Earth and rockfill dam finite element calculation three-dimensional grid generation method and system considering foundation terrain matching

Abstract

The invention discloses an earth and rockfill dam finite element calculation three-dimensional grid generation method and system considering foundation terrain matching, and the method comprises the steps: carrying out the flat bulldozing of a maximum section two-dimensional finite element grid of an earth and rockfill dam to each cross section, and carrying out the connection between adjacent sections of all nodes, so as to generate a three-dimensional finite element initial grid; all cross section ground lines are redrawn to obtain a terrain triangulation network, the terrain context of all three-dimensional nodes is judged through the terrain triangulation network, three-dimensional grids to be cut are screened out and then processed into triangular prism grids in a unified mode, and terrain cutting grades of two-dimensional grids of front and back sections are given; and finally, nesting all triangular prism grids to be cut into the three-dimensional cutting grid model, and obtaining a cut three-dimensional grid matched with the terrain by using a virtual cutting node sliding method. According to the method, the virtual cutting node sliding method is used for covering the cutting conditions of all the three-dimensional grids, the three-dimensional grids at the bottom of the earth and rockfill dam are better matched with the terrain after being cut, and the precision of finite element analysis and calculation of the earth and rockfill dam is indirectly improved.

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] As a widely used dam type, earth-rock dam is favored due to its strong adaptability and high economy. As a powerful numerical analysis tool, finite element analysis has been used for stress and deformation analysis of earth-rock dam. This method can provide detailed internal stress and deformation data, which is essential for the design of large earth-rock dams. However, the accuracy and efficiency of finite element analysis largely rely on the quality of the computational mesh, especially under complex terrain conditions.

[0003] In practical applications, the foundation terrain of earth-rock dams is complex and changeable, and traditional mesh cutting technology is difficult to adapt to this complexity. Existing mesh generation methods, such as regular grid-based division or simple automatic mesh generation, usually cannot accurately match the foundation of earth-rock dams with the foundation terrain. Summary of the invention

[0004] In view of 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 taking into account the matching of the basic terrain. The method and system can consider the unevenness of the foundation of the earth-rock dam and the complexity of the basic terrain, and generate a three-dimensional grid for finite element calculation of the earth-rock dam that matches the basic 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] The three-dimensional grid generation method for finite element calculation of earth-rock dam considering foundation terrain matching provided in this application adopts the following technical solutions:

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

[0007] The two-dimensional finite element mesh of the largest section of the earth-rock dam is pushed evenly along the dam axis to obtain the two-dimensional 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 a three-dimensional finite element initial mesh;

[0009] The position of the ground line is adjusted according to the two-dimensional nodes of the two-dimensional finite element grid to obtain the redrawn ground line, and the redrawn ground lines between adjacent cross sections are constructed into a node triangulated network to obtain a terrain triangulated network;

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

[0011] According to the terrain up-down information of the three-dimensional 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 three-dimensional 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 three-dimensional node, the terrain cutting level is assigned to the two-dimensional grid of the adjacent cross section where the triangular prism grid is located;

[0014] Construct a three-dimensional grid cutting model, slide virtual cutting nodes on all edges in the triangular prism grid according to the two-dimensional grid terrain cutting level of the adjacent cross section where the triangular prism grid is located, and obtain two three-dimensional cut grids;

[0015] It is determined whether all the meshes after three-dimensional cutting are zero volume meshes. If so, they are eliminated. If not, they are retained to obtain the three-dimensional finite element calculation mesh of the earth-rock dam matching 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-segment line 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 up and down properties of the terrain by the three-dimensional node includes:

[0019] For nodes on the terrain triangulation network, the node terrain up and 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 and down property is judged as -1.

[0022] Furthermore, the cutting edge is an edge formed by connecting two end points of a node terrain whose up and down trends are a combination 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 grids are located includes:

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

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

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

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

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

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

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

[0032] The terrain cut level is assigned to the triangle mesh with 3 nodes whose terrain up and down properties are -1, -1, -1 as 8.

[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, 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, and the virtual cutting surface is a three-dimensional mesh cutting model.

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

[0036] For the virtual cutting edge with the terrain up-down combination of the two endpoints being (-1,-1), the virtual cutting node on the virtual cutting edge is slid 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, it is slid to the endpoint on the side close to the middle section of the earth-rock dam.

[0037] For the virtual cutting edge with the terrain up-down combination of the two endpoints being (1,1) or (0,0), the virtual cutting node on the virtual cutting edge is slid 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, it is slid to the endpoint on the side close to the middle section of the earth-rock dam.

[0038] For a virtual cutting edge whose two endpoints have a terrain up-down combination of (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), 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.

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

[0041] After the 3D cutting mesh model is nested, 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] On the other hand, the present invention provides a three-dimensional grid generation system for finite element calculation of earth-rock dam considering basic 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 construction 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 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 mesh according to the relative elevation positions of the terrain triangulation network and the three-dimensional nodes;

[0047] A 3D mesh screening module for cutting is used to screen out cutting edges that intersect with the terrain triangulation network according to the terrain up-down information of the 3D nodes, 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 splitting module is used to split all three-dimensional grids to be cut into two triangular prism grids;

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

[0050] A three-dimensional grid cutting model building module is used to build a three-dimensional grid cutting model. According to the two-dimensional grid terrain cutting level of the adjacent cross section where the triangular prism grid is located, all edges in the triangular prism grid are slid with virtual cutting nodes to obtain two three-dimensional cut grids.

[0051] A zero volume mesh elimination module is used to determine whether all 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 an 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, thereby achieving accurate matching of the basic terrain.

[0054] 2. Improve calculation accuracy. Compared with the prior art, the present invention can simulate the three-dimensional structure of the earth-rock dam more accurately 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 dam.

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

[0057] The coordinate axis directions of all the drawings are unified as follows: 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 of the dam to the top of the dam, and the positive direction of the Z axis is from the left bank of the dam to the right bank of the dam, that is, the axial direction of the dam;

[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 basic terrain matching in an embodiment of the present application;

[0059] Figure 2 A two-dimensional finite element mesh of the largest section of the earth-rock dam in the embodiment of the present 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 4A schematic 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 A 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 A schematic diagram of a three-dimensional finite element initial mesh of an earth-rock dam constructed in an embodiment of the present application;

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

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

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

[0067] Fig.10 The ground line of a certain section in the embodiment of the present application is redrawn to represent the schematic diagram of the two-dimensional finite element mesh of the largest section of the earth-rock dam;

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

[0069] Fig.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] Fig.13 A schematic diagram of a terrain triangulation network in an embodiment of the present application;

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

[0072] Fig.15 A schematic diagram of a three-dimensional node judging the up and down nature of terrain according to its relative elevation to the terrain triangulation network in an embodiment of the present application;

[0073] Fig.16 This is a schematic diagram of determining the up and down nature of terrain based on the relative elevation of a node of a grid in a two-dimensional plane in an embodiment of the present application;

[0074] Fig.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] Fig.18 A schematic diagram of a triangular prism grid being cut by a terrain triangulation network in an embodiment of the present application;

[0076] Fig.19 A schematic diagram of a hexahedral grid in a grid to be cut being split into two triangular prism grids in an embodiment of the present application;

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

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

[0079] Fig. 22 A schematic diagram of different cutting conditions formed by a three-dimensional mesh to be cut, a nested three-dimensional mesh cutting model, and the application of a virtual cutting node sliding method in an embodiment of the present application;

[0080] Fig.23 It is a stereogram of the bottom mesh of the three-dimensional finite element initial mesh of the earth-rock dam in the embodiment of the present application after being cut;

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

[0082] Fig.25 This is a stereoscopic image of the earth-rock dam body after matching the terrain in the embodiment of the present application;

[0083] Fig.26 It is a downstream side view of the earth-rock dam body before it passes through the matching terrain in the embodiment of the present application;

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

[0085] In order to make the above-mentioned purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are described in detail below in conjunction with the accompanying drawings. In the following description, many specific details are set forth to facilitate a full understanding of the present application. However, the present application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without violating the connotation of the present application, so the present application is not limited by 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 here can be implemented in an order other than that illustrated or described here. In addition, the terms "including" and "having" and any of their variations 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 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 change 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 in this application is a logical division. There may be other division methods in actual application. For example, multiple units may be combined or integrated into another system, or some features may be ignored or not executed. In addition, the coupling or direct coupling or communication connection between each other shown or discussed may be through some interfaces, and the indirect coupling or communication connection between units may be electrical or other similar forms, which are not limited in this application. Moreover, the units or sub-units described as separate components may or may not be physically separated, may or may not be physical units, or may be distributed in multiple circuit units, and some or all of the units may be selected according to actual needs to achieve the purpose of the present application.

[0087] Example 1

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

[0089] The present application embodiment 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 method is pushed horizontally along the dam axis and replicated at all cross sections to obtain a two-dimensional finite element mesh at all cross sections.

[0091] In this embodiment, the maximum cross-section of the earth-rock dam is obtained by utilizing the similar shapes of the sections of the earth-rock dam, projecting the outer contour information of all cross-sections of the dam body to the same plane to obtain the union, and superimposing the material partition, filling stage 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 is composed only of triangular meshes and quadrilateral meshes.

[0092] S200: The two-dimensional finite element meshes between adjacent cross sections are projected and connected through connecting edges. The triangular mesh and the quadrilateral mesh are as follows Figure 4 and Figure 5 As shown in the figure, after the projections are connected, a triangular prism mesh and a hexahedron mesh are formed. The initial mesh of the three-dimensional finite element is composed of a triangular prism mesh and a hexahedron mesh. When all the meshes are connected after projection, 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 , Fig. 9 The original true ground line shown is redrawn as Fig.10 , Fig.11 The redrawn ground line shown is formed by connecting only the existing grid nodes. Fig.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 Fig.13 and Fig.14 The terrain triangulation shown.

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

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

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

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

[0098] S500: According to 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 three-dimensional meshes to be cut. The three-dimensional meshes to be cut are three-dimensional meshes containing one or more cutting edges, which are considered to be cut to match the terrain, such as Fig.17 and 18 shown.

[0099] S600: Convert the hexahedral mesh in the 3D mesh to be cut into Fig.19 The hexahedral mesh of the three-dimensional mesh to be cut is cut into two triangular prism meshes because the cutting of the quadrilateral meshes on the front and rear ends is complicated. Therefore, 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 topographic up and down properties of the nodes, assigning terrain cutting levels to the front and rear section grids of the three-dimensional grid to be cut, such as Fig. 20 As shown, the two-dimensional grids of adjacent cross sections are obtained by projection replication, but the relative positions of the ground line elevations of the 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 and down properties are 1, 1, 1.

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

[0107] S706: Assign a terrain cutting level of 6 to the three triangle meshes whose top and bottom properties are 0, 0, and -1.

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

[0110] S800: Nest all three-dimensional grids to be cut as follows Fig.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 influence of the number of node sliding on the mesh cutting situation is shown in the figure. Fig. 22 As shown, specifically including the following situations:

[0111] S801: For a mesh 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, after the node slides, the shape becomes a pyramid mesh.

[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 removed as a zero volume mesh.

[0115] S900: Fig.23 As shown in the figure, after all the bottom meshes of the initial mesh of the earth-rock dam 3D finite element are cut, they match the terrain. Fig.24 and Fig.25 This is the stereoscopic effect of the earth-rock dam body before and after cutting by this method. Fig.26 and Fig. 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 grid generation system for finite element calculation of earth-rock dam considering basic 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 construction 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 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 mesh according to the relative elevation positions of the terrain triangulation network and the three-dimensional nodes;

[0122] A 3D mesh screening module for cutting is used to screen out cutting edges that intersect with the terrain triangulation network according to the terrain up-down information of the 3D nodes, 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 splitting module is used to split all three-dimensional grids to be cut into two triangular prism grids;

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

[0125] A three-dimensional grid cutting model building module is used to build a three-dimensional grid cutting model. According to the two-dimensional grid terrain cutting level of the adjacent cross section where the triangular prism grid is located, all edges in the triangular prism grid are slid with virtual cutting nodes to obtain two three-dimensional 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 the three-dimensional finite element calculation mesh of the earth-rock dam that matches the terrain.

[0127] The above is only a preferred specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that can be easily conceived by any technician familiar with the technical field within the technical scope disclosed in the present application should be covered within the protection scope 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 patent protection of the present invention. Under the enlightenment 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 for the present invention shall be based on the attached claims.

Claims

1. A three-dimensional grid generation method for finite element calculation of earth-rock dam considering foundation terrain matching, characterized by: The following steps are involved: The two-dimensional finite element mesh of the largest section of the earth-rock dam is pushed evenly along the dam axis to obtain the two-dimensional 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 a three-dimensional finite element initial mesh; The position of the ground line is adjusted according to the two-dimensional nodes of the two-dimensional finite element grid to obtain the redrawn ground line, and the redrawn ground lines between adjacent cross sections are constructed into a node triangulated network to obtain a terrain triangulated network; According to the relative elevation position between the terrain triangulation network and the 3D nodes, the terrain up and down property of all the 3D nodes of the 3D finite element initial mesh is judged; According to the terrain up-down information of the three-dimensional 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 three-dimensional 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 three-dimensional node, the terrain cutting level is assigned to the two-dimensional grid of the adjacent cross section where the triangular prism grid is located; Construct a three-dimensional grid cutting model, slide virtual cutting nodes on all edges in the triangular prism grid according to the two-dimensional grid terrain cutting level of the adjacent cross section where the triangular prism grid is located, and obtain two three-dimensional cut grids; It is determined whether all the meshes after three-dimensional cutting are zero volume meshes. If so, they are eliminated. If not, they are retained to obtain the three-dimensional finite element calculation mesh of the earth-rock dam matching the terrain.

2. The three-dimensional grid generation method for finite element calculation of earth-rock dam considering basic 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-segment line 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 earth-rock dam finite element calculation considering foundation terrain matching according to claim 1 is characterized by: The step of determining the up and down properties of the terrain by the three-dimensional node includes: For nodes on the terrain triangulation network, the node terrain up and 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 and down property is judged as -1.

4. The three-dimensional grid generation method for earth-rock dam finite element calculation 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 whose up and down trends are a combination of 1 and -1; and the three-dimensional grid to be cut is a three-dimensional grid containing at least one cutting edge.

5. 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.

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 step of assigning terrain cutting levels to the two-dimensional grids of the adjacent cross sections where the triangular prism grids are located comprises: Assign a terrain cutting level of 1 to the triangle mesh with 3 nodes whose terrain up and down properties are 1, 1, 1; Assign a terrain cutting level of 2 to the triangle mesh with 3 nodes whose terrain up and down properties are 0, 1, and 1; Assign a terrain cutting level of 3 to the triangle mesh with 3 nodes whose terrain up and down properties are 0, 0, and 1; Assign a terrain cutting level of 4 to the triangle mesh with 3 nodes whose terrain up and down properties are 0, 0, 0; Assign a terrain cutting level of 5 to the triangle mesh with 3 nodes whose terrain up and down properties are 1, 0, and -1; Assign a terrain cut level of 6 to the triangle mesh with 3 nodes whose terrain up and down properties are 0, 0, and -1; Assign a terrain cut level of 7 to the triangle mesh with 3 nodes whose terrain up and down properties are 0, -1, -1; The terrain cut level is assigned to the triangle mesh with 3 nodes whose terrain up and down properties are -1, -1, -1 as 8.

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 steps of constructing a 3D mesh cutting model include: Assume that the three edges of the triangular prism mesh to be cut are virtual cutting edges, 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, and the virtual cutting surface is a three-dimensional mesh cutting model.

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 implementation steps of the virtual cutting node sliding include: For the virtual cutting edge with the terrain up-down combination of the two endpoints being (-1,-1), the virtual cutting node on the virtual cutting edge is slid 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, it is slid to the endpoint on the side close to the middle section of the earth-rock dam. For the virtual cutting edge with the terrain up-down combination of the two endpoints being (1,1) or (0,0), the virtual cutting node on the virtual cutting edge is slid 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, it is slid to the endpoint on the side close to the middle section of the earth-rock dam. For a virtual cutting edge whose two endpoints have a terrain up-down combination of (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.

9. The three-dimensional grid generation method for finite element calculation of earth-rock dam considering foundation terrain matching according to claim 8 is characterized by: The steps of judging whether all the meshes after 3D cutting are zero volume meshes include: After the 3D cutting mesh model is nested, 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.

10. A three-dimensional grid generation system for finite element calculation of earth-rock dam considering foundation terrain matching, 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 construction 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 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 mesh according to the relative elevation positions of the terrain triangulation network and the three-dimensional nodes; A 3D mesh screening module for cutting is used to screen out cutting edges that intersect with the terrain triangulation network according to the terrain up-down information of the 3D nodes, 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 splitting module is used to split all three-dimensional grids to be cut into two triangular prism grids; A terrain cutting level judgment module is used to assign a terrain cutting level to the two-dimensional grid of the adjacent cross section where the triangular prism grid is located according to the terrain up-down information of the three-dimensional node; A three-dimensional grid cutting model building module is used to build a three-dimensional grid cutting model. According to the two-dimensional grid terrain cutting level of the adjacent cross section where the triangular prism grid is located, all edges in the triangular prism grid are slid with virtual cutting nodes to obtain two three-dimensional cut grids. A zero volume mesh elimination module is used to determine whether all 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 an 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 in the three-dimensional grid generation method for finite element calculation of earth-rock dam considering basic terrain matching as described in any one of claims 1-9.

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