Abstract:Visualization of the three- dimensional geological model for the underground geological conditions is of great significance to the transformation and upgrading of the traditional geology and mineral industry, urban planning and construction. For constructing a 3D model under complex geological conditions, a 3D geological modeling method based on multi- source data and geological prior knowledge constraints is used in this paper.Methods:Taking Chengdu as an example, we applied a 3D geological modeling module of the MapGIS10.0 to build the 3D geological model through integrating all the complex geological information concerning the DEM data, digital geological map, comprehensive geological profile, borehole data, geophysical interpretation data, structural outline map, as well as geological prior knowledge such as geological body distribution form, attitude and thickness change, fault characteristic, extension direction, attitude change, staggered cutting of geological body, fold type, morphological characteristics, attitude change of two wings etc. This paper explicates the detailed model building process including the preparation of 3D modeling data source of complex geological body, modeling process and method, model construction and reliability analysis.Results: We proposed that the block modeling technology can effectively reduce the difficulties of building a three- dimensional model of a complex geological body, improve the modeling efficiency, and realize the traceless splicing of the model, while it would be easier to modify and improve the model at a later stage. Based on the constraints of multi- source data and geological prior knowledge, the block modeling technology is first used to construct the three- dimensional geological model of Chengdu.Conclusions: We examined the dependability of the model through geological prior knowledge (geological rule) and static data (visualization and real sparse drilling data which does not participate in the modeling) to calculate the error of the buried depth and layered thickness of the geological body in the three- dimensional geological model. Finally, it shows that the average error of the buried depth of the geological body is 33.15 m and the average error of the layered thickness is 21.37 m, which suggests that the model has high reliability and can provide important basic geological data support for Chengdu urban planning and major project site selection.