mtluan @ dlut.edu.cn

The testing is employed to perform cyclic torsional shear test on hollow cylinder sample under isotropic consolidated condition with static and dynamic universal triaxial and torsional shear soil testing apparatus. The authors conducted three dynamic torsional with single sample achieving dynamic properties under three confining pressures with saturated clay and undisturbed silty clay. Special attention was paid to the maximum dynamic shear modulus Gmax and obtained from single sample of cyclic torsional shear test was basic approximated with traditional method of dynamic torsional test. Based on the test results and theoretical analysis, the confining pressure had a significant influence on the dynamic shear modulus and feeble influence on the dynamic damping ratio with the single sample method. It was also found that the G of two soils decreases when the confining pressure decreases from 400kPa to 100kPa and the decreasing gradient of G is less than the increasing gradient of G from 100kPa to 400kPa. The relation of G and ξ can be fitted by logarithm equations in this paper. Furthermore, this method can diminish the difference of the sample during experiment and effectively provide convenience with authentic experimental results