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

污水管网的设计仍有许多问题有待解决。其中最重要的一个问题是在计算网络总能量损失时忽略了结点处的能量损失。本研究的目的是获得附加流作用下圆形结水头损失系数，提出从重力流到附加流或重力流两种流型下圆形结水头损失的计算方法，并利用实验结果、新的计数方法和准稳态动力波动方程，建立一种新的非定常流数值模拟方法。实验结果表明，圆形结处的总能量损失不受上下游管道水位差的影响。直通式管道中有附加物流动时，水头损失系数K从0.2变化到3.4。当弯矩为90°/ h时，管道内的附加流量为1.4 ~ 2.9。本文提出了一种新的非定常流场数值模拟方法。特别是对网络的编号方法进行了改进。利用这种编号方法，便于建立管网模型。城市非定常流场的数值计算结果表明，该方法能较好地表达实际的洪水状态，并结合结点水头损失的实验结果。

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.