A tunnel overall large deformation measurement method and device based on laser scanning

Abstract

A tunnel overall large deformation measurement method and device based on laser scanning, relate to laser ranging and tunnel deformation measurement technical field, including: S1, through laser scanning, point cloud data of multiple period tunnel primary support section is collected and three-dimensional triangular mesh model Mp of each period is constructed; S2, the reference three-dimensional triangular mesh model M0 of tunnel primary support section is constructed; S3, the grid vertex normal vector of the reference three-dimensional triangular mesh model M0 is calculated with the grid vertex normal vector straight line; S4, the intersecting relationship list of the grid vertex normal vector straight line of M0 and Mp is obtained through the hierarchical bounding box detection algorithm; S5, the deformation of Mp is calculated according to the intersecting relationship list; S6, the deformation of other period three-dimensional triangular mesh model is subtracted from the deformation of M1, and the relative deformation of each period is obtained.The hierarchical bounding box detection algorithm of the application improves the processing accuracy of large-scale point cloud data, effectively improves the deformation analysis efficiency, and reduces the cost of tunnel deformation measurement.

Description

Technical Field

[0001] This invention relates to the fields of laser ranging and tunnel deformation measurement technology, and in particular to a method and device for measuring the overall large deformation of a tunnel based on laser scanning. Background Technology

[0002] During hard rock tunnel construction, the initial support of the tunnel is prone to large deformation due to the complex environment caused by high temperature and high ground stress. Therefore, monitoring the deformation of the initial support is crucial for tunnel construction safety and dynamic parameter design. Currently, the main monitoring contents of the initial support deformation at home and abroad are horizontal convergence and crown settlement, and traditional methods such as total stations and convergence meters are mostly used to select monitoring sections for single-point measurement. Although traditional methods have high measurement accuracy and simple processing, the deformation monitoring points are too sparse, easily affected by the stability of single measuring points, and cannot reflect the overall deformation of the tunnel's initial support.

[0003] In recent years, with the improvement of construction standards and the advancement of computer technology, the research and application of deformation monitoring technology based on tunnel 3D point cloud models has become a focus. Tunnel 3D point cloud models mainly include laser scanning point clouds and photogrammetric 3D reconstructed point clouds. The former primarily relies on lidar technology, using a laser scanner to emit laser light to acquire the 3D coordinates and reflection intensity of the surface of the object being measured. The latter achieves a similar effect to laser scanning by capturing images of the object from different perspectives and using image 3D reconstruction technology. Generally, the accuracy of point clouds constructed by laser scanning is superior to that of photogrammetric 3D reconstructed point clouds.

[0004] Deformation monitoring using tunnel point clouds is mainly carried out by comparing the spatial differences of point clouds in different time periods. This is achieved by comparing the actual tunnel contour point cloud with the design contour model in the plane, or by comparing point clouds from different periods pairwise. The distance differences between the point clouds or models are calculated using specific methods such as ICP registration, M3C2 method, or Hausdorff distance calculation, thereby obtaining the relative displacement difference between the two.

[0005] However, existing laser scanning monitoring methods have many limitations: on the one hand, existing methods mostly extract fitted two-dimensional cross sections from the laser point cloud data of the tunnel's initial support for deformation analysis, which cannot fully reflect the true overall three-dimensional deformation characteristics of the tunnel; on the other hand, existing methods mostly use point cloud registration for point cloud comparison, which has low accuracy when the overall deformation of the tunnel is large; in addition, the laser point cloud data of the tunnel's initial support is usually large in volume, and existing methods lack optimization for processing large-scale point cloud data, resulting in relatively low efficiency in deformation analysis.

[0006] Therefore, under this background, there is an urgent need to propose a method and device for measuring the overall large deformation of tunnels based on laser scanning to solve the above-mentioned technical problems. Summary of the Invention

[0007] To address the aforementioned technical problems in related technologies, this invention proposes a method and apparatus for measuring the overall large deformation of tunnels based on laser scanning.

[0008] In a first aspect, the present invention provides a method for measuring the overall large deformation of a tunnel based on laser scanning, comprising the following steps:

[0009] S1. Point cloud data of the initial support section of the target tunnel at different times in phase P are collected by laser scanning. The construction coordinate system is transformed for each phase of point cloud data and a three-dimensional triangular mesh model Mp is constructed for each phase; where p=1,2,3,...,P;

[0010] S2. Based on the tunnel initial support outline design drawing and the design tunnel center axis, construct a reference three-dimensional triangular mesh model M0 for the target tunnel initial support section;

[0011] S3. Calculate the mesh vertex normal vector N and the mesh vertex normal vector line L of the reference three-dimensional triangular mesh model M0;

[0012] S4. Obtain the intersecting triangular facets of the reference 3D triangular mesh model M0 and each period 3D triangular mesh model Mp through the hierarchical bounding box detection algorithm, thereby obtaining the intersection relationship list of each period 3D triangular mesh model Mp.

[0013] S5. Calculate the deformation of the three-dimensional triangular mesh model Mp for each period based on the list of intersection relationships of the three-dimensional triangular mesh model Mp for each period.

[0014] S6. Subtract the deformation of the three-dimensional triangular mesh models of other periods (excluding the first period) from the deformation of the three-dimensional triangular mesh model M1 of the first period to obtain the deformation of the three-dimensional triangular mesh models of other periods relative to the three-dimensional triangular mesh model M1 of the first period.

[0015] Specifically, the hierarchical bounding box detection algorithm in step S4 includes the following steps:

[0016] S41. Calculate the bounding boxes for all triangular mesh faces of each period's 3D triangular mesh model Mp to obtain the original bounding box set;

[0017] S42. Take the original bounding box set as the root node, and calculate the bounding box containing the original bounding box set as the root node. Then, take the root node as the current node, recursively divide the bounding box set in the current node according to the direction of the longest axis of the current node's bounding box as the splitting axis, and divide the bounding box set in the current node according to the median position of the centroid coordinates of the bounding box to obtain the hierarchical bounding box of the binary tree structure.

[0018] S43. Starting from the root node of the hierarchical bounding box, select two child nodes of the root node, and check whether the bounding box of the child node intersects with the line L of the mesh vertex normal vector of the reference three-dimensional triangular mesh model M0. If they intersect, add the child node to the intersection detection table.

[0019] S44. Take out the nodes in the intersection detection list in sequence and perform intersection tests: If the node is a leaf node, perform a line-triangle intersection test on all triangular mesh faces contained in the leaf node; otherwise, check whether the bounding box of the node's child nodes intersects with the line L of the mesh vertex normal vector of the reference three-dimensional triangular mesh model M0. If they intersect, add the child node to the intersection detection list.

[0020] S45. Repeat step S44 until the intersection test of all nodes in the intersection detection list is completed, and the intersection relationship list of the three-dimensional triangular mesh model Mp for each period is obtained.

[0021] Specifically, step S42, which involves recursively dividing the bounding box set in the current node by the direction of the longest axis of the current node's bounding box as the dividing axis and by the median position of the bounding box's centroid coordinates to obtain the hierarchical bounding box of the binary tree structure, specifically includes:

[0022] During the binary search, the direction of the longest axis of the current node's bounding box is used as the splitting axis. The bounding box set of the current node is divided into two bounding box sets according to the median position of the centroid coordinates of the bounding box, and the left and right child nodes are constructed respectively. For each child node, the bounding box containing its own bounding box set is calculated, that is, the bounding box of the left child node and the bounding box of the right child node.

[0023] When the number of bounding boxes contained in a child node does not exceed a preset threshold or the recursion depth reaches the upper limit, the partitioning stops and the child node is marked as a leaf node; otherwise, the child node is treated as the current node and the recursive binary partitioning continues, eventually forming a hierarchical bounding box structure of a binary tree.

[0024] Specifically, the necessary and sufficient condition for the bounding box of the child node in step S43 to intersect the line L of the mesh vertex normal vector of the reference 3D triangular mesh model M0 is: ; The line representing the normal vector of a mesh vertex The point of minimum intersection on the three coordinate axes; The line representing the normal vector of a mesh vertex The point of maximum intersection on the three coordinate axes; where:

[0025] ;

[0026] in, Indicates the directions of the three coordinate axes in space; This represents the mesh vertex normal vector of the reference 3D triangular mesh model M0. Components on the i-axis; This represents the i-axis component of the grid vertex coordinates of the reference 3D triangular mesh model M0; The intersection point of the line L, which represents the normal vector of the mesh vertex of the reference 3D triangular mesh model M0, and the bounding box at the minimum boundary of the i-axis; The straight line representing the normal vector of the mesh vertex of the reference three-dimensional triangular mesh model M0. The point of intersection with the bounding box at the maximum boundary along the i-axis; This represents the minimum value of the bounding box along the i-axis; This represents the maximum value of the bounding box on the i-axis.

[0027] Specifically, the line-triangle intersection test in step S44 is as follows: if the following conditions are met... And if u, v, w are all greater than or equal to 0, then it is determined that the line L of the mesh vertex normal vector of the reference three-dimensional triangular mesh model M0 intersects with the line formed by the three vertices of the triangular mesh facet. The triangles formed intersect; at this point, the coordinates of the intersection points on the triangular mesh facets are... The reference 3D triangular mesh model M0 has a vertex normal vector line. Corresponding grid vertex coordinates Mesh vertex normal vector The tuple containing the vertex numbers I of the mesh is added to the intersection relation list of the 3D triangular mesh model Mp for each period; otherwise, it is considered non-intersecting, and no operation is performed; among which, is the normal vector of the triangular mesh surface; (u,v,w) are the coordinates of the centroid of the triangular mesh surface, and w=1-uv; Indicates from vertex Pointing to the vertex ; Indicates from vertex Pointing to the vertex The vector.

[0028] Specifically, the centroid coordinates of the triangular mesh facet can be obtained by solving the following linear equation:

[0029] ;

[0030] Among them, the coordinates of the intersection points on the triangular mesh facets = .

[0031] Specifically, step S2 includes:

[0032] S21. Extract the outer contour line of the initial support from the tunnel initial support outline design drawing, divide the outer contour line of the initial support into multiple segments according to the first fixed interval, and extract the division points as streamline points.

[0033] S22. Using the central axis of the designed tunnel as the trace, stretch the streamline points along the trace direction at a second fixed interval to construct a reference point cloud for the design of the initial support section of the target tunnel.

[0034] S23. Connect the reference point cloud of the initial support section of the target tunnel according to the preset connection rules to form a triangular mesh structure, and construct a reference three-dimensional triangular mesh model M0.

[0035] Specifically, step S3 includes:

[0036] The normal vector N of the mesh vertices of the reference 3D triangular mesh model M0 is the normal vector of all mesh vertices in the reference 3D triangular mesh model M0. The set of reference 3D triangular mesh model M0, where the line L is the normal vector line of all mesh vertices in the reference 3D triangular mesh model M0. The set; where, Let represent the normal vector of the s-th grid vertex; It is a straight line extending along the direction of its corresponding normal vector through the s-th grid vertex, and can be represented as: ,in The coordinates of the s-th grid vertex are represented; t represents a variable; s = 1, 2, ..., S; S is the total number of grid vertices contained in the reference 3D triangular mesh model M0.

[0037] Specifically, step S5 includes:

[0038] The coordinates of the intersection points on the triangular mesh faces in each element of the intersection relationship list of the 3D triangular mesh model Mp for each period are calculated by traversing the list. With grid vertex coordinates The Euclidean distance is used as the coordinate of MP of the 3D triangular mesh model relative to the mesh vertex coordinates in each period. The deformation of the corresponding I-th mesh vertex, that is, the deformation of the 3D triangular mesh model MP in each period, is the set of the deformations of all mesh vertices of the 3D triangular mesh model MP in each period relative to the reference 3D triangular mesh model M0.

[0039] Secondly, the present invention provides a device for measuring the overall large deformation of a tunnel based on laser scanning, and a method for measuring the overall large deformation of a tunnel based on laser scanning as described in the first aspect above, comprising the following units:

[0040] Each phase model building unit is used to collect point cloud data of the initial support section of the target tunnel at different times in phase P through laser scanning, and to transform the construction coordinate system of each phase point cloud data one by one to build a three-dimensional triangular mesh model Mp for each phase; where p=1,2,3,...,P;

[0041] Reference model building unit, used to construct a reference three-dimensional triangular mesh model M0 of the target tunnel initial support section based on the tunnel initial support outline design drawing and the design tunnel center axis;

[0042] The normal vector and line construction unit is used to calculate the mesh vertex normal vector N and the mesh vertex normal vector line L of the reference three-dimensional triangular mesh model M0.

[0043] The model intersection relationship calculation unit is used to obtain the intersecting triangular facets of the mesh vertex normal vector line L of the reference three-dimensional triangular mesh model M0 and the three-dimensional triangular mesh model Mp of each period through the hierarchical bounding box detection algorithm, thereby obtaining the intersection relationship list of the three-dimensional triangular mesh model Mp of each period.

[0044] The deformation calculation unit for each phase of the model is used to calculate the deformation of each phase of the three-dimensional triangular mesh model Mp based on the intersection relationship list of each phase of the three-dimensional triangular mesh model Mp.

[0045] The overall model deformation calculation unit is used to calculate the difference between the deformation of the three-dimensional triangular mesh models in other periods (excluding the first period) and the deformation of the three-dimensional triangular mesh model M1 in the first period, so as to obtain the deformation of the three-dimensional triangular mesh models in other periods relative to the three-dimensional triangular mesh model M1 in the first period.

[0046] The present invention provides a method for measuring the overall large deformation of tunnels based on laser scanning. This method directly processes and analyzes the overall three-dimensional laser point cloud data of the tunnel, thereby reflecting the true overall three-dimensional deformation characteristics of the tunnel more comprehensively and accurately. It avoids the loss of local information and misjudgment of deformation characteristics caused by two-dimensional cross-section analysis, and provides more reliable data support for tunnel safety assessment and deformation monitoring.

[0047] This invention provides a method for measuring the overall large deformation of tunnels based on laser scanning. It optimizes the filtering and detection algorithm for large-scale point cloud data through a hierarchical bounding box detection algorithm. The calculated normal distance represents the radial deformation of the support, ensuring consistency and sufficient accuracy between the calculated deformation and the actual monitoring measurements. This effectively overcomes the impact of large deformation on measurement accuracy, maintaining high measurement precision even when the tunnel experiences significant deformation. It accurately captures the tunnel's deformation, improving the efficiency of deformation analysis and providing timely feedback on tunnel deformation. This provides timely and effective evidence for engineering decisions, helps identify potential safety hazards and take corresponding measures, ensuring the safety of tunnel construction and operation. Furthermore, it helps reduce the overall cost of tunnel deformation measurement, minimizing rework and safety accidents caused by measurement errors, thereby indirectly reducing project costs and improving economic efficiency. Attached Figure Description

[0048] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0049] Figure 1 A schematic diagram of a method for measuring the overall large deformation of a tunnel based on laser scanning, provided in an embodiment of the present invention;

[0050] Figure 2 A schematic diagram of a three-dimensional view of the first-phase three-dimensional triangular mesh model M1 provided in an embodiment of the present invention;

[0051] Figure 3 Schematic diagrams of three-dimensional views of the second to fifth phase three-dimensional triangular mesh models provided in the embodiments of the present invention; Figure 3 (a) in the figure is a schematic diagram of the three-dimensional view of the second-phase triangular mesh model; Figure 3 (b) in the figure is a schematic diagram of the three-dimensional view of the third-phase triangular mesh model; Figure 3 (c) in the diagram is a 3D view of the fourth-phase triangular mesh model; Figure 3 (d) in the diagram is a 3D view of the fifth-phase triangular mesh model;

[0052] Figure 4 A schematic diagram of the triangular mesh structure of the reference three-dimensional triangular mesh model M0 provided in the embodiments of the present invention;

[0053] Figure 5 A schematic diagram of a three-dimensional view of a reference three-dimensional triangular mesh model M0 provided in an embodiment of the present invention;

[0054] Figure 6This is a schematic diagram of the initial support deformation cloud map for the second to fifth stages provided in the embodiments of the present invention; Figure 6 (a) in the figure is the deformation cloud diagram of the second-stage initial support relative to the first-stage initial support; Figure 6 (b) in the figure is the deformation cloud diagram of the third-stage initial support relative to the first-stage initial support; Figure 6 (c) in the figure is the deformation cloud diagram of the fourth stage initial support relative to the first stage initial support; Figure 6 (d) in the figure represents the deformation cloud diagram of the fifth-stage initial support relative to the first-stage initial support;

[0055] Figure 7 This is a schematic diagram of a tunnel overall large deformation measurement device based on laser scanning, provided as an embodiment of the present invention. Detailed Implementation

[0056] The present invention will be explained in detail through the following embodiments. The purpose of this invention is to protect all technical improvements within its scope. In the description of this invention, it should be understood that the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0057] To make the technical problems, technical solutions and advantages of the present invention clearer, a detailed description will be given below in conjunction with the accompanying drawings and specific embodiments.

[0058] Example 1

[0059] refer to Figure 1 This embodiment provides a method for measuring the overall large deformation of a tunnel based on laser scanning, including the following steps:

[0060] S1. Point cloud data of the initial support section of the target tunnel at different times in phase P are collected by laser scanning. The construction coordinate system is transformed for each phase of point cloud data and a three-dimensional triangular mesh model Mp is constructed for each phase; where p=1,2,3,...,P;

[0061] The initial support section of a tunnel refers to the section covered by shotcrete, which is applied immediately after tunnel excavation to control the deformation of the surrounding rock and ensure construction safety. This section covers the tunnel arch and sidewalls.

[0062] It is understood that in this embodiment, "initial support" is an abbreviation for "initial support," and the two have the same meaning.

[0063] LiDAR (LiDAR) acquires the three-dimensional point cloud coordinates of a target surface by emitting a laser beam and measuring the time difference of the reflected signal. This is existing technology and will not be elaborated here.

[0064] Point cloud data of the initial support section of the target tunnel at different times during phase P were collected by laser scanning, and the scanning time was recorded simultaneously, providing a basis for subsequent deformation measurement.

[0065] The transformation of the construction coordinate system for each phase of point cloud data is performed using the following formula:

[0066] ;

[0067] in, These are the spatial coordinates of the point cloud before transformation; These are the spatial coordinates after the point cloud transformation; These are the translation parameters for the X-axis, Y-axis, and Z-axis, respectively. These are the rotation parameters for the X, Y, and Z axes, respectively; m is the scaling parameter.

[0068] The above formula contains 7 unknown parameters ( , The values ​​of the parameters (m) can be obtained by solving for the coordinates of three control points. When there are more than three control points, the least squares method can be used to iteratively solve for the most probable value of the parameter.

[0069] The coordinates of the control points are obtained by the following method: during laser scanning operations, 3-5 control spheres are set up around the scanning area, and then the construction coordinates of the center of the control spheres are measured using a total station as the coordinates of the control points.

[0070] Understandably, the most probable value refers to the estimate that best approximates the true value obtained by processing multiple observation data under certain observation conditions. Simply put, it is the value that, considering all observation data and taking into account the existence of measurement errors, is considered most likely to represent the true situation.

[0071] The construction of the three-dimensional triangular mesh model can be carried out using existing software with relevant point cloud mesh reconstruction functions. Software such as COLMAP, Agisoft Metashape, and Meshroom can be used to convert the point cloud data after the construction coordinate system transformation in each phase into the corresponding three-dimensional triangular mesh model Mp; where p=1,2,3,...,P; P is the total number of phases.

[0072] refer to Figures 2-3 , Figure 2 This is a schematic diagram of a three-dimensional view of the first-phase three-dimensional triangular mesh model M1; Figure 3(a) in the figure is a schematic diagram of the three-dimensional view of the second-phase triangular mesh model; Figure 3 (b) in the figure is a schematic diagram of the three-dimensional view of the third-phase triangular mesh model; Figure 3 (c) in the diagram is a 3D view of the fourth-phase triangular mesh model; Figure 3 (d) in the diagram is a 3D view of the fifth-phase triangular mesh model; Figure 3 The portion between the two dashed lines in (a), (b), (c), and (d) represents the initial support section of the target tunnel;

[0073] S2. Based on the tunnel initial support outline design drawing and the design tunnel center axis, construct a reference three-dimensional triangular mesh model M0 for the target tunnel initial support section;

[0074] S21. Extract the outer contour line of the initial support from the tunnel initial support outline design drawing, divide the outer contour line of the initial support into multiple segments according to the first fixed interval, and extract the division points as streamline points.

[0075] refer to Figure 4 The tunnel initial support outline design drawing is the tunnel initial support design drawing. The design drawing includes the outer outline of the initial support, the inner outline of the initial support, the inner and outer outlines of the secondary lining, anchor bolts, and other data. The outer outline of the initial support can be extracted from the tunnel initial support outline design drawing and drawn using CAD software. The outer outline of the initial support is divided into multiple segments at fixed intervals, and the points of these segments are extracted as streamline points of the initial support outer outline. The first fixed interval can be adjusted according to the required calculation accuracy.

[0076] S22. Using the central axis of the designed tunnel as the trace, stretch the streamline points along the trace direction at a second fixed interval to construct a reference point cloud for the design of the initial support section of the target tunnel.

[0077] The design mileage of the target section's tunnel centerline is calculated along the design tunnel centerline at a second fixed interval. Each design mileage is then converted into construction coordinates. Using the design tunnel centerline as a trace, streamline points are copied and positioned segment by segment along the trace direction according to the design tunnel centerline construction coordinates, thus constructing a reference point cloud for the design of the target tunnel's initial support section. The second fixed interval can be adjusted according to the required calculation accuracy. The step of converting the design mileage to construction coordinates is existing technology; in this embodiment, the conversion is achieved through a surveyor's application. The aforementioned stretching step, which refers to the existing technology of copying and positioning the initial support outer contour points segment by segment along the trace direction according to the design tunnel centerline construction coordinates, can be constructed using CAD, Rhino, or other modeling software.

[0078] S23. Connect the reference point cloud of the initial support section of the target tunnel according to the preset connection rules to form a triangular mesh structure, and construct a reference three-dimensional triangular mesh model M0.

[0079] refer to Figure 5 , Figure 5 A 3D view of the reference 3D triangular mesh model M0;

[0080] Specifically, in this example, the preset connection rule is Delaunay triangulation; each triangular mesh structure in the reference 3D triangular mesh model M0 corresponds to a triangular mesh facet.

[0081] The three-dimensional triangular mesh model Mp and the reference three-dimensional triangular mesh model M0 are both piecewise linear surfaces formed by connecting multiple triangular mesh patches through edges and vertices. In essence, they approximate the surface of a continuous three-dimensional object by using a discrete set of triangular mesh patches.

[0082] S3. Calculate the mesh vertex normal vector N and the mesh vertex normal vector line L of the reference three-dimensional triangular mesh model M0;

[0083] Calculate each vertex of the reference 3D triangular mesh model M0. Mesh vertex normals Straight line with grid vertex normal vector Thus, the mesh vertex normal vector N and the mesh vertex normal vector line L of the reference three-dimensional triangular mesh model M0 are obtained;

[0084] This embodiment calculates each mesh of the reference 3D triangular mesh model M0 using the PCA algorithm. Mesh vertex normals This is existing technology and will not be elaborated further here.

[0085] It is understandable that the normal vector N of the mesh vertices of the reference 3D triangular mesh model M0 is the normal vector of all mesh vertices in the reference 3D triangular mesh model M0. The set of reference 3D triangular mesh model M0, where the line L is the normal vector line of all mesh vertices in the reference 3D triangular mesh model M0. A set;

[0086] in, Let represent the normal vector of the s-th grid vertex; It is a straight line extending along the direction of its corresponding normal vector through the s-th grid vertex, and can be represented as: ,in Represents the coordinates of the s-th grid vertex. ; Represents the X-axis coordinates of the grid vertices. Represents the Y-axis coordinate of the grid vertex. The Z-axis coordinate of the mesh vertex is represented; t represents the variable; s = 1, 2, ..., S; S is the total number of mesh vertices contained in the reference 3D triangular mesh model M0;

[0087] It is understandable that t is a real number parameter, and by changing the value of t, the straight line can be determined. The differences are as follows.

[0088] S4. Obtain the intersecting triangular facets of the reference 3D triangular mesh model M0 and each period 3D triangular mesh model Mp through the hierarchical bounding box detection algorithm, thereby obtaining the intersection relationship list of each period 3D triangular mesh model Mp.

[0089] The hierarchical bounding box detection algorithm specifically includes the following steps:

[0090] S41. Calculate the bounding boxes for all triangular mesh faces of each period's 3D triangular mesh model Mp to obtain the original bounding box set;

[0091] Calculate the minimum and maximum values ​​of the three vertices of each triangular mesh facet in each phase of the 3D triangular mesh model Mp on each coordinate axis. Then, construct the bounding box B of each triangular mesh facet based on the minimum and maximum values ​​of the three vertices on each coordinate axis, thereby obtaining the original bounding box set of each phase of the 3D triangular mesh model Mp; and save the correspondence between the bounding box B of each triangular mesh facet and each triangular mesh facet.

[0092] For example, if the three vertices of a triangular mesh are P1, P2, and P3, and the coordinates of each vertex in three-dimensional space can be represented as: P1=(x1,y1,z1), P2=(x2,y2,z2), P3=(x3,y3,z3), then:

[0093] Minimum value in the X-axis direction =min(x1,x2,x3), minimum value in the Y-axis direction =min(y1,y2,y3), minimum value in the Z-axis direction =min(z1,z2,z3);

[0094] Maximum value in the X-axis direction =max(x1,x2,x3), the maximum value in the Y-axis direction. =max(y1,y2,y3), the maximum value in the Z-axis direction. =max(z1,z2,z3);

[0095] The bounding box B is defined as follows:

[0096] ;

[0097] in, Represents any point in space; This represents the minimum value of the three vertices of the triangular mesh on the X, Y, and Z axes; This represents the maximum value of the three vertices of the triangular mesh on the X, Y, and Z axes; This represents the minimum value of the three vertices of the triangular mesh on the X-axis; This represents the minimum value of the three vertices of the triangular mesh on the Y-axis; This represents the minimum value of the three vertices of the triangular mesh on the Z-axis; This represents the maximum value of the three vertices of the triangular mesh on the X-axis; This represents the maximum value of the three vertices of the triangular mesh on the Y-axis; This represents the maximum value of the three vertices of the triangular mesh on the Z-axis;

[0098] S42. Take the original bounding box set as the root node, and calculate the bounding box containing the original bounding box set as the root node. Then, take the root node as the current node, recursively divide the bounding box set in the current node according to the direction of the longest axis of the current node's bounding box as the splitting axis, and divide the bounding box set in the current node according to the median position of the centroid coordinates of the bounding box to obtain the hierarchical bounding box of the binary tree structure.

[0099] Initialize the root node, traverse the set of all vertex coordinates of the S bounding boxes of the original bounding box set, and obtain the minimum corner point of the original bounding box set on the X, Y, and Z coordinate axes. Construct the maximum corner point by finding the maximum value of all vertices in the original bounding box set along the X, Y, and Z coordinate axes. Construct a bounding box containing the original bounding box set. The bounding box of the root node, that is, the root node is taken as the current node;

[0100] in, This represents the minimum value of all vertices in the original bounding box set along the X-axis; This represents the minimum value of all vertices in the original bounding box set along the Y-axis; This represents the minimum value of all vertices in the original bounding box set along the Z-axis; This represents the maximum value of all vertices in the original bounding box set on the X-axis; This represents the maximum value of all vertices in the original bounding box set on the Y-axis; This represents the maximum value of all vertices in the original bounding box set along the Z-axis;

[0101] The recursive division of the bounding box set in the current node by using the direction of the longest axis of the current node's bounding box as the dividing axis and the median position of the bounding box's centroid coordinates to obtain the hierarchical bounding box of the binary tree structure specifically includes:

[0102] During the binary search, the direction of the longest axis of the current node's bounding box is used as the splitting axis. The bounding box set of the current node is divided into two bounding box sets according to the median position of the centroid coordinates of the bounding box, and the left and right child nodes are constructed respectively. For each child node, the bounding box containing its own bounding box set is calculated, that is, the bounding box of the left child node and the bounding box of the right child node.

[0103] When the number of bounding boxes contained in a child node does not exceed a preset threshold or the recursion depth reaches the upper limit, the partitioning stops and the child node is marked as a leaf node; otherwise, the child node is treated as the current node and the recursive binary partitioning continues, eventually forming a hierarchical bounding box structure of a binary tree.

[0104] In this embodiment, the preset threshold is 128; it can be changed according to actual needs.

[0105] The recursion depth is set according to the maximum number of vertices in the 3D triangular mesh model of each period, and is set to 4096 in this embodiment.

[0106] It is understandable that when recursively dividing the child node into two bounding boxes, the direction of the longest axis of the current node's bounding box is used as the dividing axis. The bounding box set of the current node is divided into two bounding box sets according to the median position of the centroid coordinates of the bounding box, and the left and right child nodes are constructed respectively. The bounding box containing its own bounding box set is calculated for each child node. This is a typical use of recursion, which will not be elaborated here.

[0107] S43. Starting from the root node of the hierarchical bounding box, select two child nodes of the root node, and check whether the bounding box of the child node intersects with the line L of the mesh vertex normal vector of the reference three-dimensional triangular mesh model M0. If they intersect, add the child node to the intersection detection table.

[0108] The necessary and sufficient condition for the bounding box of the child node to intersect the line L, which is the normal vector of the mesh vertex of the reference 3D triangular mesh model M0, is: ; The line representing the normal vector of a mesh vertex The point of minimum intersection on the three coordinate axes; The line representing the normal vector of a mesh vertex The point of maximum intersection on the three coordinate axes;

[0109] in:

[0110] ;

[0111] in, Indicates the directions of the three coordinate axes in space; This represents the mesh vertex normal vector of the reference 3D triangular mesh model M0. Components on the i-axis; It refers to the i-axis components of the grid vertex coordinates of the reference 3D triangular mesh model M0; The intersection point of the line L, which represents the normal vector of the mesh vertex of the reference 3D triangular mesh model M0, and the bounding box at the minimum boundary of the i-axis; The straight line representing the normal vector of the mesh vertex of the reference three-dimensional triangular mesh model M0. The point of intersection with the bounding box at the maximum boundary along the i-axis; This represents the minimum value of the bounding box along the i-axis; This represents the maximum value of the bounding box on the i-axis;

[0112] S44. Take out the nodes in the intersection detection list in sequence and perform intersection tests: If the node is a leaf node, perform a line-triangle intersection test on all triangular mesh faces contained in the leaf node; otherwise, check whether the bounding box of the node's child nodes intersects with the line L of the mesh vertex normal vector of the reference three-dimensional triangular mesh model M0. If they intersect, add the child node to the intersection detection list.

[0113] It is understandable that, since the bounding box B of each triangular mesh is stored and the correspondence between each triangular mesh is found, the set of triangular meshes corresponding to each node can be obtained through the set of bounding boxes contained in the node.

[0114] The line-triangle intersection test is as follows: if the following conditions are met... And if u, v, w are all greater than or equal to 0, then it is determined that the line L of the mesh vertex normal vector of the reference three-dimensional triangular mesh model M0 intersects with the line formed by the three vertices of the triangular mesh facet. The triangles formed intersect; at this point, the coordinates of the intersection points on the triangular mesh facets are... The reference 3D triangular mesh model M0 has a vertex normal vector line. Corresponding grid vertex coordinates Mesh vertex normal vector The tuple containing the vertex numbers I of the mesh is added to the intersection list of the 3D triangular mesh model Mp for each period; otherwise, it is considered that they do not intersect and no operation is performed.

[0115] in, is the normal vector of the triangular mesh surface; (u,v,w) are the coordinates of the centroid of the triangular mesh surface, and w=1-uv; Indicates from vertex Pointing to the vertex ; Indicates from vertex Pointing to the vertex ;

[0116] The centroid coordinates are a fundamental concept in fields such as triangular mesh parameterization and geometric modeling. The position of any point within a triangle can be uniquely represented by (u,v,w), which is existing technology and will not be elaborated here.

[0117] The centroid coordinates of the triangular mesh facet can be obtained by solving the following linear equation:

[0118] ;

[0119] in, This represents the line representing the normal vector of the s-th vertex of the reference 3D triangular mesh model M0. The corresponding mesh vertex normal vector; This represents the s-th vertex of the reference 3D triangular mesh model M0; the coordinates of the intersection points on the triangular mesh facets. = ;

[0120] S45. Repeat step S44 until the intersection test of all nodes in the intersection detection list is completed, and the intersection relationship list of the three-dimensional triangular mesh model Mp for each period is obtained.

[0121] Finally, in the intersection relationship list of each 3D triangular mesh model Mp, each element is the mesh vertex number I, the intersection point I of the line L (normal vector of the mesh vertex of the reference 3D triangular mesh model M0) and the triangle formed by the three vertices of the triangular mesh facet, and the coordinates of the intersection point on the triangular mesh facet. Grid vertex coordinates Mesh vertex normal vector The constructed tuple.

[0122] S5. Calculate the deformation of the three-dimensional triangular mesh model Mp for each period based on the list of intersection relationships of the three-dimensional triangular mesh model Mp for each period.

[0123] The coordinates of the intersection points on the triangular mesh faces in each element of the intersection relationship list of the 3D triangular mesh model Mp for each period are calculated by traversing the list. With grid vertex coordinates The Euclidean distance is used as the coordinate of MP of the 3D triangular mesh model relative to the mesh vertex coordinates in each period. The deformation of the corresponding I-th mesh vertex, that is, the deformation of the 3D triangular mesh model MP in each period, is the set of the deformation of all mesh vertices of the 3D triangular mesh model MP in each period relative to the reference 3D triangular mesh model M0.

[0124] If grid vertex coordinates For multiple intersecting triangular mesh patches, the minimum Euclidean distance among the calculated distances of these patches is taken as the MP of the 3D triangular mesh model relative to the mesh vertices in each period. The amount of deformation;

[0125] Determining the direction of deformation: Calculate from the mesh vertex coordinates coordinates of the intersection point on the triangular mesh facet Two vectors, if the direction of the vectors is the same as the normal vector of the mesh vertex. If the directions are the same, the deformation is positive; otherwise, the deformation is negative.

[0126] Understandably, reference Figure 4 Each vertex of the reference 3D triangular mesh model M0 is intersected along its normal line with the triangular mesh facet on each phase 3D triangular mesh model Mp. That is, each mesh vertex can find a corresponding intersection point on each phase 3D triangular mesh model Mp. The straight-line distance from the intersection point to the mesh vertex of the reference 3D triangular mesh model M0 is the deformation amount of each phase 3D triangular mesh model Mp relative to that mesh vertex. In practice, the intersecting triangular facets of each mesh vertex of the reference 3D triangular mesh model M0 along its normal line with each phase 3D triangular mesh model Mp may not be unique. The shortest distance is taken as the deformation amount of each phase 3D triangular mesh model Mp relative to that mesh vertex.

[0127] Since each vertex of the reference 3D triangular mesh model M0 can find its intersection point with the triangular mesh facet on each period 3D triangular mesh model Mp along its normal line, all intersection points can also form a displacement model of the triangular mesh. The number of vertices in the final displacement model is the same as the number of vertices in the reference 3D triangular mesh model M0. The displacement model can be used for visualization, which can more intuitively show the deformation of each period 3D triangular mesh model Mp relative to the 3D triangular mesh model M0.

[0128] S6. Subtract the deformation of the three-dimensional triangular mesh models of other periods (excluding the first period) from the deformation of the three-dimensional triangular mesh model M1 of the first period to obtain the deformation of the three-dimensional triangular mesh models of other periods relative to the three-dimensional triangular mesh model M1 of the first period.

[0129] Using the first-phase three-dimensional triangular mesh model M1 as the benchmark, the deformation of other multi-phase models Mp (p=2,3,...,P) is subtracted from the deformation of M1 to obtain the overall relative deformation of the multi-phase models with respect to model M1. This enables the measurement and monitoring of the overall deformation of the tunnel's initial support section, providing more reliable data support for tunnel safety assessment and deformation monitoring.

[0130] refer to Figure 6 , Figure 6 Schematic diagram of initial support deformation cloud map from the second to the fifth phase; Figure 6 (a) in the figure is the deformation cloud diagram of the second-stage initial support relative to the first-stage initial support; Figure 6 (b) in the figure is the deformation cloud diagram of the third-stage initial support relative to the first-stage initial support; Figure 6 (c) in the figure is the deformation cloud diagram of the fourth stage initial support relative to the first stage initial support; Figure 6 (d) in the figure represents the deformation cloud diagram of the fifth-stage initial support relative to the first-stage initial support;

[0131] It is understandable that, since the deformation of each phase of the 3D triangular mesh model MP is the set of the deformation of all mesh vertices of each phase of the 3D triangular mesh model MP relative to the reference 3D triangular mesh model M0, the deformation of the first phase of the 3D triangular mesh model M1 and other multi-phase models Mp (p=2,3,...,P) can be obtained by subtracting the deformation of the same mesh vertex in the set, thus obtaining the deformation of other phases of the 3D triangular mesh model relative to the first phase of the 3D triangular mesh model M1.

[0132] This example provides a method for measuring the overall large deformation of tunnels based on laser scanning. It directly processes and analyzes the overall three-dimensional laser point cloud data of the tunnel, thereby reflecting the true overall three-dimensional deformation characteristics of the tunnel more comprehensively and accurately. This avoids the loss of local information and misjudgment of deformation characteristics caused by two-dimensional cross-section analysis, and provides more reliable data support for tunnel safety assessment and deformation monitoring.

[0133] The hierarchical bounding box detection algorithm in this embodiment provides algorithmic optimization for filtering and detecting large-scale point cloud data. The calculated Euclidean distance along the normal direction of the reference model is the radial deformation of the support. Therefore, the calculated deformation is consistent with the actual monitoring and measurement results and is sufficiently accurate. It can effectively overcome the impact of large deformation on measurement accuracy and maintain high measurement accuracy even when the tunnel undergoes large deformation. It accurately captures the deformation of the tunnel and can promptly report the deformation status, improving the efficiency of deformation analysis. It provides timely and effective basis for engineering decision-making, helps to promptly discover potential safety hazards and take corresponding measures, ensures the safety of tunnel construction and operation, and helps to reduce the overall cost of tunnel deformation measurement. It can reduce engineering rework and safety accidents caused by measurement errors, thereby indirectly reducing engineering costs and improving economic benefits.

[0134] Example 2

[0135] refer to Figure 7 This embodiment provides a device for measuring the overall large deformation of a tunnel based on laser scanning, which is based on the method for measuring the overall large deformation of a tunnel based on laser scanning described in Embodiment 1, and includes the following units:

[0136] Each phase model building unit is used to collect point cloud data of the initial support section of the target tunnel at different times in phase P through laser scanning, and to transform the construction coordinate system of each phase point cloud data one by one to build a three-dimensional triangular mesh model Mp for each phase; where p=1,2,3,...,P;

[0137] Reference model building unit, used to construct a reference three-dimensional triangular mesh model M0 of the target tunnel initial support section based on the tunnel initial support outline design drawing and the design tunnel center axis;

[0138] The normal vector and line construction unit is used to calculate the mesh vertex normal vector N and the mesh vertex normal vector line L of the reference three-dimensional triangular mesh model M0.

[0139] The model intersection relationship calculation unit is used to obtain the intersecting triangular facets of the mesh vertex normal vector line L of the reference three-dimensional triangular mesh model M0 and the three-dimensional triangular mesh model Mp of each period through the hierarchical bounding box detection algorithm, thereby obtaining the intersection relationship list of the three-dimensional triangular mesh model Mp of each period.

[0140] The deformation calculation unit for each phase of the model is used to calculate the deformation of each phase of the three-dimensional triangular mesh model Mp based on the intersection relationship list of each phase of the three-dimensional triangular mesh model Mp.

[0141] The overall model deformation calculation unit is used to calculate the difference between the deformation of the three-dimensional triangular mesh models in other periods (excluding the first period) and the deformation of the three-dimensional triangular mesh model M1 in the first period, so as to obtain the deformation of the three-dimensional triangular mesh models in other periods relative to the three-dimensional triangular mesh model M1 in the first period.

[0142] This specification is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of this specification. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create a machine for implementing the flowchart illustrations and / or block diagrams. Figure 1 A process, multiple processes, and / or boxes Figure 1 Devices that specify the functions in one or more boxes.

[0143] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including an instruction device, which is implemented in a process Figure 1 One or more processes and / or boxes Figure 1The function specified in one or more boxes.

[0144] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0145] The parts of this invention not described in detail are prior art. It will be apparent to those skilled in the art that this invention is not limited to the details of the above exemplary embodiments, and that the invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be regarded as exemplary and non-limiting in all respects, and are intended to encompass all changes falling within the meaning and scope of equivalents within this invention.

Claims

1. A method for measuring the overall large deformation of a tunnel based on laser scanning, characterized in that, Includes the following steps: S1. Point cloud data of the initial support section of the target tunnel at different times in phase P are collected by laser scanning. The construction coordinate system is transformed for each phase of point cloud data and a three-dimensional triangular mesh model Mp is constructed for each phase; where p=1,2,3,...,P; S2. Based on the tunnel initial support outline design drawing and the design tunnel center axis, construct a reference three-dimensional triangular mesh model M0 for the target tunnel initial support section; S3. Calculate the mesh vertex normal vector N and the mesh vertex normal vector line L of the reference three-dimensional triangular mesh model M0; S4. Obtain the intersecting triangular facets of the reference 3D triangular mesh model M0 and each period 3D triangular mesh model Mp through the hierarchical bounding box detection algorithm, thereby obtaining the intersection relationship list of each period 3D triangular mesh model Mp. The hierarchical bounding box detection algorithm described in step S4 specifically includes the following steps: S41. Calculate the bounding boxes for all triangular mesh faces of each period's 3D triangular mesh model Mp to obtain the original bounding box set; S42. Take the original bounding box set as the root node, and calculate the bounding box containing the original bounding box set as the root node. Then, take the root node as the current node, recursively divide the bounding box set in the current node according to the direction of the longest axis of the current node's bounding box as the splitting axis, and divide the bounding box set in the current node according to the median position of the centroid coordinates of the bounding box to obtain the hierarchical bounding box of the binary tree structure. S43. Starting from the root node of the hierarchical bounding box, select two child nodes of the root node, and check whether the bounding box of the child node intersects with the line L of the mesh vertex normal vector of the reference three-dimensional triangular mesh model M0. If they intersect, add the child node to the intersection detection table. S44. Take out the nodes in the intersection detection list in sequence and perform intersection tests: If the node is a leaf node, perform a line-triangle intersection test on all triangular mesh faces contained in the leaf node; otherwise, check whether the bounding box of the node's child nodes intersects with the line L of the mesh vertex normal vector of the reference three-dimensional triangular mesh model M0. If they intersect, add the child node to the intersection detection list. S45. Repeat step S44 until the intersection test of all nodes in the intersection detection list is completed to obtain the intersection relationship list of the three-dimensional triangular mesh model Mp for each period. S5. Calculate the deformation of the three-dimensional triangular mesh model Mp for each period based on the list of intersection relationships of the three-dimensional triangular mesh model Mp for each period. Step S5 specifically includes: The coordinates of the intersection points on the triangular mesh faces in each element of the intersection relationship list of the 3D triangular mesh model Mp for each period are calculated by traversing the list. With grid vertex coordinates The Euclidean distance is used as the coordinate of MP of the 3D triangular mesh model relative to the mesh vertex coordinates in each period. The deformation of the corresponding I-th mesh vertex, that is, the deformation of the 3D triangular mesh model MP in each period, is the set of the deformation of all mesh vertices of the 3D triangular mesh model MP in each period relative to the reference 3D triangular mesh model M0. S6. Subtract the deformation of the three-dimensional triangular mesh models of other periods (excluding the first period) from the deformation of the three-dimensional triangular mesh model M1 of the first period to obtain the deformation of the three-dimensional triangular mesh models of other periods relative to the three-dimensional triangular mesh model M1 of the first period.

2. The method for measuring the overall large deformation of a tunnel based on laser scanning according to claim 1, characterized in that, Step S42, which involves recursively dividing the bounding box set in the current node by the direction of the longest axis of the current node's bounding box as the dividing axis and by the median position of the bounding box's centroid coordinates to obtain the hierarchical bounding box of the binary tree structure, specifically includes: During the binary search, the direction of the longest axis of the current node's bounding box is used as the splitting axis. The bounding box set of the current node is divided into two bounding box sets according to the median position of the centroid coordinates of the bounding box, and the left and right child nodes are constructed respectively. For each child node, the bounding box containing its own bounding box set is calculated, that is, the bounding box of the left child node and the bounding box of the right child node. When the number of bounding boxes contained in a child node does not exceed a preset threshold or the recursion depth reaches the upper limit, the partitioning stops and the child node is marked as a leaf node; otherwise, the child node is treated as the current node and the recursive binary partitioning continues, eventually forming a hierarchical bounding box structure of a binary tree.

3. The method for measuring the overall large deformation of a tunnel based on laser scanning according to claim 1, characterized in that, The necessary and sufficient condition for the bounding box of the child node in step S43 to intersect the line L of the mesh vertex normal vector of the reference 3D triangular mesh model M0 is: ; The line representing the normal vector of a mesh vertex The point of minimum intersection on the three coordinate axes; The line representing the normal vector of a mesh vertex The point of maximum intersection on the three coordinate axes; where: ； in, Indicates the directions of the three coordinate axes in space; This represents the mesh vertex normal vector of the reference 3D triangular mesh model M0. Components on the i-axis; This represents the i-axis component of the grid vertex coordinates of the reference 3D triangular mesh model M0; The intersection point of the line L, which represents the normal vector of the mesh vertex of the reference 3D triangular mesh model M0, and the bounding box at the minimum boundary of the i-axis; The straight line representing the normal vector of the mesh vertex of the reference three-dimensional triangular mesh model M0. The point of intersection with the bounding box at the maximum boundary along the i-axis; This represents the minimum value of the bounding box along the i-axis; This represents the maximum value of the bounding box on the i-axis.

4. The method for measuring the overall large deformation of a tunnel based on laser scanning according to claim 1, characterized in that, The line-triangle intersection test in step S44 specifically refers to: if the following conditions are met... And if u, v, w are all greater than or equal to 0, then it is determined that the line L of the mesh vertex normal vector of the reference three-dimensional triangular mesh model M0 intersects with the line formed by the three vertices of the triangular mesh facet. The triangles formed intersect; at this point, the coordinates of the intersection points on the triangular mesh facets are... The reference 3D triangular mesh model M0 has a vertex normal vector line. Corresponding grid vertex coordinates Mesh vertex normal vector The tuples constructed from the grid vertex numbers I are placed into the intersection relationship list of the 3D triangular mesh model Mp for each period; Otherwise, they are considered non-intersecting, and no operation is performed; among them, The normal vector of the triangular mesh surface; (u,v,w) are the centroid coordinates of the triangular mesh facet, and w=1-uv; Indicates from vertex Pointing to the vertex ; Indicates from vertex Pointing to the vertex The vector.

5. The method for measuring the overall large deformation of a tunnel based on laser scanning according to claim 4, characterized in that, The centroid coordinates of the triangular mesh facet can be obtained by solving the following linear equation: ； Among them, the coordinates of the intersection points on the triangular mesh facets = .

6. The method for measuring the overall large deformation of a tunnel based on laser scanning according to claim 1, characterized in that, Step S2 specifically includes: S21. Extract the outer contour line of the initial support from the tunnel initial support outline design drawing, divide the outer contour line of the initial support into multiple segments according to the first fixed interval, and extract the division points as streamline points. S22. Using the central axis of the designed tunnel as the trace, stretch the streamline points along the trace direction at a second fixed interval to construct a reference point cloud for the design of the initial support section of the target tunnel. S23. Connect the reference point cloud of the initial support section of the target tunnel according to the preset connection rules to form a triangular mesh structure, and construct a reference three-dimensional triangular mesh model M0.

7. The method for measuring the overall large deformation of a tunnel based on laser scanning according to claim 1, characterized in that, Step S3 specifically includes: The normal vector N of the mesh vertices of the reference 3D triangular mesh model M0 is the normal vector of all mesh vertices in the reference 3D triangular mesh model M0. The set of reference 3D triangular mesh model M0, where the line L is the normal vector line of all mesh vertices in the reference 3D triangular mesh model M0. The set; where, Let represent the normal vector of the s-th grid vertex; It is a straight line extending along the direction of its corresponding normal vector through the s-th grid vertex, and can be represented as: ,in The coordinates of the s-th grid vertex are represented; t represents a variable; s = 1, 2, ..., S; S is the total number of grid vertices contained in the reference 3D triangular mesh model M0.

8. A device for measuring the overall large deformation of a tunnel based on laser scanning, based on the method for measuring the overall large deformation of a tunnel based on laser scanning according to any one of claims 1-7, characterized in that, Includes the following units: Each phase model building unit is used to collect point cloud data of the initial support section of the target tunnel at different times in phase P through laser scanning, and to transform the construction coordinate system of each phase point cloud data one by one to build a three-dimensional triangular mesh model Mp for each phase; where p=1,2,3,...,P; Reference model building unit, used to construct a reference three-dimensional triangular mesh model M0 of the target tunnel initial support section based on the tunnel initial support outline design drawing and the design tunnel center axis; The normal vector and line construction unit is used to calculate the mesh vertex normal vector N and the mesh vertex normal vector line L of the reference three-dimensional triangular mesh model M0. The model intersection relationship calculation unit is used to obtain the intersecting triangular facets of the mesh vertex normal vector line L of the reference three-dimensional triangular mesh model M0 and the three-dimensional triangular mesh model Mp of each period through the hierarchical bounding box detection algorithm, thereby obtaining the intersection relationship list of the three-dimensional triangular mesh model Mp of each period. The deformation calculation unit for each phase of the model is used to calculate the deformation of each phase of the three-dimensional triangular mesh model Mp based on the intersection relationship list of each phase of the three-dimensional triangular mesh model Mp. The overall model deformation calculation unit is used to calculate the difference between the deformation of the three-dimensional triangular mesh models in other periods (excluding the first period) and the deformation of the three-dimensional triangular mesh model M1 in the first period, so as to obtain the deformation of the three-dimensional triangular mesh models in other periods relative to the three-dimensional triangular mesh model M1 in the first period.

Images