作者想推导简短的公式，对梯形、矩形和圆形断面采用通用的程序，以得到准确的结果。
The authors want to deduce a brief formulation, and use all-purpose program to get exact result for echelon, rectangle and rotundity cross section.
有压隧洞多采用圆形断面。
圆形断面管道在工程中的应用十分广泛。
The pipelines with circular section are used widely in the practical engineering.
应用推荐