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鉴于我国室外排水设计规范对雨水管道的设计只计沿程水头损失而忽略局部水头损失,而美国等国家的城市雨水系统设计方法会考虑两部分损失,以一长2 200 m、汇水面积为0.96km2的排水干管为例,在三年一遇的设计暴雨强度下,对比分析了不计和计入管道局部水头损失两种情况下的管道测压管水头线和总水头线。结果表明,排水管道中8处三通、转弯的局部水头损失之和达1.38 m,占总水头损失的23.88%,可见忽略局部水头损失将明显高估管道的排水能力。
In view of China’s outdoor drainage design code for rainwater pipeline design only ignore head loss along the way while ignoring the local head loss, and the United States and other countries in the design of urban stormwater system will consider two parts of a loss of a length of 200m, catchment area of 0.96km2 drainage mains as an example. Under the three-year design storm intensity, the pipe headline and the total headline of pipelines are compared and analyzed in two cases without considering the partial head loss. The results show that the sum of local head losses of 8 tees and turns in the drainage pipe reaches 1.38 m, accounting for 23.88% of the total head loss. Therefore, neglecting the local head loss will obviously overestimate the drainage capacity of the pipe.