發(fā)布時間：2018-07-27 13:36

【摘要】：隨著理論研究的深入以及過程實踐的發(fā)展,非飽和滲流問題在巖土工程與環(huán)境巖土工程中受到了越來越多的重視,而非飽和滲透系數(shù)是非飽和滲流分析的必要環(huán)節(jié)。目前,非飽和滲透系數(shù)已在測試方法、模型建立和影響因素等方面得到了深入研究。但是,密實程度與水力路徑對非飽和滲透系數(shù)的影響規(guī)律與機制尚不明確。本文以荊門弱膨脹土為研究對象,采用室內(nèi)試驗、理論分析與數(shù)值模擬的方法研究密實程度與水力路徑對壓實膨脹土非飽和滲透系數(shù)的影響規(guī)律,在此基礎上,模擬降雨入滲與蒸發(fā)行為,主要研究內(nèi)容與成果如下:(1)通過變水頭滲透試驗,獲得了孔隙比在工程尺度范圍內(nèi)的荊門弱膨脹土飽和滲透系數(shù)的變動規(guī)律,在此基礎上,選用指數(shù)函數(shù)描述飽和滲透系數(shù)與孔隙比的關系,取得了較好的擬合效果。(2)采用TRIM方法,測得6種不同密實程度下荊門弱膨脹土的瞬態(tài)排水量與時間的函數(shù)關系,并以此函數(shù)關系作為目標函數(shù),根據(jù)試驗的初始、邊界條件,結合數(shù)值模擬方法求解Richards方程。通過Hydrus-1D反演模擬,獲得6種密實程度試樣脫吸濕路徑下的土水特征曲線、非飽和滲透系數(shù)函數(shù)和吸應力曲線。(3)結果表明:隨著密實程度增大,試樣的進氣值增大,持水能力增強,非飽和滲透系數(shù)減小,吸應力變化越范圍增大。不同水力路徑下,土水特征曲線、吸應力曲線以及相對滲透系數(shù)曲線,呈現(xiàn)出明顯的水力滯回效應。非飽和滲透函數(shù)用體積含水率表達時,滯回效應并不顯著,但是當用吸力表達非飽和滲透函數(shù)時,體現(xiàn)出較明顯的滯回效應。(4)基于反演結果,分析密實程度與水力路徑對VG模型參數(shù)α、n的影響,構建了VG模型參數(shù)α、n與土體密度、水力路徑相關關系的數(shù)學描述。(5)在Hydrus-1D程序中,采用不同密實程度與水力路徑下試樣的VG模型參數(shù),模擬降雨入滲與蒸發(fā)行為。明確了密實程度與水力路徑對降雨入滲與蒸發(fā)過程的影響規(guī)律。
[Abstract]:With the development of theoretical research and process practice, unsaturated seepage problem has been paid more and more attention in geotechnical engineering and environmental geotechnical engineering, and unsaturated permeability coefficient is a necessary link in unsaturated seepage analysis. At present, unsaturated permeability coefficient has been deeply studied in testing methods, modeling and influencing factors. However, the influence of density and hydraulic path on unsaturated permeability is unclear. In this paper, the influence of density and hydraulic path on unsaturated permeability coefficient of compacted expansive soil is studied by laboratory test, theoretical analysis and numerical simulation, taking Jingmen weakly expansive soil as the research object, and on the basis of which, the influence of density degree and hydraulic path on unsaturated permeability coefficient of compacted expansive soil is studied. The main research contents and results of simulating rainfall infiltration and evaporation behavior are as follows: (1) the variation of saturated permeability coefficient of Jingmen weakly expansive soil with void ratio in engineering scale is obtained through the permeability test with variable head. The exponential function is used to describe the relationship between saturation permeability coefficient and porosity ratio. (2) by using TRIM method, the function relationship between transient displacement and time of Jingmen weakly expansive soil is obtained by using TRIM method. According to the initial and boundary conditions of the experiment and the numerical simulation method, the Richards equation is solved by using the function relation as the objective function. Through Hydrus-1D inversion simulation, the soil-water characteristic curve, unsaturated permeability coefficient function and absorption stress curve under desorption path of 6 kinds of dense degree samples are obtained. (3) the results show that the inlet air value of the sample increases with the increase of compaction degree. With the increase of water holding capacity, the unsaturated permeability coefficient decreases, and the variation of absorption stress increases. Under different hydraulic paths, the characteristic curve of soil and water, the curve of absorbing stress and the curve of relative permeability coefficient show obvious hydraulic hysteretic effect. The hysteretic effect is not significant when the unsaturated permeation function is expressed by volume water content, but the hysteretic effect is obvious when the unsaturated permeation function is expressed by suction. (4) based on the inversion results, Based on the analysis of the influence of density degree and hydraulic path on the parameter 偽 n of VG model, a mathematical description of the correlation between the parameter 偽 n of VG model and soil mass density and hydraulic path is established. (5) in Hydrus-1D program, The VG model parameters of samples with different compactness and hydraulic path were used to simulate rainfall infiltration and evaporation behavior. The influence of density degree and hydraulic path on rainfall infiltration and evaporation process is clarified.
【學位授予單位】：信陽師范學院
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：TU443

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本文編號：2147997