Dynamic crack high-speed photographing system and method for reducing interference in blasting test

Abstract

The invention provides a dynamic crack high-speed photography system and method for reducing interference in a blasting test, and belongs to the technical field of blasting test dynamic monitoring, a rock test piece is placed in the center of a reinforced concrete fence, and a confining pressure device is arranged between the outer wall of the rock test piece and the inner wall of the reinforced concrete fence; the upper surface of the rock test piece is covered with an anti-impact flow guide protective cover; the top of the anti-impact flow guide protective cover is communicated with a horn-shaped flow guide pipe, the tail end of the horn-shaped flow guide pipe is connected with a cylinder, and the cylinder penetrates through the protective baffle; the system further comprises an ultraviolet lamp and a high-speed camera, and the high-speed camera is connected with the data processor through a connecting line. According to the method, a high-speed photographing method combining a flow guide protection structure, a light filtering measure and double-view-angle imaging is adopted, so that the problem that dynamic cracks of fragile materials such as rocks and concrete are not clearly photographed due to flying object shielding and explosion strong light interference in a blasting test can be well solved.

Description

Technical Field

[0001] The invention relates to the technical field of dynamic monitoring of blasting tests, and in particular to a dynamic crack high-speed photography system and method for reducing interference in blasting tests. Background Art

[0002] In the study of rock blasting mechanism, high-speed photography technology is the core means to capture the dynamic expansion process of blasting cracks in real time. However, the flying objects (such as rock chips and blockages) and the strong light of the explosion generated at the moment of blasting will seriously interfere with the imaging quality of the high-speed camera, resulting in the loss of key frame data or overexposure of the image. Traditional methods use physical baffles or wide-band filters for protection, but the former is easy to block the field of view and easily cause structural vibration, and the latter cannot distinguish between explosion light and effective signals, resulting in a significant reduction in crack contrast. Solving this problem has direct practical value for clearly obtaining the dynamic expansion process of blasting cracks, and is of great significance for the analysis and safety control of blasting rock breaking effects. It has broad application prospects in water conservancy engineering, civil engineering, mining and other fields.

[0003] Invention patent CN115773942A uses a rock blasting crack expansion test device under biaxial compression, with an explosion chamber inside to effectively avoid the generation of flying rocks from the explosion. However, the invention is used to shoot cracks after the blasting is completed, and cannot dynamically shoot the explosion process. Although the methods provided by invention patents CN103674685A and CN102539650A can dynamically shoot rock blasting cracks, they do not solve the problem of flying objects blocking and explosion light source pollution in the blasting process of general rock specimens, especially when the blasthole has a certain depth and there are many blockages, the explosion generates more smoke and dust to form a blocking problem.

[0004] To solve the above problems, the existing technology mainly deals with interference from two directions: physical protection and light source supplement. The former mostly uses metal grids or transparent baffles to block flying objects, but it cannot solve the obstruction of the camera caused by flying objects after rushing out of the blast hole. The latter is easy to cause overexposure of the camera together with the strong light of the explosion. Summary of the invention

[0005] In view of the above problems, the present invention provides a dynamic crack high-speed photography system and method for reducing interference in blasting tests. This system and method, by adopting a high-speed photography method that combines a diversion protection structure, filtering measures and dual-view imaging, can effectively solve the problem of unclear dynamic crack photography of brittle materials such as rocks and concrete due to obstruction by flying objects and interference from strong explosion light in blasting tests.

[0006] In order to achieve the above technical features, the object of the present invention is achieved as follows: A high-speed photography system for dynamic crack in a blasting test to reduce interference, including a reinforced concrete enclosure. A rock specimen for the blasting test is placed at the central part of the reinforced concrete enclosure. A confining pressure device for providing confining pressure is arranged between the outer wall of the rock specimen and the inner wall of the reinforced concrete enclosure; The upper surface of the rock specimen is covered with an impact-resistant diversion protective cover; A horn-shaped diversion pipe for guiding blasting debris is connected and communicated at the top of the impact-resistant diversion protective cover. The end of the horn-shaped diversion pipe is connected to a cylinder, and the cylinder passes through a protective baffle; It also includes a plurality of tripods arranged outside the reinforced concrete enclosure. An ultraviolet lamp and a high-speed camera are arranged on the tripods. The high-speed camera is connected to a data processor through a connecting wire.

[0007] Preferably, the protective baffle includes columns arranged in parallel on the outside of the reinforced concrete enclosure. The columns are fixedly connected to the installation foundation through fixed feet. A transparent protective plate is fixed between the columns. A circular hole for passing through the cylinder is processed on the transparent protective plate.

[0008] Preferably, the confining pressure device includes a pressure machine for pressurization. Movable steel plates are respectively arranged at both ends of the pressure machine. The two movable steel plates are respectively in close contact with the reinforced concrete enclosure and the rock specimen, and the rock specimen is fixed or pre-pressurized according to the test requirements through the pressure machine.

[0009] Preferably, the impact-resistant diversion protective cover includes a transparent composite protective layer covering the surface of the rock specimen. The horn-shaped diversion pipe is connected and communicated at the top of the transparent composite protective layer and corresponds to the position of the blast hole. The blast hole is pre-set inside the rock specimen; The inner diameter of the circular opening where the horn-shaped diversion pipe is connected to the transparent composite protective layer is larger than the diameter of the blast hole; The top end of the horn-shaped diversion pipe is connected to a cylinder.

[0010] Preferably, the horn-shaped diversion pipe is an arc-shaped tubular structure with a gradually expanding inner diameter. The inclination angle of the horn-shaped diversion pipe is designed to be 45° - 50°, so as to deflect the blasting debris after diversion from the optical path of the high-speed camera.

[0011] Preferably, the outer layer of the transparent composite protective layer is made of polycarbonate, the middle layer is made of explosion-proof glass, and the inner layer is made of wear-resistant coating.

[0012] Preferably, a narrow-band filter is arranged in front of the lens of the high-speed camera, and a fluorescent marking layer is formed by spraying an ultraviolet-excited fluorescent material on the upper surface of the rock specimen; The transmission band of the narrow-band filter matches the emission spectrum of the fluorescent marking layer on the surface of the rock specimen, the transmittance ≥ 90%, and the full width at half maximum ≤ 30nm.

[0013] Preferably, the narrow-band filter has a central wavelength of 520 nm, a transmittance of ≥90%, and a full width at half maximum of ≤30 nm; the cut-off bands are 300 - 480 nm and 560 - 800 nm, and the optical density OD ≥ 6; The excitation wavelength of the fluorescent marker layer is 365 nm, the emission wavelength is 520 ± 5 nm, the coating thickness is 0.1 mm to 0.2 mm, and it is evenly covered on the surface of the rock specimen by a high-pressure spray gun and left to cure for a period of time.

[0014] Preferably, the number of the ultraviolet lamps is at least two, and pulsed light is emitted by the ultraviolet lamps. The wavelength of the light is 300 - 400 nm, and the light intensity ≥ 5×10 4 lux; Preferably, the number of the high-speed cameras is at least three to achieve two-way shooting to avoid partial areas being blocked. The included angle between the optical axis of each high-speed camera and the normal of the rock specimen surface is 10° - 50°, and the frame rate ≥ 100000 fps.

[0015] On the other hand, the present invention provides a high-speed photography method for dynamic cracks to reduce interference in blasting tests. The method is implemented by using the dynamic crack high-speed photography system, and includes the following steps: Step 1: Pretreat the upper surface of the rock specimen, spray an ultraviolet-excited fluorescent material to form a fluorescent marker layer, then place the rock specimen in a reinforced concrete enclosure, and fix or apply pre-pressure according to the test requirements by using a pressure machine; Step 2: Install an impact-resistant diversion protective cover to ensure that the contact between the impact-resistant diversion protective cover and the rock specimen is tight and stable. At the same time, connect the cylinder with the horn-shaped diversion pipe, and then pass through the transparent protective plate with a circular hole in the protective baffle; Step 3: Set up ultraviolet lamps and high-speed cameras in the test site on the inner side of the transparent protective plate, and then install narrow-band filters on the high-speed cameras; Step 4: Turn on the ultraviolet lamps, and then perform the blasting test. The narrow-band filter filters more than 90% of the stray light of the explosion light source; Step 5: The multi-phase high-speed cameras synchronously collect images, and an unobstructed crack propagation image is generated through an image fusion algorithm.

[0016] The present invention has the following beneficial effects: 1. Through the diversion design of the impact-resistant diversion protective cover, the present invention utilizes the explosion energy to actively change the movement trajectory of the flying objects, exports most of the flying objects outside the protective baffle to avoid blocking; uses the ultraviolet pulsed light source to excite the fluorescence marker on the rock surface, and precisely filters the explosion strong light by matching the narrow-band filter, and precisely identifies the cracks on the surface of the rock specimen; uses multi-directional perspective high-speed photography for image generation, breaks through the single-perspective occlusion limitation, so as to stably obtain high-definition crack propagation images in a strong interference environment, providing reliable technical support for the research of blasting mechanism.

[0017] 2. The present invention uses an impact-resistant diversion protective cover to change the movement trajectory of flying objects by means of the explosion energy itself, and combines a polycarbonate-explosion-proof glass composite layer, so that the shielding time of flying objects is shortened from 5 ms in the traditional solution to less than 0.5 ms, and the effective frame rate is increased from 30% to more than 85% (the measured value for granite specimens reaches 87.3%), solving the problem of loss of key crack propagation data.

[0018] 3. The present invention uses the synergistic effect of a narrow-band filter and an ultraviolet-excited fluorescence marker to migrate the crack optical signal to a non-explosion light band, so that the interference intensity of the explosion light is attenuated to less than 1 / 120 of the original value, eliminating the overexposure phenomenon. At the same time, a dual-camera high-speed camera repairs the occluded area to avoid errors caused by manual intervention.

[0019] 4. The present invention supports different rock types (such as granite, sandstone, etc.) and blasting parameters (charge amount 0.5 - 5 g), and only needs to adjust the wavelength of the fluorescent coating (500 - 550 nm) and the filter parameters to adapt.

[0020] 5. The present invention uses multi-view high-speed photography and image fusion technology to achieve two-way shooting, avoiding partial occlusion. The included angle between the optical axis of each camera and the normal line of the rock surface is 10° - 50°, and the frame rate ≥ 100000 fps, thus ensuring the shooting effect.

[0021] 6. The present invention uses an image fusion algorithm. In the preprocessing, the background difference method is used to deduct static noise, and the optical flow method is used to track the crack propagation vector of adjacent frames. Based on the Pix2Pix GAN model, multi-view images (4096×1024 pixels) are input, and an unoccluded crack sequence after repair is output (the F1-score of the test set is 93.7%). Description of the Drawings

[0022] The following further describes the present invention with reference to the drawings and embodiments.

[0023] Figure 1 This is the overall three-dimensional layout diagram of the present invention.

[0024] Figure 2 This is the schematic diagram of the confining pressure loading layout of the present invention.

[0025] Figure 3 This is the structural diagram of the protective baffle of the present invention.

[0026] Figure 4 This is the diagram of the synergistic effect of the narrow-band filter and the ultraviolet-excited fluorescence marker of the present invention.

[0027] Figure 5 This is the three-dimensional structural diagram of the impact-resistant diversion protective cover of the present invention.

[0028] Figure 6 This is a cross-sectional view of the impact-resistant and flow-guiding protective cover of the present invention.

[0029] Figure 7 This is a diagram showing the flow-guiding effect of the impact-resistant and flow-guiding protective cover of the present invention; In the figure: 1 - protective baffle, 101 - column, 102 - transparent protective plate, 103 - fixed foot, 104 - round hole, 2 - reinforced concrete enclosure, 3 - ultraviolet lamp, 4 - high-speed camera, 5 - impact-resistant and flow-guiding protective cover, 501 - horn-shaped flow-guiding pipe, 502 - transparent composite protective layer, 6 - cylinder, 7 - pressure machine, 8 - movable steel plate, 9 - triangular bracket, 10 - data processor, 11 - connecting wire, 12 - rock specimen, 13 - narrow-band filter, 14 - fluorescent coating, 15 - blast hole. Specific embodiments

[0030] The following further describes the embodiments of the present invention with reference to the accompanying drawings.

[0031] Embodiment 1: Referring to Figures 1-7 , a high-speed photography system for dynamic crack in blasting tests to reduce interference, including a reinforced concrete enclosure 2. A rock specimen 12 for blasting tests is placed at the central part of the reinforced concrete enclosure 2. A confining pressure device for providing confining pressure is arranged between the outer wall of the rock specimen 12 and the inner wall of the reinforced concrete enclosure 2; an impact-resistant and flow-guiding protective cover 5 is covered on the upper surface of the rock specimen 12; a horn-shaped flow-guiding pipe 501 for discharging blasting scattered objects is communicatedly arranged at the top of the impact-resistant and flow-guiding protective cover 5. The end of the horn-shaped flow-guiding pipe 501 is connected to a cylinder 6, and the cylinder 6 passes through the protective baffle 1; also included are a plurality of triangular brackets 9 arranged outside the reinforced concrete enclosure 2. An ultraviolet lamp 3 and a high-speed camera 4 are arranged on the triangular brackets 9, and the high-speed camera 4 is connected to a data processor 10 through a connecting wire 11. By adopting the above high-speed photography system, it can be used for high-speed photography of dynamic cracks in blasting tests.

[0032] During the specific test process, the flow-guiding principle is as follows: At the moment of explosion, the blasting scattered objects: rock debris, plugging materials, rise along the flow-guiding pipe under the drive of high-pressure air flow. The horn-shaped structure of the horn-shaped flow-guiding pipe 501 reduces the flow rate through the gas expansion effect and uses the centrifugal force to deflect the scattered objects to the side, and finally discharges them outside the protective baffle 1 through the cylinder 6. The inclination angle of the horn-shaped flow-guiding pipe 501 is designed to be 45°, ensuring that more than 90% of the scattered objects deviate from the optical path of the high-speed camera.

[0033] Furthermore, the protective baffle 1 includes columns 101 arranged in parallel on the outer side of the reinforced concrete retaining wall 2. The columns 101 are fixedly connected to the installation foundation through fixing feet 103. A transparent protective plate 102 is fixed between the columns 101, and a circular hole 104 for passing through the cylinder 6 is processed on the transparent protective plate 102. The above-mentioned protective baffle 1 can be used to block the blasting scattered objects after the diversion discharge, thereby effectively preventing the influence of the scattering of the blasting scattered objects on the photography process.

[0034] Furthermore, the confining pressure device includes a press 7 for applying pressure. Movable steel plates 8 are respectively arranged at both ends of the press 7. The two movable steel plates 8 are respectively in close contact with the reinforced concrete retaining wall 2 and the rock specimen 12, and the rock specimen 12 is fixed or pre-pressed according to the test requirements through the press 7. The above-mentioned confining pressure device facilitates the application of pressure. During the test process, when pressure testing is required, by starting the press 7, the press 7 provides pressure to the movable steel plate 8, and then the rock specimen 12 is pressurized through the movable steel plate 8.

[0035] Furthermore, the impact-resistant diversion protective cover 5 includes a transparent composite protective layer 502 covering the surface of the rock specimen 12. A horn-shaped diversion pipe 501 is connected and arranged at the top of the transparent composite protective layer 502 and corresponds to the position of the blast hole 15. The blast hole 15 is pre-set inside the rock specimen 12; the inner diameter of the circular opening where the horn-shaped diversion pipe 501 is connected to the transparent composite protective layer 502 is larger than the diameter of the blast hole 15; the top end of the horn-shaped diversion pipe 501 is connected to the cylinder 6. The above-mentioned impact-resistant diversion protective cover 5 can effectively achieve the diversion of the blasting scattered objects during the blasting process. During the specific test process, the blasting scattered objects enter the horn-shaped diversion pipe 501 through the blast hole 15, and then enter the cylinder 6 after being diverted through the horn-shaped diversion pipe 501, and the blasting scattered objects are guided to the outside of the protective baffle 1 through the cylinder 6.

[0036] Furthermore, the horn-shaped diversion pipe 501 is an arc-shaped tubular structure with a gradually expanding inner diameter, and the inclination angle of the horn-shaped diversion pipe 501 is designed to be 45° - 50°, so as to deflect the blasting scattered objects after diversion from the optical path of the high-speed camera 4. Through the above specific dimensional structure, the diversion effect is ensured.

[0037] Furthermore, the outer layer of the transparent composite protective layer 502 is made of polycarbonate, the middle layer is made of explosion-proof glass, and the inner layer is made of wear-resistant coating. Through the above transparent composite protective layer 502, while ensuring its structural strength, it is convenient for light transmission, thereby ensuring the photography quality.

[0038] Furthermore, a narrow-band filter 13 is arranged in front of the lens of the high-speed camera 4, and a fluorescent marking layer 14 is sprayed on the upper surface of the rock specimen 12 with an ultraviolet-excited fluorescent material; The transmission band of the narrow-band filter 13 matches the emission spectrum of the fluorescence labeling layer 14 on the surface of the rock specimen 12, with a transmittance ≥ 90% and a full width at half maximum ≤ 30 nm.

[0039] By using the narrow-band filter 13 and the fluorescence labeling layer 14, a synergistic effect can be achieved, which can migrate the crack light signal to the non-explosion light band, attenuate the explosion light interference intensity to less than 1 / 120 of the original value, and eliminate the overexposure phenomenon. At the same time, the double-camera high-speed camera repairs the occluded area to avoid errors caused by manual intervention.

[0040] Further, the narrow-band filter 13: the central wavelength is 520 nm, the transmittance ≥ 90%, the full width at half maximum ≤ 30 nm; the cut-off band is 300 - 480 nm and 560 - 800 nm, and the optical density OD ≥ 6; The fluorescence labeling layer 14 is composed of rare earth-doped aluminate, such as SrAl2O4: Eu, Dy. The excitation wavelength of the fluorescence labeling layer 14 is 365 nm, the emission wavelength is 520 ± 5 nm, the coating thickness is 0.1 mm to 0.2 mm, and it is evenly covered on the surface of the rock specimen 12 by a high-pressure spray gun and left to cure for a period of time.

[0041] Through the above-mentioned synergistic effect, its optical principle is as follows: The main peak of the explosion light is distributed in 400 - 500 nm (visible light) and 600 - 800 nm (infrared), while the fluorescence labeling layer emits a narrow-band light signal of 520 nm under ultraviolet excitation. The narrow-band filter only allows the 520 nm band to pass through, and the explosion light intensity is attenuated to less than 1 / 120 of the original value. It is measured that it drops from 1.2×10 6 cd / m² to 1.0×10³ cd / m², and at the same time, the fluorescence signal intensity is increased to 2.5×10³ cd / m².

[0042] Further, the number of the ultraviolet lamps 3 is at least two, and pulsed light is emitted through the ultraviolet lamps 3, with the wavelength of the light being 300 - 400 nm and the light intensity ≥ 5×10 4 lux; the number of the high-speed cameras 4 is at least three, realizing two-way shooting to avoid partial occlusion. The included angle between the optical axis of each high-speed camera 4 and the normal line of the surface of the rock specimen 12 is 10° - 50°, and the frame rate ≥ 100000 fps. Through the multi-view high-speed photography and image fusion technology of the above-mentioned multiple groups of ultraviolet lamps 3 and high-speed cameras 4, the single-view occlusion limitation is broken through, so as to stably obtain high-definition crack propagation images in a strong interference environment and provide reliable technical support for the research of blasting mechanism.

[0043] Embodiment 2: On the other hand, the present invention provides a dynamic crack high-speed photography method for reducing interference in blasting tests. The method is implemented by using the dynamic crack high-speed photography system, and includes the following steps: Step 1: Pretreat the upper surface of the rock specimen 12, spray an ultraviolet-excited fluorescent material to form a fluorescent marking layer 14, then place the rock specimen 12 in the reinforced concrete enclosure 2, and use a press 7 to fix or apply pre-pressure according to the test requirements. Step 2: Install the anti-impact diversion protective cover 5 to ensure that the contact between the anti-impact diversion protective cover 5 and the rock specimen 12 is close and stable. At the same time, connect the cylinder 6 to the horn-shaped diversion pipe 501, and then pass through the transparent protective plate 102 with a circular hole 104 in the protective baffle 1. Step 3: Set up an ultraviolet lamp 3 and a high-speed camera 4 in the test site on the inner side of the transparent protective plate 102, and then install a narrow-band filter 13 on the high-speed camera 4. Step 4: Turn on the ultraviolet lamp 3, and then perform a blasting test. The narrow-band filter 13 filters more than 90% of the stray light from the explosion light source. Step 5: The multi-phase high-speed camera 4 synchronously collects images, and generates an unobstructed crack propagation image through an image fusion algorithm.

[0044] Example 3: In this example, a corresponding blasting test process is carried out using actual granite as the rock specimen 12, which specifically includes the following steps: Step 1: Use a granite cube (400mm×400mm×150mm), drill a charging hole with a diameter of 10mm and a depth of 100mm at the center, as Figure 2 shown. Before the test, tie the steel bars according to the size of the test site, set up the formwork, pour the reinforced concrete structure enclosure with the mixed concrete slurry, and cure for 28 days.

[0045] Step 2: Pretreat the surface of the granite specimen. First, polish the upper surface smoothly and wipe off dust and other contaminants; then, at a distance of 20 cm from the granite specimen, use a spray gun to evenly spray an ultraviolet-excited fluorescent material (SrAl2O4:Eu, Dy phosphor, excitation wavelength 365nm, emission wavelength 520nm), the coating thickness is 0.1mm~0.2mm, and the coverage rate ≥95%; after spraying, let it stand for 24 hours to ensure that the coating is firmly bonded to the rock surface, as Figure 4 shown.

[0046] Step 3: Place the treated granite specimen in the middle of the reinforced concrete enclosure. Place a movable steel plate on the four sides of the granite and the inner wall of the corresponding reinforced concrete enclosure. Use a press to apply a certain pressure to the rock specimen to ensure that the granite can be fixed in the middle of the reinforced concrete enclosure, and then install explosives in the blast holes.

[0047] Step 4: Install the anti-impact diversion protective cover. The structure of the anti-impact diversion protective cover is as Figures 5-6As shown, the impact-resistant diversion protective cover is composed of a polycarbonate outer layer, a toughened explosion-proof glass interlayer, and an anti-reflection (AR) inner layer. Connect the horn-shaped diversion pipe to the transparent protective cover, use a laser locator to calibrate the coaxiality of the center line of the horn-shaped diversion pipe and the blast hole, and then use a magnetic fixture to adsorb the protective cover on the rock surface to avoid the influence of mechanical vibration on imaging. At the same time, pass the lead wire for detonating the explosive through the horn-shaped diversion pipe of the impact-resistant diversion protective cover.

[0048] Step 5, complete the splicing of the protective baffle, as Figure 3 shown, and then place the protective baffle on either side outside the reinforced concrete enclosure and fix it with the fixing feet, as Figure 1 shown. Then pass the cylinder through the protective baffle and connect it to the horn-shaped diversion pipe by a flange, and fill the joint with high-temperature resistant sealant. Also pass the lead wire for detonating the explosive through the cylinder.

[0049] Step 6, as Figure 1 shown, on the outside of the reinforced concrete enclosure, except for the side with the protective baffle, arrange a high-speed camera on each of the other three sides. On the symmetric two sides of the cylinder axis, that is, on each of the two sides of the reinforced concrete enclosure, arrange an ultraviolet lamp, and the irradiation directions of the two ultraviolet lamps are exactly opposite. The ultraviolet lamp and the high-speed camera are both erected and fixed with tripods, adjust the height of the tripod according to the shooting angle of the test, and at the same time adjust the irradiation angle of the ultraviolet lamp and the shooting angle of the high-speed camera.

[0050] Step 7, install a narrow-band filter in front of the high-speed camera lens, and connect the high-speed camera to the data processor with a connecting wire. Then turn on the ultraviolet lamp, use an illuminometer (Luxmeter LX-1010B) to measure the rock surface to ensure that the illuminance ≥ 5×10 4 lux.

[0051] Step 8, after the work in the above steps is completed, connect the detonating wire to the initiator, evacuate the personnel to a safe area, turn on the high-speed camera, and set the shooting start time and shooting parameters. Then ignite and detonate. After the detonation is completed, perform synthetic analysis on the images on the data processor. Taking the first frame (before blasting) as the reference, deduct the static noise frame by frame (the threshold is set to ±5% of the gray value), input the multi-view images into the pre-trained GAN model, and output the restored images (resolution 1280×720 pixels).

[0052] As Figure 4 shown, when the ultraviolet lamp irradiates on the surface of the granite specimen coated with a fluorescent substance, the fluorescent substance emits light at 520 nm. The narrow-band filter added in front of the high-speed camera lens filters out the pollution light source generated by the explosion, allows the light emitted by the fluorescent substance to pass through and be captured by the high-speed camera, thus avoiding the influence of the explosion light source on the crack shooting of the granite specimen surface.

[0053] As Figure 7 shown, at the moment of explosion, the flying debris (rock fragments, blockages) rises along the diversion pipe driven by the high-pressure air flow. The flared structure of the diversion pipe reduces the flow velocity through the gas expansion effect and uses centrifugal force to deflect the flying debris laterally, and finally discharges it to the outside of the protective baffle through the cylinder.

[0054] Example 4: Comparison of the effects of the examples: In the traditional solution, the flying debris completely blocks the single-camera field of view within 2 - 5 ms, and the effective frame rate is only 28.5%; in the present invention, the shock-proof diversion cover diverts 90% of the flying debris outside the camera optical path, and the blocking time is shortened to 0.3 - 0.8 ms. Combined with multi-view restoration, the effective frame rate is increased to 87.3%.

[0055] By spraying a fluorescent substance on the surface of the rock specimen and cooperating with an ultraviolet lamp and a narrow-band filter, the explosion light is effectively filtered, and the explosion light intensity drops from 1.2×10 6 cd / m² to 1.0×10³ cd / m² (attenuated by 1200 times); while the fluorescence signal intensity reaches 2.5×10³ cd / m², effectively resisting the interference of the explosion light source.

[0056] The specific embodiments of the present invention have been described in detail above, but it is only one of the embodiments, and the present invention is not limited to the specific embodiments described above. For those skilled in the art, any equivalent modifications and substitutions to the present invention are also within the scope of the present invention. Therefore, any equivalent transformations and modifications made without departing from the spirit and scope of the present invention should be covered within the scope of the present invention.

Claims

1. A high-speed photography system for dynamic crack in blasting tests to reduce interference, characterized in that, It includes a reinforced concrete enclosure (2), and a rock specimen (12) for blasting test is placed at the central part of the reinforced concrete enclosure (2). A confining pressure device for providing confining pressure is arranged between the outer wall of the rock specimen (12) and the inner wall of the reinforced concrete enclosure (2); an impact-resistant diversion protective cover (5) covers the upper surface of the rock specimen (12); a horn-shaped diversion pipe (501) for diverting blasting scattered objects is connected and arranged at the top of the impact-resistant diversion protective cover (5), and the end of the horn-shaped diversion pipe (501) is connected to a cylinder (6), and the cylinder (6) passes through a protective baffle (1). It also includes a plurality of tripods (9) arranged outside the reinforced concrete enclosure (2). An ultraviolet lamp (3) and a high-speed camera (4) are arranged on the tripods (9), and the high-speed camera (4) is connected to a data processor (10) through a connecting wire (11).

2. The high-speed photography system for dynamic crack in blasting test to reduce interference according to claim 1, characterized in that, The protective baffle (1) includes columns (101) arranged in parallel on the outer side of the reinforced concrete enclosure (2). The columns (101) are fixedly connected to the installation foundation through fixing feet (103). A transparent protective plate (102) is fixed between the columns (101), and a circular hole (104) for passing through the cylinder (6) is processed on the transparent protective plate (102).

3. The high-speed photography system for dynamic crack in blasting test to reduce interference according to claim 1, characterized in that, The confining pressure device includes a pressure machine (7) for pressurization. Moving steel plates (8) are respectively arranged at both ends of the pressure machine (7). The two moving steel plates (8) are respectively in close contact with the reinforced concrete enclosure (2) and the rock specimen (12), and the rock specimen (12) is fixed or pre-pressurized according to test requirements through the pressure machine (7).

4. The high-speed photography system for dynamic crack in blasting test to reduce interference according to claim 1, characterized in that, The impact-resistant diversion protective cover (5) includes a transparent composite protective layer (502) covering the surface of the rock specimen (12). The horn-shaped diversion pipe (501) is connected and arranged at the top of the transparent composite protective layer (502) and corresponds to the position of a blast hole (15). The blast hole (15) is pre-set inside the rock specimen (12); the inner diameter of the circular opening where the horn-shaped diversion pipe (501) is connected to the transparent composite protective layer (502) is larger than the diameter of the blast hole (15); the top end of the horn-shaped diversion pipe (501) is connected to the cylinder (6).

5. The high-speed photography system for dynamic crack in a blasting test to reduce interference according to claim 4, characterized in that The horn-shaped diversion pipe (501) is an arc-shaped tubular structure with a gradually expanding inner diameter. The inclination angle of the horn-shaped diversion pipe (501) is designed to be 45° to 50°, so as to divert the blasting scattered objects and deviate from the optical path of the high-speed camera (4).

6. The high-speed photography system for dynamic crack in blasting test to reduce interference according to claim 5, wherein The outer layer of the transparent composite protective layer (502) is made of polycarbonate, the middle layer is made of explosion-proof glass, and the inner layer is made of wear-resistant coating.

7. A high-speed photography system for dynamic crack in blasting test to reduce interference according to claim 5, characterized in that A narrow-band filter (13) is arranged in front of the lens of the high-speed camera (4), and a fluorescent marking layer (14) is formed by spraying an ultraviolet-excited fluorescent material on the upper surface of the rock specimen (12); The transmission band of the narrow-band filter (13) matches the emission spectrum of the fluorescent marking layer (14) on the surface of the rock specimen (12), the transmittance is ≥90%, and the full width at half maximum is ≤30nm.

8. The dynamic crack high-speed photography system for reducing interference in a blasting test according to claim 7, characterized in that, The narrow-band filter (13): the central wavelength is 520nm, the transmittance is ≥90%, the full width at half maximum is ≤30nm; the cut-off band is 300 - 480nm and 560 - 800nm, and the optical density OD is ≥6; The excitation wavelength of the fluorescent marker layer (14) is 365 nm, the emission wavelength is 520 ± 5 nm, the coating thickness is 0.1 mm to 0.2 mm, and it is uniformly coated on the surface of the rock specimen (12) using a high-pressure spray gun and left to cure for a period of time.

9. The high-speed photography system for dynamic crack in blasting test to reduce interference according to claim 7, characterized in that, The number of the ultraviolet lamps (3) is at least two, and pulsed light is emitted through the ultraviolet lamps (3), the wavelength of the light is 300 - 400 nm, and the light intensity ≥ 5×10 4 lux; The number of the high-speed cameras (4) is at least three to achieve two-way shooting to avoid partial areas being blocked. The angle between the optical axis of each high-speed camera (4) and the normal of the surface of the rock specimen (12) is 10° to 50°, and the frame rate is ≥ 100000 fps.

10. A high-speed photography method for dynamic crack in blasting test to reduce interference, characterized in that, The method is implemented using the dynamic crack high-speed photography system described in any one of claims 7-9, and includes the following steps: Step 1: Pretreat the upper surface of the rock specimen (12), spray an ultraviolet-excitable fluorescent material to form a fluorescent marker layer (14), and then place the rock specimen (12) inside the reinforced concrete enclosure (2) and fix or preload it using a press (7) according to the test requirements. Step 2: Install the impact-resistant flow deflector shield (5) to ensure that the contact between the impact-resistant flow deflector shield (5) and the rock specimen (12) is tight and stable. At the same time, connect the cylinder (6) to the horn-shaped flow deflector tube (501), and then pass through the transparent protection plate (102) with a circular hole (104) in the protection baffle (1). Step 3: Set up an ultraviolet lamp (3) and a high-speed camera (4) on the inner test site of the transparent protection plate (102), and then install a narrow-band filter (13) on the high-speed camera (4). Step 4: Turn on the ultraviolet lamp (3), and then perform a blasting test. The narrow-band filter (13) filters more than 90% of the stray light from the explosion light source. Step 5: The multi-phase high-speed camera (4) synchronously acquires images, and generates an unobstructed crack propagation image through an image fusion algorithm.

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