本文選題：非飽和黃土 + 滲流��； 參考：《長(zhǎng)安大學(xué)》2016年碩士論文

【摘要】：野外調(diào)查表明,黃土地區(qū)地下水位一般高于臨河水位,地下水沒有臨近河流水源的補(bǔ)給,因此大氣降水(局部灌溉)成為黃土地區(qū)地下水僅有的補(bǔ)給來(lái)源。通過(guò)天然降雨剖面、人工降雨剖面、灌溉剖面觀測(cè)不同深度的含水率,發(fā)現(xiàn)地表水在黃土中的浸潤(rùn)深度有限,難以到達(dá)地下水位,因此黃土中的地表水是如何運(yùn)移并補(bǔ)給地下水是人類一直感興趣的課題。本文擬通過(guò)現(xiàn)場(chǎng)觀測(cè)和試驗(yàn)的方法,揭示降雨在非飽和黃土中入滲規(guī)律及補(bǔ)給地下水的機(jī)理。考慮到以往試驗(yàn)觀測(cè)深度小、時(shí)間短,且降雨在黃土中的入滲規(guī)律和影響深度尚不明確。本文在甘肅省正寧縣設(shè)立監(jiān)測(cè)站,開挖一口深96.0m,直徑1.0m觀測(cè)井,用以監(jiān)測(cè)黃土塬區(qū)地表水入滲補(bǔ)給地下水的完整過(guò)程。地面設(shè)置雨量計(jì)、氣壓計(jì)、空氣溫度計(jì)及空氣濕度計(jì);井壁插入土壤水分計(jì);井底水位面以下設(shè)置水位計(jì)。結(jié)果顯示:降雨引起土體含水率增大,最大浸潤(rùn)深度不超過(guò)4.0m;降雨量越大,土壤含水率增幅越大,含水率增大的響應(yīng)時(shí)間越快,影響深度越大,隨著深度增加,增幅減小,時(shí)間上漸有滯后;非飽和黃土中,水分入滲主要以非飽和滲流或水汽形式遷移;地下水位受氣壓的影響明顯,和當(dāng)前降雨無(wú)明顯聯(lián)系。針對(duì)現(xiàn)場(chǎng)監(jiān)測(cè)得出的規(guī)律,在室內(nèi)做了一個(gè)小型土柱模型試驗(yàn),取塬邊L1馬蘭黃土,人工加水模擬降雨,測(cè)量加水過(guò)程中含水率與基質(zhì)吸力的隨時(shí)間的變化。通過(guò)測(cè)得的含水率與基質(zhì)吸力,結(jié)合黃土中應(yīng)用最廣泛的Gardner、van Genuchten和FredlundXing三種理論模型擬合試驗(yàn)數(shù)據(jù),得到重塑馬蘭黃土的土水特征曲線,結(jié)果表明FredlundXing模型的擬合度最高。馬蘭黃土重塑樣中,濕潤(rùn)鋒掃過(guò)的土壤含水率不變,最大值與飽和含水率的比值為0.74。同時(shí),基于非飽和理論建立監(jiān)測(cè)井和土柱試驗(yàn)?zāi)Ｐ?利用Geo-Studio軟件結(jié)合試驗(yàn)測(cè)得的土水特征曲線及滲透性曲線,模擬降雨和土柱試驗(yàn)中水在黃土中的入滲過(guò)程。模擬結(jié)果與現(xiàn)場(chǎng)監(jiān)測(cè)結(jié)果、室內(nèi)試驗(yàn)結(jié)果相吻合。說(shuō)明水在黃土中的滲流屬于非飽和滲流,對(duì)非飽和滲流理論在實(shí)際工程中的應(yīng)用提供了依據(jù)。
[Abstract]:The field investigation shows that the groundwater level in loess area is generally higher than that in the adjacent river, and there is no recharge of groundwater near the river source, so the atmospheric precipitation (local irrigation) is the only source of groundwater recharge in loess area. Through the observation of water content at different depths through natural rainfall section, artificial rainfall section and irrigation section, it is found that the infiltration depth of surface water in loess is limited and it is difficult to reach the groundwater level. Therefore, how the surface water in loess is transported and recharged is a subject of human interest. This paper intends to reveal the infiltration law of rainfall in unsaturated loess and the mechanism of recharge of groundwater by means of field observation and test. Considering the small depth and short time, the infiltration law and influence depth of rainfall in loess are not clear. In this paper, a monitoring station was set up in Zhengning County, Gansu Province, and an observation well with a depth of 96.0m and a diameter of 1.0m was excavated to monitor the complete process of surface water infiltration and recharge of groundwater in the Loess Plateau. Set rain gauge, barometer, air thermometer and air hygrometer on the ground; insert well wall into soil moisture meter; set water level meter below bottom water level. The results show that the soil moisture content increases and the maximum wetting depth is not more than 4.0 m, the larger the rainfall, the larger the increase of soil moisture content, the faster the response time of water content increase, the greater the influence depth, and the smaller the increase with the increase of soil moisture content. In the unsaturated loess, the water infiltration is mainly in the form of unsaturated seepage or water vapor, and the groundwater level is obviously affected by the pressure, and has no obvious relation with the current rainfall. A small soil column model test was carried out in the laboratory according to the law obtained by field monitoring. The L _ 1 Ma Lan loess was taken from the edge of the tableland to simulate rainfall with artificial water, and the variation of water content and matrix suction with time was measured. The soil-water characteristic curve of remolded Ma Lan loess was obtained by combining the measured moisture content and the suction of matrix, combined with the experimental data fitted by the most widely used three theoretical models of Gardnervan Genuchten and FredlundXing in loess. The results show that the FredlundXing model has the highest fitting degree. In the remolded Ma Lan loess, the moisture content of the soil swept by the wetting front was unchanged, and the ratio of the maximum value to the saturated moisture content was 0.74. At the same time, the model of monitoring well and soil column test is established based on unsaturated theory. The infiltration process of water in loess is simulated by combining the characteristic curve of soil and water and permeability curve measured by Geo-Studio software. The simulation results are in good agreement with the field monitoring results. It shows that the seepage of water in loess belongs to unsaturated seepage, which provides the basis for the application of unsaturated seepage theory in practical engineering.
【學(xué)位授予單位】：長(zhǎng)安大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2016
【分類號(hào)】：TU411.4

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