给水管网负压引起污染物入侵的流量计算方法

Calculation method of contaminant intrusion flow rate induced by negative pressure events in water distribution system

针对污染物入侵流量计算时常用的孔口公式未能考虑管道周围土体的问题,将多孔介质中的一维渗流与孔口出流相结合,推导了稳定流条件下圆孔破损的污染物入侵流量估算方法.通过模型试验验证了该计算方法的准确性,计算结果与试验结果吻合较好.试验结果表明,多孔介质的存在会改变孔口入侵流量,入侵流量与孔口大小及多孔介质的渗透特性有关,估算入侵流量时应当考虑管道周围土体的影响.

The orifice equation is typically used for calculating intrusion inflow volumes,which does not consider the properties of the porous media surrounding the pipe.An analytical relationship was derived by combining the one-dimensional seepage and the flow through an orifice for predicting the intrusion flow rate for a circular orifice under steady-state conditions.An experiment study was conducted to validate the accuracy of the analytical expression,and the analytical results fitted well with experimental results.Experimental results indicate that the presence of porous media could change the intrusion flow rate and add dependencies on the orifice size and permeability of porous media.The impact of the soil surrounding pipelines should be considered for calculation of intrusion flow rate.