Soil-water characteristics of Gaomiaozi(GMZ)Ca-bentonite at high suctions(3–287MPa)are measured by vapour equilibrium technique.The soil-water retention curve(SWRC)of samples with the same initial compaction states i...Soil-water characteristics of Gaomiaozi(GMZ)Ca-bentonite at high suctions(3–287MPa)are measured by vapour equilibrium technique.The soil-water retention curve(SWRC)of samples with the same initial compaction states is obtained in drying and wetting process.At high suctions,the hysteresis behaviour is not obvious in relationship between water content and suction,while the opposite holds between degree of saturation and suction.The suction variation can change its water retention behaviour and void ratio.Moreover,changes of void ratio can bring about changes in degree of saturation.Therefore,the total change in degree of saturation includes changes caused by suction and that by void ratio.In the space of degree of saturation and suction,the SWRC at constant void ratio shifts to the direction of higher suctions with decreasing void ratio.However,the relationship between water content and suction is less affected by changes of void ratio.The degree of saturation decreases approximately linearly with increasing void ratio at a constant suction.Moreover,the slope of the line decreases with increasing suction and they show an approximately linear relationship in semi-logarithmical scale.From this linear relationship,the variation of degree of saturation caused by the change in void ratio can be obtained.Correspondingly,SWRC at a constant void ratio can be determined from SWRC at different void ratios.展开更多
The China-mock-up test is to evaluate the performance of the compacted Gaomiaozi （GMZ） bentonite under coupled thermo-hydro-mechanical （THM） conditions in deep geological disposal. A numerical study of the test is...The China-mock-up test is to evaluate the performance of the compacted Gaomiaozi （GMZ） bentonite under coupled thermo-hydro-mechanical （THM） conditions in deep geological disposal. A numerical study of the test is conducted in this paper. The principal THM characteristics of the bentonite are presented at first. A THM model is then presented to tackle the complex coupling behavior of the bentonite. The model of Alonso-Gens is incorporated to reproduce the mechanical behavior of the bentonite under unsaturated conditions. With the proposed model, numerical simulations of the China-mock-up test are carried out by using the code of LAGAMINE. The time variations associated with the temperature, degree of saturation, suction and swelling pressure of the compacted bentonite are studied. The results suggest that the proposed model is able to reproduce the mechanical behavior of the bentonite, and to predict moisture motion under coupled THM conditions.展开更多
In this paper, with K＋, Ca2＋ and Fe3＋ as the objects of study, retardation of soil-bentonite （SB） barrier materials for metal ions with different valences is investigated, and the adsorption mechanism, migration ...In this paper, with K＋, Ca2＋ and Fe3＋ as the objects of study, retardation of soil-bentonite （SB） barrier materials for metal ions with different valences is investigated, and the adsorption mechanism, migration patterns and permeation behavior are explored so as to provide a theoretical basis for their application. The results show that the adsorption process for metal ions with different valences by SB barrier materials is fast, and the higher the valence, the greater the adsorption capacity. The fitting of the adsorption process conforms to pseudo-second-order adsorption kinetics and Langmuir-Freundlich adsorption equation, which explains that chemical adsorption is the dominating state and that the SB surface has certain heterogeneity. The permeability coefficient of K＋, Ca2＋ and Fe3＋ in SB each has a maximum and the higher the valence, the sooner the maximum appears. Also the higher the valence, the more obvious the effect on SB retardation performance; and the sooner the ion breaks through the barrier wall completely, that is, the wall＇s retardation performance for higher valent ions may decline.展开更多
在土水特征测定试验的基础上,分析了历史上提出的各种模拟土水特征曲线的方程与试验结果的拟合程度。在非饱和渗透系数试验结果的基础上,分析了由分维理论得到的非饱和渗透系数模拟方程与试验结果的拟合程度。得出以下结论:Fredlund and...在土水特征测定试验的基础上,分析了历史上提出的各种模拟土水特征曲线的方程与试验结果的拟合程度。在非饱和渗透系数试验结果的基础上,分析了由分维理论得到的非饱和渗透系数模拟方程与试验结果的拟合程度。得出以下结论:Fredlund and Xing土水特征曲线方程对于试验结果有较好的模拟效果;Brooks和Corey土水特征曲线方程与试验结果的曲线形状更为接近,但在模拟接近309MPa的吸力段的土水曲线时与试验结果有偏差。分维理论的修正公式能更好模拟非饱和渗透系数。展开更多
基金the National Natural Sciences Foundation of China (No. 41102163)
文摘Soil-water characteristics of Gaomiaozi(GMZ)Ca-bentonite at high suctions(3–287MPa)are measured by vapour equilibrium technique.The soil-water retention curve(SWRC)of samples with the same initial compaction states is obtained in drying and wetting process.At high suctions,the hysteresis behaviour is not obvious in relationship between water content and suction,while the opposite holds between degree of saturation and suction.The suction variation can change its water retention behaviour and void ratio.Moreover,changes of void ratio can bring about changes in degree of saturation.Therefore,the total change in degree of saturation includes changes caused by suction and that by void ratio.In the space of degree of saturation and suction,the SWRC at constant void ratio shifts to the direction of higher suctions with decreasing void ratio.However,the relationship between water content and suction is less affected by changes of void ratio.The degree of saturation decreases approximately linearly with increasing void ratio at a constant suction.Moreover,the slope of the line decreases with increasing suction and they show an approximately linear relationship in semi-logarithmical scale.From this linear relationship,the variation of degree of saturation caused by the change in void ratio can be obtained.Correspondingly,SWRC at a constant void ratio can be determined from SWRC at different void ratios.
文摘The China-mock-up test is to evaluate the performance of the compacted Gaomiaozi （GMZ） bentonite under coupled thermo-hydro-mechanical （THM） conditions in deep geological disposal. A numerical study of the test is conducted in this paper. The principal THM characteristics of the bentonite are presented at first. A THM model is then presented to tackle the complex coupling behavior of the bentonite. The model of Alonso-Gens is incorporated to reproduce the mechanical behavior of the bentonite under unsaturated conditions. With the proposed model, numerical simulations of the China-mock-up test are carried out by using the code of LAGAMINE. The time variations associated with the temperature, degree of saturation, suction and swelling pressure of the compacted bentonite are studied. The results suggest that the proposed model is able to reproduce the mechanical behavior of the bentonite, and to predict moisture motion under coupled THM conditions.
基金supported by Public Welfare Special Research of National Environmental Protection of China (No. 201309004)
文摘In this paper, with K＋, Ca2＋ and Fe3＋ as the objects of study, retardation of soil-bentonite （SB） barrier materials for metal ions with different valences is investigated, and the adsorption mechanism, migration patterns and permeation behavior are explored so as to provide a theoretical basis for their application. The results show that the adsorption process for metal ions with different valences by SB barrier materials is fast, and the higher the valence, the greater the adsorption capacity. The fitting of the adsorption process conforms to pseudo-second-order adsorption kinetics and Langmuir-Freundlich adsorption equation, which explains that chemical adsorption is the dominating state and that the SB surface has certain heterogeneity. The permeability coefficient of K＋, Ca2＋ and Fe3＋ in SB each has a maximum and the higher the valence, the sooner the maximum appears. Also the higher the valence, the more obvious the effect on SB retardation performance; and the sooner the ion breaks through the barrier wall completely, that is, the wall＇s retardation performance for higher valent ions may decline.
文摘在土水特征测定试验的基础上,分析了历史上提出的各种模拟土水特征曲线的方程与试验结果的拟合程度。在非饱和渗透系数试验结果的基础上,分析了由分维理论得到的非饱和渗透系数模拟方程与试验结果的拟合程度。得出以下结论:Fredlund and Xing土水特征曲线方程对于试验结果有较好的模拟效果;Brooks和Corey土水特征曲线方程与试验结果的曲线形状更为接近,但在模拟接近309MPa的吸力段的土水曲线时与试验结果有偏差。分维理论的修正公式能更好模拟非饱和渗透系数。
