Method for Measuring Flatness of Bench Blasting Floor Based on 3D Laser Scanning

Abstract

The present invention discloses a method for measuring the flatness of the bottom plate of open-pit bench blasting based on three-dimensional laser scanning, which includes the following steps: collecting the coordinates of base station control points, collecting the coordinates of bottom plate boundary points, scanning the bottom plate, obtaining the initial model, obtaining the final model, obtaining the data of uneven areas, drawing the graphics of uneven areas, and calculating the proportion of uneven areas. The beneficial effects of the present invention are as follows: through the three-dimensional lidar scanner, the surface coordinate data of the bottom plate of open-pit mine bench blasting can be quickly obtained, and then using the supporting data processing software and post-processing software, the areas that do not meet the requirements are selected in combination with the flatness requirements of the floor, and the proportion of the uneven areas in the bench bottom plate is calculated. This method can effectively improve the measurement efficiency, save manpower and reduce labor intensity, and can also effectively improve the measurement accuracy. The proportion of uneven areas in the bench bottom plate can be used as the basis for judging whether it is necessary to carry out leveling work, and can be used to guide the leveling construction of the bench bottom plate when necessary.

Description

Technical Field

[0001] The present invention belongs to the measurement technology applied to engineering blasting, and relates to a method for measuring the flatness of the bottom plate of open-pit bench blasting based on three-dimensional laser scanning measurement. Background Technique

[0002] The flatness of the bottom plate of open-pit mine bench blasting refers to the uneven deviation value on the surface of the bench bottom plate, which is one of the important technical indicators for evaluating blasting quality. During the blasting construction process, due to various reasons such as inaccurate sampling results, unreasonable blast hole parameters, the drilling depth not reaching the design requirements, the failure of bottom explosives (water in the hole bottom), the initiating explosive package not being placed at the designed position, and the excavator not being able to dig and load normally, after the muck pile is dug and loaded, there are roots left on the bottom plate or the bottom plate is over-excavated, resulting in unevenness of the bottom plate, which not only affects the flatness of the bench, but also affects the quality of subsequent blasting and the loading efficiency. Therefore, it is very necessary to measure and evaluate the flatness of the bottom plate of open-pit mine bench blasting to form flatness specifications or standards, so as to ensure the quality of subsequent blasting and the loading efficiency.

[0003] Currently, there are few measuring instruments for detecting the flatness of the blasting bottom plate. Only manual visual observation or RTK is used for dot measurement. Manual visual observation is extremely inaccurate, and RTK dot measurement has low efficiency, affecting the construction progress. Based on this, the present invention proposes a method for measuring the flatness of the bottom plate of open-pit mine bench blasting based on three-dimensional laser scanning, which can effectively improve the measurement efficiency and accuracy of the flatness of the bench blasting bottom plate to accurately guide the construction. Summary of the Invention

[0004] The purpose of the present invention is to provide a method for measuring the flatness of the bottom plate of open-pit mine bench blasting based on three-dimensional laser scanning to solve the problems of low measurement accuracy and efficiency of the flatness of the bottom plate of open-pit mine bench blasting.

[0005] To achieve the foregoing purpose, the present invention adopts the following technical solutions.

[0006] A method for measuring the flatness of the bottom plate of open-pit bench blasting based on three-dimensional laser scanning includes the following steps:

[0007] S1, Acquisition of base station control point coordinates: After the muck pile of bench blasting is dug and loaded and the bottom plate is cleaned, an RTK base station is set up on the bench bottom plate, and the absolute three-dimensional coordinates of the base station control point in the mine area coordinate system are collected;

[0008] S2, Acquisition of bottom plate boundary point coordinates: Use an RTK rover to collect the absolute three-dimensional coordinates of the bench bottom plate boundary points in the mine area coordinate system;

[0009] S3, Floor Scanning: According to the range of the bench floor, use a 3D lidar scanning device to scan the enlarged area including the bench floor, and obtain the point cloud data of the enlarged area based on the enlargement of the bench floor;

[0010] S4, Initial Model Acquisition: Based on the point cloud data of the enlarged area and the coordinates of the base station control points, use the StarSolve software supporting the 3D lidar scanning device to perform point cloud data processing including coordinate transformation, filtering, and noise reduction, and obtain the initial 3D laser point cloud model including the complete bench floor range;

[0011] S5, Final Model Acquisition: Based on the absolute coordinates of the boundary points of the blasting area, use the laser point cloud post-processing software POSPac to perform cropping and thinning processing on the initial 3D laser point cloud model of the bench, and obtain the accurate 3D laser point cloud model of the bench floor;

[0012] S6, Data Acquisition of Unsmooth Areas: Based on all the point coordinates of the accurate 3D laser point cloud model of the bench floor exported by the laser point cloud post-processing software POSPac, and according to the flatness requirements of the mine bench floor, select the points that do not meet the requirements;

[0013] S7, Drawing of Unsmooth Area Graph: Use the laser point cloud post-processing software POSPac to draw the area graph that exceeds the flatness index requirements of the bench floor, and define it as the unsmooth area;

[0014] S8, Calculation of the Proportion of Unsmooth Areas: Obtain the percentage of the area of the unsmooth area in the area of the bench floor through calculation.

[0015] For the present invention adopting the foregoing technical solution, by using a 3D lidar scanner, the surface coordinate data of the bench blasting floor of an open-pit mine can be quickly obtained. Then, by using the supporting data processing software and post-processing software, combined with the flatness requirements of the floor, the areas that do not meet the requirements and the proportion of the unsmooth areas in the bench floor can be selected. This method can effectively improve the measurement efficiency, save manpower, and reduce labor intensity. It can also effectively improve the measurement accuracy, so as to accurately and quickly obtain the proportion of the unsmooth areas in the bench floor, and use this as the basis for judging whether leveling work needs to be carried out. When leveling is required, it can be used to guide the leveling construction of the bench floor. Among them, since the point cloud data obtained by three-dimensional laser scanning has a large density, in order to reduce the data processing volume and improve the processing efficiency, before further processing, thinning processing of the data is required.

[0016] Preferably, in step S2, the boundary points of the bench floor refer to the points whose enclosed area formed by connecting lines can completely cover the bench floor, and these points include all the inflection points on the boundary line of the enclosed area. Ensure the accuracy of the bench boundary.

[0017] Preferably, in step S3, the three-dimensional lidar scanning device includes an airborne three-dimensional lidar scanner based on an unmanned aerial vehicle, a vehicle-mounted three-dimensional lidar scanner based on a vehicle, a tripod-mounted three-dimensional lidar scanner based on a measuring stand or a measuring station, and a hand-held three-dimensional lidar scanner based on a surveyor's hand. So as to make a reasonable selection according to actual needs, such as selecting according to the principle of the lowest comprehensive cost, selecting according to the principle of priority of construction progress, etc., to improve application flexibility.

[0018] Preferably, in step S3, the enlarged area based on the expansion of the step bottom plate refers to the area extending 10m to 50m outward from the periphery of the step bottom plate. So as to select the expansion range according to the different carrier moving speeds of the scanning device. For example, when using an unmanned aerial vehicle, it can be expanded by 30m to 50m, when using a vehicle, it can be expanded by 20m to 40m, and when using a tripod-mounted carrier or a hand-held device by a surveyor, it can be expanded by 10m to 20m, ensuring that the scanned data completely covers the step bottom plate.

[0019] Preferably, the measurement accuracy of the three-dimensional lidar scanning device is within ±3 cm. Ensure the accuracy of the scanning results.

[0020] Preferably, in step S4, the point cloud data processing further includes data screening, and data screening is used to eliminate the jumping points and / or bad points that do not meet the requirements. Among them, the screening methods include eliminating bad points by visual judgment method and eliminating jumping points by curve inspection method. To eliminate interference data and ensure the accuracy of the results.

[0021] Preferably, the visual judgment method refers to directly eliminating the points that are significantly deviated from the graphic area of the cross-section data point set or significantly isolated points through the graphic display terminal, and regarding them as bad points. Bad point data refers to the data that is significantly deviated from the normal value caused by environmental factors, such as external interference caused by carrier movement, surrounding construction equipment, etc.

[0022] Preferably, the curve inspection method refers to fitting a 3rd-order or 4th-order spline curve passing through the head and tail endpoints of the cross-section by the least squares method in the same vertical plane of X-Z or Y-Z, and respectively calculating the distance |d| from the intermediate point A i between the two endpoints to the spline curve, and comparing the |d| values of each distance with the given tolerance [d]. When |d|≥[d] by the visual judgment method, it is considered that A i is a jumping point and is eliminated; among them, the value of [d] is 3 cm. Jumping points refer to abnormal data caused by the calibration change of the scanning instrument itself affected by electromagnetic interference.

[0023] Preferably, in step S5, the clipping refers to selecting the initial model data of the three-dimensional laser point cloud using the boundary of the step floor formed by connecting the boundary point coordinates, so as to retain only the laser point cloud model data of the step floor part. This is to eliminate useless data, retain useful data, reduce the amount of data processing, and improve the processing efficiency.

[0024] Preferably, in step S5, the thinning process refers to extracting the laser point cloud model data after cutting at 2% - 4% of the original density, and making the number density of points between 5 points / m 2 ~10 points / m 2 Since the density of the point cloud data obtained by three-dimensional laser scanning is usually 200 points / m 2 ~250 points / m 2 , the amount of data is too large and the processing speed is slow. Therefore, through the thinning process, the amount of data processing can be reduced and the processing efficiency can be improved.

[0025] The beneficial effects of the present invention are as follows: By using a three-dimensional lidar scanner, the surface coordinate data of the open-pit mine bench blasting floor can be quickly obtained. Then, using the supporting data processing software and post-processing software, combined with the floor flatness requirements, the areas that do not meet the requirements and the proportion of the uneven areas in the bench floor are selected. This method can effectively improve the measurement efficiency, save manpower and reduce labor intensity. It can also effectively improve the measurement accuracy, so as to accurately and quickly obtain the proportion of the uneven areas in the bench floor, which is used as the basis for judging whether leveling work needs to be carried out, and when leveling is required, it is used to guide the leveling construction of the bench floor. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 is the flow chart of the present invention.

[0027] Figure 2 is a schematic diagram of the relationship between the boundary points of the open-pit bench blasting floor and the UAV flight path boundary when applying the method of the present invention.

[0028] Figure 3 is a schematic diagram of the three-dimensional laser point cloud model of the bench blasting floor obtained by applying the method of the present invention.

[0029] Figure 4 is a schematic diagram of the principle of eliminating jump points and bad points by the curve inspection method when applying the method of the present invention.

[0030] Figure 5 is a schematic diagram of the distribution of points that do not meet the flatness requirements of the bench blasting floor when applying the method of the present invention.

[0031] Figure 6 is a schematic diagram of the uneven area of the bench blasting floor drawn by applying the method of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0032] The present invention will be further described below in conjunction with the accompanying drawings, but the present invention is not limited to the scope of the described embodiments.

[0033] See Figure 1 、 Figure 2 、 Figure 3 、 Figure 4 、 Figure 5 and Figure 6 , a method for measuring the flatness of the bottom plate of open-pit bench blasting based on three-dimensional laser scanning, comprising the following steps:

[0034] S1, Acquisition of base station control point coordinates: After the bench blasting muck loading and bottom plate cleaning are completed, an RTK base station is set up on the bench bottom plate, and the absolute three-dimensional coordinates of the base station control points in the mine area coordinate system are collected;

[0035] S2, Acquisition of bottom plate boundary point coordinates: An RTK rover is used to collect the absolute three-dimensional coordinates of the bench bottom plate boundary points in the mine area coordinate system;

[0036] S3, Bottom plate scanning: According to the bench bottom plate range, plan the UAV flight route, and use the scanning device of the UAV-borne three-dimensional lidar scanner to scan the enlarged area including the bench bottom plate according to the planned route, and obtain the point cloud data of the enlarged area based on the enlarged bench bottom plate;

[0037] S4, Acquisition of initial model: Based on the point cloud data of the enlarged area and the base station control point coordinates, use the StarSolve software supporting the three-dimensional lidar scanning device to perform point cloud data processing including coordinate transformation, filtering and noise reduction, and obtain a three-dimensional laser point cloud initial model based on absolute coordinates and including the complete bench bottom plate range;

[0038] S5, Acquisition of final model: Based on the absolute coordinates of the blasting area boundary points, use the laser point cloud post-processing software POSPac to perform cropping and thinning processing on the three-dimensional laser point cloud initial model of the bench, and obtain a precise three-dimensional laser point cloud model of the bench bottom plate;

[0039] S6, Acquisition of uneven area data: Based on all the point coordinates of the precise three-dimensional laser point cloud model of the bench bottom plate exported by the laser point cloud post-processing software POSPac, and according to the flatness requirements of the mine bench bottom plate, select the points that do not meet the requirements;

[0040] S7, Drawing of uneven area graph: Use the laser point cloud post-processing software POSPac to draw the area graph that exceeds the flatness index requirements of the bench bottom plate, and define it as the uneven area;

[0041] S8, Calculation of the proportion of the uneven area: Calculate the percentage of the area of the uneven area in the area of the bench bottom plate.

[0042] Among them, in step S2, the boundary points of the step floor slab refer to the points whose enclosed area formed by connecting lines can completely cover the step floor slab, and these points include all the inflection points on the boundary line of the enclosed area.

[0043] In step S3, the enlarged area based on the expansion of the step floor slab refers to the area that extends 30m to 50m outward from the periphery of the step floor slab; the measurement accuracy of the 3D lidar scanning device is within ±3cm.

[0044] In step S4, the point cloud data processing also includes data screening, which is used to eliminate the skipped points and / or bad points that do not meet the requirements. Among them, the screening method includes eliminating bad points by the intuitive judgment method and eliminating skipped points by the curve inspection method. The intuitive judgment method refers to directly eliminating the points that are significantly deviated from the graphic area of the cross-section data point set or are significantly isolated points through the graphic display terminal, based on the graphics. Bad point data refers to the data that is significantly deviated from the normal value due to environmental factors, such as external interference caused by the movement of the carrier, surrounding construction equipment, etc. The intuitive judgment method can be judged by experienced engineers by visual observation, or the points that are significantly deviated from the graphic area of the cross-section data point set or are significantly isolated points can be eliminated by using image recognition technology.

[0045] The curve inspection method refers to fitting a 3rd-order or 4th-order spline curve passing through the two end points of the cross-section by the least square method in the same vertical plane of X-Z or Y-Z, and calculating the intermediate point A between the two end points respectively i The distance |d| from to the spline curve, and comparing the |d| values of each distance with the given tolerance [d]. When |d|≥[d] of the intuitive judgment method, it is considered that A i Is a skipped point and is eliminated; among them, the value of [d] is 3cm. Skipped points refer to abnormal data generated by the scanning instrument itself affected by electromagnetic interference. Such as Figure 4 As shown, A1 and A7 are the two end points respectively, and A2, A3, A4, A5 and A6 are all the intermediate points between the two end points.

[0046] In step S5, the cropping refers to selecting the 3D laser point cloud initial model data by using the step floor slab boundary formed by the connection of boundary point coordinates, so that only the laser point cloud model data of the step floor slab part is retained. And in this step, the thinning process refers to extracting the cropped laser point cloud model data at 2% to 4% of the original density, and making the number density of points between 5 points / m 2 ~10 points / m 2 After that.

[0047] In this embodiment, the 3D LiDAR scanning device can also be a vehicle-mounted 3D LiDAR scanner, a stand-mounted 3D LiDAR scanner based on a measuring stand or measuring station, or a handheld 3D LiDAR scanner held by a surveyor. When using a vehicle-mounted 3D LiDAR scanner, the expanded area based on the step floor can extend 20m to 40m outward from the perimeter of the step floor. When using a stand-mounted carrier or a handheld scanner, the expanded area can extend 10m to 20m outward from the perimeter of the step floor.

[0048] The following introduces a specific application case to further illustrate the application of the aforementioned method for measuring the flatness of the open-pit step blasting floor based on three-dimensional laser scanning.

[0049] Figure 1 、 Figure 2 、 Figure 3 、 Figure 4 、 Figure 5 and Figure 6 A large open-pit coal mine carried out deep hole bench blasting mining with a bench height of 12m and a target floor elevation of +680.

[0050] The first step is to set up an RTK base station on the +680 floor surface after the bench blasting and excavation and floor cleaning are completed to obtain the absolute three-dimensional coordinates of the base station control point in the mine area coordinate system;

[0051] The second step is to use RTK to collect the absolute three-dimensional coordinates of 26 boundary points of the bench blasting bottom plate in the mine area coordinate system, including the coordinates of the points at the 9 inflection points of the boundary. The range connected by all points includes the bottom plate.

[0052] The third step is to plan the drone's flight path based on the floor area of the bench blasting. The route boundary is 30 meters horizontally from the floor boundary, and the route coverage area includes the floor area line. After the route is planned, the drone-mounted 3D LiDAR scanner is used to scan the excavated floor surface in the blasting area to obtain floor surface point cloud data. The drone-mounted 3D LiDAR scanner's measurement accuracy is controlled within ±2.3 cm.

[0053] The fourth step is to import the point cloud data and the coordinates of the base station control points into StarSolve, the supporting software for the drone-mounted 3D laser radar scanner, and perform point cloud data coordinate conversion, filtering, and noise reduction to obtain a complete 3D laser point cloud model with absolute coordinates of the blasting floor. Due to changes in the calibration parameters of the 3D laser scanner and sudden changes in the measurement environment, there are "jump points" and "bad points" in the point cloud data. The "intuitive judgment method" and "curve inspection method" are used to eliminate points that do not meet the requirements.

[0054] Step 5: Import the 3D laser point cloud model of the step surface and the absolute coordinates of the boundary points of the blasting area into the POSPac, a laser point cloud post-processing software supporting the system, for cropping and thinning to obtain an accurate 3D laser point cloud model of the blasting floor; specifically, it includes opening the original laser point cloud model of the floor, inputting the boundary point coordinates, and then cropping the point cloud model along the boundary to obtain a laser point cloud model that only retains the step blasting floor; due to the large point cloud density and large data processing volume, which affect the processing efficiency, to improve the data processing efficiency, thin the point cloud density from 230 points / m 2 to 7 points / m 2 .

[0055] Step 6: Export the coordinates of all points of the point cloud model through the supporting software POSPac, and select the data points that are more than 1m higher or lower than +680m according to the flatness requirement index of the mine step floor to obtain the coordinates of the points that do not meet the flatness requirement;

[0056] Step 7: Import the coordinates of the points that do not meet the requirements into the 3D laser point cloud model of the blasting floor with complete absolute three-dimensional coordinates, and draw the area that does not meet the flatness requirement.

[0057] Step 8: Calculate the percentage of the area of the uneven area in the area of the step floor, and then judge whether it exceeds the standard according to the evaluation standard of the proportion of the uneven area of the floor. If the proportion does not exceed the standard, it is qualified; if it exceeds the standard, level the uneven area as required until the proportion of the uneven area is less than the index requirement.

[0058] The preferred specific embodiments of the present invention have been described in detail above. It should be understood that those of ordinary skill in the art can make many modifications and variations based on the concept of the present invention without creative work. Therefore, all technical solutions that can be obtained by those skilled in the art in the technical field of the present invention through logical analysis, reasoning or limited experiments based on the concept of the present invention on the basis of the prior art shall fall within the protection scope determined by the claims.

Claims

1. A method for measuring the flatness of an open-pit step blasting floor based on three-dimensional laser scanning, characterized in that: The following steps are involved: S1, base station control point coordinate acquisition: After the bench blasting pile excavation and loading is completed and the bottom plate is cleared, an RTK base station is set up on the bench bottom plate and the absolute three-dimensional coordinates of the base station control point in the mine area coordinate system are acquired; S2, bottom plate boundary point coordinate collection: Use RTK mobile station to collect the absolute three-dimensional coordinates of the step bottom plate boundary points in the mine area coordinate system; S3, bottom plate scanning: based on the range of the step bottom plate, use a 3D laser radar scanning device to scan the expanded area including the step bottom plate, and obtain point cloud data of the expanded area based on the expansion of the step bottom plate; S4, initial model acquisition: Based on the expanded area point cloud data and the coordinates of the base station control points, StarSolve software, which is compatible with the 3D laser radar scanning equipment, is used to perform point cloud data processing including coordinate conversion, filtering, and noise reduction to obtain a 3D laser point cloud initial model that includes the entire step bottom plate range; S5, final model acquisition: Based on the absolute coordinates of the boundary points of the blasting area, the laser point cloud post-processing software POSPac is used to crop and thin the initial 3D laser point cloud model to obtain a precise 3D laser point cloud model of the step bottom plate; S6, uneven area data acquisition: exporting all point coordinates of the three-dimensional laser point cloud precise model of the step floor based on the laser point cloud post-processing software POSPac, and selecting points that do not meet the flatness requirements of the mine step floor; S7, uneven area drawing: using the laser point cloud post-processing software POSPac to draw a map of the area that exceeds the flatness index requirement of the step bottom plate, and define it as an uneven area; S8, calculation of the proportion of uneven area: obtain the percentage of the uneven area to the step bottom area by calculation.

2. The method according to claim 1, characterized in that In step S2, the boundary points of the step bottom plate refer to points where the closed area formed by the connecting lines can completely cover the step bottom plate, and these points include all inflection points on the boundary line of the closed area.

3. The method according to claim 1, characterized in that In step S3, the three-dimensional laser radar scanning equipment includes an airborne three-dimensional laser radar scanner based on a drone, a vehicle-mounted three-dimensional laser radar scanner based on a vehicle, a stand-type three-dimensional laser radar scanner based on a measuring frame or a measuring station, and a handheld three-dimensional laser radar scanner based on a surveyor's hand.

4. The method according to claim 1, wherein In step S3 , the expanded area based on the step bottom plate refers to an area extending outward by 10 m to 50 m from the periphery of the step bottom plate.

5. The method according to claim 1, wherein The measurement accuracy of the three-dimensional laser radar scanning device is within ±3cm.

6. The method according to claim 1, characterized in that In step S4, the point cloud data processing also includes data screening, which is used to eliminate jump points and / or bad points that do not meet the requirements. The screening method includes eliminating bad points using an intuitive judgment method and eliminating jump points using a curve inspection method.

7. The method according to claim 6, characterized in that The intuitive judgment method refers to directly eliminating points that obviously deviate from the graphic area of the cross-sectional data point set or obviously isolated points as bad points based on the graphics through a graphic display terminal.

8. The method according to claim 6, characterized in that The curve inspection method is to use the least squares method to fit a 3rd or 4th order spline curve passing through the first and last two ends of the section in the same XZ or YZ vertical plane, and calculate the middle point A between the two end points respectively. i The distance to the spline curve is |d|, and when the |d| value of each distance is compared with the given tolerance [d], the intuitive judgment method |d| ≥ [d], then A is considered i The jumping points are eliminated; among them, the value of [d] is 3cm.

9. The method according to claim 1, characterized in that In step S5, the clipping refers to selecting the three-dimensional laser point cloud initial model data using the step bottom plate boundary formed by connecting the boundary point coordinates, so that only the laser point cloud model data of the step bottom plate portion is retained.

10. The method according to claim 1, characterized in that In step S5, the thinning process is to extract the cut laser point cloud model data at 2% to 4% of the original density, and make the point density at 5 / m after extraction. 2 ~10 pieces / m 2 between.

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