The aim of the study is to seek a simple and inexpensive method to prevent the permeability rise of unsaturated clay caused by evaporation process and to raise its imperviousness. Taking Chengdu clay as an example, fo...The aim of the study is to seek a simple and inexpensive method to prevent the permeability rise of unsaturated clay caused by evaporation process and to raise its imperviousness. Taking Chengdu clay as an example, four treatment schemes were tried. Na 2CO 3 could reduce conspicuously the permeability of the saturated clay, but could not limit the permeability rise in the alternate wetting and drying process. NaOH had a similar effect to Na 2CO 3. NaCl could not only decrease the saturated hydraulic conductivity, but could also effectively contain the permeability rise caused by evaporation. CH 3COONa had a similar effect to NaCl. The mechanism of Na 2CO 3, NaOH, NaCl and CH 3COONa decreasing the saturated hydraulic conductivity of the clay is that Na + transformed Ca montmorillonites in the original clay into Na montmorillonites and the transformation reduces the sizes of effective pores and the effective porosity of the clay.展开更多
The establishment of energy balance equation is necessary to study the thermo-mechanical properties of unsaturated soils.To solve this equation,the determination of two fundamental parameters as volumetric specific pa...The establishment of energy balance equation is necessary to study the thermo-mechanical properties of unsaturated soils.To solve this equation,the determination of two fundamental parameters as volumetric specific parameter and thermal conductivity coefficient is essential.In this paper,the effective thermal conductivity coefficient of dry soil grain is analyzed for soils with different compositions,and the thermo-mechanical properties of porous media with water and gas are studied by considering the soil water retention curve（SWRC）.Different methods,i.e.volumetric average method,self-consistent method,Hashin-Strikman method,are employed to calculate thermal conductivity coefficients,and a new method is proposed to determine the thermo-mechanical parameters.Comparison of the results obtained by different methods shows that the proposed method is in a good agreement with the experimental results and is suitable for describing the main properties of the thermo-mechanical behaviors of soils.The relationship between the SWRC and the seepage curve is further studied by the natural proportional rule.The characteristics of the SWRC,its differential coefficient and the seepage curve,are investigated by considering the physico-mechanical mechanism;the limit scopes of the indices of the SWRC and the seepage curve are also given.展开更多
文摘The aim of the study is to seek a simple and inexpensive method to prevent the permeability rise of unsaturated clay caused by evaporation process and to raise its imperviousness. Taking Chengdu clay as an example, four treatment schemes were tried. Na 2CO 3 could reduce conspicuously the permeability of the saturated clay, but could not limit the permeability rise in the alternate wetting and drying process. NaOH had a similar effect to Na 2CO 3. NaCl could not only decrease the saturated hydraulic conductivity, but could also effectively contain the permeability rise caused by evaporation. CH 3COONa had a similar effect to NaCl. The mechanism of Na 2CO 3, NaOH, NaCl and CH 3COONa decreasing the saturated hydraulic conductivity of the clay is that Na + transformed Ca montmorillonites in the original clay into Na montmorillonites and the transformation reduces the sizes of effective pores and the effective porosity of the clay.
基金Supported by the National Natural Science Foundation of China(50779030,50879044,2008BAB29B03)the National Defenses Bureau(838)
文摘The establishment of energy balance equation is necessary to study the thermo-mechanical properties of unsaturated soils.To solve this equation,the determination of two fundamental parameters as volumetric specific parameter and thermal conductivity coefficient is essential.In this paper,the effective thermal conductivity coefficient of dry soil grain is analyzed for soils with different compositions,and the thermo-mechanical properties of porous media with water and gas are studied by considering the soil water retention curve（SWRC）.Different methods,i.e.volumetric average method,self-consistent method,Hashin-Strikman method,are employed to calculate thermal conductivity coefficients,and a new method is proposed to determine the thermo-mechanical parameters.Comparison of the results obtained by different methods shows that the proposed method is in a good agreement with the experimental results and is suitable for describing the main properties of the thermo-mechanical behaviors of soils.The relationship between the SWRC and the seepage curve is further studied by the natural proportional rule.The characteristics of the SWRC,its differential coefficient and the seepage curve,are investigated by considering the physico-mechanical mechanism;the limit scopes of the indices of the SWRC and the seepage curve are also given.
