Electromagnetic drive type heavy hammer excitation seismic source device and underground coal mine speed model calibration method

Abstract

The invention discloses an electromagnetic drive type heavy hammer excitation seismic source device and a coal mine underground speed model calibration method, and relates to the technical field of controllable seismic sources and mining geophysical exploration, and the electromagnetic drive type heavy hammer excitation seismic source device comprises an electromagnetic drive unit, a heavy hammer part, a pitch angle adjustment module, an energy control module and a signal acquisition module, according to the invention, the electromagnetic driving unit realizes non-contact acceleration of the heavy hammer through adjustable voltage, and the heavy hammer part generates high-energy pulse at the tail end; the energy control module regulates excitation energy based on closed-loop feedback, the signal acquisition module is used for monitoring excitation waveforms and executing energy self-calibration, and the calibration method comprises the following steps: picking up travel time data of multidirectional P waves and SV waves of an underground three-component accelerometer, solving vertical velocities Vp0 and Vs0 and anisotropy parameters epsilon and delta by adopting a ray tracing and inversion algorithm; a VTI speed model conforming to coal rock medium characteristics is established, the device and the method are cooperatively used, controllable excitation and model calibration can be achieved in the anti-explosion and damp-proof environment, and the construction precision of the underground speed model is improved.

Description

Technical Field

[0001] This invention relates to the field of controllable seismic source and mining geophysical exploration technology, specifically an electromagnetically driven hammer-excited seismic source device and a method for calibrating underground velocity models in coal mines. Background Technology

[0002] Microseismic events are minute vibrations caused by rock fracturing or fluid disturbance. Microseismic events triggered by coal and rock fracturing are often accompanied by large-scale mining activities, and as stress gradually accumulates, these microseismic events may evolve into stronger mine tremors, posing a significant threat to mine safety. Microseismic source location can provide spatial location information of coal and rock mass fracturing and potential hazards, and is an important technical means for monitoring and early warning of dynamic disasters in coal mines. Its location accuracy is mainly affected by the seismic wave propagation velocity model; the uncertainty of the velocity model is one of the key factors leading to location errors.

[0003] Currently, the construction of downhole velocity models faces limitations in both excitation devices and calibration methods. Regarding source excitation, existing calibration devices mostly employ traditional methods such as drop hammer, blasting, and geomagnetic drive. Traditional drop hammer sources produce low excitation energy and unstable waveforms, making repeatability difficult to guarantee; while blasting excitation offers higher energy, it poses safety hazards in high-gas mines, limiting its application; existing electromagnetically driven sources, although controllable, suffer from insufficient energy concentration and a limited excitation angle, restricting the establishment of high-resolution velocity models.

[0004] In terms of calibration methods, existing velocity models mostly assume that the medium is isotropic or only consider simple layered structures, which makes it difficult to reflect the anisotropic propagation characteristics of coal and rock masses in the bedding direction. This limits the accurate calibration of anisotropic velocity models and makes it difficult to support the needs of refined microseismic positioning.

[0005] In summary, existing technologies have limitations in terms of energy control and directionality of downhole seismic source excitation, as well as in the anisotropy description of velocity models. There is an urgent need for an energy-adjustable and angle-controllable electromagnetically driven seismic source device and a velocity model calibration method suitable for coal and rock VTI media to improve the accuracy of downhole microseismic positioning. Summary of the Invention

[0006] To address the shortcomings of related technologies, this invention employs an electromagnetically driven hammer-type excitation source device and a method for calibrating underground velocity models in coal mines. This device and method are non-destructive, reusable, have controllable excitation energy, adjustable excitation angle, and low safety risks. They can improve the accuracy of coal mine velocity models, expand the application scenarios of velocity models in microseismic monitoring, and provide reference and decision support for coal mine risk assessment. The device includes: an electromagnetic drive unit, a hammer component, a pitch angle adjustment module / cradle system, an energy control module, and a signal acquisition module.

[0007] The electromagnetic drive unit includes: a drive device cylinder, a coil assembly, a counterweight limiting component, and a fixing clamp. The coil is installed in the inner sleeve and arranged coaxially along the axis of the drive cylinder. The counterweight limiting component is a convex strip arranged axially along the inner side of the cylinder at 120° intervals. Fixing clamps are arranged at both ends of the drive device cylinder.

[0008] The counterweight component includes: an impact end cap, an armature, and a fixing latch. The impact end cap is located at the bottom of the counterweight component, the armature is located at the top of the counterweight component and connected to the impact end cap, and the fixing latch is located at the top of the counterweight structure.

[0009] The pitch angle adjustment module / cradle system includes: a four-legged support and a pitch angle adjustment gear set. The four-legged support has an annular groove for the rotating shaft in the middle section to fix the explosion-proof shell on the four-legged support. Ground nails are set at the top and bottom of the support and driven into the tunnel roof and floor respectively. The support legs at the top of the support are equipped with telescopic screws. The pitch angle adjustment gear set is coupled to the tooth arc on the explosion-proof shell. The pitch angle adjustment gear set is fixed on the four-legged support and is coupled to a handwheel through a worm gear.

[0010] The energy control module includes a power cabinet and a power control system. The power cabinet houses pulse capacitors, and the power control system includes power regulation circuits, feedback sensors, and control chips.

[0011] The signal acquisition module includes: a three-component accelerometer, a data acquisition card, a filtering and amplification circuit, and a GPS timing device. The three-component accelerometer is arranged underground as needed, and the GPS timing device is connected to the power cable and installed on the outside of the drive cylinder device.

[0012] An explosion-proof housing is installed outside the electromagnetic drive unit. A toothed arc is installed outside the explosion-proof housing and coupled to the gear set on the four-legged bracket. The electromagnetic drive unit can be suspended inside the explosion-proof housing by a fixing clamp. The counterweight component is suspended by a release device inside the explosion-proof housing. A force-bearing plate is installed at the bottom of the explosion-proof housing to withstand the impact of the counterweight component.

[0013] An electromagnetically driven hammer-induced vibration source device and a method for calibrating a velocity model in underground coal mines include the following steps:

[0014] S1: Deploy the electromagnetically driven excitation source device and three-component accelerometers. After adjusting the angle of the excitation source device, rotate the telescopic screw until the top load-bearing plate contacts the tunnel roof. Simultaneously measure the coordinates of the excitation source device and all three-component accelerometers.

[0015] S2: An external power supply charges the pulse capacitor inside the power cabinet. The control chip of the power control system controls the discharge of the pulse capacitor. The power regulation circuit adjusts the voltage applied to the coil according to the control chip's instructions, and monitors the changes in current and voltage on the coil in real time as the armature passes through through a feedback sensor. The dynamic adjustment of the capacitor discharge power achieves real-time control of the excitation energy. The armature receives electromagnetic force to drive the hammer component to impact the base plate, exciting a controllable high-energy pulse. The internal circuit of the GPS timing device sends a signal when the discharge of the last stage coil ends to obtain the excitation time of the excited source.

[0016] S3: Controllable excitation is performed according to different gradient combinations of set voltage level and tilt angle. The signal acquisition module records the excitation waveform, and the receiving array synchronously acquires multi-directional P-wave and SV-wave travel time data.

[0017] S4: Based on the travel time data under different gradient combinations, the theoretical travel time is calculated using the ray tracing algorithm, and the vertical velocities Vp0 and Vs0 and the anisotropic parameters ε and δ are obtained using the constrained inversion algorithm.

[0018] S5: By updating the model parameters through multiple rounds of iteration and integrating the inversion results under different gradient combinations, a VTI velocity model that conforms to the characteristics of coal and rock media is established.

[0019] S6: After completing the micro-vibration, reset the excitation source device, turn the handwheel to adjust the angle of the excitation source device to a downward angle, so that the fixing lock of the internal counterweight component slides into the inverted funnel slot of the unhooking device and locks it.

[0020] The present invention has the following advantages:

[0021] 1. This invention employs a composite electromagnetic drive device, combining electromagnetic acceleration and mechanical impact mechanisms to controllably accelerate a hammer in a non-contact state, with the excitation energy precisely regulated by an external voltage. Compared to traditional methods relying on the hammer's own weight or pyrotechnics for excitation, this structure achieves continuously adjustable excitation energy, stable pulse intensity, and non-destructive reusability, significantly improving the safety and reliability of the excitation system.

[0022] 2. The main body of this invention is composed of a mechanical structure and an electromagnetic system. The outer shell adopts an integrated explosion-proof and moisture-proof sealed design. Key circuit units and electromagnetic coil modules are encapsulated in a sealed cavity and equipped with moisture-wicking and insulating layers, enabling long-term stable operation in high humidity and high gas concentration environments. This structure achieves multiple protections against moisture, explosion, pollution, and electrical safety. The device can be repeatedly activated and is easy to maintain, significantly improving the reliability and safety of use in complex downhole environments.

[0023] 3. This invention achieves controllable adjustment of the excitation direction through a tilt angle orientation adjustment structure. The excitation angle can be flexibly adjusted according to the spatial geometry of the underground roadway, forming multi-directional, directional wavefield excitation. This design significantly improves the directional control accuracy of the excitation energy and the wavefield coverage, providing high-quality data support for the inversion of multi-directional anisotropic parameters.

[0024] 4. In the calibration process, this invention adopts a VTI velocity model divided by depth, which fully considers the influence of different depths and the non-uniformity of the medium between the source and the station on the stress wave propagation velocity. Combined with multi-directional excitation and constrained inversion algorithms, it can significantly improve the accuracy and stability of downhole velocity model calibration. Attached Figure Description

[0025] Figure 1 A schematic diagram of an electromagnetically driven hammer-excited vibration source device;

[0026] Figure 2 This is a disassembled diagram of an electromagnetically driven hammer-type vibration source device.

[0027] Figure 3 This is a schematic diagram of the electromagnetic drive unit in an electromagnetically driven hammer-excited vibration source device.

[0028] Figure 4 This is a schematic diagram of the hammer component in an electromagnetically driven hammer-excited vibration source device.

[0029] Figure 5 This is a schematic diagram of the explosion-proof casing in an electromagnetically driven hammer-excited vibration source device.

[0030] Figure 6 A cross-sectional view of the explosion-proof casing in an electromagnetically driven hammer-excited vibration source device.

[0031] Figure 7 This is a cross-sectional view of the explosion-proof shell cover plate in an electromagnetically driven hammer-excited vibration source device.

[0032] Figure 8 This is a schematic diagram of the four-legged support structure in an electromagnetically driven hammer-excited vibration source device.

[0033] Figure 9 This is a schematic diagram of the pitch angle adjustment gear set in an electromagnetically driven hammer-excited vibration source device.

[0034] Figure 10 This is a schematic diagram of a three-component accelerometer in an electromagnetically driven hammer-excited seismic source device.

[0035] Figure 11 This is a schematic diagram of the power supply cabinet in an electromagnetically driven hammer-excited vibration source device.

[0036] In the diagram: 1. Electromagnetic drive unit; 2. Counterweight component; 3. Explosion-proof housing; 4. Four-legged bracket; 5. Pitch angle adjustment gear set; 6. Energy control module; 7. Signal acquisition module; 8. Fixing clamp; 9. Limiting component; 10. Drive device power cable channel; 11. GPS timing device; 12. Drive cylinder device; 13. Power cable; 14. Heat sink; 15. Coil group sleeve; 16. Coil group coil; 17. Fixing latch; 18. Armature; 19. Impact end cap; 20. Explosion-proof housing cover plate; 21. Unhooking device; 22. Explosion-proof housing cover, power cable channel; 23. Inverted funnel-shaped slot for release device; 24. Locking tongue of release device; 25. Explosion-proof housing sealing ring; 26. Explosion-proof housing cylinder; 27. Bottom load-bearing plate; 28. Gear arc; 29. ​​Shoulder; 30. Shaft head; 31. Support leg; 32. Ground spike; 33. Telescopic screw; 34. Shaft collar; 35. Frame; 36. Speed ​​change gear; 37. Worm gear; 38. Handwheel; 39. Buffer washer; 40. Three-component accelerometer; 41. Power cabinet; 42. Pulse capacitor; 43. Power control system. Detailed Implementation

[0037] The preferred embodiments of the present invention will be described below with reference to the accompanying drawings. It should be understood that the preferred embodiments described herein are for illustration and explanation only and are not intended to limit the present invention.

[0038] It should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the system or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the present invention.

[0039] Example 1, please refer to Figures 1-11 An electromagnetically driven hammer-excited vibration source device includes an electromagnetic drive unit 1, a hammer component 2, an explosion-proof shell 3, a four-legged bracket 4, a pitch angle adjustment gear set 5, an energy control module 6, and a signal acquisition module 7.

[0040] The explosion-proof cover plate 20 and the explosion-proof shell cylinder 26 are fixed by bolts. A buffer washer 39 is provided between the explosion-proof cover plate 20, the electromagnetic drive unit 1 and the explosion-proof shell cylinder 26 to protect the electromagnetic drive unit 1 from the high pulse energy generated by the excitation source while fixing it.

[0041] The electromagnetic drive unit 1 includes: a fixing clamp 8, a limiting component 9, a power cable channel 10 for the drive device, a GPS timing device 11, a drive cylinder device 12, a coil assembly sleeve 15, and a coil assembly coil 16. The coil assembly coil 16 is fixed by the sleeve 15 and is coaxially arranged on the drive cylinder device 12. A heat sink 14 is fitted over the coil assembly sleeve 15 to dissipate heat from the coil assembly. The drive cylinder device 12 has fixing clamps 8 at both ends. The upper clamp has a power cable channel 10. The power cable 13 passes through the channel 10 and connects to the coil assembly coil 16. The power cable 13 is also connected to the GPS timing device 11 to collect information when micro-vibration is excited. The limiting component 9 is arranged at a 120° angle inside the drive device cylinder. When the device is started, the power control system 43 controls the pulse capacitor 42 to discharge, which in turn generates a changing magnetic field on the coil 16 of the electromagnetic drive unit 1, causing an induced current and a corresponding induced magnetic field to be generated on the armature 18. Under the mutual repulsion of the magnetic fields between the coil 16 and the armature 18, a repulsive force is generated as the driving force of the hammer component 2.

[0042] The counterweight component 2 includes: a fixing latch 17, an armature 18, and an impact end cap 19. The lower end of the armature 18 is connected to the impact end cap 19, and the upper end is connected to the fixing latch 17. The overall diameter is the same as the inner diameter of the limiting component 9 in the drive cylinder device 12, which restricts the counterweight device from moving axially within the drive cylinder device 12.

[0043] The explosion-proof housing 3 includes: an explosion-proof housing cover plate 20, a release device 21, a power cable channel 22 for the explosion-proof housing cover plate, an explosion-proof housing sealing ring 25, an explosion-proof housing cylinder 26, a bottom load-bearing plate 27, a toothed arc 28, a shoulder 29, and a shaft head 30. The top of the explosion-proof housing 3 is sealed by the explosion-proof housing cover plate 20, on which the release device 21 and the power cable channel 22 are provided. The main body of the explosion-proof housing 3 is the explosion-proof housing cylinder 26. The top of the cylinder 26 is provided with an explosion-proof housing sealing ring 25 coupled to the explosion-proof housing cover plate 20 to ensure the airtightness of the explosion-proof housing 3. The bottom of the explosion-proof housing cylinder is a load-bearing plate 27 to bear the impact force of the counterweight assembly 2. The shoulders 29 and shaft heads 30 of the rotating shaft are installed on both sides of the bottom load-bearing plate 27, which can be coupled with the rotating shaft collar 34 on the four-legged bracket 4 to give the electromagnetic drive unit 1 and the explosion-proof housing 2 a degree of freedom in the vertical plane. The bottom force plate 27 has a toothed arc 28 at its lower end, which can be coupled with the pitch angle adjustment gear set 5 to achieve precise control of the working face angle.

[0044] The unhooking device 21 includes: an inverted funnel-shaped slot 23 and a locking tongue 24. The bottom structure of the unhooking device 21 is an inverted funnel-shaped slot 23, with a circular cross-section at the funnel opening, a narrowing cross-section at the funnel tube, and an elliptical cross-section with semicircles on both sides at the neck of the funnel. The locking tongue 24 is installed inside the funnel. A mechanical component inside the unhooking device 21 pushes the locking tongue 24 out to hang the weight component 2. Before activating the excitation source device, the unhooking device 21 is controlled to retract the locking tongue 24 via the internal mechanical component to release the weight component 2. When the excitation source device is reset, the handwheel 38 of the pitch angle adjustment gear set 5 is rotated to turn the electromagnetic drive unit to a negative angle. Under the action of the limiting component, the weight component 2 slides along the axial direction of the drive device cylinder towards the unhooking device 21 by gravity. The retaining latch 17 of the counterweight assembly 2 has an inverted U-shape. When sliding towards the release device 21, the retaining latch 17 first enters the inverted funnel-shaped slot 23 of the release device. The retaining latch 17 can enter the funnel opening at any angle. As it slides downward, the retaining latch 17 automatically corrects its angle under pressure as the cross-section of the funnel changes, causing the long axis of the retaining latch 17 to reconnect with the long axis of the funnel neck. At this time, the locking tongue 24 of the release device can pass through the retaining latch 17 to hang the counterweight assembly 2.

[0045] The four-legged support 4 includes: legs 31, ground spikes 32, telescopic screws 33, collars 34, and brackets 35. The main body of the support consists of four vertical legs 31. Each leg 31 has a ground spike 32 at both the top and bottom ends, which can be driven into the tunnel roof and floor to fix the excitation source device. A collar 34 with a rotating shaft is installed in the middle of the four-legged support 4 to accommodate the rotating shaft head 30 at the bottom of the explosion-proof shell 3. Multiple brackets 35 between the legs 31 serve as structural connecting components of the four-legged support 4 and fixing components of the pitch angle adjustment gear set 5.

[0046] The pitch angle adjustment gear set 5 includes: a transmission gear 36, a worm gear 37, and a handwheel 38. The handwheel 38 is coaxially connected to the worm gear 37, and the worm gear 37 is coupled to the transmission gear 36. The torque provided by rotating the handwheel 38 can be transmitted to the transmission gear 36 through the worm gear 37. The transmission gear 36 is coupled to the tooth arc 28 at the bottom of the explosion-proof housing 3. The torque is amplified by the transmission gear 36 and acts on the tooth arc 28 to drive the electromagnetic drive device 1 to adjust the working surface angle.

[0047] The energy control module 6 includes: a power supply cabinet 41, a pulse capacitor 42, and a power control system 43. The pulse capacitor 42 and the power control system 43 are housed inside the power supply cabinet 41.

[0048] The signal acquisition module 7 array consists of multiple three-component accelerometers 40, used to record the arrival time of P waves. Based on the depth and horizontal range defined by the established velocity model, the three-component accelerometers 40 are deployed at different depths and distances from the excitation source device.

[0049] An electromagnetically driven hammer-induced vibration source device and a method for calibrating a velocity model in underground coal mines include the following steps:

[0050] S1: Deploy the electromagnetically driven excitation source device and the three-component accelerometer 40. Drill at the deployment location of the excitation source device. First, insert the bottom ground nail 32 into the reserved drilling position, and rotate the telescopic screw 33 until the top ground nail 32 contacts the tunnel roof. Simultaneously measure the coordinates of the excitation source device and all three-component accelerometers 40.

[0051] S2: The pulse capacitor 42 inside the power cabinet 41 is charged by an external power supply. The control chip of the power control system 43 controls the discharge of the pulse capacitor 42. The power adjustment circuit adjusts the voltage applied to the coil 16 according to the instructions of the control chip, and monitors the changes in current and voltage on the coil 16 in real time when the armature passes through through the feedback sensor. The discharge power of the capacitor 42 is dynamically adjusted to achieve real-time control of the excitation energy. The armature 18 receives electromagnetic force to drive the hammer component 2 to impact the bottom force plate 27 and generate a controllable high-energy pulse. The internal circuit of the GPS timing device 9 sends a signal when the discharge of the last stage coil 16 ends to obtain the excitation time of the excitation source.

[0052] S3: Controllable excitation is performed according to different gradient combinations of set voltage level, azimuth angle and tilt angle. The signal acquisition module records the excitation waveform, and the receiving array synchronously acquires multi-azimuth P-wave and SV-wave travel time data.

[0053] S4: Based on the travel time data under different gradient combinations, the theoretical travel time is calculated using the ray tracing algorithm, and the vertical velocities Vp0 and Vs0 and the anisotropic parameters ε and δ are obtained using the constrained inversion algorithm.

[0054] S5: By updating the model parameters through multiple rounds of iteration and integrating the inversion results under different gradient combinations, a VTI velocity model that conforms to the characteristics of coal and rock media is established.

[0055] S6: After completing the micro-vibration excitation, rotate the handwheel 38 to adjust the pitch angle of the electromagnetic drive unit 1 to a negative angle, so that the fixing latch 17 of the internal counterweight component 2 enters the inverted funnel slot 23 of the unhooking device and locks, thus completing the reset of the excitation source device.

[0056] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. An electromagnetically driven hammer-type vibration source device, characterized in that, include: The system comprises an electromagnetic drive unit, a counterweight component, a pitch angle adjustment module / cradle system, an energy control module, and a signal acquisition module. The electromagnetic drive unit includes a drive cylinder and a coil assembly. The coil assembly is coaxially arranged along the cylinder axis and controls the electromagnetic field strength by adjusting the voltage to achieve non-contact acceleration of the counterweight. The counterweight component is located within the drive cylinder of the electromagnetic drive unit and is used to generate a high-energy pulse by impacting the load-bearing plate after acceleration. The pitch angle adjustment module / cradle system includes a four-legged support and a pitch angle adjustment gear set. The four-legged support provides vertical freedom for the excitation source device and transmits P-wave energy. The pitch angle adjustment gear set can precisely adjust the working angle of the excitation source device, achieving precise control of its operating mode. The energy control module is electrically connected to the electromagnetic drive unit and is used to regulate the excitation energy in real time based on closed-loop feedback signals. The signal acquisition module is connected to the counterweight component and is used to monitor the excitation waveform and perform energy self-calibration.

2. The electromagnetically driven hammer-excited vibration source device according to claim 1, characterized in that, The energy control module includes a power regulation circuit, a feedback sensor, and a control chip. The feedback sensor monitors the changes in coil current and voltage in real time, and the control chip outputs pulse control signals according to the set energy level.

3. The electromagnetically driven hammer-excited vibration source device according to claim 1, characterized in that, The hammer component includes an impact end cap, an armature, and a fixing latch. Under the action of the armature, the hammer can be controlled to accelerate under non-contact conditions to obtain high-energy pulses of different gradient levels.

4. The electromagnetically driven hammer-excited vibration source device according to claim 1, characterized in that, The signal acquisition module includes a three-component accelerometer, a data acquisition card, and a filtering and amplification circuit, which are used to acquire the excitation waveform and perform spectrum analysis and amplitude calibration.

5. The electromagnetically driven hammer-excited vibration source device according to any one of claims 1-4, characterized in that, It includes an explosion-proof housing, which is fixed to the pitch angle adjustment module / cradle system via a rotating shaft. The explosion-proof housing is equipped with a toothed arc and a gear set for coupling, which is used to adjust and lock the excitation angle.

6. The method for calibrating the underground velocity model in a coal mine using the apparatus according to any one of claims 1-5, characterized in that, Includes the following steps: S1: Install a three-component accelerometer downhole and install the composite electromagnetic drive type hammer excitation source device. S2: Set different gradient voltage levels, azimuth angle and tilt angle combinations to perform spatially controllable excitation. The signal acquisition module records the excitation waveform, and the receiving array synchronously acquires multi-azimuth P-wave and SV-wave travel time data. S3: Based on the travel time data under multiple combinations of conditions, the theoretical travel time is calculated using the ray tracing algorithm, and the vertical velocities Vp0 and Vs0 and the anisotropy parameters ε and δ are obtained using the constraint inversion algorithm. S4: By updating the model parameters through multiple rounds of iteration, a VTI velocity model that conforms to the characteristics of coal and rock media is established.

7. The method for calibrating a coal mine underground velocity model according to claim 6, characterized in that: The theoretical P-wave travel time between the source and receiver is determined by the following formula: ； In the formula, x i y i z i Let x0, y0, z0 be the coordinates of the i-th detector, and v be the coordinates of the seismic source. i Let T be the propagation speed of the P-wave in the medium. i When the P-wave arrives at the i-th detector, T0 is the time of the earthquake source's origin.

8. The method for calibrating a coal mine underground velocity model according to claim 7, characterized in that: The goodness of fit of the model is evaluated using the root mean square error (RMSE), and the calculation formula is as follows: ； In the formula, rtt modi To calculate travel time, RTT obsi For the observation time, N is the number of samples.

9. The method for calibrating a coal mine underground velocity model according to claim 8, characterized in that: In the VTI model, the anisotropic P-wave velocity satisfies the following relationship: ； In the formula, V P0 Let ε be the vertical P-wave velocity, ε and δ be the anisotropy parameters, and θ be the propagation angle.

10. The method for calibrating a coal mine underground velocity model according to any one of claims 6 to 9, characterized in that: The device and method, when used in synergy, can achieve controlled excitation and synchronous calibration of anisotropic velocity models in explosion-proof and moisture-proof environments, significantly improving the accuracy and stability of underground velocity model construction in coal mines.

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