Dynamic shear modulus of saturated Nanjing fine sand in large scale shaking table tests

In order to investigate the dynamic shear modulus of saturated sand during the increasing and dissipating stages of dynamic pore water pressure (PWP), large-scale shaking table tests on saturated Nanjing fine sand are carried out. Based on test data, the significance of reasonable choice of the threshold values of low and high frequencies with band-pass filter is analyzed to obtain the displacement from acceleration by double integration. Moreover, an approach to obtain the dynamic shear modulus from the acceleration time-history relationship is established. By analyzing the relationships among the dynamic shear modulus ratio, the cycle number of loading, the PWP ratio and the shear strain amplitudes during the increasing and dissipating stages of PWP, the following results are obtained: (1) since the dynamic shear modulus during the dissipating stage of PWP is significantly smaller than that during the increasing stage, it is unreasonable to take the dynamic shear modulus during the two stages as the same; (2) the decay rate of dynamic shear modulus with the increase of the shear strain amplitude obtained from large-scale shaking table tests for saturated Nanjing fine sand is faster than that obtained from cyclic triaxial tests, in laboratory.