中文摘要：

以工程中常遇到的砂土和粉土为研究对象,对其进行土水特性试验和不同初始饱和度下的直剪试验,研究其土水特性和强度特性,重点研究其非饱和抗剪强度与饱和度间的关系。结果表明：在同一正应力下,非饱和状态的砂土和粉土的抗剪强度都随着饱和度的增大呈先增大后减小的变化,存在一个峰值;内摩擦角随着饱和度的变化不大,可视为常数。此外,根据实测的土水特征曲线,用平均骨架应力作为有效应力的强度算式对非饱和砂土和粉土的抗剪强度进行了预测,并与实测值进行对比,两者比较一致。

英文摘要：

Soil-water characteristic tests and direct shear tests were carried out for unsaturated sand and silt encountered commonly in engineering projects. The soil-water and strength characteristics of sand and silt were studied,focusing on the relationship between unsaturated shear strength and degree of saturation. The experimental results showed that at the same normal stress,with the increase of degree of saturation,the unsaturated shear strengths of sand and silt increased at first then decreased and there existed a peak strength. The friction angles of unsaturated sand and silt changed little with the increase of degree of saturation and could be considered constant. In addition,according to the measured soil-water characteristic curves,the strength equation with the average skeleton stress being equal to the effective stress for unsaturated soils was used to predict the shear strength of unsaturated sand and silt and the predicted results agreed well with measured values.