利用压力板法和饱和盐溶液蒸汽平衡法测试了广吸力范围内上海原状黏土的土水特性, 由吸力与饱和度关系曲线确定土样的进气值约为 580 kPa, 残余吸力值约为 13.8 MPa. 提出一种利用吸力与含水率关系, 并考虑脱湿过程中的变形后确定进气值和残余点的方法. 将此方法应用于上海原状黏土, 可确定其进气值约为 600 kPa, 残余吸力值约为 13 MPa, 与用吸力与饱和度关系曲线确定的值基本吻合. 对黏土土样在非饱和化过程中体积变化较大或者体变难以量测的情况, 可以利用该方法准确地确定进气值和残余点. 该方法简单实用, 避开了因试样体积量测不准确而影响其进气值和残余点的准确确定的问题.

A pressure plate method and vapor equilibrium technique with saturated salt solutions are used to investigate the water retention behavior of Shanghai soft clay in a wide suction range. From the relation between suction and degree of saturation, the air entry value is about 580 kPa and residual suction value is about 13.8 MPa for Shanghai soft clay layer. A method for determining air entry value using the relation between suction and water content is proposed, which is practical for the specimens with large volumetric shrinkage or deformation due to drying. Based on the deformation characteristics of the soil, the air entry value is about 600 kPa and residual suction value is about 13 MPa determined by using the above method, which is consistent with actual values. The air enter value and residual point of the specimens are determined with large volumetric shrinkage or deformation difficult to measure due to drying, as proposed by the water content versus suction relationship. This method can be used to avoid the effect of the volume measurement on the determinationof the air entry value and residual point.