基于GIS-GOCAD耦合技术的三维地质建模

3-Dimensional Geological Modeling Based on Coupled GIS-GOCAD

常规GIS技术建立的伪三维模型不能满足复杂地质体三维建模的需要,也不能用于三维数值模拟计算。GOCAD采用离散平滑内插方法(DSI)计算三维图形中线段或三角形的节点位置,降低了线或面的粗糙程度,实现了真三维模型的构建。为了充分发挥GIS空间数据处理能力和GOCAD真三维建模能力,研究基于GIS-GOCAD耦合技术的三维地质建模,实现了从GIS的2D数据结构到GOCAD的3D数据结构的自由转换,提升了GOCAD的三维地质建模能力。选取成兰铁路(成都—兰州)龙门山段作为示范研究区,建立其三维地质模型,直观、立体地展示了研究区地质体结构的宏观基本形态,并为进一步的三维数值模拟奠定了几何模型基础。

The pseudo 3D models constructed by ordinary GIS technology cannot meet the special need of the 3D modeling of complex geological structures, and＇ be used for the further 3D numerical simulation. However, the GOCAD, a powerful 3D geological modeling software, can construct true 3D geological models,which adopts DSI method （Discrete Smooth Interpolation） to calculate the node positions of 3D segments and triangles. To take full advantage of the capabilities of GIS spatial database and GOCAD 3D geological modeling, the 3D geological modeling process based on coupled GIS-COCAD was established according to the principle of 3D geological modeling and the different characters of the data structure between GIS and CA）CAD. The process can achieve the free conversion of data structure from 2D-GIS （F = f（x, y） ） to 3D-GOCAD （F = f（x, y, z））. Here, the z val- ue （the altitude of geological body） comes from topographic data （DEM）. The coupled GIS-GOCAD technology considerably enhances the capabilities of GOCAD 3D geological modeling. The Longmenshan section of Cheng-Lan Railway （from Chengdu to Lanzhou, in China） was selected as study area to demonstrate the 3D geological modeling proeess. The constructed 3D geolog- ical model visually and solidly shows the macroscopical geological overview of study area, and provides the preliminary geometric model for further 3D numerical simulation （e. g. FLAC3D, 3DEC）.