An Approach To Build A 3D Sealed Engineering Geological Model Suitable For Numerical Simulation

With the development of calculation technique, numerical simulation has been an indispensable instrument for solving geotechnical engineering problems. In the fields of hydropower engineering, mineral engineering, traffic engineering, etc., using numerical simulation, researchers analyze the problems which have large scale, complicated geological conditions, various engineering structures and fussy construction processes, to provide important help to the planning, design and construction. However, at present, it is still a prevalent weakness in numerical simulation technique that the qualitative effect is good but the quantitative degree is low. The calculation results are affected by many reasons; one of them as an important causation is the calculation model can hardly reflect the complicated geological and artificial objects.The 3D geological modeling technique is a powerful tool to depict geological and engineering realities. Combining it with numerical simulation can effectively improve the reliability of calculating results and the efficiency of modeling. But it cannot be used for numerical simulation directly because there are great differences in modeling purpose, modeling method, data type, etc. Therefore, a sealed engineering geological modeling (SEGM) suitable for numerical simulation is developed, realizing the tight combination between geological modeling and numerical simulation.The notion of an SEGM, and its topological representation, the data model, and the conditions of geometrical continuity, topological consistency and geometrical and geological consistency are presented systematically in this paper. On the foundation of this, an approach based on Wire Frame to build an SEGM is proposed. The key technologies involved in the approach include simulating initial geological and engineering interfaces, constructing the wire frame, editing and reconstructing the interfaces, searching blocks, classifying the 3D rock mass quality, modeling engineering structures, etc. To improve the surface mesh quality and ensure an SEGM can be meshed into calculating elements with high quality, an optimization triangulation method for the 3D interpolating surface, the methods for solving singular elements and sharp-angled problems, and a mesh harmony method are presented here.A geological model constructed by the approach can be triangulated into tetrahedral meshes with geometrical continuity and topological consistency, which can be provided to numerical simulation softwares such as finite element, finite difference. To confirm the validity of the approach, an SEGM of XIAO WAN hydropower engineering project is built, triangulated into tetrahedrons, and then provided to FLAC^3D. The presented modeling method can be widely applied to numerical simulation in geotechnical engineering, realizing the conversion that the geological modeling, a visualization and digitization tool for geological information, becomes a numerical simulation modeling tool.