非饱和土土水特征曲线(SWCC)测试与预测

非饱和土土水特征曲线(SWCC)表示了土中含水量与吸力之间的关系。文章介绍了6种常用方法,各有其适用范围。体积压力板仪可量测最大基质吸力值为1500kPa的干燥曲线和浸湿曲线;超过1500kPa时,可用盐溶液法进行量测;Tem-ple仪可量测基质吸力达100kPa的干燥曲线;滤纸法可用于测量土体的基质吸力与总吸力;Dew-point电位计可用于量测土样总吸力变化,尤其适合渗透吸力的量测;TDR探头适合于量测小于300kPa的基质吸力。用GDS非饱和土三轴仪可以进行SWCC测试,测试范围主要取决于陶土板的进气值。用准确的数学模型对测得的含水量、吸力数据进行拟合,对于预测非饱和土力学性质、渗透系数、抗剪强度及分析边坡稳定性有重要意义。由于准确测试SWCC难度较大,并且测试影响因素较多,所以根据土体孔隙大小分布和颗粒大小分布情况预测SWCC,也是一种较好的方法。

METHODS FOR TESTING AND PREDICTING OF SWCC IN UNSATURATED SOIL MECHANICS

Soil-water characteristic curve (SWCC) in unsaturated soil mechanics presents the relationship between water content and suction in the soil. The paper introduces six methods with their suitable application ranges. The volumetric pressure plate can measure the matric suction value of less than 1500kPa on wetting and drying SWCCs. The temple apparatus can measure matric suction range from 0 to 100kPa. Matric suction and total suction can be tested with filter paper. The dew-point potentiometer can be used to measure total suction, especially osmotic suction. The TDR probe is the same with matric suction less than 300kPa. The triaxial test system for GDS can be used to test SWCC. The test range lies on the air-entry value. It has a great significance for SWCC since it can be used in exact mathematic models to predict mechanics properties, coefficient of infiltration, shear strength and analysing stability of slope for unsaturated soil. It is very difficult to attain the curves accurately, which are affected by many additional factors . It is an alternative idea to predict SWCC with pore-size distribution and grain-size distribution.