Irregular rock sample point load rapid testing device and method based on digital technology

Abstract

The invention relates to the technical field of point load tests, in particular to an irregular rock sample point load rapid testing device and method based on digital technology.The testing device comprises a point load tester, a guide plate is arranged on the point load tester in a sliding mode, bearing assemblies are symmetrically arranged on the two sides of the guide plate, and adjusting assemblies are installed on the bearing assemblies; the adjusting assembly comprises a movable mounting plate, cameras are rotationally arranged at the two ends of the mounting plate respectively, and the two cameras shoot sample images of left and right visual angles of the damaged sample; the test method is applied to the test device and comprises the following steps: performing correction, extraction processing, stereo matching and three-dimensional reconstruction processing on a sample image to obtain triangulation reconstruction models of the fracture surface of the damaged sample, establishing a projection surface in the two triangulation reconstruction models of the fracture surface of the damaged sample, and obtaining a projection calculation area of the fracture surface of the sample. Calculating a point load strength index according to an equivalent area calculation formula; according to the invention, point load testing is carried out on irregular different types of rock samples, and the measurement precision and the testing efficiency are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of point load testing, and in particular to a device and method for rapid point load testing of irregular rock samples based on digital technology. Background Art

[0002] When constructing underground projects, it is necessary to evaluate the basic mechanical properties of the surrounding rock, such as uniaxial compressive strength and tensile strength. These are important basic mechanical parameters and are also the most commonly used parameters for mining sampling and engineering exploration to evaluate rock mass strength. The accuracy of the test data directly affects the safety and cost of the project. Currently, a point load tester is generally used to apply load to the specimen to destroy it, and the equivalent failure area and failure load of the specimen after loading are measured to obtain the point load strength index, thereby evaluating the overall strength grade of the rock and conducting a retrograde evaluation. The mechanical essence of point load strength is the maximum tensile stress that the specimen can withstand per unit failure area. The point load strength is related to the failure area. The equivalent area method is generally used to measure the point load strength index of rock samples. Due to the inherent heterogeneity of rocks and the complex shapes of irregular rock samples, the area of the failure zone is difficult to measure accurately. Therefore, an area factor correction is usually introduced. The introduced area factor is defined as the ratio of the actual failure cross section to the minimum cross section. Although the introduction of the area factor simplifies the measurement process to a certain extent, determining the value of the area factor requires a large number of experiments and statistical analyses. For rocks of different types and degrees of weathering, the value of the area factor needs to be determined separately, which increases the workload and complexity of the research. In addition, the selection of the area factor is relatively subjective, resulting in a decrease in the accuracy of the test results.

[0003] In addition, in the existing technology, the fracture surface of the sample is generally manually traced on the area paper by rubbing, and the fracture surface of the sample traced on the area paper is calculated. The overall process is relatively cumbersome, and the test efficiency and accuracy are low, which cannot meet the needs of rapid engineering testing and affects the test progress. Summary of the Invention

[0004] The purpose of the present invention is to provide a device and method for rapid point load testing of irregular rock samples based on digital technology to solve the problems raised in the above background technology.

[0005] To achieve the above object, the present invention provides the following technical solutions:

[0006] The method for rapid point load testing of irregular rock samples based on digital technology includes the following steps:

[0007] Select irregular specimens of natural rock, conduct point load tests, obtain the failure specimens after loading and splitting, and obtain the specimen failure load P;

[0008] The camera synchronously captures the left and right perspective images of the damaged sample on the cleavage surface of the damaged sample and transmits them to the control module, which uses the camera parameters to perform image correction on the left and right perspective images of the damaged sample;

[0009] The image of the damaged sample is processed for splitting surface extraction to obtain splitting surface features, and the SGM algorithm is used for stereo matching to obtain the view difference, realize triangulation reconstruction of the splitting surface, and obtain the triangulated reconstruction model of the splitting surface of the damaged sample;

[0010] The projection surfaces are respectively established in the triangulated reconstruction model of the splitting surfaces of the two damaged specimens, and the splitting surfaces of the damaged specimens are projected. The average projection area of the triangulated reconstruction model of the splitting surfaces of the two damaged specimens is calculated. As the calculation area A, according to the failure load P corresponding to the failure specimen and the calculation area A, the load intensity index I of the failure specimen point is calculated. S1 ;

[0011] Repeat the above steps to obtain the point load strength index I of multiple irregular samples of the same type of rock Si , where i = 1, 2, 3, 4...n, calculate the load intensity index I of multiple test points Si The average value of the same type of rock is recorded as the point load intensity index.

[0012] Preferably, the triangulated reconstruction process is as follows: the obtained disparity map is processed, the depth of each pixel point and the corresponding three-dimensional coordinates in the real world are calculated through the disparity map, the three-dimensional coordinates of each pixel point in the sample cleavage surface feature are input into the computer software, and a triangulated facet is generated using the Poisson reconstruction method to perform triangulated reconstruction of the cleavage surface of the destroyed sample.

[0013] Preferably, the step of obtaining the calculated area A is as follows: in the triangulated reconstruction model of the sample splitting, the XY plane of the corresponding three-dimensional coordinate system is rotated around the Y axis in sequence by a set angle to establish multiple target projection surfaces, and the calculated area A of the sample splitting three-dimensional model based on each target projection surface is obtained respectively. c , multiple calculation areas A c Statistical calculation of mean and variance, taking the projection calculation area when the variance is minimum, and the mean calculation area of the projection of the triangulated reconstruction model of the splitting surface of the two damaged specimens The cleavage surface area A of the real failure specimen is taken as the cleavage surface area A of the real failure specimen.

[0014] Preferably, the calculated area A of the cleavage surface of the destruction specimen is c The acquisition method is as follows: Based on a target projection surface, each triangular facet of the surface of the three-dimensional model of the damaged sample is projected onto the target projection surface, and the corresponding two-dimensional triangles are obtained respectively. The area of each two-dimensional triangle is calculated, and the area of each two-dimensional triangle is accumulated to obtain the calculated area A of the cleavage surface of the damaged sample. c .

[0015] Preferably, the point load strength I Si The index is calculated as follows:

[0016]

[0017] Where P is the failure load and A is the area of the cleavage surface of the failed specimen.

[0018] A rapid point load testing device for irregular rock samples based on digital technology is applied to the above-mentioned rapid point load testing method for irregular rock samples based on digital technology, including a point load tester, a guide plate is slidingly provided on the point load tester, an upper pressure head is telescopically provided on the upper part of the point load tester, a lower pressure head is fixedly provided on the guide plate, and receiving components are symmetrically provided on both sides of the guide plate, the receiving components include a support plate and a buffer plate, the middle part of the support plate is connected to the buffer plate by a spring, an adjustment component is installed above the support plate, the adjustment component includes a movable moving part, the moving part is driven by a gear rack mechanism to move in a direction close to or away from the lower pressure head, a mounting plate is rotatably provided on the moving part, cameras are rotatably provided at both ends of the mounting plate, the mounting plate adjusts its relative position with the sample through gear transmission, and the two cameras shoot the damaged sample from the left and right perspectives of the sample.

[0019] Preferably, the receiving assembly also includes a mounting piece, which is plugged into the side of the guide plate, and the two ends of the lower end of the mounting piece are respectively threaded with rotating screws that contact the guide plate, the upper surface of the mounting piece is fixedly connected to the support plate, and a pad is fitted on the upper surface of the buffer plate.

[0020] Preferably, the adjustment assembly also includes an adjusting part, which is fixedly arranged above the support plate, and the adjusting part is threadedly connected to the moving part through a horizontally rotating screw rod, and a slot is provided on the side of the adjusting part facing the lower pressure head, and a movable part is slidingly provided on the middle part of the upper surface of the moving part, and a moving gear is rotatably provided on one side of the movable part, and a moving rack is fixedly provided on one side of the upper surface of the moving part and is vertically arranged with the screw rod, and the moving rack is meshed with the moving gear.

[0021] Preferably, a rotating block is fixedly provided on the side of the movable member facing the lower pressure head, the rotating block is rotatably connected to a rotating ear fixedly provided in the middle of the mounting plate, and the mounting plate is rotated by a gear transmission structure.

[0022] Preferably, it also includes a control module, an image processing module, a three-dimensional reconstruction module and a strength calculation module. The control module coordinates the actions of the image processing module, the three-dimensional reconstruction module and the strength calculation module; the control module is electrically connected to the camera, and the control module is also electrically connected to the point load tester.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] The present invention provides a rapid point load testing device for irregular rock samples based on digital technology, comprising a point load tester, wherein receiving components are respectively provided on both sides of the point load tester, the receiving components comprising a buffer plate, the buffer plate receiving the broken sample after splitting, thereby preventing the broken sample from falling directly on the ground, and the impact on the splitting surface of the broken sample causing damage to the splitting surface; an adjustment component is provided on the receiving component, the adjustment component comprising a mounting plate, the mounting plate is adjusted relative to the damaged sample through a screw nut mechanism and a gear rack structure, cameras are respectively arranged at both ends of the mounting plate, and can capture sample images of the damaged sample from two perspectives, namely the left and right, to facilitate computer vision analysis of the sample images, thereby realizing automation of the point load test, reducing manual operation, improving test efficiency, and being suitable for batch testing needs. The device can be applied to samples of irregular shapes and reduces mechanical processing.

[0025] The irregular rock sample point load rapid testing device provided by the present invention, based on digital technology, adopts computer image processing algorithm to realize image correction of sample image and extraction of splitting surface features, and adopts SGM algorithm to perform stereo matching based on the splitting surface features to realize three-dimensional reconstruction and obtain the three-dimensional model of the sample splitting, which greatly reduces human measurement errors and improves data reliability.

[0026] The digital technology-based rapid point load testing method for irregular rock samples provided by the present invention is applied to a digital technology-based rapid point load testing device for irregular rock samples, eliminating the subjective influence of the area factor, and can realize point load testing on irregular rock samples, thereby improving measurement accuracy and testing efficiency. It can also be used to test different types of rock samples, and has strong applicability. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is a schematic diagram of the connection structure of the irregular rock sample point load rapid testing device based on digital technology according to an embodiment of the present invention;

[0028] Figure 2 This is a schematic diagram of the connection structure of the irregular rock sample point load rapid testing device based on digital technology according to an embodiment of the present invention in a side view;

[0029] Figure 3 This is a schematic diagram of the exploded structure of the connection between the receiving assembly, the adjusting assembly and the camera according to an embodiment of the present invention;

[0030] Figure 4 This is a schematic diagram of the decomposition structure of the adjustment component connection according to an embodiment of the present invention;

[0031] Figure 5 This is a flow chart of a method for rapid point load testing of irregular rock samples based on digital technology according to an embodiment of the present invention;

[0032] Figure 6This is a schematic diagram of an irregular sample structure in an embodiment of the present invention;

[0033] Figure 7 Schematic diagram of the coordinate system and target projection surface of the triangulated reconstruction model of the cleavage surface of one of the destroyed specimens in an embodiment of the present invention.

[0034] Figure numerals: 1. Point load tester; 11. Upper pressure head; 12. Lower pressure head; 2. Support assembly; 21. Mounting part; 22. Rotating screw; 23. Support plate; 231. Connecting block; 232. Through groove; 26. Buffer plate; 27. Pad; 28. Connecting part; 3. Adjusting assembly; 31. Adjusting part; 32. Screw; 33. Moving part; 331. Moving plate; 332. Moving rack; 34. Moving part; 341. Rotating block; 342. Moving gear; 35. Mounting plate; 351. Rotating ear; 352. Rotating gear set; 36. Rotating gear set; 4. Camera. DETAILED DESCRIPTION

[0035] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0036] In the following description of the invention, it should be noted that the terms "upper," "lower," "left," "right," "inner," and "outer," etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings and are intended solely to facilitate and simplify the description of the invention. They are not intended to indicate or imply that the devices or components referred to must have a specific orientation, be constructed, or operate in a specific orientation. The term "connected" simply indicates a connection between devices and does not have any special meaning.

[0037] In addition, the technical fields and installation methods involved in the embodiments of the present invention described below can be combined with each other as long as there is no conflict between them.

[0038] Specific examples: Please refer to Figures 1-4A rapid point load testing device for irregular rock samples based on digital technology includes a point load tester 1, an upper pressure head 11 is telescopically arranged on the upper part of the point load tester 1, a guide plate is slidingly arranged on the point load tester 1, a lower pressure head 12 is fixedly arranged on the guide plate, and receiving components 2 are symmetrically arranged on both sides of the guide plate, the receiving component 2 includes a support plate 23 and a buffer plate 26, the middle part of the support plate 23 is connected to the buffer plate 26 by a spring, an adjustment component 3 is installed above the support plate 23, the adjustment component 3 includes a movable moving part 33, the moving part 33 is driven by a gear rack mechanism to move in the direction of approaching or away from the lower pressure head 12, a mounting plate 35 is rotatably arranged on the moving part 33, cameras 4 are rotatably arranged at both ends of the mounting plate 35, the mounting plate 35 adjusts its relative position with the damaged sample through gear transmission, and the two cameras 4 shoot the damaged sample from the left and right perspectives.

[0039] The receiving assembly 2 also includes a mounting member 21, a rotating screw 22, a pad 27 and a connecting member 28; the mounting member 21 adopts a U-shaped structure, and a rotating screw 22 is provided at both ends of the lower end of the mounting member 21, and the side of the guide plate is plugged into the mounting member 21. The rotating screw 22 is composed of a knob, a threaded rod and a fixed plate from bottom to top. The threaded rod on the rotating screw 22 is threadedly connected to the mounting member 21, and the knob is turned to drive the fixed plate to abut against the lower surface of the guide plate, so that the receiving assembly 2 and the components installed on the receiving assembly 2 are convenient for disassembly or installation of the point load tester 1; the two ends of the lower surface of the support plate 23 are fixedly connected to the mounting member 21 by fixed connecting blocks 231, and a through groove 232 is provided in the middle of the support plate 23, and a buffer plate 26 is provided in the through groove 232. The two sides of the lower side of the buffer plate 26 A spring is respectively provided, and the upper end of the spring is fixedly connected to the support plate 23. A semicircular notch is provided on the side of the buffer plate 26 facing the lower pressure head 12. After the two receiving components 2 are respectively installed on both sides of the guide plate on the point load tester 1, the semicircular notches of the buffer plates 26 in the two receiving components 2 are spliced into a circular avoidance groove, and the lower pressure head 12 is slidably connected to the circular avoidance groove. A pad 27 is fitted on the upper surface of the buffer plate 26. The pad 27 is made of soft materials such as rubber and resin. After the point load test, the split sample falls directly on the pad 27 to reduce the possibility of damage to the splitting surface; connecting parts 28 are respectively fixedly provided at both ends of the upper surface of the support plate 23, and a connecting plate is provided between the two connecting parts 28. The connecting plate is located on the side of the support plate 23 away from the upper pressure head 11, and an adjustment component 3 is installed on the connecting part 28.

[0040] The adjusting assembly 3 also includes an adjusting member 31, a screw rod 32, a moving member 33 and a movable member 34. The two ends of the lower surface of the adjusting member 31 are fixedly connected to the two connecting members 28 respectively. The adjusting member 31 adopts a frame structure. The adjusting member 31 is provided with a slot on the side facing the lower pressure head 12. A screw rod 32 is rotatably provided in the adjusting member 31. The screw rod 32 is driven to rotate by an adjusting motor (not shown in the figure) provided on the end wall of the adjusting member 31. A moving member 33 is threadedly connected to the screw rod 32. A moving plate 331 is fixedly provided above the moving member 33. A movable member 34 is slidably provided in the middle of the moving plate 331. A moving gear 342 is rotatably provided on one side of the movable member 34. The moving plate 331 A moving rack 332 is fixedly provided on one side of the upper surface. The moving rack 332 is perpendicular to the screw rod 32. The moving rack 332 is meshed with a moving gear 342. The moving gear 342 is driven to rotate by a moving motor (not shown in the figure). The movable part 34 adopts an L-shaped structure. A rotating block 341 is fixedly provided on the side of the movable part 34 facing the lower pressure head 12. The rotating block 341 is rotatably connected to a rotating ear 351 fixedly provided in the middle of the mounting plate 35, and the mounting plate 35 is rotated by the rotating gear set 36. The rotating gear set 36 includes a rotating driving gear and a rotating driven gear that mesh with each other. This arrangement can adjust the relative position between the camera 4 and the damaged sample.

[0041] The rotating gear set 352 is installed at both ends of the side of the mounting plate 35 away from the lower pressure head 12. The rotating gear set 352 includes a driven gear and a driving gear. The driven gear is fixedly connected to the camera seat shaft fixedly set on the camera 4. The camera seat shaft passes through the mounting plate 35 and is rotatably connected to the mounting plate 35. The driving gear is rotatably set on the upper part of the mounting plate 35. The driven gear and the driving gear are meshed and connected. The driving gear is driven by a driving motor (not shown in the figure); when the adjustment component 3 cooperates to shoot the damaged sample, according to the position of the damaged sample, the screw rod 32 is adjusted to rotate so that the moving part 33 corresponds to the position of the damaged sample on the pad 27, and at the same time, the moving gear 342 is adjusted to rotate so that the movable part 34 and the mounting plate 35 are close to the damaged sample, and the rotating gear set 36 is adjusted to rotate so that the cameras 4 at both ends of the mounting plate 35 are respectively located on both sides of the damaged sample, which is convenient for the camera 4 to shoot. The camera 4 shoots the image of the cleavage surface of the damaged sample.

[0042] The irregular rock sample point load rapid testing device based on digital technology also includes a control module, which is electrically connected to the camera 4 and receives images of the splitting surfaces on both sides of the damaged sample taken by the camera 4; the control module is also connected to the adjustment motor, the rotating motor, the moving motor, the driving motor and the point load tester 1, transmits adjustment signals to the adjustment motor, the rotating motor, the moving motor, the driving motor and the point load tester 1, performs point load tests, and records the applied loads of the point load tester 1 during multiple tests, corresponds the corresponding loads to the splitting images of the damaged sample, and stores them in a database; at the same time, the control module obtains the focal length and resolution of the camera 4 and the baseline distance between the two cameras 4.

[0043] The image processing module performs image correction on the left and right damaged sample images, identifies the edge features of the cleavage surface of the corrected image, and extracts the cleavage surface edge. The extracted cleavage surface image is used to obtain a disparity map using the SGM algorithm, and the disparity map is post-processed to calculate the depth of each pixel in the cleavage surface image and the corresponding real-world three-dimensional coordinates.

[0044] The three-dimensional reconstruction module uses the Poisson reconstruction method to triangulate the cleavage surface of the damaged sample based on the acquired real-world three-dimensional coordinates to obtain a triangulated reconstruction model of the cleavage surface of the damaged sample;

[0045] The strength calculation module establishes multiple target projection surfaces by rotating horizontally in the triangulated reconstruction model of the splitting surface of the damaged specimen, calculates the calculation area corresponding to each target projection surface respectively, and obtains the average of the calculation areas obtained by geometric projection in the triangulated reconstruction model of the splitting surface of the two damaged specimens based on one of the selected target reference surfaces, and uses it as the actual specimen splitting surface area for point load strength calculation.

[0046] The control module controls and coordinates the operation of the image processing module, the three-dimensional reconstruction module and the intensity calculation module.

[0047] See also Figure 5-Figure 6 The method for rapid point load testing of irregular rock samples based on digital technology is applied to the aforementioned rapid point load testing device for irregular rock samples based on digital technology, and comprises the following steps:

[0048] S1: Select an irregular specimen of natural rock and conduct a point load test to obtain the failure specimen after loading and splitting, and obtain the specimen failure load P;

[0049] Specifically, multiple irregular rock blocks, such as phyllite and shale, were collected from the site and used as specimens for point load tests. The specimen surface should avoid sharp edges or obvious defects. The specimen size ranged from 30 to 85 mm. For specific specimen examples, see Figure 6As shown in the three-dimensional image of the specimen in (a), the arrow indicates the loading direction of the point load test, and the shape factor β is used as one of the factors for selecting the specimen;

[0050] The calculation formula of the sample shape factor β is:

[0051]

[0052] in, Figure 6 As shown in the left view of the specimen shown in (b), D is the spacing between loading points, W is the minimum width of the specimen perpendicular to the loading direction; the value range of the specimen shape factor β is 0.3~1.0.

[0053] Place the sample on the point load tester 1, adjust the control module to transmit the adjustment signal to the loading system of the point load tester 1, so that the upper pressure head 11 and the lower pressure head 12 are in contact with the upper and lower surfaces of the sample respectively, and the control module outputs the adjustment signal to gradually apply the load until the sample is destroyed. The sample destruction is that the splitting surface of the sample passes through the two loading points and passes through the entire sample. Record the maximum destruction load value. The two destroyed samples fall on the pad 27 respectively. Adjust the two adjustment components 3 respectively, adjust the screw rod 32 to rotate, so that the moving part 33 corresponds to the position of the destroyed sample on the corresponding pad 27, and at the same time adjust the moving gear 342 to rotate so that the movable part 34 and the mounting plate 35 are close to the destroyed sample. Adjust the rotating gear group 36 to rotate so that the cameras 4 at both ends of the mounting plate 35 are respectively located on both sides of the destroyed sample. The cameras 4 installed on the two adjustment components 3 respectively take images of the splitting surfaces of the two destroyed samples.

[0054] S2: Camera 4 synchronously captures the left and right perspective images of the damaged sample on the cleavage surface of the damaged sample, and transmits them to the control module, which uses the parameters of camera 4 to perform image correction on the left and right perspective images of the damaged sample;

[0055] Before collecting the image of the split sample, calibration is performed to obtain calibration parameters of the camera 4 to facilitate subsequent image processing. The focal length, resolution and other data of the two cameras 4 are the same, and the two cameras 4 shoot simultaneously.

[0056] Specifically, the cameras 4 located on both sides of the same damaged sample respectively capture images of the damaged sample from the left and right perspectives and transmit them to the control module. At the same time, the control module obtains and utilizes the parameters of camera 4, which include internal parameters, external parameters, distortion coefficients, etc., to perform image correction on the images of the damaged sample from the left and right perspectives to eliminate distortion and align the epipolar lines.

[0057] S3: Extract and process the cleavage surface of the damaged sample image to obtain the cleavage surface features, use the SGM algorithm for stereo matching, obtain the view difference, realize triangulation reconstruction of the cleavage surface, and obtain the triangulation reconstruction model of the cleavage surface of the damaged sample;

[0058] Specifically, the image processing module obtains damaged sample images from the left and right perspectives of the same damaged sample, and uses algorithms such as SIFT, SURF, or ORB to extract corner and edge features, thereby extracting the cleavage surface features of the damaged sample from the left and right perspectives. The cleavage surface features of the left and right damaged samples are stereo matched using the SGM algorithm to obtain a disparity map; the SGM algorithm is a semi-global matching algorithm, which is an existing technology and will not be described in detail;

[0059] Secondly, the obtained disparity map is post-processed, including median filtering and denoising. After post-processing, the depth z of each pixel and its corresponding three-dimensional coordinate in the real world are calculated from the disparity map. Then, the three-dimensional coordinates of each pixel in the cleavage surface feature of the destroyed sample are input into computer software, and the cleavage surface of the destroyed sample is triangulated and reconstructed using the Poisson reconstruction method.

[0060] Specifically, the three-dimensional coordinates of multiple pixel points are input into computer software, outlier pixels are eliminated, the point cloud normal vector is estimated by the PCA method, the computer software adaptively constructs an octree structure, the point cloud is divided into cube grids of appropriate depth, the pixel data in each cube grid is mapped to the leaf nodes of the octree, the point cloud normal vector is used to construct a vector field in each leaf node of the octree, the point cloud normal vector and the vector field are used to approximate the true gradient field of the object, and then the Poisson equation is obtained, and the implicit function is solved for the Poisson equation. The right-hand side term of the Poisson equation is the divergence of the vector field, and the left-hand side term is the divergence of the second-order derivative of the implicit function, where the implicit function is related to the point cloud coordinates, and the isosurface with the implicit function value of zero represents the reconstructed surface. The leaf nodes of the octree are traversed, the zero isosurface is extracted, and the isosurface is used to generate triangular facets, and multiple triangular facets constitute a triangulated reconstructed model of the cleavage surface of the damaged specimen.

[0061] Among them, the triangulated reconstruction model of the cleavage surface of the damaged specimen after Poisson reconstruction maintains the same coordinate system as the three-dimensional coordinates of the point cloud, and the coordinate values of the vertices of each triangular facet of the triangulated reconstruction model of the cleavage surface of the damaged specimen remain unchanged with the coordinate values of the corresponding pixel points in the point cloud.

[0062] S4: Projection surfaces are established in the triangulated reconstruction model of the splitting surfaces of the two damaged specimens, and the splitting surfaces of the damaged specimens are projected. The average projection area of the triangulated reconstruction model of the splitting surfaces of the two damaged specimens is calculated. As the calculation area A, according to the failure load P corresponding to the failure specimen and the calculation area A, the load intensity index I of the failure specimen point is calculated. S1 .

[0063] Specifically, take the triangulated reconstruction model of the cleavage surface of one of the damaged specimens as an example. Figure 7As shown, the XY plane of the corresponding three-dimensional coordinate system is rotated around the Y axis in sequence by a set angle to establish multiple target projection surfaces. For example, the XY plane is rotated around the Y axis by 10° to establish three target projection surfaces, a lower projection surface M' with an angle of -10° relative to the XY plane, a reference projection surface M with an angle of 0° relative to the XY plane, and an upper projection surface M' with an angle of 10° relative to the XY plane. The set rotation angle is greater than 0 degrees and less than 20 degrees. The triangulated reconstruction model of the cleavage surface of the damaged sample is obtained based on the calculated area A of each target projection surface. c The purpose is to reduce the directional deviation of the cleavage surface of the damaged specimen due to the uneven surface undulations, and to enhance the anti-noise ability and data robustness.

[0064] Among them, based on one of the target projection surfaces, each triangular facet of the surface of the cleavage three-dimensional model of the damaged sample is projected onto the target projection surface, and the corresponding two-dimensional triangles are obtained respectively. The area of each two-dimensional triangle is calculated, and the area of each two-dimensional triangle is accumulated to obtain the calculated area A of the cleavage surface of the damaged sample. c ;

[0065] A c =A1+A2+A3+…+A n

[0066] Assume that the area of one of the two-dimensional triangles is A1, and the coordinates of the three vertices of the two-dimensional triangle are M(x1, y1), N(x2, y2), and U(x3, y3). The calculated area of the two-dimensional triangle is:

[0067]

[0068] Based on multiple target projection surfaces, the above-mentioned projection calculation area is respectively obtained, the mean and variance of multiple projection areas are calculated, and the projection calculation area when the variance is minimum is obtained. The mean calculation area obtained by geometric projection in the triangulated reconstruction model of the splitting surface of the two damaged specimens is The cleavage surface area A of the real failure specimen is taken as the cleavage surface area A of the real failure specimen.

[0069] S5: Repeat the above steps to obtain the point load strength index I of multiple irregular samples of the same type of rock Si , where i = 1, 2, 3, 4...n, calculate the load intensity index I of multiple test points Si The average value of the same type of rock is recorded as the point load intensity index.

[0070] Specifically, the equivalent area method is used to calculate the point load intensity index I Si , point load intensity index I Si The calculation formula is:

[0071]

[0072] Where P is the failure load and A is the area of the cleavage surface of the failed specimen.

[0073] The present invention provides a rapid point load testing device for irregular rock samples based on digital technology, comprising a point load tester, wherein receiving components are respectively provided on both sides of the point load tester, the receiving components comprising a buffer plate, the buffer plate receiving the broken sample after splitting, thereby preventing the broken sample from falling directly on the ground, and the impact on the splitting surface of the broken sample causing damage to the splitting surface; an adjustment component is provided on the receiving component, the adjustment component comprising a mounting plate, the mounting plate is adjusted relative to the damaged sample through a screw nut mechanism and a gear rack structure, cameras are respectively arranged at both ends of the mounting plate, and can capture sample images of the damaged sample from two perspectives, namely the left and right, to facilitate computer vision analysis of the sample images, thereby realizing automation of the point load test, reducing manual operation, improving test efficiency, and being suitable for batch testing needs. The device can be applied to samples of irregular shapes and reduces mechanical processing.

[0074] The irregular rock sample point load rapid testing device provided by the present invention, based on digital technology, adopts computer image processing algorithm to realize image correction of sample image and extraction of splitting surface features, and adopts SGM algorithm to perform stereo matching based on the splitting surface features to realize three-dimensional reconstruction and obtain the three-dimensional model of the sample splitting, which greatly reduces human measurement errors and improves data reliability.

[0075] The digital technology-based rapid point load testing method for irregular rock samples provided by the present invention is applied to a digital technology-based rapid point load testing device for irregular rock samples, eliminating the subjective influence of the area factor, and can realize point load testing on irregular rock samples, thereby improving measurement accuracy and testing efficiency. It can also be used to test different types of rock samples, and has strong applicability.

Claims

1. A rapid point load testing method for irregular rock samples based on digital technology, characterized by: The steps include: Select irregular specimens of natural rock, conduct point load tests, obtain the failure specimens after loading and splitting, and obtain the specimen failure load P; The camera synchronously captures the left and right perspective images of the damaged sample on the cleavage surface of the damaged sample and transmits them to the control module, which uses the camera parameters to perform image correction on the left and right perspective images of the damaged sample; The image of the damaged sample is processed for splitting surface extraction to obtain splitting surface features, and the SGM algorithm is used for stereo matching to obtain the view difference, realize triangulation reconstruction of the splitting surface, and obtain the triangulated reconstruction model of the splitting surface of the damaged sample; The projection surfaces are respectively established in the triangulated reconstruction model of the splitting surfaces of the two damaged specimens, and the splitting surfaces of the damaged specimens are projected. The average projection area of the triangulated reconstruction model of the splitting surfaces of the two damaged specimens is calculated. As the calculation area A, according to the failure load P corresponding to the failure specimen and the calculation area A, the load intensity index I of the failure specimen point is calculated. S1 ; Repeat the above steps to obtain the point load strength index I of multiple irregular samples of the same type of rock Si , where i = 1, 2, 3, 4...n, calculate the load intensity index I of multiple test points Si The average value of the same type of rock is recorded as the point load intensity index.

2. The method for rapid point load testing of irregular rock samples based on digital technology according to claim 1 is characterized in that: The triangulation reconstruction process is as follows: the obtained disparity map is processed, the depth of each pixel point and the corresponding three-dimensional coordinates in the real world are calculated through the disparity map, the three-dimensional coordinates of each pixel point in the sample cleavage surface feature are input into the computer software, and the triangulation facets are generated by the Poisson reconstruction method to perform triangulation reconstruction of the cleavage surface of the destroyed sample.

3. The method for rapid point load testing of irregular rock samples based on digital technology according to claim 2 is characterized in that: The step of obtaining the calculated area A is as follows: in the triangulated reconstruction model of the sample splitting, the XY plane of the corresponding three-dimensional coordinate system is rotated around the Y axis in sequence by a set angle to establish multiple target projection surfaces, and the calculated area A of each target projection surface of the sample splitting three-dimensional model is obtained respectively. c , multiple calculation areas A c Statistical calculation of mean and variance, taking the projection calculation area when the variance is minimum, and the mean calculation area of the projection of the triangulated reconstruction model of the splitting surface of the two damaged specimens The cleavage surface area A of the real failure specimen is taken as the cleavage surface area A of the real failure specimen.

4. The method for rapid point load testing of irregular rock samples based on digital technology according to claim 3 is characterized in that: The calculated area A of the cleavage surface of the destroyed specimen c The acquisition method is as follows: Based on a target projection surface, each triangular facet of the surface of the three-dimensional model of the damaged sample is projected onto the target projection surface, and the corresponding two-dimensional triangles are obtained respectively. The area of each two-dimensional triangle is calculated, and the area of each two-dimensional triangle is accumulated to obtain the calculated area A of the cleavage surface of the damaged sample. c .

5. The method for rapid point load testing of irregular rock samples based on digital technology according to claim 1 is characterized in that: The point load strength I Si The index is calculated as follows: Where P is the failure load and a is the area of the cleavage surface of the failure specimen.

6. A device for rapid point load testing of irregular rock samples based on digital technology, applied to the method for rapid point load testing of irregular rock samples based on digital technology according to any one of claims 1 to 5, characterized in that: The invention comprises a point load tester, wherein a guide plate is slidingly provided on the point load tester, an upper pressure head is telescopically provided on the upper part of the point load tester, a lower pressure head is fixedly provided on the guide plate, receiving components are symmetrically provided on both sides of the guide plate, the receiving components include a support plate and a buffer plate, the middle part of the support plate is connected to the buffer plate by a spring, an adjustment component is installed above the support plate, the adjustment component includes a movable moving part, the moving part is driven by a gear rack mechanism to move in a direction close to or away from the lower pressure head, a mounting plate is rotatably provided on the moving part, cameras are rotatably provided at both ends of the mounting plate, the mounting plate adjusts its relative position with the sample through gear transmission, and two cameras shoot the damaged sample from the left and right angles of the sample.

7. The device for rapid point load testing of irregular rock samples based on digital technology according to claim 6 is characterized in that: The receiving assembly also includes a mounting piece, which is plugged into the side of the guide plate. Both ends of the lower end of the mounting piece are threaded with rotating screws that contact the guide plate. The upper surface of the mounting piece is fixedly connected to the support plate, and a pad is fitted on the upper surface of the buffer plate.

8. The device for rapid point load testing of irregular rock samples based on digital technology according to claim 6 is characterized in that: The adjusting assembly also includes an adjusting part, which is fixedly arranged above the support plate. The adjusting part is threadedly connected to the moving part through a horizontally rotating screw rod. A slot is provided on the side of the adjusting part facing the lower pressure head. A movable part is slidingly arranged in the middle of the upper surface of the moving part. A moving gear is rotatably arranged on one side of the movable part. A moving rack is fixedly arranged on one side of the upper surface of the moving part and is vertically arranged with the screw rod. The moving rack is meshed with the moving gear.

9. The device for rapid point load testing of irregular rock samples based on digital technology according to claim 8, characterized in that: A rotating block is fixedly provided on one side of the movable part facing the lower pressure head. The rotating block is rotatably connected to a rotating ear fixedly provided on the middle part of the mounting plate, and the mounting plate is rotated by a gear transmission structure.

10. The device for rapid point load testing of irregular rock samples based on digital technology according to claim 6, characterized in that: It also includes a control module, an image processing module, a three-dimensional reconstruction module and a strength calculation module. The control module coordinates the actions of the image processing module, the three-dimensional reconstruction module and the strength calculation module; the control module is electrically connected to the camera, and the control module is also electrically connected to the point load tester.

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