Abstract: Dynamic deformations of unsaturated silt have been tested using a suction controllable dynamic triaxial testing apparatus. The skeleton curve, dynamic elastic modulus, damping ratio were obtained at different net confining pressures and suction paths. The effect of drying and wetting cycle on dynamic deformation characteristics of unsaturated silt was studied. Test results show that at the same net confining pressure and suction, the skeleton curve and dynamic elastic modulus of silty specimens subjected to drying and then wetting are higher than that of the specimens subjected to drying path only. but the damping ratio of specimens under drying and then wetting is lower under drying path only. With increasing the maximum suction experienced, the skeleton curve and dynamic elastic modulus of unsaturated silt increase, and oppositely the damping ratio decreases. The test results can be explained by the average skeleton stress and the effect of surface tension of meniscus water, which are together used to predict the maximum shear modulus of unsaturated soil.

Key words: dynamic deformation characteristic, suction-controlled dynamic triaxial test, unsaturated soil, suction history, prediction