System and method for measuring speed of blasting flying rocks in tunnel

Abstract

The invention discloses a system and a method for measuring the speed of blasting flying rocks in a tunnel, and belongs to the field of blasting flying rock speed measurement. The invention discloses a system for measuring the speed of blasting flying rocks in a tunnel. The system comprises two laser transmitters, two photoelectric sensors, a timer and a data processing unit, the two laser emitters emit two focused laser beams which are parallel to each other, the two focused laser beams are respectively received by the two photoelectric sensors and can detect passing of flying stones, the timer is electrically connected with the two photoelectric sensors, when the first laser beam is interrupted, timing is started, and when the second laser beam is interrupted, timing is stopped; recording the flying stone crossing time; therefore, accurate measurement of the tunnel blasting flying stone speed is achieved, and when the flying stone speed is calculated, correction time delta tcoor is introduced according to the influence of air resistance, temperature, blasting vibration sound waves and the initial flying stone speed, so that it is ensured that speed measurement is more accurate under the tunnel environment condition.

Description

Technical Field

[0001] The invention belongs to the field of blasting flying rock velocity measurement, and in particular relates to a blasting flying rock velocity measurement system in a tunnel and a measurement method thereof. Background Art

[0002] The measurement of flying rock velocity during tunnel blasting is a key link in tunnel construction. During tunnel blasting construction, due to different blasting scales, methods and environments, the vibration, air shock wave, flying rocks, noise and toxic gases caused by blasting will have different degrees and ranges of impact on surrounding buildings, facilities and personnel; among them, the harm of flying rocks is particularly significant, because it may not only cause casualties, but also cause equipment damage and construction delays. In addition, the measurement data of flying rock velocity can be fed back to the blasting design. By measuring the flying rock velocity, the energy during blasting can be indirectly fed back to help engineers optimize blasting parameters such as explosive quantity, drilling depth and spacing, so as to reduce the generation and harm of flying rocks; therefore, it is of great significance to accurately measure the flying rock velocity during tunnel blasting. For this purpose, a system and method for measuring flying rock velocity during blasting in tunnels are proposed. Summary of the invention

[0003] In view of the deficiencies in the prior art, the purpose of the present invention is to provide a system and method for measuring the velocity of flying rocks during blasting in a tunnel, thereby solving the problems in the prior art.

[0004] The purpose of the present invention can be achieved through the following technical solutions:

[0005] A system for measuring the speed of flying rocks during blasting in a tunnel comprises two laser emitters, two photoelectric sensors, a timer and a data processing unit; the two laser emitters emit two parallel focused laser beams, which are respectively received by two photoelectric sensors and can detect the passage of flying rocks; the timer is electrically connected to the two photoelectric sensors, and starts timing when the first laser beam is interrupted, and stops timing when the second laser beam is interrupted, and records the time when the flying rocks pass through; the data processing unit is electrically connected to the timer to calculate the speed of flying rocks;

[0006] A pair of parallel limit baffles are arranged on one side of the two laser emitters. The two limit baffles are provided with coaxially arranged clearance holes. The axial direction of the clearance holes is perpendicular to the direction of the laser beams, and the axis of the position hole is located in the plane where the two laser beams are located.

[0007] The projection of the limit baffle along the axis direction of the clearance hole completely covers the two laser emitters and the two photoelectric sensors.

[0008] A flow guide is fixed on the limit baffle away from the laser emitter. The flow guide is fixed on a side surface of the limit baffle away from the laser emitter. The side surface of the flow guide away from the limit baffle is in an arc convex shape. A circular through hole is opened on the flow guide. The circular through hole and the give-way hole are coaxially arranged and have equal diameters. The projection of the flow guide along the axial direction of the circular through hole completely covers the limit baffle.

[0009] A pair of symmetrically placed shading plates are fixed on the limit baffle plate close to the laser emitter side. The plate surfaces of the shading plates are parallel to the planes where the two laser beams are located, and the two laser beams are located between the two shading plates.

[0010] A method for measuring the speed of flying rocks during blasting in a tunnel, using the above-mentioned system for measuring the speed of flying rocks during blasting in a tunnel, comprises the following steps:

[0011] S1, install the laser transmitter and photoelectric sensor on both sides of the tunnel respectively, adjust the height of the laser transmitter, and adjust the receiving window of the photoelectric sensor to align with the emission port of the laser transmitter; and align the clearance holes of the two limit baffles so that the axial direction of the clearance hole is perpendicular to the direction of the laser beam;

[0012] S2, start the timer and prepare for equipment testing before blasting;

[0013] S3, blasting, observing the flying stones passing through the laser beam; the laser transmitter emits a laser beam, and when the first laser beam is interrupted, the timing starts, and when the second laser beam is interrupted, the timing stops, and the time difference between the moment when the first laser beam is interrupted by the flying stone and the moment when the second laser beam is interrupted by the flying stone is obtained;

[0014] S4, the data processing unit receives the time data, calculates the flying stone speed, and displays the result.

[0015] Furthermore, equipment testing prior to blasting includes:

[0016] 1) Equipment alignment test: ensure that the emission port of the laser transmitter is accurately aligned with the receiving window of the photoelectric sensor;

[0017] 2) Laser beam inspection: Use a laser power meter to confirm the intensity and stability of the laser beam;

[0018] 3) Photoelectric sensor sensitivity test: Use a digital multimeter to check the photoelectric sensor and test the output signal of the photoelectric sensor;

[0019] 4) Timer function test: simulate laser beam interruption to check whether the timer can accurately record the time and ensure that its display is normal;

[0020] 5) Data processing unit calibration: Use the simulation software LabVIEW to simulate the input signal and test the real-time data processing capability of the data processing unit.

[0021] The calculation formula of flying stone velocity v is:

[0022]

[0023] Where v is the flying stone velocity, d is the distance between the two laser beams, Δt is the time difference between the moment when the first laser beam is interrupted by the flying stone and the moment when the second laser beam is interrupted by the flying stone, Δt coor It is correction time.

[0024] Furthermore, the correction time Δt coor The calculation formula is:

[0025] Δt corr =k 1 ×Δt air +k 2 ×Δt temp +k 3 ×Δ tvibration +k 4 ×Δt initial

[0026] In the formula, Δt air is the air resistance correction time; Δt temp is the temperature correction time; Δt vibration Δt is the correction time of the vibration sound wave initial Initial velocity correction time; k 1 , k 2 , k 3 and k 4 is the weight coefficient of each type of correction time.

[0027] Furthermore, k 1 , k 2 , k 3 and k 4 The sum is 1.

[0028] A system for measuring the speed of flying rocks during blasting in a tunnel, comprising:

[0029] Device installation module: install the laser transmitter and photoelectric sensor on both sides of the tunnel respectively, adjust the height of the laser transmitter to prevent dust in the tunnel from interfering with the laser beam, and align the receiving window of the photoelectric sensor with the emission port of the laser transmitter; align the clearance holes of the two limit baffles so that the axial direction of the clearance holes is perpendicular to the direction of the laser beam; reduce the calculation error caused by the oblique incidence of flying rocks;

[0030] Device test module: Start the timer and prepare for equipment testing before blasting;

[0031] Timing module: perform blasting and observe the flying stones passing through the laser beam; the laser transmitter emits a laser beam, and the timing starts when the first laser beam is interrupted, and stops when the second laser beam is interrupted, and the time difference between the moment when the first laser beam is interrupted by the flying stone and the moment when the second laser beam is interrupted by the flying stone is obtained;

[0032] And, the flying stone speed calculation module: the data processing unit receives the time data and calculates the flying stone speed v.

[0033] Beneficial effects of the present invention:

[0034] 1. The present invention sets two laser transmitters to emit two highly focused laser beams, which are received by the photoelectric sensor, so as to detect the passage of flying rocks, and use a timer to record the time of the flying rocks passing through, and then use a data processing unit to calculate the flying rock speed, thereby realizing the accurate measurement of the flying rock speed of tunnel blasting.

[0035] 2. When calculating the flying stone velocity, the correction time Δt is introduced to account for the influence of air resistance, temperature, blasting vibration sound waves and the initial velocity of the flying stone. coor To ensure more accurate speed measurement in tunnel environment conditions;

[0036] 3. In this application, "two laser transmitters, two photoelectric sensors, a timer, a pair of limit baffles, a guide piece, and a pair of shading plates" are used as a measurement group. Multiple measurement groups can be set in the tunnel. Multiple measurement groups share the same data processing unit to ensure that the guide pieces in each measurement group are located on the side close to the blasting end of the tunnel. Multiple measurement groups can be set at different heights and depths in the three-dimensional space of the tunnel. The axial direction of the clearance hole in each measurement group can be placed differently according to needs. Multiple measurement groups with different axial directions of the clearance holes can respectively measure the speed of various flying rocks with different splashing directions;

[0037] By setting up multiple measurement groups, a laser network can be formed in the tunnel to increase the probability of flying stones entering the makeshift hole for speed measurement during blasting, while increasing the number of flying stones that effectively pass through the measurement group. By measuring the speed of multiple flying stones at different positions and directions, and finally averaging the speeds measured for each flying stone, the accuracy of reflecting the blasting energy by measuring the flying stone speed during blasting can be improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0039] Figure 1 It is a schematic diagram of the overall structure of the present invention;

[0040] Figure 2 It is a schematic diagram of the overall structure of the present invention from different viewing angles;

[0041] Figure 3 It is a partial structural schematic diagram of the flow guide of the present invention;

[0042] Figure 4 It is a partial structural schematic diagram of the laser transmitter of the present invention;

[0043] Figure 5 It is a structural block diagram of the flying stone measurement system of the present invention;

[0044] Figure 6 It is the flying stone measurement principle diagram of the present invention. DETAILED DESCRIPTION

[0045] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0046] Example 1

[0047] like Figure 1 As shown, a system for measuring the speed of flying rocks during blasting in a tunnel comprises two laser emitters 100, two photoelectric sensors 200, a timer and a data processing unit; the two laser emitters 100 emit two parallel focused laser beams, which are respectively received by the two photoelectric sensors 200, and can detect the passing of flying rocks; the timer is electrically connected to the two photoelectric sensors 200, and starts timing when the first laser beam is interrupted, and stops timing when the second laser beam is interrupted, and records the time when the flying rocks pass through; the data processing unit is electrically connected to the timer to calculate the speed of flying rocks;

[0048] A pair of parallel limit baffles 300 are provided on one side of the two laser emitters 100, and coaxially arranged clearance holes 301 are opened on the two limit baffles 300. The axial direction of the clearance hole 301 is perpendicular to the direction of the laser beam, and the axis of the position hole is located in the plane where the two laser beams are located; it is ensured that only vertically incident (or nearly vertically incident) flying stones can pass through the two clearance holes 301 and pass through two beams of light at the same time, reducing the calculation error caused by the oblique incidence of flying stones, so as to ensure the test accuracy of the flying stone speed.

[0049] The projection of the limit baffle 300 along the axial direction of the clearance hole 301 completely covers the two laser emitters 100 and the two photoelectric sensors 200; the limit baffle 300 provides certain protection for the laser emitters 100 and the two photoelectric sensors 200.

[0050] A guide piece 400 is fixed on the limit baffle 300 away from the laser emitter 100. The guide piece 400 is fixed on a side surface of the limit baffle 300 away from the laser emitter 100. The side surface of the guide piece 400 away from the limit baffle 300 is in an arc convex shape. A round through hole 401 is opened on the guide piece 400. The round through hole 401 and the yield hole 301 are coaxially arranged and have equal diameters. The projection of the guide piece 400 along the axial direction of the round through hole 401 completely covers the limit baffle 300. Before blasting, the arc convex surface of the guide piece 400 is directed toward the blasting end of the tunnel. Through the setting of the guide piece 400, the strength of the limit baffle 300 close to the blasting end is improved. At the same time, the arc convex surface on the guide piece 400 can guide, disperse and buffer the impact generated during blasting, thereby reducing the damage of the blasting impact to the flying rock velocity measurement system.

[0051] A pair of symmetrically placed shading plates 500 are fixed on the limit baffle 300 close to the laser emitter 100. The surface of the shading plates 500 is parallel to the plane where the two laser beams are located, and the two laser beams are located between the two shading plates 500. The setting of the shading plates 500 can prevent flying stones that have not passed through the clearance holes 301 from accidentally interrupting the laser beams, thereby improving the accuracy of speed measurement.

[0052] Preferably, in the present application, "two laser emitters 100, two photoelectric sensors 200, a timer, a pair of limit baffles 300, a guide member 400, and a pair of shading plates 500" are used as a measurement group. Multiple measurement groups can be set in the tunnel, and the multiple measurement groups share the same data processing unit to ensure that the guide member 400 in each measurement group is located on the side close to the blasting end of the tunnel. The multiple measurement groups can be set at different heights and depths in the three-dimensional space of the tunnel. The axial direction of the clearance hole 301 in each measurement group can be placed differently according to needs. Multiple measurement groups with different axial directions of the clearance hole 301 can respectively measure the speed of various flying rocks with different splashing directions;

[0053] By setting up multiple measurement groups, a laser network can be formed in the tunnel to increase the probability of flying stones entering the make way hole 301 for speed measurement during blasting, while increasing the number of flying stones that effectively pass through the measurement group. By measuring the speed of multiple flying stones at different positions and directions, the speed of each flying stone is finally averaged, thereby improving the accuracy of reflecting the blasting energy by measuring the speed of the blasting flying stones.

[0054] The laser emitter 100 and the photoelectric sensor 200 are installed on both sides of the tunnel, and the emission port of the laser emitter 100 is aligned with the receiving window of the photoelectric sensor 200 to ensure that the laser beam can directly pass through the measurement area and be effectively received by the photoelectric sensor 200. This alignment ensures that the laser beam can be accurately interrupted when flying rocks pass through, thereby achieving accurate speed measurement.

[0055] Preferably, in this embodiment, the laser emitter 100 selects Coherent 100-1000 series lasers; the photoelectric sensor 200 selects Keyence PZ-G series photoelectric sensor 200, which is suitable for high-speed detection; the timer selects NationalInstruments NI 9401, which has high timing accuracy and can quickly record signal changes; the data processing unit selects RaspberryPi 4, which has powerful processing capabilities, can process data and display results in real time.

[0056] Preferably, in this embodiment, the laser emitter 100 and the photoelectric sensor 200 are fixed to the tunnel side wall by a shockproof bracket to reduce the impact of blasting vibration on the laser emitter 100 and the photoelectric sensor 200 and improve the accuracy of flying rock velocity measurement.

[0057] Example 2

[0058] In this embodiment, a method for measuring the blasting flying rock velocity in a tunnel using the measuring device in Embodiment 1 is proposed, comprising the following steps:

[0059] S1, install the laser emitter 100 and the photoelectric sensor 200 on both sides of the tunnel respectively, adjust the height of the laser emitter 100 to prevent dust in the tunnel from interfering with the laser beam, and adjust the receiving window of the photoelectric sensor 200 to align with the emission port of the laser emitter 100; and align the clearance holes 301 of the two limit baffles 300, so that the axial direction of the clearance hole 301 is perpendicular to the direction of the laser beam to ensure that the flying stones are incident vertically;

[0060] S2, start the timer and prepare for equipment testing before blasting;

[0061] Equipment testing items before blasting include:

[0062] 1) Equipment alignment test: Ensure that the emission port of the laser emitter 100 is accurately aligned with the receiving window of the photoelectric sensor 200, and adjust the position to avoid any deviation.

[0063] 2) Laser beam inspection: Use measurement tools (such as laser power meters) to confirm the intensity and stability of the laser beam to ensure that it can be clearly seen in the tunnel environment.

[0064] 3) Photoelectric sensor 200 sensitivity test: Use a digital multimeter to check the photoelectric sensor 200 to test the output signal of the photoelectric sensor 200 to ensure that its sensitivity and response time are normal, thereby ensuring that the laser beam interruption can be quickly detected.

[0065] 4) Timer function test: simulate laser beam interruption (such as using an object to block the laser beam), check whether the timer can accurately record the time, and ensure that its display is normal.

[0066] 5) Data processing unit calibration: Use the simulation software LabVIEW to simulate the input signal and test the real-time data processing capability of the data processing unit to ensure that the data processing unit can correctly receive the timer data and process and display the speed calculation results in real time.

[0067] S3, blasting is performed, and flying stones are observed to pass through the laser beam; the laser emitter 100 emits a laser beam, and timing starts when the first laser beam is interrupted, and timing stops when the second laser beam is interrupted, and the time difference Δt between the moment when the first laser beam is interrupted by the flying stone and the moment when the second laser beam is interrupted by the flying stone is obtained;

[0068] S4, the data processing unit receives the time data, calculates the flying stone velocity v, and displays the result.

[0069] The calculation formula of flying stone velocity v is:

[0070]

[0071] Where v is the flying stone velocity, d is the distance between the two laser beams (the two laser beams are parallel), Δt is the time difference between the moment when the first laser beam is interrupted by the flying stone and the moment when the second laser beam is interrupted by the flying stone, Δt coor It is the correction time, taking into account various influencing factors in the tunnel to ensure more accurate speed measurement under tunnel environmental conditions.

[0072] Among them, Δt coor The calculation formula is:

[0073] Δt corr =k 1 ×Δt air +k 2 ×Δttemp +k 3 ×Δ tvibration +k 4 ×Δt initial

[0074] In the formula, Δt air The air resistance correction time is affected by the shape and volume of the flying rocks and the air velocity in the tunnel. It can be estimated through experiments or CFD simulations and quantified as a certain time correction; Δt temp is the temperature correction time. The temperature change in the tunnel will affect the air density, thus affecting the movement of flying rocks. The corresponding correction time can be calculated through the relationship model between temperature and air density; Δt vibration Correction time for vibration sound waves. The vibration generated by blasting may affect the sensor response time, which can be quantified by monitoring and analyzing the characteristics of the vibration; Δt initial Initial velocity correction time: if the flying stone has an initial velocity, it needs to be corrected and quantified by initial velocity measurement or estimation; k 1 , k 2 , k 3 and k 4 , is the weight coefficient of each type of correction time, representing the degree of influence of each influencing factor. Through multiple experiments to measure the flying stone speed under different conditions, the actual influence of each factor is recorded, and statistical analysis methods (such as linear regression, variance analysis, etc.) are used to calculate the corresponding weight coefficient; and k 1 , k 2 , k 3 and k 4 The sum is 1.

[0075] Example 3

[0076] In this embodiment, based on the measurement method in Embodiment 2, a system for measuring the speed of flying rocks during blasting in a tunnel is proposed, comprising:

[0077] Device installation module: install the laser emitter 100 and the photoelectric sensor 200 on both sides of the tunnel respectively, adjust the height of the laser emitter 100 to prevent dust in the tunnel from interfering with the laser beam, and adjust the receiving window of the photoelectric sensor 200 to align with the emission port of the laser emitter 100; and align the clearance holes 301 of the two limit baffles 300 so that the axial direction of the clearance hole 301 is perpendicular to the direction of the laser beam;

[0078] Device test module: Start the timer and prepare for equipment testing before blasting;

[0079] Timing module: blasting is performed and flying stones are observed passing through the laser beam; the laser emitter 100 emits a laser beam, and timing starts when the first laser beam is interrupted, and timing stops when the second laser beam is interrupted, and the time difference Δt between the moment when the first laser beam is interrupted by the flying stone and the moment when the second laser beam is interrupted by the flying stone is obtained;

[0080] And, the flying stone speed calculation module: the data processing unit receives the time data and calculates the flying stone speed v.

[0081] In the description of this specification, the description with reference to the terms "one embodiment", "example", "specific example", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0082] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments, and the above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, and these changes and improvements all fall within the scope of the present invention to be protected.

Claims

1. A system for measuring the speed of flying rocks during blasting in a tunnel, characterized in that: The invention comprises two laser emitters (100), two photoelectric sensors (200), a timer and a data processing unit; the two laser emitters (100) emit two parallel focused laser beams, which are respectively received by the two photoelectric sensors (200) and can detect the passing of flying stones; the timer is electrically connected to the two photoelectric sensors (200); when the first laser beam is interrupted, the timing starts; when the second laser beam is interrupted, the timing stops, and the time of the flying stone passing is recorded; the data processing unit is electrically connected to the timer to calculate the speed of the flying stone; A pair of parallel limit baffles (300) are provided on one side of the two laser emitters (100), and coaxially arranged clearance holes (301) are provided on the two limit baffles (300). The axial direction of the clearance holes (301) is perpendicular to the direction of the laser beams, and the axis of the clearance holes is located in the plane where the two laser beams are located.

2. A system for measuring the speed of flying rocks during blasting in a tunnel according to claim 1, characterized in that: The projection of the limiting baffle (300) along the axial direction of the clearance hole (301) completely covers the two laser emitters (100) and the two photoelectric sensors (200).

3. A system for measuring the speed of flying rocks during blasting in a tunnel according to claim 2, characterized in that: A flow guide (400) is fixed on a limit baffle (300) away from the laser emitter (100). The flow guide (400) is fixed on a side surface of the limit baffle (300) away from the laser emitter (100). The side surface of the flow guide (400) away from the limit baffle (300) is in the shape of an arc convex surface. A round through hole (401) is provided on the flow guide (400). The round through hole (401) and the clearance hole (301) are coaxially arranged and have the same diameter. The projection of the flow guide (400) along the axial direction of the round through hole (401) completely covers the limit baffle (300).

4. A system for measuring the speed of flying rocks during blasting in a tunnel according to claim 3, characterized in that: A pair of symmetrically placed shading plates (500) are fixed on the limit baffle (300) near the laser emitter (100), the plate surfaces of the shading plates (500) are placed parallel to the plane where the two laser beams are located, and the two laser beams are located between the two shading plates (500).

5. A method for measuring the speed of flying rocks during blasting in a tunnel, using a system for measuring the speed of flying rocks during blasting in a tunnel according to any one of claims 1 to 4, characterized in that: The following steps are involved: S1, installing the laser emitter (100) and the photoelectric sensor (200) on both sides of the tunnel respectively, adjusting the height of the laser emitter (100), and adjusting the receiving window of the photoelectric sensor (200) to align with the emission port of the laser emitter (100); and aligning the clearance holes (301) of the two limit baffles (300) so that the axial direction of the clearance holes (301) is perpendicular to the direction of the laser beam; S2, start the timer and prepare for equipment testing before blasting; S3, blasting is performed, and flying rocks are observed to pass through the laser beam; the laser emitter (100) emits laser beams, and timing is started when the first laser beam is interrupted, and timing is stopped when the second laser beam is interrupted, and the time difference between the moment when the first laser beam is interrupted by the flying rocks and the moment when the second laser beam is interrupted by the flying rocks is obtained; S4, the data processing unit receives the time data, calculates the flying stone speed, and displays the result.

6. A method for measuring the speed of flying rocks during blasting in a tunnel according to claim 5, characterized in that: Equipment testing prior to blasting includes: 1) Equipment alignment test: ensuring that the emission port of the laser emitter (100) is accurately aligned with the receiving window of the photoelectric sensor (200); 2) Laser beam inspection: Use a laser power meter to confirm the intensity and stability of the laser beam; 3) Photoelectric sensor (200) sensitivity test: Use a digital multimeter to check the photoelectric sensor (200) and test the output signal of the photoelectric sensor (200); 4) Timer function test: simulate laser beam interruption to check whether the timer can accurately record the time and ensure that its display is normal; 5) Data processing unit calibration: Use the simulation software LabVIEW to simulate the input signal and test the real-time data processing capability of the data processing unit.

7. A method for measuring the speed of flying rocks during blasting in a tunnel according to claim 5, characterized in that: The calculation formula of flying stone velocity v is: Where v is the flying stone velocity, d is the distance between the two laser beams, Δt is the time difference between the moment when the first laser beam is interrupted by the flying stone and the moment when the second laser beam is interrupted by the flying stone, Δt coor It is correction time.

8. A method for measuring the speed of flying rocks during blasting in a tunnel according to claim 7, characterized in that: Correction time Δt coor The calculation formula is: Δt corr =k1×Δt air +k2×Δt temp +k3×Δ tvibration +k4×Δt initial In the formula, Δt air Correct the time for air drag; Δt temp is the temperature correction time; Δt vibration Correct the time for the vibration sound waves; Δt initial Initial velocity correction time; k1, k2, k3 and k4 are the weight coefficients of various correction times.

9. A method for measuring the speed of flying rocks during blasting in a tunnel according to claim 8, characterized in that: The sum of k1, k2, k3 and k4 is 1.

10. A system for measuring the speed of flying rocks during blasting in a tunnel, characterized in that: include: Device installation module: installing the laser emitter (100) and the photoelectric sensor (200) on both sides of the tunnel respectively, adjusting the height of the laser emitter (100) to prevent dust in the tunnel from interfering with the laser beam, and adjusting the receiving window of the photoelectric sensor (200) to align with the emission port of the laser emitter (100); and aligning the clearance holes (301) of the two limit baffles (300) so that the axial direction of the clearance holes (301) is perpendicular to the direction of the laser beam; Device test module: Start the timer to prepare for device testing before blasting; Timing module: blasting is performed and flying stones are observed passing through the laser beam; the laser emitter (100) emits a laser beam, and timing starts when the first laser beam is interrupted, and timing stops when the second laser beam is interrupted, and the time difference between the moment when the first laser beam is interrupted by the flying stone and the moment when the second laser beam is interrupted by the flying stone is obtained; And, the flying stone speed calculation module: the data processing unit receives the time data and calculates the flying stone speed v.

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