault is obtained;

[0161] Wherein, the basic logic of drawing the stress increment cloud chart is:

[0162] As Figure 6 shown, the stress increment matrix VΦ j According to the relative position of its elements in the matrix, the grid points are laid on the plane, and the points with the same value on the grid are connected with an interval of 1 MPa, and so on to obtain I stress increment contours;

[0163] The basic logic of drawing the stress increment curve of the working face is as follows:

[0164] Referring to the Cartesian coordinate system, the element position of the matrix and the relative position of the actual fault to the working face, the position of the working face roadway in the stress increment contour is found, and the stress increment curve of the working face is drawn along the horizontal according to the stress increment contour;

[0165] According to the stress increment matrix VΦ j of the jth combined fault, the formula for obtaining the stress influence range and peak influence range of the jth combined fault is as follows:

[0166] X1, j =Max(x j1 ,x j2 )

[0167] X, 2j =Max(x j3 ,x j4 )

[0168] Where X1, j is the stress influence range of the jth combined fault, X, 2j is the stress peak influence range of the jth combined fault, x j1 and x j2 are the influence ranges on both sides of the jth combined fault, which are defined as the two critical distances from the combined fault to the stress increment reaching the original rock stress σ0, x j3 and x j4 are the peak ranges on both sides of the jth combined fault, which are defined as the two critical distances from the combined fault to the stress increment reaching 10σ0 of the original rock stress.

[0169] According to the drop of each fault and the J combined faults, the effective drop of the jth combined fault is obtained, and the specific process is as follows:

[0170]

[0171] Where LLC j is the effective drop of the jth combined fault, LC i is the drop of the ith fault, L dtc-Min , L dtc-Maxrespectively, are the minimum and maximum distances between the combination faults;

[0172] According to the effective throw of the J combination faults, the throw influence range and the throw peak influence range of the jth combination fault structure are obtained according to the following formula:

[0173]

[0174] Y 1j is the throw influence range of the jth combination fault; Y 2j is the throw peak influence range of the jth combination fault;

[0175] According to the ground stress influence range X1, j , the ground stress peak influence range X2, 2j , the throw influence range Y 1j and the throw peak influence range Y 2j of the jth combination fault structure, the influence range and the peak influence range of the jth combination fault structure are obtained according to the following formula:

[0176] Z 1j = Max (X1, j , Y 1j )

[0177] Z 2j = Max (X2, j , Y 2j )

[0178] Wherein, Z 1j is the combination fault structure influence range of the jth combination fault, and Z 2j is the combination fault structure peak influence range of the jth combination fault.

[0179] On the basis of the above embodiment, the specific formula of the plastic zone range and the elastic zone range is as follows:

[0180]

[0181] Wherein, X et is the plastic zone range, X pt is the elastic zone range, kγH is the stress peak value at X et in the plastic zone, H is the coal seam depth, γ is the average unit weight of overburden rock, k is the stress concentration coefficient, σ r is the residual stress of surrounding rock, is the internal friction angle of coal, f is the friction coefficient of the micro unit in the plastic zone, p is the thickness of coal seam, and λ is the lateral pressure coefficient of coal.

[0182] Based on the above embodiment, the specific process of obtaining the regional hazard level of the combined fault advance and executing corresponding measures according to the hazard level is as follows:

[0183] The regional advance of combined faults (working face and lane) is divided into two stages: working face facing stage and working face departing stage;

[0184] Working surface facing stage:

[0185] The influence range Z of the j-th combined fault structure 1j , plastic zone range X et and elastic range X pt Add up and set the plastic zone range X et and the peak influence range Z of the jth combined fault structure 2j Add the sum, and the summed values ​​are all equal to D + For comparison:

[0186] When D + >Z 1j +X et +X pt , indicating that the combined fault advance regionality is a general dangerous area, and roof blasting and coal blasting are required;

[0187] When X et +Z 2j <D + ≤Z 1j +X et +X pt , indicating that the combined fault advance regionality is a medium-risk area, which requires roof blasting, coal blasting and large-diameter drilling to relieve pressure;

[0188] When 0≤D + ≤X et +Z 2j , indicating that the combined fault advance area is a dangerous area, which requires roof blasting, coal blasting, and large-diameter drilling to relieve pressure. In addition, roof and large-diameter densification treatment is also required;

[0189] Working face departure stage:

[0190] The influence range Z of the j-th combined fault structure 1j , plastic zone range X et and elastic range X pt Add up and set the plastic zone range X et and the peak influence range Z of the jth combined fault structure 2j Add the sum, and the summed values ​​are all equal to D - For comparison:

[0191] When D - ≤Xet +Z 2j , which indicates that the combination fault is a dangerous area, and roof blasting, coal blasting, large-diameter drilling pressure relief, and roof and large-diameter encryption processing are required.

[0192] When X et +Z 2j <D - >Z 1j +X et +X pt , which indicates that the combination fault is a medium dangerous area, and roof blasting, coal blasting, and large-diameter drilling pressure relief are required.

[0193] D - >Z 1j +X et +X pt , which indicates that the combination fault is a general dangerous area, and roof blasting and coal blasting are required.

[0194] D + D represents the distance from the nearest fault in the fault group when the working face is excavated towards the fault group. - D represents the distance from the nearest fault in the fault group when the working face is excavated away from the fault group.

[0195] The above formulas are all dimensionless numerical calculations, and the formulas are obtained by software simulation of a large amount of data to obtain the nearest real situation, and the preset parameters in the formula are set by a person skilled in the art according to the actual situation.

[0196] The above embodiments can be realized wholly or partially by software, hardware, firmware or any combination thereof. When realized by software, the above embodiments can be realized in the form of a computer program product wholly or partially. Those skilled in the art can realize that the units and algorithm steps of the examples described in connection with the embodiments disclosed herein can be realized by electronic hardware, or a combination of computer software and electronic hardware. Whether the functions are realized by hardware or software methods depends on the specific application and design constraints of the technical solutions.

[0197] The units described as separate components can or can not be physically separated, and the components shown as units can or can not be physical units, and can be located in one place or distributed on multiple network units. Part or all of the units can be selected according to actual needs to achieve the purpose of the embodiments.

[0198] The above is only a specific implementation method of the present application, but the scope of protection of the present application is not limited thereto. Any technician familiar with this technical field can easily think of changes or replacements within the technical scope disclosed in this application, which should be covered by the scope of protection of the present application.

[0199] The units described as separate components may or may not be physically separate, and the components shown as units may or may not be physical units, and may be located in one place or distributed across multiple network units. Some or all of these units may be selected to achieve the purpose of this embodiment as needed.

[0200] The above is only a specific implementation method of the present application, but the scope of protection of the present application is not limited thereto. Any technician familiar with this technical field can easily think of changes or replacements within the technical scope disclosed in this application, which should be covered by the scope of protection of the present application.

Claims

1. A regional hazard classification and solution under a combined fault, characterized by: The specific steps include: S1. Construct cross-sectional and plan views of the combined fault and working face, and collect basic data on the fault and working face, including the fall of each fault, the in-situ rock stress in the non-structural area, the vertical and horizontal ground stresses around the fault, the average bulk density of the coal seam overburden, the coal seam burial depth, the coal seam thickness, the stress concentration factor of the coal seam, the residual stress of the surrounding rock, the friction coefficient of the micro-units in the plastic zone of the coal body, the internal friction angle of the coal body, and the lateral pressure coefficient of the coal body; S2. Based on the cross-sectional and plan views of the combined fault and the working surface, the vertical and horizontal geostresses, obtain the calculated dip angles and plane grid matrix of the fault layers on the combined fault; based on the calculated dip angles and plane grid matrix of the fault layers on the combined fault, obtain the geostress increment matrix of the fault; based on the geostress increment matrix of the fault, obtain the influence range of each fault; based on the influence range of each fault, determine the combined relationship of the faults and obtain the combined fault; S3. Obtaining a geostress increment matrix of the combined fault based on the faults and geostress increment matrix included in the combined fault, and obtaining a geostress influence range of the combined fault and a geostress peak influence range of the combined fault based on the geostress increment matrix of the combined fault; S4. Based on the drop of each fault and the combined fault, obtain the drop influence range and drop peak influence range of each combined fault structure; based on the effective drop of the combined fault, obtain the drop influence range and drop peak influence range of each combined fault structure; S5. Obtain the influence range and peak influence range of the combined fault structure based on the combined fault in-situ stress influence range, the in-situ stress peak influence range, the drop influence range of the combined fault structure, and the drop peak influence range; S6. Process the data of the average bulk density of the coal seam overburden, the coal seam depth, the coal seam thickness, the stress concentration coefficient of the coal rock layer, the residual stress of the surrounding rock, the friction coefficient of the micro-units in the plastic zone, and the internal friction angle of the coal body to generate the range of the plastic zone. Process the data of the lateral pressure coefficient of the coal body, the coal seam thickness, the stress concentration coefficient, and the friction coefficient of the micro-units in the plastic zone to generate the range of the elastic zone. S7. Divide the working face into the working face facing stage and the diverging stage, and judge the regional hazard level of the combined fault advance according to the influence range of the combined fault structure, the peak influence range of the combined fault structure, the plastic zone range and the elastic zone range, and implement corresponding measures according to the hazard level.

2. The regional hazard classification and solution under the combined fault according to claim 1 is characterized by: A vertical cross-section with the upper and lower ranges of the fault length is made along the working face lane to obtain the fault profile line. Four inflection points with large slope changes are found in the fault profile line, and the angle and length are calculated. The calculation formula is: Among them, L i is the fault length, θ i is the calculated dip angle of the i-th fault, i is the index of the fault, the value range of i is [1, I], I is the number of faults passing through the working surface, θ i1 ,θ i2 ,θ i3 and θ i4 are the angles between the first, second, third and fourth inflection points of the fault profile and the horizontal line, h i1 、h i2 、h i3 and h i4 They are the first, second, third and fourth broken line lengths of the fault section line in the vertical section diagram; On the fault profile, a Cartesian coordinate system xoy is established with the horizontal midpoint of the working surface as the center of the circle, the actual relative profile relationship of the I faults, and the working surface advancement direction as the positive semi-axis direction of the x-axis. The moving point M represents any point relative to the fault. Establish 6 plane grid matrices of the same size and corresponding to the Cartesian coordinate system, the number of rows and columns of the plane grid matrix are both m, the plane grid matrix includes a distance matrix and an angle matrix, and the elements of the 6 plane grid matrices correspond to the planes of the Cartesian coordinate system; Among them, the elements of the 6 plane grid matrices are: Among them, the matrix element a mm The position of is (m, m); The corresponding relationship between the element positions of the plane grid matrix and the coordinates in the Cartesian coordinate system is: Where (x,y) M is the coordinate of point M in the Cartesian coordinate system, x and y are the horizontal and vertical coordinates of point M in the Cartesian coordinate system respectively, is the element position of the plane grid matrix, and are the horizontal and vertical coordinates of point M in the plane grid matrix, and the size of m is the fault length L i twice the maximum value in L1, L2, ..., L i ); l i1 、l i2 、l i3 In the Cartesian coordinate system, the moving point M(x, y) is respectively moved to the fault point D i1 、D i2 、D i3 distance, using l i1 、l i2 、l i3 , get the distance matrix; α i1 , α i2 , α i3 In the Cartesian coordinate system, the moving point M(x, y) is respectively moved to the fault point D i1 、D i2 、D i3 The angle between the line connecting the two and the positive direction of the x-axis is calculated using α i1 , α i2 , α i3 , get the angle matrix; D i1 、D i2 、D i3 are the upper endpoint, midpoint and lower endpoint of the i-th fault in the cross-section diagram respectively.

3. The regional hazard classification and solution under the combined fault according to claim 2 is characterized by: The calculation of the in-situ stress increment matrix of the i-th fault is based on the following formula: Vs i =Max(Vσ xi |,|Vσ yi |,|Vσ xyi |) Vs xi =-s i (A i -B i -1) Vs yi =-s i (1-A i -B i ) Vs xyi =-s i C i Among them, Vσ i is the ground stress increment matrix of the i-th fault, Vσ xi is the stress increment along the x direction on the i-th fault, Vσ yi is the stress increment along the y direction on the i-th fault, Vσ xyi is the increment of shear stress on the i-th fault, σ i is the simulated inclination of the i-th fault ignoring shear stress, A i From the moving point M to the fault point D i3 The distance from the moving point M to the fault point D i1 and D i2 The ratio parameter between the distances, B i From the moving point M to the fault point D i3 The scale parameter of the distance and the corresponding angle, C i From the moving point M to the fault point D i2 The proportionality parameter between the distance and the angle, σ hi is the horizontal stress of the i-th fault, σ vi is the vertical stress of the i-th fault.

4. The regional hazard classification and solution under the combined fault according to claim 3 is characterized by: According to the fault stress increment matrix of the i-th fault, the influence range of each fault is obtained. The specific steps are as follows: According to the i-th fault stress increment matrix Vσ i , obtain the stress increment curve of the working surface under the influence of I fault, and according to the stress increment curve, obtain the influence range of each fault, according to the following formula: x i =(x i1 +x i2 ) / 2 Among them, x i is the influence range of the i-th fault, x i1 and x i2 are the influence ranges on both sides of the i-th fault, defined as the two critical distances from both sides of the i-th fault to the point where the stress increment reaches the original rock stress σ0, where σ0 refers to the stress borne by the rock itself when not subjected to external forces; According to the influence range x of the i-th fault i The relative position of the fault is used to determine the combination relationship of the faults. The specific process is as follows: satisfy: L dtc <(x a +x b ) x a =(x a1 +x a2 ) / 2 x b =(x b1 +x b2 ) / 2 L dtc =Min(L dtc1 ,L dtc2 ,L dtc3 ,L dtc4 ,L dtc5 ) x a is the influence range of fault a, x b is the influence range of fault b, x a1 and x a2 are the two critical distances on both sides of fault a when the stress increment reaches the original rock stress σ0, x b1 and x b2 L is the two critical distances from the two sides of fault b to the point where the stress increment reaches the original rock stress σ0, dtc1 、L dtc2 、L dtc3 、L dtc4 、L dtc5 L is the length of the segment of the propulsion line sandwiched between the two fault planes, dtc is the minimum value among them; The distance L between fault a and fault b dtc If it is smaller than the sum of the influence ranges of the two faults, then fault a and fault b are combined faults; By combining and judging all faults, the combined relationship of the faults can be obtained, and J combined faults can be obtained.

5. The regional hazard classification and solution under the combined fault according to claim 4 is characterized by: Get the ground stress increment matrix of the jth combined fault: VF j =Max(Vσ xa +Vσ xb |,|Vσ ya +Vσ yb |,Vσ xya +Vσ xyb |) Among them, VΦ j is the ground stress increment matrix of the jth combined fault, a∈[1,I]∩b∈[1,I]∩a≠b, Vσ xa 、Vσ ya 、Vσ xya are the stress increment along the x direction, the stress increment along the y direction, and the shear stress increment on the ath fault, Vσ xb 、Vσ yb 、Vσ xyb are the stress increment along the x-direction, the stress increment along the y-direction, and the shear stress increment on the b-th fault, respectively; According to the ground stress increment matrix VΦ of the j-th combined fault j , obtain the stress increment curve of the working surface under the influence of the j-th combined fault. According to the stress increment curve of the working surface under the influence of the combined fault, the formula for obtaining the in-situ stress influence range and peak influence range of the j-th combined fault is as follows: X1, j =Max(x j1 ,x j2 ) X, 2j =Max(x j3 ,x j4 ) Among them, X1, j is the in-situ stress influence range of the j-th combined fault, X, 2j is the impact range of the peak ground stress of the jth combined fault, x j1 and x j2 are the influence ranges on both sides of the jth combined fault, which are defined as the two critical distances from the combined fault to the time when the stress increment reaches the original rock stress σ0, x j3 and x j4 are the peak ranges on both sides of the j-th combined fault, which are defined as the two critical distances from the combined fault to the time when the stress increment reaches 10σ0 of the original rock stress.

6. The regional hazard classification and solution under the combined fault according to claim 5 is characterized by: According to the drop of each fault and J combined faults, the drop influence range and drop peak influence range of each combined fault structure are obtained. The specific process is as follows: Obtain the effective drop of the j-th combined fault using the following calculation formula: Among them, LLC j is the effective drop of the jth combined fault, LC i is the drop of the i-th fault, L dtc-Min 、L dtc-Max are the minimum and maximum distances between faults within the combined fault, respectively; According to the effective drop of the j-th combined fault, the formula for obtaining the drop influence range and drop peak influence range of the j-th combined fault structure is as follows: Among them, Y 1j is the drop influence range of the jth combined fault, Y 2j is the impact range of the peak drop of the jth combined fault; According to the j-th combined fault stress influence range X1, j , the impact range of the peak ground stress X, 2j , the impact range of the combined fault structure Y 1j And the drop peak impact range Y 2j , obtain the influence range and peak influence range of the j-th combined fault structure, based on the following formula: Z 1j =Max(X1, j ,Y 1j ) Z 2j =Max(X2, j ,Y 2j ) Among them, Z 1j is the combined fault structure influence range of the jth combined fault, Z 2j is the combined fault structure peak influence range of the jth combined fault.

7. The regional hazard classification and solution for combined faults according to claim 6 is characterized by: In step S6, the specific formula for obtaining the plastic zone range and the elastic zone range is as follows: Among them, X et is the plastic zone range, X pt is the elastic region, kγH is the X et The stress peak is at the point where H is the depth of the coal seam, γ is the average density of the coal seam overburden, k is the stress concentration coefficient, σ r is the residual stress of the surrounding rock, is the internal friction angle of the coal body, f is the friction coefficient of the small unit in the plastic zone, p is the thickness of the coal seam, and λ is the lateral pressure coefficient of the coal body.

8. The regional hazard classification and solution under the combined fault according to claim 7 is characterized by: In step S7, the specific process of obtaining the regional hazard level of the combined fault advance and executing corresponding measures according to the hazard level is as follows: The regional advance of the combined fault is divided into two stages: the working face approach stage and the working face divergence stage; Working surface facing stage: The influence range Z of the j-th combined fault structure 1j , plastic zone range X et and elastic range X pt Add up and set the plastic zone range X et and the peak influence range Z of the jth combined fault structure 2j Add the sum, and the summed values ​​are all equal to D + For comparison: When D + >Z 1j +X et +X pt , indicating that the combined fault advance regionality is a general dangerous area, and roof blasting and coal blasting are required; When X et +Z 2j <D + ≤Z 1j +X et +X pt , indicating that the combined fault advance regionality is a medium-risk area, which requires roof blasting, coal blasting and large-diameter drilling to relieve pressure; When 0≤D + ≤X et +Z 2j , indicating that the combined fault advance area is a dangerous area, which requires roof blasting, coal blasting, and large-diameter drilling to relieve pressure. In addition, roof and large-diameter densification treatment is also required; Working face departure stage: The influence range Z of the j-th combined fault structure 1j , plastic zone range X et and elastic range X pt Add up and set the plastic zone range X et and the peak influence range Z of the jth combined fault structure 2j Add the sum, and the summed values ​​are all equal to D - For comparison: When D - ≤X et +Z 2j , indicating that the combined fault advance area is a dangerous area, which requires roof blasting, coal blasting, and large-diameter drilling to relieve pressure. In addition, roof and large-diameter densification treatment is also required; When X et +Z 2j <D - ≤Z 1j +X et +X pt , indicating that the combined fault advance regionality is a medium-risk area, which requires roof blasting, coal blasting, and large-diameter drilling to relieve pressure; D - >Z 1j +X et +X pt , indicating that the combined fault advance regionality is a general dangerous area, and roof blasting and coal blasting are required; D + It indicates the distance from the nearest fault in the fault group when the working face is excavated towards the fault group, D - It indicates the distance from the nearest fault in the fault group when the working face advances away from the fault group.

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