中文摘要：

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。

英文摘要：

The soil-water characteristic curve （SWCC） is defined as the relationship between the suction and the water content or degree of saturation. The soil-water characteristics and related mathematical models can be used to model the unsaturated soil properties such as the permeability and the shear strength. Conventionally, only the drying soil-water characteristic curve of soil is determined. In this work, the influences of initial water content, initial dry density, the vertical stress and drying and wetting cycles are examined and discussed in detail. The SWCCs and hysteresis loops of residual soils in Xiamen were obtained by the filter paper method. The results show that the initial water content has negligible effect on SWCCs. The specimen at the wet of optimum moisture content （OMC） has the higher air entry value and the larger hysteresis loop than that of the soil specimen at the dry of OMC. The specimen with OMC lies between them. While, the initial dry density has considerable influence on SWCCs. The specimen at lower initial dry density exhibits smaller air entry value and higher rate of desorption than that of the specimen at higher initial dry density. The size of hysteresis loop decreases as the initial dry density increases. The specimens subjected to different vertical stresses have different SWCCs. The higher the applied load on the specimen, the higher the air entry value, the higher the rate of desorption, the smaller the size of hysteresis loop. In the drying and wetting process, the size of hysteresis loop has been substantially affected by the first drying and wetting cycle. With the increasing of drying and wetting cycle, the air entry value and the size of hysteresis hoop decrease. Since the features of soil-water characteristic of sandy clay are not well defined especially for the residual state of saturation, which desaturates continuously without a distinct break point, the residual suction or residual water content, one of the key parameters in the mathematical models of SWCC, is no