Non-contact measuring device for three-dimensional blasting vibration response and surrounding rock state evaluation method

Abstract

The application discloses a three-dimensional blasting vibration response non-contact measuring device and a surrounding rock state evaluation method, and relates to the field of solid deformation measurement. The three-dimensional blasting vibration response non-contact measuring device and the surrounding rock state evaluation method use a single high-speed camera and a two-stage reflection structure to acquire images of each target point in a monitoring area when blasting operation is performed in a tunnel, simultaneously use an inertial sensing unit to collect vibration data of the high-speed camera, calculate real vibration displacement of each target point in a world coordinate system according to the images of each target point in the monitoring area acquired by the high-speed camera and the vibration data collected by the inertial sensing unit, further extract a wave velocity field of the monitoring area, calculate a wave velocity reduction rate, and evaluate the surrounding rock state of the monitoring area according to the wave velocity reduction rate. The three-dimensional blasting vibration response non-contact measuring device can realize non-contact measurement of the three-dimensional response of the tunnel blasting vibration by using a single high-speed camera, remove errors caused by the vibration of the high-speed camera itself on the evaluation result, and effectively improve the evaluation precision.

Description

Technical Field

[0001] This application relates to the field of measuring solid deformation, and more specifically, to a three-dimensional non-contact measuring device for blasting vibration response and a method for evaluating the condition of surrounding rock. Background Technology

[0002] In tunnel construction, the drill-and-blast method is widely used due to its adaptability and high efficiency. However, during the blasting process, the energy released instantaneously by the explosives propagates to the surrounding rock mass in the form of stress waves and explosive gases, easily causing vibration and damage to the surrounding rock. This negatively impacts the stability of the tunnel structure and the existing support system. Moreover, in complex geological conditions, blasting vibrations can induce safety hazards such as rockfall, loosening, and even local instability. Therefore, accurate monitoring and quantitative analysis of the vibration response generated during tunnel blasting are crucial for ensuring construction safety, optimizing blasting parameters, and improving construction quality.

[0003] Currently, tunnel blasting vibration monitoring mainly involves using contact-type devices such as velocity sensors, acceleration sensors, or vibration detectors deployed on the surface of the surrounding rock or support structure to obtain vibration velocity and acceleration parameters at single or a small number of measuring points. While this method is technically mature and widely used, it still has certain limitations: First, contact sensors typically only acquire local vibration information from a limited number of measuring points, making it difficult to reflect the overall spatial vibration distribution characteristics of the surrounding rock; second, sensors need to be fixed to the surface of the object being measured, making them susceptible to shock waves, flyrock, and dust in blasting environments, resulting in difficulties in deployment, high risk of damage, and low reusability.

[0004] With the development of high-speed imaging and digital image processing technologies, vision-based non-contact measurement methods are increasingly being applied to structural vibration and dynamic response testing. These methods analyze the motion characteristics of target points in a continuous image sequence to achieve non-contact acquisition of vibration displacement, thus avoiding the safety risks associated with direct sensor deployment. For tunnel blasting vibration, due to the extremely short blasting time, the vibration signal exhibits significant transient characteristics. To accurately capture the waveform and frequency characteristics of blasting vibration, the measurement system typically requires high temporal resolution. Engineering practice shows that to ensure vibration signal sampling accuracy and meet the requirements of blasting vibration frequency analysis, the sampling frequency of image acquisition equipment usually needs to reach above 10kHz. Therefore, vision measurement systems often require high-speed cameras capable of capturing tens of thousands of frames per second or higher. However, the cost of such high-performance high-speed cameras is far higher than that of conventional industrial high-speed cameras.

[0005] When using binocular or multi-view vision systems to acquire three-dimensional vibration information, two or more high-speed cameras are required, along with a precise time synchronization control module, which significantly increases the overall hardware cost of the system. Furthermore, multi-high-speed camera systems have complex structures and require high levels of installation space, equipment stability, and high-speed camera synchronization accuracy. They are also susceptible to vibration disturbances in tunnel blasting environments, leading to decreased system stability and increased engineering difficulty.

[0006] Therefore, there is a need for a device and method that can achieve three-dimensional detection accuracy of blasting vibration while reducing the number of high-speed cameras, system complexity, and equipment cost, in order to solve the above problems. Summary of the Invention

[0007] The purpose of this application is to provide a three-dimensional blasting vibration response non-contact measurement device and a surrounding rock condition evaluation method, which can realize non-contact measurement of the three-dimensional blasting vibration response and surrounding rock condition evaluation of a tunnel using a single high-speed camera, and eliminate the error caused by the vibration of the high-speed camera itself on the evaluation results, thereby improving the evaluation accuracy.

[0008] This application is implemented as follows: This application provides a three-dimensional non-contact measurement device for blasting vibration response. High-speed cameras are used to acquire images; A pair of outer mirrors are positioned on either side of the optical axis of the high-speed camera to reflect light. A pair of inner reflectors are positioned between two outer reflectors and opposite to the high-speed camera to reflect the light reflected by the two outer reflectors into the lens of the high-speed camera. An inertial sensing unit is connected to a high-speed camera to collect vibration data from the high-speed camera. The synchronous trigger module is electrically connected to both the high-speed camera and the inertial sensing unit, and is used to control the inertial sensing unit to collect vibration data of the high-speed camera when the high-speed camera is acquiring images.

[0009] In some alternative implementations, a rotary motor is also included for driving each outer mirror to rotate about a vertical axis.

[0010] In some alternative implementations, at least one illumination lamp is also included to provide light to illuminate the area under test, causing the light emitted from the area under test to be reflected by two outer reflectors.

[0011] This application also provides a method for evaluating the state of surrounding rock, which includes the following steps: Geometric calibration was performed on the aforementioned three-dimensional non-contact measurement device for blasting vibration response; Blasting operations are carried out inside the tunnel. The high-speed camera in the three-dimensional blasting vibration response non-contact measurement device acquires images of each target point in the monitoring area, and the vibration data of the high-speed camera is collected simultaneously using the inertial sensing unit. The true vibration displacement of each target point in the world coordinate system after removing the vibration error of the high-speed camera is calculated based on the images of each target point in the monitoring area acquired by the high-speed camera and the vibration data collected by the inertial sensing unit. The wave velocity field of the monitoring area is extracted based on the actual vibration displacement of each target point in the world coordinate system after removing the vibration error of the high-speed camera. The wave velocity and wave velocity reduction rate of the rock mass were calculated based on the wave velocity field of the monitored area. The surrounding rock condition of the monitoring area is evaluated based on the wave velocity reduction rate.

[0012] In some optional implementations, the geometric calibration of the three-dimensional blasting vibration response non-contact measurement device includes the following steps: acquiring the rotation matrix of the physical coordinate system of the high-speed camera and the inertial sensing unit, as well as the intrinsic parameter matrix of the high-speed camera; simultaneously acquiring the distance between the rotation axes of the two outer reflectors, the distance between the inner reflector and the optical center of the high-speed camera, the rotation angle of the outer reflectors, and the raw data of the inertial sensing unit in the static state of the high-speed camera before blasting; and calculating the zero bias of the accelerometer and the zero bias of the gyroscope to complete the zero bias compensation of the inertial sensing unit.

[0013] In some alternative implementations, the intrinsic parameter matrix of the high-speed camera includes focal length, principal point position, and pixel size.

[0014] In some optional implementations, calculating the true vibration displacement of each target point in the world coordinate system after removing the vibration error of the high-speed camera, based on images of each target point in the monitoring area acquired by the high-speed camera and vibration data collected by the inertial sensing unit, includes the following steps: The images of each target point in the monitoring area acquired by the high-speed camera are converted into images of an equivalent virtual high-speed camera formed behind two outer mirrors. The optical axis of the two equivalent virtual high-speed camera images is corrected to make the optical axes of the two virtual high-speed cameras parallel. The imaging posture is the same as that of the two equivalent virtual high-speed camera images. The vibration displacement of each target point in the monitoring area is calculated based on the images after optical axis correction and rotation correction of two equivalent virtual high-speed cameras. The vibration displacement of each target point in the monitoring area is corrected based on the vibration data collected by the inertial sensing unit, so as to obtain the true vibration displacement of each target point in the monitoring area after removing the vibration error of the high-speed camera.

[0015] In some alternative implementations, optical axis correction of the images from two equivalent virtual high-speed cameras to make the optical axes of the two virtual high-speed cameras parallel includes the following steps: The rotation matrix and translation vector between the two virtual high-speed cameras are calculated based on the geometric calibration parameters of the three-dimensional blasting vibration response non-contact measurement device. The baseline unit direction vector is obtained by normalizing the translation vector; The virtual baseline direction is consistent with the x-axis of the coordinate system established by the left virtual high-speed camera. This direction is selected as the x-axis direction of the correction coordinate system. The optical axis directions of the left and right virtual high-speed cameras are obtained with the left virtual high-speed camera coordinate system as the reference coordinate system. The optical axis directions of the left and right virtual high-speed cameras are weighted and averaged, and then normalized to construct the initial optical axis directions for binocular imaging with parallel optical axes. Make the calibration intrinsic parameter matrix consistent with the original intrinsic parameter matrix, and construct the y-axis direction and the final optical axis direction of the calibration coordinate system according to the orthogonal constraint relationship; The rotation correction matrices for the left and right virtual high-speed cameras are constructed based on the x-axis, y-axis, and z-axis directions of the correction coordinate system.

[0016] In some alternative implementations, rotating the images of two equivalent virtual high-speed cameras to make their imaging poses the same includes the following steps: making the corrected equivalent intrinsic parameter matrix consistent with the original intrinsic parameter matrix to obtain the corresponding corrected projection matrix and the corrected mapping matrix of the left and right images, and performing mapping correction on the images of the two equivalent virtual high-speed cameras.

[0017] In some optional implementations, calculating the vibration displacement of each target point in the monitoring area based on the images after optical axis correction and rotation correction from two equivalent virtual high-speed cameras includes the following steps: Calculate the horizontal disparity of the corresponding target point in the images corrected by two equivalent virtual high-speed cameras; Calculate the depth information of the target point based on the principle of parallel binocular geometric measurement; Calculate the three-dimensional coordinates of the target point in a virtual high-speed camera coordinate system and convert them into the three-dimensional coordinates of the target point in the world coordinate system; The vibration displacement of the target point in the adjacent frames in the world coordinate system is calculated by the coordinate difference between the acquired adjacent frames.

[0018] In some alternative implementations, correcting the vibration displacement of each target point in the monitoring area based on the vibration data collected by the inertial sensing unit includes the following steps: The original angular velocity and linear acceleration collected by the inertial sensing unit are compensated to obtain the effective linear acceleration and effective angular velocity of the inertial sensing unit. The self-vibration linear acceleration of the high-speed camera in the world coordinate system is integrated twice, and time synchronization is performed according to the frame interval of the high-speed camera to obtain the self-vibration displacement of the high-speed camera in the world coordinate system in adjacent frames. The true vibration displacement of the target point is calculated based on the vibration displacement of the target point in the world coordinate system in adjacent frames and the self-vibration displacement of the high-speed camera in the world coordinate system in adjacent frames.

[0019] In some alternative implementations, the wave velocity field of the monitoring area is extracted based on the actual vibration displacement of each target point in the world coordinate system after removing the vibration error of the high-speed camera, including the following steps: Based on the actual vibration displacement of each target point in the monitoring area, the actual vibration velocity and vibration time sequence of each target point in the world coordinate system are calculated, and the time when the blast wave arrives at each target point is calculated. Construct a regularized inversion objective function, update the increment and model parameters, and perform inversion; When the iteration stops when the convergence condition is met, a continuous arrival time field is obtained. The slowness field is obtained by calculating the spatial gradient of the arrival time field. The wave velocity field of the monitoring area is calculated based on the relationship between slowness and wave velocity.

[0020] In some optional implementation schemes, when evaluating the surrounding rock properties of the monitoring area based on the wave velocity reduction rate, the surrounding rock conditions are judged as intact, slightly damaged, moderately fractured, and strongly fractured when the wave velocity reduction rate is <5%, 5%-15%, 15%-30%, and >30%, respectively.

[0021] The beneficial effects of this application are as follows: The three-dimensional blasting vibration response non-contact measurement device and surrounding rock condition evaluation method provided by this application acquire images of each target point in the monitoring area using a single high-speed camera during blasting operations in the tunnel. Simultaneously, an inertial sensing unit collects vibration data from the high-speed camera. Based on the images of each target point in the monitoring area acquired by the high-speed camera and the vibration data collected by the inertial sensing unit, the true vibration displacement of each target point in the world coordinate system after removing the vibration error of the high-speed camera is calculated. Then, the wave velocity field of the monitoring area is extracted and the wave velocity reduction rate is calculated. Based on the wave velocity reduction rate, the surrounding rock condition of the monitoring area is evaluated. This method can achieve non-contact measurement of the three-dimensional blasting vibration response and surrounding rock condition evaluation in tunnels using a single high-speed camera, and removes the error caused by the vibration of the high-speed camera itself, effectively improving the evaluation accuracy. Attached Figure Description

[0022] 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.

[0023] Figure 1A schematic flowchart illustrating the surrounding rock condition evaluation method provided in this application embodiment; Figure 2 A schematic diagram of a three-dimensional blasting vibration response non-contact measurement device installed in a tunnel for blasting tests in the surrounding rock condition evaluation method provided in this application embodiment; Figure 3 This is a schematic diagram of the structure of the three-dimensional non-contact measurement device for blasting vibration response in the surrounding rock condition evaluation method provided in this application embodiment; Figure 4 This is a schematic diagram illustrating how the images of each target point in the monitoring area acquired by the high-speed camera are converted into images of an equivalent virtual high-speed camera formed behind two outer reflectors in the surrounding rock condition evaluation method provided in this application embodiment. Figure 5 This is a schematic diagram illustrating the conversion of images from two equivalent virtual high-speed cameras into a traditional optical axis parallel binocular system to obtain depth information of monitoring points in the surrounding rock condition evaluation method provided in this application embodiment.

[0024] In the diagram: 100, high-speed camera; 110, outer reflector; 120, inner reflector; 130, inertial sensing unit; 140, synchronous trigger module; 150, rotary motor; 160, illumination lamp; 200, tunnel; 210, target point. Detailed Implementation

[0025] 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.

[0026] 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.

[0027] 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.

[0028] 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.

[0029] 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.

[0030] 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.

[0031] 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.

[0032] The following detailed description of the features and performance of the three-dimensional blasting vibration response non-contact measurement device and surrounding rock condition evaluation method of this application, in conjunction with embodiments, provides further insight into their specifics.

[0033] like Figure 3As shown in the figure, this application provides a three-dimensional non-contact measurement device for blasting vibration response, which includes a high-speed camera 100, a pair of symmetrically arranged outer reflectors 110, a pair of symmetrically arranged inner reflectors 120, an illumination lamp 160, an inertial sensing unit 130 fixedly connected to the high-speed camera 100, and a synchronization triggering module 140 electrically connected to the high-speed camera 100 and the inertial sensing unit 130 respectively. The high-speed camera 100 is a high-speed camera used to be fixedly installed in front of the monitoring area of ​​the tunnel. The optical axis of the lens of the high-speed camera 100 is approximately pointed towards the area to be measured for synchronously acquiring multi-view imaging information of the area after reflection. A pair of outer reflectors 110 are respectively disposed on both sides of the optical axis of the high-speed camera 100. A rotary motor 150 is connected to the bottom of each outer reflector 110. The rotary motor 150 drives the mirror surface of the outer reflector 110 to rotate around the vertical axis, and its rotation angle is used to control the relationship between the baseline length and rotation angle between the equivalent viewing angles. A pair of inner reflectors 120 are fixedly installed between the two outer reflectors 110 and arranged opposite to the high-speed camera 100. The pair of inner reflectors 120 are used to perform secondary reflection of the light rays deflected by the two outer reflectors 110, and guide light rays from different directions into the lens of the same high-speed camera 100. Through the two-stage reflection structure of the pair of outer reflectors 110 and the pair of inner reflectors 120, light rays from the same target point can form left and right equivalent viewing angle images respectively, and present them as left and right partitioned real image information in the same frame. This constructs an equivalent dual-view imaging system without increasing the number of high-speed cameras 100, providing a data foundation for subsequent three-dimensional vibration displacement inversion. The inertial sensing unit 130 is fixedly connected to the high-speed camera 100 and is used to collect the vibration data of the high-speed camera 100 itself during the blasting process. The synchronization trigger module 140 is electrically connected to both the high-speed camera 100 and the inertial sensing unit 130 to synchronize their data acquisition. When the high-speed camera 100 is acquiring images, it controls the inertial sensing unit 130 to synchronously acquire the vibration data of the high-speed camera 100. The illumination lamp 160 is used to provide light to illuminate the area to be measured, so that the light emitted from the area to be measured is reflected by the two outer reflectors 110 to the two inner reflectors 120 for secondary reflection and guided into the lens of the high-speed camera 100.

[0034] like Figure 1 , Figure 2 , Figure 3 , Figure 4 , Figure 5 As shown in the figure, this application embodiment also provides a method for evaluating the surrounding rock condition, which is implemented using the above-mentioned three-dimensional blasting vibration response non-contact measurement device, and includes the following steps: Step 1: Perform geometric calibration on the three-dimensional blasting vibration response non-contact measurement device; specifically, obtain the rotation matrix of the physical coordinate system of the high-speed camera 100 and the inertial sensing unit 130. And the intrinsic parameter matrix of the high-speed camera 100 The intrinsic parameter matrix of the high-speed camera 100 includes focal length. The principal point position and pixel size are obtained, and the distance between the rotation axes of the two outer reflectors 110 is also obtained. The distance between the inner reflector 120 and the optical center of the high-speed camera 100 The rotation angle of the outer reflector 110 In addition to the raw data from the inertial sensing unit 130 of the high-speed camera 100 in a stationary state before the explosion, the accelerometer zero bias is calculated based on the raw data from the inertial sensing unit 130 of the high-speed camera 100 in a stationary state before the explosion. and gyroscope zero bias Complete the zero-bias compensation of the inertial sensing unit 130.

[0035] Step Two, as follows Figure 2 As shown, blasting operations are carried out in tunnel 200. The high-speed camera 100 in the three-dimensional blasting vibration response non-contact measurement device acquires images of each target point 210 in the monitoring area, and the vibration data of the high-speed camera 100 is collected simultaneously by the inertial sensing unit 130. Step 3: Calculate the actual vibration displacement of each target point in the world coordinate system based on the images of each target point in the monitoring area acquired by the high-speed camera 100 and the vibration data collected by the inertial sensing unit 130. 3.1 The images of each target point in the monitoring area acquired by the high-speed camera 100 are converted into images of an equivalent virtual high-speed camera formed behind the two outer reflectors 110. The optical axis of the two equivalent virtual high-speed camera images is corrected to make the optical axes of the two virtual high-speed cameras parallel. The rotation of the two equivalent virtual high-speed camera images is corrected to make the imaging posture the same. Since a single high-speed camera 100 cannot acquire depth direction information of the target point, while dual high-speed cameras acquire depth direction information, during the two-stage reflection imaging process, based on the symmetry principle of plane mirror imaging, the actual high-speed camera 100... Spatially equivalent to two virtual high-speed cameras (Left virtual high-speed camera) and (Right virtual high-speed camera). For example... Figure 4 As shown, since the optical axes of the two equivalent virtual high-speed cameras are not parallel, traditional binocular depth calculation methods are not suitable. Therefore, it is necessary to perform optical axis correction processing on the equivalent viewpoint imaging information of the left and right virtual high-speed cameras to facilitate depth calculation. Figure 5 Depth information is calculated under the condition that the optical axes of two virtual high-speed cameras are parallel.

[0036] Specifically, performing optical axis correction on the images of two equivalent virtual high-speed cameras to make their optical axes parallel includes the following steps: Intrinsic parameter matrices of left and right virtual high-speed cameras satisfy: ; Using the left virtual high-speed camera as a reference, combined with the rotation matrix between the left and right virtual high-speed cameras... Translation vector The spatial relationship between the right virtual high-speed camera and the left virtual high-speed camera can be represented as: ; In the formula, and These represent the coordinate vectors of the same point in space in the left and right virtual high-speed camera coordinate systems, respectively, combined with the appendix. Figure 4 Rotation matrix Translation vector for: ; ; In the formula, The rotation angle of the outer reflector. The distance between the optical centers of the left and right virtual high-speed cameras satisfies: ; In the formula, The distance between the rotation axes of the left and right outer reflectors 110. The relative positional relationship between the inner reflector 120 and the optical center of the real high-speed camera 100.

[0037] For translation vector Normalization is performed to obtain the baseline unit direction vector. : ; The virtual baseline direction is aligned with the x-axis of the left virtual high-speed camera coordinate system. This direction is selected as the x-axis direction of the calibration coordinate system. The left virtual high-speed camera coordinate system is used as the reference coordinate system, and the optical axes of the left and right virtual high-speed cameras are... , They are respectively: ; Weighted averages are applied to the left and right optical axes, and then normalized to construct the initial optical axis directions of the calibration coordinate system. : ; It should be noted that optical axis correction essentially involves applying rotation and resampling mapping to two sub-images. To maintain dimensional consistency, this application keeps the focal length and pixel scale unchanged. Without cropping, the correction intrinsic parameter matrix can be directly made consistent with the original intrinsic parameter matrix. This process does not introduce scale error. Based on orthogonal constraints, the y-axis direction of the correction coordinate system is constructed. : ; The optical axis direction of the calibration coordinate system is further corrected as follows: ; Constructing the correction rotation matrix of the left virtual high-speed camera : ; Correspondingly, the correction rotation matrix for the right virtual high-speed camera is: By rotating and transforming, the left and right virtual high-speed cameras are made to have the same imaging posture under a unified calibration coordinate system, with their optical axes parallel to each other and their virtual baseline direction coinciding with the x-axis of the calibration coordinate system.

[0038] After constructing the correction rotation matrix, in order to build the corrected parallel binocular equivalent imaging model, it is necessary to determine the corrected equivalent intrinsic parameter matrix. .

[0039] In this application, considering that the left and right virtual high-speed cameras are obtained from the same high-speed camera imaging system through two-stage reflection, the correction process mainly introduces rotation and planar remapping, without changing the physical focal length and pixel size of the lens. To avoid geometric scale deviation caused by additional scaling, a strategy of keeping the focal length and pixel metric unchanged is adopted. The rotation correction of the images of the two equivalent virtual high-speed cameras to make the imaging pose the same includes the following steps: Let the corrected equivalent intrinsic parameter matrix Consistent with the original intrinsic parameter matrix, i.e.: ; The corresponding corrected projection matrix is: ; in, This is the corrected equivalent intrinsic parameter matrix. Represents the unit rotation matrix. This represents the virtual baseline length. Further, the correction mapping matrices for the left and right images are constructed. and : ; The original image is remapped based on the correction mapping matrix to obtain a corrected image in which the monitoring points satisfy the epipolar constraint relationship. 3.2. The vibration displacement of each target point in the monitoring area is calculated based on the corrected image; For the corrected image where the monitoring points satisfy the epipolar constraint relationship, calculate the horizontal disparity of corresponding monitoring points in the left and right images. The horizontal parallax d is: ; Target depth information is calculated based on the principle of parallel binocular geometric measurement. : ; In the formula, l Baseline length d For horizontal parallax, f It is the focal length.

[0040] Further obtain its three-dimensional coordinates in the left virtual high-speed camera coordinate system: ; in, These are the corrected equivalent intrinsic parameters. To ensure the measurement results are consistent with the engineering coordinate system, the three-dimensional coordinates in the high-speed camera coordinate system are further transformed to the world coordinate system. It should be noted that in this application, the world coordinate system is established with the horizontal direction to the right of the monitoring area as the x-axis, the vertical direction upward as the y-axis, and the direction perpendicular to the xy plane pointing towards the high-speed camera as the z-axis; the high-speed camera coordinate system is established with the horizontal side of the image pointing to the right as the x-axis, the vertical side downward as the y-axis, and the direction perpendicular to the image plane pointing towards the front of the high-speed camera as the z-axis. Let the extrinsic parameters of the left virtual high-speed camera relative to the world coordinate system be the rotation matrix. With translation vector The corresponding coordinate transformation relationship is: ; in, This represents the spatial coordinates of the monitoring point in the world coordinate system. The vibration displacement of the target point in the world coordinate system is calculated by obtaining the coordinate difference between adjacent frames. : ; In the formula, k is the image frame number. This represents the three-dimensional displacement change of the target point from frame (k-1) to frame k.

[0041] Step 3.3: Correct the vibration displacement of each target point in the monitoring area based on the data collected by the inertial sensing unit to obtain the true vibration displacement of each target point in the monitoring area. Since the three-dimensional displacement change of the target point calculated in step 3.2 includes the influence of the vibration of the high-speed camera 100 itself, it is necessary to remove the influence by using the data collected by the inertial sensing unit 130 to calculate the displacement of the high-speed camera 100 in the world coordinate system. First, the original angular velocity and linear acceleration of the high-speed camera 100 collected by the inertial sensing unit 130 are compensated: ; In the formula These are the original angular velocity and linear acceleration. , For accelerometer zero bias and gyroscope zero bias, These are the effective angular velocity and effective linear acceleration; The effective linear acceleration is converted from the inertial sensing unit 130 to the world coordinate system, and the gravitational acceleration in the world coordinate system is subtracted. The linear acceleration of the high-speed camera 100's own vibration in the world coordinate system is obtained. The calculation formula is: ; The self-vibration linear acceleration of high-speed camera 100 in the world coordinate system Perform a second integration and synchronize the time according to the high-speed camera's 100-frame interval to obtain the self-vibration displacement of the high-speed camera 100 in the world coordinate system from frame k-1 to frame k. : ; The actual vibration displacement of target point 210 is: ; Step 4: Extract the wave velocity field of the monitoring area based on the actual vibration displacement of each target point 210 in the monitoring area; The propagation speed of waves is related to the medium. For rocks, the wave propagation speed is fast in intact rocks, but the wave speed will decrease when there are cracks or other damage. By obtaining the wave speed field of the entire area based on the actual vibration displacement of each target point 210 and comparing it with the wave speed before blasting, the state of the surrounding rock can be evaluated based on the wave speed reduction rate.

[0042] By obtaining the actual vibration displacement of each target point 210, the actual vibration velocity of the target point 210 in the world coordinate system can be further obtained. : ; Vibration time series can be obtained by capturing continuous frames using a high-speed camera 100. To determine the propagation time difference of the blast wave between different target points 210, the target point closest to the blast source in the monitoring area was selected as the reference point, and the wave arrival time was extracted by cross-correlation analysis of the vibration velocity time history of each target point.

[0043] Let the vibration curve at the reference point be... The vibration curve of the i-th target point is In the first wave of time window Internal cross-correlation function: ; In the formula, This is the amount of time delay. Using the vibration curve as a reference point, the propagation time delay is determined by searching for the location of the maximum value of the cross-correlation function. ; The time when the blast wave reaches the i-th target point is: ; To suppress noise during cross-correlation monitoring and obtain a spatially continuous time-of-arrival field, a target point map structure is constructed, where the distance between any two target points is: ; In the formula, ( X i , Y i , Z i )and( X j , Y j , Z j () represents the coordinates of two target points in the detection area in the world coordinate system; Take a given adjacency radius (Take 1.2 times the average distance between adjacent target points), define the adjacency matrix. : ; In obtaining Post-construction degree matrix : ; Define the graph Laplace smoothing operator: ; In the formula, Penalize abrupt changes in the arrival times of neighboring points, A smoother surface facilitates obtaining stable wave velocities later. The measured arrival times are used to construct the observation vector: The theoretical arrival time field vector to be inverted: The residual is then defined as: ; To improve inversion stability, a regularized inversion objective function is constructed: ; In the formula, This is the weight matrix. For the graph Laplace smoothing operator, Here is the regularization parameter. The Levenberg-Marquardt method is used for iterative solution. In the k-th iteration, update its increment. satisfy: ; In the formula, The Jacobian matrix is ​​then used to update the model parameters: ; When satisfied When the iteration stops, the continuous arrival time field is obtained. It can be achieved by calculating the arrival time field. Spatial gradients yield slow fields: ; Based on the relationship between slowness and wave speed The wave velocity field of the monitored area can then be obtained: ; Step 5: Calculate the wave velocity s based on the wave velocity field of the monitoring area, and combine it with the wave velocity obtained before the blasting from the acoustic wave test. s 0, calculate wave velocity reduction rate η ; ; Step Six: Evaluate the surrounding rock condition of the monitoring area based on the wave velocity reduction rate; when the wave velocity reduction rate is <5%, 5%-15%, 15%-30%, or >30%, the surrounding rock condition is judged as intact, slightly damaged, moderately fractured, or strongly fractured, respectively. Among them, when the wave velocity reduction rate is 15%, the surrounding rock condition can be judged as slightly damaged or moderately fractured.

[0044] The three-dimensional blasting vibration response non-contact measurement device and surrounding rock condition evaluation method provided in this application embodiment acquire images of each target point 210 in the monitoring area using a single high-speed camera 100, a pair of outer reflectors 110, and a pair of inner reflectors 120 during blasting operations in the tunnel 200. Simultaneously, an inertial sensing unit 130 collects vibration data from the high-speed camera 100. Based on the images of each target point in the monitoring area acquired by the high-speed camera 100 and the vibration data collected by the inertial sensing unit 130, the true vibration displacement of each target point 210 in the world coordinate system after removing the vibration error of the high-speed camera 100 is calculated. Then, the wave velocity field of the monitoring area is extracted, and the wave velocity reduction rate is calculated. Based on the wave velocity reduction rate, the surrounding rock condition of the monitoring area is evaluated. This method can achieve non-contact measurement of the three-dimensional blasting vibration response and surrounding rock condition evaluation in tunnels using a single high-speed camera 100, reducing testing costs and eliminating the error caused by the vibration of the high-speed camera 100 itself, effectively improving the evaluation accuracy and providing reliable data support for blasting construction safety control and parameter optimization.

[0045] 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 three-dimensional non-contact measurement device for blasting vibration response, characterized in that, High-speed cameras are used to acquire images; A pair of outer reflectors are positioned on either side of the optical axis of the high-speed camera to reflect light. A pair of inner reflectors are disposed between the two outer reflectors and arranged opposite to the high-speed camera to reflect the light reflected by the two outer reflectors into the lens of the high-speed camera. An inertial sensing unit is connected to the high-speed camera to collect vibration data from the high-speed camera. The synchronization trigger module is electrically connected to both the high-speed camera and the inertial sensing unit, and is used to control the inertial sensing unit to collect vibration data of the high-speed camera when the high-speed camera is acquiring images.

2. The three-dimensional blasting vibration response non-contact measurement device according to claim 1, characterized in that, It also includes rotary motors for driving each of the outer reflectors to rotate about a vertical axis.

3. The three-dimensional blasting vibration response non-contact measurement device according to claim 1, characterized in that, It also includes at least one illumination lamp for providing light to illuminate the area to be tested, so that the light emitted by the area to be tested is reflected by the two outer reflectors.

4. A method for evaluating the condition of surrounding rock, characterized in that, It includes the following steps: Geometric calibration of the three-dimensional blasting vibration response non-contact measurement device as described in any one of claims 1 to 3; During blasting operations inside the tunnel, the high-speed camera in the three-dimensional blasting vibration response non-contact measurement device acquires images of each target point in the monitoring area, and the vibration data of the high-speed camera is collected simultaneously using an inertial sensing unit. The true vibration displacement of each target point in the world coordinate system after removing the vibration error of the high-speed camera is calculated based on the images of each target point in the monitoring area acquired by the high-speed camera and the vibration data collected by the inertial sensing unit. The wave velocity field of the monitoring area is extracted based on the actual vibration displacement of each target point in the world coordinate system after removing the vibration error of the high-speed camera. The wave velocity and wave velocity reduction rate of the rock mass were calculated based on the wave velocity field of the monitored area. The surrounding rock condition of the monitoring area is evaluated based on the wave velocity reduction rate.

5. The method for evaluating the surrounding rock condition according to claim 4, characterized in that, The geometric calibration of the three-dimensional blasting vibration response non-contact measurement device includes the following steps: obtaining the rotation matrix of the physical coordinate system of the high-speed camera and the inertial sensing unit, as well as the intrinsic parameter matrix of the high-speed camera; simultaneously obtaining the distance between the rotation axes of the two outer reflectors, the distance between the inner reflector and the optical center of the high-speed camera, the rotation angle of the outer reflectors, and the original data of the inertial sensing unit in the static state of the high-speed camera before blasting; and calculating the zero bias of the accelerometer and the zero bias of the gyroscope to complete the zero bias compensation of the inertial sensing unit.

6. The method for evaluating the surrounding rock condition according to claim 5, characterized in that, The intrinsic parameter matrix of the high-speed camera includes focal length, principal point position, and pixel size.

7. The method for evaluating the surrounding rock condition according to claim 4, characterized in that, The calculation of the true vibration displacement of each target point in the world coordinate system after removing the vibration error of the high-speed camera, based on the images of each target point in the monitoring area acquired by the high-speed camera and the vibration data collected by the inertial sensing unit, includes the following steps: The images of each target point in the monitoring area acquired by the high-speed camera are converted into images of an equivalent virtual high-speed camera formed behind two outer mirrors. The optical axis of the two equivalent virtual high-speed camera images is corrected to make the optical axes of the two virtual high-speed cameras parallel. The imaging posture is the same as that of the two equivalent virtual high-speed camera images. The vibration displacement of each target point in the monitoring area is calculated based on the images after optical axis correction and rotation correction of the two equivalent virtual high-speed cameras. The vibration displacement of each target point in the monitoring area is corrected based on the vibration data collected by the inertial sensing unit, so as to obtain the true vibration displacement of each target point in the monitoring area after removing the vibration error of the high-speed camera.

8. The method for evaluating the surrounding rock condition according to claim 7, characterized in that, Performing optical axis correction on the images of the two equivalent virtual high-speed cameras to make the optical axes of the two virtual high-speed cameras parallel includes the following steps: The rotation matrix and translation vector between the two virtual high-speed cameras are calculated based on the geometric calibration parameters of the three-dimensional blasting vibration response non-contact measurement device. The baseline unit direction vector is obtained by normalizing the translation vector; The virtual baseline direction is consistent with the x-axis of the coordinate system established by the left virtual high-speed camera. This direction is selected as the x-axis direction of the correction coordinate system. The optical axis directions of the left and right virtual high-speed cameras are obtained with the left virtual high-speed camera coordinate system as the reference coordinate system. The optical axis directions of the left and right virtual high-speed cameras are weighted and averaged, and then normalized to construct the initial optical axis directions for binocular imaging with parallel optical axes. Make the calibration intrinsic parameter matrix consistent with the original intrinsic parameter matrix, and construct the y-axis direction and the final optical axis direction of the calibration coordinate system according to the orthogonal constraint relationship; The rotation correction matrices for the left and right virtual high-speed cameras are constructed based on the x-axis, y-axis, and z-axis directions of the correction coordinate system.

9. The method for evaluating the state of surrounding rock according to claim 7, characterized in that, The rotation correction of the images of the two equivalent virtual high-speed cameras to make the imaging posture the same includes the following steps: making the corrected equivalent intrinsic parameter matrix consistent with the original intrinsic parameter matrix to obtain the corresponding correction projection matrix and the correction mapping matrix of the left and right images, and performing mapping correction on the images of the two equivalent virtual high-speed cameras.

10. The method for evaluating the surrounding rock condition according to claim 7, characterized in that, The vibration displacement of each target point in the monitoring area is calculated based on the images after optical axis correction and rotation correction of the two equivalent virtual high-speed cameras, including the following steps: Calculate the horizontal disparity of the corresponding target points in the two images corrected by the equivalent virtual high-speed cameras; Calculate the depth information of the target point based on the principle of parallel binocular geometric measurement; Calculate the three-dimensional coordinates of the target point in a virtual high-speed camera coordinate system and convert them into the three-dimensional coordinates of the target point in the world coordinate system; The vibration displacement of the target point in the adjacent frames in the world coordinate system is calculated by the coordinate difference between the acquired adjacent frames.

11. The method for evaluating the surrounding rock condition according to claim 4, characterized in that, The correction of vibration displacement at each target point in the monitoring area based on vibration data collected by the inertial sensing unit includes the following steps: The original angular velocity and linear acceleration collected by the inertial sensing unit are compensated to obtain the effective linear acceleration and effective angular velocity of the inertial sensing unit. The self-vibration linear acceleration of the high-speed camera in the world coordinate system is integrated twice, and time synchronization is performed according to the frame interval of the high-speed camera to obtain the self-vibration displacement of the high-speed camera in the world coordinate system in adjacent frames. The true vibration displacement of the target point is calculated based on the vibration displacement of the target point in the world coordinate system in adjacent frames and the self-vibration displacement of the high-speed camera in the world coordinate system in adjacent frames.

12. The method for evaluating the surrounding rock condition according to claim 4, characterized in that, The wave velocity field of the monitored area is extracted based on the actual vibration displacement of each target point in the world coordinate system after removing the vibration error of the high-speed camera, including the following steps: Based on the actual vibration displacement of each target point in the monitoring area, the actual vibration velocity and vibration time sequence of each target point in the world coordinate system are calculated, and the time when the blast wave arrives at each target point is calculated. Construct a regularized inversion objective function, update the increment and model parameters, and perform inversion; When the iteration stops when the convergence condition is met, a continuous arrival time field is obtained. The slowness field is obtained by calculating the spatial gradient of the arrival time field. The wave velocity field of the monitoring area is calculated based on the relationship between slowness and wave velocity.

13. The method for evaluating the surrounding rock condition according to claim 4, characterized in that, When evaluating the surrounding rock properties of the monitoring area based on the wave velocity reduction rate, the surrounding rock conditions are judged as intact, slightly damaged, moderately fractured, and strongly fractured when the wave velocity reduction rate is <5%, 5%-15%, 15%-30%, and >30%, respectively.

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