Early warning method for rock burst in advance area of working face based on blasting energy density

Abstract

The invention relates to a blasting energy density-based early warning method for rock burst in a working face advance area. The method comprises the following steps of: determining a working face construction advance presplitting blasting pressure relief position every day according to geological factors and mining technical factors; the explosive loading amount m needed by the daily advanced presplitting blasting pressure relief position is manually recorded, and blasting is conducted; a micro-seismic monitoring system is used for monitoring, recording and collecting a waveform signal actively excited by blasting pressure relief, and energy solution is carried out; a blasting energy density index is introduced to eliminate an energy size error caused by the explosive loading amount of actual construction; when the blasting energy density tends to continuously increase or the energy density is in a high-value state, it is judged that the advance area of the working face has the impact danger. According to the method, dynamic monitoring and early warning of the daily impact risk of the working face advance area are realized while blasting presplitting energy release of the working face advance area is realized, and safe mining of a coal mine is guaranteed. The method is simple, convenient and high in operability.

Description

Technical Field

[0001] The invention relates to an early warning method for rock burst in an advance area of ​​a working face based on blasting energy density, and belongs to the technical field of safe mining of coal mines. Background Art

[0002] Due to geological conditions and mining technology limitations, when extra-thick coal seams are mined in layers, in order to reduce the impact of the inclined roof on adjacent tunnels and mining areas, a wide protective coal pillar is set to maintain the stability of the mining tunnel. This wide coal pillar is called a critical coal pillar, and its existence is not conducive to the prevention and control of rock burst. The stress concentration of the coal body in the critical coal pillar is high, and the integrity of the rock layer on the roof of the coal pillar is relatively good. After the upper layer is mined, the stress in the remaining coal pillar area is highly concentrated, and a high stress area is formed in the local area of ​​the lower layer, which increases the risk of rock burst during the mining of the lower layer working face.

[0003] The existing monitoring and early warning of rock burst mainly include local monitoring and regional monitoring. Among them, local monitoring mainly uses online, ground sound, drill cuttings and other methods, which are aimed at the rock burst danger in the mining area. Its advantages are simple, easy, intuitive and reliable, but it cannot form continuous monitoring in time and space; regional monitoring mainly uses microseismic monitoring system, which can realize continuous monitoring of coal rock mass in space and time, but microseismic prediction indicators cannot accurately predict the rock burst danger in the mining area. Summary of the invention

[0004] The present invention provides an early warning method for rock burst in an area ahead of a working face based on blasting energy density. The method can determine the rock burst hazard in the area ahead of a working face, and simultaneously realize blasting pre-cracking to release energy in the area ahead of a working face, and simultaneously perform dynamic monitoring and early warning of the rock burst hazard in the area ahead of a working face on a daily basis, thereby ensuring safe mining of coal mines.

[0005] In order to achieve the above object, the present invention provides an early warning method for rock burst pressure in the leading area of ​​a working face based on blasting energy density, comprising the following steps:

[0006] (1) Determine the location of pre-splitting blasting and pressure relief at the working face every day based on geological factors and mining technology factors;

[0007] (2) Since the designed charge amount cannot be reached due to the possibility of hole collapse during on-site blasting and drilling, it is necessary to manually record the charge amount m required for the daily advance pre-splitting blasting pressure relief position and carry out blasting;

[0008] (3) Use the microseismic monitoring system to monitor, record and collect the waveform signals actively excited by blasting decompression, and solve the energy;

[0009] (4) The energy generated by blasting is related to the charge amount. The charge amount varies due to geological factors at the construction site. The blasting energy density index is introduced to eliminate the energy error caused by the charge amount. The blasting energy density is solved by the ratio of the vibration energy induced by a single blasting to the single charge amount. The blasting energy density J is the ratio of the energy E solved by the microseismic monitoring system to the actual charge m, and the calculation formula is J = E / m;

[0010] (5) When the blasting energy density trend continues to increase or the energy density is at a high value, that is, the energy density is greater than 1000 J / kg, it is determined that the leading area of ​​the working face has an impact hazard.

[0011] Furthermore, the method for solving the energy in step (3) is:

[0012] a. Vibration waveform collection: Install the SOS microseismic monitoring system in the coal mine. The SOS microseismic monitoring system includes an above-ground collection and recording device and multiple probes installed underground. Multiple probes are installed on the coal seam floor. The SOS microseismic monitoring system is used to collect energy information released by blasting and record and store it;

[0013] b. Energy calculation: The vibration velocity information v(t) is measured by the probe, and its energy density ε(r) is obtained. The vibration wave is regarded as a spherical wave, and the energy density is multiplied by the surface area S(R) of the sphere to obtain the vibration energy E. According to the energy attenuation F(r) = (2r) 2n e α(2r-1) , the vibration energy calculation formula is E = ε(r)·S(R)·F(r).

[0014] The present invention determines the pre-splitting blasting pressure relief position, manually records the charge amount required for the daily advance pre-splitting blasting pressure relief position, and uses the microseismic monitoring system to monitor, record and collect the waveform signal actively excited by the blasting pressure relief, and solves the energy. The blasting energy density index is introduced to eliminate the energy size error caused by the charge amount in the actual construction. When the blasting energy density trend continues to increase or the energy density is at a high value, it is determined that the leading area of ​​the working face has an impact hazard. The present invention realizes the dynamic monitoring and early warning of the daily impact hazard of the leading area of ​​the working face while releasing energy in the blasting pre-splitting area of ​​the working face, thereby ensuring the safe mining of the coal mine. The method is simple, convenient and easy to operate. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a work flow chart of the present invention;

[0016] Figure 2 It is a schematic diagram of the blasting energy density change trend, daily blasting energy density value and warning threshold value in an embodiment of the present invention. DETAILED DESCRIPTION

[0017] The present invention will be further described below in conjunction with the accompanying drawings.

[0018] like Figure 1 As shown, a method for early warning of rock burst in the leading area of ​​a working face based on blasting energy density comprises the following steps:

[0019] (1) Determine the location of pre-splitting blasting and pressure relief at the working face every day based on geological factors and mining technology factors;

[0020] (2) Since the designed charge amount cannot be reached due to the possibility of hole collapse during on-site blasting and drilling, it is necessary to manually record the charge amount m required for the daily advance pre-splitting blasting pressure relief position and carry out blasting;

[0021] (3) Use the microseismic monitoring system to monitor, record and collect the waveform signals actively excited by blasting decompression, and solve the energy;

[0022] (4) The energy generated by blasting is related to the charge amount. The charge amount varies due to geological factors at the construction site. The blasting energy density index is introduced to eliminate the energy error caused by the charge amount. The blasting energy density is solved by the ratio of the vibration energy induced by a single blasting to the single charge amount. The blasting energy density J is the ratio of the energy E solved by the microseismic monitoring system to the actual charge m, and the calculation formula is J = E / m;

[0023] (5) When the blasting energy density trend continues to increase or the energy density is at a high value, that is, the energy density is greater than 1000 J / kg, it is determined that the leading area of ​​the working face has an impact hazard.

[0024] As a preferred embodiment, the method for solving the energy in step (3) is:

[0025] a. Vibration waveform collection: Install the SOS microseismic monitoring system in the coal mine. The SOS microseismic monitoring system includes an above-ground collection and recording device and multiple probes installed underground. Multiple probes are installed on the coal seam floor. The SOS microseismic monitoring system is used to collect energy information released by blasting and record and store it;

[0026] b. Energy calculation: The vibration velocity information v(t) is measured by the probe, and its energy density ε(r) is obtained. The vibration wave is regarded as a spherical wave, and the energy density is multiplied by the surface area S(R) of the sphere to obtain the vibration energy E. According to the energy attenuation F(r) = (22r) 2n e α(2r-1) , the vibration energy calculation formula is E = ε(r)·S(R)F(r).

[0027] Embodiment: (1) Taking the 250101-2 working face of a certain mine as an example, the stress of the working face is highly concentrated under the influence of the overlying legacy coal pillar. Therefore, it is necessary to construct a roof deep hole blasting pressure relief measure under the overlying coal pillar of the 250101-2 working face to relieve the pressure of the working face;

[0028] (2) Record the actual charge volume m of the daily construction blasting pressure relief measures. Select the actual charge volume of the daily construction blasting pressure relief measures from September 1, 2023 to September 25, 2023 as m. 9-1 =180kg,m 9-2 =165kg, m 9-3 =135kg, ...m 9-25 =135kg;

[0029] (3) The waveform signal generated by the blasting is recorded and collected using the microseismic monitoring system, and the energy is solved using the SOS microseismic monitoring system to obtain E 9-1 =1.97E+05J,E 9-2 =2.08E+05J,E 9-3 =8.30E+04J,……E 9-25 =1.03E+05J;

[0030] (4) In order to eliminate the difference in blasting energy caused by different charge amounts, the blasting energy density index J is solved according to the formula J = E / m, and the result is: J 9-1 =1.09E+03J / kg, J 9-2 =1.26E+03J / kg, J 9-3 =6.15E+02J / kg, ...J 9-25 =7.63E+02J / kg;

[0031] (5) Analyze the blasting energy density and its changing trend to conduct dynamic monitoring and early warning of rock burst in the leading area of ​​the working face: Figure 2 As shown, if the single-day blasting energy density is below the medium impact hazard warning value, the working face can produce normally; if it is above the medium impact hazard, certain pressure relief measures are needed, and after pressure relief, impact hazard monitoring is carried out in combination with other impact ground pressure monitoring and early warning methods. If the impact hazard is reduced after taking pressure relief measures, normal production can be carried out.

Claims

1. A method for early warning of rock burst pressure in the leading area of ​​a working face based on blasting energy density, characterized in that: The steps include: (1) Determine the location of pre-splitting blasting and pressure relief at the working face every day based on geological factors and mining technology factors; (2) Manually record the amount of explosives m required for the daily advance pre-splitting blasting pressure relief position and carry out blasting; (3) Use the microseismic monitoring system to monitor, record and collect the waveform signals actively excited by blasting decompression, and solve the energy; (4) The energy generated by blasting is related to the charge amount. The charge amount varies due to geological factors at the construction site. The blasting energy density index is introduced to eliminate the energy error caused by the charge amount. The blasting energy density is solved by the ratio of the vibration energy induced by a single blasting to the single charge amount. The blasting energy density J is the ratio of the energy E solved by the microseismic monitoring system to the actual charge m, and the calculation formula is J = E / m; (5) When the blasting energy density trend continues to increase or the energy density is at a high value, that is, the energy density is greater than 1000 J / kg, it is determined that the leading area of ​​the working face has an impact hazard.

2. The early warning method for rock burst in the leading area of ​​the working face based on blasting energy density according to claim 1 is characterized in that: The method for solving the energy in step (3) is: a. Vibration waveform collection: Install the SOS microseismic monitoring system in the coal mine. The SOS microseismic monitoring system includes an above-ground collection and recording device and multiple probes installed underground. Multiple probes are installed on the coal seam floor. The SOS microseismic monitoring system is used to collect energy information released by blasting and record and store it; b. Energy calculation: The vibration velocity information v(t) is measured by the probe, and its energy density ε(r) is obtained. The vibration wave is regarded as a spherical wave, and the energy density is multiplied by the surface area S(R) of the sphere to obtain the vibration energy E. According to the energy attenuation F(r) = (2r) 2n e α(2r-1) , the vibration energy calculation formula is E = ε(r)·S(R)F(r).

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