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土-水特征曲线是指基质吸力与含水率或饱和度的关系曲线。土-水特征及其相关数学模型可用于非饱和土性质如渗透系数和抗剪强度模型的建立。通常,土-水特征曲线仅有脱湿曲线。笔者详细讨论了初始含水率、干密度、竖向应力及干湿循环对脱湿曲线的影响。采用滤纸法测试了厦门地区残积土的土-水特征曲线(SWCC)及滞回环。结果表明,初始含水率对SWCC影响较小,最优含水率干侧试样SWCC的进气值小,滞回环小;湿侧试样的进气值大,滞回环大;最优含水率试样的滞回环居中。初始干密度对SWCC有显著影响,低干密度试样SWCC进气值小,脱湿速率快;高干密度试样SWCC进气值高,脱湿速率低。滞回环的大小随着初始干密度的减小而增大。不同竖向应力下SWCC变化较大。随着竖向应力的增加,进气值增大,脱湿速率减小,滞回环减小并趋于稳定。第1次干湿循环对SWCC影响最大,随着循环次数的增加,进气值减小,滞回环减小并趋于稳定。由于残积砂质黏性土SWCC的过渡区和残余区不易区分,残余含水率难以确定,因此,提出5种剔除残余含水率参数的修正SWCC模型,计算分析得出,修正Gardner模型最适合厦门地区残积土的SWCC建模。
Soil-water characteristic curve refers to the matrix suction and moisture content or saturation curve. Soil-water features and their associated mathematical models can be used for the establishment of unsaturated soil properties such as permeability coefficient and shear strength model. Normally, the soil-water characteristic curve has only a desorption curve. The author discussed in detail the initial moisture content, dry density, vertical stress and wet-dry cycle on the desorption curve. Soil-water characteristic curve (SWCC) and hysteresis loop of residual soil in Xiamen area were tested by filter paper method. The results show that the initial moisture content has little effect on the SWCC. The SWCC with the best moisture content has a small inflow value and a small hysteresis loop. The inlet value of the wet side is large and the hysteresis loop is large. The optimum moisture content Hysteresis like the middle of the ring. The initial dry density had a significant effect on SWCC. The SWCC with low dry density had a small air inlet value and a fast dehumidification rate. The SWCC with high dry density had a high air intake and low dehumidification rate. The size of the hysteresis loop increases with decreasing initial dry density. SWCC changes greatly under different vertical stress. As the vertical stress increases, the air intake increases, the desorption rate decreases, the hysteresis loop decreases and tends to be stable. The first wet-dry cycle has the greatest influence on SWCC. As the number of cycles increases, the intake air value decreases and the hysteresis loop decreases and tends to be stable. As the transition zone and the residual zone of the residual sandy clay are not easy to distinguish, the residual moisture content is difficult to determine. Therefore, five modified SWCC models are proposed to remove the residual moisture content parameters. The calculated Gardner model is the most suitable for the Xiamen region SWCC modeling of residual soil.