关于三维有限元网格自动生成若干问题的研究

网格自动生成是自适应有限元重要组成部分，其中如何有效地对三维物体轮廓面进行参数化表示一直是一个难点。本文结合岩土工程的实际情况，利用混合样条插值曲面对地形面、大规模断层面等不规则曲面进行了拟合，成功地解决了这个问题。另外本文还讨论了利用双叉树型结构进行几何搜索的算法，该算法能提高行波法生成四面体的效率。最后本文用一边坡洞室开挖的算例验证了编制程序的有效性。

The research on some problems of automatic 3D mesh generation

Advanced Front Technique(AFT) is widely used in Automatic mesh generation which is the important ingredient of adaptive finite element method. How to model the irregular surface is one of the unsolved problems in AFT, to overcome the problem, the spline-blended surface interpolation is adopted. It is found the method is suitable for the representation of the large scale surface which usually has no adequate geometric information, such as ground surface, the fault surface which are very common in geotechnical engineering. In the second part of the paper the Alternative Digital Tree(ADT) is used in geometric searching of AFT procesure, which can reduce the computation time in large magnitude. In the end of the paper, a tunnel excavated under a rock slope is modeled by tetrahedral elements, the example demonstrate the validity of above methods.