Laboratory measurements of small strain properties of dry sands by bender element

The S-wave and P-wave velocities in dry sands are simultaneously measured by a single pair of bender elements (BE) incorporated into a standard resonant column (RC) apparatus with a torsional shear (TS) function. The small strain properties, including shear modulus G₀, constrained modulus M₀ and Poisson's ratio υ, are determined for specimens at various densities and confining pressures. The results show that the G₀ values obtained from the BE tests agree well with those from RC and TS tests, indicating the reliability of the signal interpretation and the testing system. Furthermore, the G₀ data of the present test series is in good agreement with the data from the literature. The results also show that G₀ increases faster than M₀ as the soil density and the confining pressure increase. In terms of Poisson's ratio, it decreases with an increasing soil density and confining pressure and generally lies in the range of 0.18–0.32 for the tested sands. Empirical equations are established to approximately estimate Poisson's ratio from the measured G₀ or M₀ values.