本文選題：層狀包氣帶土 + 氟運移�。� 參考：《成都理工大學》2015年碩士論文

【摘要】：包氣帶是土顆粒、空氣、水三者同時存在的一個復雜系統(tǒng),作為連接地表水、大氣水和地下水的一個重要紐帶,在水循環(huán)中起著重要作用。包氣帶土也是地表溶質(zhì)進入地下水的必經(jīng)通道,溶質(zhì)在遷移的過程中與土體發(fā)生一系列物理、化學、生物等作用,使包氣帶對溶質(zhì)運移有一定阻滯作用。在自然界中層狀土分布廣泛,研究表明層狀土中的溶質(zhì)運移比均質(zhì)土復雜得多,氟作為地下水中典型的污染物,對人類健康有重要影響,因此研究層狀結(jié)構(gòu)包氣帶土中氟運移規(guī)律有重要意義。本文以地質(zhì)災害防治與地質(zhì)環(huán)境保護國家重點試驗室團隊重點課題:非飽和溶質(zhì)遷移轉(zhuǎn)化規(guī)律試驗研究(項目編號:SKLGP2011Z001)為依托,在總結(jié)前人研究包氣帶土溶質(zhì)運移的基礎上,對影響層狀土中溶質(zhì)運移的因素進行分析,通過室內(nèi)土柱試驗對不同分層方式、水分供給方式和溶質(zhì)供給方式下層狀包氣帶土中水分和氟的運移規(guī)律進行研究。為彌補室內(nèi)試驗在時間上的局限性,結(jié)合Hydrus-1D軟件對多種不同分層方式、不同水頭高度和不同溶質(zhì)供給條件下氟在層狀包氣帶土中運移規(guī)律進行數(shù)值模擬,主要研究成果如下:(1)層狀土中濕潤鋒運移分為兩個階段:第一個階段,在分層界面以上入滲速率呈非線性變化且隨時間的增加而減小;第二個階段,在分層界面以下入滲速率隨時間增加不變。濕潤鋒入滲深度隨時間增加的變化關(guān)系可以用y=axb形的冪函數(shù)進行表征。層狀包氣帶土剖面上含水率隨時間呈反“Z”字形變化,穩(wěn)定時的含水率接近土體的飽和含水率。(2)土體表層遭受高濃度氟瞬時污染后在15mm/12h降雨強度下,氟在由細及粗和由粗及細兩種分層結(jié)構(gòu)土體中運移時,隨著時間增加土柱各監(jiān)測點氟濃度先增加后減小,由于土壤顆粒的吸附作用兩種土體結(jié)構(gòu)峰值濃度隨時間和深度的增加逐漸降低。比較兩種土體結(jié)構(gòu),氟在由粗及細的土體結(jié)構(gòu)中運移快,試驗結(jié)束時由細及粗的層狀土中氟主要富集在土體上部,由粗及細層狀土中氟富集在土柱底部。因此在非飽和條件下由細及粗的層狀結(jié)構(gòu)對溶質(zhì)的阻滯作用強于由粗及細的層狀結(jié)構(gòu)。(3)當土柱表層遭受高濃度氟瞬時污染后在定水頭入滲和降雨入滲條件下,氟在相同分層方式的土柱中運移規(guī)律基本相同,濃度均隨時間先增大后減小,但在氟運移速率上有較大差異。氟運移受水分運移的影響,在定水頭入滲條件下土壤中水流速度快,對流作用使氟的運移速率也快,試驗結(jié)束時氟集中在土柱底部;在降雨入滲條件下氟運移受降雨強度的影響,土壤中水流速率慢,氟在土壤孔隙中向下運移速率慢,試驗結(jié)束時氟主要集中在土柱表層。(4)在同一降雨強度和同一分層方式下改變氟的供給方式,連續(xù)供給溶質(zhì)條件下隨著時間增加氟濃度先增大后趨于穩(wěn)定,試驗結(jié)束時氟在土柱中均勻分布,濃度與初始的供給濃度接近;瞬時供給溶質(zhì)條件下,由于降雨的淋溶作用,隨時間增加氟濃度先增大后減小,試驗結(jié)束時氟集中在土柱表層。(5)通過Hydrus-1D軟件對不同分層方式、定水頭高度和溶質(zhì)供給條件下,層狀土中氟的運移規(guī)律進行數(shù)值模擬。不同分層方式條件下層狀土中氟運移規(guī)律不同,表層土體介質(zhì)滲透性對溶質(zhì)的運移具有控制作用,表層土顆粒越細,對氟運移的阻滯作用越強,當表層土體相同時,第二層土中細顆粒越多對溶質(zhì)的阻滯作用強,因此細、中、粗的結(jié)構(gòu)對地下水污染物防治效果最好。不同定水頭高度條件下氟隨時間和深度的變化不大,水頭高度增加氟運移速率略有增大。相同質(zhì)量的溶質(zhì)分不同次數(shù)供給,供給次數(shù)越多表層土中出現(xiàn)的峰值個數(shù)越多,峰值濃度越低。(6)結(jié)合室內(nèi)土柱試驗和數(shù)值模擬,層狀包氣帶土中氟主要隨土體水分運動發(fā)生運移,不同分層方式、水分供給方式和溶質(zhì)供給方式都會不同程度的影響氟在層狀包氣帶土中的運移。
[Abstract]:The aeration zone is a complex system of soil particles, air and water at the same time. It plays an important role in the water cycle as an important link between the surface water, the atmospheric water and the groundwater, which is also an important link between the surface water, the atmospheric water and the groundwater. It is also a necessary channel for the surface solute to enter the ground water. The solute has a series of physics and chemistry in the process of migration with the soil. In nature, the layer soil is widely distributed in nature, and the study shows that the solute transport in the layered soil is much more complex than the homogeneous soil. As a typical pollutant in the groundwater, fluorine has an important influence on human health. Therefore, the study of the law of fluorine migration in the layered soil zone soil is heavy. In this paper, based on the experimental research on the transformation law of unsaturated solute transfer (project number: SKLGP2011Z001), based on the key subject of the National Key Laboratory of geological disaster prevention and geological environmental protection, the factors affecting the solute transport in the layered soil are analyzed, and the factors affecting the solute transport in the layered soil are analyzed. In order to make up for the limitation of the laboratory test in time, a variety of different stratification methods, different water head height and different solute supply conditions are applied to the fluorine in the layer under the indoor soil column test to study the movement of water and fluorine in the layer soil layer soil with different layers, water supply and solute supply. The main research results are as follows: (1) the migration of humid front in the layered soil is divided into two stages: the first stage, the infiltration rate above the stratified interface is nonlinear and decreases with the increase of time; the infiltration rate below the stratified interface increases with time in the second stage. The relationship between the depth of the infiltration depth and the time increased with time can be characterized by the power function of the y=axb shape. The water content on the layered soil profile shows a reverse "Z" shape change with time, and the water cut at the stable time is close to the saturated water content of the soil. (2) the soil surface is subjected to a high concentration of fluorine at the 15mm/12h rainfall intensity, and the fluorine is in the thin layer. The fluorine concentration increases first and then decreases with the increase of time and depth, and the peak concentration of two soil structures decreases with time and depth as the adsorption of soil particles increases. Compared to the two soil structures, the fluorine is moved quickly from the coarse and fine soil structure, and the test of fluorine is faster than two soil structures. At the end of the test, fluorine in the thin and coarse layered soil is mainly enriched in the upper part of the soil, and the fluorine is enriched at the bottom of the soil column in the coarse and fine layered soil. Therefore, under unsaturated conditions, the blocking effect of the thin and coarse layered structure on the solute is stronger than that of the coarse and fine layered structure. (3) when the surface of the soil column is subjected to a high concentration of fluorine, it is injected into the fixed water head. Under the conditions of infiltration and rainfall infiltration, the movement of fluorine in the same stratified soil column is basically the same, the concentration increases first and then decreases with time, but there is a great difference in the rate of fluorine migration. The flow of fluorine is influenced by the water migration, the flow rate of the soil is fast and the flow rate of the fluorine is fast under the condition of fixed water head infiltration. Fluorine is concentrated at the bottom of the soil column at the end of the soil. The flow rate of fluorine in the soil is slow and the rate of fluorine moves slowly down in the pore of soil under the condition of rainfall infiltration, and the fluorine is mainly concentrated on the surface of the soil column at the end of the experiment. (4) the supply of fluorine is changed under the same rainfall intensity and the same layer mode, and the solute is continuously supplied. Under the conditions, the fluorine concentration increased first and then stabilized, and the fluorine was evenly distributed in the soil column at the end of the test. The concentration of the fluorine was close to the initial supply concentration. The fluorine concentration increased first and then decreased with the leaching of the rain. The fluorine concentration was concentrated on the surface of the soil column at the end of the test. (5) through Hydrus-1D The movement of fluorine in layered soil under different stratification modes, fixed water head height and solute supply is simulated by software. The migration law of fluorine in layer soil under different stratification conditions is different. The permeability of surface soil medium has control effect on the transport of solute, the thinner the surface soil particles, the stronger the retardation of fluorine migration. When the surface soil is the same, the more fine particles in the second layers have strong blocking effect on the solute, so the fine, medium and coarse structures have the best effect on the prevention and control of the groundwater pollutants. The more the number of supply and supply times, the more peak values in the surface soil, the lower the peak concentration. (6) combined with the indoor soil column test and the numerical simulation, the fluorine in the layered soil and soil is mainly moved with the soil moisture movement, and the different stratification ways, the water supply mode and the solute supply mode will affect the fluorine in the stratified air zone in varying degrees. Movement in the soil.
【學位授予單位】：成都理工大學
【學位級別】：碩士
【學位授予年份】：2015
【分類號】：X53;X523

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