Influence of Ground Conditions on Intrusion Flows through Apertures in Distribution Pipes
Influence of Ground Conditions on Intrusion Flows through Apertures in Distribution Pipes
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DOI：
10.1061/(asce)hy.1943-7900.0000719
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发表时间：
2013-10-01
影响因子：
2.4
通讯作者：
Boxall, Joby
中科院分区：
文献类型：
--
作者：
Collins, Richard;Boxall, Joby
本文提出了一个新的，易于处理的解析表达式来描述流体侵入埋地管道在稳态条件下。新的实验结果验证的表达。推导是基于相关的现有模型的组合，通过多孔介质的流量和通过孔的损失，与所得到的表达式有关的入侵流量施加的驱动压力。所示的表达式产生的结果直接相当于从一个完整的三维（3D）计算流体动力学（CFD）模型的入侵过程中产生的。从实验中的结果，量化体积入侵从一个现实的三维多孔介质，在这里，比较有利的计算值，验证表达式。虽然实验和分析结果显示出很高的一致性，但发现分析表达式往往会略微低估实验中看到的入侵率。数值的绝对差异很小，被认为是由于多孔介质和管道界面处的优先流动路径，而分析表达式和CFD模型不包括该优先流动路径。它是数学和实验验证的粘性和惯性阻力，在多孔介质中的流动减少入侵（或泄漏）流量超过由标准孔口方程预测，并放置额外的依赖性的流量上的入侵孔口的大小。从表达式中获得的值应被视为侵入（和泄漏）率的下限，上限由标准孔口方程提供。虽然开发的入侵风险，如与配水系统相关的量化援助，表达式也验证泄漏的有限情况下，外部多孔介质被认为是完全压实，巩固，和固定的。
This paper presents a new, tractable analytical expression to describe the intrusion of fluids into buried pipes under steady-state conditions. The expression is validated with results from novel experiments. The derivation is based on the combination of the relevant existing models of flows through porous media and the losses through an orifice, with the resulting expression relating the intrusion flow rate to an applied driving pressure. The expression is shown to yield results directly equivalent to those generated from a full three-dimensional (3D) computational fluid dynamics (CFD) model of the intrusion process. Results from the experiments, quantifying volumetric intrusion from a realistic 3D porous media, presented here, compare favorably with calculated values, validating the expression. Although the experimental and analytical results show a high level of agreement, it was found that the analytical expression tends to slightly underestimate the intrusion rate seen experimentally. The absolute difference in the values is low and is thought to be attributed to preferential flow path at the porous media and pipe interface that the analytical expression and CFD model do not include. It is shown mathematically and verified experimentally that the viscous and inertial resistance to flow in the porous media reduces the intrusion (or leakage) flow over that predicted by the standard orifice equation and places additional dependencies of the flow on the size of the intrusion orifice. The values obtained from the expression should be considered as a lower bound to intrusion (and leakage) rates, with upper bounds being provided by the standard orifice equation. Although developed to aid in the quantification of intrusion risk, such as that associated with water distribution systems, the expression is also validated for leakage for the limited case that the external porous media is considered to be fully compacted, consolidated, and immobile.