A roof blasting pressure relief and danger relieving method for high stress area of a coal mine underground tunneling working face

Abstract

The application discloses a roof blasting pressure relief and danger relieving method for high stress area of a coal mine underground tunneling working face, and comprises the following steps: 1, determining the high stress area of the tunneling working face; 2, determining the roof stratum structure of the high stress area; 3, calculating the distance between each key layer of the roof stratum and the coal seam and the distance between the top of each key layer and the coal seam by XK or ZK; 4, collecting the vertical distance between high energy microseismic events and the coal seam and the horizontal distance between the coal wall during the tunneling of the high stress area by using a microseismic monitoring system to obtain a rock stratum fracture line B; 5, combining the calculation of roof blasting pressure relief and danger relieving parameters; and 6, performing roof blasting pressure relief according to the roof blasting pressure relief and danger relieving parameters obtained in the step 5. The method can effectively determine the roof fracture structure and further determine reasonable blasting parameters, can significantly improve the blasting efficiency, accuracy and pressure relief and danger relieving effect, effectively reduces stress concentration after construction, improves the stability of the roadway and is favorable for safe tunneling of the rock burst working face.

Description

Technical Field

[0001] This invention relates to a method for blasting and relieving pressure on the roof of a high-stress zone in an underground coal mine tunneling face. Background Technology

[0002] Rock bursts are a highly destructive rock dynamic disaster characterized by strong dynamic instability.

[0003] Domestic and foreign engineering and technical personnel have carried out a lot of research on rockburst disaster prevention and control technology and proposed many feasible methods. Among them, roof blasting pressure relief technology is a relatively effective method for rockburst prevention and control. In roof blasting pressure relief technology, the blasting parameters directly affect the pressure relief and disaster relief effect. At present, the determination of conventional blasting parameters is not targeted, often with poor effect and requiring continuous adjustment and optimization, which has limitations in practical application. Summary of the Invention

[0004] To address the aforementioned problems, this invention provides a method for blasting and relieving pressure and hazards in the high-stress zone of the roof in underground coal mine tunneling faces. By combining a microseismic monitoring system (such as the ARAMIS microseismic monitoring system), the fracture structure of the roof can be effectively determined, and reasonable blasting parameters can be further determined, which can significantly improve blasting efficiency, accuracy, and pressure relief and hazard mitigation effects.

[0005] To achieve the above-mentioned technical objectives and effects, the present invention is implemented through the following technical solution:

[0006] A method for blasting and relieving pressure on the roof of a high-stress zone in an underground coal mine tunneling face includes the following steps:

[0007] Step 1: Determine the high-stress zone of the tunneling face, with a length L along the direction of the face. f ;

[0008] Step 2: Arrange core holes XK in the middle of the high-stress zone or use the borehole columnar section ZK adjacent to the high-stress zone to determine the top strata structure of the high-stress zone.

[0009] Step 3: Calculate the first key layer K1, the second key layer K2, ..., the i-th key layer K using XK or ZK respectively. i ...the m-th critical layer K m And calculate the first key layer K1, the second key layer K2, ... the i-th key layer K respectively. i ...the m-th critical layer K m The distances between the top of the coal seam and the top of the coal seam are a1, a2, ... a i ...a m Where m is the total number of key layers in the top strata;

[0010] Step 4: Use a microseismic monitoring system to collect data on the vertical distances between high-energy microseismic events during tunneling in high-stress areas and the coal seam, namely A1, A2...A... i ...A m The horizontal distances from the coal face are X1, X2...X i ...X m The rock fracture line B is obtained;

[0011] Step 5: Combine a1, a2...a i ...a m A1, A2...A i ...A m X1, X2...X i ...X m And B, calculate the parameters for decompression and hazard relief during roof blasting;

[0012] Step 6: Perform roof blasting and depressurization based on the roof blasting and depressurization parameters obtained in Step 5.

[0013] Preferably, in step 4, the microseismic monitoring system is the ARAMIS microseismic monitoring system, and the high-energy microseismic events are cubic microseismic events.

[0014] Preferably, the parameters for blasting and decompression of the roof include the blast hole diameter D, blast height A, blast hole depth E, blast hole elevation angle β, charge length ZL, and sealing length FL.

[0015] Preferably, step 3, which involves calculating the key strata of the roof strata and the distance between the top of the key strata and the coal seam using XK or ZK, includes:

[0016] Step 301: Calculate the influence of the nth stratum above the coal seam roof on the first key stratum, and the resulting overlying stratum load q. n The expression is:

[0017]

[0018] In the formula, E1, E2...E n These are the elastic moduli of the 1st, 2nd...nth rock layers, h1, h2...h n These represent the thicknesses of rock layers 1, 2...n, γ1, γ2...γ n These are the volume forces of the 1st, 2nd...nth rock layers, respectively;

[0019] Step 302: When the (n+1)th rock layer satisfies the following formula, it is determined to be a key layer:

[0020]

[0021] In the formula, q n+1The load of the (n+1)th stratum above the coal seam roof on the first key stratum is the overlying stratum load, l. n+1 l is the fracture distance of the (n+1)th stratum above the coal seam roof. n The fracture distance of the nth rock layer above the coal seam roof;

[0022] Step 303: Calculate the distances a1, a2...a1 between the top of each key stratum and the coal seam based on the location of the key strata in each roof stratum. i ...a m .

[0023] Preferably, the fracture distance of the i-th rock layer is l i Calculate according to the following formula:

[0024]

[0025] In the formula, R i Let q be the uniaxial tensile strength of the i-th rock layer. i h represents the load on the i-th rock layer from the overlying strata. i Let be the thickness of the i-th rock layer.

[0026] Preferred:

[0027] The diameter D of the blast hole is obtained based on the drill bit size of the drilling tool;

[0028] Explosion height A = max{a1, a2, ..., a i ...a m A1, A2...A i ...A m};

[0029] The blast hole elevation angle β is obtained from the rock fracture line B;

[0030] The depth of the blast hole is E = A / sinβ;

[0031] ZL+FL=E, and

[0032] The beneficial effects of this invention are:

[0033] In traditional blasting parameter design, the borehole elevation angle is often determined based on experience. If the elevation angle is too small, the critical strata cannot be pre-fractured in time, failing to achieve the desired mitigation effect. Conversely, if the elevation angle is too large, underground construction becomes difficult, and the blasting area may be located within the coal pillar region, potentially leading to coal pillar instability and impact damage, posing a threat to underground safety. Furthermore, the borehole depth in traditional blasting parameter design is often roughly estimated based on columnar sections of thick, hard rock strata. After the final blasting to relieve pressure and mitigate the hazard, the stress concentration is not reduced or reduced only slightly, and the risk remains. This invention provides a method for blasting and relieving pressure on the roof of a high-stress zone in an underground coal mine tunneling face. Combining traditional critical layer theory with on-site microseismic monitoring systems (such as the ARAMIS microseismic monitoring system), it can effectively determine the roof fracture structure and the critical layer causing the disaster, and further determine reasonable blasting parameters such as blasting depth and blasting hole elevation angle. This can significantly improve blasting efficiency, accuracy, and pressure relief effect. After construction, it effectively reduces stress concentration, improves roadway stability, and is conducive to safe tunneling in rockburst-prone working faces. Attached Figure Description

[0034] Figure 1 This is a distribution diagram of the high-stress zone in a mine tunneling face according to the present invention;

[0035] Figure 2 This invention relates to a key layer and blasting design line diagram for a certain mine.

[0036] Figure 3 This is a schematic diagram of the pressure relief hole for blasting the roof of a mine according to the present invention. Detailed Implementation

[0037] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments, so that those skilled in the art can better understand the present invention and implement it. However, the embodiments are not intended to limit the present invention.

[0038] A method for blasting and relieving pressure on the roof of a high-stress zone in an underground coal mine tunneling face includes the following steps:

[0039] Step 1, as follows Figure 1 As shown, the high-stress zone of the tunneling face is determined, and its length along the face is L. f High-stress areas are areas that need to be addressed. They are usually located in areas such as connecting roadways, chambers, and areas with abnormal geological structures in the tunneling face. Specifically, they refer to areas where one or more monitoring indicators, such as micro-vibration, stress, drill cuttings, and roadway deformation, exceed the critical value. The geological and production conditions of each mine are different, and the critical value can be set according to actual needs.

[0040] Step 2: Due to significant variations in roof lithology at different locations, it is preferable to establish a new core sampling hole XK in the central part of the high-stress zone to determine the roof strata structure. When the mining schedule is tight, the high-stress zone L can be initially utilized. f The stratigraphic structure of the roof strata in the high-stress zone is determined using the columnar section diagram ZK of adjacent drilled boreholes. In this embodiment, due to the tight schedule of the mine, [the following is used]. Figure 1 The stratigraphic structure of the top strata in the high-stress zone is determined by using the borehole columnar section ZK adjacent to the left side of the high-stress zone as a reference, as shown in Table 1.

[0041] Table 1. Structure of the roof strata of ZK

[0042] Serial Number Lithology Thickness / m <![CDATA[Body force / (kN / m 3 )]]> Tensile strength / MPa Elastic modulus / GPa 4 fine-grained sandstone 5.2 20.8 2.229 12.243 3 Sandy mudstone 31.87 23.3 3.587 5.914 2 medium-grained sandstone 11.96 20.8 2.229 12.243 1 Sandy mudstone 3.84 23.6 2.506 8.544

[0043] Step 3: Calculate the first key layer K1, the second key layer K2, ..., the i-th key layer K using XK or ZK respectively. i ...the m-th critical layer K m And calculate the first key layer K1, the second key layer K2, ... the i-th key layer K respectively. i ...the m-th critical layer K m The distances between the top of the coal seam and the top of the coal seam are a1, a2, ... a i ...a m , where m is the total number of key layers in the top strata.

[0044] Specifically, preferably, step 3, which involves calculating the key strata of the roof strata and the distance between the top of the key strata and the coal seam using XK or ZK, includes:

[0045] Step 301: Calculate the influence of the nth stratum above the coal seam roof on the first key stratum, and the resulting overlying stratum load q. n The expression is:

[0046]

[0047] In the formula, E1, E2...E n These are the elastic moduli of the 1st, 2nd...nth rock layers, h1, h2...h n These represent the thicknesses of rock layers 1, 2...n, γ1, γ2...γ... n These are the volume forces of the 1st, 2nd...nth rock layers, respectively.

[0048] Step 302: When the (n+1)th rock layer satisfies the following formula, it is determined to be a key layer:

[0049]

[0050] In the formula, q n+1The load of the (n+1)th stratum above the coal seam roof on the first key stratum is the overlying stratum load, l. n+1 l is the fracture distance of the (n+1)th stratum above the coal seam roof. n This is the fracture distance of the nth stratum above the coal seam roof. In other words, the fracture distance of the next stratum is less than the fracture distance of the previous stratum.

[0051] Preferably, the fracture distance of the i-th rock layer is l i Calculate according to the following formula:

[0052]

[0053] In the formula, R i Let q be the uniaxial tensile strength of the i-th rock layer. i h represents the load on the i-th rock layer from the overlying strata. i Let be the thickness of the i-th rock layer.

[0054] Step 303: Calculate the distances a1, a2...a1 between the top of each key stratum and the coal seam based on the location of the key strata in each roof stratum. i ...a m ,right Figure 1 The calculations were performed using the Chinese implementation examples, and the results are shown in Table 2.

[0055] Table 2 Calculation of Key Layers in ZK Top Slab

[0056]

[0057]

[0058] Calculations show that the device has two critical layers: a1 is 15.8m and a2 is 47.67m.

[0059] Step 4: Use a microseismic monitoring system to collect data on the vertical distances between high-energy microseismic events during tunneling in high-stress areas and the coal seam, namely A1, A2...A... i ...A m The horizontal distances from the coal face are X1, X2...X i ...X m Thus, the rock fracture line B was obtained.

[0060] Preferably, in step 4, the microseismic monitoring system is the ARAMIS microseismic monitoring system, and the high-energy microseismic events are cubic microseismic events. During the underground working face excavation, the microseismic event energy collected by the ARAMIS microseismic monitoring system is mainly quadratic. When excavating through high-stress areas, higher-energy cubic events will be collected. The preliminary inference is that the long rock strata structure is fractured, bringing safety hazards. Therefore, by collecting the vertical position and the dip position along the working face of the cubic microseismic events, the rock strata fracture line B can be obtained.

[0061] In this embodiment, the ARAMIS microseismic monitoring system is used to collect data. Figure 1 The vertical distances between the high-energy cubic microseismic events during tunneling in the medium-high stress zone and the coal seam are A1, A2, A3, and A4, respectively, and the horizontal distances to the coal wall are X1, X2, X3, and X4, respectively, as shown in Table 3. Further, the rock strata fracture line B is obtained, as shown in Table 3. Figure 2 As shown, the sequential line connecting the endpoints w1, w2, w3, and w4 is the rock fracture line B.

[0062] Table 3. Statistics of cubic events in high-stress areas

[0063] Serial Number Vertical distance from coal seam / m Horizontal distance of coal face / m Energy / j 1 15 27 1060 2 9 21 1030 3 22 34 1730 4 4 9 1230

[0064] Step 5: Combine a1, a2...a i ...a m A1, A2...A i ...A m X1, X2...X i ...X m And B, calculate the roof blasting pressure relief and hazard mitigation parameters. Preferably, the roof blasting pressure relief and hazard mitigation parameters include the blast hole diameter D, blasting height A, blast hole depth E, blast hole elevation angle β, charge length ZL, and sealing length FL, wherein:

[0065] The diameter D of the blasting hole is obtained based on the size of the drill bit. If the drill bit size is 0.089m, then D = 0.089m.

[0066] Explosion height A = max{a1, a2, ..., a i ...a m A1, A2...A i ...A m};

[0067] The blast hole elevation angle β is obtained from the rock fracture line B, such as... Figure 3 As shown, in this embodiment, β = 33°;

[0068] The depth of the blast hole is E = A / sinβ = 87.53m;

[0069] ZL+FL=E, and

[0070] The charge length ZL should, in principle, cover all critical layers. To ensure blasting safety, the sealing length FL should not be less than 1 / 3 of the blasting hole depth. When there is a conflict between the charge length ZL and the sealing length FL, priority should be given to ensuring that the sealing length FL meets the requirements before designing the charge length ZL. In this embodiment, ZL = 57.53m, FL = 30m, and the parameters for decompression and hazard relief during roof blasting are shown in Table 4.

[0071] Table 4. Parameters for Decompression and Safety Relief from Blasting of the Roof Plate in High-Stress Zones

[0072] D / m β / ° E / m ZL / m FL / m 0.089 33 87.53 57.53 30

[0073] Step 6: Perform roof blasting and depressurization based on the roof blasting and depressurization parameters obtained in Step 5.

[0074] This invention provides a method for blasting and relieving pressure on the roof of a high-stress zone in an underground coal mine tunneling face. Combined with a microseismic monitoring system (such as the ARAMIS microseismic monitoring system), it can effectively determine the roof fracture structure and further determine reasonable blasting parameters. This can significantly improve blasting efficiency, accuracy, and pressure relief effect. After construction, it effectively reduces stress concentration, improves roadway stability, and is conducive to safe tunneling in rockburst-prone working faces.

[0075] The above are merely preferred embodiments of the present invention and do not limit the patent scope of the present invention. Any equivalent structural or procedural transformations made based on the content of the present invention's specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A method for blasting and relieving pressure on the roof of a high-stress zone in an underground coal mine tunneling face, characterized in that, Includes the following steps: Step 1: Determine the high-stress zone of the tunneling face, with a length L along the direction of the face. f ; Step 2: Arrange core holes XK in the middle of the high-stress zone or use the borehole columnar section ZK adjacent to the high-stress zone to determine the top strata structure of the high-stress zone. Step 3: Calculate the first key layer K1, the second key layer K2, ..., the i-th key layer K using XK or ZK respectively. i ...the m-th critical layer K m And calculate the first key layer K1, the second key layer K2, ... the i-th key layer K respectively. i ...the m-th critical layer K m The distances between the top of the coal seam and the top of the coal seam are a1, a2, ... a i ...a m , where m is the total number of key layers in the top strata; Step 4: Use a microseismic monitoring system to collect data on the vertical distances between high-energy microseismic events during tunneling in high-stress areas and the coal seam, namely A1, A2...A... i ...A m The horizontal distances from the coal face are X1, X2...X i ...X m The rock fracture line B is obtained; Step 5: Combine a1, a2...a i ...a m A1, A2...A i ...A m X1, X2...X i ...X m And B, calculate the parameters for decompression and hazard relief during roof blasting; Step 6: Perform roof blasting and depressurization based on the roof blasting and depressurization parameters obtained in Step 5.

2. The method for blasting and relieving pressure on the roof of a high-stress zone in an underground coal mine tunneling face according to claim 1, characterized in that, In step 4, the microseismic monitoring system is the ARAMIS microseismic monitoring system, and the high-energy microseismic events are cubic microseismic events.

3. The method for blasting and relieving pressure on the roof of a high-stress zone in an underground coal mine tunneling face according to claim 2, characterized in that, The parameters for blasting and decompression of the top plate include the blast hole diameter D, blast height A, blast hole depth E, blast hole elevation angle β, charge length ZL, and sealing length FL.

4. The method for blasting and relieving pressure on the roof of a high-stress zone in an underground coal mine tunneling face according to claim 3, characterized in that, Step 3, which involves calculating the key strata of the roof strata and the distance between the top of the key strata and the coal seam using XK or ZK, includes: Step 301: Calculate the influence of the nth stratum above the coal seam roof on the first key stratum, and the resulting overlying stratum load q. n The expression is: In the formula, E1, E2...E n These are the elastic moduli of the 1st, 2nd...nth rock layers, h1, h2...h n These represent the thicknesses of rock layers 1, 2...n, γ1, γ2...γ... n These are the volume forces of the 1st, 2nd...nth rock layers, respectively; Step 302: When the (n+1)th rock layer satisfies the following formula, it is determined to be a key layer: In the formula, q n+1 The load of the (n+1)th stratum above the coal seam roof on the first key stratum is the overlying stratum load, l. n+1 l is the fracture distance of the (n+1)th stratum above the coal seam roof. n The fracture distance of the nth rock layer above the coal seam roof; Step 303: Calculate the distances a1, a2...a1 between the top of each key stratum and the coal seam based on the location of the key strata in each roof stratum. i ...a m .

5. A method for blasting and relieving pressure on the roof of a high-stress zone in an underground coal mine tunneling face according to claim 4, characterized in that, The fracture distance of the i-th rock layer is l i Calculate according to the following formula: In the formula, R i Let q be the uniaxial tensile strength of the i-th rock layer. i h represents the load on the i-th rock layer from the overlying strata. i Let be the thickness of the i-th rock layer.

6. The method for blasting and relieving pressure on the roof of a high-stress zone in an underground coal mine tunneling face according to claim 4, characterized in that: The diameter D of the blast hole is obtained based on the drill bit size of the drilling tool; Explosion height A = max{a1, a2, ..., a i ...a m A1, A2...A i ...A m }; The blast hole elevation angle β is obtained from the rock fracture line B; The depth of the blast hole is E = A / sinβ; ZL+FL=E, and

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