基于TRIM方法的膨胀土非饱和渗透行为研究

发布时间：2018-07-27 13:36

【摘要】：随着理论研究的深入以及过程实践的发展,非饱和渗流问题在岩土工程与环境岩土工程中受到了越来越多的重视,而非饱和渗透系数是非饱和渗流分析的必要环节。目前,非饱和渗透系数已在测试方法、模型建立和影响因素等方面得到了深入研究。但是,密实程度与水力路径对非饱和渗透系数的影响规律与机制尚不明确。本文以荆门弱膨胀土为研究对象,采用室内试验、理论分析与数值模拟的方法研究密实程度与水力路径对压实膨胀土非饱和渗透系数的影响规律,在此基础上,模拟降雨入渗与蒸发行为,主要研究内容与成果如下:(1)通过变水头渗透试验,获得了孔隙比在工程尺度范围内的荆门弱膨胀土饱和渗透系数的变动规律,在此基础上,选用指数函数描述饱和渗透系数与孔隙比的关系,取得了较好的拟合效果。(2)采用TRIM方法,测得6种不同密实程度下荆门弱膨胀土的瞬态排水量与时间的函数关系,并以此函数关系作为目标函数,根据试验的初始、边界条件,结合数值模拟方法求解Richards方程。通过Hydrus-1D反演模拟,获得6种密实程度试样脱吸湿路径下的土水特征曲线、非饱和渗透系数函数和吸应力曲线。(3)结果表明:随着密实程度增大,试样的进气值增大,持水能力增强,非饱和渗透系数减小,吸应力变化越范围增大。不同水力路径下,土水特征曲线、吸应力曲线以及相对渗透系数曲线,呈现出明显的水力滞回效应。非饱和渗透函数用体积含水率表达时,滞回效应并不显著,但是当用吸力表达非饱和渗透函数时,体现出较明显的滞回效应。(4)基于反演结果,分析密实程度与水力路径对VG模型参数α、n的影响,构建了VG模型参数α、n与土体密度、水力路径相关关系的数学描述。(5)在Hydrus-1D程序中,采用不同密实程度与水力路径下试样的VG模型参数,模拟降雨入渗与蒸发行为。明确了密实程度与水力路径对降雨入渗与蒸发过程的影响规律。
[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 伪 n of VG model, a mathematical description of the correlation between the parameter 伪 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.
【学位授予单位】：信阳师范学院
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TU443

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