A borehole blasting process transparentization testing device and blasting pressure testing method

Abstract

A blast hole detonation process transparent test device and a blasting pressure test method, relate to the field of blasting equipment. The blast hole detonation process transparent test device comprises a blockage collection box provided with a collection cavity, a detonation device, a first camera and a second camera, one end of the blockage collection box is provided with a collection hole in communication with the collection cavity and one side is provided with a first observation window; the detonation device comprises a connecting pipe, a metal sleeve and a sealing flange connected in sequence, one end of the connecting pipe extends into the collection hole, the metal sleeve is provided with an accommodating cavity inside, the accommodating cavity accommodates at least one cylindrical rock sample, the rock sample is provided with a blast hole penetrating through both ends thereof, the blast hole is used to accommodate blasting agent; the outer wall of the metal sleeve is provided with a second observation window; the first camera is used to collect images in the collection cavity through the first observation window; the second camera is used to collect images in the accommodating cavity through the second observation window. The blast hole detonation process transparent test device and method can simulate the simulated test of the real blasting engineering charging structure and realize the visualization of the detonation process.

Description

Technical Field

[0001] This application relates to the field of blasting equipment, and more specifically, to a transparent testing device for the borehole detonation process and a method for testing blasting pressure. Background Technology

[0002] In geotechnical engineering fields such as mining, tunneling, water conservancy and hydropower, and urban underground space development, the drill-and-blast method is the most traditional and widely used rock-breaking method. Its blasting effect directly depends on the pressure load generated by the detonation of explosives within the borehole and its attenuation law. Therefore, accurately obtaining the characteristics of the detonation pressure distribution and the composition of the blasting load within the borehole is a crucial prerequisite for revealing the rock-breaking mechanism of blasting, optimizing the design of the charge structure, predicting the hazards of blasting vibration, and evaluating the stability of the surrounding rock. The blasting load is the shock wave pressure acting on the surrounding rock of the borehole wall after the explosive detonation. Its peak value and waveform are affected by the type of explosive, the charge structure, coupling conditions, and rock mass characteristics, and are difficult to quantify accurately due to limitations in experimental data and theoretical research.

[0003] Currently, there are two main research methods for studying the explosive load variation history in boreholes, both domestically and internationally. The first method involves directly measuring the pressure variation history within the borehole cavity using testing elements and instruments. The second method uses theoretical analysis of the stress wave field excited by the explosive charge cavity, combined with field tests of the near-field load history curve of the explosion source, to fit a semi-empirical, semi-theoretical formula for the explosive pressure variation history curve. Theoretically, measuring the pressure within the borehole cavity is the most direct and reliable method for determining the explosive load variation history. However, due to the extreme physical conditions involved in the borehole detonation process, such as instantaneous high temperature, high pressure, high speed, and strong impact, coupled with the performance limitations of testing elements and instruments under high temperature and high pressure conditions, direct measurement of pressure within the borehole faces significant challenges. If sensors are placed directly inside the borehole, reliable fixation and effective sealing are difficult to achieve, and they may be damaged by severe impacts, resulting in extremely low measurement success rates and large data dispersion.

[0004] Currently, borehole pressure measurement mainly relies on indirect calculation methods, such as theoretical calculations based on the state equation of detonation products and empirical formulas based on the inversion of rock mass vibration velocity. However, these methods cannot directly obtain the true pressure time history curve of the borehole wall, and the calculation results are significantly affected by the uncertainty of rock mass parameters, making it difficult to meet the urgent need for accurate experimental data in blasting engineering.

[0005] Existing experimental setups have significant limitations in multi-dimensional simultaneous measurement capabilities. Most experiments can only measure pressure or strain at a single location, failing to achieve simultaneous monitoring of multiple locations and physical quantities, such as the borehole inner wall, rock sample outer wall, and inter-sample contact surfaces. The strain on the borehole inner wall reflects the direct impact effect of the detonation wave in the near-field region; the strain and stress on the rock sample outer wall characterize the propagation and attenuation of stress waves within the rock mass; and the stress transfer at the interstices of the rock samples reveals the cross-interface distribution mechanism of detonation energy in layered rock masses. Without these multi-location, multi-physical quantity simultaneous monitoring methods, it is difficult to comprehensively characterize the spatiotemporal distribution and transmission patterns of detonation loads in the rock mass, and even more difficult to establish a quantitative correlation model between detonation pressure, rock mass response, and fragmentation effect. Summary of the Invention

[0006] The purpose of this application is to provide a transparent testing device and a blasting pressure testing method for the borehole detonation process, which can simulate the actual blasting engineering charge structure for simulation testing, thereby realizing the visualization of the detonation process and accurately measuring and calculating the generated rock cuttings data.

[0007] This application is implemented as follows: This application provides a device for testing the transparency of the borehole detonation process, comprising: The blockage collection box has an internal collection chamber, a collection hole at one end of the blockage collection box that communicates with the collection chamber, and a transparent first observation window on one side of the blockage collection box. The detonation device includes a connecting pipe, a metal sleeve, and a sealing flange that are detachably connected in sequence. The end of the connecting pipe away from the metal sleeve extends into a collection hole. The metal sleeve has a receiving cavity inside, which is used to hold at least one cylindrical rock sample arranged in sequence along its length. The rock sample has blast holes that penetrate both ends of it, and the blast holes are used to hold explosives. The outer wall of the metal sleeve has a transparent second observation window. The first camera is used to acquire images of the cavity through the first observation window; The second camera is used to acquire images of the cavity through the second observation window.

[0008] In some alternative implementations, the outer wall of the metal sleeve is provided with a plurality of side detection holes penetrating its inner wall, and each side detection hole contains a side pressure sensor.

[0009] In some alternative implementations, the sealing flange has multiple end detection holes communicating with the receiving cavity, each end detection hole containing an end pressure sensor.

[0010] In some alternative implementations, multiple strain gauges are also included, with multiple strain gauges connected to the outer wall of the rock sample and the inner wall of the borehole, respectively.

[0011] In some alternative implementations, when the cavity contains two or more rock samples, multiple strain gauges are provided between the end faces of two adjacent rock samples.

[0012] In some optional embodiments, a rubber sleeve is also included, which is fitted onto the outer wall of the rock sample. The outer wall of the rubber sleeve and the inner wall of the metal sleeve form an annular confining cavity. The outer wall of the metal sleeve is provided with at least one inlet and at least one outlet communicating with the confining cavity.

[0013] This application also provides a method for testing burst pressure, which is performed using the aforementioned transparent testing device for borehole detonation process, and includes the following steps: The explosive charge is placed in the boreholes penetrating both ends of the rock sample, and at least one cylindrical rock sample is placed in the receiving cavity of the metal sleeve. The explosive charge in the blast hole detonates the rock sample, causing the shock wave and explosive gas generated by the blast to pass through the connecting pipe and enter the collection chamber in the blockage collection box; The first and second cameras were used to acquire images of the collection cavity and the containment cavity, respectively. The punching velocity, velocity field, geometric and mass parameters, kinetic energy, and total splash kinetic energy of the rock cuttings are calculated based on the images acquired by the first camera. The total pressure field, shock wave pressure field, and explosion gas pressure field are calculated based on images acquired by the second camera.

[0014] In some alternative implementations, the pixel displacement of the rock cutting particles in two consecutive frames of images acquired by the first camera is converted into actual displacement, and the actual displacement is removed to obtain the punching speed of the rock cutting particles by the time interval between the two consecutive frames.

[0015] In some alternative implementations, calculating the velocity field of rock cuttings based on images acquired by the first camera includes the following steps: With the center of the borehole as the origin, and with the radial and longitudinal directions of the borehole as... x shaft and y Establish a coordinate system based on axes, and define the window in two consecutive frames of images. and The grayscale distributions are respectively and Establish normalized cross-correlation function : The displacement vector is determined by fitting subpixel peak values. Obtain the velocity field.

[0016] In some alternative implementations, calculating the geometric and mass parameters of rock cuttings based on images acquired by the first camera includes the following steps: The image sequence is binarized and contours are extracted to obtain the number of pixels of each splashed rock fragment and convert it into the actual projected area. Assuming the ejected rock fragments are spherical, the mass of a single ejected rock fragment is calculated by combining the actual projected area of ​​the ejected rock fragments.

[0017] In some alternative implementations, the number of splashed rock fragments is obtained from images acquired by the first camera, and the kinetic energy of the rock fragments and the total splash kinetic energy of the entire field are calculated by combining the mass of a single splashed rock fragment and the punching speed of the rock fragment.

[0018] In some alternative implementations, calculating the total pressure field based on images acquired by the second camera includes the following steps: With the center of the borehole as the origin, and with the radial and longitudinal directions of the borehole as... x shaft and y A coordinate system is established along the axis, and the grayscale change value and light intensity distribution of each pixel at different times during the detonation process are obtained based on the images of the cavity acquired by the second camera. Convert grayscale change values ​​into deflection angles; The deflection angle is converted into a density gradient using the Gladstone-Dale relation: Spatial numerical integration of the density gradient field reconstructs the density field of the detonation process: The total pressure field is obtained by inversion using the ideal gas law.

[0019] In some alternative implementations, calculating the shock wave pressure field and the explosion gas pressure field based on images acquired by the second camera includes the following steps: The wavefront position is extracted from the images acquired by the second camera, and the radial spread velocity of the wavefront is calculated. Constructing the spatiotemporal mask function: The total pressure field of the explosive gas is calculated from the density field of the explosive gas. The total pressure field of the explosive gas is then divided into shock wave pressure field and explosive gas pressure using a mask function space.

[0020] In some alternative implementations, calculating the explosion gas pressure based on images acquired by the second camera includes the following steps: Under the axisymmetric assumption, the radial density distribution of air at a certain axial position of the borehole is obtained by reconstructing the density field of the detonation process. For the shock wave region, the density at the shock wave front is extracted from the radial density distribution of air at a certain axial position of the borehole, and the shock wave density jump is calculated. The shock wave pressure was calculated by incorporating the shock wave density jump into the Rankine-Hugoniot relation. For the explosive gas region, the density of the explosive gas region is extracted from the radial density distribution of air at a certain axial position of the borehole, and the relative specific volume is calculated; The pressure of the explosion gas was calculated based on the relative specific volume and the JWL equation of state.

[0021] In some alternative implementations, the following steps are also included: A unified time coordinate system is established with the detonation moment as the zero point. The chemical energy of the explosive is calculated based on the linear density of the explosive charge, the charge length, and the heat of explosion. Calculate the kinetic energy of the explosive gas based on the mass of the punched material and the punching velocity of the rock cuttings: The total strain energy of the rock mass is calculated based on the number of strain gauges installed on the outer wall of the rock sample and the inner wall of the borehole, the strain energy density detected by each strain gauge, and the volume of the rock sample. According to Bond's power index, the first i The mass of the particle size range and the corresponding particle size are used to calculate the rock mass fracturing energy.

[0022] The beneficial effects of this application are as follows: The transparent testing device for the borehole detonation process provided by this application includes a blockage collection box with an internal collection cavity, a detonation device, a first camera, and a second camera. One end of the blockage collection box has a collection hole communicating with the collection cavity, and one side of the blockage collection box has a transparent first observation window. The detonation device includes a connecting pipe, a metal sleeve, and a sealing flange that are detachably connected in sequence. The end of the connecting pipe away from the metal sleeve extends into the collection hole. The metal sleeve has a receiving cavity inside, which is used to hold at least one cylindrical rock sample arranged sequentially along its length. The rock sample has boreholes penetrating both ends, and the boreholes are used to hold explosives. The outer wall of the metal sleeve has a transparent second observation window. The first camera is used to acquire images inside the collection cavity through the first observation window; the second camera is used to acquire images inside the receiving cavity through the second observation window. The transparent testing device and method for the borehole detonation process provided by this application can simulate the actual blasting engineering charge structure for simulation testing, thereby realizing visualization of the detonation process and accurately measuring and calculating the generated rock cuttings data. Attached Figure Description

[0023] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0024] Figure 1 This is a schematic diagram of the structure of the test device for making the borehole detonation process transparent, provided in an embodiment of this application. Figure 2 This is a partial cross-sectional view of the transparent testing device for borehole detonation process provided in an embodiment of this application.

[0025] In the diagram: 100, Blockage collection box; 110, Collection chamber; 120, Collection hole; 130, First observation window; 200, Detonation device; 210, Connecting pipe; 220, Metal sleeve; 221, Receiving cavity; 230, Sealing flange; 231, Reaction device; 240, Second observation window; 250, Side detection hole; 260, Side pressure sensor; 270, End detection hole; 280, End pressure sensor; 290, Strain gauge; 300, First camera; 400, Second camera; 500, Rubber sleeve; 510, Confining pressure cavity; 520, Liquid inlet; 530, Liquid outlet; 600, Rock sample; 610, Blast hole. Detailed Implementation

[0026] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. The components of the embodiments of this application described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0027] Therefore, the following detailed description of the embodiments of this application provided in the accompanying drawings is not intended to limit the scope of the claimed application, but merely to illustrate selected embodiments of the application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

[0028] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0029] In the description of this application, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product of this application is in use. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on this application. In addition, the terms "first," "second," and "third," etc., are only used to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0030] Furthermore, terms such as "horizontal," "vertical," and "sag" do not imply that components must be absolutely horizontal or suspended, but rather that they can be slightly tilted. For example, "horizontal" simply means that its direction is more horizontal relative to "vertical," and does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0031] In the description of this application, it should also be noted that, unless otherwise expressly specified and limited, the terms "set up," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0032] In this application, unless otherwise expressly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature being directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature being directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0033] The features and performance of the hole detonation process transparency testing device and testing method of this application are further described in detail below with reference to the embodiments.

[0034] like Figure 1 and Figure 2 As shown, this application provides a transparent testing device for the detonation process of a borehole, which includes a blockage collection box 100 with an internal collection chamber 110, a detonation device 200, a first camera 300 and a second camera 400: wherein, one end of the blockage collection box 100 is provided with a collection hole 120 communicating with the collection chamber 110, and a transparent first observation window 130 is provided on one side of the blockage collection box 100; The detonation device 200 includes a connecting pipe 210, a metal sleeve 220, and a sealing flange 230, which are detachably connected in sequence by bolts. The end of the connecting pipe 210 away from the metal sleeve 220 extends into a collection hole 120. The sealing flange 230 closes the end of the metal sleeve 220 away from the connecting pipe 210. An annular reaction device 231 is connected to the end of the sealing flange 230 away from the metal sleeve 220. The metal sleeve 220 has a cylindrical receiving cavity 221 inside, which is used to receive one or more cylindrical rock samples 600 arranged sequentially along its length. Each rock sample 600 has a borehole 610 penetrating both ends, which is used to contain explosives. A rubber sleeve 500 is fitted over the outer wall of the rock sample 600, and the outer wall of the rubber sleeve 500 and the inner wall of the metal sleeve 220 enclose each other to form a... The annular confining pressure chamber 510 has two inlets 520 and two outlets 530 on the outer wall of the metal sleeve 220, both of which are connected to the confining pressure chamber 510. The outer wall of the metal sleeve 220 has an arc-shaped transparent second observation window 240. The outer wall of the metal sleeve 220 has side detection holes 250 arranged at intervals along its circumference, which penetrate the inner wall of the metal sleeve 220. Each side detection hole 250 contains a side pressure sensor 260. The sealing flange 230 has end detection holes 270 arranged at intervals along its circumference, which are connected to the receiving cavity 221. Each end detection hole 270 contains an end pressure sensor 280. The outer wall of the rock sample 600 and the inner wall of the borehole 610 are respectively connected to strain gauges 290 arranged at intervals. Optionally, when the accommodating cavity 221 accommodates two or more rock samples 600, strain gauges 290 are arranged at intervals between the end faces of two adjacent rock samples 600.

[0035] The first camera 300 and the second camera 400 are respectively aligned with the first observation window 130 and the second observation window 240. The first camera 300 is used to acquire images inside the collection cavity 110 through the first observation window 130; the second camera 400 is used to acquire images inside the receiving cavity 221 through the second observation window 240.

[0036] This application also provides a method for testing burst pressure, which is performed using the aforementioned transparent testing device for borehole detonation process, and includes the following steps: Step 1: Process a cylindrical rock sample 600. Open a blast hole 610 through both ends of the rock sample 600. Place strain gauges 290 on the inner and outer walls of the rock sample 600. Place explosives in the blast hole 610 inside the rock sample 600. After separating the connecting pipe 210 and the metal sleeve 220, remove the metal sleeve 220, sealing flange 230 and reaction device 231 connected in sequence. Place the rubber sleeve 500 in the receiving cavity 221 of the metal sleeve 220, so that the outer wall of the rubber sleeve 500 and the inner wall of the metal sleeve 220 form an annular confining pressure cavity 510. Place the rock sample 600 inside the rubber sleeve 500. Place the side pressure sensor 260 and the end pressure sensor in the corresponding side detection hole 250 and end detection hole 270, respectively. Connect the metal sleeve 220 and the connecting pipe 210 into a whole by bolts. Step 2: Detonate the explosive in the borehole 610 of the rock sample 600, so that the shock wave and explosive gas generated by the explosion pass through the connecting pipe 210 and enter the collection chamber 110 in the blockage collection box 100. Step 3: Use the first camera 300 and the second camera 400 to acquire images of the collection cavity 110 and the receiving cavity 221, respectively; Step 4: Calculate the punching velocity, velocity field, geometric and mass parameters, kinetic energy, and total splash kinetic energy of the rock cuttings based on the images acquired by the first camera 300. Specifically, firstly, taking the center of borehole 610 as the origin, and taking the radial and longitudinal directions of borehole 610 as... x shaft and y A coordinate system is established along the axes. Based on the images acquired by the first camera (300), the pixel displacement of the rock cutting particles in two consecutive frames is obtained and converted into actual positions using calibration coefficients. The time interval is then removed to calculate the punching velocity of the rock cutting particles. : ; In the formula, The punching speed is in m / s; The calibration coefficients are obtained through calibration. and The centroid pixel coordinates of the same rock debris particle in two consecutive frames of images; The frame interval, in μs, is determined by the first camera's frame rate of 300 frames per second.

[0037] Calibration coefficient The method for obtaining the data is as follows: a background scale plate is set outside the first observation window 130. The background scale plate uses black and white stripes with a stripe width of 10mm as the displacement calibration reference. The calibration coefficient is determined in advance by placing a calibration plate of known size on the background scale plate.

[0038] Calculating the velocity field of rock debris particles based on images acquired by the first camera 300 includes the following steps: Suppose a window in two consecutive frames of images and The grayscale distributions are respectively and Establish a normalized cross-correlation function :

[0039] In the formula, and These are the grayscale values ​​of corresponding pixels in the two frames, obtained from the captured images; and windows respectively and Average gray level; and The windows are respectively in and Number of pixels in the direction; The pixel displacement vector is determined by the peak position of the normalized cross-correlation function, and the peak position with integer pixel precision is obtained through the Particle Image Velocity (PIV) cross-correlation algorithm. The corresponding normalized cross-correlation function The displacement vector is determined by fitting the maximum value at integer pixels using sub-pixel peak fitting (three-point Gaussian fitting). At the measured integer pixel peak point On the two pixels to its left and right (a total of three points), for The distribution is fitted with a three-point Gaussian curve. Because... The curve approximately follows a Gaussian distribution near its peak. By fitting the positions of the extreme points of the curve, the displacement accuracy can be improved from integer pixels to sub-pixel level, thus obtaining the displacement vector. Thus, the velocity field is obtained: ; In the formula, The velocity field vector is in m / s; The calibration coefficients are obtained through calibration. The pixel displacement vector is determined by the normalized cross-correlation algorithm; The frame interval, in μs, is determined by the first camera's frame rate of 300 frames per second.

[0040] The calculation of the geometric and mass parameters of rock cuttings based on images acquired by the first camera 300 includes the following steps: The image sequence was binarized and contour extracted to obtain the number of pixels for each splashed rock fragment. Convert to actual projected area: ; In the formula, For the first k The actual projected area of ​​each particle, in mm 2 ; A K For the first k The number of pixels per particle is extracted by an image processing algorithm; The calibration coefficients are obtained through calibration. Assuming the ejected rock fragments are spherical, then: ; In the formula, d K The equivalent diameter is in mm. V K For equivalent volume, mm 3 ; The actual projected area is in mm. 2 ; Mass of a single splashed rock fragment m K Calculate using the following formula: ; In the formula, m K The mass of a single splashed rock fragment, in grams; Density of rock sample (g / cm³) 3 Preliminary measurements were taken; V K For equivalent volume, mm 3 .

[0041] Based on the images acquired by the first camera 300, the kinetic energy of the rock fragments and the total splash kinetic energy of the entire field are calculated using the following formula: ; ; In the formula, E k For the first k The kinetic energy of each particle, J; E total For the total splash kinetic energy of the entire field, J; The total number of identified splashed rock fragments was obtained by an image processing algorithm. m k For the first k Mass of each particle, g; The punching speed is in m / s; V k For the first k The velocity of each particle is m / s. V k The velocity field obtained by fitting subpixel peaks Velocity value at the particle's center of mass: ; In the formula, For the first The centroid coordinates of each particle; , These represent the horizontal and vertical components of the velocity field.

[0042] Calculate the kinetic energy density distribution function : ; In the formula, Let J / mm be the kinetic energy density distribution function. 3 ; It is a collection of particles within a spatial grid cell, determined by the spatial grid division; Mesh cell volume (mm) 3 The size is determined by the grid size setting; For the first k The kinetic energy of a particle, J.

[0043] Step 5: Calculate the total pressure field, shock wave pressure field, and explosion gas pressure field based on the images acquired by the second camera 400.

[0044] Calculating the total pressure field based on images acquired by the second camera 400 includes the following steps: The grayscale changes of each pixel at different times during the detonation process are obtained by acquiring images of the cavity 221 from the second camera 400. and light intensity distribution ; Based on the blade cutoff relationship, convert the grayscale change value into a deflection angle: ; In the formula, for Location at The deflection angle at any moment; for Location at The grayscale change value at any given time is dimensionless. To achieve uniform background light intensity; The cutting edge height is in mm, representing the position of the cutting edge relative to the focal point of the undeflected ray. This is the knife-edge cutoff function; Light travels in a straight line in a homogeneous medium. When light passes through a region of density gradient in the detonation gas, it is bent and deflected due to the change in the gas's refractive index with density (Gladstone-Dale relation). The deflection angle describes the angle by which light deviates from its original direction of propagation. In a schlieren system, These are the image plane coordinates (corresponding to the observation plane position in physical space). This is a high-speed photography moment. The larger the value, the more intense the gas density gradient at that location and time, which usually corresponds to the shock wave front or a region of strong turbulence.

[0045] In a schlieren system, parallel light emitted from a light source is focused by a lens, and a blade-like edge (such as the edge of a razor blade) is placed at the focal point. Undeflected light rays converge at the focal point and are partially blocked by the blade; deflected light rays deviate from the focal point due to the change in angle, and the degree of blocking changes, thus creating differences in brightness on the imaging screen. Defined as the vertical distance from the edge of the blade to the focal point of the undeflected ray, it determines the sensitivity of the system. The smaller the value, the more sensitive it is to minute deflections, but the smaller its dynamic range. The larger the value, the greater the dynamic range, but the lower the sensitivity.

[0046] knife-edge cutoff function This describes the quantitative relationship between the change in light intensity caused by the blade's obstruction and the angle of light refraction. For a straight-edged blade, Approximately a linear function: (Under small deflection angle conditions); for more complex blade shapes (such as graduated filters). Since it is a nonlinear function, its specific form needs to be determined through calibration experiments.

[0047] The deflection angle is converted into a density gradient using the Gladstone-Dale relation: ; In the formula, For density gradient, kg / m 4 ; ρ ref For reference density, kg / m³ 3 ; K GD m is the Gladstone-Dale constant. 3 / kg; The optical path length in the thickness direction of the second observation window 240 is m; Equivalent optical path considering refractive index: ; In the formula, The refractive index of the material (high-strength polycarbonate) for the second observation window 240; The second observation window has a geometric thickness of 240. In the Gladstone-Dale relationship's deflection angle formula, The effective length of light passing through the detonation gas region, i.e., the light propagation distance in the thickness direction of the second observation window 240, determines the cumulative effect of the deflection angle on the density gradient: the longer the optical path, the larger the deflection angle caused by the same density gradient, and the higher the system sensitivity.

[0048] Spatial numerical integration of the density gradient field reconstructs the density field of the detonation process: ; In the formula, C ( x , t ) is the integration constant, determined by the boundary conditions (such as the undisturbed region). ρ = ρ 0) Confirm; The total pressure field is obtained by inversion using the ideal gas law. : ; In the formula, To reconstruct the density field of the detonation process; The specific gas constant of the explosive gas is... ; Let K be the temperature field.

[0049] Temperature field An estimation can be made by assuming an isentropic expansion temperature relationship: ; In the formula, CJ surface temperature, K; CJ surface density, kg / m 3 ρ is the density of the expanded gas, kg / m³ 3 The density field of the reconstructed detonation process is given by the density field. ρ CJ The density of the detonation products at the detonation wave front is compared with the specific volume on the CJ surface. V CJ They are reciprocals of each other, that is... ρ CJ =1 / V CJ .

[0050] The CJ plane (Chapman-Jouguet plane) is the chemical reaction equilibrium plane behind the detonation wave front, representing the initial state of the detonation products. Specific volume (volume per unit mass, m³) of the detonation products on the CJ surface. 3 / kg). Density (mass per unit volume, kg / m³) of detonation products on the CJ surface 3 The two are reciprocals of each other: ; Temperature relationship in isentropic expansion middle, The expanded density ρ is normalized as a reference density and used to calculate the temperature change.

[0051] During detonation, two pressure fields with distinctly different physical mechanisms exist simultaneously: the shock wave pressure field and the generated gas pressure field. Shock wave pressure field Propagating at supersonic speeds, with an extremely thin wavefront; the pressure field of the explosive gas. It expands in a quasi-static expansion manner, and its propagation speed is much lower than that of a shock wave.

[0052] The calculation of the shock wave pressure field and the explosion gas pressure field based on the spatial segmentation method of mask function includes the following steps: Wavefront position is extracted from schlieren images acquired by the second camera 400. r(t) And calculate the radial spread velocity of the wavefront: ; In the formula, The radial propagation velocity of the wavefront is m / s; r(t) for t Radial position of the wavefront at time t, m; Let be the frame interval of the second camera, s; Constructing a spatiotemporal mask function : ; In the formula, The velocity threshold is in m / s. , The longitudinal wave velocity of the rock mass is given in m / s. Density field of explosive gas Calculate the total pressure field of the explosive gases The shock wave pressure field is obtained by dividing the space of the mask function. and the pressure of the explosive gas :

[0053] .

[0054] The independent inversion method based on physical equations for calculating the pressure of explosive gases includes the following steps: Under the assumption of axis symmetry, the axial position of borehole 610 is obtained from the density field of the reconstructed detonation process. Air radial density distribution at [location] ,in ; The radial-axial plane of the sleeve was photographed using a schlieren system. x - zDensity field of a plane ,in Radial coordinates, This refers to the axial coordinate. It represents a specific axial position of the borehole. The radial density distribution of air at a fixed location, i.e. ,extract radial coordinates The distribution curve reflects the radial density gradient of the detonation products at a specific axial depth, i.e., the radial density distribution of air. It is used to locate the shock wave front (density jump point) and identify the expansion region of the explosive gas (density gradient region).

[0055] For the shock wave region, from a certain axial position of borehole 610 Air radial density distribution at [location] Extracting the density at the shock wave front Calculate the density jump of the shock wave: ; In the formula, For shock wave density jump, kg / m 3 ; The density at the shock wave front is kg / m³. 3 ,Depend on At the wavefront position Extract from; Initial air density, kg / m³ 3 ; The shock wave pressure was calculated by substituting the shock wave density jump into the Rankine-Hugoniot relation: ; In the formula, The shock wave pressure is measured in MPa. Initial air density, kg / m³ 3 ; The longitudinal wave velocity of the rock mass is given in m / s. The adiabatic index is dimensionless. For the explosive gas zone, at a certain axial position of borehole 610 Air radial density distribution at [location] Density of the explosive gas region Calculate the relative volume: ; In the formula, It is a relative volume, dimensionless; The density of the explosive gas region is kg / m³. 3 ,Depend on In mask function Region extraction; Initial air density, kg / m³ 3； Calculate the explosion gas pressure based on the JWL equation of state: ; In the formula, The pressure of the explosive gas is MPa; A , B The pressure parameter is in MPa. R 1. R 2. ω is a dimensionless parameter; The internal energy per unit volume of the detonation products, in J / m³. 3 .

[0056] Step 6: Analyze the blast energy based on the data collected by strain gauge 290. 。

[0057] The time of detonation is taken as zero point. Establish a unified time coordinate system; The chemical energy of explosives is calculated using the following formula: ; In the formula, The chemical energy of the explosive, J; The linear density of the explosive charge, in g / m, is determined by weighing and measuring the length of the explosive charge. Let the length of the charge be m; The explosive heat of combustion is expressed in J / g, determined by referring to a table based on the type of explosive or by calorimetry experiments. Calculate the kinetic energy of the explosive gas : ; In the formula, The mass of the punched material, in kg, is determined by measuring the mass difference before and after the test in the blockage collection box 100. The punching speed is in m / s; Calculate the total strain energy of the rock mass: ; In the formula, The number of strain gauge detection points 290 are set on the outer wall of rock sample 600 and the inner wall of borehole 610; For the first The strain energy density measured at 290 detection points of each strain gauge, in J / m². 3 ; For the first The control volume represented by the 290 detection points of each strain gauge is m³. 3 The volume of the rock sample is determined by dividing it equally according to the number of test points; Calculate rock mass fracturing energy : ; In the formula, Bond's work index, J / kg, under confining pressure Modified under the action to ; The Bond work index at zero confining pressure, in J / k, is determined by looking up a table based on rock type or by Bond work index testing. The confining pressure influence coefficient is dimensionless. m i For the first i Mass of particle size range, kg; For the corresponding particle size, m; m i and Determined by sieving after the experiment.

[0058] Calculate the energy density of stress wave propagation : ; In the formula, Impact stress, MPa, measured by a PVDF piezoelectric thin film applied to the outer wall of rock sample 600. Density of rock, kg / m³ 3 ; The longitudinal wave velocity is given in m / s. Calculate the stress wave propagation energy based on the stress wave propagation energy density:

[0059] In the formula, For the effective cross-sectional area of ​​stress wave propagation, m 2 It is determined by the cross-sectional area of ​​the rock sample or the range of stress wave propagation. The duration of the stress wave is in seconds.

[0060] The borehole detonation process transparency testing device provided in this application embodiment collects detonation products by setting up a blockage collection box 100 with an internal collection cavity 110. A collection hole 120 communicating with the collection cavity 110 is provided at one end of the blockage collection box 100. A rock sample 600 is contained in a cavity 221 through a metal sleeve 220 in the detonation device 200. One end of the metal sleeve 220 is sealed with a sealing flange 230. A connecting pipe 210 connects the other end of the metal sleeve and the collection hole 120. This allows the shock wave and explosive gas generated after the explosive in the borehole 610 of the rock sample 600 are detonated to pass through the connecting pipe 210 and enter the collection cavity 110 in the blockage collection box 100 for collection. At the same time, a first camera 300 and a second camera 400 are used to detect the detonation products. The first observation window 130 on the blockage collection box 100 and the second observation window 240 on the metal sleeve 220 collect images of the collection chamber 110 and the receiving chamber 221. This allows the test personnel to calculate the punching velocity, velocity field, geometric and mass parameters, kinetic energy, total splash kinetic energy, total pressure field, shock wave pressure field, and explosive gas pressure field of the rock cuttings based on the collected images. At the same time, the test personnel can also calculate the chemical energy of the explosive, the kinetic energy of the explosive gas, the rock mass fragmentation energy, the stress wave propagation energy density, and the stress wave propagation energy based on the stress data detected by the strain gauges 290 installed on the outer wall of the rock sample 600 and the inner wall of the borehole 610. This allows for simulation testing of the actual explosive charge structure in blasting engineering, thereby visualizing the detonation process and accurately measuring and calculating the generated rock cuttings data.

[0061] The embodiments described above are some, but not all, of the embodiments of this application. The detailed description of the embodiments of this application is not intended to limit the scope of the claimed application, but merely to illustrate selected embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

Claims

1. A transparent testing device for the borehole detonation process, characterized in that, It includes: The blockage collection box has a collection chamber inside, a collection hole communicating with the collection chamber at one end, and a transparent first observation window on one side of the blockage collection box. The detonation device includes a connecting pipe, a metal sleeve, and a sealing flange that are detachably connected in sequence. The end of the connecting pipe away from the metal sleeve extends into the collection hole. The metal sleeve has a receiving cavity inside, which is used to receive at least one cylindrical rock sample arranged sequentially along its length. The rock sample has blast holes penetrating both ends of it, and the blast holes are used to contain explosives. The outer wall of the metal sleeve has a transparent second observation window. A first camera is used to acquire images of the collection cavity through the first observation window; A second camera is used to acquire images of the cavity through the second viewing window.

2. The transparent testing device for borehole detonation process according to claim 1, characterized in that, The outer wall of the metal sleeve is provided with a plurality of side detection holes penetrating its inner wall, and each side detection hole is provided with a side pressure sensor.

3. The transparent testing device for borehole detonation process according to claim 1, characterized in that, The sealing flange is provided with multiple end detection holes that communicate with the receiving cavity, and each end detection hole is provided with an end pressure sensor.

4. The transparent testing device for borehole detonation process according to claim 1, characterized in that, It also includes multiple strain gauges, with multiple strain gauges connected to the outer wall of the rock sample and the inner wall of the borehole, respectively.

5. The transparent testing device for borehole detonation process according to claim 4, characterized in that, When the accommodating cavity contains two or more rock samples, a plurality of strain gauges are provided between the end faces of two adjacent rock samples.

6. The transparent testing device for borehole detonation process according to claim 1, characterized in that, It also includes a rubber sleeve fitted onto the outer wall of the rock sample, wherein the outer wall of the rubber sleeve and the inner wall of the metal sleeve enclose an annular confining cavity, and the outer wall of the metal sleeve is provided with at least one inlet and at least one outlet communicating with the confining cavity.

7. A method for testing burst pressure, characterized in that, It is conducted using the hole detonation process transparency testing apparatus as described in any one of claims 1 to 6, and includes the following steps: The explosive charge is placed in the boreholes penetrating both ends of the rock sample, and at least one cylindrical rock sample is placed in the receiving cavity of the metal sleeve. The explosive charge in the borehole of the rock sample is detonated, and the shock wave and explosive gas generated by the explosion pass through the connecting pipe and enter the collection chamber in the blockage collection box. Images of the collection cavity and the receiving cavity are captured using a first camera and a second camera, respectively. The punching velocity, velocity field, geometric and mass parameters, kinetic energy, and total splash kinetic energy of the rock cuttings are calculated based on the images acquired by the first camera. The total pressure field, shock wave pressure field, and explosion gas pressure field are calculated based on the images acquired by the second camera.

8. The method for testing burst pressure according to claim 7, characterized in that, The pixel displacement of the rock cutting particles in two consecutive frames of images acquired by the first camera is converted into actual displacement. The actual displacement is removed and the punching speed of the rock cutting particles is obtained by taking the time interval between the two consecutive frames.

9. The method for testing burst pressure according to claim 7, characterized in that, Calculating the velocity field of rock debris particles based on images acquired by the first camera includes the following steps: With the center of the borehole as the origin, and with the radial and longitudinal directions of the borehole as... x shaft and y Establish a coordinate system based on axes, and define the window in two consecutive frames of images. and The grayscale distributions are respectively and Establish normalized cross-correlation function : The displacement vector is determined by fitting subpixel peak values. Obtain the velocity field.

10. The method for testing burst pressure according to claim 8, characterized in that, Calculating the geometric and mass parameters of rock cutting particles based on images acquired by the first camera includes the following steps: The image sequence is binarized and contours are extracted to obtain the number of pixels of each splashed rock fragment and convert it into the actual projected area. Assuming the ejected rock fragments are spherical, the mass of a single ejected rock fragment is calculated by combining the actual projected area of ​​the ejected rock fragments.

11. The method for testing burst pressure according to claim 10, characterized in that, The number of splashed rock fragments is obtained from the images captured by the first camera. The kinetic energy of the rock fragments and the total splash kinetic energy of the entire field are calculated by combining the mass of a single splashed rock fragment and the punching speed of the rock fragment.

12. The method for testing burst pressure according to claim 7, characterized in that, Calculating the total pressure field based on the images acquired by the second camera includes the following steps: With the center of the borehole as the origin, and with the radial and longitudinal directions of the borehole as... x shaft and y A coordinate system is established along the axis, and the grayscale change value and light intensity distribution of each pixel at different times during the detonation process are obtained based on the images of the cavity captured by the second camera. Convert grayscale change values ​​into deflection angles; The deflection angle is converted into a density gradient using the Gladstone-Dale relation: Spatial numerical integration of the density gradient field reconstructs the density field of the detonation process: The total pressure field is obtained by inversion using the ideal gas law.

13. The method for testing burst pressure according to claim 12, characterized in that, Calculating the shock wave pressure field and the explosion gas pressure field based on the images acquired by the second camera includes the following steps: The wavefront position is extracted and the radial spread velocity of the wavefront is calculated based on the image acquired by the second camera. Constructing the spatiotemporal mask function: The total pressure field of the explosive gas is calculated from the density field of the explosive gas. The total pressure field of the explosive gas is then divided into shock wave pressure field and explosive gas pressure using a mask function space.

14. The method for testing burst pressure according to claim 12, characterized in that, Calculating the explosion gas pressure based on images acquired by the second camera includes the following steps: Under the axisymmetric assumption, the radial density distribution of air at a certain axial position of the borehole is obtained by reconstructing the density field of the detonation process. For the shock wave region, the density at the shock wave front is extracted from the radial density distribution of air at a certain axial position of the borehole, and the shock wave density jump is calculated. The shock wave pressure was calculated by incorporating the shock wave density jump into the Rankine-Hugoniot relation. For the explosive gas region, the density of the explosive gas region is extracted from the radial density distribution of air at a certain axial position of the borehole, and the relative specific volume is calculated; The pressure of the explosion gas was calculated based on the relative specific volume and the JWL equation of state.

15. The method for testing burst pressure according to claim 8, characterized in that, It also includes the following steps: A unified time coordinate system is established with the detonation moment as the zero point. The chemical energy of the explosive is calculated based on the linear density of the explosive charge, the charge length, and the heat of explosion. Calculate the kinetic energy of the explosive gas based on the mass of the punched material and the punching velocity of the rock cuttings: The total strain energy of the rock mass is calculated based on the number of strain gauges installed on the outer wall of the rock sample and the inner wall of the borehole, the strain energy density detected by each strain gauge, and the volume of the rock sample. According to Bond's power index, the first i The mass of the particle size range and the corresponding particle size are used to calculate the rock mass fracturing energy.

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