Study And Application On 3D Hybrid Geological Modeling And Attribute Interpolation Of Mineral Deposit

3D geological modeling of mineral deposit is the fundamental and core function of digital mine software system. The real 3D geological environment of mineral deposit, including 3D models of stratum, faults, orebodies etc. and prediction of geological variables was established through complex geological data of mine. The 3D geological environment provides a visual and realistic open data source of mineral deposit for spatial analysis of geological variables, resource management, mine planning, mine design, mine planning and analysis of catastrophe process in mining activities.Software packages with 3D geological modeling function of deposit have been developed in countries, such as Australia, Canada, and America, which are advanced in mining industry. These software packages are used all over the word. Many colleges, institutes and large scale mine in China have bought them for application and research. However, these software packages are very expensive and also have some drawbacks. Our country started late on the software development, expect for the reason of economy and organization, the great difficulty in developing is the main reason. With the recovery of mining industry and requirement of digital mine, some homemade software packages with 3D geological modeling function of deposit begin to appear. With this opportunity, the research of this thesis was carry out under the developing of DIMINE digital mine software system. Through using the previous research results for reference, key techniques in modeling methods of surface model, discrete model and attribute interpolation were implemented. Finally, application examples utilizing these techniques showed the practicability and innovation. The main study works are as follow:1) By analyzing the existing 3D data models,3D hybrid data model consists of surface model and discrete model to describing deposit was proposed. Furthermore, the flow of establishing hybrid model was presented.2) The multi-source exploration data was abstract to borehole data, and the data storage method using table designed for borehole was proposed. The calculation method and hybrid data structure of 3D borehole model were analyzed. Then, the automatic orebody delineation algorithm for single borehole based on 3D borehole model was implemented. Approach to convert the sectional drawing to 3D coordinates was also proposed.3) Tiling method for surface reconstruction based on contour lines was expounded. Multi-resolution tiling method was proposed. In this method, tiling of lower resolution contour line is used to construct a tiling for the full resolution contour line. The branch problem of surface reconstruction was solved by utilizing transition line calculated through medial axis algorithm. Algorithm for Boolean operations on surface models based on OBB tree was presented.4) Robust creation method of block model from complex orebody model was put forward. An octree with force subdivision as the data structure of block model with subdivision blocks on the boundary. OBB collision detection algorithm was used for celebrating the intersect test and Feito-Torres algorithm was used for inclusion test between block and surface model. The theorem of Delaunay tetrahedralization was described and tetrahedral model was obtained by tetrahedralizing surface model with TetGen mesh generator.5) The method of exploratory data analysis was described and introduced to analyze the 3D geological attribute data. The strategy of directional search prism used for pair-wise search in experiment variogram calculation was discussed. Several theory variogram model were studied and interactive fitting method was presented. The nest structure variogram model of geometric anisotropic variograms was discussed. Furthermore, the calculation method for reducing anisotropy to isotropy by a linear transformation of the coordinates was presented.6) The search strategy of neighbor dada for interpolation was discussed. The octant search method was improved with minimum number of borehole as constrain condition. Index of sample data was built within a 3D grid for speeding up the neighbor data search process. The IDW and kriging method were expounded and their implemention processes were presented. Correcting of negative kriging weights and cross validation were investigated.7) An copper deposit was took as an example, the 3D borehole model, surface models of faults and deposit, block model were established accurately and thereby verified the algorithms of this thesis. Another example was numerical model for selection mining scheme of certain copper mine. Surface models of stratum and stopes were constructed and tetrahedralized to generate the numerical model for excavation of rock mass under complex geological body.