Dynamic properties of sand from dry to fully saturated states

By using bender and extender elements test, the velocities of the primary and shear waves, V_p and V_s respectively, were measured for a sandy material by gradually varying the degree of saturation, S_r, between the dry and fully saturated states. The effect on the results of varying the relative density and effective confining pressure was also studied. The measurements clearly reveal that for a certain optimum S_r, which is around 0·7–0·9% for the chosen sand, the value of the shear modulus G reaches a maximum value, whereas the corresponding Poisson's ratio ν attains a minimum value. The values of the shear modulus corresponding to S_r ≈ 0% and S_r = 100% tend towards the same value. For values of Skempton's B parameter greater than 0·99, the values of V_p and ν rise very sharply to those of water. The predictions from Biot's theory with respect to the variation of V_p with S_r match well with the measured experimental data.