Underground cavern group engineering design and analysis integrated CAE modeling method

Abstract

In order to reduce the complexity of underground cavern engineering modeling and improve the modeling efficiency, the invention provides an underground cavern engineering design and analysis integrated CAE modeling method, which has the core that a cavern excavation body, a cavern area mountain and a surrounding rock supporting structure model are obtained from a cavern engineering 3DE design result; an established 3DE underground cavern excavation support modeling pretreatment program drives 3DE to complete cavern step-by-step excavation support entity modeling according to a cavern layered excavation and support design scheme, outputs a key modeling information file, drives Gmsh to reproduce an entity modeling process in 3DE by using the file, and performs mesh generation on a volume entity on the basis, so as to obtain an underground cavern excavation support modeling model. And naming according to the volume entity number in the modeling key information file, and finally outputting a model grid file, so that the underground cave group three-dimensional design result is directly used for carrying out cave group step-by-step excavation support numerical simulation modeling and model grid automatic subdivision.

Description

Technical Field

[0001] The present invention mainly relates to the technical field of numerical simulation of rock and soil underground engineering, and in particular to an integrated CAE modeling method for engineering design analysis of underground cavern groups. Background Art

[0002] The CAD / CAE integrated technology builds a "bridge" between design and computational analysis, enabling design results to be smoothly used for three-dimensional numerical modeling, and then carrying out computational analysis on the rationality of design schemes. Therefore, it can effectively improve the efficiency of design scheme optimization and numerical computational analysis.

[0003] At present, the research on CAD / CAE integrated technology carried out in the field of hydropower engineering mainly focuses on the design of hydraulic structures. For example: based on the CATIA three-dimensional design platform and ANSYS finite element software, the shape design and optimization analysis of the steel bifurcation pipe of a hydropower station are realized; through CAPRI, the model data transmission between CATIA and ANSYS is realized to achieve the optimal design of the tunnel lining structure; the ISIGHT platform is used to integrate the CATIA and Abaqus finite element software to realize the optimal design of the section parameters of a concrete gravity dam, etc. These existing technologies are only applicable to hydraulic structures with relatively simple and regular shapes and are difficult to be applied to the underground cavern group projects of large hydropower projects.

[0004] The main problems involved in the design optimization of large hydropower underground cavern group projects include the optimization of cavern group layout, the excavation procedure and support optimization of caverns, etc. Therefore, in the CAD stage, geological body modeling, cavern group modeling and cavern group support system modeling need to be carried out, and in the CAE stage, according to the actual excavation and support sequence, the simulation calculation of the step-by-step excavation and support of the cavern group needs to be carried out. For the design optimization of hydropower underground engineering, the main bottleneck lies in the numerical modeling link in the CAE stage, and the main problems are: (1) Limited by finite element modeling tools, it is difficult to reuse design models; (2) The excavation and support procedures of cavern groups are complex, and the manual finite element modeling operation is monotonous and cumbersome, with low efficiency; (3) Limited by the low efficiency of manual operation, it is difficult to quickly respond to changes in geological bodies.

[0005] The 3DE 3D design platform software has powerful 3D solid modeling capabilities and is widely used in the hydropower engineering field for 3D forward design. It also provides a rich set of secondary development interface functions, facilitating the creation of 3D solid models of cavern groups under complex geological conditions through code compilation. However, it does not have the function of mesh generation for solid models. Gmsh is an open-source software that can perform 3D solid modeling and mesh generation. Although its solid modeling ability is relatively weak, it provides the function of directly importing solid models in various formats. Compared with the mesh generation functions built into ANSYS and Abaqus, as well as specialized mesh generation tool software such as Hypermesh, its advantage lies in providing a scripting language and secondary development API functions for solid modeling and solid mesh generation, facilitating the modeling and mesh generation of 3D solids through code compilation. Therefore, it is feasible to integrate the design and analysis of large underground cavern group projects based on 3DE and Gmsh. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to provide an integrated CAE modeling method for the design and analysis of underground cavern group projects, aiming to reduce the complexity of CAE modeling for underground cavern group projects and improve the modeling efficiency.

[0007] The technical solution adopted by the present invention to solve the above technical problems is as follows:

[0008] An integrated CAE modeling method for the design and analysis of underground cavern group projects, the method comprising the following steps:

[0009] Step 1: Obtain the 3DE model of the cavern group excavation body, the 3DE model of the mountain body in the cavern group area, and the 3DE model of the surrounding rock support structure of the cavern group. The 3DE model of the cavern group excavation body does not contain information on rock mass types and structural planes, and the 3DE model of the mountain body in the cavern group area includes 3DE models of various rock masses and structural planes at all levels;

[0010] Step 2: Based on 3DE, write a pre-processing program for underground cavern group excavation and support modeling. Using the 3DE model of the cavern group excavation body, the 3DE model of the mountain body in the cavern group area, and the 3DE model of the surrounding rock support structure of the cavern group as the input of the pre-processing program for underground cavern group excavation and support modeling, drive 3DE to layer and block each cavern body according to the design scheme of chamber-by-chamber excavation and support. After fusing the layered and blocked cavern bodies with the surrounding mountain body, then fuse the mountain body itself, and output the key modeling information for step-by-step excavation and support simulation of the cavern group;

[0011] Step 3: Based on Gmsh, write a program for automatic mesh generation of the underground cavern group model. Combine the key modeling information output in Step 2 for step-by-step excavation and support simulation of the cavern group to drive Gmsh to reproduce the solid modeling process in 3DE, perform mesh generation on the volume entities, and output the model mesh file;

[0012] Step 4: Based on the information of the step-by-step excavation and support modeling of the cavern group output in Step 2 and the model mesh file output in Step 3, a command file for simulating the excavation and support process of the cavern group is formed.

[0013] Furthermore, the key modeling information for the step-by-step excavation and support simulation of the cavern group includes:

[0014] (1) Naming information, spatial range information, and rock type attribute information of the layered and block-excavated bodies of the cavern group and the surrounding rock mass of the caverns;

[0015] (2) The cavern group excavation bodies involved in each excavation step;

[0016] (3) Geometric information, material property information, and support timing information of the surrounding rock support structure.

[0017] Furthermore, Step 2 includes:

[0018] Step 2.1: Based on the established pre-processing program for the excavation and support modeling of the underground cavern group, drive 3DE to perform layer-by-layer and block-by-block division of each cavern in the cavern group according to the layer-by-layer and block division scheme set in the cavern layer excavation and support design plan, and perform entity fusion and attribute fusion of the divided cavern bodies with the mountain body to obtain the layer-by-layer and block-excavated bodies of the caverns integrated with rock type information and structural plane information;

[0019] Step 2.2: Define the step-by-step excavation process of the cavern group based on the pre-processing program for the excavation and support modeling of the underground cavern group, and determine at which excavation step the layers and blocks of the caverns are to be excavated;

[0020] Step 2.3: Based on the established pre-processing program for the excavation and support modeling of the underground cavern group, drive 3DE to perform entity fusion and attribute fusion of various rock masses around the caverns with secondary and tertiary structural planes to obtain the surrounding rock mass of the caverns integrated with rock type information and structural plane information;

[0021] Step 2.4: Set the material properties and support timing of the support structure, and extract the geometric information of the support structure.

[0022] Furthermore, the method further includes: In Step 2.3, based on the spatial range of the cavern group excavation body, expand a set range outward in six directions, namely up, down, left, right, front, and back, of the excavation body to form a box body. Take the surrounding rock area of the caverns within the box body as the core area around the caverns, and the area outside the box body as the non-core area around the caverns. When Gmsh performs mesh division on the volume entity in Step 3, set different mesh sizes for the core area and the non-core area around the caverns to optimize the calculation efficiency.

[0023] Further, in step 2.4, after setting the material properties of the support structure, drive 3DE to re-model the support structure according to the vector lines determined by the intersection points of the support structure and the cave wall, the head and tail nodes of the support structure, and the support structure length information in the material properties, ensuring that the head node of the support structure is within the surrounding rock.

[0024] Further, in step 2.4, the support timing is indirectly set by specifying the anchoring activation delay parameter for each layer of the cavern excavation.

[0025] Further, the method further includes step 2.5: saving the key modeling information of the staged excavation support simulation of the cavern group in the form of data blocks using a text file, and driving Gmsh to reproduce the entity modeling process in 3DE.

[0026] Further, step 3 includes:

[0027] Step 3.1: Export the 3DE models of the cavern group excavation body and the mountain body in the cavern group area as step format files. Based on the mesh automatic meshing program of Gmsh, identify the caverns in the step file, and drive Gmsh to perform staged excavation modeling of the caverns according to the cavern identification results and the staged excavation design information of the caverns, the entity fusion of the staged excavation body of the caverns and the mountain body, and the entity fusion of the mountain body itself;

[0028] Step 3.2: Use the physical group naming function of Gmsh to assign a physical group to each volume entity in the model, and name the physical group to which the volume entity belongs according to the naming information of the cavern group excavation body and the surrounding rock mass of the cavern in the key modeling information output in step 2;

[0029] Step 3.3: Set the mesh element sizes for the model cavern group area, the core area around the cavern, and the non-core area respectively, and Gmsh performs mesh meshing. After successful meshing, the model mesh file is output.

[0030] Further, the method further includes step 3.4: If there are tertiary structural planes in the model, identify the tertiary structural planes in the model, output the physical group name information of the rock masses above and below the tertiary structural planes, and create interface elements for simulating the structural mechanical behavior based on the physical group name information.

[0031] Further, the specific method of step 3.4 is as follows: Based on the Gmsh API function GetEntitiesInBoundingBox, obtain the surface entity objects in the model. Based on the Gmsh API function getNodes, obtain the nodes on the surface entity, and use getNormal to obtain the normal vectors at the nodes. By judging whether the normal vectors at the nodes are the same, determine whether the surface entity is a plane. Based on the Gmsh API functions getAdjacencies, getPhysicalGroupForEntity, and getPhysicalName, extract the volume entity on both sides of the surface entity and its physical group name.

[0032] The beneficial effects of the present invention are as follows:

[0033] 1. The present invention proposes an integrated CAE modeling method for the engineering design and analysis of underground cavern groups. This method fully combines the entity modeling function of 3DE software and the mesh meshing ability of Gmsh software, and compiles a numerical modeling auxiliary tool program using the secondary development API functions of 3DE and Gmsh. It can drive 3DE to complete the step-by-step excavation and support modeling of large underground cavern groups, and drive Gmsh to complete the automatic mesh meshing of the entity model. The advantage of this method is to achieve the reuse purpose of three-dimensional design results, eliminate the operation of remolding the existing three-dimensional design results during numerical modeling, effectively shorten the modeling cycle, and lay a foundation for the integrated engineering design and analysis of large underground cavern groups.

[0034] 2. By compiling the preprocessing program for the excavation and support modeling of large underground cavern groups and the automatic mesh meshing program for complex cavern group models, the present invention replaces the monotonous and cumbersome manual modeling process of numerical simulation, greatly compresses the time-consuming of numerical simulation modeling, and indirectly shortens the time cycle for the design and optimization of engineering solutions.

[0035] 3. Before establishing the preprocessing program for the excavation and support modeling of underground cavern groups, the present invention disassembles the mountain body into various rock masses and structural planes at all levels. On the one hand, it is more adaptable to the requirements of integrated design and analysis modeling and conforms to the conventional operation specifications of the industry; on the other hand, it also provides convenience for adding or modifying structural planes. During the construction stage, with the continuous exposure of excavation, compared with the feasibility study and design stage, the number of structural planes may increase, and the spatial position of the structural planes may also change. If the design result is already a fusion of rock masses and structural planes, then once the structural plane changes, it is necessary to re-fuse at the design end. However, when the rock masses and structural planes are modeled separately, the design end only needs to provide the updated structural planes.

[0036] (4) The support timing of the support structure is not directly set on each support structure object, but is indirectly set by specifying the anchoring activation delay parameter for each layer of the cavern excavation. When the step-by-step excavation plan of the cavern group changes, it is not necessary to adjust the support timing of the support structure to ensure the correctness of the sequence of excavation and support, and it can ensure that the phenomenon of'supporting before excavation' does not occur. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 It is a flowchart of the preprocessing program for the excavation and support modeling of the underground cavern group described in the present invention;

[0038] Figure 2 It is a flowchart of the grid automatic meshing program processing based on Gmsh described in the present invention;

[0039] Figure 3 It is a schematic diagram of the setting of the core area around the cavern described in the present invention;

[0040] Figure 4 It is a schematic diagram of the end, through and invalid anchor cables (rods) described in the present invention;

[0041] Figure 5 It is a schematic diagram before and after the reconstruction of the anchor cable (rod) described in the present invention;

[0042] Figure 6 It is a flowchart for identifying the volume entities of the hanging wall and footwall of the third-level structural plane described in the present invention;

[0043] Figure 7 It is the design result of the underground powerhouse cavern group model of Yeba Tan Hydropower Station in the embodiment;

[0044] Figure 8 It is the design result of the anchor cable model in the underground powerhouse cavern group area of Yeba Tan Hydropower Station in the embodiment

[0045] Figure 9 It is the design result of the mountain body model in the underground powerhouse cavern group area of Yeba Tan Hydropower Station in the embodiment;

[0046] Figure 10 It is a fusion result diagram of the layered excavation body and the third-level structural plane of the underground cavern group of Yeba Tan Hydropower Station in the embodiment;

[0047] Figure 11 It is the result of layering the caverns and fusing them with the mountain body recorded on the 3DE model structure tree of the cavern group in the embodiment;

[0048] Figure 12(a) shows the step-by-step excavation setting of the cavern group in the embodiment;

[0049] Figure 12(b) shows a schematic diagram of the storage of the step-by-step excavation information of the cavern group on the 3DE in the embodiment;

[0050] Figure 13(a) shows the setting of the cable bolt support timing in the embodiment;

[0051] Figure 13(b) is a schematic diagram of the cable bolt activation delay in the embodiment;

[0052] Figure 14(a) shows the fusion result of the surrounding rock in the core area around the holes of Yeba Tan Hydropower Station in the embodiment;

[0053] Figure 14(b) shows the fusion result of the surrounding rock in the non-core area around the holes of Yeba Tan Hydropower Station in the embodiment;

[0054] Figure 15 It is the result of the progressive fusion of the surrounding rock mass of the holes recorded on the 3DE model structure tree of the hole group in the embodiment;

[0055] Figure 16 It is the input setting diagram of the mesh generation program interface of Gmsh in the embodiment;

[0056] Figure 17 It is the result diagram of the solid modeling reproduced in Gmsh of Yeba Tan Hydropower Station in the embodiment;

[0057] Figure 18 It is the mesh generation result of the hole group model in Gmsh in the embodiment;

[0058] Figure 19 It is the model mesh diagram imported into FLAC3D in the embodiment;

[0059] Figure 20 It is the interface element diagram representing the tertiary structural plane in the Yeba Tan powerhouse hole group area in FLAC3D of the embodiment;

[0060] Figure 21 It is the Cable element diagram representing the cable bolts in the Yeba Tan powerhouse hole group area in FLAC3D of the embodiment. Detailed implementation manners

[0061] To facilitate the explanation of the technical details of the present invention, the relevant concepts defined in the present invention are first explained:

[0062] (1) Rock mass. In the present invention, the rock mass specifically refers to the rock masses of various levels divided from the mountain body within the modeling range according to the rock mass classification method, such as class II rock mass (fresh and slightly weathered rock mass), class III rock mass (weakly weathered rock mass), class IV rock mass (strongly weathered rock mass), etc., which do not include structural planes.

[0063] (2) Structural plane. Geologically, structural planes are usually classified according to their scale (length, thickness). Since the area of the underground cavern group in hydropower projects is relatively limited and carefully selected, the first-level structural planes (regional fault zones) are deliberately avoided. Therefore, in the present invention, only the second-level and third-level structural planes are explicitly simulated, and the structural planes above level IV (also called joints) are not explicitly simulated but are equivalent to the rock mass.

[0064] (3) Mountain body. In the present invention, the area where the cavern group is located is called the mountain body, which is a complex composed of various rock masses, second-level structural planes, and third-level structural planes.

[0065] The integrated CAE modeling method for the engineering design and analysis of the underground cavern group described in the present invention includes the following steps:

[0066] Step 1: Obtain the 3DE model of the cavern group excavation body and the 3DE model of the mountain body in the cavern group area. The 3DE model of the cavern group excavation body does not include the 3DE model of rock types and structural planes, and the 3DE model of the mountain body in the cavern group area includes the 3DE models of various rock masses and structural planes at all levels;

[0067] Step 2: Based on 3DE, write a preprocessing program for the modeling of the excavation and support of the underground cavern group. Using the 3DE model of the cavern group excavation body, the 3DE model of the mountain body in the cavern group area, and the 3DE model of the cavern group support (anchor cables, anchor bolts) as the input of the preprocessing program for the modeling of the excavation and support of the underground cavern group, drive 3DE to layer and block each cavern body according to the design scheme of the chamber-by-chamber excavation and support, and perform the fusion of the chamber-by-chamber excavation body and the surrounding mountain body as well as the self-fusion of the surrounding mountain body itself, and output the key information for the step-by-step excavation and support simulation of the cavern group; The key information for the step-by-step excavation and support simulation of the cavern group specifically includes:

[0068] (1) Naming information, spatial range information, and rock type attribute information of the cavern group excavation body and the surrounding rock mass;

[0069] (2) The cavern group excavation body involved in each excavation step;

[0070] (3) Geometric information, material property information, and support timing information of the surrounding rock support structure.

[0071] As Figure 1 shown, the specific method for obtaining the key information for the step-by-step excavation and support simulation of the cavern group is:

[0072] Step 2.1: Modeling of the step-by-step excavation of the cavern group and the integration of the layered excavation body with the mountain body. That is: through the pre-processing program for the excavation support modeling of the underground cavern group, drive 3DE to divide each cavern body in the cavern group into layers and blocks according to the set layered and block-divided scheme, and then integrate the layered and block-divided cavern bodies with the mountain body. The so-called integration includes two levels: entity integration and attribute integration. The so-called entity integration is the Boolean intersection and Boolean removal of the cavern excavation body with geological bodies such as various rock masses, secondary structural planes, and tertiary structural planes, and the attribute integration is the by-product of the entity integration process. That is, during the entity integration process, the attributes of the cavern excavation body are iteratively updated, evolving from only containing cavern attribute information to finally including, in addition to the basic attribute of the cavern attribute, excavation layer and block information, rock mass category information, secondary structural plane information, and tertiary structural plane information.

[0073] Step 2.2: Definition of the construction process of the step-by-step excavation of the cavern group. That is: divide the excavation process of the cavern group into several excavation steps, and determine in which excavation step each layer (and block) of each cavern is excavated.

[0074] Step 2.3: Self-integration of the rock mass around the cavern. That is: through the pre-processing program for the excavation support modeling of the underground cavern group, drive 3DE to complete the self-integration of the rock mass around the cavern, that is, the integration of various rock masses around the cavern with secondary structural planes and tertiary structural planes. The integration here also includes entity integration and attribute integration. Entity integration refers to the Boolean operations (including intersection, removal, and cutting, etc.) of various rock masses around the cavern with secondary structural planes and tertiary structural planes, and attribute integration refers to the iterative update of the surrounding rock entity attributes during the entity integration process, that is: evolving from only containing rock type information to finally also including secondary structural plane information and tertiary structural plane information.

[0075] For the convenience of specifying the grid element size by zone during subsequent mesh generation and achieving the purpose of gradually increasing the mesh size outward from the cavern group, in Step 2.3, based on the spatial range of the cavern group excavation body, expand a certain range outward in the up, down, left, right, front, and back directions to form a 'box' body around the cavern (because it wraps the cavern group inside, so it is called the box body), as Figure 3 . Figure 3 where: ΔX + 、ΔX - 、ΔY + 、ΔY - 、ΔZ + 、ΔZ - respectively represent the lengths of the outward expansion along the positive and negative directions of the X-axis, the positive and negative directions of the Y-axis, and the positive and negative directions of the Z-axis. The rock mass area around the cavern within this box body is the core area around the cavern, and the area outside the box body is called the non-core area around the cavern. Before the integration with the secondary and tertiary structural planes, the rock mass around the cavern has been divided into two parts: the rock mass in the core area around the cavern and the rock mass in the non-core area.

[0076] Through the above steps 2.2 and 2.3, the layered modeling of the cavern and its integration with the mountain body, as well as the self-integration modeling of the mountain body around the cavern, are completed. Through attribute integration, the excavation attribute information and rock type attribute information of the entities in the model are obtained. These attribute information are the core information for forming the FLAC3D calculation commands.

[0077] Step 2.4: Extract the geometric information of the support structure and set the material properties and support timing of the support structure. When using the FLAC3D software to simulate the mechanical behavior of the surrounding rock support structure of the cavern (such as systematic bolts and cables), it is necessary to determine the geometric information, material property information, and support timing information of the support structure. In the design model of the cavern group, due to the large number and regular shape of the cables (bolts), they are often generated in an array manner during design modeling and named according to the cavern location where they are located, the elevation information of the installation hole orifice, and the cable type. Therefore, in the pre-processing program for the excavation and support modeling of the underground cavern group, first, the material properties and support timing of these cable array objects are set, and then 3DE is driven to disassemble these array objects to obtain single-cable objects represented by straight line segments, and further obtain the coordinate values of the start and end points of each cable (bolt) (i.e., the geometric information of the cable).

[0078] In this step, the support timing of the cables (bolts) is not directly set on each cable array object, but indirectly set by specifying the anchoring activation delay parameter for the layered excavation of the cavern. The anchoring activation delay parameter is the number of steps of the cable delay application, which is a natural number greater than or equal to 0, indicating how many (simulated) steps the cables in this excavation layer are lagged behind to be activated (applied). Assume that a certain excavation layer is excavated in the 1st (simulated) step. If the anchoring activation delay parameter of this excavation layer is set to 1, the cables in this layer will be activated in the 2nd (simulated) step. If the anchoring activation delay parameter is set to 0, the cables in this layer will also be activated in the 1st step, that is, the cables are applied immediately after excavation. The advantage of this indirect setting of the support timing of the cables (bolts) is that when the step-by-step excavation plan of the cavern group changes, it is not necessary to adjust the support timing of the cables (bolts) to ensure the correctness of the excavation and support sequence and prevent the phenomenon of 'pre-support before excavation'.

[0079] In this step, when the pre-processing program for the excavation and support modeling of the underground cavern group analyzes the design results of the cables (bolts), such as Figure 4As shown in the figure, the anchor cable with only one end intersecting with the chamber stratified excavation body is identified as the end anchor cable, the anchor cable with both ends intersecting with different chamber stratified excavation bodies is identified as the through anchor cable, and the anchor cable with neither end intersecting with the chamber stratified excavation body is identified as the invalid anchor cable. After setting the material properties of the anchor cable (rod), the pre-processing program for the excavation support modeling of the underground cavern group will drive 3DE to re-model the anchor cable (rod) based on the intersection points of the anchor cable (rod) and the cavern wall, the vector (direction) determined by the head and tail nodes of the anchor cable (rod), and the length information in the anchor cable material properties, ensuring that the head node of the anchor cable (rod) is located within the surrounding rock, as Figure 5 shown in the figure. The coordinates of the head and tail nodes of the finally extracted anchor cable (rod) do not come from the original design results, but from the re-created anchor cable (rod) object. The head node of the re-built anchor cable (rod) is located within the surrounding rock, which can ensure that when creating Cable elements in FLAC3D, the cable element nodes can establish correct connections with the surrounding rock elements; through the anchor cable (rod) reconstruction function of the pre-processing program for the excavation support modeling of the underground cavern group, the original design length of the anchor cable (rod) can be freely adjusted, so as to adapt to the actual application scenario of adjusting the anchor cable design length during the construction period.

[0080] In order to transfer data to the automatic mesh generation program based on Gmsh and take into account the readability of the data, step 2.5 is also included in step 2: saving and outputting the key information for the modeling of the step-by-step excavation support simulation of the cavern group in the form of data blocks in a text file.

[0081] The format of the data block is as follows:

[0082] "

xxx

[0083] Column header

[0084] Data row 1

[0085] …

[0086] Data row n"

[0087] In the present invention, the data blocks generated during the process of step 2.1 for modeling the step-by-step excavation of the cavern group and the integration process of the layered excavation body and the mountain body include: ① Cavern structure (its column headings are: serial number, cavern name, coordinate range); ② Cavern layered elevation (its column headings are: serial number, cavern name, excavation layered elevation); ③ Cavern excavation body (its column headings are: serial number, entity number, entity name, rock type number to which it belongs). The data blocks generated during the process of step 2.2 for defining the step-by-step excavation construction process of the cavern group include: Cavern group excavation sequence (its column headings are: serial number, excavation sequence number, entity number). The data block generated during the process of step 2.3 for the self-integration of the surrounding rock mass of the cavern includes the surrounding rock mass of the cavern, and its column headings are the same as those of the data block 'Cavern excavation body'. The data blocks related to step 2.1 and step 2.3 are: Entity spatial range (its column headings are: serial number, entity number, entity spatial range coordinates); the data blocks related to step 2.4 are: Geometric information, material properties and support timing of the support structure (its column headings are: Anchor cable (rod) number, head and tail node coordinates of the anchor cable (rod), material number to which it belongs, support timing (represented by the excavation sequence number of the cavern group). When there are tertiary structural planes in the model, a data block named 'Tertiary structural plane' will be added to the key modeling information file (its column headings are: serial number, positioning point coordinates, structural plane number).

[0088] Step 3: Write an automatic mesh generation program for the underground cavern group model based on Gmsh, and drive Gmsh to reproduce the entity modeling process in 3DE based on the key modeling information output in step 2 for the step-by-step excavation and support simulation of the cavern group, perform mesh generation on the volume entities, and output the model mesh file and the tertiary structural plane modeling information file.

[0089] Step 3.1: Use the geometric entity Boolean operation function provided by OpenCASCADE CAD of Gmsh to reproduce the entity modeling performed in 3DE in Gmsh. The reason for not directly importing the entity modeling result of 3DE into Gmsh is mainly to reduce the occurrence probability of the failure of the model entity mesh generation due to geometric reasons. It should be particularly noted that since step 3 is only for obtaining the model mesh file, only entity integration is required during the reproduction process, and attribute integration is not required.

[0090] Such as Figure 2As shown in the figure, the inputs required in the automatic meshing program for the underground cavern group model include two categories: First, the step format files exported from the two design results of the 3DE model of the cavern group excavation body and the 3DE model of the mountain body in the cavern group area, including the step file of the cavern group entity, the step file of the secondary structural plane entity, the step file of the tertiary structural plane entity, the step files of various rock masses, and the step file of the imaginary river valley erosion body entity (the step file of the secondary structural plane entity, the step file of the tertiary structural plane entity, the step files of various rock masses, and the step file of the imaginary river valley erosion body entity are optional); Second, the key modeling information output by the pre-processing program for the excavation and support modeling of the underground cavern group for the step-by-step excavation and support simulation of the cavern group.

[0091] The key to this operation step is to complete the excavation layering treatment of each cavern in Gmsh. The cavern group usually contains dozens of caverns, and each cavern has its own excavation layering design. Therefore, first, it is necessary to be able to correctly identify each cavern imported from the step file of the cavern group entity in Gmsh. Since the spatial ranges of the caverns cannot completely overlap, the method of comparing spatial ranges is used for identification. Specifically, the cavern is determined by comparing the spatial coordinate range of the cavern obtained by the API function 'getBoundingBox' of Gmsh and the cavern spatial range information in the 'cavern structure' data block output in step 2. On the basis of the correct identification of the cavern, the excavation layering modeling of the cavern is completed in Gmsh according to the cavern layering design information in the 'cavern layering elevation' data block output in step 2.

[0092] Step 3.2: In order to ensure that the unit group names in the mesh file output by Gmsh are consistent with the names of the cavern excavation body and the surrounding rock mass of the cavern output in step 2, use the physical group naming function of Gmsh to define a physical group for each volume entity in the model, and the group name is named correspondingly according to the naming information of the cavern group excavation body and the surrounding rock mass of the cavern output in the 'cavern excavation body' and 'cavern surrounding rock mass' data blocks in step 2.

[0093] Step 3.4: Adopt the logic as Figure 6 shown to identify the tertiary structural planes in the model, output the physical group name information of the rock masses on the upper and lower plates of the structural plane, and create interface elements for simulating the mechanical behavior of the structural plane based on the physical group name information of the rock masses on the upper and lower plates of the structural plane.

[0094] Step 4: Based on the step-by-step excavation and support modeling information of the cavern group output in step 2, the model mesh file output in step 3, and the tertiary structural plane modeling information file, form a command file for simulating the excavation and support process of the cavern group.

[0095] Example:

[0096] In this embodiment, taking the underground powerhouse cavern group project of Yeba Tan Hydropower Station as an example, the integrated CAE modeling method for the design and analysis of underground cavern group projects described in the present invention is further explained.

[0097] Step 1: Obtain the 3DE design model of the cavern group project of Yeba Tan Hydropower Station, including the underground cavern group model (each cavern should be an independent entity) as shown in Figure 7 , the anchor cable model of the underground cavern group area as shown in Figure 8 , and the mountain body model of the cavern group area as shown in Figure 9 . The mountain body model of the cavern group area includes: the modeled rock mass (volume entity), which is of the same type (type Ⅲ1) throughout the area; secondary structural planes (volume entities), a total of 3; and tertiary structural planes (plane entities), a total of 5.

[0098] Step 2: Based on 3DE, write a preprocessing program for the modeling of the excavation and support of the underground cavern group. Using the 3DE model of the cavern group excavation body, the 3DE model of the mountain body in the cavern group area, and the 3DE model of the surrounding rock support structure (anchor cables, bolts) of the cavern group as the input of the preprocessing program for the modeling of the excavation and support of the underground cavern group, drive 3DE to layer and block each cavern body according to the layered excavation and support design scheme of the caverns, fuse the layered and blocked cavern bodies with the surrounding mountain body, and then fuse the mountain body itself, and output the key modeling information for the step-by-step excavation and support simulation of the cavern group.

[0099] Step 2.1: Perform the layered excavation of the cavern group and the fusion of the layered excavation body with the mountain body. On the interface of the preprocessing program for the modeling of the excavation and support of the underground cavern group, after specifying the layered excavation elevation of each cavern in an interactive manner according to the layered excavation design scheme of the caverns, drive 3DE to complete the layered excavation modeling, and further drive 3DE to complete the fusion of the layered cavern body with the mountain body on this basis. The result is as shown in Figure 10 , and the fusion process and its intermediate results are recorded under the node of the cavern group excavation body modeling (underground cavern layering and blocking) on the 3DE model structure tree of the cavern group, as shown in Figure 11 ; Figure 11 In, the next-level nodes of the cavern group excavation body modeling node (such as layering, fusion with rock types, fusion with secondary structural planes, fusion with tertiary structural planes) record the results of the Boolean division of each cavern body with the layered plane, the Boolean intersection with various rock masses, the Boolean intersection with secondary structural planes, and the Boolean division with tertiary structural planes in sequence. From Figure 11It can be seen that the Boolean operation process of the integration of the chamber stratified body and the mountain body is a sequential and progressive operation process, that is: performing Boolean intersection with various rock masses is based on performing Boolean division with the stratified plane, and performing Boolean intersection with the secondary structural plane is based on performing Boolean intersection with various rock masses, and so on. In this process, the original chamber body is gradually decomposed, and the decomposed chamber body clearly records the traceability information of the above progressive operation process through its name, that is, the attribute information of the chamber entity. From this perspective, the above progressive operation process is also a process in which the entity attributes are continuously updated, that is, the entity attribute integration process described above.

[0100] Step 2.2: Setting the timing of staged excavation and cable anchor support for the underground cavern group. This step is completed interactively on the pre-processing program interface for the excavation support modeling of the underground cavern group. This process does not involve 3DE geometric operations, but the relevant definition information will be saved in the 3DE model shown in Figures 12(a) and 12(b) in the form of model parameters for subsequent output to files.

[0101] Step 2.3: Self-integration of the surrounding rock of the cavern. For the surrounding rock mass of the cavern, considering that it is necessary to control the size of the mesh elements in different zones during subsequent mesh meshing, it is divided into two parts: the core area around the cavern and the non-core area. The integration results of these two parts of the surrounding rock are shown respectively in Figure 14(a) and 14(b) as shown. This integration process and its intermediate results are recorded under the node of modeling of the surrounding rock mass of the cavern (rock mass faults of underground caverns) on the 3DE model structure tree of the cavern group shown in Figure 15 . In Figure 15 , the next-level nodes of the node of modeling of the surrounding rock mass of the cavern (such as zoning of the surrounding rock of the cavern, integration with the secondary structural plane, integration with the tertiary structural plane) successively record the results of performing Boolean intersection between the surrounding rock mass and the box body around the cavern, performing Boolean intersection with the secondary structural plane, and performing Boolean division with the tertiary structural plane. It can be seen from Figure 15 that this is a sequential and progressive operation process, that is: performing Boolean intersection with the secondary structural plane is based on performing Boolean intersection with the box body around the cavern, and performing Boolean cutting with the tertiary structural plane is based on performing Boolean intersection with the secondary structural plane. In this process, the original surrounding rock mass is gradually decomposed, and the decomposed surrounding rock mass clearly records the traceability information of the above progressive operation process through its name, that is, the attribute information of the surrounding rock entity.

[0102] Step 2.4: Support structure modeling. In this example design model, the anchor cables (rods) used as support structures are divided based on their cavern locations, elevations, and anchor cable (rod) types, with more than 50 array objects built. In the pre-processing program for underground cave excavation support modeling, the material properties of the anchor cable array objects are interactively set directly, and then the anchor cable array objects are disassembled to obtain the line entity representing a single anchor cable. The intersection of the line entity and the cave wall is then obtained. The anchor cable is reconstructed based on the intersection, the vector (direction) determined by the first and last nodes of the anchor cable, and the length information in the anchor cable material properties. Finally, the coordinate values of the first and last nodes of each reconstructed anchor cable are output, and its material number is output. Finally, the anchor cable activation delay is set as shown in Figure 13 (b), and the support timing information shown in Figure 13 (a) is output.

[0103] Step 2.5: Output the key modeling information in the form of data blocks through the underground cave group excavation support modeling pre-processing program.

[0104] Step 3: If Figure 16 As shown in the figure, the underground cave group model automatic mesh generation program based on Gmsh is used, with the key modeling information output in step 2 and the key modeling information output by Figure 7 The cave excavation model shown in the figure is as follows: Figure 9 The step format file exported from the 3DE model of the cave group excavation body and the 3DE model of the cave group area mountain model is used as the basic input to drive Gmsh to complete the cave group entity modeling, physical group naming of volume entity, volume entity meshing, physical group identification of the lower and upper plate of the third-level structural surface, and the output of the mesh file. The results of cave group entity modeling are shown in Figure 1. Figure 17 As shown, the volume entity mesh generation results are as follows Figure 18 shown.

[0105] Step 4: Based on steps 2 and 3, the key modeling information of the step-by-step excavation and support simulation of the Yebatan powerhouse cavern group, the cavern group model grid file, and the three-level structural surface modeling information are obtained respectively. Based on this, according to the writing rules of the FLAC3D command file, the command file for the step-by-step excavation and support of the Yebatan powerhouse cavern group can be obtained by manual compilation or automatic compilation by the program, and the integrated CAE modeling of the design and analysis of the Yebatan powerhouse cavern group is completed.

[0106] To verify the correctness of the grid cell group name, the model grid file is imported into FLAC3D. The result is as follows: Figure 19 As shown, after comparison, Figure 19 The names of the model grid unit groups shown are completely consistent with the entity numbers in the cave excavation and rock mass data blocks around the cave in the key modeling information.

[0107] This model contains three-level structural planes. To verify the correctness of the positions of the structural planes, the physical group names of the rock masses in the hanging wall and footwall of the three-level structural planes output in Step 3 and the interface elements corresponding to each three-level structural plane created in FLAC3D as shown in Figure 20 are compared with Figure 14(a), and the positions of the interface elements are correct.

[0108] To verify the correctness of the application of the anchor cables, the Cable elements representing the anchor cables created in FLAC3D using the two data blocks of "Anchor Cable (Rod) Material" and "Geometric Information, Material Properties and Support Timing of Anchor Cable (Rod)" are as shown in Figure 21 and are compared with the design results of the anchor cables as shown in Figure 8 , indicating that the positions of the Cable elements are correct.

Claims

1. An integrated CAE modeling method for the engineering design analysis of underground cavern groups, characterized in that, The method includes the following steps: Step 1: Obtain the 3DE model of the underground cavity group excavation body, the 3DE model of the mountain body in the underground cavity group area, and the 3DE model of the surrounding rock support structure of the underground cavity group. The 3DE model of the underground cavity group excavation body does not contain rock mass category and structural plane information, and the 3DE model of the mountain body in the underground cavity group area includes 3DE models of various rock masses and structural planes at all levels; Step 2: Based on 3DE, write a pre-processing program for underground cavity group excavation and support modeling. Use the 3DE model of the underground cavity group excavation body, the 3DE model of the mountain body in the underground cavity group area, and the 3DE model of the surrounding rock support structure of the underground cavity group as the input of the pre-processing program for underground cavity group excavation and support modeling. According to the layered excavation and support design plan of the caverns, drive 3DE to layer and block each cavern body. After fusing the layered and blocked cavern bodies with the surrounding mountain body, then fuse the mountain body itself, and output the key modeling information for step-by-step excavation and support simulation of the cavern group; Step 3: Based on Gmsh, write a program for automatic mesh generation of the underground cavity group model. Combine the key modeling information output in Step 2 for step-by-step excavation and support simulation of the cavern group to drive Gmsh to reproduce the entity modeling process in 3DE, perform mesh generation on the volume entity, and output the model mesh file; Step 4: Based on the excavation and support modeling information of the cavern group output in Step 2 and the model mesh file output in Step 3, form a command file for simulating the excavation and support process of the underground cavity group.

2. The integrated CAE modeling method for underground cavern group engineering design analysis according to claim 1, wherein The key modeling information for step-by-step excavation and support simulation of the cavern group includes: (1) Naming information, spatial range information, and rock type attribute information of the layered and block-excavated bodies of the cavern group and the surrounding rock masses; (2) The underground cavity group excavation bodies involved in each excavation step; (3) Geometric information, material property information, and support timing information of the surrounding rock support structure.

3. The integrated CAE modeling method for underground cavern group engineering design analysis according to claim 1 or 2, characterized in that Step 2 includes: Step 2.1: Based on the established pre-processing program for underground cavity group excavation and support modeling, drive 3DE to layer and block each cavern in the cavern group according to the layered and block plan set in the layered excavation and support design plan of the caverns. Fuse the layered and blocked cavern bodies with the mountain body for entity and attribute fusion, and obtain the layered and block-excavated bodies of the caverns that have fused rock type information and structural plane information; Step 2.2: Define the step-by-step excavation process of the cavern group based on the pre-processing program for underground cavity group excavation and support modeling, and determine at which excavation step the layering and blocking of the caverns are to be excavated; Step 2.3: Based on the established pre-processing program for underground cavity group excavation and support modeling, drive 3DE to perform entity and attribute fusion on various rock masses around the caverns with secondary and tertiary structural planes, and obtain the surrounding rock masses around the caverns that have fused rock type information and structural plane information; Step 2.4: Set the material properties and support timing of the support structure, and extract the geometric information of the support structure.

4. The integrated CAE modeling method for underground cavern group engineering design analysis according to claim 3, characterized in that, The method further includes: in step 2.3, taking the spatial range of the cavern group excavation body as a reference, expanding a set range outward in six directions of up and down, left and right, front and back of the excavation body to form a box body, taking the rock area around the caverns within the box body as the core area around the caverns, and the area outside the box body as the non-core area around the caverns. When Gmsh meshes the volume entity in step 3, different mesh sizes are set for the core area around the caverns and the non-core area around the caverns to optimize the calculation efficiency.

5. The integrated CAE modeling method for underground cavern group engineering design analysis according to claim 3, characterized in that, In step 2.4, after setting the material properties of the support structure, 3DE is driven to re-model the support structure according to the vector line determined by the intersection points of the support structure and the cavern wall, the start and end nodes of the support structure, and the support structure length information in the material properties, ensuring that the start node of the support structure is located within the surrounding rock.

6. The integrated CAE modeling method for underground cavern group engineering design analysis according to claim 3, wherein, In step 2.4, the support timing is indirectly set by specifying the anchoring activation delay parameter for each layer of the cavern excavation.

7. The integrated CAE modeling method for underground cavern group engineering design analysis according to claim 3, wherein The method further includes step 2.5: using a text file to save the key modeling information of the step-by-step excavation and support simulation of the cavern group in the form of data blocks, and driving Gmsh to reproduce the entity modeling process in 3DE.

8. The integrated CAE modeling method for underground cavern group engineering design analysis according to claim 1 or 2, characterized in that, Step 3 includes: Step 3.1: Export the 3DE model of the cavern group excavation body and the 3DE model of the mountain body in the cavern group area as step format files. Based on the mesh automatic meshing program of Gmsh, identify the caverns in the step file, and drive Gmsh to perform layered excavation modeling of the caverns according to the cavern identification results and the layered excavation design information of the caverns. The entity fusion of the layered excavation body of the caverns and the mountain body, and the entity fusion of the mountain body itself; Step 3.2: Using the physical group naming function of Gmsh, assign a physical group to each volume entity in the model, and name the physical group to which the volume entity belongs according to the naming information of the cavern group excavation body and the rock mass around the caverns in the key modeling information output in step 2. Step 3.3: Set the mesh element sizes for the model cavern group area, the core area around the caverns, and the non-core area respectively. Gmsh performs mesh division, and after successful division, outputs the model mesh file.

9. The integrated CAE modeling method for underground cavern group engineering design analysis according to claim 8, characterized in that The method further includes step 3.4: If there are tertiary structural planes in the model, identify the tertiary structural planes in the model, output the physical group name information of the rock masses above and below the tertiary structural planes, and create interface elements for simulating the structural mechanical behavior based on the physical group name information.

10. The integrated CAE modeling method for underground cavern group engineering design analysis according to claim 9, characterized in that, The specific method of step 3.4 is: Based on the API function GetEntitiesInBoundingBox of Gmsh, obtain the surface entity object in the model. Based on the API function getNodes of Gmsh, obtain the nodes on the surface entity, and getNormal to obtain the normal vector at the nodes. By judging whether the normal vectors at the nodes are the same, judge whether the surface entity is a plane. Based on the API functions getAdjacencies, getPhysicalGroupForEntity, and getPhysicalName of Gmsh, extract the volume entities on both sides of the surface entity and their physical group names.

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