A pressure relief and impact prevention method for thick coal seam by three-dimensional layering buffer energy band

Abstract

The present application relates to a kind of thick coal seam three-dimensional layer buffer energy absorption zone pressure relief anti-bumping method, belong to the technical field of coal mine thick coal seam floor lane prevention and control rock burst, first determine the support stress curve distribution length L along the working face advancing direction, with L independent anti-bumping unit is divided, stress rise zone length L1, stress critical load zone length L2, stress drop zone length L3, stress static load zone length L4 are determined in sequence, and different cut seam borehole distribution spacing parameters are determined in different stress partition;In the vertical direction of working face, coal stress stability zone height H1, stress height H2, stress superposition zone height H3 are determined in sequence, different stress partition is determined in different regions Cut seam parameters and barrier groove position;Reasonable jet parameters are taken in different stress regions, barrier groove is formed by continuous cutting at different partition junction, both play the role of coal pressure relief, can also block stress transmission, solve the problem such as coal seam pressure relief insufficient, uneven etc.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of thick coal seam floor roadway prevention and control of rock burst, and relates to a thick coal seam three-dimensional layered buffer energy absorption zone pressure relief and rock burst prevention method. BACKGROUND

[0002] With the increase of coal mining scale and depth year by year, the strength and harm of rock burst are increasingly prominent. Rock burst disasters occur during the mining process, destroying the mining system such as mining face and roadway, causing a large amount of equipment damage, personnel casualties and economic losses. After a large amount of theoretical research and engineering practice on the mechanism and technical means of rock burst prevention and control, coal seam water injection, large-diameter borehole pressure relief, coal seam blasting unloading, roof deep hole blasting, coal seam roof fracturing and other rock burst prevention and control techniques have been formed. Due to the small range of large-diameter borehole pressure relief, large engineering quantity, disorder of coal seam roof fracturing, uncontrollable fracturing range, difficulty in material source due to the influence of mining explosive control, and high cost, the above technical measures have limitations in the field of rock burst prevention and control.

[0003] According to previous research and a large amount of engineering practice, it is shown that taking effective pressure relief technical measures in the coal seam and reducing the stress concentration of the coal seam are the main prevention and control means of rock burst. However, due to the complex geological conditions of thick coal seams, the stress of coal seam roof and floor, the lateral stress of goaf roof, the support pressure of mining face, the layout of working face and other factors, the rock burst prevention and control measures are not sufficient and uniform, which cannot effectively reduce the rock burst danger and seriously affect the safety production of the mine. Thick coal seams with gas disasters are usually arranged with floor roadways, and pressure relief is performed by drilling through the layer. With the development of water jet technology and equipment, a pressure relief buffer energy absorption zone can be formed by artificially cutting a slot in the coal seam, which can provide a pressure relief deformation space for the coal body to reduce the accumulation of elastic energy, block stress transmission and reduce stress concentration, thereby effectively reducing the rock burst danger of the coal seam. However, there is no mature theoretical system as a basis for implementing water jet pressure relief and rock burst prevention in thick coal seams, and the parameters of water jet cutting coal body in the field are usually determined based on engineering experience, which is blind and may cause insufficient pressure relief of coal body in the mining area and unsatisfactory rock burst prevention effect of the coal seam. SUMMARY

[0004] Therefore, the purpose of the present application is to provide a thick coal seam three-dimensional layered buffer energy absorption zone pressure relief and rock burst prevention method to solve the problems of insufficient and uneven pressure relief of thick coal seams in rock burst mines.

[0005] To achieve the above-mentioned purpose, the present application provides the following technical scheme:

[0006] A thick coal seam three-dimensional layered buffer energy absorption zone pressure relief and rock burst prevention method, comprising the following steps:

[0007] S1 determines the distribution length L of the abutment stress curve along the advancing direction of the working face, divides the coal body corresponding to L into an independent anti-burst unit, and partitions the anti-burst unit along the advancing direction of the working face, sequentially as a stress rising zone length L1, a stress critical load zone length L2, a stress descending zone length L3, and a stress static load zone length L4.

[0008] S2 determines the arrangement interval of the cut joint drill hole in the advancing direction of the working face and the arrangement interval of the stress prediction drill hole in different partitions of an anti-burst unit.

[0009] S3 constructs the stress prediction drill hole, counts the drill hole cutting amount of the stress prediction drill hole, calculates the stress distribution law in the vertical direction of the working face according to the drill hole cutting amount of the stress prediction drill hole, and divides the stress stable zone height H1, the stress increasing zone height H2, and the stress superposition zone height H3.

[0010] S4 determines the cut joint parameters and barrier groove positions in the vertical direction of the working face in different stress partitions according to the stress distribution law in the vertical direction of the working face, and constructs the cut joint and the barrier groove.

[0011] S5 performs anti-burst and pressure relief construction on the remaining anti-burst units according to steps S1-S4 to form a three-dimensional pressure relief space in the entire coal seam.

[0012] Optionally, in step S1, when 0≤σ i ≤1.5σ c , it is determined that the interval is the stress rising zone length range L1∈[L σc , L 1.5σc ]; when σ i ≥1.5σ c from the front of the working face, it is determined that the interval is the stress critical load zone length L2=L ≥1.5σc ; when 1.5σ c ≥σ i ≥σ c from the front of the working face, and the stress appears to decrease, it is determined that the interval is the stress descending zone length range L3∈[L 1.5σc , L σc ].

[0013] Optionally, in step S1, the stress static load zone range L4 is obtained according to the stress distribution evolution law of the working face, L4=K1(L1+L2+L3), K1 is the working imbalance coefficient, and K1 is taken as 1.2-1.5.

[0014] Optionally, in step S2, one row of stress prediction drill holes is constructed every 30m in the advancing direction of the working face, and each row of drill holes is at least 3, which controls the crossheading on both sides of the working face and the middle position.

[0015] Optionally, in step S2, the interval of the cutting seam drill hole arrangement is 3m in the stress rising area, the stress falling area, and the stress critical load area, and the interval of the cutting seam drill hole arrangement is 4m in the stress static load area.

[0016] Optionally, in step S3, the average value W of the cutting amount of the stress prediction drill hole unit coal penetration depth is calculated. i And the cutting amount change value AW.

[0017] Optionally, in step S3, when the cutting amount change value AW is in [-0.2, 0.2] Kg / m 3 , it is the stress stable area height H1; when the cutting amount change value AW is in [0.2, 0.5] Kg / m 3 , it is the stress stable area height H2; and when AW is greater than or equal to 0.5 Kg / m 3 , it is the stress superposition area height H3.

[0018] Optionally, in step S4, the interval of the cutting seam drill hole is 3m in the coal stress stable area height H1, the interval of the cutting seam drill hole is 2m in the coal stress increasing area height H2, and the interval of the cutting seam drill hole is 1m in the coal stress superposition area height H3.

[0019] Optionally, in step S4, the supplementary cutting seam drill hole is constructed, and the continuous barrier groove is cut at the coal stress stable area height H1, the stress increasing area height H2 and the stress superposition area height H3.

[0020] Optionally, the water jet pressure relief construction is implemented on the anti-burst unit in the coal seam floor roadway.

[0021] The beneficial effects of the present application are that the present application is based on the stress distribution law in the advancing direction and the vertical direction of the thick coal seam mining face, the water jet pressure relief drill hole is implemented on the stress concentration area of the mining area in the coal seam floor roadway, the buffer energy absorption pressure relief anti-burst belt is artificially manufactured in the coal seam, different jet cutting parameters are adopted in different stress areas to cut the coal body, and the stress concentration in the coal body is effectively reduced. At the same time, according to the stress division basis of the thick coal seam, the barrier groove is continuously cut at the junction of different partitions in the coal body, which not only plays a role in coal pressure relief, but also can block the stress transmission. Through the division of the stress distribution of the thick coal seam, reasonable jet parameters are adopted in different stress areas, and the method of layered pressure relief in the coal seam is adopted, the problems of insufficient and uneven pressure relief of the coal seam are solved, and the three-dimensional pressure relief anti-burst of the thick coal seam is formed, and the danger of coal bumping is effectively reduced.

[0022] Additional advantages, objects, and features of the application will be apparent to those skilled in the art upon examination of the following detailed description, it being understood that each of the foregoing general statements are not limiting upon the scope of the application and that all patentable combinations of the recited features are contemplated and are within the scope of the present application. The application is defined solely by the appended claims. BRIEF DESCRIPTION OF DRAWINGS

[0023] In order to make the objectives, technical solutions and advantages of the present application clearer, the preferred embodiments of the present application will be described in detail below with reference to the drawings, in which:

[0024] Fig. 1 is a schematic diagram of support stress curve distribution along the advancing direction of the working face in thick coal seam;

[0025] Fig. 2 is a schematic diagram of borehole construction layout along the advancing direction of the working face in thick coal seam;

[0026] Fig. 3 is a schematic diagram of vertical section construction of three-dimensional pressure relief and anti-caving in thick coal seam.

[0027] The drawings show: coal seam 1, mining working face 1-1, coal seam pressure relief area 1-2, coal seam floor 3, floor drainage roadway 4, working face support stress curve 5, cut joint borehole 6, stress prediction borehole 7, stress increase area length L1, stress critical load area length L2, stress decrease area length L3, stress static load area length L4, roadway stress curve 8, working face superimposed stress curve 9, cut joint groove 10, barrier groove 11, supplementary cut joint borehole 12, stress stabilization area height H1, stress increase area height H2, stress superimposed area height H3. DETAILED DESCRIPTION

[0028] The embodiments of the present application will be described in detail below with reference to specific examples. Those skilled in the art can easily understand other advantages and effects of the present application from the disclosure of the specification. The present application can also be implemented or applied in different specific embodiments, and various modifications or changes can be made to the details in the specification without departing from the spirit of the present application. It should be noted that the drawings provided in the following examples only illustrate the basic concept of the present application in a schematic manner, and the following examples and features in the examples can be combined with each other without conflict.

[0029] The drawings are only used for illustrative explanation, and the representation is only a schematic diagram, not a physical diagram, and should not be understood as a limitation on the present application. In order to better illustrate the embodiments of the present application, some components in the drawings may be omitted, enlarged or reduced, and do not represent the actual size of the product. It is understandable to those skilled in the art that some well-known structures and their descriptions in the drawings may be omitted.

[0030] The same or similar reference numerals in the drawings of the embodiments of the present application correspond to the same or similar components; in the description of the present application, it is understood that if the orientations or positional relationships indicated by the terms "upper", "lower", "left", "right", "front", "back", etc. are based on the orientations or positional relationships shown in the drawings, they are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, therefore the terms describing the positional relationship in the drawings are only used for exemplary illustration, and cannot be understood as a limitation on the present application, for those skilled in the art, the specific meanings of the above terms can be understood according to the specific circumstances.

[0031] Referring to Figs. 1-3 A thick coal seam three-dimensional layering buffer energy absorption zone pressure relief and bumping prevention method, based on the stress distribution law in the advancing direction and the vertical direction of the thick coal seam mining face, water jet pressure relief boreholes are implemented in the stress concentration area of the mining area in the coal seam floor roadway, and a buffer energy absorption zone is formed by cutting a barrier groove in the coal seam. First, the support stress curve distribution length L is estimated along the advancing direction of the working face to divide an independent bumping prevention unit. The stress rising area length L1, the stress critical load area length L2, the stress descending area length L3, and the stress static load area length L4 are determined in sequence, and different cutting seam borehole spacing parameters are determined in different stress partitions. In the vertical direction of the working face, the coal body stress stable area height H1, the stress increasing area height H2, and the stress superposition area height H3 are determined in sequence, and different stress partition cutting seam parameters and barrier groove positions are determined in different areas. Reasonable jet parameters are adopted in different stress areas, and a barrier groove is continuously cut at the junction of different partitions, which not only plays a role in coal seam pressure relief, but also blocks stress transmission, solves the problems of insufficient and uneven coal seam pressure relief, and forms a three-dimensional pressure relief and bumping prevention in thick coal seams, effectively reducing the risk of coal bumping.

[0032] Specifically includes the following steps:

[0033] S1 According to the basic geological data such as coal seam occurrence conditions, coal body mechanical characteristic parameters, and working face layout, the support stress curve distribution length L along the advancing direction of the working face is estimated. The stress rising area length L1, the stress critical load area length L2, the stress descending area length L3, and the stress static load area length L4 are determined in sequence.

[0034] S2 According to the support stress distribution law in the advancing direction of the mining working face, the cutting seam borehole 6 and the stress prediction borehole 7 arrangement spacing in different partitions of a three-dimensional independent unit for preventing rock burst are determined.

[0035] S3 The stress prediction borehole adopts the drilling chip quantity statistical method to calculate the stress distribution law in the vertical direction of the working face, and reasonably divides the stress increasing area height H2 and the stress superposition area height H3.

[0036] S4 According to the stress distribution law of the thick coal seam in the mining face, the cutting seam parameters and the position of the barrier groove in different stress zones are determined.

[0037] S5 According to the construction parameters determined in steps S1-S4, the rest of the anti-bumping units are constructed to form a three-dimensional pressure relief space in the whole coal seam.

[0038] Preferably, the length L of the working face support stress curve distribution field is determined by the support stress distribution law in front of the mining face 1-1, i.e. L=L1+L2+L 3+ L4. The coal body in front of the working face support stress curve distribution length L of the thick coal seam working face is regarded as a three-dimensional independent unit for preventing and controlling rock burst.

[0039] Preferably, according to the rock mass control theory, the coal body strength σ c can be measured and calculated by CT stress scanning, stress meter, numerical simulation analysis and other means in front of the mining face 1-1 L i . i .

[0040] Preferably, when 0≤σ i ≤1.5σ c and the stress increases, the interval is determined as the stress increasing zone length range L1∈[L σc , L 1.5σc ].

[0041] Preferably, when σ i ≥1.5σ c in front of the working face, the interval is determined as the stress critical load zone length range L2=L ≥1.5σc .

[0042] Preferably, when 1.5σ c ≥σ i ≥σ c and the stress decreases, the interval is determined as the stress decreasing zone length range L3∈[L 1.5σc , L σc ].

[0043] Preferably, when σ i =σ c in front of the working face, the interval can be determined as the stress static load zone range L4. According to the working face support stress distribution evolution law, L4=K1(L1+L2+L3), K1 is the working imbalance coefficient, and K1 is generally taken as 1.2-1.5.

[0044] Preferably, the purpose of the stress prediction boreholes is to obtain the stress distribution pattern in the vertical direction of the working face, providing a basis for determining the cutting spacing parameters for the cutting boreholes 6. A row of stress prediction boreholes is constructed every 30m along the advancing direction of the longwall face, with at least 3 boreholes in each row, respectively controlling the roadways on both sides and the middle position of the working face.

[0045] Preferably, the spacing parameters of the slotted holes 6 are different in different stress zones. The spacing of the slotted holes 6 is 3m in the stress rise zone and stress fall zone, 2m in the stress critical load zone, and 4m in the stress static load zone.

[0046] Preferably, the amount of cuttings W per unit depth of coal penetration in each stress prediction borehole 7 from the point of coal encounter to the end of the borehole is statistically analyzed. 1i W 2i W 3i Where i represents the unit coal penetration depth. The average value W is taken from the cuttings output per unit coal penetration depth of the three stress prediction boreholes. i =(W 1i +W 2i +W 3i ) / 3.

[0047] Preferably, the change in the amount of cuttings produced per unit depth of the coal seam is calculated as ΔW = W. i+1 —W i When ΔW∈[-0.2, 0.2]Kg / m 3 When the stress distribution within the coal penetration depth area is relatively uniform, the height H1 of the stress stability zone can be determined.

[0048] Preferably, the change in the amount of cuttings produced per unit depth of the coal seam is calculated as ΔW = W. i+1 —W i When ΔW∈[0.2, 0.5]Kg / m 3 At that time, the amount of debris produced gradually increases within the coal penetration depth area, reflecting the gradual increase in coal stress, which can determine the height H2 of the stress stability zone.

[0049] Preferably, the change in the amount of cuttings produced per unit depth of the coal seam is calculated as ΔW = W. i+1 —W i When ΔW ≥ 0.5 kg / m 3 At that time, the amount of debris produced in the coal penetration depth area increased significantly, reflecting that the coal body was squeezed due to high stress, and the height H3 of the stress superposition zone can be determined.

[0050] Preferably, the vertical distance between the borehole cutting slot working face is 3m in the range of the coal body stress stable zone height H1, 2m in the range of the coal body stress increasing zone height H2, and 1m in the range of the coal body stress superposition zone height H3.

[0051] When the barrier groove 11 cannot be penetrated by the cutting slot borehole 6, a supplementary cutting slot borehole 12 can be constructed to cut a continuous barrier groove 11 at the coal body stress stable zone height H1, the stress stable zone height H2, and the stress superposition zone height H3, respectively, so as to form a buffer energy absorption zone between the barrier grooves 11.

[0052] Embodiment

[0053] This embodiment takes the coal II layer of a certain rock burst mine as a geological background, which has a combined dynamic disaster risk of outburst and rock burst. The mining working face is located in the south of the coal II layer six mining area, with a ground elevation of 1995-2320m and a buried depth of 594-777m. The coal II layer is mined, with a thickness of 25.04-45.0m and an average of 34.5m. The working face has a mining height of 5m, a coal seam inclination of 5°-15°, a designed strike length of 584m, a dip width of 120m, and a coal body strength σ c = 18MPa.

[0054] A thick coal seam three-dimensional layered buffer energy absorption zone pressure relief and rock burst prevention method, as shown in Figs. 1-3 , the figure shows a coal seam 1, a mining working face 1-1, a coal seam pressure relief area 1-2, a coal seam floor 3, a floor drainage roadway 4, a working face support stress curve 5, a cutting slot borehole 6, a stress prediction borehole 7, a stress increasing zone length L1, a stress critical load zone length L2, a stress decreasing zone length L3, a stress static load zone length L4, a roadway stress curve 8, a working face superposition stress curve 9, a cutting slot 10, a barrier groove 11, a supplementary cutting slot borehole 12, a stress stable zone height H1, a stress increasing zone height H2, and a stress superposition zone height H3, comprising the following steps:

[0055] S1 According to the coal seam occurrence conditions, coal body mechanical characteristic parameters, working face layout, and other basic geological data, the stress distribution law is studied along the working face advancing direction using the working face CT stress scanning method. In the range of 0-25m in front of the working face, the coal body stress σ is 0-27MPa and shows an increasing trend. In the range of 25-40m, the stress σ is greater than 27MPa, with a maximum value of 40MPa and a trend of first increasing and then decreasing. In the range of 40-70m, the stress σ value is 18-27MPa. After 70m, the stress σ is about 18MPa.

[0056] According to the above stress distribution range, the stress in front of the working face shows a state of first increasing, then decreasing, and then tending to be moderate, which is a combined working face support stress distribution law. According to the stress increasing zone (0≤σi ≤1.5σ c ), stress critical load zone (σ i ≥1.5σ c ), stress drop zone (1.5σ c ≥σ i ≥σ c ) division, it can be determined that the stress rise zone length is 35m, the stress critical load zone length is 40m, and the stress drop zone length is 70m.

[0057] According to the working face support stress distribution evolution law, L4=K1(L1+L2+L3), K1 is the working imbalance coefficient, K1 is 1.5, the stress static load zone length L4=1.5×(25+15+30)=105m can be calculated; the working face support stress curve distribution field length L is determined, that is, L=L1+L2+L3+L4=25+15+30+105=175m. Therefore, the coal seam within the range of 175m in front of the working face can be regarded as a three-dimensional independent unit for preventing and controlling rock burst; the three-dimensional independent unit for preventing and controlling rock burst is divided by the working face length, and a single unit is managed if it does not meet the length of an independent unit. Therefore, the working face length l is 584m, n=[l / L]+1=[584÷175]+1=4, so the working face can be uniformly divided into 4 units for management.

[0058] S2 determines the arrangement interval of the cut seam drill hole 6 and the stress prediction drill hole 7 in different partitions of a three-dimensional independent unit for preventing and controlling rock burst according to the support stress distribution law in the advancing direction of the mining working face, and the remaining rock burst prevention units are managed in the same way.

[0059] The purpose of constructing the stress prediction drill hole is to obtain the vertical direction stress distribution law of the working face and provide a basis for determining the cut seam interval parameters of the cut seam drill hole 6. A row of stress prediction drill holes is constructed every 30m in the advancing direction of the mining working face, and each row has at least 3 drill holes to control the crossheading on both sides of the working face and the middle position. Therefore, 6 rows of stress prediction drill holes need to be arranged in an independent rock burst prevention unit.

[0060] In different stress partitions, the cut seam drill hole 6 adopts different hole arrangement interval parameters. In the stress rise zone and the stress drop zone, the row interval of the cut seam drill hole 6 is 3m, in the stress critical load zone, the row interval of the cut seam drill hole 6 is 2m, and in the stress static load zone, the row interval of the cut seam drill hole 6 is 4m. Therefore, in the stress rise zone, 8 rows of cut seam drill holes 6 are arranged, in the stress critical load zone, 7 rows of cut seam drill holes 6 are arranged, in the stress drop zone, 10 rows of cut seam drill holes 6 are arranged, and in the stress static load zone, 21 rows of cut seam drill holes 6 are arranged.

[0061] S3: Stress prediction borehole adopts the method of drilling out debris quantity statistics to calculate the stress distribution law in the vertical direction of the working face, and reasonably divide the height H2 of the stress increasing area and the height H3 of the stress superposition area.

[0062] The out debris quantity W of each stress prediction borehole 7 per unit coal depth from the coal seam point to the final hole point is counted 1i , W 2i , W 3i , and i is the unit coal depth. The average value W i = (W 1i +W 2i +W 3i ) / 3 of the out debris quantity per unit coal depth of the three stress prediction boreholes 7 is taken.

[0063] The out debris quantity change value AW of the coal seam per unit depth is calculated as AW = W i+1 -W i . The out debris quantity change value AW is calculated by counting the out debris quantity W i per unit coal depth. Within the height range of 5m from the coal seam point, AW ∈ [-0.2, 0.2] Kg / m 3 . Within the height range of 5-25m, AW ∈ [0.2, 0.5] Kg / m 3 , and the out debris quantity of the borehole gradually increases. Within the height range of 25-40m, AW ≥ 0.5 Kg / m 3 .

[0064] The height H1 of the working face is determined as 5m, the height H2 of the stress increasing area is determined as 20m, and the height H3 of the stress superposition area is determined as 15m.

[0065] S4: According to the vertical stress distribution law of the thick coal seam in the mining working face, different cutting seam parameters and barrier groove positions are constructed in different stress zones.

[0066] Within the height H1 = 5m range of the coal body stress stability area, the drilling cutting seam spacing is 3m, within the height H2 = 20m range of the coal body stress increasing area, the drilling cutting seam spacing is 2m, and within the height H3 = 15m range of the coal body stress superposition area, the drilling cutting seam spacing is 1m.

[0067] By constructing the supplementary cutting seam borehole 12, the barrier groove 11 is constructed at the positions of 5m, 25m and 40m from the coal seam floor, respectively.

[0068] S5: The construction parameters are determined by referring to steps S1-S4, the remaining anti-scour units are subjected to anti-scour and pressure relief engineering construction, and a three-dimensional pressure relief space is formed in the entire coal seam.

[0069] The present application forms the thick coal layer three-dimensional pressure relief and prevents the rush by the way of the thick coal layer internal layering pressure relief, partitioned management, effectively reduces the coal seam pressure bump danger, solves the problems of the thick coal seam pressure bump mine pressure relief insufficiency, unevenness and the like.

[0070] Finally, it is explained that the above examples are only used to illustrate the technical solutions of the present application and are not limited. Although the present application is described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present application can be modified or replaced by equivalents without departing from the purpose and scope of the technical solutions, which should be covered in the scope of the claims of the present application.

Claims

1. A method for pressure relief and shock prevention using a three-dimensional layered buffer energy-absorbing zone in thick coal seams, characterized in that: Includes the following steps: S1 determines the length L of the support stress curve distribution along the working face advance direction, divides the coal body corresponding to L into an independent anti-scour unit, and divides the anti-scour unit into partitions along the working face advance direction, namely, stress rise zone length L1, stress critical load zone length L2, stress fall zone length L3, and stress static load zone length L4. S2 determines the spacing of the slotted boreholes in the working face advancing direction and the spacing of the stress prediction boreholes in different zones of an anti-impact unit. S3 Construction stress prediction borehole, statistical analysis of the amount of cuttings produced in the stress prediction borehole, calculation of the stress distribution law in the vertical direction of the working face based on the amount of cuttings produced in the stress prediction borehole, and division of the stress stability zone height H1, stress increase zone height H2, and stress superposition zone height H3. S4 Determine the cutting parameters and barrier groove positions in the vertical direction of the working face according to the stress distribution law in the vertical direction of the working face in different stress zones, and construct the cutting and barrier groove. S5. Following steps S1 to S4, carry out anti-impact and pressure relief construction on the remaining anti-impact units to form a three-dimensional pressure relief space throughout the coal seam.

2. The method for pressure relief and shock prevention of a three-dimensional layered buffer energy-absorbing zone in a thick coal seam according to claim 1, characterized in that: In step S1, within the range in front of the working face, 0 ≤ σ i ≤1.5σ c Furthermore, when the stress increases, this interval is determined to be the stress-increase zone length range L1∈[L σc L 1.5σc ]; Within the range σ in front of the working face i ≥1.5σ c When this interval is determined to be the length range of the stress critical load zone, L2 = L ≥1.5σc ; within a range of 1.5σ in front of the working face c ≥σ i ≥σ c Furthermore, when the stress decreases, this interval is determined to be the stress decrease region, with length L3 ∈ [L]. 1.5σc L σc ].

3. The method for pressure relief and shock prevention of a three-dimensional layered buffer energy-absorbing zone in a thick coal seam according to claim 1, characterized in that: In step S1, the range of the static load zone L4 is obtained based on the evolution law of the stress distribution of the working face support. L4 = K1(L1 + L2 + L3), where K1 is the working imbalance coefficient, and K1 is taken as 1.2~1.

5.

4. The method for pressure relief and shock prevention of a three-dimensional layered buffer energy-absorbing zone in a thick coal seam according to claim 1, characterized in that: In step S2, a row of stress prediction boreholes is constructed every 30m along the advancing direction of the mining face, with at least 3 boreholes in each row, to control the roadways on both sides and the middle position of the working face.

5. The method for pressure relief and shock prevention of a three-dimensional layered buffer energy-absorbing zone in a thick coal seam according to claim 1, characterized in that: In step S2, along the working face advancing direction, the spacing of the slotted drill holes is 3m in the stress rising zone and stress falling zone, 2m in the stress critical load zone, and 4m in the stress static load zone.

6. The method for pressure relief and shock prevention of a three-dimensional layered buffer energy-absorbing zone in a thick coal seam according to claim 1, characterized in that: In step S3, the average value W of the cuttings output per unit coal penetration depth of the statistical stress prediction borehole is taken. i And the change in the amount of chips discharged, ΔW.

7. The method for pressure relief and shock prevention of a three-dimensional layered buffer energy-absorbing zone in a thick coal seam according to claim 6, characterized in that: In step S3, when the change in the amount of chips ΔW ∈ [-0.2, 0.2] Kg / m 3 When the stress stability zone height H1 is reached; when the chip output change value ΔW ∈ [0.2, 0.5] Kg / m 3 When ΔW ≥ 0.5 kg / m, the stress stability zone height is H2; when ΔW ≥ 0.5 kg / m 3 At that time, the height H3 is the stress superposition zone.

8. The method for pressure relief and shock prevention of a three-dimensional layered buffer energy-absorbing zone in a thick coal seam according to claim 1, characterized in that: In step S4, along the vertical direction of the working face, the spacing of the borehole cuts is 3m within the height H1 range of the coal stress stability zone, 2m within the height H2 range of the coal stress increase zone, and 1m within the height H3 range of the coal stress superposition zone.

9. The method for pressure relief and shock prevention of a three-dimensional layered buffer energy-absorbing zone in a thick coal seam according to claim 1, characterized in that: In step S4, additional cutting boreholes are drilled during construction to cut continuous barrier grooves at the heights H1 (stress stability zone), H2 (stress increase zone), and H3 (stress superposition zone) of the coal body.

10. A method for pressure relief and shock prevention in a three-dimensional layered buffer energy-absorbing zone for thick coal seams according to claim 1, characterized in that: Water jet anti-scour and pressure relief construction was carried out on the anti-scour unit in the coal seam bottom roadway.

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