干湿条件下压实粘土渗透系数的预测研究
发布时间：2019-02-22 14:59
【摘要】：压实粘土作为典型的非饱和土,因其易于施工且建设费用低,在防渗工程中常作为性能优良的防渗剂使用,军事工程中埋藏核废料也常采用压实粘土作为隔离材料。但是,在实践中其渗透性质难以确定,依据相关理论对非饱和土渗透特性参数作进一步的研究是很有必要的。基于此,本文结合国家自然科学基金面上项目(41072214)做了以下工作： (1)首先采用非饱和土联合测试系统,基于瞬时释放和吸入法(TRIM法),对于不同压实度下重塑粘土进行了干湿试验,根据数据采集系统Labview记录的大量数据、体积含水率与时间的关系曲线、初边值条件以及陶土板材料参数,运用一维水分运移过程分析软件HYDRUS-1D反算出水力特性参数θ(h)和K(h),进而得到非饱和土干湿土水特征曲线和渗透函数曲线,并分析了压实度对曲线的影响。 (2)其次对确定渗透函数的间接方法(即经验公式和统计模型法)进行了总结；介绍了根据土水特征曲线三参数模型BrooksCorey(1964)模型和Mualem(1976)相对渗透系数计算模型(简称BCM模型)计算压实粘土试样非饱和渗透系数kw的解析法,并对3种压实度粘土试样的非饱和渗透系数进行了预测；此外,还从预测原理、模型参数及获得方法、模型预测结果等方面与采用四参数模型Van Genuchten(1978)模型和Mualem(1976)相对渗透系数计算模型(简称VGM模型)的数值反演预测方法进行了对比,结果表明：两种模型预测得到的非饱和渗透系数非常接近。 (3)最后分析了6种压实度试样饱和渗透系数随压实度的变化规律,为后面讨论相对渗透系数奠定了基础：同时,从中选取3种压实度试样对其相对渗透系数随饱和度的变化规律进行了分析,有助于定性讨论相同干湿条件下压实度对相对渗透系数的影响。基于以上研究,根据干化阶段的试验数据推导了以饱和度S和压实度λ为自变量的归一化渗透函数表达式；并选取压实度为90.O%和77.8%试样湿化阶段的试验数据对表达式进行了验证。验证表明,实测渗透系数与预测渗透系数吻合度总体较好,推导出的考虑压实度变化的归一化渗透函数对压实粘土是适用的。
[Abstract]:Compacted clay, as a typical unsaturated soil, is often used as an impermeable agent in impervious engineering because of its ease of construction and low construction cost. Compacted clay is also often used as an isolation material in military engineering. However, the permeability of unsaturated soil is difficult to be determined in practice, and it is necessary to further study the permeability parameters of unsaturated soil based on relevant theory. Based on this, this paper has done the following work in combination with project (41072214) of the National Natural Science Foundation: (1) the unsaturated soil joint test system is adopted first, based on instantaneous release and inhalation (TRIM method), The dry and wet tests of remolded clay under different compaction degrees were carried out. According to a large number of data recorded by Labview data acquisition system, the relationship curve between volume moisture content and time, initial boundary value condition and clay plate material parameters were obtained. The hydraulic characteristic parameters 胃 (h) and K (h), were calculated by using one-dimensional water migration analysis software HYDRUS-1D, and the characteristic curves and permeability function curves of dry and wet soil were obtained, and the influence of compaction degree on the curves was analyzed. (2) secondly, the indirect method of determining osmotic function (i.e. empirical formula and statistical model method) is summarized. The analytical method for calculating unsaturated permeability coefficient (kw) of compacted clay samples based on BrooksCorey (1964) model and Mualem (1976) relative permeability model (BCM model) is introduced. The unsaturated permeability coefficients of three kinds of compactness clay samples were predicted. In addition, from the prediction principle, model parameters and methods of obtaining, The prediction results of the model are compared with the numerical inversion prediction method using the four-parameter model Van Genuchten (1978) and the Mualem (1976) relative permeability calculation model (VGM model). The results show that the unsaturated permeability coefficient predicted by the two models is very close. (3) at last, the variation of saturation permeability coefficient with compaction degree is analyzed, which lays a foundation for the discussion of relative permeability coefficient: at the same time, Three kinds of compactness samples are selected to analyze the change of relative permeability coefficient with saturation, which is helpful to discuss qualitatively the influence of compaction degree on relative permeability coefficient under the same dry and wet conditions. Based on the above research, the expression of normalized permeability function with saturation S and compactness 位 as independent variables is derived according to the test data of drying stage. The experimental data of the wetting stage of 90.O% and 77.8% samples were selected to verify the expression. The results show that the measured permeability coefficient is in good agreement with the predicted permeability coefficient, and the normalized permeability function, which takes into account the change of compaction degree, is suitable for compacted clay.
【学位授予单位】：武汉理工大学
【学位级别】：硕士
【学位授予年份】：2013
【分类号】：TU442
本文编号：2428337
[Abstract]:Compacted clay, as a typical unsaturated soil, is often used as an impermeable agent in impervious engineering because of its ease of construction and low construction cost. Compacted clay is also often used as an isolation material in military engineering. However, the permeability of unsaturated soil is difficult to be determined in practice, and it is necessary to further study the permeability parameters of unsaturated soil based on relevant theory. Based on this, this paper has done the following work in combination with project (41072214) of the National Natural Science Foundation: (1) the unsaturated soil joint test system is adopted first, based on instantaneous release and inhalation (TRIM method), The dry and wet tests of remolded clay under different compaction degrees were carried out. According to a large number of data recorded by Labview data acquisition system, the relationship curve between volume moisture content and time, initial boundary value condition and clay plate material parameters were obtained. The hydraulic characteristic parameters 胃 (h) and K (h), were calculated by using one-dimensional water migration analysis software HYDRUS-1D, and the characteristic curves and permeability function curves of dry and wet soil were obtained, and the influence of compaction degree on the curves was analyzed. (2) secondly, the indirect method of determining osmotic function (i.e. empirical formula and statistical model method) is summarized. The analytical method for calculating unsaturated permeability coefficient (kw) of compacted clay samples based on BrooksCorey (1964) model and Mualem (1976) relative permeability model (BCM model) is introduced. The unsaturated permeability coefficients of three kinds of compactness clay samples were predicted. In addition, from the prediction principle, model parameters and methods of obtaining, The prediction results of the model are compared with the numerical inversion prediction method using the four-parameter model Van Genuchten (1978) and the Mualem (1976) relative permeability calculation model (VGM model). The results show that the unsaturated permeability coefficient predicted by the two models is very close. (3) at last, the variation of saturation permeability coefficient with compaction degree is analyzed, which lays a foundation for the discussion of relative permeability coefficient: at the same time, Three kinds of compactness samples are selected to analyze the change of relative permeability coefficient with saturation, which is helpful to discuss qualitatively the influence of compaction degree on relative permeability coefficient under the same dry and wet conditions. Based on the above research, the expression of normalized permeability function with saturation S and compactness 位 as independent variables is derived according to the test data of drying stage. The experimental data of the wetting stage of 90.O% and 77.8% samples were selected to verify the expression. The results show that the measured permeability coefficient is in good agreement with the predicted permeability coefficient, and the normalized permeability function, which takes into account the change of compaction degree, is suitable for compacted clay.
【学位授予单位】：武汉理工大学
【学位级别】：硕士
【学位授予年份】：2013
【分类号】：TU442
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