雨水管渠设计参数折减系数m的理论研究

Theory of Attenuation Coefficient m in Urban Storm Sewer System Design

针对中国室外排水设计规范沿用原苏联采用了折减系数m修正汇水时间设计雨水管渠的方法,详细分析了采用m后,不同的城市暴雨强度公式地方参数b和n、地面汇水时间t1、管内汇水时间t2对计算设计流量Qm/Q0的影响.研究发现Qm/Q0是b的增函数,是n的减函数,是t1的增函数,是t2的减函数.由于采用了m严重影响到城市暴雨强度公式的适用范围,根据不同的t1,t2的适用范围缩小到57.5～52.5 min.根据北京市城市暴雨强度公式分析发现,采用m后可以使设计流量缩小40%～50%.

The code for design of outdoor wastewater engineering in China follows the storm sewer system design method of the former Soviet Union, using attenuation coefficient m for amending the catchment concentration time. In view of the method, the paper analyzes that different urban storm intensity formula parameters b, n and surface catchment concentration time t1, flow time t2 in pipes have impact on the design flow Qm/Q0 after using the attenuation coefficient m. The research finds out that Qm/Q0 is an increasing function of b and t1, and a decreasing function of n and t2. The suitable scope of urban storm intensity formula has been severely affected as a result of using the attenuation coefficient m. Depending on the different surface catchment concentration times, the suitable scope of design flow time t2 in pipes has reduced to 57.5 - 52.5 min. According to the urban storm intensity formula of Beijing, after using attenuation coefficient m, the design flow has reduced 40% -50%.