雨水管渠设计参数折减系数m的理论研究

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%.

Theory of Attenuation Coefficient m in Urban Storm Sewer System Design

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 57.5-52.5min.According to the urban storm intensity formula of Beijing,after using attenuation coefficient m,the design flow has reduced 40%-50%.