A dynamic crack high-speed photography system and method for reducing interference in a blast test

Abstract

The application provides a dynamic crack high-speed photography system and method for reducing interference in a blasting test, and belongs to the technical field of dynamic monitoring of blasting tests. A rock test piece is placed at the center of a reinforced concrete retaining wall, and a confining pressure device is arranged between the outer wall of the rock test piece and the inner wall of the reinforced concrete retaining wall. The upper surface of the rock test piece is covered with an impact-resistant flow guide protective cover. A horn-shaped flow guide pipe is arranged at the top of the impact-resistant flow guide protective cover in communication, the horn-shaped flow guide pipe is connected with a cylinder at the end, the cylinder penetrates through a protective baffle, and the high-speed camera is connected with a data processor through a connecting line. The high-speed photography method combining the flow guide protection structure, the light filtering measure and the double-view imaging can solve the problem that the dynamic crack of brittle materials such as rock and concrete is not clear in the blasting test due to the shielding of flying objects and the interference of strong light.

Description

TECHNICAL FIELD

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

[0002] In the study of rock blasting mechanism, high-speed photography technology is the core means for real-time capturing of the dynamic expansion process of blasting cracks. However, the flying objects (such as rock debris, blockages) generated in the blasting moment and the strong explosion light will seriously interfere with the imaging quality of the high-speed camera, resulting in loss of key frame data or overexposure of the image. The traditional method uses physical baffles or wide-band filters for protection, but the former easily blocks the view and causes 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 effect, and has wide application prospects in the fields of water conservancy engineering, civil engineering, and mining.

[0003] The invention patent CN115773942A adopts a double-axle compression rock blasting crack expansion testing device, which is internally provided with an explosion cavity to effectively avoid the generation of flying stones during blasting. However, this invention is used for shooting cracks after blasting is completed, and cannot dynamically shoot the explosion process. The methods provided by the invention patents CN103674685A and CN102539650A can dynamically shoot rock blasting cracks, but do not solve the problems of flying object obstruction and explosion light pollution during the blasting process of general rock specimens, especially when the blast hole has a certain depth and there are many blockages, the explosion action produces more smoke and dust to form an obstruction.

[0004] To solve the above problems, the existing technology mainly deals with interference from two directions of physical protection and light source supplementation. The former uses metal grids or transparent baffles to block flying objects, but cannot solve the obstruction of flying objects to the camera after they are ejected from the blast hole. The latter is easy to cause overexposure of the camera together with the strong explosion light. SUMMARY

[0005] To solve the above problems, the present application provides a dynamic crack high-speed photography system and method for reducing interference in blasting tests, which adopts a high-speed photography method combining a flow guide protection structure, a light filtering measure, and double-view imaging, and can well solve the problem of unclear dynamic crack shooting caused by flying object obstruction and explosion light interference in the blasting test of brittle materials such as rock and concrete.

[0006] In order to realize the above technical features, the application is achieved as follows: a dynamic crack high-speed photography system for reducing interference in a blasting test, comprising a reinforced concrete enclosure, a rock sample for the blasting test being placed at a central part of the reinforced concrete enclosure, and a confining pressure device being arranged between an outer wall of the rock sample and an inner wall of the reinforced concrete enclosure to provide confining pressure; an impact-resistant flow guide protective cover being covered on an upper surface of the rock sample; a horn-shaped flow guide pipe being arranged in communication with a top of the impact-resistant flow guide protective cover to guide blast flyaway; a cylinder being connected to an end of the horn-shaped flow guide pipe, and the cylinder penetrating through a protective baffle.

[0007] Further comprising a plurality of tripods arranged at the periphery of the reinforced concrete enclosure, and an ultraviolet lamp and a high-speed camera being arranged on each of the tripods, and the high-speed camera being connected to a data processor through a connecting line.

[0008] Preferably, the protective baffle comprises upright columns arranged in parallel outside the reinforced concrete enclosure, the upright columns being fixedly connected to a mounting base through fixing feet, and a transparent protective plate being fixed between the upright columns, and a circular hole for the cylinder being processed on the transparent protective plate.

[0009] Preferably, the confining pressure device comprises a press for pressurization, and two movable steel plates being arranged at two ends of the press respectively, and the two movable steel plates being tightly attached to the reinforced concrete enclosure and the rock sample respectively, and the press being used to fix or pre-press the rock sample according to test requirements.

[0010] Preferably, the impact-resistant flow guide protective cover comprises a transparent composite protective layer covering the surface of the rock sample, the horn-shaped flow guide pipe being arranged in communication with the top of the transparent composite protective layer and corresponding to the position of a blast hole, and the blast hole being pre-arranged in the rock sample; an inner diameter of a circular port of the horn-shaped flow guide pipe in communication with the transparent composite protective layer being greater than a diameter of the blast hole; and a top end of the horn-shaped flow guide pipe being connected to the cylinder.

[0011] Preferably, the horn-shaped flow guide pipe is an arc-shaped tubular structure with gradually increasing inner diameter, and an inclination angle of the horn-shaped flow guide pipe is designed to be 45°-50°, so as to deflect the blast flyaway after flow guiding and deviate from an optical path of the high-speed camera.

[0012] Preferably, an outer layer of the transparent composite protective layer is polycarbonate, an intermediate layer is explosion-proof glass, and an inner layer is a wear-resistant coating.

[0013] Preferably, a narrow-band filter is arranged in front of a lens of the high-speed camera, and a fluorescent marker layer is formed by spraying an ultraviolet excitation fluorescent material on the upper surface of the rock sample.

[0014] The transmission band of the narrow-band filter matches the emission spectrum of the fluorescent marker layer on the surface of the rock sample, and the transmittance is ≥90% and the half-peak width is ≤30 nm.

[0015] Preferably, the narrow-band filter: center wavelength 520 nm, transmittance ≥ 90%, half-width ≤ 30 nm; cutoff band 300-480 nm and 560-800 nm, optical density OD ≥ 6;

[0016] The excitation wavelength of the fluorescent marking layer is 365 nm, the emission wavelength is 520±5 nm, the coating thickness is 0.1 mm~0.2 mm, the high-pressure spray gun is used to uniformly cover the surface of the rock sample, and the rock sample is left to stand for a period of time to solidify.

[0017] Preferably, the number of ultraviolet lamps is at least two, and the ultraviolet lamps emit pulsed light, the wavelength of the light is 300-400 nm, and the light intensity is ≥ 5×10 4 lux;

[0018] Preferably, the number of high-speed cameras is at least three, and the high-speed cameras are bidirectional to avoid being blocked by some areas, the angle between the optical axis of each high-speed camera and the normal line of the rock sample surface is 10°~50°, and the frame rate is ≥ 100000 fps.

[0019] Another aspect of the present application provides a dynamic crack high-speed photography method for reducing interference in a blasting test, wherein the method is realized by using the dynamic crack high-speed photography system, and comprises the following steps:

[0020] Step one: pre-treat the upper surface of the rock sample, spray the ultraviolet excitation fluorescent material to form a fluorescent marking layer, then place the rock sample in the reinforced concrete enclosure, and use the pressure machine to fix or pre-press according to the test requirements;

[0021] Step two: install the impact-resistant flow guide protection cover to ensure that the impact-resistant flow guide protection cover is in close and stable contact with the rock sample, connect the cylinder with the horn-shaped flow guide pipe, and then pass through the transparent protection plate with a round hole in the protection baffle;

[0022] Step three: install the narrow-band filter on the high-speed camera after erecting the ultraviolet lamp and the high-speed camera on the inner side of the transparent protection plate;

[0023] Step four: turn on the ultraviolet lamp, and then perform the blasting test, wherein the narrow-band filter filters more than 90% of the stray light of the explosion light source;

[0024] Step five: the multi-phase high-speed camera synchronously collects images, and generates an unobstructed crack propagation image through an image fusion algorithm.

[0025] The present application has the following beneficial effects:

[0026] 1.The present application changes the trajectory of flying objects by using explosion energy through the flow design of the impact-resistant flow guide shield, actively changes the trajectory of flying objects, and directs most of the flying objects outside the protective baffle to avoid shielding; the surface fluorescence marker of the rock is excited by using the ultraviolet pulse light source, and the explosion strong light is accurately filtered by matching the narrowband filter, and the surface crack of the rock sample is accurately identified; multi-angle high-speed photography is used to generate images, breaking through the single-angle shielding limitation, so that high-definition crack propagation images are stably obtained in a strong interference environment, and reliable technical support is provided for blasting mechanism research.

[0027] 2.The present application changes the trajectory of flying objects by using explosion energy through the impact-resistant flow guide shield, and combines polycarbonate-explosion-proof glass composite layer to shorten the shielding time of flying objects from 5ms in the traditional scheme to below 0.5ms, and effectively improve the frame rate from 30% to above 85% (the measured granite sample reaches 87.3%), solving the problem of loss of key crack propagation data.

[0028] 3.The present application cooperates the narrowband filter with the ultraviolet excited fluorescence marker to migrate the crack light signal to the non-explosion light band, so that the interference intensity of the explosion light is attenuated to below 1 / 120 of the original value, and the overexposure phenomenon is eliminated. At the same time, the double-machine high-speed camera repairs the shielding area to avoid errors caused by manual intervention.

[0029] 4.The present application supports different rock types (granite, sandstone, etc.) and blasting parameters (charge amount 0.5-5g), and only needs to adjust the fluorescence coating wavelength (500-550nm) and the filter parameters to adapt.

[0030] 5.The present application realizes bidirectional shooting by using multi-angle high-speed photography and image fusion technology, avoids that part of the area is shielded, the angle between the optical axis of each camera and the normal line of the rock surface is 10°-50°, the frame rate is ≥100000 fps, and then the shooting effect is ensured.

[0031] 6.The present application adopts an image fusion algorithm, subtracts static noise in pre-processing by background difference method, and tracks crack propagation vectors of adjacent frames by optical flow method, inputs multi-angle images (4096x1024 pixels) based on a Pix2Pix GAN model, and outputs repaired unshielded crack sequences (test set F1-score 93.7%). BRIEF DESCRIPTION OF DRAWINGS

[0032] The present application will be further described below in combination with the drawings and examples.

[0033] Figure 1 It is a whole three-dimensional layout of the present application.

[0034] Figure 2 It is a schematic diagram of the confining pressure loading arrangement of the present application.

[0035] Figure 3 The structure diagram of the protective baffle of the present application.

[0036] Figure 4 The diagram of the synergistic effect of the narrow-band filter and the ultraviolet excitation fluorescent marker of the present application.

[0037] Figure 5 The three-dimensional structure diagram of the impact-resistant flow guide protective cover of the present application.

[0038] Figure 6 The sectional view of the impact-resistant flow guide protective cover of the present application.

[0039] Figure 7 The flow guide effect diagram of the impact-resistant flow guide protective cover of the present application.

[0040] In the figure: 1 - protective baffle, 101 - stand, 102 - transparent protective plate, 103 - fixing foot, 104 - round hole, 2 - reinforced concrete fence, 3 - ultraviolet lamp, 4 - high-speed camera, 5 - impact-resistant flow guide protective cover, 501 - horn-shaped flow guide pipe, 502 - transparent composite protective layer, 6 - cylinder, 7 - pressure machine, 8 - movable steel plate, 9 - triangular support, 10 - data processor, 11 - connecting line, 12 - rock specimen, 13 - narrow-band filter, 14 - fluorescent coating, 15 - blasthole. DETAILED DESCRIPTION

[0041] The embodiments of the present application will be further described below in combination with the drawings.

[0042] Example 1:

[0043] Reference Figures 1-7 A dynamic crack high-speed photography system for reducing interference in blasting test, comprising a reinforced concrete fence 2, a rock specimen 12 for blasting test is placed at the central part of the reinforced concrete fence 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 fence 2; an impact-resistant flow guide protective cover 5 covers the upper surface of the rock specimen 12; a horn-shaped flow guide pipe 501 for guiding the blasting flying objects out is arranged at the top of the impact-resistant flow guide protective cover 5, the horn-shaped flow guide pipe 501 is connected with a cylinder 6 at the end, and the cylinder 6 penetrates through the protective baffle 1; a plurality of triangular supports 9 are arranged on the periphery of the reinforced concrete fence 2, an ultraviolet lamp 3 and a high-speed camera 4 are arranged on the triangular supports 9, and the high-speed camera 4 is connected with a data processor 10 through a connecting line 11. The above-mentioned high-speed photography system can be used for dynamic crack high-speed photography in blasting test.

[0044] In the specific test process, the flow guide principle is:

[0045] At the moment of explosion, the blasting fly ash: rock debris, blockage, under the driving of high pressure gas flow along the guide pipe rising. The horn-shaped guide pipe 501 of the horn-shaped structure through the gas expansion effect reduces the flow rate, and uses the centrifugal force to deflect the fly ash to the side, and finally through the cylinder 6 to the outside of the protective baffle 1, the horn-shaped guide pipe 501 is designed as 45°, to ensure that more than 90% of the fly ash deviates from the light path of the high-speed camera.

[0046] Further, the protective baffle 1 includes a column 101 arranged in parallel outside the reinforced concrete fence 2, the column 101 is fixed to the installation foundation through the fixing foot 103, the transparent protective plate 102 is fixed between the columns 101, and the transparent protective plate 102 is processed with a round hole 104 for passing through the cylinder 6. The above-mentioned protective baffle 1 can be used to block the blasting fly ash after the guide discharge, thereby effectively preventing the influence of the blasting fly ash on the photography process.

[0047] Further, the confining pressure device includes a press 7 for pressurization, and the press 7 is provided with movable steel plates 8 at both ends, respectively. The two movable steel plates 8 are tightly attached to the reinforced concrete fence 2 and the rock sample 12, respectively, and the rock sample 12 is fixed or pre-pressed according to the test requirements through the press 7. The above-mentioned confining pressure device facilitates pressure application. During the test, when pressure test is required, the press 7 is started to provide pressure to the movable steel plates 8, and then the rock sample 12 is pressurized through the movable steel plates 8.

[0048] Further, the impact-resistant guide protection cover 5 includes a transparent composite protective layer 502 covering the surface of the rock sample 12, and the horn-shaped guide pipe 501 is connected to the top of the transparent composite protective layer 502 and corresponds to the position of the blast hole 15, which is pre-set in the rock sample 12. The inner diameter of the circular port of the horn-shaped guide pipe 501 connected to the transparent composite protective layer 502 is greater than the diameter of the blast hole 15; the top end of the horn-shaped guide pipe 501 is connected to the cylinder 6. The above-mentioned impact-resistant guide protection cover 5 can effectively realize the guide of the blasting fly ash during the blasting process. In the specific test process, the blasting fly ash enters the horn-shaped guide pipe 501 through the blast hole 15, and then enters the cylinder 6 after being guided by the horn-shaped guide pipe 501, and the blasting fly ash is guided to the outside of the protective baffle 1 through the cylinder 6.

[0049] Further, the horn-shaped guide pipe 501 is an arc-shaped tubular structure with gradually increasing inner diameter, and the inclination angle of the horn-shaped guide pipe 501 is designed as 45°~50°, thereby deflecting the blasting fly ash after being guided away from the light path of the high-speed camera 4. Through the above-mentioned specific size structure, the guide effect is ensured.

[0050] Further, the outer layer of the transparent composite protective layer 502 is polycarbonate, the middle layer is explosion-proof glass, and the inner layer is a wear-resistant coating. The transparent composite protective layer 502 can ensure the structural strength and facilitate light transmission, thereby ensuring the photography quality.

[0051] Further, the lens of the high-speed camera 4 is provided with a narrow-band filter 13, and the upper surface of the rock sample 12 is sprayed with ultraviolet excitation fluorescent material to form a fluorescent marking layer 14.

[0052] 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 sample 12, with a transmittance ≥ 90% and a half-peak width ≤ 30 nm.

[0053] The narrow-band filter 13 and the fluorescent marking layer 14 can achieve synergistic effect, which can migrate the crack light signal to the non-explosive light band, attenuate the explosion light interference intensity to 1 / 120 of the original value, and eliminate the overexposure phenomenon. At the same time, the double-camera high-speed camera repairs the blocked area to avoid errors caused by manual intervention.

[0054] Further, the narrow-band filter 13 has a center wavelength of 520 nm, a transmittance ≥ 90%, and a half-peak width ≤ 30 nm; a cutoff band of 300-480 nm and 560-800 nm, and an optical density OD ≥ 6.

[0055] The fluorescent marking layer 14 is composed of rare earth doped aluminate, such as SrAl2O4: Eu, Dy. The excitation wavelength of the fluorescent marking layer 14 is 365 nm, the emission wavelength is 520±5 nm, the coating thickness is 0.1 mm~0.2 mm, and the high-pressure spray gun is used to uniformly cover the surface of the rock sample 12, and then it is left to solidify for a period of time.

[0056] Through the above synergistic effect, the optical principle is:

[0057] The main peak of the explosion light is distributed in 400-500 nm (visible light) and 600-800 nm (infrared), while the fluorescent marking layer emits 520 nm narrow-band light signal under ultraviolet excitation. The narrow-band filter only allows 520 nm band to pass, and the explosion light intensity is attenuated to 1 / 120 of the original value. The measured value decreases from 1.2×10 6 cd / m² to 1.0×10³ cd / m², and the fluorescent signal intensity increases to 2.5×10³ cd / m².

[0058] Further, the number of ultraviolet lamps 3 is at least two, and the ultraviolet lamps 3 emit pulsed light with a wavelength of 300-400 nm and an intensity ≥ 5×10 4lux; the number of the high-speed cameras 4 is at least three, bidirectional shooting is realized to avoid partial area being shielded, the angle between the optical axis of each high-speed camera 4 and the normal line of the rock sample 12 surface is 10°-50°, and the frame rate is greater than or equal to 100000 fps. Through the multi-view high-speed photography and image fusion technology of the above multiple sets of ultraviolet lamps 3 and high-speed cameras 4, the single-view shielding limitation is broken through, so that the high-definition crack propagation image is stably obtained in the strong interference environment, and reliable technical support is provided for the blasting mechanism research.

[0059] Embodiment 2

[0060] Another aspect of the present application provides a dynamic crack high-speed photography method for reducing interference in a blasting test, which is realized by using the dynamic crack high-speed photography system and comprises the following steps:

[0061] Step one: the upper surface of the rock sample 12 is pretreated, the fluorescent marker layer 14 is formed by spraying ultraviolet excitation fluorescent material, then the rock sample 12 is placed in the reinforced concrete enclosure 2, and the pressurizing machine 7 is used to fix or pre-press according to the test requirements;

[0062] Step two: the impact-resistant flow guide protective cover 5 is installed to ensure that the impact-resistant flow guide protective cover 5 is in close and stable contact with the rock sample 12, the cylinder 6 is connected with the horn-shaped flow guide pipe 501, and then the transparent protective plate 102 with a round hole 104 in the protective baffle 1 is penetrated;

[0063] Step three: the ultraviolet lamp 3 and the high-speed camera 4 are erected on the inner side of the transparent protective plate 102, and the narrow-band filter 13 is installed on the high-speed camera 4;

[0064] Step four: the ultraviolet lamp 3 is turned on, and the blasting test is performed, and the narrow-band filter 13 filters more than 90% of stray light of the explosion light source;

[0065] Step five: the multi-phase high-speed camera 4 synchronously collects images, and a non-shielded crack propagation image is generated through an image fusion algorithm.

[0066] Embodiment 3

[0067] In this embodiment, the corresponding blasting test process is carried out by taking granite as the rock sample 12, which specifically comprises the following steps:

[0068] Step 1, a granite cube (400mm×400mm×150mm) is used, a charge hole with a diameter of 10mm and a depth of 100mm is drilled in the center, as shown in FIG. 1. Figure 2 Before the test, the steel bars are bound according to the size of the test site, the formwork is erected, the reinforced concrete structure enclosure is poured with the mixed concrete paste, and the curing is maintained for 28 days.

[0069] Step 2, surface pre-treatment of granite specimen, first polish the upper surface 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 the ultraviolet excitation fluorescent material (SrAl2O4:Eu, Dy fluorescent powder, excitation wavelength 365 nm, emission wavelength 520 nm), coating thickness 0.1 mm~0.2 mm, coverage rate ≥95%; after spraying, stand for 24 hours to ensure that the coating is firmly combined with the rock surface, such as Figure 4

[0070] Step 3, place the treated granite specimen in the middle of the reinforced concrete barrier, place a movable steel plate around the granite and on the inner wall of the corresponding reinforced concrete barrier, use a press to apply pressure to the rock specimen to ensure that the granite is fixed in the middle of the reinforced concrete barrier, then install explosives in the blast hole.

[0071] Step 4, install the impact-resistant flow guide protective cover, the structure of the impact-resistant flow guide protective cover is as shown in Figures 5-6 The impact-resistant flow guide protective cover is composed of a polycarbonate outer layer, a tempered explosion-proof glass interlayer, and an anti-reflection (AR) inner layer. Connect the horn-shaped flow guide tube with the transparent protective cover, use a laser positioning instrument to calibrate the coaxiality of the center line of the horn-shaped flow guide tube with the blast hole, then use a magnetic clamp to adsorb the protective cover to the rock surface to avoid mechanical vibration affecting imaging. At the same time, the detonation lead of the explosive is drawn out from the horn-shaped flow guide tube of the impact-resistant flow guide protective cover.

[0072] Step 5, splice the protective baffle as shown in Figure 3 , then place the protective baffle on any one side of the reinforced concrete barrier and fix it with a fixing foot as shown in Figure 1 . Then pass the cylinder through the protective baffle and connect it with the horn-shaped flow guide tube through the flange, fill the joint with high-temperature resistant sealant, and also draw the detonation lead of the explosive out of the cylinder.

[0073] Step 6, as shown in Figure 1 , on the outside of the reinforced concrete barrier, except for one side of the protective baffle, one high-speed camera is arranged on each of the other three sides. On the symmetric sides of the cylinder axis, i.e. on the two sides of the reinforced concrete barrier, one ultraviolet lamp is arranged on each side, and the directions of the two ultraviolet lamps are exactly opposite. The ultraviolet lamp and the high-speed camera are both erected and fixed with tripods, and the height of the tripod is adjusted according to the shooting angle of the test, and the shooting angle of the high-speed camera and the irradiation angle of the ultraviolet lamp are also adjusted.

[0074] Step 7, install a narrow band filter in front of the lens of the high-speed camera, and connect the high-speed camera to the data processor using a connecting line. Then turn on the ultraviolet lamp and use a luxmeter (Luxmeter LX-1010B) to measure the rock surface to ensure that the illuminance is ≥5×10​4 lux.

[0075] Step 8: After the work of the above steps is completed, connect the detonation line with the initiator, personnel evacuate to a safe area, turn on the high-speed camera, set the shooting start time and shooting parameters. Then ignite the detonation, and after the detonation is completed, synthesize and analyze the images on the data processor. Take the first frame (before blasting) as the reference, subtract the static noise (threshold set to gray value ± 5%) frame by frame, input the multi-view images into the pre-trained GAN model, and output the repaired images (resolution 1280x720 pixels).

[0076] As shown in Figure 4 , when the ultraviolet lamp irradiates on the surface of the granite test piece coated with fluorescent substance, the fluorescent substance emits light of 520 nm, the narrow-band filter added in front of the lens of the high-speed camera 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, thereby avoiding the influence of the explosion light source on the shooting of the surface crack of the granite test piece.

[0077] As shown in Figure 7 , at the moment of explosion, the flying matters (rock debris, blockage) rise along the guide pipe under the driving of high-pressure gas flow. The horn-shaped structure of the guide pipe reduces the flow rate through the gas expansion effect, and deflects the flying matters to the side by centrifugal force, and finally discharges them to the outside of the protective baffle through the cylinder.

[0078] Example 4:

[0079] Example effect comparison:

[0080] In the traditional scheme, the flying matters completely block the single-camera view within 2-5 ms, and the effective frame rate is only 28.5%; in the present application, the impact-proof deflector makes 90% of the flying matters guided out of the camera light path, and the shielding time is shortened to 0.3-0.8 ms, combined with multi-view repair, the effective frame rate is improved to 87.3%.

[0081] By spraying fluorescent substance on the surface of the rock test piece, cooperating with the ultraviolet lamp and the narrow-band filter, the explosion light is effectively filtered, and the explosion light intensity is reduced from 1.2x10 6 cd / m² to 1.0x10³ cd / m² (attenuation of 1200 times); while the fluorescent signal intensity reaches 2.5x10³ cd / m², effectively resisting the interference of the explosion light source.

[0082] The specific embodiments of the present application are described in detail above, but it is only one of the embodiments, and the present application is not limited to the specific embodiments described above. Any equivalent modification and substitution of the present application made by those skilled in the art is also within the scope of the present application. Therefore, any equivalent transformation and modification made without departing from the spirit and scope of the present application should be covered within the scope of the present application.

Claims

1. A dynamic crack high speed photographic system for use in a blast test to reduce interference, characterized by, The application relates to a rock blasting test device, which comprises a reinforced concrete fence (2), a rock test piece (12) for blasting test is arranged at the central part of the reinforced concrete fence (2), a confining pressure device for providing confining pressure is arranged between the outer wall of the rock test piece (12) and the inner wall of the reinforced concrete fence (2); the upper surface of the rock test piece (12) is covered with an anti-impact flow guide protective cover (5); a horn-shaped flow guide pipe (501) for guiding blasting flying matters is arranged at the top of the anti-impact flow guide protective cover (5) in a communicating mode, the horn-shaped flow guide pipe (501) is connected with a cylinder (6), and the cylinder (6) penetrates through a protective baffle (1); a plurality of tripods (9) are arranged outside the reinforced concrete fence (2), ultraviolet lamps (3) and high-speed cameras (4) are arranged on the tripods (9), and the high-speed cameras (4) are connected with a data processor (10) through connecting lines (11); the anti-impact flow guide protective cover (5) comprises a transparent composite protective layer (502) covering the surface of the rock test piece (12), the horn-shaped flow guide pipe (501) is arranged at the top of the transparent composite protective layer (502) in a communicating mode and corresponds to the position of a blast hole (15) arranged in the rock test piece (12) in advance; the inner diameter of a circular opening, which is in communication with the transparent composite protective layer (502), of the horn-shaped flow guide pipe (501) is larger than the diameter of the blast hole (15); and the top end of the horn-shaped flow guide pipe (501) is connected with the cylinder (6). the horn-shaped flow guide pipe (501) is an arc-shaped tubular structure with gradually increasing inner diameter, the inclination angle of the horn-shaped flow guide pipe (501) is designed to be 45-50 degrees, so that the blasting flying matters are guided to deviate from the light path of the high-speed camera (4); 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 a fluorescent material on the upper surface of the rock test piece (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 test piece (12), the transmittance is greater than or equal to 90%, and the half peak width is less than or equal to 30 nm.

2. The dynamic crack high-speed photography system for reducing interference in a blasting test according to claim 1, characterized in that, the protective baffle (1) comprises vertical columns (101) arranged in parallel outside the reinforced concrete fence (2), the vertical columns (101) are fixedly connected with a mounting base through fixing feet (103), transparent protective plates (102) are fixed between the vertical columns (101), and circular holes (104) for penetrating through the cylinder (6) are formed in the transparent protective plates (102).

3. The dynamic crack high-speed photography system for use in a blast test to reduce interference according to claim 2, characterized in that, the confining pressure device comprises a presser (7) for pressurization, two movable steel plates (8) are arranged at the two ends of the presser (7) respectively, the two movable steel plates (8) are tightly attached to the reinforced concrete fence (2) and the rock test piece (12) respectively, and the presser (7) is used for fixing or pre-pressing the rock test piece (12) according to test requirements.

4. The dynamic crack high-speed photography system for use in a blast test to reduce interference according to claim 2, characterized in that, the outer layer of the transparent composite protective layer (502) is polycarbonate, the middle layer is explosion-proof glass, and the inner layer is a wear-resistant coating.

5. The dynamic crack high-speed photography system for use in a blast test to reduce interference according to claim 2, characterized in that, the narrow-band filter (13) has a central wavelength of 520 nm, a transmittance greater than or equal to 90%, a half peak width less than or equal to 30 nm, a cutoff band of 300-480 nm and 560-800 nm, and an optical density OD greater than or equal to 6. The excitation wavelength of the fluorescent marking layer (14) is 365 nm, the emission wavelength is 520±5 nm, the coating thickness is 0.1 mm~0.2 mm, and the high-pressure spray gun is used to uniformly cover the surface of the rock specimen (12), and then it is left for a period of time to solidify.

6. The dynamic crack high-speed photography system for use in a blast test to reduce interference according to claim 2, wherein The number of the ultraviolet lamps (3) is at least two, and the ultraviolet lamps (3) emit pulsed light with a wavelength of 300-400 nm and a light intensity of ≥5×10 4 lux. The number of high-speed cameras (4) is at least three, which realizes bidirectional shooting to avoid partial area being blocked, the 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 is ≥100000 fps.

7. A dynamic crack high speed photography method for reducing interference in a blasting test, characterized in that, The method adopts the dynamic crack high-speed photography system of any one of claims 3-6 to realize, including the following steps: Step one: pretreat the upper surface of the rock specimen (12), spray the ultraviolet excitation fluorescent material to form a fluorescent marking layer (14), then place the rock specimen (12) in the reinforced concrete fence (2), and use the pressurizing machine (7) to fix or pre-press according to the test requirements; Step two: install the impact-resistant flow guide protection cover (5) to ensure that the impact-resistant flow guide protection cover (5) is in close and stable contact with the rock specimen (12), and then connect the cylinder (6) with the horn-shaped flow guide pipe (501), and then pass through the transparent protection plate (102) with a round hole (104) in the protection baffle (1); Step three: erect the ultraviolet lamp (3) and the high-speed camera (4) on the inner side of the transparent protection plate (102), and then install the narrowband filter (13) on the high-speed camera (4); Step four: turn on the ultraviolet lamp (3), then perform the blasting test, and the narrowband filter (13) filters more than 90% of the stray light of the explosion light source; Step five: the multi-phase high-speed camera (4) synchronously collects images, and generates an unblocked crack propagation image through an image fusion algorithm.

Images