Research On Key Techniques For 3D Modeling Of Salt Cavern

Salt cavern is a kind of artificial underground cave formed by the method of solution mining in underground thicker salt stratum or salt dome, it is an important way of reserving strategic materials, mainly used for keeping the substances that not dissolved in salt safely. Salt cavern is the three-dimensional space of non-homogeneous and NLOS (Non Line of Sight), with different sizes and shapes according to different geological conditions. In China, the research on salt cavern is still in the primary stage at present, it is significant to construct salt cavern three-dimension model for it’s development and utilization.Salt cavern measurement is the base of salt cavern three-dimension modeling, for obtaining more accurate data of salt cavern shape, surface area and volume is one of the major problems which needs to be solved in the salt cavern measurement. Volume and surface area of a salt cavern are important parameters in stability analysis, traditional calculation method of the salt cavern volume and surface area is on the basis of the two-dimensional graphic, with approximate calculation and poor accuracy. The method of overcoming the shortage is to build a three-dimension model of a salt cavity, however, at home and abroad now there isn’t mature three-dimension modeling tools and methods of salt cavern.This thesis takes measurement data of salt cavern as the studying object, from the point of view of geological three-dimension modeling, to study the modeling method of a salt cavern three-dimension surface model and volume model by the analysis of the salt cavern measurement method and the characteristics of the measured data, tries to establish a set of relatively complete salt cave three-dimension modeling theory and method system.In the process of data preprocessing, the validation, correction and interpolation of measurement data are studied, in order to avoid the data distortion in the process of interpolation, introduces an interpolation method of a shape preserving Hermite for interpolating of horizontal section lines and vertical section lines.Through the analysis of section lines spatial relationship, summarized the characteristics of salt cavern section lines. Several typical reconstruction algorithms of section lines surface model are studied. About the modeling problem of external vertical section lines, the space nearest point modeling algorithm of surface model is put forward, and is further improved, that is the modified space nearest point modeling algorithm. On the basis of these algorithms, introduces the modeling algorithm of bilateral weighted distance angle of surface mode by making use of evaluation function. In order to solve the modeling problem of the rocky body which extended into the internal salt cavern, puts forward the classification algorithm and extension method of inner vertical section lines. Traditional ray method is improved through the two fast exclusion methods during voxelization of surface model.Because of the complex salt cave shape, there are some complex branches and correspondence problem while constructing the surface modeling by its horizontal sections. In order to solve this modeling difficulty, takes the thought of contour deformation method as lesson, through the way of constructing attribute field, introduces the variational methods of implicit function to make the data interpolation directly for horizontal section data. Then regulates voxel model to generate volume model, realizes the transformation from volume data model to the surface model by rendering technology of isosurface.According to the algorithm proposed in this thesis, the experimental system of three-dimension modeling on measurement data of salt cavern is designed and implemented. The experimental system carries out the actual measurement data of a salt cavern and generates surface model and volume model, applies for the three-dimension model to calculate the area and volume, and compares the results with actual measurement data analysis results of salt cavern, the validity of this method is verified.