三维实体模型在公路设计中的应用研究

Application of 3D solid model in highway design

采用 CAD软件系统建立公路三维模型可方便、快速地检验和评价公路设计方案。目前常用的公路三维建模方法是面模型方法 ,存在着交接拼合计算困难、不可剖切和切割等不足。为此提出了公路三维实体建模方法 ,该方法是在逐桩进行横断面“戴帽子”设计之前 ,由数字地面模型 (DTM)建立地形实体 ,由路线平面、纵断面及路基标准横断面建立公路填方实体和挖方实体 ,填挖过程可由实体间的布尔运算 (并、交、差运算 )来实现 ,即地形实体与挖方实体进行“差”运算 ,再与填方实体进行“并”运算 ,所得结果是公路及其周围地形共同组成的组合实体 ,同时得到填、挖方体积 ,并可剖切得到任一桩号处横断面 ,为公路平、纵、横设计提供了三维可视化分析工具。该实体建模方法原理简明 ,在

Highway's 3D model can be built by CAD system to examine and evaluate conveniently and quickly a highway design project. The current highway's 3D modeling method is a surface modeling method, which has some shortcomings, such as computational difficulty in merging among surface models, no sectioning and slicing, etc. So the highway's 3D solid modeling method is presented as an improvement. Before detailed cross sections are designed stake by stake, the terrain solid is built from DTM; the highway's fill solid and cut solid are built from horizontal alignment, vertical alignment and standard cross section definition; then the fill and cut design procedures can be realized by Boolean operations (union, intersection and subtraction) among solids, i.e. subtracting the cut solid from the terrain solid, and then uniting with the fill solid, with resulting composite solid consisting of highway and terrain. The 3D composite solid, from which fill and cut earth volumes and cross sections at stakes can be obtained, provides 3D visualization analysis tools for highway design. The solid modeling method can be conveniently developed and realized in CAD system.