GIS-based Modeling And Visualization Analysis Of 3D Stratigraphic Structure In Nanhu Ecological Area Of Tangshan

Traditional engineering geological data can only reflect information and changes in one aspect or direction of the stratum.For example,borehole data can only reflect the changes of the vertical information of the stratum.Profile data can only reflect the changes in lateral information of the stratum.Their expressive ability of three-dimensional geological bodies is limited,and it is difficult to analyze the attribute information and spatial changes within the geological body,and it is difficult to meet the actual needs.With the development and application of visualization technology and geological information simulation technology,three-dimensional geological modeling has developed rapidly,and it can intuitively express the attribute information and spatial changes of three-dimensional geological bodies.Three-dimensional geological modeling combines the knowledge and technology of geology,geographic information science and computer science,focusing on the complexity of geological bodies,the complexity of geological information,the reliability of geological models and the high requirements of geological analysis.The geological body is the research object,and the three-dimensional stratum structure model is constructed and the three-dimensional section cutting is performed,which can meet the requirements of the visual visibility comprehensiveness of geological analysisBased on the "Beijing-Tianjin-Hebei three-dimensional stratigraphic structure modeling and visualization" as the background,the Nanhu eco-region of Tangshan City was used as the research scope and the three-dimensional stratigraphic model of the eco-region was constructed,combined with borehole data,profile data and geophysical data,etc.,using Kriging interpolation method and GIS technology.The methods and techniques of three-dimensional geological modeling were studied in this paper.The main research contents include:(1)systematically analyzing the principles,applications,advantages and disadvantages of the surface model,volume model and hybrid model of the current 3D geological modeling and exploring the modeling ideas of the surface model;(2)determining the stratigraphic deposition sequence of the Nanhu ecological region;(3)establishing a database of borehole information;(4)analyzing the applicable conditions of ordinary Kriging interpolation,exploring spatial datasets,including variation analysis,trend analysis and normal inspection;(5)exploring GIS technology for 3D stratigraphic model construction,section cutting and borehole information query.The main research results are as follows:(1)The modeling ideas for the layered geological bodies in the Nanhu eco-region were proposed,namely,"discrete borehole points—extracting stratigraphic interface datasets—dataset exploration and analysis—stratigraphic interface interpolation fitting—constrution stratigraphic entities;(2)determining the sequence of stratigraphic deposition in the Nanhu ecoregion,divided into 9 major layers and 17 sub-layers;(3)establishing a reasonable and efficient file-type geodatabase tshan.gdb for borehole information;(4)analyzing the datasets of the sub-interfaces variability,trend and normality,the data sets have relatively weak spatial correlation,anisotropy and global trend and conforms to the normal distribution,identifying and eliminating three borehole anomalies;(5)three-dimensioanl stratum model of Nanhu ecological area was established,and three-dimensional section cutting and borehole information query were realized based on intersection algorithm and recognition algorithm.In this paper,three-dimensional GIS and visualization technology were used to reflect the spatial distribution characteristics of underground geological bodies,and to improve the scientific comprehensiveness of geological bodies,so as to reduce the blind spots of geological understanding.At the same time,three-dimensional geological modeling can provide technical support for the assessment of ground motion effects near the surface,and provide guidance for urban earthquake prevention and disaster reduction.Finally,the research has certain demonstration significance and can be applied in other regions.