【摘要】：當給水管網(wǎng)內(nèi)發(fā)生負壓時,埋地管道周圍環(huán)境中含有污染物的地下水會通過管道上的破損口侵入管網(wǎng)內(nèi)部,對飲用水造成污染。侵入管網(wǎng)的地下水的體積流量的估算對用戶暴露風險的評估具有重要作用。目前在計算入侵流量時常用的孔口公式未能考慮管道周圍土體的影響。本文針對負壓驅(qū)動下侵入埋地管道破損口的地下水的流量估算問題,進行了實驗研究與理論分析,重點考慮破損口周圍土體對入侵流量的影響。 第三章通過實驗研究管道周圍的多孔介質(zhì)對孔口入侵流量的影響。由于含有污染物的地下水與普通的水具有相同的流動特性,所以本文實驗均采用普通水進行。實驗采用2種孔徑,3種多孔介質(zhì),分別研究了小孔所處表面形式(平面／曲面)、小孔周圍的多孔介質(zhì)以及大雷諾數(shù)對入侵流量的影響。第四章考慮流速、孔徑和多孔介質(zhì)滲透性等多種因素的影響,實驗研究了孔口水頭損失和多孔介質(zhì)水頭損失。在第五章中,將多孔介質(zhì)中的三維滲流與孔口入流相結合推導了污染物入侵流量改進模型。模型考慮管道物理邊界的影響對透水區(qū)域進行修正,改進了已有模型中幾何修正系數(shù)的取值方法,本模型中多孔介質(zhì)水頭損失部分的流量線性項系數(shù)降低了40%-60%,流量二次項系數(shù)降低了70%-80%。第六章進行了三維滲流條件下的圓孔入侵實驗,驗證入侵流量改進模型的準確性。 通過對實驗結果進行分析,可得主要結論如下：(1)小孔周圍的多孔介質(zhì)可以使小孔流量系數(shù)發(fā)生改變,且使入侵流量與孔徑、多孔介質(zhì)滲透性及流動雷諾數(shù)有關；(2)孔口流量系數(shù)根據(jù)雷諾數(shù)的不同呈現(xiàn)出分區(qū)的變化特點；(3)孔口流動雷諾數(shù)較大時,流量系數(shù)可能存在突變的現(xiàn)象,這是流線從孔壁的分離導致的；(4)入侵流量與管道內(nèi)外的壓力差、破損口的大小、土體的滲透性以及管道直徑有關；(5)三維滲流實驗結果證明本模型具有較高的準確性。 本次研究主要針對穩(wěn)定流動條件下的單個圓孔形破損口進行研究,并且沒有考慮管道周圍土顆粒的運動。后續(xù)研究可圍繞管內(nèi)壓力瞬變的情況,管道的多種破損形式,管網(wǎng)中分布的多個破損口,破損口周圍土顆粒的移動等問題展開。
[Abstract]:When the negative pressure occurs in the water supply network, the groundwater containing pollutants in the surrounding environment of the buried pipeline will invade the pipe network through the damaged opening of the pipeline, which will cause pollution to the drinking water. The estimation of groundwater volume flow is very important to the assessment of user exposure risk. At present, the commonly used method for calculating the invasion flow is the influence of soil around the pipeline. In this paper, an experimental study and theoretical analysis are carried out on the estimation of the underground water flow in the damaged outlet of a buried pipeline driven by negative pressure, with emphasis on the influence of the soil around the damaged opening on the intrusive discharge. In the third chapter, the influence of porous media around the pipeline on the flow rate of orifice intrusion is studied experimentally. Since the groundwater containing pollutants has the same flow characteristics as ordinary water, the experiments are carried out with ordinary water. In this paper, two kinds of pore size and three kinds of porous media were used to study the influence of the surface form (plane / surface) of the pore, the porous media around the pore and the large Reynolds number on the intrusion flow rate. In chapter 4, considering the influence of flow rate, pore diameter and permeability of porous media, the loss of orifice head and porous media head are studied experimentally. In the fifth chapter, the improved model of pollutant intrusion flow is derived by combining three-dimensional seepage and orifice flow in porous media. Considering the influence of the physical boundary of pipeline, the model modifies the permeable region, and improves the method of calculating the geometric correction coefficient in the existing model. In this model, the linear coefficient of flow in the head loss of porous media is reduced by 40 to 60, and the coefficient of the second term of flow is reduced by 70 to 80. In chapter 6, the experiment of circular hole intrusion under three-dimensional seepage condition is carried out to verify the accuracy of the improved intrusion flow model. Through the analysis of the experimental results, the following conclusions can be drawn: (1) the porous media around the pores can change the flow coefficient of the pores, and the intrusion flow rate is related to the pore diameter, the permeability of porous media and the flow Reynolds number; (2) the flow coefficient of the orifice presents the characteristic of zone change according to the Reynolds number, (3) when the Reynolds number of the orifice is larger, the flow coefficient may have a sudden change, which is caused by the separation of the flow line from the hole wall; (4) the intrusion flow rate is related to the pressure difference inside and outside the pipeline, the size of the damaged opening, the permeability of the soil and the diameter of the pipeline. (5) the experimental results of three-dimensional seepage show that the model has high accuracy. In this study, a single circular hole is studied under steady flow conditions, and the movement of soil particles around the pipe is not considered. Further studies can be carried out around the transient pressure in the pipe, the various damaged forms of the pipeline, the distribution of multiple damaged openings in the pipe network, and the movement of soil particles around the damaged opening.
【學位授予單位】：浙江大學
【學位級別】：博士
【學位授予年份】：2015
【分類號】：TU991.33

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