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膨胀土在吸水时会产生体积膨胀,研究湿胀条件下膨胀土的土-水特征具有重要意义。以合肥地区9种弱膨胀土为研究对象,采用滤纸法和渗析法试验测定了膨胀土的土-水特征,采用蒸汽加湿法试验测定了膨胀土在吸湿过程中的体积变化。基于土-水特征曲线(SWCC)试验及加湿试验,获得了膨胀土在吸湿过程中的体积变化规律,得到了湿胀条件下膨胀土的重力含水率-基质吸力曲线(w-ψ曲线)及体积含水率-基质吸力曲线(θw3-ψ曲线),分析了膨胀土吸湿过程中的体积变化对体积含水率-基质吸力曲线的影响,探讨了w-ψ与θw3-ψ曲线拟合参数的变异性及参数间的相关性。结果表明:蒸汽法加湿土样是一种较为理想的增湿方式;湿胀条件下,w-ψ曲线与考虑体变的θw3-ψ曲线的差异程度与吸湿结束后的土样含水率有关;w-ψ曲线的变异性小于θw3-ψ曲线的变异性;拟合参数n的变异性小于参数a及m的变异性;w-ψ曲线及θw3-ψ曲线的对应拟合参数间呈线性关系。
Expansive soil will produce volume expansion when absorbing water. It is of great significance to study the characteristics of soil-water expansive soil under wetting conditions. Taking 9 kinds of weak expansive soils in Hefei as the research object, the soil-water characteristics of expansive soil were determined by filter paper method and dialysis method. The volume change of expansive soil during moisture absorption was measured by steam humidification test. Based on the soil-water characteristic curve (SWCC) test and the humidification test, the volume change law of expansive soils during moisture absorption was obtained, and the gravitational moisture content-matrix suction curve (w-ψ curve) Volumetric water content-matrix suction curve (θw3-ψ curve), the influence of the volume change of the expansive soil moisture on the volumetric water content-matrix suction curve was analyzed, and the variation of fitting parameters of w-ψ and θw3-ψ curves was discussed Sex and the correlation between parameters. The results show that steam humidification is an ideal humidifying method. Under wetting conditions, the difference between w-ψ curve and θw3-ψ curve considering volume change is related to soil moisture content after moisture absorption. The variability of w-ψ curve is less than that of θw3-ψ curve; the variability of fitting parameter n is less than the variability of parameters a and m; and the corresponding fitting parameters of w-ψ curve and θw3-ψ curve show a linear relationship .