Coal mine underground driving working face high-stress area roof blasting pressure relief danger relieving method

Abstract

The invention discloses an underground coal mine driving working face high-stress area roof blasting pressure relief danger relieving method. The method comprises the steps that 1, a driving working face high-stress area is determined; 2, determining a roof rock stratum structure of a high-stress area; 3, respectively calculating each key layer of the roof rock stratum and the distance between the top of each key layer and the coal seam through XK or ZK; step 4, collecting the vertical distance between the macro-energy micro-seismic event and the coal seam and the horizontal distance between the macro-energy micro-seismic event and the coal wall in the tunneling period of the high-stress area by using the micro-seismic monitoring system to obtain a rock stratum fracture line B; 5, top plate blasting pressure relief and danger relief parameters are calculated in a combined mode; and 6, roof blasting pressure relief is conducted according to the roof blasting pressure relief danger relieving parameters obtained in the step 5. According to the method, the roof fracture structure can be effectively determined, reasonable blasting parameters can be further determined, the blasting efficiency and accuracy and the pressure relief and danger relief effect can be remarkably improved, stress concentration is effectively reduced after construction, the roadway stability is improved, and safe tunneling of the rock burst working face is facilitated.

Description

Technical Field

[0001] The invention relates to a method for blasting and decompressing a roof in a high stress zone of an underground coal mine excavation working face. Background Art

[0002] Rock burst disaster is a highly destructive rock dynamic disaster with strong dynamic instability characteristics. In recent years, due to the continuous increase in the depth of underground coal mining, the frequency and intensity of rock burst disasters have continued to increase. Rock burst disasters have occurred in various coal-producing countries, causing certain casualties and property losses.

[0003] Engineering and technical personnel at home and abroad have carried out a lot of research work on the prevention and control technology of rock burst disasters and proposed many feasible methods. Among them, roof blasting unloading technology is a relatively effective method for preventing and controlling rock burst disasters. The blasting parameters in the roof blasting unloading technology directly affect the unloading and disaster relief effect. At present, the determination of conventional blasting parameters is not targeted, the effect is often poor and needs to be continuously adjusted and optimized in the future, and there are limitations in practical applications. Summary of the invention

[0004] In view of the above problems, the present invention provides a method for blasting and unloading pressure in the high-stress area of ​​the roof of an underground coal mine excavation working face. Combined with a microseismic monitoring system (such as the ARAMIS microseismic monitoring system), it can effectively determine the roof rupture structure and further determine reasonable blasting parameters, which can significantly improve the blasting efficiency, accuracy and pressure unloading effect.

[0005] In order to achieve the above technical objectives and the above technical effects, the present invention is implemented through the following technical solutions:

[0006] A method for blasting and decompressing the roof of a high stress area in an underground coal mine excavation working face, comprising the following steps:

[0007] Step 1: Determine the high stress area of ​​the excavation working face, and its length along the working face is L f ;

[0008] Step 2: arrange a core hole XK in the middle of the high stress area or use the adjacent drill hole histogram ZK of the high stress area to determine the top rock structure of the high stress area;

[0009] Step 3: Calculate the first key layer K1, the second key layer K2, and the i-th key layer K of the roof rock layer through XK or ZK. i ...the mth key layer K m , and calculate the first key layer K1, the second key layer K2, ... the i-th key layer K i ...the mth key layer K m The distances between the top and the coal seam are a1, a2, ... ai ……a m , where m is the total number of key layers of the roof rock strata;

[0010] Step 4: Use the microseismic monitoring system to collect the vertical distances between the large-energy microseismic events and the coal seam during the excavation in the high-stress area, which are A1, A2, ..., A i ...A m , the horizontal distances from the coal wall are X1, X2...X i ...X m , and obtain the rock formation fracture line B;

[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 roof blasting decompression and emergency relief;

[0012] Step 6: Perform roof blasting decompression according to the roof blasting decompression and emergency relief parameters obtained in step 5.

[0013] Preferably, in step 4, the microseismic monitoring system is an ARAMIS microseismic monitoring system, and the large-energy microseismic event is a cubic microseismic event.

[0014] Preferably, the roof blasting decompression and emergency relief parameters include blasting hole diameter D, blasting height A, blasting hole depth E and blasting hole elevation angle β, charging length ZL and sealing hole length FL.

[0015] Preferably, the step of calculating the key layer of the roof rock layer and the distance between the top of the key layer and the coal seam by XK or ZK in step 3 includes:

[0016] Step 301: Calculate the overburden load q caused by the influence of the nth rock layer above the coal seam roof on the first key rock layer. n The expression is:

[0017]

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

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

[0020]

[0021] In the formula, q n+1 is the overburden load of the n+1th layer of rock above the coal seam roof on the first key rock layer, l n+1 is the breaking distance of the n+1th rock layer above the coal seam roof, l n is the breaking distance of the nth rock layer above the coal seam roof;

[0022] Step 303: Calculate the distances a1, a2, ..., a between the top of each key layer and the coal seam according to the key layer positions of each roof rock layer. i ……a m .

[0023] Preferably, the breaking distance l of the i-th rock layer i Calculated according to the following formula:

[0024]

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

[0026] Preferred:

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

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

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

[0030] Depth of blast hole E = A / sinβ;

[0031] ZL+FL=E, and

[0032] The beneficial effects of the present invention are:

[0033] The elevation angle of the blast hole in the traditional blasting parameter design is often based on experience. When the elevation angle is too small, the key disaster-causing layer cannot be pre-cracked in time, and the danger cannot be eliminated. When the elevation angle is too large, underground construction is difficult, and it is easy to cause the local blasting construction area to be located in the coal pillar area, which is easy to cause the coal pillar to become unstable and impact-damaged, bringing hidden dangers to underground production safety. The depth of the blast hole in the traditional blasting parameter design is often designed based on the rough estimate of the thick and hard rock layer based on the bar chart. After the final blasting pressure relief, the stress concentration has not been reduced or the reduction is too small, and the risk still exists. The present invention provides a method for decompression and emergency relief by blasting the roof in a high-stress area of ​​an underground coal mine excavation working face. Combining the traditional key layer theory and an on-site microseismic monitoring system (such as an ARAMIS microseismic monitoring system), the method can effectively determine the roof rupture structure and the disaster-causing key layer, and further determine reasonable blasting parameters such as blasting depth and blasting hole elevation angle. The method can significantly improve the blasting efficiency, accuracy and decompression and emergency relief effects. After construction, the stress concentration is effectively reduced, the stability of the tunnel is improved, and it is beneficial to the safe excavation of the rock burst working face. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 This is a distribution diagram of high stress areas in a mine excavation working face of the present invention;

[0035] Figure 2 It is a key layer and blasting design line diagram of a mine of the present invention;

[0036] Figure 3 It is a schematic diagram of a mine roof blasting pressure relief hole according to the present invention. DETAILED DESCRIPTION

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

[0038] A method for blasting and decompressing the roof of a high stress area in an underground coal mine excavation working face, comprising the following steps:

[0039] Step 1: Figure 1 As shown in the figure, the high stress area of ​​the excavation working face is determined, and its length along the working face is L f The high stress area is the area that needs to be de-risked, usually located in the tunneling working face, chambers, geological structure anomalies and other areas. Specifically, it refers to the area where one of the monitoring indicators such as microseismic, stress, drill cuttings, and tunnel deformation exceeds the critical value. The geological conditions and production conditions of each mine are different, and the critical value can be set according to actual needs.

[0040] Step 2: Since the rock properties of the roof vary greatly at different locations, it is preferred to arrange a new core hole XK in the middle of the high stress area to determine the roof rock structure. f The adjacent constructed borehole columnar diagram ZK is used to determine the roof rock structure of the high stress area. Figure 1 The top rock structure of the high stress zone is determined based on the adjacent borehole column diagram ZK on the left side of the medium and high stress zone, see Table 1.

[0041] Table 1 ZK roof rock structure

[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, and the i-th key layer K of the roof rock layer through XK or ZK. i ...the mth key layer K m , and calculate the first key layer K1, the second key layer K2, ... the i-th key layer K i ...the mth key layer K m The distances between the top and the coal seam are a1, a2, ... a i ……a m , where m is the total number of key layers of the roof rock strata.

[0044] Specifically, preferably, the step of calculating the key layer of the roof rock layer and the distance between the top of the key layer and the coal seam by XK or ZK in step 3 includes:

[0045] Step 301: Calculate the overburden load q caused by the influence of the nth rock layer above the coal seam roof on the first key rock layer. n The expression is:

[0046]

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

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

[0049]

[0050] In the formula, q n+1 is the overburden load of the n+1th layer of rock above the coal seam roof on the first key rock layer, ln+1 is the breaking distance of the n+1th rock layer above the coal seam roof, l n It is the breaking distance of the nth rock layer above the coal seam roof. That is, the breaking distance of the next rock layer is smaller than the breaking distance of the previous rock layer.

[0051] Among them, preferably, the breaking distance l of the i-th rock layer i Calculated according to the following formula:

[0052]

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

[0054] Step 303: Calculate the distances a1, a2, ..., a between the top of each key layer and the coal seam according to the key layer positions of each roof rock layer. i ……a m ,right Figure 1 The calculation results are shown in Table 2.

[0055] Table 2 ZK roof key layer calculation

[0056] Lithology Thickness / m Distance from coal seam / m Load bearing / kPa Key layer type Sandy mudstone 31.87 47.67 843.1492 The second key layer Medium-grained sandstone 11.96 15.8 248.768 The first key layer

[0057] Through calculation, it can be known that there are two key layers in the device, a1 is 15.8m and a2 is 47.67m.

[0058] Step 4: Use the microseismic monitoring system to collect the vertical distances between the large-energy microseismic events and the coal seam during the excavation in the high-stress area, which are A1, A2, ..., A i ...A m , the horizontal distances from the coal wall are X1, X2...X i ...X m , and obtain the rock fracture line B.

[0059] Preferably, in step 4, the microseismic monitoring system is an ARAMIS microseismic monitoring system, and the large-energy microseismic event is a cubic microseismic event. During the excavation of the underground working face, the energy of the microseismic events collected by the ARAMIS microseismic monitoring system is mainly quadratic. When the excavation is too high in the stress area, cubic events with higher energy will be collected. The preliminary inference is that the longer rock structure has cracked, posing a safety hazard. Therefore, by collecting the vertical position of the cubic microseismic event and the position along the inclination of the working face, the rock fracture line B can be obtained.

[0060] In this embodiment, the ARAMIS microseismic monitoring system is used to collect Figure 1During the excavation in the medium and high stress zone, the vertical distances of the large energy cubic microseismic events to the coal seam are A1, A2, A3 and A4, and the horizontal distances to the coal wall are X1, X2, X3 and X4, as shown in Table 3. The rock stratum fracture line B is further obtained, as shown in Figure 2 As shown, the lines connecting the end points, w1, w2, w3 and w4 in sequence are the rock fracture lines B.

[0061] Table 3 Statistics of cubic events in high stress areas

[0062] Serial number Vertical distance from coal seam / m Horizontal distance of coal wall / m Energy / j 1 15 27 1060 2 9 21 1030 3 22 34 1730 4 4 9 1230

[0063] 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 decompression and emergency relief parameters, preferably, the roof blasting decompression and emergency relief parameters include blasting hole diameter D, blasting height A, blasting hole depth E and blasting hole elevation angle β, charging length ZL and sealing hole length FL, wherein:

[0064] The blast hole diameter D is obtained according to the drill bit size of the drilling tool. If the drill bit size of the drilling rig is 0.089m, then D = 0.089m;

[0065] Blasting height A = max{a1, a2...a i ……a m , A1, A2...A i ...A m};

[0066] The blast hole elevation angle β is obtained according to the rock fracture line B, as Figure 3 As shown, in this embodiment, β = 33°;

[0067] Depth of blast hole E = A / sinβ = 87.53m;

[0068] ZL+FL=E, and

[0069] In principle, the charge length ZL should cover all key layers. In order 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, the sealing length FL should be guaranteed to meet the requirements first, and then the charge length ZL should be designed. In this embodiment, ZL = 57.53m, FL = 30m, and the roof blasting decompression and emergency relief parameters are shown in Table 4.

[0070] Table 4 Parameters of roof blasting decompression and emergency relief in high stress area

[0071] D / m β / ° E / m ZL / m FL / m 0.089 33 87.53 57.53 30

[0072] Step 6: Perform roof blasting decompression according to the roof blasting decompression and emergency relief parameters obtained in step 5.

[0073] The present invention provides a method for decompression and emergency relief by blasting the roof in a high-stress area of ​​an underground coal mine excavation working face. Combined with a microseismic monitoring system (such as an ARAMIS microseismic monitoring system), the method can effectively determine the roof rupture structure and further determine reasonable blasting parameters, which can significantly improve the blasting efficiency, accuracy and decompression and emergency relief effects. After construction, stress concentration is effectively reduced, tunnel stability is improved, and safe excavation of the impact ground pressure working face is facilitated.

[0074] The above are only preferred embodiments of the present invention, and are not intended to limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made using the contents of the present invention specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A method for decompression and emergency relief of the roof blasting in a high stress area of ​​an underground coal mine excavation working face, characterized in that: The following steps are involved: Step 1: Determine the high stress area of ​​the excavation working face, and its length along the working face is L f ; Step 2: arrange a core hole XK in the middle of the high stress area or use the adjacent drill hole histogram ZK of the high stress area to determine the top rock structure of the high stress area; Step 3: Calculate the first key layer K1, the second key layer K2, and the i-th key layer K of the roof rock layer through XK or ZK. i ...the mth key layer K m , and calculate the first key layer K1, the second key layer K2, ... the i-th key layer K i ...the mth key layer K m The distances between the top and the coal seam are a1, a2, ... a i ……a m , where m is the total number of key layers of the roof rock strata; Step 4: Use the microseismic monitoring system to collect the vertical distances between the large-energy microseismic events and the coal seam during the excavation in the high-stress area, which are A1, A2, ..., A i ……A m , the horizontal distances from the coal wall are X1, X2...X i ...X m , and obtain the rock formation fracture line B; 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 roof blasting decompression and emergency relief; Step 6: Perform roof blasting decompression according to the roof blasting decompression and emergency relief parameters obtained in step 5.

2. A method for decompression and emergency relief of the roof of a high stress area in an underground coal mine excavation working face according to claim 1, characterized in that: In step 4, the microseismic monitoring system is the ARAMIS microseismic monitoring system, and the large-energy microseismic events are cubic microseismic events.

3. A method for decompression and emergency relief by blasting the roof of a high stress area in an underground coal mine excavation working face according to claim 2, characterized in that: The roof blasting decompression and emergency relief parameters include blasting hole diameter D, blasting height A, blasting hole depth E and blasting hole elevation angle β, charging length ZL and sealing hole length FL.

4. A method for decompression and emergency relief of the roof blasting in a high stress area of ​​an underground coal mine excavation working face according to claim 3, characterized in that: The steps of calculating the key layer of the roof rock layer and the distance between the top of the key layer and the coal seam by XK or ZK in step 3 include: Step 301: Calculate the overburden load q caused by the influence of the nth rock layer above the coal seam roof on the first key rock layer. n The expression is: In the formula, E1, E2...E n are the elastic moduli of the 1st, 2nd…nth rock layers, h1, h2…h n are the thicknesses of the 1st, 2nd…nth rock layers, γ1, γ2…γ n are the volume forces of the 1st, 2nd…nth rock layers respectively; Step 302: When the n+1th rock layer satisfies the following formula, it is determined to be a key layer: In the formula, q n+1 is the overburden load of the n+1th layer of rock above the coal seam roof on the first key rock layer, l n+1 is the breaking distance of the n+1th rock layer above the coal seam roof, l n is the breaking distance of the nth rock layer above the coal seam roof; Step 303: Calculate the distances a1, a2, ..., a between the top of each key layer and the coal seam according to the key layer positions of each roof rock layer. i ……a m .

5. A method for decompression and emergency relief by blasting the roof of a high stress area in an underground coal mine excavation working face according to claim 4, characterized in that: The breaking distance l of the i-th rock layer i Calculated according to the following formula: In the formula, R i is the uniaxial tensile strength of the i-th rock layer, q i is the load on the overlying rock layer on the i-th rock layer, h i is the thickness of the i-th rock layer.

6. A method for decompression and emergency relief of the roof of a high stress area in an underground coal mine excavation working face according to claim 4, characterized in that: The blast hole diameter D is obtained according to the drill bit size of the drilling tool; Blasting height A = max{a1, a2...a i ……a m , A1, A2...A i ……A m }; The blast hole elevation angle β is obtained according to the rock fracture line B; Depth of blast hole E = A / sinβ; ZL+FL=E, and

Images