在地质体建模中，曲面间的拓扑结构分析是一个非常重要的步骤。为了得到块体结构的模型，需要对层面模型内所有的曲面进行全局性的拓扑分析。当层面模型的数据规模极其庞大的时候，这种全局性的分析势必要受到内存容量的限制。为了提高运算速度，提出了一种基于简化面片的闭合块体构造算法，该算法可将模型内所有的曲面数据尽可能地简化，仅仅保留交线附近的关键数据。这种简化后的层面模型既包含了全局的拓扑信息，又可以完全载入内存。实验结果表明，该算法不仅具有较快的拓扑分析速度，并能适用于大规模的地质体模型的构建。

Topology analysis of spatial data model is a very important step in geological modeling.To construct coherent geological blocks，we should analyze the topology of all elements in the surface model.When the scale of surface model is very large，this global analysis must be limited by memory capacity.In order to improve the speed of computation，this paper presents an algorithm of constructing geological blocks which is based on the simplified surface pieces.This algorithm simplifies the data of surface model as much as possible and only preserves crucial data which have relation with the intersection lines.Such simplified surface model has global topology information and can be read wholly into memory.Experimental results show that，this algorithm can effectively speed up the process of topology analysis，and can be applied to geological model with large-scale data.