Capacity of urban drainage system its stochastic interpretation on safety factor.

污水管网的设计还有许多问题没有解决。其中最重要的一个是在计算网络中的总能量损失时忽略节点处的能量损失。本研究的目的是获得超载水流作用下圆形枢纽的水头损失系数，提出从重力流到超载流或重力流的水流流态下圆形枢纽水头损失的计算方法，并利用试验结果发展一种新的非恒定流数值模拟方法，提出一种新的编号方法，实验结果表明，上下游管道的高差对圆形连接处的总能量损失影响很大。在直通管中有超载流的情况下，水头损失系数K在0.2到3.4之间变化。在90 °弯管中有超载流动时，其数值变化范围为1.4 ~ 2.9。特别是对网络的编号方法进行了改进。通过这种编号方法，很容易建立一个污水管网模型。对某城区非恒定流条件下的数值计算结果表明，采用新的编号方法和交叉口水头损失的试验结果能够较好地反映实际的洪水状态。

Many problems remain unsolved for designing a sewer network. One of the most important ones is neglect of energy losses at junctions on calculating total energy losses in the network. The objectives of this study are to obtain the coefficient of head loss in circular junctions under surcharge flow, to propose a calculation method of the head loss in circular junctions under a flow pattern from gravity flow to surcharge flow or gravity flow, and to develop a new method of numerical simulation for unsteady flow by use of experimental results, a new numbering method, and quasi-steady state dynamic wave equations.The experimental results indicated that the total energy loss at a circular junction is fairy influenced by the difference in level between the upstream and downstream pipes. In case of surcharge flow in a straight-through pipe, the head loss coefficient, K changes from 0.2 to 3.4. In case of surcharge flow in a 90ﾟ -bending pipe, it changes from 1.4 to 2.9.In this study, a new numerical simulation method under unsteady flow was presented. Especially the numbering method of a network was improved. By this numbering method, it is easy to construct a model of a sewer network. The results of numerical under unsteady flow in an urban area indicated that it can successfully express actual flooding states by use of the new numbering method and experimental results on head loss at junctions.