Three-dimensional grid generation method and system for finite element calculation of earth-rock dam considering foundation terrain matching

Abstract

The present invention discloses a method and system for generating a three-dimensional mesh for finite element calculations of earth-rock dams that considers matching the underlying terrain. The method comprises: flattening the two-dimensional finite element mesh of the largest section of the earth-rock dam to each cross section, connecting all nodes between adjacent sections to generate an initial three-dimensional finite element mesh, redrawing all cross-sectional ground lines to obtain a terrain triangulation network, using the terrain triangulation network to determine the topographical properties of all three-dimensional nodes, and screening out three-dimensional meshes to be cut. These meshes are then uniformly processed into triangular prism meshes, and the terrain cutting levels of the two-dimensional meshes of the front and rear sections are assigned. Finally, all the triangular prism meshes to be cut are nested in a three-dimensional cutting mesh model, and a virtual cutting node sliding method is used to obtain a cut three-dimensional mesh that matches the terrain. The present invention utilizes the proposed virtual cutting node sliding method to cover the cutting conditions of all three-dimensional meshes, so that the cut three-dimensional mesh at the bottom of the earth-rock dam better matches the terrain, indirectly improving the accuracy of the earth-rock dam finite element analysis calculation.

Description

Technical Field

[0001] The present application relates to the field of finite element calculation of water conservancy projects, and in particular to a three-dimensional grid generation method and system for finite element calculation of earth-rock dams taking into account foundation terrain matching. Background Art

[0002] Earth-rockfill dams are a widely used dam type, favored for their adaptability and economic efficiency. Finite element analysis (FEM), a powerful numerical analysis tool, has been used to analyze the stress and deformation of earth-rockfill dams. This method provides detailed internal stress and deformation data, which is crucial for the design of large earth-rockfill dams. However, the accuracy and efficiency of FEM analysis depend heavily on the quality of the computational mesh, especially in complex terrain.

[0003] In practice, the foundation terrain of an earth-rock dam is complex and varied, making traditional mesh cutting techniques difficult to adapt to this complexity. Existing mesh generation methods, such as regular grid-based division or simple automatic meshing, are often unable to accurately match the earth-rock dam foundation to the underlying terrain. Summary of the Invention

[0004] In response to the technical problems existing in the prior art, the present invention provides a method and system for generating a three-dimensional grid for finite element calculation of an earth-rock dam that takes into account the matching of the foundation terrain. The method can take into account the unevenness of the earth-rock dam foundation and the complexity of the foundation terrain, and generate a three-dimensional grid for finite element calculation of the earth-rock dam that matches the foundation terrain, so as to improve the accuracy of the finite element analysis of the calculation grid of the earth-rock dam foundation and ensure the reliability of the analysis results.

[0005] This application provides a three-dimensional mesh generation method for finite element calculation of earth-rock dams considering foundation terrain matching, which adopts the following technical solutions:

[0006] The three-dimensional mesh generation method for finite element calculation of earth-rock dam considering foundation terrain matching includes the following steps:

[0007] The 2D finite element mesh of the largest section of the earth-rock dam is pushed evenly along the dam axis to obtain the 2D finite element meshes at all cross sections.

[0008] Connect the corresponding nodes of the two-dimensional finite element meshes of adjacent cross sections with connecting edges to construct the three-dimensional finite element initial mesh;

[0009] The positions of the ground lines are adjusted according to the two-dimensional nodes of the two-dimensional finite element grid to obtain redrawn ground lines, and the redrawn ground lines between adjacent cross sections are triangulated using nodes to obtain a terrain triangulation network;

[0010] According to the relative elevation position of the terrain triangulation network and the 3D nodes, the terrain up and down judgment is performed on all the 3D nodes of the 3D finite element initial mesh;

[0011] According to the terrain up-down information of the 3D nodes, the cutting edges that intersect with the terrain triangulation are screened out, and the finite element initial mesh containing the cutting edges is used as the 3D mesh to be cut to match the terrain;

[0012] Split all three-dimensional grids to be cut into two triangular prism grids;

[0013] According to the terrain up-down information of the 3D node, the terrain cutting level is assigned to the 2D grid of the adjacent cross section where the triangular prism grid is located;

[0014] Construct a 3D grid cutting model, and slide virtual cutting nodes on all edges of the triangular prism grid according to the 2D grid terrain cutting level of the adjacent cross section to obtain two 3D cut grids.

[0015] Determine whether all the meshes after 3D cutting are zero volume meshes. If so, remove them. If not, retain them. Then obtain the 3D finite element calculation mesh of the earth-rock dam that matches the terrain.

[0016] Furthermore, the step of redrawing the ground line includes:

[0017] The three-dimensional nodes of the three-dimensional finite element initial grid are connected to find a multi-node connected polyline that is closest to the real ground line as the redrawn ground line; and the triangulation algorithm is used to construct a node triangulation network of the redrawn ground lines between adjacent cross sections to obtain a terrain triangulation network.

[0018] Furthermore, the step of determining the terrain up and down of the three-dimensional node includes:

[0019] For nodes on the terrain triangulation, the node terrain up-down property is judged as 0;

[0020] For nodes whose elevation is higher than the terrain triangulation, the node terrain up-down property is judged as 1;

[0021] For nodes whose elevation is lower than the terrain triangulation, the node terrain up-down property is judged as -1.

[0022] Furthermore, the cutting edge is an edge formed by connecting two end points of a node terrain with an up-down tendency of 1 and -1; and the three-dimensional grid to be cut is a three-dimensional grid containing at least one cutting edge.

[0023] Furthermore, the three-dimensional grid to be cut includes a triangular prism grid and a hexahedral grid. The hexahedral grid in the three-dimensional grid to be cut is cut into two triangular prism grids, and the two-dimensional grids of adjacent cross sections where the triangular prism grids are located are all triangular grids.

[0024] Furthermore, the step of assigning terrain cutting levels to the two-dimensional grids of the adjacent cross sections where the triangular prism grid is located includes:

[0025] Assign terrain cutting level 1 to the triangle mesh with 3 nodes whose terrain up and down properties are 1, 1, 1;

[0026] Assign terrain cutting level 2 to the triangle mesh with 3 nodes whose terrain up and down properties are 0, 1, and 1;

[0027] Assign terrain cutting level 3 to the triangle mesh with 3 nodes whose terrain up and down properties are 0, 0, and 1;

[0028] Assign a terrain cut level of 4 to the triangle mesh with 3 nodes whose terrain up and down properties are 0, 0, 0;

[0029] Assign a terrain cut level of 5 to the triangle mesh with 3 nodes whose terrain up and down properties are 1, 0, and -1;

[0030] Assign terrain cutting level 6 to the triangle mesh with 3 nodes whose terrain up and down properties are 0, 0, and -1;

[0031] Assign terrain cut level 7 to the triangle mesh with 3 nodes whose terrain up and down properties are 0, -1, and -1;

[0032] Assign a terrain cut level of 8 to the triangle mesh with 3 nodes whose terrain up and down properties are -1, -1, -1.

[0033] Furthermore, the steps of constructing a three-dimensional mesh cutting model include:

[0034] Assume that the three edges of the triangular prism mesh to be cut are virtual cutting edges, and there are virtual cutting points on them. The initial positions of the three virtual cutting points are the midpoints of the edges. The three virtual cutting points form a virtual cutting surface, which is a three-dimensional mesh cutting model.

[0035] Furthermore, the implementation steps of the virtual cutting node sliding include:

[0036] For a virtual cutting edge with a terrain combination of (-1,-1) at both ends, slide the virtual cutting node on the virtual cutting edge along the direction of the virtual cutting edge to the endpoint on the side with a lower terrain cutting level in the adjacent section. If the terrain cutting levels are equal, slide it to the endpoint on the side close to the middle section of the earth-rockfill dam.

[0037] For a virtual cutting edge with two endpoints whose topographic properties are (1,1) or (0,0), slide the virtual cutting node on the virtual cutting edge along the direction of the virtual cutting edge to the endpoint with a higher terrain cutting level in the adjacent section. If the terrain cutting levels are equal, slide the node to the endpoint close to the middle section of the earth-rockfill dam.

[0038] For a virtual cutting edge with two endpoints whose topographic combinations are (1,-1) or (-1,1), slide the virtual cutting node on the virtual cutting edge along the direction of the virtual cutting edge to the position after the edge is cut by the terrain triangulation.

[0039] For a virtual cutting edge whose two endpoints have a terrain up-down combination of (0,-1), (0,1), (-1,0) or (1,0), the virtual cutting node on the virtual cutting edge is slid along the direction of the virtual cutting edge to the endpoint where the terrain up-down is 0.

[0040] Furthermore, the step of determining whether all the three-dimensional cut meshes are zero-volume meshes includes:

[0041] After nesting the 3D cutting mesh model, if three virtual cutting nodes slide to the same cross section, the 3D cutting mesh will be a zero volume mesh and will be removed.

[0042] In another aspect, the present invention provides a three-dimensional grid generation system for finite element calculation of earth-rock dams taking into account foundation terrain matching, comprising:

[0043] A two-dimensional finite element mesh generation module is used to push the two-dimensional finite element mesh of the largest section of the earth-rock dam equidistantly along the dam axis to obtain the two-dimensional finite element meshes at all cross sections;

[0044] A three-dimensional finite element initial mesh construction module is used to connect the corresponding nodes of the two-dimensional finite element meshes of adjacent cross sections with connecting edges to construct a three-dimensional finite element initial mesh;

[0045] A terrain triangulation module is used to adjust the position of the ground line according to the two-dimensional nodes of the two-dimensional finite element grid to obtain a redrawn ground line, and to construct a node triangulation network of the redrawn ground lines between adjacent cross sections to obtain a terrain triangulation network;

[0046] A terrain up-down judgment module is used to judge the terrain up-down of all three-dimensional nodes of the three-dimensional finite element initial grid based on the relative elevation positions of the terrain triangulation network and the three-dimensional nodes;

[0047] The 3D mesh to be cut screening module is used to screen out cutting edges that intersect with the terrain triangulation network based on the 3D node terrain up-down information, and use the finite element initial mesh containing the cutting edges as the 3D mesh to be cut to match the terrain;

[0048] A three-dimensional grid to be cut splitting module is used to split all three-dimensional grids to be cut into two triangular prism grids;

[0049] A terrain cutting grade judgment module is used to assign a terrain cutting grade to the two-dimensional grids of the adjacent cross sections of the triangular prism grid according to the terrain up-down information of the three-dimensional node;

[0050] A 3D grid cutting model building module is used to build a 3D grid cutting model. It slides virtual cutting nodes on all edges of the triangular prism grid according to the 2D grid terrain cutting level of the adjacent cross section where the triangular prism grid is located, and obtains two 3D cut grids.

[0051] A zero volume mesh elimination module is used to determine whether all meshes after 3D cutting are zero volume meshes. If so, they are eliminated; otherwise, they are retained to obtain a 3D finite element calculation mesh for the earth-rock dam that matches the terrain.

[0052] Compared with the prior art, the present invention has the following beneficial effects:

[0053] 1. Complete coverage of cutting conditions. The method of the present invention abandons the traditional enumeration idea and uses a three-dimensional grid cutting model and a virtual cutting node sliding method to fully cover all three-dimensional grid cutting conditions and achieve accurate matching of the basic terrain.

[0054] 2. Improved calculation accuracy: Compared with the existing technology, the present invention can more accurately simulate the three-dimensional structure of the earth-rock dam through the method of basic terrain matching, thereby improving the accuracy of finite element calculation.

[0055] 3. Enhance the applicability of the model. The method of the present invention is applicable to various complex terrain conditions and enhances the applicability and flexibility of the finite element model of earth-rock dams.

[0056] 4. Easy to integrate and expand. The method of the present invention can be easily integrated into existing earth-rock dam design and analysis software and has good scalability to adapt to future technological developments. BRIEF DESCRIPTION OF THE DRAWINGS

[0057] The coordinate axes of all the drawings are in the same direction: the positive direction of the X axis is from the upstream to the downstream of the dam, the positive direction of the Y axis is from the bottom to the top of the dam, and the positive direction of the Z axis is from the left bank to the right bank of the dam, that is, the direction of the dam axis;

[0058] Figure 1 This is a flow chart of a three-dimensional mesh generation method for finite element calculation of an earth-rock dam considering foundation terrain matching in an embodiment of the present application;

[0059] Figure 2 is a two-dimensional finite element mesh of the largest section of the earth-rock dam in the embodiment of this application;

[0060] Figure 3 This is a schematic diagram of pushing the two-dimensional finite element mesh of the largest section of the earth-rock dam to each cross section along the dam axis in the embodiment of the present application;

[0061] Figure 4Schematic diagram of projecting and connecting the triangular meshes of the front and rear sections to form a triangular prism mesh in an embodiment of the present application;

[0062] Figure 5 Schematic diagram of projecting and connecting the quadrilateral meshes of the front and rear sections to form a hexahedral mesh in an embodiment of the present application;

[0063] Figure 6 Schematic diagram of the initial three-dimensional finite element mesh of the earth-rock dam constructed in the embodiment of the present application;

[0064] Figure 7 Schematic diagram of redrawing ground lines within a single grid of each cross section in an embodiment of the present application;

[0065] Figure 8 This is a schematic diagram showing the original ground line of a certain section in the embodiment of the present application represented by a two-dimensional finite element mesh of the largest section of the earth-rock dam;

[0066] Figure 9 for Figure 8 A magnified schematic diagram of the middle dam crest area;

[0067] Figure 10 The diagram is a redrawn diagram of a two-dimensional finite element mesh of the largest section of an earth-rock dam after the ground line of a certain section in an embodiment of the present application is drawn;

[0068] Figure 11 for Figure 10 A magnified schematic diagram of the middle dam crest area;

[0069] Figure 12 A schematic diagram of constructing a terrain triangulation network by performing Delaunay triangulation between adjacent ground lines in an embodiment of the present application;

[0070] Figure 13 A schematic diagram of a terrain triangulation network in an embodiment of the present application;

[0071] Figure 14 for Figure 13 A magnified schematic diagram of the middle dam area;

[0072] Figure 15 This is a schematic diagram of a three-dimensional node judging the verticality of terrain based on its relative elevation to the terrain triangulation network in an embodiment of the present application;

[0073] Figure 16 This is a schematic diagram of determining the topography of a node of a grid on a two-dimensional plane according to its relative elevation to the ground line in an embodiment of the present application;

[0074] Figure 17 A schematic diagram of a triangular prism grid being cut by a terrain triangulation network in a two-dimensional perspective in an embodiment of the present application;

[0075] Figure 18 Schematic diagram of a triangular prism grid being cut by a terrain triangulation network in an embodiment of the present application;

[0076] Figure 19 Schematic diagram of a hexahedral grid to be cut into two triangular prism grids in an embodiment of the present application;

[0077] Figure 20 A schematic diagram of assigning terrain cutting levels to triangular meshes of each section according to the terrain up-down properties of nodes within the mesh in an embodiment of the present application;

[0078] Figure 21 A schematic diagram of a three-dimensional grid cutting model proposed in an embodiment of the present application;

[0079] Figure 22 Schematic diagram of different cutting situations formed by applying the virtual cutting node sliding method to a three-dimensional mesh to be cut, a nested three-dimensional mesh cutting model, and the like in an embodiment of the present application;

[0080] Figure 23 This is a three-dimensional diagram of the cut bottom mesh of the three-dimensional finite element initial mesh of the earth-rock dam in the embodiment of the present application;

[0081] Figure 24 This is a stereoscopic image of the earth-rock dam body before the terrain matching process in the embodiment of the present application;

[0082] Figure 25 This is a three-dimensional image of the earth-rock dam body after matching the terrain in the embodiment of this application;

[0083] Figure 26 This is a downstream side view of the earth-rock dam body before it passes through the matching terrain in the embodiment of this application;

[0084] Figure 27 This is a downstream side view of the earth-rock dam body after matching the terrain in the embodiment of this application. DETAILED DESCRIPTION

[0085] To make the above-mentioned objects, features, and advantages of the present application more clearly understood, the specific embodiments of the present application are described in detail below with reference to the accompanying drawings. The following description sets forth many specific details to facilitate a full understanding of the present application. However, the present application can be implemented in many other ways than those described herein, and those skilled in the art can make similar improvements without violating the scope of the present application. Therefore, the present application is not limited to the specific embodiments disclosed below.

[0086] The terms "first", "second", etc. in the specification and claims of this application and the above-mentioned drawings are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchangeable where appropriate so that the embodiments described herein can be implemented in a sequence other than that illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device that includes a series of steps or modules is not necessarily limited to those steps or modules clearly listed, but may include other steps or modules that are not clearly listed or that are inherent to these processes, methods, products or devices. The naming or numbering of steps in this application does not mean that the steps in the method flow must be executed in the time / logical sequence indicated by the naming or numbering. The process steps that have been named or numbered can be changed in the execution order according to the technical purpose to be achieved, as long as the same or similar technical effects can be achieved. The division of units described in this application is a logical division. In actual implementation, other divisions may be used. For example, multiple units may be combined or integrated into another system, or some features may be ignored or not implemented. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be through interfaces, and the indirect coupling or communication connection between units may be electrical or other similar forms, all of which are not limited in this application. Furthermore, the units or subunits described as separate components may or may not be physically separated, may or may not be physical units, or may be distributed across multiple circuit units. Some or all of these units may be selected based on actual needs to achieve the objectives of this application.

[0087] Example 1

[0088] The following is combined with Figure 1-27 This application is described in further detail.

[0089] The embodiment of the present application discloses a method for generating a three-dimensional grid by finite element calculation of an earth-rock dam considering the matching of the foundation terrain. Figure 1 ,The 3D mesh generation method of finite element calculation of earth-rock dam considering foundation terrain matching includes the following steps:

[0090] S100: Figure 2 The 2D finite element mesh of the largest section of the earth-rock dam shown is Figure 3 The finite element meshes at all cross sections are obtained by pushing the finite element meshes along the dam axis in a horizontal direction and replicating them at all cross sections.

[0091] In this embodiment, the maximum cross-section of the earth-rock dam is obtained by projecting the outer contour information of all cross-sections onto the same plane and taking the union, and then superimposing the material partitioning, filling phase and rock foundation limit frame. The two-dimensional finite element mesh meets the requirement that the two-dimensional mesh of the Solid185 unit in ANSYS consists only of triangular meshes and quadrilateral meshes.

[0092] S200: Project the two-dimensional finite element meshes between adjacent cross sections and connect them through connecting edges. The triangular mesh and the quadrilateral mesh are as follows: Figure 4 and Figure 5 As shown, after the projection is connected, a triangular prism grid and a hexahedron grid are formed. The initial grid of the three-dimensional finite element is composed of a triangular prism grid and a hexahedron grid. When all the grids are projected and connected, the whole is as follows Figure 6 The three-dimensional finite element initial mesh of the earth-rock dam is shown.

[0093] S300: Use the ground line redrawing method to Figure 8 、 Figure 9 The original true ground line shown is redrawn as Figure 10 、 Figure 11 The redrawn ground line shown is formed by connecting only the existing grid nodes, and finally Figure 12 As shown in the figure, the Delaunay triangulation algorithm commonly used at home and abroad is used to construct the triangulation network of nodes between adjacent ground lines, generating Figure 13 and Figure 14 The terrain triangulation shown.

[0094] S400: Use the terrain triangulation network to judge the terrain up and down of the three-dimensional node, such as Figure 15 As shown, the terrain up and down judgment of nodes in the two-dimensional grid is as follows Figure 16 As shown, the specific steps include:

[0095] S401: For a node on the terrain triangulation, the node terrain up-down property is judged to be 0.

[0096] S402: For nodes whose elevation is higher than the terrain triangulation, the node terrain up-down property is judged as 1.

[0097] S403: For nodes whose elevation is lower than the terrain triangulation, the node terrain up-down property is judged as -1.

[0098] S500: Based on the terrain up-down information of all nodes, meshes with cutting edges whose two endpoints have terrain up-down combinations of 1 and -1 are selected as 3D meshes to be cut. 3D meshes to be cut are any 3D meshes containing one or more cutting edges, which are considered to be cut to match the terrain, such as Figure 17 and 18 shown.

[0099] S600: Press the hexahedral mesh in the 3D mesh to be cut Figure 19 The hexahedral mesh of the three-dimensional mesh to be cut is split into two triangular prism meshes. Since the quadrilateral meshes on the front and rear ends are cut in a complicated manner, the hexahedral mesh is cut into two triangular prism meshes to reduce the cutting complexity of the three-dimensional mesh to be cut so as to better match the terrain.

[0100] S700: Using the topographical properties of the nodes, assign terrain cutting levels to the front and rear section grids of the 3D grid to be cut, such as Figure 20 As shown, the two-dimensional grids of adjacent cross sections are obtained by projection replication, but the relative positions of the ground lines of their respective cross sections are different, and in addition, they are cut, so the shapes are similar and they are all triangular grids;

[0101] The specific steps include:

[0102] S701: Assign a terrain cutting level of 1 to the triangular mesh with three nodes whose terrain up-down properties are 1, 1, 1.

[0103] S702: Assign a terrain cutting level of 2 to the triangle mesh with three nodes whose terrain up and down properties are 0, 1, and 1.

[0104] S703: Assign a terrain cutting level of 3 to the triangle mesh with three nodes whose terrain up and down properties are 0, 0, and 1.

[0105] S704: Assign a terrain cutting level of 4 to the triangle mesh with three nodes whose terrain up and down properties are 0, 0, 0.

[0106] S705: Assign a terrain cutting level of 5 to the three triangle meshes whose nodes have terrain up / down properties of 1, 0, and -1.

[0107] S706: Assign a terrain cutting level of 6 to the triangle mesh with three nodes whose terrain up and down properties are 0, 0, and -1.

[0108] S607: Assign a terrain cutting level of 7 to the triangle mesh with three nodes whose terrain up and down properties are 0, -1, and -1.

[0109] S708: Assign a terrain cutting level of 8 to the triangle mesh with three nodes whose terrain up and down properties are -1, -1, and -1.

[0110] S800: Nest all three-dimensional grids to be cut as follows Figure 21 The three-dimensional mesh cutting model is shown in the figure, and the virtual cutting nodes on the cutting edge are slid along the edge. The effect of the number of node sliding on the mesh cutting situation is shown in the figure. Figure 22 Specifically, the following situations are included:

[0111] S801: For meshes with three real cutting nodes, maintain the triangular prism mesh shape.

[0112] S802: For a mesh having two real cutting nodes and one virtual cutting node that needs to slide, the shape becomes a pyramid mesh after the node slides.

[0113] S803: For a mesh having one real cutting node and two virtual cutting nodes that need to slide, the shape becomes a tetrahedral mesh after the nodes slide.

[0114] S804: For a mesh having 0 real cutting nodes and 3 virtual cutting nodes that need to slide, after the nodes slide, the mesh is directly eliminated as a zero-volume mesh.

[0115] S900: Figure 23 As shown in the figure, after the bottom mesh of the initial mesh of the earth-rock dam 3D finite element is completely cut, it matches the terrain. Figure 24 and Figure 25 This is the stereoscopic effect of the earth-rock dam body before and after cutting by this method. Figure 26 and Figure 27 This is the downstream side view of the earth-rock dam body before and after cutting using this method.

[0116] Example 2

[0117] This embodiment provides a three-dimensional mesh generation system for finite element calculation of earth-rockfill dams considering foundation terrain matching, including:

[0118] A two-dimensional finite element mesh generation module is used to push the two-dimensional finite element mesh of the largest section of the earth-rock dam equidistantly along the dam axis to obtain the two-dimensional finite element meshes at all cross sections;

[0119] A three-dimensional finite element initial mesh construction module is used to connect the corresponding nodes of the two-dimensional finite element meshes of adjacent cross sections with connecting edges to construct a three-dimensional finite element initial mesh;

[0120] A terrain triangulation module is used to adjust the position of the ground line according to the two-dimensional nodes of the two-dimensional finite element grid to obtain a redrawn ground line, and to construct a node triangulation network of the redrawn ground lines between adjacent cross sections to obtain a terrain triangulation network;

[0121] A terrain up-down judgment module is used to judge the terrain up-down of all three-dimensional nodes of the three-dimensional finite element initial grid based on the relative elevation positions of the terrain triangulation network and the three-dimensional nodes;

[0122] The 3D mesh to be cut screening module is used to screen out cutting edges that intersect with the terrain triangulation network based on the 3D node terrain up-down information, and use the finite element initial mesh containing the cutting edges as the 3D mesh to be cut to match the terrain;

[0123] A three-dimensional grid to be cut splitting module is used to split all three-dimensional grids to be cut into two triangular prism grids;

[0124] A terrain cutting grade judgment module is used to assign a terrain cutting grade to the two-dimensional grids of the adjacent cross sections of the triangular prism grid according to the terrain up-down information of the three-dimensional node;

[0125] A 3D grid cutting model building module is used to build a 3D grid cutting model. It slides virtual cutting nodes on all edges of the triangular prism grid according to the 2D grid terrain cutting level of the adjacent cross section where the triangular prism grid is located, and obtains two 3D cut grids.

[0126] The zero volume mesh elimination module is used to determine whether all the meshes after three-dimensional cutting are zero volume meshes. If so, they are eliminated; otherwise, they are retained to obtain a three-dimensional finite element calculation mesh of the earth-rock dam that matches the terrain.

[0127] The above is only a preferred specific implementation method of the present application, but the scope of protection of the present application is not limited thereto. Any changes or replacements that can be easily thought of by any technician familiar with this technical field within the technical scope disclosed in this application should be covered by the scope of protection of the present application.

[0128] It should be understood that parts not elaborated in detail in this specification belong to the prior art.

[0129] It should be understood that the above description of the preferred embodiment is relatively detailed and cannot be regarded as limiting the scope of protection of the patent of the present invention. Under the guidance of the present invention, ordinary technicians in this field can also make substitutions or modifications without departing from the scope of protection of the claims of the present invention, which all fall within the scope of protection of the present invention. The scope of protection requested by the present invention shall be based on the attached claims.

Claims

1. A three-dimensional mesh generation method for finite element calculation of earth-rock dams considering foundation terrain matching, characterized by: The following steps are involved: The 2D finite element mesh of the largest section of the earth-rock dam is pushed evenly along the dam axis to obtain the 2D finite element meshes at all cross sections. Connect the corresponding nodes of the two-dimensional finite element meshes of adjacent cross sections with connecting edges to construct the three-dimensional finite element initial mesh; The positions of the ground lines are adjusted according to the two-dimensional nodes of the two-dimensional finite element grid to obtain redrawn ground lines, and the redrawn ground lines between adjacent cross sections are triangulated using nodes to obtain a terrain triangulation network; Based on the relative elevation positions of the terrain triangulation network and the three-dimensional nodes, terrain up-down judgment is performed on all three-dimensional nodes of the three-dimensional finite element initial mesh; the step of terrain up-down judgment on the three-dimensional nodes includes: For nodes on the terrain triangulation, the node terrain up-down property is judged as 0; For nodes whose elevation is higher than the terrain triangulation, the node terrain up-down property is judged as 1; For nodes whose elevation is lower than the terrain triangulation, the node terrain up-down judgment is -1; According to the terrain up-down information of the 3D nodes, the cutting edges that intersect with the terrain triangulation are screened out, and the finite element initial mesh containing the cutting edges is used as the 3D mesh to be cut to match the terrain; Split all three-dimensional grids to be cut into two triangular prism grids; According to the terrain up-down information of the 3D node, the terrain cutting level is assigned to the 2D grid of the adjacent cross section where the triangular prism grid is located; Construct a 3D grid cutting model and slide virtual cutting nodes on all edges of the triangular prism grid according to the 2D grid terrain cutting level of the adjacent cross section to obtain two 3D cut grids. Determine whether all the meshes after 3D cutting are zero volume meshes. If so, remove them. If not, retain them. Then obtain the 3D finite element calculation mesh of the earth-rock dam that matches the terrain.

2. The three-dimensional grid generation method for finite element calculation of earth-rock dam considering foundation terrain matching according to claim 1 is characterized by: The steps to redraw the ground line include: The three-dimensional nodes of the three-dimensional finite element initial grid are connected to find a multi-node connected polyline that is closest to the real ground line as the redrawn ground line; and the triangulation algorithm is used to construct a node triangulation network of the redrawn ground lines between adjacent cross sections to obtain a terrain triangulation network.

3. The three-dimensional grid generation method for finite element calculation of earth-rock dam considering foundation terrain matching according to claim 1 is characterized by: The cutting edge is an edge formed by connecting two end points of a node terrain with an up-down tendency of 1 and -1; and the three-dimensional grid to be cut is a three-dimensional grid containing at least one cutting edge.

4. The three-dimensional grid generation method for finite element calculation of earth-rock dam considering foundation terrain matching according to claim 1 is characterized by: The three-dimensional grid to be cut includes a triangular prism grid and a hexahedral grid. The hexahedral grid in the three-dimensional grid to be cut is cut into two triangular prism grids. The two-dimensional grids of adjacent cross sections where the triangular prism grids are located are all triangular grids.

5. The three-dimensional grid generation method for finite element calculation of earth-rock dam considering foundation terrain matching according to claim 4 is characterized by: The step of assigning terrain cutting levels to the two-dimensional grids of the adjacent cross sections where the triangular prism grid is located comprises: Assign terrain cutting level 1 to the triangle mesh with 3 nodes whose terrain up and down properties are 1, 1, 1; Assign terrain cutting level 2 to the triangle mesh with 3 nodes whose terrain up and down properties are 0, 1, and 1; Assign terrain cutting level 3 to the triangle mesh with 3 nodes whose terrain up and down properties are 0, 0, and 1; Assign a terrain cut level of 4 to the triangle mesh with 3 nodes whose terrain up and down properties are 0, 0, 0; Assign a terrain cut level of 5 to the triangle mesh with 3 nodes whose terrain up and down properties are 1, 0, and -1; Assign terrain cutting level 6 to the triangle mesh with 3 nodes whose terrain up and down properties are 0, 0, and -1; Assign terrain cut level 7 to the triangle mesh with 3 nodes whose terrain up and down properties are 0, -1, and -1; Assign a terrain cut level of 8 to the triangle mesh with 3 nodes whose terrain up and down properties are -1, -1, -1.

6. The three-dimensional grid generation method for finite element calculation of earth-rock dam considering foundation terrain matching according to claim 5 is characterized by: The steps to construct a 3D mesh cutting model include: Assume that the three edges of the triangular prism mesh to be cut are virtual cutting edges, and there are virtual cutting points on them. The initial positions of the three virtual cutting points are the midpoints of the edges. The three virtual cutting points form a virtual cutting surface, which is a three-dimensional mesh cutting model.

7. The three-dimensional grid generation method for finite element calculation of earth-rock dam considering foundation terrain matching according to claim 6 is characterized by: The implementation steps of the virtual cutting node sliding include: For a virtual cutting edge with a terrain combination of (-1, -1) at both endpoints, slide the virtual cutting node on the virtual cutting edge along the direction of the virtual cutting edge to the endpoint on the side with the lower terrain cutting level in the adjacent section. If the terrain cutting levels are equal, slide it to the endpoint on the side close to the middle section of the earth-rockfill dam. For a virtual cutting edge with two endpoints whose terrain up-down combination is (1,1) or (0,0), slide the virtual cutting node on the virtual cutting edge along the direction of the virtual cutting edge to the endpoint on the side with a higher terrain cutting level in the adjacent section. If the terrain cutting levels are equal, slide it to the endpoint on the side close to the middle section of the earth-rock dam. For a virtual cutting edge with two endpoints whose topographic combinations are (1, -1) or (-1, 1), slide the virtual cutting node on the virtual cutting edge along the direction of the virtual cutting edge to the position after the edge is cut by the terrain triangulation. For a virtual cutting edge whose two endpoints have a terrain up-down combination of (0, -1), (0, 1), (-1, 0) or (1, 0), slide the virtual cutting node on the virtual cutting edge along the direction of the virtual cutting edge to the endpoint where the terrain up-down is 0.

8. The three-dimensional grid generation method for finite element calculation of earth-rock dam considering foundation terrain matching according to claim 7 is characterized by: The steps to determine whether all 3D cut meshes are zero volume meshes include: After nesting the 3D cutting mesh model, if three virtual cutting nodes slide to the same cross section, the 3D cutting mesh will be a zero volume mesh and will be removed.

9. A 3D mesh generation system for finite element calculation of earth-rock dams considering foundation terrain matching is characterized by: include: A two-dimensional finite element mesh generation module is used to push the two-dimensional finite element mesh of the largest section of the earth-rock dam equidistantly along the dam axis to obtain the two-dimensional finite element meshes at all cross sections; A three-dimensional finite element initial mesh construction module is used to connect the corresponding nodes of the two-dimensional finite element meshes of adjacent cross sections with connecting edges to construct a three-dimensional finite element initial mesh; A terrain triangulation module is used to adjust the position of the ground line according to the two-dimensional nodes of the two-dimensional finite element grid to obtain a redrawn ground line, and to construct a node triangulation network of the redrawn ground lines between adjacent cross sections to obtain a terrain triangulation network; A terrain up-down judgment module is used to judge the terrain up-down of all three-dimensional nodes of the three-dimensional finite element initial grid based on the relative elevation positions of the terrain triangulation network and the three-dimensional nodes; The 3D mesh to be cut screening module is used to screen out cutting edges that intersect with the terrain triangulation network based on the 3D node terrain up-down information, and use the finite element initial mesh containing the cutting edges as the 3D mesh to be cut to match the terrain; A three-dimensional grid to be cut splitting module is used to split all three-dimensional grids to be cut into two triangular prism grids; A terrain cutting grade judgment module is used to assign a terrain cutting grade to the two-dimensional grids of the adjacent cross sections of the triangular prism grid according to the terrain up-down information of the three-dimensional node; A 3D mesh cutting model construction module is used to construct a 3D mesh cutting model. It slides virtual cutting nodes on all edges of the triangular prism mesh according to the 2D mesh terrain cutting level of the adjacent cross section to obtain two 3D cut meshes. A zero volume mesh elimination module is used to determine whether all meshes after 3D cutting are zero volume meshes. If so, they are eliminated; otherwise, they are retained to obtain a 3D finite element calculation mesh for the earth-rock dam that matches the terrain. The three-dimensional grid generation system for finite element calculation of earth-rock dam considering basic terrain matching is used to execute the steps of the three-dimensional grid generation method for finite element calculation of earth-rock dam considering basic terrain matching according to any one of claims 1-8.

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