承压雨水管水力计算研究

Study on Hydraulic Calculation of Confined Storm Drainage Pipe

传统雨水管道设计假定雨水管道流态为满管重力流,采用推理公式法和曼宁公式进行水力计算。当排放口处尾水水位高于管顶标高时,雨水管道处于承压状态,传统水力计算方法已不适用。针对传统水力计算方法的缺陷,采用美国联邦公路管理局的估算法进行雨水管道的初步设计。将美国联邦公路管理局的水面线计算方法应用到一个工程案例中,计算结果表明以水面线作为雨水管道设计依据是可行的。在案例分析过程中,发现检查井的局部水头损失较大,设计中不能忽视,并且雨水口淹没出流能充分利用水头差,减轻管道淤积。

In the process of traditional storm drainage pipe design, the pipe is assumed as full and the flow regime as gravity, and the rational method and Manning formula are used for hydraulic calculation. This traditional hydraulic calculation method is unavailable when the tail water of outfall is higher than the pipe crown because the storm drain is under pressure. The Federal Highway Administration＇ s estimation method is used in the preliminary design of storm drainage pipe due to the defects of traditional hydraulic calculation method. The storm drainage pipe was calculated in a project case using the hydraulic grade line calculation method of the Federal Highway Administration. The calculation results showed that it was feasible to use the hydraulic grade line as the design basis of storm drain design. In the process of case analysis, it had been found that the local loss of manhole was so significant that it could not be ignored in the design, and submerged outfall could make full use of the head difference to reduce deposition in the storm drainage pipe.