A three-dimensional laser scanning method for monitoring and evaluating the stability of high-stage pillars in mines.

Abstract

This invention provides a three-dimensional laser scanning method for monitoring and evaluating the stability of high-stage pillars in mines. The method includes: constructing an internal and external control network and fixed splicing targets for the pillar; collecting point clouds from multiple roadways and preprocessing them; rigidly registering the multi-stage point clouds using target constraints and an iterative nearest-point algorithm; extracting monitoring sections and calculating five deformation indices; normalizing the indices based on allowable deformation thresholds; reconstructing the vertical profile deformation field using Kriging interpolation; calculating the area ratio of hazardous zones; generating a comprehensive stability index based on combined weights and identifying the dominant indices; classifying stability according to the index and triggering graded early warnings. This invention comprehensively evaluates the stability of high-stage pillars and implements an early warning mechanism based on the evaluation results to promptly identify potential risks, ensure the safety of underground workers, and guarantee the efficient and stable operation of mining.

Description

Technical Field

[0001] This invention belongs to the field of research on the stability of high-stage pillars in deep metal mines, and more specifically relates to a three-dimensional laser scanning method for monitoring and evaluating the stability of high-stage pillars in mines. Background Technology

[0002] In recent years, the development of deep metal mineral resources has gradually shifted from traditional mining methods such as open-cut and caving methods to backfill mining methods using large-scale structural parameter stopes, aiming to achieve large-scale mining, improve ore recovery rates, and protect the ecological environment. This shift is towards higher stages, higher subdivisions, larger scale, and trackless operation. For example, in the high-stage cemented backfill mining method, the stage height (the vertical distance between two adjacent stage transport roadways) generally exceeds 80 m, reaching a maximum of 120 m. This mining method typically involves two steps: dividing the stope and pillars along the strike perpendicular or parallel to the ore body; the first step involves mining the stope to form a high-stage pillar; immediately after mining the high-stage stope, backfilling is performed; and the second step involves mining the pillar again. High-stage pillars are not only key units supporting large-scale structural stopes in deep metal mines but also recoverable resources. The instability and failure of high-stage pillars inevitably leads to changes in the mechanical state of the stope, and may even affect the stability of the entire goaf. Furthermore, the failure of any high-stage pillar supporting a deep underground mining system can easily trigger a domino effect, often resulting in widespread and regional damage to the surrounding rock of large-scale stopes in deep metal mines, such as large-scale roof collapses. Therefore, research on methods for monitoring and assessing the stability of high-stage pillars in deep mines is urgently needed. Traditional methods for monitoring and assessing the stability of high-stage pillars in deep mines typically focus only on changes on the pillar surface. However, due to the significant height of pillars in deep metal mines and the need for rapid backfilling of adjacent stops after mining, traditional monitoring methods face considerable challenges in the placement and construction of monitoring points on the surface of high-stage pillars. Furthermore, after stope backfilling, traditional methods often fail to provide effective and timely monitoring. This paper proposes a method for assessing the stability of high-stage pillars by establishing segmented roadway platforms within the high-stage pillars, enabling real-time and effective monitoring of pillar stability. More importantly, the proposed method comprehensively considers multiple indicators, including horizontal deformation, settlement deformation, deformation rate, roadway convergence, and changes in the shape of the roadway monitoring cross-section. Through this multi-indicator comprehensive evaluation, the stability of high-stage pillars in deep metal mines can be effectively assessed. This assessment method can promptly identify potential risks, ensure the safety of underground workers, and guarantee the efficient and stable operation of mining, possessing significant theoretical and practical value. Summary of the Invention

[0003] This invention, by setting up segmented roadway platforms within high-stage pillars, enables real-time and effective monitoring of pillar stability. More importantly, the proposed method for assessing the stability of high-stage pillars comprehensively considers multiple indicators, including horizontal deformation, settlement deformation, deformation rate, roadway convergence, and shape changes of the roadway monitoring section. Through this multi-indicator comprehensive evaluation, the stability of high-stage pillars in deep metal mines can be effectively assessed. This assessment method can promptly identify potential risks, ensure the safety of underground workers, and guarantee the efficient and stable operation of mining, possessing significant theoretical and practical value.

[0004] This invention belongs to the field of stability research on high-stage pillars in deep metal mines, and more specifically relates to a method for monitoring and evaluating the stability of high-stage pillars in deep mines based on three-dimensional laser scanning, which includes the following steps: Step S1: Set up benchmark control points in the stable transport roadway outside the high-stage pillar, and set up scanning control points in the segmented roadways inside the pillar. Along the surrounding rock surface of the segmented roadways, set up fixed spliced ​​targets as monitoring points at each monitoring section position; use a total station to complete the coordinate connection measurement from the external benchmark control points to the internal scanning control points; use a 3D laser scanner to perform full coverage scanning at multiple 3D laser scanning monitoring stations in the roadway to obtain point cloud data, and scan each roadway cyclically until the entire segmented roadway of the high-stage pillar is covered; Step S2: Using the cross-sectional profile of the point cloud obtained in the first monitoring cycle as a benchmark, calculate the deformation index of each monitoring section in each monitoring cycle, including: average cross-sectional displacement rate, average cross-sectional settlement difference coefficient, average cross-sectional level difference coefficient, average convergence of cross-sectional survey lines, and cross-sectional shape area change rate. Step S3: According to the allowable upper limit threshold of each deformation index in the mine safety regulations. Compared with the theoretical minimum value The deformation indices obtained in step S2 are normalized to obtain dimensionless normalized deformation index values. Step S4: Input the normalized deformation index values ​​of each monitoring section within the high-stage pillar into the Kriging interpolation algorithm to generate a deformation index contour map within the vertical profile of the high-stage pillar. Within the vertical profile, delineate dangerous areas based on contour thresholds and calculate the area ratio of dangerous areas. Combine this with preset weighting coefficients to calculate the weighted value of the dangerous area ratio of each deformation index, thus obtaining the dominant index S. The vertical profile is a plane with the vertical direction and the roadway axis as coordinate axes. Step S5: Stability Classification and Early Warning: The stability of high-stage pillars is classified using the dominant indicator S, establishing a three-level stability evaluation standard. Level I: S < 0.4; Level II: 0.4 ≤ S < 0.6; Level III: 0.6 ≤ S < 1; An early warning is triggered based on the stability classification results.

[0005] Furthermore, in step S1, the number of reference control points and scanning control points is not less than 3; the monitoring sections are set in the stress concentration zone of the high-stage pillar, the abrupt change zone of the surrounding rock structure, or the section with obvious signs of deformation and damage, and the spacing between adjacent monitoring sections along the roadway axis is 6 m to 10 m.

[0006] Furthermore, in step S1, five spliced ​​targets are symmetrically arranged along the contour of each monitoring section as monitoring points. The positions are located at the left side, left arch shoulder, arch center, right arch shoulder and right side, and are numbered 1 to 5 in a clockwise direction.

[0007] Furthermore, in step S1, the overlapping common area scanned by two adjacent three-dimensional laser scanning monitoring stations accounts for no less than 30% of the scanning field of view of each three-dimensional laser scanning monitoring station, and the scanning resolution is configured such that the average point spacing of the effective point cloud is no greater than 10 mm.

[0008] Furthermore, in step S1, the scanning control point and monitoring point use pre-embedded metal expansion bolts as permanent observation marks, and the exposed end of the bolt is equipped with a detachable and replaceable reflective component. The reflective component includes a prism base for total station joint measurement and a spherical target or planar target for three-dimensional laser scanning. The prism base and the scanning target are adapted and replaceable through the same threaded interface. When performing joint measurement from the reference control point to the scanning control point, a prism mount is installed on the exposed end of the metal expansion bolt at the scanning control point; when using a 3D laser scanner to scan the roadway, a spherical target or a planar target is installed on the exposed end of the metal expansion bolt at the scanning control point and the monitoring point as a reflective target. If, during installation, the center of the reflective target and the prism center of the prism mount are not concentric with the axis of the pre-embedded bolts or cannot be vertically aligned, perform three-dimensional eccentricity correction according to the following steps: (1) Install prism mounts and reflective targets alternately at the exposed ends of metal expansion bolts at the scanning control points. Obtain the offset of the center of the reflective target relative to the center of the prism in the (X, Y, Z) axes by using precision measuring tools to pre-calibrate or calibrate the tooling. ; (2) Screw the prism mounts for connecting the reference control point and the scanning control point onto the exposed ends of the metal expansion bolts at the scanning control points. Using a total station, starting from the external reference control point, perform coordinate connection measurements on the scanning control points of each internal segment of the roadway to obtain the prism center coordinates of each scanning control point. Based on the measured offset, the coordinates of the center of the reflecting target are calculated as follows: (3) The corrected coordinates of the center of the reflective target As a unified spatial reference control point coordinate.

[0009] Furthermore, in step S2, the three-dimensional coordinates of the l-th roadway, the m-th monitoring section, and the i-th monitoring point during the t-th monitoring cycle are: in: For radial coordinates, the direction is perpendicular to the radial direction of the higher-stage pillar roadway. Positive coordinates point in the direction of stope advancement, and negative coordinates point outwards. For axial coordinates, the direction along the tunnel axis and pointing towards the end of the scan is positive, and the opposite direction is negative; The direction is a vertical coordinate, along the vertical axis, with downward being negative and upward being positive; The tunnels inside the high-stage pillar are numbered from bottom to top. ; The monitoring section number is assigned to each individual roadway from the scanning control point to the other end. ; Number the monitoring points of the artificial reflective target on each monitoring section. .

[0010] Further, in step S2, the deformation index is obtained using the following steps: (1) Average displacement rate of cross section: monitoring points In the Subsequent The three-dimensional displacement change during the next scan is: The total displacement during scanning between adjacent cycles is: The cross-sectional displacement deformation rate between adjacent monitoring cycles is: in, Indicates the first Next and first Displacement rate between monitoring cycles; This represents the time difference between two monitoring cycles; The average displacement rate of the m-th monitoring section for: (2) No. The average settlement difference coefficient of the m-th monitoring section in the upper and lower adjacent roadways in the next monitoring cycle is: in, and These are the average cross-sectional settlement deformation values ​​of the m-th monitoring section of two adjacent roadways, respectively. It is the vertical distance between two adjacent lanes; (3) No. The average level difference coefficient of the m-th monitoring section in adjacent roadways of the next monitoring cycle is: in, and These are the average horizontal deformation values ​​of the m-th monitoring section of two adjacent roadways, respectively. (4) No. During the scanning process, the convergence of each cross-sectional survey line of the monitoring section is obtained sequentially. The convergence of each cross-sectional survey line is the length of the cross-sectional survey line at the t=0th scan and the length of the cross-sectional survey line at the t=0th scan. The difference in length during the first scan is summed by the convergence of all cross-sectional survey lines to obtain the first... Average convergence of cross-sectional survey lines during each scan: The cross-sectional survey lines include the lines connecting the left side and the center of the arch crown, the left side and the right shoulder, the left side and the right side, the left shoulder and the right side, and the center of the arch crown and the right side. (5) No. During each scan, the rate of change of the cross-sectional shape and area of ​​the monitored section was: in, For the first During each scan, the change in the shape and area of ​​the monitored cross-section relative to the initial time point is measured. The initial cross-sectional shape and area are obtained from the initial time point scanning data. Both are calculated by extracting the cross-sectional boundary points using a point cloud spatial contour fitting algorithm and using a polygon area integral model.

[0011] Furthermore, in step S3, the normalization formula is as follows: in, For the first The deformation values ​​at each monitoring point are normalized values ​​between 0 and 1.

[0012] Furthermore, in step S3, for areas where no monitoring section covers the top of high-stage pillars, the normalized index value is extrapolated and corrected using the normalized index values ​​of adjacent monitored sections, and the calculation formula is as follows; in, This represents the normalized index value for the unmonitored area at the top of the higher stage. Normalized index values ​​for adjacent monitoring areas This is the correction coefficient for the normalized index value of the unmonitored area.

[0013] Further, in step S4, the formula for calculating the dominant indicator S is: in: These are the average displacement rate of the cross section, the average settlement difference coefficient of the cross section, the average level difference coefficient of the cross section, the average convergence of the cross section survey line, and the percentage of the dangerous area of ​​the cross section shape and area change rate. , , , and Let be the weighted value corresponding to each evaluation indicator, and satisfy: .

[0014] The beneficial effects of this invention are: (1) Overcoming the limitations of traditional pillar monitoring and assessment, this invention sets up segmented roadway platforms inside high-stage pillars, and uses total station joint measurement + permanent expansion bolt target + eccentric correction to ensure that multi-stage scanning data are compared under the same high-precision spatial reference, which can effectively monitor the stability of pillars in real time.

[0015] (2) The high-stage pillar stability assessment method proposed in this invention comprehensively considers multiple indicators such as horizontal deformation, settlement deformation, deformation rate, roadway convergence and shape change of roadway monitoring section. Through comprehensive assessment of multiple indicators, the stability of high-stage pillars in deep metal mines can be effectively assessed. This assessment method can promptly identify potential risks, ensure the safety of underground workers, and guarantee the efficient and stable operation of mining. It has important theoretical significance and application value.

[0016] (3) Non-contact scanning reduces the frequency of manual well entry and safety risks. Precise intervention based on key indicators avoids "over-support" or "blind advancement", significantly reducing support costs and production stoppage losses. Attached Figure Description

[0017] Figure 1 A flowchart of a three-dimensional laser scanning method for monitoring and evaluating the stability of high-stage pillars in mines; Figure 2 A schematic diagram of the layout of segmented roadways and monitoring sections for high-stage pillars in a deep metal mine. Figure 3 A diagram showing the layout of monitoring points for spliced ​​target points along the monitoring section; Figure 4 The location and average displacement rate of each monitoring section. Data chart; Figure 5 This is a screenshot of the Surfer software user interface. Figure 6 Contour plot of average displacement rate of the interrupted surface in Surfer software; Figure 7 Contour maps of the average displacement rate at each cross-section obtained from monitoring; Figure 8 Contour maps of the average settlement difference coefficients at each cross-section obtained from monitoring. Figure 9 Contour maps of the average level difference coefficients for each cross-section obtained from monitoring; Figure 10 Contour maps of the average convergence of the survey lines at each cross-section obtained from monitoring; Figure 11 Contour maps showing the rate of change of shape and area of ​​each cross-section obtained from monitoring.

[0018] in Figure 5 and Figure 6 In the diagram, Grid Data is the grid data button, Contour is the contour plot button, GriddingMethod is the grid division method, Kriging is the Kriging interpolation method, X Direction is the X-axis, Y Direction is the Y-axis, Column represents the column, and Grid Report is the grid report. The remaining parts are unrelated to step S05 of this invention or are default settings, and will not be explained in this invention. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of the embodiments of this disclosure clearer, the technical solutions of the embodiments of this disclosure will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this disclosure. All other embodiments obtained by those skilled in the art based on the described embodiments of this disclosure without creative effort are within the scope of protection of this disclosure.

[0020] Example 1

[0021] Combination Figure 1This embodiment provides a method for constructing an external benchmark and internal scanning control network for a high-stage pillar. The specific steps are as follows: S01. At least 3 benchmark control points shall be set up in the stable transport roadway outside the high-stage pillar, and at least 3 scanning control points shall be set up in the stable deformation zone of the surrounding rock in each segment roadway inside the pillar. Fixed splicing targets shall be accurately arranged at each monitoring section along the surface of the surrounding rock of the segment roadway, and the spacing between adjacent monitoring sections along the roadway direction shall be 8 m.

[0022] like Figure 2 The diagram shows the layout of the segmented roadways and monitoring sections of a high-stage pillar in a deep metal mine. The high-stage pillar is set to have a length × width × height of 60 m × 20 m × 80 m. The high-stage pillar has 4 segmented roadways, located at the bottom, 20 m, 40 m and 60 m height respectively. like Figure 3 As shown, five spliced ​​targets are symmetrically set as monitoring points on each monitoring section, located on the left and right sides, left and right shoulders, and the center line of the arch. The monitoring points are numbered starting from the left side and proceeding clockwise. Points 1 to 5 correspond to the left side, left shoulder, center of the arch, right shoulder, and right side, respectively, thus constructing a monitoring network for the convergence of the two sides and the roof of the roadway.

[0023] The scanning control points and monitoring points use pre-embedded metal expansion bolts as permanent observation markers. The exposed ends of the bolts are equipped with detachable and replaceable reflective components. These reflective components include a prism mount for total station measurements and a spherical or planar target for three-dimensional laser scanning. The prism mount and the scanning target are interchangeable via the same threaded interface. When measuring the connection between the reference control point and the scanning control point, a prism mount is installed at the exposed end of the metal expansion bolt at the scanning control point. When using a three-dimensional laser scanner to scan the tunnel, a spherical or planar target is installed at the exposed end of the metal expansion bolt at the scanning control point and monitoring point as a reflective target.

[0024] After installation, the center of the reflective target and the center of the prism mount should be concentric with the axis of the pre-embedded bolt and aligned in vertical elevation. When there is installation eccentricity between the center of the reflective target and the center of the prism, three-dimensional eccentricity correction should be performed. The specific steps are as follows: (1) Install prism mounts and reflective targets alternately at the exposed ends of metal expansion bolts at the scanning control points. Obtain the offset of the center of the reflective target relative to the center of the prism in the (X, Y, Z) axes by using precision measuring tools to pre-calibrate or calibrate the tooling. ; (2) Screw the prism mount for connecting the reference control point and the scanning control point onto the exposed end of the metal expansion bolt at the scanning control point. Use a total station to connect the coordinates of the scanning control points of each section of the internal roadway from the external reference control point.

[0025] The prism center coordinates of each scanning control point are obtained as follows: Based on the measured offset, the coordinates of the center of the reflecting target are calculated as follows: (3) The corrected coordinates of the center of the reflective target The coordinates of the unified spatial reference control points are used for subsequent multi-stage point cloud splicing and registration, and cross-sectional deformation calculation.

[0026] A 3D laser scanner is used at multiple 3D laser scanning monitoring stations within the roadway to perform a full-coverage scan of multiple scanning control points and monitoring points, acquiring point cloud data. After completing one scanning control point and monitoring point, the process moves to the next, until the scanning of one roadway within the high-stage pillar is completed. After each roadway is scanned, the same steps are followed for the next roadway, until all roadways within the high-stage pillar are scanned. S02. Import the point cloud data into the processing software and remove flying points, noise points and redundant point clouds. The total station introduces the coordinates of the scanning control points through the reference control points, establishes the monitoring coordinate system and defines the coordinate parameters of the monitoring points. Based on the monitoring points and the scanning control points, the rigid registration and stitching of the point clouds in each monitoring cycle are completed to generate a complete three-dimensional point cloud under a unified coordinate system. Where the baseline period is set to t=0, the three-dimensional coordinates of the l-th roadway, the m-th monitoring section, and the i-th monitoring point in the t-th monitoring cycle are: in: The direction is perpendicular to the axis of the higher-stage pillar roadway, with the side pointing towards the direction of stope advancement being positive and the other side being negative; The direction is along the tunnel axis, with the direction pointing towards the last scanned section being positive and the opposite direction being negative; The direction is vertically downwards, with downwards being negative and upwards being positive; The tunnels inside the high-stage pillar are numbered from bottom to top. ; The monitoring section number is assigned to each individual roadway from the scanning control point to the other end. ; Number the monitoring points of the artificial reflective target on each monitoring section. .

[0027] The requirements for the arrangement of multiple 3D laser scanning monitoring stations are as follows: multiple 3D laser scanning monitoring stations should be set up in the roadway during scanning to achieve continuous coverage of the roadway surrounding rock surface. The proportion of the overlapping common area scanned by two adjacent 3D laser scanning monitoring stations to the scanning field of view of each 3D laser scanning monitoring station (i.e., the overlap rate) should not be less than 30%. The scanning resolution should ensure that the average point distance of the effective point cloud does not exceed 10 mm.

[0028] S03. Based on the cross-sectional profile of the first phase point cloud, calculate the normal projection distance between the current phase cross-sectional profile and the reference cross-sectional profile, the spatial coordinate offset of the feature points, and the change of the cross-sectional geometric area. Extract the deformation index of each monitoring section, including: the average displacement rate of the cross-section, the average settlement difference coefficient of the cross-section, the average level difference coefficient of the cross-section, the average convergence of the cross-sectional survey line, and the change rate of the cross-sectional shape area; (1) The method for determining the average displacement rate of the cross-section is as follows: monitoring points In the Subsequent During the second scan, monitoring points The three-dimensional displacement change is as follows: The total displacement (i.e., the distance in three-dimensional space) during scanning between adjacent cycles is: The cross-sectional displacement deformation rate between adjacent monitoring cycles is: in, Indicates the first Next and first Displacement rate between monitoring cycles; This represents the time difference between two monitoring cycles.

[0029] Then the average displacement rate of the m-th monitoring section for: (2) No. The average settlement difference coefficient of the m-th monitoring section in the upper and lower adjacent roadways in the next monitoring cycle is: in, and These are the average values ​​of cross-sectional settlement deformation of the m-th monitoring section of two adjacent roadways. It is the vertical distance between two adjacent lanes.

[0030] (3) No. The average level difference coefficient of the m-th monitoring section in adjacent roadways of the next monitoring cycle is: in, and These are the average horizontal deformation values ​​of the m-th monitoring section of two adjacent roadways, respectively. It is the vertical distance between two adjacent lanes.

[0031] (4) For the five measuring lines of each monitoring section (numbered 1 to 3, 1 to 4, 1 to 5, 2 to 4, and 3 to 5 respectively), taking the convergence of measuring lines 1 to 3 as an example, calculate the first... Average convergence of cross-sectional survey lines during each scan: in For the initial time point ( The distance between monitoring point 1 and monitoring point 3, where The distance between monitoring point 1 and monitoring point 3 during the t-th scan: Then the first The average convergence of the cross-sectional survey lines monitored during each scan is: if A value greater than 0 indicates that the cross-section is shrinking.

[0032] (5) No. During each scan, the rate of change of the cross-sectional shape and area of ​​the monitored section was: in, For the first During the second scan, the shape of the monitored section relative to the initial time point ( The change in shape area (=0) was obtained by precise measurement using a CAD system through 3D point cloud data. The specific calculation process is as follows: In the first... During the second scan, the actual shape of each monitoring section is first obtained through three-dimensional point cloud data and compared with the initial time point ( =0) Compare the shapes of the same monitoring section and calculate the change in shape area between the two scans; Through the initial time point ( =0) The initial cross-sectional shape and area obtained from the scan data.

[0033] S04. Based on the allowable upper limit threshold of each deformation index. and minimum value The deformation indices are normalized using the following formula: in, For the first The deformation index values ​​at the time of monitoring were normalized to between 0 and 1. =0 indicates that the deformation index is in the most stable state; =1 indicates that the deformation index has reached the dangerous state of the allowable deformation limit.

[0034] The normalized deformation index value of the unmonitored area at the top of the high-stage pillar is obtained by correcting the normalized index value of the adjacent monitoring area. The calculation formula is as follows: in, This represents the normalized deformation index value for the unmonitored area at the top of the high-stage pillar. The normalized deformation index values ​​are those of adjacent monitoring areas. Here, the correction coefficient for the normalized deformation index value of the unmonitored area is... Take 1.

[0035] S05. Import the normalized deformation index data into Surfer software, use Kriging interpolation to perform interpolation calculations on the deformation indexes of each monitoring section, generate contour maps, and set the generated contour lines of each deformation index.

[0036] For example in Figure 5 In the Surfer software interface shown, click the Grid Data button to import data such as... Figure 4 The locations and average displacement rates of each monitoring section are shown. Then click the contour map button (Contour) to bring up a dialog box. In the dialog box, specify the x-axis data of the contour map as... Figure 4 Column A represents the distance from the monitoring section to the starting end of the segmented roadway. The data on the y-axis is specified as... Figure 4 Column B represents the segmented tunnel height, with the z-axis data specified as... Figure 4 average cross-sectional displacement rate In the Gridding Method section, select Kriging interpolation. Modify the minimum and maximum values ​​for the X-axis to 0 and the length of the high-level pillar, respectively. Similarly, modify the minimum and maximum values ​​for the Y-axis to 0 and the length of the high-level pillar, respectively. Then click the Grid Report option and the OK button to generate the report. Figure 6 The contour lines showing the average displacement rate of the cross section are shown.

[0037] The location of each monitoring section includes the height of the segment roadway represented by column B and the distance from the monitoring section to the starting end of the segment roadway represented by column A. Based on the above operations and the generated contour map, the danger zone of the high-stage pillar profile is divided, and the danger zone is calculated. =0.6~1) is the proportion of the total high-stage pillar profile area, according to Figures 7-11 The results showed that the average displacement rate of the cross section, the average settlement difference coefficient of the cross section, the average level difference coefficient of the cross section, the average convergence of the cross section survey line, and the proportion of the dangerous area of ​​the cross section shape and area change rate were 0.50, 0.19, 0.04, 0.57, and 0.56, respectively.

[0038] By setting the weights of each monitoring indicator and multiplying the area proportion of the dangerous zone of each indicator by its corresponding weight, the dominant indicator S of the risk index for the overall stability assessment of the high-stage pillar is obtained. in: It serves as the leading indicator of the comprehensive hazard index for high-stage pillar stability assessment; These are the average displacement rate of the cross section, the average settlement difference coefficient of the cross section, the average level difference coefficient of the cross section, the average convergence of the cross section survey line, and the percentage of the dangerous area of ​​the cross section shape and area change rate. , , , and The weighted values ​​for each evaluation indicator are given, and the following conditions are met: Let the weighted values ​​for the average displacement rate of the cross-section, the average settlement difference coefficient of the cross-section, the average level difference coefficient of the cross-section, the average convergence of the cross-section survey lines, and the rate of change of cross-section shape and area be 0.25, 0.15, 0.15, 0.25, and 0.20, respectively. The calculated values ​​are: S06. Using the dominant index S, stability classification of high-stage pillars is performed, and a three-level stability evaluation standard is established: Level I (basically stable): S < 0.4; Level II (Unstable): 0.4 ≤ S < 0.6; Level III (Hazardous): 0.6≤S<1. Based on the evaluation results, yellow, orange, and red level warnings are triggered, and corresponding control measures such as intensified monitoring, temporary support reinforcement, or cessation of mining and evacuation of personnel are initiated to achieve dynamic assessment of the stability of the high-stage pillar and closed-loop control of risks.

[0039] Therefore, the stability of the high-stage pillars in deep metal mines is understability. An early warning mechanism is implemented based on the assessment results to promptly identify potential risks, ensure the safety of underground workers, and guarantee the efficient and stable operation of mining.

[0040] Although the above embodiments have described the present invention and its implementation in detail, it should be noted that for those skilled in the art, any changes, modifications, substitutions, combinations, simplifications, etc., made to the corresponding conditions without departing from the technical principles of the present invention should be considered as equivalent substitutions, and these improvements should also be considered within the scope of protection of the present invention.

Claims

1. A three-dimensional laser scanning mine high-stage pillar stability monitoring and evaluation method, characterized in that, Includes the following steps: Step S1: Set up benchmark control points in the stable transport roadway outside the high-stage pillar, set up scanning control points in the segmented roadways inside the pillar, and set up fixed spliced ​​targets as monitoring points at each monitoring section along the surrounding rock surface of the segmented roadways; use a total station to complete the coordinate connection measurement from the external benchmark control points to the internal scanning control points. A 3D laser scanner is used to perform full-coverage scanning at multiple 3D laser scanning monitoring stations in the roadway to acquire point cloud data. The roadway is scanned cyclically until all sections of the high-stage pillar are covered. Step S2: Using the cross-sectional profile of the point cloud obtained in the first monitoring cycle as a benchmark, calculate the deformation index of each monitoring section in each monitoring cycle, including: average cross-sectional displacement rate, average cross-sectional settlement difference coefficient, average cross-sectional level difference coefficient, average convergence of cross-sectional survey lines, and cross-sectional shape area change rate. Step S3: according to the upper limit threshold of each deformation index in the mine safety regulations to the theoretical minimum value , the normalization processing is performed on each deformation index obtained in step S2 to obtain the dimensionless normalized deformation index value; Step S4: Input the normalized deformation index values ​​of each monitoring section within the high-stage pillar into the Kriging interpolation algorithm to generate a deformation index contour map within the vertical profile of the high-stage pillar. Within the vertical profile, delineate dangerous areas based on contour thresholds and calculate the area ratio of dangerous areas. Combine this with preset weighting coefficients to calculate the weighted value of the dangerous area ratio of each deformation index, thus obtaining the dominant index S. The vertical profile is a plane with the vertical direction and the roadway axis as coordinate axes. Step S5: Stability Classification and Early Warning: The stability of high-stage pillars is classified using the dominant indicator S, establishing a three-level stability evaluation standard. Level I: S < 0.4; Level II: 0.4 ≤ S < 0.6; Level III: 0.6 ≤ S < 1; An early warning is triggered based on the stability classification results.

2. The method of claim 1, wherein, In step S1, the number of reference control points and scanning control points is no less than 3; the monitoring sections are set in the stress concentration zone of the high-stage pillar, the abrupt change zone of the surrounding rock structure, or the section with obvious signs of deformation and damage, and the spacing between adjacent monitoring sections along the roadway axis is 6 m to 10 m.

3. The method according to claim 1, characterized in that, In step S1, five spliced ​​targets are symmetrically arranged along the contour of each monitoring section as monitoring points. The targets are located at the left side, left shoulder, center of the arch top, right shoulder and right side, and are numbered 1 to 5 in a clockwise direction.

4. The method according to claim 1, characterized in that, In step S1, the overlapping common area scanned by two adjacent three-dimensional laser scanning monitoring stations accounts for no less than 30% of the scanning field of view of each three-dimensional laser scanning monitoring station, and the scanning resolution is configured such that the average point spacing of the effective point cloud is no greater than 10 mm.

5. The method according to claim 1, characterized in that, In step S1, the scanning control point and monitoring point use pre-embedded metal expansion bolts as permanent observation marks. The exposed ends of the bolts are equipped with detachable and replaceable reflective components. The reflective components include a prism base for total station measurement and a spherical or planar target for three-dimensional laser scanning. The prism base and the scanning target are adapted and replaceable through the same threaded interface. When performing the connection measurement from the reference control point to the scanning control point, install the prism mount on the exposed end of the metal expansion bolt at the scanning control point; When using a 3D laser scanner to scan a tunnel, spherical or planar targets are installed on the exposed ends of metal expansion bolts at the scanning control points and monitoring points as reflective targets. If, during installation, the center of the reflective target and the prism center of the prism mount are not concentric with the axis of the pre-embedded bolts or cannot be vertically aligned, perform three-dimensional eccentricity correction according to the following steps: (1) Install prism mounts and reflective targets alternately at the exposed ends of metal expansion bolts at the scanning control points. Obtain the offset of the center of the reflective target relative to the center of the prism in the (X, Y, Z) axes by using precision measuring tools to pre-calibrate or calibrate the tooling. ; (2) Screw the prism mounts for connecting the reference control point and the scanning control point onto the exposed ends of the metal expansion bolts at the scanning control points. Using a total station, starting from the external reference control point, perform coordinate connection measurements on the scanning control points of each internal segment of the roadway to obtain the prism center coordinates of each scanning control point. Based on the measured offset, the coordinates of the center of the reflecting target are calculated as follows: (3) The corrected coordinates of the center of the reflective target As a unified spatial reference control point coordinate.

6. The method according to claim 1, characterized in that, In step S2, the three-dimensional coordinates of the l-th roadway, the m-th monitoring section, and the i-th monitoring point during the t-th monitoring cycle are as follows: in: For radial coordinates, the direction is perpendicular to the axis of the higher-stage pillar roadway. Positive coordinates point in the direction of stope advance, and negative coordinates point outwards. For axial coordinates, the direction along the tunnel axis and pointing towards the end of the scan is positive, and the opposite direction is negative; The direction is a vertical coordinate, along the vertical axis, with downward being negative and upward being positive; The tunnels inside the high-stage pillar are numbered from bottom to top. ; The monitoring section number is assigned to each individual roadway from the scanning control point to the other end. ; Number the monitoring points of the artificial reflective target on each monitoring section. .

7. The method according to claim 6, characterized in that, In step S2, the deformation index is obtained through the following steps: (1) Average displacement rate of cross section: monitoring points In the Subsequent The three-dimensional displacement change during the next scan is: The total displacement during scanning between adjacent monitoring cycles is: The cross-sectional displacement deformation rate between adjacent monitoring cycles is: in, Indicates the first Next and first Displacement rate between monitoring cycles; This represents the time difference between two monitoring cycles; The average displacement rate of the m-th monitoring section for: (2) No. The average settlement difference coefficient of the m-th monitoring section in the upper and lower adjacent roadways in the next monitoring cycle is: in, and These are the average cross-sectional settlement deformation values ​​of the m-th monitoring section of two adjacent roadways, respectively. It is the vertical distance between two adjacent lanes; (3) No. The average level difference coefficient of the m-th monitoring section in adjacent roadways of the next monitoring cycle is: in, and These are the average horizontal deformation values ​​of the m-th monitoring section of two adjacent roadways, respectively. (4) No. During the scanning process, the convergence of each cross-sectional survey line of the monitoring section is obtained sequentially. The convergence of each cross-sectional survey line is the length of the cross-sectional survey line at the t=0th scan and the length of the cross-sectional survey line at the t=0th scan. The difference in length during the first scan is summed by the convergence of all cross-sectional survey lines to obtain the first... Average convergence of cross-sectional survey lines during each scan: The cross-sectional survey lines include the lines connecting the left side and the center of the arch crown, the left side and the right shoulder, the left side and the right side, the left shoulder and the right side, and the center of the arch crown and the right side. Initial time point The distance between monitoring point 1 and monitoring point 3, of which The distance between monitoring point 1 and monitoring point 3 during the t-th scan; (5) No. During each scan, the rate of change of the cross-sectional shape and area of ​​the monitored section was: in, For the first During each scan, the change in the shape and area of ​​the monitored cross-section relative to the initial time point is measured. The initial cross-sectional shape and area are obtained from the initial time point scanning data. Both are calculated by extracting the cross-sectional boundary points using a point cloud spatial contour fitting algorithm and using a polygon area integral model.

8. The method according to claim 1, characterized in that, In step S3, the normalization formula is as follows: in, For the first The deformation values ​​at each monitoring point are normalized values ​​between 0 and 1.

9. The method according to claim 1, characterized in that, In step S3, for areas where no monitoring section covers the top of high-stage pillars, the normalized index value is extrapolated and corrected using the normalized index value of adjacent monitored sections. The calculation formula is as follows: in, This represents the normalized index value for the unmonitored area at the top of the higher stage. Normalized index values ​​for adjacent monitoring areas This is the correction coefficient for the normalized index value of the unmonitored area.

10. The method according to claim 1, characterized in that, In step S4, the formula for calculating the dominant indicator S is: in: These are the average displacement rate of the cross section, the average settlement difference coefficient of the cross section, the average level difference coefficient of the cross section, the average convergence of the cross section survey line, and the percentage of the dangerous area of ​​the cross section shape and area change rate. , , , and Let be the weighted value corresponding to each evaluation indicator, and satisfy: .

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