Research On Mixed-element Mesh Generation Methodology Based On Sealed Geological Modeling

With the development of calculation technique, numerical simulation has been an important instrument for solving geotechnical engineering problems. The 3D geological modeling technique is a powerful tool to depict geological and engineering realities; however, it is mainly used for visualization and numeralization of geological information. The sealed geological modeling has improved the geological modeling technique used for visualization and numeralization of geological information to be a tool for numerical simulation. The key of combing geological modeling with numerical simulation is that the sealed geological models can be meshed optimally and can be easily set and modified the mechanics parameters.The main purpose of this thesis is to develop a mixed-element mesh generation methodology based on the sealed geological modeling. Hence, the sharp of the blocks in the sealed geological model is analysised firstly and then five typical blocks are sumerized to be responsing templates, and the meshing techniques for the templates have been researched; a block recognizing method has been developed to recognize a block generated by the sealed geological modeling to be a simple geometry; the recognized thin blocks are meshed into tetrahedrons while a hexahedron-dominant mesh generation methodology has been proposed for other blocks: at first, a block shrinking method is researched and the template layer and the transition layer are set and defined; then a meshing technique for the template layer has been developed to mesh it into hexahedrons roughly while another one also has been developed to mesh the transition layer into pyramids and tetrahedrons; at last, a block mapping method has been proposed which can transform the simple geometry together with its meshes to its reponsing original block. Finally, the mixed-element meshes of the geological model are generated by combing all blocks'meshes togetherly.Additionally, a 3D meshing program named GeoMesher has been developed using VC++ and OpenGL, and the methods of block recognizing, shrinking, template layer and transition meshing , block mapping have been realized roughly. A block in the sealed geological model can be meshed into hexahedron-dominant meshes using the proposed methodology. To confirm the validity of the methodology, a sealed geological model of XIAO WAN hydropower engineering project is built, and several blocks of the geological model are meshed using the proposed methodology while others are meshed into tetrahedrons. Finally, the mixed-element meshes of the geological model are generated and then provided to FLAC3D.