Abstract: A series of resonant column tests was carried out on undisturbed silty clay and silt in the same borehole from surface to bedrock in the estuary of the Yangtze River. Then the variation law of dynamic shear modulus G with soil depth H was explored within various strain ranges in the same undisturbed soil. It was found that the G in the various strain ranges of undisturbed silty clay and silt increased regularly with the increase of H. Meanwhile, the maximum dynamic shear modulus Gmax linearly increased with the increase of H, whereas the attenuation relationship of G decreased with the increase of H. The experimental results showed that the G of the undisturbed soil was correlated with the soil depth H. Based on the soil depth H and Hardin model, the G prediction method was put forward accordingly to predict the Gmax of each kind of undisturbed soil at different depths and their G within various strain ranges. According to the comparison and analysis of three kinds of G prediction methods, the G prediction method based on soil depth H was the most advantageous. In addition, the applicability of the method was further verified by re-processing the data of undisturbed marine soil in Bohai sea area.

Key words: undisturbed silty clay, undisturbed silt, dynamic shear modulus, soil depth, Hardin model, prediction method