Research On Geological Body Modeling Method Based On Tetrahedral Grid

The geological features in nature exhibit apparent complexity and uncertainty in spatial terms.Traditional two-dimensional geological maps are insufficient in fully displaying the underground morphological characteristics of geological objects.In contrast,three-dimensional geological models enable rapid visualization of the spatial relationships and geometric forms of rock formations,thereby enhancing the decision-making process and quality for engineering and resource development.Three-dimensional modeling of geological structures has gradually become a major research focus in the field of geology.However,the precise construction of high-quality three-dimensional geological models,using existing geological data,that can directly guide practical production remains a challenging research topic in the field of geological engineering.Accurately simulating the physical morphology of complex underground geological blocks,this paper takes into full consideration the complexity of boundaries of underground spatial objects.Based on borehole data,a closed surface model of stratigraphic blocks is constructed using triangular mesh constraints.Constrained Delaunay triangulation is then applied to generate a three-dimensional geological body model with excellent visual effects,where tetrahedrons serve as the basic elements.The specific research contents of this paper are as follows:(1)To efficiently construct a continuous layered and seamless geological body model,this study utilizes the incremental insertion Delaunay triangulation algorithm to build spatial surfaces of geological layers.By combining the triangular mesh fitting of boundary contour lines on the sides and multiple layer combinations,a spatially closed geological body model is created.This method enables the rapid generation of a well-constrained triangular mesh model of continuous layered geological bodies with favorable topological relationships.Subsequently,the model can be partitioned to generate a tetrahedral grid geological body model.(2)In response to the discontinuity phenomenon observed in non-continuous layered geological bodies,this paper proposes a modeling method based on drilling data and the establishment of a Voronoi diagram for determining the distribution range of attribute layers in a planar point set.Subsequently,a closed stratigraphic model is constructed using a triangular mesh,followed by layer-by-layer partitioning to build the geological body model.This method effectively simulates the occurrence of pinching out and lensing phenomena within the geological body,with good visual effects in model construction.Due to the geometric continuity and topological compatibility at the boundaries between different layers in the model,it can be subjected to tetrahedral meshing,enabling three-dimensional solid representation of noncontinuous layered geological bodies.(3)Considering the poor tetrahedral shape quality within layered geological body models,this paper proposes a method to optimize and reconstruct the tetrahedral geological body models using constraints such as the radius-to-edge ratio and minimum dihedral angle.The reconstructed models are then subjected to quality analysis,and the VTK library is employed for three-dimensional model visualization.By constraining the parameters of the feature constraints,sharp features in specific regions of the geological body model can be preserved,while improving the tetrahedral quality within the model.As a result,three-dimensional geological body models with higher tetrahedral quality are generated.