| Geo-hazard is an important factor of infrastructure security risks and is prevalent in china, especially in southwest china where Karst and complicated geo-environment is ubiquitous. In this paper, the study area is New International Airport of××Kunming, and the result of field geological hazard comprehensive evaluation is achieved through the establishment of a series of related mathematical models. At the same time, GIS as an effective spatial analysis and visualization tools, have had many successful applications in geological hazard analysis and assessing field, but the main target is limited to qualitative or quantitative research based on the analysis of basic data, which is mainly focusing on basic geological data collation and quantitative data model research, but is insufficient in true results-based three-dimensional visualization and comprehensive analysis. Therefore, the combination of three-dimensional GIS technology and geological environment safety assessment led to a new technology: geological environment three-dimensional visualization modeling technology. Geological data is a collection of multi-dimensional and vast amount data sets, including geography, physical, chemical and remote sensing data, but traditional GIS software could only handle 2D, 2.5D data which could not meet the actual needs. After careful analysis, summarize and sum up the three-dimensional geological environment common models and surface TIN model, the three-dimensional geological environment stability assessment method is proposed based on surface-quasi tri-prism mixture model (DTM-QTP), and a software system was programmed combining data management, model editing, analysis and display. In addition to traditional GIS software with mapping functions, our software also fused of various data information in a real three-dimensional visualization platform for the realization of highly integrated geological hazard assessment. As a result, environmental assessment experts can be more intuitive understanding of the overall geological hazard development pattern and unified structures of surface phenomenon and subsurface tectonic in the study area. The major research works are shown as follows:(1) Considering the major Karst collapse factors that would affect the study area, and establishing Karst collapse prediction mathematic models of airport construction site. Establish the three major factors of risk assessment math models, including groundwater effective level dynamic factor, Karst cave overlay stability factor and airport land use of overburden pressure potential risk factor, and calculate their own quantitative indicator values as APi, AHi, AGi, then build change weight matrix and calculate dynamic weighting to acquire Karst collapse comprehensive evaluation risk value of ASi. Use GIS spatial analysis method such as center attribution method and overlay analysis method to process the original data, and acquire 2479 evaluation units of study area.(2) Existence testimony of Delaunay triangular netword "window" feature and it's application. According to surface structure of quasi tri-prism model, the "window" feature of Delaunay triangular network is proposed, and a precise definition and scrutiny of "window" feature is executed, which was also applied to fast Delaunay triangulation and dynamic update and terrain features auto-fitted high-precision interpolation.(3)Study of three-dimensional data model. Based on previous three-dimensional GIS data models, a brand new model of Surface-Quasi Tri-Prism mixed (DTM-QTP) model was proposed, which can be successfully applied to three-dimensional geological hazard evaluation. In this paper, geometric features and data structures of the model is carefully analyzed. DTM-QTP mixed model is the combination of DTM model and QTP model, which can construct the surface topography and geological volume element separately.(4)Interpretation of complex geological phenomena. According to stratigraphic feature of study area, this paper analyses the surface phenomena, geological phenomena and hierarchy of strata structure, then establish an universal data format and stratigraphic division method to suit quasi tri- prism modeling.(5) Dummy borehole chain and cross-boundary problem. In order to solve border control problem of underground hidden complex geological structure and trend problem of surface linear structure, the"dummy borehole chain"control method was proposed in this paper. In the mean time, the causes of Delaunay triangle network structure's"cross-boundary problem"was analyzed while do not use"dummy borehole chain", and corresponding solutions are given.(6) Study of a series of algorithms based on borehole data. According to stratigraphic division method and quasi tri- prism body construction method designed in this paper, a series of algorithms were proposed, including"borehole interpolation algorithm","quasi tri-prism construction algorithm"and quasi tri-prism split algorithm .etc, meanwhile, three efficient algorithm acceleration programs were also presented.(7) Designing of three-dimensional visualization system. A computer system of real 3D visualization geological hazard assessment model was designed and realized based on object-oriented computer technology and OpenInventor visualization technology. Which was consisted of database management, evaluation model editing and calculation and three-dimensional visualization modeling and analysis, some relevant functions were also implemented.(8) Engineering application. Applying real three-dimensional geological modeling and visualization technique to research program of comprehensive evaluation model of Karst collapse in New International Airport of××Kunming demonstrated that the system is valid and practicably, which also provided a new way of visual analysis for geological hazard assessment model.
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